The importance of welding power supply for resistance spot welding machine

News 2022-06-14 62

The power supply of resistance welding equipment plays a very important role in the performance of all spot welding machines. The inverter power supply of the intermediate frequency resistance welding machine is input through a 380V three-phase AC power supply, converted into a DC power supply by a rectifier circuit and a filter capacitor, and then converted into an intermediate frequency square wave power supply by an inverter circuit composed of power switching devices, and then reduced by a transformer. High voltage and high-power diodes are rectified into DC power supply, which provides the electrodes of the intermediate frequency resistance welding machine and welds the workpiece.

The control circuit of the inverter power supply of the intermediate frequency resistance welding machine is composed of DSP and CPLD, and the PWM wave, detection signal and protection signal generated by the DSP are logically operated in the CPLD. The intermediate frequency inverter resistance welding machine adjusts the power inverter. Generally, current feedback is used to realize PWM to obtain a relatively stable constant current output. The circuit power supply of the intermediate frequency resistance welding machine inverter power supply is the power supply voltage.

U primary is the intermediate frequency voltage output by the inverter, and the secondary current of the transformer is I secondary. Adjusting the pulse width of PWM can control the size of I secondary. The inverter current adopts a full bridge structure. The main circuit is composed of 4 IGBTs and an intermediate frequency transformer. It converts the DC voltage into an intermediate frequency square wave AC voltage and sends it to the intermediate frequency transformer. It is output after decompression, rectification and filtering. The stability of the circuit comes from the stable operation of the IGBT.