This takes the mains supply voltage and converts it from the supply frequency of 50 or 60 Hz and also converts it to 'DC'. This can supply a variable DC voltage, a fixed DC voltage or a variable DC current. In the case of a variable systems, they are used to provide overall power control for the system. Fixed voltage rectifiers need to be used in conjunction with an alternative means of power control. This can be done by utilising a switch mode regulator or a by using a variety of control methods within the inverter section.
