Implementing Sensorless Performance Improvement And Dead-time Compensation Of Permanent Magnet Synchronous Motor

Frequency conversion drive of permanent magnet synchronous motor(PMSM)is widely used in various fields of industrial motion control.In the variable frequency drive system of permanent magnet synchronous motor(PMSM),the installation of position coder not only increases the cost of production,increases the volume of motor,but also reduces the stability of motor control system.Therefore,the Position-free control strategy is of great significance to the frequency conversion drive of permanent magnet synchronous motor.If the estimation accuracy of Position-free control algorithm is not high enough,it is difficult for the system to achieve good control performance,or even affect the stability of the system.In order to realize the high performance control of sensorless of PMSM in medium and high speed area,it is important to study how to improve the control performance of the control system.In this paper,the sensorless of PMSM is taken as the research object,and the performance of the estimation algorithm and the stability of the motor control system are studied.In this paper,the mathematical model of PMSM is established,and the second-order sliding mode observer and the full-order sliding mode observer based on the extended back-EMF model are established to estimate the rotor position and speed.The control performance of the two sliding mode observers is compared.The influence of the sliding mode observer switching function on the system control performance is analyzed.A new switching function is proposed,which replaces the symbolic function with a curve function to reduce the jitter of the estimated speed and position and improve the control performance of the system.The influence of dead-time effect on motor control system is studied.By compensating the dead-time effect of the system,the vibration of the estimated rotor position is reduced and the control accuracy of the system is improved.Finally,the output back-EMF of the dead-time compensated observer is filtered to eliminate the high-order harmonics in the back-EMF and further reduce the vibration of the estimated rotor position.The experimental platform of sensorless motor control system is built under the software of MATLAB/Simulink to verify the correctness and effectiveness of a series of sliding mode observers.Finally,on the basis of theoretical analysis,a physical experiment platform for sensorless of PMSM is built.And a lot of debugging and verification work has been done on this platform to prove the accuracy of the content analyzed in this paper.The accuracy of system degree estimation has been improved,and the control performance of Position-free vector control system is good.