Solid-state lighting with an interface between an internal control voltage and an external voltage
An LED luminaire comprises a power converter, a power switching driver, LED array(s) powered by the power switching driver, and a voltage detection circuit. The voltage detection circuit comprises a first voltage detection circuit, a second voltage detection circuit, a voltage regulator circuit, an optocoupler circuit, and a pair of low-voltage input ports receiving an external voltage. The voltage detection circuit is configured to extract a flyback signal from an output voltage and the external voltage and to couple the flyback signal to the power switching driver. The external voltage comprises a voltage sent from a Zigbee luminaire controller, which comprises a Zigbee module and a meter and control unit. The Zigbee luminaire controller is configured to receive commands from the Zigbee module, to control the LED luminaire, and to measure in response to the commands.
1. A light-emitting diode (LED) luminaire, comprising:
one or more LED arrays;
a power converter configured to convert a line voltage from alternate-current (AC) mains into a first direct-current (DC) voltage;
a power switching driver comprising a transformer having a primary side relative to a first ground reference and a secondary side relative to a second ground reference, a power factor correction (PFC) and control circuit, and a flyback control input, the power switching driver coupled to the power converter and configured to convert the first DC voltage into a second DC voltage with an output current driving the one or more LED arrays; and
a voltage detection circuit comprising a first voltage detection circuit, a second voltage detection circuit, a voltage regulator circuit, an optocoupler circuit, and a pair of low-voltage input/output ports receiving an external voltage, the first voltage detection circuit and the second voltage detection circuit respectively configured to extract a flyback signal from the second DC voltage and the external voltage and to couple to the power switching driver;
wherein:
the optocoupler circuit comprises an LED and a photo-detector;
the LED is configured to receive the flyback signal from both the first voltage detection circuit and the second voltage detection circuit and to illuminate the photo-detector;
the photo-detector is configured to receive the flyback signal in an optical form, to convert the flyback signal from the optical form to an electric signal, and to control the power switching driver;
a combination of the LED and the photo-detector is configured to electrically isolate the second ground reference from the first ground reference; and
the flyback control input is configured to receive the electric signal from the photo-detector for the power switching driver to provide the output current driving the one or more LED arrays in response to the flyback signal.
2. The LED luminaire of claim 1 , wherein the first voltage detection circuit comprises a first operational amplifier, a first voltage reference, and a first diode, and wherein the first voltage detection circuit is configured to monitor the second DC voltage and to partially control a current flowing through the LED.
3. The LED luminaire of claim 1 , wherein the second voltage detection circuit comprises a second operational amplifier, a second voltage reference, a voltage divider coupled to the second operational amplifier, and a second diode, and wherein the second voltage detection circuit is configured to monitor the external voltage and to partially control a current flowing through the LED.
4. The LED luminaire of claim 1 , wherein the power switching driver further comprises a first rectifier, at least one output capacitor, and at least one output resistor connected in parallel with the at least one output capacitor, and wherein the first rectifier, the at least one output capacitor, and the at least one output resistor are configured to build up the second DC voltage to drive the one or more LED arrays.
5. The LED luminaire of claim 1 , wherein the power switching driver further comprises a second rectifier connected to a center tap of the transformer, and wherein the second rectifier is configured to provide an unregulated DC voltage.
6. The LED luminaire of claim 5 , wherein the voltage regulator circuit comprises a first voltage regulator circuit comprising a first Zener diode and a transistor coupled to the Zener diode, and wherein the first voltage regulator circuit is configured to receive the unregulated DC voltage and to convert the unregulated DC voltage into a third DC voltage to operate the first operational amplifier and the second operational amplifier.
7. The LED luminaire of claim 6 , wherein the voltage regulator circuit further comprises a second voltage regulator circuit comprising at least one transistor, a third diode, and a second Zener diode, and wherein the second voltage regulator circuit is configured to convert the third DC voltage into a fourth DC voltage and to interface the fourth DC voltage with the external voltage.
8. The LED luminaire of claim 7 , wherein the third diode is configured to control the fourth DC voltage to appear at the pair of low-voltage input/output ports when the pair of low-voltage input/output ports are floating with respect to a voltage level thereof, and wherein the third diode is further configured to control the external voltage to couple to the second voltage detection circuit.
9. The LED luminaire of claim 6 , wherein the third DC voltage is configured to operate the LED in such a way that a control current corresponding to the flyback signal can flow through the LED.
10. The LED luminaire of claim 1 , wherein the power switching driver further comprises a third rectifier configured to provide a fifth DC voltage to operate the photo-detector.
11. The LED luminaire of claim 1 , wherein the power converter comprises a filter configured to reduce ripples at a mains frequency and at twice the mains frequency on the first DC voltage and consequently to improve ripples on both the second DC voltage and the output current driving the one or more LED arrays to emit a light with a lowered flicker rate.
12. The LED luminaire of claim 1 , wherein the external voltage comprises control signals received from a Zigbee luminaire controller.
13. The LED luminaire of claim 12 , further comprising the Zigbee luminaire controller, wherein the Zigbee luminaire controller comprises a Zigbee module configured to receive commands of switching, 0-to-10 volts dimming, and metering and to respond to luminaire statuses and metering results.
14. The LED luminaire of claim 13 , wherein the Zigbee luminaire controller further comprises a meter and control unit configured to receive the commands from the Zigbee module and to control the LED luminaire.
15. The LED luminaire of claim 14 , wherein the meter and control unit comprises one or more meters configured to, in response to the commands, measure an AC current, an AC voltage, a temperature, a frequency, or an active power.
16. The LED luminaire of claim 14 , wherein the meter and control unit comprises a power and low-voltage controller configured to control an AC power to couple to the power switching driver and to control the external voltage.
17. The LED luminaire of claim 16 , wherein the meter and control unit further comprises a first photo control comprising a first relay, and wherein the photo control is configured to overwrite commands of the switching and the 0-to-10 volts dimming and to turn on the AC power to couple to the power switching driver when an ambient light level is below a predetermined value.
18. The LED luminaire of claim 16 , wherein the meter and control unit further comprises a second photo control comprising a second relay, and wherein the second photo control is configured to duplicate the first photo control for preventing failure of the first photo control and to overwrite commands of the switching and the 0-to-10 volts dimming and to turn on the AC power to couple to the power switching driver when an ambient light level is below a predetermined value.
19. The LED luminaire of claim 13 , wherein the Zigbee luminaire controller further comprises a pair of controlled AC outputs coupled to the power switching driver, and wherein the pair of controlled AC outputs is configured to turn on or shut off an AC power to the power switching driver.
20. The LED luminaire of claim 1 , wherein the external voltage comprises a nominal DC voltage in a range from 0 to 10 volts.