Direct Torque Control Of Permanent Magnet Synchronous Machines

Because of its excellent performance, Permanent Magnet Synchronous Motor (PMSM) has been paid more attention in the past two decades. With the development of the PMSM design and its control techniques, the PMSM has widely been used in many industrial applications. When time goes on, Direct Torque Control (DTC) has become an accepted advanced control method beside the current vector control. Although DTC was initially applied in asynchronous machines, but it has been introduced successfully to synchronous machines. This thesis will discuss the DTC in the PMSM.Based on widely reading of references and understanding of PMSM operational principle, the thesis analyzes the principle of PMSM DTC and proposes the PMSM DTC strategy. The main contents of the study as follows:(1) An introduction to the space vector theory and its application on the modeling of PMSM is presented firstly, which shows the basic idea of PMSM DTC. A comparison of DTC in asynchronous machine and PMSM is made as well. In order to take the full advantage of the DTC, the PMSM has to be properly selected. Therefore the effect of the motor parameters is analyzed taking the control principle into account.(2) Based on the basic analysis of the PMSM DTC principle, the function and the realization of the sub-modules of PMSM DTC are discussed. A set of PMSM DTC strategy and the simulation platform are presented; the simulation result proves that this set of strategy is effective in the theory.(3) A hardware platform with the arrangement of DSP+IPM and PMSM DTC software realization are also given in the thesis. The drive system works the way that we expected, which gives the solid feasibility reasons of the strategy. Although some problems for the strategy are still found in the real system, this thesis will give the explanation for them.This thesis discusses principal issues of the PMSM DTC such as prime principle, control strategy, stator flux linkage estimation and its applications etc. By the theoretical analysis, computer simulation and experimental investigation, some valuable experiences and significant conclusions are given, which found the basis of the project for the further studies.