Note: Descriptions are shown in the official language in which they were submitted.
ELECTRONIC CONTROLLER FOR RAPID DEFROSTING AND AUTOMATED
DEFOGGING IN VEHICLES
FIELD
The present disclosure relates to methods and systems for defrosting and
defogging
surfaces of vehicles, such as those of Electric Vehicles (EVs).
BACKGROUND
Transparent windshields for various vehicles, such as cars, rail vehicles
including trains,
streetcars, and locomotives, snowmobiles, airplanes, helicopters and sea
vessels, are deiced or
defrosted using available on-board power. Typically, defrosting is
accomplished by blowing air
heated by the vehicle's engine onto the windshield. In gas engine vehicles,
deicing/defrosting
takes a considerable amount of time since the engine is initially cold upon
startup. In EVs, a
considerable amount of energy from the battery is used to produce the heat to
defrost or deice
the windshield.
A windshield deicing system was previously introduced using pulse electro
thermal
deicing (PETD) as disclosed in US Pat Nos. 8,921,739 and 6,870,139. Such a
system provides a
high density of heating power (W/m2) which allows for rapid and energy
efficient deicing or
defrosting. It should be noted that throughout the present disclosure use of
the term
"defrosting" and "deicing" will be used interchangeably to generally refer to
removing frozen
water from a surface.
Electric vehicles are growing at a very rapid rate and are expected to reach
50% of
global sales in the early 2030s. Previous defrosting/defogging methods were
developed for gas
engines. However, EVs present different challenges for managing power input to
the controller
and controller outputs to the windshield.
In EVs, the same methods for air defrost and air defog have carried over to
EVs from
gas vehicles. However, the source of the power for defrost and defog in an EV
often is
generated from the EV's high-voltage battery, the same source of power for
motor power. So
any energy diverted from the battery to defrost and defog reduces the driving
range. One study
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Date Recue/Date Received 2023-03-28
of actual driving range in EV fleets by Geotab found that at -20 C, actual
driving range
dropped by 41% compared to stated range due to cabin heating, which includes
defrost and
defog.
To defrost a low-e windshield or glass that has transparent conductive metal
coatings
inside of the glass lamination, a voltage is applied to this conductive layer.
In order to
minimize the heat used to remove frost, ice and fog from a vehicle's glass
surface, high power
levels of typically 3 kW or more, are applied to this metal layer. This is the
minimal power
level to completely defrost and defog the windshield by itself, without air
defrost or defog and
down to temperatures of -40 C.
The metal layers used in glass typically have resistance levels of 1-15 ohms.
To reach
these power levels high-voltage levels (typically 250V to 900V, nominal)
directly from the
high-voltage battery can be provided to a controller that controls the power
to the windshield
and optimizes the power level to provide the minimal amount, or more, of heat
to melt the
interfacial layer of ice, thus making it easy to remove mechanically with
gravity, wipers, or
another method. This low energy method is very efficient because it does not
attempt to melt
the entire mass of ice. Due to the variation in operating voltages of about +/-
25% based on the
state of charge (SOC) for the battery, a step-down transformer may be needed
to provide
optimal power to the glass surface.
Windshield defrosting/defogging systems using pulse-el ectro thermal deicing
(PETD)provide a high density of heating power (W/m2), which allows for rapid
and energy-
efficient defrosting. Rapid heating ensures that the thin, or boundary, layer
of ice (e. g.,
between 1 pin and 1 mm) at the ice/windshield interface is heated to the ice
melting point. In
one variation, windshield heaters are continuous film metal-oxide transparent
coatings made of
indium-tin-oxide (ITO), Zinc-oxide, tin-oxide or any other electrically
conductive, transparent,
film made of a single metal oxide or a composite of several metal oxides. In
another variation,
windshield heaters are thin optically transparent metal films made of silver,
aluminum, gold or
the like, or of an electrically conductive and optically transparent polymer
material.
In automotive, commercial vehicle and other markets, high-voltage (HV) systems
are
defined as those with voltage levels above 60V. At high voltages, the OEMs and
industry
standards bodies have additional safety requirements and standards. In some
cases, these
requirements reduce the risk of human exposure to these high voltages.
Additionally, costs for
high-voltage components are generally more expensive since the sales volumes
are lower.
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Accordingly, systems that operate at lower ranges, e.g., below 60V, have lower
design
requirements and lower costs.
BRIEF SUMMARY
According to a first aspect, there is provided a system for defogging and
defrosting a
vehicle surface including: a vehicle surface adapted to receive discontinuous
electrical signals
for application to said vehicle surface; at least one DC bus; and a power
controller for
providing the electrical signals to the vehicle surface, the power controller
coupled to a first
DC bus of the at least one DC bus via an input EMI filter, coupled to the
vehicle surface via an
output filter, and including a voltage converter controlled by a
microcontroller for modulating
voltage and current levels for the electrical signals, and internal signal
sensors for monitoring
the provision of electrical signals to the vehicle surface.
In some embodiments, the electrical signals provided to the vehicle surface
are low-
voltage high-current signals, and the output filter of the power controller
includes a low-voltage
high-current output filter.
In some embodiments, the voltage converter of the power controller includes
galvanic
isolation coupled between the EMI filter and the low-voltage high-current
output filter.
In some embodiments, the first DC bus includes a high-voltage DC bus, and the
voltage
converter includes a synchronous rectifier coupled between the galvanic
isolation and the low-
voltage high-current output filter configured for low-voltage high-current
operation, and a full
bridge MOSFET coupled between the input EMI filter and the galvanic isolation.
In some embodiments, the power controller further includes a first isolated
gate driver
coupled between the microcontroller and the full bridge MOSFET and a second
isolated gate
driver coupled between the microcontroller and the synchronous rectifier, the
first and second
isolated gate drivers for use by the microcontroller in controlling a pulsing
of the electrical
signals.
In some embodiments, the first DC bus includes a high-voltage DC bus, in which
the at
least one DC bus includes a low-voltage DC bus, in which the power controller
is coupled to
the low-voltage DC bus, and in which the voltage converter includes an output
full bridge
MOSFET configured for low-voltage high-current operation and coupled between
the galvanic
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Date Recue/Date Received 2023-03-28
isolation and the low-voltage high-current output filter, and an input full
bridge MOSFET
coupled between the input EMI filter and the galvanic isolation.
In some embodiments, the power controller further includes a first isolated
gate driver
coupled between the microcontroller and the input full bridge MOSFET and a
second isolated
gate driver coupled between the microcontroller and the output full bridge
MOSFET, the first
and second isolated gate drivers for use by the microcontroller in controlling
a pulsing of the
electrical signals.
In some embodiments, the power controller further includes a further output
full bridge
MOSFET coupled between the galvanic isolation and the low-voltage DC bus, and
an isolated
gate driver coupled between the microcontroller and the further output full
bridge MOSFET,
whereby the power controller performs DC/DC conversion between the high-
voltage DC bus
and the low-voltage DC bus.
In some embodiments, the first DC bus includes a low-voltage DC bus, and in
which the
voltage converter includes, coupled between the EMI filter and the low-voltage
high-current
output filter, a multi-phase converter without galvanic isolation for
adjusting voltage levels of
the electrical signals.
In some embodiments, the power controller further includes an isolated gate
driver
coupled between the microcontroller and the multi-phase converter, the
isolated gate driver for
use by the microcontroller in controlling a pulsing of the electrical signals.
In some embodiments, the power controller further includes vehicle surface
sensors for
generating vehicle surface data for use by the microcontroller in said
modulating voltage and
current levels for the electrical signals.
In some embodiments, the discontinuous electrical signals include pulse
electro thermal
defrosting (PETD) signals.
In some embodiments, the vehicle surface comprises a windshield.
According to another aspect, there is provided a method of preventing
condensation on a
vehicle surface of a vehicle, the method including: gathering data from
sensors of the vehicle;
determining a dew point from the data; and controlling a temperature of the
vehicle surface to
remain above the dewpoint with discontinuous electrical signals provided to
the vehicle
surface.
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Date Recue/Date Received 2023-03-28
In some embodiments, the sensors of the vehicle include at least one of a
cabin
temperature sensor, a cabin relative humidity sensor, an outside temperature
sensor, and a
vehicle surface temperature sensor.
Some embodiments further provide for: determining parameters for driving the
electrical
signals from the data measured from the sensors.
In some embodiments, data from the sensors is sampled intermittently at an
adjustable
time period determined with use of the data measured from the sensors.
According to a further aspect, there is provided a method of automatic
notification of a
defect in a vehicle surface of a vehicle, the method including: detecting the
defect in the
vehicle surface; sending a signal to the vehicle Controller Area Network (CAN)
bus with a
Diagnostic Troubleshooting Code (DTC) error message; and communicating a
notification of
the DTC error thereby notifying a defect in the vehicle surface for repair or
replacement.
In some embodiments, communicating the notification includes sending an error
message to a driver of the vehicle via one or more of local vehicle display
and electronic
notification to electronic device of the driver.
In some embodiments, communicating the notification includes sending an error
message to an Original Equipment Manufacturer (OEM) by the vehicle.
Some embodiments further provide for sending the communicated notification to
a
service provider for facilitating repair or replacement of the vehicle
surface.
BRIEF DESCRIPTION OF THE DRAWINGS
To easily identify the discussion of any particular element or act, the most
significant
digit or digits in a reference number refer to the figure number in which that
element is first
introduced. In order to better understand various exemplary embodiments,
reference is made to
the accompanying drawings.
FIG. 1 illustrates a known defrost/defog system.
FIG. 2 illustrates a defrost/defog system including a Type I Power Controller
according
to an embodiment.
FIG. 3 illustrates a Type I Power Controller according to an embodiment.
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Date Recue/Date Received 2023-03-28
FIG. 4 illustrates a defrost/defog system including a Type II Power Controller
according
to an embodiment.
FIG. 5 illustrates a Type II Power Controller according to an embodiment.
FIG. 6 illustrates a defrost/defog system including a Type III Power
Controller
according to an embodiment.
FIG. 7 illustrates a Type III Power Controller according to an embodiment.
FIG. 8 illustrates a method of automated defogging according to an embodiment.
FIG. 9 illustrates a method of defect detection reporting according to an
embodiment.
DETAILED DESCRIPTION
Safe, simple and cost efficient, low energy surface defrosting and defogging
systems
and methods are disclosed. The systems utilize step-up converters, step-down
converters,
DC/DC converters to provide power levels high enough to defrost a glass
surface in less than
1.5 minutes. Some of the disclosed systems include sensors for exterior
temperature and in
some embodiments, for interior temperature and interior humidity. A controller
is used for
limiting defrosting time to that sufficient to melt the boundary layer of ice,
between 1 micron
and 1 millimeter thick, and thereafter to prevent the boundary layer from re-
freezing while
removing the ice. In the case of defogging embodiments, the controller
prevents the formation
of condensation on surfaces by maintaining the surface temperature above the
dew point. The
controller of embodiments with sensors calculates the defrosting power as a
function of
ambient temperature, surface material's coefficient of heat transfer, and the
distance between
the heating layer and ice. For defogging, this controller of embodiments with
sensors calculates
defog power as a function of interior temperature, interior humidity, surface
temperature,
surface material's coefficient of heat transfer, and the distance between the
heating layer and
condensation.
In some embodiments, a controller described as a Type I controller, is
connected to the
high-voltage battery, e.g., via a high-voltage bus. In some embodiments, a
controller described
as a Type II controller, is connected to a DC/DC converter with output
voltages of 12V-48V,
e.g., via a low-voltage bus. The controller steps the voltage up in order to
reach the optimal
power level described above. In some embodiments, a controller described as a
Type III
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Date Recue/Date Received 2023-03-28
controller, is directly embedded inside the DC/DC converter and controls the
pulsing of the
power provided by the DC/DC converter as a secondary output. This embodiment
is the safest,
simplest, and least costly to implement since it allows the DC/DC converter to
utilize existing
circuits for features like galvanic isolation (a typical OEM requirement for
HV safety) and/or
Electromagnetic Interference (EMI) filtering.
The present disclosure describes systems and methods for generating optimal
power
levels in EVs that are safe, simple, and minimize costs. These power levels
can be achieved
with high voltages (>60V) or low voltages ( < 60V). Some embodiments operate
at low
voltages, to achieve the low energy targets for defrosting in a vehicle. These
methods are safer,
simpler and less costly than providing high voltage levels to the glass
because the lower voltage
level is not considered harmful if there is human exposure. Also, a low-
voltage solutions are
not required to meet the OEM's higher requirements for high-voltage
components.
The disclosed variety of methods and systems enable a vehicle maker
flexibility on how
they integrate defrosting and defogging systems into the electrical system of
an EV in
accordance therewith. The first type of power controller, the type I
controller, is an independent
control unit, that is connected to the HV battery on the input side and the
windshield on the
output side. The benefit of this system to the vehicle OEM is that it is
easier to implement with
few architecture changes to the electrical systems. The second type of power
controller, the
type II controller, as an independent control unit that is connected to the
DC/DC converter on
the input side and the windshield on the output side. There are two major
benefits of this
system. First, it can eliminate some of the electronics (e.g., galvanic
isolation) by commonizing
parts with less weight, size and lower costs. The second benefit is that this
system is safer
compared to the first option because the input voltage to this controller is
low-voltage or lower
voltage than the HV battery. The third type of power controller, the type III
controller, has the
hardware for this controller integrated into the vehicles's DC/DC converter,
so that the DC/DC
converter would have two outputs, one to manage the vehicle low-voltage
systems and another
to manage the pulses to the windshield. The benefit of this type of system is
that it is more
integrated with the existing electrical architecture such as the DC/DC
converter. This system
has fewer components, less weight, less size and less cost. In all cases the
control unit (whether
independent or integrated inside the DC/DC converter) would be connected to
the vehicle
Controller Area Network (CAN) system for sensor data exchange. The CAN bus is
a robust
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Date Recue/Date Received 2023-03-28
vehicle bus standard designed to allow microcontrollers and devices to
communicate with each
other's applications without a host computer.
In some embodiments, the electrical pulses from this system provided to the
windshield
have a maximum voltage higher than 60 Volts. In this case, the windshield and
the connecting
wires and connectors are considered high-voltage components and have higher
requirements for
High-Voltage safety from standards bodies such as ISO and Vehicle Original
Equipment
Manufacturers (OEMs).
In some embodiments, the pulses going to the windshield have a maximum voltage
of
60 Volts or lower. In this case the windshield and the connecting wires and
connectors are not
considered high-voltage components, and are known as low-voltage components
which are
considered much safer and having lower electrical safety requirement from
vehicle makers
(e.g., OEMs).
The windshield defrosting/defogging system can be applied to hybrid vehicles
or fully
electric vehicles as well as commercial vehicles either that are electric,
hybrid or have a 12V or
48V system with internal combustion engines. This include light duty trucks
(class 3 or 4),
medium duty (5 or 6) and heavy duty (class 7 or 8) or equivalent
classifications in other
regions.
In some embodiments, the system automatically keeps a vehicle's windshield fog-
free
without any intervention by the driver by using the proprietary defog system
for providing
efficient heat from the conductive layer in the windshield. It may also use a
temperature sensor
and a humidity sensor in the cabin. In another embodiment, a temperature
sensor in the
windshield is also used. This system keeps the glass temperature above the dew
point so that
moisture does not condense onto the windshield and create fog, which occludes
the driver's
vision of the road and creates a very unsafe condition.
A safety system described before, can detect cracks in the conductive layer
that causes a
change in resistance. A crack in this layer could cause allow human exposure
to an electrical
potential which is unsafe, so the detection of a crack automatically shuts
down the output
power to the windshield. A new and separate idea is that after the detection
of a cracked
windshield in the algorithm described previously, a message can be generated
and sent via the
CAN Bus to generate a Diagnostic Troubleshooting Code (DTC) or other alert
notice, that the
vehicle can communicate the need to replace the windshield to the driver, the
dealer, and the
OEM. To notify the driver, this can be done via an onboard service message to
the car's driver
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Date Recue/Date Received 2023-03-28
display and/or a phone app for that vehicle. The DTC code can be sent to the
OEM via their
onboard diagnostics systems and/or telematics system to notify them of the
service need. The
OEM can contact a dealer, or other service provider, and allow them to notify
the driver to
replace the windshield. The dealer can also allow the vehicle owner to
schedule the windshield
replacement when the service part is at the dealer and there is an open
service time.
FIG. 1 shows a detailed view of a windshield with a high-power defrosting
system. A
windshield 102 incorporates a transparent conductive layer 104 which acts as a
heating
element. Power for the heating element is supplied by a power supply 108, and
the supply of
power is regulated by controller 112 and switch 110. The controller 112 uses
information from
.. the sensors 114 to calculate optimum operation conditions and power
delivery. In practice, the
transparent conductive layer 104 will often incorporate several busbars 106,
together called the
heating apparatus. Although busbars 106 are illustrated in this figure at the
top and bottom of
the transparent conductive layer 104, a person skilled in the art will
recognize that the busbars
could be of varying number and locations around the transparent conductive
layer 104.
FIG. 2 shows one embodiment where a Type I Power Controller 226 is connected
to the
High Voltage DC Bus 204 in the vehicle on the input side and to the Windshield
224 on the
output side. FIG. 2 shows the connection diagram for this embodiment into an
EV architecture.
Typically, the High Voltage Battery 210 and the On-Board Charger 208 (that
connects to the
Charging Station 202) and Other High Voltage Loads 218 are connected to the
High Voltage
DC Bus 204. A DC/DC Converter 216 connects the High Voltage DC Bus 204 to the
Low-
voltage DC Bus 206, the DC/AC Converter 220 connects the High Voltage DC Bus
204 to the
Electric Motors / Powertrain 222. The Low-voltage Battery 212 and Low-voltage
Loads 214
are connected to the Low-voltage DC Bus 206. The Type I Power Controller 226
is an addition
to the existing EV architecture as shown in the figure. This embodiment
results in minimal
changes to the current EV architecture because the defrosting and defogging
system is directly
connected to the high-voltage bus having access to the battery energy
directly. In this
architecture, the current power distribution does not need any change.
FIG. 3 shows a proposed controller block diagram for this embodiment. This
usually
include an input EMI Filter 304 and Galvanic Isolation 312. The EMI Filter 304
(to block
.. conductive electromagnetic interference to the DC Bus) is connected to a DC
Link 306 (local
energy storage to facilitate quick energy conversion for the power stage) that
is connected to a
Full Bridge MOSFET 308 (converts DC to AC) on the input side of the Galvanic
Isolation 312
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Date Recue/Date Received 2023-03-28
(for safety and isolating the battery from the windshield). The output side of
the Galvanic
Isolation 312 is connected to a Synchronous Rectifier 314 (converts AC back to
DC) and an
Output Filter 318 (to remove high frequency noise on the output voltage). The
Full Bridge
MOSFET 308 is controlled through an Isolated Gate Driver 310 and the
Synchronous Rectifier
314 is controlled through another Isolated Gate Driver 316; both gate drivers
are operated using
a dedicated Microcontroller (Defrost/Defog Algorithm) 324. The microcontroller
manages
sensor data from both the Power Sensors 320 (this include current and voltage
sensors that are
embedded inside the power controller for example) and the Windshield Sensors
322 (such as
capacitive sensor and optional temperature sensor(s) that are embedded inside
the windshield).
The Type I Power Controller 226 is also connected to the Vehicle CAN Bus 302
for sensor data
exchange with the vehicle. The vehicle Controller Area Network (CAN bus) is a
robust vehicle
bus standard designed to allow microcontrollers and devices to communicate
with each other's
applications without a host computer.
The three components: Full Bridge MOSFET 308, Galvanic Isolation 312, and
Synchronous Rectifier 314 act (collectively) as a "voltage converter"
controlled by the
microcontroller, to deliver the appropriate voltage (and current), according
to the pulsing
schedule appropriate for PETD signal application to the windshield, one
consequence of which
is a lowering of voltage for low-voltage high-current embodiments in a high DC
voltage bus
context.
This embodiment can be flexible to work with either low-voltage or high-
voltage output
to the windshield. In the case of low-voltage, this will require higher
currents and larger bus
bars on the heated surfaces like the Windshield. This offers more flexibility
to automakers to
implement this technology based on the voltage levels of the vehicle and the
resistance levels
of the heating element such as the conductive layer in the glass. A low-
voltage option such as
less than 60V will be considered safer and have lower safety requirements from
automakers.
For example, high-voltage specifications will not apply to these low-voltage
embodiments. In
addition, embodiments that are below 100V will be safer than higher voltages
such as 400V or
800V. Lower voltage ranges offer benefits for safety and design requirements.
Such flexibility
in the design of the controller is an advantage to work with various vehicle
architectures such
as voltage, conductive materials, resistance levels and current levels.
In some embodiments, in the context of high-current, low-voltage PETD signal
delivery
to the windshield, it should be understood that the Synchronous Rectifier 314
and Output Filter
Date Recue/Date Received 2023-03-28
318 on the output side of the Galvanic Isolation 312 are configured
specifically for high-current
and low-voltage signals, and provision of the same to the windshield.
FIG. 4 shows another embodiment where a Type II Power Controller 402 is
connected
to the Low-voltage DC Bus 206 that is connected to the DC/DC Converter 216.
The DC/DC
Converter 216 is a standard part in EVs that is used for the vehicle's low-
voltage systems, e.g.,
12v, 24v, or 48v Systems (206). The Type II Power Controller 402 would be low-
voltage on
the input side and would control the pulses to the Windshield 224. FIG. 4
shows the connection
diagram for this embodiment into an EV architecture. This controller is
connected to the Low-
voltage DC Bus and using a DC/DC converter it steps up/down the voltage
accordingly to
reference signals calculated by PETD algorithm. This architecture is more
suitable for
applications with windshields coated with a metal layer with lower sheet
resistance (ohms per
unit area).
FIG. 5 shows a proposed controller block diagram for this embodiment. In this
embodiment, the low-voltage bus is used to supply power for defrosting and
defogging cycles.
The Type II Power Controller 402 is connected to the Low-voltage DC Bus 206 on
the input
side and the Windshield 224 on the output side. The EMI Filter 502 (to block
conductive
electromagnetic interference to the DC Bus) is connected to a DC Link 504
(local energy
storage to facilitate quick energy conversion for the power stage) that is
connected to a Multi-
phase Converter (No Galvanic Isolation) 506 (to adjust the output voltage
level to the required
value with galvanic isolation) and an Output Filter 510 (to remove high
frequency noise on the
output voltage). The Multi-phase Converter (No Galvanic Isolation) 506 is
controlled through
an Isolated Gate Driver 508 that is operated using a dedicated Microcontroller
(Defrost/Defog
Algorithm) 518. The microcontroller manages sensor data from both the Current
Sensors 512,
the Voltage Sensors 514 and the Windshield Sensors 322 (such as capacitive
sensor and
optional temperature sensor(s) that are embedded inside the windshield). The
Type II Power
Controller 402 is also connected to the Vehicle CAN Bus 302 for sensor data
exchange with the
vehicle.
The Multi-phase Converter (No Galvanic Isolation) 506 acts as a "voltage
converter"
controlled by the microcontroller, to deliver the appropriate voltage (and
current), according to
the pulsing schedule appropriate for PETD signal application to the
windshield.
This architecture provides advantages in comparison with the previous one in
regard to
safety requirements because it can operate in a voltage range between the
voltage bus and 60 V,
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Date Recue/Date Received 2023-03-28
which classifies it as a low-voltage system (voltage class "A" according to
ISO 6469-3). This
fact allows the usage of non-isolated DC/DC power converters which can operate
without the
galvanic isolation provided by bulky and expensive transformers. This saves
significant space,
weight and cost if the galvanic isolation is used in the existing DC/DC
converter providing
power to the Low-voltage DC Bus 206. However, because the power is being
provided at a
lower voltage, in some cases, the input current at the DC/DC converter may be
higher in
comparison with the previous architecture. To overcome this issue multiphase
DC/DC
converters with an interleaved operation could be used as the best option to
implement the
PETD algorithm.
In some embodiments, in the context of high-current, low-voltage PETD signal
delivery
to the windshield, it should be understood that the Output Filter 510 on the
output side of the
Multi-phase Converter (No Galvanic Isolation) 506 is configured specifically
for high-current
and low-voltage signals, and provision of the same to the windshield.
FIG. 6 shows another embodiment a Type III Power Controller 602 is used to
combine
the functions of both the DC/DC converter and the Defrost/Defog controller.
The Type III
Power Controller 602 would have two outputs, one to manage the vehicle low-
voltage systems,
e.g., 12V, 24V, or 48V Systems (206) and another to control the pulses to the
Windshield 224.
FIG. 6 shows the connection diagram for this embodiment into an EV
architecture. This
embodiment aims to optimize the usage of power electronic resources in
electric or hybrid
vehicles through the integration of a DC/DC converter currently present in all
electrified
vehicles. This new vehicular DC/DC converter is connected to the high-voltage
bus and has
two independent output ports, each one generating independent DC buses with
different
voltages and power availabilities. DC/DC converters with Single Input and
Multiple Outputs
(SIMO) are frequently designated as Multiport DC/DC converters. This structure
has
advantages over the previous topologies in terms of the number of power
devices and
conversion steps used because the systems resources (i.e., conversion devices)
are shared. As a
result, this architecture can achieve higher efficiency with low cost,
centralized control and
compact packaging. All these features have high value in automotive and
vehicle applications.
FIG. 7 shows a proposed controller block diagram for this embodiment. The
input port
is connected to the vehicle's high-voltage battery, and it is magnetically
coupled through a
multi-winding transformer (Galvanic Isolation 710) to the output ports 1 and
2, which are used
for DC/DC converter and Defrosting/Defogging, respectively. The Type III Power
Controller
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Date Recue/Date Received 2023-03-28
602 is connected to the High Voltage DC Bus 204 on the input side and the
Windshield 224 as
well as the Low-voltage DC Bus 206 on the output side. The EMI Filter 702 (to
block
conductive electromagnetic interference to the DC Bus) is connected to a DC
Link 704 (local
energy storage to facilitate quick energy conversion for the power stage) that
is connected to an
Input Full Bridge MOSFET 706 (converts DC to AC) on the input side of the
Galvanic
Isolation 710 (for safety and isolating the battery from the windshield and
the low-voltage DC
Bus). One output side of the Galvanic Isolation 710 is connected to Output 1
Full Bridge
MOSFET 712 (converts AC back to DC) and a DC Link 720. The other output side
of the
Galvanic Isolations 710 is connected to Output 2 Full Bridge MOSFET 716
(converts AC back
.. to DC) and an Output Filter 722 (to remove high frequency noise on the
output voltage). The
Input Full Bridge MOSFET 706 is controlled through an Isolated Gate Driver
708, and the
Output 1 Full Bridge MOSFET 712 and Output 2 Full Bridge MOSFET 716 are
controlled
through Isolated Gate Driver 714 and Isolated Gate Driver 718; all three gate
drivers are
operated using a dedicated Microcontroller (Microcontroller (DC/DC Converter
Algorithm and
Defrost/Defog Algorithm) 730. The microcontroller manages sensor date from
both the Current
Sensors 724, the Voltage Sensors 726 and the Windshield Sensors 728 (such as
capacitive
sensor and optional temperature sensor(s) that are embedded inside the
windshield). The Type
III Power Controller 602 is also connected to the Vehicle CAN Bus 302 for
sensor data
exchange with the vehicle.
The components: Input Full Bridge MOSFET 706, Galvanic Isolation 710, and
Output 2
Full Bridge MOSFET 716 act (collectively) as a "voltage converter" controlled
by the
microcontroller, to deliver the appropriate voltage (and current), according
to the pulsing
schedule appropriate for PETD signal application to the windshield, one
consequence of which
is a lowering of voltage for low-voltage high-current embodiments in a high DC
voltage bus
context.
In alternate embodiments, the input side of the Galvanic Isolation 710 has two
separate
inputs for separate coupling of the Input Full Bridge MOSFET 706 respectively
with the Output
1 Full Bridge MOSFET 712 and with the Output 2 Full Bridge MOSFET 716. In
further
embodiments, galvanic isolation is provided by two Galvanic Isolators (similar
to the Galvanic
Isolation 710 as shown) coupled between the Input Full Bridge MOSFET 706 and
respectively
the Output 1 Full Bridge MOSFET 712 and the Output 2 Full Bridge MOSFET 716.
In further
13
Date Recue/Date Received 2023-03-28
embodiments, there are two Input Full Bridge MOSFETs to operate each output
channel
separately.
In this DC/DC converter topology, the energy can be transferred from one port
to
another changing the phase shifts and duty cycles on each one of the three
Full-Bridge
MOSFETs (Input Full Bridge MOSFET 706, Output 1 Full Bridge MOSFET 712, and
Output 2
Full Bridge MOSFET 716). In this application, there are energy storage devices
connected to
the input port (high-voltage battery) and first output port (low-voltage
battery), which means
that these two channels need a bi-directional energy-flowing capability. Each
port has its own
DC link and operates as local subsystem units, within the DC bus the power of
each source can
simply be controlled by regulating the source power/current with duty cycle as
the control
variable. This architecture implemented utilizing multiport DC/DC converters
can extend the
functionalities already present on regular automotive or vehicle DC/DC
converters and
integrate the high-efficient PETD technology for defrosting and defogging
sharing resources as
cables, connectors, enclosures, EMI filter, transformer, liquid cooling system
and control unit
which offers a significant level of savings in terms of space, weight and
cost. This embodiment
can be flexible to work with Defrosting/Defogging controller with either low-
voltage or high-
voltage to the windshield. In the case of low-voltage, this will require
higher currents and
larger bus bars on the heated surfaces like the Windshield. This offers more
flexibility to
automakers to implement this technology based on the voltage levels of the
vehicle and the
.. resistance levels of the heating element such as the conductive layer in
the glass. A low-voltage
option such as less than 60V will be considered more safe and have lower
safety requirements
from automakers. For example, high-voltage specifications will not apply to
these low-voltage
embodiments. In addition, embodiments that are below 100V will be safer than
higher voltages
such as 400V or 800V. Lower voltage ranges offer benefits for safety and
design requirements.
Such flexibility in the design of the controller is an advantage to work with
various vehicle
architectures such as voltage, conductive materials, resistance levels and
current levels.
In some embodiments, in the context of high-current, low-voltage PETD signal
delivery
to the windshield, it should be understood that Output 2 Full Bridge MOSFET
716 and Output
Filter 722 on the output side of the Galvanic Isolation 710 are configured
specifically for high-
current and low-voltage signals, and provision of the same to the windshield.
Although the above embodiments describe systems in the context of defrosting
and
defogging vehicle windshields, it should be understood that the above
teachings are equally
14
Date Recue/Date Received 2023-03-28
applicable to defrosting and/or defogging other surfaces of a vehicle
including but not limited
to side glass, rear glass, camera lenses, LiDAR, headlamps, ... etc. As with
embodiments
described above, the voltage and current levels of the electrical signals are
modulated for
appropriate application to these surfaces, and internal signal sensors as well
as sensors
proximate the surfaces may be used for monitoring the provision of the
electrical signals to
these surfaces.
As described before, the defrost/defog controller can be used to defog a
surface by
heating it to a temperature above the dew point which depends on the
temperature and the
relative humidity of the surroundings. Here, we combine the basic defogging
function with
additional sensors that are being added to vehicles along with the capability
to detect when
defogging is needed in order to automate the defogging feature. As a result of
this feature,
drivers will not need to experience fogged surfaces such as windshields, and
do not need to
push any buttons to initiate the defogging function. This feature provides
additional safety
and convenience to the driver. FIG. 8 shows the flowchart of the automated
defogging feature
using the defrost/defog controller. The controller will receive a signal from
the Vehicle CAN
Bus with information about the outside temperature, cabin temperature, cabin
relative humidity
(802). The controller will then calculate the dew point at the windshield
interior surface (804)
and optimize the pulses of power (frequency, amplitude, and run time) (806).
The controller
will apply optimized power to the transparent conductive layer inside the
glass (808). The
optimized power could be pulsed or not pulsed depending on the operating
conditions. The
process could be repeated after a set adjustable time, possibly between 30
seconds and 10
minutes (810). An optional glass temperature sensor could be used to improve
the accuracy of
the control. The windshield temperature would be allowed to fluctuate within a
certain
tolerance above the dew point to maintain the windshield fog free. This works,
by keeping the
glass above the dew point, so that humidity does not condense onto interior
surfaces like the
windshield or other glass surfaces. The benefit of this feature is that driver
does not need to
intervene, typically after the glass fogs up and then wait a minute or two for
defogging to work.
This feature prevents condensation or fogging on the glass surfaces
automatically so that the
glass does not ever fog up, creating a potentially dangerous situation.
Although the above description makes specific reference to PETD signals used
to
defrost and defog a windshield, it should be understood that although PETD may
be preferable
in some contexts, the systems and methods above contemplate more generally
contemplate the
Date Recue/Date Received 2023-03-28
application of any sufficiently effective intermittent or pulsed signals to
the windshield. For
greater clarity, the term "discontinuous electrical signals" in the context of
electrical signals
applied to the windshield for defrosting or defogging, shall be understood as
including both
intermittent signals and pulsed signals.
Although the method of FIG. 8 has been described in the context of preventing
condensation on a vehicle windshield, it should be understood that the above
teachings are
equally applicable to keeping other surfaces of a vehicle free from unwanted
condensation,
including but not limited to side glass, rear glass, camera lenses, LiDAR,
headlamps, ... etc.
As explained before, the defrost/defog controller tests the resistance of the
windshield
system prior to and during defrosting and defogging operations to guard
against unsafe
operation, safely and cost-effectively. This is particularly useful in the
case of windshields,
since problems can develop prior or during the defrosting process, such as a
new chip in the
windshield or the widening of a previously-minor crack, all of which would
affect the
resistance of the system. Since this layer could be 1 to 3 layers (e.g.,
Glass, PVB, glass) from
the exterior surface, significant damage to the windshield will be necessary
to damage the
conductive layer. Here, we describe a new method to detect that a windshield
has significant
damage, typically more than a surface chip or surface crack. When we detect
this, we can
provide an output to alert the driver and automaker that the windshield needs
replacement. FIG.
9 shows the flowchart of the crack detection reporting feature. Using the
safety systems
described earlier, a crack in the windshield can be detected (902) and
reported to the driver,
dealer, and OEM that the windshield needs to be replaced. The OEM can
communicate to the
dealer that the glass needs to be repaired and enable the dealer to schedule a
windshield
replacement service appointment when the replacement windshield has been
received and the
repair shop has an open service time available. This will increase driving
safety and the chance
of further damage to the windshield. Once a crack is detected with the
defrost/defog controller,
a signal will be sent to the vehicle CAN Bus with an error message or a
Diagnostic
Troubleshooting Code (DTC) (904). This DTC error message can communicate to
the driver,
the dealer, and the OEM, the need for a replacement windshield. To notify the
driver, this can
be done via an onboard service message to the car's driver display and/or a
phone app for that
vehicle (906). The DTC code can be sent to the OEM via their onboard
diagnostics systems that
communicate via cellular telematics (e.g., 5G networks) (910) or other methods
to notify them
of the need so that they can contact a dealer, or other service provider, and
allow them to notify
16
Date Recue/Date Received 2023-03-28
the driver to replace the windshield (908). The dealer can also allow the
vehicle owner to
schedule the windshield replacement when the service part is at the dealer and
when there is
open service time.
Although the method of FIG. 9 has been described in the context of replacement
or
repair of vehicle windshields having associated defrosting and/or defogging
systems, it should
be understood that the above teachings are equally applicable in the context
of replacement or
repair of other vehicle surfaces or components comprising them, having similar
associated
defrosting and/or defogging systems. Such surfaces of the vehicle include, but
are not limited
to, side glass, rear glass, camera lenses, LiDAR, headlamps, ... etc.
The invention is not intended to be limited to the embodiments described
herein, but
rather the invention is intended to be applied widely within the scope of the
inventive concept
as defined in the specification as a whole including the appended claims.
17
Date Recue/Date Received 2023-03-28
