Axial Flux PMG Testing for 100W Wind Turbine - William

[W R-P]

Hey everyone.
I've been working on a axial flux permanent magnet DC generator to use on a 100W wind turbine(small I know), to charge 12v batteries in low wind speed areas. Now that it's complete, I'd like to determine the full power curve at different rpms.
So far I've been running it on NO LOAD,using a lathe machine as a prime mover. My results from this were the open circuit voltage and the short circuit current at various rpms- up to about 500rpm. i doubt multiplying the two readings will give me a TRUE value of the power I should expect.
I then tried using a dc bulb as a load, but the only available ones are 9w at 12vdc. If my voltage goes way above 12..it will blow,so that test won't go on for long. No power transducer available either..
My question is is there any simple experiment I can carry out to determine the power output, and what kind of load should i use?

some helpful data
STATOR
1.4mm wire
80 turns
6 coils
star connection, passed on to two block rectifiers
Any input would be appreciated.
William

 

[Achy47]

Hello William,

Congratulations on completing your axial flux permanent magnet DC generator! It sounds like you have already made some great progress in determining the open circuit voltage and short circuit current at various rpms. However, as you mentioned, simply multiplying these two values will not give you an accurate estimation of the power output.

One simple experiment you can carry out to determine the power output is to use a variable resistor as a load. This will allow you to adjust the resistance and measure the corresponding voltage and current. By plotting these values on a graph and calculating the power using the equation P = VI, you can determine the power output at different rpms.

Another option is to use a dynamometer, which is a device used to measure torque and rotational speed. By measuring the torque and rpm of your generator, you can calculate the mechanical power output using the equation P = 2πNT, where N is the rotational speed and T is the torque. From there, you can use the efficiency of your generator (which can be determined through calibration tests) to estimate the electrical power output.

In terms of the type of load to use, it would be best to use a resistive load such as a heating element or a variable resistor. This will provide a consistent and predictable load for your generator. It is important to make sure that the load can handle the voltage and current levels of your generator to prevent damage.

I hope this helps and good luck with your experiments! Don't hesitate to reach out if you have any further questions or need more guidance.