ELECTRONIC CONTROL GEARS FOR LED LIGHT ENGINE AND APPLICATION THEREOF

• US 20140210351A1
• Filed: 01/26/2014
• Published: 07/31/2014
• Est. Priority Date: 01/31/2013
• Status: Active Grant

• Current Assignee: Groups Tech Co., Ltd.
• Original Assignee: Groups Tech Co., Ltd.
• Inventors: Yu, Ching Sheng, Wang, Chih Liang, Chen, Kuang Hui
• Granted Patent: US 9,107,264 B2
• Time in Patent Office: Days
• US Class Current: 315/122
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices

Abstract

Disclosed are electronic control gears for LED light engines able to improve power factor by way of gearing up or down the LED current and the AC input current in response to and in synchronization with the AC input voltage. Moreover, the disclosed electronic control gears could further reduce flicker phenomenon and total harmonic distortion when used in collocation with disclosed valley fillers, filling the LED current valleys only during the dead time, and in conjunction with disclosed dummy loads, ramping up or down the AC input current only during the dead time.

Claims

1. An electronic control gears for LED light engine comprising:

a rectifier for connecting to an external AC voltage source;

a current regulator connecting to the rectifier; and

a switch regulator chain having a plurality of switch regulators, the switch regulator chain connected to the current regulator and connected in parallel with an external LED array chain, the external LED array chain having a plurality of LED array segments, each of the switch regulators connected in parallel with a corresponding LED array segments except for a last segment of the LED array segment, each of the switch regulators comprising a bypass switch and a detector, a present detector receiving a voltage sense signal or a current sense signal, and a present bypass switch regulates LED current of a lower LED array segment at a preset constant level, wherein the bypass switch is a normally closed electronic switch, the bypass switch is short in normal state when the bypass switch receiving no control voltage or the control voltage is zero, wherein

when an input voltage is insufficient to forward-bias lower LED array segment, a present bypass switch remains in on state to short out the present LED array segment;

when the input voltage is high enough to forward-bias the lower LED array segment but fails to forward-bias the present LED array segment, the present bypass switch regulates LED current of the lower LED array segment at a preset constant level; and

when the input voltage is high enough to forward-bias the present LED array segment, the present bypass switch is shut off as an off state.

2. The electronic control gears for LED light engine according to claim 1, wherein the bypass switches is an n-channel depletion-mode metal-oxide-semiconductor field-effect transistor (MOSFET) or an n-channel depletion-mode junction gate field-effect transistor (JFET).

3. The electronic control gears for LED light engine according to claim 1, wherein the detector is a current detector, a voltage detector, an optical detector, a magnetic detector or a comparator.

4. The electronic control gears for LED light engine according to claim 1, wherein the detector is a voltage detector, and the voltage detector comprises a voltage divider connected to two terminals of at least one LED in the lower LED array segment, a partial or full forward voltage drop of the at least one LED sensed by the voltage divider is provided to the present bypass switch as a driving voltage.

5. The electronic control gears for LED light engine according to claim 1, wherein the detector is a current detector, and the current detector comprises a voltage divider, an npn bipolar junction transistor (npn BJT) and a detecting resistor, the detecting resistor is wired to the next segment of the LED array segment, a base terminal and an emitting terminal of the npn BJT are wired to two terminals of the detecting resistor, the voltage divider is connected between the lower LED array segment and a collector of the npn BJT, the divided voltage of the voltage divider is provided to the current segment of the bypass switch as a driving voltage.

6. The electronic control gears for LED light engine according to claim 1, wherein the detector is a current detector comprising a voltage divider, a shunt regulator and a detecting resistor, the detecting resistor is wired to the lower LED array segment, an anode and a reference node of the shunt regulator are wired to two terminals of the detecting resistor, the voltage divider is connected between the lower LED array segment and a cathode of the shunt regulator, a divided voltage of the voltage divider is provided to the present bypass switch as a driving voltage.

7. The electronic control gears for LED light engine according to claim 1, wherein the current regulator comprises a MOSFET and is connected to an npn BJT, and the npn BJT is used for controlling the MOSFET to switch on or off.

8. The electronic control gears for LED light engine according to claim 1, wherein the current regulator comprises a MOSFET and is connected to a shunt regulator, the shunt regulator is used for controlling the MOSFET to switch on or off.

9. The electronic control gears for LED light engine according to claim 1, further comprising a valley filler connected to the rectifier, wherein the valley filler fills up valleys of an LED current waveform during a dead time, and wherein the valley filler comprises a first diode, a second diode, a first energy storage capacitor, a second energy storage capacitor, and a programmable constant current source, and wherein the programmable constant current source comprises a transistor, a third diode, a first resistor, an npn BJT and a second resistor, wherein the programmable constant current source is connected between the first energy storage capacitor and the second energy storage capacitor, wherein when the input voltage is higher than a first energy storage capacitor voltage and a second energy storage capacitor voltage, the first energy storage capacitor and the second energy storage capacitor are charged in series with a first preset constant current, when the input voltage is lower than the first energy storage capacitor voltage and the second energy storage capacitor voltage, the first energy storage capacitor and the second energy storage capacitor are discharged in parallel with a second preset constant current.

10. The electronic control gears for LED light engine according to claim 1, further comprising a valley filler connected to the rectifier, wherein the valley filler fills up valleys of an LED current waveform during a dead time, and wherein the valley filler comprises a first energy storage capacitor, a second energy storage capacitor, a first diode, and a programmable constant current source, the programmable constant current source comprises a transistor, a first resistor, an npn BJT, and a second resistor, wherein the programmable constant current source is connected between the first energy storage capacitor and the second energy storage capacitor, wherein when the input voltage is higher than a first energy storage capacitor voltage and a second energy storage capacitor voltage, the first energy storage capacitor and the second energy storage capacitor are charged in series with a first preset constant current, when the input voltage is lower than the first energy storage capacitor voltage and the second energy storage capacitor voltage, the first energy storage capacitor and the second energy storage capacitor are discharged in series with a second preset constant current.

11. The electronic control gears for LED light engine according to claim 1, further comprising a valley filler connected to the rectifier, wherein the valley filler fills up valleys of an LED current waveform during a dead time, and wherein the valley filler comprises an energy storage capacitor and a programmable constant current source connected to the energy storage capacitor, the programmable constant current source comprises a transistor, a first resistor, an npn BJT and a second resistor.

12. The electronic control gears for LED light engine according to claim 1, further comprising a dummy load connected to the rectifier and connected between a positive terminal and a negative terminal of the rectifier, and wherein the dummy load comprises:

a voltage divider;

a shunt regulator, connected to the voltage divider;

a controlled switch, connected to the shunt regulator;

a resistive load, connected to the controlled switch; and

a pull-up resistor, connected to the controlled switch.

13. The electronic control gears for LED light engine according to claim 1, wherein the electronic control gears for LED light engine is integrated onto an integrated circuit, or the electronic control gears for LED light engine is separated into a plurality of modules to be integrated onto a circuit board.

14. An LED lighting equipment, comprising:

the electronic control gears for LED light engine according to claim 1; and

an LED array chain, wherein the LED array chain is connected in parallel with the electronic control gears for LED light engine.

15. An integrated circuit of an electronic control gears for LED light engine, comprising:

a rectifier used for connected to an external AC power source;

a current regulator connected to the rectifier; and

a switch regulator chain having a plurality of switch regulators connected in series, the switch regulator chain being connected to the current regulator and in parallel with an external LED array chain, the external LED array chain having a plurality of LED array segments connecting in series, each of the switch regulators is connected in parallel with a corresponding one of the LED array segments, each of the switch regulators having a bypass switch and a detector, the detector detecting a lower LED array segment to switch a present bypass switch, and the bypass switches being normally closed electronic switches, the bypass switches being short in normal state when the bypass switch receiving no control voltage or the control voltage is zero, wherein

when an input voltage is insufficient to forward-bias lower LED array segment, a present bypass switch remains in on state to short out the present LED array segment;

when the input voltage is high enough to forward-bias the lower LED array segment but fails to forward-bias the present LED array segment, the present bypass switch regulates LED current of the lower LED array segment at a preset constant level; and

when the input voltage is high enough to forward-bias the present LED array segment, the present bypass switch is shut off as an off state.

16. The integrated circuit of an electronic control gears for LED light engine according to claim 15, further comprising a valley filler wired to the rectifier to fills up valleys of an LED current waveform during a dead time, wherein the valley filler comprises an energy storage capacitor and a programmable constant current source, wherein the programmable constant current source is electrically connected to the energy storage capacitor to control a charging current and a voltage of an energy storage capacitor.

17. The integrated circuit of an electronic control gears for LED light engine according to claim 15, further comprising a dummy load connected to the rectifier and connected between a positive terminal and a negative terminal of the rectifier, wherein the dummy load comprises:

a resistive load; and

a controlled switch connected to the resistive load in series, wherein the resistive load draws a line current during a dead time, and the controlled switch cuts off the resistive load during non-dead time.

18. An LED lighting equipment, comprising:

the integrated circuit of an electronic control gears for LED light engine according to claim 15; and

an LED array chain, wherein the LED array chain is connected in parallel with the integrated circuit of the electronic control gears for LED light engine.