Distributed Carrier Phase Shifting Control Method for Modular Interleaved Parallel Inverters

Modular parallel inverters with interleaving are a cost-effective approach to improve system performances. In this article, a simple distributed carrier phase shifting control method with the local controller is proposed. First, the resultant current harmonics for modular parallel inverters are analyzed considering the crystal oscillator frequency deviation. Then, a NOR gate circuit-based synchronous signal generator is constructed, which generates a common low-frequency digital synchronous signal to trigger the carrier phase shifting control. With the carrier phase detection and error compensation considering the time delay, a proportional carrier phase shifting controller with detailed parameter design considerations is proposed to dynamically adjust the carrier relative phase angles of parallel modules until they are properly interleaved. The proposed method has overcome the issue of a single point of failure (i.e., high reliability) and is immune to sampling error and line impedance voltage drop (i.e., high accuracy). Finally, different carrier phase shifting methods are compared and the experimental results have verified the effectiveness of the proposed method.