| Permanent magnet synchronous motor is widely used in the national military field,all kinds of light industry and heavy industry,life and other corners,PMSM needs to accurately obtain the rotor position and speed to start and run normally,the previous method is to install mechanical position sensor in the motor,but the installation of mechanical sensor has many disadvantages,such as increasing the volume and weight of the whole motor,the motor in many bad places can not work properly.Therefore,people began to study the method of speed estimation without position sensor.The advanced artificial intelligence algorithm can accurately detect the rotor position in the full speed range,but the artificial intelligence has high requirements on equipment,high cost and harsh requirements on the working environment,which is only suitable for a small number of work occasions.However,most of the existing rotor position detection methods are only applicable to a specific speed range,and the error will be larger if it is higher than or lower than this range.In view of the situation of this kind of error detection,this thesis by the method of high frequency voltage injection pulse vibration of motor rotor zero speed detection and sliding mode variable structure control method of motor rotor in high speed detection of two kinds of detection methods as the core,we design a compound control method,the above problems puts forward the optimization method of error,and aiming at the shortcomings of the two methods is put forward their respective optimization improvement strategy to improve the precision of rotor position detection,the main work is as follows:(1)The principle of sensorless control system for pulse-induced high frequency signal injection is introduced.High frequency pulsed voltage signal injected into the rotor reference coordinate system to be estimated will generate the corresponding high frequency current response on the stator side,and the rotor position information of the motor is contained in this current signal,and on that basis,this thesis proposes a method to optimize the traditional pulse high frequency injection method for the case that the multiple use of filter will reduce the signal delay and the bandwidth of the current loop.Adding a modulation signal to the high-frequency current response signal can reduce the use of some filters in traditional methods and simplify theoverall structure of the system,it can be seen from the simulation results that it is compared with the traditional method,under the circumstances of external disturbances such as load addition,load reduction and speed change,the motor response becomes faster,the overshoot amount is smaller,the rotor position detection error and delay become smaller,and the operation fluctuation becomes smaller.(2)The principle of rotor position detection with sliding mode observer is introduced,SMO has a lot of inertia in practice,the switching function ssign)(used in the traditional method will generate relatively large buffeting due to its discontinuity,and the low pass filter will lead to a large number of harmonic errors,propose optimization method,The buffeting phenomenon can be reduced by using smooth ssigmoid)(function instead of ssign)(function,and a large number of harmonics in the system can be filtered by kalman filter.Simulation results show that the optimized method effectively reduces the lag of traditional rotor Angle detection and weakens chattering,thus improving the motor performance.(3)In combination with the above two detection methods,a switching interval is selected for the error detection accuracy of different velocity segments.In this speed interval,the two methods work simultaneously,a weighted switching method is designed to select the weighted mean of velocity according to the detection accuracy.It can switch smoothly between medium speed and zero speed,and finally realizes the accurate detection of the rotor position in the full speed field of the motor. |
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