Simulation of TIG welder unit in PSpice

This paper presents the modeling and simulation of TIG welding in PSpice simulator. The TIG welder unit is modeled by use of a transistor chopper, a PWM generator and an analog PID regulator. The load of the welder unit is the electric arc. The arc model is formed based on the combination and modifications of classical Cassie and Mayr equations. The combination of these two models gives an acceptable approximation of static and dynamic behavior of the electric arc. To implement the arc model in PSpice, nonlinear controlled current and voltage sources were used. The model of electric arc is parametrized and verified through comparison of simulated waveforms with the experimental waveforms from the literature [1], given for low frequency (50 Hz) power source. This model is used for loading the high-frequency welder unit by simulations. The choice of initial values of PID regulator parameters was based on experience. Later the parameters were optimized by repeated simulations.