School of Mechanical Engineering,Shanghai Jiao Tong University,China
Project Supported by National Natural Science Foundation of China (Grant No. 51677118); Shanghai Pujiang Program (2017YFE0102000)
In order to solve the performance degradation of automotive lithium-ion battery at low temperature, this paper developed a self-heating method based on traction drive reconfiguration of electric vehicles. In the proposed method, the stator windings were utilized as the energy storage units, so that additional hardware could be eliminated. The detailed mathematical description of AC heating topology was established and the analytical relationship between battery voltage at first, where current and heating control parameters was obtained. Then, an adaptive fuzzy PI controller was implemented on the reconfigured inverter to regulate both the heating current and the charge/discharge voltages of the batteries dynamically. With the proposed control strategy, the heat generation rate could always be guaranteed without triggering severe lithium plating. In addition, in order to relieve mechanical vibration and noise of traction motors, this paper also proposed a torque-cancel scheme during internal heating, ensuring passenger comfort and durability of motors. The results demonstrate effectiveness and superiority of the proposed strategy. The tested batteries are warmed up from -20 °C to above 0 °C within 403 s without permanently damaging the battery life.