Английская Википедия:Goodness factor
Материал из Онлайн справочника
Шаблон:Short description The goodness factor is a metric developed by Eric Laithwaite to determine the 'goodness' of an electric motor.[1][2] Using it he was able to develop efficient magnetic levitation induction motors.[3]
- <math>G = \frac {\omega} {\mathrm{resistance} \times \mathrm{reluctance}} = \frac {\omega \mu \sigma A_\mathrm{m} A_\mathrm{e}} {l_\mathrm{m} l_\mathrm{e}}</math>
where
- Шаблон:Math is the goodness factor (factors above 1 are likely to be efficient)
- Шаблон:Math, Шаблон:Math are the cross sections of the magnetic and electric circuit
- Шаблон:Math, Шаблон:Math are the lengths of the magnetic and electric circuits
- Шаблон:Math is the permeability of the core
- Шаблон:Math is the angular frequency the motor is driven at
- Шаблон:Math is the conductivity of the conductor
From this he showed that the most efficient motors are likely to be relatively large. However, the equation only directly relates to non-permanent magnet motors.
Laithwaite showed that for a simple induction motor this gave:
- <math>G \propto \frac {\omega \mu_0 p^2} {\rho_\mathrm{r} g}</math>
where Шаблон:Math is the pole pitch arc length, Шаблон:Math is the surface resistivity of the rotor and Шаблон:Math is the air gap.
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