A capacitor voltage balancing method with zero-voltage switching for split phase inverter

This paper presents a new method of current control that employs burst mode in order to balance the dc-side capacitor voltages of split phase inverters. By alternating the inductor current in every switching period, zero-voltage switching (ZVS) can be achieved, which avoids the reverse recovery issue of power MOSFETs. As a result, super-junction MOSFETs instead of IGBTs can be employed to achieve higher efficiency. Combining the hysteresis current control with traditional pulse-width modulation (PWM), a new burst mode control method is proposed in this paper. The minimum operation time during a set modulation period is limited then the efficiency at the light load can be increased. A buck-and-boost converter is employed as the auxiliary circuit for the capacitor voltage balancing circuit. Due to the proposed ZVS method, inductor volume can be reduced. A prototype with 25 A current capacity is built to verify all the performance of the presented control method. The efficiency over the whole load range is over 98% with a peak efficiency of 98.4%.