A converter is a semiconductor based device which is capable of transforming ac electrical energy into dc form. On the contrary, inverter is a semiconductor based device which is capable of transforming dc electrical energy into ac form. Sometimes, a device with both ac to dc and dc to ac conversion capability is also called a converter. Moreover, devices that can convert ac directly into ac and dc directly into dc with different voltage levels also exist. All of these can be referred to as a “Converter” in general as a principle.

The use of converters has been increasing since the first mass production of semiconductor devices. Currently, not only the motors in the industry, but also a large portion of our domestic appliances include converters in them, or alternatively, they are fed from external converters. Their use is expected to become even more widespread around the world in the coming years because of the predicted increase in solar panel installations. Since solar panels produce dc output, they must be coupled to the network via inverters. Converters may also be used as the basis of some power quality enhancement equipment such as STATCOM, active power filter, etc.