Research On Position Sensorless Control Of IPMSM Based On Improved High Frequency Square Wave Injection Methods

Interior Permanent Magnet Synchronous Motor(IPMSM)is widely used in the field of high performance motor servo because of its good weak magnetism and strong convex polarity.The combination of position sensorless control and IPMSM in motor control has became a hot topic with lower system cost and higher reliability.It is important to study the high performance IPMSM sensorless control system with high control accuracy,wider operating range and higher speed regulation performance.Most of the motors used high frequency signal injection method based on motor convex polarity during zero-low speed operation.Among them,issues such as improving the position estimation accuracy and extending the operating range become key issues that need to be studied in depth.In this paper,the problems of position observation accuracy and extended operating range of high frequency square wave injection IPMSM sensorless control at zero-low speed are investigated and effective improvement solutions are proposed.The paper firstly introduces the permanent magnet synchronous motor and establishes the mathematical model of IPMSM.The theory of coordinate transformation,convex pole effect and space vector pulse width modulation is studied in depth,and a simulation model is built and analysed to verify the dynamic response and robustness of the system,laying the foundation for the following high frequency injection sensorless control.Then the principles of different high frequency injection methods are introduced,the filterless method is proposed for the phase delay problem of the filter,the crosssaturation effect is analysed for the problem of affecting the rotor estimation accuracy,the failure of the conventional position observer when the motor is reversed and the rotor position deviation when the motor is accelerated and decelerated are analysed,the initial position detection is added to the high frequency square wave injection method for practicality,and the filterless method with initial position detection A simulation of the high-frequency square wave injection method without current demodulation is carried out to verify its good estimation accuracy and dynamic response performance at zero and low speeds.Based on the previous paper,the cross-saturation effect is further investigated and a mathematical model is derived that will take the crosssaturation effect into account,and a method to compensate for the cross-coupling angle error is proposed and simulated to show that the position estimation accuracy is effectively improved.Further,a tangent-locked-loop based position observer is proposed to solve the motor reversal failure problem,and a normalisation method and compensation link are proposed to solve the tangent-locked-loop estimation accuracy problem in the motor variable acceleration/deceleration state and validated by simulation.Finally,the above points are combined with the high-frequency square wave injection method and simulated to verify the dynamic and steady-state performance of the system and the accuracy of the estimated rotor position.Simulation and experimental results show that this solution effectively improves the accuracy of rotor position information estimation,has good rotor position tracking capability,extends the operating range,and achieves the performance requirements of no position steadystate error in forward and reverse rotation and accurate rotor position tracking in the zero-low speed range of the motor.The above theoretical study is validated on a Matlab simulation platform and a hardware platform based on the TMS320F28335 main control chip.