A voltage source three phase PWM converter with chopper circuit

This paper presents a novel strategy of a PWM power converter to control output voltage using a chopper circuit. Voltage source PWM converters are unsuitable for general purposes with wide adjustable voltage range. However, the surge voltage at switching becomes small and the input current waveforms have low harmonics and less resonant oscillations as compared with the current source power converters. In this circuit, the input current waveform is controlled by the PWM power converter with the fixed optimum voltage modulation factor and the output voltage amplitude is adjusted by the chopper circuit with very fast response and precise control. The results are verified by experiments. Finally, a control scheme for application to an AC motor drive is presented and discussed.