Research On Position Sensorless Control Strategy Of IPMSM Based On Adaptive High Frequency Injection Amplitude

With the continuous development of permanent magnet materials and the progress of control technology,permanent magnet synchronous motors have been widely used in all walks of life.Embedded permanent magnet synchronous motors have the advantages of high power density and good field weakening performance.Many applications are in the field of high-performance servo drives.At present,in the traditional vector control strategy of permanent magnet synchronous motor,the use of Hall,resolver and other position sensors to obtain angle information not only increases the cost of materials and manufacturing,but also has factors such as poor connection and electromagnetic interference in terms of reliability.The position sensor has become one of the main fault sources in the control system.When the motor speed is high,the model-based method obtains the rotor position by observing the motor back electromotive force.This method is relatively mature.When the motor is in the zero-low speed state,the back EMF is small and difficult to observe.The high-frequency injection method uses the saliency of the rotor to estimate the position,but the accuracy and stability of the position estimation need to be improved.This article will mainly study the influence of the embedded type The factor of the rotor position estimation accuracy of the permanent magnet synchronous motor under the high-frequency injection method,and the strategy that can improve the position accuracy is proposed.Firstly,introduce the position sensorless control strategy based on different operating states of permanent magnet synchronous motors.For the zero-low-speed operating state,the principles of different high-frequency injection methods are introduced in detail,and the problems to be solved in the current high-frequency injection are analyzed.In order to carry out the research on the low accuracy of position estimation under high frequency injection of permanent magnet synchronous motors,by establishing mathematical models of permanent magnet synchronous motors in different coordinate systems,the vector control strategy is studied,and the theory is provided for the high frequency injection sensorless vector control strategy.Based on the traditional embedded high frequency square wave into the sensorless permanent magnet synchronous motor control model,in view of the traditional filter,is adopted to realize separation due to the current delay problems,no filter method to extract the fundamental frequency and high frequency current,position tracking observer design based on phase-locked loop,to extract the rotor position estimation.The influence of different factors on the estimated position of the rotor under high frequency injection in the nonlinear inverters is deeply studied.According to the different phase current amplitude and polarity,the influence of dead zone,parasitic capacitance and pipe voltage drop on the output voltage is analyzed in combination with the power tube state,and the voltage error equation is established.Then,analyze the output voltage distortion under different dead zone types,and study the dead zone types that have less influence on the estimated position of the rotor.An improved high-frequency square wave injection method is proposed to reduce the high-frequency response current distortion caused by the dead zone during the entire injection cycle.An improved high-frequency square wave voltage amplitude adaptive method is proposed to reduce the high-frequency voltage distortion caused by the dead zone at different carrier stages,optimize the fundamental frequency and high-frequency current separation strategy,and reduce the high-frequency current distortion to improve the rotor Estimate the position accuracy.Then,the hardware circuit is designed,the software function is analyzed,and the experimental platform based on the vector control of embedded permanent magnet synchronous motor is built.The current waveform obtained from the experiment under the traditional high frequency square wave injection is analyzed to verify the rationality of the influence of the inverter nonlinearity on the current under the theoretical analysis.By comparing the estimated positions of the traditional positionless control system under high frequency square wave injection and the improved positionless control system under high frequency square wave injection,the feasibility of the improved high frequency square wave voltage injection amplitude adaptive method is proved.Finally,this paper summarizes and looks forward to the full text,points out the direction of further research and problems to be solved,and provides research ideas and theoretical reference for improving the accuracy of position estimation based on high frequency injection sensorless control and promoting the performance of position less control strategy.