Study On The PFM-APWM Hybrid Power Regulation Strategy Based On Half-Bridge Induction Cooker Inverter

In recent years,with the development of science and technology,induction heating technology has been widely applied to many aspects of the households,industries,medical equipment and so forth,due to the remarkable characteristics of high heating efficiency,environmental protection,and cleanliness,and it possesses broad developing prospects and great research value.Induction cooker is a typical application of the induction heating technology,which has gradually replaced traditional heating method in household and commercial fieldsTo address the adverse effects of the pulse frequency modulation(PFM)strategy,usually applied to half-bridge induction cooker inverters,such as the narrow range of power regulation and low output efficiency in low-power stage,this paper proposes a pulse frequency modulation-asymmetric pulse width modulation(PFM-APWM)hybrid Power adjustment strategy.Firstly,the inverter topologies and frequency modulation strategy of induction cooker inverters are explored and analyzed.By summarizing and comparing three common inverter topologies for induction cooker,the half-bridge inverter topology is selected as the research direction in this paper.Secondly,with the theoretical analysis the output power characteristics and IGBT loss characteristics of PFM strategy,it is concluded that PFM strategy possesses the adverse effects of narrow power regulation range and high power losses of IGBTs in low-power stage.To eliminate this disadvantage,a PFM-APWM hybrid strategy is proposed.The strategy adopts PFM strategy in high-power stage and fixed-frequency APWM strategy in low-stage,which expands the power regulation range,reduces the highest operating frequency,and reduces the device loss.To provide an algorithm basis for power closed-loop control,two switching modes for the PFM-APWM strategy,power switching(PL)and frequency switching(FL),are proposed.The main circuit of the half-bridge induction cooker is built in PSIM,and the simulation results demonstrate the rationality of the PFM-APWM hybrid strategy.Finally,the experiment platform of half-bridge induction cooker is built,including rectifier filter circuit,inverter circuit,drive circuit,sampling circuit and protection circuit.The power closed-loop control of the PFM-APWM hybrid strategy is realized,and the experimental results demonstrate the correctness and feasibility of the PFM-APWM hybrid strategy.