Inverters are circuits that convert dc to ac. More precisely, inverters transfer
power from a dc source to an ac load. The controlled full-wave bridge converters
in Chap. 4 can function as inverters in some instances, but an ac source must preexist
in those cases. In other applications, the objective is to create an ac voltage
when only a dc voltage source is available. The focus of this chapter is on inverters
that produce an ac output from a dc input. Inverters are used in applications
such as adjustable-speed ac motor drives, uninterruptible power supplies (UPS),
and running ac appliances from an automobile battery.