Timing and PWM Question

Started by Bobmic, November 17, 2013, 04:12:34 PM

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Bobmic

I've seen these questions and related information in quite a few places but I am still not completely clear about a few things.
I was testing my rimfire 1.20 and even though I did not hook up the Eagle Tree to have a complete data set I changed the timing from 12 to 30deg and the PWM frequency from 12 to 16kHz. The current consumption increased by about 10%. Since I have not measured the rpm I don't know the the output power also increased by the same amount. The motor seemed to be working fine in both settings and if I remember correctly I read somewhere that the efficiency drops and higher trimming and I should keep it as low as possible before the motor looses timing. I would be really nice to have some information from Rimfire but I couldn't find any.

Obviously I would like to get the maximum power out if the prop, motor and battery I am using.
Any suggestions?
Thank you
Bobby

pmackenzie

PWM only affects part throttle operation. Higher PWM = more heat in the motor, less in the ESC. But only at part throttle.
Once you are at full power there is no chopping, so PWM frequency has no effect.

Timing will affect full power and also the ability to accelerate. Too low and some ESCs will lose sync and make screeching/rattling noises.

Pat MacKenzie

Bobmic

Thanks Pat,
So first how do I find the sweet point for PWM?
Second should I keep the trimming as high as possible?

Ededge2002

Although I'm famous for trying to get the most out of a system sometimes less is more!

Remember absolute power is at the cost of efficiency and flight time.
Yea 400W/lb should about do it.. But wouldn't a nice round 500 be better?