The Application Of Frequency-Tracing Technology Based On PLL For HF-Inverter Power Supply

In order to solve the problem about the variety of resonance frequency,it's very necessary to design and utilize the phase-lock technique of serial resonant inverter with power MOSFET as switching divice.Firstly,PLL's mathematic model is set up and analyzed in Pspice.After that,the corresponding waveforms of simulation are given.The results show that the control methods and the inverter models are reasonable and correct.Secondly,an induction heating power is designed taking the load series-resonant High-Frequency-Inverter model as an example.In consideration of the resonant frequency being changed by load parameter variation,which led the power efficiency reduction and the stress increasing of switching components in a conventional inverter,a control system with the nophase difference of frequency track devised based on the HC4046 integrated phase locked loop is designed and proposed.It is applied to control the operating frequency of an High-Frequency-Inverter timely,so as to adapt varieties of the load resonant frequency to keep the inverter always working on Zero Votage-Zero Current Switching(ZVZCS)mode.Meanwhile,the losses of switching components are reduced obviously and the efficiency of the power is improved greatly on ZVZCS mode.Meanwhile, the paper analyzes and discusses the phase compensation and question of starting of the control system.And the corresponding experiment is done finally.It provides a useful and practical method to analyze as well as to design a PLL controller in inverters.