| Permanent magnet synchronous motor (PMSM) plays a more and more important role in our daily life for its advantages such as, small volume, light weight, high power density and simple structure. And the combination with high-precision control method such as DTC and Vector Control, makes full use of its advantages. But both of them need detection of position and speed of rotor, in traditional motor control system, it is achieved by mechanical sensors like optical encoder. But the existence of mechanical sensors limits the application of PMSM in some special occasions, for example, in high temperature or high humidity locations. Against this problem, this paper proposes a speed observer based on variable structure control and model reference adaptive system, and apply it into PMSM-DTC system.In addition, this paper makes a progress on the non-linear Quadrature feedback compensation flux observer. On the basis of analysis of the observer, we add a sliding surface into it, so that its performance in low-speed conditions and its accuracy are improved. On the basis of above improvement, this paper combines the advantages of variable structure control and MRAS, and proposes a speed observer based on them, realizing sensorless control of PMSM. Through simulation analysis, the advantages of speed observer such as fast response, low steady-state error and better robustness are proved. And it will return back to new steady-state as soon as possible after disturbance of speed or torque.At last, on the basis of simulation, this paper makes experimental verification. We build the observer on the basis of C language, and make good use of it in PMSM-DTC system. Through analysis of tracking performance under three operating conditions, the feasibility of this method can initially be verified. |
