A parallel induction heating power supply inverter feedback circuit and method

Abstract

The invention relates to the technical field of induction heating power supplies and discloses an inverter feedback circuit and method for a parallel induction heating power supply. Circuits adopted by the method include a voltage division circuit and a voltage following and amplitude-limiting circuit, wherein the voltage division circuit connected with an LC parallel resonance loop is connected with the voltage following and amplitude-limiting circuit; and one part of the output end of the voltage following and amplitude-limiting circuit is connected with a frequency feedback output circuit through a sine voltage amplifying amplitude-limiting and shaping circuit while the other part of the output end of the voltage following and amplitude-limiting circuit is connected with a voltage feedback output circuit through a sine voltage rectifying, filtering and amplifying circuit and a voltage-frequency conversion circuit. The inverter feedback circuit and method are suitable for parallel resonance induction heating power supplies of more than 100kW; the problem of reduced power factor caused by change of the resonant frequency of an LC parallel circuit due to change of the magnetic properties when the temperature approaches or reaches the Curie point temperature in a workpiece heating process is solved; the situation of damage to main devices such as an IGBT and the like by a high current generated in circuit detuning is avoided; and the induction heating power supply is ensured to work normally.

Description

technical field [0001] The invention relates to the technical field of induction heating power supplies, in particular to a parallel induction heating power supply inverter feedback circuit and method. Background technique [0002] At present, the 0-500V DC voltage of the induction heating power supply is obtained by a three-phase fully-controlled rectifier circuit, and sent to the circuit composed of four insulated gate bipolar transistors (IGBT) V1, V2, V3, and V4 through smoothing reactors L1 and L2. The inverter bridge, the inverter bridges V1, V2, V3, V4 are alternately turned on under the action of the trigger pulse sent by the main control circuit, and the frequency of the pulse is controlled by the main control circuit. During the heating process of the workpiece, as the temperature approaches or reaches the Curie point, the magnetic properties will change, thereby changing the resonant frequency of the LC parallel circuit, resulting in a decrease in power factor, ci...

AI Technical Summary

Problems solved by technology

During the heating process of the workpiece, as the temperature approaches or reaches the Curie point, the magnetic properties will change, thereby changing the resonant frequency of the LC parallel circuit, resulting in a decrease in power factor, circuit detuning, and large current, which may cause IGBT Damage to major components

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