Overview

Power electronics and its control fall within what is known as 'inner-loop' control of the hybrid ac drive system. Starting with solid state, or brushless, commutators, for permanent magnet electric machines in the 1970s the techniques of solid state motor control have been applied to industrial induction machines in the form of adjustable speed drives (nearly 90% of all electric machines produced and sold are induction machines) and recently to interior permanent magnet and reluctance machines for hybrid propulsion. Without the advancements and miniaturization efforts of the semiconductor community, the hybrid vehicle would not be market ready.

As the highest cost component of the hybrid propulsion system, with the possible exception of the vehicle battery, the power electronics represents one of the most complex power processing elements in the vehicle. In this chapter the various types of semiconductor devices are summarised along with their applicability for use as in-vehicle power control. The assessment of power electronics for ac drive systems then continues with discussion of various modulation techniques, thermal design and reliability considerations. Modulation techniques are important for many reasons. Most of the present modulation methods are capable of synthesising a clean sinusoidal ac waveform from the vehicle's on-board energy storage system but not all do so with equal efficiency, noise emissions or dc voltage utilisation.

Integration of power electronics systems today is at the stage where a single integrated power module consisting of a full active bridge of power semiconductors, integrated gate drivers, and fault detection and reporting...