Sensorless Control of Surface-Mounted Permanent Magnet Synchronous Motor Based on Sliding-Mode Observer

　　Sensorless Control of Surface-Mounted Permanent Magnet Synchronous Motor Based on Sliding-Mode Observer
　　This thesis presents an approach to sensorless vector control system of permanent magnet synchronous motor (PMSM) using sliding-mode observer.First of all, mathematical models of PMSM are set up. Afterwards, the theory of sliding-mode observer is analyzed in details. The nonlinear equations of motor driver are linearized using αβ reference frame. Real-time online estimation of motor rotor position and speed of PMSM is conducted utilizing sliding-mode observer. Neodymium Magnets To obtain the rotor position and speed, it is sufficient that the terminal voltage and phase current of motor are known according to the model of motor driver. It is not influence on the performance of control that the d- and q-axis current components are estimated to feed back at the same time,
　　which is an important character of the sliding-mode observer. The observer shows that the time-delay, in rotor position estimation, does not have influence on the vector control when the d- and q-axis current components are accurately estimated. The d- and q-axis current components are accurately estimated when the estimated e.m.f. and current space vectors have the same delay as to the actual ones. The PI controllers, fed by the actual d- and q-axis current errors, generate the correct voltage references in the estimated rotor reference frame. The coordinate transformation needs the estimated rotor position with no correction. To obtain accurate estimates of the d- and q-axis current components, it is sufficient that the estimated e.m.f. and current space vectors have the same delay with the actual ones. An adaptive sliding-mode observer, with low-pass filter, is used to estimate the e.m.f. space vector, and a similar low-pass filter to delay the current space vector. The rotor speed and position are http://www.999magnet.com obtained from the estimated e.m.f. space vector and its derivative. The simulation in the environment of Matlab shows that this method has good motor rotor position tracking performance and rather good speed tracking performance. Moreover, the ability of anti-disturbance of load is the remarkable feature of this system, and the controlling performance is pretty good. It is shown this method makes it.In addition, the realization of control system needs PWM wave, which is generated by SVPWM. Its theory is explained in detail, and SVPWM simulation model is set up as a part of control system. Simulation results are presented to prove the exactness and effectiveness of the modulation approach.At last, by the experiment of the hardware and software system designed it is shown that DSP has fast calculating capacities. DSP can implement all complex arithmetic in real time.