Common-mode voltage reduction PWM technique for wide speed range control of induction motor drives fed by inverter with diode front end

The main theme of this paper is to demonstrate the applications of the newly developed common-mode voltage reduction PWM technique, which restricts the common-mode voltage to one third of DC-link voltage, to vector-controlled induction motor drives. As compared to previous common-mode voltage reduction techniques, either only for inverter with PWM-controlled front end or resulting in the reduction of linear modulation range, the presented technique can be applied to the inverter with diode front end and has no adverse effect on the linear modulation range. Therefore, the vector-controlled drives using the developed technique for inverter control are with wide speed range. Moreover, the effects of the common-mode voltage reduction PWM technique on speed response for vector-controlled induction motor drives is fully investigated in this paper. It is demonstrated by intensive experimental results that speed performance is not deteriorated significantly within the rated speed range.