New PWM strategy for nine-switch inverters with minimum number of semiconductor switching

Controllability of the nine-switch inverter is studied with the switched linear system model. On the basis of analysis results, a novel space vector pulse modulation (SVPWM) strategy is proposed. Compared with the classic SVPWM strategy, the number of operation modes used in the novel modulation strategy is reduced by half, therefore the switching sequence of the vectors can be simplified. In addition, the switching frequencies of the power semiconductors are significantly reduced by two-thirds. Therefore, the switching losses of the power devices can be reduced and the efficiency of the inverter can be improved. Simulation and experimental results verified the correctness of the proposed SVPWM strategy.