| PMSM are proverbially applied to rail transit,ship drive systems and new energy vehicles.The operating conditions and application conditions of electric motors are becoming more and more demanding.When the internal temperature of the motor reaches its maximum rated operating temperature,it will accelerate the aging of the outer insulation of the copper wire winding,that will affect that normal operation and service life of PMSM.Therefore,The purpose is to ameliorate the service life of PMSM,reduce its failure due to excessive temperature,real-time monitoring of the motor temperature is necessary.For this paper,the stator winding temperature estimation strategy of PMSM with signal injection in αβ coordinate system is studied.The signal injection method is analyzed in detail from the aspects of signal injection method,magnetic saturation,torque ripple,loss and temperature estimation.The influence of motor performance is put forward,and the optimization strategy of signal injection method is proposed.At the same time,a real-time signal sampling processing model is designed.Finally,it is verified by simulation and experiment.Firstly,the mathematical model of PMSM is established by analyzing the structure and characteristics of permanent magnet synchronous motor.The field oriented control of permanent magnet synchronous motor is analyzed.The signal injection strategy and implementation block diagram of stator winding temperature estimation of permanent magnet synchronous motor are introduced..Secondly,two kinds of signal injection methods of injecting DC voltage in the α-axis and injecting AC current in the d-axis are compared.According to the analysis results,the influence of DC voltage injection on the performance of the motor is analyzed.1)The variation of the total magnetic flux of the motor in the case of signal injection and no signal injection is analyzed.The extraction formula of the stator voltage and current DC component is re-derived considering the magnetic saturation of the motor.The result proves that even considering the magnetic saturation,the stator The resistance estimation results will not be affected.2)The motor torque ripple ratio is proposed,and the torque ripple of the motor under signal injection is theoretically derived.The relationship between torque ripple ratio and torque ripple is obtained.3)The additional copper consumption ratio is proposed.The loss generated by the motor under signal injection is analyzed and deduced.The analysis shows that the additional copper consumption accounts for less than one percent of the normal copper consumption of the motor.Core loss is negligible.4)The factors affecting the motor temperature estimation are analyzed.The error of the stator temperature estimation is theoretically deduced.At the same time,the experimental scheme of stator temperature estimation is briefly introduced.Then,a signal injection optimization strategy for stator winding temperature estimation of motor is proposed.1)The DC current ratio is proposed,and the optimization of signal injection size is theoretically deduced.When the DC current ratio is 5%,the motor torque ripple and resistance identification error are the smallest,and the optimized signal injection amplitude can be obtained.2)By studying the characteristics of the low-pass filter,the dynamic response time is considered to meet the required signal injection duration.3)Considering the cooling and cooling mechanism of the motor,the torque ripple of the motor and the sampling and processing frequency of the motor,the signal injection time interval is comprehensively designed,and an implementation scheme for determining the signal injection time interval is obtained.4)A real-time signal sampling processing model composed of notch filter and low-pass filter is proposed,which reduces the extraction error of DC component and mathematically models the model.Finally,the simulation research was carried out by MATLAB/Simulink,and the experimental platform of motor winding temperature estimation was built.The software design was carried out.The experimental results were verified by the signal injection optimization algorithm based on signal injection.The signal injection optimization strategy was proved to be effective. |
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