Intelligent smart parallel led-driver detection for load sharing

Abstract

The present invention provides an LED driver for supplying power to an LED load. Said LED driver comprises a droop characteristic defined by a droop characteristic curve, which represents the relationship between an output voltage and an output current of the LED driver, wherein the output voltage decreases as the output current increases. Said LED driver further comprises a control unit configured to autonomously modify the droop characteristic curve without external input.

Description

TECHNICAL FIELD

[0001] The present invention relates to LED driver technology, specifically to DC-output LED drivers for use in parallel ("stacked") configurations to supply combined DC power to a shared LED load. The invention focuses on methods for determining the operational status of an LED driver, whether functioning independently or as part of a parallel system, without the need for communication between the drivers.BACKGROUND

[0002] In modern LED lighting systems, multiple LED drivers are often stacked or connected in parallel at their DC output to supply combined DC power to a single LED load. Such configurations are used to meet higher power demands, ensuring redundancy and load-sharing between the parallel drivers. However, in these systems, there is typically no communication between the individual drivers. As a result, each LED driver does not know whether it is operating alone or in parallel with other drivers in the system. This lack of communication poses a challenge, as certain parameters and characteristics of the LED driver, such as output voltage and current regulation, need to be adjusted depending on whether the driver is in single or parallel operation.

[0003] Traditional LED drivers often rely on "voltage droop control" to balance the load between parallel drivers. Voltage droop control is a technique wherein the output voltage of an LED driver is controlled by its internal control to decrease with increasing output current. This ensures that when multiple drivers are operating in parallel, their loads are balanced by matching their output characteristics.

[0004] However, conventional LED drivers require pre-configuration or external input to determine their operation mode (single or parallel). The inability to autonomously detect whether a driver is part of a stacked system or operating individually can lead to inefficient operation, improper load balancing, or even system failure in certain cases.SUMMARY

[0005] In view of the above-discussed limitations, the objective of this invention is to enable an LED driver to independently determine whether it is operating alone or in parallel with other drivers. An additional objective of this invention is to allow the LED driver to dynamically adjust its parameters, thereby optimizing its performance for the current configuration without the need for external communication or configuration.

[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 LED driver is provided. Said LED driver comprises a droop characteristic defined by a droop characteristic curve, which represents the relationship between an output voltage and an output current of the LED driver, wherein the output voltage decreases as the output current increases. Said LED driver comprises a control unit configured to autonomously modify the droop characteristic curve without external input.

[0008] The invention provides an LED driver that can autonomously shift its droop characteristic curve without external input. The droop characteristic curve represents how the output voltage is controlled by the internal control of the driver to "droop" when the load current increases. For instance, the voltage is at its highest at no load, and as the load increases, the voltage decreases along the curve, with the slope determining the amount of droop.

[0009] The autonomous modification of the droop characteristic curve allows the LED driver to dynamically adjust its behavior based on internal conditions. This eliminates the need for external input or communication, simplifying the system design and enabling real-time adaptation to varying load conditions. It provides flexibility in system architecture, allowing the driver to optimize its performance regardless of external configuration.

[0010] According to a further implementation form of the first aspect of the invention, the control unit is configured to shift the droop characteristic curve in order to determine an operating status of the LED driver, the operating status comprising single mode operation or parallel operation, wherein in parallel operation, the LED driver operates in parallel with at least one other LED driver.

[0011] This configuration introduces the ability of the control unit to shift the droop characteristic curve to determine the operating status of the LED driver, whether in single mode or in parallel operation with at least one other driver. By shifting its internally stored droop characteristic curve, the driver can self-determine its operating status (single or parallel mode) autonomously. This enables the system to dynamically recognize when it's part of a larger driver network and adapt its operational parameters accordingly. It enhances scalability and provides a basis for efficient load sharing when operating in parallel mode.

[0012] According to a further implementation form of the first aspect of the invention, the LED driver further comprises a measurement unit configured to measure changes in the output voltage and / or output current of the LED driver.

[0013] The measurement unit allows the driver to monitor its real-time operating conditions. This data is essential for the control unit to accurately modify the droop characteristic curve and determine the operating mode. The inclusion of this feature ensures the system can respond accurately to fluctuations in load or operational status, improving overall system responsiveness and precision

[0014] According to a further implementation form of the first aspect of the invention, the control unit is configured to: determine that the LED driver is in single mode operation when the measured voltage and / or current change is larger than or equal to an expected voltage and / or current change, and determine that the LED driver is in parallel operation when the measured voltage and / or current change is smaller than the expected voltage and / or current change.

[0015] In single mode, or namely in standalone operation, the LED driver operates independently and powers one or more LEDs on its own, without needing to be synchronized with or work alongside other drivers. In parallel operation, multiple LED drivers work together to power a larger or more complex LED system. Advantageously, this provides a robust method for accurately determining whether the driver is operating alone or with other drivers in parallel. Such approach improves detection accuracy and reduces misidentification, thereby ensuring that the driver operates with the appropriate configuration. This leads to better load balancing and system efficiency, particularly in multi-driver configurations.

[0016] According to a further implementation form of the first aspect of the invention, the control unit is further configured to adjust one or more operational parameters of the LED driver, based on the determined operating status of the LED driver.

[0017] For instance, by adjusting operational parameters such as voltage and current regulation, the LED driver can optimize its performance based on whether it is operating in single or parallel mode. This increases energy efficiency, improves load sharing in parallel mode, and ensures stable performance in single mode. It enhances the driver's adaptability to different system configurations and operational demands.

[0018] According to a further implementation form of the first aspect of the invention, the control unit is configured to flatten the slope of the droop characteristic curve when the LED driver is in single mode operation, or restore the original droop characteristic curve when the LED driver is in parallel operation.

[0019] Advantageously, flattening the droop characteristic curve in single mode reduces the sensitivity of the driver to changes in current, providing more stable output voltage and better regulation for standalone operation. Restoring the original curve in parallel mode ensures that the driver contributes appropriately to load sharing. This functionality maximizes system efficiency and prevents driver overload in parallel configurations.

[0020] According to a further implementation form of the first aspect of the invention, the control unit is further configured to: calculate the total power supplied by the parallelly connected LED drivers based on the measured voltage and / or current changes, and / or determine a number of LED drivers operating in parallel based on the measured voltage and / or current changes.

[0021] The ability to calculate total power and determine the number of parallel drivers allows the system to intelligently manage load distribution. This helps prevent overloading or underutilization of individual drivers and ensures that all drivers contribute effectively to the shared load. This improves the system's scalability and robustness in larger configurations, allowing for efficient power management and optimization.

[0022] According to a second aspect of the invention, an LED system is provided. The LED system comprises an LED load, and at least one LED driver according to the first aspect or any implementation form of the first aspect.

[0023] The inclusion of the LED driver in a complete system enables flexible scaling and efficient power management for lighting applications. Multiple LED drivers can be connected in parallel to scale the system for larger LED arrays, with each driver adjusting its performance accordingly. The invention also proposes an intelligent, adaptive system that can dynamically adjust to varying numbers of drivers and loads, providing enhanced reliability and efficiency in LED systems.

[0024] According to a third aspect of the invention, a method for detecting an operation status of an LED driver is provided. Said method comprises: measuring an output voltage and / or output current of the LED driver; autonomously shifting a droop characteristic curve, which represents the relationship between the output voltage and the output current of the LED driver; measuring a change of output voltage and / or a change of output current based on the shifted droop characteristic curve; comparing the measured voltage and / or current change with an expected voltage and / or current change; and determining whether the LED driver is operating in single mode or in parallel with at least one other LED driver based on the comparison of the measured change and the expected change.

[0025] This invention proposes a method that provides a precise, autonomous means of detecting whether the LED driver is operating in single or parallel mode. This provides an accurate detection mechanism that allows the driver to adapt its behavior without manual intervention or external communication. This reduces system complexity and enhances operational flexibility.

[0026] According to a further implementation form of the third aspect of the invention, the method further comprises determining that the LED driver is operating in single mode when the measured voltage and / or current change is larger than or equal to an expected voltage and / or current change, and determining that the LED driver is in parallel operation when the measured voltage and / or current change is smaller than the expected voltage and / or current change.

[0027] This ensures that the system can reliably distinguish between single and parallel operation, which is critical for adapting the driver's behavior and optimizing load distribution. It provides a robust, accurate detection mechanism that enables efficient energy usage and better load balancing across multiple drivers.

[0028] According to a further implementation form of the third aspect of the invention, the method further comprises adjusting one or more operational parameters of the LED driver, based on the determined operating status of the LED driver.

[0029] By adjusting the operational parameters (e.g., voltage or current regulation), the system optimizes performance according to the specific operating mode. In single mode, this ensures stable operation, while in parallel mode, it allows for efficient load sharing.

[0030] According to a further implementation form of the third aspect of the invention, the method further comprises flattening the slope of the droop characteristic curve when the LED driver is operating in single mode, or restoring the original droop characteristic curve when the LED driver is operating in parallel with at least one other LED driver.

[0031] Flattening the slope in single mode provides stable output, while restoring the original curve in parallel mode facilitates load sharing. This ensures that the driver operates optimally in both modes, improving energy efficiency and performance. This method provides better voltage regulation in single mode and enhanced load sharing in parallel mode, leading to improved system stability. According to a further implementation form of the third aspect of the invention, the method further comprises calculating the total power supplied by the parallelly connected LED drivers based on the measured voltage and / or current change, and / or determining a number of LED drivers operating in parallel based on the measured voltage and / or current change.

[0032] This calculation enables the system to manage the total power output of the drivers and optimize load distribution. It allows the system to intelligently adapt to different numbers of drivers, ensuring balanced power delivery and preventing overloads. The effect is increased scalability and adaptability, ensuring optimal performance as more drivers are added to or removed from the system.

[0033] 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

[0034] 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 LED driver according to an embodiment of this invention. Fig. 2shows the output characteristic curves of two LED drivers according to an embodiment of this invention. Fig. 3shows a method according to an embodiment of this invention. Fig. 4shows a method according to an embodiment of this invention. DETAILED DESCRIPTION OF EMBODIMENTS

[0035] Illustrative embodiments of an LED driver, a LED system, and a method for detecting an operation status of an LED driver 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.

[0036] 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.

[0037] With respect to Fig. 1, an exemplary embodiment of a LED driver 10 is illustrated. The LED driver 10 is designed to supply power to an LED load 11 while autonomously adjusting its operation based on whether it functions alone (single mode) or in parallel with other LED drivers (parallel operation).

[0038] The LED driver 10 includes the following key components and functionalities: Droop Characteristic Curve: The LED driver 10 exhibits a droop characteristic that defines the relationship between the output voltage (Vout) and output current (Iout). This relationship is graphically represented by a droop characteristic curve, where the output voltage decreases as the output current increases. This behavior allows the LED driver 10 to participate in load-sharing when operating in parallel with other drivers. Control Unit (not shown in Fig. 1): The control unit in the LED driver 10 is a critical component that autonomously modifies the droop characteristic curve. This modification is performed without requiring external input. The control unit may further adjust the curve based on measured data to optimize the driver's performance depending on whether it is operating independently or in conjunction with other drivers.

[0039] Optionally, the control unit can shift the droop characteristic curve to determine the driver's operational status. Specifically, the control unit alters the curve to observe the effects on output voltage and current, allowing the driver to evaluate whether it is working alone or in parallel.

[0040] In one embodiment, the LED driver 10 also includes a measurement unit that continuously monitors changes in output voltage and / or current. This real-time data is sent to the control unit, which uses it to adjust the droop characteristic curve and determine whether the driver is operating in single mode or in parallel operation.

[0041] The control unit analyzes the measured data and compares it to expected changes based on the modified droop characteristic curve. This allows the driver to autonomously detect its operating status: Single Mode: If the measured change in voltage / current is larger than or equal to expected, the control unit determines that the driver is in single mode, meaning it is solely responsible for supplying power to the LED load. Parallel Operation: If the measured change in voltage / current is smaller than expected, the driver is operating in parallel with at least one other LED driver.

[0042] Once the operational status is determined, the driver can adjust various parameters such as output voltage, output current, or power regulation settings to optimize its performance for either single or parallel operation. This allows for dynamic self-optimization without requiring external communication between drivers, resulting in better system performance, increased efficiency, and enhanced reliability.

[0043] Optionally, this includes modifying the droop characteristic curve: In single mode, the slope of the droop characteristic curve is flattened, reducing voltage variation with increasing current, and providing more stable power regulation.

[0044] In parallel operation, the control unit restores the original droop characteristic curve to ensure effective load sharing with other parallel drivers.

[0045] In one embodiment, the control unit can further calculate the total power supplied by parallelly connected drivers based on the measured voltage / current changes. Additionally, it can determine the number of drivers operating in parallel, allowing the system to manage and balance the load dynamically.

[0046] In one embodiment, the control unit may use a mathematical model to calculate the expected voltage change based on whether the LED driver 10 is operating in single mode or parallel operation. The following equations are used by the control unit to determine the output voltage and current in each case.Linear Equations for Output Voltage:

[0047] The relationship between the output voltage (Vout) and output current (Iout) for the droop characteristic is modeled as a linear equation with the same slope (k) for both drivers but with different offsets (di and d 2 ) : V out = k ∗ l 1 + d 1 V out = k ∗ l 2 + d 2 Parallel Operation:

[0048] In parallel operation, the power supplied to the load is shared between both drivers. The total power (P) is the sum of the power supplied by each driver: P = V out ∗ l 2 + V out ∗ l 2

[0049] By solving for Vout in the case of parallel operation, the control unit obtains the following equation: V out = 1 4 d 1 2 + 2 d 1 d 2 + d 2 2 + 8 kP + d 1 + d 2

[0050] This equation allows the control unit to predict the expected output voltage when both drivers are operating in parallel mode, sharing the load.Single Operation:

[0051] In single operation, the LED driver 10 supplies the entire power (P_total) to the load. The power relationship is simplified to: P total = V out + I

[0052] Using the same approach, the control unit calculates the output voltage in single operation mode: V out = k + l out + d

[0053] Solving for Vout, the control unit obtains the following expression for single operation: V out = 1 2 d 2 + 4 kP + d

[0054] The control unit compares the actual measured voltage change to the expected changes for both single mode and parallel operation.

[0055] If the measured voltage change is equal to or larger than the expected voltage change for single mode, the control unit determines that the driver is operating independently. Possibly, if the measured change in voltage or current falls within an acceptable tolerance range around the expected value, the control unit can determine that the driver is operating in single mode, supplying power independently to the LED load.

[0056] If the measured voltage change is smaller than the expected value, it indicates parallel operation with at least one other driver.

[0057] The invention also encompasses an LED system 1 that integrates one or more LED drivers 10 to power an LED load 11. This system 1 is designed to automatically adjust the performance of its drivers based on their operational status (single mode or parallel mode) and ensure efficient load distribution.

[0058] Notably, Fig. 1 also depicts an embodiment of an LED system 1 comprising multiple LED drivers connected in parallel to supply power to a shared LED load 11.

[0059] In Fig 1, two 50W LED drivers are connected in parallel to power a single 30W LED load. The system 1 is powered by an AC supply of 230V at 50Hz. The following components are illustrated: For instance, each of the two LED drivers is designed to supply a maximum power of 50W. These drivers are connected to the same AC power source, sharing the input from the 230V 50Hz supply. The LED load (e.g., 30W) is connected to both drivers in parallel. In this configuration, the drivers work together to provide the necessary power to the load.

[0060] In this configuration, each driver autonomously may detect whether it is operating in parallel mode or single mode using the principles described in the previous embodiments.

[0061] In may be understood that the system is scalable, meaning that additional LED drivers can be added to increase the total power supply to the load. The autonomous detection and adjustment mechanism in each driver ensures that no external configuration is necessary as new drivers are introduced into the system. This results in a highly flexible system that can adapt to varying load demands while maintaining efficient power distribution.

[0062] Fig. 2 illustrates the output characteristic curves of two LED drivers (Driver 1 and Driver 2) operating in parallel. The graph depicts the relationship between the output current (Iout) and the output voltage (Vout) of the two drivers.

[0063] The downward slopes of the curves represent the droop characteristic of each driver, meaning the output voltage decreases as the output current increases. This behavior is typical for droop-regulated LED drivers to facilitate load sharing between drivers in parallel.

[0064] Fig. 2(a) represents a typical design of an LED system where the driver cannot detect whether it is operating in parallel mode or single mode. In such a design, Driver 1 and Driver 2 operate based on their individual droop characteristic curves, which define the relationship between the voltage and current. The system lacks the ability to autonomously detect whether the drivers are working independently or in parallel.

[0065] The black dots in Fig. 2(a) represent the operating points of both drivers in parallel operation. Due to the drivers' differing droop characteristics, Driver 1 operates at a higher output voltage than Driver 2 for the same current. However, neither driver can detect the operating condition; they continue to operate based on their predefined curves without any dynamic adjustment.

[0066] The grey dot represents the operating point of Driver 1 in single mode, indicating the voltage and current it would provide when operating alone. In this typical design, if the system switches between single and parallel mode, the drivers cannot detect the change or adjust their droop curves accordingly.

[0067] Fig. 2(b) shows an improved LED system where Driver 1 is equipped with the ability to autonomously detect whether it is operating in single mode or parallel mode, and adjust its behavior accordingly. This figure expands on the limitations shown in Fig. 2(a) by illustrating the impact of autonomous detection and adjustment.

[0068] In this setup, Driver 1 is capable of shifting its droop characteristic curve to detect its operating status. The original droop curve of Driver 1 is shown as a dashed line, while the shifted curve (after being modified by the control unit) is shown as the solid line. Driver 2 continues to operate based on its original droop characteristic.

[0069] When operating in single mode, the control unit of Driver 1 shifts its droop characteristic curve downwards and compares the resulting voltage change. The grey dot represents the operating point in single mode after the droop characteristic curve has been shifted. In parallel mode, the control unit of Driver 1 similarly shifts its droop characteristic curve but detects a smaller voltage change compared to single mode. The operating points in parallel mode are represented by the black and grey stars for both the old and shifted droop curves.

[0070] The difference between the operating points in single and parallel mode (as indicated by the differences in voltage changes) allows the control unit to autonomously detect whether the driver is operating alone or in parallel with another driver.

[0071] Once the control unit detects whether the driver is operating in single mode or parallel mode, it adjusts the droop characteristic curve accordingly.

[0072] In single mode, the control unit flattens the droop characteristic curve to stabilize the output voltage across varying currents, reducing unnecessary variations. In parallel mode, the control unit restores the original curve to ensure proper load sharing with other drivers.

[0073] This design enables the driver to: Autonomously detect its operational status (single or parallel mode) by comparing the voltage changes resulting from the shifted droop curve. Adjust operational parameters such as the slope of the droop characteristic curve to optimize performance based on the detected mode. Balance the load more effectively in parallel operation, preventing any driver from taking on an excessive portion of the load.

[0074] With reference to Fig. 3, an embodiment of a method 300 for detecting the operational status of an LED driver 10, is illustrated. The LED driver 10 may be the LED driver described in the previous embodiments, as shown in Fig. 1. The method 300 comprises the following steps: A step 301 of Measuring Output Voltage / Current: The method begins by measuring the output voltage and / or output current of the LED driver 10.

[0075] A step 302 of Shifting the Droop Characteristic Curve: The droop characteristic curve, which represents the relationship between the output voltage and current, is then autonomously shifted by the control unit.

[0076] A step 303 of Measuring Voltage / Current Changes: After the curve is shifted, the method involves measuring the change in output voltage and / or current based on the shifted curve.

[0077] A step 304 of Comparing Measured Changes to Expected Values: The measured change is then compared with an expected voltage and / or current change. This comparison allows the control unit to determine whether the LED driver 10 is operating in single mode or in parallel with at least one other driver.

[0078] A step 305 of Determining Operating Status: Based on the comparison: The driver 10 is determined to be in single mode if the measured change is larger than or equal to the expected change.

[0079] The driver 10 is determined to be in parallel operation if the measured change is smaller than the expected change.

[0080] Optionally, the method may further involve adjusting one or more operational parameters of the LED driver based on the determined status: Flattening the slope of the droop characteristic curve when in single mode, or Restoring the original droop characteristic curve when in parallel mode.

[0081] Optionally, the method can also include calculating the total power supplied by the parallelly connected drivers or determining the number of parallelly connected drivers based on the measured changes in voltage and / or current.

[0082] Fig. 4 illustrates a detailed flowchart for the process of detecting the operational status of an LED driver 10 (single mode or parallel mode) according to an embodiment of this invention. The flowchart outlines the sequential steps the control unit follows to autonomously determine whether the driver is operating independently (single mode) or in conjunction with another driver (parallel mode).

[0083] The process begins by measuring the output voltage of the LED driver while it is operating with its default droop characteristic curve. This measurement provides a baseline for comparison later in the process.

[0084] The control unit autonomously reduces the offset of the droop characteristic curve. This reduction shifts the curve, causing a change in the relationship between the output voltage and the output current. The purpose of this shift is to create a measurable difference in the output voltage for the subsequent comparison.

[0085] Based on the new (reduced) droop characteristic curve (e.g., shown in Fig. 2(b)), the control unit calculates the expected voltage change that would occur if the driver were operating in single mode. This expected change represents the voltage variation that should occur if no other drivers are connected in parallel.

[0086] After the droop characteristic curve has been shifted, the control unit again measures the output voltage. This measurement is used to compare the actual behavior of the system with the expected behavior (calculated in the previous step).

[0087] The control unit calculates the actual voltage change by comparing the initial voltage measurement (before the shift) and the post-shift voltage measurement. This step provides the measured voltage change, which is critical for determining the operating status.

[0088] The control unit compares the measured voltage change to the expected voltage change calculated in step 3. This comparison determines whether the LED driver is operating alone or in parallel.

[0089] If the measured voltage change equals or falls within a tolerance range around the expected change, it indicates that the driver is operating in single mode (no other drivers detected) . If the measured voltage change is smaller than the expected change (considering the tolerance range), it indicates that the driver is operating in parallel mode with at least one other driver sharing the load. Based on the comparison, the control unit arrives at one of two conclusions: If the measured voltage change falls within a tolerance range around the expected value, the system confirms that the driver is operating alone. If the measured voltage change is lower than this range, the system concludes that another driver is operating in parallel.

[0090] Fig. 4 thus illustrates a key aspect of the invention: the ability of the LED driver 10 to autonomously detect its operating status by shifting the droop characteristic curve and comparing voltage changes. This process enhances the adaptability and performance of the system, particularly in configurations where multiple drivers are connected in parallel.

[0091] To summarize, this invention offers an advanced LED driver capable of autonomously detecting its operational status and adjusting its performance for optimal operation in both single and parallel modes. This enables dynamic load balancing and system optimization.

[0092] The droop characteristic curve is automatically adjusted based on the detected operating status. In single mode, the curve is flattened to provide stable voltage regulation, while in parallel mode, the original curve is restored for efficient load sharing.

[0093] The system is scalable, allowing multiple LED drivers to be connected in parallel. The system can detect and adapt to varying numbers of parallel drivers, optimizing the load distribution dynamically.

[0094] The ability to calculate the total power supplied by parallel drivers and detect the number of drivers in parallel improves the overall system efficiency and reliability. This feature is especially beneficial in large-scale LED systems where load balancing is crucial.

[0095] 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.

[0096] 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 LED driver (10) for supplying power to an LED load (11), comprising: a droop characteristic defined by a droop characteristic curve, which represents the relationship between an output voltage and an output current of the LED driver (10), wherein the output voltage decreases as the output current increases; and a control unit configured to autonomously modify the droop characteristic curve without external input.

2. The LED driver (10) of claim 1, wherein the control unit is configured to shift the droop characteristic curve in order to determine an operating status of the LED driver, the operating status comprising single mode operation or parallel operation, wherein in parallel operation, the LED driver (10) operates in parallel with at least one other LED driver (10).

3. The LED driver (10) of claim 2, further comprises a measurement unit configured to measure changes in the output voltage and / or output current of the LED driver (10) .

4. The LED driver (10) of claim 3, wherein the control unit is configured to: determine that the LED driver (10) is in single mode operation when the measured voltage and / or current change is larger than or equal to an expected voltage and / or current change, and determine that the LED driver (10) is in parallel operation when the measured voltage and / or current change is smaller than the expected voltage and / or current change.

5. The LED driver (10) of claim 4, wherein the control unit is further configured to adjust one or more operational parameters of the LED driver (10), based on the determined operating status of the LED driver (10).

6. The LED driver (10) of claim 5, wherein the control unit is configured to: flatten the slope of the droop characteristic curve when the LED driver is in single mode operation, or restore the original droop characteristic curve when the LED driver is in parallel operation.

7. The LED driver (10) of claims 3 to 6, wherein the control unit is further configured to: calculate the total power supplied by the parallelly connected LED drivers based on the measured voltage and / or current changes, and / or determine a number of LED drivers operating in parallel based on the measured voltage and / or current changes.

8. A LED system (1) comprising: an LED load (11), and at least one LED driver (10) of any preceding claims.

9. A method (300) for detecting an operation status of an LED drive(10), comprising: measuring (301) an output voltage and / or output current of the LED driver (10); autonomously shifting (302) a droop characteristic curve, which represents the relationship between the output voltage and the output current of the LED driver (10); measuring (303) a change of output voltage and / or a change of output current based on the shifted droop characteristic curve; comparing (304) the measured voltage and / or current change with an expected voltage and / or current change; and determining (305) whether the LED driver (10) is operating in single mode or in parallel with at least one other LED driver (10) based on the comparison of the measured change and the expected change.

10. The method (300) of claim 9, comprising: determining that the LED driver (10) is operating in single mode when the measured voltage and / or current change is larger than or equal to an expected voltage and / or current change, and determining that the LED driver (10) is in parallel operation when the measured voltage and / or current change is smaller than the expected voltage and / or current change.

11. The method (300) of claim 9 or 10, comprising: adjusting one or more operational parameters of the LED driver, based on the determined operating status of the LED driver (10).

12. The method (300) of one of the claims 9 to 11, further comprising: flattening the slope of the droop characteristic curve when the LED driver (10) is operating in single mode, or restoring the original droop characteristic curve when the LED driver (10) is operating in parallel with at least one other LED driver (10).

13. The method (300) of one of the claims 9 to 12, further comprising: calculating the total power supplied by the parallelly connected LED drivers based on the measured voltage and / or current change, and / or determining a number of LED drivers operating in parallel based on the measured voltage and / or current change.

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