Διανυσματικός έλεγχος κινητήρα μόνιμων μαγνητών με χρήση PI ελεγκτών και προβλεπτικού ελέγχου

Abstract

Τhis diploma thesis refers to the field oriented speed control of a permanent magnet synchronous motor with PI controllers and predictive control. In the first part there is a brief presentation of control systems with PI controllers. The understanding and design of these controllers is of great importance because such control systems are used in the majority of industrial electric motors and power converters. The design of the PI controllers is based in the pole-assignment control method. This method is distinguished by its simplicity in designing a control system and provides an efficient method of selecting parameters for optimal closed loop performance in transcient response, disturbance rejection and noise attenuation. Τhe PI control system is in cascade feedback structure in the q-axis, in which both inner-loop q-axis current and outer-loop velocity are controlled with PI controllers. In addition an anti-windup mechanism is needed for the implementation in order to avoid the saturation phenomenon caused by integral wind-up. In the second part the topology remains the same with the difference that an implementation of predictive control is used for the control of of the inner loop currents. The mathematical model derives from the descitisation of the machine equations.The cost function which is used predicts one step ahead Since for a two level VSI, there are eight combinations of inverter states, the terminology of finite control set (FCS) is given. Furthermore, the optimization of the inverter states is performed using the receding horizon control principle, which is the core of model predictive control. By combining the finite control set with model predictive control technology, FCS-MPC is given and also simulated in Matlab.In addition in order to overcome steady-state errors a second predictive control model that contains an integrator(I-FCS-MPC) is used .