Research on thermal management system of Tesla electric vehicle

Heating link: Mainly for cockpit heating, heat pump and internal heat exchange system are the mainstream. In the design of Model 3, Tesla abandoned the high-pressure PCT heater solution and creatively used the motor and related controller to generate heat to provide a heat source. The motor heat is recovered during normal driving, and the motor still rotates alone to generate heat when stationary. The Model Y design adds a heat pump system, and chooses to use a compressor, a blower in low-efficiency mode, and a low-power PCT as a supplementary heat source. In addition, Tesla innovatively uses an eight-way valve as a bridge connecting the cooling link and the heat pump system on the Model Y, realizing series and parallel connection between several systems, and further simplifying the complexity of the valves and pipelines of the thermal management system.

Only after thermal management calibration and obtaining the parameters of each component and the whole vehicle at different temperatures can the above-mentioned complex vehicle intelligent thermal management algorithm be applied. Generally speaking, recalibration is required every 2°C, and the heat conducted between different circuits must be coordinated. Thermal management calibration is so complicated that it takes 100-200 vehicles to complete the calibration, and the calibration cost is as high as tens of millions on average. Tesla Model Y obtained the thermal parameters of each module in series and parallel after hundreds of calibrations in the laboratory. The accuracy is comparable to that of Japanese manufacturers such as Toyota, and is far ahead of other competitors. In addition, as Tesla's thermal management technology becomes more mature, Model Y can also upgrade the thermal management algorithm through the OTA system, optimize the control of each component according to the owner's driving habits, and achieve more intelligent thermal management.

4. Research and judgment on thermal management technology routes

4.1 The general trend of heat pump air conditioning

The cruising range of new energy vehicles has always been a key concern, and the current battery energy density improvement has encountered a bottleneck, so reducing the energy consumption of the entire vehicle is particularly critical. The advantages of the heat pump system over PTC air conditioners are very obvious. In winter, it can greatly reduce the energy consumption of the entire vehicle, thereby greatly improving the cruising range. The main reasons why most domestic manufacturers have been slow to install them are: (1) The technology is not up to standard, and the problems of low heating efficiency and heating capacity and evaporator frosting cannot be solved in winter; (2) Cost reasons, the heat pump will increase the value of each vehicle by an average of 1,000-2,000 yuan, and the willingness to install A00-class EVs is low; (3) Policy reasons, many domestic OEMs are still waiting for the country to provide technical guidance on refrigerants, and a few have begun to focus on CO2 media. However, from the Tesla Model Y, we can find that by using motor waste heat recovery, motor stall technology, compressor and blower waste heat utilization and other technologies, Tesla has perfectly solved the problems of low COP and insufficient heating capacity of the heat pump system at low temperatures, and the outdoor evaporator does not frost in the range of -5℃-5℃. Therefore, in the foreseeable future, with technological breakthroughs and clear policies, heat pump air conditioners will be used by more OEMs due to their excellent COP ratio. Therefore, we expect that heat pump systems will become standard for new energy vehicles priced at more than 150,000 yuan; at the same time, as costs decrease, heat pump systems are expected to be installed in lower-priced A00-class EVs.

4.2 Integrated applications accelerate penetration

BYD Dolphin uses integrated thermal management technology. Dolphin is the first model equipped with the e-platform 3.0 architecture. Its integrated thermal management (refrigerant) technology is based on the heat pump electric air-conditioning compressor and the integrated thermal management control module as the core. The generated "cold" or "heat" is redistributed to different demand units (cockpit, blade battery, electric drive, etc.). BYD has carried out large-scale integration of the refrigerant circuit, greatly reducing the complexity of the coolant circuit.

4.3 Local cost reduction and efficiency improvement continue

Under the high-voltage fast-charging technology route, battery thermal management technology has been upgraded. On June 23, 2022, CATL released the Kirin battery thermal management technology, which optimizes the water cooling system structure design to adapt to the thermal management requirements of high-voltage fast charging (high current charging and discharging, shortening charging time) of new energy vehicles, and improves thermal conductivity by 50%.

4.4 Environmental protection promotes the upgrade of air conditioning refrigerants

Environmental protection promotes the upgrade of air conditioning refrigerants, and the fourth-generation refrigerants are accelerating penetration. Heat pumps using R1234yf refrigerant are compatible with existing heat pump parts and have lower costs, but the refrigerant patent is still under protection; R744 (carbon dioxide) refrigerant heat pump air conditioners have better heating effects at minus 20 degrees, but the cost is higher.

The high-end version of the Volkswagen ID.4 CROSS model can be equipped with an optional CO2 heat pump air conditioner: the cost of carbon dioxide gas itself is low, but the cost of updating thermal management parts is high. The price of the Volkswagen ID.4 carbon dioxide heat pump optional package is 9,000 yuan, including a thickened air compressor to adapt to the high pressure of carbon dioxide refrigerant operation, and the use of high-pressure valves (leakage prevention) to ensure reliability in long-term operation.

5. Investment Analysis

From the trend level, the new energy vehicle thermal management industry has entered the 2.0 era, with supply chain flattening, efficiency improvement, cost reduction and responsiveness as the core driving forces:

1) Technical level: Technology upgrades such as heat pump air conditioning + integrated control have become the mainstream trend. In particular, the mass production of Tesla Model Y in 2020 has accelerated the iteration cycle and application of thermal management solutions. At this point in time, the industry's technology iteration is still continuing;

2) Spatial level: 2021 is the first year of rapid growth of global new energy vehicles, with domestic sales increasing by 165% year-on-year and a penetration rate of 13.4%; coupled with the increase in the value of each vehicle caused by the upgrade of thermal management solutions, the thermal management market space is expanding rapidly; it is estimated that the domestic market space in 2021-2025 will reach 17.3/30.1/40.1/50.2/60.6 billion yuan, respectively, a year-on-year increase of 199%/74%/33%/25%/21%, respectively.

3) Layout level: The industry space will expand rapidly in 2021. After increasing production, OEMs will actively develop demand for point B suppliers, and new industry entrants such as Top and Dun'an will increase their layout.

At present, the division of labor in the thermal management industry chain of new energy vehicles is relatively clear. The OEMs dominate system design and software control, and the core competitive factor of Tier1 lies in the self-development and self-production capabilities of the underlying components. The thermal management system of fuel vehicles is simple and the supply chain is mature: the OEM directly purchases the assembly from air-conditioning system manufacturers (Valeo, Denso, Hanon, etc.); the thermal management system of new energy vehicles is more complex, and the OEM dominates the system design and development. Sanhua and other original Tier2 upgraded to Tier1, mainly because of: 1) Technical differences: Thermal management system solutions continue to upgrade, and OEMs need to have know-how, and the original Tier1 assembly companies are difficult to meet the needs; 2) Rapid response: The R&D cycle of new energy new models is shortened, and it is more efficient for OEMs to face parts suppliers directly; 3) Reduce costs: As Tier1 direct suppliers, parts manufacturers and decentralized supply chains are conducive to OEMs to improve their bargaining power.

Domestic Tier 1 is expected to gradually establish a global leading position with the advantages of rapid technology iteration and cost leadership. At present, domestic thermal management component manufacturers all have their own core technologies: Sanhua Intelligent Control's product portfolio and technological innovation have taken the lead, while Yinlun, Aotecar, Songzhi Co., Ltd., and Kelai Electromechanical have strong technical reserves in heat exchangers, compressors, and pipelines. In the international thermal management market, Japanese and Korean thermal management manufacturers have firmly controlled the supply channels of OEMs such as Toyota and Hyundai with their deep accumulation; traditional American and German thermal management giants are also developing together with overseas OEMs, hoping to accelerate their entry into the new energy vehicle thermal management market.