A Combined DPWM Based on DSOGI-FLL for Switching-Loss Reduction and Dead-Time Compensation

High efficiency and high output power quality of converters are always two goals pursued in power electronic systems. In this paper, the conventional discontinuous pulse width modulation (DPWM) for switching-loss reduction and a modified time-based dead-time compensation for reducing output current harmonics are investigated. And a combined DPWM for switching-loss reduction and dead-time compensation is proposed, where the amplitude adjustment and the zero-sequence injection in modulation waves are carried out separately in different current intervals related to polarities of three-phase currents. Moreover, in order to detect accurate polarities of the three-phase currents with ripples and harmonics, the second-order generalized integrator frequency-locked loop (DSOGI-FLL) is adopted and inserted into the combined DPWM. Finally, a combined DPWM based on DSOGI-FLL is proposed for switching-loss reduction and dead-time compensation. The comparison of experimental results with several PWM schemes verifies that, the proposed PWM scheme can both effectively reduce the switching loss and compensate the dead-time, simultaneously enhancing the efficiency and the output power quality of the converter.