Research Of Sensorless Control Of Permanent Magnet Synchronous Motor Based On High Frequency Signal Injection

Permanent magnet synchronous motors (PMSM) have been widely used as AC drives over the last several years due to their high efficiency, high power density and no DC field winding in the rotor. Motion control of PMSM requires accurate position and velocity signals to realize field orientation. In conventional motion controls, optical encoders or electromagnetic resolvers are used for this purpose. However, these additional sensors increase the cost of system and decrease the reliability.The thesis takes embed PMSM as subject investigated and focuses on the sensorless operation in the whole speed region, including zero speed.The thesis introduced that high frequency signal injection was used to detect the spatial position of PMSM's rotor based on the salient pole's effect. After the high frequency signal injection into the stator, the saliency of the rotor at low speed modulated the current which was generated by the voltage signal of high frenquency, and the current of high frenquency was the function of the position of salient pole, which also had the information of rotor's position. In this way, heterodyne method was used in the rotor's position tracking observer, which could extract the information relating to rotor's position from stator's current vector. The error of the rotor's position could be obtained which could be used to construct the estimation system of rotor's position. The rotor position estimation method which is based on Luenberger observer is discussed in detail, and torque command is the feedforward command to the Luenberger observer to obtain the zero-phase lag position estimation. In the passage, high frequency voltage and currunt signal injection are both analized. In the strategy of vector control, the maximum torque per current control is discussed. It can take advantage of the saliency of the motor to make maxium electromagnetic torque in the use of the currunt of motor stator. The paper introduces PWM technology of spatial voltage vector in detail, and takes the method of SVPWM to inplement the three-modulation of the wave of PWM.The simulation which is used by Matlab/Simulink for sensorless vector control operation is completed both at low-speed and zero speed. The results show it is feasible for low speed including zero speed.