METHOD AND SYSTEM FOR SUPPLYING MULTIPLE LED DRIVERS USING THE SAME TRAIC DIMMER

• US 20120249012A1
• Filed: 03/30/2011
• Published: 10/04/2012
• Est. Priority Date: 03/30/2011
• Status: Abandoned Application

• Current Assignee: GRE Alpha Electronics Limited
• Original Assignee: GRE Alpha Electronics Limited
• Inventors: Xu, Abel
• Application Number:
  US13/075,200
• Publication Number:
  US 20120249012A1
• Time in Patent Office: Days
• US Class Current: 315/291
• CPC Class Codes: H02M 5/257 using semiconductor devices only
• CPC Class Codes: H05B 45/385 using flyback topology

Abstract

An RCD transient absorption circuit, having a first port and a second port, the RCD transient absorption circuit comprising a first resistor, a capacitor and a diode, wherein: the first resistor is connected in parallel to the capacitor, and resultant parallel connection of which is connected in series to a diode; one end of the resultant parallel connection of the first resistor and the capacitor is connected to a cathode of the diode; another end of resultant parallel connection is the first port of the RCD transient absorption circuit; and the second port of the RCD transient absorption circuit is an anode of the diode; the RCD transient absorption circuit further comprises a power-trimming device connected in parallel to the first resistor and the capacitor.

Claims

1. An RCD transient absorption circuit, having a first port and a second port, the RCD transient absorption circuit comprising a first resistor, a capacitor and a diode, wherein:

the first resistor is connected in parallel to the capacitor, and resultant parallel connection of which is connected in series to a diode;

one end of the resultant parallel connection of the first resistor and the capacitor is connected to a cathode of the diode;

another end of resultant parallel connection is the first port of the RCD transient absorption circuit; and

the second port of the RCD transient absorption circuit is an anode of the diode;

the RCD transient absorption circuit further comprises a power-trimming device connected in parallel to the first resistor and the capacitor.

2. The RCD transient absorption circuit of claim 1, wherein the power-trimming device is a variable resistor.

3. The RCD transient absorption circuit of claim 1, wherein the power-trimming device is formed by a second resistor and a variable resistor connected in series.

4. The RCD transient absorption circuit of claim 2, wherein the variable resistor has a resistance range from a few 10 k ohms to a few 100 k ohms.

5. The RCD transient absorption circuit of claim 3, wherein the second resistor has a resistance value of a few 10 k ohms in order to protect the variable resistor from being mistakenly set to zero ohm.

6. The RCD transient absorption circuit of claim 1, further comprising a TVS connected in parallel to the power-trimming device, wherein the cathode of the TVS is also connected to the cathode of the diode.

7. A dimmable LED driver system comprising a dimmer and at least one LED driver, each LED driver comprising:

an AC-to-DC converter that matches the characteristics of the dimmer;

a transformer for storing energy and for changing the voltage level;

an output section for supplying power to LED(s) for lighting; and

a PWM controller and a switcher, both of which are used for control of the output power;

wherein the dimmable LED driver system is controlled by the dimmer;

the at least one LED driver uses an RCD transient absorption circuit;

a first port and a second port of the RCD transient absorption circuit connect to a first end and a second end of the primary winding of the transformer respectively; and

the first port of the RCD transient absorption circuit connects to an output of the AC-to-DC converter.

8. The dimmable LED driver system of claim 7, wherein the dimmer is a TRIAC dimmer.

9. The dimmable LED driver system of claim 8, wherein the TRIAC dimmer is series connected to the at least one LED driver.

10. A method that employs a dimmer to perform the dimming function on a plurality of LED drivers, the method comprising the steps of:

installing an RCD transient absorption circuit into each of the plurality of LED drivers, wherein the RCD transient absorption circuit includes a power-trimming device;

choosing one LED driver as a reference driver;

setting the dimmer to a conduction angle;

adjusting the conduction angle such that the reference driver delivers an output current that is 1% within full-load current;

measuring output current level of each of the plurality of LED drivers other than the reference driver; and

adjusting the power-trimming device of the RCD transient absorption circuit in each of the LED drivers such that the output current is the same as that of the reference driver.