Verification of parallel connected multiple motor drive system with numbers of permanent magnet synchronous motors

This paper discusses a multi-parallel drive system for permanent magnet synchronous motors PMSMs). This system proposes to use two different functions of inverter, a main inverter with V/f control to control the speed of all parallel connected PMSMs. Then, each of PMSM is individually connected with an auxiliary inverter. The auxiliary windings which are used in the auxiliary inverter are placed in the slots together with the conventional windings. In addition, implementation of the damping control in the auxiliary inverter is discussed and the stability analysis is evaluated in order to suppress the speed and torque vibrations which are caused from the resonance between the inertia moment and the synchronous reactance. The simulation and experimental results demonstrate the effectiveness of the proposed system. Moreover, the relationship between the damping gain and the output power of the auxiliary inverter is clarified. From the results, it can be confirmed that if the application that is required a slow response is applied in the auxiliary inverter, then the power capacity of the auxiliary inverter can achieve the smallest which is equivalent to 10% of the main inverter power capacity.