Research On Speed Sensorless Control Strategy Of Vehicle Permanent Magnet Synchronous Motor

Faced with the dual challenges of the global energy crisis and the deteriorating environment,countries around the world are accelerating the advancement of the electric vehicle industry.Permanent magnet synchronous motors are widely used in electric drive systems of electric vehicles due to their high power density,high efficiency,and low noise.In order to achieve high-performance vector control of the permanent magnet synchronous motor electric drive system,it is necessary to use a mechanical sensor to actually detect the rotor position of the motor.However,mechanical sensors will not only increase the size and cost of the electric drive system,but also reduce the reliability of the electric drive system.Therefore,the sensorless technology of permanent magnet synchronous motors has become a research hotspot in the field of motor control,and it is bound to accelerate the innovation of electric drive technology for electric vehicles.This paper first analyzes and theoretically studies the sensorless technology of permanent magnet synchronous motors in different speed regions at home and abroad,and summarizes their advantages and disadvantages.Secondly,the physical structure and mathematical model of PMSM are introduced,and the vector control and space vector pulse width modulation algorithm are briefly summarized.Then,the sliding mode observer algorithm suitable for sensorless operation in the medium and high speed region is researched.The traditional high frequency chattering,phase delay and estimation accuracy of traditional sliding mode observer and adaptive sliding mode observer need to be further improved.In this paper,an improved adaptive sliding mode observer algorithm is proposed.Based on the extended back-EMF estimation,the rotor magnetic flux is estimated by introducing the realtime participation of electrical angular velocity,and the rotor position information and The experimental results show that the method reduces the system chattering,improves the estimation accuracy and robustness.Then,the theoretical analysis shows that when the motor turns abruptly,the traditional phase-locked loop structure will cause a large error in the estimated rotor position.This error can be avoided by using a phase-locked loop structure based on the tangent function.Because the back-EMF signal-to-noise ratio obtained by the motor at zero and low speed operating areas is small,the sliding mode observer method is no longer applicable,and the high-frequency voltage injection method is widely used in this range.Aiming at the additional loss caused by the high-frequency voltage injection method to the system,the I /F control algorithm has the advantages of simple structure and low cost to complete the rotor position estimation in this range.By analyzing the principles of open-loop I / F and closedloop I / F,the closed-loop I / F algorithm can automatically adjust the current size as the load changes,improving the current utilization rate and enhancing the stability of the system.By designing a reasonable linear switching algorithm,the sensorless control of the electric vehicle in the full speed range is achieved.This paper builds a permanent magnet synchronous motor hardware system platform based on DSP28335 as the main control chip.The experimental results verify the effectiveness and practicality of the above method.The method studied in this paper has certain practical value for the speed sensorless control technology of the permanent magnet synchronous motor in the full speed range.