Research On Sensorless Control Technology Of PMSM For Electric Vehicles

The emergence of new permanent magnetic mateirals greatly accelerated the develop?ment of the Permanent Magnet Synchronous Motor (PMSM). Owing to high power densityand high operation eiffciency, PMSM has been widely used in Electric Vehicle (EV). Vectorcontrol method is the most mature and reliable technology of permanent magnet motorcontrol method, but its high-performance control requires accurate rotor position to completethe closed-loop control. In conventional motion control systems, optical encoders or rotarytransformer are used for this purpose. However, these additional sensors increase the costs ofthe system and reduce the reliability. To overcome these shortcomings, sensorless controltechniques have been proposed and are becoming one of the popular research directions of themotor control.The mathematical model of the permanent magnet synchronous motor is built ifrstly，thetheory of vector control on permanent magnet synchronous motor is studied tfirther deeply,angle and speed phase-locked loop are designed. Aiming at the shotrcomings of conventionalSPWM? the space-voltage vector pulse width modulation (SVPWM) is proposed in thisdissertation. The SVPWM can help the inverter to decrease the current harmonic componentand restrain the torque irpples, the DC bus voltage utilization can be improved and the speedrange of the system can be expanded.Secondly, the thesis emphasizes the illustration of the pirnciple of the parallel EKF andits application in the system, deduces the EKF equations of PMSM in the static coordinatesystem, and the control diagram is provided.The simulation model of the vector control system of PMSM based on the EKF andSVPWM is established and the application of the sensorless in motor control is successfullyrealized. The simulation results demonstrate the validity and rationality of the parallel EKFalgorithm in the motor control.The hardware part of the sensorless vector control system is built on Expert3. TheSotfware Design is realized based on PE-View9integrated development environment. Thecontrol sotfware is being programmed with C. The flow charts of main program, functionsub-modules program and PWM interrupt service routine are given. The program has donedebugged largely based on the hardware platform to reduce torque irpples and improve staticand dynamic performance. The expeirmental results verify the correctness and feasibility ofthe theory and design. The whole system can satisfy the demand of dirver design.