DEVICE AND METHOD FOR ADAPTING THE CHARGING CURRENT IN AN ELECTRONIC CIRCUIT

Abstract

The invention provides a device and a method for reading the current delivered by a voltage source to a current-consuming device. When the read current is below a predetermined limit, which may correspond, for example, to a predetermined limit of a diagnostic device for the current-consuming device, the invention's measures allow for the addition of a fictitious current consumption to raise the current measured by the diagnostic device to a value greater than or equal to the predetermined limit, and therefore acceptable. This prevents the diagnostic device from falsely detecting a fault in the current-consuming device.

Description

In practice, as well as during certain conformity tests, the measured value of the intensity of the charging current consumed by the electronic device is however distorted by parasitic signals which are superimposed on the evaluated signals. During a specific conformity test, for example, a sinusoidal signal is superimposed on the direct voltage assumed to be constant and supplied by a battery of a motor vehicle. This disturbance propagates through the system and potentially distorts the intensities of the electric current consumed by the device which is powered by the resulting electric voltage. Figure 1 schematically shows the main electronic components of a device 100 according to a preferred embodiment of the invention. A voltage source 10 supplies a device 20. This is for example a battery 10 of a motor vehicle. Furthermore, the device 20 may comprise one or more light sources of the light-emitting diode, LED, type, as well as means for controlling the power supply of the light sources. Such control means are known in the art and generally involve DC / DC converters to provide a current of an intensity capable of controlling the LEDs mounted on load. The device 100 comprises in particular means 110 for measuring and detecting the current lin(V) consumed by the consumer device 20. The current depends on the voltage applied to the terminals of the device 100, it is therefore also sensitive to disturbances in the voltage V|N supplied by the voltage source 10. The measuring and detecting means 110 are functionally connected to a charging circuit 120 of the device 100. The charging circuit 120 implements a dummy load which is capable of consuming an electric current of a predetermined intensity l|Oad in the electric circuit. This electric current is however only consumed when the measuring and detecting means 110 control the charging circuit 120 to activate it. The activation signal of the charging circuit 120 is generated by the measuring and detection means 110 only if the measured electric current lin(V) is lower than a predetermined static threshold value lseuii, i.e. independent of the applied voltage. The threshold value preferably corresponds to a threshold value below which diagnostic means of the motor vehicle conclude that there is a fault in the consumer 20. For a consumer comprising LED light sources, the threshold value may for example be approximately 130 mA. When an electric current lin(V) lower than the threshold value lseui| is detected while the consumer device has no operating fault, the dummy load 120 is activated and consumes an additional load current l|Oad sized so that (lin(V) + l|Oad) > lseui|. The additional load current l|Oad is independent of the applied voltage. When the electric current lin(V) becomes higher than the threshold value lseui| again, the dummy load 120 is deactivated. The device may include means (not shown) for detecting a failure of the current consumer, separate from the measuring and detecting means, which, when a failure is detected, disconnect the dummy load 120. This functionality may also be included in the circuit or microcontroller that implements the measuring and detecting means. A failure may, for example, be detected if no current flows through the load branch comprising the LEDs, while the load branch is supposed to be powered. The load 120 is preferably sized so that the current intensity lioad is substantially equal to the threshold value lseuii, possibly increased by a margin of error or safety of the order of ten milliamperes. When liOad=lseuii, it goes without saying that the above inequality is respected for measured values ​​lin(V) that are positive but less than lseui|. It follows that a diagnostic device measuring the total charging current lin(V) + lseui| will therefore conclude that the device is operating correctly. In order to ensure correct operation when lin(V) can take negative values, one can choose l,oad = lseui| + Ah with A|>0 positive. In the example of Figure 1, the charging circuit 120 is connected in parallel with the consumer device 120. The measuring and detection means 110 are produced using a shunt resistor R connected low-side, that is to say in series and on the weak side of the consumer device 20 and the charging circuit 120. The voltage measured across the shunt resistor R allows a microcontroller element to evaluate the intensity of the current lin(V). The threshold value lseui| is stored in a memory element of, or readable by, the microcontroller element, so that the latter can compare the intensity of the measured current to the threshold value, and activate the charging circuit 120 according to the result of this comparison, as described above. In the example shown, the charging circuit 120 is activated by closing a switch element.Other embodiments of this functionality are however conceivable without departing from the scope of the present invention. Once the charging circuit 120 is connected, the microcontroller element measures the charging current lin(V) + l|Oad, which is preferably equal to lin(V) + lseui|. A comparison of this charging current with the double threshold 2-lseui| allows the microcontroller element to decide whether the actual charging current lin(V) has a sufficiently high intensity to be able to deactivate the charging circuit 120. Indeed, if lin(V) + lseui| > 2-lseui|, the deactivation condition is met and a control signal for deactivating the charging circuit is generated by the microcontroller element. The sizing of the corresponding lower and upper threshold values, as well as the Ah value, strongly depends on the components (BCM, powered device) used. A person skilled in the art will be able to adapt these values ​​depending on a particular application, without departing from the scope of the present invention and without having to apply any inventive step.Similarly, the measuring and detecting means 110 may be implemented by analog comparator circuits instead of using a programmed microcontroller element. It is also possible to combine analog circuits with one or more microcontroller elements to implement the functionality just described. By way of example only and without limitation, Figure 2 shows a circuit diagram of a dummy load circuit 120 as shown in Figure 1. The circuit which can be activated and deactivated using a binary control signal generated by a microcontroller element, and which, when activated, consumes an electric current of a predetermined intensity in the electronic circuit which incorporates it. The signal SW LOAD controls the transistor U5 and makes it possible to deactivate the circuit in the event of a real failure of the consumer device, or when the load current lin(V) is greater than the predetermined threshold value lseui|. The assembly uses the operating principle of a Schmitt trigger.When the measured charging current, indicated indirectly by the voltage Vsense, is lower than a first lower threshold, the circuit consumes an electric current of a predetermined intensity, which is sized so that its sum with lin(V) is greater than lseui|. Similarly, when the resulting sum becomes greater than a second predetermined threshold, no electric current is consumed by the charging circuit.

Claims

Claims 1. Electronic device (100) intended to be connected to the load of a voltage source which supplies a current consumer, the device comprising means for measuring and detecting (110) the current lin(V) consumed by the consumer and a load circuit (120), the measuring and detecting means being connected to the load circuit (120); characterized in that the measuring and detecting means (110) are intended to control the activation of the charging circuit (120) following the detection of a current lin(V) of an intensity lower than a predetermined static threshold value Iseuii, and in that the charging circuit (120) is intended to consume a current hoad, the intensity of which is such that (hn(V) + hoad) s |seUii when it is activated, the measuring and detecting means (110) are intended to deactivate the charging circuit (120) following the detection of a current (hn(V) + hoad) of an intensity greater than twice the predetermined static threshold value Iseuii- 2. Device according to claim 1, characterized in that the predetermined threshold value is equal to lseuii = hoad +Ai, Ai being less than 10 mA.

3. Device according to one of claims 1 to 2, characterized in that the charging circuit (120) is intended to be connected in parallel with the current consumer.

4. Device according to one of claims 1 to 3, characterized in that the measuring and detection means (110) comprise a shunt resistor connected in series with the current consumer and the load circuit, on the weak side thereof.

5. Device according to one of claims 1 to 4, characterized in that the measuring and detection means (110) comprise a microcontroller element.

6. Device according to claims 4 and 5, characterized in that the microcontroller element is configured to obtain a measurement of the intensity of the electric current which passes through the shunt resistor.

7. Electrical power supply system for a light device for a motor vehicle comprising a current source (10), a light device (20) powered by said source, and a diagnostic device intended to detect a failure of the light device (20) if the load current measured by the diagnostic device is of an intensity lower than a predetermined static threshold value lseuii, characterized in that the system comprises a device (100) according to one of claims 1 to 6 connected to the load of said voltage source (10), intended to adapt the load current measured by the diagnostic device to a value greater than or equal to lSeuii, when the current consumed by the light device (20), Ijn(V), is lower than lSeuii without presenting a failure.

8. System according to claim 7, characterized in that the light device (20) comprises one or more light sources.

9. System according to claim 7, characterized in that the light sources comprise light-emitting diodes, LEDs, organic light-emitting diodes, OLEDs, or laser diodes.

10. System according to one of claims 7 to 9, characterized in that the light device (20) comprises means for controlling the power supply of the light sources.

11. Method for adapting the charging current using a device (100) according to one of claims 1 to 6 in an electronic circuit comprising a current consumer (20) supplied by a current source (10), characterized in that the method comprises the following steps: detection of a current consumed by the consumer, ljn(V), of an intensity lower than a predetermined static threshold value lSeuii; activation of the charging circuit (110) of said device (100) following said detection, the charging circuit consuming a current l|Oad, the intensity of which is such that the charging current (lin(V) + hoad) s lSeuili- 12. Method according to claim 11, characterized in that the method further comprises a step of deactivating the charging circuit (110) following the detection of a charging current greater than a predetermined limit threshold value.

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