Design And Analysis Of The Rotor Speed Self-sensing For Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor(PMSM) has the technical features of simple structure, high power density and high efficiency. It has been widely used in a variety of the high-performance AC motor control and drive system which constituted by PMSM. It is inseparable from accurate rotor speed detection device. But the rotor speed detection sensor system not only increases the difficulty of installation, increases the cost of the system, either reduces the reliability of the motor control system. A new structure of the rotor speed self-sensing for PMSM can be a good solution to these problems. This paper design a new structure of the rotor speed self-sensing for PMSM. And correctness of the design has been proved through finite element simulation and experimental verification.Firstly, the development and research status of PMSM are briefly introduced, the research on speed detection and rotor initial position identification methods of PMSM, the basic structure of PMSM, the mathematical model, the working principle and speed detection principle for PMSM are detailed introducedSecondly, a new structure of the rotor speed self-sensing for PMSM by setting detection windings in the stator tooth is proposed, the rotor speed can be obtained by detecting the cycle time or frequency of rotor tooth harmonic electromotive force in the detection winding, which combines the structures of speed sensor and motor. Using the magnetic circuit method to complete with the design of a 15 k W PMSM and set detection windings in the stator tooth of the PMSM through Maxwell 2D, then calculate the parameter, operating characteristics to prove that the motor design is reasonable.Thirdly, flux line distribution and air gap density distribution of the motor are obtained through Ansoft maxwell 2D finite element analysis. Also a comparative analysis of the different rotor slots are made to obtain better detection performance, such an air gap flux density and teeth harmonic content. Then, the motor speed simulation analysis method in steady-state operation and dynamic process, the results both indicate that the rotor speed self-sensing method for PMSM is validity and accuracy. Meanwhile, motor rotation direction can be obtained simply and effectively.Finally, rotor initial position detection for PMSM based on single-phase signal injection method and the principle of polarity discrimination are introduced in detail. The results show the validity and accuracy of the rotor initial position detection of single-phase signal injection method for PMSM through finite element simulation and experimental verification.