Nonlinear analysis of high-frequency self-oscillating resonant inverters

To efficiently predict the output frequency of self-oscillating high-frequency inverter, this paper summarizes a nonlinear control method using describing function and extended Nyquist Criterion. By analyzing the transfer functions of linear parts and the describing functions of nonlinear parts of four different high-frequency self-oscillating inverters, the starting conditions and oscillating frequencies of the inverters are investigated. Experimental results show that the relative difference between the estimated frequency and the actual frequency is around 5%, which validates the method.