The book chapter shows that it is rare for soft magnetic materials in a.c. applications to be subject to perfectly sinusoidal flux-density waveforms. The designers and users of electrical machines are placing increasing demands on the magnetic cores. Traditionally, the electrical steels used in these devices are characterised under standard conditions with power frequency sinusoidal magnetisation requiring designers to over-engineer the magnetic components based on previous experience. It is common knowledge that many applications of electrical steels exhibit flux density waveforms which are far removed from the sinusoidal ideal. Even for conventional, sinusoidally excited, devices such as induction motors, the flux density waveforms vary from close to sinusoidal to highly distorted and, behind the teeth, rotational flux conditions.

Chapter Contents:

• 7.1 Introduction
• 7.2 Power electronic converters
• 7.2.1 Square wave inverter
• 7.2.2 PWM inverter
• 7.2.3 Matrix converters
• 7.2.4 Space vector modulation
• 7.3 Losses under distorted waveforms
• 7.4 Loss models under distorted magnetisation waveforms
• 7.5 Influence of distorted waveforms on material properties
• 7.6 Measurement and testing under non-sinusoidal magnetisation
• References

Inspec keywords: magnetisation; magnetic cores; magnetic flux; silicon alloys; soft magnetic materials; iron alloys; ferromagnetic materials; induction motors

Other keywords: power frequency sinusoidal magnetisation; soft magnetic materials; nonsinusoidal magnetisation; magnetic cores; flux density waveforms; rotational flux conditions; electrical machines; FeSi; electrical steels; induction motors

Subjects: Asynchronous machines; Magnetization curves, hysteresis, Barkhausen and related effects; Ferromagnetism of Fe and its alloys; Ferromagnetic materials; Magnetic cores