A Microwave Drying System with Continuous Linear Adjustable Output Power

Abstract

The invention relates to a microwave power control system, by means of a feedback control circuit, voltage of a magnetron resonant cavity polar plate is adjusted, so that adjustable continuous linearity of microwave output power is achieved. The system is mainly composed of an independent magnetron filament power supply, voltage-power non-linear correction and a feedback controlled magnetron resonant cavity power supply circuit. By means of needed power density, control voltage Vc is output by the voltage-power non-linear curve correction, and the Vc serves as a feedback controlled reference signal. The reference signal is compared with a feedback signal, a servo motor is controlled to act, an electric brush is driven to slide, output voltage of an autotransformer is changed, then a resonant cavity of a magnetron is supplied with power by a boosting transformer, so that microwaves with different power output by the magnetron is controlled. Continuous and changeable power input is provided for a to-be-dried object in microwave drying, and the applicability of drying equipment is greatly improved.

Description

technical field [0001] The invention relates to a microwave power control system, in particular to a microwave drying system with continuously linearly adjustable output power. Background technique [0002] In daily life, people often use microwave ovens to heat, cook and defrost food. At the same time, microwaves also have many functions such as disinfection and sterilization of tableware, moth-proof and mildew-proof items, food drying and dehydration, etc., which are very versatile. The microwave output adjustment system of the traditional household microwave oven is mainly to change the average power within a period of time by changing the ratio of the magnetron on and off power supply time when the microwave output power of the magnetron is constant. For example, to obtain microwave output power that is half of the rated power, the on-off time ratio of the power supply can be controlled to be 1:1. The average power output of other values ​​can be obtained by appropriate...

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Problems solved by technology

At present, there are generally three problems in the power adjustable microwave system: the filament and the plate of the resonant cavity share a transformer for power supply, while reducing the output voltage of the anode transformer, the voltage of the filament will also decrease accordingly, which will easily cause "poisoning" caused by the temperature of the filament being too low. "Phenomenon; the method of changing the input voltage through a thyristor, etc., on the one hand, due to the leakage inductance of the transformer, the current phase lag is prone to out of control, on the other hand, due to the incomplete waveform, a large number of high-frequency components will be introduced to cause the microwave oven to vibrate during operation; there is no feedback The controlled power supply system will cause the output power of the microwave oven to be unstable when the power grid fluctuates

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