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Power electronics

in general is a technology that deals with conversion of electrical energy by electronic circuits. A unit that perform such conversion is known as power supply unit, or PSU. Technically speaking of course, a PSU does not "supply" power, it just converts it from one form (such as AC) into another (such as DC) and changes its characteristics as required. Power electronics originated about a century ago. Originally it started with the application of grid-controlled gas-filled tubes for power control. The subsequent development of SCR, bipolar transistors and especially high-voltage MOSFETs really revolutionized the industry and resulted in rapid expansion of various power electronic applications.

There are two main types of PSU depending on the mode of operation of power semiconductors: linear and switching. Most modern power supplies except for linear amplifiers are of switching mode type. A PSU of such type is referred to as SMPS power supply. The control of energy flow in such a device is performed with power semiconductors that are continuously switching on and off with frequencies that are much higher than the input AC line frequency. These semiconductor switches are embedded in a network of inductors and capacitors, which each cycle accumulate some energy from the input and transfer it to the output. When a semiconductor device acts as a switch, it is possible to control large amounts of energy with a relatively low dissipation in the switching device. Indeed, an ideal switch does not dissipate any energy since it has either zero voltage when it's closed or zero current when it's open. A computer PSU is a typical example of an SMPS power supply.

This site is a power supply/ power electronics information resource. Here you can find general reference information, schematics, electronics calculators, as well as engineering career resources.

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