High efficiency driver circuit with fast response

• US 9,791,110 B2
• Filed: 05/30/2014
• Issued: 10/17/2017
• Est. Priority Date: 04/25/2014
• Status: Active Grant

• Current Assignee: IDEAL Industries Lighting, LLC (Ideal Industries Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Hu, Yuequan, Pope, Daniel, Hu, Qingcong
• Primary Examiner(s): Owens, Douglas W
• Assistant Examiner(s): Chan, Wei
• Application Number:
  US14/291,829
• Publication Number:
  US 20150312983A1
• Time in Patent Office: 1,236 Days
• Field of Search: 315291, 315297, 315294, 315224, 315186, 315122, 327536
• CPC Class Codes: F21K 9/23 Retrofit light sources for lighting devices with a single fitting for each light source, e.g. for substitution of incandescent lamps with bayonet or threaded fittings
• CPC Class Codes: F21K 9/64 using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
• CPC Class Codes: F21S 8/088 with lighting device mounted on top of the standard, e.g. for pedestrian zones
• CPC Class Codes: F21V 14/04 by movement of reflectors in vehicle head lamps F21S41/675
• CPC Class Codes: F21V 17/02 with provision for adjustment F21V17/04 - F21V17/08 take precedence
• CPC Class Codes: F21V 23/007 enclosed in a casing
• CPC Class Codes: F21V 23/06 the elements being coupling devices , e.g. connectors
• CPC Class Codes: F21V 29/503 of light sources cooling arrangements structurally associated with gas-discharge or vapour-discharge lamps H01J61/52; cooling arrangements structurally associated with electric incandescent lamps H01K1/58; cooling arrangements structurally associated with light-emitting diodes H01L33/64
• CPC Class Codes: F21V 29/773 the planes containing the fins or blades having the direction of the light emitting axis
• CPC Class Codes: F21V 3/00 Globes; Bowls; Cover glasses with refracting properties F21V5/00; with reflecting properties F21V7/00; characterised by cooling arrangements F21V29/506
• CPC Class Codes: F21V 7/0066 specially adapted to cooperate with point like light sources; specially adapted to cooperate with light sources the shape of which is unspecified F21V7/16 - F21V7/30 take precedence
• CPC Class Codes: F21W 2131/10 Outdoor lighting
• CPC Class Codes: F21W 2131/103 of streets or roads
• CPC Class Codes: F21Y 2107/30 on the outer surface of cylindrical surfaces, e.g. rod-shaped supports having a circular or a polygonal cross section
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H01R 43/00 Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors of trolley lines B60M1/28
• CPC Class Codes: H05B 45/14 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/37 Converter circuits
• CPC Class Codes: H05B 45/46 having LEDs disposed in parallel lines
• CPC Class Codes: H05B 45/50 responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
• CPC Class Codes: Y02B 20/30 : Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A high efficiency driver circuit with fast response is disclosed. Embodiments of the present invention relate to an LED driver that can drive a plural number of LED strings. The driver according to example embodiments includes a voltage converter stage with a feedback loop. The driver can include a speed-up circuit, and/or an adaptive output voltage control circuit, also referred to herein as an overhead control circuit. In at least some embodiments, an input inductor helps to attenuate input current ripple, which could otherwise lead to low high-frequency winding loss in other inductors. The speed-up circuit can provide current regulation of the LED strings and prevent flickering of the LEDs. The overhead control circuit can adjust the output voltage of the driver to an optimum value to improve operating efficiency.

Claims

1. A switched-mode driver including an input, and an output connectable to a load, the switched-mode driver comprising:

a converter stage to receive an input voltage at the input and provide an output voltage to the load at the output, the converter stage further including a switching device;

a power factor correction controller connected to the switching device to provide a gate signal so that an input current waveform follows an input voltage waveform;

a speed-up circuit connected to the switching device, the speed-up circuit comprising a control switch with an associated series current sensing resistance to determine current flowing between the switching device and the control switch, and being operable to increase current at the input of the switched-mode driver in response to an increased demand for current by the load; and

one or more current regulators, each connectable one or more LED strings;

wherein the one or more current regulators comprise an overhead controller to inject a signal into a feedback loop in the converter stage in response to a duty cycle of the one or more current regulators.

2. The switched-mode driver of claim 1 wherein the speed-up circuit further comprises a voltage monitor connected to the control switch.

3. The switched-mode driver of claim 2 wherein the voltage monitor is implemented by a microcontroller.

4. The switched-mode driver of claim 2 wherein the converter stage further comprises a single-ended primary inductor converter (SEPIC).

5. The switched-mode driver of claim 2 wherein the converter stage further comprises at least one of a buck converter and a boost converter.

6. The switched mode driver of claim 2 wherein the voltage monitor is connected to the output to respond to changes in the output voltage.

7. The switched-mode driver of claim 2 further comprising a current amplifier connectable to the load, wherein the voltage monitor is connected to the current amplifier to respond to the increased demand for current by the load.

8. A switched-mode driver including an output connectable to a load, the switched-mode driver comprising:

a converter stage to receive an input voltage at an input and provide an output voltage to the load at the output, the converter stage further comprising a feedback loop, the converter stage further including a switching device;

a power factor correction controller connected to the switching device to provide a gate signal so that an input current waveform follows an input voltage waveform;

a speed-up circuit connected to the switching device in the converter stage, the speed-up circuit comprising a control switch with an associated series current sensing resistance to determine current flowing between the switching device and the control switch, and being operable to increase current at the input of the switched-mode driver in response to an increased demand by the load; and

one or more current regulators comprising an overhead control circuit configured to inject a control signal into the feedback loop to adaptively adjust the output voltage in response to changes in operating efficiency of the load.

9. The switched-mode driver of claim 8 wherein each of the one or more current regulators is connectable to one or more parallel LED strings serving as the load.

10. The switched-mode driver of claim 9 wherein the converter stage further comprises a single-ended primary inductor converter (SEPIC).

11. The switched-mode driver of claim 9 wherein the converter stage further comprises at least one of a buck converter and a boost converter.

12. An LED lighting system comprising:

the switched-mode driver of claim 8;

one or more parallel LED strings connected to the switched-mode driver as the load; and

a rectifier connected to the input of the switched-mode driver.

13. An LED lighting system comprising:

the switched-mode driver of claim 9;

the one or more parallel LED strings; and

a rectifier connected to the input of the switched-mode driver.

14. A method of operating an LED lighting system, the method comprising:

receiving an input voltage and supplying an output voltage to one or more parallel LED strings;

using a power factor correction controller connected to a switching device to provide a gate signal so that an input current waveform follows an input voltage waveform;

using a speed-up circuit comprising a control switch with an associated series current sensing resistance to determine current flowing between the switching device and the control switch, to increase current at an input to a converter stage in response to an increased demand for current by the one or more parallel LED strings;

using a current regulator, the current regulator comprising an overhead controller to adaptively adjust the output voltage in response to changes in the operating efficiency of LEDs in the one or more parallel LED strings.

15. The method of claim 14 wherein the using of the speed-up circuit further comprises sensing the output voltage using a voltage monitor.