TECHNICAL FIELD
[0001] The present subject matter described herein, relates to starting of an
electric vehicle. More particularly, the present subject matter provides a traction
battery pack to by-pass faulty battery modules and generates traction voltage
using remaining battery modules.
BACKGROUND
[0002] Background description includes information that may be useful in
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 electric vehicles, a traction battery pack is provided which is
primary energy source for providing energy for traction of vehicle. The traction
battery pack has a battery string having a plurality of battery modules connected
in series with each other. When any of the battery module is faulty or doesn’t
provide required voltage, the faulty battery module is by-passed instead of
stopping the output of the traction battery pack by a master controller. Further, a
boost converter is connected in parallel with output of the battery string to boost
the reduced voltage to meet the requirement of the electric vehicle. The boost
converter connected in parallel with output of the battery string provide necessary
traction voltage in limp home safe mode to the vehicle.
[0004] The existing solution where the boost converter is connected in parallel
with the battery string has several disadvantages as the boost converter is to be of
higher power transfer capability to provide proper traction. With higher power
transfer capabilities, the boost converter is bigger in size, heavier in weight and
increases cost of the traction battery pack. Further, high power capability boost
converter has higher efficiency loses.
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[0005] Therefore, there is a need of a system for a traction battery pack that
can by-pass the faulty battery module and generate required traction voltage with
less cost and less efficiency losses using the isolated DCDC converter.
OBJECTS OF THE DISCLOSURE
[0006] Some of the objects of the present disclosure, which at least one
embodiment herein satisfy, are listed herein below.
[0007] The principal object of the present invention is to provide a system for
a traction battery pack to by-pass the faulty battery modules and generate required
traction voltage with less efficiency losses.
[0008] Another object of the present invention is to provide a system where
output of isolated DCDC step down converter is provided in series with battery
string to generate required traction voltage.
[0009] Another object of the present invention is to provide a system where
the isolated DCDC step down converter has small size and corresponding less
efficiency losses.
[0010] These and other objects and advantages will become more apparent
when reference is made to the following description and accompanying drawings.
SUMMARY
[0011] This summary is provided to introduce concepts related to a system for
a traction battery back of an electric vehicle for traction in limp home mode. The
concepts are further described below in the detailed description. This summary is
not intended to 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.
[0012] In an embodiment, the present subject matter relates to a traction
battery pack of an electric vehicle for safe traction capability in limp home mode
or when one of a battery module is faulty or not working. The traction battery
pack comprises a battery string including a plurality of battery modules connected
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in series by a plurality of relays. Further each of the plurality of battery modules
has by-pass relay connected in parallel with each of the plurality of battery
modules. The traction battery pack includes a master controller which is coupled
with each of the plurality of battery modules, each of the plurality of relays, and
the by-pass relays of each of the plurality of battery module. The master controller
is configured to receive fault information from any of the plurality of battery
modules and opening the relay and closing by-pass relay of respective faulty
battery module to by-pass the faulty battery module. The traction battery pack
further includes a DCDC converter having output connection in series with the
battery string to generate traction voltage as required by vehicle control unit.
[0013] In an aspect, the DCDC converter coupled with the master controller
where the master controller is configured to receive traction voltage requirement
from vehicle control unit and compare the traction voltage requirement with
output voltage from the battery string. Upon affirmation that output voltage from
the battery string is less than the traction voltage requirement, the master
controller activates the DCDC converter.
[0014] In an aspect, the DCDC converter is activated by opening SC relay.
The master controller opens the SC relay.
[0015] In an aspect, an input of the DCDC converter is in parallel with output
of the battery string and output of the DCDC converter (104) is in series with
output of the battery string.
[0016] In an aspect, the DCDC converter is an isolated step down converter.
[0017] In an embodiment, the present subject matter relates to a method for
traction of an electric vehicle using traction battery pack having at least one faulty
battery module. The method includes opening a relay (R1-Rn) of the at least one
faulty battery module by master controller and closing by-pass relay (S1-Sn) of
the at least one faulty battery module to by-pass the at least one faulty battery
module. The method further includes activating a DCDC converter to generate
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traction voltage when traction voltage requirement is more than remaining output
voltage from the battery string.
[0018] 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
like numerals represent like components.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] 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 herein,
wherein:
[0020] Fig. 1 illustrates architecture of traction battery pack with DCDC
converter, in accordance with an embodiment of the present subject matter; and
[0021] Fig. 2 illustrates a method for generating traction voltage from the
traction battery pack of Fig. 1, in accordance with an embodiment of the present
subject matter.
[0022] 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
methods illustrated herein may be employed without departing from the principles
of the disclosure described herein.
DETAILED DESCRIPTION
[0023] The detailed description of various exemplary embodiments of the
disclosure is described herein with reference to the accompanying drawings. It
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
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contrary, the intention is to cover all modifications, equivalents, and alternatives
falling within the scope of the present disclosure as defined by the appended
claims.
[0024] It is also to be understood that various arrangements may be devised
that, although not explicitly described or shown herein, embody the principles of
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.
[0025] The terminology used herein is for the purpose of describing particular
embodiments only and is not intended to be limiting of example embodiments. 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,
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.
[0026] 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,
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.
[0027] 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
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.
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[0028] Unless otherwise defined, all terms (including technical and scientific
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
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.
Non-limiting Definitions
[0029] In the disclosure hereinafter, one or more terms are used to describe
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.
[0030] Master controller: A controller which 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.
[0031] DCDC converter: A DCDC converter is an electronic circuit or
electromechanical device that converts a source of direct current (DC) from one
voltage level to another. There are two type of DCDC converter: one is buck type
(step down) and another is boost type (step up).
[0032] Isolated step down DCDC Converter: It is an electronic circuit or
electro-mechanical device that converts a source of direct current (DC) from one
voltage level to another. The output voltage level of step down converter is always
less than input voltage and output is also isolated from input.
[0033] 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
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various arrangements that, although not explicitly described herein, embody the
principles of the present subject matter and are included within its scope.
[0034] Main objective of the present invention is to provide a traction battery
pack for an electric vehicle that can generate traction voltage when there is at least
one battery module which is not working or not generating enough power.
[0035] The present invention can be implemented in any electric vehicle
having traction battery pack. Further, the present invention overcomes all the
technical problems as mentioned in the background section by providing low
power DCDC converter for generation of required traction voltage when at least
one battery module is not working or not generating enough power.
Exemplary Implementations
[0036] To this, as shown in fig. 1, a traction battery pack 100 for an electric
vehicle is explained. The traction battery pack 100 comprises a battery string 101,
a master controller 103, and a DC-DC converter. The battery string 101 includes a
plurality of battery modules 102a-102n that are connected in series with each
other by a plurality of relays R1-Rn. For implementation, a relay is provided in
between two battery modules connected in series. Further, each of the battery
module from the plurality of battery modules 102a-102n has a by-pass relay S1-
Sn connected in parallel to by-pass each of the battery modules.
[0037] The master controller 103 is communicatively coupled with each of the
plurality of battery modules 102a-102n. Further, each of the battery modules
102a-102n may have a controller which is in communication with the master
controller 103. The master controller 103 is communicatively coupled with each
of the plurality of relays R1-Rn by means of connections 107. The master
controller 103 is communicatively coupled with each of the by-pass relay S1-Sn
by means of connection 108. The connections 107 and 108 may be hard wire
connections. Upon receiving fault information from any of the battery module
from the plurality of battery modules 102a-102n over the connections, the master
controller 103 opens corresponding relay from the plurality of relays R1-Rn and
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closes corresponding by-pass relay from the plurality of by-pass relays S1-Sn of
respective faulty battery module to by-pass the faulty battery module. The fault
information is alarm signal generated by the battery module. The battery module
can be faulty because of under voltage (UV), over voltage (OV), under
temperature (UT), and over temperature (OT), etc. For example, if battery module
102b is faulty battery module and is to be by-passed, the master controller 103
opens the relay R2 and closes the by-pass relay S2 to by-pass the faulty battery
module 102b.
[0038] As shown in the fig. 1, the DCDC converter 104 is coupled with the
master controller 103 and activates based on the inputs from the master controller.
Where input of the DCDC converter 104 is in parallel with the battery string 101
and output of the DCDC converter 104 is in series with the battery string 101. The
master controller 103 is communicatively coupled with a vehicle control unit 106
to receive information required traction voltage ‘Vr’. The master controller 103
compares the required traction voltage ‘Vr’ with the output voltage ‘Vo’ by the
battery string 101. Upon comparing, the master controller 103 opens SC relay 105
to activate the DCDC converter when the output voltage ‘Vo’ from the battery
string 101 is less than the traction voltage requirement ‘Vr’.
[0039] The DCDC converter 104 is an isolated step down converter that has
input connected parallel with the output voltage ‘Vo’ to reduce the voltage and
output is in series connection with the battery string 101. The DCDC converter
104 generates reduce voltage by processing the parallel received output voltage
‘Vo’ of the battery string ‘Vs’ and combines the reduced voltage ‘Vs’ with the
output voltage ‘Vo’ coming from the battery string 101 connected in series to
generate the required traction voltage ‘Vr’.
[0040] For example, the battery string 101 has three battery modules to
generate total voltage of 300V. When one battery module is faulty, the battery
string output voltage reduces to 200V. The master controller 103 receives
requirement traction voltage of 300V. The master controller 103 activates the
DCDC converter 104 to generate the required traction voltage 300V. The DCDC
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converter 104 receives input voltage of 200V as input is in parallel tothe battery
string 101 and generates the reduced output voltages of 100V. Further, output of
the DCDC converter 101 is in series connection with the battery string 101, the
output voltage of 200V is combined with output voltage of 100V from the DCDC
converter to generate required traction voltage of 300V.
[0041] Fig. 2 illustrates a method 200 for starting an electric vehicle using
traction battery pack 100, in accordance with an embodiment of the present
disclosure. 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.
[0042] At block 201, the method includes determining condition of a plurality
of battery modules 102a-102n. The master controller 103 receives fault
information from faulty battery module from the plurality of battery modules
102a-102n and proceed to next step at block 202.
[0043] At block 202, the method includes opening relay of the faulty module
to cut the faulty battery module from the series connection of the plurality of
battery modules102a-102n.
[0044] At block 203, the method includes closing by-pass relay of the faulty
battery module to by-pass the faulty battery module from the plurality of battery
modules 102a-102n.
[0045] At block 204, the method includes receiving required traction voltage
‘Vr’ from the vehicle control unit 106 and comparing the same with the output
voltage ‘Vo’ of the battery string 101 with by-passed faulty module. At block 206,
the master controller 103 activates the DCDC converter when the required traction
voltage ‘Vr’ is more than the output voltage ‘Vo’ of the battery string.
[0046] At block 207, the master controller 103 generates the required traction
voltage ‘Vr’.
[0047] At block 205 the master controller 103 keeps the SC relay closed and
DCDC converter de-activated.
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[0048] The present traction battery pack 100 uses an isolated DCDC step
down converter to generate required traction voltage as compared to existing
DCDC step up converters. Further, the present isolated DCDC step down
converter is connected in series with the battery string to generate the required
traction voltage. Therefore, the present traction battery pack requires low power
and small size isolated DCDC step down converter in place of high power and big
size DCDC step up converter. Further, the present DCDC step down converter has
less losses due to efficiency loss.
[0049] For example, a step up and step down DCDC converter provides 90%
efficiency and there is requirement of 300V traction voltage and 9kW traction
power. To generate this much power, the traction battery pack would require 9kW
DCDC step up converter as per conventional method or 3kW step down DCDC
converter, in case of one module failure, as per the present invention. With the
DCDC step down converter with the present invention, there would be loss of
300W whereas in 9kW DCDC step up converter with conventional method would
suffer a loss of 900W.
[0050] The present subject matter provides technically advance, small in size,
less in cost and light in weight solution for the technical problems of the traction
battery as explained.
[0051] 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
“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
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
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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 such
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
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
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
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,
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
both terms. For example, the phrase “A or B” will be understood to include the
possibilities of “A” or “B” or “A and B.”
[0052] 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 the
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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 traction battery pack (100) of an electric vehicle comprising:
a battery string (101) including a plurality of battery modules (102a-
102n) connected in series by a plurality of relays (R1-Rn), where a by-pass
relay (S1, S2-Sn) connected in parallel with each of the plurality of battery
modules (102a-102n);
a master controller (103) coupled with each of the plurality of battery
modules (102a-102n), each of the plurality of relays (R1-Rn), and the bypass
relay (S1, S2-Sn) of each of the plurality of battery modules (102a-
102n), the master controller (103) configured to:
receive fault information from a faulty battery module from the
plurality of battery modules (102a-102n),
open the relay and closing by-pass relay of respective faulty
battery module to by-pass the faulty battery module;
characterized in that
a DCDC converter (104) having output connection in series with the
battery string (101) to generate traction voltage.
2. The traction battery pack (100) as claimed in claim 1, wherein the DCDC
converter (104) coupled with the master controller (103), the master
controller (103) configured to:
receive traction voltage (Vr) requirement from a vehicle control unit
(106);
compare the traction voltage requirement (Vr) with output voltage
(Vo) from the battery string (101); and
activate the DCDC converter (104) when the output voltage (Vo) from
the battery string (101) is less than the traction voltage requirement (Vr).
3. The traction battery pack (100) as claimed in claim 2, wherein the DCDC
converter (104) is activated by opening SC relay (105).
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4. The traction battery pack (100) as claimed in claim 1, wherein input of the
DCDC converter (104) is in parallel with the battery string (101) and output
of the DCDC converter (104) is in series with the battery string (101).
5. The traction battery pack (100) as claimed in claim 1, wherein the DCDC
converter (104) is an isolated step down converter.
6. A method (200) for traction an electric vehicle using traction battery pack
(100) having at least one faulty battery module from a plurality of battery
modules (102a-102n), the method (200) comprising:
opening (202), by master controller (103), relay (R1-Rn) of the faulty
battery module from the plurality of battery modules (102a-102n);
closing (203), by the master controller (103), by-pass relay (S1-Sn) of
the faulty battery module to by-pass the faulty battery module from the
plurality of battery modules (102a-102n);
activating (206), by the master controller (103), a DCDC converter
(104) to generate traction voltage (Vr).
7. The method (200) as claimed in claim 6, wherein the DCDC converter (104)
is activated when:
traction voltage requirement (Vr) is more than output voltage (Vo)
from the battery string (101).
8. The method (200) as claimed in claim 6, wherein the method (200) further
comprises opening (206), by the master controller (103), relay (SC) to
activate the DCDC converter (104).
9. The method (200) as claimed in claim 6, wherein the DCDC converter (104)
having output connection in series with the battery string (101) to generate
traction voltage (Vr).
10. The method (200) as claimed in claim 6, wherein input of the DCDC
converter (104) is in parallel with the battery string (101) and output of the
DCDC converter (104) is in series with the battery string (101).
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11. The traction battery pack (100) as claimed in claim 1, wherein the DCDC
converter (104) is an isolated step down converter.