Active damper and driving method thereof
View Patent ↗An exemplary embodiment of the present invention relates to an active damper and a driving method thereof. An AC input passed through a dimmer is transmitted to an active damper through a rectification circuit. The active damper includes a damper resistor connected to the rectification circuit, a damper switch connected to the damper resistor in parallel, and a delay circuit delaying a turn-on time of the damper switch by a predetermined initial period from a turn-on time of the dimmer.
1. An active damper that receives an input current that is generated from an AC input that is passed through a dimmer and rectified by a rectification circuit, the active damper comprising:
a damper resistor connected to the rectification circuit;
a damper switch connected to the damper resistor in parallel; and
a delay circuit delaying a turn-on time of the damper switch by a predetermined initial period from a turn-on time of the dimmer,
wherein after the damper switch is turned-on, the damper switch is turned-off based on a voltage that is developed and sensed across the damper resistor.
2. The active damper of claim 1 , wherein the delay circuit comprises:
a resistor including a first end connected to a first end of the damper resistor, and
a capacitor connected between a second end of the resistor and a second end of the damper resistor.
3. The active damper of claim 2 , wherein the damper switch comprises a gate electrode connected to a node of the resistor and the capacitor.
4. The active damper of claim 1 , further comprising a reset circuit that resets the delay circuit based on the voltage that is developed and sensed across the damper resistor.
5. The active damper of claim 4 , wherein the reset circuit comprises a diode having a cathode connected to a first end of the damper resistor and an anode connected to a gate electrode of the damper switch.
6. The active damper of claim 1 , wherein the input current flows to a power supply through the active damper.
7. The active damper of claim 6 , wherein the input current flows through the damper resistor during an initial period, and then the input current flows through the damper switch after the initial period elapses.
8. A driving method of an active damper that receives an input current that is generated from an AC input that is passed through a dimmer and rectified by a rectification circuit, the active damper including a damper resistor and a damper switch connected to the damper resistor in parallel, the driving method comprising:
charging a capacitor connected between a gate electrode and a source electrode of the damper switch during an initial period from a turn-on time of the dimmer;
turning on the damper switch when a gate-source voltage of the damper switch reaches a threshold voltage by a voltage charged in the capacitor during the initial period; and
after turning on the damper switch, turning off the damper switch based on a voltage that is developed and sensed across the damper resistor.
9. The driving method of claim 8 , further comprising, during a normal period during which the damper switch is turned on, constantly maintaining a both-end voltage of the damper resistor with the threshold voltage.
10. The driving method of claim 9 , further comprising;
flowing the input current through the damper resistor during the initial period; and
flowing the input current through the damper switch during a normal period.
11. The driving method of claim 8 , further comprising;
connecting a diode when a both-end voltage of the damper resistor becomes lower than the threshold voltage of the damper switch by a decrease of the input current; and
discharging the voltage charged in the capacitor through the connected diode.