Power supply device used for arc machining

Abstract

PROBLEM TO BE SOLVED: To overcome the problem that the reduction in the reverse bias voltage of a switching element drive circuit operable to drive an inverter circuit of a power source device increases the turn-off loss, which leads to the deterioration of the switching element. SOLUTION: The power source device for arc processing comprises: a DC conversion circuit; a full-bridge inverter circuit which converts a DC voltage to a high frequency AC voltage; an output control circuit which controls the inverter circuit, and stops the inverter circuit for a given length of time when the input current to a transformer reaches or exceeds a reference current; a switching element drive circuit which drives a switching element according to an output control signal, and supplies a reverse bias capacitor with current; and a switching control circuit. The switching control circuit turns on first and fourth switching elements so that the period of the first switching element remaining ON does not overlap the period of the fourth switching element remaining ON between 0 and 1 / 2 cycle, and turns on second and third switching elements so that the period of the second switching element remaining ON does not overlap the period of the third switching element remaining ON between 1 / 2 and 1 cycle when the inverter circuit remains stopped.

Description

technical field [0001] The present invention relates to control of a switching element drive circuit that drives an inverter circuit built in a power supply device. Background technique [0002] When the reverse bias voltage of the switching element of the inverter circuit built in the power supply unit for arc machining is lowered, there will be a delay in turning off, and the turn-off loss will increase. [0003] Figure 4 It is the electrical connection diagram of the power supply device for electric arc machining in the prior art. exist Figure 4 Here, the DC conversion circuit is formed of a primary rectification circuit DR1 and a smoothing capacitor C1 provided in parallel on the output side of the primary rectification circuit DR1. [0004] The inverter circuit INV forms a full bridge through the opposing first switching element TR1 to fourth switching element TR4, converts the DC voltage into a high-frequency AC voltage, and outputs it. [0005] The transformer INT...

AI Technical Summary

Problems solved by technology

[0020] However, if the operation stop time of the inverter circuit becomes longer, the charging of the reverse bias capacitor forming the switching element drive circuit becomes insufficient, and the reverse bias voltage decreases.

Moreover, if the reverse bias voltage decreases, the turn-off speed of the switching element will slow down. If the long-term short circuit is released in this state and the inverter circuit starts to operate, the initial turn-off loss and the loss of the switching element during turn-off will be reduced. The collector current will increase significantly, causing the problem of deterioration of the switching element

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