Claims:WE CLAIM

1. A thermal management system 1000 in an electric vehicle for managing temperature of powertrain, the thermal management system comprising:
at least one battery 1010;
an onboard charger 1020 operatively coupled to at least one battery 1010;
a reservoir 1120 operatively coupled to the onboard charger 1020 to supply coolant to the system 1000;
a first pump 1081 operatively coupled to the battery 1010, wherein the first pump 1081 is operatively coupled to a first coolant junction 1131;
a first type heat exchanger 1051 operatively coupled to the reservoir 1120, wherein the first type heat exchanger 1051 is operatively coupled to a coolant valve 1071;
a compressor 1090 operatively coupled to the first type heat exchanger 1051;
a receiver drier 1110 to supply refrigerant to the system 1000, wherein the receiver drier 1110 is further operatively coupled to a first type heat exchanger 1052;
an expansion valve 1100 operatively coupled to the first type heat exchanger 1052, wherein the expansion valve 1100 is operatively coupled to the first type heat exchanger 1051;
a second coolant valve 1075 operatively coupled to the first type heat exchanger 1052, wherein the second coolant valve 1075 is further operatively coupled to a second coolant junction 1132;
a control unit 1040 operatively coupled to the second coolant junction 1132;
a motor 1030 operatively coupled to the control unit 1040;
a second type heat exchanger 1053 operatively coupled to the motor 1030, wherein the second type heat exchanger 1053 comprises a fan 1060, wherein the second type heat exchanger 1053 is operatively coupled to the first type heat exchanger 1052 via a second pump 1082, wherein the second type heat exchanger 1053 is further coupled to the first coolant junction 1131 via a third coolant valve 1072 and a fourth coolant valve 1073;
a fifth coolant valve 1075 operatively coupled to the second coolant junction 1132, wherein the fifth coolant valve 1075 is further coupled to the reservoir 1120;
a sensor (not shown in the figures) coupled to the control unit 1040, wherein the sensor detects battery 1010 temperature and ambient temperature;
wherein the control unit 1040 defines an upper threshold and a lower threshold for the temperature of battery 1010, wherein the temperature above the upper threshold indicates that the battery 1010 is to be cooled, wherein the temperature below the lower threshold indicates that the battery 1010 is to be heated, wherein the temperature between the upper threshold and the lower threshold indicates a safe operating range for the battery 1010,
wherein the control unit 1040 charges the battery 1010 when the sensor detects that the temperature is in the safe charging range,
the control unit 1040 operates the onboard charger 1020, the first coolant valve 1071, the second coolant valve 1072, the third coolant valve 1073, the fourth coolant valve 1074, the fifth coolant valve 1075, the first pump 1081, the second pump 1082, the compressor 1090, the expansion valve 1100, the fan 1060 in order to charge the battery 1010 in the safe charging temperature range.

2. The thermal management system 1000 as claimed in claim 1, wherein the control unit 1040 operates the motor 1030, the first coolant valve 1071, the second coolant valve 1072, the third coolant valve 1073, the fourth coolant valve 1074, the fifth coolant valve 1075, the first pump 1081, the second pump 1082, the compressor 1090, the expansion valve 1100, the fan 1060 at the time of preconditioning the electric vehicle to bring the temperature of the battery 1010 to the safe charging temperature range.
3. The thermal management system 1000 as claimed in claim 1, wherein the refrigerant is a mixture of more than one refrigerant.
4. The thermal management system 1000 as claimed in claim 1, wherein the refrigerant comprises additives.
5. The thermal management system 1000 as claimed in claim 1, wherein the coolant is one of a liquid or a gas.
6. The thermal management system 1000 as claimed in claim 1, wherein the coolant comprises additives.
7. The thermal management system 1000 as claimed in claim 1, wherein the second type heat exchanger 1053 is a radiator.
8. A thermal management system 1000 in an electric vehicle for managing temperature of powertrain, the thermal management system comprising:
at least one battery 1010;
an onboard charger 1020 operatively coupled to at least one battery 1010;
a reservoir 1120 operatively coupled to the onboard charger 1020 to supply coolant to the system 1000;
a first pump 1081 operatively coupled to the battery 1010, wherein the first pump 1081 is operatively coupled to a first coolant junction 1131;
a first type heat exchanger 1051 operatively coupled to the reservoir 1120, wherein the first type heat exchanger 1051 is operatively coupled to a coolant valve 1071;
a compressor 1090 operatively coupled to the first type heat exchanger 1051;
a receiver drier 1110 to supply refrigerant to the system 1000, wherein the receiver drier 1110 is further operatively coupled to the first type heat exchanger 1052;
an expansion valve 1100 operatively coupled to the first type heat exchanger 1052, wherein the expansion valve 1100 is operatively coupled to the first type heat exchanger 1051;
a second coolant valve 1075 operatively coupled to the first type heat exchanger 1052, wherein the second coolant valve 1075 is further operatively coupled to a second coolant junction 1132;
a control unit 1040 operatively coupled to the second coolant junction 1132;
a motor 1030 operatively coupled to the control unit 1040;
a second type heat exchanger 1053 operatively coupled to the motor 1030, wherein the second type heat exchanger 1053 comprises a fan 1060, wherein the second type heat exchanger 1053 is operatively coupled to the first type heat exchanger 1052 via a second pump 1082, wherein the second type heat exchanger 1053 is further coupled to the first coolant junction 1131 via a third coolant valve 1072 and a fourth coolant valve 1073;
a fifth coolant valve 1075 operatively coupled to the second coolant junction 1132, wherein the fifth coolant valve 1075 is further coupled to the reservoir 1120;
a sensor (not shown in the figures) coupled to the control unit 1040, wherein the sensor detects battery 1010 temperature and ambient temperature;
wherein the control unit 1040 defines an upper threshold and a lower threshold for the temperature of battery 1010, wherein the temperature above the upper threshold indicates that the battery 1010 is to be cooled, wherein the temperature below the lower threshold indicates that the battery 1010 is to be heated, wherein the temperature between the upper threshold and the lower threshold indicates a safe operating range for the battery 1010,
wherein the control unit 1040 discharges the battery 1010 when the sensor detects that the temperature is in the safe discharging range, the control unit 1040 operates the motor 1030, the first coolant valve 1071, the second coolant valve 1072, the third coolant valve 1073, the fourth coolant valve 1074, the fifth coolant valve 1075, the first pump 1081, the second pump 1082, the compressor 1090, the expansion valve 1100, the fan 1060 in order to discharge the battery 1010 in the safe discharging temperature range.
9. The thermal management system 1000 as claimed in claim 8, wherein the control unit 1040 operates the motor 1030, the first coolant valve 1071, the second coolant valve 1072, the third coolant valve 1073, the fourth coolant valve 1074, the fifth coolant valve 1075, the first pump 1081, the second pump 1082, the compressor 1090, the expansion valve 1100, the fan 1060 at the time of preconditioning the electric vehicle to bring the temperature of the battery 1010 to the safe discharging temperature range.
10. The thermal management system 1000 as claimed in claim 8, wherein the refrigerant is a mixture of more than one refrigerant.
11. The thermal management system 1000 as claimed in claim 8, wherein the refrigerant comprises additives.
12. The thermal management system 1000 as claimed in claim 8, wherein the coolant is one of a liquid or a gas.
13. The thermal management system 1000 as claimed in claim 8, wherein the coolant comprises additives.
14. The thermal management system 1000 as claimed in claim 8, wherein the second type heat exchanger 1053 is a radiator.
, Description:
FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)

“ELECTRIC VEHICLE POWERTRAIN THERMAL MANAGEMENT SYSTEM”
By
Emflux Motors Pvt. Ltd.
An Indian Company
No. 16, Bhuvanappa Layout, Tavarekere Main Road, Kaveri Layout, Suddagunte Palya, Bengaluru, Karnataka 560029

The following specification particularly describes the invention and the manner in which it is to be performed.

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 in an EV.

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 e.g. battery pack, power electronics units e.g. Motor Controller or Control Unit, and Motors. 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.
[005] Therefore, there is a need for an improved system and method for maintaining optimal temperature of vehicle powertrain components.

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 battery pack) 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 the 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 1000 in an electric vehicle, in accordance with embodiments of the present disclosure comprises of at least one battery 1010, an onboard charger 1020, at least one motor 1030, a control unit 1040 having sensor, first type heat exchangers 1051 and 1052, a second type heat exchanger 1053, a fan 1060, coolant valves 1071 to 1075, pumps 1081 and 1082, a compressor 1090, an expansion valve 1100, a receiver-drier 1110, a coolant reservoir 1120 and coolant junctions 1131 and 1132.
[0023] The present disclosure does not intend to limit the type of above-mentioned components. For example, the compressor 1090 can be either of scroll compressor, reciprocating compressor, etc. Similarly, the battery 1010, the onboard charger 1020, the motor 1030, the control unit 1040, the heat exchangers 1051, 1052 and 1053, the circulating pumps 1081 and 1082, the expansion valve 1100, the coolant valves 1071 to 1075, the fan 1060, receiver drier 1110, the coolant reservoir 1120 and the coolant junctions 1131 and 1132 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 1010 is not limited. The batteries 1010 may be thermally connected in series or parallel or a combination of both.
[0025] The number or arrangement of motors 1030 is not limited. The motors 1030 may be thermally connected in series or parallel or a combination of both.
[0026] The thermal management system 1000 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 1201, a second coolant loop 1202, a third coolant loop 1203, a fourth coolant loop 1204 and a refrigerant loop 1205.
[0027] The battery 1010 and the onboard charger 1020 along with the circulating pump 1081, the coolant valve 1071, the coolant junction 1131, the first type heat exchanger 1051 and the coolant reservoir 1120 form the first coolant loop 1201. The first coolant loop 1201 extracts the heat from the battery 1010, and onboard charger 1020 and discharges the heat to the first type heat exchanger 1051. The first coolant loop 1201 is active in case of cooling the battery through refrigeration in hot climate as illustrated in Fig. 2.
[0028] The motor 1030 and the control unit 1040 along with the circulating pump 1082, the coolant valve 1072, the coolant junction 1132, the first type heat exchanger 1052, the second type heat exchanger 1053 and the fan 1060 form the second coolant loop 1202. The coolant in the second coolant loop 1202 extracts heat from the motor 1030, the control unit 1040, and the second heat exchanger 1052 and discharges the heat to the second type heat exchanger 1053. This loop is active in case of cooling the motor 1030, control unit 1040 and first type heat exchanger 1052 using the second type heat exchanger 1053 as illustrated in Fig. 2.
[0029] The battery 1010, the onboard charger 1020, the motor 1030 and the control unit 1040 along with the circulating pump 1081, the coolant valves 1073 and 1075, the coolant junctions 1131 and 1132, the second type heat exchanger 1053, the fan 1060 and the coolant reservoir 1120 form the third coolant loop 1203. The third coolant loop 1203 bypasses the refrigerant loop 1205 (explained later in paragraph 0032) and thermally connects battery 1010 and onboard charger 1020 to motor 1030 and control unit 1040; this way, the operation of the refrigeration system in cold climate is disabled. The heat from the battery 1010 and onboard charger 1020 can be directly rejected to the second type heat exchanger 1053 as illustrated in Fig. 3.
[0030] The battery 1010, the onboard charger 1020, the motor 1030 and the control unit 1040 along with the circulating pump 1081, the coolant valves 1074 and 1075, the coolant junction 1131 and 1132, and the coolant reservoir 1120 form the fourth coolant loop 1204. The fourth coolant loop 1204 thermally connects the battery 1010 and the onboard charger 1020 to the motor 1030 and the control unit 1040; this loop is used to heat up the battery from the heat produced in motor 1030 and control unit 1040 in cold climate as illustrated in Fig. 4.
[0031] The compressor 1090, the expansion valve 1100, the receiver drier 1110 and the first type heat exchangers 1051 and 1052 form the refrigerant loop 1205. 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 1205 provides cooling to the first heat exchanger 1051 and discharges the heat to the second heat exchanger 1052. 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 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 cold 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 1053 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 1053 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
?Tlm - the log mean temperature difference in the ambient air and coolant inside the second type heat exchanger 1053
?Tlm,d - the desired log mean temperature difference in the ambient air and coolant inside the second type heat exchanger 1053 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 1201, the second coolant loop 1202, the third coolant loop 1203, the fourth coolant loop 1204 and the refrigerant loop 1205 in accordance with the battery temperature, ambient air temperature, battery charging and discharging rate.
[0037] The loop switching is achieved using coolant valves 1071 to 1075. The valves may be operated electronically by a controller and power source present in the electric vehicle.
[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 5010, 5020 and 5030 in Fig.5. The vehicle is then operated as indicated in 5040. Heat produced in the battery 1010, motor 1030, control unit 1040 is then determined from the discharge rate of the battery and/or sensors in the thermal management system 1000 as indicated in 5050 & 5060. Depending on the climate condition (hot or cold), the refrigerant loop is either operated or bypassed to keep the battery 1010 within a safe discharging temperature range as indicated in 5070, 5080 and 5090.
[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 6010, 6020, 6030, 6040 and 6050 in Fig.6. The charging is then switched on and heat produced from the battery 1010 is determined from charging rate and/or sensors in the thermal management system 1000 as indicated in 6060. Depending on the climate condition (hot or cold), the refrigerant loop is either operated or bypassed to keep the battery 1010 within a safe charging temperature range as indicated in 6070, 6080 and 6090.
[0040] If the log mean temperature difference in the ambient air and coolant inside the second type heat exchanger 1053 is sufficient enough for effective heat transfer from second type heat exchanger 1053 to the environment (cold climate), the refrigeration loop 1205 is bypassed using coolant valves 1071 & 1075 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 1053 is insufficient for effective heat transfer from second type heat exchanger 1053 to the environment (hot climate), the refrigeration loop 1205 is switched on using coolant valves 1071 to 1075 and thermal management system can be operated as illustrated in Fig. 2.
[0042] The thermal management system 1000 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.