Energy-Efficient Train Control: A Comparative Study Based on Permanent Magnet Synchronous Motor and Induction Motor

The permanent magnet synchronous motor (PMSM) has recently garnered significant interest due to its high efficiency, lightweight, and low life cycle cost, positioning it as a strong candidate for the next-generation traction system in railway applications. By comparing the widely used induction motor (IM) with the PMSM, this paper integrates the dynamic motor efficiency map, which plays a crucial role in energy saving, into the energy-efficient train control (EETC) problem. The paper adopts auxiliary variables and utilizes data transformation to perform double surface-fitting for highly nonlinear and non-convex dynamic efficiency. This transformation naturally distinguishes the train traction and braking operating states, further enhancing the solution accuracy of the EETC model. Results reveal that the proposed model, while maintaining high computational accuracy, can achieve millisecond-scale computation time, and the results are closer to the actual distribution of train operating points. Based on a real case analysis of Qingdao Metro Line, it was found that replacing the IM with PMSM as a traction motor does not require adjustments to the train operation control strategy, and the PMSM can save at least 1.01 kWh/km, achieving an energy-saving rate of 12.96%.