DE102017116647A1 - Calibration of the supply voltage for lighting systems - Google Patents

Abstract

Disclosed is a method of calibrating a supply voltage for lighting systems comprising a plurality of LED strings, comprising adjusting (301) the supply voltage of LED strings (and control units connected to clusters of strings) to a first value, from the it is expected that all the LEDs in the plurality of LED strings will function therewith, measuring (303) a voltage in a connection between each controller and its associated LED strings, and comparing (304) the measured voltage with a preset voltage for each Strand. If the measured voltage is higher than a predefined error voltage above the preset voltage, or lower than the preset voltage, a notification signal is generated in the controller (305) to notify a master unit that the supply voltage is high or low , Based on the message signal, the first voltage value is corrected (306). At least the settings for obtaining the highest value of the corrected supply voltage are stored (307, 317).

Description

Field of the invention

The present invention relates to the field of power supply of electronic systems. In particular, it relates to the calibration of the supply voltage in electronic automotive systems, such as lighting systems.

General state of the art

A common requirement for lighting systems, for example for signaling, is the stability of the lighting. This requirement is especially valid for LED lighting systems that are currently included in numerous applications due to their low power consumption. They are often found in light and signal systems of vehicles.

LED lighting systems typically include one or more LEDs connected in series to form an LED string. For special applications, LEDs can also be connected in parallel. Light sources comprising LEDs typically have the problem of reducing their intensity due to degradation, e.g. B. due to thermal degradation. Furthermore, the luminosity of such a LED string is current-dependent. To ensure a given luminosity for such a LED string, a predetermined current is required. The current can be regulated to ensure a given luminosity. Aging effects and thermal degradation may possibly be corrected. During current regulation, the voltage across the LED string may possibly vary. In order to ensure current regulation, for example by a current source or a switching element, a minimum voltage across this current source or the switching element is necessary. In addition, the voltage across the LED string should not fall below a minimum size to ensure a given brightness (brightness). If the voltage across the power source or switching element is too high, there will be high power dissipation across the power source or switching element, which can potentially lead to damage, reduced life due to overheating, degradation effects, and so on. These problems, individually or in combination, can create dangerous situations. Therefore, it is of interest, a power supply for the LED strand and its drive elements, such. As a power source or a switching element to use, which is high enough for the current control, but low enough for optimum power dissipation.

In the particular case of automotive applications, there are several different types of lighting systems. For example, these may include headlamp or lighting systems (headlamps, auxiliary lights such as fog lights), signal and visibility systems (daytime running lights, reversing lights and parking lights, tail or tail lights, direction indicators, etc.), interior lights, license plate lights, etc. These systems need to be stable and efficient, but they are rarely used all at once. For example, in automotive applications, direction indicators are used only when needed, regardless of the use of e.g. B. headlamps. In addition, different lighting systems are usually not matched, for example, because different types of LEDs and / or number of them are required. Despite the fact that systems are usually not matched, vehicles typically include a single power source for all their electrical devices, including lighting systems (usually a battery). To avoid compromising the lighting conditions of a system in use when a second system is activated, custom control of each system is usually provided. In this way, systems can have stable lighting at the expense of greater complexity. For example, to get an optimal supply voltage that meets the needs of all possible LED strings, e.g. For example, in the taillights, the power management system would need to be tailored for each LED model and / or architecture, depending on the type of vehicle and even the brand. It would also have to have a final calibration, depending on the model of the tail light, for example on the production line at the supplier of the energy management system. This implies the use of different parts and devices for each different model, resulting in a higher logistic effort to cope with the differently configured master control units. Alternatively, the calibration can be done on the vehicle manufacturer's production line, which also adds cost and manufacturing time. However, long-term degradation can not be taken into account in these systems, so there is room for improvement.

Brief description of the invention

It is an object of embodiments of the present invention to provide a system for driving one or more lighting systems with voltage calibration capabilities, particularly for automotive applications.

It is an advantage of embodiments of the present invention to provide a calibration method for lighting systems with great flexibility and simplicity, and providing lighting stability for a wide range of applications, lighting systems, and configurations.

• - Einstellen der Versorgungsspannung auf einen ersten Spannungswert, von dem zu erwarten ist, dass alle LEDs in der Vielzahl von LED-Strängen damit funktionieren,
• - Bereitstellen des ersten Spannungswertes für die Vielzahl von LED-Strängen und für Steuereinheiten, die mit Clustern von LED-Strängen verbunden sind, wobei jeder Cluster mindestens einen LED-Strang umfasst,
• - Messen einer Spannung in einer Stiftverbindung zwischen jeder Steuereinheit und ihren jeweiligen verbundenen LED-Strängen, und Vergleichen der gemessenen Spannung mit einer voreingestellten Spannung für den jeweiligen Strang. Wenn die gemessene Spannung höher ist als eine vordefinierte Fehlerspannung über bzw. oberhalb der voreingestellten Spannung, beziehungsweise niedriger ist als die voreingestellte Spannung, kann ein Meldesignal in der entsprechenden Steuereinheit erzeugt werden, um einer Master- bzw. Haupt-Steuereinheit (MCU) zu melden, dass die Versorgungsspannung hoch, beziehungsweise niedrig ist,
• - basierend auf dem Meldesignal, Berichtigen bzw. Einstellen des ersten Spannungswertes auf eine berichtigte Versorgungsspannung, und
• - Speichern von Einstellungen zum Erhalten des höchsten Wertes der berichtigten Versorgungsspannung unter den Versorgungsspannungen, die pro Cluster zum Erreichen der voreingestellten Spannung in jedem Cluster notwendig ist, wenn mindestens eine Steuereinheit jedes Clusters eine gemessene Spannung erkennt, die höher ist als die voreingestellte Spannung und um weniger als die vordefinierte Fehlerspannung von der voreingestellten Spannung für diesen Strang abweicht.

In a first aspect, a method of calibrating a supply voltage for lighting systems comprising a plurality of light emitting diode (LED) LED strings is described, the method comprising:

• Adjusting the supply voltage to a first voltage value that is expected to cause all the LEDs in the plurality of LED strings to function therewith;
• Providing the first voltage value for the plurality of LED strings and for control units connected to clusters of LED strings, each cluster comprising at least one LED string,
• Measuring a voltage in a pin connection between each control unit and their respective connected LED strings, and comparing the measured voltage with a preset voltage for the respective string. If the measured voltage is higher than a predefined error voltage above or above the preset voltage, or lower than the preset voltage, a notification signal can be generated in the corresponding control unit to notify a master control unit (MCU) in that the supply voltage is high, or low,
• based on the notification signal, adjusting the first voltage value to an adjusted supply voltage, and
• Storing settings for obtaining the highest value of the rectified supply voltage among the supply voltages necessary per cluster to reach the preset voltage in each cluster when at least one controller of each cluster detects a measured voltage higher than the preset voltage and at less than the predefined error voltage deviates from the preset voltage for that string.

It is an advantage of embodiments of the present invention that control of a complex lighting system or complex lighting systems can be provided with a limited amount of control units and a single master control unit. It is a further advantage that a calibration of voltage drop variations across the LED strings can be obtained depending on the system usage, the activation scheme thereof, and / or the degradation. In some embodiments, the settings may be stored in memory. The settings may include, for example, the settings of a voltage converter to obtain at least the highest supply voltage among all the supply voltages that the clusters might need. Saving the settings may also include saving the (highest voltage supply settings to obtain the highest corrected supply voltage and configuration, e.g. The particular cluster used, which require such highest corrected supply voltage. Storing the settings may also include storing the settings of a voltage converter to obtain each corrected voltage needed by each cluster. It is an advantage that at least the maximum supply voltage can be used, or a rectified supply voltage optimized for a particular configuration, or the highest corrected voltage from a pool of corrected voltages per cluster selected in accordance with the particular cluster is used.

Some embodiments of the present invention may further include providing a signal indicating that calibration is complete when all controllers detect a measured voltage that is higher than the preset voltage and less than the predefined error voltage from the preset voltage for deviates from this strand.

It is an advantage of embodiments of the present invention that an operator can be confident that the calibration has been successful.

Some embodiments of the present invention may further comprise the step of performing some or all of the steps of the method at predetermined time intervals.

It is an advantage of embodiments of the present invention that illumination variations of the LED systems due to temperature changes, degradation, etc. can be compensated regularly.

In some embodiments of the present invention, the preset voltage per cluster and / or strand may be defined.

In further embodiments, the preset voltage may be varied in accordance with the illumination configuration of clusters and / or the application.

It is an advantage of embodiments of the present invention that the preset voltage can be selected in accordance with the type of LED, the number of LEDs in a string, and the required illumination, thus taking into account the granularity of the lighting system.

In some embodiments of the present invention, the predefined error voltage may be varied in accordance with the illumination configuration of clusters and / or the application.

It is an advantage of embodiments of the present invention that the resulting illumination may be more robust to changes, unwanted spikes, or supply and / or external supply (eg, battery) disturbances.

In some embodiments of the present invention, the preset voltage and / or the predefined error voltage may be programmed.

Some embodiments of the present invention may further comprise storing the setting of the converter to obtain the highest corrected supply voltage value required by all clusters, and further comprising adjusting the supply voltage to the highest adjusted supply voltage value after another power up.

It is an advantage of embodiments of the present invention that the power supply for all LED strings can be secured, which reduces the chance that an LED string will be under powered and produce less illumination. It is an advantage of embodiments of the present invention that a single VS can be used, thereby reducing computational load and memory usage.

Alternative embodiments of the present invention may include storing each of the settings of the voltage converter to provide corrected supply voltage levels required by each cluster, and further comprising adjusting the supply voltage in accordance with the highest adjusted supply voltage value from at least one of the active control units is imposed after further turning on these control units to reach the preset voltage for powering at least each LED string.

It is an advantage that the highest supply voltage may be dependent on the active clusters, and may change during use, providing optimum drive depending on the specific operation.

• - mindestens eine LED-Antriebseinheit pro LED-Strang in dem Cluster,
• - eine Spannungslesevorrichtung zum Ablesen der Spannung an einem Knoten zwischen der Steuereinheit und jedem LED-Strang,
• - einen Spannungskomparator zum Vergleichen der gemessenen Spannung mit einer voreingestellten Spannung für diesen Strang,
• - einen Signalgenerator zum Erzeugen eines ersten Signals, falls die gemessene Spannung eine vordefinierte Fehlerspannung über der voreingestellten Spannung übersteigt, oder eines zweiten Signals, falls die gemessene Spannung die voreingestellte Spannung nicht erreicht,
• - Übertragungsmittel zum Senden mindestens irgendeines ersten oder zweiten erzeugten Signals an die MCU, wobei die MCU des Weiteren Mittel zum Berichtigen der Ausgangsversorgungsspannung in Übereinstimmung mit den Signalen umfasst, die in jeder der Steuereinheiten erzeugt werden.

In a second aspect, a system for powering a plurality of clusters comprising at least one LED string. The system may include a master controller (MCU) including a voltage converter for providing an output supply voltage and at least one interface for communicating with a plurality of controllers, at least one controller for powering at least each LED cluster (hence one or more controllers per cluster). Each control unit includes:

• at least one LED drive unit per LED string in the cluster,
• a voltage reading device for reading the voltage at a node between the control unit and each LED string,
• - a voltage comparator for comparing the measured voltage with a preset voltage for that string,
• a signal generator for generating a first signal if the measured voltage exceeds a predefined error voltage above the preset voltage or a second signal if the measured voltage does not reach the preset voltage,
• Transmission means for transmitting to the MCU at least any first or second generated signal, the MCU further comprising means for adjusting the output supply voltage in accordance with the signals generated in each of the control units.

It is an advantage of embodiments of the present invention that an MCU be provided for one or all LED strings that may be remote from the power source. It is a further advantage that fewer control units than LED strings are needed when grouping LED strings, for example one controller per LED cluster or z. B. a controller for each taillight illumination system. It is another advantage that this implementation can be applied to a wide variety of vehicles and brands; z. For example, the present invention may provide a universal lighting system.

In some embodiments of the present invention, the control unit may be integrated into a single integrated circuit.

It is an advantage of embodiments of the present invention that a compact, modular control per lighting system can be obtained.

In some embodiments of the present invention, the MCU further comprises a configuration memory for storing a plurality of settings of the voltage converter for obtaining rectified supply voltages, and a cluster lighting configuration for which the value has been obtained.

It is an advantage of embodiments of the present invention that the first supply voltage can be optimized in a prior calibration, thereby potentially reducing the chances of further calibration required.

In some embodiments of the present invention, a secondary LIN network is provided between the controllers and the MCU, separate from a primary network for connecting the master controller to a higher level system.

It is an advantage of embodiments of the present invention that isolation between the primary network and the secondary network is obtained, thereby reducing interference, thereby reducing, for example, crosstalk between the elements of the primary network and the lighting system.

In alternative embodiments, a CAN network is provided between the controllers and the MCU to provide a direct connection to a higher level system.

It is an advantage of embodiments of the present invention that the communication network can be made simpler, with all elements connected to a single network, which for example improves the problem diagnosis.

In some embodiments of the present invention, the control unit further comprises a processing unit for controlling the LED drive units, obtaining the measured voltages from the voltage reading device and comparing them with the preset voltages, and generating signaling signals.

It is an advantage of embodiments of the present invention that a compact control can be obtained.

Particular and preferred aspects of the invention are set forth in the appended independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims and with features of other dependent claims, as appropriate, and not solely as set forth in the claims.

These and other aspects of the invention will be explained below with reference to the embodiment (s) described hereinafter.

list of figures

• 1 eine erste Ausführungsform eines Systems gemäß einem Aspekt der vorliegenden Erfindung, umfassend ein sekundäres Netzwerk zwischen einer Master-Steuereinheit und einer Vielzahl von Steuereinheiten,
• 2 eine weitere Ausführungsform eines Systems gemäß einem Aspekt der vorliegenden Erfindung, umfassend ein einzelnes Netzwerk zur Kommunikation zwischen einem höherstufigen System, der Master-Steuereinheit und der Vielzahl von Steuereinheiten,
• 3 ein Ablaufdiagramm eines Verfahrens gemäß Ausführungsformen der vorliegenden Erfindung, einschließlich optionaler Schritte,
• 4 ein Ablaufdiagramm eines Kalibrierverfahrens gemäß Ausführungsformen der vorliegenden Erfindung, das auf einzelne Cluster oder auf viele Cluster gleichzeitig anwendbar ist, mit einer ersten niedrigen Versorgungsspannung,
• 5 ein Ablaufdiagramm eines Kalibrierverfahrens gemäß Ausführungsformen der vorliegenden Erfindung, das auf einzelne Cluster oder auf viele Cluster gleichzeitig anwendbar ist, mit einer hohen Versorgungsspannung.

Show it:

• 1 A first embodiment of a system according to an aspect of the present invention comprising a secondary network between a master controller and a plurality of controllers;
• 2 another embodiment of a system according to one aspect of the present invention comprising a single network for communication between a higher level system, the master controller and the plurality of controllers;
• 3 3 is a flowchart of a method according to embodiments of the present invention, including optional steps;
• 4 3 is a flow chart of a calibration method according to embodiments of the present invention that can be applied to individual clusters or to many clusters simultaneously, with a first low supply voltage;
• 5 a flowchart of a calibration method according to embodiments of the present invention, which is applicable to individual clusters or to many clusters simultaneously, with a high supply voltage.

The drawings are purely schematic and not restrictive. In the drawings, for illustrative purposes, the size of some elements may be exaggerated and may not be to scale.

Any reference numbers in the claims are to be construed as not limiting the scope. In the different drawings, the same reference numerals refer to the same or analogous elements.

Detailed Description of Illustrative Embodiments

The present invention will be described with respect to particular embodiments and with reference to certain drawings, but the invention is not limited thereto, but only by the claims. The drawings are purely schematic and not restrictive. In the drawings, for illustrative purposes, the size of some elements may be exaggerated and may not be to scale. The dimensions and relative dimensions do not correspond to actual reductions in the practice of the invention.

The terms first, second and the like in the description and in the claims are used to distinguish between similar elements and not necessarily to describe a sequence either temporally, spatially, orderly or in any other way. It will be understood that the terms so used are interchangeable with each other in appropriate circumstances and that the embodiments of the invention described herein are operable in sequences other than those described or illustrated herein.

Moreover, the terms top, bottom and the like are used in the description and claims for descriptive purposes and not necessarily for describing relative positions. It should be understood that the terms so used are interchangeable with each other in appropriate circumstances and that the embodiments of the invention described herein are operable in other orientations than those described or illustrated herein.

It should be noted that the term "comprising" as used in the claims should not be interpreted as limited to those listed thereafter; he does not exclude other elements or steps. Consequently, it should be interpreted to specify the presence of the specified features, integers, steps, or components as referenced, but the presence or addition of one or more other features, integers, steps, or components or groups thereof, not a priori excludes. Consequently, the scope of the term "a device comprising means A and B" should not be limited to devices consisting solely of components A and B. become. It means with reference to the present invention that the only relevant components of the device are A and B.

The reference throughout this specification to "the embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, occurrences of the phrases "in the embodiment" or "in one embodiment" at various points in this entire specification may not necessarily all refer to the same embodiment, but they may. In addition, the particular features, structures, or features may be combined in any suitable manner in one or more embodiments, as would be apparent to those skilled in the art from this disclosure.

Similarly, it should be appreciated that in describing exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure or description thereof for the purpose of streamlining disclosure and assistance in understanding one or more of the various aspects of the invention. However, this disclosure method is not to be interpreted as reflecting an intention that the claimed invention requires more features than expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single previously disclosed embodiment. Accordingly, the claims which follow the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

Moreover, while some embodiments described herein include only certain features included in other embodiments, combinations of features of different embodiments are intended to be within the scope of the invention and to formulate various embodiments, as those skilled in the art would understand. For example, in the following claims, any of the claimed embodiments may be used in any combination.

In the description provided herein numerous specific details are set forth. It is understood, however, that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail so as not to obscure the understanding of this description.

In general lighting systems require a stable illumination intensity. When a variety of lighting systems, which may vary in style and design, are powered by a single power source, compensation is required to ensure that all systems receive a voltage that is high enough to activate the light sources. On the other hand, it is also desirable to reduce the power dissipation that usually occurs when light sources or their drive elements are overloaded with a voltage higher than that required to provide sufficient illumination.

These requirements are particularly important in automotive applications where there is typically a single constant source of energy in the vehicle (eg, a battery). For safety reasons, sufficient intensity should be provided in all lighting systems. In an extreme example, the headlights should not dim their lighting when the direction indicators are used. The only energy source must be able to sustain all of the electronic systems, including the different types of lighting systems, and provide a stable energy supply in all of them. However, the electronic network should not be overly complex. Less complexity facilitates installation, problem diagnosis, parts replacement, lower system costs, etc.

Vehicle-based lighting systems in vehicles are typically distributed in multiple LEDs, including a plurality of LEDs connected in series. LEDs have lower energy consumption, but they tend to suffer degradation as well as thermal degradation over time (with advancing age).

Wherever reference is made to an "LED string" in embodiments of the present invention, reference will be made to a plurality of LEDs connected in series. Different LED strings of any or all lighting systems can be powered by a power supply be supplied. Wherever reference is made to a "supply voltage (VS)" in embodiments of the present invention, reference will be made to the supply voltage for the different LED strings and their drive elements of a particular system or for all lighting systems.

A particular lighting system according to the embodiments may include one or more LED strings forming an "LED cluster." A particular lighting system may include at least one LED cluster.

In a first aspect of the present invention, a system is provided that provides control and compensation for variations in the voltage drop of electronic systems, including lighting systems. In particular, voltage calibration is provided for one or more LED lighting systems comprising LED clusters using a master control unit (MCU) and at least one control unit per LED cluster.

The MCU includes at least one connection to a power source (eg, a battery, for example, a 12V or 48V battery) and at least connections to the plurality of LED clusters, for example, parallel connections to the LED clusters to provide a supply voltage VS to the lighting systems. For example, the MCU may include at least one converter for adjusting a voltage from a power source (eg, battery) to an output supply voltage VS for the lighting system. In this way, the MCU provides a common supply voltage for all LED strings across the converter.

Consequently, all LED strings are connected to only one common supply voltage output from the MCU. Since the LED strings may differ in the number and type of LEDs, the present invention provides for optimizing the supply voltage VS an MCU adapted to correct its output supply voltage in accordance with the energy requirements of the LED clusters. For example, the MCU may include a regulator, such as a voltage regulator or calibrator. The control may alternatively or additionally be provided by controlling the converter using a microcontroller. The scheme can z. B. be done by any suitable, adjustable, linear voltage regulator. For example, a controller may include an adjustable switching power supply. The particular implementation of the switched mode power supply may include a buck converter, a boost converter, an inverse converter, or any other switching power supply for regulating the car battery voltage level to a supply voltage level adapted for powering an LED string / strings and their drive elements.

The MCU may optionally include fail-safe and diagnostic mechanisms and functions, for example, by including a voltage measuring unit to measure the output supply voltage VS. The MCU may be capable of detecting the actual voltage provided at the output. The MCU may compare the requirements of the connected controllers to increase or decrease voltage in accordance with the calibration values needed by the controllers to ensure a proper power supply to each string. In some embodiments, the MCU has an expectation of what voltage, or voltage within an expected range, should be provided to a given controller. The expectation may be based on a calibration value stored, for example, from a previous calibration. If a controller requests a voltage outside the expected voltage range, the MCU may be able to diagnose a failure in the system. Examples of voltage measuring units include analog-to-digital converters (ADCs), comparators, optionally with an adjustable reference voltage, etc.

The MCU may also be programmed or include electronic devices to provide a gateway function to a higher level network of the vehicle, e.g. As a primary network to form, the z. B. a Local Interconnect Network (LIN) or a Controller Area Network (CAN), including appropriate protocols may be.

In some embodiments, the MCU may include a memory unit to store different calibration values, for example, associated with different lighting system configurations. The storage unit may be of any suitable type. It may be a programmable memory, such as random access memory (RAM), etc. It may be non-volatile memory (NVM), such as EEPROM, flash memory, etc., at certain times (e.g., after each Turning on the lighting system or systems) and which can reuse the values stored therein, thus providing a robust and reliable system with which Time can be saved if the system must provide the specified function in operating mode. In any case, the storage unit should preferably be able to store new or updated values at any time, e.g. In the case of a recalibration during operation, during a diagnosis or maintenance in the workshop. Consequently, a single, one-time programmable memory is less preferred.

The present invention may provide for controlling the powering of LEDs by providing at least one controller per cluster. The MCU can exchange information with the controllers of the clusters. This can be done by electrical connections. For example, the MCU may be connected to one or more controllers via a bus interface (eg, a LIN bus or CAN bus). This network can be seen as a secondary network, for example, a network containing a variety or all of the lighting systems, e.g. B. in a vehicle controls (but it could also be used any data transfer).

The controllers of the present invention include a connection to each LED string of a same cluster. In embodiments of the present invention, the connection may be given the generic name "node" or "pen".

Furthermore, the control units include a voltage measuring unit that is used to obtain the voltage drop in the LED string. For example, the voltage may be measured at a node between the LED string and the control unit, e.g. B. between the LED string and a corresponding drive element in the control unit. This voltage will be named Vpin in the present invention. This name can be extended to any type of connection.

The control unit further includes access to a memory for storing values of voltage Vr, which Vr is the minimum voltage required at the pin to drive an LED string. For example, the controller may include a connection or interface to retrieve the information from an external memory (eg, a connection to a primary or secondary network, etc.). In preferred embodiments, the information may be stored in a memory implemented in the control unit itself.

Each control unit further includes an LED driver (including, for example, variable current sources, switching elements controlled by a PWM unit, a combination of any of these, etc.) per LED string in each cluster. For example, two or three LED strings in a cluster may each be connected to a corresponding controller driver. In this case, the control unit should include at least two or three drivers. If a controller is an integrated driver circuit, the number of drivers may be limited. In such a case, if one cluster comprises more LED strings than drivers in the available control unit, the cluster could be connected to two or more controllers. For example, if the number of LED strings is very high, the cluster may be connected to a plurality of controllers, each LED string having a drive channel, e.g. B. has a connection via the pin or pin to a drive unit of a control unit of the plurality thereof. In turn, the controllers of the same cluster may obtain values of the required minimum voltage Vr for the same requirements of e.g. B. Save brightness according to the function of this particular cluster.

The control units may further comprise a unit for comparing a measured voltage with the required voltage Vr. For example, a comparator can be implemented. For example, a processing unit may be included to process the signals from the voltage measuring unit. For example, the processing unit may be a microcontroller, a CPU, or any other suitable hardware device. The processing unit may provide the MCU with a signal that includes information regarding the voltage on the pin or a voltage drop across the LED string, in particular whether it is higher or lower than a predetermined value range. The control unit may share this information with the MCU via communication interfaces in a network.

Furthermore, the control unit may optionally include a diagnostic function in a similar manner as the MCU. The control unit can read the voltage at the output of the MCU. If the voltage on the connected LED is too low, it can send messages to the MCU, for example during normal operating mode (not just during calibration). This may be enabled as before by including a voltage measuring unit, such as ADCs, comparators, optionally with an adjustable reference voltage, etc., adapted to read the voltage VS at the output of the MCU or by allowing the controllers to access a voltage measurement unit in the MCU to measure the VS.

The controllers may be provided in a separate integrated circuit, for example in monolithic circuits. The controllers may also be arranged as a plurality of circuits with their multiple components implemented as separate circuits, e.g. An ADC, a communication transceiver (eg LIN transceiver or CAN transceiver), a CPU or a state machine, a PWM unit formed as separate units.

With regard to the lighting system or systems, the clusters may be part of the same type of lighting system or each cluster may be part of a different type of system. For example, a cluster comprising two LED strings may be part of the taillight illumination, while another cluster comprising a single LED string may be part of the turn signal system. In each, according to embodiments of the present invention, all clusters are connected to the same MCU, but each cluster is connected to at least one associated control unit.

In embodiments of the present invention, a lighting system comprises at least one cluster comprising at least one LED string. Since the controllers are connected to clusters, accurate drive and voltage reading and compensation for each leg in a cluster can be obtained by using a single controller, thus reducing the complexity of the system. In some embodiments, a cluster may comprise a single strand comprising one or more LEDs. In some embodiments, a cluster may include a string with four LEDs or three LEDs. In some embodiments, combinations of multiple clusters of different types, number of strands, and / or number of LEDs per strand may be included. The system is capable of driving any of these cluster combinations that form lighting systems that may be different from one another and to ensure correct drive and illumination of all systems.

In an exemplary embodiment of the present invention, which is shown in FIG 1 is illustrated, an illumination system for a car comprises at least two clusters (two are in 1 one of the clusters comprises a plurality of strands. The MCU 10 may include a voltage converter, for. B. a DC / DC converter 16 for correcting the voltage of the power supply (eg vehicle battery supply) VBAT to a supply voltage VS for z. B. the taillight system of a vehicle. The supply voltage VS may be higher or lower than the car battery supply.

The lighting system may have different LED clusters 29 . 30 and each LED cluster can have one or more LED strands 27 . 31 comprise, wherein the LED strands each at least one LED, possibly a plurality of LEDs 26 which are connected in series include. Although the present invention may be used on strings comprising a single LED, it is advantageous to have multiple LEDs in series, since the correct power supply of all the LEDs in the string is ensured, thereby providing a system with much better illumination and visibility capabilities than one single LED is allowed.

Furthermore, the MCU 10 possibly a voltage measuring unit 14 , for example, an ADC or a comparator with an adjustable reference voltage, for measuring the output supply voltage VS of the voltage converter, for. B. DC / DC converter, with which the different LED strands are supplied, include.

The MCU 10 may further include a storage unit 11 for storing a value of the supply voltage VS to be used at the beginning of a calibration procedure. It can store the voltage converter settings to adjust the VBAT voltage to the supply voltage for the lighting systems. The storage unit 11 Optionally, it may store other values, such as required minimum voltages for LED strings and information regarding previous calibrations.

While the output supply voltage VS to supply the LED strings from the MCU 10 can be controlled and measured, the voltage drop or the current through the LED strings from a control unit, for. B. a control unit 20 leading to each corresponding LED cluster 29 . 30 is associated, also controlled and measured. The control unit 20 In embodiments of the present invention, not only can the power supply to the associated LED clusters be controlled (eg, by controlling the current through each leg), but also can measure parameters related to the power supply, such as the voltage at each pin, optionally at the supply voltage VS, and it can also derive the voltage drop in each strand of the cluster. Referring to 1 includes a control unit 20 , z. B. a control IC of the tail lamp, an LED drive unit for driving the LED strands 27 . 31 and Z. B. to control their activation and their brightness. The LED drive unit may be, for example, a controllable power source 23 , a switching element 22 (eg, a transistor) controlled by a PWM drive unit, or a combination of both.

In the 1 shown control units 20 each include two LED drive units; however, this is not limiting on the present invention. In the in 1 implementation are both LED drive units of the control unit 20 that with the cluster 29 used, which includes two LED strands used. However, there will only be one LED drive unit of the control unit that is connected to the cluster 30 used, which comprises a single LED string. It can be seen that the same architecture can be used for a wide range of applications, configurations and vehicle models without having to fabricate their own controls. The control units 20 close a voltage measuring unit 24 , z. B. an ADC, for reading the voltage at the connection between the control unit 20 and the LED string. In particular, each LED drive unit of the control unit can be connected to a string of the associated cluster. In some embodiments of the present invention, a driver pin may be included in the cluster at the junction between the controller and the LED string. For example, a driver pin may connect a microchip that includes the controller and the LED string. In embodiments of the present invention, there may potentially be different voltages Vpin on the driver pins for different LED strings. For example, an LED string 31 possibly connected to the pin DRV1 and, consequently, to an LED drive unit. Another LED strand 27 may possibly be connected to another pin DRV2 and thus to another LED drive unit of the same cluster 29 ,

The voltage measuring unit 24 may possibly z. B. connected via a multiplexer (not shown here) to each pin, including the pin for the supply voltage VS. A multiplexer has the advantage of being able to read voltages on a plurality of pins with a single device, thus improving the compactness. Such a voltage measuring unit 24 can z. B. comprise an ADC and / or a comparator with a configurable reference voltage. The control unit 20 may further comprise a processing unit, for example a microcontroller 25 that measures the voltage measurement unit 24 read and process. The microcontroller 25 can also control the power supply of the LED strings by the controller via the driver, z. B. via the controllable power source 23 , and / or the PWM drive unit 21 provided. The control unit 20 may have access to a storage device (eg, a device included in the control unit 20 is included, or access to the storage device 11 implemented in the MCU) which stores a plurality of required voltages Vr to perform the comparison. The memory may include programmable capabilities so that the Vr can be varied and corrected according to each particular application.

The processing unit 25 can furthermore with a communication interface 28 the control unit 20 be connected to the MCU 10 to tell whether the measurement is within the adopted parameters or not. The control unit 20 includes a signal generator to generate a signal and send it to the MCU 10 if the measurement is higher or lower than expected, for example outside a predetermined error margin. The MCU 10 The supply voltage VS would then each decrease or increase.

It should be noted that any part or all parts of the control unit 20 may be included in a single integrated circuit, such as a semiconductor chip, thereby further improving compactness.

The master control unit 10 can be a secondary communication interface 15 for data exchange with the communication interface 28 each control unit 20 of the system. As a result, the MCUs communicate 10 and the control units 20 with each other via this secondary network, e.g. B. over the lines 17 of the secondary network. This is advantageous in many vehicles that have their own network architecture for some or all of the lighting systems, separate from the rest of the network architecture, and reduce risks of interfering with other systems of the vehicle, e.g. Advantageously, this secondary network does not have to demonstrate high performance, so the implementation costs can be reduced, such as security systems, engine control and cruise control, distance and impact sensors, air conditioning, communication systems, etc. By using a LIN. Implementing multiple controllers into a secondary network is usually less expensive than implementing them on the CAN with a complete vehicle wiring and providing a single connection to the CAN via the MCU. In this case, the MCU is a CAN-LIN gateway. Other implementations, however, are permitted. For example, a CAN may be used for MCUs and controllers if the system is seen as a safety-critical system, as in 2 shown. In other embodiments, the MCU may be connected to a LIN for very low network cost. In such a case, the MCU is a slave with respect to a higher-level network, but a master with respect to all the control units. In this case, the MCU is a LIN-LIN gateway.

The exchanged data may include at least data as to whether the voltage drop measurement has been made and the result thereof (from the control unit 20 to the MCU 10 ), but they may also include other signals, for example, signals to enable calibration.

The voltage converter 16 , z. As the DC / DC converter, the MCU 10 provides an adjustable output supply voltage VS. If a first group of clusters is used, a corrected supply voltage value VS may be obtained, which may differ from the corrected value when using a second, different group of clusters. The plurality of received rectified supply voltages VS can form a list of calibration values. These calibration values can be stored, for example in a central memory of the vehicle or in a memory unit 11 that in the MCU 10 is included.

The status of the system or systems may be communicated to a higher level processing unit (eg, the onboard power supply control module (BCM) or similar control of a vehicle), for example, to receive commands to the central processing unit.

The higher level processing unit may also provide control over which of the lighting systems must be activated. The communication can be provided by a dedicated primary communication interface 13 that in the MCU 10 which is connected to the primary network, e.g. B. over network lines 18 provides. However, the present invention is not limited to this architecture. In some embodiments of the present invention, the primary and secondary networks are contained in a single shared network as described above.

Such an embodiment is in 2 sketched, which shows a special vehicle architecture with a common network. A shared network can be easily obtained with a CAN implementation of the primary and secondary networks. In this case, only one communication interface 113 in the MCU 10 needed. Two communication paths, one line CAN-High 101 (CANH) and a CAN-Low line 102 (CANL) can be included together with a ground line. In this case, a signal through the CAN to the MCU 10 are sent to start a calibration. The communication between control units 120 and the MCU 10 is done by the CAN via general interfaces 128 in the control units 120 , The activation schemes using these lines are known in the art.

In a second aspect, a method of voltage calibration for an LED-based lighting system is presented. The method permits the calibration of a supply voltage for lighting systems comprising a plurality of light emitting diode (LED) LED strings, compensating for the effects of differences in the LED strings, such as the number or type of LEDs in the LED strings Strands and consequently the voltage drop across the LED strings.

The method shown schematically in the flowchart of 3 outlined, includes the steps of setting 301 the supply voltage to a first voltage VS, from which it can be expected that all the LEDs in the plurality of LED strands work with it. This first voltage may be a calibration value, for example a calibration value obtained during a previous calibration procedure and stored in a memory. In embodiments of the present invention, a voltage converter (eg, the DC / DC converter 16 . 116 ) supply voltage VS from an external power source (eg, the battery of a vehicle) by converting the voltage into the output supply voltage. The method further comprises the step of providing 302 the first voltage value for the plurality of LED strings 27 . 31 and for control units 20 . 120 , The LED strands 27 . 31 are to clusters 29 . 30 grouped, each cluster 29 . 30 includes at least one LED string. The method may be advantageous for a variety of clusters 29 . 30 thus applying the same voltage to a plurality of clusters and obtaining centralized control. In embodiments of the present invention, the method is used to power a plurality of clusters, wherein at least one cluster comprises a plurality of LED strings. Different clusters may need to but not to include a different number of LED strings. High execution and installation flexibility can be achieved by grouping multiple LED strings and connecting them to the same control unit 20 . 120 while providing an adjustable common supply voltage VS for all LED strings of one or more clusters. Another advantage is the improvement of compactness and cost of the system. A drive unit requires a certain area of a package and / or an IC. A compact microcontroller should be able to drive at least two or three strands of a cluster.

The method further includes measuring 303 at least one parameter related to the power supply of the LED string. For example, the method may include measuring a voltage Vpin at a node between each control unit 20 . 120 and their respective strand or strands. For example, the node may connect an LED string to the connection to the MCU 10 be, or analogously thereto, the connection of the LED string to the corresponding LED drive unit in the control unit 20 . 120 , The voltage drop (VS-Vpin) across each leg, between the supply voltage and the voltage at the node between each leg and the control unit, can be additionally obtained, which may vary from cluster to cluster, or even between strings of the same cluster.

The obtained voltage Vpin at the node between a string and the control unit is then compared with a preset voltage Vr 304 that is required for each strand. The preset voltage may be the minimum analog voltage required to provide needed light information of a given LED string connected to the control unit. The preset voltage Vr may advantageously be as low as possible to provide minimum power dissipation in the control unit, but as high as necessary to allow proper current or voltage control of the connected LED string.

In embodiments of the present invention, the preset minimum voltage Vr may be different for each cluster, chosen according to the application (eg, lights for lighting have different requirements than lights for visibility, so the Vr in clusters of these systems will be different becomes). Also, each strand may be assigned a different Vr, advantageously taking into account a different number of LEDs in each strand for the same cluster. In some embodiments, the preset minimum voltage levels Vr may be programmable.

Measuring and comparing may be performed in any suitable voltage measuring circuit, e.g. An ADC 24 . 124 , and processing unit of the control unit 20 . 120 (eg in the microcontroller 25 . 125 ) respectively. A signal may be generated according to the result of the comparison 305 become. If the voltage measured at the node between the LED string and the control unit is lower than a predefined error voltage, lower than the preset voltage Vr, the MCU will 10 reported 308 in that the supply voltage VS is too low. The preset voltage Vr may be, for example, between 0.5 V and 3.0 V, e.g. B. 0.5 V or 1 V or 2 V or 3 V. For example, the predefined error voltage may be between 5 and 20% of the Vr. In general, the fault voltage must not be too low to provide a rugged drive. In some embodiments of the invention, a "LOW" annunciator may be generated in the corresponding processing unit, for example in the microcontroller, to the MCU 10 to report that the supply voltage VS is too low. The generated signal may include information regarding the value of the measurement (how low the measurement is) and / or how much it deviates from the preset voltage Vr. The communication may be through any suitable communication network, such as a wireless network (although less preferred because the costs are higher). Preferably, the MCU exchanges (receives and / or transmits) 10 Data with the control units over a wired communication network. The controllers receive information for driving the lighting system and send diagnostic information back to the master unit 10 , For example, the information may relate to the current through the LED string, the voltage drop across an LED string, the voltage at the point of connection of the LED string to the drive elements, the supply voltage VS, and so on. In some embodiments, the MCU 10 send the information to a primary network in a gateway function. In some embodiments, all controllers are 20 . 120 and the MCU 10 in the same network hierarchy and are controlled by the primary network. In other embodiments, any or all of the controllers are 20 . 120 with the MCU 10 connected via a secondary network, and the data exchange with the primary network is performed by the MCU 10 , Any other suitable communication means may be used, resulting in a highly flexible method.

In addition, the method may include generating a notification signal that is different from the "LOW" signal when the measured voltage is higher than a predefined error voltage, higher than the preset voltage Vr. The signal, identified as a "HIGH" signal, indicates 309 in that the supply voltage is too high and may include information regarding the value of the measurement, and / or how much it deviates from the preset voltage Vr.

In embodiments of the present invention, the predefined error voltage above and below the preset voltage Vr may be application-dependent and different for each cluster. This depends on the resolution setting of the measurement, and it may be different for the strands of a cluster, but usually it is the same. The predefined error voltage above the preset voltage Vr may differ from the predefined error voltage below the preset voltage Vr. Furthermore, a plurality of the predefined error voltages may be stored and used in accordance with the particular configuration and / or application, ensuring hysteresis in the control loop between increasing or decreasing the supply voltage VS, as explained below. In some embodiments, the predefined error voltage levels may also be programmable.

The method further includes correcting 306 the supply voltage VS in a corrected supply voltage VS, based on the received message signal. In some embodiments of the present invention (eg, the embodiment of FIG 1 ), a change of the output from the voltage converter, z. B. DC / DC output, supply voltage VS from a control unit, eg. B. a microcontroller 12 . 112 in the MCU 10 be performed.

If the MCU 10 receives a "LOW" signal then raises the MCU 10 the supply voltage VS (eg, by increasing the voltage conversion, for example, by changing the configuration or setting of a DC / DC converter by means of a microcontroller) to ensure proper lighting and control of each LED string of each cluster. The MCU 10 increases the supply voltage VS until the voltage Vpin at the node between the LED string and the control unit reaches or exceeds the preset voltage Vr. When this state is reached for all the LED strings of all the controllers of a given cluster, the calibration for that given cluster is complete and a particular VS setting for that given cluster is taken by the MCU 10 stored, at least temporarily stored. The whole calibration is finished when all control units of all clusters have been detected. The MCU 10 then derived individual VS settings per cluster during calibration.

On the other hand, if the MCU 10 receives a "HIGH" signal, then reduces the MCU 10 the supply voltage VS until the voltage Vpin at the node between the LED string and the control unit reaches the preset voltage Vr, thereby reducing the power dissipation and heating in the drive elements of the control unit, and ultimately the risks of damaging or reducing the service life of the drive elements Control units are reduced. Calibration for a given cluster is complete when the first controller reaches this state for the first connected string. The MCU 10 may then increase the voltage VS only in a small step, so that the Vpin is again higher than the Vr. The calibration is complete when all control units of all clusters have been detected. The MCU 10 then also derived individual VS settings per cluster during calibration.

In embodiments of the present invention, the voltage Vpin at the node between the LED string and the control unit need not exactly match the preset voltage Vr, and it is sufficient that the voltage Vpin at the node between the LED string and the control unit within a predefined error of, but higher than, Vr is. This ensures that the required minimum voltage is provided to all the LED strings of a given cluster.

In embodiments of the present invention, the MCU uses 10 the setting that results in the highest VS, the value from the derived individual VS settings for each cluster, and stores this setting for further use. The MCU 10 can be programmed to select the highest of the different required supply voltages than the corrected output supply voltage VS. 310. Consequently, no LED string is power-undersupplied, and correct lighting can be obtained.

In other embodiments, the setting of the converter leading to the highest VS and the configuration of clusters resulting in this highest VS are stored 307 , When the same clusters are activated, the MCU uses the highest VS stored for this configuration. In Other embodiments of the present invention use the MCU 10 All derived individual VS settings per cluster and stores these settings 317 for further use. Because the MCU 10 possibly via the bus interface according to 1 controls all clusters of the lighting system has the MCU 10 always the information about which cluster is in operation. The individual VS setting for a given cluster may possibly be chosen to provide the lighting system with VS. If multiple clusters are operating at the same time, it may be possible to select the VS setting of the cluster that will result in the highest VS for all lighting systems (eg, all clusters).

The stored setting includes the setting or configuration of the voltage converter for converting the voltage of a main source to the required corrected output supply voltage, and may also include information regarding the number of driven strings, the illumination intensity, the VS value needed to produce the Vr to reach for all strands in this cluster. Saving a setting may include storing data values. For example, during calibration, different data values are collected for the supply voltage VS (depending on the clusters). These data values can be stored in a memory. The data value for the supply voltage VS, data for setting the converter and providing such data values of the supply voltage VS and the clusters according to these values can be stored. The voltage converter may include a control register. For an 8-bit register, data values can be stored in a range between 00 Hex and FF Hex. Each stored data value may possibly correspond to an analog output value of a different supply voltage VS. The MCU may select a data value from memory (depending on which cluster is used) and may include that value in the control register for the converter. If more clusters are used in another power supply of lighting systems, the MCU can select the setting that provides the highest value of all activated clusters.

Optionally, a third type of alert signal may be provided 311 if the signal is within the prescribed parameters (eg, within the predefined error voltage), thereby serving as a test signal to indicate that the LED cluster is functioning and that the communication channels are active ,

In some embodiments, where a single Vr per function is defined (eg, to obtain the VSs needed for all LED strands of a single cluster in which all Vr's are the same for all strands), the method can using "HIGH" and "LOW" signals. In such a case, the MCU stores the VS setting for that particular cluster in accordance with the minimum required to operate, but results in lower power dissipation. However, if many Vr are used, only "LOW" signals can be used. In a practical example, in normal operating mode, an output voltage for fog lamp systems VS (fog) may differ from the output voltage for tail lights VS (rear). Both values can be derived during calibration and in memory 11 the MCU will be stored, for example. When the fog lamps and taillights are on, the setting of the converter providing the highest VS is selected by the MCU (either fog lamp or tail lamp), because if the lowest VS were selected then a lighting system might not work in accordance with the given luminosity , Thus, the MCU does not adapt the VS in accordance with a lower VS request ("LOW" signal) if the Vpin exceeds Vr, in this particular case of clusters with different Vr.

In another embodiment, several predefined error voltages may possibly be given to ensure a given hysteresis between increasing / decreasing the supply voltage VS in order to have enough margin against disturbances on the supply voltage VS.

The method further includes storing 307 the corrected supply voltage settings as previously described. The rectified supply voltage may be stored in an external memory unit or it may be stored in an internal memory unit, for example a memory unit in the MCU 10 ,

In some embodiments of the present invention, a signal from the MCU 10 generated 312 which can be sent to an output through the primary network, indicating that the calibration is complete (for example, setting a "configuration finished flag").

In one embodiment of the present invention, this flag can also be stored in one of the described memories, so that during a next system start-up possibly no more calibration step is needed.

In embodiments of the present invention, the method includes starting with a first supply voltage VS that is very low (low enough to ensure that no cluster has the required voltage Vr in any of its strings) or very high (high enough to ensure that all Strands of all clusters have a voltage that is at least higher than Vr) may be. All Vpin voltages are measured on all controllers and all clusters. During calibration, there may be two options depending on the first supply voltage VS.

a) 4 illustrates a first possibility wherein a low supply voltage VS is set 313 The state Vpin> Vr is not satisfied for any Vpin. Send the microcontroller 308 a LOW signal and the MCU increases 306 the supply voltage. The state Vpin> Vr may possibly be satisfied for a first Vpin in a given cluster. The rest of the strands of this cluster (and other clusters) require a higher supply voltage VS, which is why the supply voltage VS is increased. When the state Vpin> Vr is satisfied for all Vpin (all strands) of a first particular cluster, the setting S resulting in that supply voltage VS is stored for that particular cluster 307 , and the calibration of this cluster is finished 316 , For example, the setting may be as a data field, e.g. B. "S (cluster 1 )", get saved. In the case of a single cluster, the calibration would be completely terminated, but in the case of multiple clusters, the rest of the clusters still do not necessarily match the state in each of its strands. Therefore, LOW signals are generated and the supply voltage VS is further increased. When the state Vpin> Vr is reached for all vpins of a next cluster, the new setting for that cluster is saved, e.g. B. S (cluster 2 ) and so on. When all clusters are done and Vpin> Vr is satisfied for all Vpin of all clusters, calibration is terminated 312 ,

This process can be done simultaneously for all clusters, or sequentially cluster by cluster, or simultaneously for a subset of clusters, and then for at least one other subset of clusters. If the process is not simultaneous for all clusters, the clusters should be calibrated in a particular order, or alternatively, the supply voltage VS should start again at the very low first value for each cluster. The particular order may be based on an estimate of the lowest Vr needed by each cluster so that the clusters are calibrated in a sequence of increasing minimum Vr. Alternatively, if the MCU detects that a cluster has been calibrated and its calibration settings are stored, any further signal from microcontrollers of that cluster can be ignored.

b) 5 shows a second possibility, wherein a high supply voltage VS is set 314 The state Vpin> Vs is satisfied for all Vpin. The microcontrollers send a HIGH signal and the MCU lowers the supply voltage VS until the state Vpin <Vr for a first Vpin for a first cluster is reached. The value of the supply voltage VS is again increased by a small margin 315 (for example, increasing it by a predefined error voltage) to ensure that the state Vpin> Vr is present again. Alternatively, the MCU may reduce the supply voltage VS until Vpin is strictly above Vr within a predetermined error margin. In either case, the new Vpin value is closer to Vr than the first high value of the supply voltage VS, which consequently reduces the power dissipation. The settings are saved or recorded as before, eg. B. "S (cluster 1 ) ". The calibration for this cluster would be over 316 , In the case of a single cluster, the calibration of the entire system would be complete 312 but in the case of multiple clusters, the supply voltage VS is further reduced until the first Vpin for another cluster satisfies the state Vpin <Vr. The value of the supply voltage VS is then slightly increased again until the state Vpin> Vr occurs for this first Vpin of the next cluster. The setting is stored in a memory z. B. as S (cluster 2 ) recorded. The process is repeated for the remaining clusters. For each cluster calibration, the already calibrated cluster will output LOW signals that will be ignored by the MCU because the setting is already saved according to the calibrated clusters.

In this case, the setting of the minimum supply voltage VS is stored for each cluster 317 so that the state Vpin> Vr is reached for all Vpin of all controllers for a given cluster.

Both calibrations can be combined in some cases. For example, when performing a cluster-by-cluster calibration, some clusters may be calibrated beginning with a higher than required supply voltage VS to obtain Vr in all their strings, and others may starting with a lower than required supply voltage VS to obtain Vr in all their strings. For example, for a high-strands cluster, starting with a high supply voltage VS can quickly end the calibration, with values for the voltage in the node within a predefined error above Vr. On the other hand, for a cluster with one or only a few strings (eg, two), starting with a very low supply voltage VS may result in a supply voltage VS that results in one of Vr being very close to Vpin, thus reducing power dissipation. In some embodiments, only a single supply voltage VS is stored, the minimum value for which all the strings of each cluster operate with minimal power dissipation, and for obtaining a Vpin that is slightly higher than the required voltage.

1. i) die Einstellung auswählen, die zu der höchsten Versorgungsspannung VS aller gespeicherten Einstellungen führt. Dies kann auf jene Fälle angewendet werden, in denen alle Cluster zusammen verwendet werden.
2. ii) die Einstellung auswählen, die zu der höchsten Versorgungsspannung VS der Cluster führt, die zu diesem Zeitpunkt gerade verwendet werden. Die MCU verfügt über Informationen darüber, welche Cluster gerade verwendet werden und die gewählten Einstellungen stellen die höchste Versorgungsspannung VS aller verwendeten Cluster bereit. Wenn nur ein Cluster verwendet wird, dann wird die Einstellung der Versorgungsspannung VS dieses einzigen Clusters verwendet.

In a subsequent activation of lighting systems (eg, in a subsequent turn-on of one or more lighting systems), the MCU will either:

1. i) select the setting that leads to the highest supply voltage VS of all stored settings. This can be applied to those cases where all clusters are used together.
2. ii) select the setting that results in the highest supply voltage VS of the clusters currently in use. The MCU has information about which clusters are in use and the selected settings provide the highest supply voltage VS of all clusters used. If only one cluster is used then the setting of the supply voltage VS of this single cluster is used.

An exemplary implementation of the method may be used with embodiments of the first aspect of the present invention, for example, those described in U.S. Pat 2 shown embodiment. A converter 116 in the MCU 10 adjusts the supply voltage VS. This can be done by converting the voltage of an external source or battery, outputting a first supply voltage VS to the clusters 29 . 30 respectively. The control units 120 receive the supply voltage VS, which in turn become active, as well as each LED string 27 . 31 in the clusters 29 . 30 , The control units 120 may include elements for controlling the power supply of the LED strings of their associated clusters. This power supply can be achieved, for example, by current control, e.g. B. with an LED string driver 123 , in accordance with the required brightness. The voltage Vpin is at each node 103 . 104 between each LED string 27 . 31 every cluster 29 . 30 and its corresponding control unit 120 and compared with a preset required voltage Vr (stored in a memory unit, in the controller 120 or in the MCU 10 can be stored). If the result is lower than Vr or higher than an error margin over the preset required voltage Vr, a signal is generated which includes information as to whether the voltage Vpin is at the node 103 . 104 too high or too low. Every control unit 120 perform this action. Reading, comparing voltage and signal generation can be done with one or more readers and optionally integrated comparators in any combination. For example, reading with a reading device 124 and comparing and generating signals with a processing unit 125 or by any other means. However, this configuration is not limiting and the reader and comparator may be integrated in the same unit.

If at least one message signal is generated, the signal of the MCU 10 reported, for example, between a general communication interface 128 in the control and the communication interface 113 in the MCU 10 over the CAN network. After receiving the message, the MCU controls 10 the first supply voltage VS to an adjusted supply voltage VS. If several message signals are received, the MCU 10 be programmed to select a supply voltage VS which will ensure a power supply to all LED strings, thus ensuring that the optimum voltage drop is provided for at least one LED string, and at the same time a higher voltage drop for the remainder of the LED string. Strands is provided.

The MCU 10 Then, the value of the corrected supply voltage VS and the configuration of the lighting system (eg, settings of the converter that achieve such a voltage, which systems are powered, and their required brightness) can be stored in memory 11 Save ("configuration memory"). The regulation, control of the voltage measurement of the supply voltage VS and other actions such as reading the supply voltage VS at the output (eg via a voltage measuring unit 14 ) can by means of a single processing unit 112 within the MCU 10 to be controlled. When a given configuration is activated the next time, the MCU can 10 the previously saved corrected supply voltage VS, which has been obtained for this configuration, as the first output supply voltage VS provide.

It should be noted that in the case of 2 the interface 113 for communication with the control units is also used for communication with a higher-level processing unit, but as in 1 As can be seen, two interfaces can alternatively be used 15 . 13 in the MCU 10 one to communicate with the controllers through a secondary network, the other to communicate with a central unit through a primary network. In addition, some or all of the elements could be applied to and combined with any implementation of the present invention, not only in vehicles but also in industrial machinery, household appliances, etc.

The present invention can be used with multiple strands with different numbers and types of LEDs 26 be used. The granularity of the illumination system (eg how many LEDs per strand, how many LEDs per cluster) is mainly determined by the design, the optical arrangements, the required luminosity, the thermal management, the light color and other parameters.

Therefore, a preset voltage Vr (eg, the minimum required voltage to operate a given LED string, as previously defined) may be defined per cluster, or even per string, taking into account the granularity of the system. As seen earlier, multiple preset voltages Vr may be used depending on the particular light sources (LEDs, strings, clusters, groups thereof) that are on. These values can be stored in a memory of the control units 120 , for example one in the processing unit 125 memory included in the controllers, or in the memory 11 the MCU 10 or stored in a higher-level control unit. Any or all of these values may be programmable.

Several calibration values for the voltage transformer can also be stored, eg. In the configuration memory 11 the MCU 10 or in an external memory. If several clusters are switched on, the highest value of the supply voltage VS can be used.

For example, information regarding the control and status of a lighting system may be communicated to the MCU via the primary network 10 be sent. For example, calibration values for the supply voltage VS may be externally programmed for a number of configurations of lighting systems. This information can be sent to the MCU 10 which accordingly provides the required supply voltage VS for a given configuration (via the converter) after turning on the lighting systems according to the programmed configuration. The output supply voltage VS can be obtained by calculation, for example, since the given light source and its configuration are known. In other embodiments, the first supply voltage VS may be obtained by using the calibration method in a previous calibration, thus taking into account the history (degradation, etc.) of the light sources. For example, if several light sources are turned on simultaneously, that calibration value that matches the highest value of the light source power supply VS is used. This ensures an application-dependent, improved, preferably optimal energy management, so that the supply voltage on the one hand as low as possible, but still high enough, so that an individual current or voltage control of each LED string is possible.

• - Ausgangsspannung ist VS = 12 V.
• - Der Spannungsabfall über diese LED = 3 V.
• - Die Spannung an dem Stift ist $$\text{Vpin}=12\text{V}-13\text{V}=9\text{V}$$
  
• - Verlustleistung an der in der IC wäre dann P = 9 W

As an example of the importance of energy management, the following calculation takes into account a single LED, with a current of ILED = 1 A

• - Output voltage is VS = 12 V.
• - The voltage drop across this LED = 3 V.
• - The tension on the pen is $$\text{CPIn}=12\text{V}-13\text{V}=9\text{V}$$
  
• - Power loss at the IC would then be P = 9W

• - Ausgangsspannung ist VS = 4 V
• - Die Spannung an dem Stift ist $$\text{Vpin}=4\text{V}-3\text{V}=1\text{V}\text{.}$$
  
• - Verlustleistung an der in der IC: P = 1 W.

Well, taking into account the same voltage drop and the same current, but with lower supply voltage VS:

• - Output voltage is VS = 4V
• - The tension on the pen is $$\text{CPIn}=4\text{V}-3\text{V}=1\text{V}\text{,}$$
  
• - Power loss at the in the IC: P = 1 W.

Thus, the present invention provides a VS correction that is advantageous for thermal management and energy savings.

In embodiments of the present invention, the method may be applied at start-up of the system. For example, the calibration may become active immediately after the system is "powered up". In other embodiments, alternatively or additionally, it may be activated in a diagnostic mode, during maintenance in the workshop, and so on. If in this case a stored signal in the MCU 10 may be present, indicating that the calibration has been performed ("ready-flag configuration"), the signal may possibly be reset by the processor of the MCU. This recalibration instruction may possibly be received through the primary network connected to the MCU.

The initialization of a calibration step may possibly be initiated by the higher-level system when the lighting system z. B. the 1st time in use or z. B. the first time is turned on or if there is a workshop mode (workshop maintenance), for example. The higher tier system may be the MCU 10 trigger and the MCU 10 can the control units 20 . 120 to start a calibration.

If the primary network and the secondary network are the same, initialization may be possible in parallel from the higher-level system to the MCU 10 and the control units 20 . 120 be sent.

The initialization may possibly be from the MCU 10 can also be started locally if either from the MCU during a diagnostic cycle 10 or from the control units 20 . 120 a malfunction of the VS supply is detected, for. For example, the voltage on a given stylus is diagnosed as too low.

LIST OF REFERENCE NUMBERS

MCU 10 Storage 11 MCU microcontroller 12 Primary communication interface 13 Voltage measuring unit 14 Secondary communication interface of the MCU 15 DC converter 16 Secondary network cables 17 Primary network cables 18 control unit 20 PWM drive unit 21 switching element 22 Controllable power source 23 Voltage measuring unit 24 microcontroller 25 LEDs 26 LED cluster 27, 31 Communication interface of the controller 28 LED cluster 29, 30 CAN-High 101 CAN low 102 Knot (pin) 103, 104 MCU processing unit 112 Communication Interface 113 DC converter 116 control unit 120 LED string driver 123 reading device 124 processing unit 125 General interface of the controller 128 VS setting 301, 313, 314 VS deployment for strands 302 Measurement Vpin 303 Comparison with Vr 304 signal generation 305 VS-rectification 306 VS-storage 307, 317 Message LOW signal 308 Message HIGH signal 309 Election highest VS 310 Provision signal "no correction" 311 Generation calibration finished signal 312 Minor VS increase 315 Calibration done for a cluster 316

Claims (16)

A method of calibrating a supply voltage (VS) for lighting systems, comprising a plurality of LED strings (27, 31) of light emitting diodes (LEDs) (26), the method comprising: Setting (301, 313, 314) the supply voltage (VS) to a first voltage value, - providing (302) the first voltage value for the plurality of LED strings (27, 31) and for control units (20, 120) connected to clusters (29, 30) of LED strings (27, 31), wherein each cluster (29, 30) comprises at least one LED string (27, 31), Measuring (303) a voltage (Vpin) in a pin connection between each control unit (20, 120) and their respective connected LED strings (27, 31), and comparing (304) the measured voltage (Vpin) with a preset voltage ( Vr) for the respective strand, and - When the measured voltage (Vpin) is higher than a predefined error voltage above the preset voltage (Vr), or lower than the preset voltage (Vr), generating (305) a message signal in the corresponding control unit to a master control unit (10 ) to report that the supply voltage (VS) is high, or low, based on the notification signal, correcting (306) the first voltage value for a corrected supply voltage, and - storing (307, 317) at least the setting for obtaining the corrected supply voltage for which a minimum supply voltage (VS) is obtained, the minimum supply voltage (VS) being the smallest supply voltage (VS) for which the measured voltage (Vpin) is higher as the preset voltage (Vr) for all strands of a cluster (29, 30). Method according to Claim 1 further comprising providing (312) a signal indicating that the calibration is complete when a minimum supply voltage (VS) is stored for each cluster (29, 30) or if all of the control units (20, 120) detect a measured voltage (Vpin) higher than the preset voltage (Vr) for each leg of each cluster, and less than the predefined error voltage from the preset voltage (Vr). for at least one strand (27, 31) deviates. Method according to one of the preceding claims, further comprising performing the method at predetermined time intervals. The method of any preceding claim, wherein adjusting (301, 313, 314) the supply voltage (VS) to a first voltage value further comprises (313) adjusting the supply voltage to a first voltage value such that the measured voltage is lower than the required voltage Vr for each leg of a cluster, and wherein generating (305) a signaling signal further comprises generating (305) a signaling signal in the corresponding control unit of that cluster after recognizing that the measured voltage is lower than the required voltage (Vr) for at least one Strand of the cluster to notify a master controller (10) that the supply voltage (VS) is low, - Based on the message signal, correcting (306) of the first voltage value to a corrected supply voltage by means of the master control unit (10), and - storing (307, 317) the setting for obtaining the corrected supply voltage for which the measured voltage (Vpin) in each of the at least one string of this cluster is higher than the required voltage (Vr). Method according to one of Claims 1 to 3 wherein adjusting (301, 313, 314) the supply voltage (VS) to a first voltage value further comprising adjusting (314) the supply voltage to a first voltage value such that the measured voltage is higher than the required voltage Vr for each leg of a cluster; and wherein generating (305) a notification signal further comprises generating (305) a notification signal in the corresponding controller of that cluster after detecting that the sensed voltage is lower than the required voltage (Vr) for at least one leg of the cluster To inform the master control unit (10) that the supply voltage (VS) is high, - based on the notification signal, correcting (306) the first voltage value for a corrected supply voltage by means of the master control unit (10), and - after recognizing that the measured voltage (Vpin) is lower than the required voltage, increasing (315) the supply voltage (VS) until the gem Essence (Vpin) is higher than the required voltage (Vr), and - storing (307, 317) the setting for obtaining the corrected supply voltage for which the measured voltage (Vpin) in each of the at least one string of this cluster is higher than the required voltage (Vr). A method according to any one of the preceding claims, wherein the preset voltage (Vr) per cluster and / or strand (29, 30 and / or 27, 31) can be defined and / or varies in accordance with the lighting configuration of clusters and / or the application can be. The method of any one of the preceding claims, wherein the predefined error voltage can be varied in accordance with the illumination configuration of clusters and / or the application. Method according to one of the preceding claims, wherein the preset voltage (Vr) and / or the predefined error voltage can be programmed. The method of any one of the preceding claims, further comprising storing (307) the adjustment of the transducer to obtain the highest corrected supply voltage value required by all clusters, and further comprising adjusting the first supply voltage (VS) to the highest adjusted supply voltage value after further turning on for driving the LEDs of the lighting systems. Method according to one of Claims 1 to 8th , further comprising storing (317) each of the settings of the voltage converter to provide corrected supply voltage values needed by each cluster, and further comprising adjusting the supply voltage (VS) in accordance with the highest corrected supply voltage value required by all the clusters after one further turning on these clusters to reach the preset voltage (Vr) for powering at least each LED string of each of the clusters. A system for powering a plurality of clusters (29, 30) comprising at least one LED string (27, 31), the system comprising a master controller (10) including a voltage converter (16, 116) for providing an output supply voltage (VS) and at least one interface (13, 15, 113) for communicating with a plurality of control units (20, 120), the system further comprising at least one control unit (20, 120) for powering at least each LED cluster (29 , 30), each control unit (20, 120) comprising: - at least one LED drive unit (20, 21, 23) per LED string (27, 31) in the cluster (29), - a voltage reading device (24, 124) for reading the voltage (Vpin) at a node between the control unit (20, 120) and each LED string (27, 31), - a voltage comparator for comparing the measured voltage (Vpin) with a preset voltage (Vr) for this strand, - a signal generator for Erzeu a first signal, if the measured voltage (Vpin) exceeds a predefined error voltage above the preset voltage (Vr), or a second signal, if the measured voltage (Vpin) does not reach the preset voltage (Vr), transmission means (28, 128) for transmitting at least a first or second generated signal to the master control unit (10), the master control unit (10) further comprising means for adjusting the output supply voltage (VS) in accordance with the signals present in each of the control units (20, 120) are generated. System after Claim 11 wherein each control unit (20, 120) is integrated in a single integrated circuit. System according to one of Claims 11 or 12 wherein the master control unit (10) further comprises a configuration memory (11) for storing a plurality of settings of at least the voltage converter for obtaining corrected supply voltages (VS) and a cluster lighting configuration for which the value has been obtained. System according to one of Claims 11 to 13 wherein a secondary LIN network is provided between the control units (20, 120) and the master control unit (10), separate from a primary network for connecting the master control unit (10) to a higher level system. System according to one of Claims 11 to 13 wherein a CAN network is provided between the control units (20, 120) and the master control unit (10) to provide a direct connection to a higher level system. System according to one of Claims 11 to 15 wherein the control unit (20, 120) further comprises a processing unit (25, 125) for controlling the LED drive units (20, 21, 23), obtaining the measured voltages (Vpin) from the voltage reading device (24, 124), and comparing of these with the preset voltages (Vr) and for generating signaling signals.

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