Light emitting diode power supply

• US 6,411,045 B1
• Filed: 12/14/2000
• Issued: 06/25/2002
• Est. Priority Date: 12/14/2000
• Status: Expired due to Term

• Current Assignee: Current Lighting Solutions, LLC (f/k/a GE Lighting Solutions, LLC) (American Industrial Partners)
• Original Assignee: General Electric Company
• Inventors: Nerone, Louis R.
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): Lee, Wilson
• Application Number:
  US09/736,994
• Time in Patent Office: 558 Days
• Field of Search: 315/209.R, 315/224, 315/291, 315/219, 315/307, 315/200.A, 315/200.R, 315/185.S, 315/185.R, 315/241.P, 362/800
• US Class Current: 315/291
• CPC Class Codes: H02M 7/4815 Resonant converters H02M7/4811 and H02M7/4826 take precedence
• CPC Class Codes: H02M 7/538 in a push-pull configuration H02M7/5375 takes precedence ; with oscillating arrangements H02M7/53832, H02M7/53846
• CPC Class Codes: H05B 45/37 Converter circuits
• CPC Class Codes: H05B 45/382 with galvanic isolation between input and output
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A space efficient circuit arrangement for supplying power to an LED array, the power supply circuit (100) has a rectifier (105), a starting circuit coupled to the rectifier (105), a gate drive arrangement coupled to the starting circuit, and a resonant converter circuit (120, 125) coupled between the rectifier (105) and a resonant load circuit (135). The resonant load circuit includes a resonant inductance (150), a resonant capacitance (155) coupled to the resonant inductance (150), and a load connected in parallel to the resonant capacitance (155). A plurality of light emitting elements (170, 175) and a capacitor (160) define at least a portion of the load. All of the circuit components may be placed on the same circuit board as the light emitting elements (170, 175), thereby taking up less space in a traffic signal housing and making retrofitting a traditional incandescent lamp traffic signal easier.

Claims

1. A power supply circuit, comprising:

(a) a first rectifier for converting an AC current to DC current;

(b) a starting circuit coupled to the first rectifier for providing a path for the AC current;

(c) a gate drive arrangement coupled to the starting circuit;

(d) a resonant converter circuit regeneratively controlled by the gate drive arrangement; and

(e) a load circuit coupled to a resonant converter circuit for inducing the AC current in the load circuit, the load circuit, comprising;

(1) a resonant inductance;

(2) a resonant capacitance coupled to the resonant inductance; and

(3) a load connected in parallel to the resonant capacitance, the load including,

(i) a group of light emitting elements; and

(ii) a capacitor coupled between the resonant capacitance and the group of the light emitting elements.

2. The circuit of claim 1, wherein the light emitting elements are light emitting diodes.

3. The circuit of claim 1, wherein the light emitting elements are connected in parallel.

4. The circuit of claim 1, wherein the light emitting elements are oppositely polarized.

5. The circuit of claim 1, wherein the light emitting elements are polarized in the same direction.

6. The circuit of claim 1, wherein the load further comprises:

(a) a second rectifier for converting the AC current to DC current, the second rectifier coupled in parallel to the resonant capacitance;

(b) a current limiting inductance coupled between the rectifier and the group of the light emitting elements; and

(c) a diode coupled in parallel to the second rectifier, the second rectifier allowing the DC current to continuously flow through the current limiting inductance.

7. The circuit of claim 1, wherein the group is a pair of the light emitting elements oppositely polarized and connected in parallel.

8. The circuit of claim 1, wherein the group is a pair of branches of the light emitting elements of each branch polarized in the same direction.

9. A power supply circuit, comprising:

(a) a first rectifier for converting an AC current to DC current;

(b) a starting circuit coupled to the rectifier for providing a path for the AC current;

(c) a gate drive arrangement coupled to the starting circuit;

(d) a resonant converter circuit regeneratively controlled by the gate drive arrangement; and

(e) a load circuit coupled to a resonant converter circuit for inducing the AC current in the load circuit, the load circuit, comprising;

(1) a resonant inductance;

(2) a resonant capacitance coupled to the resonant inductance; and

(3) a load connected in parallel to the resonant capacitance, wherein the resonant converter circuit includes, (i) first and second switches serially connected between a bus conductor and a reference conductor by a common node through which the AC current flows, the first and second switches each including a control node and a reference node, a first voltage between each of the control nodes and the common node determining a conduction state of the switches, and (ii) a voltage-divider network which is connected between the bus conductor and the reference conductor.

10. The circuit of claim 9, further comprising a bidirectional voltage clamp is connected between the control nodes and the common node for limiting positive and negative excursions of the first voltage.

11. The circuit of claim 9, wherein the gate drive arrangement comprises a capacitor which limits a rate of change of the first voltage dependent, at least in part, on the size of the capacitor.

12. The circuit of claim 9, wherein the gate drive arrangement comprises a driving inductor mutually coupled to the resonant inductor in such manner that a second voltage is induced therein which is proportional to an instantaneous rate of change of the AC current.

13. The circuit of claim 12, wherein the gate drive arrangement comprises a second inductor serially connected to the driving inductor, the second inductor and driving inductor being connected between the common node and the control node.

14. The circuit of claim 9, wherein the starting circuit comprises:

(a) three resistors, the first and second resistors coupled in parallel to the first rectifier and the third resistor coupled in parallel to one of the first and second switches; and

(b) a blocking capacitor coupled between each of the control nodes and the common node.

15. The circuit of claim 9, further comprising a snubber capacitor, the snubber capacitor shunting the first switch.

16. The circuit of claim 9, further comprising a snubber capacitor, the snubber capacitor shunting the second switch.

17. A power supply circuit for light emitting elements, comprising:

(a) a resonant load circuit incorporating the light emitting elements and including a resonant inductance, a resonant capacitance, and a capacitor;

(b) a DC-to-AC converter circuit coupled to the resonant load circuit for inducing an AC current in the resonant load circuit, the converter circuit comprising;

(1) first and second switches serially connected between a bus conductor at a DC voltage and a reference conductor, and being connected together at a common node through which the AC current flows;

(2) the first and second switches each comprising a reference node and a control node, the voltage between such nodes determining the conduction state of the associated switch;

(3) the respective reference nodes of the first and second switches being interconnected at the common node; and

(4) the respective control nodes of the first and second switches being directly interconnected;

(c) an inductance connected between the control nodes and the common node;

(d) a starting pulse-supplying capacitance connected in series with the inductance, between the control nodes and the common node;

(e) a network connected to the control nodes for supplying the starting pulse-supplying capacitance with charge so as to create a starting pulse; and

(f) a polarity-determining impedance connected between the common node and one of the bus conductor and the reference conductor, to set the initial polarity of pulse to be generated by the starting pulse-supplying capacitor.