Recap of Power Electronics

Electric Power Lines
Kirchhoff's Voltage and Current Laws
Filtering a Switched Power Supply

Power electronics involves the study of electronic circuits intended to control the flow of electrical energy. These circuits handle power flow at levels higher than the individual device ratings.

Energy conversion is our business because people use light, mechanical work, information, heat and other tangible results of energy – not electricity itself. In most electronics, devices are limited by their ability to dissipate lost energy. In power electronics, we are interested in how much energy flow a device can manipulate, and intend to keep the dissipation as low as possible. Power handling ratings, given by the product of ratings for voltage and current, are larger than power dissipation ratings by more than a factor of 100 for many power electronic devices.

Voltage level and frequency conversion are the most common needs for electrical energy conversion. All major industries use power converters. Significant growth is expected in AC drives, electric transportation, portable power, telecommunications applications, and utility applications.

A power converter is positioned between a source and a load. A primary objective is 100% efficiency. Very high reliability is also important. The switch is a familiar lossless device the can manipulate energy flow. Many circuits can be analyzed through energy conversion considerations. Functions such as DC voltage conversion can be created with switch networks.

A power electronic system consists of an electrical source and load, a power electronic circuit containing switches and energy storage, and control functions. The power electronic circuit portion often has relatively few parts, and most of the components in a commercial system perform control functions.

Power electronics today is evolving from a device-driven field to an applications-driven field. Not long ago, the possible conversion functions were limited by the types of switch technologies. Today, new applications such as AC motor controllers can be built with several types of devices. In the future, application requirements will not be limited by device capabilities.

Kirchhoff's Voltage and Current Laws
Filtering a Switched Power Supply

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