Research Of Ultra High Frequency Induction Heating Power Supply Based On CPLD

Ultra high frequency induction heating power supply is a device that uses the AC/DC/AC technology and converts electrical energy into heat energy, it has great value in the field of heating application. This article is based on the development of power electronic semiconductor technology, using new type of high speed switch tube MOSFET, design a frequency of 400 kHz-600 kHz ultra-high frequency induction heating power supply.Based on the theory of high frequency induction heating technology, design a practical closed-loop control of the power supply. To analyze system inverter topology structure, firstly, it analyzes the difference between the half bridge inverter and full bridge inverter, then it analyzes the pros and cons of series resonant with parallel harmonic union, based on high-frequency low-power power supply in this article, through theoretical analysis, selects a half-bridge series resonant inverter structure. In the field of ultra high frequency power supply, soft switch technology is widely used, namely to achieve frequency induction heating power supply load current tracking. It analyzes the common several kinds of frequency tracking technology in theory, the frequency tracking of chip control, single-chip microcomputer control, DSP control, FPGA/CPLD control, comparing and considering its economic value, it uses the CPLD to control the design of digital phase locked loop frequency tracking technology. All digital phase-locked loop is similar to analog phase lock loop, using digital phase detector, digital loop filter, digital controlled oscillator to complete lock frequency and lock phase. In this paper, it uses the technique of inductive heating frequency tracking that is with automatic model controller, based on the input signal phase difference of the two road, automatically changes the size of the modulus value, solves the contradiction between the phase lock speed and the synchronization error. The half bridge inverter control signals must have a certain dead zone, to guarantee the switch tube shut off first, open after, the synchronization signals of phase-locked loop output forms a closed loop system after through the dead zone formation circuit, her excitation circuit, conversion circuit, etc, configures the CPLD and designs the peripheral circuit, get a full control of DC/AC controller.On the basis of theoretical research, writing module program, drawing the schematic and PCB board, setting up system experimental platform, verifying the system heating effect through the experiment, the device is that concentrated energy transmission, no pollution, quick heating, good heating effect, it can be used in different fields through change the load model.Based on this article adopted design thinking, designing the 500 kHz small power induction heating power supply is feasible and it can realize the frequency of the current tracking, the anti-interference ability of the device is strong, and it has a very high economic value.