Power electronic systems

Power electronics is a technology associated with the efficient conversion, control, and conditioning of electric power by static means from its available input form into the desired electrical output form.

The main component of the power electronic system is shown in the form of a block diagram in a figure. The main power source may be an AC supply system or a DC supply system.
The output from the power electronic circuit, it may be variable DC or AC voltage, or it may be a variable voltage and frequency. In general, the output of a power electronic converter circuit depends upon the requirement of the which type of load.
The feedback component in figure measure a parameter of the load, say speed in case of a rotating machine, and compares it with the command.

The difference of this two, through the digital circuit components and controls the instant of turn-on of semiconductor devices forming the solid state power converter system.
In this manner, the behavior of the load circuit can be controlled as desired, over a wide range with the adjustment of the command. 

Block diagram of a typical power electronic system

You can check more details about power electronics system: POWER ELECTRONICS