Device for controlling the electrical power supply of a circuit for a vehicle, comprising a battery and corresponding assembly

The present invention generally relates to the electrical power supply of an electrical or electronic circuit of a motor vehicle provided with an electrical battery.

Usually, a vehicle comprises electrical circuits for powering various electrical equipment, such as an additional heating device or a lighting system. The vehicle also includes electronic circuits and, in particular, a computing and controlling system which comprises, for example, one or more computers for saving data and controlling equipment of the vehicle. These electrical or electronic circuits are intended to be powered by the battery of the vehicle.

However, during the operation of the vehicle, the battery may be subjected to drops in voltage. To compensate for these drops in voltage, the vehicle comprises a capacitive reserve, i.e. a reserve of electrical energy stored by one or more capacitive elements such as a capacitor or a supercapacitor. During a drop in voltage, the capacitive reserve makes it possible to continue powering the circuits of the vehicle in need thereof.

However, it is noted that the capacitive reserve of the vehicle discharges very rapidly. Thus, a computer of the computing and controlling system of the vehicle that is in the process of carrying out a memory write operation may not have sufficient time to complete this operation. The result thereof can be, for example, that the computing and controlling system of the vehicle may generate errors and/or be damaged.

An aim of the present invention is, for example, to propose a new circuit controlling device which makes it possible, in the case of a drop in voltage of the battery, to favor the powering of one or some circuits of the vehicle, for example to reduce the risk of a computer of the vehicle not having the time to complete writing to a memory (such as a read-only memory) of the computing and controlling system.

To this end, the subject matter of the invention is a device for controlling the electrical power supply of a circuit for a vehicle, said vehicle comprising:

an electrical battery having a first terminal and a second terminal, an electrical energy storage element, one terminal of which is linked to the first terminal of the battery and the other terminal of which is linked to an electrical ground, a first circuit, capable of consuming electricity coming from the electrical battery, and having a first and a second terminal which are connected to the first and second terminals of the electrical battery, respectively, electrical power supply management means configured to allow or prevent the passage of electrical current between said electrical energy storage element and said first circuit,

characterized in that said controlling device includes:

detection means configured to detect a drop in the voltage of the electrical battery below a threshold value; command means configured, in the case of detection of a drop in the voltage of the battery below said threshold value, to command said electrical power supply management means to prevent the passage of electrical current between the electrical energy storage element and said first circuit.

Such a controlling device makes it possible, in the case of a drop in voltage of the battery, to favor the powering of one or some circuits of the vehicle, by isolating said first circuit from the energy storage element. Thus, the energy of the energy storage element can be used to continue powering a computer for the time that it takes to finish a memory write operation.

Such a device also makes it possible, in the case where said first circuit includes one or more transistors, to reduce the risk of damage to said transistor(s) of this first circuit. In the absence of such a controlling device, the drop in voltage could force the transistor(s) to operate in linear mode which could damage them.

According to an advantageous characteristic of the invention, said first terminal of the battery is the positive terminal and said second terminal is the negative terminal.

According to an advantageous characteristic of the invention, said electrical power supply management means comprise a first transistor.

Thus, said command means are configured to command, in the case of detection of a drop in the voltage of the battery below said threshold value, the off-state of the first transistor.

According to an advantageous characteristic of the invention, said first transistor has an input electrode connected to the first terminal of the battery, an output electrode connected to said second terminal of said first circuit, and a further output electrode connectable to the electrical ground.

According to an advantageous characteristic of the invention, said command means comprise a transistor command module and a second transistor comprising an input electrode connected to said command module, an output electrode connectable to the electrical ground and a further output electrode connectable to the input electrode of the first transistor.

According to an advantageous characteristic of the invention, said device comprises a resistor, one terminal of which is connected to the input electrode of the second transistor and the other terminal of which is connectable to the electrical ground.

According to an advantageous characteristic of the invention, since the device comprises a computer processing unit, said detection means are implemented in the form of computer instructions programmed in said unit.

According to an advantageous characteristic of the invention, the device comprises a converter configured to convert the voltage of the battery into a reduced voltage, and said detection means are configured to interpret said reduced voltage supplied by the converter.

According to an alternative embodiment of the invention, said detection means comprise a hysteresis comparator.

According to an advantageous characteristic of the invention, said energy storage element comprises one or more capacitors.

The invention also relates to an assembly for a vehicle, said vehicle comprising:

an electrical battery having a first terminal and a second terminal, an electrical energy storage element, one terminal of which is linked to the first terminal of the battery and the other terminal of which is linked to an electrical ground,

said assembly comprising:

a first circuit, capable of consuming electricity coming from the electrical battery, and having a first and a second terminal which are connectable to the first and second terminals of the electrical battery, respectively, electrical power supply management means configured to allow or prevent the passage of electrical current between said electrical energy storage element and said first circuit,

said assembly also comprising a second circuit connectable to the storage element so as to be able to be powered by said storage element,

characterized in that said assembly also comprises a controlling device as described above.

Preferentially, the second circuit comprises a computer processing unit and a memory in which said computer processing unit is capable of performing a write operation.

Advantageously, said assembly includes a third circuit connected to the energy storage element, said third circuit comprising a motor and a command module for said motor, and the second circuit comprises a controlling unit connected to the command module for said motor and configured, in the case of detection of a drop in voltage by said detection means, to transmit, to said command module, an order for shut down of said motor.

The invention will be clearly understood on reading the following description of an exemplary embodiment, with reference to the single FIGURE which is a diagram of the controlling device according to the invention associated with a battery and electrical and electronic circuits.

As stated above, the invention relates to a device 10 for controlling the electrical power supply of a circuit for a vehicle. Preferentially, said vehicle is a motor vehicle, such as a car. Said vehicle comprises an electrical and/or electronic installation 1 which comprises an electrical battery 2 and electrical and/or electronic circuits.

The electrical battery 2 has a first terminal VBAT, namely the positive terminal of the battery, and a second terminal −VBAT, namely the negative terminal of the battery.

The vehicle also comprises an electrical energy storage element, one terminal of which is linked to the first terminal VBAT and the other terminal of which is linked to an electrical ground. In the example illustrated in the FIGURES, the electrical energy storage element comprises a capacitor C 1 .

Said electrical or electronic circuits comprise elements capable of consuming electricity coming from the electrical battery 2 . Said circuits comprise, in particular, a first circuit 5 connected to the first and second terminals −VBAT, VBAT of the battery 2 . Said first circuit 5 comprises an element 51 capable of consuming electricity coming from the electrical battery 2 , for example an additional heating element or a lighting system.

The electrical and/or electronic installation 1 comprises electrical power supply management means configured to allow or prevent the passage of electrical current between said electrical energy storage element C 1 and said first circuit 5 .

In the example illustrated in the FIGURE, the electrical power supply management means comprise a first transistor Q 1 , called a battery reversing transistor.

As detailed hereafter, said electrical power supply management means Q 1 are commandable, during a drop in voltage of the battery below a given threshold value, so as to prevent the passage of electrical current between the electrical energy storage element C 1 and said first circuit 5 , i.e. such that the energy storage element C 1 cannot electrically power said at least one circuit 5 .

Said transistor Q 1 has an input electrode connected to the first terminal VBAT of the battery, via a resistor R 1 , an output electrode connected to the second terminal −VBAT of the battery, and a further output electrode connected to an electrical ground. The electrical ground can be included in the controlling device or in another part of the vehicle. By way of example, a resistor R 1 value equal to 10 kOhms can be chosen.

The first transistor Q 1 makes it possible to detect reverse mounting of the battery. Indeed, in the case of reversed connection of the terminals of the battery 2 , the voltage on the input electrode of the first transistor Q 1 is not sufficient to provide for the passage of current between the output electrodes of the first transistor Q 1 such that the first transistor Q 1 forms an open switch between the first circuit 5 and the capacitor C 1 which, therefore, cannot power the first circuit 5 . Conversely, when the battery is correctly connected, therefore when the first terminal VBAT is connected to the input of the first transistor Q 1 , via the resistor R 1 , the voltage to which it is subjected provides for the passage of current between the output electrodes of the first transistor Q 1 , which allows the first circuit 5 to be powered, if necessary, by the capacitor C 1 so as to be able to compensate, up to a certain level, for a voltage drop of the battery 2 .

The controlling device 10 makes it possible to control the first transistor Q 1 . Said controlling device 10 comprises detection means 41 configured to detect a drop in the voltage of the battery 2 below a threshold value, for example below 7 Volts.

Said controlling device 10 also comprises command means 42 configured, in the case of detection by the detection module 41 of a voltage of the battery 2 less than said threshold value, to command the off-state of the first transistor Q 1 , so as to prevent the first circuit 5 from being powered by discharging the capacitor C 1 .

Said command means 42 comprise a transistor command module 420 and a second transistor Q 2 . The second transistor Q 2 comprises an input electrode connected to said command module 420 , an output electrode connected to the electrical ground and a further output electrode connected to the input electrode of the first transistor Q 1 .

The command means 42 are arranged with the energy storage element C 1 in order to be able to be powered by said energy storage element C 1 in the case of a drop in voltage of the battery.

A resistor R 2 , for example of 10 kOhms, has a terminal connected to the input electrode of the second transistor Q 2 and a terminal connected to the electrical ground. This resistor R 2 thus makes it possible to keep by default, i.e. when there is no command of voltage in order to keep the second transistor Q 2 on, the input electrode at a defined potential close to the ground (0 Volts) and therefore to keep the second transistor Q 2 in the off-state.

Preferentially, the controlling device 10 comprises a computer processing unit 40 , used, for example, as a computer, and said detection means 41 are implemented in the form of a group of computer instructions, which group is saved and can be executed by the computer processing unit 40 . Advantageously, the computer processing unit 40 is a microcontroller or a microprocessor. The computer processing unit 40 also comprises means for transmitting an order signal to the command module 420 depending on the result of the detection. The order signal may be a binary signal: a signal at 0 to leave the second transistor Q 2 off and a signal at 1 to command the command module 420 to apply a voltage to the input electrode of the second transistor Q 2 such that it is on.

The device comprises a converter 3 connected to the battery and configured to convert the voltage of the battery 2 applied at the input of the converter into a reduced output voltage. The computer processing unit 40 comprises a terminal connected to the output of said converter 3 . Said detecting means 41 are configured to acquire the reduced output voltage of said converter 3 and detect whether the reduced output voltage corresponds to a drop in the battery voltage below said threshold value.

According to an alternative not illustrated in the FIGURES, said detection means can be implemented in the form of an electronic component or components separate from a computer processing unit. Thus, according to a particular embodiment, said detection means comprise a hysteresis comparator. Implementing the detection means using electronic components makes it possible to improve the responsiveness of the device compared to a computer solution.

The electrical and/or electronic installation comprises a second circuit 4 connected to the storage element so as to be able to be powered by the capacitor C 1 in the off-state of said first transistor Q 1 . Said command means 42 form part of this second circuit 4 . Thus, during normal operation, said command means 42 are powered by the battery and, in the case of a drop in voltage, they can, while continuing to be powered by the capacitor C 1 , command the off-state of the first transistor Q 1 so that the first circuit 5 does not consume the energy of the capacitor C 1 .

In the example illustrated in the FIGURE, said assembly includes a third circuit 6 connected to the energy storage element C 1 in order to be able to be powered by said energy storage element. Said third circuit 6 comprises an electrical motor 62 and a command module 61 for said motor 62 . Said motor is, for example, the drive motor for a fan mounted in a housing of a heating, ventilation and/or air conditioning (called HVAC) set.

The second circuit 4 comprises a controlling unit, preferably formed by the computer processing unit 40 , connected to the command module 61 for said motor 62 and configured, in the case of detection of a drop in voltage by said detection means, to transmit, to said command module 61 , an order for shut down of said motor 62 .

Thus, in the case of an excessive drop in voltage of the battery, the second circuit 4 , which comprises said command means 42 , continues to be powered by the capacitor so as to make it possible, firstly, to command the opening of the switch formed by the first transistor Q 1 in order to isolate the second circuit 5 from the capacitor C 1 , and, secondly, to command the shut down of the motor 62 via the transmission of an order to the command module 61 thereof. Thus, the first and third circuits 5 , 6 do not consume the energy of the capacitor C 1 , which energy can be reserved for the operation of another circuit, in particular for the operation of the computer processing unit 40 of the second circuit 4 in order to enable it to complete a memory write operation. Said memory is, for example, an electrically-erasable programmable read-only memory, also called an EEPROM.

Although at least one embodiment of the invention has been illustrated and described, it should be noted that other modifications, substitutions and alternatives become apparent to a person skilled in the art and can be changed without departing from the scope of the subject matter described herein.

The present application envisages covering all the adjustments and variations of the embodiments described above. Moreover, the word “comprising” does not exclude other elements or steps and the term “a” does not exclude the plural. Furthermore, characteristics or steps which have been described with reference to one of the embodiments set forth above may also be used in combination with other characteristics or steps of other embodiments set forth above. It will be noted that it is necessary to include, in the scope of the patent, all the modifications envisaged above insofar as they form part of the contribution of the inventors to the prior art. Such modifications, substitutions and alternatives can be carried out without departing from the scope and the spirit of the present invention.