Research On The Main Circuit Control System Of Current-source High-frequency Induction Heating Power Supply Used On Steel Tube

Induction heating power supply has been widely used in machinery manufacturing,metallurgy,aerospace,automobile manufacturing and other fields for its high heating efficiency,speed,controllable and easy to be automated,etc.the performance of its control system directly affects the quality of products.So it is very important to ensure induction heating power supply work stably and efficiently.Phase-locked loop which ensures the tank working on resonant frequency is an important part.This article analyzes the accuracy of phase-locked loop,especially focusing on how the delay time,produced by the Phase-Locked Loop(PLL)circuit,affects the accuracy of phase-locked loop,and presents a mathematical model of the delay time of the PLL circuit which provides a theoretical method for PLL phase compensation.Phase compensation is achieved in software by improving the digital PLL control algorithm;And the performance of PLL is tested by building a small power prototype.The results show that this PLL control algorithm can guarantee the normal operation of induction heating power.And the phase compensation measures work ideally.In view of the problems of traditional PI controller parameter design,the article uses a single neuron PI controller with adaptive parameters,and analyzes the dynamic adjustment of the parameters of K,and a relatively simple dynamic adjustment method is adopted.A small power prototype is built to test the performance of the traditional PI controller and single neuron PI controller respectively.The results show that the single neuron PI controller,whose parameter K can be dynamically adjusted,can meet the control requirement.And the parameters design is more simple than the traditional PI controller.