FR3070571A1 - DEVICE FOR CONTROLLING THE POWER SUPPLY OF LIGHT SOURCES WITH DYNAMICALLY RESPONSIVE BEHAVIOR - Google Patents

Abstract

The invention proposes a device for controlling the power supply of light sources, for example of LED light emitting diode type, the light sources participating in the production of a plurality of light functions of a motor vehicle. Each function may require a specific power profile in terms of speed, accuracy and stability. The architecture proposed by the invention makes it possible to provide this specific power supply profile for each light function by means of a single power unit.

Description

DEVICE FOR CONTROLLING THE SUPPLY OF LIGHT SOURCES TO

DYNAMIC SERVO BEHAVIOR

The invention relates to devices for controlling the power supply of light sources, in particular for motor vehicles. The invention relates in particular to a control device for supplying several light-emitting diodes, LEDs, which participate in the production of several light functions of a motor vehicle.

A light emitting diode, LED, is a semiconductor electronic component capable of emitting light of a predetermined wavelength when it is traversed by an electric current of a predetermined intensity. Above a threshold value called direct current, the intensity of the light flux emitted by an LED generally increases with the intensity of the electric supply current. Their small size and low power consumption make LED components interesting in the field of light modules for motor vehicles. LED-type light sources can for example be used to make distinctive optical signatures by placing the components along predetermined contours. By using LED components, the realization of lights with multiple light functions is also facilitated. The same light can for example perform a daytime running light function, DRL ("daytime running light") in a white color, and participate in a flashing function, TI ("turn indicator"), in amber color, by placing different components LED emitting light in the appropriate colors close to each other within the light module which produces the light in question. The different light functions have different needs in terms of power supply. Indeed, each light function is differentiated among other things by a regulatory light intensity that must be satisfied.

In order to guarantee a suitable power supply for light sources performing a given light function of a motor vehicle, it is known to use a control device comprising a switching converter. The duty cycle of the switching switch is controlled as a function of a current setpoint value to be supplied for the realization of the light function, and of a return value from a servo loop, the value of return representing the intensity of the current actually supplied by the converter to the sources. The control device makes known use of a comparison circuit providing a proportional-integrator type compensator, PI, in order to guarantee an appropriate reaction of the converter from the set value and the return value. The parameters of a PI type compensator determine, in a known manner, the speed, the precision and the stability of the control loop. For a precise light function, the electronic components of the PI compensator can therefore be dimensioned in a known manner in order to guarantee a suitable power supply for the light sources.

However, it is advantageous to be able to power a plurality of light functions of a motor vehicle by means of a single power unit, or a converter. This allows in particular a gain in terms of production costs and in terms of space required to produce a device for controlling the supply of several light functions.

However, the reactivity requirements in relation to the controlled values depend largely on the light functions. For example, a daytime running light (DRL) function may require that the electrical supply current rise slowly but precisely. On the other hand, a position light function, PL ("position light") may require a rapid rise while it tolerates a less precise level than the DLR function, while emitting a much reduced luminous flux.

A known power supply control device uses only one power unit, the servo loop of which includes a PI compensator sized to satisfy only the reaction needs compared to the servo values of a single light function . With such a device, the heterogeneous needs for electrical power for different light functions of a motor vehicle cannot therefore be optimally satisfied by the same power unit.

The invention aims to overcome at least one of the problems posed by the prior art. More specifically, the object of the invention is to propose a device for controlling the electrical supply of a plurality of light sources which is capable of supplying the light sources performing several heterogeneous light functions of a motor vehicle in an optimal manner and by means of a single power unit.

The subject of the invention is a device for controlling the electrical supply of at least one light source of a motor vehicle, configured to supply an electric current and an electric voltage to said light sources, the intensity of the electric current or the electrical voltage dependent on a supply setpoint. The control device comprises a comparison unit which comprises a first input for receiving said supply instruction, and a second input for receiving a return signal from a feedback loop, the feedback loop being configured to make available a signal representative of the intensity of the electric current or of the electric voltage supplied to the light sources, in which the comparison unit is arranged to generate a supply control signal which depends on said supply setpoint and said signal return according to a given servo function;

a power unit intended to receive said power control signal and to generate an electric current and an electric voltage for the supply of said light sources, the intensity of the electric current or the electric voltage being dependent on said control signal food.

The device is remarkable in that the comparison unit further comprises at least a third input for receiving a signal for selecting a servo function from a plurality of servo functions, the comparison unit being arranged for selecting said servo function according to said selection signal to generate said power control signal.

Preferably, the comparison unit can comprise a comparison circuit having an amplifier configured to amplify the difference between the supply setpoint and the return value, the participating amplifier, depending on the state of a selection circuit, when one of a plurality of proportional-integrator type compensators, PI, is produced, each PI regulator implementing a servo function, the state of the selection circuit being controlled by the selection signal. Alternatively, the plurality of compensators can include one or more proportional, P, proportional-derivative, PD, proportional-integrator-derivative, PID type compensators, or combinations thereof.

The comparison circuit may preferably include an amplifier feedback loop, and at least two different resistors through which the feedback signal can be connected to the amplifier, the selection circuit being configured to selectively connect the amplifier. 'one of said resistors to participate in the PI compensator.

Preferably, the comparison circuit may comprise a resistor through which the feedback signal is connected to the amplifier, and at least two feedback loops connectable to the amplifier, the selection circuit being configured to connect in a manner selective one of said feedback loops to participate in the PI compensator.

The comparison unit may preferably comprise a comparison circuit comprising a plurality of proportional-integrator compensators, PI, each PI compensator implementing a servo function, and each PI compensator having a dedicated amplifier and feedback loop for amplify the difference between the supply setpoint and the return value. The output of the comparison unit selectively corresponds to the output of one of the PI compensators, the output selection being carried out by a selection circuit controlled by the selection signal

Preferably, each servo function, and therefore each selectable PI compensator of the comparison circuit, can be configured so as to provide servo reactivity adapted to a particular light function of a motor vehicle, the reactivity being expressed in terms speed, precision and stability of the power control signal supplied by the comparison unit.

At least a part of the feedback branches can comprise a series connection of a capacity and a resistance.

Preferably, the comparison unit can include a fourth input for receiving a second return signal from a second feedback loop, the second feedback loop being configured to provide a signal representative of the voltage or current. electric supplied to light sources. The comparison unit can preferably be arranged to select a current or electric voltage servo function as a function of said selection signal to generate said power control signal.

The comparison unit can preferably comprise at least one signal measurement circuit or feedback signals, the measurement circuit comprising a measurement amplifier.

Preferably, the power unit can comprise a switching converter, the closing duty cycle of its switching switch having an influence on the intensity of the electric current generated by the power unit.

The switching converter may preferably be a converter of the SEPIC (“Single Ended Primary Inductor Converter”) type.

The comparison unit may preferably include a conversion circuit configured to transform the output signal of the comparison circuit into a power control signal intended to control the state of the switching switch of said switching converter.

Preferably, the power unit can comprise a linear converter. The comparison unit may preferably include a conversion circuit configured to transform the output signal of the comparison circuit into a signal level suitable for changing the setpoint of the linear element of said linear converter.

Preferably, the comparison unit can comprise at least one switch, preferably produced by a transistor, for example of the field effect transistor type, to participate in the production of said selection circuit.

The invention also relates to a light module for a motor vehicle comprising a plurality of light sources intended to perform a plurality of light functions of the motor vehicle, a device for controlling the electrical supply of the light sources and a control unit. The light module is remarkable in that the piloting device conforms to the device according to the invention, and in that the control unit is configured to supply a selection signal to the piloting device, the selection signal being dependent on the light function to be performed by light sources.

Alternatively or in addition, the selection signal may preferably depend on another parameter, such as for example the input supply voltage or the ambient temperature and / or light sources.

Preferably, the control unit can be configured to supply a supply setpoint to the control device, the supply setpoint being dependent on the light function to be performed by the light sources.

The control unit is preferably configured to determine the selection signal and / or the supply instruction which is to be supplied to the control device on the basis of an instruction received from a central unit of a motor vehicle,

Preferably, the light sources can comprise components with light-emitting semiconductor elements. It can for example be light-emitting diodes, LEDs.

Using the measures proposed by the present invention, it becomes possible to propose a device for controlling the electrical supply of a plurality of light sources comprising a single power unit and making it possible to choose a servo function for the unit. of power selectively. The proposed architecture makes it possible in particular to implement each servo function using a compensator, for example of the proportional integrator, PI, dedicated type. The electronic components of a given compensator are advantageously chosen so that their characteristics make it possible to produce an optimal control loop for a given light function of a motor vehicle. By making it possible to selectively switch between a plurality of servo-control functions available, the invention makes it possible to reduce the production costs of a light module integrating several light functions. In fact, by using a control device according to the invention in such a light module, it becomes possible to supply light functions with heterogeneous electric current needs (DRL, PL, TI, etc.) in an optimal manner by using a single converter. A reduction in the need for space compared to known solutions goes hand in hand with the gain in terms of production costs, since the proposed architecture uses only one converter, whereas according to the prior art, it would have needed a dedicated converter with a dedicated control function / loop and optimized by light function in order to obtain equivalent performance

Other characteristics and advantages of the present invention will be better understood with the aid of the description of the examples and of the drawings among which:

Figure 1 shows schematically a control device according to a preferred embodiment of the invention;

Figure 2 shows a circuit diagram of a control device according to a preferred embodiment of the invention;

Figure 3 shows an assembly diagram of a detail of a control device according to a preferred embodiment of the invention;

Figure 4 shows an assembly diagram of a detail of a control device according to a preferred embodiment of the invention;

Figure 5 shows an assembly diagram of a detail of a control device according to a preferred embodiment of the invention;

Figure 6 shows an assembly diagram of a control device according to a preferred embodiment of the invention.

Unless specifically indicated to the contrary, technical characteristics described in detail for a given embodiment may be combined with the technical characteristics described in the context of other embodiments described by way of examples and without limitation. Similar reference numbers will be used to describe similar concepts across different embodiments of the invention. For example, references 100, 200 and 500 denote three embodiments of a control device according to the invention.

The illustration of FIG. 1 shows a device 100 for controlling the electrical supply of at least one light source of a motor vehicle according to a first embodiment of the present invention. The light sources are illustrated by way of example by light-emitting diodes, LEDs. The device 100 is configured to supply an electric current of intensity I to said light sources. The intensity I of the electric current depends on a supply instruction 10 received by the device, for example from a control unit of a motor vehicle. The power supply setpoint may for example include an electric current intensity value that the device 100 must supply to the light sources to perform a given light function of the motor vehicle. The device comprises a comparison unit 110 which comprises a first input for receiving said supply instruction 10, and a second input for receiving a return signal 20 coming from a feedback loop. The feedback loop is configured to provide a signal representative of the intensity I of the electric current actually supplied to the light sources by the device 100. The comparison unit is arranged to generate a power control signal 40 which depends said supply setpoint 10 and said return signal 20 according to a given control function F1, F2, F3, ... The comparison unit 110 further comprises inputs for signals 10 and 20, at least a third input for receiving a selection signal 30 of a servo function Fx from among a plurality of servo functions Fl, F2, F3, ... available. Each control function makes it possible to specify the operation of the control device 100 in terms of reactivity with respect to the control loop. Thus, each function is preferably optimized for supplying a specific light function of the motor vehicle. For example, a first control function ensures that the electrical supply current supplied by the device 100 rises slowly but precisely, while a second control function ensures a rapid rise while the continuous level is adjusted by less precise. Other behaviors can be implemented, in particular by proportional-integrator compensators, PI, without departing from the scope of the invention. The comparison unit 110 is configured to select said servo function as a function of the selection signal 30 to generate the power control signal 40.

The device 100 also comprises a power unit 130 capable of generating an electric current of a predetermined intensity from an input voltage V ^, supplied for example by a current source internal to the vehicle, such as a battery , and from a supply control 40. This is, for example, a switching converter, the supply control 40 being in this case a control signal from the switching switch of the converter. Such converters are known per se in the art and their operation will not be detailed in the context of the present invention.

A light module according to an embodiment of the invention comprises a device 100 for controlling the electrical supply of the light-emitting diodes LED and a control unit produced for example by means of a microcontroller element. The operation of such a module is described by way of example only, and without limitation. The microcontroller element receives a message from a central vehicle control unit that the daytime running light function, DRL, should be turned on. The microcontroller element is configured to determine the intensity of the electric current to be supplied for this function, and to determine the servo function. This can for example be achieved by pre-recording this data in a memory element to which the microcontroller element has read access. The signals 10 and 30 are thus determined and supplied to the respective inputs of the device 100, which selects the required servo function - ie, in the DRL case it is a function which ensures that the supply current rises gently but precisely - and transmits the power control signal corresponding to the power unit 130.

FIG. 2 shows a second embodiment of the control device 200 according to the invention. Compared to the diagrammatic illustration in Figure 1, some components are specified more explicitly. For example, and in a nonlimiting manner, the power unit 230 is represented by a switching converter of the SEPIC type, the operation of which is known per se, and the switching switch of which is controlled by the control signal d power supply 40 supplied by the comparison unit 210. The comparison unit 210 comprises several arrangements. It is a comparison assembly 220 intended to compare the supply setpoint 10 with the return signal 20 by means of a servo function chosen according to the selection signal 30. The operation of the comparison assembly 220 will be detailed in relation with FIG. 3. The conversion assembly 214 is configured to convert the output signal 41 of the comparison assembly 220 into the power control signal 40 adapted to control the converter 230. The output signal 41 generally corresponds to a difference between the compared values which remains to be filled by the converter, while the supply control signal 40 is generally a PWM type signal ("draw width modulation") specifying binary the durations of the state of opening / closing of the controlled switch. Optionally, the comparison unit 210 comprises a measurement circuit 212 involving a measurement amplifier, such arrangements being per se known in the art and serving to obtain a measurement representative of the intercepted electric current.

Figure 3 shows the comparison circuit 220 of the comparison unit 210 shown in Figure 2 in detail. The circuit includes an amplifier 222 having as input the supply setpoint 10 and the return value 20. The amplifier is provided with a feedback branch comprising a series connection of a capacitor C and of a resistance R. The comparison circuit 220 includes a selection circuit involving two switches S1 and S2. If the selection signal 30 specifies the control function PII, the switch SI is closed and the switch S2 is open, so that the return value 20 of the control loop is connected through the resistor RB1 to the amplifier. The resulting assembly is a first proportional-integrator compensator, PI, whose components RB 1, R, C define the behavior of the control loop in terms of stability, precision and speed. If the selection signal 30 specifies the servo function PI2, the switch SI is open and the switch S2 is closed, so that the value 20 of feedback from the servo loop is connected through the resistor RB2, of different ohmic resistance to RB 1, to the amplifier. The resulting assembly is a second proportional-integrator compensator, PI, whose components RB2, R, C define the behavior of the control loop in terms of stability, precision and speed. The two selectable compensators PII and PI2 implement two different control functions and the resulting signal 41 is used, after conversion as described above, to control the power unit of the device according to the invention.

FIG. 4 shows a different embodiment of the comparison circuit 320 which can also be used in the comparison unit 210 shown in FIG. 2. The circuit comprises an amplifier 322 at which the return value 20 of the servo loop is connected through a resistor R. On the other hand, the supply setpoint 10 is also supplied at the input of the amplifier. If the selection signal 30 specifies the servo function PI3, the switch SI is closed and the switch S2 is open, so that the circuit includes a first feedback loop comprising the series connection of the capacitor CAI and RAI resistance. The resulting assembly is a first proportional-integrator compensator, PI, whose components R, RAI, CAI define the behavior of the control loop in terms of stability, precision and speed. If the selection signal 30 specifies the servo function PI4, the switch SI is open and the switch S2 is closed, so that the circuit includes a second feedback loop comprising the series connection of the capacitor CA2 and resistance RA2. The second feedback loop comprises at least one component different from the CAI, RAI components of the first feedback loop.

The resulting assembly is a second proportional-integrator compensator, PI, whose components R, RA2, CA2 define the behavior of the control loop in terms of stability, precision and speed. The two selectable compensators PI3 and PI4 implement two different control functions and the resulting signal 41 is used, after conversion as described above, to control the power unit of the device according to the invention.

FIG. 5 shows a different embodiment of the comparison circuit 420 which can also be used in the comparison unit 210 shown in FIG. 2. The circuit comprises a first amplifier 422 at which the return value 20 of the loop servo is connected through a resistor RB 1 and having a feedback branch comprising a series connection of a capacitor Cl and of a resistor RL The circuit also includes a second amplifier 423 to which the return value 20 of the loop servo is connected through a resistor RB2 and having a feedback branch comprising a series connection of a capacitor CAI and a resistor RAI. The supply setpoint 10 is supplied at the input of the two amplifiers 422, 423. If the selection signal 30 specifies the servo function PI5, the switch SI is closed and the switch S2 is open. The circuit comprising the first amplifier 422 is activated. It produces a first proportional-integrator compensator, PI, whose components RB1, RI, Cl define the behavior of the control loop in terms of stability, precision and speed. If the selection signal 30 specifies the control function PI6, the switch SI is open and the switch S2 is closed. The circuit comprising the second amplifier 423 is activated. It produces a second proportional-integrator compensator, PI, whose components RB2, RAI, CAI define the behavior of the control loop in terms of stability, precision and speed. The two selectable compensators PI5 and PI6 implement two different control functions and the resulting signal 41 is used, after conversion as described above, to control the power unit of the device according to the invention.

The switches of the selection assemblies described can preferably be produced by transistors, in particular field effect. The examples described for the selection between two control functions by comparison circuit can be extended to a greater number of control functions without departing from the scope of the present invention.

FIG. 6 shows another embodiment of the control device 500 according to the invention. The power unit 530 is represented in a nonlimiting manner by a SEPIC type switching converter, the switching switch of which is controlled by the power control signal 40 supplied by the comparison unit 510. The comparison unit 510 includes several assemblies. On the one hand, it is a comparison assembly 520 intended to compare the supply setpoint 10 with a first return signal 20 representative of the intensity of the electric current supplied to the light sources by means of a selected servo-control function. using the selection signal 30. As such, the comparison assembly comprises a first PI type compensator, 522. The comparison assembly is also intended to compare, alternatively, the supply setpoint 10 and a second return signal 20 ′ representative of the electric voltage applied to the branch comprising the light sources, by means of a servo function chosen using the selection signal 30. As such, the comparison assembly comprises a second type compensator PI, 523. The selection signal 30 makes it possible to use either the output of the first PI 522 compensator, or of the second PI 523 compensator at output 41 of the comparison assembly, so as to switch between a current or electric voltage control.

The conversion assembly 514 is configured to convert the output signal 41 of the comparison assembly 520 into the power control signal 40 adapted to control the converter 530. The output signal 41 generally corresponds to a difference between the compared values which remains to be filled by the converter, while the power control signal 40 is generally a PWM type signal ("draw width modulation") specifying binary the durations of the open / close state of the '' controlled switch. Optionally, the comparison unit 510 comprises measurement circuits 512, 512 ′ involving a measurement amplifier, such arrangements being per se known in the art and serving to obtain a measurement representative of the intercepted electric current or voltage. .

While in the embodiments described, the example of one or more PI type compensators has been given, the compensators involved in the respective comparison units may also, depending on the intended application, include proportional type compensators, 15 P , proportional-derivative, PD, proportional-integrator-derivative, PID, or combinations thereof.

The extent of protection is determined by the claims.

Claims (12)

1. Device for controlling (100, 200, 500) the electrical supply of at least one light source of a motor vehicle, configured to supply an electric current and an electric voltage to said light sources, the intensity of the electric current or the electric voltage depending on a supply setpoint (10), the control device comprising: a comparison unit (110, 210, 510) which comprises a first input for receiving said supply instruction (10), and a second input for receiving a return signal (20) from a feedback loop, the loop being configured to provide a signal representative of the intensity of the electric current or the electric voltage supplied to the light sources, in which the comparison unit (110, 210, 510) is arranged to generate a control signal supply (40) which depends on said supply setpoint and said return signal according to a given control function; a power unit (130, 230, 530) for receiving said power control signal (40) and for generating an electric current and an electric voltage for supplying said light sources, the intensity of the electric current or the electric voltage being dependent on said supply control signal, characterized in that the comparison unit (110, 210, 510) further comprises at least a third input for receiving a selection signal (30) of a function d 'servo among a plurality of servo functions, the comparison unit being arranged to select said servo function according to said selection signal (30) to generate said power control signal (40). 2. Device according to claim 1, characterized in that the comparison unit (210, 510) comprises a comparison circuit (220, 320, 420, 520) having an amplifier (222, 322, 422) configured to amplify the difference between the supply setpoint (10) and the return value (20), the amplifier participating, depending on the state of a selection circuit, in the production of one of a plurality of proportional type compensators -Integrator, PI, each PI compensator implementing a servo function, the state of the selection circuit being controlled by the selection signal (30). 3. Device according to claim 2, characterized in that the comparison circuit (220) comprises a feedback loop of the amplifier, and at least two different resistors through which the return signal (20) is connectable to Γ amplifier (222), the selection circuit (SI, S 2) being configured to selectively connect one of said resistors to participate in the PI compensator. 4. Device according to claim 2, characterized in that the comparison circuit (320) comprises a resistor through which the return signal (20) is connectable to the amplifier, and at least two feedback loops of the amplifier (322), the selection circuit (SI, S2) being configured to selectively connect one of said feedback loops to participate in the PI compensator. 5. Device according to claim 1, characterized in that the comparison unit comprises a comparison circuit (420) comprising a plurality of proportional-integrator compensators, PI, each PI compensator implementing a servo function, and each PI compensator having a dedicated amplifier (422, 423) and a feedback loop for amplifying the difference between the supply setpoint and the return value, the output of the comparison unit selectively corresponding to the output of the one of the PI compensators, the output selection being carried out by a selection circuit controlled by the selection signal (30). 6. Device according to one of claims 3 to 5, characterized in that at least a part of the feedback branches comprises a series connection of a capacity and a resistance. 7. Device according to one of claims s 1 to 6, characterized in that the comparison unit (510) comprises a fourth input for receiving a second feedback signal (20 ') from a second feedback loop, the second feedback loop being configured to provide a signal representative of the electric voltage supplied to the light sources, the comparison unit (510) being arranged to select a function for controlling current or electric voltage as a function of said signal selection (30) for generating said power control signal (40). 8. Device according to one of claims 1 to 7, characterized in that the comparison unit comprises (210, 510) at least one measurement circuit (212, 512, 512 ') of the signal or return signals, the circuit measuring device comprising a measuring amplifier. 9. Device according to one of claims 1 to 8, characterized in that the power unit (130, 230, 530) comprises a switching converter, whose duty cycle of closing of its switching switch has an influence on the intensity of the electric current generated by the power unit, x 10. Device according to claim 9, characterized in that the comparison unit (210, 510) 5 comprises a conversion circuit (214, 514) configured to transform the output signal of the comparison circuit (41) into a power control signal (40) intended to control the state of the cut-off switch of said converter cutting. 11. Light module for a motor vehicle comprising a plurality of sources 10 lights intended to perform a plurality of light functions of the motor vehicle, a device for controlling the electrical supply of light sources and a control unit, characterized in that the control device conforms to the device according to one of claims 1 to 10, and in that the control unit is configured to supply a selection signal to the control device, the signal 15 selection being dependent on the light function to be performed by the light sources. 12. Light module according to claim 11, characterized in that the light sources comprise components with light-emitting semiconductor elements.