Class-E-based charge-equalisation circuit for battery cells

The aim of this study is to carry out a charge-equalisation circuit for ten series-connected lithium battery cells. This circuit is composed of a class-E inverter and a multi-winding transformer, which can constantly perform the equalisation task. In addition, the zero-voltage-switching feature of the class-E inverter helps reduce the switching loss and boosts the operation efficiency of the equalisation circuit. With the application of the class-E inverter, only one active switch is present in this circuit. Since adaptation of the duty ratio is not required, the circuit control task is very simple, and can be easily realised by a low-cost pulse-width-modulation (PWM) control chip.