| Recent years,the Permanent Magnet Synchronous Motor(PMSM)system has been widely applied in the fields of home appliances,industrial control and aerospace.However,the nonlinearity of the inverter in the PMSM system and the non-ideal factors of the motor will inject a large number of harmonics in the phase current,resulting in larger output torque ripple,which limits the application of PMSM in high-precision occasions.Meanwhile,installing a position encoder will increase the cost and volume of the motor and reduce the reliability of the control system.Therefore,the researches on current harmonic suppression technology and position-sensor-less control strategy are meaningful for the drive control of PMSM.The main content and results of the thesis are as below:(1)Current study at home and abroad:describing the existing PMSM current harmonic suppression technology and position-sensorless control method,using harmonic current suppression method which combines the rotating PI,disturbance observer and proportional quasi-resonance to suppress specific current harmonics such as 5th,7th,11th and 13th,proposing an improved high-frequency injection position estimation method for the shortcomings of traditional methods.(2)Basic theoretical analysis and mathematical deduction.The basic types and mathematical models about PMSM are introduced,the coordinates transformation formulas are deduced and the dynamic mathematical model of PMSM is constructed with the help of coordinate transformation theory.The common control methods such as i_d=0 control are explained,and the influence of the inverter’s nonlinearity is deeply analyzed.The mathematical model of harmonic motor is deduced(3)Researches on specific sub-current harmonic suppression strategy.These includes using rotating PI algorithm,disturbance observation strategy and proportional quasi-resonance adjustment compound harmonic suppression strategy.Under the harmonic d-q axis system,the former extracts the harmonic components and then enters the harmonic voltage calculation module,transforms the calculated harmonic voltage components and injects them into the control system to eliminate the influence of harmonics.The latter combines disturbance observation and resonance in order to eliminate system disturbances and fully use the zero-steady-error tracking characteristics of resonance control.The simulation results show that both two current harmonic suppression strategies are effective.(4)An improved PMSM position estimation method is proposed and studied.The basic theory of high-frequency injection method is introduced,two position estimation strategies are analyzed and the method based on amplitude judgment is used to identify the initial magnetic pole position.In order to solve the problems of traditional high-frequency injection method in PMSM sensorless control,an improved high-frequency injection position estimation method is proposed.This method considers the influence of coupling term and current detection deviation on position estimation.By designing a new position signal acquisition method,a pre-compensation way is used to eliminate the influence of coupling term,and a parameter self-adaptive filter is designed to eliminate the second harmonic caused by current detection deviation.The simulation verifies the feasibility of the improved algorithm.(5)The experimental verification of control strategy:build an experimental platform and design the control program with TMS320F28335 chip as the core.By comparing the harmonic suppression experiments,it is proved that both the harmonic current suppression which based on the rotating PI and the compound control harmonic suppression method can effectively suppress the specific sub-current harmonics of the PMSM.By the improved high-frequency signal injection control experiment,it proves that the proposed methods can effectively estimate the rotors’position and speed. |
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