High-performance control of electric drives.

The improvement of the performance and the use of strategies that require the least tuning work possible, have always been among the biggest challenges in the field of electric drives. The strategies that are most used in high performance AC motor drives are Field Oriented Control (FOC) and Direct Torque Control (DTC). In the last years thanks to the strong improvement of the microcontroller performances it was possible to adopt new control strategies based on the MPC. At present, among the most recent innovations, in the field of electric drives for AC motor drives, there is the Sequential Model Predictive Control (SMPC). The elimination of weighting factors and associated tuning work is among the biggest advantages of the SMPC strategy. The evaluation of the cost functions takes place in two sequential stages, reducing the number of vectors available for the evaluation of the cost function at each stage. Like the conventional finite control states MPC, the SMPC also has a disadvantage of variable switching frequency. In this thesis a detailed analysis of the SMPC strategy was carried out, and modulation was also implemented to solve the problems related to the variable switching frequency. All analyses were conducted on a three-phase induction motor powered by a 2-Level Voltage Source Inverter (2L-VSI). The effects of reducing the vectors used to evaluate the cost functions in the second stage, the inversion of the cost functions evaluated in the two stages and finally the improvements obtained thanks to the implementation of the modulation were studied. Everything has been verified both by simulations and experimental tests. In particular, it is shown that the introduction of the modulator allows to obtain performances from the SMPC strategy that are on a par with their competitors, but without using weighting factors and therefore avoiding all the tuning problems.