Carrier Synchronization Method using High-Speed Sampling for Parallel Inverters without Communication

This paper proposes a novel carrier- synchronized control method for the parallel operation of two inverters using high-speed sampling. The proposed method focuses on the active power component at the switching frequency. When carrier synchronization is achieved, the active power at the switching frequency becomes zero for inverters connected in parallel. The proposed method calculates the active power at the switching frequency using high-speed sampling, switching states, and the fast Fourier transform (FFT). The proposed method requires only DC voltage and inductor current measurement without additional sensors. Furthermore, the proposed method is implemented in a single-phase inverter and does not need communication between units. Experimental results demonstrate that the circulating current is successfully suppressed to less than 66% of the rated current, thereby, validating the efficacy of the proposed control method.