Study On Sensorless Position Technology And Harmonic Suppression Of PMSM

In recent years,the rapid development of science and technology leads to the continuous progress of industrial automation.As the actuator of the transmission mechanism,PMSM has become a necessary part in the field of industrial control.The ultimate aim of the PMSM control system is to make the output speed of the motor match the preset value,and the torque pulse is small.The vector control system of PMSM is suitable for most occasions.Vector control of PMSM needs to collect rotor position information of the motor.The sliding mode observer is robust for nonlinear system.The position information of the motor is accurate and the algorithm is simple.The difficulty is that it is difficult to measure the back EMF information at low speed.These include cogging effect of motor,conduction voltage drop of inverter,saturation voltage drop of diode and the dead time will increase the harmonic content of the motor current,and the torque ripple will become larger.For this reason,this paper proposes a PMSM sensorless technique to suppress the current harmonics,which not only solves the disadvantages of the mechanical sensor and the bad performance of traditional SMO in low speed,but also eliminates the harmonics in the system.Firstly,this paper analyzes the development of motor and the current situation of motor control system at home and abroad,and compares the common motor control mode and the realization mode of the sensorless technology.The control of PMSM is realized by using the vector control method of id=0 and measuring the position information of the motor with a new SMO.Secondly,the mathematical model of PMSM is established.The vector control of PMSM is realized by controlling inverter with SVPWM modulation technology.The nonlinear factors of the inverter and the influence of the modulation strategy on the system and the harmonic suppression mode are analyzed.The traditional SMOmodel is established in the ?-? coordinate system.This paper first obtains the back EMF information and then extracts the position information.The new SMO is established in the d-q coordinate system,and the speed information of the motor is extracted directly through the sliding surface.Thirdly,simulation model of the system under Matlab is built,including vector control model,PMSM model,new sliding mode observer model,SVPWM model,and proportional resonant regulator module,etc.The simulation results can prove the establishment of the sliding mode observer.The stator current waveform of the motor before and after the PR regulator is compared,and the suppression effect of the harmonic is observed.Finally,the hardware circuit and software of control system are designed,and the hardware platform of control system is built.The results prove the feasibility of the system.