METHOD FOR REGULATING THE OUTPUT VOLTAGE OF A DC-DC VOLTAGE CONVERTER IN A MOTOR VEHICLE

Abstract

The invention relates to a method for regulating the output voltage (Ureg) of a DC-DC converter in a motor vehicle, characterized in that said method comprises a step of measuring the temperature of the 48V traction battery (BT) by said temperature sensor (CT); a step of determining a setpoint (Cs) by the battery voltage control unit (BVCU), said setpoint (Cs) being the appropriate output voltage (Ureg) value for the 12V battery (B12V) as a function of the temperature (Tbat) measured during said measurement step, said setpoint (Cs) being transmitted to the on-board charger (OBC); and a step of regulating the output voltage (Ureg) transmitted by said on-board charger (OBC) to said 12V battery (B12V), said output voltage (Ureg) being equal to the setpoint (Cs). Figure 1

Description

Title of the invention: METHOD FOR REGULATING THE OUTPUT VOLTAGE OF A DC-DC VOLTAGE CONVERTER IN A MOTOR VEHICLE

[0001] The invention relates to the management of 12V batteries in motor vehicles.

[0002] Prior art patent application CN113054288, which describes a method for heating a vehicle battery, is known. The vehicle comprises a heating module, a DC-DC converter module, and a battery. The DC-DC converter module amplifies a first direct current supplied by the battery to obtain a second direct current. The second direct current is supplied to the heating module to heat the battery. The second direct current can be amplified to form a third direct current. The DC-DC converter module enters a voltage reduction mode when the battery temperature exceeds a threshold value. In reduction mode, the DC-DC converter module controls the reduction of the third direct current to obtain the first direct current. The first direct current is a low-voltage current, while the third direct current is a high-voltage current.However, one drawback remains. The reduction mode is activated when the temperature exceeds a single threshold value. Thus, the current is not actually adjusted according to the battery temperature, but only in the event of overheating. This is likely to reduce the battery's performance and, in the long term, damage it.

[0003] The objective of the present invention is to remedy these drawbacks and to improve the performance, safety and lifespan of the 12V battery.

[0004] To achieve this objective, the invention proposes a method for regulating the output voltage of a DC-DC voltage converter of a motor vehicle, said vehicle comprising a 12V battery, a 48V traction battery and a battery voltage control unit, said 48V traction battery comprising a temperature sensor, said DC-DC voltage converter comprising an on-board charger, notable in that said method comprises the following steps: - a step of measuring the temperature of the 48V traction battery by said temperature sensor, the measured temperature being transmitted to the battery management system, said temperature being transmitted by the battery management system to the battery voltage control unit; - a step of determining a setpoint by the battery voltage control unit, said setpoint being the appropriate output voltage value to recharge the 12V battery according to the temperature measured during said measurement step, said setpoint being transmitted to the on-board charger; - a step of regulating the output voltage emitted by said on-board charger to said 12V battery, said output voltage being equal to the setpoint.

[0005] Thanks to the invention, the voltage for recharging the 12V battery is adapted so as to prolong its lifespan and improve its performance.

[0006] Preferably, the 12V battery has a autonomy corresponding to a duration during which said 12V battery can supply electrical energy before requiring a recharge, said method comprising a step of emitting a cut-off alert when said duration is equal to a predetermined threshold value.

[0007] Advantageously, said predetermined threshold value is equal to 2 hours and 10 minutes.

[0008] Advantageously, during said determination step, said setpoint is between 14V and 15.2V.

[0009] Advantageously, said 12V battery has a capacity of 4 amp-hours.

[0010] Thus, the 12V battery is undersized compared to conventional 12V batteries. This helps to reduce the overall weight of the vehicle.

[0011] Furthermore, the invention relates to a computer program comprising instructions which, when the program is executed by a computer, lead the latter to implement the steps of the method of regulating the output voltage of a DC-DC voltage converter of a motor vehicle previously described.

[0012] The invention also relates to a motor vehicle comprising a computer configured to implement the method of regulating the output voltage of a DC-DC voltage converter of a motor vehicle previously described.

[0013] The invention will be further detailed by describing non-limiting embodiments, and based on the accompanying figures illustrating variants of the invention, in which: - [Fig.l] schematically illustrates the interactions between the components of a motor vehicle to implement a method of regulating an output voltage of a DC / DC voltage converter; - [Fig.2] illustrates, in tabular form, the appropriate output voltage in function of the temperature of the 48V traction battery.

[0014] The invention relates to a method for regulating an output voltage Ureg of a DC / DC direct-direct voltage converter of a motor vehicle. The vehicle includes a 12V B12V battery, a 48V BT traction battery, a battery management system (BMS), and a battery voltage control unit (BVCU). The 12V B12V battery's primary function in any type of motor vehicle is to power the headlights, infotainment system, electrical safety devices, and heating and ventilation systems. Preferably, the 12V B12V battery has a capacity of 4 amp-hours, allowing for a smaller battery size. This saves space and reduces the vehicle's overall weight. In the case of a motor vehicle with an internal combustion engine, the 12V battery provides the energy needed to power the starter motor, thus starting the engine.In the case of an electric or hybrid vehicle with a traction battery, the 12V battery is essential for maintaining safety functions, including controlling the battery management system (BMS) when the vehicle is off or in the event of a traction battery failure. The BMS is a crucial component for monitoring, protecting, and optimizing the use of the 48V BT traction battery. This improves the lifespan, safety, and performance of the 12V B12V battery. The 12V B12V battery consists of at least one module containing multiple electrochemical cells. The battery voltage control unit (BVCU) monitors the voltage of each module or electrochemical cell to prevent any one module or cell from exhibiting a significant charge difference compared to the others.A DC-DC converter is an electronic device that converts a first DC voltage into a second DC voltage, the second DC voltage being different from the first. The second DC voltage is either higher or lower than the first DC voltage. The DC-DC converter includes an onboard charger configured to convert electrical energy from an external source into electrical energy usable by the 12V battery.

[0015] The method comprises a plurality of steps. In a measurement step, the temperature Tbat of the 48V BT traction battery is measured by the temperature sensor CT. As illustrated in [Fig. 1], the temperature Tbat of the 48V BT traction battery is then transmitted to the battery management system (BMS), which redirects the information to the battery voltage control unit (BVCU). In a determination step, a setpoint Cs corresponding to the appropriate output voltage value Ureg is determined by the battery voltage control unit (BVCU). The appropriate output voltage value Ureg is the voltage value that allows for optimal performance of said battery as a function of the The temperature Tbat is the setpoint. Preferably, the setpoint Cs is between 14V and 15.2V. Figure 2 illustrates, in tabular form, the appropriate output voltage Ureg as a function of the temperature Tbat of the 48V BT traction battery. For example, when the 48V BT traction battery has a temperature of 40°C, the appropriate output voltage Ureg for charging the 12V B12V battery is 14.3V. The on-board charger (OBC) determines the appropriate output voltage Ureg and delivers an electrical current at that voltage to the 12V B12V battery. The setpoint Cs is transmitted to the OBC. During a regulation step, the OBC adjusts the output voltage Ureg to a value equal to the setpoint Cs to charge the 12V B12V battery.

[0016] The invention also relates to a computer program configured to implement said method for regulating the output voltage Ureg of a DC / DC converter in a motor vehicle. Furthermore, the invention relates to a motor vehicle comprising a computer configured to implement said method described above.

Claims

Demands

1. Method for regulating an output voltage (Ureg) of a DC / DC voltage converter of a motor vehicle, said vehicle comprising a 12V battery (B 12V), a 48V traction battery (BT) and a battery voltage control unit (BVCU), said 48V traction battery (BT) comprising a temperature sensor (CT), said DC / DC voltage converter comprising an on-board charger (OBC), characterized in that said method comprises the following steps: - a step of measuring the temperature of the 48V traction battery (BT) by said temperature sensor (CT), the measured temperature (Tbat) being transmitted to the battery management system (BMS), said temperature (Tbat) being transmitted by the battery management system (BMS) to the battery voltage control unit (BVCU);- a step of determining a setpoint (Cs) by the battery voltage control unit (BVCU), said setpoint (Cs) being the appropriate output voltage value (Ureg) to recharge the 12V battery (B 12V) as a function of the temperature (Tbat) measured during said measurement step, said setpoint (Cs) being transmitted to the on-board charger (OBC); - a step of regulating the output voltage (Ureg) emitted by said on-board charger (OBC) to said 12V battery (B 12V), said output voltage (Ureg) being equal to the setpoint (Cs).

2. Method according to claim 1 characterized in that, during said determination step, said setpoint (Cs) is between 14V and 15.2V.

3. Method according to claim 1 or 2 characterized in that said 12V battery (B 12V) has a capacity of 4 ampere-hours.

4. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the steps of the method for regulating the output voltage (Ureg) of a DC-DC voltage converter of a motor vehicle according to any one of claims 1 to 3.

5. Motor vehicle comprising a computer configured to implement the output voltage regulation (Ureg) method of a DC-DC voltage converter according to any one of claims 1 to 3.