A Generic Multi-Frequency Repetitive Control Scheme for Power Converters

A Generic Multi-Frequency Repetitive Control (GMFRC) scheme, is proposed to perfectly compensate for all kinds of periodic signals including multi-frequency signals, where multiple selective harmonic repetitive controllers in parallel are added into a stable instantaneous feedback control loop to achieve overall satisfactory performance. The GMFRC scheme provides a general framework for housing various repetitive control and even resonant control schemes in power electronic conversion and other extensive engineering applications. A universal approach to the analysis and synthesis of the digital GMFRC scheme has been developed, which includes the stability criteria and control gain rules. More important, the digital GMFRC controller is transformed into a general fractional-order one for exact compensation of multi-frequency signals and other fractional-order periodic signals in practice. An application example of a 5kVA three-phase PWM inverter under a fractional-order GMFRC scheme is provided. Experimental results demonstrated that the proposed GMFRC scheme can force the inverter to produce required mono-frequency or multi-frequency voltages with high accuracy, fast response and good robustness.