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A power supply unit (sometimes abbreviated power supply or PSU) is a device that supplies electrical power to a device or group of devices. The term is most commonly applied to units that are integrated with the devices they supply, such as computers and household electronics , and never to devices supplying, conditioning or otherwise supporting an electric utility grid. (For large-scale power supplies, see electricity generation.)A power supply (or in some cases just a transformer) that is built into the top of a plug is known as a wall wart
The range of different types of power supply is very broad, since widely differing design criteria affect each application.
As well as the usual requirements of cost, reliability, weight and size, constraints that commonly affect power supplies are the amount of power they can supply, how long they can supply it for without needing some kind of refueling or recharging, how stable their output voltage or current is under varying load conditions, and whether they provide continuous power or pulses.
Common power supply technologies include:
- Batteries
- Chemical fuel cells
- ...and other forms of power storage systems
- Solar power
- Conversion of another form of electrical power into the desired form (typically converting 120 or 240 volt alternating current supplied by a utility company (see electricity generation) into low-voltage direct current for electronic devices); see switched-mode power supply, linear regulatorA linear regulator is an electronic power supply circuit that attempts to produce a smoothed, constant- voltage, output from a varying input voltage. Linear regulators are so named because they contain a transistor operating in its "linear region", with t, rectifierA rectifier is one or more diodes arranged for converting alternating current (AC) to direct current (DC). When just one diode is used to rectify AC (by omitting the negative portion of the waveform) the difference between the term diode and the term rect, inverter (electrical)An inverter is a circuit for converting direct current to alternating current, they are used in a wide range of applications, from small power supplys for a computer to large industrial applications to transport bulk power. An inverter can have one or two
- Generators or alternatorAn alternator is a generator that produces alternating current by converting mechanical energy to electrical energy. Alternators are generally simpler, more reliable, and can be more efficient than direct current generators because they do not need to uses (particularly useful in vehicles of all shapes and sizes, where the engine has rotational power to spare, or in semi-portable units containing an internal combustion engineAn internal combustion engine is an engine that is powered by the expansion of hot combustion products of fuel directly acting within an engine. A piston internal combustion engine works by burning hydrocarbon or hydrogen fuel that presses on a piston; an and a generator)
More specialised power supplies might be based upon:
- FlywheelA flywheel is a heavy rotating disk used as a repository for angular momentum. Flywheels resist changes in their rotation speed, which helps steady the rotation of the shaft when an uneven torque is exerted on it by its power source such as a piston-baseds coupled to generatorA generator refers to several things: an electrical generator the generating set of a group In computer science, particularly in the Python programming language, a generator is a type of continuation that can be used as an iterator.s or alternators
- Capacitors
- Compulsators
- Explosively pumped flux compression generators
