Sample Time Staggered One-cycle Control Strategy of Three-phase H-bridge Cascaded Inverter

An one-cycle control strategy was proposed for three-phase H-bridge cascaded inverter. The formula of switch duty ratio of each inverter unit was derived. It was pointed out that the average value of the switch variables in each switching cycle can be made equal or proportional to the control reference by controlling the switch duty ratio. In order to increase level number of output voltage of the cascaded inverter, a scheme was proposed of applying sample time staggered technique in the one-cycle control strategy of cascaded inverter, namely staggering the sampling time of each inverter unit. The simulation result verified fesibility of the sample time staggered one-cycle control strategy applied in three-phase H-bridge cascaded inverter, and the strategy can make output voltage of the inverter have small harmonic content with quick response and strong robustness.