Characteristics of independent two induction motor variable speed drives fed by a four-leg inverter with vector control method

This paper presents the experimental results of the independent drive of the two induction motors (IMs) fed by a four -leg inverter with vector control method. The inverter consists of four legs and two capacitors connected in a series. Recently the four-leg inverter and four switch inverter have been studied, but they have several disadvantages. First, the balanced three-phase current cannot be obtained. Second, the drift phenomenon is happened by the two capacitor voltages fluctuation. This paper resolves the unbalance of three-phase current by vector control method. This paper also analyzes the drift phenomenon of the neutral point potential of two capacitors and compensates it. Next, the independent drive of two IMs fed by the four-leg inverter with the vector control method is demonstrated by the experimental results. Moreover, relation between capacitance of capacitors and two capacitor voltages fluctuation is shown by experiment.