Battery low temperature self-heating technology

The solution for low-temperature heating of the battery is to use self-heating, that is, a resistor is embedded inside the battery, and when heating is required, the internal circuit of the battery is connected to achieve a controllable "internal short circuit". After the current is passed, heat is generated, and the heating effect on the battery helium leak detection is realized from the inside of the battery. When the battery temperature reaches the preset temperature, disconnect the circuit, and the battery will return to the normal working mode.

This scheme can achieve the heating effect from -45°C to 0°C within 45 s, consumes 5% SOC of power, and the temperature difference between inside and outside is less than 5°C. It has been partially commercialized, but the safety and reliability of this scheme still need to be further developed. Verification, and the difficulty of control at the battery pack level is still relatively high.

Fuel Auxiliary Heating System

In actual operation, in order to minimize the energy loss during the heating process of the whole vehicle, one idea is to use an external energy source, such as an auxiliary heating system driven by fuel. For example, Weimar EX5 uses a parking heater driven by a diesel engine. This solution uses diesel as the energy source of the heating system, which can heat the cabin and battery system at low temperatures, and reduces power consumption by 13.24% when running at low temperatures and fully charged. Kwh, battery life increased by 100Km, thus solving the problem of low heating efficiency at low temperature.

This scheme is essentially similar to a hybrid scheme, but the fuel consumption is relatively small, and the heating efficiency is also high, which is generally feasible.

Carbon dioxide or the main medium of air-conditioning refrigerant

According to different refrigerants, vehicle heat pump air conditioners mainly include multiple technical routes such as R134a, R1234yf and R744 (CO2). R134a does not meet regulatory requirements, R1234yf has barriers, and patents are monopolized. R134a is the third-generation traditional refrigerant, and its GWP (Global Warming Potential) does not meet the requirements of the European Union. It has been banned from being used in new cars sold in the European Union since 2017. R1234yf is the fourth-generation refrigerant, which is approved by DuPont and Honeywell. patent monopoly.

In terms of environmental protection performance, the greenhouse effect of R1234yf and CO2 is relatively close, and neither will cause damage to the ozone layer. In terms of heating performance helium leak detection system, the energy efficiency ratio (COP) of the R134a and R1234yf schemes dropped significantly at low temperatures (-10°C). It can reach 2, because in terms of performance, the CO2 heat pump solution is expected to become one of the mainstream choices in the future. However, representative companies include Mercedes-Benz and Volkswagen, etc., but their working pressure is 10 times higher than that of ordinary refrigerants, and the cost of system pressure upgrade is high.