The universal approximation characteristic of fuzzy controller and precision control for inverter welding power source

In the past few years, fuzzy systems have been used in many actual applications and many available explorations have been carried out. The majority of such fuzzy systems are Mamdani fuzzy system. With fuzzy singletons as rule consequent, however, it is a kind of simplified fuzzy system, and equivalent to the linear T-S fuzzy systems under special conditions. In order to improve the fuzzy control accuracy, it is necessary to increase the number of membership functions on the universe of discourse, and this will result in the increase of the cost and complexity of control system. A solution scheme based on the T-S fuzzy system is proposed to achieve precision control in welding process in this paper. T-S model is essentially a nonlinear interpolator between linear systems and a kind of universal approximator. It can satisfy the requirement of dynamic characteristics of complex systems in the control process, and is thought of as a feasible method for solving those of control problems with nonlinear, time-variable, strongly disturbed and strongly coupled characteristics. By use of adaptive tuning membership function in rule premise and the associated parameters of T-S fuzzy model, precision control in welding process can be implemented. Simulations and experiments show that steady characteristic and accuracy of the welding system designed are improved significantly.