FIELD OF INVENTION
[001] The present invention relates generally to Electric Vehicles (EVs) and, more
specifically, to a system and method for maintaining optimal temperature of the battery,
motor, control unit and onboard charging unit.
BACKGROUND
[002] Over the rising concerns of oil costs, climate change, and energy security, efforts to
promote energy efficient EVs have grown. EVs provide overall reduced air emissions
compared to conventional combustion vehicles.
[003] The performance of EVs depends on energy storage systems like a battery. It is known that temperature has an influence over battery life and performance. The battery is preferred to operate within an optimum temperature range. Thus, a thermal management system is required to achieve desired performance in varied climate conditions while maintaining high efficiency.
[004] Existing electric vehicles often use multiple independent heat management systems. Such an approach is inherently less efficient as each heat management subsystem requires its own components (e.g., heat exchangers, pumps, coolant valves, compressors, expansions coolant valves, reservoirs etc.). Though such systems are capable of handling thermal loads from the powertrain, a simplified system is required for minimizing the number of parts and cost of the vehicle.
[005] Therefore, there is a need for an improved system and method for maintaining optimal temperature of vehicle powertrain components while reducing the part count, as well as eliminating the requirement of a heater unit.

BRIEF DESCRIPTION
[006] This summary is provided to introduce a selection of concepts in a simple manner that
are further described in the detailed description of the disclosure. This summary is not
intended to identify key or essential inventive concepts of the subject matter nor is it
intended for determining the scope of the disclosure.
[007] The heat producing units in a vehicle powertrain are the battery, motor, control unit and onboard charger. Two working fluids are used, one being a coolant and the other being a refrigerant. In accordance with a first embodiment of the present invention, a powertrain thermal management system is provided for operating the vehicle (i.e. discharging) in hot climate and cold climate conditions and charging the vehicle in hot climate and cold climate.
[008] In accordance with a second embodiment of the present invention, an electric vehicle powertrain thermal management system is provided to precondition the battery to a safe operating range in hot and cold climate conditions before charging and discharging the battery.
BRIEF DESCRIPTION OF DRAWINGS
[009] Embodiments of the invention are described below with reference to the accompanying
drawings. [0010] Fig. 1 is a schematic diagram of a powertrain thermal management system, in
accordance with both embodiments of the invention. [0011] Fig. 2 is a schematic of powertrain thermal management system with refrigeration in
hot climate in accordance with both embodiments of the invention. [0012] Fig. 3 is a schematic of powertrain thermal management system with refrigeration loop
bypassed in cold climate in accordance with both embodiments of the invention.

[0013] Fig. 4 is a schematic of powertrain thermal management system for heating the battery in cold climate in accordance with embodiments of the invention.
[0014] Fig. 5 illustrates a thermal management method for battery preconditioning before running the vehicle as well as a method for powertrain thermal management during battery discharging i.e. when the vehicle is running, in accordance with both embodiments of the invention.
[0015] Fig. 6 illustrates a thermal management method for battery preconditioning before charging as well as a method for battery thermal management during charging in accordance with both embodiments of the invention.
[0016] Further, persons skilled in the art to which this disclosure belongs will appreciate that elements in the figures are illustrated for simplicity and may not have necessarily been drawn to scale. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the figures by conventional symbols, and the figures may show only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the figures with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.
DETAILED DESCRIPTION
[0017] For the purpose of promoting an understanding of the principles of the disclosure,
reference will now be made to the embodiment illustrated in the figures and specific
language will be used to describe them. It will nevertheless be understood that no limitation
of the scope of the disclosure is thereby intended. Such alterations and further modifications
to the disclosure, and such further applications of the principles of the disclosure as

described herein being contemplated as would normally occur to one skilled in the art to which the disclosure relates are deemed to be a part of this disclosure.
[0018] It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the disclosure and are not intended to be restrictive thereof.
[0019] The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such a process or a method. Similarly, one or more devices or sub-systems or elements or structures or components preceded by "comprises... a" does not, without more constraints, preclude the existence of other devices, other sub-systems, other elements, other structures, other components, additional devices, additional sub-systems, additional elements, additional structures, or additional components. Appearances of the phrase “in an embodiment”, “in another embodiment” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.
[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.
[0021] Embodiments of the present disclosure will be described below in detail with reference to the accompanying figures.
[0022] Referring to FIG. 1, the powertrain thermal management system 100 in an electric vehicle, in accordance with embodiments of the present disclosure comprises of at least one battery 201, an onboard charger 202, at least one motor 203, a control unit 204 having sensor, first type heat exchangers H1 and H2, a second type heat exchanger H3, a fan 303,

coolant valves V1 and V2, pumps P1 and P2, a compressor 302, an expansion valve 301, a receiver-drier 402, and a coolant reservoir 401.
[0023] The present disclosure does not intend to limit the type of above-mentioned components. For example, the compressor 302 can be either of scroll compressor, reciprocating compressor, etc. Similarly, the battery 201, the onboard charger 202, the motor 203, the control unit 204, the heat exchangers H1, H2 and H3, the circulating pumps P1 and P2, the expansion valve 301, the coolant valves V1 and V2, the fan 303, receiver drier 402 and the coolant reservoir 401 can be of different types known in the art. The coolant used can be of any type and either in liquid or gaseous state. The refrigerant is also not limited to any particular type.
[0024] The number or arrangement of batteries 201 is not limited. The batteries 201 may be thermally connected in series or parallel or a combination of both.
[0025] The number or arrangement of motors 203 is not limited. The motors 203 may be thermally connected in series or parallel or a combination of both.
[0026] The thermal management system 100 consists of various paths where the fluids can flow in a cyclic manner. One or more such cyclic paths are hereinafter referred to as a “thermal loop”. Various thermal loops involved in the thermal management system are four coolant loops i.e., a first coolant loop L1, a second coolant loop L2, a third coolant loop L3, a fourth coolant loop L4 and a refrigerant loop L5.
[0027] The battery 201 and the onboard charger 202 along with the circulating pump P1, the coolant valve V1, the first type heat exchanger H1 and the coolant reservoir 401 form the first coolant loop L1. The first coolant loop L1 extracts the heat from the battery 201, and onboard charger 202 and discharges the heat to the first type heat exchanger H1. The first coolant loop L1 is active in case of cooling the battery through refrigeration in hot climate as illustrated in Fig. 2.

[0028] The motor 203 and the control unit 204 along with the circulating pump P2, the coolant valve V2, the first type heat exchanger H2, the second type heat exchanger H3 and the fan 303 form the second coolant loop L2. The coolant in the second coolant loop L2 extracts heat from the motor 203, the control unit 204, and the second heat exchanger H2 and discharges the heat to the second type heat exchanger H3. This loop is active in case of cooling the motor 203, control unit 204 and first type heat exchanger H2 using the second type heat exchanger H3 as illustrated in Fig. 2.
[0029] The battery 201, the onboard charger 202, the motor 203 and the control unit 204 along with the circulating pump P1, the coolant valves V1 and V2, the second type heat exchanger H3, the fan 303 and the coolant reservoir 401 form the third coolant loop L3. The third coolant loop L3 bypasses the refrigerant loop and thermally connects battery 201 and onboard charger 202 to motor 203 and control unit 204; this way, the operation of the refrigeration system in cold climate is disabled. The heat from the battery 201 and onboard charger 202 can be directly rejected to the second type heat exchanger H3 as illustrated in Fig. 3.
[0030] The battery 201, the onboard charger 202, the motor 203 and the control unit 204 along with the circulating pump P1, the coolant valves V1 and V2 and the coolant reservoir 401 form the fourth coolant loop L4. The fourth coolant loop L4 thermally connects the battery 201 and the onboard charger 202 to the motor 203 and the control unit 204; this loop is used to heat up the battery from the heat produced from motor 203 and control unit 204 in cold climate as illustrated in Fig. 4.
[0031] The compressor 302, the expansion valve 301, the receiver drier 402 and the first type heat exchangers H1 and H2 form the refrigerant loop L5. A refrigerant loop is the one in which working fluid is a refrigerant. The refrigerant is circulated in a cyclic path and undergoes phase change between liquid and gas. The refrigerant in the refrigerant loop L5

provides cooling to the first heat exchanger H1 and discharges the heat to the second heat exchanger H2. This loop is only operated in hot climate as illustrated in Fig. 2. [0032] To maintain the optimal temperature of various components in powertrain, a (control method [CR|L1]is disclosed, in accordance with embodiments of the present disclosure. The conditions involved for control are:
[Case 1] Operating the vehicle in hot climate
[Case 2] Operating the vehicle in cold climate
[Case 3] Charging the vehicle in hot climate
[Case 4] Charging the vehicle in cold climate
[Case 5] Preconditioning the vehicle in hot climate
[Case 6] Preconditioning the vehicle in hot climate
[0033] The term ‘hot climate’ refers to a range of environmental temperature at which there is
insufficient heat transfer (due to low log mean temperature difference) from the second
type heat exchanger H3 to the environment while the refrigeration is bypassed.
[0034] The term ‘cold climate’ refers to a range of environmental temperature at which there is sufficient heat transfer (due to high log mean temperature difference) from the second type heat exchanger H3 to the environment while the refrigeration is bypassed.
[0035] Following terms are defined for further explanation of control method of the thermal management system of the present invention:
Tbattery - the battery temperature
Td,upper & Td,lower - the upper and lower threshold of safe discharging temperature of the battery respectively
Tc,upper & Tc,lower - the upper and lower threshold of safe charging temperature of the battery respectively
ΔTlm - the log mean temperature difference in the ambient air and coolant inside the second type heat exchanger H3
ΔTlm,d- the desired log mean temperature difference in the ambient air and coolant inside the second type heat exchanger H3 for effective heat transfer

where the log mean temperature difference follows general definition as in any heat transfer literature.
[0036] The control method comprises the operation of the first coolant loop L1, the second coolant loop L2, the third coolant loop L3, the fourth coolant loop L4 and the refrigerant loop L5 in accordance to the battery temperature, ambient air temperature, battery charging and discharging rate.
[0037] The loop switching is achieved using coolant valves V1 & V2.
[0038] In one example embodiment, preconditioning is provided to bring the battery temperature to a safe discharging temperature range (between Td,upper & Td,lower) before discharging as indicated in 501, 502 and 503 in Fig.5. The vehicle is then operated as indicated in 504. Heat produced in the battery 201, motor 203, control unit 204 is then determined from the discharge rate of the battery as indicated in 505 & 506. Depending on the climate condition (hot or cold), the refrigerant loop is either operated or bypassed to keep the battery 201 within a safe discharging temperature range as indicated in 507, 508 and 509.
[0039] In another example embodiment, preconditioning is provided to bring the battery temperature to a safe charging temperature range (between Tc,upper & Tc,lower) before charging as indicated in 601, 602, 603, 604 and 605 in Fig.6. The charging is then switched on and heat produced from the battery 201 is determined from charging rate as indicated in 606. Depending on the climate condition (hot or cold), the refrigerant loop is either operated or bypassed to keep the battery 201 within a safe charging temperature range as indicated in 607, 608 and 609.
[0040] If the log mean temperature difference in the ambient air and coolant inside the second type heat exchanger H3 is sufficient enough for effective heat transfer from second type heat exchanger H3 to the environment (cold climate), the refrigeration loop L5 is bypassed

using coolant valves V1 & V2 and thermal management system can be operated as illustrated in Fig. 3.
[0041] If the log mean temperature difference in the ambient air and coolant inside the second type heat exchanger H3 is insufficient for effective heat transfer from second type heat exchanger H3 to the environment (hot climate), the refrigeration loop L5 is switched on using coolant valves V1 & V2 and thermal management system can be operated as illustrated in Fig. 2.
[0042] The thermal management system 100 of the present disclosure, provides advantages in weight and cost of the overall vehicle due to the use of less number of parts. Moreover, the control method as disclosed in the foregoing description operates less number of parts simultaneously to provide temperature regulation, thereby reducing the power consumption.
[0043] While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person skilled in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.
[0044] The figures and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of processes described herein may be changed and are not limited to the manner described herein. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts necessarily need to be performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples.

Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of embodiments is at least as broad as given by the following claims.

1. A thermal management system 100 in an electric vehicle for managing temperature of powertrain, the thermal management system comprising:
at least one battery 201;
an onboard charger 202 operatively coupled to at least one battery 201;
a reservoir 401 operatively coupled to the onboard charger 202 to supply coolant to the
system 100;
a first pump P1 operatively coupled to the battery 201, wherein the first pump P1 is
operatively coupled to a first coolant valve V1;
a first type heat exchanger H1 operatively coupled to the reservoir 401;
a compressor 302 operatively coupled to the first type heat exchanger H1;
a receiver drier 402 to supply refrigerant to the system 100;
wherein the receiver drier 402 is further operatively coupled to the first type heat
exchanger H2;
an expansion valve 301 operatively coupled to the first type heat exchanger H2;
wherein the expansion valve is operatively coupled to the first type heat exchanger H1;
a second coolant valve V2 operatively coupled to the reservoir 401; wherein the second
coolant valve V2 is further operatively coupled to the first type heat exchanger H2;
a control unit 204 operatively coupled to the second coolant valve V2;
a motor 203 operatively coupled to the control unit 204;
a second type heat exchanger H3 operatively coupled to the motor 203, wherein the
second type heat exchanger H3 comprises a fan 303, wherein the second type heat
exchanger H3 is operatively coupled to the first type heat exchanger H2 via a second
pump P2, wherein the second type heat exchanger H3 is coupled to the first coolant
valve V1;

a sensor coupled to the control unit 204, wherein the sensor detects battery 201 temperature and ambient temperature;
wherein the control unit 204 defines an upper threshold and a lower threshold for the temperature of battery 201, wherein the temperature above the upper threshold indicates that the battery 201 is to be cooled, wherein the temperature below the lower threshold indicates that the battery 201 is to be heated, wherein the temperature between the upper threshold and the lower threshold indicates a safe operating range for the battery 201, wherein the control unit 204 charges the battery 201 when the sensor detects that the temperature is in the safe charging range,
the control unit 204 operates the onboard charger 202, the reservoir 401, the first type heat exchanger H1, the first coolant valve V1, the second coolant valve V2, the first pump P1, the second pump P2, the compressor 302, the receiver drier 402, the expansion valve 301, the first type heat exchanger H2, the second type heat exchanger H3, the fan 303 in order to charge the battery 201 in the safe charging temperature range.
2. The thermal management system 100 as claimed in claim 1, wherein the control unit 204 operates the motor 203, the reservoir 401, the first type heat exchanger H1, the first coolant valve V1, the second coolant valve V2, the first pump P1, the second pump P2, the compressor 302, the receiver drier 402, the expansion valve 301, the first type heat exchanger H2, the second type heat exchanger H3, the fan 303 at the time of preconditioning the electric vehicle to bring the temperature of the battery 201 to the safe charging temperature range.
3. The thermal management system 100 as claimed in claim 1, wherein the refrigerant is a mixture of more than one refrigerants.

4. The thermal management system 100 as claimed in claim 1, wherein the refrigerant comprises additives.
5. The thermal management system 100 as claimed in claim 1, wherein the coolant is one of a liquid or a gas.
6. The thermal management system 100 as claimed in claim 1, wherein the coolant comprises additives.
7. The thermal management system 100 as claimed in claim 1, wherein the second type heat exchanger H3 is a radiator.
8. A thermal management system 100 in an electric vehicle for managing temperature of powertrain, the thermal management system comprising:
at least one battery 201;
an onboard charger 202 operatively coupled to at least one battery 201;
a reservoir 401 operatively coupled to the onboard charger 202 to supply coolant to the
system 100;
a first pump P1 operatively coupled to the battery 201, wherein the first pump P1 is
operatively coupled to a first coolant valve V1;
a first type heat exchanger H1 operatively coupled to the reservoir 401;
a compressor 302 operatively coupled to the first type heat exchanger H1;
a receiver drier 402 to supply refrigerant to the system 100;
wherein the receiver drier 402 is further operatively coupled to the first type heat
exchanger H2;
an expansion valve 301 operatively coupled to the first type heat exchanger H2;
wherein the expansion valve is operatively coupled to the first type heat exchanger H1;
a second coolant valve V2 operatively coupled to the reservoir 401; wherein the second
coolant valve is further operatively coupled to the first type heat exchanger H2;

a control unit 204 operatively coupled to the second coolant valve V2; a motor 203 operatively coupled to the control unit 204; a second type heat exchanger H3 operatively coupled to the motor 203, wherein the second type heat exchanger H3 comprises a fan 303, wherein the second type heat exchanger H3 is operatively coupled to the first type heat exchanger H2 via a second pump P2, wherein the second type heat exchanger H3 is coupled to the first coolant valve V1;
a sensor (not shown in the figures) coupled to the control unit 204, wherein the sensor
(not shown in the figures) detects battery 201 temperature and ambient temperature;
wherein the control unit 204 defines an upper threshold and a lower threshold for the
temperature of battery 201, wherein the temperature above the upper threshold indicates
that the battery 201 is to be cooled, wherein the temperature below the lower threshold
indicates that the battery 201 is to be heated, wherein the temperature between the upper
threshold and the lower threshold indicates a safe operating range for the battery 201,
wherein the control unit 204 discharges the battery 201 when the sensor detects that the
temperature is in the safe discharging range,
the control unit 204 operates the motor 203, the reservoir 401, the first type heat
exchanger H1, the first coolant valve V1, the second coolant valve V2, the first pump
P1, the second pump P2, the compressor 302, the receiver drier 402, the expansion
valve 301, the first type heat exchanger H2, the second type heat exchanger H3, the fan
303 in order to discharge the battery 201 in the safe discharging temperature range.
9. The thermal management system 100 as claimed in claim 9, wherein the control unit 204
operates the motor 203, the reservoir 401, the first type heat exchanger H1, the first coolant
valve V1, the second coolant valve V2, the first pump P1, the second pump P2, the
compressor 302, the receiver drier 402, the expansion valve 301, the first type heat

exchanger H2, the second type heat exchanger H3, the fan 303 at the time of preconditioning the electric vehicle to bring the temperature of the battery 201 to the safe discharging temperature range.
10. The thermal management system 100 as claimed in claim 9, wherein the refrigerant is a mixture of more than one refrigerants.
11. The thermal management system 100 as claimed in claim 9, wherein the refrigerant comprises additives.
12. The thermal management system 100 as claimed in claim 9, wherein the coolant is one of a liquid or a gas.
13. The thermal management system 100 as claimed in claim 9, wherein the coolant comprises additives.
14. The thermal management system 100 as claimed in claim 9, wherein the second type heat exchanger H3 is a radiator.

.