Research On Sensorless Composite Control Of Permanent Magnet Synchronous Motor In Wide Speed Domain Based On DSP

In recent years,along with the development and utilization of high performance rare-earth permanent magnet materials,permanent magnet synchronous motors are widely used in new energy vehicles,household appliances,intelligent manufacturing,aerospace,and other fields with its advantages of high power density,wide speed range and low rotational inertia.Highperformance permanent magnet synchronous motor control system general needs mechanical sensors to obtain accurate rotor position information to achieve normal operation.However,introduction of mechanical sensors not only increases weight and size of system but also directly affects stability of system,making it impossible to operate normally under bad severe conditions,so the sensorless control technology of permanent magnet synchronous motor has important research value.This thesis targets vector control system of permanent magnet synchronous motor,the sensorless hybrid control in wide speed range is studied,and the improvement of its estimation accuracy and response speed is emphatic discussed.The main researches of this thesis are on the following areas:Firstly,the sliding mode observer method suitable for medium and high speed range is analyzed.an improved adaptive sliding mode observer is designed to solve the problems of traditional sliding mode observer,such as low observation accuracy and phase delay,which is easily affected by high frequency chattering,and the stability of the improved observer is judged by Lyapunov stability theorem.By using piecewise function instead of switching function,an adaptive back EMF observer is constructed,which effectively suppresses the influence of high frequency chattering on the system and reduces the phase delay.At the same time,combined with phase-locked loop technology to extract speed and rotor position information,the observation accuracy is improved.The improvement effect is verified by simulation comparison.Secondly,an improved pulse high frequency square wave injection method is studied to solve the problems of carrier signal separation,rotor position estimation delay and observation error in the traditional pulse high frequency injection method suitable for low speed range.In this method,the square wave signal injection is used to replace the original sine wave signal injection,and the high frequency current response is demodulated by mathematical operation method,which avoids the use of filter in the process of signal separation and improves the response speed of the system.At the same time,Luenberger observer is used to extract speed and rotor position information,which further improves the estimation accuracy.The simulation results show the effectiveness of the improved control method.Then,a hybrid control strategy is studied to solve the disadvantage of the above two improved sensorless control methods that only applicable to a specific speed range.The average weighted switching method is used to combine the adaptive sliding mode observer method with the pulsating high-frequency square wave injection method,which avoids the problem of excessive speed pulsation during switching process.The simulation result proves that the hybrid control strategy can realize sensorless control of permanent magnet synchronous motor in a wide speed range.Finally,TMS320F28335 DSP is used as control core to complete design and debugging of hardware and software.An experimental platform for the sensorless control system of permanent magnet synchronous motor was built,and a surface-mounted permanent magnet synchronous motor with power of 750 W was used to conduct a physical test of the researched sensorless hybrid control strategy.Through comparison of experimental waveforms,the feasibility and correctness of the content discussed in this thesis are verified.