TECHNICAL FIELD
[0001] The present subject matter described herein, relates to starting of an
electric vehicle. More particularly, the present subject matter provides a system
that starts the electric vehicle by traction battery pack or main battery of 5 f the
electric vehicle when auxiliary battery of the electric vehicle is either fully or
partially discharged.
BACKGROUND
[0002] Background description includes information that may be useful in
10 understanding the present invention. It is not an admission that any of the
information provided herein is prior art or relevant to the presently claimed
invention, or that any publication specifically or implicitly referenced is prior art.
[0003] In vehicles either electric vehicles or gasoline vehicles, auxiliary
battery provides initial power or current for starting of the vehicle. If the auxiliary
15 battery is not charged, the vehicle will not be started by the auxiliary battery. To
start the vehicle, discharged battery is replaced with fully charged battery or
discharged battery is first charged before use. The auxiliary battery may get
discharged due to stray loads of the vehicle, such as head lamps in ON condition,
door remained open, key off condition for long time, direct connection of radiator
20 fan, and use of music system and fan in ignition off condition. Use of electric
appliances of vehicle in ignition off condition, the auxiliary battery supplies
power to the electric appliances that discharge the auxiliary battery.
[0004] In the existing technologies of electric vehicle, the traction battery, i.e.,
main battery charges the auxiliary battery when auxiliary battery is at minimum
25 SOC even when the key is OFF. In this scenario, whenever the auxiliary battery is
at a minimum state of charge (SoC), then upper level control unit wakes up and
3
charges the auxiliary battery when key is OFF. The existing technology has below
mentioned technical dis-advantages and problems:
[0005] First, in case of high voltage traction battery, it is not safe to energize
the high voltage line outside the battery pack, i.e., in the vehicle, when the key is
OFF. This might cause electrocution injuries to operator or user 5 r of the vehicle.
[0006] Second, when key is OFF, if there is additional stray load on auxiliary
battery (which might be because of faulty sensor/door open/headlamps ON), the
auxiliary battery gets discharged. In order to charge up the auxiliary battery, the
energy of traction battery also gets depleted. After some time, both, traction
10 battery as well as auxiliary battery are in discharged condition. This might cause
unwanted energy loss and vehicle traction may not be possible without charging
the vehicle again.
[0007] Third, if above mentioned second scenario happens multiple times, this
may decrease the traction battery life due to increase in Depth of Discharge
15 (DoD%) percentage multiple times. It may also increase the number of cycles
which wastes the cycle life of battery. Traction battery contributes much cost in
electric vehicle, so traction battery should be used for traction only as much as
possible to increase the system efficiency.
[0008] Fourth, if auxiliary battery has poor health, i.e., low state of health
20 (SoH), then the situation may worsen and may increase the occurrence of second
scenario multiple times. Frequent occurrence of second scenario would decrease
the traction battery life and increase the cost of electric vehicle maintenance.
[0009] Therefore, there is a need for a system that can start the vehicle even
when the auxiliary battery is completely drained, or when the auxiliary battery has
25 insufficient power to activate the ECUs, required for vehicle start-up.
4
[0010] Therefore, to avoid above mentioned technical problems, it is required
to stop the charging of auxiliary battery during key off condition of the vehicle. If
the auxiliary battery is not charged, the electric vehicle will not start.
[0011] Therefore, there is a need for a system that can start the vehicle
without using discharged auxiliary battery and charge the discharged auxili5 ary
battery only in key on condition or after starting the vehicle.
OBJECTS OF THE DISCLOSURE
[0012] Some of the objects of the present disclosure, which at least one
embodiment herein satisfy, are listed herein below.
10 [0013] The principal object of the present invention is to provide a system to
start an electric vehicle using traction battery safely.
[0014] Another object of the present invention is to provide a system that can
charge a discharged auxiliary battery after starting the vehicle.
[0015] Another object of the present invention is to provide a system that can
15 increase life of traction battery by charging the auxiliary battery only in key on
condition.
[0016] Another object of the present invention is to provide a system that can
decrease maintenance cost of electric vehicle by increasing life and efficiency of
the traction battery by decreasing number of charging cycles.
20 [0017] These and other objects and advantages will become more apparent
when reference is made to the following description and accompanying drawings.
SUMMARY
[0018] This summary is provided to introduce concepts related to a system for
starting an electric vehicle from a traction battery when auxiliary battery is
25 discharged and unable to start the electric vehicle. The concepts are further
described below in the detailed description. This summary is not intended to
5
identify key features or essential features of the claimed subject matter, nor is it
intended to be used to limit the scope of the claimed subject matter.
[0019] In an embodiment, the present subject matter relates to a system for
starting an electric vehicle from a traction battery when an auxiliary battery is
completely discharged and is unable to start the electric vehicle. The syste5 m
comprises a master battery management system (BMS) coupled with a plurality of
slave battery management system (BMS) of the traction battery pack. Each of
slave BMS from the plurality of slave BMS manages an individual battery module
of the traction battery pack. The master BMS comprises an isolated low power
10 Direct current (DC)-Direct current (DC) converter which is coupled with high
voltage (HV) line and low voltage (LV) line of the plurality of slave BMS to
convert the high voltage (HV) line to low voltage (LV) line and activate an
electronic control module by supplying the low voltage (LV) line to perform a
plurality of safety checks on the electric vehicle when the auxiliary battery is
15 completely discharged. The electronic control module activates the master BMS
after receiving complete safety check inputs. If the vehicle is safe to start, the
electronic control module activates the master BMS. The master BMS starts the
electric vehicle based on inputs received from the electronic control module by
turning ON P relay and N relay to allow transmission of High Voltage (HV)
20 power from the traction battery pack to power electronic module (PEM) and other
HV auxiliaries (such as high power DC-DC converter, compressor, heater etc.).
[0020] In an aspect, the electronic control module may comprise an electronic
control unit (ECU), Body Control Module (BCM), Telematics Control Unit
(TCU), Battery Management System (BMS), etc., to perform all safety checks
25 which are necessary for starting the electric vehicle.
[0021] In an aspect, the low power DC-DC converter is activated when
auxiliary battery is discharged below a threshold level (Thv) and a switch is
pressed.
6
[0022] In an aspect, the auxiliary battery is discharged below the threshold
level (Thv) or the electronic control module is not able to be powered by the
auxiliary battery.
[0023] In an aspect, a switch block having diode and parallel relay provided to
supply the low voltage (LV) power from the low power DC-DC converter to th5 e
electronic control module only and not to auxiliary loads or auxiliary battery.
[0024] In an aspect, the isolated low power Direct current (DC)-Direct current
(DC) converter activates only when voltage value of the traction battery pack is in
between a predefined range and no alarm signal is received from the plurality of
10 slave battery packs of the traction battery pack.
[0025] In an aspect, the alarm signal comprises under voltage signal, over
voltage signal, under temperature signal, and over temperature signal.
[0026] In an aspect, the system further comprises a high power DC-DC
converter coupled with the high voltage (HV) generated by the master BMS from
15 the traction battery pack, the high power DC-DC converter configured to charge
an auxiliary battery, supply low voltage (LV) power to a plurality of auxiliary
loads, and supply low voltage (LV) power to the electronic control module.
[0027] In an aspect, the master BMS deactivates the isolated low power DCDC
converter when the electronic control module receives the low voltage (LV)
20 power from the high power DC-DC converter.
[0028] In another aspect of the present subject matter, a method is provided
for starting an electric vehicle using traction battery of the electric vehicle when
auxiliary battery is completely discharged. The method comprises generating low
voltage (LV) power from a traction battery pack by low power DC-DC converter
25 and supplying generated low voltage power to an electronic control module to
perform safety checks in the electric vehicle. The method further includes starting
the electric vehicle by transmitting high voltage (HV) power from the traction
7
battery pack upon receiving inputs from the electronic control module to activate
the master BMS by the master BMS.
[0029] In an aspect, the low voltage (LV) power is generated when auxiliary
battery is discharged below a threshold level (Thv) and a switch is pressed.
[0030] In an aspect, the low voltage (LV) power is generated when auxiliar5 y
battery is discharged below such a level, that electronic control module cannot be
powered up to perform safety checks, or power up the vehicle.
[0031] In an aspect, the method further includes supplying generated low
voltage (LV) power to the electronic control module only.
10 [0032] In an aspect, the method further comprises activating the isolated low
power DC-DC converter to generate the low voltage (LV) power when voltage
value of the traction battery pack is in between a predefined range and no alarm
signal is received from the plurality of slave BMS of the traction battery pack.
[0033] In an aspect, the method further comprises charging an auxiliary
15 battery from low voltage (LV) power generated by a high power DC-DC
converter from the high voltage (HV) power transmitted by the master BMS,
supplying the low voltage power to a plurality of auxiliary loads, and supplying
the low voltage power to the electronic control module.
[0034] In an aspect, the method further comprises deactivating the isolated
20 low power DC-DC converter when the electronic control module receives low
voltage (LV) power from the high power DC-DC converter.
[0035] Various objects, features, aspects, and advantages of the inventive
subject matter will become more apparent from the following detailed description
of preferred embodiments, along with the accompanying drawing figures in which
25 like numerals represent like components.
BRIEF DESCRIPTION OF THE DRAWINGS
8
[0036] The illustrated embodiments of the subject matter will be best
understood by reference to the drawings, wherein like parts are designated by like
numerals throughout. The following description is intended only by way of
example, and simply illustrates certain selected embodiments of devices, systems,
and methods that are consistent with the subject matter as claimed herein5 ,
wherein:
[0037] Fig. 1 illustrates architecture of electric vehicle with traction battery
pack and auxiliary battery, in accordance with an embodiment of the present
subject matter; and
10 [0038] Fig. 2 illustrates a method for starting an electric vehicle using system
of fig. 1, in accordance with an embodiment of the present subject matter.
[0039] The figures depict embodiments of the present subject matter for the
purposes of illustration only. A person skilled in the art will easily recognize from
the following description that alternative embodiments of the structures and
15 methods illustrated herein may be employed without departing from the principles
of the disclosure described herein
DETAILED DESCRIPTION
[0040] The detailed description of various exemplary embodiments of the
disclosure is described herein with reference to the accompanying drawings. It
20 should be noted that the embodiments are described herein in such details as to
clearly communicate the disclosure. However, the amount of details provided
herein is not intended to limit the anticipated variations of embodiments; on the
contrary, the intention is to cover all modifications, equivalents, and alternatives
falling within the scope of the present disclosure as defined by the appended
25 claims.
[0041] It is also to be understood that various arrangements may be devised
that, although not explicitly described or shown herein, embody the principles of
9
the present disclosure. Moreover, all statements herein reciting principles, aspects,
and embodiments of the present disclosure, as well as specific examples, are
intended to encompass equivalents thereof.
[0042] The terminology used herein is for the purpose of describing particular
embodiments only and is not intended to be limiting of example embodiments. 5 As
used herein, the singular forms “a",” “an” and “the” are intended to include the
plural forms as well, unless the context clearly indicates otherwise. It will be
further understood that the terms “comprises,” “comprising,” “includes” and/or
“including,” when used herein, specify the presence of stated features, integers,
10 steps, operations, elements and/or components, but do not preclude the presence
or addition of one or more other features, integers, steps, operations, elements,
components and/or groups thereof.
[0043] It should also be noted that in some alternative implementations, the
functions/acts noted may occur out of the order noted in the figures. For example,
15 two figures shown in succession may, in fact, be executed concurrently or may
sometimes be executed in the reverse order, depending upon the functionality/acts
involved.
[0044] In addition, the descriptions of "first", "second", “third”, and the like in
the present invention are used for the purpose of description only, and are not to
20 be construed as indicating or implying their relative importance or implicitly
indicating the number of technical features indicated. Thus, features defining
"first" and "second" may include at least one of the features, either explicitly or
implicitly.
[0045] Unless otherwise defined, all terms (including technical and scientific
25 terms) used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which example embodiments belong. It will be further
understood that terms, e.g., those defined in commonly used dictionaries, should
10
be interpreted as having a meaning that is consistent with their meaning in the
context of the relevant art and will not be interpreted in an idealized or overly
formal sense unless expressly so defined herein.
[0046] Non-limiting Definitions
[0047] In the disclosure hereinafter, one or more terms are used to describ5 e
various aspects of the present disclosure. For a better understanding of the present
disclosure, a few definitions are provided herein for better understating of the
present disclosure.
[0048] Battery Management System (BMS): A battery management system
10 (BMS) is any electronic system that manages a rechargeable battery (cell or
battery pack), such as by protecting the battery from operating outside its safe
operating area, monitoring its state, calculating secondary data, reporting that
data, controlling its environment, authenticating it and / or balancing it.
[0049] High Voltage (HV): High voltage is defined as voltage in range 30 to
15 1000 VAC or 60 to 1500 VDC.
[0050] Low Voltage (LV): Low voltage is defined as voltage in range 0 to 30
VAC or 0 to 60 VDC.
[0051] Power Electronic Module (PEM): Power electronic module provides
the physical containment for several power components, usually includes inverter
20 and motors.
[0052] State of Charge (SoC): The SoC of a battery is defined as the ratio of
its current capacity to the nominal capacity. The nominal capacity is given by the
manufacturer and represents the maximum amount of charge that can be stored in
the battery.
11
[0053] Depth of Discharge (DoD): A battery’s depth of discharge (DoD)
indicates the percentage of the battery that has been discharged relative to the
overall capacity of the battery.
[0054] State of Health (SoH): State of health (SoH) is a figure of merit of the
condition of a battery (or a cell, or a battery pack), compared to its idea5 l
conditions.
[0055] DC-DC converter: A DC-to-DC converter is an electronic circuit or
electromechanical device that converts a source of direct current (DC) from one
voltage level to another.
10 [0056] These and other advantages of the present subject matter would be
described in greater detail with reference to the following figures. It should be
noted that the description merely illustrates the principles of the present subject
matter. It will thus be appreciated that those skilled in the art will be able to devise
various arrangements that, although not explicitly described herein, embody the
15 principles of the present subject matter and are included within its scope.
[0057] Main objective of the present invention is to provide a system to start
an electric vehicle using traction battery when auxiliary battery is complete
discharged and unable to start the electric vehicle. Further, the present system
charges the discharged auxiliary battery only in key on condition or vehicle start
20 condition.
[0058] The present invention can be implemented in any electric vehicle
having traction battery and auxiliary battery. Further, the present invention
overcomes all the technical problems as mentioned in the background section by
restricting charging of the auxiliary battery in key off condition and solving
25 technical problem of starting the vehicle when the auxiliary battery is completely
discharged by starting the vehicle through the traction battery using present
system as explained below.
12
[0059] Exemplary Implementations
[0060] To this, as shown in fig. 1, a system 100 for starting an electric vehicle
using traction battery when auxiliary battery is fully or partially discharged is
explained. The system 100 comprises a traction battery pack 115 having a
plurality of battery modules, a master battery management system (BMS) 101, 5 a
plurality of slave BMS 102, an electronic control module 104, auxiliary loads 110,
auxiliary battery 111, a switch block 109, high power DC-DC converter 108 and
power electronic module (PEM) 107.
[0061] In the electric vehicle, traction battery pack 115 has a plurality of
10 battery modules to provide power to an electric drive train of the electric vehicle.
The traction battery pack 115 comprises a plurality of slave battery management
system (BMS) 102 and a master battery management system (BMS) 101. Each of
slave BMS 102 from the plurality of slave BMS 102 coupled with an individual
battery module of the traction battery pack 115 to manage the battery module. For
15 example, the traction battery pack 115 has 64 battery modules, there will be 64
slave BMS 102 coupled with the 64 battery modules. The master BMS 101 is
coupled with the plurality of slave BMS 102 to manage each of the battery
module by receiving information about the battery modules. The traction battery
pack 115 provides high voltage in range 60 to 1500 VDC power which is further
20 converted into low voltage in range 0 to 60 VDC for charging an auxiliary battery
111, running auxiliary loads 110 of the electric vehicle, and electronic control
module 104 of the electric vehicle.
[0062] The master BMS 101 includes an isolated low power direct current
(DC)-direct current (DC) converter 103 that has wired connection with a key 116
25 and a switch 105 (explained in detail in subsequent explanation of the figure). The
operable range of low power DC-DC converter is 0 to 60 VDC. Further, the
isolated low power DC-DC converter 103 is coupled with the plurality of slave
BMS 102 to receive a plurality of alarm signals from the battery modules of the
13
traction battery pack 115. The plurality of alarm signals defines safe operational
condition of the traction battery pack 115. The plurality of alarm signals
comprises under voltage (UV) signal, over voltage (OV) signal, under temperature
(UT) signal, and over temperature (OT) signal. The cell voltage and temperature
range depends on the type of cell chemistry. For example, for LFP chemistry 5 UV
is 2.5V and OV is 3.9V, UT is -10˚C and OT is 65 ˚C. The alarm signals received
from the battery modules of the traction battery pack 115 are hardwired, and low
power DC-DC converter 103 does not require any power to read them.
[0063] The isolated low power DC-DC converter 103 is coupled with high
10 voltage power of the traction battery pack 110 and the high voltage power line of
the plurality of slave BMS 102. When the auxiliary battery 111 is fully discharged
or is below a threshold level ‘Thv’, the auxiliary battery 111 is not able to power
up an electronic control module of the electric vehicle. To start the electric
vehicle, the key 116 is put at key on position and the switch 105 is pressed, the
15 isolated low power DC-DC converter 103 determines whether traction battery
voltage value of the traction battery pack 115 is in between a predefined range or
not. The DC-DC converter itself senses the HV from the pack HV+ and HV- lines
through hardwired signals. The isolated low power DC-DC converter 103 also
checks whether alarm signals from the plurality of slave BMS 102 are present or
20 not. If the traction battery voltage value is in between the predefined range and
there is no alarm signals from the plurality of slave BMS 102, the isolated low
power DC-DC converter 103 activates to convert the high voltage (HV) power
line of the traction battery pack 115 to low voltage (LV) power line.
[0064] As shown in the fig. 1, the isolated low power DC-DC converter 103 is
25 wired with the electronic control module 104 through wires. The isolated low
power DC-DC converter 103 activates the electronic control module 104 by
supplying generated low voltage line. The electronic control module 104 or
electronic control boards 104 comprises an electronic control unit (ECU), Body
14
Control Module (BCM), Telematics Control Unit (TCU), Battery Management
System (BMS), etc., to perform a plurality of safety checks to start the electric
vehicle safely. Further, the electronic control module 104 is isolated from the
auxiliary loads 110 and the auxiliary battery 111 by a circuit breaker or by a
switch block 109 having a diode and a parallel relay to restrict flow of 5 f power in
one side only, i.e., from the isolated low power DC-DC converter 103 to the
electronic control module 104. The switch block 109 is positioned in between
auxiliary battery 111 and the isolated low power DC-DC converter output in such
a way that it only powers up the electronic control module 104 and doesn’t charge
10 the auxiliary battery 111 or power up the auxiliary loads 110.
[0065] The electronic control module 104 provides information regarding the
plurality of safety checks to the master BMS 101. When the plurality of safety
checks indicate that it is safe to start the vehicle, the master BMS turn on P relay
106a provided on positive side of the high voltage line and N relay 106b provided
15 on negative side of the high voltage line to supply the high voltage line to the
power electronic module 107 from the traction battery pack 115.
[0066] As shown in fig. 1, the high power DC-DC converter 108 that is
connected with high voltage line of the traction battery pack 115 receives the high
voltage power and converts the same into low voltage power line. The generated
20 low voltage power line charges the auxiliary battery 111 and supplies low voltage
power to the auxiliary loads 110, such as headlamp, fan, tuner, wiper and other
equipment which are operated by the electric power of the auxiliary battery 111.
The generated low power passes through the switch block 109 and supplies power
to the electronic control module 104. The electronic control module 104 sends a
25 signal to the master BMS 101 regarding low voltage power from the high power
DC-DC converter 108. The master BMS 101 stops the isolated low power DC-DC
converter 103 from working and converting the high voltage into low voltage.
15
[0067] As explained above, if the switch 105 is not pressed and there is alarm
signals from the plurality of slave BMS 102, the isolated low power DC-DC
converter 103 will not start and vehicle will not start.
[0068] Fig. 2 illustrates a method 200 for starting an electric vehicle using
system 100, in accordance with an embodiment of the present disclosure. 5 The
order in which the method 200 is described is not intended to be construed as a
limitation, and any number of the described method blocks may be combined in
any order to implement the method 200, or an alternative method.
[0069] At block 201, the method includes determining condition of an
10 auxiliary battery 111. If the auxiliary battery is fully discharged, it is not able to
power up the electronic control module 104. Also, if auxiliary battery is partially
discharged, such that it is not able to power up the electronic control module 104.
If yes, the method 200 proceed to block 202.
[0070] At block 202, the method includes determining whether key is in ON
15 condition or not. If not, the method checks key condition again. If yes, the method
proceeds to block 203.
[0071] At block 203, the method includes determining whether switch 105 is
pressed. If not pressed, the method again determines status of the switch 105. If
pressed, the method proceeds to block 204.
20 [0072] At block 204, the method includes activating the isolated low power
DC-DC converter 103 to generate the low voltage (LV) power when voltage value
of the traction battery pack is in between a predefined range and no alarm signal is
received from the plurality of slave BMS 102 of the traction battery pack 115.
[0073] At block 205, the method includes generating low voltage power from
25 the high voltage power of the traction battery pack by the isolated low power DCDC
converter 103.
16
[0074] At block 206, the method includes supplying generated low voltage
power to the connected electronic control module 104 to perform a plurality of
safety checks.
[0075] At block 207, the method includes starting the electric vehicle upon
receiving inputs of the plurality of safety checks from the electronic contro5 l
module by the master BMS 101. The master BMS 101 turn on the P relay and the
N relay to supply high voltage power from the traction battery pack 115 to the
power electronic module 107.
[0076] At block 208, the method includes charging the auxiliary battery 111
10 by the high power DC-DC converter 108. The high power DC-DC converter 108
receives high voltage power from the traction battery pack 115 allowed by the
master BMS 101 and convert the same to low voltage power to charge the
auxiliary battery 111 and to supply the low voltage power to the auxiliary loads
110. The high power DC-DC converter 108 supplies power to the electronic
15 control module 104 through the switch block 109.
[0077] At block 209, the method includes stopping the isolated low power
DC-DC converter 103 by the master BMS 101 upon receiving inputs from the
electronic control module 104 regarding low voltage power supply by the high
power DC-DC controller 108.
20 [0078] It will be understood by those within the art that, in general, terms used
herein, and especially in the appended claims (e.g., bodies of the appended
claims) are generally intended as “open” terms (e.g., the term “including” should
be interpreted as “including but not limited to,” the term “having” should be
interpreted as “having at least,” the term “includes” should be interpreted as
25 “includes but is not limited to,” etc.). It will be further understood by those within
the art that if a specific number of an introduced claim recitation is intended, such
an intent will be explicitly recited in the claim, and in the absence of such
17
recitation no such intent is present. For example, as an aid to understanding, the
following appended claims may contain usage of the introductory phrases “at least
one” and “one or more” to introduce claim recitations. However, the use of such
phrases should not be construed to imply that the introduction of a claim recitation
by the indefinite articles “a” or “an” limits any particular claim containing suc5 h
introduced claim recitation to inventions containing only one such recitation, even
when the same claim includes the introductory phrases “one or more” or “at least
one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should
typically be interpreted to mean “at least one” or “one or more”); the same holds
10 true for the use of definite articles used to introduce claim recitations. In addition,
even if a specific number of an introduced claim recitation is explicitly recited,
those skilled in the art will recognize that such recitation should typically be
interpreted to mean at least the recited number (e.g., the bare recitation of “two
recitations,” without other modifiers, typically means at least two recitations, or
15 two or more recitations). Furthermore, in those instances where a convention
analogous to “at least one of A, B, and C, etc.” is used, in general such a
construction is intended in the sense one having skill in the art would understand
the convention (e.g., “a system having at least one of A, B, and C” would include
but not be limited to systems that have A alone, B alone, C alone, A and B
20 together, A and C together, B and C together, and/or A, B, and C together, etc.).
In those instances where a convention analogous to “at least one of A, B, or C,
etc.” is used, in general such a construction is intended in the sense one having
skill in the art would understand the convention (e.g., “a system having at least
one of A, B, or C” would include but not be limited to systems that have A alone,
25 B alone, C alone, A and B together, A and C together, B and C together, and/or A,
B, and C together, etc.). It will be further understood by those within the art that
virtually any disjunctive word and/or phrase presenting two or more alternative
terms, whether in the description, claims, or drawings, should be understood to
contemplate the possibilities of including one of the terms, either of the terms, or
18
both terms. For example, the phrase “A or B” will be understood to include the
possibilities of “A” or “B” or “A and B.”
[0079] While the foregoing describes various embodiments of the invention,
other and further embodiments of the invention may be devised without departing
from the basic scope thereof. The scope of the invention is determined by 5 the
claims that follow. The invention is not limited to the described embodiments,
versions or examples, which are included to enable a person having ordinary skill
in the art to make and use the invention when combined with information and
knowledge available to the person having ordinary skill in the art.

We claim:
1. A system (100) for starting an electric vehicle having a traction battery pack
(115), the system (100) comprising:
a master battery management system (BMS) (101) coupled with a
plurality of slave battery management system (BMS) (102), each of sla5 ve
BMS (102) from the plurality of slave BMS (102) manages a battery
module of the traction battery pack of the electric vehicle, the master BMS
(101) comprising:
an isolated low power Direct current (DC)-Direct current (DC)
10 converter (103) coupled with high voltage (HV) line and low voltage
(LV) line of the plurality of slave BMS (102), the isolated low power
Direct current (DC)-Direct current (DC) converter is configured to:
convert the high voltage (HV) line to low voltage (LV) line; and
activate an electronic control module (104) by supplying the low
15 voltage (LV) line to perform a plurality of safety checks on the
electric vehicle;
the master BMS (101) starts the electric vehicle based on inputs received
from the electronic control module (104) by transmitting High Voltage (HV)
power from the traction battery pack to power electronic module (PEM) (107).
20 2. The system (100) as claimed in claim 1, wherein the electronic control
module (104), based on inputs from the plurality of safety checks, activates
the master BMS (101).
3. The system (100) as claimed in claim 1, wherein the electronic control
module (104) comprises an electronic control unit (ECU), Body Control
25 Module (BCM), Telematics Control Unit (TCU), Battery Management
System (BMS).
20
4. The system (100) as claimed in claim 1, wherein the low power DC-DC
converter (103) is activated when auxiliary battery (111) is discharged
below a threshold level (Thv) and a switch (105) is pressed.
5. The system (100) as claimed in claim 2, wherein the auxiliary battery (111)
is completely discharged or is below a threshold level (Thv) or th5 e
electronic control module (104) is not able to power up by the auxiliary
battery (111).
6. The system (100) as claimed in claim 1, wherein a switch block (109)
having diode and parallel relay provided to supply the low voltage (LV)
10 power from the low power DC-DC converter (103) to the electronic control
module (104) only.
7. The system (100) as claimed in claim 1, wherein the isolated low power
Direct current (DC)-Direct current (DC) converter (103) activates when:
voltage value of the traction battery pack is in between a
15 predefined range; and
no alarm signal is received from the plurality of slave BMS
(102) of the traction battery pack.
8. The system (100) as claimed in claim 7, wherein the alarm signal comprises
under voltage signal, over voltage signal, under temperature signal, and over
20 temperature signal.
9. The system (100) as claimed in claim 1, wherein the system (100) further
comprises:
a high power DC-DC converter (108) coupled with the high voltage
(HV) generated by the master BMS (101) from the traction battery pack, the
25 high power DC-DC converter (108) configured to:
charge an auxiliary battery (111);
supply low voltage (LV) power to a plurality of auxiliary loads
(110); and
21
supply low voltage (LV) power to the electronic control module
(104).
10. The system (100) as claimed in claim 5, wherein the master BMS (101)
stops the isolated low power DC-DC converter (103) when the electronic
control module (104) receives the low voltage (LV) power from the 5 high
power DC-DC converter (108).
11. A method (200) for starting an electric vehicle using traction battery pack
(115), the method (200) comprising:
generating (205), by low power DC-DC converter (103), low voltage
10 (LV) power from a traction battery pack;
supplying (206) generated low voltage power to an electronic control
module (104) to perform safety checks in the electric vehicle;
starting (207), by master BMS (101), the electric vehicle by
transmitting high voltage (HV) power from the traction battery pack to
15 power electronic module (PEM) (107).
12. The method (200) as claimed in claim 11, wherein the low voltage (LV)
power is generated when auxiliary battery (111) is discharged below a
threshold level (Thv) and a switch (105) is pressed.
13. The method (200) as claimed in claim 11, wherein the method (200) further
20 comprises supplying (206) generated low voltage (LV) power to the
electronic control module (104) only.
14. The method (200) as claimed in claim 11, wherein the method further
comprises:
activating (204) the isolated low power DC-DC converter (103) to
25 generate the low voltage (LV) power when:
voltage value of the traction battery pack is in between a
predefined range; and
no alarm signal is received from the plurality of slave BMS
(102) of the traction battery pack.
22
15. The method (200) as claimed in claim 11, wherein the method further
comprises:
charging (208) an auxiliary battery (111) from low voltage (LV)
power generated by a high power DC-DC converter (108) from the
high voltage (HV) power transmitted by the master BMS (5 101);
supplying the low voltage power to a plurality of auxiliary loads
(110); and
supplying the low voltage power to the electronic control
module (104).
10 16. The method (200) as claimed in claim 15, wherein the method (200) further
comprises:
stopping (209) the isolated low power DC-DC converter (103) when
the electronic control module (104) receives low voltage (LV) power from
the high power DC-DC converter (108).