Analysis and evaluation of zero-voltage-transition converters applied to DC motor drives

Zero-voltage-transition (ZVT) converters which combine pulse-width modulati on (PWM) with the soft-switching characteristics have very low voltage and current stress and the soft switching of the rectifier diode. Therefore, ZV T-PWM converters can increase the switching frequency and consequently redu ce the ripple current. Although the ZVT-PWM converter has the above advanta ges, the application of ZVT-PWM converter to DC motor dl-ive has not been d iscussed until now. This paper will analyse and discuss the characteristics of ZVT-PWM technique applied to the separately-excited and series DC motor drives. Effects of switching frequency and duty cycle on efficiency: speed characteristic and ripple current for the various DC motors are also inves tigated. The comparison of the ZVT-PWM converter-fed DC motor with the trad itional hard-switching PWM topology shows that the ZVT-PWM converter-fed DC motor can reduce switching loss and ripple current and improve the efficie ncy evert if the load variation is very large. Furthermore, the performance improvement after the addition of art adequate filter is also appreciated in this paper.