A dual-buck based equalizer operating in burst-mode for split phase inverter

Abstract

This paper presents a new method of current control that utilizes burst mode in order to balance the dc side capacitor voltages of split phase inverters. The outer voltage control loop employs hysteresis control, which provides fast transient response. When this voltage control loop is used in conjunction with the burst mode current loop, the efficiency at light load is improved and the capacitor voltages are more precisely balanced. A dual-buck converter is employed as the balancing auxiliary circuit, which has higher reliability due to the avoidance of shoot-through as well as avoiding the reverse recovery issue of the power MOSFET. No reverse recovery allows the use of super-junction MOSFETs instead of IGBTs in order to achieve higher efficiency. A 4 kW prototype with 400 V dc bus voltage is built to verify all the performance and a peak efficiency of 98.3% is achieved.