The importance of welding power supply for resistance welding equipment

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 medium frequency resistance welding machine is input through a 380V three-phase AC power supply, which is converted into DC power supply by the rectifier circuit and filter capacitor, and then passes through the power switch The inverter circuit composed of the device is converted into a medium-frequency square wave power supply, which is then decompressed by a transformer and rectified by a high-power diode into a DC power supply, which is used as the electrode of the medium-frequency resistance welding machine to weld the workpiece.

The control circuit of the medium frequency resistance welding machine inverter power supply is composed of DSP and CPLD. The PWM wave, detection signal, and protection signal generated by the DSP are logically calculated in the CPLD. The regulating power inverter of the medium frequency resistance welding machine is generally implemented by current feedback. PWM to obtain a relatively stable constant current output, the circuit power supply of the medium frequency resistance welding machine inverter power supply is the power supply voltage.

U primary is the inverter output intermediate frequency voltage, and the transformer secondary current is I secondary. Adjusting the pulse width of PWM can control the size of I secondary. The inverter current uses a full-bridge structure. The main feature is that the main transformer has strong working ability. The main circuit consists of 4 IGBTs and an intermediate frequency transformer. The DC voltage is converted into an intermediate frequency square wave AC voltage and sent 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 IGBTs.