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Sommaire du brevet 2632513 

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(12) Brevet: (11) CA 2632513
(54) Titre français: SYSTEME DE CHARGE A DISTANCE DE BATTERIE AVEC REGLAGE DYNAMIQUE DE TENSION, ET METHODE D'UTILISATION
(54) Titre anglais: REMOTE BATTERY CHARGING SYSTEM WITH DYNAMIC VOLTAGE ADJUSTMENT AND METHOD OF USE
Statut: Réputé périmé
Données bibliographiques
Abrégés

Abrégé français

Dans un système de charge de batterie à distance comprenant un circuit de charge, il y a toujours une perte de tension en raison de résistances inhérentes dans le système attribuables à des éléments comme des connecteurs et des conducteurs. Ces résistances créent des pertes de tension dans le système, ce qui entraîne une augmentation considérable des temps de charge. La présente invention compense les pertes de tension dans le système en générant une tension d'ajustement dynamique durant la période de charge. Un circuit translateur de tension est utilisé pour mesurer la tension et le courant de sortie du circuit de charge au cours d'une pluralité de périodes de temps incrémentielles durant la période de charge et calculer un signal proportionnel aux changements dans la tension et le courant de sortie au cours de la période de temps incrémentielle. Le signal est alors appliqué au circuit de charge pour compenser toute perte de tension.


Abrégé anglais

In a remote battery charging system comprising a charging circuit there is always a voltage loss due to inherent resistances in the system from such things as connectors and conductors. These resistances create voltages losses in the system such that charging times are increased substantially. The present invention compensates for voltage losses on the system by generating a dynamic adjustment voltage over the charging period. A voltage translator circuit is used to measure charging circuit output voltage and current over a plurality of incremental time periods during the charging period an calculate a signal proportional to changes in output voltage and current over the incremental time period. The signal is then applied to the charging circuit to offset any voltage losses.

Revendications

Note : Les revendications sont présentées dans la langue officielle dans laquelle elles ont été soumises.


CLAIMS
1. A remotely operated dynamically-compensated battery charging system having
an dynamic voltage
source having a system output voltage V o and a system output current l o for
charging at least one
battery having a maximum voltage V satt over a charging time period T, said
system comprising:
a. a positive conductor and a ground conductor for connecting said at least
one battery to the
system, wherein said positive and ground conductors have an undetermined
aggregate, and
dynamic inherent resistance R i causing a dynamic inherent voltage loss V i;
b. a microprocessor for measuring changes to I o(dl o /dt) and changes to V
o(dV o /dt) caused by R i,
over incremental time periods t;
c. said microprocessor generating a signal S proportional to one of dV o /dt
and dI o /dt;
d. a voltage translator circuit for receiving said signal S and calculating an
incremental offset
voltage V off/dt;
e. said voltage translator circuit adding V off/dt to V o thereby dynamically
compensating for V,
over charging period T.
2. The system of claim 1 wherein T comprises a T cc and a T cv during which
times the system is in a
constant current mode and a constant voltage mode respectively and a
transition point between T CC and
T cv, so that:
a. during T CC V off is zero:
b. at said transition point and during T cv point the microprocessor:
i. measures V o during time periods t;
ii. calculates dV o /dt;
iii. measures lo during said time periods t:
iv. calculates dl o /dt:
v. calculates changes in R i (dR i /dt) subtracted from dV o /dl o;
vi. calculates V off /dt as dR i/dt X l o: and,
23

c. wherein the voltage translator circuit adds V off /dt to V o the result
being that V o is always
greater than V Batt during T cv.
3. The system of claim 2 wherein the microprocessor includes a first sub-
program to reduce V o during T cc
so that V o plus V off is less than that V Batt.
4. The system of claim 3 wherein the microprocessor includes a second sub-
program to sum V off and V o
during T cv so that V o is always greater than V Batt.
5. The system of claim 1 wherein the system has an undetermined, aggregate and
dynamic resistance
R sys causing a dynamic inherent system voltage loss V sys and wherein the
least one battery includes a
safety thermistor having an R therm said system further comprising:
a. a current limiter connected between the dynamic voltage source the positive
conductor;
b. a current monitor connected between the dynamic voltage source and the
ground conductor;
c. said microcontroller connected to a third conductor through an A/D
converter and wherein
said third conductor has a biasing current source;
d. wherein said safety thermistor is connected to the microprocessor by the
third conductor
having a resistance R3 and a biasing current I bias wherein R3 is negligible
compared to R therm and
I bias is negligible compared to I o and wherein l bias and R3 produce a
voltage V3 at said
analogue/digital converter;
e. wherein when l bias is zero. R3=R sys so that said microcontroller
calculates V off as a function of
R sys and adds V off to V o.
6. The system of claim 5 wherein when the positive conductor comprises a
single wire and the ground
conductor comprises a first and a second parallel wires, the result being that
the resistance in the
positive wire is twice the resistance in any of said first and said second
wires.
7. The system of claim 6 wherein the at least one battery comprises a
thermistor and the
microprocessor comprises a mathematical summing node in series with a current
monitor and an A/D
converter connected to said thermistor by a third conductor having similar
resistance to the positive and
ground conductors and wherein said current monitor transmits the magnitude of
dl o/dt to said
mathematical summing node where it is converted into a control signal S' for
transmission to the
24

adjustable voltage source to determine V off/dt and adjust V o dynamically
over charge time T in order to
optimize l o and wherein the microprocessor controls a bias current in the
third conductor for battery
temperature measurement, so that when the microprocessor terminates said bias
current, it is able to
measure a voltage loss in the third conductor and calculate V off as twice
said voltage loss in the third
conductor.
8. A method of dynamically compensating a battery charging system having a
charging circuit for
generating a dynamic output voltage V o and a dynamic output current l o for
charging an at least one
battery, said at least one battery having a thermistor and a predetermined
maximum battery voltage
V Batt said method comprising the steps of:
a. connecting said at least one battery to said charging circuit by a positive
conductor and a
ground conductor wherein said positive and ground conductors have an aggregate
inherent
resistance R i causing an aggregate voltage loss V i at a current level of I o
b. connecting said thermistor between a second ground conductor and a third
conductor;
c. connecting a microprocessor to said third conductor:
d. connecting an A/D converter serially between said third conductor and said
microprocessor:
e. applying a bias current I bias to the third conductor for measuring
resistance within the
thermistor:
f. terminating I bias:
g, measuring a voltage loss V3 in the third conductor:
h. calculating V off based upon V3 such that V off =2V3 : and,
i. dynamically adjusting V o by V off using a voltage translator circuit.
9. A method of dynamically compensating a battery charging system haying a
charging circuit for
generating an dynamic output voltage V o and a dynamic output current I o for
charging an at least one
battery during a time T and a current monitor and a voltage monitor, said at
least one battery having a
predetermined maximum battery voltage V Batt said system having an
approximated aggregate system
resistance R sys said method comprising the steps of:


a. setting said charging circuit to compensate for R sys:
b. connecting a mathematical summing node in series with said current monitor;
c. measuring the magnitude of I o:
d. measuring during time T and at intervals of t, changes in I o:
e. transmitting changes in I o to said mathematical summing node:
f, using the mathematical summing mode to convert the changes in I o into a
control signal S':
and,
g. transmitting said control signal S' to said adjustable voltage source to
adjust V o by a V off based
on changes in I o.
10. The method of claim 9 further comprising the steps of:
a. providing a microprocessor within said charging circuit for measuring
during T, at time
intervals of t, changes to I o and V o;
b. said microprocessor generating a signal S proportional to said changes to I
o and V o;
c. the microprocessor applying signal S to said charging circuit to generate
an variable offset
voltage V off ; and,
d. the microprocessor summing V off and V o during a constant current charging
mode so that the
sum is always less than V Batt.
11. A method of dynamically compensating a battery charging system having a
charging circuit for
generating an dynamic output voltage V o and a dynamic output current I o for
charging an at least one
battery during a time T and a current monitor and a voltage monitor, said at
least one battery having a
predetermined maximum battery voltage V Batt said method comprising the steps
of:
a. adding a temperature sensitive resistor to said at least one battery for
battery temperature
measurement;
26


b. connecting said temperature sensitive resistor between a second ground
conductor and a
third conductor wherein said third conductor has a resistance similar to first
positive and second
ground conductors;
c. providing an analogue to digital converter within the battery charger;
d. connecting said analogue to digital converter between the third conductor
and the
microprocessor;
e. applying a bias current to the third conductor for measuring resistance
within the
temperature sensitive resistor;
f. terminating said bias current;
g. measuring aggregate voltage loss V1 in the third conductor;
h. applying said V1 to the first positive and second ground conductors: and,
i. calculating variable offset voltage V off based upon the VI, in the first
positive and the second
ground conductors; and,
j. adjusting V o by V off.
12. A method of dynamically compensating a battery charging system having a
charging circuit for
generating a dynamic output voltage V o and a dynamic output current lo for
charging an at least one
battery, said at least one battery having a thermistor and a predetermined
maximum battery voltage
V Batt said method comprising the steps of:
a. connecting said at least one battery to said charging circuit by a positive
conductor and a
ground conductor wherein said positive and ground conductors have an aggregate
inherent
resistance R i causing an aggregate voltage loss V i at a current level of I
o
b. connecting said thermistor between a second ground conductor and a third
conductor;
c. connecting a microprocessor to said third conductor:
d. connecting an A/D converter serially between said third conductor and said
microprocessor:
27

e. applying a bias current I bias to the third conductor for measuring
resistance within the
thermistor:
f. terminating l bias:
g. measuring a voltage loss V3 in the third conductor:
h. calculating V off based upon V3 such that V off =2V3: and,
i. dynamically adjusting V o by V off using a microprocessor.
28

Description

Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.


CA 02632513 2008-05-26
INVENTION TITLE
Remote Battery Charging System with Dynamic Voltage Adjustment and Method of
Use
DESCRIPTION
[Para 1] Background of the Invention.
[Para 21 Different rechargeable battery technologies require different
charging techniques.
A popular battery charging technology is called CCCV or Constant Current
Constant Voltage
charging. This charging technique uses a controlled current to recharge the
battery during
the first phase of charging. As the battery nears fully charged the charger
voltage reaches a
point where it is limited and the current is allowed to fall. This method of
charging is most
commonly used in ion-exchange systems such as Lithium Ion based batteries.
[Para 31 Systems currently in use fall into two broad categories, hardware
based "dumb"
chargers which use discrete circuitry to control the CCCV system, or "smart"
chargers which
communicate with the battery through a digital communication path, or use four-
wire
voltage sensing at the battery terminals to precisely set the current or
voltage outputs from
the charge system.
[Para 4] Dumb chargers have the advantage that they are very low cost and are
easier to
develop. The current is measured and regulated as it exits from the charger
system and the
voltage is measured at the output of the charger system. The disadvantage of
the dumb
charger system is that it works best when closely coupled with the battery
itself. Therefore
operating a dumb charger in a housing that is separated from the battery (such
as a charger
cradle for a phone) results in a voltage difference between the output
terminals of the
charger and the battery itself. This can result in longer charge times and
reduced charge
capacity as the battery charging may terminate early.
Page 1 of 25

CA 02632513 2008-05-26
[Para 5] Dumb chargers have been improved by implementing a four-wire
connection, in
this case charge current to the battery is provided on two wires, and the
voltage at the
battery is measured and returned to the charger on two separate wires. This
allows voltage
drop in the wires to be compensated for in a very precise way. A four wire
system is very
accurate and fast at charging the battery and can be used in cases where the
charger is
separated from the battery by long wires. One disadvantage of this system is
the added cost
and complexity of the wiring and connectors which now have double the number
of
conductors. A second disadvantage of this system is poor safety as problems
with the
returned voltage signal such as broken wires, or current leakage such as from
moisture on
the connector, can cause the charger system to mistakenly output too high a
voltage.
[Para 6] When Lithium based batteries are charged with too much voltage, even
just 1%
higher than their normal rating, their chemistry can become unstable and in
extreme cases
the batteries may become hot, vent or even catch fire.
[Para 7] Smart charger systems have the advantage that the battery voltage,
charge state
and current can be read digitally over a communication bus, therefore
resulting in the
highest level of safety possible. Charge current can be maximized, thereby
reducing charge
time. Loss of digital communication can be used as a signal to the charger to
disable
charging completely which also improves safety. The principle disadvantages of
a smart
system lie in the cost and complexity. Development time of a smart system
tends to be
quite long, the system requires multiple micro-controllers (one in the battery
and one in the
charge system at a minimum) and the number of connections required to the
battery is
high, often as many as 5 total connections. A further disadvantage of the
system lies in the
reliance on multiple micro-processors each running embedded software which may
have
design bugs that could result in an unsafe condition.
[Para 8] There exists a need for a system that provides rapid charging in a
CCCV based
system without sacrificing safety, and without increasing the number of
connections
Page 2 of 25

CA 02632513 2008-05-26
required, especially when used to charge a battery through long wires. There
further exists
a need for a system that fills the void between a completely "dumb" charging
system and a
completely "smart" charging system.
Page 3 of 25

CA 02632513 2008-05-26
[Para 9] Summary of the Invention
[Para 1 01 In a preferred embodiment of the invention there is provided a
system that,
through the use only of discrete hardware elements and no software control,
can improve
the performance of a dumb charging system that connects to a battery that is
separable
from the charging system through only two long wires, with no remote sensing
of any kind.
[Para 11]The preferred embodiment uses a voltage translator circuit that
monitors the
output current of the charging circuit and uses this signal to modify the
output voltage with
a variable offset which will partially compensate for voltage loss in the
wires and connectors
leading to the battery. In particular the variable offset is proportional to
charging current
and will reduce to zero volts before the charging current reduces to zero
amps, in this way
proper accuracy levels are maintained at the termination of charging. In this
system, the
amount of compensation must be less than or equal to the expected requirements
of the
wires and connectors leading to the battery, but the precise value cannot be
determined,
and therefore the compensation will not be as good as an ideal four-wire
sensing system.
We call this a Blind Compensation Charger System because the amount of
compensation is
fixed at a compromise level.
[Para 1 2] In an alternative embodiment of the invention, a microprocessor is
incorporated
which monitors the charging current and/or voltage and can modify the output
voltage
and/or current of the charging circuit thereby increasing flexibility of the
dynamic
adjustment. The microprocessor has the ability to apply one set of charge
parameters and
measure the output, it may then set a second set of charge parameters and
measure the
output changes to determine the compensation required to dynamically adjust
the system in
a way that can closely match the performance and control normally associated
with a four-
wire battery charger system. We call this a Dynamically Compensated Charger
system.
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CA 02632513 2008-05-26
[Para 13] In still another embodiment of the invention, a microprocessor is
used to sense the
battery pack temperature through a temperature sensitive resistor located
inside the battery
pack and electrically connected to a third battery pack connection wire. The
system also
uses said third battery pack connection to sense the true voltage drop between
the charger
system and the battery pack on one wire. Very little current flows through
this third wire
which allows it to sense the offset on the other high-current carrying wires
leading to the
pack. By doubling this sensed voltage drop on one wire and adding the offset
to the output
voltage of the charger, a further improvement in charging time and voltage
accuracy can be
gained at the expense of a third connection to the battery pack, which is
often incorporated
for thermal safety in many situations and therefore is not seen as an
additional cost in most
cases. The use of a single wire for compensation is safer than a dedicated
sense wire
because the reliability and resistance of the connections are tested when this
connection is
used for its original function of measuring temperature. If this third wire is
damaged or
making a poor connection, this will be measured as part of the temperature
sensor's
resistance and will therefore be interpreted as a change in temperature. In
the case of a
standard 10K NTC Thermistor, an open wire will be interpreted as an extremely
cold battery
which will result in charging being disabled. Compensation through a third
wire connection
has been implemented in other products and technologies as a way to estimate
voltage
drop in a system which would normally have four wires. However, the use of a
connection
that is normally used for temperature monitoring, and multiplexing the use of
this third
connection between both functions, and relying on the temperature monitoring
function to
also verify the reliability of the connection is unique. We call this a
Multiplexed Third-Wire
Compensated Charger System.
Page 5 of 25

CA 02632513 2008-05-26
[Para 1 4] Objects and Advantages of the Invention.
[Para 1 51 It is an object of the present invention to provide a battery
charging system that
can dynamically adjust its output voltage in a way that is proportional to the
output current
in order to compensate for voltage loss in the wires and connectors leading to
the battery,
without use of sense wires leading to the battery.
[Para 1 6] It is a further object of the invention to provide a battery
charging system that can
dynamically adjust its output current and/or voltage and measure output
current and/or
voltage in a way that allows the required compensation to be calculated and
applied to the
system to compensate for voltage loss in the wires and connectors leading to
the battery,
without the use of any sense wires leading to the battery.
[Para 1 7] It is a further object of the invention to allow a temperature
sensing connection,
normally found in battery packs, to be used in a way that allows voltage loss
in the wires
leading to the battery to be measured, thereby expanding the use of the third
wire leading
to the battery without sacrificing the original intent of the temperature
monitoring third
wire.
[Para 1 8] It is a further object of this invention that the overall safety
and reliability of the
system remain unchanged or be increased when compared to the current state of
the art
systems which rely on multiple processors, digital communications or multiple
sensing
wires leading to the battery pack.
Page 6 of 25

CA 02632513 2013-10-30
REPLACEMENT SHEET
[Para 19] Description of the Drawings.
[Para 201 Figure 1 is a graph of an ideal charger performance for a Lithium
battery.
[Para 21] Figure 2 is a block diagram of a battery connected to a "Dumb"
charger.
[Para 22] Figure 3 is a graph of a charger performance for a "Dumb" charger.
[Para 23] Figure 4 is a block diagram of a Dynamically Compensated Charger
System.
[Para 24] Figure 5 is a block diagram of a Blind Compensated Charger System.
[Para 25] Figure 6 is a graph of a charger based on Blind Compensation.
[Para 26] Figure 7 is a block diagram of a battery which contains a
temperature sensor connected
to a charger based on Multiplexed Third-Wire Compensation.
[Para 27] Figure 8 is a graph of a charger based on Multiplexed Third-Wire
Compensation.
[Para 28] Figure 9 is a graph of the expected charge times for the four
different charging
methods.
[Para 29] Figure 10 is a table showing one method of the invention.
[Para 30] Figure 11 is a table showing another method of the invention.
[Para 31] Figure 12 is a table showing yet another method of the invention.
[Para 32] Figure 13 is a table showing another method of the invention.
[Para 33] Figure 14 is a continuation of Figure 13.
Page 7 of 27

CA 02632513 2008-05-26
[Para 29] Detailed Description.
[Para 30] Referring to Figure 1, a graph (100) showing ideal charger
performance when
connected to a lithium battery. In this case the output voltage Vo (101) of
the charger is
exactly the same as the voltage present on the battery terminals VBatt (101).
In the case of a
two-cell Lithium Polymer battery where the end-of-charge voltage is 8.4 volts
(102), the
desired maximum charge rate is 2 amps and the battery capacity is 2 amp-hours,
the graph
shows what characteristics make this an ideal charger.
[Para 31] The graph is divided into two sections. In the Constant Current (CC
mode) section
(103), the battery voltage is lower than 8.4 volts so the charge current (104)
will be exactly
2 amps. Once the battery reaches 8.4 volts the system enters Constant Voltage
(CV mode)
(105). In an ideal case a "knee" is formed (106) in the graph where the
charging current 10
immediately and rapidly begins to fall. This happens at the point where the
battery voltage
(101) reaches 8.4 volts. The total charge time (T), in this example case where
the applied
charge current lo is equal to the battery capacity, with a lithium polymer
battery could be
around 1.2 hours. It can be easily understood that applying a higher charge
current lo will
result in faster charging, and a lower charge current lo will result in longer
charging. But in
any case, with any charge current, lithium based technologies will still have
two distinct
charge regions as outlined above. In particular, for this example, at the
point where the
system transitions from CC mode to CV mode of operation, the battery capacity
(110) will
be at about 95% and after 1 hour of charging the battery will be at 99.1%
capacity. These
two points will be used for comparison with the other methods that form part
of this
invention. A person skilled in the art will recognize that the exact graph
shape, voltages and
charging times will vary from battery to battery and depending on the battery
technology
being employed. The benefits of the inventions disclosed herein will vary for
different
battery technologies and charge rates and in some cases the results may be
better than
anticipated here, especially with higher charge rates, long charging wires and
shorter
Page 8 of 25

CA 02632513 2008-05-26
charge times. In some cases, especially low charge rates, or where the charger
and battery
are integrated into the same physical housing, the advantages may not be
significant.
[Para 32] Referring to Figure 2, a charging circuit is shown that would
normally constitute
the simplest complete system possible. A battery (200) may be any type of
rechargeable
battery which is connected to a charger (207) through at least two wires and
at least one
pair of connectors. The connectors may be located on the positive terminal
(201) and
negative terminal (202) of the battery (200) or they may be located at the
positive output
(205) and negative output (206) of the charging circuit, or the system may
contain all four
connections. It would be obvious to one skilled in the art that an individual
connection or
wire may be replaced with multiple or larger individual connectors to increase
current
carrying capacity or to decrease voltage losses. Figure 2 also shows two
equivalent
resistances which represent the resistance of the positive wire (203) and the
resistance of
the negative wire (204) as well as any interconnections in series with these
elements. These
resistances are shown schematically and will be distributed along the length
of the wire and
will vary depending on the length, diameter and overall conductivity of the
wire itself. It is
well understood in the art that every wire and every connection will
contribute to the overall
inherent resistance R, found in the system. Therefore the total resistance
between where the
charger monitors it's output voltage and where the battery cells receive
charging voltage is
equal to the sum of all resistances including all four connections (201, 202,
205, 206) and
both wires (203, 204).
[Para 33] Figure 2 also shows the internal details of the charger system. A
constant voltage
source (210) connects to the output terminals (205, 206) through a current
limiter (211).
When the battery (200) voltage \het is less than the constant voltage source
Vo (210), then
current lo will flow through the current limiter (211) up to the maximum value
allowed by
the limiter. If the battery (200) has reached the same voltage as the voltage
source (210)
then the current in the system will be determined by the chemical
characteristics
Page 9 of 25

CA 02632513 2008-05-26
(sometimes called the charge acceptance) of the battery itself and the current
limiter (211)
will not do anything to restrict this current as it falls below the limiting
range.
[Para 34] If the resistances R, shown in Figure 2 were all zero, then this
system would
produce the ideal graph previously shown in Figure 1. However, the system
resistances
mean that additional voltage drops V1 exist in the system resulting in a
difference between
the constant voltage source (210) and the actual voltage presented on the
battery (200)
itself.
[Para 35] The voltage drop can be found by the simple formula of VI = I x Ri
where VI is the
voltage loss, I. is the current flowing and RI is the total resistance in the
system.
Considering a representative system consisting of a 2-cell Lithium Ion battery
pack. The
charging voltage for the pack should be between 8.3 and 8.5 volts for maximum
capacity.
This is a very tight tolerance to reach, but is necessary for many similar ion-
exchange based
technologies. At voltages lower than 8.3 volts this pack may suffer 20% or
more capacity
loss. At voltages higher than 8.5 volts the chemistry inside the battery
begins to become
unstable and therefore safety is compromised, the charger voltage will
therefore normally
be set at 8.4 volts in this example.
[Para 36] It will be appreciated from one skilled in the art that different
battery technologies
will have different thresholds, accuracy and safety requirements.
[Para 37] Further, by example, a battery may require 2 amps of charging
current. It is also
common for removable electrical connections to have 0.05 ohms of resistance
and for a
meter of wire to have 0.1 ohms of resistance. Therefore the total resistance
in a system with
two wires and four connections would be Ri = (2 x 0.1) + (4 x 0.05) = 0.4
ohms. At 2 amps
of current flowing the total voltage drop VI will be 0.8 volts. If the charger
has an output
voltage set at 8.4 volts, then at full current the battery will only "see" 7.6
volts which is too
low for proper charging. The result is that the battery charger current I.
will start to drop off
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CA 02632513 2008-05-26
when the battery is only partially charged and this current drop will be
interpreted as
indicative of a fully charged battery, even though it is only partially
charged.
[Para 38] Figure 3 shows a representative graph (300) of the performance for
the dumb
charger system as shown in Figure 2 when system resistance is taken into
consideration.
The graph is divided into a CC mode section (301) and CV mode section (302).
The CC
mode section lasts for a much shorter time than the section shown in the graph
of Figure 1.
The charge current (303) is shown in this graph as well as the battery
capacity (304). The
charger output voltage (305) is not the same as the battery terminal voltage
(306) due to
the system resistances and charging current. The charger output voltage will
be equal to the
battery terminal voltage only when the charge current has fallen to zero. The
sharp knee of
charger current (106) originally seen in Figure 1 has been replaced with a
soft complex
curve (307) and a long period of reduced current that gradually tapers off to
zero. The
current initially drops off when the charger voltage (305) first reaches the
set point of the
constant voltage source (210) of Figure 2. However, this occurs before the
battery voltage
has reached this level, the result is that the charger transitions from CC to
CV mode at a
point where the battery capacity (304) is only 30% charged (in this example).
The reduced
charge rate results in a much longer charge time of approximately 1.6 hours
for this
example.
[Para 39] Figure 4 shows a block diagram of a Dynamically Compensated Charger
(400)
connected to the same battery (200) using the same wires and connectors (201,
202, 203,
204, 205, 206) previously shown in Figure 2. The Dynamically Compensated
Charger (200)
contains a micro-controller (401) and has an adjustable voltage source (402)
and current
limiter (403). It can be appreciated that one skilled in the art can implement
the adjustable
voltage and current sources in a variety of ways, these may be switched-mode
or linear-
mode regulators, they may be combined in to a single current limited voltage
element or
the order of these elements may be reversed, or a voltage limiter may be used
instead of
Page 11 of 25

CA 02632513 2008-05-26
voltage source. The micro-controller (401) also monitors the output current
using a current
monitor (404) and monitors the output voltage using a voltage monitor (405).
It is
understood that the current monitor may be implemented using a variety of
methods well
understood in the art including a current to voltage converter (resistor),
amplifier, sensor,
coupler, current mirror, hall effect sensor or optically isolated system.
Similarly the voltage
monitor may be implemented using a variety of techniques including voltage
ladders,
dividers, amplifiers, couplers and isolators. If the system is operating in CC
mode, then
there is no need to adjust the voltage or current as the system is presumed to
be supplying
the maximum allowed charge current. At the point where an uncompensated system
would
normally transition to CV mode, micro-controller can perform a check to
determine if the
output voltage may be adjusted in order to safely optimize the charge being
delivered to the
battery. The micro-controller will measure the output voltage and output
current, the
system will then adjust the output voltage by a small amount and repeat the
measurement
of output voltage and current. The difference in voltage is `scIV' and the
difference in current
is 'dl'. The system resistance 'ft' can then be estimated as `dV/d1'. Using
the absolute value
of the charging current 'I', the difference in the charger output voltage and
the actual
battery terminal voltage can be estimated as 'V = IR'. The system desires the
battery to be
charged at a voltage that is appropriate for the chemistry and number of
cells, in this
example we use 8.4 volts. The micro-controller can then adjust the output
voltage of the
system to a level that is higher than the battery by the compensation amount,
in such a way
that the battery terminal voltage remains below 8.4 volts, which is the
maximum allowed
voltage on the battery terminals. The system resistance test can be
periodically repeated to
ensure that accuracy is maintained. As the battery voltage rises to 8.4 volts,
the charger will
enter CV mode, but with the charger set at a voltage that is higher than 8.4
volts. As
charging current drops the compensation voltage will be reduced by the micro-
controller
proportionally which in turn maintains the8.4 volt level at the battery
terminals. To ensure
Page 12 of 25

CA 02632513 2008-05-26
maximum accuracy of the system, it may be desirable to cease providing
compensation
once the charge current has fallen below a certain threshold. Certain limits
on the
compensation limit can also be included to ensure that poor connections do not
result in an
unreasonably high amount of compensation voltage being applied to the
batteries. This
maximum compensation value would be determined on a case by case basis based
on the
maximum expected charge current and resistance values.
[Para 40] From a safety perspective, the dynamically compensated charger
offers superior
safety when compared to a four-wire remote voltage sensed charge system. The
dynamic
compensation system utilizes the same wires and connections that are being
used for
supplying power to the battery, therefore if there is a flaw in these
connectors or wires it
will impact both the delivery of power and the sensing of the power making
error detection
safe and effective. The dynamic compensation system will also be more accurate
as the
system resistance is based on all resistances in the system. A four-wire
system only
compensates for resistances up-to and including the point where the sense-
wires are
connected. The battery pack itself may still contain some residual resistance
sources
including the individual cell connections themselves, any connection wires,
fuses and other
protection circuitry may also impact accuracy.
[Para 41] It would be clear to someone skilled in the art that dynamically
adjusting the
charging parameters based on dynamically varying and measuring the output of
the charger
itself can be accomplished using a variety of methods and parameters. In
particular, the
charger current itself could be varied from zero (cut off) to the maximum
value in a step
function, or other variation levels and wave shapes may be used on both the
current and
voltage set points in order to determine the compensation requirements of the
charger in
order to optimally deliver energy into the battery.
[Para 42] Figure 5 is a block diagram of a Blind Compensated Charger. In this
case the
charger (501) is set with an approximate value of the total resistances
expected to be found
Page 13 of 25

CA 02632513 2013-10-30
in the system, even though it cannot actually see these resistances, hence the
term "Blind" is
used. The resistances would include all of the connectors and wires (501, 502,
503, 504,
505, 506) previously shown in Figure 2. This charger contains a fixed current
limiter (511)
and uses hardware or software means to measure the output current using a
current
monitor (508) and uses that current to modify the output voltage setting for
the voltage
source (509) through a mathematical summing node (510) which could be
constructed from
hardware using resistors and amplifiers, or by software using a
microcontroller. By example,
if the total resistance of the system was expected to be 0.5 ohms, and the
maximum charge
rate was expected to be 2.0 amps, then there is a potential for the output of
the charger to
be 1.0 volts lower than the terminal voltage of the battery (500). Using
hardware or software
the system can measure the output current and convert it at the mathematical
node (510)
into a control signal to the voltage source (509) which causes the output
voltage of the
source to rise by 1.0 volts. In reality a lower voltage would be used to
ensure safe operation.
Additionally, a provision could be made to remove the compensation, or set it
to zero, when
the charge current drops below a certain threshold, this allows the system to
rapidly charge
the battery during the first stages of charging, but to enter a more
conventional, and
therefore safer, mode of constant-voltage charging as the battery reaches a
fully charged
state. The negative wire (507) is shown along with its equivalent resistance.
[Para 433 Figure 6 shows a graph (600) of a Blind Compensated charging system.
The
conventional CC region (601) of the graph Is quite small, much like the non-
compensated
"dumb" charging graph of Figure 3. The system switches over to a compensated
region
(602) at the point where the charger output exceeds the normal set point of
8.4 volts (60.3),
the charger output continues to rise to a maximum value, in this case the
charger set point
is raised 1/10th the value of the current, therefore about 0.2 volts. The
charger voltage
therefore rises to a maximum level (610) of 8.6 volts where it remains until
the end of the
compensation region. The battery voltage (604) continues to rise as it charges
and
Page 14 of 25

CA 02632513 2008-05-26
eventually the voltage difference between the charger voltage (605) and the
battery voltage
(604) is too small for the system to continue to deliver full current. At this
point the charge
current (609) begins to taper off which causes a corresponding drop in the
amount of
compensation causing the charger voltage to also drop. The example shown
assumes the
compensation will be switched off (set to zero) when the charger current falls
below 1 amp;
at this point the charger switches over to a conventional CV mode (606) and
continues
charging the battery with a fixed voltage at the output of the charger of 8.4
volts.
[Para 44] The Blind Compensation method shown here as an example would charge
the
battery capacity (608) to 93.4% after 1 hour which is much better than the un-
compensated
"Dumb" charger, but not as good as the Dynamic Compensated or the Ideal charge

examples.
[Para 45] Figure 7 shows a battery pack system (700) that contains a safety
thermistor (701)
connected in a way that is standard practice in the battery industry. However,
this also
enables its use in a more inventive way, to also create a compensated charger
system called
a Multiplexed Third Wire Compensation system. The thermistor changes
resistance based
on the temperature of the pack and is often used as a backup safety sensor. A
number of
battery standards, including the SMBus Standard provide specific details on
the type and
connection strategy that must be employed for such a sensor. Normally this
resistor is
connected to the battery ground terminal. The third wire (702) which leads to
the thermistor
will have resistance that is similar to the other wires (703, 704) in the
system, however, the
current normally used to read the thermistor, and the magnitude of the wire
resistance
when compared to the resistance of the thermistor itself is quite small. The
pack will also
contain multiple connectors similar to those shown on other figures (not
labeled for clarity).
The Third Wire Multiplexed Charger (710) contains a current limiter (709) and
a current
monitor (711) which connect to a micro-controller (705) which is shown
controlling the
voltage source (706) and connecting to the third wire (702) through an Analog
to Digital
Page 15 of 25

CA 02632513 2008-05-26
(A/D) converter (707) and with a current bias supply (708) which may be
enabled or
disabled. The bias supply can be constructed in a number of ways and
essentially applies a
known current to the third wire which, when combined with the resistance of
the thermistor
in the battery pack will produce a voltage at the A/D converter of the micro-
processor.
[Para 46] When the battery is charging, a voltage drop is generated on the
supply wires
feeding the battery pack. The battery charging current is several orders of
magnitude higher
than the bias current that is used to measure the thermistor resistance. In
particular the
current flowing through the ground wire (704) causes the ground voltage of the
battery
pack to be higher than the ground voltage of the charger. The offset voltage
is a function of
the current flow multiplied by the total connection resistance, including all
connectors, wire
and other sources of resistance in the ground side of the system. If the micro-
processor
turns off the bias supply to the third wire leading to the pack, then this
ground voltage
offset can be read by the A/D converter of the microprocessor through the
third wire (702)
without error. There is essentially no voltage drop on this third wire because
negligible
current will flow in this wire. Depending on the construction of the battery
pack, connector
and wire harnesses, a mathematical formula can easily be created that allows
this ground
offset voltage to be used to also estimate the offset voltage that would be
present on the
positive supply wire (703). In the case where the wire length, size and
connectors are the
same for both of the supply wires, then the ground offset can be assumed to be
equal to
the positive supply offset. In the case where, for example, the ground wire is
composed of
two discrete wires and connectors in parallel, compared to a single wire and
connector for
the positive wire, then clearly the positive wire will have double the
resistance of the ground
wire, and therefore the offset will be approximately double what is measured
on the ground
wire. Combining the measured ground offset with the calculated positive offset
results in an
accurate total compensation voltage which can be applied to the voltage
source. The ground
offset can be periodically measured, especially as the battery nears fully
charged state. The
Page 16 of 25

CA 02632513 2008-05-26
temperature of the battery pack can also be periodically measured on the same
wire by
applying a small, known bias current to the wire which will create an
additional voltage
offset which is proportional to the value of the thermistor resistance, and
therefore the
temperature of the battery pack.
[Para 47] It can be appreciated that in a system where the temperature sensor
was
connected instead to the positive wire (703) or where the temperature sensor
(701) were
composed of a different material such as a thermocouple, the method of
removing the bias
current, reading the voltage drop of one wire (in this case with reference to
the positive
supply instead of the ground) and then mathematically calculating the total
expected
voltage drop in the system would still apply.
[Para 48] Figure 8 shows the expected performance graph (800) for the
Multiplexed Third
Wire Compensation strategy. The battery voltage (801), battery current (802)
and battery
capacity (803) have the same magnitude and shape as the ideal charger graph of
Figure 1.
The only difference is that the charger output voltage (804) is now accurately
compensated
and will actually rise beyond the normal 8.4 volts allowed to charge a two
cell lithium
battery pack. The charger output rises the exact amount required to overcome
the losses in
the connections between the battery pack and the charger. As the battery nears
a fully
charged state the measured voltage offset, and therefore the voltage
compensation applied
to the voltage source is automatically reduced. By the time the battery has
reached a fully
charged state, current has fallen to nearly zero, and therefore the charger
output voltage
become equal to the battery voltage at 8.4 volts. In particular, the charging
current flow in
the CC area (805) of the graph looks identical to the Compensation area (806).
The CV area
of the graph (807) only occurs once the battery is fully charged (current has
reached zero),
which essentially means that the CV portion of battery charging employed by
the current
state of the art systems has actually been eliminated in this invention. It
has been replaced
Page 17 of 25

CA 02632513 2013-10-30
REPLACEMENT SHEET
by the actively compensated area (806), yet the overall charge time is
identical to an ideal (and
therefore previously not-achievable) system.
[Para 49] Figure 9 shows a graph (900) of the battery capacity versus time for
each of the charge
compensation methods presented. The charging parameters of a two cell, 2 amp-
hour battery
pack being charged with an 8.4 volt, 2 amp charger are the same for each
example, yet the time
required to charge the battery pack is different based on the compensation
method chosen. The
originally presented -dumb" charging system (901) is the slowest, requiring
over l .5 hours to
reach 99% capacity, while the Multiplexed Third Wire Compensation strategy
(902) was the
fastest, equivalent in fact to an ideal system (903) at about 1.0 hours to
reach fully charged state.
The Blind Compensation Method (904) is simple to implement without a micro-
controllerand
results in 1.3 hours to reach 99% capacity, this may be a good compromise for
some systems
where a little faster charging is desired. The charging accuracy, and
therefore speed, of the Blind
Compensation method can be improved by accurately characterizing the
resistances that will be
faced in the final system, the example shown here assumed the compensation
value was only
50% of the actual resistance value, therefore representation a large
estimation error.
[Para 50] Existing state of the art lithium charging systems are called
Constant Current
Constance Voltage or CCCV systems. The cases illustrated by the various
compensation
methods outlined in this document are all characterized by a common theme that
a new charging
more with Dynamic Voltage characteristics has been added. Some of the
preferred embodiments
contain elements of CC and DV and CV combined. The final example of a
Multiplexed Third
Wire Compensation system actually eliminates the CV step from active charging;
this can
therefore by expressed as a CCDV charging system.
[Para 51] Referring now to Figure 10 there is shown one method of the
invention for
dynamically compensating a battery charging system having a charging circuit
for generating a
dynamic output voltage and a dynamic output current for charging and at least
one battery
wherein the at least one battery has a then-nistor and a predetermined maximum
battery voltage,
the method comprising the steps of:
200 Connecting said at least one battery to said charging circuit by a
positive
conductor and a ground conductor wherein said positive and ground conductors
Page 18 of 27

CA 02632513 2013-10-30
REPLACEMENT SHEET
have an aggregate inherent resistance, 12.,, causing an aggregate voltage loss
V, at a
current level of I0
204 Connecting said thermistor between the second ground conductor and a
third
conductor
206 Connecting a microprocessor to said third conductor
208 Connecting an AID converter serially between said third conductor
and said
microprocessor
210 Applying a bias current Ibtas to the third conductor for measuring
resistance within
the thermistor
212 TerminatingIbias
214 Measuring avoltage loss V3 in the third conductor
216 Calculating Voff based upon V3 such that Voff=2V3
218 Dynamically adjusting V0 by Voff
[Para 52] Now referring to Figure 11 there is shown steps of a method of
dynamically
compensating a battery charging system having a charging circuit for
generating a dynamic
output voltage and a dynamic output current for charging and at least one
battery during a time T
and a current monitor and a voltage monitor wherein the at least one battery
has a predetermined
maxi tnumvoltage,the systemhasanapproximate aggregate system resistance, the
method
comprising the steps of:
300 Setting said charging circuit to compensate for Rsys
304 Connecting a mathematical summing node in series with said current
monitor
306 Measuring the magnitude of I
308 Measuring time T and at intervals oft, changes in I
Page 19 of 27

CA 02632513 2013-10-30
REPLACEMENT SHEET
310 Transmitting changes in Io to saidmathematic al summing node
312 Using the mathematical summing node to convert the changes in I0
into a control
signal S'
314 Transmitting said control signal S. to said adjustable voltage
source to adjust Vo
by a Voff based on changes in I
[Para 53] Now referring to Figure 12 the method of Figure 11 further comprises
the following
steps
400 Providing a microprocessor within said charging circuit for
measuring during T,
at time intervals oft, changes to Io and Vo
402 Said microprocessor generating a signal S proportional to said
changes to I o and
Vo
404 The microprocessor applying signal S to said charging circuit to
generate an
variable offset voltage Voff
406 The microprocessor summing Voff and Vo during a constant current
charging
mode so that the sum is always less than VBatt
Page 20 of 27

CA 02632513 2013-10-30
REPLACEMENT SHEET
[Para54] Referring now to Figure 13 there is shown a method of dynamically
compensating a
battery charging system having a charging circuit for generating a dynamic
output voltage and a
dynamic output current for charging and at least one battery during a time T
and a current
monitor and a voltage monitor said at least one battery having a predetermined
maximum battery
voltage, the method comprising the following steps
500 Adding a temperature sensitive resistor to said at least one battery
for battery
temperature measurement
502 Connecting said temperature sensitive resistor between said second
ground
conductor and a third conductor wherein said third conductor has a resistance
similar to the first positive and second ground conductors
504 Providing an analogue to digital converter within the battery
charger
506 Connecting said analogue to digital converter between the third
conductor and the
microprocessor
508 Connecting said analogue to digital converter between the third
conductor and the
microprocessor
510 Applying a bias current to the third conductor for measuring
resistance within the
temperature sensitive resistor
512 Terminating said bias c urrent
[Para 55] Referring now to Figure 14 which is a continuation of Figure 13 the
steps continued
are
514 Measuring Vi in the third conductor
516 Applying said V; to the first positive and second ground conductors
518 Cale ulating Voff based upon the Vi, in the positive and the second
ground
conductors
520 Adjusting V, by Voff
Page 21 of 27

CA 02632513 2013-10-30
REPLACEMENT SHEET
[Para 56] Although the description above contains much specificity, these
should not be
construed as limiting the scope of the invention but as merely providing
illustrations of some of
the presently preferred embodiments of this invention. Any digital gates or
signals may be easily
redefined such that they perform similar functions as inverse logic or using
alternate gates or
logic topology. Logic, analog detection and control means may be implemented
using integrated
circuitry, microprocessor control, software and wireless control. Thus the
scope of the invention
should be determined by the appended claims and their legal equivalents.
Page 22 of 27

Dessin représentatif
Une figure unique qui représente un dessin illustrant l'invention.
États administratifs

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États administratifs

Titre Date
Date de délivrance prévu 2014-08-05
(22) Dépôt 2008-05-26
(41) Mise à la disponibilité du public 2009-11-26
Requête d'examen 2013-03-08
(45) Délivré 2014-08-05
Réputé périmé 2020-08-31

Historique d'abandonnement

Il n'y a pas d'historique d'abandonnement

Historique des paiements

Type de taxes Anniversaire Échéance Montant payé Date payée
Le dépôt d'une demande de brevet 200,00 $ 2008-05-26
Taxe de maintien en état - Demande - nouvelle loi 2 2010-05-26 50,00 $ 2010-03-12
Taxe de maintien en état - Demande - nouvelle loi 3 2011-05-26 50,00 $ 2011-05-05
Taxe de maintien en état - Demande - nouvelle loi 4 2012-05-28 50,00 $ 2012-03-16
Requête d'examen 400,00 $ 2013-03-08
Taxe de maintien en état - Demande - nouvelle loi 5 2013-05-27 100,00 $ 2013-03-08
Enregistrement de documents 100,00 $ 2014-01-17
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Taxe de maintien en état - brevet - nouvelle loi 10 2018-05-28 250,00 $ 2018-05-21
Taxe de maintien en état - brevet - nouvelle loi 11 2019-05-27 450,00 $ 2019-08-02
Titulaires au dossier

Les titulaires actuels et antérieures au dossier sont affichés en ordre alphabétique.

Titulaires actuels au dossier
PANACIS INC.
Titulaires antérieures au dossier
CARKNER, STEVE
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Abrégé 2008-05-26 1 19
Description 2008-05-26 19 784
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Dessins 2008-05-26 9 203
Dessins représentatifs 2009-10-30 1 6
Page couverture 2009-11-17 1 37
Dessins 2013-06-06 14 336
Description 2013-06-21 22 867
Revendications 2013-06-21 5 164
Dessins représentatifs 2013-08-02 1 7
Description 2013-10-30 22 884
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Dessins 2013-10-30 15 284
Dessins représentatifs 2014-07-11 1 5
Page couverture 2014-07-11 1 37
Correspondance 2008-07-02 1 58
Cession 2008-05-26 2 85
Correspondance 2010-01-27 1 39
Poursuite-Amendment 2013-06-13 1 29
Courrier retourné 2019-07-29 2 75
Poursuite-Amendment 2013-03-08 1 30
Correspondance 2013-06-03 5 225
Correspondance 2013-06-06 1 14
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Poursuite-Amendment 2013-06-06 12 325
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Poursuite-Amendment 2013-06-21 8 245
Poursuite-Amendment 2013-07-26 1 21
Poursuite-Amendment 2013-08-22 3 97
Poursuite-Amendment 2013-10-30 21 599
Cession 2014-01-17 3 115
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Correspondance 2015-01-08 4 141
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Taxes 2015-05-20 2 92