Variable switching period to achieve minimum output current ripple of discontinuous PWM three-phase voltage source inverters

A new method to achieve minimum output current ripple of discontinuous PWM three-phase voltage source inverters is presented in this paper. The proposed method is realized by varying the switching period based on the total current ripple pattern. To show the general applicability of the proposed method, analytical expressions for output current ripple of the inverter as a function of the discontinuous modulation signals are derived. This method provides general expressions to control the current ripple of the inverter without sacrificing the switching losses of the inverter. It is shown that by using this technique, the minimum output current ripple is obtained. Experimental results are included to show the validity of the proposed concept.