Research On Position-sensorless Control Technology Of Surface PMSM In Wide Speed Range

Permanent Magnet Synchronous Motor(PMSM),with its advantages of small size,high power density and wide speed range,has gradually occupied a leading position in the electric drive field of household appliances,rail transit,industrial control,aerospace and other industries.The high-performance control of PMSM requires closed-loop control of its speed and current.The speed and position parameters required for these controls are often measured by installing mechanical sensors.However,mechanical sensors are often limited by environmental,cost,and integration requirements,making it difficult for PMSM to play a good role in some special occasions.The emergence of position sensorless control technology can solve problems of mechanical sensors well,but the research of position sensorless is currently limited to position detection under the condition of a single speed.The research on sensorless control strategy of wide speed range PMSM has good theoretical significance and engineering application value.After a comparative analysis of the existing position sensorless control technology,in order to achieve wide-range adjustable speed control of the motor,for different speed domains,sliding mode observer method(SMO),pulsating high frequency voltage injection(PHFVI)and the smooth switching method of them are studied.The main work content is as follows:First of all,according to different coordinate systems,the mathematical models of the motors are constructed respectively,and the i_d=0 control strategy is adopted to realize the wide-range speed regulation and build the simulation model,which verifies the feasibility.Next,in order to achieve high-speed,stable and high-performance operation in the medium and high-speed range of PMSM,SMO is adopted,and fuzzy control is introduced to adaptively adjust the sliding mode gain to solve the serious problem of SMO chattering and improve the observation accuracy;for the non-ideal factors in the back EMF method Analyze the harmonic content caused by the high-order harmonics,introduce the Delay Signal Cancellation-Phase Locked Loop(DSC-PLL)to suppress the harmonics,and simulate and verify with the traditional method The effectiveness of the proposed method.Secondly,in view of the problem that SMO will fail at zero and low speeds,PHFVI is introduced to realize the zero-speed start of the motor to low-speed operation.Perform theoretical analysis on PHFVI injection signal parameters;consider the amplitude change and phase offset caused by the Bandpass Filter(BPF),simplify and improve PHFVI,eliminate the position angle estimation error caused by the phase offset under the BPF,and eliminate the resulting phase shift causes system instability.The effectiveness of the proposed method is verified by simulation.In view of the switching problem between low,medium and high speed of PMSM,the soft switching method is selected,and the upper limit speed applicable to PHFVI and the lower limit speed applicable to SMO are obtained through simulation analysis,and the appropriate speed switching interval is obtained.Fuzzy theory is introduced to realize the parameters value selection based on experience,calculate the position and speed of the switching interval,and realize the smooth switching during the transition of the two algorithms.Finally,this article builds a sensorless control system of PMSM based on STM32F103 of ARM,gives the hardware system block diagram and the main program and main interrupt subroutine flowchart,and verifies the feasibility of the above method based on this system.Based on the encoder,the characteristics of wide speed regulation at the rated speed of the motor are verified;the accurate position and speed observation performance of SMO at medium and high speeds,and its observation errors and failure phenomena at lower speeds are verified.