The Methods Of Gain Self-tuning Of Controllers For PMSM Drives

In this paper, a new and practical real-time gain-tuning method for proportional plus integral (PI) controllers has been introduced, using the speed control of a permanent-magnet synchronous motor drive system as a studied object. This novel strategy proves to be a completely model-free approach, it not only enhances the performance of traditional PI controller greatly, but also preserves the simple structure and features of PI controllers.The essential idea of self-tuning controllers described in this essay is as follows: according to the system dynamics to step variation, to define a performance index to evaluate the system response; based on the monotonous relationship between the performance index and an intermediate PI gain parameter, this latter parameter is estimated with tuning approach in order to improve the performance index; finally, PI gains are calculated and renewed according to the estimated intermediate, in order to improve the performance of system. This method has been tested under different conditions such as small initial overshoot, big initial overshoot and a sudden load variation. It proved by the experiments that this method is effective and able to apply widely to AC servo systems.In this paper, two kinds of self-tuning methods of gain and a kind of method of nonlinear PID controller's gain-tuning have been put forward. To achieve tuning the gain of the controller by software and digital logical circuits, This article took the first method for example and introduced the tuning process and tuning result in detail, meanwhile, it has also been validated by the experiments and MATLAB. Besides simple structure and easy implement for real-time applications, the proposed methods also possesses features such as versatility, stability, and effectiveness. In addition, they can be joined in to existent servo systems easily in order to improve the dynamic performance of systems. The contradiction between respond speed of normal PID control system and overshoot is solved by joining a non-liner gain before a liner PID controller with constant gain.