Intelligent PID Control For PMSM Servo Systems

With the development of microelectronic technique, power electronics technique, sensor technique and the advancement of permanent-magnet material and control theory, servo technique had come into the age of AC at the end of 70's. Kinds of AC servo systems have been developed and applied to automation control field. To some extent, they also have replaced magnetic stepping motors and DC servo motor drive systems, up to now, AC servo systems have been the mainstream of servo systems.In the AC servo system control, all the control theories based on the classical control theory and modern control theory face the same problem. That is they all depend on the motor model, and when the system suffered the influences of parameters varying and disturbance, its performance will be much affected. So, how to restrain this influence has always been a big problem. In recent years, it is an inevitable trend that imports intelligent control which is taken seriously into AC servo control, because it can get rid of the dependence of control plants' model and has feasibility and robustness for processing the uncertain and inexact problems.Aiming at the parameters varying and highly nonlinearity of permanent magnetic AC servo system, a new nonlinear immune controller is proposed based on the immune feedback law applied to the speed control and position control of permanent magnetic servo system to realize high performance AC servo system with adaptation. The content of this research falls into the following.This paper analyzes the work mechanisms, builds the mathematical model of permanent magnetic synchronous motor firstly and analyzes its work characteristics and control mechanisms deeply. Then, analyzes the control system globally, and aiming at PMSM's nonlinearity and highly coupling builds three closed loops system which includes position loop, speed loop and current loop with three different kinds of frequency conversion (PWM, SPWM, SVPWM) by using vector change to decouple the motor model. And the simulations with Matlab/Simulink have been done for the three closed loops system.Based on the characteristics of PID control, this paper analyzes its relative merits, introduces conventional PID control principles and its parameters regulating methods. And also introduces the intelligent PID control principles and its parameters regulating methods.This paper researches the feedback law of biological immune system, abstracts and simplifies the complicated self-regulating mechanism of immune system. Thus obtains the feedback mechanism of immune response. And makes an analogy between immune system and control system, proposes a new immune controller. This fuzzy-immune PID controller combines conventional PID control and fuzzy inference to make up fuzzy-immune PID controller is used to improve the control performance. Simulation results demonstrate that, this system has better dynamic performance, stronger disturbance rejection ability and higher robustness compared to conventional PID control. And the arithmetic is simple, easy to realize and has feasibility to someextent.