Patent ID: 7397225
Filing Date: 2008-07-08
Classification: H02M

Abstract:
1. Apparatus for controlling the power of an AC voltage supplying an electrical consumer by phase control and for reducing mainly the third harmonic caused by said phase control, comprising a first switching element (TRIAC) connected in series with said consumer and driven at a first firing angle into a conducting state by a control device for performing a phase control of said consumer during a given half cycle of the AC supply voltage, characterized in that a second switching element and a resistor element are provided, both being electrically connected in series to form a series connection, said series connection is provided parallel to the first switching element, said control device being adapted to drive the second switching element at a second firing angle into a conducting state at a first point in time (t 1 ) during said given half cycle that is shortly before a second point in time (t 2 ) when the first switching element is driven into the conducting state.