Field weakening operation control of permanent magnet synchronous motor for railway vehicles based on maximum electromagnetic torque at full speed

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. To solve electromagnetic torque output insufficient of IPMSM using the traditional field weakening control method, 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 weakening based on the maximum electromagnetic torque at full speed (whether in the base rate areas or in the field weakening region) were proposed. The method consists of two parts, one is the determination of the field weakening region, and another is the current reference modification. The field weakening region was determined. The reference current vector and the maximum electromagnetic torque expression were obtained by solving the voltage limit equations and the current limit equations in the field weakening region I; the reference current vector was obtained by solving the voltage limit equations and the electromagnetic torque equations in the field weakening region II. 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 TMS320LF2407ADSP. The validity of the proposed strategy was proved by the simulation and experimental results.