Research on the Amplitude Frequency Decoupled AC Heater for Lithium Ion Battery and Its Onboard Implementation

In cold climates, lithium-ion batteries have deteriorated charge-discharge performance so that the driving range of electric vehicles (EVs) will drop substantially. Thus, this paper proposes an alternating current (AC) heater that can heat electric vehicle lithium batteries at low temperatures. Based on the hysteresis current control strategy, the proposed AC heater can generate heating current whose amplitude and frequency can be flexibly controlled. The designed AC heater has a simple structure and can be integrated into the drive circuit and permanent magnet motor of an electric vehicle to realize its on-board application. In addition, the AC heater can act as an equalizer to balance the battery capacity.