Abstract
The authors have proposed a new method to decrease high-frequency harmonics at 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 with a trial-and-error method that involved complex computation procedures in the previous studies. In this paper, a new calculation procedure for obtaining the MT-PWM waveform with a simple calculation is proposed. Second, a new VDS controller (drain-source voltage controller) based on voltage feedback is proposed 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 VDS controller considering the source voltage variation 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 the experiment.
