Magnetic and Thermal Analysis of Electrically Excited Synchronous Motors for Electric Vehicles

Electrically excited synchronous motors are becoming quite popular as an alternative to permanent magnet machines, thanks to their capability to provide comparable peak torques and optimal field weakening operation. However, their rotor excitation determines higher rotor losses, which are difficult to dissipate. In this work a magnetic and thermal analysis of a classical electrically excited synchronous motor and another one with hybrid excitation is provided, respectively by means of finite element and lumped parameter circuit simulations, illustrating the machine behaviour both in steady state and transient overload conditions. Some possible cooling solutions and approaches are analyzed and discussed.