Emergency LED driver

Abstract

The invention relates to an emergency LED driver (100) for supplying an LED load (300), comprising a mains connection (101) for receiving a mains voltage; an output port (105) configured to forward a driver supply voltage based on the mains voltage to an external driver (200); an input port (107) configured to receive an LED supply voltage from the external driver (200); an LED connection (113) for connecting the LED load (300) to the emergency LED driver (100); and a load side relay (111). In a non-emergency mode, the load side relay (111) is adapted to electrically connect the LED connection (113) with the input port (107) such that the LED supply voltage received at the input port (107) is forwarded to the connected LED load (300). Upon a mains voltage failure, the load side relay (111) is configured to maintain the connection between the LED connection (113) and the input port (107) for a predetermined delay time and, after the delay time has passed, to disconnect the input port (107) from the LED connection (113) and to switch the voltage supply of the LED load (300) to a battery (110).

Description

Technical Field

[0001] This invention relates to an emergency LED driver and a system and method for supplying power to an LED load. Background Technology

[0002] Emergency LED (light-emitting diode) converters are known that can supply power to LED loads in the event of a mains power failure. Typically, such emergency LED converters are connected to an external driver, which supplies power to the LED load as long as mains power is available.

[0003] The emergency LED converter can be connected to an external driver via a relay. In the event of a mains power failure, the relay can switch the power supply to the LED load or a portion thereof from the external driver to the emergency converter. The emergency converter can then provide battery power for an autonomous cycle that typically lasts 1 to 3 hours.

[0004] The disadvantage of this relay coupling method is that, in the event of a brief mains power outage, the mains-powered relay may disconnect. Synchronizing the relay is difficult because its coil loses power before any timing control from the microcontroller can take effect. This means that the relay connecting the external converter to the LED load can be disconnected while the external driver remains operational. This can lead to a high output voltage buildup on the output side of the external driver. If the mains power outage is brief, the relay quickly reconnects the external driver to the LED load, resulting in high current and power surges in both the load and the relay contacts. This so-called "hot-plugging" can cause soldering of the contacts and potentially damage the LED load. This negative impact can be particularly pronounced for high-power converters operating at 300 to 450 W.

[0005] Therefore, the objective is to provide an improved emergency LED driver and an improved method for supplying LED loads, which avoids the aforementioned drawbacks. In particular, one objective is to protect LED loads from unwanted voltage pulses or surges after a brief mains power failure. Summary of the Invention

[0006] The object of this invention is achieved by the solution provided in the appended independent claims. Advantageous embodiments of the invention are further defined in the dependent claims.

[0007] According to a first aspect, the present invention relates to an emergency LED driver for supplying an LED load, comprising: an AC connector for receiving AC voltage; an output port configured to forward a driver supply voltage based on the AC voltage to an external driver; an input port configured to receive an LED supply voltage from the external driver; an LED connector for connecting an LED load to the emergency LED driver; and a load-side relay; wherein, in a non-emergency mode of the emergency LED driver, the load-side relay is adapted to electrically connect the LED connector to the input port such that the LED supply voltage received at the input port is forwarded to the connected LED load; and wherein, in the event of an AC voltage failure, the load-side relay is configured to maintain the connection between the LED connector and the input port for a predetermined delay time, and after the delay time has elapsed, disconnect the input port from the LED connector and switch the voltage supply to the LED load to a battery.

[0008] This achieves the following advantages: During the delay time, the LED current can drop completely, allowing for zero-current and / or zero-power switching from the external driver to the emergency LED driver once mains power is restored. In other words, any current or voltage remaining in the external driver during a mains failure can be dissipated during the delay time. Therefore, unwanted surges or voltage pulses to the LED load when reconnecting the external driver after a brief mains failure, the so-called "hot-plug" effect, can be avoided. Furthermore, this allows for switching high power with a relatively small load-side relay, as the connected LED load itself commutates the load current. For example, the switching power can be four times the relay's rating.

[0009] The driver supply voltage can be the mains voltage that is passed to the external driver unchanged. Alternatively, the mains voltage can be stabilized and / or converted, particularly from AC voltage to DC voltage, by an emergency LED driver to generate the driver supply voltage.

[0010] Specifically, the non-emergency mode is the mode for the emergency LED driver, during which a stable mains voltage is available. In non-emergency mode, the LED load can be supplied by the LED supply voltage from the external driver. If the mains voltage fails, the emergency LED driver switches to emergency mode, in which the load-side relay disconnects the external driver from the LED load, and the LED load is supplied directly or indirectly by the battery. This disconnection of the external driver upon detection of a mains failure is preferably delayed by a predetermined delay time to allow the external driver to dissipate any residual energy.

[0011] The battery supply for LEDs can be indirectly achieved via an electronic power supply circuit that adapts the battery power supply to a specific load. For example, boost or buck topologies can be used for battery power conversion.

[0012] The battery can be an internal battery of the emergency LED driver or an external battery connected to the emergency LED driver.

[0013] The external driver can be a general lighting AC power driver, i.e., a conventional LED driver operating on conventional AC power for LED loads. In particular, the external driver includes an LED converter. The external driver may include an input port for receiving a forwarded driver supply voltage from an emergency LED driver and an output terminal for forwarding the LED supply voltage to the emergency LED driver.

[0014] LED loads can be lighting equipment, particularly emergency lights or illuminated evacuation signs. LED loads can include LED modules or LED tracks having at least one light-emitting diode (LED).

[0015] In this implementation, the load-side relay is configured to receive power from the battery, enabling it to maintain the connection between the input port and the LED connector during the delay time. This achieves the advantage that the load-side relay can remain operational at least for the duration of the delay time in the absence of mains voltage supply.

[0016] Specifically, the load-side relay is configured to receive its power supply from the mains voltage and, in the event of a mains voltage failure, from the battery. Thus, the load-side relay can receive sufficient power from the battery to remain closed during the delay period.

[0017] In this implementation, the emergency LED driver also includes a transistor, particularly a MOSFET, connected in series with the load-side relay, wherein the transistor is configured to regulate the voltage across the load-side relay. Specifically, the transistor may also be configured to control the switching of the load-side relay.

[0018] The transistor can also be configured to control a load-side relay to disconnect the external driver from the LED load after a delay time has elapsed. For example, the transistor can be configured to switch the load-side relay by interrupting the power supply from the battery at the end of the delay time.

[0019] In the implementation, the emergency LED driver includes a mains-side relay connected before the output port, wherein the mains-side relay is configured to interrupt the forwarding of the driver's supply voltage in the event of a mains voltage failure. Preferably, this near-immediate shutdown of the mains-side relay in the event of a mains voltage failure interrupts any voltage supply to the external driver.

[0020] In the implementation, the mains-side relay is configured to interrupt the forwarding of the driver supply voltage before the input port is disconnected from the LED connector via the load-side relay. This achieves the advantage that any accumulated energy within the external driver can be effectively dissipated on the output side of the external driver during the delay time.

[0021] In one implementation, the emergency LED driver includes an additional transistor, particularly an additional MOSFET, connected in series with the mains-side relay, wherein the additional transistor is configured to regulate the voltage across the mains-side relay. Specifically, the additional transistor may be configured to control the switching of the mains-side relay.

[0022] In this implementation, the emergency LED driver includes a processor, particularly a microcontroller, configured to control the operation of transistors and / or other transistors. This achieves the advantage that the transistors, and therefore the relays, can be effectively controlled. Specifically, by controlling the respective transistors, the processor is able to control the operation of the relays.

[0023] The processor can be a microcontroller for an emergency LED driver. The processor can be configured to detect a mains power failure and control a load-side relay to remain closed for a delay period following the detection of the mains power failure. After the delay period has elapsed, the processor can be configured to control the load-side relay to switch the power supply to the LED load to the battery. The processor can also be configured to immediately open the mains-side relay after detecting a mains power failure.

[0024] Specifically, the processor can be configured to execute a duty cycle protocol that maintains the supply to the load-side relays by switching the duty cycle level to the battery supply of the relays after the mains power supply is lost.

[0025] In the implementation, the predetermined delay time is 250 milliseconds or less. This provides sufficient time to dissipate the accumulated energy in the external drive.

[0026] In one embodiment, the emergency LED driver includes a battery connector for connecting a battery, which is preferably an external battery.

[0027] In the implementation, the driver supply voltage forwarded to the external driver is AC voltage, specifically mains voltage.

[0028] Alternatively, the driver supply voltage forwarded to the external driver can be a DC voltage, wherein the emergency LED driver includes an AC / DC converter configured to convert the mains voltage into the supply voltage. Specifically, the AC / DC converter is a flyback converter.

[0029] AC / DC converters can also be external converters connected to emergency LED drivers.

[0030] In the implementation scheme, the emergency LED driver includes an emergency LED converter.

[0031] According to a second aspect, the present invention relates to a system comprising an external driver, a battery, and an emergency LED driver according to a first aspect of the invention.

[0032] The system may also include an LED load.

[0033] According to a third aspect, the present invention relates to a method for supplying an LED load, wherein the LED load is connected to an LED connector of an emergency LED driver, the method comprising:

[0034] - Receives mains voltage at the emergency LED driver;

[0035] - Forward the driver supply voltage based on the mains voltage to the external driver;

[0036] - Receive LED supply voltage from an external driver at the input port of the emergency LED driver;

[0037] - In the non-emergency mode of the emergency LED driver, the LED connector is connected to the input port via a relay, so that the LED supply voltage received at the input port is forwarded to the connected LED load.

[0038] - In the event of a mains voltage failure, the connection between the LED connector and the input port is maintained for a predetermined delay time via a load-side relay, and

[0039] - After the delay time has elapsed, the input port is disconnected from the LED connector via the load-side relay, and the voltage supply to the LED load is switched to the battery.

[0040] This achieves the following advantages: during the delay time, the LED current can drop completely, allowing for zero-current and / or zero-power switching from the external driver to the emergency LED driver once mains power is restored. In other words, any current or voltage remaining in the external driver during a mains failure can be dissipated during the delay time. Therefore, unwanted surges or voltage pulses to the LED load, the so-called "hot-plug" effect, can be avoided when reconnecting the external driver after a brief mains failure.

[0041] The battery can be an internal battery of the emergency LED driver or an external battery connected to the emergency LED driver.

[0042] In this implementation, the method further includes supplying power to the load-side relay via the connected battery, enabling the load-side relay to maintain the connection between the input port and the LED connector during the delay time. This achieves the advantage that the load-side relay can remain operational at least for the duration of the delay time in the absence of mains voltage supply.

[0043] In the implementation scheme, the method further includes: interrupting the forwarding of the driver supply voltage to the external driver via the mains-side relay in the event of a mains voltage failure.

[0044] In the implementation, the mains-side relay is configured to interrupt the forwarding of the driver supply voltage before the input port is disconnected from the LED connector via the load-side relay. This achieves the advantage that any accumulated energy within the external driver can be effectively dissipated on the output side of the external driver during the delay time. Attached Figure Description

[0045] The present invention will now be described in conjunction with the accompanying drawings.

[0046] Figure 1 A schematic diagram of an emergency LED driver for supplying an LED load, according to an embodiment, is shown;

[0047] Figure 2 A schematic diagram of an emergency LED driver and its associated external driver according to an implementation scheme is shown;

[0048] Figure 3 A schematic diagram of an emergency LED driver and an associated external driver according to an alternative embodiment is shown;

[0049] Figure 4 A circuit diagram of an emergency LED driver according to an implementation scheme is shown;

[0050] Figure 5 A circuit diagram of an emergency LED driver according to another embodiment is shown;

[0051] Figure 6 Timing diagrams of various electrical parameters of the emergency LED driver during a mains voltage failure, according to the embodiment, are shown; and

[0052] Figure 7 A flowchart is shown for a method of supplying an LED load. Detailed Implementation

[0053] Figure 1 A schematic diagram of an emergency LED driver 100 for supplying an LED load 300 according to an embodiment is shown.

[0054] The emergency LED driver 100 includes an AC connector 101 for receiving AC voltage, an output port 105 configured to forward a driver supply voltage based on the AC voltage to an external driver 200, an input port 107 configured to receive an LED supply voltage from the external driver 200, and an LED connector 113 for connecting an LED load 300 to the emergency LED driver 100. The emergency driver 100 also includes a relay 111, wherein, in the non-emergency mode of the emergency LED driver 100, the load-side relay 111 is adapted to electrically connect the LED connector 113 to the input port 107, such that the LED supply voltage received at the input port 107 is forwarded to the connected LED load 300.

[0055] In the event of a mains voltage failure, load-side relay 111 is configured to maintain the connection between LED connector 113 and input port 107 for a predetermined delay time. This delay time can be 250 milliseconds or less. After the delay time has elapsed, load-side relay 111 is configured to disconnect input port 107 from LED connector 113 and switch the voltage supply to battery 110 for LED load 300. Specifically, the delay time can be configurable, allowing any suitable delay time to be set.

[0056] exist Figure 1 In the illustrated embodiment, battery 110 is an external battery connected to battery connector 109 of emergency LED driver 100. Alternatively, battery 110 may be an internal battery of emergency driver 100. In particular, battery 110 is capable of providing emergency power to LED load 300.

[0057] In the event of a mains power outage, delaying the switching of the load-side relay 111 to the battery 110 allows energy in the external driver 200 to be dissipated and stops the generation of a high output voltage that could lead to hot-plugging and damage to the LED load 300 and / or the contacts of relay 111. Additionally, this method minimizes the power switched by the load-side relay 111, as current is commutated by the LED load 300 when the load-side relay 111 contacts open. This further reduces stress on the external driver.

[0058] Preferably, the load-side relay 111 is configured to receive power from the connected battery 110. This additional power supply from the battery 110 allows the load-side relay 111 to maintain the connection between the input port 107 and the LED connector 113 during the delay time. After the delay time has elapsed, the load-side relay 111 can connect the LED connector 113 to the battery 110 by establishing a connection between the LED connector 113 and the battery connector 109. In particular, depending on the operating mode of the emergency LED driver 100, the load-side relay 111 can be configured to receive power from mains voltage or from the battery.

[0059] The driver supply voltage forwarded to external driver 200 can be the AC mains voltage that is passed unchanged, such as 230V. Alternatively, the mains voltage can be stabilized and / or converted, particularly from AC voltage to DC voltage, by emergency LED driver 100 to generate the driver supply voltage.

[0060] The non-emergency mode of the emergency LED driver 100 is a mode in which a stable mains voltage exists. In non-emergency mode, the LED load 300 can be supplied by the LED supply voltage provided from the external driver 200. If the mains voltage fails, the emergency LED driver 100 switches to emergency mode, in which the load-side relay 111 disconnects the external driver 200 from the LED load 300, and the LED load 300 is supplied by the battery 110 instead.

[0061] Specifically, the load-side relay 111 is an output relay that controls which voltage source (e.g., AC mains or battery 110) supplies the LED load 300.

[0062] The external driver 200 can be a general lighting AC power driver, i.e., a conventional LED driver that operates based on conventional AC power for LED loads. In particular, the external driver 200 includes an LED converter. Figure 1 The external driver shown includes an input port 201 for receiving the driver supply voltage forwarded from the emergency LED driver 100 and an output terminal 203 for forwarding the LED supply voltage to the emergency LED driver 100.

[0063] LED load 300 can be a lighting device, particularly an emergency light or an illuminated evacuation sign. LED load 300 may include LED modules or LED tracks.

[0064] Input port 107 may include connection pins on the housing of emergency LED driver 100 for electrical connection to external driver 200. Similarly, AC connector 101, output port 105, LED connector 113, and / or battery connector 109 may each include one or two connection pins to achieve suitable electrical connections.

[0065] Figure 1 The illustrated emergency LED driver 100 also includes an AC-side relay 103 connected upstream of the output port 105. The AC-side relay 103 can be configured to interrupt the relaying of the driver's supply voltage in the event of a AC voltage failure. Preferably, this shutdown of the AC-side relay 103 interrupts the voltage supply to the external driver 200 almost immediately after a AC voltage failure.

[0066] Specifically, the mains-side relay 103 can be configured to interrupt the forwarding of the driver supply voltage before the input port 107 is disconnected from the LED connector 113 via the load-side relay 111.

[0067] For example, each of relays 103 and 111 is an electrically operated switch including at least one input and at least one contact terminal. Each of relays 103 and 111 remains closed (on) as long as sufficient current flows through the relay, i.e., as long as there is enough current in its coil to operate the contacts, such as mains power. If the power supply to one of relays 103 and 111 is interrupted, relay 103 or 111 opens (off). Each relay 103 or 111 may include a coil and a movable armature.

[0068] Therefore, the load-side relay 111 and the mains-side relay 103 can be configured to prevent hot-plugging of the load 300 and controlled, sequential disconnection of the external driver in the event of a mains power failure, thus preventing potential surges observed by the output load side 111. This prevents open-circuit stress from being applied to the external driver 200 and the lighting wiring. It also prevents the external driver 200 from entering open-circuit load shutdown from where its logic circuitry needs to be reset.

[0069] Optionally, the mains-side relay 103 can be configured to delay the reconnection of the external driver 200 to the output port 105 by an additional delay time, such as 1 second, after the mains voltage has been restored. In other words, the mains-side relay 103 can delay returning to normal operating mode after the previously faulty mains voltage has been restored. This additional delay can be caused by the delay circuitry of the external driver 200 and allows the shutdown circuitry of the external driver 200 to reset. Without this additional delay, the shutdown circuitry may remain locked.

[0070] The emergency LED driver 100 may include a processor (not shown), such as a microcontroller, which may be configured to control the switching of relays 103, 111, for example, via dedicated transistors for controlling relay coils 103, 111.

[0071] The processor can be configured to detect mains power failures and control relays 103 and 111 to turn off in the order described above, that is, first control mains power side relay 103 to turn off, and then control load side relay 111 to turn off after the delay time has elapsed.

[0072] Specifically, the processor can be configured to execute a duty cycle protocol that maintains the supply to the load-side relay by switching the duty cycle level to the battery supply of relay 111 after the mains power supply is lost.

[0073] Figure 2 A schematic diagram of an emergency LED driver 100 and an associated external driver 200 according to an embodiment is shown. For example, Figure 2 The emergency LED driver 100 and external driver 200 shown can correspond to Figure 1 The corresponding drivers 100 and 200 are shown.

[0074] like Figure 2 As shown, the emergency LED driver 100 may include an emergency LED converter 112. The emergency LED converter 112 may be connected to a battery (not shown).

[0075] exist Figure 2 In the highly schematic diagram shown, the load-side relay 111 is depicted by two switches 121 and 123. In the non-emergency mode of the emergency LED driver 100, the switches connect the external driver to the LED load 300. In the event of a mains power failure, the emergency LED driver 100 enters emergency mode, and switches 121 and 123 disconnect the external driver 200 and connect the emergency LED converter 112.

[0076] Figure 3 A schematic diagram of an emergency LED driver 100 and an associated external driver 200 according to an alternative embodiment is shown.

[0077] The emergency LED driver 100 can be an emergency converter, which connects to the mains connection L in The switching line at the location receives mains voltage from the LED driver power supply 131 and connects to the output L. outThe voltage is forwarded to the external driver 200. The relay 103 in the emergency driver can control the power to the external driver 200. Additionally, an external switch (wall switch) can independently switch the power to the external driver 200 as needed by the user, for example, to switch lights when not needed.

[0078] Figure 3 The external driver is an LED controller capable of handling loads up to 450W. Therefore, Figure 3 The relays 103 and 111 of the emergency LED converter 100 are preferably capable of switching to this power level. An LED control device 200, labeled "control device," forwards the LED supply voltage to the input port of the emergency LED converter 100. The emergency LED converter 100 also includes a battery connector and an LED connector; the battery connector includes two pins labeled "battery," and the LED connector includes two pins labeled "LED."

[0079] Figure 3 The emergency LED driver 100 includes a supply voltage port (terminals N, L) for receiving a dedicated supply voltage, such as AC mains power, from a voltage source 133. This dedicated supply voltage can be used for battery charging and for detecting mains power failures. This unswitched power supply can also be used to power relays 103 and 111.

[0080] The emergency LED driver 100 may also include a DALI communication interface, a test switch, and indicator LEDs.

[0081] Figure 4 and Figure 5 Circuit diagrams 400a and 400b of an emergency LED driver 100 according to two embodiments are shown.

[0082] Figure 4 and Figure 5 The only difference between circuit diagrams 400a and 400b is the position of diode 409. Figure 4 It is arranged after the load-side relay 111 and in Figure 5 It is positioned in front of the load-side relay 111.

[0083] Two circuit diagrams, 400a and 400b, show an AC-side relay 103 that forwards the driver supply voltage to the external driver 200, and a load-side relay 111 that forwards the LED supply voltage from the external driver 200 to the LED load 300. Figure 4 and Figure 5In the highly schematic circuit diagrams 400a and 400b, an external driver 200 is depicted between the mains side and the load side of the circuit. Typically, the external driver 200 is connected to the relay contacts of the mains-side relay 103, and power is supplied to the external driver 200 via said relay contacts, while the coils operate these contacts. Corresponding transistors 401 and 403 are connected in series with each of the relays 103 and 111. Transistors 401 and 403 can be configured to regulate the voltage at the respective relays 103 and 111, specifically to ensure that the coil voltage of each of the relays 103 and 111 is close to its nominal value.

[0084] Each of transistors 401 and 403 can be a field-effect transistor (FET), particularly a metal-oxide-semiconductor field-effect transistor (MOSFET).

[0085] Specifically, each of transistors 401 and 403 can be controlled by the microcontroller of the emergency LED driver 100. In this way, the microcontroller can control the switching of relays 103 and 111.

[0086] The load-side relay 111 can be an output relay, and the mains-side relay 103 can be a third-pole relay.

[0087] Circuit diagrams 400a and 400b also show corresponding diodes 407 and 408 connected in parallel with each of relays 103 and 111.

[0088] The circuit also includes a battery circuit for connecting the battery 110, which includes a buck-boost converter. Alternatively, the battery circuit may include a boost converter or another type of converter.

[0089] The emergency LED driver 100 may also include a converter 405, particularly a flyback converter. The flyback converter can be configured to charge the battery 110 and supply power to relays 103, 111. For example, both relays 103, 111 can be supplied from the output DC rail of the converter 405.

[0090] Converter 405 can also be an external converter connected to emergency LED driver 100.

[0091] For example, in the event of a mains power failure, the large-capacity storage capacitor C cannot sustain the power supply to relays 103 and 111 for more than tens of milliseconds. Therefore, if no other power supply is provided, relays 103 and 111 will disconnect even during a relatively short mains power interruption. The external driver 200 remains operational when its load is disconnected by the load-side relay 111, causing its output capacitor to charge to a high voltage and its protective shutdown circuit to operate. This can be avoided by supplying power to the load-side relay 111 from the battery 110 after a mains power failure, thereby maintaining the connection between the external driver 200 and the LED load 300. In this way, any charge accumulated in the external driver can be dissipated before the power supply to the LED load 300 is finally switched back to the battery 110.

[0092] Because the shutdown circuit of the external driver 200 is triggered, the mains-side relay 103 has a typical one-second delay before reconnection to allow the external driver to reset. When mains power returns, the load-side relay 111 can be switched immediately, but the delay circuit can delay the mains-side relay 103 by at least one second to allow the shutdown circuit of the external driver 200 to reset, otherwise it will remain locked.

[0093] Preferably, supplying the load-side relay 111 from the battery side of the emergency drive 100 allows the relay to remain in place for up to 0.25 seconds, which is sufficient for the external converter to dissipate its residual energy, especially since its mains power supply can be disconnected almost immediately by the mains-side relay 103 if mains power is lost. In particular, the mains-side relay 103 is configured to disconnect immediately upon detection of a mains power failure, or alternatively, to disconnect immediately upon a flyback having insufficient energy to support the relay.

[0094] Additionally, after approximately 250 milliseconds, the transistor 401 supplying the load-side relay 111 can be disconnected by the processor of the emergency LED driver 100, thereby preventing excessive battery drain in emergency mode.

[0095] Specifically, prolonged supply of power to a relay (e.g., load-side relay 111) from battery 110 may cause the relay to drain battery 110. If this drain continues after the low battery level is cut off at the end of the emergency duration, it will affect system autonomy and battery life. Therefore, the transistor 401 of the load-side relay 111 can be configured to disconnect the load-side relay 111 from battery 110 after the delay time has elapsed to prevent such drain.

[0096] Therefore, maintaining the connection of the external driver 200 to the LED load via the load-side relay can result in several advantages, such as reducing stress on the external driver 200 by not pulling its load while it is still powered, reducing the voltage on the wiring and connectors associated with the external driver 200 and the LED load 300 by not putting the external converter into a fault mode, and thus also preventing hot-plug events.

[0097] Furthermore, brief mains power interruptions and hot-plug events resulting in high voltage on the external driver 200 caused by using the load-side relay to pull the load of the external driver 200 can be avoided. In particular, it can be prevented that high voltage accumulated on the output capacitor of the external driver 200 could exert a damaging pulse on the contacts of the LED load 300 and the load-side relay 111 when the contacts are reconnected at the end of a mains power outage. Therefore, erroneous shutdown of the external driver 200 can be avoided.

[0098] Finally, for applications where a small relay is expected to support loads between 300 and 450W, the stress on the load-side relay 111 during switching can be reduced. Specifically, the actual switching power can be reduced to a negligible level because the load is already commutated by the LED and is not actually switched by the load-side relay contacts. This allows a tiny relay rated at 80W to switch more than four times its rated power.

[0099] Figure 6 Timing diagrams of various electrical parameters of an emergency LED driver during a mains voltage failure, according to an embodiment, are shown.

[0100] Figure 6 The electrical parameters shown in the chart are: AC mains voltage (V) 市电 ), the supply voltage of the mains-side relay 103 (V) 继电器_市电 LED load current (I) 负载 ), the supply voltage (V) of the load-side relay 111 继电器_负载 ), the voltage supplied to the LED load is 300V (V) 负载 ) and the power supplied to the LED load 300 (P 负载 ).

[0101] like Figure 6 As shown, before time T0, there exists an AC mains voltage (V). 市电 And the external driver 200 is in operation. During this period, relays 103 and 111 are both turned on, supplying power, for example, 450W, to the LED load 300.

[0102] At time T0, a mains power failure occurs. This mains power failure is detected by an emergency driver 100 at time T1, which disconnects the mains relay 103, for example, by means of a microcontroller and an additional transistor 403. However, the load-side relay 111 maintains the connection between the external driver 200 and the LED load 300 for a delay time, for example, 250 milliseconds, and ends at T3.

[0103] For a short time interval of a few milliseconds after T1, the residual energy from the external driver 200 continues to drive the LED load 300 until the current in the LED load 300 becomes zero at time T2. The load-side relay remains connected, i.e., the connection between the external driver 200 and the LED load 300 is maintained until time T3. Due to this connection, the LED load voltage decays slowly. Because of I... 负载 The power is zero, therefore the power through the relay contacts of the load-side relay 111 is zero. During this period, the load-side relay 111 receives its power supply from the battery 110.

[0104] At time T3, after the delay time has elapsed, load-side relay 111 finally disconnects with zero power. At time T4, emergency actuator 100 begins to power the LED load with a much lower power (≤10W) from battery 110. With both relays 103 and 111 disconnected, emergency operation continues until mains power is restored (not shown).

[0105] Figure 7 A flowchart of a method 70 for supplying an LED load 300 according to an embodiment is shown.

[0106] LED load 300 is, for example, LED connector 113 connected to emergency LED driver 100 via physical wiring.

[0107] The method 70 includes the following steps:

[0108] -Receives 72V AC mains voltage at the emergency LED driver 100;

[0109] - Forward the driver supply voltage based on the mains voltage to the external driver 200;

[0110] - Receives 74 LED supply voltage from external driver 200 at input port 107 of emergency LED driver 100;

[0111] - In the non-emergency mode of the emergency LED driver 100, the LED connector 113 is connected to the input port 107 via the load-side relay 111 75, so that the LED supply voltage received at the input port 107 is forwarded to the connected LED load 300.

[0112] - In the event of a mains voltage failure, the connection between the LED connector 113 and the input port 107 is maintained for a predetermined delay time of 76 seconds via the load-side relay 111, and

[0113] - After the delay time has elapsed, the input port 107 is disconnected from the LED connector 113 via the load-side relay 111, and the voltage supply of the LED load 300 is switched to the battery 110.

[0114] Preferably, the method further includes the additional step of supplying power to the load-side relay 111 via the battery 110 connected to the emergency LED driver 100, so that the load-side relay 111 can maintain the connection between the input port 107 and the LED connector 113 during the delay time.

[0115] The method may include the additional step of interrupting the relay of the driver supply voltage to the external driver 200 via the mains-side relay 103 once a mains voltage failure occurs, particularly once the mains voltage failure is detected, for example, by the processor of the emergency LED driver 100.

[0116] The mains-side relay 103 can be configured to interrupt the forwarding of the driver supply voltage before the input port 107 is disconnected from the LED connector 113 via the load-side relay 111.

Claims

1. An emergency LED driver (100) for supplying an LED load (300), the emergency LED driver comprising: Mains power connector (101), the mains power connector being used to receive mains voltage; Output port (105), which is configured to forward the driver supply voltage based on the mains voltage to an external driver (200). An input port (107) is configured to receive an LED supply voltage from the external driver (200); LED connector (113), the LED connector being used to connect an LED load (300) to the emergency LED driver (100); and Load-side relay (111). In the non-emergency mode of the emergency LED driver (100), the load-side relay (111) is adapted to electrically connect the LED connector (113) to the input port (107), such that the LED supply voltage received at the input port (107) is forwarded to the connected LED load (300); and When a fault in the mains voltage is detected, the load-side relay (111) is configured to maintain the connection between the LED connector (113) and the input port (107) for a predetermined delay time, and after the delay time has elapsed, disconnect the input port (107) from the LED connector (113) and connect the LED connector (113) to the battery (110) to provide voltage supply from the battery (110) to the LED load (300); During the delay period, the current supplied from the external driver (200) to the LED load (300) becomes zero, and wherein, The emergency LED driver includes a mains-side relay (103) connected before the output port (105), wherein the mains-side relay (103) is configured to interrupt the forwarding of the driver's supply voltage in the event of a mains voltage failure, and The mains-side relay (103) is configured to delay the emergency LED driver (100) back to the non-emergency mode for at least one second after the mains voltage of the previous fault is restored, so that the shutdown circuit of the external driver (200) can be reset.

2. The emergency LED driver (100) according to claim 1, wherein, The load-side relay (111) is configured to receive power from the battery (110) so that the load-side relay (111) can maintain the connection between the input port (107) and the LED connector (113) during the delay time.

3. The emergency LED driver (100) according to claim 1 or 2, wherein the emergency LED driver further includes a transistor (401) connected in series with the load-side relay (111), wherein, The transistor (401) is configured to regulate the voltage across the load-side relay (111).

4. The emergency LED driver (100) according to claim 1, wherein, The mains-side relay (103) is configured to interrupt the forwarding of the driver supply voltage before the input port (107) is disconnected from the LED connector (113) via the load-side relay (111).

5. The emergency LED driver (100) according to claim 3, wherein the emergency LED driver includes an additional transistor (403) connected in series with the mains-side relay (103), wherein, The additional transistor (403) is configured to regulate the voltage across the mains-side relay (103).

6. The emergency LED driver (100) according to claim 5, wherein, The emergency LED driver (100) includes a processor configured to control the operation of the transistor (401) and / or the additional transistor (403).

7. The emergency LED driver (100) according to claim 1, wherein, The predetermined delay time is 250 milliseconds or less.

8. The emergency LED driver (100) according to claim 1, wherein, The emergency LED driver (100) includes a battery connector (109) for connecting the battery (110).

9. The emergency LED driver (100) according to claim 1, wherein, The voltage supplied to the external driver (200) is AC voltage.

10. The emergency LED driver (100) according to claim 3, wherein, The transistor (403) is a MOSFET.

11. The emergency LED driver (100) according to claim 5, wherein, The additional transistor (403) is an additional MOSFET.

12. The emergency LED driver (100) according to claim 6, wherein, The processor is a microcontroller.

13. The emergency LED driver (100) according to claim 8, wherein, The battery is an external battery.

14. The emergency LED driver (100) according to claim 9, wherein, The driver supply voltage forwarded to the external driver (200) is the mains voltage.

15. A system comprising an external driver (200), a battery (110), and an emergency LED driver (100) according to any one of claims 1 to 14.

16. A method (70) for supplying an LED load (300), wherein, The LED load (300) is connected to the LED connector (113) of the emergency LED driver (100), and the method includes the following steps: - Receives (72) mains voltage at the emergency LED driver (100); - Forward (73) the driver supply voltage based on the mains voltage to the external driver (200); - Receive (74) LED supply voltage from the external driver (200) at the input port (107) of the emergency LED driver (100); - In the non-emergency mode of the emergency LED driver (100), the LED connector (113) is connected (75) to the input port (107) via the load-side relay (111), such that the LED supply voltage received at the input port (107) is forwarded to the connected LED load (300). - Upon detection of a fault in the mains voltage, the connection between the LED connector (113) and the input port (107) is maintained (76) for a predetermined delay time via the load-side relay (111), and - After the delay time has elapsed, the input port (107) is disconnected (77) from the LED connector (113) via the load-side relay (111) and the LED connector (113) is connected to the battery (110) to provide voltage supply for the LED load (300) from the battery (110). During the delay period, the current supplied from the external driver (200) to the LED load (300) becomes zero. The method further includes: - In the event of the aforementioned mains voltage failure, the forwarding of the driver supply voltage to the external driver (200) via the mains-side relay (103) is interrupted; and - After the mains voltage of the previous fault is restored, the operation of returning the emergency LED driver (100) to the non-emergency mode via the mains-side relay (103) is delayed by at least one second so that the shutdown circuit of the external driver (200) can be reset.

17. The method (70) according to claim 16, further comprising: - Power is supplied to the load-side relay (111) via the battery (110) so that the load-side relay (111) can maintain the connection between the input port (107) and the LED connector (113) during the delay time.

18. The method (70) according to claim 16, wherein, The mains-side relay (103) is configured to interrupt the forwarding of the driver supply voltage before the input port (107) is disconnected from the LED connector (113) via the load-side relay (111).

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