Independent rated speed control of two induction motors fed by a four-leg inverter

This paper presents the experimental results of the independent rated speed control of two induction motors (IMs) fed by a four-leg inverter (4LI) with field-weakening control method. The inverter consists of four legs and two capacitors connected in a series. The 4LI have several disadvantages. First, it is not possible to modulate W phase voltage of the IMs. Second, the neutral point potential of two capacitors fluctuates. Third, motors speed does not come up to the rated speed. This paper shows an expanded two-arm modulation, compensation method and field-weakening control method to solve them. Next, the independent rated speed control of two IMs fed by the 4LI with the field-weakening control system is demonstrated by the experimental results. Moreover, it shows the effectiveness of those methods.