DESC:Form 2
The Patent Act 1970
(39 of 1970)
AND
Patent Rules 2003
Complete Specification
(Sec 10 and Rule 13)
Title
Method and System for Detecting Quantum of Battery
Discharge in an electric vehicle
Applicant(s) Vogo Automotive Pvt. Ltd.
Nationality India
Address
#483, 17th Cross, 27th Main Road, Sector 2, HSR Layout,
Bengaluru-560102, Karnataka, India.
The following specification particularly describes the invention and the manner in
which it is to be performed.
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DESCRIPTION
FIELD OF INVENTION
[0001] Embodiments of the present disclosure relate generally to battery voltage sensing device
and more specifically to a method and system for detecting quantum of battery discharge in an
electric vehicle.
RELATED ART
[0002] In an electric vehicle, precise monitoring of the state of the battery charge is necessary for
efficient functioning of an energy storage system as well as to determine the distance travelled by
the electric vehicle. It is also necessary to determine a precise value for the charging and/or
discharging the battery so that it helps in analyzing a quantum of charge dissipated from the
battery for a particular ride.
[0003] In order to determine the quantum of battery discharge in a vehicle, there are various
methods disclosed in the prior art. A well-known and widely implementing method for assessing
the state of charge in a battery comprises calculating state of charge from the total value of the
charge and the value of discharged voltage and then evaluating the state of charge from voltage
divider circuit voltage of the battery. Conventionally, the state of charge is estimated by voltage
divider circuit voltage in standby mode based on the measured electric current and the measured
voltage using an equivalent circuit model. However, internal resistance of the resistors used in
the circuit significantly alters the accuracy in determining the state of charge which results in
erroneous or inaccurate values of the distance travelled by the vehicle. In case of a rented
vehicle, accurate state of charge and the distance travelled by the vehicle plays a prominent role
in determining the payment dues.
[0004] Hence, there is a need for an efficient and robust system for accurately determining state
of charge of the battery in a vehicle.
SUMMARY
[0005] According to an aspect of the present disclosure, a method (301) of determining a
quantum of a battery discharge in a vehicle comprising, checking (304) the status of ignition
switch, determining (306) a first voltage divider circuit voltage of the battery at a first time,
determining (308) a first state of charge of the battery based on first voltage divider circuit
voltage at the first time, checking (310) ignition status of the vehicle, determining (312) a second
voltage divider circuit voltage of the battery at a second time, determining (314) a second state of
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charge of the battery based on second voltage divider circuit voltage at the second time, and
computing (316) the remaining state of charge of the battery in the vehicle, wherein the
remaining state of charge of the battery is computed by determining a unique multiplication
factor based on input and output voltages in the voltage divider circuit such that an accurate
quantum of the battery discharge is determined for each ride of a vehicle.
[0006] Several aspects are described below, with reference to diagrams. It should be understood
that numerous specific details, relationships, and methods are set forth to provide a full
understanding of the present disclosure. One who skilled in the relevant art, however, will readily
recognize that the present disclosure can be practiced without one or more of the specific details,
or with other methods, etc. In other instances, well-known structures or operations are not shown
in detail to avoid obscuring the features of the present disclosure.
BRIEF DESCRIPTION OF DRAWINGS
[0007] FIG. 1 is a block diagram illustrating a system for determining a quantum of a battery
discharge in a vehicle in an embodiment of the present disclosure.
[0008] FIG. 2 is an example voltage divider circuit used within the system of the present
disclosure.
[0009] FIG. 3 is a flowchart illustrating a method of determining a quantum of a battery discharge
in a vehicle in another embodiment of the present disclosure.
[0010] FIG. 4 is a flowchart illustrating the steps involved in detecting battery replacement based
on the quantum of battery discharge in yet another embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE PREFERRED EXAMPLES
[0011] FIG. 1 is a block diagram illustrating a system (101) for determining a quantum of a
battery discharge in a vehicle in an embodiment of the present disclosure. As shown there, the
system (101) comprises a processor 110, a memory unit 120, a state of charge detector 130, a
user interface 140 and vehicle built-in components 150.
[0012] The processor 110 in the system 101 is configured to execute instructions to perform
various mathematical and control operations. The processor 110 comprises one or more
processors or processor cores operating in conjunction to execute multiple instructions
sequentially or simultaneously. The processor 110 comprises processors or cores customized to
efficiently perform specific tasks, such as one or more Digital Signal Processing (DSP) cores,
math coprocessors etc. In one embodiment, the processor 110 is configured to perform operations
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related to components 120 through 150 by executing a respective set of instructions (programs)
stored in. In an embodiment, the processor 110 receives data from other elements 120 through 150
in the system 101 and performs various operations such as signal processing, image processing, on
the data received to generate a plurality of parameters, notifications, and alerts. Further, the
processor 110 may transfer the data thus collected from the other elements 120 through 150 of the
system 101 through a wireless transceiver to an external electronic device/vehicle unit/central
server. The processor 110 may save the data received from the other elements in the memory unit
120 for further processing or while processing.
[0013] The memory unit 120 is configured to store data and instructions (e.g., one or more
programs) for execution by the processor 110. The memory unit 120 provides a direct interface
with other components in the system 101. The memory unit 120 comprises, but is not limited to,
different types of Read Only Memory (ROM), Random Access Memory (RAM), external
memory disks, removable disks, flash, caches and data cards.
[0014] The state of charge detector 130 detects an accurate battery level and provide details such
as initial battery charge before ignition, dissipation of charge while the battery is in use, rate of
discharge of the battery, remaining state of charge leftover after using the battery and the like.
These details are computed or determined based on a preprogrammed algorithm that works in
conjunction with the processor 110 and the other elements 130 through 150. Further, the state of
charge detector 130 may communicate with an external device or an external server through a
wireless communication channel.
[0015] In an embodiment, the voltage divider circuit provides an accurate output by eliminating
error factor due to inherent tolerance of the resistors. The processor in the system 101 detects Vout
from the R1 and R2 of the resistors based on the following equation,
Vout = Vin [(R2)/(R1+R2)]
In an embodiment, the processor detects the Vout only in terms of digital value i.e., ADC.
[0016] Every voltage divider circuit needs to be calibrated for providing an output wherein the
calibration needs to connect to a known input voltage so that a multiplication factor is
determined. The multiplication factor is determined based on the following equation,
MF = Vout/Vin,
Wherein MF is the multiplication factor, Vout is an output voltage that is detected by the
processor, Vin is a known voltage source for calibration. In an embodiment, the determined
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multiplication factor is stored in the memory of the system and may be used for further
computation of voltage.
[0017] The user interface 140 is configured to display various parameters that are determined by
the processor 110 as well as the state of charge detector 130. In an embodiment, the user
interface 140 enables a person skilled in the art to input necessary information or instructions that
are required for the processor 110 and the state of charge detector 130.
[0018] The vehicle built-in components 150 detects condition and status of the vehicle, like
ignition on/off, engine rpm, speed, load, cabin temperature, occupancy, engine temperature, fuel
etc. In one embodiment the vehicle built in components 150 are interfaced to the state of charge
detector 130 through a communication bus, thus, making it a part of the vehicle. The
communication bus may be data interface lines like CAN bus or any other proprietary vehicle bus
made available for interfacing the vehicle built in components 150. The data and profile of the
vehicle may also be transferred on the CAN bus to the processor 110. The profile of the vehicle
may comprise engine type, make, power, braking, fuel type and analysis, gear assembly, axle
weight, or any data from OBD or telematics.
[0019] FIG. 2 is an example voltage divider circuit used within the system of the present
disclosure. As shown in the figure, the voltage divider circuit 201 comprises a couple of resistors
210 and 220 (say R1 and R2 respectively) that are either connected in series or parallel to each
other within the circuit 201. In the voltage divider circuit 201, the voltage is divided across two
resistances. The voltage divider circuit 201 is configured in such a way that the voltage across one
of the resisters 210 and 220 never increases a predetermined voltage range. In an embodiment, 1M
and 39k resistors (210 and 220) are employed in the present disclosure. The 1M resistor 210 is
mainly used to limit the current, as the circuit 201 mainly deals with voltage calculations and not
current. A desired resistor ratio is selected such that, even if the input voltage battery varies from
5V to 100V, the circuit 201 is designed in such a way that, the output always be in the voltage
sensing range of the micro-controllers and processors. Thus, the voltage divider circuit 201 is used
in order to sense the battery level of the vehicle. A communication protocol is developed in such a
way that, when the output voltage (Vout) is multiplied with a multiplication factor (MF), we get
back the supply/input voltage (Vin). In an embodiment, Vout is in terms of ADC.
[0020] However, the output i.e., battery level of the vehicle from the voltage divider circuit 201 is
inaccurate when tolerance values of the resistors are considered. If the tolerance values of the
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resistors are considered, each of the circuit parameters differ because the tolerance values vary
from resistor to resistor which in turn leads to few percentages of errors. Considering the tolerance
of the resistors, a novel, efficient and robust method for determining accurate battery level of the
vehicle is disclosed in the present disclosure wherein the method is described in the following
figures.
[0021] FIG. 3 is a flowchart illustrating a method (301) of determining a quantum of a battery
discharge in a vehicle in another embodiment of the present disclosure. The flowchart starts at
302. In step 304, the status of the ignition switch in the vehicle is determined. If the ignition
switch is turned on, the flowchart moves to step 306 or else to step 304. In an example, the
ignition status of the vehicle may be determined by vehicle built-in components and the
processor that communicating to each other within the system.
[0022] In step 306, a first voltage divider circuit voltage of the battery is determined at a first time.
In an example, the first circuit voltage of the battery is determined by using the following equation
after ignition switch of the vehicle is turned on.
Vout = [(Vin*R2)/(R1+R2)]*[1+{(52/27)/(?R2/R2)}], (1)
wherein, Vout is the output voltage i.e., the remaining state of charge, Vin is an input voltage, R1,
R2 represents the 1M and 39k resistors respectively and ?R2 is the inherent tolerance of the
resistor.
[0023] In step 308, a first state of charge of the battery is determined based on the first circuit
voltage at the first time. In an example, the state of charge of the battery is determined by
computing the variation of first voltage divider source voltage and the dissipated charge of the
battery when the ignition switch is turned off. In step 310, ignition status of the vehicle is
determined in a similar way to that of the step 304.
[0024] In step 312, a second circuit voltage of the battery is determined at a second time. In an
example, the second circuit voltage of the battery is determined by using the same equation (1)
after a predetermined period of time or at the time when the ignition switch of the vehicle is
turned off.
Vout = [(Vin*R2)/(R1+R2)]*[1+{(52/27)/(?R2/R2)}], (1)
wherein, Vout is the output voltage i.e., the remaining state of charge, Vin is an input voltage, R1,
R2 represents the 1M and 39k resistors respectively and ?R2 is the inherent tolerance of the
resistor.
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[0025] In step 314, a second state of charge of the battery is determined based on the second
circuit voltage at the second time. In an example, the state of charge of the battery is determined
by computing the variation of second voltage divider source voltage and the dissipated charge of
the battery when the ignition switch is turned off.
[0026] In step 316, the remaining state of charge of the battery is computed by considering the
inherent tolerances of the resistors in the voltage divider circuit as mentioned in the equation (1) in
steps 306 and 312. In an embodiment, an error value in the battery index due to inherent tolerance
for each and every ride of a vehicle is determined by using the equation [1+{(52/27)/(?R2/R2)}],
when 1M and 39k resistors are employed in the voltage divider circuit. The flowchart ends at 318.
Thus, accurate value of the battery charge level in a vehicle is determined by considering the
inherent tolerance values of the resistors.
[0027] FIG. 4 is a flowchart illustrating the steps involved in a method (401) of detecting battery
replacement based on the quantum of battery discharge in yet another embodiment of the present
disclosure. In step 402, a battery charge level in a vehicle is determined from the voltage divider
circuit employing 1M and 39k resistors. In an embodiment, the battery charge level is determined
by considering the tolerance values of the resistors as disclosed in the FIG. 3.
[0028] In step 404, net energy extracted from the battery is monitored by vehicle built-in
components and the processor wherein all the parameters related to net energy extraction are
stored in the memory unit.
[0029] In step 406, available or remaining energy in the battery is determined and updated within
the system based on the first and second state of charge computed at the first and second time
from the voltage divider circuit of the battery unit.
[0030] In step 408, the battery is fully loaded with external power source and the charge level of
the fully loaded battery is determined by considering the tolerances of the resistors in the voltage
divider circuit.
[0031] In step 410, the measured charge of the fully loaded battery is compared with an expected
charge level that is pre-programmed or stored within the memory unit of the system to detect the
battery replacement. In case the comparison between the measured charge and the expected
charge is more than a threshold value of the pre-programmed parameter, the processor
communicates the detection of replacement of battery to an external device or server or may be
communicated to the user interface within the system.
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[0032] While various embodiments of the present disclosure have been described above, it should
be understood that they have been presented by way of example only, and not limitation. Thus, the
breadth and scope of the present disclosure should not be limited by any of the above-discussed
embodiments but should be defined only in accordance with the following claims and their
equivalents. ,CLAIMS:CLAIMS
I/We Claim,
1. A method (301) of determining a quantum of a battery discharge in a vehicle comprising:
checking (304) the status of ignition switch;
determining (306) a first voltage divider circuit voltage of the battery at a first time;
determining (308) a first state of charge of the battery based on first voltage divider circuit
voltage at the first time;
checking (310) ignition status of the vehicle;
determining (312) a second voltage divider circuit voltage of the battery at a second time;
determining (314) a second state of charge of the battery based on second voltage divider
circuit voltage at the second time; and
computing (316) the remaining state of charge of the battery in the vehicle,
wherein the remaining state of charge of the battery is computed at the first time as well as
the second time by determining a unique multiplication factor based on input and output
voltages in the voltage divider circuit such that an accurate quantum of the battery discharge
is determined for each ride of a vehicle.
2. The method as claimed in claim 1, wherein the voltage divider circuit of the battery in the
vehicle comprises two resistors with known inherent tolerances that are connected either in
series or parallel.
3. The method as claimed in claim 2, wherein the resistors used in the voltage divider circuit of
the battery comprises 1M and 39k resistors.
4. The method as claimed in claim 3, wherein the voltage divider circuit provides an accurate
output by eliminating error factor due to inherent tolerance of the resistors such that the
unique multiplication factor is determined while calculating the battery voltage as
MF = Vout/Vin (known),
in that, MF represents unique multiplication factor, Vout represents output voltage
determined by a processor and Vin(known) is a known input voltage.
5. The method as claimed in claim 4, wherein the remaining state of charge of the battery in
the vehicle is computed by using the following equation,
Vout = [(Vin*R2)/(R1+R2)]*[1+{(52/27)/(?R2/R2)}],
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in that, Vout is the output voltage i.e., the remaining state of charge, Vin is an input voltage,
R1, R2 represents the 1M and 39k resistors respectively and ?R2 is the inherent tolerance of
the resistor.
6. The method as claimed in claim 4, wherein battery capacity and rate of charge in the battery
are computed by determining variation in the remaining state of charge of the battery
computed at the first time and the second time.
7. A method, system and apparatus providing one or more features as described in the
paragraphs of this specification.