Three Stages of New Energy Vehicle
Thermal Management System Development
Stage 1
First-Generation Thermal Management System: Battery air-cooled or liquid-cooled, PTC heating, and motor electronically controlled liquid cooling, all operating independently.
In the early stages of new energy vehicle development, the focus was primarily on replacing the engine in gasoline vehicles with batteries and motors. During normal driving, the battery system generates heat, with its efficient operating temperature being 15-35℃. Air cooling was widely adopted in early new energy vehicles due to its simple structure, low cost, and ease of maintenance.
As motor and charging power increased, air cooling could no longer meet the battery thermal management requirements, leading to a gradual upgrade to liquid cooling. In winter, due to lower ambient temperatures, PTC heating was used to heat the coolant, which then transferred the heat to the battery system. Cooling in the passenger compartment continued using the gasoline vehicle-era system: mechanical air conditioning compressors were upgraded to electric compressors; heating was typically achieved using PTC heating. The overall advantages of this solution were simplicity, low cost, and low structural complexity; the disadvantages were high energy consumption and short driving range in winter.
Stage 2
Second-Generation Thermal Management System: Battery liquid cooling, PTC heating, and motor/electronic control liquid cooling. This system utilizes waste heat from the motor/electronic control system to heat the battery system, achieving thermal recycling.
Building upon the first generation, this system connects the motor/electronic control and battery thermal management circuits in series and parallel, fully utilizing the waste heat from the motor/electronic control system to heat the battery system. This reduces PTC usage in winter, improves the overall thermal management efficiency of electric vehicles, and increases their driving range.
For example, the XPeng P7 uses a four-way valve to connect the motor/electronic control cooling circuit and the battery pack assembly cooling circuit. When the battery pack does not require heating, the heat from the motor/electronic control circuit is dissipated through the front-end module's motor radiator assembly. When heating is needed, the coolant carries away the heat from the motor/electronic control system and flows through the battery pack cooling circuit. If the heat is insufficient, PTC provides auxiliary heating for energy saving.
The second-generation thermal management system still uses PTC to meet the heating needs of the cabin and battery. The cabin heating is generally achieved using a fan-heated PTC heater.
The PTC heater heats the surrounding air, and then the blower system blows the air into the cabin to achieve the heating function. Alternatively, a water-based PTC heater can be used to heat the coolant, which then flows through the heater core to provide heating for the cabin. The battery system's heating needs are primarily met by using a water-based PTC heater to heat the coolant and thus the battery pack.
However, PTC heaters typically have a power output of 1-6kW, adding an extra 4-6kWh of energy consumption per 100km. For example, with a full charge driving time of 4-5 hours, PTC heating can reduce the range of a new energy vehicle by 100-150km, which is why the range is reduced when the heater is on in winter.
Stage 3
Third Generation Thermal Management System: This stage adds a heat pump system, resulting in a more efficient and complex overall thermal management system. The refrigerant and water-based systems are integrated, representing a trend towards greater integration, exemplified by the Tesla Model Y.
On the refrigerant side, an indoor condenser and a refrigerant three-way valve are added to meet the heat pump heating requirements, replacing the original high-pressure PTC heater. Two additional low-pressure PTC heaters primarily provide defrosting, defogging, and auxiliary heating functions. Generally speaking, replacing the existing system with a heat pump will save 2-3 kWh of electricity per 100 kilometers, achieving an overall range improvement of 10%-15%.
