Field Weakening Operation Control Strategies of Permanent Magnet Synchronous Motor for Railway Vehicles

The interior permanent magnet synchronous motor (IPMSM) can make use of the magnetoresistive effect to improve its efficiency and speed characteristics,so that it is suited to railway vehicle. The field weakening control strategy of interior permanent magnet synchronous motor for railway vehicle was studied in the paper. A novel method of modifying the current reference and field weaking based on gradient descent of voltage limit according to the ellipse were proposed. The method consists of two parts,one is the determination of the field weakening region,another is the current reference modification. The field weakening region was determined by the angle between the constant torque direction and the voltage limited ellipse decreasing direction. The direction of voltage limited ellipse decreasing was calculated by using the gradient descent method. The current reference was modified by the field weakening direction and the magnitude of the voltage error according to the field weakening region. The simulink model was founded by Matlab and the experiment platform of the 100 kW IPMSM field weakening control system was implemented using a TMS320LF2407A DSP. The validity of the proposed strategy was proved by the simulation and experimental results.