# I Eddy current losses in microelectric generators?

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1. Jul 17, 2017

### gildomar

For a microscale electric generator (where the driving force is a fraction of a newton), can losses from eddy currents be significant enough to noticeably alter the rotational velocity of the rotor? Because my understanding is that the rotation is basically taken as a constant when examining the behavior of electric generators.

2. Jul 17, 2017

### Staff: Mentor

More details would be helpful. But an initial answer would be that eddy current losses (as a percentage) do not change with the magnitude of the currents, while hysteresis losses do.

3. Jul 17, 2017

### gildomar

For more details, I was considering a very small electric generator with also a very small driving force. I know that obviously an electric current would be induced from the rotation, which in turn would generate a magnetic field that would oppose the motion. When doing calculations involving generators, I've always taken the rotational velocity as a constant (which keeps calculations simple). But I was wondering if the magnetic "friction" from the opposing field would be strong enough to significantly slow down the generator, thus making calculations trickier.

4. Jul 17, 2017

### Staff: Mentor

I think a bigger issue for you would be the losses in the rectification of the output current from your microgenerator. What voltages and currents are you looking at? Can you say more about what the microgenerator looks like? Maybe there is a better way to convert the small input mechanical power to stored electrical energy...

5. Jul 17, 2017

### gildomar

I don't have any info for voltages or currents yet, since it's still a theoretical exercise (but I'm trying to get to the point where I can determine voltages and currents). As such, I'm determining what the generator would look like, particularly since I'm also trying to determine the exact size of the driving force (but that's a separate topic). I can say that I was looking at trying to utilize a brushless arrangement, so as to minimize friction, and thus get every erg that I can from it. Hence why I was wondering about eddy current losses.