Esc Switching Freq?

[Robdog007]

Hi everybody!

What is considered a "high" switching frequency for a tail esc? I have an esc laying around, and was thinking about putting it in my heli to replace my Piccoboard. As soon as I get a gyro, that is.

The esc is an Elictrifly C-5, here is a link:

http://www.electrifly.com/gpmm2000.html



Edit: I just noticed it is for 5-8 cells. I guess that means my Etec pack will fry it?

[pgoelz]

High frequency for the purpose of saving tail motors would be anything over about 50 KHz. Conventional ESCs switch around 2-8 KHz. There aren't very many high frequency ESCs out there....yet. The JMP HF9, the Wes Tek HF100 (which is NOT an HF9) and the Schulze Slim-105he are the only three I am aware of.

[Robdog007]

Ah. So 3KHz would not be considered high. Heck, I wouldn't even consider that low. 3KHz sounds laughable.

Thanks Paul

[Robdog007]

Hmm...what frequency does the Piccoboard use? I have an upgraded tail motor, so would having the better esc be much of a benefit?

[pgoelz]

Next time I put one on the bench I can measure it, but I would guess it is in the 3-6 KHz range by the sound of it. I think the Phoenix switches around 8 KHz. From what I have seen, there are no ESCs that switch higher than about 8 KHz until you get to the high frequency ones I mentioned.

The reason there are not more high frequency ESCs is probably that it is much harder to switch high currents at 100 KHz than it is at 8 KHz. There are issues involved in driving the gate of a FET at those speeds and I think there may also be issues in the drive circuitry, which is usually a PIC chip that has to operate much faster than the switching frequency to interpret the incoming pulse train and develop the appropriate drive pulse.