PWM rate

[keithbradley]

I came across this formula for determining the best PWM rate to run on escs...thought I would share:

Motor Kv x Motor Pole Count x Nominal volts used / 20

[m4a1usr]

Is that formula; Motor Kv x Motor poles x pack voltage divided by 20? Didnt work out right for a Castle 1515/1Y.

2200 x 4 x 14.8 volts divided by 20= 6512 or
2200 x 4 x 4S divided by 20= 1760?

Must be my math.

John

[GP73]

If I understand correctly, your math is right, the PWM in the first case is 6512Hz or approx 6KHz.

[m4a1usr]

If I understand correctly, you math is right, the PWM in the first case is 6512Hz or approx 6Khz.

But it doesnt work out for some ESC. A Castle Hydra 240 ESC needs 12khz PWM for the CC/Neu 1515. And a Schulze 40.160 ESC likes the 9 to 19khz setting for a 4 pole motor. Neu motors recommends 11 to 13 khz on their motors. Something isnt right. Either its my math or its the formula. Not sure which. But I would welcome something to use a rule of thumb. Otherwise I'm going to stick with the manufacturers recomendations.

John

[Gary]

Did not know you could change that on castle. How do you do that? Have seen it on other ESC's though.

[m4a1usr]

Did not know you could change that on castle. How do you do that? Have seen it on other ESC's though.

Its changeable on the A/C ESC's. Not the Hydra series. Heli's have a recommended setting of 8khz. http://www.castlecreations.com/suppo...0mx-530kv.html

John

[keithbradley]

But it doesnt work out for some ESC. A Castle Hydra 240 ESC needs 12khz PWM for the CC/Neu 1515. And a Schulze 40.160 ESC likes the 9 to 19khz setting for a 4 pole motor. Neu motors recommends 11 to 13 khz on their motors. Something isnt right. Either its my math or its the formula. Not sure which. But I would welcome something to use a rule of thumb. Otherwise I'm going to stick with the manufacturers recomendations.

John

I've never ran anything other than 8k on an inrunner (Including my 1515-1y) and they've all ran well. I'm not saying you're wrong, but I dont understand why you would need 12k on a Neu 15 series motor...or why you would run a completely different PWM on one ESC than you would on another.
Still, I would start with the manufacturer's reccomendation. If that works well, then run it. This formula would come into play more when you have a motor that you don't already have info on. For example, my suppo 2200kv 6 pole motors in my EKOS (2200x6x18.5/20). For those motors a good starting point would be 12k.

I found this formula on another forum. I was researching "outrunner mode" on my castle ICE ESCs as I suspected it being a possible cause of excess current draw in my EKOS. It was posted by a castle creations rep as a guide for people who had no idea where to set the PWM, and he stated that he hadn't come across a conbo that didn't work well with this formula. I can't confirm that, as I just found this info myself, but I will be trying it out with my current and future setups.