POWER CONVERTER FOR AN LED ASSEMBLY AND LIGHTING APPLICATION

• US 20110115412A1
• Filed: 07/10/2009
• Published: 05/19/2011
• Est. Priority Date: 07/11/2008
• Status: Active Grant

• Current Assignee: eldoLAB Holding B.V. (Acuity Brands, Inc.)
• Original Assignee: eldoLAB Holding B.V. (Acuity Brands, Inc.)
• Inventors: Welten, Petrus Johannes Maria
• Granted Patent: US 8,710,757 B2
• Time in Patent Office: Days
• US Class Current: 315/307
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/375 using buck topology
• CPC Class Codes: H05B 45/382 with galvanic isolation between input and output
• CPC Class Codes: H05B 45/39 Circuits containing inverter bridges
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

The present invention relates to a power converter for an LED assembly, the power converter comprising—a switched mode power supply arranged to power the LED assembly, an AC/DC converter arranged to provide a DC supply voltage to the switched mode power supply, a control unit arranged to receive an input signal representing a required load voltage for powering the LED assembly, the control unit being arranged to control the AC/DC converter based on the input signal.

Claims

1. A power converter for an LED assembly, the power converter comprising

a switched mode power supply arranged to power the LED assembly;

an AC/DC converter arranged to provide a variable DC supply voltage to the switched mode power supply; and

a control unit arranged to receive an input signal representing a required load voltage for powering the LED assembly, the control unit being arranged to control the AC/DC converter, in accordance with the required load voltage.

2. The power converter according to claim 1 wherein the control unit is arranged to control the AC/DC converter to provide the variable DC supply voltage at a level substantially matching or proportional to the required load voltage.

3. The power converter according to claim 1 wherein the AC/DC converter comprises

a transformer arranged to provide a variable AC output voltage based on a control signal from the control unit;

and

a first rectifier for converting the variable AC voltage to the variable DC supply voltage.

4. The power converter according to claim 3 wherein the transformer comprises a primary winding having multiple terminals connectable to an AC power source via a selector element, said selector element being controlled by the control signal of the control unit, and a secondary winding connected to the first rectifier.

5. The power converter according to claim 3 wherein the secondary winding comprises multiple terminals connectable to the first rectifier via a selector element, said selector element being controlled by the control signal of the control unit.

6. The power converter according to claim 3 wherein the transformer comprises a plurality of primary windings and/or secondary windings and a switching element enabling a series and/or parallel connection of a subset or all of the plurality of primary windings and/or secondary windings thereby, in use, providing the variable AC output voltage, said switching element being controlled by the control signal of the control unit.

7. The power converter according to claim 1 wherein the AC/DC converter comprises a transformer arranged to provide a variable AC output voltage based on a control signal from the control unit, the transformer comprising

a primary winding having multiple terminals connectable to an AC power source via a selector element, said selector element being controlled by the control unit and

a plurality of secondary windings, each secondary winding being provided with a first rectifier for, in use, converting the variable AC voltage over the secondary winding to the variable DC supply voltage.

8. The power converter according to claim 3 wherein the AC/DC converter is further arranged to convert an AC power source having a comparatively low frequency to an AC power source having a comparatively high frequency.

9. The power converter according to claim 7 wherein the AC/DC converter comprises a second rectifier for rectifying the AC power source having a comparatively low frequency and a frequency converter for converting the rectified AC power source to the AC power source having a comparatively high frequency, the second rectifier and frequency converter being controlled by the control unit, based on the input signal.

10. The power converter according to claim 9 wherein the AC power source having a comparatively low frequency is an AC mains supply at 50 Hz or 60 Hz.

11. The power converter according to claim 9 wherein the comparatively high frequency is more than 500 Hz.

12. The power converter according to claim 3 wherein the transformer comprises a plurality of transformer modules and a switching element for enabling a series and/or parallel connection of a subset or all of the plurality of transformer modules thereby, in use, providing the variable AC output voltage, the switching element being controlled by the control signal of the control unit based on the input signal.

13. The power converter according to claim 1 wherein the input signal is based on a forward voltage measurement of the LED assembly or based on a set point obtained from a user interface.

14. A Lighting application comprising a power converter according to claim 1 and an LED assembly arranged to, in use, being powered by the switched mode power supply of the power converter.

15. The lighting application according to claim 14 wherein the control unit is further arranged to control a current, in use, provided by the switched mode power supply to the LED assembly.

16. The lighting application according to claim 14 wherein the LED assembly comprises a chain of multiple LED units in series, each LED unit being provided with a parallel switching element that is controlled by the control unit.