DE102017116647B4 - Calibration of the supply voltage for lighting systems - Google Patents

Abstract

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:- adjusting (301, 313, 314) the supply voltage ( VS) to a first voltage value, - providing (302) the first voltage value for the plurality of LED strands (27, 31) and for control units (20, 120) which are connected to clusters (29, 30) of LED strands (27 , 31), each cluster (29, 30) comprising 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 string, and- if the measured voltage (Vpin) is higher than a predefined error voltage across the preset voltage (Vr), or lower than d the preset voltage (Vr), generating (305) a notification signal in the corresponding control unit to notify a master control unit (10) that the supply voltage (VS) is high or low, respectively, - based on the notification signal, correcting (306 ) the first voltage value to a corrected supply voltage by means of the master control unit (10), 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 is the smallest supply voltage (VS) for which the measured voltage (Vpin) in each of the at least one string of the cluster is higher than the preset voltage (Vr) for all strings of a cluster (29, 30), the setting (301, 313 , 314) the supply voltage (VS) to a first voltage value further comprises setting (313) the supply voltage to a first voltage value, sod that the measured voltage is lower than the preset voltage (Vr) for each strand of a cluster, and wherein generating (305) a notification signal further comprises generating (305) a notification signal in the corresponding control unit of that cluster after detecting that the measured voltage is lower than the preset voltage (Vr) for at least one string of the cluster to notify a master controller (10) that the supply voltage (VS) is low; orwherein setting (301, 313, 314) the supply voltage (VS) to a first voltage value further comprises setting (314) the supply voltage to a first voltage value such that the measured voltage is higher than the preset voltage (Vr) for each string of a cluster, and wherein generating (305) a notification signal further comprises generating (305) a notification signal in the corresponding control unit of that cluster after detecting that the measured voltage is higher than the preset voltage (Vr) for at least one string of the cluster to report to a master controller (10) that the supply voltage (VS) is high and after detecting that the measured voltage (Vpin) is lower than the preset voltage, increasing (315) the supply voltage (VS) until the measured voltage (Vpin) is higher than the preset voltage (Vr).

Description

field of invention

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

General state of the art

A common requirement for lighting systems, for example for signalling, is the stability of the lighting. This requirement is especially valid for LED lighting systems, which are currently included in numerous applications due to their low energy consumption. They are often found in vehicle lighting and signaling systems.

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, which include LEDs, usually have the problem that their intensity decreases due to degradation, e.g. B. due to thermal degradation changes. Furthermore, the luminosity of such an LED strand depends on the current. In order to ensure a specified luminosity for such an LED string, a specified current is required. The current can be controlled to ensure a given luminosity. Aging effects and thermal degradation can possibly be corrected. During current regulation, the voltage across the LED string may vary. In order to ensure current regulation, for example by a current source or switching element, a minimum voltage across this current source or switching element is necessary. In addition, the voltage across the LED string should not drop below a minimum level in order to ensure a specified luminosity (brightness). If the voltage across the power source or switching element is too high, there will be large power dissipation across the power source or switching element, possibly causing damage, reducing lifespan due to overheating, degradation effects, etc. These problems, individually or in combination, can create dangerous situations. It is therefore of interest to have a power supply for the LED string and its drive elements, such as e.g. a current source or switching element that is high enough for current regulation but low enough for optimal power dissipation.

In the particular case of automotive applications, there are several different types of lighting systems. For example, these may include front lighting or lighting systems (headlights, auxiliary lamps such as fog lights), signaling and visibility systems (daytime running lights, backup 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 the same time. For example, in automotive applications, turn signals are used only when needed, regardless of the use of e.g. B. headlights. 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 typically not coordinated, vehicles typically include a single power source for all of their electrical devices, including lighting systems (usually a battery). In order to avoid affecting the lighting conditions of one system in use when a second system is activated, individual control of each system is usually provided. In this way, systems can have stable illumination 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. in the rear lights, the energy management system would have to be tailor-made for each LED model and/or architecture, which depends on the vehicle type and even the brand. It would also have to have a final calibration, depending on the model of the rear lamp, 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 logistical effort to cope with the differently configured master control units. Alternatively, the calibration can be done on the vehicle manufacturer's assembly line, which also increases cost and manufacturing time. However, long-term degradation cannot be accounted for in these systems, so there is room for improvement.

US 2010/0 327 772 A1 discloses a control device and an LED light emitting device using the same, and a technology for providing a high contrast ratio for the LED light emitting device and enabling the LED light emitting device to perform stable operation. The LED lighting device includes a DC/DC converter Ref Limit voltage generator that generates a DC/DC converter reference voltage such that a minimum level of a channel voltage with a maximum LED voltage drop matches a predetermined minimum reference voltage by detecting a plurality of channel voltages representing LED voltage drops of each of a plurality of LEDs correspond to channels, and an output voltage controller that controls an output voltage of the DC/DC converter using a distribution voltage that corresponds to an output voltage and the DC/DC converter reference voltage.

US 2016/0 181 911 A1 discloses a load regulation device for controlling the amount of power supplied to an electrical load capable of calibrating the magnitude of an output voltage of the load regulation device to control the magnitude of a load voltage across the electrical load to a predetermined level. The load regulation device may receive the feedback from a calibration device adapted to be coupled to load wiring proximate the electrical load. The feedback may indicate when the magnitude of the load voltage across the electrical load has reached a predetermined level. The load regulation device may gradually adjust the magnitude of the output voltage, receive the feedback from the calibration device, and then use the feedback to determine the magnitude of the output voltage that corresponds to when the magnitude of the load voltage across the electrical load reaches the predetermined level.

US 2016/0 381 748 A1 discloses an error signal generation unit configured such that (i) in a calibration period, the error signal generation unit is placed in a first state in which it amplifies an error signal by amplifying a difference between a predetermined first reference voltage and the lowest one among a plurality of first detection voltages, and such that (ii) after the calibration period the error signal generation unit is placed in a second state in which it generates the error signal by amplifying a difference between a second detection voltage and a second reference voltage. A reference voltage setting unit holds as the second reference voltage the largest value of the second detection voltage detected in the calibration period.

Summary 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 that they provide a calibration method for lighting systems with great flexibility and simplicity, and while 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 mittels Master-Steuereinheit, und
• - Speichern von Einstellungen zum Erhalten der berichtigten Versorgungsspannung, für die eine Mindestversorgungsspannung die kleinste Versorgungsspannung ist, für die gemessene Spannung in jedem Strang des Clusters höher ist als die voreingestellte Spannung für alle Stränge dieses Clusters.

According to claim 1, a method for calibrating a supply voltage for lighting systems is defined, comprising a plurality of LED strings of light-emitting diodes (LEDs), described, the method comprising:

• - setting the supply voltage to a first voltage value that all LEDs in the plurality of LED strings are expected to operate at,
• - providing the first voltage value for the plurality of LED strings and for control units that are 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 its 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 is lower than the preset voltage, a notification signal can be generated in the corresponding control unit to report to a master or main control unit (MCU). that the supply voltage is high or low,
• - based on the notification signal, correcting the first voltage value to a corrected supply voltage by means of the master control unit, and
• - storing settings for obtaining the corrected supply voltage for which a minimum supply voltage is the smallest supply voltage for which measured voltage in each string of the cluster is higher than the preset voltage for all strings of this cluster.

The method according to claim 1 is characterized in that setting the supply voltage to a first voltage value further comprises setting the supply voltage to a first voltage value such that the measured voltage is lower than the preset voltage for each string of a cluster, and wherein generating a notification signal further comprises generating a notification signal in the corresponding control unit of that cluster after detecting that the measured voltage is lower than the preset voltage for at least one string of the cluster, to report to a master controller that the supply voltage is low; or
wherein setting the supply voltage to a first voltage value further comprises setting the supply voltage to a first voltage value such that the measured voltage is higher than the required preset voltage for each strand of a cluster, and wherein generating a notification signal further comprises generating a notification signal in the corresponding control unit of that cluster, after detecting that the measured voltage is higher than the required preset voltage for at least one string of the cluster, to report to a master control unit (10) that the supply voltage is high, and after detection that the measured voltage is lower than the required preset voltage, increasing the supply voltage until the measured voltage is higher than the required preset voltage.

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

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

It is an advantage of embodiments of the present invention that an operator can have assurance that the calibration was successful.

Some embodiments of the present invention may further include 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 fluctuations of the LED systems due to temperature changes, degradation, etc. can be compensated for on a regular basis.

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

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

It is an advantage of embodiments of the present invention that the preset voltage can be chosen according to the type of LED, the number of LEDs in a string and the lighting required, thus accounting for the granularity of the lighting system.

In some embodiments of the present invention, the predefined error voltage may be varied according to the lighting configuration of clusters and/or the application.

It is an advantage of embodiments of the present invention that the illumination obtained can be more robust to changes, unwanted spikes or disturbances in the supply voltage and/or the external supply (e.g. battery).

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

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

It is an advantage of embodiments of the present invention that power can be secured for all LED strings, reducing 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 values required by each cluster, and further adjusting the supply voltage in accordance with the highest corrected supply voltage value used by at least any of the active control units is imposed upon further switching on of these control units in order to reach the preset voltage for powering at least each LED string.

It is an advantage that the highest supply voltage can depend on the active clusters and it can change during use, providing an optimal 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 Versorgungsspannung in Übereinstimmung mit den Signalen umfasst, die in jeder der Steuereinheiten erzeugt werden.

According to the independent claim 9, a system for supplying energy to a large number of clusters, which comprise at least one LED strand, is defined. The system includes a master control unit (MCU), which includes a voltage converter for providing a supply voltage and at least one interface for communication with a plurality of control units, with at least one control unit serving to supply power to at least each LED cluster (hence one or more control units per clusters). Each control unit includes:

• - at least one LED drive unit per LED strand 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 to compare 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 sending at least any first or second generated signal to the MCU, the MCU further comprising means for correcting the supply voltage in accordance with the signals generated in each of the control units.

The method according to claim 9 is characterized in that the control unit further comprises a processing unit for controlling the LED driving units, receiving the measured voltages from the voltage reading device and comparing them with the preset voltages and generating notification signals.

It is an advantage of embodiments of the present invention that an MCU is provided for one or all LED strings that may be remote from the power source. It is a further advantage that fewer controllers than LED strings are required when LED strings are grouped, for example one controller per LED cluster or e.g. B. a controller for each taillight lighting system. Another benefit is that this implementation can be applied to a wide variety of vehicles and brands; e.g. B. the present invention can provide a general purpose lighting system.

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

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

In some embodiments of the present invention, the MCU further includes a configuration memory for storing a plurality of settings of the voltage converter to obtain corrected supply voltages and a cluster lighting configuration for which the value was obtained.

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

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 tier system.

It is an advantage of embodiments of the present invention that isolation is obtained between the primary network and the secondary network, thereby reducing interference, for example reducing 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 being connected into a single network, which improves problem diagnosis, for example.

In some embodiments of the present invention, the control unit further includes a processing unit for controlling the LED driver units, receiving the measured voltages from the voltage reading device and comparing them with the preset voltages, and generating notification signals.

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

Particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. Features from the dependent claims may be combined with features of the independent claims and with features of other dependent claims as appropriate, and not merely as explicitly set out in the claims.

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

character list

• 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 control unit and a plurality of control units,
• 2 a further embodiment of a system according to an aspect of the present invention, comprising a single network for communication between a higher level system, the master control unit and the plurality of control units,
• 3 a flowchart of a method according to embodiments of the present invention, including optional steps,
• 4 a flow chart of a calibration method according to embodiments of the present invention, which can be applied to individual clusters or to many clusters at the same time, with a first low supply voltage,
• 5 a flow chart of a calibration method according to embodiments of the present invention, which is applicable to single clusters or to many clusters at the same time, with a high supply voltage.

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

Any reference signs in the claims should not be construed as limiting the scope in any way. In the different drawings, the same reference numbers refer to the same or analogous elements.

Detailed Description of Illustrative Embodiments

The present invention will be described in terms of 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 non-limiting. In the drawings, the size of some elements may be exaggerated and not to scale for illustrative purposes. The dimensions and relative dimensions do not correspond to actual reductions in practicing the invention.

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

Furthermore, in the specification and claims, the terms top, bottom, and the like are used for descriptive purposes and not necessarily to describe relative positions. It will be understood that the terms so used are interchangeable under appropriate circumstances, and that the embodiments of the invention described herein are operable in orientations other than those described or illustrated herein.

It should be noted that the term "comprising" used in the claims should not be construed as limited to the means listed thereafter; it does not exclude other elements or steps. Accordingly, it is to be construed as specifying the presence of the specified feature, integer, step, or component as referred to, but not a priori specifying the presence or addition of one or more other feature, integer, step, or component, or group thereof excludes. Consequently, the scope of the expression "a device comprising means A and B" should not be limited to devices consisting solely of components A and B. It means with reference to the present invention that the only relevant components of the device are A and B.

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. Consequently, occurrences of the phrases "in the embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but they may be. In addition, the specific features, structures, or characteristics 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, in describing exemplary embodiments of the invention, it should be appreciated that, at times, various features of the invention are grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various aspects of the invention. However, this disclosure procedure should not be interpreted to reflect any intent that the claimed invention requires more features than are 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 that 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.

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

Numerous specific details are set forth in the description provided herein. However, it should be understood 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 in order not to obscure an understanding of this description.

In general, in lighting systems, one desires to have a stable illumination intensity. When multiple lighting systems, which may vary in style and design, are powered from a single power source, compensation is required to ensure that all systems receive a high enough voltage 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 driving 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 (e.g., a battery). For safety reasons, sufficient intensity should be provided in all lighting systems. In an extreme example, the headlights should not dim their illumination when the turn signals are used. The single power source must be able to sustain all electronic systems, including the different types of lighting systems, and provide a stable power supply to all of them. However, the electronic network should not be overly complex. Less complexity facilitates installation, problem diagnosis, parts replacement, resulting in lower system costs, etc.

LED-based lighting systems in vehicles are typically distributed across multiple LEDs, including multiple LEDs connected in series. LEDs have lower power consumption, but they tend to suffer from degradation over time (with age) and also from thermal degradation.

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

A particular lighting system according to 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 described that provides control and compensation for variations in 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 (e.g. a battery, for example a 12V or a 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 rectifying a voltage from a power source (e.g., battery) to a supply voltage VS for the lighting system. In this way, the MCU provides a common supply voltage for all LED strings via the converter.

Consequently, all LED strings are connected to just one common supply voltage, which is output by the MCU. Since the LED strings may differ in number and type of LEDs, the present invention provides an MCU for optimizing the supply voltage VS, which is adapted to correct its supply voltage in accordance with the power requirements of the LED clusters. For example, the MCU may include a regulator, such as a voltage regulator or calibrator. The regulation may alternatively or additionally be provided by controlling the converter using a microcontroller. The regulation can e.g. B. be done by any suitable, adjustable, linear voltage regulator. For example, a regulator may include an adjustable switched-mode 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 switched-mode power supply for regulating the car battery voltage level to a supply voltage level that is adapted to power an LED string(s) and their driving elements.

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

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

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

The present invention can provide control of powering of LEDs by providing at least one controller per cluster. The MCU can exchange information with the control units of the clusters. This can be done through electrical connections. For example, the MCU can be connected to one or more control units via a BUS interface (e.g. a LIN bus or CAN bus). This network can be seen as a secondary network, e.g. a network connecting a variety or all lighting systems e.g. B. controls in a vehicle (however, any data transmission could also be used).

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 "pin".

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 can 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 term can be extended to any type of connection.

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

Each control unit further includes one LED driver (including eg 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 can each be connected to a corresponding driver of the control unit. In this case, the control unit should include at least two or three drivers. If a control unit is a driver integrated circuit, the number of drivers may be limited. In such a case, if a cluster includes more LED strings than drivers in the available controller, the cluster could be connected to two or more controllers. For example, if the number of LED strings is very high, the cluster can be connected to a variety of control units, each LED string having a drive channel, e.g. B. a connection via the pin or pin, to a drive unit of a control unit of the plurality thereof. In turn, the control units of the same cluster can set values of the preset minimum voltage Vr for the same requirements of e.g. B. store brightness according to the function of this particular cluster.

The control units may further comprise a unit for comparing a measured voltage with the preset voltage Vr. For example, a comparator can imple be mentioned. For example, a processing unit can be included to process the signals from the voltage measurement unit. For example, the processing unit can be a microcontroller, a CPU, or any other suitable hardware unit. The processing unit may provide the MCU with a signal including information regarding the voltage on the pin or a voltage drop across the LED string, specifically whether it is higher or lower than a predetermined range of values. The control unit can share this information with the MCU via communication interfaces in a network.

Furthermore, the control unit can optionally include a diagnostic function, in a similar way 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 only during calibration). This can be made possible as before by including a voltage measurement 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 control units to access a voltage measurement unit in the Access MCU to measure the VS.

The control units can be provided in a separate integrated circuit, for example in monolithic circuits. The control units can also be arranged as a plurality of circuits with their multiple components implemented as separate circuits, e.g. B. an ADC, a communication transceiver (z. B. 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 can be part of the same type of lighting system or each cluster can be part of a different type of system. For example, a cluster that includes two LED strings can be part of the taillight lighting, while another cluster that includes a single LED string can 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 includes at least one cluster that includes at least one LED string. Because the controllers are associated with clusters, accurate drive and voltage reading and compensation for each string in a cluster can be obtained by using a single controller, thus reducing the complexity of the system. In some embodiments, a cluster may include a single string that includes one or more LEDs. In some embodiments, a cluster may include a string of four LEDs or three LEDs. In some embodiments, combinations of multiple clusters of different types, number of strings, and/or number of LEDs per string may be included. The system is able to power any of these cluster combinations forming lighting systems that may differ from each other and ensure correct powering and lighting of all systems.

In an exemplary embodiment of the present invention disclosed in 1 is shown, a lighting system for a car includes at least two clusters (two are in 1 illustrated), one of the clusters comprising a plurality of strands. MCU 10 may include a voltage converter, e.g. B. a DC / DC converter 16 for correcting the voltage of the power supply (z. B. vehicle battery supply) VBAT to a supply voltage VS for z. B. the rear light system of a vehicle. The supply voltage VS can be higher or lower than the car battery supply.

The lighting system may comprise different LED clusters 29, 30 and each LED cluster may comprise one or more LED strings 27, 31, each LED string having at least one LED, possibly a plurality of LEDs 26 connected in series , lock in. Although the present invention can be used on strings comprising a single LED, it is advantageous to have multiple LEDs in series as it ensures correct powering of all LEDs in the string, resulting in a system with much better lighting and visibility capabilities than one only LED is allowed.

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

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

While the supply voltage VS used to power the LED strings can be controlled and measured by the MCU 10, the voltage drop or current through the LED strings can be controlled by a control unit, e.g. a control unit 20 associated with each respective LED cluster 29, 30 can also be controlled and measured. The controller 20 in embodiments of the present invention can not only control the powering of the associated LED clusters (e.g., by controlling the current through each string), but can also measure powering-related parameters, such as the voltage at each pin , optionally also at the supply voltage VS, and it can also derive the voltage drop in each phase of the cluster from this. Referring to 1 comprises a control unit 20, e.g. B. a control IC of the rear light, an LED drive unit for driving the LED strings 27, 31 and z. B. to control their activation and their brightness. The LED driver may include, for example, a controllable current source 23, a switching element 22 (e.g., a transistor) controlled by a PWM driver, or a combination of both.

In the 1 illustrated control units 20 each include two LED drive units; however, this is not limitative of the present invention. in the in 1 In the illustrated implementation, both LED drive units of the control unit 20 connected to the cluster 29 comprising two LED strings are used. However, only one LED drive unit of the control unit connected to the cluster 30 comprising a single LED string is used. It can be seen that the same architecture can be used for a wide range of applications, configurations and vehicle models without having to build custom controllers. The control units 20 include a voltage measuring unit 24, e.g. an ADC, to read the voltage at the connection between the controller 20 and the LED string. In particular, each LED drive unit of the control unit can be connected to a strand of the associated cluster. In some embodiments of the present invention, a driver pin may be included in a cluster at the connection between the controller and the LED string. For example, a driver pin can connect a microchip containing the controller and the LED string. In embodiments of the present invention, there may be potentially different voltages Vpin on the driver pins for different LED strings. For example, an LED string 31 may be connected to pin DRV1 and hence to an LED driver. Another LED string 27 can possibly be connected to another pin DRV2 and consequently to another LED drive unit of the same cluster 29.

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

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

It should be noted that any or all parts of the control unit 20 can be contained in a single integrated circuit, such as a semiconductor chip, which further improves compactness.

The master controller 10 may include a secondary communication interface 15 for communicating with the communication interface 28 of each controller 20 of the system. Consequently, the MCU 10 and the control units 20 communicate with each other via this secondary network, e.g. B. via the lines 17 of the secondary network. This is advantageous in many vehicles that include a dedicated network architecture for some or all lighting systems, separate from the rest of the network architecture and reduces risks of interference with other systems in the vehicle, e.g. security systems, engine control and cruise control, distance and impact sensors, air conditioning, communication systems, etc. Advantageously, this secondary network does not need to be high-performing, so implementation costs can be reduced, e.g. B. by using a LIN. Implementing multiple controllers on a secondary network is usually cheaper than implementing them on the CAN with wiring through an entire vehicle and providing a single connection to the CAN via the MCU. In this case the MCU is a CAN-LIN gateway. However, other implementations are permitted. For example, a CAN can potentially be used for MCU and control units when the system is seen as a safety-critical system, as in 2 shown. In other embodiments, the MCU can be connected to a LIN for very low network costs. In such a case, the MCU is a slave with respect to a higher level network, but a master with respect to all control units. In this case the MCU is a LIN-LIN gateway.

The exchanged data may at least include data on whether the voltage drop measurement was performed and the result thereof (from the control unit 20 to the MCU 10), but it may also include other signals, for example signals to activate the calibration.

The voltage converter 16, z. B. the DC / DC converter, the MCU 10 provides an adjustable supply voltage VS ready. If a first group of clusters is used, a corrected supply voltage value VS can be obtained, which may differ from the corrected value if a second, different group of clusters is used. The plurality of corrected supply voltages VS obtained 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 included in the MCU 10.

The status of the system or systems may be communicated to a higher-level processing unit (e.g., the on-board control module (BCM) or similar controller of a vehicle), for example to receive commands for the central processing unit.

The higher level processing unit may also provide control over which of the lighting systems needs to be activated. The communication can be provided by a dedicated primary communication interface 13 included in the MCU 10 which connects to the primary network, e.g. B. via 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 included in a single, common network, as described above.

Such an embodiment is in 2 outlined, which shows a special vehicle architecture with a common network. A common network can easily be obtained with a CAN implementation of the primary and secondary networks. In this case only one communication interface 113 in the MCU 10 is required. Two communication paths, a CAN high 101 (CANH) line and a CAN low 102 (CANL) line, may be included along with a ground line. In this case a signal can be sent through the CAN to the MCU 10 to start a calibration. Communication between controllers 120 and the MCU 10 occurs through the CAN over common interfaces 128 in the controllers 120. Activation schemes using these lines are known to those skilled in the art.

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

The procedure, which is shown schematically in the flow chart of 3 1 includes the steps of setting 301 the supply voltage to a first voltage VS that all LEDs in the plurality of LED strings are expected to function with. This first voltage may be a calibration value, for example a calibration value determined during a previous calibration procedure obtained and stored in memory. In embodiments of the present invention, a voltage converter (e.g., the DC/DC converter 16, 116) adjusts the supply voltage VS from an external power source (e.g., a vehicle's battery) by converting the voltage to the 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 strings 27, 31 are grouped into clusters 29, 30, each cluster 29, 30 includes at least one LED string. The method can advantageously be used for a plurality 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, where at least one cluster includes a plurality of LED strings. Different clusters can, but do not have to, contain different numbers of LED strings. A high design and installation flexibility can be obtained by grouping several LED strings and connecting them to the same control unit 20, 120, while at the same time providing an adjustable common supply voltage VS for all LED strings of one or more clusters. Another benefit is the improvement in 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 powering of the LED string. For example, the method may include measuring a voltage Vpin at a node between each controller 20, 120 and its respective leg or legs. For example, the node can be the connection of an LED string opposite the connection to the MCU 10, or analogously, 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 string, between the supply voltage and the voltage at the node between each string and the control unit, can additionally be obtained, which may differ from cluster to cluster, or even between strings of the same cluster.

The obtained voltage Vpin at the node between a string and the controller is then compared 304 to a preset voltage Vr required for the particular string. The preset voltage may be the minimum analog voltage required to provide needed lighting information of a given LED string connected to the controller. The preset voltage Vr can advantageously be as low as possible to have 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 can be different for each cluster, chosen according to the application (e.g., lights for illumination have different requirements than lights for visibility, so the Vr in clusters of these systems are different becomes). A different Vr can also be assigned to each string, advantageously taking into account a different number of LEDs in each string for the same cluster. In some embodiments, the preset minimum voltage levels Vr may be programmable.

Measuring and comparing can be done in any suitable voltage measuring circuit, e.g. B. an ADC 24, 124, and processing unit of the control unit 20, 120 (e.g. in the microcontroller 25, 125). A signal may be generated 305 according to the result of the comparison. If the voltage measured at the node between the LED string and the controller is lower than a predefined error voltage, lower than the preset voltage Vr, the MCU 10 is reported 308 that the supply voltage VS is too low. The preset voltage Vr in typical vehicle applications can for example be between 0.5 V and 3.0 V, e.g. B. be 0.5V or 1V or 2V or 3V. For example, the predefined error voltage may be between 5 and 20% of Vr. In general, the error voltage must not be too low to provide a robust drive. In some embodiments of the invention, a "LOW" notification signal can be generated in the corresponding processing unit, for example in the microcontroller, to notify the MCU 10 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 can be through any suitable communication network, such as a wireless network (although less preferred as costs are higher). Preferably, the MCU 10 exchanges (receives and/or transmits) data with the controllers via a wired communications network. The tax one Units receive information for driving the lighting system and send diagnostic information back to the master unit 10. For example, the information may include the current through the LED string, the voltage drop across an LED string, the voltage at the connection point of the LED string to the Drive elements that affect the supply voltage VS etc. In some embodiments, MCU 10 may send the information to a primary network in a gateway role. In some embodiments, all control units 20, 120 and MCU 10 are in the same network hierarchy and are controlled by the primary network. In other embodiments, any or all of the control units 20, 120 are connected to the MCU 10 via a secondary network and communication with the primary network is through the MCU 10. Any other suitable means of communication may be used, resulting in a highly flexible procedure.

Additionally, the method may include generating a notification signal 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, reports 309 that the supply voltage is too high, and it 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 can be different for the strands of a cluster, but usually it is the same. The predefined error voltage above the preset voltage Vr may be different from the predefined error voltage below the preset voltage Vr. Furthermore, a plurality of the predefined error voltages can be stored and used according to 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 can also be programmable.

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

If the MCU 10 receives a "LOW" signal, then the MCU 10 increases the supply voltage VS (e.g. by increasing the voltage conversion, for example by changing the configuration or setting of a DC/DC converter via a microcontroller) by ensure correct 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 controller reaches or exceeds the preset voltage Vr. When this condition is reached for all LED strings of all control units of a given cluster, the calibration for that given cluster is finished and a particular VS setting for that given cluster is saved by the MCU 10, at least temporarily saved. 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 the MCU 10 decreases 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 power dissipation and heating in the driving elements of the control unit are reduced and ultimately the risks of damaging or reducing the service life of the driving elements of the control units are reduced. Calibration for a given cluster is complete when the first controller reaches this state for the first connected thread. The MCU 10 may then only be able to increase the VS voltage in a small step such that the Vpin is then higher than the Vr again. 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. This ensures that the minimum voltage required for all LED strands of a given cluster.

In embodiments of the present invention, the MCU 10 uses the setting that results in the highest VS, the value from the derived individual VS settings for each cluster, and stores 307 that setting for further use. The MCU 10 can be programmed to select 310 the highest of the different required supply voltages as the corrected supply voltage VS. Consequently, no LED string is starved of power and correct lighting can be obtained.

In other embodiments, the converter setting that results in the highest VS and the configuration of clusters that resulted in that highest VS are saved 307. When the same clusters are activated, the MCU uses the highest VS saved for that configuration is. In other embodiments of the present invention, the MCU 10 uses all derived individual VS settings per cluster and stores these settings 317 for further use. Since the MCU 10 may have the bus interface in accordance with 1 controls all clusters of the lighting system, the MCU 10 always has the information about which cluster is in operation. The individual VS setting for a given cluster may be chosen to provide VS to the lighting system. If multiple clusters are operating at the same time, it may be possible to choose the cluster's VS setting that results in the highest VS for all lighting systems (e.g. all clusters).

The saved setting includes the setting or configuration of the voltage converter to convert the voltage of a main source to the corrected supply voltage required and may also include information regarding the number of strings driven, the lighting intensity, the VS value required to meet the Vr to achieve for all strands in that cluster. Saving a setting may include saving data values. For example, different data values for the supply voltage VS (depending on the clusters) are collected during the calibration. These data values can be stored in a memory. The data value for the supply voltage VS, data for adjusting the converter and providing such data values of the supply voltage VS and the clusters corresponding 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 from 00 hex to FF hex. Each stored data value can possibly correspond to an analog output value of a different supply voltage VS. The MCU can select a data value from memory (depending on which cluster is used) and include that value in the control register for the converter. If more clusters are used in another lighting system power supply, the MCU can select the setting that provides the highest value of all enabled clusters.

Optionally, a third type of notification signal can be provided 311 if the signal is within the prescribed parameters (e.g. 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 is defined per function (e.g., to obtain the VS needed for all LED strings of a single cluster where all Vr are the same for all strings), the method include 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 function, but resulting in lower power dissipation. However, if many Vr are used, only “LOW” signals can be used. In a practical example, an output voltage for fog lamp systems VS(fog) can differ from the output voltage for rear lamps VS(rear) in normal operating mode. Both values can be derived during calibration and stored in the memory 11 of the MCU, for example. When fog lights and tail lights are on, the converter setting that provides the highest VS is chosen by the MCU (either fog lights or tail lights) because if the lowest VS were chosen then a lighting system could not function in accordance with the specified luminosity . Consequently, the MCU does not adjust the VS in accordance with a request for lower VS ("LOW" signal) when the Vpin exceeds the Vr, in this particular case of clusters with different Vr.

In another embodiment, possibly several predefined error voltages can be given in order to ensure a given hysteresis between increase/decrease of the supply voltage VS in order to suffice to have enough leeway against disturbances in the supply voltage VS.

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

In some embodiments of the present invention, a signal may be generated 312 by the MCU 10 that may be sent to an output through the primary network indicating that the calibration is complete (e.g., setting a "configuration complete flag"). .

In one embodiment of the present invention, this flag may also be stored in one of the memories described so that a next time the system is powered up, a calibration step may not be 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 preset voltage Vr in any of its strings) or very high (high enough to ensure that all strands of all clusters have a voltage at least higher than Vr). All Vpin voltages are measured on all controllers and all clusters. There can be two possibilities during the calibration, depending on the first supply voltage VS used.

a) 4 illustrates a first possibility, where a low supply voltage VS is set 313: the condition Vpin > Vr is not fulfilled for any Vpin. The microcontrollers send 308 a LOW signal and the MCU increases 306 the supply voltage. The condition Vpin > Vr may possibly be satisfied for a first Vpin in a given cluster. The rest of the strings of this cluster (and other clusters) require a higher supply voltage VS, which is why the supply voltage VS is increased. If the condition Vpin > Vr is satisfied for all Vpins (all threads) of a first particular cluster, the setting S resulting in this supply voltage VS is saved 307 for this particular cluster and the calibration of this cluster is finished 316. For example the setting can be configured as a data field, e.g. "S (Cluster 1)" can be saved. In the case of a single cluster, the calibration would stop completely, but in the case of multiple clusters, the rest of the clusters still do not necessarily agree with the state in each of its threads. Therefore, LOW signals are generated and the supply voltage VS is further increased. When the Vpin > Vr state 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 ready and Vpin > Vr is true for all Vpins of all clusters, the calibration ends 312.

This process can occur simultaneously for all clusters, or sequentially cluster by cluster, or simultaneously for a subset of the clusters and then for at least one other subset of the clusters. If the process does not happen simultaneously 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 required by each cluster, such that the clusters are calibrated in a sequence of increasing minimum Vr. Alternatively, if the MCU recognizes that a cluster has been calibrated and its calibration settings are saved, any further signal from microcontrollers of that cluster can be ignored.

b) 5 shows a second possibility, with a high supply voltage VS being set 314: the condition Vpin>Vs is fulfilled for all Vpins. The microcontrollers send a HIGH signal and the MCU decreases the supply voltage VS until the condition Vpin < Vr is reached for a first Vpin for a first cluster. The value of the supply voltage VS is again increased 315 by a small margin (e.g. by increasing it by a predefined error voltage) to ensure that the condition Vpin > Vr is present again. Alternatively, the MCU can decrease the supply voltage VS until Vpin is strictly above Vr, within a predetermined error margin. In any case, the new Vpin value is closer to Vr than the first high value of the supply voltage VS, thus reducing the power dissipation. The settings are saved or recorded as before, e.g. For example, "S (Cluster 1)". The calibration for this cluster would be finished 316. In the case of a single cluster the calibration of the entire system would be finished 312, but in the case of multiple clusters the supply voltage VS is further reduced until the first Vpin for another cluster satisfies the condition 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. recorded as S (Cluster 2). The process is further repeated for the remaining clusters. For each cluster calibration, the already calibrated cluster outputs LOW signals, which are ignored by the MCU since the setting corresponding to the calibrated clusters is already stored.

In this case, the setting of the minimum supply voltage VS for each cluster is saved 317 such that the condition Vpin > Vr is reached for all Vpins of all controllers for a given cluster.

Both calibrations can be combined in some cases. For example, if a cluster-by-cluster calibration is performed, some clusters can be calibrated starting with a higher than required supply voltage VS to get Vr in all their strings, and others can be calibrated starting with a lower than required supply voltage VS to get Vr in all its strands. For example, for a cluster with many strings, starting with a high supply voltage VS can finish the calibration quickly, 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 (e.g. two), starting with a very low supply voltage VS can result in a supply voltage VS that gives a very close Vr to Vpin, thus reducing power dissipation. In some embodiments, only a single supply voltage VS is stored, the minimum value for which all strings of each cluster will function with minimal power dissipation and to obtain a Vpin slightly higher than the preset voltage.

• 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.
• 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 (e.g. in a subsequent switching on of one or more lighting systems), the MCU will either:

• i) select the setting that results in the highest supply voltage VS of all stored settings. This can be applied to those cases where all clusters are used together.
• 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 currently being used and the chosen 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 can be applied with embodiments of the first aspect of the present invention, for example in 2 embodiment shown. A converter 116 in the MCU 10 adjusts the supply voltage VS. This can be done by converting the voltage from an external source or battery, outputting a first supply voltage VS to the clusters 29,30. The control units 120 receive the supply voltage VS which in turn becomes active, as does each LED string 27, 31 in the clusters 29, 30. The control units 120 may include elements for controlling the powering of the LED strings of their associated clusters. This energy supply can, for example, by current control, z. with an LED string driver 123, in accordance with the required brightness. The voltage Vpin is measured at each node 103, 104 between each LED string 27, 31 of each cluster 29, 30 and its corresponding controller 120 and compared to a preset preset voltage Vr (stored in a memory unit, controller 120 or in the MCU 10 can be stored). If the result is lower than Vr or higher than an error margin above the preset (required) voltage Vr, a signal is generated that includes information as to whether the voltage Vpin at node 103, 104 is too high or too low. Each control unit 120 performs this action. Reading, voltage comparison and signal generation can be done with one or more reading devices and optionally integrated comparators in any combination. For example, the reading can be done with a reader 124 and the comparison and signal generation with a processing unit 125, or by any other suitable means. However, this configuration is not limitative, and the reading device and the comparator can be integrated in the same unit.

If at least one notification signal is generated, the signal is reported to the MCU 10, for example between a general communication interface 128 in the controller and the communication interface 113 in the MCU 10 via the CAN network. After receiving the notification, the MCU 10 regulates the first supply voltage VS to a corrected supply voltage VS. If multiple notification signals are received, the MCU 10 can be programmed to select a supply voltage VS that will ensure all LED strings are powered, thus ensuring that the optimal voltage drop is provided for at least one LED string, and at the same time providing a higher voltage drop for the rest of the LED strings.

The MCU 10 can then store the value of the corrected supply voltage VS and the configuration of the lighting system (e.g. settings of the converter that achieve such a voltage value, which systems are powered and their required brightness) in a memory 11 ("configuration memory"). to save. 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 (e.g. via a voltage measuring unit 14) can be controlled by a single processing unit 112 within the MCU 10. The next time a given configuration is activated, MCU 10 may provide the previously stored corrected supply voltage VS obtained for that configuration as the first supply voltage VS.

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 15, 13 can alternatively be used in the MCU 10, one for communicating with the control units through a secondary network, the other for communicating with a central unit through a primary network. Furthermore, 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 machines, household appliances, etc.

The present invention can be used with multiple strings having different numbers and types of LEDs 26 . The granularity of the lighting system (e.g. how many LEDs per string, 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 (e.g. the minimum voltage required to operate a given LED string as defined above) can be defined per cluster or even per string, taking into account the granularity of the system. As seen previously, several preset voltages Vr can be used depending on the particular light sources (LEDs, strings, clusters, groups thereof) that are turned on. These values may be stored in a memory of the control units 120, for example a memory included in the processing unit 125 of the control units, or in the memory 11 of the MCU 10 or 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 saved, e.g. B. in the configuration memory 11 of 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 sent to the MCU 10 over the primary network. For example, calibration values for the supply voltage VS can be externally programmed for a number of lighting system configurations. 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 switching on the lighting systems according to the programmed configuration. The supply voltage VS can be obtained, for example, by calculation, since the given light source and its configuration are known. In other embodiments, the first supply voltage VS can 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 switched on at the same time, the calibration value that matches the highest value of the power supply VS for the light sources is used. This ensures an application-dependent, improved, preferably optimal energy management, so that the supply voltage is on the one hand as low as possible, but still high enough that an individual current or voltage regulation of each LED string is possible.

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

As an example of the importance of power management, the following calculation considers a single LED, with a current of ILED = 1A

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

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

Well, considering the same voltage drop and current, but with lower supply voltage VS:

• - Output voltage is VS = 4V
• - The voltage on the pin is $$\text{Vpin}=4\text{V}-3\text{V}=1\text{V}.$$
  
• - Power loss at the IC: P = 1 W.

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

In embodiments of the present invention, the method may be applied at system startup. For example, the calibration can become active immediately after the system is "switched on". In other embodiments, it may alternatively or additionally be activated in a diagnostic mode, during workshop maintenance, and so on. In this case, if there is a stored signal in the MCU 10 indicating that the calibration has been performed ("configuration done flag"), the signal may be reset by the MCU's processor. This recalibration instruction may be received over the primary network connected to the MCU.

The initialization of a calibration step can possibly be initiated by the higher level system if the lighting system is e.g. B. is the 1st time in use or z. B. is switched on for the 1st time or if there is, for example, a workshop mode (workshop maintenance). The higher level system can trigger the MCU 10 and the MCU 10 can trigger the controllers 20, 120 to start a calibration.

If the primary network and the secondary network are identical, the initialization can possibly be sent in parallel from the higher level system to the MCU 10 and the control units 20, 120.

The initialization can possibly also be started locally by the MCU 10 if a fault in the VS supply is detected during a diagnostic cycle either by the MCU 10 or by the control units 20, 120, e.g. B. the voltage on a given pin is diagnosed as too low.

Reference List

10

MCU

11

Storage

12

MCU microcontroller

13

Primary communication interface

14

voltage measurement unit

15

Secondary communication interface of the MCU

16

voltage converter

17

Secondary network lines

18

Primary network lines

20

control unit

21

PWM drive unit

22

switching element

23

Controllable power source

24

voltage measurement unit

25

microcontroller

26

LEDs

27, 31

LED strand

28

Communication interface of the controller

29, 30

LED cluster

101

CAN high

102

CAN low

103, 104

knot (pin)

112

MCU processing unit

113

communication interface

116

voltage converter

120

control unit

123

LED string driver

124

reading device

125

processing unit

128

General interface of the controller

301, 313, 314

VS setting

302

VS deployment for strands

303

Measurement Vpin

304

Comparison with vr

305

signal generation

306

VS correction

307, 317

VS storage

308

Message LOW signal

309

Message HIGH signal

310

Choice of highest VS

311

Provision of signal "no correction"

312

Generation of calibration complete signal

315

Slight VS increase

316

Calibration complete for a cluster

Claims (13)

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 strand (27, 31), - measuring (303) a voltage (Vpin) in a pin connection between each control unit (20, 120) and its respective connected LED strings (27, 31), and comparing (304) the measured voltage (Vpin) with a preset voltage ( Vr) for the respective strand, and - if the measured voltage (Vpin) is higher than a predefined error voltage above the preset voltage (Vr), respectively lower than the preset voltage (Vr), generating (305) a notification signal in the corresponding control unit to inform 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 to a corrected supply voltage by means of the master control unit (10), 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) in each of the at least one string of the cluster is higher than the preset voltage (Vr) for all strings of a cluster (29, 30), wherein setting (301, 313, 314) the supply voltage (VS) to a first voltage value further comprises setting ( 313) adjusting the supply voltage to a first voltage value such that the measured voltage is lower than the preset voltage (Vr) for each string of a cluster, and wherein generating (305) a notification signal further comprises generating (305) a notification signal in the corresponding Control unit of this cluster includes after detecting that the measured voltage is lower than the preset voltage (Vr) f for at least one strand of the cluster to report to a master control unit (10) that the supply voltage (VS) is low; or wherein setting (301, 313, 314) the supply voltage (VS) to a first voltage value further comprises setting (314) the supply voltage to a first voltage value such that the measured voltage is higher than the preset voltage (Vr) for each string of a cluster, and wherein generating (305) a notification signal further comprises generating (305) a notification signal in the corresponding control unit of that cluster after detecting that the measured voltage is higher than the preset voltage (Vr) for at least one string of the cluster to report to a master controller (10) that the supply voltage (VS) is high and after detecting that the measured voltage (Vpin) is lower than the preset voltage, increasing (315) the supply voltage (VS) until the measured voltage (Vpin) is higher than the preset voltage (Vr). procedure after 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 when all control units (20, 120) have a measured voltage (Vpin ) that is higher than the preset voltage (Vr) for each strand of each cluster and that deviates from the preset voltage (Vr) for at least one strand (27, 31) by less than the predefined error voltage. Method according to one of the preceding claims, further comprising performing the method at predetermined time intervals. Method according to any of the preceding claims, wherein the preset voltage (Vr) per cluster and/or string (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. A method according to any one of the preceding claims, wherein the predefined error voltage can be varied in accordance with the lighting configuration of clusters and/or the application. A method according to any one of the preceding claims, wherein the preset voltage (Vr) and/or the predefined error voltage can be programmed. A method according to any one of the preceding claims, further comprising storing (307) the setting of the converter to obtain the highest corrected supply voltage value required by all clusters and further comprising adjusting the first supply voltage (VS) to the highest corrected supply voltage value after a further power-up for driving the LEDs of the lighting systems. Procedure according to one of Claims 1 until 6 , further comprising storing (317) each of the voltage converter settings to provide calibrated supply voltage values required by each cluster, and further comprising adjusting the supply voltage (VS) in accordance with the highest calibrated supply voltage value required by all clusters after a further turning on those clusters to reach the preset voltage (Vr) to power at least each LED string of each of the clusters. System for supplying energy to a large number of clusters (29, 30) which comprise at least one LED strand (27, 31), the system comprising a master control unit (10) which has a voltage converter (16, 116) for providing a supply voltage (VS) and at least one interface (13, 15; 113) for communication with a large number of control units (20, 120), the system also comprising at least one control unit (20, 120) for supplying energy to at least each LED cluster (29 , 30), each control unit (20, 120) comprising: - at least one LED drive unit (20, 21, 23) per LED strand (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 to compare the measured voltage (Vpin) with a preset voltage (Vr) for that string, - a signal generator for generating 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 sending at least a first or second generated signal to the master control unit (10), the master control unit (10) further comprising means for correcting the supply voltage (VS) in accordance with the signals, which are generated in each of the control units (20, 120); wherein the control unit (20, 120) further comprises a processing unit (25, 125) for controlling the LED driving units (20, 21, 23), for obtaining the measured voltages (Vpin) from the voltage reading device (24, 124) and comparing this with the preset voltages (Vr) and for generating alarm signals. system after claim 9 , wherein each control unit (20, 120) is integrated in a single integrated circuit. system according to one of the claims 9 or 10 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 was obtained. system according to one of the claims 9 until 11 wherein a secondary LIN network is provided between the controllers (20, 120) and the master controller (10), separate from a primary network for connecting the master controller (10) to a higher tier system. system according to one of the claims 9 until 11 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.

Images