DC - To - AC Conversion

The converter that changes a dc voltage to an alternating voltage is called an inverter. Earlier inverters were built with SCRs. Since the circuitry required to turn the SCR off tends to be complex, other power semiconductor devices such as bipolar junction transistors, power MOSFETs, insulated gate bipolar transistors (IGBT) and MOS-controlled thyristors (MCTs) are used nowadays. Currently only the inverters with a high power rating, such as 500 kW or higher, are likely to be built with either SCRs or gate turn-off thyristors(GTOs). There are many inverter circuits and the techniques for controlling an inverter vary in complexity.
Some of the applications of an inverter are listed below:

• Emergency lighting systems,

• AC variable speed drives,

• Uninterrupted power supplies, and

• Frequency converters.
  
  Source : http://powerdesigners.com/InfoWeb/resources/pe_html/ch01/ch01_p1.htm#second