Study on restraint of circulating current in parallel inverters system with SPWM modulation by adjusting phases of triangular carrier waves

Aiming at the circulating current of parallel inverter with SPWM modulation for AC motor drive, a restraining method of circulating current is proposed based on the relationship between the circulating current and phase difference of carrier waves in this paper. The direction for phase difference of carrier waves has been detected according to the principle of minimal accommodation, and then the value of the phase difference has been computed from the relationship between the DC circulating current and phase difference of carrier waves. So the triangular carrier wave which is anterior has been accommodated laggardly according to the phase difference and the direction of triangular carrier waves, the circulating current has been restrained effectively. The results of simulation have verified the proposed method.