Phase protection circuit, phase protection method and electromagnetic heating device

Abstract

The invention provides a phase protection circuit applied to a half-bridge resonance circuit. The phase protection circuit comprises a comparator circuit and a controller. The comparator circuit is used for obtaining resonance current in the half-bridge resonance circuit, a current waveform of the resonance current is compared with a control waveform corresponding to drive control signals of an upper bridge or a lower bridge in the half-bridge resonance circuit, and therefore the phase difference of the current waveform and the control waveform is obtained; the controller is connected to the comparator circuit, according to the phase difference, whether the half-bridge resonance circuit is in a normal work state or not is judged, and when a judgment result is negative, the operation that the control signals are sent to the half-bridge resonance circuit is stopped. Correspondingly, the invention further provides a phase protection method and an electromagnetic heating device. According to the technical scheme, the phenomenon that due to a phase error of the drive control signals, an IGBT is turned on by mistake after a zero crossing point of current occurs is avoided, the IGBT is prevented from being overheated and burnt, and the IGBT is effectively protected.

Description

technical field [0001] The invention relates to the technical field of electromagnetic heating, in particular to a phase protection circuit. Phase protection method and electromagnetic heating device. Background technique [0002] At present, the heating of the induction cooker mainly uses single-tube, half-bridge, and full-bridge as the topological structure of the circuit, and the half-bridge heating is between the single-tube and the full-bridge, and it is also the most commonly used circuit, but it is necessary to adjust in the work of the induction cooker. The power will adjust the resonant frequency of the circuit accordingly. When the adjusted frequency of the circuit is lower than the natural resonant frequency, or when the parameters of the circuit change and the natural frequency changes, the IGBT will be turned on after the current zero crosses. If Turning on the IGBT after zero crossing will cause the IGBT to overheat and burn out. [0003] Therefore, how to av...

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Problems solved by technology

[0002] At present, the heating of the induction cooker mainly uses single-tube, half-bridge, and full-bridge as the topological structure of the circuit, and the half-bridge heating is between the single-tube and the full-bridge, and it is also the most commonly used circuit, but it is necessary to adjust in the work of the induction cooker. The power will adjust the resonant frequency of the circuit accordingly. When the adjusted frequency of the circuit is lower than the natural resonant frequency, or when the parameters of the circuit change and the natural frequency changes, the IGBT will be turned on after the current zero crosses. If Turning on the IGBT after zero crossing will cause the IGBT to overheat and burn out

[0003] Therefore, how to avoid IGBT overheating and burning has become a technical problem to be solved urgently.

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