Why Can’t We Just Use a Dimmer Switch? The Advantages of PWM
3. PWM vs. Analog Control
You might be thinking, “Why not just use a dimmer switch, like on a lamp?” That’s a valid question! Dimmer switches reduce the voltage going to the lamp, which reduces its brightness. While this seems similar, there are some key differences that make PWM superior for motor control.
One major advantage is efficiency. Dimmer switches waste energy as heat. They essentially “burn off” the excess voltage. PWM, on the other hand, is much more efficient. It simply switches the power on and off, without wasting energy. This is especially important for battery-powered devices, where every bit of energy counts. Think about the longevity of your drone’s flight time!
Another advantage is torque. Motors need torque (rotational force) to overcome resistance and turn a load. At low voltages, a motor may not have enough torque to even start turning. PWM can deliver short bursts of full voltage, providing the necessary torque to get the motor spinning, even at low average speeds. A dimmer switch simply reduces the voltage, potentially starving the motor of the initial torque it needs.
Finally, PWM is less susceptible to voltage drops and other electrical noise. The rapid switching action of PWM helps to filter out these disturbances, resulting in more stable and predictable motor control. So, while a dimmer switch might work for a lamp, PWM is the clear winner for motor control, offering better efficiency, torque, and stability.