Research On On-line Estimation Of Stator Temperature Of Permanent Magnet Synchronous Motor For Electric Vehicle

The operating condition of electric vehicle is very complicated,and the heat dissipation condition is limited.With the increase of running time,the temperature of motor rises sharply,it is faced with the risk of failure.The on-line monitoring of motor temperature can provide effective heat protection for motor operation,reduce motor failure rate,guarantee motor running life and enhance reliability of electric drive system of electric vehicle.In this paper,permanent magnet synchronous motor used for electric vehicle is taken as the research object,and various methods of motor temperature estimation have been analyzed.An on-line estimation strategy for stator temperature of permanent magnet synchronous motor based on DC voltage signal injection has been studied.The optimal signal injection strategy is also studied,and simulation and experiment are carried out to verify the above strategy and theoretical analysis.The physical structure of permanent magnet synchronous motor is analyze d in detail,and the mathematic model of the motor is obtained by simplifying and equivalence.At the same time,the classical vector control strategy of permanent magnet synchronous motor and the physical characteristics of the motor are introduced to determine the basic principle of the on-line estimation of motor temperature.On this basis,a new motor temperature estimation strategy based on DC voltage signal injection is proposed,which realizes the stator resistance identification by injecting DC voltage signal into the alpha axis,and realizes the motor real-time temperature estimation with the strict linear relationship between the metal temperature and its resistance.The temperature estimation strategy of permanent magnet synchronous motor based on signal injection needs to weigh the temperature estimation precision and the output torque ripple.In order to accurately identify the stator resistance,ensure the high temperature estimation precision and reduce the negative effect of the signal injection on the motor performance,the influence of the motor parameters,load and motor physical characteristics on the temperature estimation accuracy and output torque ripple are considered.The optimal signal injection strategy is discussed,and the three elements of injected signal are optimized(inject signal size,signal injection duration,and signal injection cycle).The temperature estimation system model of permanent magnet synchronous motor is built under the MATLAB/Simulink environment,the motor temperature estimation strategy and optimization strategy under the typical operation conditions of the electric vehicle is simulated and analyzed,and the system experiment platform is built by DSP.The simulation and experimental results show that the propo sed motor temperature estimation strategy is feasible,can effectively monitor the temperature of the driving motor,and the operation is simple,no additional installation of temperature sensor,no need to change the hardware structure of the motor drive system,has high engineering application value.