Patent ID: 6278245
Filing Date: 2001-08-21
Classification: H05B,Y02B

Abstract:
An electronic ballast for high intensity discharge lamps having combined boost and buck converters and a simple current sensing technique, wherein said electronic ballast comprises:an AC voltage source having a first terminal and a second terminal;a series arrangement of a first inductance, a second inductance and a high intensity discharge lamp connected to said first terminal of said AC voltage source;a first capacitor arranged in parallel with said high intensity discharge lamp;a first series arrangement of a first high frequency switch, along with a body diode, and a first low frequency switch arranged in parallel with said second inductance and said high intensity discharge lamp;a second series arrangement of a second high frequency switch, along with a body diode, and a second low frequency switch arranged in parallel with said second inductance and said high intensity discharge lamp, a junction between said second high frequency switch and said second low frequency switch being connected to ground;a series arrangement of two diodes, a cathode of one of said two diodes being connected to a junction of said first high frequency switch and said first low frequency switch, and an anode of the other of said two diodes being connected to the junction of said second high frequency switch and said second low frequency switch, a junction between said two diodes being connected to a second terminal of said AC voltage source; anda series arrangement of a capacitor and a current sensing resistor arranged in parallel with said series arrangement of two diodes, wherein a current through said sensing resistor is used to detect an input buck current of said electronic ballast for indirectly controlling an output power generated by said electronic ballast.