Parallel PWM converters with carrier phase shifting can increase system capacity

reduce current harmonics into the grid

whereas lead to the problem of circulating current. Consequently

we established and analyzed the equivalent and average mathematic models of the zero-sequence circulating current（ZSCC）. Based on space vector pulse width modulation（SVPWM） of zero sequence injecting to sinusoidal pulse width modulation（SPWM）

the frequency characteristics and mathematic expression of ZSCC were researched. Aiming to reduce the dc and 3

9 and 15 harmonic components of ZSCC

we proposed a suppression method for the ZSCC based on QPR and PI

and simulated ZSCC for a converter which consists of 4 parallel modules. A microgrid platform was built to perform experiments of grid-connected mode and island mode. Results indicate that the control strategy is effective in reducing harmonic current and ZSCC.