Improved Frequency and Phase Control Strategy for VOC Parallel Inverter Based on Resonant Circuit Perspective

Aiming at the high content of third harmonics in traditional parallel VOC inverters and the problem of frequency and phase offset when the output is connected to an inductive load, a nonlinear frequency modulation method and pre-synchronization method based on the perspective of resonant circuits are proposed. This is a control method without interconnection lines. It can avoid power calculation. The two control objectives can be achieved only by adjusting the virtual capacitance. For the frequency modulation control method, after the phase adjustment is completed, the influence of phase adjustment on virtual capacitance will become transparent. Finally, the algorithm is verified by simulation, effectively reducing the third harmonic, suppressing system circulating current, and achieving power equalization.