Research On Ultrasonic Induction Heating Power Supply

With the improvement of energy conservation and emission reduction and the goal of green production,the status of induction heating in industrial production is getting higher and higher.Ultrasonic induction heating uses the law of electromagnetic induction and electromagnetic eddy current technology to apply ultrasonic alternating current to the load,which makes the heated workpiece produce eddy current and generate a large amount of heat energy.It has the advantages of high efficiency,high speed and low pollution.According to the needs of chemical engineering experiment,this paper studies and designs a fully digital prototype of ultrasonic induction heating for chemical engineering heating experiment.In order to achieve the best heating effect of induction heating device(induction coil and crucible,hereinafter referred to as system load),this paper uses the multi physical field simulation interface of "electromagnetic temperature" in COMSOL software to analyze the interaction between electromagnetic field and temperature field on the load side of the system,and models the parameters on the load side of the system according to the heating rate.Based on the electromagnetic thermal simulation results of the structure of the system load and the number of coil turns,an induction heating device is designed to achieve the best heating effect.In order to improve the efficiency,this paper compares the circuit topology,summarizes the mathematical model,and puts forward the control strategy and algorithm.In this paper,the switching mode with frequency as the boundary(FL)is used to determine the boundary frequency of switching between phase shifted PWM and PFM.The hybrid power regulation of phase shifted PWM and PFM combines the soft switching(ZVZCS)characteristics of the former with the fast power regulation characteristics of the latter.In the process of initial startup,this design uses the automatic identification algorithm of resonant frequency.The algorithm uses two known working frequencies to indirectly calculate the natural resonant frequency of the power supply,which can lock and capture the resonant frequency within20 milliseconds.The power supply has a variety of control modes to meet the needs of engineering experiments: constant current mode,constant power mode and constant temperature mode.The three modes have their own feedback links,and all adopt integral separation type limiting PI control algorithm.In this paper,according to the system design index and simulation results,the system components are selected to design and build the main circuit of series resonance;Then the control circuit based on stm32f334 is designed and built;Commissioning and assembly of design program;The final design experiment proves that the experimental prototype verifies the feasibility and advantages of the above control strategy and algorithm,and also verifies the correctness and reliability of the main circuit and control circuit.