Got some thoughts as to how these gizmos work that I would like affirmed or corrected.

It is my understanding that the electrical power produced by a PMA is based on a number of factors such as the strength of the magnets, the number of the magnets, the construction of the coils, the distance between the magnets and the coils, temperature and the speed of the relative motion between the magnets and the coils. Have I missed anything?

Another understanding is that the power produced is proportional to the speed of the relative motion between the magnets and the coils. Double the speed and double the power produced. Is this correct?

In the case of a PMA that has its voltage regulated, the regulation is being performed by shunting current within the regulator as needed to maintain a given output voltage. And for a given rotor speed, the amount of shunting varies. That is, if the current to a load is higher then the shunting within the regulator is less, and if the current to a load is less, then the shunting within the regulator is higher. Does this make sense?

Thanks for any and all comments.

 

It is my understanding that the electrical power produced by a PMA is based on a number of factors such as the strength of the magnets, the number of the magnets, the construction of the coils, the distance between the magnets and the coils, temperature and the speed of the relative motion between the magnets and the coils. Have I missed anything?

Looks like you have a good understanding of it.

Another understanding is that the power produced is proportional to the speed of the relative motion between the magnets and the coils. Double the speed and double the power produced. Is this correct?

That may not be totally correct. Double the speed will double the frequency, but might have a four fold increase in voltage. But that - I'm not sure of.

Here's what I see as a potential problem: The type of magnet used, or more so - the polarization of it. If you used magnets out of a microwave oven or out of a speaker, their shape is toroidal and the magnetic field moves through the hole in the middle and around the outside to complete a magnetic circle. Rotating such a magnet between coils may produce very little current. If any. A PROPER magnet will have its poles extending in opposite directions from the rotor shaft. Doughnut magnets don't align with that.

I HAVE seen people use doughnut magnets as a generator but the coils were adjacent to the magnets. And as the doughnuts passed the coils they supposedly generated a voltage. I don't tend to believe everything I see on YouTube. I'll see if I can find a video like what I described. Nope. Couldn't easily find one. Lots of false claims to free energy though.

 

This is an example of a magnet used in a PM (Permanent Magnet) alternator.


The above magnet was a quality control reject. Looking close you can see a few chips on the edges.

Another understanding is that the power produced is proportional to the speed of the relative motion between the magnets and the coils. Double the speed and double the power produced. Is this correct?

That isn't quite true. As Tony points out, in the case of an AC generator the rotational speed determines the frequency.

The frequency of AC produced in a generator is determined by the rotor's speed (RPM) and the number of magnetic poles in the machine, following the formula: Frequency (Hz) = (RPM × Poles) / 120, with faster rotation or more poles increasing the frequency. Essentially, it's how many times the magnetic field sweeps past the coils per second, with each complete sweep (or pair of sweeps for some setups) creating one cycle of AC.

Ron

 

Got some thoughts as to how these gizmos work that I would like affirmed or corrected.

It is my understanding that the electrical power produced by a PMA is based on a number of factors such as the strength of the magnets, the number of the magnets, the construction of the coils, the distance between the magnets and the coils, temperature and the speed of the relative motion between the magnets and the coils. Have I missed anything?

Another understanding is that the power produced is proportional to the speed of the relative motion between the magnets and the coils. Double the speed and double the power produced. Is this correct?

In the case of a PMA that has its voltage regulated, the regulation is being performed by shunting current within the regulator as needed to maintain a given output voltage. And for a given rotor speed, the amount of shunting varies. That is, if the current to a load is higher then the shunting within the regulator is less, and if the current to a load is less, then the shunting within the regulator is higher. Does this make sense?

Thanks for any and all comments.

A PMA can be modeled as an AC sinewave source in series with an inductor. As RPMs increase, frequency and open-circuit voltage go up together. At high frequencies, it approaches a constant-current source, which is why they are usually regulated by shorting.

 

Thanks for the replies.

A core question is, as a load is added or subtracted to the circuit, what effect does it have on the regulator?

My thinking is the regulator will be heating up less with a greater load since the regulator will not have to be shunting as much current in order to keep the voltage in check. Whereas with a light load the regulator may be shunting more current to maintain the voltage. And with more shunting I would think the regulator would be running at a higher temperature.

 

Yes, with a PM alternator, power is proportional to speed, but the series reactance of the coils mean that the available current does not double when the speed doubles. I have wanted to replace the field coil in a MOPAR alternator with a big ceramic speaker magnet and spin it with a windmill. Getting the coil out and the magnet in is the challenge. It takes special tools.
It is also possible to add a rectifier and switching regulator and have a motorcycle that will not burn out the lights when the zener connection fails at night. But it is not super-simple to do.

 

Yes, with a PM alternator, power is proportional to speed, but the series reactance of the coils mean that the available current does not double when the speed doubles. I have wanted to replace the field coil in a MOPAR alternator with a big ceramic speaker magnet and spin it with a windmill. Getting the coil out and the magnet in is the challenge. It takes special tools.
It is also possible to add a rectifier and switching regulator and have a motorcycle that will not burn out the lights when the zener connection fails at night. But it is not super-simple to do.

Rotors are made with permanent magnets that can replace a field coil rotor. Not sure if they make one for a MOPAR alternator however.

https://windandsolar.com/products/b...OBRB-WlOWRJ_7r1v93Ygo0TiA7-E_MxBwEemrf8vYbDsX

https://www.ebay.com/itm/332495413215

 

Adding a voltage regulator to the motorcycle was a good way to solve a big problem for a segment of the "Biker Community." Probably it could have spun off to a whole business for me, but I was not interested in a startup at the time.
The addition does require changing a bit of wiring on that British Bike. It was not a simple "Bolt On" modification.