Analyses of modular windings of a traction motor in a hybrid bus

Abstract

Winding constructions are studied for a traction motor utilized in a hybrid bus. In vehicle applications, acceleration and deceleration require high torque. Thereby high current density is required intermittently while volume is adjusted to minimum. However, mobile converters may have a limited current output. This current amount is usually not enough for heavy drive cycles. Therefore, the authors designed a traction machine, which has two separate windings to be supplied by two separate converters. Therefore, the motors total current may reach higher values. Another important benefit is that the machine can be driven even when one winding or one supply unit is broken. In transportation use this may give the bus driver the possibility to drive to the destination or to a repair workshop. Several separated winding arrangements were designed and simulated with finite element method. A hybrid bus is designed and constructed at Lappeenranta University of Technology and the modular winding motor presented here has been applied in the bus.