Analysis on circulating current of parallel inverter with SPWM modulation for AC motor drive

An analysis method of circulating current in parallel SPWM inverter system for AC motor drive is proposed based on double Fourier Transform theory in this paper. The models of driving current and circulating current are constructed by voltage equations of inverters and motor load. The characteristic of circulating current is analyzed by using the modulating equations under the condition that the triangular carrier waves have the different phases. And the harmonic analysis of circulating current has been done based on double Fourier Transform theory, the relationships between circulating current and the phase difference of triangular carrier waves have been obtained. Simulation results are presented to verify the proposed analytical method.