What is Switching Frequency? - RC Groups
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Oct 14, 2011, 06:33 PM
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jonathan7x70's Avatar

What is Switching Frequency?

I have the Turnigy 55Amp Delx Esc.

It has 8kHz & 16kHz.

What one should I use? 8 or 16?

Here is the ESC Link if you need it:
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Oct 14, 2011, 10:18 PM
Registered User
Dr Kiwi's Avatar
Words of wisdom from Ron:

PWM = Pulse Width Modulation

Unless your ESC is at full power, the ESC pulses (or chops up) the voltage to the motor. The wider the pulse, the more power it gets, 100% pulse width is 100% power. The frequency of these pulses can be 8kHz, 16kHz or 32kHz. Although the voltage to the motor is pulsed, the current to/in the motor is not pulsed. The 'smoothess' of the current depends in the motors inductance (the more inductance, the smoother) and the PWM frequency (the higher the frequency, the smoother). High inductance (e.g. outrunners) motors can do with 8kHz, low inductance motors (eg. slotless or ironless motors, Kontronik Tango) need 32kHz. Driving a high inductance motor with 32kHz won't hurt, but controller losses will be higher. So in your outrunner case, use 8kHz.

Vriendelijke groeten Ron
Last edited by Dr Kiwi; Oct 15, 2011 at 12:40 PM.
Oct 14, 2011, 10:47 PM
Fly, fly, fly, fly , fly more!
jonathan7x70's Avatar
wow thats a lot of info.. not sure i understand but ill stick with 8kHz. the link is not working.
Oct 15, 2011, 08:41 AM
100% electric since 1990
twest's Avatar
Some suggestions to start with:

Outrunner motors: most likely 8 khz (unless you are turning high rpms in edf or heli)

8 pole inrunner (neu 1900, big astro brushless)- 8khz or 12 khz

6 or 4 pole inrunner (mega, neu, astro, aveox): 12 khz (or 8 if your esc won't do 12)

2 pole inrunner (slotless, hacker, kontronic, etc) 16 khz

kontronic tango: 32 khz
Oct 15, 2011, 08:43 AM
100% electric since 1990
twest's Avatar
If using helis, there is a formula I've seen in the castle creations forum on how to calculate needed frequency, and it uses motor poles, gear ratio, head speed, etc to come up with an estimate.

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