Research On Sensorless Full Speed Control Method Of Permanent Magnet Synchronous Motor

In recent years,China has been promoting the work of carbon neutral carbon peak,and with the continuous improvement of the "1+N" policy system of double carbon action,energy-saving and environment-friendly motors in the field of power electronics and power transmission will definitely go to a broader market,among which Permanent Magnet Synchronous Motor(PMSM)is promoted to many application scenarios in daily life,agriculture,industry,and military with its advantages of high efficiency,low loss,and good force energy index.PMSM with its high efficiency,low loss,good force index and other advantages,is promoted to daily life,agriculture,industry,military and many other application scenarios.The mainstream motor control method is Field-Oriented Control(FOC),which relies heavily on mechanical sensors to accurately identify the rotor position,and in some special scenarios such as shaftless thrusters for submarines and drive motors for fans,mechanical sensors cannot be used at all.In these special scenarios,a sensorless motor control strategy is needed.In this thesis,the sensorless motor control strategy is studied with the bullet-punching machine in Robo Master competition,and the research is carried out in both the zero-low speed domain and the medium-high speed domain of motor operation.The main contents of the study are:(1)In the zero-low speed domain of motor operation,a secondary positioning method was used to determine the rotor position,and the I/f start control strategy is adopted after determining the motor rotor position.Finally,the simulation on Matlab/Simulink platform verifies that the secondary positioning method can better solve the problem of positioning blind area and the I/f start can steadily drag the motor.(2)In the medium and high speed domain of motor operation,a sensorless control method based on the adaptive sliding mode observer is employed.Firstly,constructing the current-type sliding mode surface based on the state equation of the PMSM model.Secondly,determining the sliding mode control law and then introducing the adaptive law to estimate the extended counter-electromotive force.Thirdly,the speed and position angle is estimated by designing the quadrature phase-locked loop.Finally,the simulation on Matlab/Simulink platform verifies that the adaptive sliding mode observer has better dynamic characteristics when the motor parameters are varied compared with the conventional sliding mode observer.(3)In the transition process of switching from the zero-low speed domain of motor operation to the medium-high speed domain,a weighted switching method based on the improved Sigmoid function is used to adjust the command angle during the I/f start to approximate the estimated angle of the sliding mode observer,and a smooth transition between the two operating regions is achieved while maintaining the motor operating performance.Finally,the feasibility of this switching method is verified by simulation on Matlab/Simulink platform.(4)A hardware experimental platform for PMSM is built and related program is designed,and the sensorless control methods in the full speed range utilized in this thsis is physically tested.The analysis of the experimental results shows that the control strategy can make the motor accelerate more stably in the zero-low speed domain,transition smoothly in the switching interval,and have good operating efficiency and dynamic-static characteristics in the medium-high speed interval.