View Full Version : PWM rate
keithbradley
05-23-2011, 11:06 PM
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
05-24-2011, 12:12 AM
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
If I understand correctly, your math is right, the PWM in the first case is 6512Hz or approx 6KHz.
m4a1usr
05-24-2011, 12:48 AM
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
Did not know you could change that on castle. How do you do that? Have seen it on other ESC's though.
m4a1usr
05-24-2011, 01:13 AM
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/support/align_heli_settings/align-700e-700mx-530kv.html
John
keithbradley
05-24-2011, 06:25 AM
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.:confused2:
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.:thumbup1:
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