Analysis of Control Schemes of Parallel Inverters for Driving Motor

In order to analysis the traction system of two parallel inverters, the math model and the equivalent circuits are proposed, the cause of circulating current between two inverters is described, and the change of circulating current paths and the influence of circulating current amount are analyzed on the condition of different DC power source. On this basis, two controlling schemes for parallel inverters system are proposed, the two schemes are forced current sharing scheme and individual current control scheme. After comparatively analyzing characters of two control schemes, individual current control scheme is suitable for parallel inverter. Then phase shift technology is combined with individual control schemes in order to reduce harmonic. The simulation results show that this method can restrain the circulating current effectively, and reduce the harmonic of stator current for motor.