This article covers unidirectional Pulse Width Modulation (PWM) and how it can be used to control the power applied to a DC motor or the current in a stepper motor winding, for instance. While we eventually want to talk about doing bidirectional PWM with an h-bridge, we’ll start with a simple, one-direction control circuit.
An h-bridge is a bipolar driver circuit that is often used to control a load such as a brush type DC motor. This article covers the most basic concepts of a simplified h-bridge circuit. Later articles dig deeper into the details of practical h-bridge operation and design.