Research On High-power And High Frequency Induction Heating Power Supply Of 400KHz Based On DSP

This paper studied the induction heating power, briefly introduced the basic principle,class and the development trend of induction heating power technology. It introduced the two main topologies that are often used in induction heating power supply, and comparative analyse was made between the current source inverter and the voltage source inverter, and one was selected according to the design demand, and analyzed power regulating methods of induction heating power supply too. It can be concluded that power regulation in the commutate side in favor of enhancing the frequency and power level of high-frequency induction heating power supply. We chose uncontrolled rectifying circuit and Buck choppering power regulation method as the subject investigated. The paper designed a PI power adjustor including double zero-point and top-point. It designed multiplex chopping circuit because of too much harmonic of a single buck chopping circuit. Meanwhile, a closed-loop system of current and power was designed, and the power controlling problem of the induction heating power supply was transformed to the current controlling problem. In addition, the paper analyzed the working principle of the induction heating power supply's inverter, aimed at the working frequency of 400kHz, a high speed driving circuit was designed. The principle of phase-locked loop was explained, and a frequency-follewed system of inverter was designed by the integration PLL component CD4046, made the inverter working on the state of power factor nearly to 1 and the power supply running in high efficiency. Considering the power limit of a single MOSFET inverter, the paper designed a new form of parallel-inverters, and adoptted the form of high-frequency transformer power synthesize in the load side, in order to increase the output power.Chapter 5 of this paper introduced an experiment model machine of a 20KW induction heating power supply with double chopping circuit and two paralleled inverters. Thereinto the chopping frequency is 50kHz, working frequency of the inverter is 400kHz, the type of the control chip is TMS320F2812DSP by the TI. The experiment result showed that the manner of multiplex chopping and parallel inverters can increase the working frequency and output power obviously, also heighten the whole system's efficiency. The paper showed the structure design of the whole machine, DC chopping part block diagram, inverter control block diagram, and the design of driving circuit and protecting circuit. At the same time, the paper showed the simulation and experiment waves of some key circuits.Finally, a simple summing-up was given about the job done on the paper.