Research And Design Of Series Resonant Medium Frequency Induction Heating Power Supply

With the continuous development of science and technology and people’s awareness of environmental protection,energy conservation and emission reduction,traditional heating methods can no longer meet people’s needs.The new induction heating power supply has received great attention from the industry due to its high efficiency and clean advantages,and its application fields are becoming wider and wider.This paper studies and designs an induction heating power supply with DSP as the control chip and IGBT as the main power switching device.The power is 4k W and the frequency is 20 k Hz.The feasibility and correctness of the scheme are verified through modeling and simulation and the construction of experimental circuits.This article first describes the development status of induction heating power supply,analyzes the basic principles of induction heating,combines the research status,and compares several common induction heating power supply main circuit structures.In order to ensure the power factor of the system,the rectification circuit adopts uncontrolled rectification,and then according to For design requirements and applications,select a more practical series resonant inverter circuit.In the power regulation part of the power supply,this article focuses on the inverter side power regulation method,using phase-shift PWM power regulation.Since the power device uses IGBT,the main loss of the device is during the turn-off period,and the capacitive power regulation can achieve zero current turn-off.It is determined to adopt the capacitive phase-shifting PWM power adjustment method suitable for IGBT,and use Matlab to build a simulation model to verify the feasibility of capacitive phase-shifting power modulation.Aiming at the shortcomings of the traditional PI control algorithm,an improved incremental PI algorithm is adopted.This method does not require accumulation,and only the most recent sampled value is related to the control increment ?u(k),which greatly reduces the calculation time,To ensure the system regulation speed and output accuracy,and realize intelligent control;then through parameter calculation,the hardware circuit is designed;for the frequency tracking problem,the current zero-crossing synchronization technology is adopted in the article,and the frequency tracking circuit is composed of a bidirectional comparator and an optocoupler isolation circuit.Compared with the shortcomings of the phase-locked loop circuit,such as the narrow working range and the inability to automatically adjust the parameters of different frequency bands,this technology has the advantages of small error and rapid response.It can realize the automatic tracking of the natural frequency of the load,so as to ensure that the whole heating process The power supply is in the best working condition;use CCS software to compile the programs of each part of the system and carry out software debugging.Finally,an experimental platform is built,software and hardware are jointly debugged,and experimental waveforms are obtained to prove the feasibility and correctness of the scheme.After analyzing the experimental results,this scheme can well realize functions such as power control and frequency tracking,and the conversion efficiency also achieves the expected effect.The entire control system has the characteristics of simple structure,easy control,strong stability,etc.,which basically meets the design requirements,and the power supply performance has been improved.The scheme designed in this article also has a certain reference value for induction heating.