Why can resistance welding equipment be used in the automotive industry?

Resistance welding equipment is ubiquitous, especially in the automotive parts manufacturing industry. According to differences in welding control principles, it is mostly divided into medium frequency spot welding machines, variable frequency spot welding machines, power frequency spot welding machines, energy storage spot welding machines and three-phase secondary Rectifier spot welding machines and other types of resistance welding equipment.

The output frequency of the variable frequency spot welding machine controller can be adjusted to suit transformers of different frequencies. Compared with ordinary industrial frequency welding machines and medium frequency welding machines, its output is a complete sine wave, the equipment has less spatter, and the three-phase power consumption is balanced , which has the advantages of less pollution to the power grid.

The control circuit is composed of DSP and CPLD. The PWM wave, detection signal, and guarantee signal generated by the DSP are logically operated in the CPLD. The resistance welding machine control power inverter generally uses current feedback to complete PWM to obtain a stable constant current output. In the circuit schematic diagram of the inverter power supply of the variable frequency spot welding machine, the U power supply is the power supply voltage, the U primary is the inverter output variable frequency voltage, the transformer secondary current is the I secondary, and controlling the pulse width of the PWM can control the size of the I secondary. The current variable adopts a full-bridge structure. The specific feature is that the main transformer has strong working ability. Its main circuit is composed of 4 IGBTs and an intermediate frequency transformer. The DC voltage is converted into a variable frequency square wave AC voltage and sent to the variable frequency transformer. It is output after step-down rectification and filtering. , the stability of the circuit comes from the stable operation of IGBT