Overview

This chapter explores the four classes of electric machines having the most bearing on hybrid propulsion systems: the brushless permanent magnet machine in its surface permanent magnet (SPM) configuration; the interior permanent magnet (IPM) synchronous machine in either inset or buried magnet configuration; the asynchronous or cage rotor induction machine (IM); and the variable reluctance or doubly salient machine (VRM).

There exists a mountain of books, papers and training workshops dedicated to the design and study of these four classes of machines. The purpose of this chapter is to present a design perspective of these electric machines in the context of hybrid vehicle propulsion. This is a topic that is still not as well defined, for example, as the design of industrial electric machines. In this chapter we focus attention on the design characteristics of the four classes of electric machines of most interest for hybrid propulsion. To amplify the reasons for these choices consider the following products now available in the market:

• SPM (Honda Insight and Civic mild hybrids, FCX-V3 FCEV; Mannesman-Sachs ISA)

• IPM (Toyota Prius, Estima and Ford Motor Co. hybrid Escape)

• IM (GM Silverado ISG, Continental ISAD, Delphi-Automotive ISG, Valeo ISA)

• VRM (Dana ISA).

These machines in current use are all of the drum design - that is, rotor flux is radial across a cylindrical airgap, versus axial designs that have a distinct pancake appearance with axial flux across an airgap that separates the disc shaped stator(s) and rotor(s). A plural connotation is used on axial...