Battery activation of a vehicle's electrical power system via a pre-charge circuit

Abstract

The invention relates to an electrical power supply system (1) for a motor vehicle, the vehicle comprising an electrical power supply network (10), the power supply system (1) comprising a plurality of batteries (B1, B2, Bn), each battery (B1, B2, Bn) comprising: an electrical energy storage unit (S1, S2, Sn), a control unit (U1, U2, UN), a switching device (C1, C2, Cn), connected on one side to the energy storage unit (S1, S2, Sn) and intended to be connected on the other side to the electrical power supply network (10) of the vehicle, A pre-charge circuit (Cprec) connected in parallel with the switching device (C1, C2, Cn), The control unit (U1, U2, UN) being configured to control the activation and deactivation of the switching device (C1, C2, Cn) and of the pre-charge circuit (Cprec). Figure for the abridged version: Fig 1

Description

Title of the invention: Battery activation of a vehicle electrical power supply system by a pre-charging circuit Technical field

[0001] The invention relates to the field of hybrid or electric vehicles, in particular two-wheeled vehicles, and more precisely to an electrical power supply system, a method of activating a vehicle by the power supply system and a method of recharging the power supply system. Prior art

[0002] In a known manner, an electric or hybrid vehicle comprises a set of electrical power supply batteries, for example lithium-ion batteries, for supplying power to the vehicle's electrical network. The electrical network thus makes it possible to supply power to the vehicle's electrical equipment.

[0003] According to the example presented here, all batteries are independently connected to the electrical network. The batteries are connected in parallel.

[0004] It may happen that the batteries are not at the same state of charge, some batteries having been removed from the system to be charged and / or to be replaced by a battery having a different charge level. A problem thus persists in the case where several batteries are connected in parallel to the electrical network and their state of charge is different. This can create energy transfers from a more charged battery to a less charged battery, which can damage the batteries and the electrical circuits and components of the electrical equipment connected to the power network, such as for example the input capacitors or the connectors of the electrical equipment, which must then be replaced.

[0005] In order to overcome this problem, a switching device, commonly called a "switching box" by those skilled in the art, is added, connected on the one hand to each battery and on the other hand to the vehicle's electrical network. More specifically, the switching device comprises a set of contactors, each contactor being connected between a battery and the vehicle's electrical network. Closing a contactor therefore makes it possible to connect the corresponding battery to the electrical network. Thus, the battery is connected to the network and supplies the electrical power supply network. The expression used "activation of a battery" corresponds to the fact of connecting a battery to the electrical network, by closing the contactor. The switching device is therefore configured to activate or deactivate each battery so as to avoid connecting in parallel batteries whose state of charge is significantly different, and thus to avoid energy transfers between batteries.

[0006] However, this type of switching device adds constraints regarding integration into the vehicle. In addition, this device must be supplied with electrical energy. This also requires the addition of a power source for the switching device, as well as connectors and electrical power wires to connect the power source and the switching device.

[0007] There is therefore a need for a solution that can overcome, at least in part, the drawbacks described above. Statement of the invention

[0008] To this end, the invention relates to an electrical power supply system for a motor vehicle, the vehicle comprising an electrical power supply network, the power supply system comprising a plurality of batteries, each battery comprising: a. an electrical energy storage unit, b. a control unit, c. a switching device, connected on the one hand to the energy storage unit and intended to be connected on the other hand to the electrical power supply network of the vehicle, d. A pre-charging circuit connected in parallel with the switching device, the control unit being configured to control the activation and deactivation of the switching device and the pre-charging circuit, when a battery receives an ignition request in order to supply the electrical network, the control unit of said battery is configured to: a. Activate the precharge circuit of said battery having received an ignition request, b. Then, obtain the value of the so-called “discharge” current of said battery, said discharge current designating the current flowing between said battery and the power supply network: • If the value of the discharge current obtained is lower than a predefined activation threshold, deactivate the battery, • If the discharge current value is higher than the predefined activation threshold, connect the battery to the power supply network in order to supply the power supply network with electrical energy.

[0009] Thus, when several batteries connected in parallel receive an ignition request, the power system can itself understand which battery to activate in order to provide electrical energy to the power network.

[0010] Indeed, when several batteries are connected to the power supply network and the value of the output current of one of the batteries is negative, this means that said battery is not the most charged battery. However, the battery for which the The output current is positive and the battery is the most charged, and it is therefore this last battery which will be used first to supply the electricity supply network.

[0011] Advantageously, the battery is connected to the power supply network in order to supply the power supply network with electrical energy, via the switching device.

[0012] Preferably, according to the power supply system as presented, when a battery receives an ignition request in order for said battery to be recharged from the electrical supply network, the control unit of said battery is configured to: a. Activate the precharge circuit of said battery having received an ignition request, b. Then, obtain the value of the so-called “charging” current of said battery, said charging current designating the current flowing between the power supply network 10 and said battery: • If the value of the charging current obtained is lower than a predefined activation threshold, deactivate the battery, • If the charging current value is higher than the predefined activation threshold, connect the battery to the power supply network in order to recharge the battery from the voltage supplied by the power supply network.

[0013] Thus, when several batteries are connected in parallel in order to be recharged, the power supply system can itself activate the least charged battery first so that this battery is recharged first.

[0014] Preferably again, according to a first embodiment, for each battery of the power supply system presented previously: a. The load switch includes a MOSFET transistor, b. The discharge switch includes a MOSFET transistor, c. The load switch and the discharge switch are connected in so that: i. The source of the load switch is connected to that of the discharge switch, ii. The drain of the load switch is connected to the supply network, iii. The drain of the discharge switch is connected to the storage unit of energy.

[0015] Preferably, according to a second embodiment, for each battery of the power supply system presented previously: a. The charge switch includes a MOSFET transistor, b. The discharge switch includes a MOSFET transistor, c. The load switch and the discharge switch are connected in so that: i. The source of the load switch is connected to that of the discharge switch, ii. The drain of the load switch is connected to the energy storage unit, iii. The drain of the discharge switch is connected to the power supply network.

[0016] Thus, a switching module as presented previously according to the first embodiment and the second embodiment, is a known structure, simple to integrate into a vehicle. It is presented here the fact that a control unit integrated in each battery optimally controls this type of substantially known structure.

[0017] Advantageously, each precharge circuit comprises a precharge resistor and a precharge switch connected in series and the activation of the precharge circuit corresponds to the closing of the precharge switch.

[0018] The invention also relates to a motor vehicle comprising an electrical power supply system as presented previously.

[0019] The invention also relates to a method for supplying a motor vehicle supply network by a supply system as presented previously, for each request to switch on a battery in order to supply the supply network, said method comprising steps consisting of: a. Activate the precharge circuit of each battery that has received an ignition request, b. Then, obtain the value of the so-called “discharge” current of said battery, said discharge current designating the current flowing between said battery and the power supply network: • If the current value obtained is lower than a predefined activation threshold, deactivate the battery, • If the current value is higher than the predefined activation threshold, connect the battery to the power supply network in order to supply the power supply network with electrical energy.

[0020] Thus, when several batteries connected in parallel receive an ignition request, the power supply method makes it possible to select from among these batteries the most charged battery or batteries which are the batteries to be activated in order to supply electrical energy to the power supply network.

[0021] The invention also relates to a method for charging at least one battery of an electrical power supply system as presented previously, when a battery receives an ignition request so that said battery is recharged from the electrical network, the method comprises the steps of: a. Activate the precharge circuit of each battery that has received an ignition request, b. Then obtain the value of the so-called “charging” current of said battery, said charging current designating the current flowing between the supply network and said battery: i. If the value of the charging current obtained is lower than a predefined activation threshold, deactivate the battery, ii. If the charging current value is higher than the predefined activation threshold, connect the battery to the supply network in order to recharge the battery from the supply network.

[0022] The charging process thus makes it possible to activate the least charged battery first so that this battery is recharged first. Brief description of the drawings

[0023] Other characteristics and advantages of the invention will become apparent from reading the description which follows. This is purely illustrative and must be read in conjunction with the appended drawings in which:

[0024] [Fig.l] [Fig.l] is a schematic representation of a vehicle power supply system according to the invention.

[0025] [Fig.2] [Fig.2] is a schematic representation of one embodiment of a power supply system according to [Fig.l].

[0026] [Fig.3] [Fig.3] is a timing diagram representing the variation of the states of the first switch and the second switch of a device for switching a battery of a power supply system according to [Fig.l] or [Fig.2], according to a first case where the value of the discharge current Idischarge is lower than a predefined activation threshold.

[0027] [Fig.4] [Fig.4] is a timing diagram representing the variation of the states of the first switch and the second switch of a switching device of a battery of a power system according to [Fig.l] or [Fig.2], according to a second case where the value of the discharge current Idischarge is greater than a predefined activation threshold. Description of the embodiments

[0028] Vehicle

[0029] With reference to [Fig.l], an embodiment of the power supply system according to the invention will now be presented, mounted in a vehicle, and in particular a two-wheeled vehicle. The power supply system here makes it possible to implement functions which can be used in the context of BMS, for "Battery Monitoring System" or "Battery Management System" in English.

[0030] The vehicle comprises an electrical power supply network 10, in particular making it possible to power the electrical equipment mounted in the vehicle.

[0031] Power supply system 1

[0032] The power supply system comprises N batteries B1, B2, ..., Bn, n being a positive integer greater than or equal to 2.

[0033] More precisely, each battery Bl, B2, Bn comprises: a. an electrical energy storage unit SI, S2, Sn, b. a switching device Cl, C2, Cn, connected on the one hand to the energy storage unit SI, S2, Sn and intended to be connected on the other hand to the electrical supply network of the vehicle, c. A precharge circuit Cprec connected in parallel with the switching device Cl, C2, Cn, d. a control unit U1, U2, UN.

[0034] switching device Cl, C2, Cn

[0035] Each switching device C1, C2, Cn comprises a first switch called “charge” switch I1 and a second switch called “discharge” switch I2, connected in series.

[0036] According to an embodiment shown in [Fig. 2], the charge switch II and the discharge switch 12 each comprise a MOSFET transistor. The charge switch II and the discharge switch 12 may correspond to any other type of switches.

[0037] According to a first embodiment, the load switch II and the discharge switch 12 are connected so that: a. The source of the load switch II is connected to that of the discharge switch 12, b. The drain of the load switch II is connected to the power supply network 10, c. The drain of the discharge switch 12 is connected to the energy storage unit SI, S2, Sn.

[0038] As a reminder, each MOSFET transistor comprises an intrinsic diode.

[0039] According to a second embodiment, the charge switch II and the discharge switch 12 are connected so that: i. The source of the load switch II is connected to that of the discharge switch 12, ii. The drain of the load switch II is connected to the energy storage unit SI, S2, Sn, iii. The drain of the discharge switch 12 is connected to the supply network 10.

[0040] More precisely still, the first charging switch II is configured to: a. According to a so-called “closed” state, allow the energy storage unit SI, S2, Sn to charge from the electrical energy supplied by the power supply network 10, b. According to a so-called “open” state, prevent the current from moving from the power supply network 10 to the energy storage unit SI, S2, Sn.

[0041] Similarly, the second discharge switch 12 is configured to: a. In a so-called “closed” state, allowing the energy storage unit SI, S2, Sn to discharge and supply the electrical network 10 with electrical energy, b. In a so-called “open” state, preventing current from moving from the energy storage unit SI, S2, Sn to the power supply network 10.

[0042] Subsequently, the expression “the battery is activated” or “connect the battery B1, B2, Bn to the power supply network 10”, means that the first charge switch II and the second discharge switch 12 of said battery are closed.

[0043] Cprec precharge circuit:

[0044] Each precharge circuit Cprec comprises a precharge resistor Rp and a precharge switch Ip and the activation of the precharge circuit corresponds to the closing of the precharge switch Ip.

[0045] The precharge circuit Cprec of a battery Bl, B2, Bn is activated momentarily, for a predefined duration, for example 250 ms, when said corresponding battery must be activated and connected to the power supply network 10. In this way, the current supplied by said battery Bl, B2, Bn to the power supply network 10 is temporarily limited by the precharge resistor Rp. This makes it possible to protect the electrical equipment connected to the power supply network 10 and which will be powered from the power supply network 10, by temporarily limiting the current flowing from said battery Bl, B2, Bn to the power supply network 10.

[0046] Current measuring device

[0047] In addition, each battery B1, B2, Bn comprises a measuring device (not shown in the figures) for measuring the current i flowing between said battery B1, B2, Bn and the power supply network 10. For this purpose, the measuring device is in particular configured to measure the value of the current between the switching device C1, C2, Cn of said battery B1, B2, Bn and the power supply network 10 and / or between the switching device C1, C2, Cn and the energy storage unit S1, S2, Sn.

[0048] In the case where at least one battery Bl, B2, Bn supplies the power supply network 10, this means that the current flows from the at least one battery Bl, B2, Bn to the power supply network 10 in order to supply the power supply network 10. In this case, the current measured by the measuring device corresponds to a discharge current Idecharge.

[0049] Conversely, in the case where at least one battery B1, B2, Bn is powered by the power supply network 10, this means that the current flows from the power supply network 10 to the at least one battery B1, B2, Bn. The current measured by the measuring device corresponds to a charging current Icharge.

[0050] Control unit Ul, U2, UN

[0051] The control unit Ul, U2, UN is configured to control: a. activation and deactivation of the precharge circuit (Cprec), b. The load switch II and the discharge switch 12 of each switching device module Cl, C2, Cn.

[0052] Each battery B1, B2, Bn can receive an ignition request, issued for example by a charger (so that the battery recharges from the energy supplied by the charger) or by the consumer vehicle (so that said battery supplies electrical energy to the vehicle's power supply network). The charger can correspond to a charger on board the vehicle or external to the vehicle, and is electrically connected to the power supply network 10.

[0053] More precisely still, for each battery Bl, B2, Bn having received an ignition request in order to supply the electrical supply network 10, in other words an activation request, the control unit Ul, U2, UN of said battery Bl, B2, Bn is configured to: a. Activate the precharge circuit Cprec of each battery B1, B2, Bn having received an ignition request, b. Obtain the value of the so-called “discharge” current Idischarge of said battery B1, B2, Bn.

[0054] If the value of the discharge current obtained is lower than a predefined activation threshold, the control unit Ul, U2, UN of said battery Bl, B2, Bn is configured to deactivate the battery Bl, B2, Bn.

[0055] The activation threshold is for example defined at 0 amperes.

[0056] With reference to [Fig.3], a first case is shown where the value of the discharge current Idischarge is lower than the predefined activation threshold, itself defined at 0 amperes.

[0057] [Fig. 3] comprises four timing diagrams. The first timing diagram represents the variation of the activation command Cmd of the batteries B1, B2, Bn. The second timing diagram represents the variation of the state of the precharge switch Ip, the high level representing the closing of the precharge switch Ip and the low level representing the opening of the precharge switch Ip. The third timing diagram represents the variation of the discharge current Idischarge. Finally, the fourth timing diagram represents the variation of the state of the first switch II and the second switch I2, the high level representing the closing and the low level representing the opening.

[0058] More precisely, at a so-called "initial" instant t0, the control unit Ul, U2, UN receives an activation request to discharge the battery Bl, B2, Bn to which the control unit Ul, U2, UN belongs. It is therefore at this initial instant t0 that the control unit Ul, U2, UN commands the closing of the precharge switch Ip of the precharge circuit Cprec of said battery Bl, B2, Bn so that said discharge switch Ip is closed for a predefined duration (for example defined at 250 ms).

[0059] A first instant tl defines the instant at which the precharge duration has elapsed. In other words, at the first instant tl, the control unit Ul, U2, UN commands the opening of the precharge switch Ip.

[0060] Furthermore, at the first instant t1, the discharge current Idischarge is measured. The discharge current Idischarge is in particular measured by the measuring device. The value of the discharge current Idischarge is in this first case lower than the threshold, which means that the battery B1, B2, Bn receives current from another more charged battery and therefore does not correspond to the most charged battery. The control unit U1, U2, UN therefore does not control the closing of the first switch II and the second switch 12, in order to leave the battery deactivated.

[0061] If the value of the discharge current Idecharge is greater than the predefined activation threshold, the control unit Ul, U2, UN of said battery Bl, B2, Bn is configured to connect the battery Bl, B2, Bn to the power supply network 10 in order to supply the power supply network with electrical energy.

[0062] With reference to [Fig.4], the case is shown where the value of the discharge current Idischarge is greater than the activation threshold, itself defined at 0 amperes.

[0063] [Fig.4] comprises four timing diagrams. The first timing diagram represents the variation of the activation command Cmd of the batteries B1, B2, Bn. The second timing diagram represents the variation of the state of the precharge switch Ip, the high level representing the closing of the precharge switch Ip and the low level representing the opening of the precharge switch Ip. The third timing diagram represents the variation of the discharge current Idischarge. Finally, the fourth timing diagram represents the variation of the state of the first switch II and the second switch 12, the high level representing the closing and the low level representing the opening.

[0064] More precisely, at a so-called “initial” instant t0, the control unit Ul, U2, UN receives an activation request to discharge a battery Bl, B2, Bn. It is therefore at this initial instant t0 that the control unit Ul, U2, UN commands the closing of the discharge switch Ip of the precharge circuit Cprec of said battery Bl, B2, Bn for a predefined duration (for example defined at 250 ms).

[0065] When the precharge duration has elapsed, at a first instant t1, the current of discharge Idischarge is measured. The discharge current Idischarge is measured in particular by the measuring device installed in the vehicle. The value of the precharge current Iprecharge is in this second case higher than the threshold, which means that the battery Bl, B2, Bn is among the most charged in the vehicle. The control unit Ul, U2, UN therefore controls the closing of the first switch II and the second switch 12 so that the battery is activated and supplies a voltage to the supply network 10.

[0066] Furthermore, for each battery Bl, B2, Bn having received an ignition request so that said battery is powered by the electrical supply network 10 in order to be recharged, the control unit Ul, U2, UN of said battery Bl, B2, Bn is configured to: a. Activate the precharge circuit Cprec of each battery B1, B2, Bn having received an ignition request, b. Obtain the value of the so-called “charging” current of said battery Bl, B2, Bn.

[0067] If the value of the charging current Icharge obtained is lower than a predefined activation threshold, the control unit Ul, U2, UN of said battery Bl, B2, Bn is configured to deactivate the battery Bl, B2, Bn,

[0068] If the value of the charging current Icharge is greater than the predefined activation threshold, the control unit Ul, U2, UN of said battery Bl, B2, Bn is configured to connect the battery Bl, B2, Bn to the power supply network 10 in order to recharge the battery from the charger connected to the power supply network 10.

[0069] The invention also relates to a method for supplying a power supply network by at least one battery B1, B2, Bn of the power supply system 1 as presented previously and a method for charging at least one battery B1, B2, Bn of a power supply system 1 from the electrical energy of the network, each of the methods being implemented by the control unit U1, U2, UN as presented previously.

Claims

Claims

1. Electrical power supply system (1) for a motor vehicle, the vehicle comprising an electrical power supply network (10), the power supply system (10) comprising a plurality of batteries (Bl, B2, Bn), each battery (Bl, B2, Bn) comprising: a. an electrical energy storage unit (SI, S2, Sn), b. a control unit (U 1, U2, UN), c. a switching device (Cl, C2, Cn), connected on the one hand to the energy storage unit (SI, S2, Sn) and intended to be connected on the other hand to the electrical supply network (10) of the vehicle, each switching device (Cl, C2, Cn) comprises a first switch called "charge" (II) and a second switch called "discharge" (12) connected in series, each charge switch (II) comprises a MOSFET transistor, each discharge switch (12) comprises a MOSFET transistor, d. A precharge circuit (Cprec) connected in parallel with the switching device (Cl, C2, Cn), The control unit (Ul, U2, UN) being configured to control the activation and deactivation of the switching device (Cl, C2, Cn) and the precharging circuit (Cprec), When a battery (Bl, B2, Bn) receives an ignition request in order to supply the electrical supply network (10), the control unit (Ul, U2, UN) of said battery (Bl, B2, Bn) is configured to: - Activate the precharge circuit (Cprec) of said battery (Bl, B2, Bn) having received an ignition request, - Obtain the value of the so-called “discharge” current (Idecharge) of said battery (Bl, B2, Bn), said discharge current (Idecharge) designating the current circulating between said battery (Bl, B2, Bn) and the power supply network (10): • If the value of the discharge current (Idischarge) obtained is lower than a predefined activation threshold, deactivate the battery (Bl, B2, Bn), • If the discharge current value (Idischarge) is higher than the predefined activation threshold, connect

2.

3. the battery (Bl, B2, Bn) to the power supply network (10) in order to supply the power supply network (10) with electrical energy. Power supply system (1) according to the preceding claim wherein, when a battery (Bl, B2, Bn) receives an ignition request so that said battery is recharged from the electrical network (10), the control unit (Ul, U2, UN) of said battery (Bl, B2, Bn) is configured to: - Activate the precharge circuit (Cprec) of said battery (Bl, B2, Bn) having received an ignition request, - Obtain the value of the so-called “charging” current (Icharge) of said battery (Bl, B2, Bn), said charging current (Icharge) designating the current flowing between the power supply network (10) and said battery (Bl, B2, Bn): • If the value of the charging current (Icharge) obtained is lower than a predefined activation threshold, deactivate the battery (Bl, B2, Bn), • If the charging current value (Icharge) is higher than the predefined activation threshold, connect the battery (Bl, B2, Bn) to the power supply network (10) in order to recharge said battery (Bl, B2, Bn) from the voltage supplied by the power supply network (10). Power supply system (1) according to the preceding claim, in which, for each battery (Bl, B2, Bn): the charge switch (II) and the discharge switch (12) are connected so that: i. The source of the charge switch (II) is connected to that of the discharge switch (12), ii. The drain of the load switch (II) is connected to the supply network (10), iii. The drain of the discharge switch (12) is connected to the energy storage unit (SI, S2, Sn).

4. Power supply system (1) according to claim 2, wherein, for each battery (Bl, B2, Bn): the charge switch (II) and the discharge switch (12) are connected so that: i. The source of the charge switch (II) is connected to that of the discharge switch (12), ii. The drain of the charge switch (II) is connected to the energy storage unit (SI, S2, Sn), iii. The drain of the discharge switch (12) is connected to the power supply network (10).

5. Power supply system (1) according to any one of the preceding claims wherein, each precharge circuit (Cprec) comprises a precharge resistor (Rp) and a precharge switch (Ip) connected in series and the activation of the precharge circuit (Cprec) corresponds to the closing of the precharge switch (Ip).

6. Motor vehicle comprising an electrical power supply system (1) according to any one of the preceding claims.

7. Method for supplying a motor vehicle power supply network (10) by an electrical power supply system (1) according to any one of claims 1 to 5, for each ignition request of a battery (Bl, B2, Bn) in order to supply the power supply network (10), said method comprising steps consisting of: a. Activating the precharge circuit (Cprec) of each battery (B 1, B2, Bn) having received an ignition request, b.Obtain the value of the so-called “discharge” current (Idecharge) of said battery (Bl, B2, Bn), said discharge current (Idecharge) designating the current circulating between said battery (Bl, B2, Bn) and the power supply network (10): • If the value of the current obtained is lower than a predefined activation threshold, deactivate the battery (Bl, B2, Bn), • If the value of the current is higher than the predefined activation threshold, connect the battery (Bl, B2, Bn) to the power supply network (10) in order to supply the power supply network with electrical energy.

8. Method for charging at least one battery (Bl, B2, Bn) of an electrical power supply system (1) according to any one of claims 1 to 5, when a battery (Bl, B2, Bn) receives an ignition request so that said battery (Bl, B2, Bn) is recharged from the power supply network (10), the method comprises the steps of: a. Activate the precharge circuit (Cprec) of each battery (B 1, B2, Bn) having received an ignition request, b. Obtain the value of the so-called “charging” current (Icharge) of said battery (Bl, B2, Bn), said charging current (Icharge) designating the current flowing between the power supply network (10) and said battery (Bl, B2, Bn): i. If the value of the charging current obtained is lower than a predefined activation threshold, deactivate the battery (B1, B2, Bn), ii. If the charging current value (Icharge) is higher than the predefined activation threshold, connect the battery (Bl, B2, Bn) to the supply network (10) in order to recharge the battery (Bl, B2, Bn) from the supply network (10).

Images