Circulation current reduction for a motor simulator system using a power converter with a common mode transformer

This paper presents a new suppression method of circulation current for a motor simulator system. A conventional system requires a large transformer at grid frequency to avoid a circulation current between the motor simulator and a test inverter, besides a regenerative converter is required too. In the proposed topology, the high frequency components of the circulation current are suppressed by a common mode transformer, and the low frequency components are suppressed by zero phase current control. Furthermore, a small size medium frequency common mode transformer is used instead of the regenerative converter and the grid frequency transformer. In addition, the proposed system can simulate the transient condition of the motor. The proposed method is validated based on the simulation and experimental results. The motor simulator primary current waveform agrees well with that of the actual motor, including the distortion due to a voltage error by a dead time period. Also the low frequency component of the circulation current was suppressed to less than 1% of the fundamental component by using the proposed method.