Independent speed and position control of two permanent magnet synchronous motors fed by a four-leg inverter

This paper presents the experimental results of the independent speed and position control of two permanent magnet synchronous motors (PMSMs) fed by a four-leg inverter (4LI) with vector control method. The inverter consists of four legs and two capacitors connected in a series. 4LI have several disadvantages. First, it is not possible to modulate w phase of the PMSMs. Second, the neutral point potential of two capacitors fluctuates. This paper shows an expanded two-arm modulation and compensation method to solve them. Next, the independent speed and position controls of two PMSMs fed by the 4LI with the vector control system is demonstrated by the experimental results. Moreover, it shows the effectiveness of those methods.