Sensorless Control Of High Speed Permanent Magnet Synchronous Motor Based On Improved Sliding Mode Observer

High speed Permanent Magnet Synchronous Motor(HSPMSM)has the advantages of high power density,small moment of inertia,fast dynamic response and high working efficiency.It is widely used in aerospace,mold processing,industrial and agricultural modernization,smart home and other fields.Since the speed of HSPMSM in operation is generally not less than 10000 r/min,the stator current frequency will be several times higher than that of the constant speed motor.Execssive current frequency will not only bring a lot of harmonics,but also bury hidden trouble to the safe use of inverter.In addition,the use of mechanical sensor will not only increase the cost of the control system,but also reduce the stability of the system,and the high speed of the high speed motor makes it impossible for ordinary sensors to accurately detect its speed and rotor position,so it is necessary to adopt sensorless control technology to obtain rotor information.The high speed and high frequency characteristics of HSPMSM pose new challenges to the inverter technology and sensorless control technology,so studying the related technology has theoretical and practical significance.In this paper,the two aspects of HSPMSM control system inverter algorithm and sensorless control method are studied.Firstly,the research background of the subject and the current research situation both at home and abroad are elaborated.And the control methods for HSPMSM are summarized,and these methods are studied and analyzed.Secondly,the mathematical model of HSPMSM is established respectively in ABC three-phase stationary coordinate system,α-β two-phase stationary coordinate system and d-q two-phase rotating coordinate system.On this basis,the vector control,space vector pulse width modulation(SVPWM)technology and sensorless control of HSPMSM are studied in depth.To suppress the current harmonic and improve the reliability of using inverter the three-level SVPWM algorithm is adopted.Aiming at the shortcomings of complex calculation in the implementation of the algorithm,by redividing the space vector sector and optimizing the reference voltage vector synthesis method,the algorithm is equivalent to two-level SVPWM algorithm,and the correctness and feasibility of the optimization algorithm are verified by simulation.Furthermore,the sliding mode observer with good robustness and easy implementation is selected as the sensorless control method.In order to suppress the chattering phenomenon of the sliding mode observer and improve the accuracy of rotor information detection,the sliding mode observer is improved by introducing the sigmoid()function,the back electromotive force observer and the phase lock loop structure to replace the sign()function,the low-pass filter and the arc-tangent function.Finally,on the basis of vector control and optimization of three-level SVPWM algorithm,the simulation model of HSPMSM sensorless control system based on conventional and improved sliding mode observer is built in Maltab/Simulink software.At a given speed of10000r/min,the simulation comparison is carried out to verify the superiority of the improved sliding mode observer.