Switch-mode power supply is a well-developed topic in power electronics. There are many text books and articles on this subject. The purpose here is to present the same information in a different manner. The aim is to use a layered approach to present the information, so that the students and the practitioners may find it easy to understand the topic. It is also the aim to make the presentation as interactive as possible.
The step-down converter, also known as the buck converter, is often used in place of the linear power supply because of smaller size and higher efficiency. The first converter to be presented is the step-down converter.
The step-up converter, also known as the boost converter, has an output voltage greater than the input voltage. In order to step up the input voltage by ten times or more, it may be necessary to connect a few boost converters in cascade. A combination of an inverter and rectifier may be better option in some cases. A unity-power factor rectifier has the boost converter as its core component.
A fly-back converter is a dc-to-dc converter, but the output is electrically isolated from the input by use of a coupled inductor. It is possible to have multiple secondaries and a corresponding number of outputs. The converter used for power supply used in computers is a fly-back converter.
A Cuk converter, named after its creator, is capable of higher power output than the boost or buck converter. The feature of a Cuk converter is that it has two-stage LC filter and the result is that the output has very low ripple content. Additionally, the polarity of output is opposite to that of input. In application that need dual power supplies with opposite polarities, a Cuk converter can be used to produce the second supply from a dc source.
There have been many developments in the last decade or so in the area of SMPS, but most of the books do not cover them. Some of the developments are presented here.
There are topics that are important to all converters. Traditionally MOSFETs and fast diodes are used in switch-mode power supplies. Magnetics plays an important role in any SMPS. The other important element of a switch-mode power supply is the capacitor. These topics are presented in as much detail as possible.