Patent ID: 7042204
Filing Date: 2006-05-09
Classification: H02M

Abstract:
1. A voltage source comprising a serial capacitor connected in series between an AC power source and a load, and a first voltage limiting circuit and a second voltage limiting circuit connected in parallel to the load, the first voltage limiting circuit comprising a first switching element and a first capacitor connected in series, the second voltage limiting circuit comprising a second switching element and a second capacitor connected in series, wherein the first switching element is constantly conductive to an electric current flowing in one direction for charging the first capacitor in a positive half cycle of the AC power source, and is controllably turned on and off for an electric current flowing in the other direction, wherein, when a voltage of the first capacitor exceeds a predefined positive voltage level (E wherein the second switching element is constantly conductive to an electric current flowing in one direction for charging the second capacitor in a negative half cycle of the AC power source, and is controllably turned on and off for an electric current flowing in the other direction, wherein, when a voltage of the second capacitor is reduced below a predefined negative voltage level (−E