PWM frequency is one of the settings people change most often for the wrong reason. Usually it’s because someone said higher is smoother, which is true, but it’s only half the story.
What it is (and what it isn’t) #
It isn’t DShot, and it has nothing to do with the signal coming from your flight controller. PWM frequency is how many times per second the ESC switches its MOSFETs on and off.
That switching is how an ESC controls the voltage and current delivered to the motor.
At 40% duty, the ESC isn’t simply feeding the motor a steady 40% of battery voltage. The MOSFETs switch the full battery voltage on and off very quickly, with the average effect corresponding roughly to that commanded duty.
The motor windings smooth those pulses into current.
Smooth is relative, though. The current rises while voltage is applied and falls between switching events, so it is always moving slightly around its average value. That variation is called current ripple.
Higher vs lower #
Switch faster, and the current has less time to rise and fall between switching events, so the ripple becomes smaller.
Higher PWM frequency generally gives smoother motor current, smoother low-throttle behavior, and quieter motors. The cost is heat: every switching transition wastes a small amount of energy in the MOSFETs, so more switching events usually mean higher ESC switching losses.
Lower PWM frequency reduces switching losses and can improve ESC efficiency, especially at high current. The trade-off is greater current ripple, more audible motor noise, and potentially rougher behavior at low throttle.
Neither is universally better. It’s a trade-off between smoothness, switching losses, and the motor being used.
Your motor changes the answer #
Very roughly, current ripple increases with voltage and decreases with winding inductance and PWM frequency.
So:
more voltage = more potential ripple
more inductance = less ripple
higher PWM frequency = less ripple
High-KV motors often have relatively low winding inductance, so they can experience more current ripple at the same PWM frequency than a larger, lower-KV motor.
Higher battery voltage also increases the rate at which current can change through the winding.
That’s why small, high-KV builds often benefit from a higher PWM frequency, while larger, lower-KV long-range motors can frequently run a lower frequency and gain some efficiency.
There’s one catch at the very bottom of the throttle range.
At high PWM frequency and very low duty, each individual ON pulse becomes extremely short. That leaves less useful time for the ESC to observe the motor’s electrical behavior between switching events.
On a sensorless ESC, this can make rotor-position detection more difficult near idle or during difficult transitions.
That’s one reason why “just set PWM as high as possible” isn’t always the best answer.
When to change it #
Start with the default: AUTO.
Change it only when you have a reason.
| Symptom | Try |
|---|---|
| ESC runs unusually hot during otherwise normal flights | One step lower |
| Rough or gritty low throttle; motors sound harsh | One step higher |
| Long-range build where efficiency matters | One step lower, then check ESC and motor temperatures |
| Very high-KV motor on high voltage with rough low-throttle behavior | One step higher, while checking idle behavior and temperatures |
Change only one step at a time.
Fly the same battery type and roughly the same kind of flight, then check both the ESC and motor temperatures.
If something gets worse, go back.
Don’t change PWM frequency, timing, ramp settings, and PID tuning all at once. If you change four things and the quad suddenly flies better or worse, you have learned almost nothing about which setting actually caused it.
