Improved Modified Switching Transient Pulse Width Modulation (MT‐PWM) Method Applied to H‐Bridge Type Step‐Down Converter

The authors have devised a new method to decrease high‐frequency harmonics in a specific frequency band by modifying the switching transient slope. In previous studies, there were several problems in applying modified transient pulse width modulation (MT‐PWM) to actual converters. In this paper, three problems are solved using an improved MT‐PWM method. First, the MT‐PWM signal was obtained using a trial‐and‐error approach that involved complex computation procedures in the previous studies. In this paper, a new calculation procedure for obtaining the MT‐PWM waveform using a simple calculation is proposed. Second, a new controller (drain‐source voltage controller) based on voltage feedback is proposed in order to realize a modified switching transient to increase the stability of the switching operation. Third, the dependency of MT‐PWM on source voltage variation is investigated in order to implement MT‐PWM in an actual step‐down converter. From this result, the concept of a new type of controller with the source voltage variation taken into consideration is proposed. Finally, the authors attempted to apply MT‐PWM to an H‐bridge converter to expand the application of MT‐PWM. An H‐bridge converter with MT‐PWM for a dc motor drive is successfully operated in an experiment.