Study on generalized switch functions for motor drive inverter

Based on the single-to-single phase matrix conversion technique, switch functions for a single-to-three phase matrix power converter are derived. Furthermore, the above idea is introduced into a conventional rectifier-inverter (RI), and so-called generalized switch functions are proposed. Such switch functions are characteristic of the follow-up of DC-link voltage variation and frequency drift, bringing about size-reductions in DC-link electrolytic capacitor and improved mains side power factor. In particular, when a valley-fill-filter substitutes for the electrolytic capacitor, the mains side power factor is much higher. Additionally, all the other switch functions, such as saddle wave PWM and flat-roofed wave PWM can also be deduced according to the same rule. Another point to be noticed is that such switch functions is identical in essence with those deduced from three-to-three phase matrix conversion. In the paper, all the above are discussed in theory and proved by simulation results, which is helpful to seek after generality among AC converters