Parallel operating inverters with common direct current (DC) power supply can generate zero-sequence circulating current leading to unbalanced load current

output current distortion

system loss increase and so on. To suppress zero-sequence circulating current

an analysis is made of the mechanism and components of zero-sequence circulating current based on its equivalent model first. Then

a new strategy based on the active zero state pulse width modulation (AZSPWM) and proportional-resonant (PR) control is proposed

which uses two opposite active vectors instead of zero vectors to suppress the higher frequency circulating current and reduces the lower frequency circulating current by means of zero-sequence circulating current closed-loop control based on the PR controller. It is able to eliminate circulating current with high-efficiency usage of DC voltage and without increasing the hardware cost. Finally

the effectiveness of the strategy between two parallel inverters is verified on an experimental platform. This work is supported by National Natural Science Foundation of China (No. 61201010) and National High Technology Research and Development Program of China (863 Program) (No. 2013AA051002).