The Hardware And Software System Design For LLC Resonant Microwave Oven Power Supply

With the accelerated pace of economic development and people’s lives,microwave oven gradually become an indispensable appliances. Traditionalmicrowave oven has a serious limitation in volume, efficiency and intelligence, so theimproved problem becomes more and more prominent for the new microwave oven.Early microwave oven power supply usually used a fixed-frequency transformerrectifier, which makes the power supply is not adjustable, high energy consumption,serious device depletion, volume and weight. As the non-adjustable output power,microwaves oven can only take intermittent power supply to the magnetron to changethe average output power of the microwave oven, such frequent open-close methodhas a serious impact on the life of the magnetron. This subject follow contemporarytrends, try to use the LLC resonant circuit to give a continuously adjustable powersupply voltage for microwave magnetron. And using the ZVS soft-switchingtechnology to reduce the switching losses of the switch tubes.（1）A comparison of several common resonant circuit, we can point out theadvantages of the LLC resonant transform circuit. And next a detailed analysis of thestate and waveform diagram of LLC resonant converter circuit works in differentswitching frequency range. Use FHA fundamental analysis to give a thorough anddetailed analysis of DC gain of the LLC resonant circuit, and impedancecharacteristics parameters.（2） Optimization calculation for the main parameters of LLC resonantconversion circuit, and then pushed the conditions of the ZVS soft switching guide;through the calculation of the parameters, select the appropriate inductor, capacitorswitching tube, diode, drive, micro-controller chips and other devices to complete thehardware part of the LLC resonant switching power supply; analysis of the differencebetween the actual transformer and ideal transformer, designed integrated Magneticstransformer structure to simplify the resonance circuit.（3）Use the core chip STM32F103VBT6to design the LLC resonant switchingpower supply control part of the software and hardware systems. Hardware partincludes auxiliary power supply, drive chip IR2110and its peripheral circuits, themicro-controller STM32F103VBT6peripheral circuit and current detection circuit;software part includes complementary PWM waveform output, current sensing ADCconversion and over current protection enabled software design under IAR EmbeddedWorkbench for ARM work environment.(4)Make the LLC resonant switching power supply prototype structures in thelaboratory, and get the acquisition of the actual circuit waveform, and compared withthe theoretical analysis.