Research And Design Of Low Har-Monic Induction Heating Power Supply Based On PWM Convert

Aiming at the harmonic problem of induction heating power supply,this paper focuses on the rectification part that produces harmonic pollution to the power grid,and designs a light induction heating power supply ap-plied to the industrial mechanical arm to reduce the harmonic content.Firstly,because the designed induction heating power supply needs to be installed on the industrial mechanical arm,lightweight design is made for the filter part and radiator of the induction heating power supply from the aspects of material and structure.Combined with the characteristics that the designed induction heating power supply needs to reduce volume and improve efficiency,the PWM rectifier mode that can improve power factor and reduce harmonic generation is selected.According to the technical in-dex of the designed induction heating power supply,the equivalent model of output voltage,current and load of the rectifier is calculated.However,PWM rectifier still contains a large number of high harmonics near the switching frequency,so LC filtering method with blocking and dredging is selected to solve the harmonic problem thoroughly.Then,after deeply studying the working principle and mathematical model of PWM rectifier,a double-closed loop feed-forward decoupling control strategy composed of outer voltage loop and inner current loop was determined,and a seven-stage method of allocating conduction time in the process of SVPWM signal synthesis was selected to reduce the generation of harmonics.In the design of passive filtering,the filtering inductance used in the traditional 1-type PWM rectifier is relatively large and its dynamic performance is poor,while the LCL type PWM rectifier makes the model-ing more complicated and the control more difficult because of the addition of capacitor elements.In this paper,a kind of LC filter PWM rectifier with additional resonant control is designed on the relatively simple model of 1-type filter by adopting the idea of split design,and the upper and lower limits of the corresponding dc side capacitance,ac side filter capacitance and inductance are calculated according to the technical indexes of the de-veloped induction heating power supply.And in the MATLAB software to carry on the before the 15 kw induction heating power supply level simu-lation,under the condition of without any increase in volume of inductance,the design of LC type PWM rectifier PWM rectifier harmonic is smaller than a single inductor,attached to join the resonant controller near the res-onance frequency of the filter effectively suppress the harmonic amplifica-tion,verifies the correctness of the harmonic suppression scheme.Finally,the hardware and software of PWM rectifier are designed.Ac-cording to the technical specifications of a 15kW,20khz induction heating power supply,the power main circuit,driving circuit,sampling circuit and main control circuit of PWM rectifier are designed.And completed the DSP software design.