CONTROL PREDICTIVO DE VELOCIDAD Y CORRIENTE EN CASCADA EN ACCIONAMIENTOS

Abstract

This work presents and experimentally validates a new control scheme for electricaldrive systems, named cascaded predictive speed and current control (PSCC). This newstrategy uses the model predictive control concept. It has a cascaded structure like thatfound in field-oriented control or direct torque control. Therefore the control strategy hastwo loops, external and internal, both implemented with model predictive control. Theexternal loop controls the speed, while the inner loop controls the stator currents. Theinner control loop is based on Finite Control Set Model Predictive Control (FS-MPC),and the external loop uses MPC deadbeat, making full use of the inner loop's highlydynamic response. Experimental results show that the proposed strategy is overshootfreeand has a high dynamic response.On the other hand, FS-MPC has many advantages, such as fast dynamic response andintuitive implementation. For these reasons it has been thoroughly researched in thelast decade. However, the spread switching frequency spectrum of FS-MPC remains amajor disadvantage of the strategy. The second part of this research discusses a modulatedmodel predictive control that guarantees a fixed spectrum switching frequency inthe linear modulation range and extend its optimized response to the over-modulationregion. Due to the equivalent high gain of the predictive control, and due to the limiton the voltage actuation of the power converter, it is expected for the actuation voltageto enter into the over-modulation region during large reference change or in response toload impacts. For this situation an optimized over-modulation strategy, that convergesto FS-MPC response for large tracking errors, is proposed. This technique seamlesslycombines the good steady-state switching performance of PWM with the high dynamicresponse of FS-MPC during large transients. Experimental results that show thegood steady-state switching performance, the FS-MPC like transient response and theseamless transition between modes of operation are presented for a permanent magnetsynchronous machine drive to test the proposed modulated predictive control strategy.