Microwave Circuits and Microwave Ovens

Abstract

The invention provides a microwave oven circuit and a microwave oven. The microwave oven circuit comprises an electric control board and a high-frequency heating circuit. The electric control board comprises a relay drive circuit used for transmitting electricity signals to the high-frequency heating circuit, a power drive circuit used for transmitting power signals to the high-frequency heating circuit, a first filter circuit connected to the signal feedback end of the high-frequency heating circuit and used for filtering magnetron current signals fed back by the high-frequency heating circuit, an analog-digital conversion circuit connected to the first filter circuit and used for conducting analog-digital conversion processing on signals output by the first filter circuit and a controller connected to the analog-digital conversion circuit, the relay drive circuit and the power drive circuit and used for controlling the electricity signals transmitted by the relay drive circuit and controlling the power signals transmitted by the power drive circuit according to the signals output by the analog-digital conversion circuit.

Description

technical field [0001] The invention relates to the technical field of microwave ovens, in particular to a microwave oven circuit and a microwave oven. Background technique [0002] Compared with the transformer power supply, the inverter in the microwave oven circuit has the advantages of lightness, high power factor, continuously adjustable power, etc., and has been widely favored by users. With the extensive use of inverters, the repair rate in the market has generally increased. Judging from the repair data, IGBT (Insulated Gate Bipolar Transistor, Insulated Gate Bipolar Transistor) and rectifier bridge stacks are mostly damaged. Now the control approach has been severely challenged. [0003] Such as figure 1 As shown, the existing frequency conversion microwave oven control system includes an electric control board and a high frequency heating device. Among them, the electric control board includes MCU, relay drive module and PWM (pulse width modulation) drive module...

AI Technical Summary

Problems solved by technology

Assuming that the mains power is 220V AC, if the mains signal is at a peak value of 310V, and the voltage across the capacitor C2' is 0 when the microwave relay is turned on, then the voltage across the capacitor C2' cannot change suddenly at the moment the microwave relay is turned on, and the peak value of the mains power 310V is directly applied to the inductor L1'. Due to the characteristics of the inductor (that is, the current cannot change suddenly), a large reverse voltage will be generated to prevent the current from increasing. Therefore, at the front end, that is, the port of the rectifier bridge stack 1', a large Large voltage, up to 1000V, easily damages the rectifier bridge stack 1'

This theoretical analysis is also consistent with the feedback data from the market, that is, the maintenance rate of bridge rectifier 1' remains high

[0008] At the same time, another high maintenance rate is IGBT 5', because the G pole voltage of the IGBT cannot exceed 25V, but under the existing control mode, when the microwave relay is turned on, the G pole of the IGBT will occasionally have a voltage above 33V

[0009] Therefore, how to reduce the voltage at both ends of the rectifier bridge stack when the inverter is turned on, to avoid damage to the rectifier bridge stack due to excessive voltage at both ends of the rectifier bridge stack, and to avoid damage to the G pole of the IGBT due to excessive voltage has become an urgent problem to be solved. technical problem

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