Automotive thermal management system key parts disassembly series report

In terms of thermal management technology, Tesla has iterated three versions of technology routes in the four models of Model S/X/3/Y; it has strong technical accumulation in motor waste heat recovery, large integrated control valves, motor stall technology, vehicle thermal management calibration and intelligent thermal management algorithms.

In order to better understand Tesla’s technological iterations and highly integrated thermal management technologies, today we will briefly introduce Tesla’s first and second generation thermal management systems.

Tesla's first generation thermal management system

System architecture schematic diagram

The first generation thermal management system is used in Model S and Model X, with three circuits: air conditioning circuit, battery circuit, and motor circuit. The main difference is that the Model S passenger compartment heating relies on A-PTC, while the Model X replaces A-PTC with warm air and relies on W-PTC in the battery circuit to heat the passenger compartment. This solution connects the motor thermal management circuit and the battery thermal management circuit in series through a four-way valve, and relies on the characteristics of the multi-way valve to switch the series and parallel connection of different circuits, and introduces the high-temperature refrigerant in the motor thermal management circuit into the low-temperature battery circuit to heat the battery pack.

Domestic manufacturers' early thermal management technology generally connected the three major circuits of motor, battery and car air conditioning in parallel (such as NIO ES8 and Xiaopeng G3). It was not until the first generation of technology after 2018 that the motor cooling circuit and battery circuit were connected in series by adding a four-way valve/three-way valve to realize the function of motor waste heat recovery. However, Tesla has designed this function in the Model S launched in 2013.

System mode cycle diagram

Air conditioning circuit

Passenger compartment cooling through refrigeration cycle

Heating the passenger compartment via air PTC

Battery circuit-refrigeration cycle

Through the refrigerant circulation on the chiller side and the battery coolant circuit, it absorbs the heat in the battery and reduces the battery temperature

Battery circuit - heating cycle 1

Battery heating through water PTC heating

Battery circuit - heating cycle 2

Battery heating through electric drive waste heat + water PTC heating

Electric drive circuit-refrigeration cycle 1 (small cycle)

Based on the large specific heat value of the coolant, the temperature of the electric drive system is maintained through the self-circulation of the electric drive circuit

Electric drive circuit-refrigeration cycle 2 (small cycle)

Based on the larger specific heat value of the coolant, and the heat absorption of the battery and insulation layer, the temperature of the electric drive system is maintained, and the cycle is consistent with the battery heating cycle 2

Electric drive circuit-refrigeration cycle 3 (large cycle)

The low-temperature radiator dissipates heat to the environment to ensure that the temperature of the electric drive system does not get too high

Tesla's second-generation thermal management system

The second-generation thermal management system is used in the Model 3. Compared with the first-generation system, the second-generation system uses a Supper bottle integrated valve body. By assembling two electronic water pumps, a chiller, a three-way valve and a four-way valve together, it realizes the preliminary integration of valves, pumps and exchangers in the thermal management circuit, which can greatly save the number of unnecessary valve bodies and pump bodies in the circuit to save costs, and simplify the piping structure to reduce the weight of the vehicle.

In the Model 3 system, Tesla can also integrate the AD AS controller and battery pack management module into the cooling circuit by optimizing the pipeline design, and add an oil cooling module to assist cooling, greatly improving thermal management efficiency.

Another technical point of the second-generation system is the use of motor stall heating technology to replace W-PTC to generate heat to meet the heating needs of the battery.

Compared with Model S, it saves: 1 W-PTC, 1 electronic water pump, 1 expansion kettle, 1 three-way valve, 1 condenser, 2 electronic fans, and some pipes.

System architecture diagram

System mode cycle diagram

Air conditioning circuit

Passenger compartment cooling through refrigeration cycle

Heating the passenger compartment via air PTC

Battery circuit-battery refrigeration cycle

The refrigerant circulation on the chiller side is coupled with the battery coolant circuit to absorb the heat in the battery and reduce the battery temperature

Battery circuit-heating cycle

In heating mode, the battery and power electronics circuits are connected in series and bypass the main radiator, allowing heat to accumulate. When the battery needs to be heated, the coolant is pumped to the rear management module, enters the oil cooling heat exchanger in the drive unit to obtain heat, transfers from the radiator through the integrated valve and directly passes through the cooler to heat the battery. Tesla actually uses the motor stall to generate a lot of heat to heat the battery, which can save a water heater.

Electric drive circuit-refrigeration cycle 1 (small cycle)

Refrigeration cycle 2 is the battery heating cycle

Electric drive circuit-refrigeration cycle 2 (large cycle)

Tesla's third-generation thermal management system

Model Y uses the third-generation thermal management system, which has four major highlight technologies: (1) Valve body integration technology (2) Motor stall technology (3) Intelligent thermal management algorithm (4) Multi-function heat pump technology