Pulse Width Modulation (PWM)

Controlling average voltage or power by rapidly switching a signal and adjusting how long it stays high.

PWM is a way of controlling “how much power” using a digital switching signal: the frequency stays fixed, and only the fraction of each cycle spent high, the duty cycle, is adjusted. At a 50% duty cycle, the average voltage seen by the load is about half the supply voltage. Because the switching device is always either fully on or fully off, it wastes very little energy itself, which is why motor drivers, switching power supplies, and LED dimming all use it. In robots, a motor driver uses PWM in a three-phase inverter bridge to generate motor current, often paired with field-oriented control (FOC); a servo, meanwhile, encodes its target angle in the width of a PWM pulse. Both microcontrollers and the Raspberry Pi can output PWM directly.

ExampleA typical analog servo receives one pulse every 20 ms, with a pulse width of roughly 1–2 ms corresponding to different target angles.

Also called

Pulse-Width Modulation

Related

Servo Drive (Motor Driver) · Field-Oriented Control · Servo (Smart Serial Bus Servo) · Brushless DC Motor · Microcontroller Unit (MCU) · Raspberry Pi

Sources

Pulse-width modulation - Wikipedia