A Novel Intermittent High-Frequency Square-wave Injection Method Of Ipmsm Sensorless Drive

Interior Permanent Magnet Synchronous Motor(IPMSM)has the advantages of high power density,high efficiency,wide speed range and low noise,which is widely used in many fields such as electric vehicles,wind power generation,and household appliances.Generally,the rotor position and speed information of the motor can be obtained through mechanical sensors to achieve high-performance vector control.However,the installation of position sensors not only increases the cost and connection complexity of the control system,brings inconvenience to some industrial field applications,but also seriously deteriorates the system reliability in the sensors failure.Consequently,sensorless control strategies of IPMSM have been extensively studied.The earlier study mainly focused on the position observer methods based on backEMF.However,studies have shown that the accuracy of the position estimation can be seriously declined at a low-speed or even zero-speed due to the very small back-EMF,which deteriorates the dynamic performance of IPMSM and limits operation speed range.Furthermore,the sensorless control method based on high frequency sinusoidal signal injection guarantees that most permanent magnet synchronous motors can achieve zero speed operation under full torque in transient and steady state.Subsequently,the highfrequency square-wave signal injection was proposed to increase the bandwidth of speed and position control by at least 5 times.However,further research is needed to improve dynamic and steady-state performance and position estimation accuracy.This paper mainly studies the position sensorless strategy based on high-frequency square-wave voltage injection,focusing on analyzing the effect of the dead-time on the position estimation:Firstly,the various sensorless control methods of IPMSM are introduced,and the research status and problems of high-frequency voltage injection are analyzed.In order to carry out the research on high-frequency square-wave voltage injection,this paper analyzes the mathematical model of IPMSM,designs the voltage space vector control system,and performs parameter calculation.Next,the principle of high frequency square-wave injection is analysed.The high frequency and fundamental currents are separated without filter,and a phase-locked loop position tracking observer is designed.The polarity of rotor is identified by the pulse voltage injection.Based on the analysis of the conventional high-frequency square-wave voltage injection,the injected voltage and the induced current ripple is distorted,the position estimation performance is degraded by the dead time of the inverter,and the conventional current separation method cannot accurately separate the high-frequency current and the fundamental current under transient condition,which severely lead to the deterioration of the dynamic control performance.A novel intermittent high-frequency square-wave voltage injection method and a new current separation method are proposed.By the proposed method,the effect of the dead-time can be reduced,and the high frequency and fundamental currents can be separated correctly under transient condition.The amplitude of the high-frequency current response is reduced with the amplitude of the injected voltage unchanged,proving that the proposed method is more efficient.Then the hardware and software of the motor controller is designed,and the performance of the traditional high-frequency square-wave injection method and the intermittent square-wave injection method are compared.The experiment shows that dynamic performance and position estimation performance are significantly improved,...