Originally posted by Ted Ewert
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I think the relevant things are as follows
1) The type of core material, which will cause the flux to switch at faster or slower rates. Slowing the switching of the flux should make it easier to see the output from the permanent magnets.
2) The speed of the ramp up and ramp down of the switch to our power coil. I suspect this should be at least as fast as our permanent magnet switching.
3) The frequency of the pulse needs to be as fast as the switching of the permanent magnets, or we will only see point 4. Points 1, 2 and 3 will have to be matched.
4) Transformer actions between our power coil and output coil. If our input is too great or too slow it will mask the effects of the magnets. The voltage we apply should not cause a greater voltage via transformer actions in the output than the permanent magnet flux, or we will only be seeing the voltage and current of the transformer action.
These four points were what I noticed on a motor I was working on. My input coils were too high an inductance so my ramp up and ramp down were too slow and/or my laminated iron core was too fast. The high inductance meant that I was having to use too high a voltage to see electrical output from the magnets.
The motor (a universal type) required at least 40v pulsed DC at 50% duty cycle to make it turn when no permanent magnets were connected. I used 1 field coil and the armature as the input and 1 field coil as the output. when I placed a magnet in parallel and the motor turned faster and I was able to use a lower voltage input.
This only proved that the permanent magnet flux assisted the motor and that the electrical output from the permanent magnets were being masked. Using digital meters I was not able to get good readings as the meter was giving strange readings. This often happens when you have a lot of transient type spikes as you get with an uncompensated universal motor. My scope wasn't a lot of help either as the transients from the brushes were hiding everything.
Placing Christmas tree light bulbs on the output coil was my best measurement as it takes real power to light them (very topical although this was done about 5 years ago). With the Permanent magnets in place the bulbs lit brighter so I was getting more output but how much I cannot say with any accuracy.
My conclusion is that real power can be gained from parallel path but it isnt just a case of placing magnets in a parallel circuit, everything needs to be matched.
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