HK40009274A - Power over ethernet emergency lighting system - Google Patents

Description

Ethernet power supply emergency lighting system

Cross Reference to Related Applications

The application is a divisional application of an invention patent application with the filing date of 2016, 3 and 17, and the filing number of 201680001641.6, and the title of the invention is power over ethernet emergency lighting system and a method for detecting power loss of a link section of the power over ethernet emergency lighting system.

This application claims the benefit of U.S. provisional patent application No. 62/135,006 entitled "POWER OVER ETHERNET EMERGENCY LIGHTING SYSTEM (POWER OVER ethernet emergency lighting system)" filed 3/18/2015, the entire contents of which are incorporated herein by reference for all purposes.

Technical Field

The present invention relates to emergency lighting systems, and more particularly to providing an emergency lighting system powered by a power over ethernet ("POE") system.

Background

Lighting systems, particularly in commercial environments, are subject to a number of stringent functional requirements set by various standards-setting organizations. One of these requirements is: emergency lighting should be provided in the event of loss of building power. These mandatory emergency power systems must provide backup lighting for a predetermined period of time, must be tamper-resistant, fire-resistant, flood-resistant, and earthquake-resistant, and must meet certain other functional requirements. Conventionally, emergency lighting systems are provided as self-contained units installed in light fixtures, the emergency lighting systems including batteries charged by a dedicated a/C power line.

The promulgation of the IEEE standard for power over ethernet ("POE") in conjunction with the ubiquity of RJ45 ethernet cables in modern commercial and residential buildings provides an alternative to architectural lighting. There are currently two approved IEEE standards for POE: IEEE 802.3af and IEEE 802.3 at. An ethernet port operating in accordance with the IEEE 802.3af standard is capable of supplying 12.95 watts to a powered device ("PD") over a POE link. IEEE 802.3at defines the POE + standard, which enables delivery over POE links up to 25.5W. Efforts are currently underway to promulgate more advanced POE standards (e.g., POE + and POE + +), which will specify devices capable of supplying up to 90W over a POE link.

A POE link implementing physical connection over Cat5+ ethernet cable according to one of two alternatives is schematically illustrated in fig. 1. As can be seen in fig. 1, the RJ45 ethernet cable 105 carries 8 conductors grouped into 4 twisted pairs (110a, 110b and 115a, 115b), where two twisted pairs (e.g., 110, 115) form the communication link (transmit and receive) of the first port and the remaining two twisted pairs may be idle (e.g., 115a, 115 b). In alternative a, a DC voltage is supplied on the data line across a center tap on an internal signal coupling transformer (120a, 120b) connected across the pair of conductors on each of the transmit and receive twisted pairs. The DC voltage is then supplied from the center tap of the other pair of transformers (125a, 125b) across the receive side twisted pair of transmit and receive lines. This DC voltage is supplied to a Powered Device 130 on the receiving end of the link. In alternative B of the POE standard, the DC voltage is supplied over an unused or spare twisted pair. Newer and proposed POE standards provide more power and faster data by using all 8 conductors. These methods require 4 data converters, where power is applied to all pairs.

In recent years, LED lighting has begun to replace fluorescent lighting in commercial environments as cost has decreased and the efficiency of light emitting diodes ("LEDs") has increased. Fig. 2 is a schematic representation of a conventional LED lighting fixture powered by a POE link (or more precisely, an ethernet cable referred to under the POE standard as a port data link segment). The 48V DC rating is supplied over a link by a Power Sourcing Equipment ("PSE") 205 (e.g., a POE switch, hub, or midspan injector). Power is superimposed onto the data transmission line pair of ethernet link segments (e.g., 210a, 210b) carried on the CATnx (e.g., Cat 5+) cable. The link segment (210a, 210b) supplies power to a powered end device (PD, e.g., POE luminaire lighting LED driver 220), where the power is intelligently extracted (i.e., separated from data) at the PD. Power extraction occurs at POE lighting LED driver 220, which appears to the PSE as any conventional PSE operating according to the POE standard. Power is then delivered by the driver 220 to the LED lamp 225. In some conventional implementations, the driver 220 and the LED lamp 225 are co-located in an LED light fixture 215 mounted at a ceiling light fixture, for example.

In a typical AC power system, certain light fixtures (i.e., light fixtures) are designated as also emergency light fixtures that must maintain illumination in the event of a loss of AC power in accordance with code and accepted building practices. The lamp has all necessary lamp components; for example, a light source (lamp, such as an LED), a ballast, or a lamp power supply (such as an LED driver), etc. If the luminaire is also used to act as an emergency luminaire, it is equipped with additional hardware enabling it to drive all or part of the light source (i.e. lamp) for emergency lighting in emergency mode operation (a condition triggered by loss of AC power). Thus, existing lamps in these light fixtures are used for both normal lighting when AC power is supplied and for lighting in emergency mode operation when normal AC power fails.

Disclosure of Invention

The present invention relates to an emergency lighting fixture powered by a POE network connection, for example deployed in an existing POE lighting environment. Embodiments of the invention include an ethernet link segment that enables a first power source, a rechargeable emergency battery pack, a normal lighting LED driver, an LED lamp, and a power loss monitor. In some embodiments, the first power enabled ethernet connection is to a POE port link segment. Further, a rechargeable emergency battery pack containing a battery charger, a rechargeable battery, and an emergency LED driver is connected to one input of the relay device. Furthermore, the other input of the relay device is electrically connected to a normal lighting LED driver (which drives the LED lighting array under normal operating conditions), and the output of the relay device is connected to the LED lamp.

Embodiments of the present invention further include a power loss monitor that determines whether power is being supplied by a normal lighting LED driver or whether there has been a power interruption. When the power loss monitor detects a loss of power from the normal lighting LED driver, a controller connected to the power loss monitor connects one input of the relay device to the LED lamp. However, when the normal LED driver has power, the other input of the relay device is connected to the LED lamp.

In some embodiments, the emergency lighting fixture further comprises a second POE input connectable to the power POE port link segment. When the first POE input is connected to the battery charger, the second POE input is connected to the normal lighting LED driver. Further, the first and second POE inputs are included in an emergency battery pack, the emergency battery pack further including a POE output connected to the second POE input by a pass-through loop. The POE output is also connected to the normal lighting LED driver. In other embodiments, the power loss monitor communicates with the normal lighting POE link pass-through loop.

In some embodiments, the relay device adapted to form an electrical connection between the battery and the LED lighting array (or the stand-alone emergency LED array) is an electromechanical switch.

In certain embodiments, the POE emergency luminaire includes a battery charged by a port link segment that is completely separate from the port link segment that drives normal lighting. In other embodiments, the system includes a battery that is charged with DC power via an auxiliary power output interface from the normal lighting LED driver, itself driven by a single POE port link segment. In other embodiments, a single POE port link segment supplies power to an emergency backup battery pack, which then supplies normal lighting power via a power bridge.

In certain embodiments, the power loss monitor is connected to a first conductor on a first POE data pair of a POE port link segment, and the power loss monitor is connected to a second conductor on a second data pair of the same POE port link segment. The power loss monitor can determine when a POE port link segment loses power without interfering with data communications on that link segment. In other embodiments, the power loss monitor further comprises an optocoupler, a resistor, and a zener diode. The power loss monitor adjusts the current flowing through the LED of the optocoupler based on whether the voltage difference between the first conductor and the second conductor exceeds a predetermined threshold. Further, the power loss monitor includes a ferrite bead capable of filtering connected between the rectifying diode bridge and the first and second conductors. Furthermore, the first and second conductors are connected to the POE link segment via the first power over ethernet input.

Embodiments of the present invention also provide a system for providing emergency backup power in a POE luminaire having a connection to a POE link segment, a lamp driver and a lamp. The system further includes a power loss monitor connected to detect loss of POE power in the POE link segment, and an emergency backup battery and lamp driver connected to supply power to the lamp when the power loss monitor detects loss of POE power in the POE link segment.

Further, an embodiment of the present invention provides a method for detecting power loss in a POE link segment, including: a differential DC voltage is detected between a first conductor in a first data pair on a POE link segment and a second conductor in a second data pair on the same POE link segment. In some embodiments, the step of detecting the differential DC voltage comprises: the current decrease is detected by the measurement device when the differential DC voltage between the first conductor in the first data pair on the POE link segment and the second conductor in the second data pair on the same POE link segment falls below a predetermined threshold.

Drawings

The present invention will be more fully understood by reference to the following detailed description, taken in conjunction with the accompanying drawings, which are incorporated in the detailed description below.

Fig. 1 is a schematic diagram of a conventional power over ethernet link.

Fig. 2 is a schematic diagram of a conventional LED-based POE lighting system.

Fig. 3 is a schematic diagram of a POE emergency lighting fixture with two POE port links, according to an embodiment of the invention.

Fig. 4 is a schematic diagram of an emergency POE battery pack for use with the lighting fixture of fig. 3.

Fig. 5 is a schematic diagram of a POE emergency lighting fixture using an auxiliary power link, in accordance with an embodiment of the invention.

Fig. 6 is a schematic diagram of an emergency POE battery pack for use with the lighting fixture of fig. 5.

Fig. 7 is a schematic diagram of a POE emergency lighting fixture using a port power bridge, in accordance with an embodiment of the invention.

Fig. 8 is a schematic diagram of an emergency POE battery pack for use with the lighting fixture of fig. 7.

Fig. 9 is a schematic diagram of a POE interface according to the present invention.

Fig. 10 is a circuit diagram of a power loss monitor according to an embodiment of the invention.

Detailed Description

The following sets forth a detailed description of a preferred embodiment of the invention.

Reference throughout this specification to "one embodiment," "an embodiment," "a related embodiment," or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment," "in an embodiment," and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment. It is to be understood that no part of this disclosure (both by itself and in possible connection with the accompanying drawings) is intended to provide a complete description of all of the features of the invention.

Further, the following disclosure may describe features of the invention with reference to the corresponding figures, in which like numerals represent the same or similar elements whenever possible. In the drawings, the structural elements depicted are generally not to scale, and certain features are exaggerated relative to other features for purposes of emphasis and understanding. It is to be understood that no single drawing is intended to support a complete description of all the features of the invention. In other words, a given figure typically only describes some of the features of the invention and typically not all of the features of the invention. For purposes of simplifying a given figure and discussion, and to direct the discussion to specific elements that are features in this figure, a given figure and associated portion of the invention that includes the description made with reference to this figure typically do not include all of the elements of the particular view or all of the features shown in this figure. One of ordinary skill will recognize that the invention may be practiced without the specific features, elements, components, structures, details, or characteristics, or with other methods, components, materials, and so forth. Thus, although specific details of an embodiment of the invention may not necessarily be shown in each figure describing this embodiment, the presence of such details in the figures may be implied unless the context of the description requires otherwise. In other instances, well-known structures, details, materials, or operations may not be shown or described in detail in a given figure in order to avoid obscuring the ongoing aspects of the embodiments of the invention.

Fig. 3 shows an emergency POE lighting fixture 300 using two POE port link segments 305a, 305 b. The lighting fixture 300 comprises two POE inputs 310a, 310b, each connected to a POE port link segment 305a, 305b, respectively. POE port link segments 305a, 305b are connected to non-illustrated power sourcing equipment, such as POE enabled devices, hubs or midspans (i.e., injectors). Both POE input 310a and POE input 310b are electrically connected to POE emergency battery pack 315. The battery pack 315 includes a POE interface 320 connected to the first POE port link segment 310a via the input 305 a. The battery pack 315 also includes a battery charger 325, a battery 330, and an LED driver 335. The POE interface 320 extracts DC power (e.g., supplied as 48Vdc) from the POE port link segment 310a and then supplies the power to the battery charger 325. The battery charger 325 steps down the voltage supplied by the POE interface 320 and performs certain current regulation functions.

An exemplary POE interface suitable for use as POE interface 320 is shown in additional detail in fig. 9. POE interface 900 of fig. 9 performs several functions. First, it extracts DC power from the RJ45 connector 905 via the center taps of the data converters 910a, 910b, both connected to the primary side of the POE link segment. Further, the POE interface is used to separate the data flow 915 from the power flow, and to couple both data and power to the application 920 (i.e., the functional components of the PD that contains the POE interface). POE interface 900 includes RJ45 connector 905, data transformers with primary center taps 910a and 910b, bridge rectifier(s) 925, signature circuit 930, classification circuit 935, intelligent switching over-current isolation "active switches" with gating FETs 940, and DC/DC isolated power converter 945.

When POE interface 900 draws DC power from the RJ45 connector via the center tap of data transformers 910a, 910b, the power is coupled to input diode bridge 925, which prevents the circuits within the PD from connecting to the opposite polarity input voltage by accepting either a positive polarity input or a negative polarity input. Power is then "intelligently" supplied by the PSE (connected on the other side of the POE link segment) to the PD via a communication protocol through the "physical" (PHY) layer conforming to the IEEE 802.3xx standard. DC power is supplied by the PSE at a nominal target voltage of 48 Vdc. The "power on" process follows the following sequence: wherein once the PD is connected to the end of the POE link segment via RJ45 connector 905, the PSE starts to boost the voltage from 0Vdc with predetermined levels, timing and current detection based on the IEEE 802.3xx standard. The sequence follows from left to right, from signature to sort to DC/DC to application. The first phase of the sequence (detection) of the power supply sequence occurs when the PSE polls the connected PD to determine whether it provides the correct impedance signature. The PSE is done by ramping the current limit (5mA) detection value (from 2.5V to 10V) across the designated CAT-x pair (at a repetition rate of about 2 ms) and measuring the voltage and current at the end of the ramp time. If the PSE detects the proper signature impedance according to the IEEE 802.3xx standard, it determines that a valid PD is present at the end of the link. The PSE then proceeds to the next step in the process, classification. Classification is the process by which the PD "indicates" to the PSE the required range of power that it will need. There are 5 categories (classes). In the classification process, the PSE induces 15.5Vdc-20.5Vdc limited to 100mA for a period of 10ms to 75ms, in response to which is some current consumption of the PD, indicating its power level. The sequence proceeds to the next step as the PSE ramps up the voltage to 34Vdc and the PD "closes" the switch that is "on" (gated FET in 940) but slowly controls inrush current consumption (over 350 mA) within 50ms once this step is completed, the PSE ramps up the voltage to 48Vdc for the DC/DC isolated power converter 945 to supply power to the application 920. The application 920 of fig. 3 for POE emergency battery packs is the battery charger 325.

Battery charger 325 is a high frequency switched mode power supply designed to manage battery charging based on battery capacity, size, terminal voltage, type, and other factors of influence relative to energy usage and regional duration rules or limitations. In some embodiments, the battery charger 325 is a "flyback" topology high frequency mode switching current source type with isolation of analog to digital control. Other topologies are used in other embodiments to better manage the selected battery, such as a "buck" converter or a "buck-boost" converter, or other topologies, and the power supply or over-current over-voltage power supply may be used during the charging process, pulsed or linear charging, constant rate or multiple rates. The battery charger 325 may be designed to charge different types of batteries, such as NiCd, NiMH, Pb-based, or lithium-based. When the battery 330 is a NiCd battery, the battery charger 325 is a "smart charger" capable of supplying 1 to 3 watts of power during the rechargeable phase, supplying 1 watt during maintenance mode charging. In normal operation, the battery charger 325 provides a trickle charge to the battery 330 (supplied at a nominal current range of between 1.2Vdc to 20Vdc and 30mA to 300 mA; however these voltage and current values depend on the type of battery 330, battery pack design, and state of charge).

The battery 330 supplies DC power to the LED driver 335 at 2.4Vdc to 24Vdc (most typically 6Vdc to 19.2Vdc depending on the type of LED light fixture 345). In certain embodiments, battery 330 is a rechargeable NiCd battery with a reserve capacity of 2.5 to 3.0 amp-hours at 6Vdc to 19.2 Vdc. Other embodiments use other cell types, such as NiCd cells with a reserve capacity of 1.5 to 4.0 hours at 2.4Vdc to 24Vdc (1.2 Vdc/cell) or lithium ion phosphate (LiFePO4) cells with a reserve capacity of 0.5 to 3.0 ampere hours at 3.0Vdc to 3.6 Vdc/cell.

In certain embodiments, the LED driver 335 is a switched-mode power converter that powers the LED lamp(s) with power (energy/time) provided by the battery 330 and supplies a rated 0.08A to 2.0A DC current in the 10Vdc to 60Vdc voltage range to the LED lamp 345 via the relay device 340. The LED current supplied in these embodiments is only a DC current or a DC current with low AC ripple.

In an alternative embodiment, LED driver 335 is a DC-DC "flyback" topology high frequency switching mode power supply with Pulse Width Modulation (PWM) control (digital or analog) when adjusting the output voltage or current or power supply. In these embodiments, the PWM current is delivered through the LED. Other topologies are used in other embodiments, such as "Buck" or "Buck-boost" converters, or half-bridge or full-bridge converters, or other topologies. Typical LED power levels for emergency mode operation range from 3 to 25 watts, with other power levels being possible. For class 2 operation, typical LED voltages range from 10Vdc to 60Vdc, with other voltages also possible.

Depending on the embodiment, the LED lamp 345 varies in operating voltage, current, power supply, and light output. Typical LED lamps for LED fixtures are provided over a large area illumination voltage range from 10Vdc to 60Vdc for class 2 and over a large range of different types over a higher voltage range for non-class 2. The LED fixture lamp array & module operates over a wide range of current levels from 0.08Adc to 3 Adc. Depending on the embodiment, the color temperature of the LED lamp 345 ranges from 2500K (warm white) to 6000K (bright white).

In one embodiment, the relay device 340 is an electromechanical switch that alternately couples one of two inputs (341 connected to the emergency battery pack 315 or 342 connected to the normal lighting LED driver 350) to the LED lamp 345. The use of an electromechanical switch as the relay device 340 is advantageous because it causes near zero insertion loss of the battery pack 315, i.e. when the battery pack 315 is not connected, the normal lighting LED driver 350 is connected to the LED lamp 345 having the smallest resistance. The invention or any embodiment is not limited to electromechanical switches as relay devices, alternative relay devices (such as diodes or solid state switches or other types) are possible and within the scope of the invention.

Via the normal lighting POE input 355, the POE power link segment 305b is electrically connected to the normal lighting LED driver 350 through the second POE input 305b of the battery pack. The normal lighting LED driver 350 includes a POE interface 360 that extracts the DC power (i.e., 48Vdc) available on the second POE link segment 310b and supplies it to the LED driver 365. Like the emergency LED driver 335, the LED driver 365 has different operating parameters according to embodiments. In one embodiment, the LED driver 365 is optimized for operating over a wide range of voltages from 10Vdc to 60Vdc for class 2 and higher voltages for non-class 2. Such drivers can operate over a wide range of current levels from 0.08Adc to 3 Adc. POE power levels are currently limited to about 55 watts, however, additional higher power LED drivers and higher power luminaires are possible and within the scope of the invention, each allowed up to nearly 90 watts through future development. The LED driver 365 is electrically connected to an input of the relay device 340 through an output 370 and then to the LED lamp 345 depending on the status of the relay device 340.

In normal lighting operation, the LED lamp 345 is driven from a normal lighting LED driver 350, which draws DC power from the power link segment 305b (supplied in a pass-through manner by the emergency battery pack 315). The emergency battery pack 315 further comprises a power loss monitor 375 that monitors the state of power supplied to the second POE input 305b by monitoring a pass-through loop 380 between the second POE input 305b and a POE output 385. The POE output 385 is in turn connected to the normal lighting driver POE input 355.

When the luminaire 300 of fig. 3 is in the normal lighting mode, the relay device 340 is arranged such that its second input 342 is electrically connected to the LED lamp 345. This produces a current supplied to the LED lamp 345 from the normal LED lighting driver 350. As will be further discussed with respect to the battery pack of fig. 4, when the power loss monitor 375 detects a power outage condition on the pass-through loop 380, the relay device 340 switches state such that its first input 341 is connected to the emergency LED driver 335 to the LED lamp 345.

The luminaire described with respect to fig. 3 has certain advantages. Since the luminaire uses two separate POE link segments (one for charging the backup battery and the other for driving the LED lamp under normal lighting conditions), the luminaire of fig. 3 minimizes the possibility of damaging or otherwise interfering with the fidelity of the data sent or received over the second POE link segment 305 b. This may be helpful if link segment 305b is used for communication as well as the supply of DC power. Moreover, existing lighting and building codes (e.g., NFPA 70 national power code, NFPA 101 life safety code, and UL 924 standard for safety emergency lighting and power supply equipment) require that unswitched power supplies (i.e., normal lighting power supplies) should be monitored at entry points of the luminaire for emergency backup lighting. This is done in the luminaire of fig. 3, since a power loss is detected at the input 310b to the luminaire 300. This arrangement is also advantageous because it locates all of the important components of the emergency light fixture within the fixture, which minimizes the risk of a disaster that could cause failure of the emergency lighting fixture due to tampering, smoke, flooding, fire, freezing, vandalism, or other adverse conditions.

Fig. 4 schematically illustrates an emergency battery pack 400 that may be used for a luminaire having two independent POE links (e.g., luminaire 300 discussed above with reference to fig. 3). Battery pack 400 includes two POE inputs (one for battery charging 410a and a second for powering normal operating conditions 410b) that are passed through battery pack 400 to POE output 485. The charging POE input is connected to POE interface 420, which extracts DC power from the connected POE link and supplies that power to battery charger 425. The battery charger 425 charges the battery 430 under normal operating conditions. The battery 430 supplies an LED driver 435 that is connected to a first input 441 of a relay device 440, which in some embodiments is an electromechanical switch. The relay device 440 alternately connects either its first input 441 or its second input 442 to an output 443 that is electrically coupled to an LED lamp, not shown. A second input 442 of the relay device 440 is connected to an input 444 that receives normal lighting power from the normal lighting LED driver when the battery pack 400 is installed.

The battery pack 400 of fig. 4 also includes a power loss monitor 475 that detects a loss of power on the pass-through loop 480. Upon detection of a loss of power by the power loss monitor 475, the controller 490 (which in some embodiments is a microprocessor in communication with a memory not shown) toggles the relay device 440 so that its first input 441 is connected to the output 443 of the battery pack. The controller 490 includes additional functionality in some embodiments. For example, upon detection of a power loss condition, the controller may send a signal via the I/O ports 495a, 495b to external or internal signaling or indication devices indicating that a power loss condition is detected. In certain embodiments, the controller 490 sends a shuffle signal to one of the ports 495a, 495b upon detecting a loss of normal lighting power. In some embodiments, the disarrangement signal illuminates an LED to alert the user that the emergency lighting system has been activated. In some embodiments, the controller 490 sends additional data communication signals to the ports 495a, 495b that are connected to other external devices (e.g., connected to the ports 495a, 495b through ethernet links). Such signals may inform the remote ethernet connection device of the status of the battery pack 400, the occurrence of a power loss condition, and any other useful information. The controller 490 also optionally receives input control signals via the ports 495a, 495 b. Exemplary input control signals include test signals for stimulating a power loss condition in order to test the functionality of the battery pack 400 or status queries of the controller 490. In certain embodiments, the controller 490 communicates with other external devices, such as a normal lighting LED driver (e.g., 350 in fig. 3) or a data logger.

FIG. 5 is a schematic diagram of an alternative embodiment of a light fixture using an emergency lighting battery pack fed by an auxiliary power supply derived from a normal lighting LED driver. Unlike the embodiment of fig. 3, the embodiment of fig. 5 relies only on a single POE port link segment 505, which supplies DC power (and in some embodiments, data communications) to the normal lighting LED driver 510 through the POE input 515. As in the embodiment of fig. 3, POE interface 520 extracts DC power from POE link segment 505 and supplies it to LED driver 520. Under normal lighting operating conditions, the LED driver 525 supplies drive current to the LED lamp 585 via the driver output 530 and the first input 582 of the relay device 580, as will be described in greater detail in connection with the battery pack 550.

The embodiment of fig. 5 also includes a battery pack 550 for supplying emergency power to the LED lamp 585 in the event of a power loss condition of a normal LED lighting driver. Like the embodiment of fig. 3, the battery pack 550 includes a battery charger 565 that charges a battery 570 that drives an LED driver 575. The output of the LED driver 575 is connected to a first input 581 of a relay device 580, which alternately connects its first or second input 581, 582 to the LED lamp 585, so that the power supply can be switched from the normal lighting LED driver 530 to the battery pack 550 in the event that a normal lighting power loss condition is detected.

Unlike the embodiment of fig. 3, the luminaire 500 of fig. 5 does not use two POE link segments. Instead, a single port method is enabled by extracting a low level of DC power from the normal lighting power supplied to the normal lighting LED driver 510 by the auxiliary power output interface 535. After POE interface 520 has separated the data flow domain from the power flow (or at any point before or after the interface in other implementations), power is extracted from POE fed DC power coupled to auxiliary power output interface 535. In one embodiment, DC power (0W to 3W) is extracted at a rated POE voltage of 48Vdc (range of 36Vdc-57 Vdc) on the POE input 515 to the driver 510 and supplied to the battery pack 550 via the output 540, the auxiliary power link 545 and the power input 555. The DC power interface converter 560 controls (i.e., by limiting inrush current, bi-directionally filtering noise, and buffering) the 48Vdc power supply feeding the supplied power to operate the battery charger 565.

With this arrangement, in one embodiment, the input voltage of the battery charger 565 is a nominal 48Vdc (a range of 36Vdc-57 Vdc). In the same embodiment, the output voltage of the battery charger 565 typically floats to the nominal battery voltage of the battery 570 (9.6 Vdc +/-20% fully charged), or V for only certain other batteries_{Battery _ float}. In other embodiments the charger is capable of supporting other battery voltages in a typical range between 2.4Vdc and 24 Vdc. The battery charging current ranges from 0.0Adc (no charging current) up to 1C depending on the charging level, time, application and battery type, where C is the battery charging capacity equivalent current expressed in Adc. The C values supported by embodiments of the present invention include 1.2A, 1.5A, 2A, 2.2A, 2.5A, 3A, 3.5A, 4A, where C ═ 3A is most typical for POE lighting.

The input of LED driver 575 is coupled to battery 570 at +/-20% of the battery's nominal terminal voltage and ranges to 1V/battery cell at the end of the discharge cycle. In a typical embodiment, a typical battery voltage for a full charge is approximately 9.6Vdc for an 8-cell NiCd battery. The input current to LED driver 575 depends on battery voltage, output power, and efficiency. A typical input current for LED driver 575 is approximately 1.7Adc for a 9.6Vdc battery voltage.

For emergency mode operation, the LED driver 575 is connected to a first input 581 of the relay device 580, which is connected to an LED lamp 585. The LED driver 575 is capable of driving the LED lamp 585 over a wide range of voltages from 10Vdc to 60Vdc for class 2 (and a larger voltage for non-class 2), and over a wide range from 0.08Adc to 2Adc, where higher current levels are possible in the future. POE power levels are currently limited to about 55 watts, however, each allowed up to nearly 90 watts through future developments.

In the embodiment of fig. 5, the loss of normal lighting power is detected by a power loss monitor 590 in the battery pack 550. In this embodiment, a loss of power at the normal lighting LED driver 510 (e.g., because power has been lost on POE port link segment 505) causes a loss of power on the auxiliary power link 545, such that the loss of power can be detected at the battery pack 550. This maintains the advantages of the system described with reference to fig. 3, where power may be lost at any point to the light fixture without affecting the functionality of the emergency lighting system.

As in the embodiment of fig. 4, battery pack 550 includes a controller 595 that switches at least relay device 580 in response to detecting a power loss condition. The controller 595 optionally has additional functionality in additional embodiments, which is described more fully below with reference to fig. 6.

Fig. 6 schematically illustrates an emergency battery pack 600 that may be used for a luminaire having one POE port link segment (e.g., luminaire 500 discussed above with reference to fig. 5). Like the battery pack described in fig. 4, the battery pack 600 includes a controller 655, but also includes I/O ports 665a, 665b for bi-directional communication with external devices, for example, for receiving test signals and status queries and for transmitting status data and clutter signals in a power loss condition.

Fig. 7 schematically illustrates a POE standby luminaire 700 according to another embodiment of the present invention. In the embodiment of fig. 7 (like the embodiment of fig. 5), the luminaire receives power over a single POE port link segment 702. Unlike the embodiment of fig. 5, POE link segment 702 is first connected directly to battery pack 705. The POE port interface with integral power bridge ("IIPB") 715 draws low level DC power to provide to battery charger 720 that charges battery 725 to supply power to the LED driver to drive LED lamp 750 in a power loss condition as already described.

The IIPB 715 operates to provide an isolated data link, and a DC power link from the link segment 702 to the normal lighting LED driver. The IIPB also draws or bridges a low level amount of power from link segment 702 to battery charger 720. From a system level perspective, link segment 702 is a dedicated link segment for normal lighting purposes, data or power on a single link segment. The IIPB 715 enables this single use usage to be maintained while the power supply is also used to power the battery charger 720. According to the IEEE 802.xx POE standard, power is provided from the PSE normal power source to the normal lighting LED driver 705 via link segment 702, which supports active and intelligent communication between the PSE normal power source and the normal lighting LED driver 705. The IIPB 715 is an intelligent power extractor that extracts low level power from the normal lighting POE link segment in order to provide power to the battery charger 720 in such a way that data communication or power flow between the PSE and the normal lighting driver 705 is not disturbed or disturbed. Each POE port link segment is intended to be a dedicated link between the PSE and the PD (in this case, the normal lighting LED driver). The IIPB is transparent in this process and does not communicate over POE port link segment 702.

As in the previous embodiment, the controller 747 detects a power loss condition and switches the relay device 740 to connect the battery 725 to the LED lamp 750. Unlike in the previously described embodiment, a power loss condition is detected in the battery pack 705. Power loss monitoring is a shared function, where initial monitoring is concentrated within the IIPB 715 and additionally supported by the electronic control 747.

Fig. 8 schematically illustrates an emergency battery pack 800 with a power bridge 810 available for a luminaire with one POE port link segment connected to input 805. Such a light fixture may be used as a battery pack in, for example, light fixture 700 discussed above with reference to fig. 7. Like the battery pack depicted in fig. 4 and 6, battery pack 800 includes controller 840, but also includes I/O ports 845a, 845b for bi-directional communication with external devices, such as for receiving test signals and status queries, and for transmitting status data and confusion signals in a power loss condition.

Fig. 10 illustrates a pair of power loss monitors, each of which may be used with the power loss monitor 375 described above with reference to fig. 3. Fig. 10 shows two circuits: 1005, which detects a loss of power on port 1 (between pin 1 and pin 3) of the attached RJ45POE cable 1015; and 1010, which detects a loss of power on port 2 (between pin 4 and pin 7) of the same cable. In the discussion that follows, reference will be made primarily to port 1 circuit 1005, which involves circuit components R22, D21-D24, D25, D26, U4, U5, FB5, and FB 6; however, it should be understood that the discussion applies equally to the adjacent circuitry 1010 of port 2.

As explained above with respect to fig. 1, power extraction in POE typically occurs on the data converters (e.g., 125a and 125b in fig. 1) of the power receiving end devices, specifically from the "center tap" of the twisted pair transformer winding (PD data converter primary). As shown in fig. 1, these terminations (referenced to RJ45 connectors) are pin sets (1, 2-3, 6) and (4, 5-7, 8). Turning now to fig. 3, since the luminaire of fig. 3 uses two separate POE links (a separate dedicated emergency link for battery charging and a separate link for the normal lighting LED driver), access to the PD data converter (e.g., located at POE interface 360) for the normal lighting POE link is not provided for the power loss monitor (e.g., 375). Embodiments of the present invention address this problem by recognizing that the POE voltage is DC and has the same value (ideally) on each of such pin pairs. I.e. V_{Pin 1}＝V_{Pin 2}And V_{Pin 3}＝V_{Pin 6}And the like. Therefore, rated voltage V_{Pin 1}-V_{Pin 3}+/-48 Vdc. Likewise, the rated voltage V_{Pin 2}-V_{Pin 6}+/-48 Vdc. Likewise, the rated voltage V_{Pin 4}-V_{Pin 7}+/-48 Vdc. Likewise, the rated voltage V_{Pin 5}-V_{Pin 8}+/-48 Vdc. Termination circuitry across any of these pin pairs (i.e., any pin pair in which each pin is associated with its own twisted pair in the cable) is then used to measure and detect power on a given port. Minimal data disturbance can be achieved because the generated dc current i _ monitor is relatively low and is a common mode dc signal.

One novel advantage of the method and system for detecting POE power loss is: noise and interference are minimized by the DC current being applied only differentially between two pairs of groups (differentially across the power supply terminals, not across any one digital data pair). A low level DC current is applied as a common mode current for each data pair, but differentially between data pair groups. The data pairs are only responsive to differential signals within the pair and reject common mode signals. Also, for each twisted pair, the data signal is in AC differential mode; thus, AC interference to the data signal is minimized by the "non-differential mode" of the i _ monitor, which is instead a common mode DC across the set of groups. Also, this power loss monitor connection method is valid for both alternatives a or B shown in fig. 1.

In the circuit of fig. 10, port power "on" or "off" is detected by the optocoupler U5 (or similarly U6 on port 2), where the digital signal-port power "on" state at the time of output signal causes the current in the optocoupler to be sufficient to drive the output transistor of the optocoupler to the "on" state. Optocouplers are "high gain" devices where a minimum current through the input LED of the optocoupler is desired, which allows power detection with very low power. In addition, the optocoupler U5 provides galvanic isolation (isolating functional parts of the power system to prevent direct current flow) which prevents noise interference between circuits to the greatest extent.

In the circuit of fig. 10, current is provided through the optocoupler U5 via the bridge rectifier 915 so that the power loss monitor is compatible with each of the possible polarity implementations (see D21-D24 of the circuit 1005 of fig. 10).

As shown, the circuit of fig. 10 includes two zener diodes (D25, D26) connected in series to an optocoupler U5. A first zener diode D25 is connected in series with the input LED of the optocoupler, which provides the desired current only when the port input operating voltage exceeds the breakdown voltage (Vb) of D25, thereby providing a voltage reference device. When the voltage across D25 exceeds its Vb value, D25 "turns on" and passes current according to the familiar zener diode I-V curve, such that the current increases sharply as the voltage continues to rise above Vb. In the arrangement of figure 10, when the POE port input operating voltage rises from 0Vdc to a nominal value of 48Vdc, the component values are selected so that at the desired port voltage, the circuit turns "on" sharply, allowing current to flow and then increasing in amplitude when the input port voltage exceeds Vb. In this way, the POE power supply "on" threshold voltage (minimum input operating voltage of 37Vdc) is measured and a circuit response is initiated. Those of ordinary skill in the art will appreciate that integrated circuits and programmable devices may be readily used to implement zener diode D25 and its functionality.

As can be seen in fig. 10, the circuit additionally and optionally includes a series resistor R22, an input LED of the optocoupler, and the two series zener diodes D25, D26. The zener diode total breakdown voltage (along with the two zener diode Vb values) is selected to set the circuit response (the point at which the digital output of the optocoupler U5 changes state). Thus, the circuit comprising the series resistor R22, the optocoupler, and the two series zener diodes (D25 and D26) forms a functional analog to digital converter.

The circuit of fig. 10 additionally and optionally includes certain features that provide hysteresis. Hysteresis is a time-based function of the system output with respect to current and past input variables. Dependencies arise because the history affects the value of the internal state. In order to predict its future output state, its internal state or its history must be known. In the circuit of fig. 10, the "noise immunity" becomes depleted continuously when the input voltage reaches the circuit "threshold voltage", where the output state change according to the input voltage level becomes extremely unstable. The design of fig. 10 provides sufficient hysteresis values to suppress circuit response instability and ambiguity.

The circuit of fig. 10 includes isolated hysteresis sub-circuits (including components D26, U5) and a feed from a power monitoring control circuit, not shown, for example, contained in the controller described above. Isolation is achieved by using an optical coupler U5. Hysteresis is achieved by setting the "on" voltage level higher than the "off voltage level. An exemplary method of accomplishing this, implemented in one embodiment of the present invention, is to first divide the total breakdown voltage Vb _ total of the zener diodes into two separate zener diodes (D25 and D26). The breakdown voltage Vb _ D26 is a small fraction of the total voltage; also, Vb _ D26< Vb _ D25. When the port input voltage rises from 0Vdc to 48Vdc (with the circuit "on" threshold voltage set at 37Vdc), the optocoupler responds with a circuit response by changing the digital state on its output transistor. The output of the optocoupler U4 feeds a monitor and control circuit, which is then coupled back to the power loss monitor via the optocoupler U5 in the form of information feedback. The output of U5 (transistor) is connected to bypass zener diode D26. When U5 transitions from the state "off" to "on," its output transistor diverts current around D26, dropping the D26 zener voltage to near zero volts. The overall breakdown voltage of the zener diode is thus reduced by the value of Vb _ D26. The circuit "threshold" voltage is reset to a lower voltage (30Vdc), referred to as the "falling input voltage". The output state of the optocoupler U4 will not change state until the input voltage drops and decreases by less than 30 Vdc. The differential voltage between the "on voltage" (37Vdc) and the "off voltage" (30Vdc) is 7V and is referred to as the hysteresis voltage.

The power loss monitor circuit of fig. 10 also includes features for attenuating crosstalk and filtering noise. The ferrite beads FB5& FB6 were placed such that they acted as low pass filters, attenuating high frequency noise energy. They are actually series inductors in the circuit. Thus, the ferrite beads block high frequency currents, thereby enabling attenuation of high frequency noise coupled into the data pairs.

While the preferred embodiments of the present invention have been illustrated in detail, it should be apparent that modifications and adaptations to those embodiments may occur to one skilled in the art without departing from the scope of the present invention.

Claims (17)

1. A power over ethernet emergency battery pack comprising: a battery charger, a rechargeable battery, and an emergency LED driver connected to a first input of a relay device having first and second inputs alternately switchable to an output;

a power loss monitor configured to detect a loss of power at a first POE port link section of a connection, wherein the power loss monitor is connected to a controller configured to connect a first input of the relay device to an output of the relay device when the power loss monitor detects a loss of power at the first POE port link section of the connection,

wherein the power loss monitor is connected to a first conductor on a first POE data pair of a POE port link segment and the power loss monitor is connected to a second conductor on a second data pair of the same POE port link segment, and wherein the power loss monitor detects a voltage difference between the DC voltage on the first conductor and the second conductor.

2. The battery pack of claim 1, further comprising a first POE input connected between the first POE port link segment and the power loss monitor.

3. The battery pack of claim 2, further comprising a POE output.

4. The battery pack of claim 3, wherein the POE output is connected to the first POE input by a pass-through loop, and wherein the power loss monitor is configured to detect a loss of power on the pass-through loop.

5. The battery pack of claim 2, wherein the first POE input is connected to the battery charger.

6. The battery pack of claim 1, further comprising a second POE input connected between a second POE port link segment and the battery charger.

7. The battery pack of claim 1, wherein the relay device is an electromechanical switch.

8. The battery pack of claim 1, wherein the relay device is a solid state device.

9. The battery pack of claim 1, wherein the battery charger receives DC power over a single POE link segment.

10. The battery pack of claim 1, further comprising an integral POE port interface comprising an integral power bridge with POE outputs.

11. The battery pack of claim 1, wherein the power loss monitor includes a connection between the first and second conductors and a rectifying diode bridge.

12. The battery pack of claim 11, wherein the power loss monitor further comprises an optocoupler, a resistor, and a zener diode connected to and arranged with respect to the rectifying diode bridge such that current flows through an LED of the optocoupler when a voltage difference between the first conductor and the second conductor exceeds a predetermined threshold.

13. The battery pack of claim 11, wherein the power loss monitor further comprises an optocoupler, a resistor, and a zener diode connected to and arranged with respect to the rectifying diode bridge such that an amount of current is prevented from flowing through the LED of the optocoupler when the voltage difference between the first conductor and the second conductor is below a predetermined threshold.

14. The battery pack of claim 11, wherein the power loss monitor further comprises a ferrite bead filter.

15. The battery pack of claim 1, wherein the first and second conductors are connected to the first POE link segment through a first POE input.

16. A power loss monitor configured to detect a loss of power at a first connected POE port link segment, wherein the power loss monitor is connected to a first conductor on a first POE data pair of a POE port link segment, and the power loss monitor is connected to a second conductor on a second data pair of the same POE port link segment, wherein the power loss monitor detects a voltage difference between a DC voltage on the first conductor and the second conductor.

17. An apparatus for switching power in a POE lighting system, comprising a relay device and a power loss monitor, wherein the power loss monitor is configured to detect a loss of power at a first POE port link section of a connection, wherein the power loss monitor is connected to a controller configured to connect a first input of the relay device to an output of the relay device when the power loss monitor detects a loss of power at the first POE port link section of the connection,

wherein the power loss monitor is connected to a first conductor on a first POE data pair of a POE port link segment and the power loss monitor is connected to a second conductor on a second data pair of the same POE port link segment, and wherein the power loss monitor detects a voltage difference between the DC voltage on the first conductor and the second conductor.