Buck-boost circuit for electromagnetic heating device and its control method

Abstract

The invention discloses a buck-boost circuit for an electromagnetic heating device and a control method thereof. The buck-boost circuit comprises an H-bridge circuit, a first capacitor, a resonance circuit and a controller, wherein the H-bridge circuit comprises a first IGBT, a first switch tube, a second IGBT, a second switch tube and a first inductor, the input end of the H-bridge circuit is connected with the output end of a rectifier bridge in the electromagnetic heating device, the first capacitor is connected to the output end of the H-bridge circuit in parallel, the resonance circuit is connected with the first capacitor, the controller is connected with the G pole of the first IGBT and the G pole of the second IGBT, and the voltage across the two ends of the first capacitor is adjusted according to the working state of the electromagnetic heating device by controlling the duty ratio of the first IGBT and the duty ratio of the second IGBT. According to the buck-boost circuit, the voltage of the capacitor is adjusted by controlling the duty ratio of each IGBT, so that the voltage of the resonance circuit is increased or reduced, and then the turn-on loss of a switching device is reduced when the electromagnetic heating device is in the high-voltage and low-power state and power is increased quickly when the electromagnetic heating device is in the low-voltage and high-power state.

Description

Technical field [0001] The invention relates to the field of household appliances, in particular to a buck-boost circuit used in an electromagnetic heating device and a control method thereof. Background technique [0002] In the prior art, a single-tube parallel resonant circuit is used in an electromagnetic heating device such as an induction cooker. However, when the electromagnetic heating device is at high voltage and low power, the IGBT (Insulated Gate Bipolar Transistor, insulated gate bipolar transistor) has high turn-on voltage and large turn-on loss. IGBT temperature rises and is easy to damage; when the electromagnetic heating device has low voltage and high power, it is difficult to increase the power, so there is a need for improvement. Summary of the invention [0003] The purpose of the present invention is to solve one of the above technical defects at least to a certain extent. [0004] To this end, an object of the present invention is to provide a buck-boost circ...

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Problems solved by technology

[0002] In the prior art, single-tube parallel resonant circuits are used in electromagnetic heating devices such as induction cookers. However, when the electromagnetic heating device has high voltage and low power, the turn-on voltage of IGBT (Insulated Gate Bipolar Transistor, insulated gate bipolar transistor) is high and the turn-on loss is large. , IGBT temperature rises and is easy to be damaged; when the electromagnetic heating device is at low voltage and high power, it is difficult to increase the power, so there is a need for improvement

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