Emergency lighting powered by DC source

Abstract

The present invention provides an emergency driver for driving an LED load off a mains voltage or a dedicated emergency LED load off a battery. The emergency driver comprises input terminals for looping an electrical power from output terminals of a mains-powered LED driver through the emergency driver before being supplied to output terminals of the emergency driver. The emergency driver further comprises the output terminals being arranged for supplying the electrical power to an LED light source. The emergency driver is further provided with a charging circuit for charging the battery based on the electrical power looped through the emergency driver. The present invention also provides an emergency lighting driver arrangement comprising a mains-powered LED driver and said emergency driver.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of emergency lighting, specifically to an emergency lighting LED driver. This invention is designed to provide emergency lighting functionalities to LED luminaires, ensuring they remain operational during power outages or other emergency situations.BACKGROUND

[0002] Emergency lighting systems are crucial for ensuring safety and visibility during power outages or emergency situations. Currently, the state of the art in emergency lighting for LED luminaires involves devices that integrate emergency lighting functionalities directly into the LED fixtures. These devices allow LED luminaires to switch to battery power during an outage, ensuring continuous illumination. A typical system includes an AC (alternating current) / DC (direct current) stage that powers essential circuitry, primarily for battery charging. Once the battery is fully charged, this AC / DC stage continues to operate to maintain the control circuitry, which has very low power requirements.

[0003] Despite the advancements, existing emergency lighting systems for LED luminaires exhibit several limitations. In current systems, the AC / DC stage is designed to supply power to the battery charging circuitry and subsequently maintain the control circuitry. However, once the battery is charged, the AC / DC stage is only required to power the control circuitry, which consumes very little power. This results in significant underutilization of the AC / DC stage, leading to inefficiencies. The continuous operation of the AC / DC stage to maintain low-power control circuitry is not energy-efficient. The current design involves maintaining a separate AC / DC stage primarily for battery maintenance, adding complexity and potential points of failure in the system.

[0004] These limitations highlight the need for an improved emergency lighting LED driver that can address these inefficiencies and provide a more reliable and energy-efficient solution.SUMMARY

[0005] In view of the above-discussed limitations, the objective of this invention is to optimize power management and remove the AC / DC stage in emergency lighting systems for LED luminaires.

[0006] These and other objectives are achieved by the solution of this disclosure as described in the independent claims. Advantageous implementations are further defined in the dependent claims.

[0007] According to a first aspect of the invention, an emergency driver for driving an LED load off a mains voltage or a dedicated emergency LED load off a battery is provided.

[0008] The emergency driver comprises input terminals for looping an electrical power from output terminals of a mains-powered LED driver through the emergency driver before being supplied to output terminals of the emergency driver. The emergency driver further comprises the output terminals being arranged for supplying the electrical power to an LED light source. The emergency driver is further provided with a charging circuit for charging the battery based on the electrical power looped through the emergency driver.

[0009] Advantageously, the proposed emergency driver draws a small amount of power directly from the LED to charge the battery, without the need for a specific AC / DC stage. In this way, only the critical circuitry is present, thus increasing the efficiency of the device use and minimizing material and development costs.

[0010] According to an implementation form of the first aspect of the invention, the emergency driver comprises further input terminals for receiving mains voltage information via a non-switched line, and a mains failure detection module connected to the further mains failure input terminals.

[0011] Advantageously, the mains voltage information is supplied via a non-switched line to the emergency driver, thereby allowing the emergency state to be detected.

[0012] According to a further implementation form of the first aspect of the invention, the mains failure detection module is configured to detect an emergency state, wherein the emergency state is detected when the mains voltage fails or an LED load supply is unpowered, and the emergency driver is configured to power the LED light source by discharging the battery upon the detection of the emergency state.

[0013] For instance, the emergency driver can detect the emergency state (and start the emergency lighting operation) by detecting the event that the mains voltage fails. Alternatively, the mains failure detection module can monitor the LED load supply and assume an emergency state when the LED is unpowered. In the emergency state (when the mains voltage fails or when the LED load supply is unpowered), the LED light source is powered by the battery.

[0014] According to a further implementation form of the first aspect of the invention, the emergency driver is configured to charge the battery in a non-emergency state, i.e. a non mains-failure state.

[0015] Advantageously, the charging operation of the battery of the emergency driver is performed by using a fraction of the LED power delivered, in the non-emergency state, by the LED mains driver.

[0016] According to a further implementation form of the first aspect of the invention, the charging circuit comprises a transformer with a primary winding and a secondary winding, wherein the primary and secondary windings are used for both charging and discharging the battery.

[0017] The charging circuit may be understood as a bi-directional driver, or a bi-directional battery charger / discharger.

[0018] According to a further implementation form of the first aspect of the invention, the charging circuit further comprises: a first switch coupled to the primary winding, configured to operate during the charging of the battery to allow energy transfer from the electrical power from the output terminals of the mains powered LED driver to the battery, and a second switch coupled to the secondary winding, configured to operate during the discharging of the battery to allow energy transfer from the battery to the LED load.

[0019] Advantageously, in the non-emergency state, i.e., the non mains-failure state, the first switch may be switched to provide the battery charge. In the emergency state, the second switch may be switched to discharge the battery and provide power to the LED load.

[0020] According to an implementation form of the first aspect of the invention, the charging circuit is configured as an integrated driver, using the same windings for both charging and discharging operations.

[0021] Advantageously, this bi-directional driver, functioning as the charging circuit, operates as an integrated driver by using the same windings for both charging and discharging the battery. This is achieved by incorporating switches on both the primary and secondary sides of the isolated driver.

[0022] According to a further implementation form of the first aspect of the invention, the charging circuit is configured as dedicated drivers, using separate windings for the charging and discharging operations.

[0023] Optionally, other bi-directional driver configurations can be implemented, such as using two dedicated drivers for the charging and discharging operations of the battery.

[0024] According to a further implementation form of the first aspect of the invention, the emergency driver further comprises a connection to an external test switch, and / or a connection to an external LED light indicator.

[0025] Advantageously, the inclusion of a connection for an external test switch allows for easy testing of the emergency lighting system. The connection for an external LED light indicator provides a visual status indicator of the emergency system. Advantageously, with external connections, maintenance personnel can conduct regular checks and troubleshooting without needing to access the internal components of the luminaire.

[0026] According to a further implementation form of the first aspect of the invention, the emergency driver further comprises communication means for receiving a first control signal from a controller, and / or sending a second control signal to the mains powered LED driver.

[0027] Preferably, the control signal (e.g., DALI control signal) is supplied to the emergency driver and if required, it may be further routed to the mains driver.

[0028] According to a further implementation form of the first aspect of the invention, the emergency driver further comprises a control logic, wherein the control logic is configured to determine whether to send the second control signal.

[0029] Advantageously, commands from an external controller are routed via the emergency driver before arriving in the mains driver. This gives the emergency driver the ability to filter or modify any command that could turn OFF the mains driver output and trigger a false emergency event in the emergency driver.

[0030] Additionally, in the event that the battery is not fully charged, the emergency driver requires the LED supply to remain present in order to continue charging the battery. The control logic may ensure that the LED supply remains present to continue charging the battery.

[0031] According to a further implementation form of the first aspect of the invention, determining whether to send the second control signal comprises: routing the first control signal as the second control signal to the mains powered LED driver, bypassing the first control signal and deciding not to send the second control signal, or overriding the first control signal and deciding to send the second control signal.

[0032] For instance, the emergency driver may have the ability to forward, intercept, or override DALI commands from the DALI controller, in cases where those commands go against the driver's needs.

[0033] According to a second aspect of the invention, an emergency lighting driver arrangement is provided. Said emergency lighting driver arrangement comprises a mains-powered LED driver with output terminals for electrical power for driving an LED load off the mains voltage, and an emergency driver for driving said LED load or a dedicated emergency LED load off a battery. The electrical power from the output terminals of the mains-powered LED driver is looped through the emergency driver before being supplied to LED output terminals of the emergency driver. The emergency driver is further provided with a charging circuit for charging the battery based on the electrical power looped through the emergency driver.

[0034] The invention relies on an architecture, where an LED mains driver is supplied with mains voltage and supplies the LED power for the non-emergency operation of the LED lighting means by routing this non-emergency LED power through an emergency driver. Advantageously, the battery for the emergency driver is not charged via a dedicated mains-supplied battery charger. Rather, the charging operation of the battery of the emergency driver is performed by using a fraction of the LED power delivered, in the non-emergency state, by the LED mains driver.

[0035] Implementation forms of the emergency lighting driver arrangement of the second aspect may correspond to the implementation forms of the emergency driver of the first aspect described above. The emergency lighting driver arrangement of the second aspect and its implementation forms achieve the same advantages and effects as described above for the emergency driver of the first aspect and its implementation forms.

[0036] According to a third aspect of the invention, a method for driving an LED load off a mains voltage or a dedicated emergency LED load off a battery is provided. Said method comprises the step of looping an electrical power from output terminals of a mains-powered LED driver through an emergency driver before being supplied to output terminals of the emergency driver, charging the battery based on the electrical power looped through the emergency driver in a non-emergency state, and powering an LED light source with the electrical power in the non-emergency state, or powering the LED light source by discharging the battery in an emergency state.

[0037] According to an implementation form of the third aspect, the method further comprises the step of receiving mains voltage information via a non-switched line, and detecting the emergency state when the mains voltage fails.

[0038] Implementation forms of the method of the third aspect may correspond to the implementation forms of the emergency driver of the first aspect described above. The method of the third aspect and its implementation forms achieve the same advantages and effects as described above for the emergency driver of the first aspect and its implementation forms.

[0039] All steps that are performed by the various components described in this application, as well as the functionalities described to be performed by the various components, are intended to mean that the respective component is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external components is not reflected in the description of a specific detailed element of that component that performs that specific step or functionality, it should be clear to a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof.BRIEF DESCRIPTION OF DRAWINGS

[0040] The above-described aspects and implementation forms are now further explained with respect to the drawings by way of example only, and not for limitation. In the drawings: Fig. 1shows an exemplary emergency driver according to an embodiment of this invention; Fig. 2shows an exemplary charging circuit of the emergency driver according to an embodiment of this invention; Fig. 3shows an exemplary block diagram of the emergency driver according to an embodiment of this invention; Fig. 4shows an exemplary emergency lighting driver arrangement according to an embodiment of this invention; and Fig. 5shows a method according to an embodiment of this invention. DETAILED DESCRIPTION OF EMBODIMENTS

[0041] Illustrative embodiments of an emergency driver, an emergency lighting driver arrangement, and a method are described with reference to the figures. Although this description provides a detailed example of possible implementations, it should be noted that the details are intended to be exemplary and in no way limit the scope of the application.

[0042] An embodiment / example may refer to other embodiments / examples. For example, any description including but not limited to terminology, element, process, explanation, and / or technical advantage mentioned in one embodiment / example is applicable to the other embodiments / examples. The same elements are labeled with the same reference signs and may function similarly or likewise.

[0043] With respect to Fig. 1, an exemplary embodiment of an emergency driver 10 for driving an LED load off a mains voltage 21 or a dedicated emergency LED load off a battery 30, is illustrated.

[0044] In accordance with Fig. 1, the emergency driver 10 comprises input terminals 11 for looping an electrical power from output terminals 22 of a mains-powered LED driver 20 through the emergency driver 10 before being supplied to output terminals 12 of the emergency driver 10. The emergency driver 10 comprises the output terminals 12 being arranged for supplying the electrical power to an LED light source 40. The emergency driver 10 is further provided with a charging circuit 14 (not shown in Fig. 1) for charging the battery 30 based on the electrical power looped through the emergency driver 10.

[0045] The present invention is especially in the field of emergency LED Driver, designed to be attached to a Constant Voltage (CV) DC source or Constant Current (CC) DC source, such as a maintained LED Driver output. Maintained is to be understood that the same (LED) lighting means are used both for emergency lighting and for non-emergency lighting, i.e. lighting while the mains power is still available.

[0046] On maintained applications (i.e., LED light ON while mains power is present), a maintained LED driver is used in conjunction with said emergency LED driver 10. For non-maintained applications (LED light OFF while mains power is present), a DC constant voltage source is used in conjunction with said emergency LED driver 10. It may be understood that a single emergency LED driver device can be adapted for different applications by changing its behavior through various configuration methods, such as, via physical input such as jumper link, voltage input, resistor input, or software configuration.

[0047] The emergency driver 10 draws power from the maintained driver LED output or from the DC voltage source output, to charge the battery and power all auxiliary circuits such as indicators LED or test switches.

[0048] According to the present invention, the AC / DC conversion happens on the maintained driver or DC power source, as well as the galvanic insulation required by emergency lighting standards. The emergency driver 10 contains only the essential circuitry necessary for emergency operation, including a charging circuit, an emergency lamp driver, and, if required, indicator and test switch circuits.

[0049] Notably, the mains voltage information is also supplied via a non-switched line to input terminals 11 of the emergency driver 10, such that the emergency driver 10 can detect the emergency state (and start the emergency lighting operation) by detecting the event that the mains voltage fails. The emergency driver 10 may further comprise a mains failure detection module connected to the further mains failure input terminals 13.

[0050] For instance, the emergency driver 10 can detect the emergency state (and start the emergency lighting operation) by detecting the event that the mains voltage fails. In the emergency state (when the mains voltage fails), the LED light source 40 is powered by the battery 30. Advantageously, the charging operation of the battery 30 of the emergency driver 10 is performed by using a fraction of the LED power delivered, in the non-emergency state, by the LED mains driver 20.

[0051] According to an embodiment of this invention, the charging circuit 14 of the emergency driver 10 may be as shown in Fig. 2.

[0052] In accordance with Fig. 2, the charging circuit 14 comprises a transformer 141 with a primary winding 1411 and a secondary winding 1412, wherein the primary and secondary windings are used for both charging and discharging the battery 30.

[0053] The charging circuit may be understood as a bi-directional driver, or a bi-directional battery charger / discharger. Advantageously, this bi-directional driver, functioning as the charging circuit 14, operates as an integrated driver by using the same windings for both charging and discharging the battery. This may be achieved by incorporating switches on both the primary and secondary sides of the isolated driver.

[0054] Possibly, the charging circuit 14 further comprises a first switch 142 coupled to the primary winding 1411, and a second switch 143 coupled to the secondary winding 1412. The first switch 142 is configured to operate during the charging of the battery 30 to allow energy transfer from the electrical power from the output terminals 12 of the mains powered LED driver 20 to the battery 30. The second switch 143 is configured to operate during the discharging of the battery 30 to allow energy transfer from the battery 30 to the LED load.

[0055] Advantageously, in the non-emergency state, i.e., the non mains-failure state, the first switch 142 may be switched to provide the battery charge as well as the "AUX" supply. When the battery does not need charging, AUX is the only load for the battery charger. In the emergency state, the second switch 143 may be switched to discharge the batter and provide power to the LED load 40. The first and second switches can also be used for synchronous rectification.

[0056] Alternatively, other bi-directional driver configurations can be implemented, such as using two dedicated drivers for the charging and discharging operations of the battery. Fig. 2 merely represents an exemplary charging circuit for the emergency driver 10 and is not intended to limit the scope of the concept.

[0057] Fig. 3 shows a block diagram of the emergency driver 10 according to an embodiment of the invention.

[0058] Notably, the emergency event (failure of mains supply) can be detected by the absence of DC voltage in both the LED maintained driver and the DC voltage source. In the case of dimmable drivers where the LED output current can be completely disabled, an innovative solution is implemented using a dual DALI interface. Here, the external controller communicates directly with the emergency driver via a first DALI channel, while the maintained LED driver communicates with the emergency driver via a second independent channel. This configuration allows commands from the external controller to be routed through the emergency driver before reaching the maintained LED driver. Consequently, the emergency driver can filter or modify any command that could potentially turn off the maintained LED driver output, thereby preventing the triggering of a false emergency event.

[0059] Other emergency functions like Function Test of Duration Test can be triggered and executed by enabling the emergency driver 10 in parallel with the mains-powered LED driver 20. The differential increase of the LED may be monitored by the emergency driver 10 and the function execution is validated.

[0060] It should be understood that Fig. 3 is an exemplary block diagram of the emergency driver 10 and is not intended to limit the scope of the concept. Additional circuitry can be incorporated to provide further functionalities, such as wireless communications or additional communication ports.

[0061] In accordance with Fig. 3, the emergency driver 10 positive input is fed through, directly to the LED 40 (as shown in Fig. 1), with only a switch in line and current sensing in between the input and output. The Switch prevents the unintended flow of current from the emergency output 12 to the LED driver 20 or DC source when in emergency Mode. The switch also prevents currents from flowing directly from the DC voltage source to the LEDs, in cases where the LED voltage is below the DC source voltage. The switch can be enabled by default on start-up and later disabled by the software when the mains controller starts, or vice-versa.

[0062] The LED current sensing block is used to determine the LED power, in conjunction with LED voltage monitoring, when used with maintained LED Drivers. They also can be used for short-circuit and over-current protection. If minimum or maximum power requirements exist, the emergency driver can react based on the values monitored. In the main control algorithm, the LED current sense is also used to determine the maximum power the charger can divert from the LED source, especially when a dimming operation is involved.

[0063] The Battery current sense is used to monitor and control the charging algorithm. The maximum charge current can be a fixed default value, when powered by a DC voltage source or dynamic when powered by and LED maintained driver.

[0064] A controller is necessary to implement the control logic necessary to manage communications, charging process, faults management and indications, and emergency lighting functionalities, such as LED light output, function tests, duration tests, etc.

[0065] A small start-up fixed voltage regulator might be required as these can be used to limit the system start-up currents and limit the input voltage for the controller and driving system power supply (LVPS - low voltage power supply). This regulator can be later shut-down once the charger is, as it is a more efficient system (switch regulation).

[0066] For main emergency lighting functionality, a power stage is essential, comprising a battery charger and an LED lamp driver. These can be combined into a single bi-directional DC / DC converter, as they do not operate simultaneously.

[0067] Indicators and tests switch circuitry can also exist if required, to check emergency lighting functionalities and indications of faults in the system.

[0068] Alternatively, the emergency driver 10 may further comprise a connection to an external test switch, and / or a connection to an external LED light indicator. Advantageously, the inclusion of a connection for an external test switch allows for easy testing of the emergency lighting system. The connection for an external LED light indicator provides a visual status indicator of the emergency system.

[0069] Advantageously, with external connections, maintenance personnel can conduct regular checks and troubleshooting without needing to access the internal components of the luminaire.

[0070] The emergency driver 10 may further comprise communication means 15, as shown in Fig. 4, for receiving a first control signal from a controller, and / or sending a second control signal to the mains-powered LED driver 20.

[0071] Advantageously, the emergency driver 10 may further comprise a control logic, wherein the control logic is configured to determine whether to send the second control signal.

[0072] For instance, in the event that the battery is not fully charged, the control logic ensures that the LED supply remains present to continue charging the battery. This control logic manages the charging process, allowing the battery to reach its full charge capacity. By doing so, the control logic enables the emergency driver to effectively power the LED light source during an emergency state, such as a mains voltage failure. This approach enhances the system's reliability and effectiveness in providing emergency lighting when needed, by coordinating the availability of the LED supply with the battery's charging requirements.

[0073] The embodiment shown in Fig. 4 is based on the embodiment shown in Fig. 1, with the presence of communications capability. In this embodiment, the mains-powered LED driver 20 is controlled (e.g., via DALI) by the emergency driver 10, while the emergency driver 10 communicates directly to an external (DALI) controller.

[0074] For the sake of completeness, it is noted that Fig. 1 and Fig. 4 also depict an exemplary embodiment of a system, namely, an emergency lighting driver arrangement comprising a mains-powered LED driver 20 with output terminals 22 for electrical power for driving an LED load off a mains voltage 21, and an emergency driver 10 for driving said LED load or a dedicated emergency LED load off a battery 30.

[0075] Preferably, the control signal (e.g., DALI control signal) is supplied to the emergency driver 10 and if required, it may be further routed to the mains driver 20.

[0076] A dual-channel DALI input may also exist in systems where DALI communications are required. In particular, the emergency driver 10 may have the capability to communicate over DALI, for instance, with a dual channel system: one channel controls the LED Driver 20 while the second channel interacts with the external DALI controller.

[0077] The DALI controller communicates directly with the emergency driver 10 and DT6 commands and is redirected to the maintained driver 20, via the emergency driver 10, while DT1 commands are executed by the emergency driver 10. Therefore, the emergency driver 10 will have a small application controller to drive the maintained driver 20. The emergency driver 10 will have the ability to intercept or override DALI commands from the DALI controller, in cases where those commands go against the driver's needs, like turning OFF the LED output. In cases where the commands require the power to be reduced or simply turned OFF, the emergency driver 10 can modify the dim level to allow enough power to be delivered to the battery 30 and the remaining correspond to the initially desired LED lighting level.

[0078] Commands to turn OFF the maintained LED driver output can be modified to a low dim level, while the in-line switch is turned OFF to disconnect the LED output, and all the power from the maintained driver 20 is diverted to the emergency driver 10 consumption. A correct dimensioning and selection of the maintained driver 20 is required to maintain this minimum power balance with the emergency driver 10.

[0079] It may be further understood that the proposed emergency driver 10 is a Self-Contained emergency LED driver. Self-contained emergency LED drivers are generally devices integrated into LED lighting fixtures to ensure they continue to operate during a power failure. These drivers have a built-in battery that automatically switches on when it detects a loss of power.

[0080] In one exemplary embodiment, the proposed emergency driver 10 may be attached to a maintained 150W LED Driver. Both the LED Driver's mains supply and LED output go through relays inside the emergency driver 10, giving it the ability to control the instant the LED Driver is powered.

[0081] The Self-Contained emergency drivers have their own AC / DC power supply, a battery charger, an LED Lamp Driver, charging indicators and test switches (to assess the emergency light function) and means to monitor the AC mains status.

[0082] When mains power is present, the device charges the battery and maintains it fully charged. When the mains is absent, the device turns the Emergency LED Driver supplied by the battery.

[0083] It should be understood that the AC / DC conversion section of a conventional non-maintained Emergency LED Driver is critical for the operation, even though it only exists to power the sections necessary for emergency operation. On the other hand, it is the most complex and difficult section to develop, requiring a dedicated controller to drive the energy conversion process, as well as galvanic isolation, complex and expensive inductors, and extensive regulatory requirements to meet, such as Emissions and Immunity requirements.

[0084] Nevertheless, the AC / DC section can be eliminated by adopting a different concept for a non-maintained emergency LED driver that includes only the essential components for emergency operation. This approach offers several advantages such as: Lower bill of material costs Shorter development times Faster time-to-market Easier compliance with regulatory requirements Smaller PCBs, resulting in cost savings Smaller housings, further reduce costs Enabling more compact luminaire designs.

[0085] In a possible embodiment, the emergency driver 10 is devoid of AC / DC conversion stage.

[0086] In a possible embodiment, the emergency driver 10 is designed to be supplied by DC voltage, in CC or CV control.

[0087] In a possible embodiment, the emergency driver 10 is designed to be configured for CC or CV supply via physical input such as jumper link, voltage input, resistor input, or software configuration.

[0088] In a possible embodiment, the emergency driver 10 is specially designed to be supplied by standard LED driver output.

[0089] In a possible embodiment, the emergency driver 10 comprises at least one input and two output connections.

[0090] In a possible embodiment, the emergency driver 10 input is designed to be connected to a CV DC source or CC LED Driver output.

[0091] In a possible embodiment, the emergency driver 10 output is designed to be connected to the LED light source.

[0092] In a possible embodiment, the emergency driver 10 output is designed to be connected to a battery, local or remote to the driver.

[0093] In a possible embodiment, the emergency driver 10 contains maintained LED driver current sensing capability for use cases when supplied by constant current supply.

[0094] In a possible embodiment, the emergency driver 10 contains battery charging circuity, supplied from the driver supply.

[0095] In a possible embodiment, the emergency driver 10 contains means for lighting the LED source in the absence of its own supply, from the device battery.

[0096] In a possible embodiment, the emergency driver 10 contains a microcontroller or other integrated circuit where the control logic is implemented.

[0097] In a possible embodiment, the emergency driver 10 may contain a connection for an external test switch for testing emergency lighting function.

[0098] In a possible embodiment, the emergency driver 10 may contain a connection for an external LED light indicator, for emergency lighting functions.

[0099] In a possible embodiment, the emergency driver 10 control algorithm defined the battery charging current based on the operation mode.

[0100] In a possible embodiment, the emergency driver 10 control algorithm, when in CV mode, charges the battery at a predefined current, configured in the control logic unit.

[0101] In a possible embodiment, the emergency driver 10 control algorithm, when in CC mode, charges the battery at a current calculated via a predefined algorithm, have as base the power supplied to the LED load, by the maintained driver, to which the emergency driver is connected to. The algorithm is implemented in the control logic.

[0102] In a possible embodiment, the emergency driver 10 may contain means of communication, wired or wireless communications.

[0103] In a possible embodiment, the emergency driver 10 containing wired communications may contain control logic to drive an external maintained LED driver via the wired communications port in the driver.

[0104] In a possible embodiment, the emergency driver 10 containing wired communications may contain control logic to bypass the external controller's commands to the LED driver.

[0105] In a possible embodiment, the emergency driver 10 containing wired communications may contain control logic to override or re-route external controllers commands, sent to the LED driver.

[0106] In a possible embodiment, the emergency driver 10 contains means to detect emergency events by monitoring its own supply.

[0107] In a possible embodiment, the emergency driver 10 contains means to implement emergency lighting functions like Function Test and Duration test.

[0108] In a possible embodiment, when supplied by CV source, the emergency driver 10 powers the LED via its own internal light source driver and monitors the LED light current during Function Test and Duration test and determines whether it is a successful or failed test based on the LED light being correctly powered or not.

[0109] In a possible embodiment, when supplied by CC source, the emergency driver 10 adds additional current to the LED via its own internal light source driver and monitors the LED light current differential during Function Test and Duration test and determines whether it is a successful or failed test based on the differential result.

[0110] Fig. 5 shows a method according to an embodiment of this invention. The method of FIG. 5 is an example of the method of the third aspect of this disclosure. The description of the method of the third aspect is correspondingly valid for the method of FIG. 5.

[0111] The method of Fig. 5 is a method for driving an LED load off a mains voltage 21 or a dedicated emergency LED load off a battery 30. As shown in Fig. 5, the method comprises a step 501 of looping an electrical power from output terminals 22 of a mains-powered LED driver 20 through an emergency driver 10 before being supplied to output terminals 12 of the emergency driver 10. The method further comprises a step 502 of charging the battery (30) based on the electrical power looped through the emergency driver 10 in a non-emergency state, and a step 503 of powering an LED light source (40) with the electrical power in the non-emergency state, or powering the LED light source (40) by discharging the battery (30) in an emergency state. In one example, the method is performed by the emergency driver 10 shown in Fig. 1, Fig. 3, or Fig. 4.

[0112] Optionally, the method further comprises a step of receiving mains voltage 21 information via a non-switched line, and a step of detecting the emergency state when the mains voltage 21 fails.

[0113] While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not by limitation. Numerous changes to the disclosed embodiments can be made in accordance with the disclosure herein without departing from the spirit or scope of the invention. Thus, the breadth and scope of the present invention should not be limited by any of the above described embodiments. Rather, the scope of the invention should be defined in accordance with the following claims and their equivalents.

[0114] Although the invention has been illustrated and described with respect to one or more implementations, equivalent alterations, and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In addition, while a particular feature of the invention may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application.

Claims

1. An emergency driver (10) for driving an LED load off a mains voltage (21) or a dedicated emergency LED load off a battery (30), comprising: input terminals (11) for looping an electrical power from output terminals (22) of a mains-powered LED driver (20) through the emergency driver (10) before being supplied to output terminals (12) of the emergency driver (10), the output terminals (12) being arranged for supplying the electrical power to an LED light source (40), wherein the emergency driver (10) is provided with a charging circuit (14) for charging the battery (30) based on the electrical power looped through the emergency driver (10) .

2. The emergency driver (10) according to claim 1, comprising: further input terminals (13) for receiving mains voltage information via a non-switched line, and a mains failure detection module connected to the further mains failure input terminals (13).

3. The emergency driver (10) according to claim 2, wherein the mains failure detection module is configured to: detect an emergency state when the mains voltage (21) fails or an LED load supply is unpowered, and wherein the emergency driver (10) is configured to power the LED light source (40) by discharging the battery (30) upon the detection of the emergency state.

4. The emergency driver (10) according to any preceding claims, configured to: charge the battery (30) in a non-emergency state, i.e. a non mains-failure state.

5. The emergency driver (10) according to any preceding claims, wherein the charging circuit (14) comprises a transformer (141) with a primary winding (1411) and a secondary winding (1412), wherein the primary and secondary windings are used for both charging and discharging the battery (30).

6. The emergency driver (10) according to claim 5, wherein the charging circuit (14) further comprises: a first switch (142) coupled to the primary winding (1411), configured to operate during the charging of the battery (30) to allow energy transfer from the electrical power from the output terminals (12) of the mains powered LED driver (20) to the battery (30), and a second switch (143) coupled to the secondary winding (1412), configured to operate during the discharging of the battery (30) to allow energy transfer from the battery (30) to the LED load.

7. The emergency driver (10) according to claim 5 or 6, wherein the charging circuit (14) is configured as an integrated driver, using the same windings for both charging and discharging operations.

8. The emergency driver (10) according to claim 5 or 6, wherein the charging circuit (14) is configured as dedicated drivers, using separate windings for the charging and discharging operations.

9. The emergency driver (10) according to any preceding claims, further comprising: a connection to an external test switch, and / or a connection to an external LED light indicator.

10. The emergency driver (10) according to any preceding claims, further comprising: communication means (15) for receiving a first control signal from a controller, and / or sending a second control signal to the mains powered LED driver (20).

11. The emergency driver (10) according to claim 10, emergency driver (10) further comprising: a control logic, configured to determine whether to send the second control signal.

12. The emergency driver (10) according to claim 11, wherein determining whether to send the second control signal comprises: routing the first control signal as the second control signal to the mains powered LED driver, bypassing the first control signal and deciding not to send the second control signal, or overriding the first control signal and deciding to send the second control signal.

13. An emergency lighting driver arrangement, comprising: a mains-powered LED driver (20) with output terminals (22) for electrical power for driving an LED load off a mains voltage (21), an emergency driver (10) for driving said LED load or a dedicated emergency LED load off a battery (30), wherein the electrical power from the output terminals (12) of the mains powered LED driver is looped through the emergency driver (10) before being supplied to LED output terminals (12) of the emergency driver (10), and wherein the emergency driver (10) is provided with a charging circuit (14) for charging the battery (30) based on the electrical power looped through the emergency driver (10) .

14. A method for driving an LED load off a mains voltage (21) or a dedicated emergency LED load off a battery (30), the method comprising the steps of: looping (501) an electrical power from output terminals (22) of a mains powered LED driver (20) through an emergency driver (10) before being supplied to output terminals (12) of the emergency driver (10), charging (502) the battery (30) based on the electrical power looped through the emergency driver (10) in a non-emergency state, and powering (503) an LED light source (40) with the electrical power in the non-emergency state, or powering the LED light source (40) by discharging the battery (30) in an emergency state.

15. The method according to claim 14, further comprising the steps of: receiving mains voltage (21) information via a non-switched line, and detecting the emergency state when the mains voltage (21) fails.

Images