Contents I. Introduction
The parallel operation of voltage source inverters has become a popular choice in high power applications due to its many advantages, such as larger system capacity, increased system robustness, easy and flexible implementation, and lower cost for repair and replacement of each failure [1] –[5]. In a parallel connection of voltage-source inverters, one of the major concerns is the circulating currents between inverters, since it reduces the power rating and efficiency of the system [6], [7]. The circulating current can be generated by the loose of the synchronization between inverters, mismatched output inductance, measuring errors, and discretization of the controllers [8], [9]. In order to suppress circulating currents, various control techniques have been introduced including voltage frequency droop control [10], circular chain-control [11], and harmonic-elimination pulse-width modulation (PWM) [12]. By introducing these techniques, most of the fundamental and low-order harmonic circulating currents can be eliminated.
