Direct Torque Control For Bearingless Induction Motor Based On DSVM

Bearingless induction motor is one kind of new motor which combined motor with magnetic bearings in one stator windings. Compared with traditional magnetic motors, the axial space of bearingless induction motor is short and with the high speed. Bearingless motor make the rotating magnetic field of itself as the bias magnetic field, so magnetic power greatly reduced, with the advantage of high quality energy-saving. Because of bearingless induction motor has some advantage, like weak magnetic easy, the simple structure, high reliability, so it is widely appreciated in science and technology.According to the analysis of bearingless induction motor, establish the mathematical model of bearingless induction motor; Using DSVM-DTC to achieve the self-decoupling of motor's torque, using PID radial force feedback to achieve the control of rotor suspension, according the independent suspension subsystem to achieve the decoupling control between motor torque part and the suspension part; Analyzing the underlay causes of motor torque ripple, improved the DSVM-DTC control strategy when in low speed and introduced the duty ratio control to improve the relatively simple DSVM-DTC's pulse width modulation. It can restrain torque ripple, improve its dynamic and static characteristics, reduce the current distortion. This comprehensive program not only can reduce the ripple of torque, current, flux linkage without increase the switching frequency obviously but also without increasing the complexity of the system and achieve the better control effect in bearingless induction motor.In the end, create tradition DTC, DSVM-DTC, improved low-speed DSVM-DTC, duty ratio control combined DSVM-DTC in MATLAB / Simulink. The results show that duty ratio control combined DSVM-DTC were significantly restrain flux, torque ripple, the current harmonics and a series of serious shortcomings, improve the system's performance effectively. And on this basis, using of DSP (TMS320F2812) to achieve the control algorithm of bearingless induction motor.