EFFICIENT MULTI-LOOP THERMAL MANAGEMENT ARCHITECTURE AND THE CONTROL SYSTEM FOR ELECTRICAL POWER TRAIN VEHICLES

FIELD OF THE INVENTION

The preferred invention is related to the comfort in passenger cabin in Electric Vehicles (EV). Air Conditioning (AC) System is necessary to provide comfort for the driver and the passengers, especially in hot regions. Therefore, the present invention is specifically an Efficient multi-loop thermal management architecture and the control system for electrical power train vehicles, which is also added as battery cooling systems, traction motor cooling system, etc.
BACKGROUND OF THE INVENTION
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.
In the current scenario, many ideas and applications try to condition pure electric coaches, but cooling or heating range is not enough to cater all working conditions especially low cooling requirements, and these kind of systems are not advisable for countries like India where weather conditions change drastically from one place to another. Also, they are typically used for cooling the coach, not for other thermal management of pure electric coaches. The referred system uses heat pump system for heating, which has better efficiency than PTC heater but cannot be used in countries like Europe, North America, and Russia, etc., where the temperature goes below zero very often. However, by adding the PTC heater to this system, the system is enabled to work at sub-zero temperature. The heat pump system has been very efficient in countries like India, UAE, etc. These heat pump systems are prioritized to have a high energy-efficient system (high COP: Coefficient of Performance) for heating systems.
Currently, for the larger size of vehicles, electric bus, have a quite large range of cabin thermal management requirements, serving different numbers of people and different climate conditions. But there is no efficient thermal management architecture and control system

dealing with this large load variation. Typically, only one big cabin thermal management system is designed for max capacity and is used for the smallest thermal load as well. For the low load condition with the necessity of managing all cabin space, one big electrical compressor control is difficult and not efficient, even having durability issues due to bad oil return. Then, if the compressor is seized, all the system stops, and the bus cannot operate for repair work. There is a need to address this kind of an issue and provide an efficient solution.
Therefore, there is a need for a cabin cooling system for pure electric commercial vehicles used in hot and humid climate regions, in which all AC subsystems of a single system run simultaneously to provide effective cooling to the passenger cabin. This cabin cooling system is intended to be integrated with the cabin, the battery, and the traction motor to create heating of cabin, battery cooling system, and traction motor cooling system additionally. Furthermore, this need for such a cabin cooling system is targeted towards hot regions such as India, Gulf coast countries, Thailand, a part of Africa, and the countries closer to the equator, where most of the area experience hot climatic conditions and where the temperature rarely goes to below 0 Degree Celsius.
SUMMARY OF THE INVENTION
It is intended that all such features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims. The following summary is provided to facilitate an understanding of some of the innovative features unique to the disclosed embodiment and is not intended to be a full description. A full appreciation of the various aspects of the embodiments disclosed herein can be gained by taking the entire specification, claims, drawings, and abstract as a whole.
As comfort and vehicle range both are important on an electric vehicle and AC system is also the largest energy consumer after propulsion system, it must be efficient in all load conditions (Low, Mid, High) to maximise the driving range with a single full charge of the battery. At the same time, thermal management systems should be affordable with minimal cost of ownership.
The present invention is providing a system solution having features listed below:

- Integrating multiple subsystems of thermal management system into one thermal system to cool pure electric vehicles cabin, battery, and electronics.
- Heat transfers in each subsystem is managed using vapour compression refrigeration cycle driven by an electric compressor, heat exchangers, thermal expansion valves and connecting pipes.
- Each AC System (system subsystem) has a specific performance and outlet air of each AC system is collected and distributed through blowers.
- Each system consists of an evaporator, a condenser, a variable speed compressor, an expansion valve connected with AC lines and an accumulator, if it is heat pump system or a receiver dryer, if it is a cooling system, assembled before the e-Compressor in AC lines, electrical fans for the condenser, and blowers for the evaporator. AC unit also consists of a DCDC converter for low voltage requirements and a control unit to provide signals to different components.
- This integrated AC system and other thermal management systems are adapted for the application being used in both hot and moderate climate regions.
- Heating of the passenger cabin is done by changing the AC system into a heat pump using 3-way valves and straight through valves and thermal expansion valves with solenoid valves.
- All the thermal management system subsystems are controlled together by a controller unit, which also provides complete control on electric compressor, condenser fans, and blowers to achieve the desired performance.
- By adding a chiller with an expansion device and a coolant circuit to the thermal management system, the electric vehicle battery is cooled during charging and discharging.
- Using controller units, the system is controlled for very low cooling or heating requirements by running only one or two refrigerant subsystems (based on requirements) or just cool batteries with minimum cooling and shut off cabin cooling systems. This will reduce frequent cut-off of the system during low load and reduce power requirements.
The thermal management system for electrical power train vehicles comprises multiple subsystems for vapour compression of a refrigerant, wherein each subsystem is interconnected to the adjoining subsystem. Each subsystem includes connecting pipes, a compressor, a condenser, and an evaporator. The connecting pipes connect the compressor, the condenser, and the evaporator to circulate a refrigerant. The compressor compresses refrigerant vapour to increase temperature and pressure of the refrigerant. The condenser

condenses the high pressure and high-temperature refrigerant from the compressor using ambient air. The evaporator in communication with the compressor and the condenser absorbs heat from the air to generate the refrigerant vapour. The subsystems operate either in combination or separately to control heat load conditions in the vehicle at the same time depending on either a low or high heat load condition. In an embodiment, one or more subsystems are run in of combination or separately using a controller based on heat load conditions, wherein the controller operates based on different inputs from or more sensors, a control panel and a vehicle control unit (VCU) feedback, wherein variable performance is generated when the controller runs alternative subsystems during either low cooling or heating requirements.
The thermal management system for electrical power train vehicles uses multiple refrigerant vapour compression circuits where each works independently and have at least one e-compressor for each of the circuits. This multi-sub system includes a complete in combination as well as an independent thermal load control for each circuit at the same time, allowing to manage lowest heat load condition with high energy efficiency and continuous system operations to high load conditions with maximum cooling/heating and it also compensates accidental stop of one or some independent systems by using other systems capability without stopping vehicle operation by the control system due to loss of cooling or heating.
The basic principle for the referred air conditioning system is a vapour compression refrigerant cycle that comprises multiple subsystems of the refrigeration cycle. In an embodiment, each refrigeration cycle consists of one electric compressor, an air-cooled condenser, 2 expansion valves, 2 solenoid valves, one 3-way flow control valve for refrigerant at compressor discharge, one evaporator, one PTC heater, and connecting pipes. Condenser fan and blower are common components for all the subsystems. An air conditioning system for hot climate regions of electric buses use the basic principles of vapour compression refrigerant cycle, which comprises multiple subsystems of the refrigeration cycle. These refrigeration cycles run individually and separately based on requirements. In an example embodiment, one subsystem or two subsystems or all subsystems are run together by using a control unit, which operates this system based on different inputs from sensors, control panel and vehicle control unit (VCU) feedback. In an

embodiment, alternative subsystems are run to get better performance during low cooling or heating requirements. This is achieved by using proper logic in the controller unit.
In an embodiment, the integrated system of battery and cabin cooling is using the basic principle of vapour compression cycle and single-phase coolant cycle and each thermal management circuit comprises of one electric compressor, an air-cooled condenser, 3 expansion valves, 3 solenoid valves, one 3-way flow control valve for refrigerant at compressor discharge, one evaporator, one PTC heater, one chiller as a common heat exchanger between two cycles, one electric water pump, connecting pipes and coolant hoses.
In an embodiment, a solenoid valve is placed before both expansion valves. This solenoid valve blocks the refrigerant flow in connecting pipes and blocking of flow depends on the cooling system or heating system. In an embodiment, a 3-way valve is used to change the direction of refrigerant flow at compressor discharge to change cooling mode to heat pump mode. In an embodiment, coolant temperature sensors are placed at the inlet and outlet of the battery pack to check and control coolant flow and its temperature using a control unit. In an embodiment, at least one pressure and temperature sensor is placed after the compressor. In an embodiment, at least one air temperature sensor is placed at the outlet of the evaporator and condenser in each circuit. In an embodiment, one cabin air temperature sensor is placed before the evaporator to provide input to the controller. In an embodiment, all components, which includes electric compressors, condensers, expansion valves, chillers, pumps and evaporators are packaged in one container.
In an embodiment, using sensor input and other input from the VCU in the vehicle data network, one control unit is controlling the total system including, electric compressors, condenser fans, blowers, 3-way valve, electric water pumps and solenoid valves. In an embodiment, connecting pipes between components are made of Aluminium pipes and ethylene propylene diene monomer (EPDM) hose. In an embodiment, the container is made from fibre reinforced plastic (FRP) material. The thermal management system disclosed here is used in all climatic conditions with the addition of different components but is more efficient and effective in hot climate regions, for example, Delhi, Pune, and Chennai in India, Thailand, Spain, Africa, Gulf coast countries, etc.

BRIEF DESCRIPTION OF DRAWINGS
The invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
FIGS. 1A and IB illustrates an AC System diagram that shows the combination of 4 subsystems of the thermal management system, where FIG. IB shows how all the 4 subsystems that are separated in refrigerant circuit but connected for air side flow.
FIG. 1C shows a vehicle data network, that enables a controller to control the thermal management system.
FIG. 2A illustrates a single AC subsystem of the thermal management system that shows one out of 4 subsystems as all are symmetric, for example, the HVAC subsystem.
FIG. 2B illustrates a cooling mode system diagram of the HVAC subsystem of the thermal management system that shows how cooling happens in an AC system along with non-operative lines during cooling.
FIG. 2C illustrates a heating mode system diagram of the HVAC subsystem of the thermal management system that shows how heating happens in AC system along with non-operative lines during heating.
FIG. 3A illustrates a combination of heating and cooling circuit during low requirements in the thermal management system, which shows a circuit when there is low or very low cooling or heating requirements for vehicle cabin, then subsystem 2 and subsystem 4 are used to reduce compressor cycling and power consumption.
FIG. 3B illustrates a combination of heating and cooling circuit during low requirements in the thermal management system, which shows a circuit when we have low or very low cooling or heating requirements for vehicle cabin, then subsystem 1 and subsystem 3 are used to reduce compressor cycling and power consumption.

FIG. 4A illustrates an integrated cabin cooling and battery cooling system for one system of the thermal management system, where the same is extended to all the subsystems and is used to maintain vehicle battery temperature during charging and discharging along with passenger cabin cooling.
FIG. 4B illustrates a subsystem of the thermal management system during battery charging and shows an active system during battery charging of a pure electric vehicle.
FIG. 5 illustrates an air conditioning system of the thermal management system with low load conditions, which shows only one subsystem that maintains cabin comfort during very low load conditions.
FIG. 6 illustrates a multi-zone air conditioning system of the thermal management system, where different cabin zones are maintained at different temperatures.
FIG. 7 illustrates two flexible subsystems of the thermal management system, where the number of subsystems is changeable based on vehicle thermal load.
DESCRIPTION OF THE INVENTION
The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, persons skilled in the art will recognize that various changes and modifications to the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
The terms and words used in the following description are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to the person skilled in the art that the following description of exemplary embodiments of the present invention are provided for

illustration purpose only. It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.
The present invention aims to provide a thermal management system for cabin cooling of pure electric commercial vehicles used in hot and humid climate region, in which all AC System subsystems run simultaneously to provide effective cooling to the passenger cabin. The foregoing advantages, as well as the working of the thermal management system, will become more noticeable and understandable from the following detail description thereof when read in conjunction with the accompanying drawings.
Referring to FIGS. 1A-1C, FIG. 1A and IB illustrate an AC System diagram that shows the combination of 4 subsystems 1, 2, 3, and 4 of the thermal management system 100, where Fig.IB shows how all the 4 subsystems 1, 2, 3, and 4 are separated in the refrigerant circuit but connected for airflow. FIG. 1C shows a vehicle data network 200, that enables a controller 202 to control the thermal management system 100. As used herein, subsystems 1, 2, 3, and 4 are represented by Loops 1, 2, 3, and 4, respectively as shown in Fig. IB. In general, the proposed multi-sub system thermal management architecture and the control system, or in short, the thermal management system 100, uses the basic principles of vapour compression refrigeration cycle. Each air conditioning subsystem 1, 2, 3, or 4 include an electric compressor 104, multi-flow condenser 106, thermal expansion valve (TXV) 110, solenoid valve 112, 3-way valve 114, evaporator 108, accumulator 120 and connecting pipes 102. The thermal management system 100 is packaged in a single container made of Fibre-reinforced plastic (FRP) material. The connecting pipes 102 are made of Aluminium and ethylene propylene diene monomer (EPDM).
As disclosed here, the components for each subsystem 1, 2, 3, and 4 are separately denoted with a, b, c, and d. For example, the components in subsystem 1 include the electric compressor 104a, multi-flow condenser 106a, thermal expansion valve (TXV) 110a, solenoid valve 112a, 3-way valve 114a, evaporator 108a, accumulator 120a and connecting pipes 102. The components in subsystem 2 include the electric compressor 104b, multi-flow condenser 106b, thermal expansion valve (TXV) 110b, solenoid valve 112b, 3-way valve 114b, evaporator 108b, accumulator 120b and connecting pipes 102. The components in subsystem 3 include the electric compressor 104c, multi-flow condenser 106c, thermal expansion valve

(TXV) 110c, solenoid valve 112c, 3-way valve 114c, evaporator 108c, accumulator 120c and connecting pipes 102. The components in subsystem 4 include the electric compressor 104d, multi-flow condenser 106d, thermal expansion valve (TXV) llOd, solenoid valve 112d, 3-way valve 114d, evaporator 108d, accumulator 120d and connecting pipes 102.
The compressor 104 is powered by a battery pack 128, compresses the refrigerant vapour thereby increasing temperature and pressure of the refrigerant. The condenser 106 is used to condense high pressure and high-temperature refrigerant using ambient air and the TXV 110 controls refrigerant pressure, temperature, and refrigerant flow before the evaporator 108 based on pressure and temperature setting defined for TXV 110. Refrigerant pressure and temperature sensor 118 after compressor 104 are used as the controller 202 input data. The controller 202 is, for example, is in communication with the vehicle control unit or the electronic control unit (ECU) 122, as shown in all the FIGS. 1-7. The 3-Way valve 114 after the compressor 104 switches refrigerant flow toward condenser 106 for cooling mode and toward evaporator 108 for heating mode. As shown in Figs. 2A-2C, there are also condenser fans 126 and blowers 124 to control airflow across the condenser 106 and evaporator 108 respectively and transfer heat between refrigerant and air.
As shown in FIG. 1C, using the input data from the refrigerant pressure and temperature sensors 118 and the VCU 122 defined in a vehicle data network 200, the controller 202 controls each subsystem 1, 2, 3, and 4 of the thermal management system 100 that includes the compressors 104, condenser fans 126, blowers 124, 3-way valve 114, electric water pumps 130 and the solenoid valves 112. As shown in FIG. 2A, at least one air temperature sensor 134a is positioned at outlet of the evaporator 108 and the condenser 106 in each subsystem 1, 2, 3, and 4 which is in communication with the controller 202. Based on FIGS 4A-4B, coolant temperature sensors 132a and 132b placed at inlet and outlet of a battery pack 128 checks and controls coolant flow and temperature of the coolant using the controller 202. The coolant temperature sensors 132a and 132b comprise a Battery Inlet Temp Sensor (BITS) and a Battery Out Temp Sensor (BOTS) respectively. Based on FIG. 2A, a cabin air temperature sensor 134b that is positioned before the evaporator 108 provide input regarding temperature of the cabin to the controller 202. Furthermore, an outside air temperature sensor 136 is positioned in each subsystem 1, 2, 3, and 4, which is in communication with the controller 202 to detect and transmit data regarding temperature of outside air.

With references to FIGS. 2A-2C, Fig. 2A illustrates a single subsystem, for example, subsystem 1 of the thermal management system 100 that shows one out of 4 subsystems 1, 2, 3, and 4 as all are symmetric, for example, the HVAC subsystem. Fig. 2B illustrates a cooling mode system diagram of the HVAC subsystem 1 of the thermal management system 100 that shows how cooling happens in an AC system along with non-operative lines during cooling. During the cabin cooling, refrigerant pumped by compressor 104 flows through the 3-way valve 114 and is directed toward condenser 106 by the 3-way valve 114, wherein the flow towards evaporator 108 is blocked by deactivating the 3-way valve 114 using a controller 202. Then the refrigerant flows through condenser 106 and heat transfer that occurs through the condenser 106 condenses the refrigerant. The refrigerant then flows up to the evaporator 108 through TXV 110, where the refrigerant absorbs heat from the air to cool the passenger cabin. Furthermore, at least one air temperature sensor 134a-is positioned at outlet of the evaporator 108 and the condenser 106 in each subsystem 1, 2, 3, and 4 to measure the air temperature. The air temperature sensors 134a and 134b comprise an Evaporator Air Temp Sensor (EATS) and a Return Air Temp Sensor (RATS) respectfully. In an embodiment, at least one cabin air temperature sensor 134b is positioned before the evaporator 108 to provide input regarding temperature of the cabin to the controller 202.
Fig. 2C illustrates a heating mode system diagram of the HVAC subsystem of the thermal management system 100 that shows how heating happens in AC system along with non-operative lines during heating. During the cabin heating, refrigerant pumped by compressor 104 will flow through the 3-way valve 114 and is directed toward evaporator 108 by the 3-way valve 114, where flow towards condenser 106 is blocked by deactivating the 3-way valve 114 using the controller 202. Then refrigerant flows through the evaporator 108, which acts as a condenser in this case and heat transfer from refrigerant to air through evaporator 108 heats the air from the cabin. Refrigerants then flows to the condenser 106 through TXV 110, where air adds heat to the refrigerant.
This subsystem 1 of the thermal management system 100 further comprises a PTC heater 116, which is protected so that this unit is used in low temperature (below 0 Degree C) ambient conditions also. PTC heaters 116 heat the cabin air for some time before a certain temperature in the cabin is achieved, where the heat pump works effectively. Also, PTC

heaters 116 are used for faster heating of the cabin initially. Performance of thermal management system 110 is further increased by adding components like, for example, internal heat exchangers (IHX) to the system based on requirements, this will also increase COP for the thermal management system 100.
Therefore, based on FIGS. 1A-2C, the thermal management system 100 for electrical power train vehicles comprises multiple subsystems 1, 2, 3, and 4 for vapour compression of a refrigerant, wherein each subsystem 1, 2, 3, or 4 is interconnected to the adjoining subsystem 1, 2, 3, or 4. Each subsystem 1, 2, 3, or 4 includes connecting pipes 102, a compressor 104, a condenser 106, and an evaporator 108. The connecting pipes 102 connect the compressor 104, the condenser 106, and the evaporator 108 to circulate a refrigerant. The compressor 104 compresses refrigerant vapour to increase temperature and pressure of the refrigerant. The condenser 106 condenses the high pressure and high-temperature refrigerant from the compressor 104 using ambient air. The evaporator 108 in communication with the compressor 104 and the condenser 106, absorbs heat from the air to generate the refrigerant vapour. The subsystems 1, 2, 3, or 4 operate either in combination or separately to control heat load conditions in the vehicle at the same time depending on either a low or high heat load condition. In an embodiment, one or more subsystems 1, 2, 3, or 4 are run either in combination or separately using a controller 202 based on heat load conditions, wherein the controller 202 operates based on different inputs from or more sensors 118, 132 (a,b), and 134 (a,b), a control panel 138, and a vehicle control unit (VCU) 122 feedback, wherein variable performance is generated when the controller 202 runs alternative subsystems 1, 2, 3, or 4 during a low cooling or heating requirements.
Regarding FIGS. 3A and 3B, FIG. 3A illustrates a combination of heating and cooling subsystems during low requirements in the thermal management system 100, which shows an arrangement when there is low or very low cooling or heating requirements for vehicle cabin, then subsystem 2 and subsystem 4 are used to reduce compressor 104 cycling and power consumption. FIG. 3B illustrates a combination of heating and cooling subsystem 2 and 4 during low requirements in the thermal management system 100, which shows an arrangement when we have low or very low cooling or heating requirements for vehicle cabin, then subsystem 1 and subsystem 3 are used to reduce compressor 104 cycling and power consumption. One of the major benefits of this thermal management system 100 is that

it is operated at a very wide range of performance requirements. In above-proposed AC thermal management system 100, controller 202 unit controls different AC subsystems 1, 2, 3, and 4 independently, which means that it manages very low load condition, for example, when the cooling load is very low, the controller 202 runs only one refrigerant subsystem and reduces the speed of blower 124 and condenser fan 126, which typically reduces the power consumption without losing passenger's comfort.
As seen in FIGS 3A and 3B, the controller 202 changes operation of the thermal management system 100 from one subsystem to another to maintain equal comfort to different zone passenger, for example, a controller 202 initially activates the subsystem 1 (in FIG.l) and after some time it deactivates subsystem 1 and activates subsystem 3 and same way subsystem 3 gets deactivated by controller 202 and subsystem 2 is activated. Again, after some time interval as earlier subsystem 2 is deactivated and subsystem 4 gets activated and this cycle of activating and deactivating is maintained during low load condition.
Also as shown in FIGS. 3A and 3B, during medium load conditions, the thermal management system 100 is operated with less power consumption concerning any conventional air conditioning system by operating alternative subsystems 1, 2, 3 or 4 to maintain the cooling requirements, which also improves compressor 104 durability as less frequent cut off during low/medium cooling or heating requirements. The thermal management system 100 is controlled either way using a controller 202 unit. As shown in FIGS. 2A-3B, this controller 202 for the thermal management system 100 also changes rpm of the blower 124, condenser fan 126 and compressor 104-based set temperature and achieve cabin temperature. This way the thermal management system 100 reduces power consumption and increases battery range for the electrical bus. At the time when loads are high, the thermal management system 100 performs to its maximum capacity to maintain passenger comfort.
Referring to FIGS. 4A and 4B, FIG. 4A illustrates an integrated cabin cooling and battery cooling system 400 for one system of the thermal management system 100, where the same is extended to all the subsystems 1, 2, 3, and 4 and is used to maintain vehicle battery temperature during charging and discharging along with passenger cabin cooling. FIG. 4B illustrates a subsystem of the thermal management system 100 during charging of battery pack 128 and shows an active system during charging of battery pack 128 of a pure electric

vehicle. Another example of how the controller 202 unit controls the thermal management system 100 is when a battery cooling system 400 is integrated with the cabin cooling system or the thermal management system 100 is used. In this case, during charging of the battery pack 128, the AC system is cut off and only the battery cooling system 400 is run with a minimum requirement to maintain battery cell temperature. Furthermore, coolant temperature sensors 132a and 132b are placed at inlet and outlet of a battery pack 128 that powers the thermal management system 100, wherein the coolant temperature sensors 132a and 132b check and control coolant flow and temperature of the coolant using the controller 202. Furthermore, by adding a chiller 140 with an expansion device and a battery cooling system 400 to the thermal management system 100, the electric vehicle battery pack 128 is cooled during charging and discharging.
FIG. 5 illustrates an air conditioning system of the thermal management system 100 with low load conditions, which shows only one subsystem 1 that maintains cabin comfort during very low load conditions. Also, during vehicle running conditions when cabin cooling is not required as the outside ambient temperature is low but at the same time as power train is running and discharging the battery pack 128, the battery pack 128 rejects heat and is required to be cooled to maintain battery pack 128 cell temperature. In such conditions, the blowers 124 are switched off and only the compressor 104 is operated, and fans 126 and the electric water pump 130 are run at a minimum desired speed to maintain the temperature of the battery pack 128 which improves system efficiency during low load conditions.
Another major advantage of this thermal management system 100 is that even if one subsystem 1, 2, 3, or 4 fails during vehicle running condition, it will not create discomfort to passengers. In an embodiment, the combined and separate operation of the subsystems 1 and 3 compensate accidental stoppage of one or more of the subsystems 2 and 4 by using other subsystems 1 and 3 that are operational, to avoid stoppage of operation of the vehicle by the controller 202 due to loss of cooling or heating. In other words, if the thermal management system 100 is used as an integrated system with battery pack 128 cooling, a failure of one subsystem 1, 2, 3, or 4 will not force to stop the vehicle due to battery pack 128 overheating.
FIG. 6 illustrates a multi-zone air conditioning system of the thermal management system 100, where different cabin zones are maintained at different temperature. The thermal

management system 100 is also used as a multi-zone system using a proper partition of zones within the thermal management system 100 and in vehicles, is able to maintain different temperatures at different zones. By adding walls and flaps to the unit and vehicle's air distribution duct, the vehicle cabin are divided into different zones, for example, vehicle zones 1, 2, 3, and 4 as shown in FIG. 6. For an example, the vehicle has 4 zones 1, 2, 3, and 4, assuming that sun is on the left side of the vehicle, in this case, left side of the vehicle has a higher load compared to the right side, by using solar sensor and in-cab temperature sensor load difference between two zones is measured and by using controller 202 unit in different system subsystems 1 and 2 runs with different capacity to maintain the same temperature across the vehicle. Another example is the temperature difference created due to the door opening of the vehicle. Assuming that doors of vehicle are in front and the doors open multiple times during boarding and off-boarding of passengers. In this case, the front side subsystem runs with a higher capacity than the rear to maintain the same temperature across the vehicle cabin.
FIG. 7 illustrates two flexible subsystems 1 and 2 of the thermal management system 100, where the number of subsystems 1, 2, 3, and 4 is changeable based on vehicle thermal load. Another benefit of having a multi-subsystem system 1, 2, 3, and 4 is its flexibility to increase/decrease capacity by changing the number of subsystems 1, 2, 3, and 4. For smaller vehicles, the number of subsystems 1, 2, 3, and 4 is reduced to 1 or 2 and for bigger vehicles, or the number of subsystems 1, 2, 3, and 4 are increased, or a single subsystem 1, 2, 3, or 4 is used with passenger vehicles. Each system subsystem 1, 2, 3, or 4 is packaged independently and joined together to generate higher capacity. It will also help us to easily replace subsystems 1, 2, 3, or 4 during failure.
Most of the AC systems used in a commercial vehicle like the pure electric bus uses refrigerant like R407C, but this thermal management system 100 uses a more environment-friendly Refrigerant R134a, which supports uses of aluminium heat exchangers due to its low pressure working characteristics, even during heat pump system when evaporator 108 works at high refrigerant pressure, this high refrigerant pressure is still lower than the maximum allowed working pressure for the evaporator 108. This thermal management system 100 also uses refrigerant R1234yf (UFO) with some loss in performance or can be supplemented with internal heat exchange (MX) to recover the losses due to capacity reduction of refrigerant.

This thermal management system 100 is also used with refrigerants like C02 with changes in compressor 104, heat exchangers and other refrigerant flow components.
Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore, contemplated that such modifications can be made without departing from the spirit or scope of the present invention as defined.

We Claim:

1. A thermal management system for electrical power train vehicles, comprising:
a plurality of subsystems for vapour compression of a refrigerant, wherein each subsystem is interconnected to the adjoining subsystem, and wherein each subsystem includes:
a plurality of connecting pipes that connects a compressor, a condenser, and an evaporator to circulate a refrigerant;
the compressor compresses refrigerant vapour to increase temperature and pressure of the refrigerant;
the condenser condenses the high pressure and high-temperature refrigerant from the compressor using ambient air; and
the evaporator in communication with the compressor and the condenser, wherein the evaporator absorbs heat from the air to generate the refrigerant vapour, wherein the subsystems operate one of in combination and separately to control heat load conditions in the vehicle at the same time depending on one of a low heat load and a high heat load condition.
2. The thermal management system as claimed in claim 1, wherein each subsystem further
comprises:
at least two expansion valves, wherein each expansion valve controls pressure, temperature, and flow of the refrigerant before the evaporator based on pressure and temperature setting defined for the expansion valve;
at least two solenoid valves, wherein each solenoid valve blocks the refrigerant flow in the connecting pipes depending on whether the thermal management system is in one of a cooling mode and a heating mode;
a 3-way flow control valve to control flow of the refrigerant at discharge of the compressor, wherein the 3-way flow control valve is positioned after the compressor to switch the flow of the refrigerant towards the condenser for the cooling mode and towards the evaporator for the heating mode;
a positive temperature coefficient (PTC) heater that heats air in a cabin of the vehicle for a predefined time before a specific temperature in the cabin is generated; and

a pressure and temperature sensors positioned after the compressor to provide input data to a controller.
3. The thermal management system as claimed in claim 2, wherein one of the combined and the separate operation of the subsystems compensate accidental stoppage of one or more of the subsystems by using other subsystems that are operational, to avoid stoppage of operation of the vehicle by the controller due to loss of cooling or heating.
4. The thermal management system as claimed in claim 2, wherein using the input data from the pressure and temperature sensors and a vehicle control unit (VCU) defined in a vehicle data network, the controller controls each subsystem of the thermal management system that includes the compressors, condenser fans, blowers, 3-way valve, electric water pumps and the solenoid valves.
5. The thermal management system as claimed in claim 2, further comprising a set of coolant temperature sensors that are placed at inlet and outlet of a battery pack that powers the thermal management system, wherein the coolant temperature sensors check and control flow and temperature of coolant using the controller.
6. The thermal management system as claimed in claim 2, further comprising at least one air temperature sensor that is positioned at outlet of the evaporator and the condenser in each subsystem to measure air temperature.
7. The thermal management system as claimed in claim 2, further comprising at least one cabin air temperature sensor that is positioned before the evaporator to provide input regarding temperature of the cabin to the controller.
8. The thermal management system as claimed in claim 2, is packaged in a single container made of Fibre-reinforced plastic (FRP) material.
9. The thermal management system as claimed in claim 8, wherein the connecting pipes are made of Aluminium and ethylene propylene diene monomer (EPDM).

10. The thermal management system as claimed in claim 2, wherein during cooling of the cabin, the refrigerant pumped by the compressor flows through the 3-way valve and is directed toward the condenser by the 3-way valve, wherein flow towards evaporator is blocked by deactivating the 3-way valve using the controller, wherein the refrigerant flows through the condenser and heat transfer in the condenser condenses the refrigerant, and wherein the refrigerant then flows up to the evaporator through the thermal expansion valve, and where the refrigerant absorbs heat from the air present in the cabin to cool the cabin.
11. The thermal management system as claimed in claim 2, wherein during heating of the cabin, the refrigerant pumped by the compressor flows through the 3-way valve and is directed towards the evaporator via the 3-way valve, and flow of the refrigerant towards the condenser is blocked by activating the 3-way valve using the controller, wherein the refrigerant flows through the evaporator that acts as a condenser and transfers heat from the refrigerant to the air and heats the air present in the cabin, and wherein the refrigerant flows to the condenser through the thermal expansion valve, where ambient air adds heat to the refrigerant.
12. The thermal management system as claimed in claim 2, wherein during one of a low cooling and a low heating requirement for the cabin of the vehicle, at least two subsystems are operated to reduce compressor cycling and power consumption.
13. A thermal management system for electrical power train vehicles, comprising:
a plurality of subsystems for vapour compression of a refrigerant, wherein each subsystem is interconnected to the adjoining subsystem, and wherein each subsystem includes:
a plurality of connecting pipes that connects a compressor, a condenser, and an evaporator to circulate a refrigerant;
the compressor compresses refrigerant vapour to increase temperature and pressure of the refrigerant;
the condenser condenses the high pressure and high-temperature refrigerant from the compressor using ambient air; and
the evaporator in communication with the compressor and the condenser, wherein the evaporator absorbs heat from the air to generate the refrigerant

vapour, wherein the one or more subsystems are operated in of combination or separately using a controller based on heat load conditions, wherein the controller operates based on different inputs from one or more sensors, a control panel and a vehicle control unit (VCU) feedback, and wherein variable performance is generated when the controller runs alternative subsystems during one of a low cooling and a low heating requirement.
14. The thermal management system as claimed in claim 13, wherein each subsystem further comprises:
at least two expansion valves, wherein an expansion valve controls pressure, temperature, and flow of the refrigerant before the evaporator based on pressure and temperature setting defined for the expansion valve;
at least two solenoid valves, wherein each solenoid valve blocks the refrigerant flow in the connecting pipes depending on whether the thermal management system is in one of a cooling mode and a heating mode;
a 3-way flow control valve to control flow of the refrigerant at discharge of the compressor, wherein the 3-way flow control valve is positioned after the compressor to switch the flow of the refrigerant towards the condenser for the cooling mode and towards the evaporator for the heating mode;
a positive temperature coefficient (PTC) heater that heats air in a cabin of the vehicle for a predefined time before a specific temperature in the cabin is generated; and
a pressure and temperature sensor positioned after the compressor to provide input data to a controller.