Electric power conversion
In all fields of electrical engineering, power conversion is the process of converting electric energy from one form to another. A power converter is an electrical or electro-mechanical device for converting electrical energy. A power converter can convert alternating current (AC) into direct current (DC) and vice versa; change the voltage or frequency of the current or do some combination of these. The power converter can be as simple as a transformer or it can be a far more complex system, such as a resonant converter. The term can also refer to a class of electrical machinery that is used to convert one frequency of alternating current into another. Power conversion systems often incorporate redundancy and voltage regulation. Power converters are classified based on the type of power conversion they do. One way of classifying power conversion systems is according to whether the input and output are alternating current or direct current. Finally, the task of all power converters is to "process and control the flow of electrical energy by supplying voltages and currents in a form that is optimally suited for user loads". DC-to-DC converter The following devices can convert DC to DC: Linear regulator Voltage regulator Motor–generator Rotary converter Switched-mode power supply The following devices can convert DC to AC: Power inverter Motor–generator Rotary converter Switched-mode power supply Chopper (electronics) The following devices can convert AC to DC: Rectifier Mains power supply unit (PSU) Motor–generator Rotary converter Switched-mode power supply AC-to-AC converter The following devices can convert AC to AC: Transformer or autotransformer Voltage converter Voltage regulator Cycloconverter Variable-frequency transformer Motor–generator Rotary converter Switched-mode power supply Three-phase electric power There are also devices and methods to convert between power systems designed for single and three-phase operation. The standard power voltage and frequency vary from country to country and sometimes within a country.