Research On Position Sensorless Control Strategy Of IPMSM Based On Full-order Sliding Mode Observer

Permanent Magnet Synchronous Motor has the advantages of high power density,small size and high efficiency.So it has been widely used in electrical transmission devices,such as numerical control machine tools,mine Motor equipment and new energy vehicles.The position and speed information on the rotor are needed in the permanent magnet synchronous motor control system to realize the high-performance control of the motor.The traditional method is to obtain rotor information by installing a position sensor on the motor shaft,but it will increase the size of the motor and the cost of the system,and reduce the stability of the system.Therefore,the research of permanent magnet synchronous motor without position sensor is the focus on current research.In this paper,the position sensorless control based on the full-order sliding mode observer is studied.The introduction to the full-order sliding mode observer effectively improves the accuracy of observation.At the same time,the influence of the changes of harmonic current and electrical parameters on the accuracy of observation is analyzed from Suppression of harmonic current and online parameter identification to improve the accuracy of observation and control performance.First,this article analyzes the principle and structure of permanent magnet synchronous motors.According to the principle of coordinating transformation,the mathematical model of the electric motor in each coordinates system is derived.According to the mathematical model of permanent magnet synchronous motor,several commonly used PMSM vector control strategies are analyzed.Aiming at the situation that the sliding mode observer cannot operate in the low-speed phase,the open-loop startup strategy is analyzed,and the principle of the IF open-loop startup is analyzed.Secondly,the traditional sliding mode observer is theoretically derived,and the problems of sliding mode chattering,the use of low-pass filters and the poor anti-disturbance ability of the observation angle during the operation of the traditional sliding mode are analyzed.Aiming at the problems of traditional sliding mode observers,this paper first establishes a full-order sliding mode observer to eliminate system chattering and solve the problem of using low-pass filters.At the same time,to further suppresses sliding mode chattering,the arctangent function is used instead of the traditional Switch function,and feed back the observed extended back EMF to the sliding mode current observer to improve the accuracy of the observation,and then use a phase-locked loop to extract the rotor position information in the back EMF,and add a link to eliminate the rotation factor to solve The influence of rotation speed on angle extraction further improves the accuracy of observation.Finally,the effectiveness of the scheme is verified by simulation.Thirdly,A variable frequency drive system with TMS320F28335 as the processor is built,and the corresponding hardware circuit and software design are given.In terms of hardware circuit protection design,in order to detect the occurrence of IGBT over-current in time,a timely and effective over-current detection circuit is designed according to the principle that the voltage drop of the IGBT increases as the current increases.At the same time,in terms of peak voltage,by adding a pre-circuit on the basis of the active clamp circuit,the generation of the peak voltage can be effectively suppressed,thereby protecting the IGBT.At the same time,the suppression of harmonic current and online parameter identification are studied in the software design.Finally,a series of experiments such as harmonic current suppression,IF current-to-frequency ratio control,and comparative analysis between traditional sliding mode observers and full-order sliding mode observers in this article are carried out on the platform built,which verifies the effectiveness of the proposed scheme in this article.And the stability of the platform built.