The research of variable parameter PI adjustment based on the fuzzy control technique

A variable parameter PI adjustment system based on the fuzzy control technique was developed, which improved the performance of the dynamic response of inverter welding power supply effectively. DSPIC30F2020 was used as the core control chip, and a two-input two-output fuzzy controller was established. By taking the welding current deviation and its changing rate as input signals, and fuzzy processing them respectively, the PI control parameters were optimized, which make sure the precise controlling of the power output. With a resistive and a capacitive load, comparison tests between dynamic response of a variable parameter PI control system and a traditional PI control system were carried out. The results proved that: The rise time of a step response of current with variable parameter PI adjustment is less than 0.4ms; In short circuit transfer welding, variable parameter PI adjustment can inhibit the overshoot effectively when the load changes dramatically, which will be the basis of the inhibition of welding spatter.