Power electronics and its motives

Power electronics refers to control and conversion of electrical power by power semiconductor devices wherein these devices operate as switches. Advent of silicon-controlled rectifiers,abbreviated as SCRs, led to the development of a new area of application called the power electronics. Prior to the introduction of SCRs, mercury-arc rectifiers were used for controlling electrical power, but such rectifier circuits were part of industrial electronics and the scope for applications of mercury-arc rectifiers was limited. Once the SCRs were available, the application area spread to many fields such as drives, power supplies, aviation electronics, high frequency inverters and power electronics originated.

Power electronics has applications that span the whole field of electrical power systems, with the power range of these applications extending from a few VA/Watts to several MVA /MW. The main task of power electronics is to control and convert electrical power from one form to another. The four main forms of conversion are:

(1) Rectification referring to conversion of ac voltage to dc voltage,
(2) DC-to-AC conversion,

(3)DC-to DC conversion and

(4)AC-to-AC conversion.

"Electronic power converter" is the term that is used to refer to a power electronic circuit that converts voltage and current from one form to another. These converters can be classified as:

1.  Rectifier converting an ac voltage to a dc voltage,

2. Inverter converting a dc voltage to an ac voltage,

3. Chopper or a switch-mode power supply that converts a dc voltage to another dc voltage, and

4. Cycloconverter and cycloinverter converting an ac voltage to another ac voltage.
In addition, SCRs and other power semiconductor devices are used as static switches.