Adaptive Quasi-Resonant Control for the Medium-Frequency Power Supply With Wide Variation of Output Frequency

To improve the output voltage quality of the medium-frequency inverter power supply with wide variation of the output frequency, a harmonic quasi-resonant (QR) control strategy with on-line frequency adaptability is proposed. Aiming at eliminating the steady-state error at the fundamental frequency, the integral and the QR controller are combined to track the voltage reference. Since the harmonic frequencies of the inverter are commonly located outside the control bandwidth, a phase-lead angle is added to QR to provide enough phase margin without sacrificing the gain at these frequencies. The design guideline of the on-line adjustment of the compensated angle is finally elaborated to improve the adaptability to the frequency reference. An experimental platform of 600VA/300-800Hz inverter power supply is built in the laboratory. The theoretical analyses and experimental results validate that satisfied steady-state and dynamic performance are ensured by the proposed control strategy, and the ability to suppress harmonics of the arbitrary frequency reference is also provided.