Optimized Design and Operation Control of Refrigerant Direct Cooling Thermal Management System for Power Battery

Abstract

In order to solve the compatibility problem of lithium batteries thermal management and cabin comfort in electric vehicles, a refrigerant direct cooling thermal management system is designed in this article, which is expected to balance the temperature demands of entire vehicle at different driving conditions. A one‐dimensional model is established to investigate the system performance, whose accuracy has been verified by the testing bench of a prototype fixed with a 16‐battery module. By the aid of this model, the thermal characteristics of the battery pack and the passenger cabin are obtained, and the compressor speed as well as the valves are selected as control units by sensitivity analysis of the important components. Subsequently, detailed control strategies around the variable frequency of compress speed and switch regulation for the valves are proposed based on the temperature changes, torque, and operating power consumption of the system in different control modes. Under the test conditions of the global light‐duty vehicle test procedure, it is found that cabin temperature can be quickly stabilized about 26 °C under different ambient temperatures. Additionally, the battery pack can be effectively maintained within the safe operating temperature range of 20–40 °C.