Patent Publication Number: US-2019191508-A1

Title: Solid-State Lighting With Multiple Control Voltages

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present disclosure is part of a continuation-in-part (CIP) application of U.S. patent application Ser. No. 16/247,456, filed 14 Jan. 2019, which is part of CIP application of U.S. patent application Ser. No. 16/208,510, filed 3 Dec. 2018, which is part of CIP application of U.S. patent application Ser. No. 16/154,707, filed 8 Oct. 2018, which is part of a CIP application of U.S. patent application Ser. No. 15/947,631, filed 6 Apr. 2018 and issued as U.S. Pat. No. 10,123,388 on 6 Nov. 2018, which is part of a CIP application of U.S. patent application Ser. No. 15/911,086, filed 3 Mar. 2018 and issued as U.S. Pat. No. 10,136,483 on 20 Nov. 2018, which is part of a CIP application of U.S. patent application Ser. No. 15/897,106, filed 14 Feb. 2018 and issued as U.S. Pat. No. 10,161,616 on 25 Dec. 2018, which is a CIP application of U.S. patent application Ser. No. 15/874,752, filed 18 Jan. 2018 and issued as U.S. Pat. No. 10,036,515 on 31 Jul. 2018, which is a CIP application of U.S. patent application Ser. No. 15/836,170, filed 8 Dec. 2017 and issued as U.S. Pat. No. 10,021,753 on 10 Jul. 2018, which is a CIP application of U.S. patent application of Ser. No. 15/649,392 filed 13 Jul. 2017 and issued as U.S. Pat. No. 9,986,619 on 29 May 2018, which is a CIP application of U.S. patent application Ser. No. 15/444,536, filed 28 Feb. 2017 and issued as U.S. Pat. No. 9,826,595 on 21 Nov. 2017, which is a CIP application of U.S. patent application Ser. No. 15/362,772, filed 28 Nov. 2016 and issued as U.S. Pat. No. 9,967,927 on 8 May 2018, which is a CIP application of U.S. patent application Ser. No. 15/225,748, filed 1 Aug. 2016 and issued as U.S. Pat. No. 9,743,484 on 22 Aug. 2017, which is a CIP application of U.S. patent application Ser. No. 14/818,041, filed 4 Aug. 2015 and issued as U.S. Patent No. 9,420,663 on 16 Aug. 2016, which is a CIP application of U.S. patent application Ser. No. 14/688,841, filed 16 Apr. 2015 and issued as U.S. Pat. No. 9,288,867 on 15 Mar. 2016, which is a CIP application of U.S. patent application Ser. No. 14/465,174, filed 21 Aug. 2014 and issued as U.S. Pat. No. 9,277,603 on 1 March 2016, which is a CIP application of U.S. patent application Ser. No. 14/135,116, filed 19 Dec. 2013 and issued as U.S. Pat. No. 9,163,818 on 20 Oct. 2015, which is a CIP application of U.S. patent application Ser. No. 13/525,249, filed 15 Jun. 2012 and issued as U.S. Pat. No. 8,749,167 on 10 June 2014. Contents of the above-identified applications are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     Technical Field 
     The present disclosure relates to light-emitting diode (LED) luminaires and more particularly to an LED luminaire with multiple control voltages to change a light level of the LED luminaire and to measure some operating parameters in response to commands received from a wireless luminaire controller. 
     Description of the Related Art 
     Solid-state lighting from semiconductor LEDs has received much attention in general lighting applications today. Because of its potential for more energy savings, better environmental protection (with no hazardous materials used), higher efficiency, smaller size, and longer lifetime than conventional incandescent bulbs and fluorescent tubes, the LED-based solid-state lighting will be a mainstream for general lighting in the near future. Meanwhile, as LED technologies develop with the drive for energy efficiency and clean technologies worldwide, more families and organizations will adopt LED lighting for their illumination applications. In this trend, the potential safety concerns such as risk of electric shock and fire become especially important and need to be well addressed. 
     In today&#39;s retrofit applications of an LED lamp to replace an existing fluorescent lamp, consumers may choose either to adopt a ballast-compatible LED lamp with an existing ballast used to operate the fluorescent lamp or to employ an alternate-current (AC) mains-operable LED lamp by removing/bypassing the ballast. Either application has its advantages and disadvantages. In the former case, although the ballast consumes extra power, it is straightforward to replace the fluorescent lamp without rewiring, which consumers have a first impression that it is the best alternative. But the fact is that total cost of ownership for this approach is high regardless of very low initial cost. For example, the ballast-compatible LED lamps work only with particular types of ballasts. If the existing ballast is not compatible with the ballast-compatible LED lamp, the consumer will have to replace the ballast. Some facilities built long time ago incorporate different types of fixtures, which requires extensive labor for both identifying ballasts and replacing incompatible ones. Moreover, the ballast-compatible LED lamp can operate longer than the ballast. When an old ballast fails, a new ballast will be needed to replace in order to keep the ballast-compatible LED lamps working. Maintenance will be complicated, sometimes for the lamps and sometimes for the ballasts. The incurred cost will preponderate over the initial cost savings by changeover to the ballast-compatible LED lamps for hundreds of fixtures throughout a facility. In addition, replacing a failed ballast requires a certified electrician. The labor costs and long-term maintenance costs will be unacceptable to end users. From energy saving point of view, a ballast constantly draws power, even when the ballast-compatible LED lamps are dead or not installed. In this sense, any energy saved while using the ballast-compatible LED lamps becomes meaningless with the constant energy use by the ballast. In the long run, the ballast-compatible LED lamps are more expensive and less efficient than self-sustaining AC mains-operable LED lamps. 
     On the contrary, AC mains-operable LED lamps do not require a ballast to operate. Before use of the AC mains-operable LED lamps, the ballast in a fixture must be removed or bypassed. Removing or bypassing the ballast does not require an electrician and can be replaced by end users. Each of AC mains-operable LED lamps is self-sustaining. Once installed, the AC mains-operable LED lamps will only need to be replaced after 50,000 hours. In view of above advantages and disadvantages of both the ballast-compatible LED lamps and the AC mains-operable LED lamps, it seems that market needs a most cost-effective solution by using a universal LED lamp that can be used with the AC mains and is compatible with a ballast so that LED lamp users can save an initial cost by changeover to such an LED lamp followed by retrofitting the lamp fixture to be used with the AC mains when the ballast dies. Moreover, the AC mains-operable LED lamps consume less power than ballast compatible LED lamps do because extra power consumed by the ballast is saved. 
     To further save lighting energy cost, the lighting industry proposed to use daylight harvesting years ago. In daylight harvesting, the ambient light such as natural daylight and an artificial light present in a space is utilized to reduce overhead lighting. When a sufficient ambient light level is present or when the space is unoccupied, a control mechanism in a daylight harvesting system dims or switches off the artificial light in the system. The daylight harvesting system is typically designed to maintain a recommended light level, which varies depending on activity needs in the space. For instance, the commonly recommended light level for normal office work, study library, personal computer work, groceries, show rooms, and laboratory is 500 lux on the desktop, whereas in warehouses and homes, the recommended light level is 250 lux. 
     The daylight harvesting system uses a photo-sensor to detect a prevailing light level in an open-loop or a closed-loop manner. The photo-sensor is used to adjust light level from electric lighting based on the available daylight in the space. In an open-loop system, the photo-sensor is used to detect the amount of available daylight only and can be positioned on the building&#39;s exterior wall or roof, or inside the building facing the window or skylight. In a closed-loop system, the photo-sensor is used to measure total photometric amount of light, from both daylight and electric lighting in the space. For instance, in an office, a closed-loop photo-sensor can be positioned on the ceiling facing the desktops in order to detect the amount of light on the work surface. In both the open- and closed-loop configurations, the signal from the photo-sensor must be calibrated to accurately show the effect of exterior daylight variations on the light level for activities in the space. 
     Studies have shown that by using daylight harvesting technologies, owners can have an average annual energy savings of 24%. Even with such a potential energy saving, some of daylight harvesting systems still cannot be widely accepted. In fact, impressive energy savings estimates may not be realized in practice due to a poor system design, a time-consuming calibration, or a complicated commissioning. High costs and imperfect performance of the technologies also inhibit the adoption of daylight harvesting technologies. 
     The AC mains-operable LED luminaires can easily be used with a wireless lighting control system, taking advantages of no rewiring needed for wireless control. No wiring or rewiring can save dramatic installation cost, and such a lighting control system is free of the wiring errors in contrast to an all wired system that is highly susceptible to such errors. With the acceleration of LED luminaire deployment in the lighting industry, the needs of energy saving, utilization efficiency of lighting energy, and intelligent control of lighting have become very urgent. Traditional luminaire controls have drawbacks such as no scheduling possible for manual switch control, susceptibility of the interference by the strong magnetic field from a power line for power carrier control, and failing to meet the requirements of centralized monitoring, recording, and energy management. On the other hand, the lighting industry needs control systems that can program different lighting schedules across multiple zones based on shifts or the type of work occurring throughout the day. Moreover, users can dim individual lights or adjust light levels for any area in buildings and streets or scheduling for more energy savings. It is, therefore, a motive to design such an LED luminaire incorporating a cost-effective remote wireless control that is simple to implement without commissioning in the field. 
     SUMMARY 
     An LED luminaire comprises one or more LED arrays, a full-wave rectifier configured to convert a line voltage from the AC mains into a first direct-current (DC) voltage, an input filter configured to suppress electromagnetic interference (EMI) noise, a power switching driver, an electric current controller, and a detection and control circuit. The power switching driver comprises a power factor correction (PFC) and control circuit and a transformer having a primary side relative to a first ground reference and a secondary side relative to a second ground reference. The power switching driver is coupled to the full-wave rectifier via the input filter and configured to convert the first DC voltage into a second DC voltage. The power switching driver further comprises a first rectifier and a first at least one output capacitor. The first rectifier and the first at least one output capacitor are configured to build up the second DC voltage to operate the electric current controller to drive the one or more LED arrays. The electric current controller comprises at least one current sensing resistor and an enable input. The electric current controller is configured to convert the second DC voltage into a third DC voltage with an output current driving the one or more LED arrays. The at least one current sensing resistor is coupled in series with the one or more LED arrays and configured to convert the output current driving the one or more LED arrays into an error control voltage sent to the electric current controller to control a current flowing into and out of the one or more LED arrays. 
     The electric current controller further comprises a diode, a second electronic switch, a second at least one output capacitor, and an inductor. The diode, the second electronic switch, the second at least one output capacitor, and the inductor are configured to build up the third DC voltage and to provide the output current driving the one or more LED arrays in response to a controllable feedback signal voltage. The second electronic switch comprises a transistor, a metal-oxide-semiconductor field-effect transistor (MOSFET), or a combination thereof. 
     The detection and control circuit comprises a voltage regulator, a voltage comparator circuit, and a pair of low-voltage input/output ports receiving an external voltage V BB′ . The detection and control circuit is configured to extract the controllable feedback signal voltage from the external voltage V BB′  and to couple the controllable feedback signal voltage to the electric current controller to change the output current driving the one or more LED arrays. The voltage regulator comprises at least one transistor and a voltage divider circuit coupled to the at least one transistor. The at least one transistor and the voltage divider circuit are configured to regulate the second DC voltage into a fourth DC voltage to operate the voltage comparator circuit. The voltage regulator circuit further comprises a Zener diode configured to control the at least one transistor to provide the fourth DC voltage to operate the voltage comparator circuit. 
     The voltage comparator circuit comprises a first comparator circuit configured to compare a DC voltage coupled from the fourth DC voltage with the external voltage, partially controlling the controllable feedback signal voltage. The first comparator circuit comprises a first comparator, a resistor, and a first electronic switch coupled to the first comparator. The first comparator, the resistor, and the first electronic switch are configured to pull down the controllable feedback signal voltage when the external voltage V BB′  is less than the fourth DC voltage. Specifically, when the external voltage V BB′  is a zero voltage, the first comparator outputs a relatively high voltage, immediately controlling the first electronic switch to pull down the controllable feedback signal voltage to a minimum. The first comparator circuit further comprises a voltage divider circuit configured to provide a second voltage reference to appear at the pair of low-voltage input/output ports when the pair of low-voltage input/output ports are floating. The first comparator circuit further comprises at least one integrator circuit configured to average out a pulse-width modulation (PWM) signal inputted from the external voltage V BB′ . 
     The voltage comparator circuit further comprises a second comparator circuit configured to build up a first voltage reference. The voltage comparator circuit further comprises a third comparator circuit comprising a third comparator. The third comparator circuit is configured to receive an integrated signal from both the external voltage V BB′  and the fourth DC voltage, to compare the integrated signal with the first voltage reference, and to partially control the controllable feedback signal voltage. The electric current controller further comprises a PWM generator and a fourth comparator. The fourth comparator is configured to receive the controllable feedback signal voltage via the enable input and to enable the PWM generator to tune the output current driving the one or more LED arrays in response to the controllable feedback signal voltage. 
     The external voltage V BB′  comprises control signals received from a wireless luminaire controller. The wireless luminaire controller comprises a wireless module configured to communicate with a gateway by receiving commands of switching, 0-to-10 volts dimming, and metering from the gateway and responding luminaire statuses and metering results to the gateway. The wireless luminaire controller further comprises a meter and control unit receiving commands from the wireless module. The meter and control unit is configured to control the LED luminaire and to measure in response to the commands. The meter and control unit comprises one or more meters configured to measure an AC current, an AC voltage, a temperature, an active power, or a reactive power. The meter and control unit further 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 V BB′ . The wireless luminaire controller further comprises a pair of controlled AC output coupled to the power switching driver. The pair of controlled AC output is configured to turn on or shut off the AC power to the power switching driver. The meter and control unit further comprises a photo control configured to overwrite commands of the switching and the 0-to-10 volts dimming and to turn on the AC power to the power switching driver when ambient light level is below a predetermined value. The external voltage comprises a nominal DC voltage in a range from 0 to 10 volts. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting and non-exhaustive embodiments of the present disclosure are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various figures unless otherwise specified. 
         FIG. 1  is a block diagram of an LED luminaire with multiple control voltages according to the present disclosure. 
         FIG. 2  is an embodiment of an electric current controller according to the present disclosure. 
         FIG. 3  is a block diagram of the LED luminaire integrated with a wireless luminaire controller according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a block diagram of an LED luminaire  700  with multiple control voltages according to the present disclosure. The LED luminaire  700  comprises one or more LED arrays  214 , a full-wave rectifier  203  connected to a pair of AC power input ports  101  receiving a line voltage from the AC mains, an input filter  102 , a power switching driver  402 , an electric current controller  301 , and a detection and control circuit  501 . The pair of AC power input ports  101  are also denoted as AA′. The input filter  102  is configured to suppress EMI noise. The full-wave rectifier  203  is configured to convert the line voltage from the AC mains into a first DC voltage. The power switching driver  402  comprises a power factor correction (PFC) and control circuit  407  and a transformer  404  having a primary side  405  relative to a first ground reference  255  and a secondary side  406  relative to a second ground reference  256 . The power switching driver  402  is coupled to the full-wave rectifier  203  via the input filter  102  through a power input  430 . The power switching driver  402  is configured to convert the first DC voltage into a second DC voltage. The power switching driver  402  further comprises a first rectifier  411  and at least one output capacitor  412 . The first rectifier  411  and the at least one output capacitor  412  are configured to build up the second DC voltage at an output port  414  to power up the electric current controller  301  and the detection and control circuit  501 . 
     The electric current controller  301  comprises a driving device  302 , at least one current sensing resistor  303 , and an enable input E receiving a controllable feedback signal voltage. The electric current controller  301  receives the second DC voltage from the output port  414  to power up the electric current controller  301  and is configured to convert the second DC voltage into a third DC voltage with an output current driving the one or more LED arrays  214 . The at least one current sensing resistor  303  is coupled in series with the one or more LED arrays  214  and configured to convert the output current driving the one or more LED arrays  214  into an error control voltage sent to the driving device  302  to control a current flowing into and out of the one or more LED arrays  214 . The electric current controller  301  further comprises a diode  304 , a second electronic switch  305 , a second at least one output capacitor  306 , and an inductor  307 . The diode  304 , the second electronic switch  305 , the second at least one output capacitor  306 , and the inductor  307  are configured to build up the third DC voltage and to provide the output current driving the one or more LED arrays  214  in response to the controllable feedback signal voltage. The second electronic switch  305  comprises a transistor, a metal-oxide-semiconductor field-effect transistor (MOSFET), or a combination thereof. 
     In  FIG. 1 , the detection and control circuit  501  comprises the second ground reference  256 , a voltage regulator  510 , a voltage comparator circuit  520 , and a pair of low-voltage input/output ports  570  (also denoted as BB′) receiving an external voltage V BB′ . The second ground reference  256  is the same as the ground reference for the electric current controller  301  and for the secondary side  406  of the transformer  404 . Thus, multiple control signal voltages can be sent single-ended (like “C” and “E” in  FIG. 1 ) among the power switching driver  402 , the electric current controller  301 , and the detection and control circuit  501  because they share the same ground reference  256 . The detection and control circuit  501  is configured to extract the controllable feedback signal voltage from the external voltage V BB′  and to couple the controllable feedback signal voltage to the electric current controller  301  to change the output current driving the one or more LED arrays  214 . The voltage regulator  510  receives the second DC voltage from the output port  414  of the power switching driver  402 , also denoted as C in the detection and control circuit  501 . The voltage regulator  510  comprises at least one transistor  511  and a first voltage divider circuit  512  coupled to the at least one transistor  511 . The at least one transistor  511  and the first voltage divider circuit  512  are configured to regulate the second DC voltage into a fourth DC voltage to operate the voltage comparator circuit  520 . The voltage regulator circuit  510  further comprises a Zener diode  513  and a capacitor  514 . The Zener diode  513  and the capacitor  514  are configured to control the at least one transistor  511  to provide the fourth DC voltage to operate the voltage comparator circuit  520 . 
     In  FIG. 1 , the voltage comparator circuit  520  comprises a first comparator circuit  530  configured to compare a fifth DC voltage coupled from the fourth DC voltage with the external voltage V BB′ , partially controlling the controllable feedback signal voltage. The first comparator circuit  530  comprises a first comparator  531 , a resistor  532 , a first electronic switch  533  coupled to the first comparator  531 , and a second voltage divider circuit  534  configured to set up the fifth DC voltage. The first comparator  531 , the resistor  532 , and the first electronic switch  533  are configured to pull down the controllable feedback signal voltage when the external voltage V BB′  is less than the fourth DC voltage. Specifically, when the external voltage V BB′  is a zero voltage, the first comparator  531  outputs a relatively high-level voltage equivalent to a voltage operating the first comparator, immediately controlling the first electronic switch to pull down the controllable feedback signal voltage to the second ground reference. The second voltage divider circuit  534  is further configured to provide a second voltage reference to appear at the pair of low-voltage input/output ports  570  when the pair of low-voltage input/output ports  570  are floating. The first comparator circuit  530  further comprises at least one integrator circuit  535  comprising a resistor  536  and a capacitor  537  configured to average out a pulse-width modulation (PWM) signal inputted from the external voltage V BB′ . 
     In  FIG. 1 , the voltage comparator circuit  520  further comprises a second comparator circuit  540 . The second comparator circuit  540  comprises a second comparator  541  and a third voltage divider circuit  542 . The second comparator circuit  540  is configured to build up a first voltage reference. The voltage comparator circuit  520  further comprises a third comparator circuit  550  comprising a third comparator  551  and a fourth voltage divider circuit  552 . The third comparator circuit  550  is configured to receive an integrated signal from both the external voltage V BB′  and the fourth DC voltage, to compare the integrated signal with the first voltage reference, and to partially control the controllable feedback signal voltage. As can be seen in  FIG. 1 , the third comparator  551  is connected to the first electronic switch  533 . In other words, both the first comparator circuit  530  and the third comparator circuit  550  control the controllable feedback signal voltage. 
       FIG. 2  is an embodiment of an electric current controller according to the present disclosure. In  FIG. 2 , the electric current controller  301  comprises a driving device  302 , at least one current sensing resistor  303 , an enable input E, and the second ground reference  256 , as depicted in  FIG. 1 . The second ground reference  256  is the same as the ground reference for the secondary side  406  of the transformer  404  in  FIG. 1 . The electric current controller  301  receives the second DC voltage from the port  414  of the power switching driver  402  and is configured to convert the second DC voltage into a third DC voltage with an output current driving the one or more LED arrays  214 . The at least one current sensing resistor  303  is coupled in series with the one or more LED arrays  214  and configured to convert the output current driving the one or more LED arrays  214  into the error control voltage sent to the driving device  302  to control a current flowing into and out of the one or more LED arrays  214 . The electric current controller  301  further comprises a diode  304 , a second electronic switch  305 , a second at least one output capacitor  306 , and an inductor  307 , wherein the diode  304 , the second electronic switch  305 , the second at least one output capacitor  306 , and the inductor  307  are configured to build up the third DC voltage and to provide the output current driving the one or more LED arrays  214  in response to the controllable feedback signal voltage. The second electronic switch  305  comprises a transistor, a metal-oxide-semiconductor field-effect transistor (MOSFET), or a combination thereof. In  FIG. 2 , the driving device  302  further comprises a PWM generator  308  and a fourth comparator  309 , and wherein the fourth comparator  309  is configured to receive the controllable feedback signal voltage via the enable input E and to enable the PWM generator  308  to tune the output current driving the one or more LED arrays  214  in response to the controllable feedback signal voltage. 
       FIG. 3  is a block diagram of the LED luminaire integrated with a wireless luminaire controller according to the present disclosure. In  FIG. 3 , the LED luminaire  700  comprises the pair of AC power input ports  101 , also denoted as AA′, and the pair of low-voltage input/output ports  570 , also denoted as ports BB′. The pair of AC power input ports  101  and the pair of low-voltage input/output ports  570  are connected to a wireless luminaire controller  620 . The wireless luminaire controller  620  comprises a wireless module  621  configured to communicate with a gateway (not shown) by receiving commands of switching, 0-to-10 volts dimming, and metering from the gateway and responding luminaire statuses and metering results to the gateway. The wireless luminaire controller  620  further comprises a meter and control unit  622  receiving commands from the wireless module  621 . The meter and control unit  622  is configured to control the LED luminaire  700  via the pair of AC power input ports  101  and the pair of low-voltage input/output ports  570  and to measure in response to the commands. The meter and control unit  622  comprises one or more meters  623  configured to measure an AC current, an AC voltage, a temperature, an active power, or a reactive power. 
     In  FIG. 3 , the meter and control unit  622  further comprises a power and low-voltage controller  624  configured to control an AC power to deliver to the power switching driver  402  (in  FIG. 1 ) of the LED luminaire  700  via the pair of AC power input ports  101  and to control the external voltage V BB′  via the pair of low-voltage input/output ports  570 . The meter and control unit  622  further comprises a relay  625  controlled by the power and low-voltage controller  624  and a photo control  626  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  402  of the LED luminaire  700  when ambient light level is below a predetermined value. In other words, when ambient light level is below a predetermined value, say 1.5 foot-candle, the photo control  626  instantly controls the power and low-voltage controller  624  to control the relay  625  to immediately turn on the AC power to the LED luminaire  700 . In this case, the wireless luminaire controller  620  may further comprise a pair of controlled AC output  627  coupled to the power switching driver  402  (in  FIG. 1 ) of the LED luminaire  700 . 
     In  FIG. 3 , the wireless luminaire controller  620  further comprises a pair of AC input ports  603  receiving the AC power from the AC mains and a pair of low-voltage output ports  628 . The pair of AC input ports  603  are also denoted as LN whereas the pair of AC output ports  627  are also denoted as L′N. The pair of low-voltage output ports  628  is connected to the pair of low-voltage input/output ports  570  in the LED luminaire  700 . The pair of AC output ports  627  connected to the relay  625  is connected to the pair of AC power input ports  101  in the LED luminaire  700 . When the AC power LN is available, the relay  625  is enabled by the power and low-voltage controller  624  to couple the AC power LN to the pair of AC output ports  627  and to deliver a controlled power to the pair of AC power input ports  101  denoted as AA′ in the LED luminaire  700  providing the controlled power to operate the LED luminaire  700 . 
     In  FIG. 3 , when the AC power LN  603  is available but the command received from the wireless module  621  demands turning off the LED luminaire  700 , the power and low-voltage controller  624  controls the relay  625  to disconnect the AC power LN  603  to the pair of AC output ports  627 , thus completely shutting off the LED luminaire  700  for conserving energy. When the AC power LN  603  is available and the photo control  626  detects ambient light level is lower than a predetermined value, the power and low-voltage controller  624  controls the relay  625  to couple the AC power LN  603  to the pair of AC output ports  627  and to deliver the controlled power L′N to the pair of AC power input ports  101  in the LED luminaire  700  providing the controlled power to operate the LED luminaire  700 . Therefore, the photo control  626  overwrites the command to turn on the LED luminaire  700  for security reasons. On the other hand, when the AC power LN  603  is available and the photo control  626  detects ambient light level is higher than another predetermined value, say 2.25 foot-candle, the power and low-voltage controller  624  controls the relay  625  to disconnect the AC power LN  603  to the pair of AC output ports  627  and to disconnect the controlled power L′N to the pair of AC power input ports  101 , shutting off the LED luminaire  700 . The photo control  626  overwrites the command to shut off the LED luminaire  700  for energy saving. That is to say that the pair of controlled AC output  627  is configured to connect to the pair of AC power input ports  101  and to turn on or shut off an AC power to the power switching driver  402 . The external voltage V BB′  at the pair of low-voltage input/output ports  570  comprises a nominal DC voltage in a range from 0 to 10 volts. 
     Whereas preferred embodiments of the present disclosure have been shown and described, it will be realized that alterations, modifications, and improvements may be made thereto without departing from the scope of the following claims. Another kind of schemes with multiple control voltages adopted in an LED luminaire using various kinds of combinations to accomplish the same or different objectives could be easily adapted for use from the present disclosure. Accordingly, the foregoing descriptions and attached drawings are by way of example only, and are not intended to be limiting.