High Performance Direct Torque Control For Permanent Magnet Synchronous Motor Based On DSP

In this thesis, the research works are focused on the Direct Torque Control (DTC) of Surface Permanent Magnet Synchronous Motor (SPMSM). Control strategies, flux observation, rotor initial position detection, phase voltage calculation, and the DSP-based PMSM DTC experiment platform design are studied. Theoretical analysis, simulations and experiments are presented in order to demonstrate the effectiveness of the proposed techniques and the flexibility of PMSM DTC.Firstly mathematical models of SPMSM are set up based on the motor electromagnetism, and an in-depth research is conducted on PMSM DTC. Secondly the basic issues are discussed such as the principle of stator flux linkage sections partition, the effect and the selection of the voltage space vectors in PMSM DTC. Then a variable-speed PMSM DTC system is set up to verify the DTC theory in PMSM. Also an investigation about the effect of the zero voltage space vectors in the PMSM DTC system is described. If using the zero voltage space vectors rationally, not only the DTC system can be driven successfully, but also torque ripples are reduced and the performance of the system is improved.By analysising the drawback of the conventional PMSM DTC, a new DTC strategy based on voltage space vectors and flux linkage regions subdivision is introduced. The more flux linkage regions make the more accurate estimation of flux linkage position and the more voltage space vectors make the more optional choice according to dispersions of the torque and flux linkage. Consequently, the ripples of torque and flux linkage are diminished and the performance of the DTC system is improved.Only one voltage space vector is applied in each sampling period in conventional PMSM DTC, which results in large ripples in torque and flux linkage, and nonconstant switching frequency. A new DTC algorithm based on the area voltage vectors table has been proposed. It includes mainly two parts: one is area voltage vectors table and the other is predictive control of torque and flux. By using the predictive control strategy, voltage space vectors with arbitrary phase angle and magnitude can be selected to control torque and flux from a voltage vectors area, which can lead to high dynamic performance and can reduce...