Four Switches Three Phase Inverter Space Vector Modulation Considering DC-link Capacitors Voltage Imbalance for PMSM drive

the four-switch three-phase inverter topology has been treated as a fault tolerant topology for three phase machine drive system. Since one phase is connected to the midpoint of two serious capacitors on the DC-link, the voltage vector can be consisting of only two long voltage vectors and two short voltage vectors. The zero voltage vector needs to be synthesized by these four voltage vectors. However, the two capacitors continuously charge and discharge, which lead to imbalance of two capacitor voltage. When the capacitance is small, the voltage imbalance problem will be aggravated, further deteriorating the control performance. In this paper, the influence of capacitor value on the voltage balance issue is explored and proposes an equivalent synthesis method of zero vector voltage. A two-voltage space vector modulation method considering the voltage imbalance problem is presented. Simulation and experiments prove the effectiveness of the method.