Patent ID: 9325254
Filing Date: 2016-04-26
CPC Classification: H02M,H05B,Y02B

Claim Text:
1. A SCR dimming circuit comprising a SCR element, a rectifier circuit, a filter circuit, a power converter, and a dimming control circuit, wherein said SCR element, said rectifier circuit and said filter circuit are configured to obtain a bus voltage from an AC power supply for said power converter, said dimming control circuit comprising: a phase angle detection circuit for receiving a bus voltage sampling signal indicative of said bus voltage, comparing said bus voltage sampling signal with a threshold voltage, an outputting a phase angle signal; an output current feedback control circuit for receiving said phase angle signal and an output current feedback signal indicative of an output current of said power converter, and generating a first control signal in accordance with said phase angle signal and said output current feedback signal; an input current control circuit for receiving an input current sampling signal indicative of an input current of said power converter, comparing said input current sampling signal with a predetermined value, and outputting a second control signal, wherein said predetermined value is less than a holding current of said SCR element; a maximum operation time detection circuit for receiving said phase angle signal, measuring a first time period during which said phase angle signal is valid, and generating a third control signal which is valid when said first time period reaches a predetermined time and is valid when said phase angle signal becomes invalid; and a logic operator for receiving said first control signal, said second control signal and said third control signal, and outputting a driving signal.