WO2018138060A1

WO2018138060A1 - Module for controlling the electrical power supply of a plurality of light sources of a motor vehicle

Info

Publication number: WO2018138060A1
Application number: PCT/EP2018/051479
Authority: WO
Inventors: Christophe Roger
Original assignee: Valeo Vision
Priority date: 2017-01-26
Filing date: 2018-01-22
Publication date: 2018-08-02
Also published as: FR3062258B1; FR3062258A1

Abstract

The invention relates to a module for controlling a plurality of light sources of a motor vehicle. The module is designed to emit a plurality of pulsewidth modulation signals generated from a primary control signal. The pulsewidth modulation signals generated are used to control devices for controlling the electrical power supply of said light sources.

Description

ELECTRIC POWER SUPPLY CONTROL MODULE OF A PLURALITY OF LIGHT SOURCES OF A MOTOR VEHICLE

The invention relates to lighting systems for motor vehicles. In particular, it relates to controlling the power supply of a plurality of light sources in pulse width modulation mode.

It is becoming more and more common to use light sources with a semiconductor element, such as light-emitting diodes, LEDs, to achieve different light functions of a vehicle. These functions may for example include daytime running lights, position lights, direction indicators or dipped beam. In known manner, a device for controlling the power supply is necessary to power a group of LEDs performing a given light function. Such a control device generally comprises a voltage converter which, from a DC input voltage supplied by a source internal to the vehicle, such as a battery, is capable of generating an output voltage of appropriate value for the power supply of the group of LEDs. An LED emits light when a voltage of at least one threshold value, called forward voltage, is applied across its terminals. The intensity of the luminous flux emitted by an LED generally increases with the average intensity of the electric current passing through it, beyond the threshold value of the direct current.

Known converters include converters SEPIC type (of the English "Single-Ended Primary Inductor Converter"), flyback, boost ("boost") or step-down ("buck"). Such converters involve a switch element, such as a transistor, whose state is periodically switched between the open and closed values. The switching frequency applied to the switch influences the value of the output voltage and the average value of the output current.

It is furthermore known to adjust the luminous intensity of the light sources thus fed, by applying a pulse width modulation (PWM) signal having a given duty cycle and peak current to the converter. cutting. By adapting the frequency, the duty cycle and the peak current of the pulse width modulation signal, a predetermined average current intensity can thus be obtained at the converter. This implies, at the level of the light sources supplied, that a luminous flux of an intensity corresponding to the average intensity of the current flowing through them is emitted. The greater the average intensity of the current flowing through the light sources, the greater the intensity of the luminous flux emitted by light sources is important. Such an architecture thus makes it possible to sift the intensity of the luminous flux by the light sources by modifying the parameters of a PWM signal. As the frequency of a PWM signal is generally high, the emitted luminous flux will be pulsed at this same frequency, and the pulsations are not perceptible by the human eye. The human visual system is distinguished by an integral type of perception and perceives, with respect to a constant and non-pulsed luminous flux, a flux of constant but reduced luminous intensity.

The number of LEDs required per projector in a motor vehicle increases, with a need for individual management of the luminous flux emitted by each LED. This implies that it is necessary to generate a large number of PWM signals. In known manner each PWM signal is generated by a microcontroller element. However, the number of available channels per microcontroller element is limited and typically less than twenty. The use of a plurality of microcontroller elements in parallel is an expensive solution that requires a large physical volume in the restricted environment of a motor vehicle headlamp. There is therefore a need for a solution that makes it possible to obtain forty or more PWM signals according to the number of LEDs envisaged, while maintaining a restricted physical footprint. The invention aims to overcome at least one of the problems posed by the prior art.

The invention relates to a control module of a plurality of electronic components, including a plurality of light sources of a motor vehicle. The control module is notable in that it is configured to output a plurality of pulse width modulation signals for controlling devices for controlling the power supply of said electronic components. The module comprises a control unit configured to generate a primary control signal as a function of at least one supply setpoint, in particular voltage and / or current, and a shift unit comprising a plurality of outputs. The shift unit is configured to receive said primary control signal in portions, temporally offset. It transmits a portion of each received portion on one of the outputs, so that each output generates one of the pulse width modulation signals. Preferably, each portion of the primary control signal may include as many values as there are outputs on the shift unit. The control unit may preferably comprise a microcontroller element. Alternatively or in a complementary manner, the control unit may comprise an ASIC element (acronym for "Application-Specific Integrated Circuit", literally "application-specific integrated circuit"), or an element of type FPGA (acronym for "Field-Programmable Gâte Array" or "network of doors programmable in situ").

Alternatively, the shift unit may comprise a shift register. The shift unit is made by a programmable electronic component. It may be an FPGA ("Field Programmable Gate Array") component.

Preferably, the shift unit may comprise three signal inputs: data, latch and dock, said signals being supplied by the control unit.

Preferably, the data signal may comprise the primary control signal, and the latch pulse has, over a period of the primary control signal, a frequency equivalent to the inverse of the number of different duty cycles that the width modulation signals pulse can take, the contents of the shift unit being switched to its outputs on receipt of a latch pulse.

Preferably, a value of the primary control signal may be loaded into the shift unit upon receipt of each pulse of the dock signal. The shift unit may preferably comprise as many outputs as the module generates different pulse width modulation signals.

The invention also relates to a light device for a motor vehicle, comprising a plurality of light sources whose power supply is controlled by a plurality of control devices, and comprising a control device of the control devices which is configured to providing a plurality of pulse width modulation signals to the drivers. The light device is remarkable in that the control module is in accordance with the invention. The light sources may preferably include electroluminescent semiconductor element sources. These can be LEDs, LEDs, or Laser diodes. By using a shift unit to convert a serial primary control signal into a plurality of PWM-type parallel control signals, the measurements of the invention make it possible to generate a large number of different control signals with a single generator. The large number of control signals allows in particular the individual management of the luminous flux emitted by a large number of electroluminescent light sources.

Other features and advantages of the present invention will be better understood from the exemplary description and the drawings, among which:

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

FIG. 2 schematically shows the use of one of the control signals generated by means of a control module according to a preferred embodiment of the invention;

Figure 3 schematically shows the generation of control signals in a control module according to a preferred embodiment of the invention.

Unless specifically indicated otherwise, 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 example and not limitation.

Figure 1 gives a schematic illustration of a control module 100 according to a preferred embodiment of the invention. Such a control module is used to control a plurality of light sources, exemplary light emitting diode type, LED, of a motor vehicle. The module 100 comprises a control unit 110 operably connected to a shift unit 120. The control unit 110 is exemplarily indicated as being made by a microcontroller element, and the offset unit 120 is illustrated as being a register. shift. These two units can, however, be implemented by different means, for example by programmable elements of the FPGA type, without departing from the scope of the invention. The module is supplied with electric current by an internal power source to the vehicle that it equips. The control unit 110 is configured to generate a primary control signal 112 on its output labeled "Data". In addition, it generates a pulse signal clock periodicals on the "clock" output and another periodic pulse signal on the "latch" output. The signal 112 is preferably periodic and the duration of its period T corresponds to the number of different control signals to be generated in parallel, multiplied by the number of different cyclic ratios that these control signals can take.

The output signals of the control unit 110 are wiredly connected to the inputs of the shift unit 120. In the example shown, the shift unit comprises four separate outputs A, B, C and D. From In general, a number of outputs N (in the example given, N = 4) equivalent to the number of different control signals to be generated by the module 100 is provided. At each clock stroke of the clock signal, CLK, a value of the primary control signal 112 is received on the input "Data" and stored temporarily in a memory element connected to one of the outputs A, B, C or D. All the memory elements of the shift register 120 therefore comprise a specific value after N clock ticks. The values contained in the memories A-D are sequential values of the primary control signal and constitute a portion of the control signal. The pulse signal "latch" has, by period T of the primary control signal 112, a frequency equal to the inverse of the number of different cyclic ratios that the pulse width modulation signals can take (R = 4 in The example). Upon receipt of a latch signal pulse, the shift register 120 toggles the contents of the memory elements A-D to its respective outputs. Part of the portion of the registered primary control signal is transmitted on each of the PWM_A, PW _B, PW _C and PWM_D outputs, respectively. The output values represent the first values of the four pulse width modulation signals generated by the control module 100. The register then receives the next four sequential values of the primary control signal 112, and so on.

FIG. 2 shows, as an example, the use of one of the generated signals PWM_A in a light device of a motor vehicle. The control signal PWM_A makes it possible to control the intensity of the luminous flux emitted by the LEDs 10, by acting on the average intensity of the electric current I which passes through them, and which is supplied by the power control device 130.

FIG. 3 serves to illustrate in more detail the steps of the method of generating the PW _A, PWM_B, P _C, and PW _D signals from the primary control signal 112 and by means of the control module 100 of FIG. primary control signal 112 corresponds to the "Data" output of the microcontroller element 110. According to the axis temporal, signal portions 112-1, 112-2, 112-3 and 112-4 follow each other. Each portion includes a value for inclusion in one of the control signals PWM_A, PWM_B, PWM_C, and PWM_D, respectively. The successive values of each of the control signals PWM_A, PW _B, PWM_C, and PWM_D follow each other in the order of the portions 112-1, 112-2, 112-3 and 112-4 of the primary control signal 112.

After the first four clock ticks of the dock signal, CLK, the four values corresponding to the first portion of the control signal 112 appear in the memory elements A, B, C, and D of the shift register 120. At this time , the first signal pulse "latch", indicated by "Latch 1" is received by the shift register, and the respective values (A = 1, B = 1, C = 1, D = 1) are generated on the outputs PWM_A, PWM_B, PWM_C, and PWM_D respectively.

After the next four clock ticks of the dock signal, CLK, the four values corresponding to the second portion 112-2 of the control signal 112 are contained in the memory elements A, B, C, and D of the shift register 120. At this time, the second "latch" signal pulse, indicated by "Latch 2" is received by the shift register, and the respective values (A = 1, B = 1, C = 1, D = 0) are generated. on the PWM_A, PWM_B, PWM_C, and PWM_D outputs respectively, and so on.

It becomes apparent that the example given makes it possible to produce PWM signals with cyclic ratios having increments of 25%. The duty cycle of the signal PW _D corresponds to 25%, the duty cycle of the signal PWM_C corresponds to 50%, that of the signal PWM_B corresponds to 75% and the signal PWM_A has a duty cycle of 100%. There are therefore four control signals with four possible different duty cycles using four latch pulses, and one primary control signal spread over sixteen clock ticks.

With the functional and structural description that has just been given, those skilled in the art will be able to program a microcontroller element so as to implement the functions according to the invention, by using his general knowledge in computer science. The parameters of the module according to the invention (number of outputs of the offset unit, switching frequency, resolution of the cyclic ratios, design of the primary control signal, etc.) can in particular be adapted to the specific applications targeted and according to the number of PWM type control signals required, without departing from the scope of the present invention.

Claims

claims

Control module (100) for a plurality of electronic components, in particular a plurality of light sources (10) of a motor vehicle, characterized in that

the module is configured to output a plurality of pulse width modulation signals (PWM_A, PWM_B, PWM_C, PWM_D) for controlling power control devices (130) of said electronic components;

the module comprising

a control unit (110) configured to generate a primary control signal (112) as a function of at least one supply setpoint, in particular current or voltage, and

a shift unit (120) having a plurality of outputs (A, B, C, D), the shift unit being configured to receive said primary control signal (112) in portions (112-1, 112-2, 112- 3, 112-4) in a temporally offset manner, and to emit a portion of each received portion on one of the outputs, so that each output (A, B, C, D) generates one of the width modulation signals pulse (PWM_A, PWM_B, PWM_C, PWM_D).

Module according to the first claim, characterized in that each portion of the primary control signal comprises as many values as there are outputs on the shift unit.

Module according to one of claims 1 or 2, characterized in that the control unit comprises a microcontroller element.

Module according to one of claims 1 to 3, characterized in that the shift unit comprises a shift register.

Module according to one of claims 1 to 3, characterized in that the shift unit is provided by a programmable electronic component.

Module according to one of claims 1 to 5, characterized in that the shift unit comprises three signal inputs: data, latch and dock, said signals being provided by the control unit.

7. Module according to claim 6, characterized in that signal data comprises the primary control signal, and in that the latch pulse has, over a period of the primary control signal, a frequency equivalent to the inverse of the number of reports. cyclic different pulse width modulation signals can take, the contents of the shift unit being switched to its outputs on receipt of a latch pulse.

8. Module according to one of claims 6 or 7, characterized in that a value of the primary control signal is loaded in the shift unit on receipt of each pulse of the dock signal.

9. Module according to one of claims 1 to 7, characterized in that the shift unit comprises as many outputs that the module generates different pulse width modulation signals.

A light device for a motor vehicle, comprising a plurality of light sources whose power supply is controlled by a plurality of drivers, and comprising a driver control module which is configured to provide a plurality of signaling signals. pulse width modulation to the control devices, characterized in that the control module is according to one of claims 1 to 9.

11. Light device according to claim 10, characterized in that the light sources comprise electroluminescent semiconductor element sources.