基于锁相环1MHz感应加热电源频率跟踪的研究

Research on the Frequency-Tracing for 1MHz Series Reasonate Induction Heating Power Supply based on PLL

针对高频感应加热电源负载参数变化引起固有谐振频率变化,导致逆变器效率降低现象提出并实现了一种以集成高速锁相环74HC4046为核心的应用于采用功率MOSFET为主开关器件的1MHz串联谐振感应加热电源的无相差频率跟踪控制系统,对电源的输出频率进行实时控制,实现逆变器工作频率对负载谐振频率的同步跟踪,并就控制系统的相位补偿和启动等问题进行了分析讨论;其次推出了适用于高频逆变电源的锁相环数学模型并用Pspice进行了仿真分析;最后进行了实验验证。

In consideration of the resonant frequency being changed by load parameter variation, which led the power efficiency reduction in a induction heating power, a control system with the nophase difference of frequency track devised based on the HC4046 integrated phase locked loop is designed and proposed firstly. It is applied to control the operating frequency of a IMHz serial resonant inverter with power MOSFET as switching divice timely, so as to adapt varieties of the load resonant frequency to keep the inverter always working on Zero Votage-Zero Current Switching mode. Meanwhile, the paper analyzes and discusses the phase compensation and question of starting of the control system. Secondly, PLL＇s mathematic model is set up and analyzed in Pspice. And the corresponding experiment is done finally. After that, the waveforms of simulation and experiments are given. The results show that the control methods and the inverter models are rea- sonable and correct.