Note: Descriptions are shown in the official language in which they were submitted.
POWER BOOST REGULATOR
FIELD OF THE DISCLOSURE
[0001-3] The present disclosure relates to power generation systems of a
vehicle and more particularly to a power boost regulator configured to provide
load-
matched voltage operation.
BACKGROUND
[0004] Electrical power requirements in recreational vehicles, including
Off
Road Vehicles, ATVs, snowmobiles, etc., continue to rise as a consequence of
increasing electrical loads. Growing electrical power requirements are driving
the
need for increased power output from the magneto or alternator charging
systems
that serve as the core of a vehicle's electrical system. Traditionally,
magneto size
has been scaled to meet increasing electrical power demands, which results in
increased cost.
[0005] The power generation systems of many vehicles operate at a fixed
load
voltage. A load voltage is selected and the charging system is operated at
this
voltage throughout the RPM range. Such a system results in reduced power at
low
and high engine speeds and causes the charging system to compromise between
power needed at high engine speeds and power needed for engine
starting/idling.
For example, FIG. 5 illustrates an exemplary power curve 104 showing exemplary
power provided by a conventional power generation system over a range of
engine
speeds. Curve 104 depicts that the conventional power generator compromises on
power available at low and/or high engine speeds due to the fixed load voltage
constraint and fails to capitalize on maximum power output at low and high
engine
speeds. In addition, some engines, such as air-cooled engines of snowmobiles
for
example, are prone to overheating when large currents are produced by the
magneto to provide the required vehicle power at the fixed load voltage.
[0006] Some vehicles, such as snowmobiles or other recreational vehicles,
include a manual start system, such as a recoil start or a kick start system,
for
starting the engine of the vehicle. The power requirements for controlling the
engine
start-up are often difficult to achieve with a manual start. For example, the
low
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Date Recue/Date Received 2020-08-31
engine speeds initiated by the manual pull are often insufficient to generate
sufficient
power for the engine control unit, thereby forcing multiple manual start
attempts by
the rider.
[0007] Some recreational vehicles include a plow or other work tool that is
driven by a winch or other electric machine that draws power from the power
generation system. The engine speed may not be sufficient to maintain proper
power levels to other loads while the electric machine draws power during the
plow
operation. For example, the battery charge level may not be sufficiently
maintained
during plowing as a result of the current draw by the plow.
SUMMARY
[0008] The present disclosure provides a power boost regulator operative to
harness larger amounts of power from a magneto. In some embodiments, the
regulator utilizes low loss field effect transistors (FETs) to implement
switching
transformations to allow for load matched voltage operation at the stator
throughout
the entire RPM range. For example, the power boost regulator induces a desired
voltage/current combination at the stator for each engine speed to provide the
demanded electrical load. In some embodiments, this allows for an increase in
power output from a given stator without requiring alteration to the stator or
flywheel.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a diagrammatical view of an exemplary vehicle control
system
of the present disclosure including a power boost regulator;
[0010] FIG. 2 is a left front perspective view of a vehicle, illustratively
a
snowmobile, incorporating the power boost regulator of FIG. 1;
[0011] FIG. 3 is a representative view of exemplary stages of the power
boost
regulator of FIG. 1 including an input stage, a DC/DC converter stage, and an
output
stage;
[0012] FIG. 4 is a representative view of exemplary configurations of the
power boost regulator of FIG. 1;
[0013] FIG. 5 is a graph illustrating a conventional power curve and a
power
curve provided with the power boost regulator of FIG. 1 over an engine speed
range
according to some embodiments;
[0014] FIG. 6 is a graph illustrating power versus voltage curves for a
plurality
of different engine speeds provided by the power boost regulator of FIG. 1
according
to some embodiments;
[0015] FIG. 7 is a diagrammatical view of inputs and outputs of an
electronic
controller for controlling the power boost regulator of FIG. 1 according to
some
embodiments;
[0016] FIG. 8 is a flow diagram illustrating an exemplary method of
operation
of the electronic controller of FIGS. 1 and 7;
[0017] FIG. 9 is a flow diagram illustrating an exemplary detailed method
of
operation of the electronic controller of FIGS. 1 and 7;
[0018] FIG. 10 is a graph illustrating exemplary operating regions of the
power
boost regulator of FIG. 1 including operating regions to the left and right of
the peak
power point;
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[0019] FIGS. 11A-B is a schematic view of an exemplary power boost
regulator including a boost rectifier stage, a buck converter stage, and a
power/current steering stage;
[0020] FIG. 110 is a schematic view of another exemplary power boost
regulator including a boost rectifier stage and a power/current steering
stage;
[0021] FIG. 11D is a schematic view of another exemplary power boost
regulator including a boost rectifier stage and a power/current steering
stage;
[0022] FIG. 12 is a diagrammatical view of exemplary electrical loads of
the
system of FIG. 1 for power distribution by the power/current steering stage of
FIGS.
11A-B;
[0023] FIGS. 13A-B is a schematic view of another exemplary power boost
regulator including a shunt regulator stage and an interleaved buck converter
stage;
[0024] FIG. 14 illustrates an exemplary single phase shunt regulator
according
to an embodiment;
[0025] FIG. 15 illustrates an exemplary three-phase shunt regulator
according
to an embodiment;
[0026] FIG. 16 illustrates an exemplary control scheme for the shunt
regulators of FIGS. 14 and 15;
[0027] FIG. 17 is a perspective view of an engine according to an
embodiment
including a power generation assembly;
[0028] FIG. 18 is a partially exploded perspective view of the power
generation assembly of FIG. 17 including a housing, a shroud, and a magneto
and
starter assembly;
[0029] FIG. 19 is an exploded back perspective view of the housing and
shroud of FIG. 18;
[0030] FIG. 20 is a cross-sectional view of the power generation assembly
of
FIG. 17 taken along lines 4-4 of FIG. 17;
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[0031] FIG. 21 is a back perspective view of the assembled crankcase and
power generation assembly of FIG. 17;
[0032] FIG. 22 is a back perspective view of the housing, the shroud, and
the
recoil starter of FIG. 18;
[0033] FIG. 23A is a schematic view of a magnet pole;
[0034] FIG. 23B is a schematic view of a segmented magnet pole;
[0035] FIG. 24 is a graph showing exemplary voltage output for a power
boost
regulator;
[0036] FIG. 25 is a flowchart showing operations performed to assess health
of capacitors of the power boost regulator;
[0037] FIG. 26 is a schematic view of an exemplary start-up circuit;
[0038] FIG. 27 is a flow chart showing operation of a battery relay;
[0039] FIG. 28 is a schematic view showing operation of power output
prioritization;
[0040] FIG. 29 is a schematic view showing operation of a power boost
regulator able to call for cooling;
[0041] FIG. 30 is a perspective partially-cut-away view of a flywheel
usable
with the engine of FIG 17;
[0042] FIG. 31 illustrates an exemplary voltage monitoring system.
[0043] Corresponding reference characters indicate corresponding parts
throughout the several views. The exemplification set out herein illustrates
embodiments of the invention, and such exemplifications are not to be
construed as
limiting the scope of the invention in any manner.
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DETAILED DESCRIPTION OF THE DRAWINGS
[0044] The embodiments disclosed herein are not intended to be exhaustive
or limit the disclosure to the precise forms disclosed in the following
detailed
description. Rather, the embodiments are chosen and described so that others
skilled in the art may utilize their teachings.
[0045] The term "logic" or "control logic" as used herein may include
software
and/or firmware executing on one or more programmable processors, application-
specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs),
digital
signal processors (DSPs), hardwired logic, or combinations thereof. Therefore,
in
accordance with the embodiments, various logic may be implemented in any
appropriate fashion and would remain in accordance with the embodiments herein
disclosed.
[0046] Referring initially to FIG. 1, an illustrative embodiment of a
vehicle
control system 10 includes an electronic controller 12, an engine 16, a
transmission
18, and an AC power source 22 driven by engine 16. A power boost regulator 24
in
communication with electronic controller 12 is operative to control the
generation and
delivery of power provided by power source 22, as described herein. AC power
source 22, power boost regulator 24, and electronic controller 12 provide a
power
generation system 21 for the vehicle.
[0047] Electronic controller 12 receives a plurality of inputs and controls
a
plurality of output devices of the vehicle. For example, controller 12 is
operative to
output an electrical signal indicative of a throttle percentage to an actuator
of throttle
17 to control a position of the throttle valve for regulating air intake and
controlling
engine speed. In one embodiment, the throttle opening percentage is based at
least
in part on the detected position of accelerator 34 actuated by the rider.
Accelerator
34, which includes a position sensor, may be an accelerator pedal, a thumb
actuated
lever, a twist grip, or any other suitable operator input device that, when
actuated by
an operator, is configured to provide an operator throttle demand to
controller 12. A
throttle valve position sensor provides feedback to controller 12 indicative
of the
actual position or degree of opening of throttle 17. Additional details of
electronic
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throttle control provided with controller 12 is disclosed in U.S. Patent
Application
Publication No. 2011/0297462, entitled ELECTRONIC THROTTLE CONTROL.
[0048] In some embodiments, controller 12 receives signals from position
sensor(s) of a user-operated brake 36 identifying a brake demand and controls
the
vehicle brakes (if equipped) based on the brake demand. The vehicle may
alternatively include mechanically (e.g., cable) controlled brakes and/or
throttle. A
mode input device 32 provides a signal to controller 12 representative of a
mode of
operation (e.g., normal, plow, generation, performance, etc.) of the vehicle.
Control
system 10 includes a battery 14 providing voltage and/or state of charge
feedback to
controller 12, although in other embodiments the vehicle may be batteryless.
[0049] Controller 12 includes one or more processors 13 that execute
software and/or firmware code stored in internal or external memory 15 of
controller
12. The software/firmware code contains instructions that, when executed by
the
one or more processors 13 of controller 12, causes controller 12 to perform
the
vehicle functions described herein. Controller 12 may alternatively include
one or
more application-specific integrated circuits (ASICs), field-programmable gate
arrays
(FPGAs), digital signal processors (DSPs), hardwired logic, or combinations
thereof.
Controller 12 may include one or more physical control modules in
communication
with one another. For example, controller 12 may include one or more of an
engine
control unit (ECU), a vehicle control unit (VCU), a transmission control unit
(TCU),
and/or other suitable control modules operating to control the functionality
of the
vehicle.
[0050] Memory 15 is any suitable computer readable medium that is
accessible by the processor(s) 13 of controller 12. Memory 15 may be a single
storage device or multiple storage devices, may be located internally or
externally to
controller 12, and may include both volatile and non-volatile media. Exemplary
memory 15 includes random-access memory (RAM), read-only memory (ROM),
electrically erasable programmable ROM (EEPROM), flash memory, CD-ROM,
Digital Versatile Disk (DVD) or other optical disk storage, a magnetic storage
device,
or any other suitable medium which is configured to store data and which is
accessible by controller 12.
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[0051] Transmission 18 illustratively includes an electronically controlled
continuously variable transmission (eCVT), although other transmission types
may
be provided. Electronic controller 12 provides a clutch angle control signal
to eCVT
18 to control the transmission gear ratio. Additional details of the control
and
operation of eCVT 18 are disclosed in U.S. Patent No. 8,682,550, entitled
PRIMARY
CLUTCH ELECTRONIC CVT.
[0052] Power source 22 provides alternating current (AC) power for use by
various components and systems of the vehicle. In the illustrated embodiment,
power source 22 includes a magneto or alternator (e.g., magneto 524 of FIG.
18)
coupled to the output of engine 16. Engine 16 drives power source 22 to
generate
the AC power regulated by power boost regulator 24.
[0053] Power boost regulator 24 is operative to control the generation and
delivery of power provided by power source 22. Power boost regulator 24
includes
an AC-DC converter operative to convert the AC generated power from power
source 22 to DC power deliverable to electrical loads 38. As described herein,
power boost regulator 24 is operative to provide load matched voltage
operation by
inducing in the stator a voltage and current to achieve a target power output
for each
engine speed. Further, power boost regulator 24 is operative to selectively
direct
power to different electrical loads 38 based on the available power and a
power
distribution priority, as described herein. Illustrative electrical loads 38
include
system loads 26, critical loads 28, and chassis loads 30. System loads 26
include
one or more electronic control units of the vehicle, such as the engine
control unit
(ECU) of controller 12, for example, for controlling engine operation such as
fuel
injection and ignition. Critical loads 28 include critical components for
engine
operation such as the fuel pump, oil pump, and electrical valve actuator
(e.g., throttle
valve actuator, etc.). Chassis loads 30 include, for example, vehicle lights,
a battery
charging system, air conditioning, panel instrumentation, electrically
operated
handwarmers, and other suitable non-critical loads.
[0054] Referring to FIG. 2, an exemplary vehicle incorporating control
system
of FIG. 1 is illustrated in the form of a snowmobile 50. Other suitable
vehicles
may incorporate control system 10. Snowmobile 50 of FIG. 2 includes a chassis
or
frame 52 having a front frame portion 52a and a rear frame portion 52b. A body
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Date Recue/Date Received 2020-08-31
assembly 54 generally surrounds at least front frame portion 52a of frame 52.
Front
frame portion 52a is supported by front ground-engaging members,
illustratively skis
56, and rear frame portion 52b is supported by a rear ground-engaging member,
illustratively an endless track 58. The rider uses a steering assembly 60,
which is
operably coupled to at least skis 56, to control the direction of snowmobile
50. A
seat assembly 62 is provided generally rearward of steering assembly 60 and is
configured to support the rider.
[0055] Front skis 56 are operably coupled to a front suspension assembly
64,
and endless track 58 cooperates with a rear suspension assembly 66. A
powertrain
assembly is positioned generally intermediate front suspension assembly 64 and
rear suspension assembly 66, and provides power to endless track 58 to move
snowmobile 50. For example, the powertrain assembly includes engine 16 and
transmission 18 of FIG. 1 and at least one drive shaft. Additional details of
snowmobile 50 are disclosed in U.S. Patent No. 9,096,289, U.S. Patent No.
9,506,407, U.S. Patent No. 10,358,187, U.S. Provisional Patent Application
Serial
No. 61,513,949, and U.S. Provisional Patent Application Serial No. 61/582,426,
all of
which are publicly available.
[0056] Referring to FIG. 3, a system level diagram of power boost regulator
24
of FIG. 1 is illustrated. Power boost regulator 24 implements closed loop
control to
induce a load matched voltage in the stator of power source 22, i.e., a
voltage and
current in the stator corresponding to a stator power output suitable for the
load.
Power boost regulator 24 illustratively includes an input portion or stage 80,
a DC/DC
conversion stage 82, and an output stage 84. In the illustrated embodiment,
input
stage 80 includes an AC-DC rectifier and boost converter circuit, conversion
stage
82 includes a DC/DC buck converter circuit, and output stage 84 includes a
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Date Recue/Date Received 2020-08-31
power/current distribution circuit, such as a current steering circuit as
described
herein or another suitable distribution circuit. In another embodiment, power
boost
regulator 24 includes only input stage 80 and output stage 84 and does not
include
DC/DC conversion stage 82.
[0057] FIG. 4 includes a chart 70 illustrating three different
configurations 72
of power boost regulator 24 including a boost configuration, a boost-buck
configuration, and a boost-interleaved buck configuration. In each
configuration,
power boost regulator 24 includes a boost rectifier circuit as input stage 80
that
includes an AC-DC rectifier and a boost converter. In the boost configuration,
power
boost regulator 24 does not include a DC-DC converter stage 82 and includes a
current steering circuit as the output stage 84. In the boost-buck
configuration,
power boost regulator 24 includes a step-down buck converter circuit as DC/DC
stage 82 and a current steering circuit as output stage 84. In the boost-
interleaved
buck configuration, power boost regulator 24 includes interleaved buck
converter
circuit as DC/DC stage 82 and a single output circuit as output stage 84.
Alternatively, the boost-interleaved buck configuration may include a current
steering
circuit as the output stage 84. An exemplary boost rectifier circuit 304, step
down
buck converter circuit 306, and current steering circuit 308 are illustrated
in FIGS.
11A-B and described herein. An exemplary interleaved buck converter circuit
356
and single output circuit 358 are illustrated in FIGS. 13A-B and described
herein.
[0058] FIG. 5 is a graph 100 illustrating two exemplary power curves 102,
104
versus engine speed (RPM). Power curve 102 illustrates exemplary maximum
power in Watts (W) that AC power source 22 is operative to generate over a
range of
engine speeds as controlled by power boost regulator 24. Curve 104 illustrates
the
maximum power that a conventional generation system is able to provide over
the
same range of engine speeds due to operation at a fixed system load voltage
(e.g.,
16V). As illustrated in FIG. 5, power boost regulator 24 of FIG. 1 is
operative to
capture and store additional energy at low engine speeds, illustratively
speeds
between zero RPM and 1200 RPM, as well as at high engine speeds,
illustratively
speeds greater than 1500 RPM. While an exemplary speed range of 2000 RPM is
illustrated in FIG. 5, other suitable speed ranges may be provided depending
on
engine type and configuration. Accordingly, power boost regulator 24 serves to
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increase the available electrical power across a larger range or an entire
range of
engine speeds as compared to the conventional AC/DC rectifier. In an
embodiment
with engine having a manual start (e.g., pull-start, kick-start, etc.), the
likelihood of
the engine starting after a single pull or kick on the recoil starter is
improved due to
the availability of power at lower engine speeds.
[0059] Referring to FIG. 6, a graph 110 illustrates exemplary power (W)
versus voltage (V) curves generated by AC power source 22 of FIG. 1 as
controlled
by power boost regulator 24 of FIG. 1 for a subset of engine speeds (RPM).
Curve
112 represents generated power at 200 RPM, curve 114 represents generated
power at 500 RPM, curve 116 represents generated power at 800 RPM, curve 118
represents generated power at 1200 RPM, curve 120 represents generated power
at
1500 RPM, curve 122 represents generated power at 2000 RPM, and curve 124
represents generated power at 2500 RPM. As illustrated, the output power
varies for
a given engine speed based on the output voltage. In the illustrated
embodiment,
there is a single peak power point at each engine speed. In particular, at
each
engine speed there is an output voltage at which a maximum output power is
achieved, and the voltage is not the same for every engine speed. As such, in
one
embodiment, power deliverable by AC power source 22 is maximized for a single
load matched output voltage at each engine speed. In one embodiment, the
different peak power points are achieved due to high armature leakage
inductance of
AC power source 22 that results in a large DC-side output impedance of power
boost
regulator 24, thereby causing the power deliverable by AC power source 22 at a
given engine speed to be maximized for a single load-matched output voltage.
Accordingly, power boost regulator 24 is capable of performing load matched
voltage
operation and adjusting its operating voltage to allow for maximum power
production
at each engine speed.
[0060] An exemplary maximum power curve 126 of FIG. 6 intersects each
peak power point of power curves 112-124 for the illustrated engine speeds,
while
maximum power curve 102 of FIG. 5 illustrates exemplary maximum power points
for
all engine speeds. Maximum power curves 126 (FIG. 6) and 102 (FIG. 5) thereby
illustrate the additional power that is available for capture and storage
across the
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engine speed range as compared to a conventional power generator depicted by
curve 104 of FIG. 5.
[0061] At each engine speed, there is also an output voltage above which
the
output current (and therefore output power) of AC power source 22 becomes
zero,
referred to herein as the open circuit current. In some embodiments, this
output
voltage for each engine speed corresponds to the peak of the line-to-line emf
voltage
above which rectification diodes of power boost regulator 24 do not conduct
electricity. The curves of FIGS. 5 and 6 are exemplary curves according to one
embodiment. Different embodiments of power boost regulator 24 may provide
different shaped curves depending on the configuration of power boost
regulator 24
and the AC power source 22.
[0062] FIG. 7 illustrates an electronic controller 128, illustratively a
microcontroller 128, for controlling power boost regulator 24 of FIG. 1. In
one
embodiment, microcontroller 128 is a component of electronic controller 12 of
FIG. 1
and communicates with the ECU and other control unit(s) of electronic
controller 12
(e.g., via CAN or other communication protocol). Microcontroller 128
illustratively
includes power boost regulator control logic 130 operative to perform control
functionality for power boost regulator 24. Microcontroller 128 determines the
stator
current based on feedback signals from at least one current sensor 142 at the
stator
of AC power source 22. Microcontroller 128 determines the system voltage,
i.e., the
voltage available at the output of power boost regulator 24 for use by
electrical loads,
based on feedback signals from at least one voltage sensor 144. In one
embodiment, voltage sensor 144 is positioned external to power boost regulator
24
and monitors a voltage input to a first electrical load of a plurality of
electrical loads
38 of the vehicle. In one example, the first electrical load is the highest
priority load
receiving power from power boost regulator 24 based on the available power and
a
power distribution priority. An exemplary voltage monitoring system is
depicted in
FIG. 31 and discussed in more detail herein. Returning to FIG. 7, the measured
stator current and measured system voltage are provided as input to control
logic
130. Control logic 130 also receives as input a target system voltage 141,
which is a
constant predetermined value representing the required load voltage.
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[0063] Microcontroller 128 calculates the engine speed (RPM) 134 based on
output from an engine speed sensor 132. In the illustrated embodiment, sensor
132
provides a signal indicative of the zero voltage crossing of each phase of the
three-
phase magneto (e.g., AC power source 22 of FIG. 1), and microcontroller 128
calculates engine speed 134 based on the zero voltage crossing information. In
one
embodiment, based on the engine speed 134, microcontroller 128 accesses a
magneto data lookup table 136 stored in memory 15 (FIG. 1) to determine a
corresponding current value 138 for maximum power for the measured engine
speed
and a short circuit current value 140 for the measured engine speed. In
particular,
value 138 is the current level at which AC power source 22 outputs a maximum
power for that engine speed. Short circuit current value 140 is the current
level at
which the stator power goes to zero. Power boost regulator control logic 130
receives as input the maximum power current value 138 and short circuit
current
value 140 and controls power boost regulator 24 based on these values. Based
on
the inputs including target voltage 141, max power current 138, short circuit
current
140, measured stator current 142, and measured system voltage 144, control
logic
130 provides a control output to drive boost rectifier circuit 80 (FIGS. 3 and
4) of
power boost regulator 24 such that AC power source 22 (FIG. 1) generates power
at
the desired voltage and current levels. In the illustrated embodiment,
microcontroller
128 includes an internal or external pulse width modulation (PWM) generator
150
that receives a duty cycle command from control logic 130 and thereby outputs
a
drive signal 152 to drive boost rectifier circuit 80.
[0064] In one embodiment, magneto data lookup table 136 is unique to the
type and model of AC power source 22 installed in the vehicle. Magneto data
lookup table 136 comprises data identifying the power characteristics of AC
power
source 22 (FIG. 1) of the vehicle for all or multiple engine speeds. For
example,
lookup table 136 contains current, voltage, and power values corresponding to
an
entire engine speed range or to a plurality of engine speeds in the range. In
one
embodiment with lookup table 136 containing power characteristics for a
plurality,
but not all, engine speeds, controller 12 selects an engine speed available in
table
136 that is closest to the measured engine speed for determining the power
characteristics. For example, if the measured engine speed is 2250 RPM, and
lookup table 136 contains power characteristics for engine speeds of 2150 RPM
and
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2300 RPM, controller 12 selects 2300 RPM as the "measured" engine speed for
purposes of determining the maximum power current 138 and short circuit
current
140 of FIG. 7.
[0065] Referring still to FIG. 7, in one embodiment output control logic
156
receives voltage inputs 146 comprising the measured voltages at each
electrical load
or for each electrical load group (e.g., system loads 26, critical loads 28,
chassis
loads 30 of FIG. 1) of the electrical system. For example, output control
logic 156
may receive these inputs when power boost regulator 24 includes the current
steering circuit for output stage 84 (FIGS. 3 and 4). In this embodiment,
output
control logic 156 provides a control output 154 for driving output stage 84
(FIG. 3) to
distribute the power based on the priority of the electrical loads, as
described herein.
In one embodiment, output 154 is generated by an internal or external PWM
generator 158 and includes a pulse width modulation (PWM) / gate drive signal
for
driving MOSFETs of the current steering circuit.
[0066] Referring to FIG. 8, a flow diagram 170 illustrates a control
method of
microcontroller 128 of FIG. 7 for controlling power boost regulator 24
according to an
illustrative embodiment. At blocks 172 and 174, microcontroller 128 uses data
from
magneto lookup table 136 for the measured engine speed to set minimum and
maximum current limits of the stator of AC power source 22 (FIG. 1), as
described in
greater detail herein with respect to FIGS. 9 and 10. At block 180, control
logic 130
controls the system voltage, i.e., the load voltage output by power boost
regulator
24, with proportional-integral (PI) control based on inputs including the
minimum/maximum current limits and the target voltage and measured system
voltage (block 176). Control logic 130 further controls the stator current at
block 186
with proportional-integral (PI) control based on the target stator current and
the
measured stator current (block 184). Microcontroller 128 drives the boost
rectifier
circuit 80 (FIGS. 3 and 4) of power boost regulator 24 to the system voltage
and
stator current determined at blocks 180, 186 using a pulse width modulation
signal
(block 188) having an appropriate duty cycle and frequency (e.g., via PWM
generator 150 of FIG. 7).
[0067] Referring to FIG. 9, a flow diagram 200 illustrates a detailed
control
method performed by microcontroller 128 of FIG. 7 for controlling power boost
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regulator 24 according to some embodiments. In the illustrated embodiment,
when
the power generation system does not operate at the maximum or peak power
point,
microcontroller 128 is capable of driving power boost regulator 24 to control
AC
power source 22 (FIG. 1) at one of two operating conditions for each engine
speed,
referred to herein as left side control strategy and right side control
strategy. FIG. 10
illustrates an exemplary power versus voltage curve 234 and a current versus
voltage curve 232 for a given engine speed. For any power level (other than
maximum power point 236) at the given engine speed, power boost regulator 24
is
capable of controlling the output power of AC power source 22 in two different
operating points or conditions, including a first voltage/current combination
in left
side control region 244 (i.e., left of the peak power point 236) and a second
voltage/current combination in the right side control region 246. For example,
for a
power level P1, control logic 130 is operative to control power boost
regulator 24
such that the output power P1 of AC power source 22 is achieved with a first
voltage
V1 and current 11 combination or a second voltage V2 and current 12
combination. V1,
li is in the left side control region 244 and operates at a lower voltage and
a higher
current, while V2, 12 is in the right side control region 246 and thereby
operates at a
higher voltage and a lower current.
[0068] Control logic 130 of microcontroller 128 determines which region
244,
246 to operate in based on a number of factors. In the illustrated embodiment,
power boost regulator 24 normally operates in right-side region 246 as long as
hardware limits are not reached. In one embodiment, hardware limits include
maximum voltage thresholds of hardware components. For example, an exemplary
maximum operating voltage of MOSFET devices may be about 80 volts. When a
hardware limit is reached during right-side region 246 control, power boost
regulator
24 is operative to switch operation to left-side region 244. In the
illustrated
embodiment, operation in right-side region 246 results in lower stator
temperature
and lower internal temperature of power boost regulator 24 due to lower
current
levels as compared to operation in left-side region 244.
[0069] In one embodiment, power boost regulator 24 operates in left-side
region 244 during startup, idle, and low engine speed conditions and switches
over
to right-side control region 246 after the engine speed crosses a speed
threshold. In
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this embodiment, the higher currents and lower voltages in the left-side
control
region 244 drive the power boost circuit for starting the engine and
maintaining
suitable power levels during low engine speeds. The engine speed threshold is
based at least in part on the stator and flywheel design. An exemplary engine
speed
threshold in one engine configuration is about 1600 to 1700 RPM, although
other
suitable thresholds may be provided based on engine design.
[0070] In another embodiment, power boost regulator 24 may normally
operate in the left side region 244 in certain configurations, such as in the
boost (no
buck) configuration or the boost-interleaved buck configuration of FIG. 4.
[0071] In an alternative implementation wherein power boost regulator 24
does not include a DC/DC conversion stage 82, the number of stator winding
turns of
AC power source 22 and the output voltage level of AC power source 22 are
selected such that the stator open-circuit voltage is always at or below the
output
voltage level, thereby allowing continuous operation on the right-side region
246 of
the stator power curve of FIG. 10 without requiring DC-DC conversion stage 82.
[0072] In the illustrated embodiment, operation in the left side region
244
results in lower voltages and higher currents, while operation in right side
region 246
results in higher voltages and lower currents for the same power output. In
one
embodiment, operation in right side region 246 results in lower heat
generation in AC
power source 22 due to lower stator currents. In one embodiment, operation in
right
side region 246 results in less shunting and lower generator braking torque on
the
engine. Control logic 130 is operative to switch between operation regions
244, 246
for each configuration of power boost regulator 24 based on voltage/current
limits,
other hardware limits, and/or temperature limits being reached. For example,
if
operating in the left side region 244 and the stator or engine temperature
exceeds a
temperature threshold, control logic 130 is operative to switch to right side
region
246 to reduce the stator current while maintaining the same power output,
thereby
reducing heat generation by the stator. Similarly, if operating in right side
region 246
and hardware limits are reached, control logic 130 is operative to switch to
left side
region 244 while maintaining the same power output.
- 16 -
CA 3021812 2018-10-23
[0073] When power boost regulator 24 operates in left side control region
244
of FIG. 10, the minimum current level is set (block 174 of FIG. 8) to the
current at
maximum power 238 for the given engine speed, and the maximum current level
(block 174 of FIG. 8) is set to the short circuit current level 240 for the
given engine
speed. When power boost regulator 24 operates in right side control region
246, the
minimum current level is set to zero (open circuit current), and the maximum
current
level is set to the current at maximum power 238 for the given engine speed.
[0074] In method 200 of FIG. 9, control logic 130 determines a voltage
error at
204 based on the difference between the target system (load) voltage 202 and
the
measured system (load) voltage 206. In one embodiment, the target system
voltage
is fixed and based on the electrical loads. At block 212, control logic 130
commands
a target stator voltage via PI control based on the voltage error and the
minimum and
maximum current levels determined at block 174 of FIG. 8. In particular, the
currents
from lookup table 136 corresponding to the min/max current levels for the
measured
engine speed are used as the lower and upper current limits of PI control 212.
Control logic 130 at 214 determines the target stator current based on the
target
stator voltage (i.e., current = power/voltage) and the maximum current level.
The
maximum current level input to block 214 is the short circuit current when
operating
in left side control region 244 of FIG. 10 and the maximum power current when
operating in the right side control region 246 of FIG. 10, as described
herein. At
block 216, control logic 130 determines a current error based on the
difference
between the measured current 218 and the target stator current and commands
the
stator target current using PI control. In the illustrated embodiment, the
target stator
voltage and target stator current are commanded using a pulse width modulation
generator as described herein.
[0075] In the illustrated embodiment, power boost regulator 24 is
configured to
operate in a plurality of different modes selectable by a user with mode input
device
32 of FIG. 1. Referring to FIG. 1, mode input device 32, which may be provided
on
an instrument cluster, provides a discrete or CAN input signal to electronic
controller
12 indicative of the selected mode. One exemplary mode is a plow mode of
operation. The plow mode may be used during a work operation of the vehicle,
such
as when plowing and/or hauling snow, earth, or other material, due to the
additional
- 17 -
CA 3021812 2018-10-23
power drawn by the electrical actuator of the plow or work tool. In the plow
mode,
controller 12 monitors the output voltage and battery charge output percentage
of
power boost regulator 24 and controls the fuel to injectors 20, the throttle
opening
percentage, and the clutch control angle of eCVT 18 to achieve higher engine
speeds at idle and low vehicle speeds. For example, when the vehicle is idling
or
moving a low speeds below a predetermined speed threshold in the plow mode,
controller 12 speeds up engine 16 and adjusts the transmission ratio
accordingly to
maintain the proper vehicle speed. The higher engine speed results in
additional
power output by AC power source 22. In the plow mode, electronic controller 12
communicates a target charging output percentage to power boost regulator 24
(e.g.,
for charging the vehicle battery) and retrieves or receives the actual
charging output
percentage from power boost regulator 24. Controller 12 then adjusts the
engine
speed to provide the required power to achieve the target charging output
percentage. For example, if controller 12 calls for 100% charging output and
the
battery voltage is not at the desired voltage, controller 12 increases the
engine RPM
such that the battery may be charged to the proper level during the work
operation.
[0076] Another
exemplary mode of operation of power boost regulator 24 is a
performance mode. In the performance mode, controller 12 operates power boost
regulator 24 to improve the performance (e.g., acceleration) of the vehicle by
reducing the load on engine 16 during periods of high acceleration and/or high
engine speeds. In one embodiment, electronic controller 12 controls power
boost
regulator 24 to draw less current from AC power source 22 in response to
detecting
an acceleration that exceeds a threshold and/or an engine speed that exceeds a
threshold. Power boost regulator 24 achieves the reduced current draw by doing
one or more of the following: reducing the output voltage on the non-critical
output
loads (e.g., chassis loads 30 of FIG. 1) via the current steering circuit,
removing the
output voltage from the chassis loads 30 for an adjustable period of time via
the
current steering circuit, and/or drawing the power from AC power source 22 at
a
higher voltage and a smaller current (e.g., switching to operation at right
side region
246 of FIG. 10). Other suitable modes of operation may be selected and
implemented with power boost regulator 24.
- 18 -
CA 3021812 2018-10-23
[0077] FIGS. 11A-B illustrates a circuit-level view of an exemplary power
boost regulator 300 according to an illustrative embodiment. Power boost
regulator
300 includes control circuitry 314 for controlling operation of power boost
regulator
300, including MOSFETs Q1-Q11. In the illustrated embodiment, control
circuitry
314 includes microcontroller 128 of FIG. 7 that controls functionality of and
measures
characteristics of power boost regulator 300. Control circuitry 314 further
includes
voltage dividers for feedback signals, current measurement circuits,
temperature
measurement circuits, magneto phase level signal detectors, and other suitable
control circuitry, such as the input/output devices illustrated in FIG. 7. An
exemplary
boost rectifier circuit 304 corresponding to input stage 80 of FIG. 3 is
coupled to the
output of a three-phase stator 302 of AC power source 22 (FIG. 1). Boost
rectifier
304 includes a bridge rectifier comprising MOSFET devices Q1-Q6 driven by
controller 12 (e.g., PWM generator 150 of FIG. 7) for causing stator 302 to
see its
RPM dependent load matched voltage and to produce the target power levels at
the
desired voltage and current combinations. Resistors R2, R3 are coupled in
series
with the three phase output of stator 302 for measuring inductor current of
stator
302, and another current sensing resister R1 is coupled at the output of boost
rectifier 304. In one embodiment, MOSFET devices Q1-Q11 of power boost
regulator 300 of FIGS. 11A-B are low loss switching MOSFETs.
[0078] Power boost regulator 300 illustratively includes a DC-DC buck
converter circuit 306 including a pair of MOSFETs Q10, Q11, an inductor L1,
and a
capacitor C6. MOSFETs Q10, Q11 are driven by the PWM generator to provide
open loop DC-DC conversion control. In one embodiment, buck converter circuit
306 runs different fixed PWM duty cycles to improve efficiency and reduce the
likelihood of high boost ratios. In one embodiment, buck converter circuit 306
reduces the DC power supply to the proper point when the supply exceeds the
required load. In one embodiment, the power boost regulator 300 with DC-DC
buck
converter circuit 306 normally operates in the right side region 246 of FIG.
10 unless
hardware or temperature limits are reached.
[0079] In an exemplary operation, MOSFETs Q10, Q11 are operated in
complementary fashion at a fixed frequency and duty cycle in order to step
down a
higher voltage across C6 to a lower voltage on the output of the buck section
306.
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Date Recue/Date Received 2020-08-31
Complementary operation means that Q10 and Q11 are never both turned on
simultaneously. The duty cycle is set to the desired step-down ratio, i.e.,
operation of
Q10 at 25% duty cycle and complementary operation of Q11 at 75% duty cycle
results in a buck section output voltage that is 25% of the input voltage. In
one
embodiment, the frequency of MOSFET activation and the inductance are selected
to reduce current ripple in the inductor L1.
[0080] Power boost regulator 300 further includes a current steering
circuit
308 coupled to the output of buck converter circuit 306 (or the output of
boost
rectifier 304 if circuit 306 is not used). Current steering circuit 308 is
operative to
distribute power to multiple output loads based on a priority schedule. For
example,
referring to FIG. 12, several exemplary load devices 440 are coupled to the
output of
power boost regulator 24 and have a preconfigured priority. An engine control
unit
(ECU) 400 is driven by a 16VDC power and controls fuel injection 410
(injectors 20
of FIG. 1), engine throttle, and engine ignition 412 and monitors engine
parameters
via engine sensors 414. In the illustrated embodiment, ECU 400 has the highest
priority for current steering circuit 308 of FIGS. 11A-B so that the engine
can be run
properly during periods of limited electrical power. Engine fuel pump 418 and
a relay
419 illustratively have the next highest priority, and relay 419 routes power
to
headlights 424 and instrumentation 432. Engine loads 402 illustratively have
the
next highest priority for current steering circuit 308 and receive 14 VDC
power for an
engine oil pump 416 and an exhaust valve actuator 420 and other suitable loads
classified as having the next highest priority for engine operation. Exhaust
valve
actuator 420 controls the position of exhaust valves on the engine. Chassis
loads
406 have the next highest priority and receive 14 VDC power for various
vehicle
loads including taillights 422, handwarmers 426 (if equipped), accessory (ACC)
power 428 (e.g., connected to other non-essential accessory loads), battery
charging
430, and other suitable chassis loads that are not critical to proper engine
operation.
In one embodiment, the above priority scheme allows the headlights and hand-
warmers to be fully active at engine idle. Other suitable priority schemes may
be
implemented.
[0081] Current steering circuit 308 of FIGS. 11A-B includes MOSFETs Q7-Q9,
diodes D1-D5, and capacitors C1-05 that cooperate to control the priority of
power
- 20 -
CA 3021812 2018-10-23
delivery to the electrical loads. In the illustrated embodiment, control
circuitry 314 is
preconfigured to control current steering circuit 308 according to the desired
power
distribution hierarchy. Referring to FIG. 12, in one embodiment current
steering
circuit 308 always delivers first available power to ECU 400. If the power
received
by ECU 400 meets the demand (e.g., 16 VDC), current steering circuit 308
switches
on power to critical loads including fuel pump 418 and relay 419 (FIG. 12). If
power
received by fuel pump 418 and relay 419 meets demand (e.g., 14-16 VDC),
current
steering circuit 308 switches on power to engine loads 402 (FIG. 12). If power
received by engine loads 402 meets demand (e.g., 14 VDC), current steering
circuit
308 switches on power to chassis loads 406 (FIG. 12). In one embodiment, after
meeting the power requirements for each load 440, excess power from power
boost
regulator 24 is routed to an external shunt resistor 408 for dissipation. If
power
output is limited during engine operation, current steering circuit 308 drops
power to
the loads in order of least priority to improve the likelihood of maintaining
proper
engine operation, i.e., switches off power to chassis load 406 first, followed
by
engine loads 402, etc.
[0082] Fig. 28 schematically illustrates another embodiment system 800 to
control multiple voltage outputs based on the priority of power delivery to
the
electrical loads. The loads are illustrated as outputs 1-n (801, 802, 80n).
Furthermore, the outputs represent pulse-width modulation duty cycles where an
output receives a percentage of the full cycle or period. In the illustrated
case,
output one 801 is the output with the highest priority. The full input power
(from
source 810) is available to output 1, 801. For outputs of lower priority, 2-n
(802-80n),
the maximum ON-time (pulse-width modulation duty cycle) is the full period
less the
sum of the ON-times for all outputs of a higher priority (see summer 830).
This is
represented by the "(Yo" variability pieces 820, 830 of Fig. 28.
[0083] During any time that power is delivered to a shunt (such as shunt
408)
(shunt time), no power is delivered to the system (AC phases shorted). To
control
the power delivered to the system the shunt time is adjusted based on the
power
demand of the outputs 1-n. In the event of a system power demand that exceeds
the power capabilities of the source, the voltage (power) from the output with
the
lowest priority is eliminated first. As such, higher priority components are
able to be
- 21 -
CA 3021812 2018-10-23
provided in a stable manner while only low priority functionality is
sacrificed, and then
only sacrificed when (and to the extent) needed. Still further, a power
draining failure
on a lower priority component (such as a short in a handgrip heater) does not
have
the ability to negatively impact operation of higher priority elements such as
engine
operation.
[0084] In one embodiment, power boost regulator 24 is operative to direct
pulse width modulation of fuel pump 418, thereby allowing fuel pump 418 pump
pressure to be scaled as needed. In one embodiment, fuel pump 418 further
serves
as a partial power shunt.
[0085] In one embodiment, the priorities for power are dynamic. In such an
embodiment, the priority for loads is dependent on other factors. In one
embodiment, the RPM of the engine is an input in determining the priority for
loads.
For example, at engine RPM's of less than 1500, chassis loads 30 are
prioritized
over critical loads 28 for any portions of a duty cycle beyond the absolute
minimum
needed to supply each load. Alternatively, at engine RPM's of greater than
1500,
critical loads 28 (or other loads) are prioritized over chassis loads 30 for
any excess
portion of a duty cycle (excess portions being those portions not absolutely
necessary for minimum viable function of a component.) As one implementation
of
this, when engine RPM's are below 1500, this represents an idle state. As
such,
components that serve to propel the vehicle are not being fully utilized.
Thus, the
duty cycle excess is better served by being made available to chassis loads,
such as
a load that charges the battery or ultracapacitor.
[0086] In the illustrated embodiment of FIGS. 11A-B, power boost regulator
300 provides a wake-up operation for starting the engine. In particular, when
the
engine is initially rotated for starting via a pull-start or other actuation
mechanism,
power from stator 302 bypasses boost rectifier stage 304 via the intrinsic
diodes
(e.g., diode 312, etc.) of MOSFETs Q1-Q6 to build up voltage in capacitor Cl.
Once
the voltage across Cl exceeds a turn-on threshold, control circuitry 314
powers up
and begins operating MOSFETs 01-06 of boost rectifier stage 304 based on
control
commands from microcontroller 128 (FIG. 7).
- 22 -
CA 3021812 2018-10-23
[0087] Fig. 26 illustrates a start-up circuit 600. Start-up circuit 600
operates to
increase power generation during start-up, thereby improving starting quality.
For
batteryless systems, voltage regulator 350 is powered via the permanent magnet
magneto 22 output during engine start. Body diodes in the Boost/Rectify
MOSFETs
Q1-06, 304, rectify the AC voltage from the stator to produce power. Output
power
can be increased by periodic shunting of the stator output. While shunted, the
stator
current builds up so that when the shunting stops, the higher current is
delivered,
charging capacitor C3 (610). It should be appreciated that the shown circuit
is
operable to shunt the stator with voltage of less than 1V. As such, the
provided
circuit is able to operate at a relatively low voltage. This ability allows
starting the
regulator 350 and engine at a lower voltage than would otherwise be permitted.
This
low starting voltage allows for a reduced number of stator turns, which boosts
output
power at higher RPM. The system overall provides for easier starting.
[0088] Again referring to the circuit 600 of Fig. 26, during engine start,
the
diodes in MOSFETs Q1-Q6 rectify the low AC voltage and charge capacitor C3
through diode Dl. IC U2 is a low drop-out voltage regulator. Initially VDD is
nearly
equal to the voltage across C3. When VDD reaches approximately 0.75V, the U1
oscillator circuit starts operation, connecting GATE to VDD and charging Cl.
When
Cl exceeds a predetermined percentage of VDD, GATE is turned off and pin 7 of
U1
is pulled low, discharging C1. When the voltage held by Cl becomes less than a
second, lower percentage of VDD, GATE is turned ON, pin 7 becomes high-
resistance, and Cl resumes charging, restarting the cycle.
[0089] The voltage pulses on the gate of Q7 cause it to cycle on and off.
When on, VBUS is grounded, shunting the stator through the diodes of MOSFETS
Q1-Q6. When off, VBUS rises to pass current through D1 and charge 03. The
start-
up circuit 600 is disabled by pulling the CONTROL line low when the voltage
across
03 is sufficient for normal operation.
[0090] In certain embodiments, ultracapacitors are used in place of
batteries.
Ultracapacitors store energy in an electric field rather than a chemical
reaction.
Ultracapacitors provide the ability to survive many more charging and
discharging
events than batteries. Fig. 27 illustrates operation of a relay that can be
used to
- 23 -
CA 3021812 2018-10-23
control battery charging and that can also support the use of ultracapacitors.
Still
further, the operation shown in Fig. 27 provides for detection of a failed
battery.
[0091] In operation, regulator 350 or ECU 400 controls a battery charge
relay
that selectively couples power to a chassis power output of regulator 350
(which
supplies chassis loads 30). The relay has an open state in which chassis loads
30
are disconnected from power and has a closed state in which chassis loads 30
are
connected to power. Whenever the vehicle is powered down or the engine is not
running, the relay is in the open configuration, block 710. Upon vehicle
startup,
block 720, the regulator 350 (or ECU 400) receives an indication of battery
voltage
and chassis power output. These values are received, for example, either by
directly
measuring them, or via message over CAN.
[0092] The relay remains closed after startup, block 730, until chassis
power
output is greater than or equal to the battery voltage (and the battery
voltage is
greater than zero.), block 730. It should be appreciated that this condition
is
expected to occur relatively quickly after startup. Once this condition is
met, the
relay is closed, block 750. Once the relay is closed, power is delivered to
the
chassis load 30. If the user ever stops the engine, block 760/765, then the
relay is
opened, block 710 to await the next engine start.
[0093] While the relay is closed, the chassis output continues to be
monitored.
For so long as the Chassis Output does not drop below 12.8V for 300 seconds,
block
770, the relay remains closed, block 750. However, if the chassis output drops
below 12.8V for 300 seconds, block 770, then the relay is opened for one
second,
block 780. The chassis output is monitored during that time to see if the
chassis
voltage recovers quickly in response to the relay opening, block 790. If it
does not,
then the relay remains open, and the system returns to block 740 to monitor
the
chassis output and battery voltage to close or open the relay as previously
described. If the chassis output voltage recovers by 1.0V or greater at block
790,
then it is assumed that the battery is having a harmful effect on the chassis
output
voltage. Thus, a battery fault is noted and the relay remains open, block 795.
As
such, chassis loads 30 are not permitted to drain the battery. Still further,
a faulty
battery is not able to drain power at the expense of chassis loads 30.
Finally,
because the relay closes as soon as the chassis voltage rises to the battery
voltage,
- 24 -
CA 3021812 2018-10-23
there is no current spike therebetween. Such a setup provides for increased
life of
the electrical components linked by the relay. Also, this relay prevents
discharge of
the battery or ultracapacitor when the engine is stopped.
[0094] Referring to FIGS. 13A-B, another exemplary power boost regulator
350 is illustrated according to an embodiment. Power boost regulator includes
a
three phase shunt regulator circuit 354 coupled to the output of a stator 352
and an
interleaved DC-DC converter buck circuit 356 coupled to the output of circuit
354. A
single output stage 358 is illustratively coupled to the output of interleaved
buck
circuit 356, such as for charging a vehicle battery, for example. Shunt
regulator
circuit 354 is another exemplary type of boost rectifier circuit, also
referred to as a
half controlled boost rectifier, with switching elements only on the low side
(phase to
ground). Control logic 355 of shunt regulator circuit 354 may be provided with
a
microcontroller, such as microcontroller 128 of FIG. 7, for controlling
functionality of
circuit 354.
[0095] Similar to buck circuit 306 of FIGS. 11A-B, interleaved buck
circuit 356
of FIGS. 13A-B is operative to regulate the supply power to the proper point
as
determined by the load. Interleaved buck circuit 356 is further operative to
reduce
the amount of ripple in the output current. Each MOSFET switch Q5-Q7 has a
respective complementary MOSFET switch 06-O8, and the MOSFET switches
operate in parallel with inductors L1-L3. In the illustrated embodiment, the
duty cycle
of the MOSFETs is fixed at 1/n, where n is the number of parallel circuits
(illustratively n=3). As such, one high-side MOSFET switch is on at a time,
and
when one MOSFET switch is turned off another MOSFET switch is turned on.
Accordingly, one inductor is connected to the source (e.g., first stage
output) at all
times resulting in substantially constant input current and a reduction in
required
source capacitance. Interleaved buck circuit 356 is operative to
simultaneously fix
the buck duty cycle and provide a constant, regulated output voltage based on
the
load because voltage regulation is performed by varying the boost section duty
cycle.
[0096] In one embodiment, the interleaved buck circuit 356 is used for a
vehicle with a battery, and the single output 358 routes power for charging
the
battery. In another embodiment, a current steering circuit, such as circuit
308 of
- 25 -
CA 3021812 2018-10-23
FIGS. 11A-B, is coupled to the output of buck circuit 356 for distributing
power to
loads of a vehicle with or without a battery.
[0097] In the illustrated embodiment, power boost regulator 24 of FIG. 1
(and
exemplary regulators 300, 350 of FIGS. 11A and 13A) is operative to reduce the
amount of shunting required due to the adjustment of the stator voltage at the
boost
circuit stage. In one embodiment, less shunting results in less heat
generated. As
described herein, power boost regulator 24 is operative to shunt excess power
to
external shunt resistor 408 (FIG. 12) such that the output voltage is not
higher than
the target load voltage. However, such shunting is substantially reduced
compared
to conventional charging systems due to the ability of power boost regulator
24 to
change the voltage at which power is taken from AC power source 22 (FIG. 1) in
the
boosting circuit.
[0098] As an example, in a vehicle requiring 320 W power at 5800 RPM,
power boost regulator 24 in one embodiment is operative to match the stator
output
to the load voltage by causing the stator to run at 109 V at 2.93 amps (A) to
achieve
the 320 W. However, a conventional power generator system having only shunt
type
regulation without power boost regulator 24 operates at or below the
regulating
voltage. For example, the stator in a conventional system may operate at 7 V
and
45.7 A to achieve the 320 W power, which is 15 times more current and 240
times
more resistive losses than the exemplary operating points provided with power
boost
regulator 24.
[0099] Fig. 11D shows another exemplary regulator 360 that provides reduced
part count, reduced heat generation, reduced package size, and reduced
complexity
relative to regulators 300, 300' of Figs. 11A, 11B, and 11C. Regulator 360
uses a
different rectify/boost stage 304" and provides a different current steering
circuit
308" relative to steering circuits 308, 308' of the embodiments of Figs. 11B
and 11C.
Steering circuit 308" provides the same functionality as steering circuits
308, 308'.
Circuit 308" uses less transistors/MOSFETs (Q8, Q9) than circuits 308, 308'.
This
results in less heat generation and less space needs. Steering circuit 308"
shows,
as an example, three outputs (to ECU, critical, and chassis loads). However,
the
design shown in Fig. 11D can be expanded to handle additional loads. Such
designs employing the concepts of steering circuit 308" utilize 3*N diodes in
the main
- 26 -
Date Recue/Date Received 2020-08-31
current paths (D2-10 in the shown example), where N= the number of outputs.
[00100] Alternative embodiments of a shunt regulator are illustrated in
FIGS. 14
and 15. In the embodiments of FIGS. 14 and 15, a shunt regulator 450, 460 is
operative to provide regulated voltage to the ECU, fuel injectors, and other
critical
loads while automatically reducing the voltage applied to non-critical loads
such as
lights and handwarmers at low engine speeds. A single phase shunt regulator
450
of FIG. 14 includes a full-wave rectifier with diodes D1-D4 and control
circuitry 454
that regulates the output of a single phase stator winding 452. A diode T3 is
a shunt
device operative to shunt excess rectifier output to ground. A capacitor Cl
provides
a smooth voltage to the critical loads.
[00101] Similarly, a three-phase shunt regulator 460 of FIG. 15 includes a
three-phase rectifier and control circuitry 464 that regulates the output of a
three-
phase stator winding 462. The three-phase rectifier is formed with diodes D6-
D12,
and diodes T4-T6 are shunt devices operative to shunt excess rectifier output
to
ground. A capacitor C2 provides a smooth voltage to the critical loads.
[00102] In operation, the percentage on-time of the respective shunt device
and
the non-essential devices of FIGS. 14 and 15 are adjusted to ensure constant
voltage to the essential loads. At low engine speeds, the shunt device remains
off
and the non-essential device (e.g., light device, handwarmer, etc.) is
modulated.
When the non-essential device modulation reaches 100%, the shunt device is
modulated to continue regulator the essential load voltage. FIG. 16
illustrates an
exemplary control scheme 470 for shunt regulators 450, 460 of FIGS. 14 and 15.
At
block 472, the smoothing capacitor voltage is compared to a reference voltage.
Ki,
Kp, and the integral block 473 form a standard PI regulator 474. The output
range of
the integrator of PI regulator 474 is clamped to between zero and two to
reduce the
likelihood of issues at light and maximum load. The Clamp 0..1 block outputs
the
input value if the input is between the limits of zero and one, and otherwise
it outputs
the closest limit value of zero or one. The Clamp 1..2 block outputs the input
value if
the input is between the limits of one and two, and otherwise it outputs the
closest
limit value of zero or one. The effect is that for control values between zero
and one
the non-essential devices are modulated while the shunt device stays off, and
for
- 27 -
Date Recue/Date Received 2020-08-31
control values between one and two the non-essential devices are on 100% of
the
time and the shunt device stays off. In some embodiments, the control scheme
470
of FIG. 16 is implemented as an analog circuit (e.g., control circuitry 454,
464 of
FIGS. 14 and 15) or as software in a microcontroller, for example.
[00103] In one embodiment, the shunt is located to dissipate current from
the
stator to an externally cooled surface, such as a surface of the engine
assembly or
other surface. In another embodiment, the shunt is located to dissipate
current to
the surface of the fuel tank of the vehicle.
[00104] Power supplied to outputs (such as ECU, Critical, and Chassis)
varies
through a pulse width modulation (PWM) cycle. This variability (Fig. 24) is
referred
to as voltage "ripple." While some ripple is expected, relatively high amount
of ripple
can negatively impact engine performance. The ripple is calculated by taking
multiple readings throughout the PWM cycle and then subtracting the minimum
voltage from the maximum voltage, block 2500, Fig. 25. This value is then
compared to a threshold of acceptable ripple, block 2510. When the measured
ripple is below the threshold (in an acceptable range) the system resets a
timer,
block 2520, and continues to take readings and monitor the ripple.
[00105] The threshold is set to a value where the engine can still operate
above
the threshold. Such a setting provides that the ripple will exceed the
threshold at a
point before engine failure occurs. When the ripple exceeds the threshold, the
system increments a timer, block 2530, and then checks to see if the timer
indicates
the passage of a sufficient amount of time, block 2540. This timer check
determines
if the ripple value is a transient over-threshold ripple or a sustained over-
threshold
ripple. Again, whenever the ripple is below the magnitude threshold, the timer
gets
reset, block 2520. When the timer is below a time threshold, the system again
measures and calculates the ripple, block 2500. When the timer is above a
threshold, thereby establishing a lasting nature to the out of specification
ripple, a
diagnostic code is triggered indicating trouble, block 2550. This diagnostic
code
indicates that the ripple is too high for a sustained period of time. This is
likely
indicative of failure of capacitors within the system that are used to
stabilize outputs.
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CA 3021812 2018-10-23
[00106] In addition to supplying power to the outputs (ECU, Critical, and
Chassis), some amount of power is consumed by the regulator (300, 350, 360)
itself.
For efficiency, efforts are made to keep such power consumption low. Still
further,
operational faults can cause increases in power consumption of the regulator
(300,
350, 360). With reference to Fig. 11C, in normal operation, C2-C4 have nearly
constant voltage, i.e., equal charge is added and then removed each PWM cycle.
Thus charge out of the Rectify/Boost stage 304 is fed either to the internal
control
electronics or one of the outputs. The average current out of the
Rectify/Boost stage
304 is the current measured by measuring voltage across resistor R1 multiplied
by
the percent of time the Rectify/Boost stage 304 is not shunting.
[00107] All three outputs share a common ground connection, so the current
through resistor R2 is the sum of the current delivered to the three outputs.
Any
charge delivered by the Rectify/Boost stage 304 and not delivered to the
outputs is
consumed internally to the regulator 360. This internal current consumption
can be
calculated from the calculated average Rectify/Boost output and the measured
ground current. If this exceeds a predetermined threshold for a predetermined
time,
a diagnostic code is sent. Earlier detection of an internal power drain
increases the
likelihood any negative impact caused thereby is lessened.
[00108] Such internal power drains are one type of failure or degraded
operation of PBR 300, 350, 360. PBR 300, 350, 360 is provided with a serial
communication port(s) that provide for serial communication. Due to the PBR
300,
350, 360 having serial communication and the ability to detect internal or
external
faults of the Charging System. The PBR 300, 350, 360 is able to alert the
system
that a fault is detected. Thus, in the case of fault detection by the PBR 300,
350,
360, the PBR 300, 350, 360 is be able to react with the following control: 1)
Send out
diagnostic message that indicates to the system that there is a fault
detected. 2)
Send out the Diagnostic Message and Limit the chassis output (lowest priority
output).
[00109] The diagnostic message further indicates a severity level of the
detected fault. The system is then able to react in a manner appropriate for
the
severity of the detected fault. By the way of example, in one embodiment, the
following severity levels are used:
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Date Recue/Date Received 2020-08-31
Severity level 1: regulator limits Chassis power output (comfort reduced)
Severity level 2: ECU limits engine RPM or vehicle speed (performance reduced)
Severity level 3: ECU or regulator shuts down engine (loss of function)
[00110] Referring to FIG. 17, an illustrative embodiment of an engine 500
(e.g.,
engine 16 of FIG. 1) includes an engine head 502 coupled to an engine block
504. A
power generation assembly 510 is coupled to a crankcase 506 of engine 500 and
driven by the engine crankshaft 518 (FIG. 20). As illustrated in FIG. 18,
power
generation assembly 510 includes a housing 514, a shroud 516, and a magneto
and
starter assembly 512. Magneto and starter assembly 512 includes a recoil
starter
520, a magneto 524, and a flywheel 522 coupled between magneto 524 and recoil
starter 520. Flywheel 522 illustratively includes a plurality of
circumferentially spaced
blades 528 configured to draw air through the stator of magneto 524 during
operation and through circumferentially spaced openings 530 of recoil starter
520.
Alternatively, a separate air pump or fan may be coupled to assembly 512 for
drawing air through assembly 512.
[00111] Certain embodiments of magneto and starter assembly 512 use a
plurality of magnets disposed on a flywheel with alternating polarities.
Movement of
the magento and starter assembly 512 induce eddy currents due to the relative
motion of the magnets and current source. Eddy current losses are proportional
to
the square of the conductor area. Fig. 23A shows a typical magnet pole having
a
width W and a length L. In one embodiment, rather than providing a single
magnet
each magnet pole is divided into multiple pieces, Fig. 23B. The Eddy current
power
loss for the magnet of Fig. 23A is calculated as Loss=K*(L*W)2. By using three
magnets each having a width of 1/3 of W, Fig. 23B, the calculated loss is
calculated
as Loss=3*K(L*W/3)2. Thus, the loss for the setup of Fig. 23B is 1/3 of the
loss for
the setup of Fig. 23A.
[00112] Power loss manifests itself as heat. Thus reducing the loss reduces
the total heat generation and maximum magnet temperature. Magnets have
reduced performance at higher temperatures. Reducing power losses in the
magnets
reduces magnet temperature and thus increases output in steady-state
conditions.
- 30 -
CA 3021812 2018-10-23
[00113] As illustrated in FIGS. 18, 19, and 22, shroud 516 includes a
circumferential wall 532 configured to form a perimeter around flywheel 522.
Wall
532 of shroud 516 includes radially extending regions 534, 536 that fit in
corresponding cavities 552, 554 of housing 514. A circumferential flange
portion 538
of shroud 516 is positioned on end or seat 550 of housing 514 such that flange
portion 538 is coupled between housing 514 and crankcase 506 (FIG. 20). In
another embodiment, shroud 516 is integral with crankcase 506. Housing 514
includes a plurality of spaced slots or openings 556 extending through the
outside
cover. An inner wall 558 of housing 514 is substantially cylindrical and forms
an
opening to receive shroud 516 and magneto and starter assembly 512. FIG. 22
illustrates recoil starter 520 positioned in housing 514 between shroud 516
and the
end cover of housing 514. Recoil starter 520 includes a plurality of
circumferentially
spaced openings 574 configured to route air flow received through flywheel
through
openings 556 of housing 514. A fastener 546 such as a bolt or screw is
threaded
through recoil starter 520 and into a bearing assembly 548 of housing 514 such
that
recoil starter 520 and flywheel 522 may rotate relative to housing 514. An
opening
560 in housing 514 is configured to receive a pull-start cord of recoil
starter 520.
When the cord is pulled, the uncoiling rope spins recoil starter 520 to crank
engine
500 (FIG. 17). After the cord is pulled, flywheel 522 keeps spinning and
engine 500
starts.
[00114] Referring to FIG. 20, assembly 510 couples to crankcase 506 via a
plurality of fasteners or bolts through housing 514. Magneto 524 includes a
rotor
540 and a stator 542 having coil windings. Rotor 540 illustratively includes a
permanent magnet 541 operative to rotate around coils of stator 542 to induce
a
voltage and current in the stator coils that is regulated by power boost
regulator 24
(FIG. 1). Another suitable magneto, alternator, or electrical generator may be
provided. A plurality of spaced openings 570 are formed in crankcase 506
behind
magneto 524 (FIGS. 20 and 21).
[00115] Shroud 516 extends from the outer wall of crankcase 506 to the
outer
wall of magneto 524, thereby forcing air drawn through openings 570 behind
magneto 524 to flow over the stator windings 542 and through openings in the
flywheel 522. Shroud 516 thereby blocks or limits the intake air from openings
570
- 31 -
CA 3021812 2018-10-23
from flowing around the outside of stator 542 and flywheel 522. In operation,
flywheel 522 or a separate fan or air pump draws air through openings 570 of
crankcase 506 and over stator coils 542 of magneto 524. Shroud 516 blocks air
flow
around flywheel 522 causing the air to flow through openings in flywheel 522,
openings 574 (FIG. 22) in recoil starter 520, and out openings 556 of housing
514.
[00116] In one embodiment, assembly 510 is operative to draw air from a
cooler side of engine 500 behind magneto 524 and to outlet the air to a hotter
side of
engine 500, thereby facilitating cooling of magneto 524. For example, an
exhaust
system may be coupled adjacent recoil starter 520 which causes additional heat
at
that side of engine 500.
[00117] FIG. 30 shows an alternative embodiment flywheel 950. Flywheel 950
includes a circumferential wall 966 on which alternating magnetic poles 962,
964 are
mounted. On the exterior of wall 966 is mounted a ferrous steel ring 958. The
inner
side of wall 966 has a non-magnetic stainless ring 952 mounted thereto. The
wall
966 includes slots 956 therein. Flywheel 950 further includes ribs 968
extending
from an end face and includes a plurality of holes in the end face. In
operation, air
(or oil) approaching flywheel 950 in direction 960 enters flywheel 950 via the
holes in
the end face (or otherwise) and is routed radially in the direction of arrows
954 with
the aid off ribs 968. The air (or oil) enters slots 956 and exits the upper
side (as
oriented in Fig. 30). This configuration provides additional cooling to
flywheel 950
and to the magnetic poles 962, 964. As previously noted, a controlled
temperature
proximate magnetic poles 962, 964 provides improved performance and
consistency
of performance relative to poles 962, 964 with elevated temperature.
[00118] As previously noted, PBR 300, 350, 360 includes serial
communication. PBR 300, 350, 360 is able to sense internal temperatures,
either
directly via sensors, or indirectly via measurements indicating things such as
degradation in performance. When the internal temperature reaches a set-point
that
is able to be calibrated, then the PBR 300, 350, 360 will send a CAN message
to the
ECU 400 that controls the fan 900. The ECU 400 will then turn on the fan until
the
PBR CAN message indicating elevated temperature is no longer active.
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CA 3021812 2018-10-23
[00119] Referring to FIG. 31, an exemplary voltage monitoring system 1000
is
shown. As shown in FIG. 31, power boost regulator 24 is coupled to a plurality
of
electrical loads 38 through at least one power output line 1002. Electrical
loads 38
illustratively include an engine control unit (ECU) 1004, an ignition system
1006, and
an injector system 1008. Other electrical loads are contemplated and disclosed
herein. Engine control unit (ECU) 1004 controls ignition system 1006 and
injector
system 1008 through at least a first control line 1010 and a second control
line 1012,
respectively. In the illustrated embodiment, each of engine control unit (ECU)
1004,
ignition system 1006, and injector system 1008 are connected to power boost
regulator 24 through the same power output line 1002. In other embodiments,
one
or more of engine control unit (ECU) 1004, ignition system 1006, and injector
system
1008 may be connected to power boost regulator 24 independently. In other
embodiments, engine control unit (ECU) 1004 is connected to power boost
regulator
24 through power output line 1002 and in turn provides power to ignition
system
1006 and injector system 1008.
[00120] A voltage sense line 1020 is coupled to a high side of the fuel
injector
system 1008 at a location remote from power boost regulator 24. An external
voltage sense circuit 1030 of power boost regulator 24 monitors the voltage at
the
high side of the fule injector system 1008. The monitored voltage is compared
to a
desired voltage and is used by power boost regulator 24 to control AC power
source
22 to provide a target voltage level and a target current level as disclosed
herein.
Adavntages, among others, for monitoring the voltage at the highest priority
load,
illustratively injector system 1008, and using that monitored voltage to
control AC
power source 22 are a reduction in voltage ripple at the highest priority
load, higher
performance, and lower emissions.
[00121] Power boost regulator 24 further includes an internal voltage sense
circuit 1032 which monitors a voltage over line 1038 being output by power
boost
regulator 24 to power output line 1002 through a first connector interface
1040.
Exemplary connector interfaces include plugs, screws, and other devices for
making
an electrical connection. In one embodiment, if the voltage monitored over
external
voltage sense line 1020 is below a first threshold then power boost regulator
substitutes the voltage monitored by internal voltage sense circuit 1032 for
the
- 33 -
Date Recue/Date Received 2020-08-31
voltage monitored by the external voltage sense circuit in the control of AC
power
source 22. An exemplary first threshold is 2 volts (V). In this manner, the
voltage
monitored over line 1038 provides continued operation of power boost regulator
in a
scenario wherein sense line 1020 has been disconnected or otherwise damaged.
[00122] As shown in FIG. 31, sense line 1020 is coupled to power boost
regulator 24 through a second connector interface 1050 which is spaced apart
from
first connector interface 1040. Exemplary connector interfaces include plugs,
screws, and other devices for making an electrical connection.
[00123] While this invention has been described as having an exemplary
design, the present invention may be further modified within the spirit and
scope of
this disclosure. This application is therefore intended to cover any
variations, uses,
or adaptations of the invention using its general principles. Further, this
application
is intended to cover such departures from the present disclosure as come
within
known or customary practice in the art to which this invention pertains.
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Date Recue/Date Received 2020-08-31
