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Stormclad

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## Homework Statement

I want to know the affect of stator design on bicycle dynamo performance using magnetic circuits, and power output. The bicycle dynamo is a single phase AC generator with permanent magnets on its rotor (mounted on hubshell) and a lundell type armature(mounted on bike axle). At 30rpm, the dynamo is expected give out 2.4W at 3V. Load is 15ohm.

## Homework Equations

I've tried using Faraday' law, Voltage generated=-N(change in flux & area)over time, but I keep getting larger results than expected.

My attempt at applying:

Faraday's Law:

Total B of the magnet is: 4000mT, so for this voltage estimation I am assuming perfect coupling of field through the stators

The coil has a cross area of 483.05mm^2 and 320 turns.

There are 28 poles, so I assume the coil experiences a field change 14 times per second at 30rpm.

So Voltage generated = -(320)(4000mT)(483.05mm^2*14) = 8.65V

How do you factor in the 15 ohm load into the basic equation?

## The Attempt at a Solution

Aside from the attempt in the previous section, I'm stuck. Would appreciate links or recommendations of reference if some reading is in order.

Thank you,

Derek

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