Control method for frequency-conversion power supply circuit starting process of magnetron

Abstract

The invention provides a control method for the frequency-conversion power supply circuit starting process of a magnetron. The method comprises the steps that s1) after electrification, a switch control signal is sent to a drive circuit in the initial minimal pulse width value and the initial switch frequency value, and at the same time, a sampling signal is output to a control module; s2) the pulse width of the switch control signal is increased gradually till the filament power of the magnetron reaches a preset basic power value for filament heating; s3) whether the anode current of the magnetron is increased and the increase amount are determined, the pulse width of the switch control signal is increased and the frequency of the switch control signal is reduced if the anode current is increased, and the pulse width and the frequency of the switch control signal are maintained if the anode current is not increased; and s4) whether the anode power of the magnetron reaches an oscillation-starting power threshold of the magnetron is determined, if the threshold is not reached, the s3) is returned to, and if the threshold is reached, the starting process is completed. The control method can be used to control the filament current during starting within the specification of the magnetron, and ensure that starting is completed in the standard prescribed time of the product.

Description

technical field [0001] The invention relates to a control method of an induction heating power supply device during the start-up process of a magnetron. Background technique [0002] Induction heating power supply device, such as microwave oven power supply, its load is an electric vacuum device - magnetron, like other electric vacuum devices, it needs a start-up process after it is powered on before it can start to work normally. This is because the condition for the normal operation of the magnetron is that the filament can emit electron flow according to the control of the anode voltage. Only when this state is reached, the magnetron can emit microwave power normally. The filament must go through a certain heating time and reach a high enough temperature before it can emit electron flow under controlled conditions. This is the so-called start-up process. During this process, since the magnetron cannot generate microwave power yet, the load of the power supply unit is bas...

AI Technical Summary

Problems solved by technology

[0004] In order to solve the technical problem that the secondary rectifier diode is easily subjected to excessive reverse high voltage and start-up consistency during the start-up process of the existing magnetron, the present invention proposes a control method for the start-up process of the magnetron variable frequency power supply circuit. The tube frequency conversion power supply circuit includes a rectification filter circuit, a power conversion circuit, a sampling module, a control module, a frequency / pulse width modulation generation unit and a drive circuit; the rectification filter circuit is used to rectify and filter the current of the AC power supply, and its output terminal is connected The power conversion circuit; the power conversion circuit includes an electrically connected power switch tube and a power transmission network topology; the power transmission network topology is used to provide voltage to the anode and cathode of the magnetron; the control of the power switch tube connected to the output terminal of the driving circuit, the input terminal of the driving circuit is connected to the output terminal of the frequency / pulse width modulation generating unit, and the sampling module is used to monitor parameter sampling and send its output signal to the a control module, the frequency / pulse width modulation generating unit is controlled by the control module;

Images