Hybrid digital control of dual buck half bridge inverter

Dual buck half bridge inverter(DBHBI) has a benefit of no shoot-through issue, however, severe waveform distortion is badly undesirable. Hysteresis control is commonly used to improve output quality, which has fast dynamic response and easy to approach. Since the switching frequency in the hysteresis control is unfixed, voltage loss and harmonic frequency issues are inevitable. The paper proposes a novel hybrid sine pulse width modulation control strategy. When the inductor current is greater than the critical inductor current, DBHBI is switched to the half-cycle SPWM mode, otherwise, to the full-cycle SPWM mode. Besides, nonlinear relationship between input and output is optimized to linear relationship which facilitates the controller. In addition, the influences of the mode transition are discussed, and control methods to solve distortion problems under different traditions are proposed. Finally, simulation and experiment results demonstrate the superior performance of implemented strategy on waveform improvement.