Comparative analysis of performance and energy losses in light railways vehicles equipped with IM or PMSM drive

With reference to light railways transportation systems, in the paper a comparison is carried out between vehicles equipped with either Induction Motor Drive or Permanent Magnet Brushless Motor Drive. The attention is particularly focused on energetic performance, in term of losses and efficiency. The main characteristics of the traction units of the two compared vehicles have been chosen in accordance with the real constraints, usually imposed or suggested by the motor type, which influences mechanical and electrical configurations, control architectures and techniques. Thus, the analysis has not the aim to compare specific devices, which are different for the two considered cases, but the whole traction units, each one with its own proper characteristics. Based on both assigned characteristic of the railways sections and vehicle mission, an extensive numerical analysis has been carried out in various operating conditions, with the aim to comparatively evaluate either fast dynamic performance, in response to the PWM modulation, or slow dynamic performance, concerning the time constant of mechanical quantities, or losses and energy efficiency.