Development Of Variable Frequency Microwave Oven Power Supply In LLC Resonant Converter With Multiple Output

In the modern family, microwave oven has been used more and more. Its efficiency, intelligent and environmental protection and energy saving performance got more and more attention. The traditional microwave oven magnetron power supply consists of an industrial frequency transformer and a half-wave voltage doubling rectifying. In the design of traditional microwave oven magnetron power supply, it would like to use two independent magnetron power supply that provide power for magnetron cathode and anode. Because of the high voltage to ground of the magnetron cathode and anode, it needs to provide two systems to isolation voltage, so it make circuit become complex and expensive. In addition, as the way of traditional microwave power supply, it results some shortcomings, such as low efficiency, large volume, heavy weight and its power is not adjustable. If the supply could realize multiple output, PID control and soft switching, It will not only effectively overcome the above defects, greatly reduce the complexity and the cost of the magnetron power supply, but also it can improve the efficiency and service life of microwave power Therefore, this paper studies the multiple output LLC resonant converter and closed loop feedback control system and put forward a microwave power supply design scheme which can realize magnetron cathode anode voltage output and magnetron continuous adjustable power output.Based on the understanding of the working characteristics on the basis of the magnetron, the working principle of the LLC resonant converter is analyzed in detail. Putting forward a design scheme of variable frequency microwave oven magnetron power supply with closed-loop feddback. The main circuit uses two-stage structure and closed-loop feedback. The front-end circuit uses the active power factor correction circuit with PID control, then using LLC resonant soft switching converter and doubler rectifier circuit. This soft switching power supply can take the place of the traditional linear power supply. So that the microwave oven can with low complexity, lowcost and high efficiency. And also can realize continuous adjustable output power, which greatly improve the intelligent level of microwave oven.Firstly, Confirm the main circuit of multiple output microwave oven magnetron power supply and analyze the features of the LLC resonant converter in detail. Equivalent constraint model and elicit the curve of Dc voltage. Analysis of the influence law of different circuit parameters on voltage gain and make a feasibility analysis and calculation of the LLC resonant converter to the anode and cathode of the magnetron.Secondly, combined with the specific requirements of this topic, calculating the main circuit of the variable frequency microwave oven power supply in LLC resonant converter. The design of main circuit parameters is completed. And also the selection of components has been done.Thirdly, to realize online real-time adjust the microwave power supply power output, combined with the equivalent circuit model of LLC resonant converter, based on the DC voltage gain of the LLC resonant converter, design with PWM pulse generator with PID control feed back system composed of PID controller, then select the parameters.At last, using segmented simulation method, the results of active power factor correction circuit are analyzed by using of the SABER simulation software. And the simulation results are analyzed. At the same time, the use of MATLAB software on the system of the multiple output system are simulated, then the PID control closed loop feedback system are simulated, which makes the switching frequency of the converter can realize online adjustment, finally using the control variable method to compare under the presence of the PID closed-loop control of LLC resonant converter performance difference and draw a conclusion.