Research On A Novel Induction Heating Power Controlled By The LAPS-PWM Strategy

The induction heating power is studied and discussed in this paper. The principium and characters of the induction heating are introduced in brief. The status and the evolutions of the induction heating power technology are discussed. The main circuit of the induction heating power is chose by considering the complexity, the performances and the cost of power. All kinds of power control methods of the induction heating power are analyzed and compared in detail by simulation. A novel power control strategy, Load Adaptive Phase Shifted PWM(LAPS-PWM), is introduced in this paper. The work principle of power is introduced, and the theoretical analysis of power regulating principle is studied. The simulation results confirm that the LAPS-PWM control strategy can realize a wider output power range regulation by means of varying the phase-shifted angleθcontinuously, and at the same time, the switching devices of the induction heating power mentioned above are working in soft-switching transitions.The dynamic model and the small signal model of the LAPS-PWM controlled induction heating power are obtained by using the Extended-Describing-Function (EDF) method, and then its steady-state operating point is found. Furthermore, the small signal model of the power and its stability are analyzed and simulated. The EDF analysis results have shown that the model can be used to describe the dynamic characteristics of the LAPS-PWM controlled induction heating power actually, both under time domain and frequency domain condition. The model provides a theatrical aid effectively for analyzing and designing the control system of the induction heating power more veritably.In order to verify the validity and the feasibility of the LAPS-PWM control method, an induction heating power supply controlled by LAPS-PWM is designed and turned out, the power and frequency of which are 10kw and 10kHz separately. The special DSP chip of TMS320LF2407A that produced by TI Company is used as main controller of the power. The software and hardware of the power are designed. The experimental results show that the output current ripple of the LAPS-PWM controlled induction heating power is less than 5%. The output power can be regulated continuously, and the power conversion efficiency is higher due to lower switching losses.