Three-level hysteresis band modulation strategy for single-phase PWM inverters

A novel three-level adaptive hysteresis band modulation strategy for single -phase inverters is presented. It is shown that the total harmonic current distortion of the new strategy closely approximates that of the off-line pr ecalculated harmonic minimised PWM switching angle solution sets. It is sho wn that the three-level adaptive hysteresis band strategy can be defined us ing a modulation process possessing both pulse-width and pulse-position mod ulation. Two strategies are presented to determine the switching angles in one quarter of the fundamental period of the PWM and the advantages of each method are discussed using a digital signal processor implementation. Both simulation and experimental results for the three-level adaptive hysteresi s band PWM strategy are presented to confirm the theoretical analysis.