Hybrid Excitation Synchronous Machines: Energy-Efficient Solution for Vehicles Propulsion

In this paper, the suitability of a class of electric machines for vehicle traction applications is discussed. These machines, which are known as hybrid excitation synchronous machines, combine permanent-magnet (PM) excitation with wound field excitation. The goal behind the principle of hybrid excitation is to combine the advantages of PM excited machines and wound field synchronous machines. It is shown that these machines have good flux weakening capability compared with PM machines, and that they constitute an energy-efficient solution for vehicle propulsion.

I. Introduction

Autonomy is a key issue in the development of electric vehicles. The major problem of electric traction is the electric energy source, which is often a battery. Batteries suffer from limited energy storage capacity to mass ratio, which limits the autonomy of electric vehicles and pushes industrialists to find other solutions such as fuel-cell electric vehicles or hybrid electric vehicles. Energy management is the key problem of electric vehicles. Therefore, the efficiency of each component of the traction chain should be optimized. In [1], Biais and Langry show that improving the efficiency of traction motors in the most frequently used operating zones by a few points can significantly increase vehicle range.