An engineer's diary

[No. 96] Machine Design Parameters and their Ordering

How many parameters are needed to determine the dimensions of an electric machine?

[No. 95] Actuator agony

Electromagnetic actuators (solenoids, relays, torque motors, etc.) comprise an important class of electromagnetic devices with a wide range of applications.

[No. 94] The Axial-flux Machine and Faraday’s Law

Sometimes I get a request to have a look at a disused electric machine in an old factory or even in a barn. Often the question is ‘does it work?’, or ‘can we make it run on single…

[No. 93] Equivalent circuits and the finite-element method

We are sometimes told that there are two theories of electric machines: the field theory and the circuit theory.

[No. 92] The Phasor Diagram and the Finite-element Method

The phasor diagram is fundamental in the theory and calculation of the steady-state operation of the synchronous machine (including both wound-field and permanent-magnet types).

[No. 91] Synchronous machine operating characteristics

The wound-field synchronous machine was one of the first electric machines to benefit from the development of numerical field-analysis techniques in the 1960s.

[No. 90] Did Potier solve the problem of calculating saturation in synchronous machines?

The work of Alfred Potier (1840-1905) belongs securely in the foundations of the theory of the wound-field synchronous machine.

[No. 89] Cognitive Science and Engineering Analysis — Ideas from an Unexpected Source

There is a curious parallel between a live musical performance and a large engineering computation involving Big Data (Engineer’s Diary No. 87).

[No. 88] The Case for Minimal Data

I asked my grandson the price of a postage stamp in binary, and pretty quickly he reported the result, 10100101 (pennies). And how many bytes is that? One byte.

[No. 87] The Case for Big Data

What is Big Data, and why do we need it? Let’s try to answer this question with very little specialist knowledge of numerical analysis software. Big Data refers to a computing env…

[No. 86] Sanity check

There is an old story about the engineer who was asked to multiply 4 × 3, who took out a slide-rule, and who declared the result to be “about 12”. While this is a cruel caricature…

[No. 85] Machines with Carbon Brushes

I can already hear a certain reaction to the idea of machines with carbon brushes: ‘We got rid of those many years ago’ . That is true in many industries. It is even true that man…

[No. 84] How to generate a sinusoidal EMF

In a practical rotating electric machine it is not possible to generate a perfect sinewave EMF waveform of the form sin ωt. We are, however, concerned with sinusoidal waveforms, i…

[No. 83] Steady-state short-circuit operation of a PM brushless machine

One of the most important test conditions for a brushless permanent-magnet machine is the steady-state short-circuit condition, sometimes called the ‘sustained’ short-circuit.

[No. 82] Electromagnetic nutcracker

Powersys has just announced a seminar on the use of JMAG ‘to simulate, optimize, and co simulate the most critical small components: frameless motors, actuators, encoders, and bey…

[No. 81] Flummoxed by Flux-Waves?

Electric machine engineers often speak of the flux wave in the air-gap of an electric machine, yet when we look at a flux-plot such as Fig. 1 we cannot see it.