Choppers: how they work

First of all, the term chopper refers to the class of DC/DC converters. They can be PWM (Pulse Width Modulation) or PPM (Pulse Position Modulation) modulated.

From a structural point of view, a three-phase PWM inverter will be made up of six simple DC/DC choppers, grouped into three reversible choppers of the same type. So it's important to understand how choppers work, before tackling inverters in another article.

The chopper is indispensable when the source is continuous (battery, catenary, etc.). But it is also widely used in industrial robotics (mains supply + rectifier), as its high switching frequency gives a wide bandwidth motor-drive.

The purpose of the article [E 3 964] is to study the operation of single-quadrant voltage step-down and step-up choppers, from which the operation of the reversible voltage chopper in two and four quadrants will be deduced. Other chopper variants are briefly discussed: intermediate storage, insulated, resonant...

Fine modeling of the accessories of the structures encountered, as well as their control, are the subject of this article. .