WO2013121133A2

WO2013121133A2 - System for matching the voltage and current of a lithium ion battery, for an automotive vehicle

Info

Publication number: WO2013121133A2
Application number: PCT/FR2013/050268
Authority: WO
Inventors: Erwan Monnier
Original assignee: Peugeot Citroen Automobiles Sa
Priority date: 2012-02-16
Filing date: 2013-02-08
Publication date: 2013-08-22
Also published as: WO2013121133A3; FR2987191B1; FR2987191A1

Abstract

The invention relates to a system for matching the voltage and current of a lithium-ion battery (2) intended to supply electrical parts of an automotive vehicle, comprising a heat-engine starter (12), an alternator (14) and on-board network (8), characterized in that it also comprises an electrical circuit (10) placed between, on the one hand, the battery (2), and on the other hand, the starter (12) and the alternator (14), this circuit comprising resistors (R1, R2, R2'), and switches (K1, K2, K3, K2') establishing various connections in order to interpose certain resistors between the battery and the parts, depending on the operating modes of these parts.

Description

VOLTAGE AND CURRENT ADAPTATION SYSTEM FOR LITHIUM-ION BATTERY FOR MOTOR VEHICLE

The present invention relates to a voltage and current matching system for a battery of the onboard network of a motor vehicle, and a motor vehicle equipped with such an adaptation system.

Motor vehicles generally comprise lead batteries charged by an alternator, which are connected to the on-board network to supply the equipment of this network. Lead-acid batteries generally comprising a voltage of about 12V, are commonly used because they have a reduced cost. The vehicle networks may comprise a single battery, or several associated batteries, which will be called thereafter generally "battery".

A problem that arises is that lead batteries having a high mass, about 20 to 25 kg, are relatively heavy compared to the amount of electrical energy they store.

In addition, lead-acid batteries are, for the moment, derogated from the legislation of the European Commission which prohibits lead. This derogation could be removed one day, prohibiting the sale of these batteries, forcing manufacturers to provide alternatives.

Lithium-ion "Li-ion" batteries, including ferphosphate technology with a voltage level close to the current one by combining four cells in series, could replace lead-acid batteries. However, this type of battery poses, depending on the operating mode, and temperature, voltage and current problems that may be different from those of lead batteries.

Especially for start-ups at current temperatures, with an iron-phosphate battery the voltage is higher. This voltage is with a charged battery of the order of 13.4V, instead of 12.8V for the lead-acid battery, and the voltage drop is lower, which gives a greater power starting or restart of the engine, but a risk of reducing the life of the starter member.

For engine starts at cold temperatures, especially below 0 ° C, the internal resistance of this type of battery is higher than for lead-acid batteries, causing a voltage drop of the battery which, for a low voltage of this battery battery, can prevent the engine from starting.

Moreover, during running some organs of the dashboard may require in a mode of operation called "boost" a higher voltage, for example of the order of 14.2V. However, the battery with iron phosphate retains with a high load level, for example 90%, a large current acceptance may saturate the alternator that can not raise its voltage high enough.

To protect an electrical machine from current peaks, a known solution, presented in particular by the document GB-316436, comprises inductors and electric capacitors arranged in different ways on the stator circuit of this machine.

However this type of circuit is not suitable for the adaptation of a battery to iron phosphate on a circuit of an onboard network of a motor vehicle, intended to receive a lead battery.

The present invention is intended to avoid these disadvantages of the prior art.

It proposes for this purpose a voltage and current adaptation system for a lithium-ion battery, intended for the electrical equipment of a motor vehicle, comprising a heat engine starter, an alternator and an on-board electrical system connected to the battery, characterized in that it comprises an electric circuit arranged between firstly the battery, and secondly the starter and the alternator, this circuit comprising resistors, and switches establishing different connections to to intercalate certain resistances between the battery and the equipment, according to the modes of operation of this equipment.

An advantage of this voltage and current matching system is that with a simple circuit interposed between the battery on the one hand and the alternator and the starting means on the other hand, it is possible to correct the voltages and the currents of a lithium-ion battery, in order to use without modification the electrical equipment usually provided for lead-acid batteries.

The voltage and current matching system of the invention may further include one or more of the following features, which may be combined with each other.

Advantageously, the adaptation system comprises at least two possible links that can be alternately interposed between the battery and the starter, one comprising a low resistance and the other a higher resistance.

Advantageously, the links are arranged in parallel, each having a resistor, and a switch mounted in series to activate this resistance.

Advantageously, the voltage and current matching system comprises at least two possible links that can be alternately interposed between the battery and the alternator, at least one comprising a higher resistance.

Advantageously, some of the possible connections to the starter and to the alternator are common.

Advantageously, the voltage and current matching system incorporates at least some of the components of a protection device of a lithium-ion battery, comprising, starting from the positive terminal of the cells of this battery, a switch of protection upstream, then a downstream protection switch, each switch comprising a switch function having an internal diode arranged in parallel.

The downstream protection switch may have the low resistance arranged in series, to connect it between the battery and the starter. The downstream protection switch and its low resistance arranged in series, can receive in parallel the stronger resistance and its switch.

The upstream protection switch, can receive in parallel a stronger resistance and its switch.

Advantageously, the approximate values of the resistances are as follows, for a resistance which is low, I mOhms, for a resistance which is stronger, 6mOhms.

According to one embodiment, the voltage and current matching system is integrated at least partially in the battery.

According to another embodiment, some of the components of the voltage and current matching system are integrated in the starter.

The invention also relates to a motor vehicle equipped with a lithium-ion battery, intended for electrical equipment comprising a heat engine starter, an alternator and an onboard network, this vehicle having more than one system of voltage and current adaptation having any of the preceding features.

In particular, the battery may comprise cells using iron-phosphate technology.

The invention will be better understood and other features and advantages will appear more clearly on reading the following description given by way of example and without limitation, with reference to the accompanying drawings in which:

- Figures 1 to 3 show successively three electrical circuit diagrams for matching systems made according to the invention;

FIG. 4 shows a diagram of a lithium-ion battery comprising a protection device;

- Figure 5 shows a fourth circuit diagram, resulting from a pooling of a matching system with the battery protection device; FIGS. 6 to 10 show five graphs showing, as a function of time, for a lead-acid battery, and for a lithium-ion battery with the fourth electric circuit, voltages and intensities; and

- Figure 1 1 shows a fifth circuit diagram for an electrical adapter system.

FIG. 1 shows, for a motor vehicle, an iron phosphate battery 2, the negative terminal of which is directly connected firstly to the body of the body 4, and secondly to the earth of the power unit 6. The terminal positive battery 2 is directly connected to the vehicle's on-board network 8, comprising various accessories of the powertrain or the body, to supply power.

The positive terminal of the battery 2 is also connected by a first electrical circuit 10, to the starter 12 of the heat engine, and to the alternator 14 driven by this engine, which produces the charging electricity of this battery. Note that the starter 12 can be made according to the various known technologies, for example to perform cold starts of the engine, or automatically reboots after short stops.

The electrical circuit 10 comprises between the positive terminal of the battery 2 and the starter 12, a first link comprising a low resistance R1 arranged in series with a first switch K1, and a second link comprising a higher resistance R2 arranged in series with a second switch K2.

The electrical circuit 10 comprises between the positive terminal of the battery 2 and the alternator 14, a third link comprising only a switch K3, and a fourth link comprising a higher resistance R2 'disposed in series with a fourth switch K2'.

The orders of magnitude of the resistances are as follows, for the weak resistance R1, I mOhms, for the higher resistances R2, R2 ', 6mOhms. The switches K1, K2, Κ3, Κ2 'are controlled by a control and control electronics receiving various information on the operation of the vehicle and on the demands of the driver, who implements a control method according to the received information, for activate these switches which each connect a link.

The electrical circuit 10 can be included in various systems of the vehicle, in particular in the battery supervision electronics 2 which can be integrated in this battery or not, in order to achieve a compact and economical package.

The operation of the first electrical circuit 10 is as follows.

For starting the heat engine using the starter 12, the control method can close only the switch K2 to pass the intensity by the stronger resistance R2, and perform a voltage clipping by lowering the voltage delivered by the battery. In the case of charged batteries, then a voltage of 13.4V is passed for a battery with iron phosphate, a voltage called TO which is 12.8V for a lead battery.

The starter 12 then operating under normal conditions, does not involve any risk of premature wear.

For this start of the heat engine, the control method can alternatively close only the switch K1 to pass the intensity by the low resistance R1, which then gives a higher voltage called TO + x which is 13.4V, delivering exceptional way to the starter 12 a stronger power facilitating starting in difficult conditions, for example during cold periods.

For the simple recharging of the battery 2 by the alternator 14, the control method can close only the switch K3 to pass the charging current without additional resistance, so as to deliver the maximum power to the battery with iron-phosphate which can accept a strong current while its level of charge is high. The strong current usually saturates the alternator. In the case where it is desired to deliver to the on-board network 8 a higher voltage, for example to give the equipment of this network a higher power in the boost charging mode, or if one wants to equal power to reduce the intensity delivered to the equipment to preserve the life of this equipment, the control method can alternatively close only the switch K2 'to pass the intensity by the stronger resistance R2'. This reduces the charge current in the battery 2 and the risk of saturation of the alternator 14, the voltage delivered by the alternator can go up.

FIG. 2 shows alternatively for the same motor vehicle, a second electrical circuit 20 similar to the previous circuit 10, comprising between the positive terminal of the battery 2, and the starter 12 as well as the alternator 14 connected together, the first link comprising the low resistance R1 arranged in series with the first switch K1, the second link comprising the higher resistance R2 arranged in series with the second switch K2, and the third link comprising only the switch K3.

There is thus with a link less that which reduces the costs for starting the heat engine with the starter 12, as before, the choice to have in series only the low resistance R1, or the stronger resistance R2 for clipping. Of voltage.

We also have for the recharge of the battery 2 as before, the choice to have in series only the stronger resistance R2 which has the same value as the stronger resistance R2 'previous, for the recharge mode with boost, or not not use resistance with the K3 switch for single charging.

FIG. 3 shows alternatively for the same motor vehicle, a third electrical circuit 30 similar to the preceding circuit 20, comprising only between the positive terminal of the battery 2, and the starter 12 as well as the alternator 14 connected together, the first link comprising the low resistance R1 arranged in series with the first switch K1, and the second link comprising the higher resistance R2 arranged in series with the second switch K2.

There is thus with a link less that which further reduces the costs, for starting the heat engine with the starter 12, as previously, the choice to have in series only the low resistance R1, or the stronger resistance R2 for the voltage clipping.

We also have for the recharge of the battery 2 as before, the choice to have in series only the stronger resistance R2 for the boost mode with boost, or to have in series only the low resistance R1 for the single charging mode, this resistance R1 is weak enough to find almost a connection without resistance.

FIG. 4 shows a diagram of an iron phosphate battery 2 comprising four elementary cells which deliver a voltage of approximately 12V, and a protection device comprising, starting from the positive terminal of these cells, a protection switch called by upstream convention Kr, then a protection switch called downstream Kd. Advantageously, the protection device is integrated in the battery 2.

Each switch Kr, Kd typically consists of a power transistor of the MOS type, represented by a switch having an internal diode disposed in parallel with this switch.

There are four possible modes of operation. With the two protection switches Kr, Kd open, the battery is isolated. With the Kr switch open and the Kd switch closed, discharge is possible, and the battery is protected against excessive loads. With the Kr switch closed and the Kd switch open, charging is possible, and the battery is protected against excessive discharges. And with both Kr, Kd protection switches closed, the battery is fully functional for both charging and discharging.

Figure 5 shows a fourth electrical circuit 40, resulting from a pooling of the protection device with the voltage matching system described above. This diagram shows the two upstream protection switches Kr and downstream Kd connected in series, between the battery 2 on one side, and on the other side the starter 12 and the alternator 14 connected together. The low resistance R1 is added between the downstream switch Kd, and the connection to the starter 12 and the alternator 14. The edge network 8 is connected between the two protection switches Kr, Kd.

Between the battery 2 and the onboard network 8 there is a second upstream switch K2 'with its higher resistance R2' connected in series, which is arranged in parallel with the first upstream switch Kr.

And between the edge network 8, and the starter 12 and the alternator 14, there is a second downstream switch K2 with its higher resistance R2 connected in series, which is arranged in parallel with the first downstream switch Kd.

The operation of the fifth electrical circuit 50 is as follows.

With the two upstream switches Kr, K2 'open, and the two downstream switches Kd, K2 closed, discharge is possible, and the battery is protected against too high loads. With the two downstream switches Kd, K2 open, and the two upstream switches Kr, K2 'closed, the charging is possible, and the battery is protected against too strong discharges.

With the switches Kr, K2 and K2 'closed and the switch Kd open, there is the stronger resistor R2 in series in the case of the discharge, for voltage clipping to protect the starter 12. With the switches Kd, K2 and K2 'closed and the switch Kr open, there is the stronger resistance R2' in series in the case of the load, which provides the recharge mode with boost giving the network equipment a higher power.

FIGS. 6 and 7 show, as a function of the time t in seconds, respectively the currents I in Amperes and the voltages U in volts, currents consumed by the same starter 12 during a start of the engine, supplied by various means.

The lower curves at the beginning of the graphs 60, 70 respectively show the intensity and the voltage for a battery at lead, they are the reference values adapted to the starter 12, which was originally designed for this battery.

The highest curves at the beginning of the graphs 62, 72 respectively show the intensity and the voltage for a battery with iron-phosphate, without resistance in the circuit.

The curves 64, 74 which are at the beginning of the graphs slightly above the curves 60, 70, and at the end slightly below, present respectively the intensity and the voltage for a battery with iron-phosphate, with the stronger resistance R2 arranged in series in order to perform the voltage clipping which protects the starter 12. In this case one obtains curves very close to the reference values 60, 70, the starter 12 works under similar conditions.

FIGS. 8 and 9 show, as a function of time t in seconds, respectively the currents I in Amperes and the voltages U in Volts, currents produced by alternator 14 charging a lead-acid battery for curves 90 and 100, and currents charging an iron-phosphate battery for the curves 92 and 102. For the iron-phosphate battery, the setpoint voltage of the alternator 14 is 14.2V, and the intensity of the current is limited in absolute value to 180A. There is no additional resistance in the circuits, between the alternator 14 and the battery 2.

It is noted for the lead battery that the intensity of the current 90 rises to about 100A, and that the voltage 100 remains stable at 15.2V.

It is also noted for the iron-phosphate battery, that the intensity of the current 92 is well limited in absolute value at 180A, but that the voltage 102 does not exceed 13.7V. It is deduced that the iron-phosphate battery absorbs all the current produced, which saturates the alternator 14 and prevents to reach the required voltage of 14.2V. You can not perform a boost mode on the network 8.

FIG. 10 shows, as a function of the time t in seconds, the curve 1 12 of the intensity I in amperes of the current produced by the alternator 14 charging the battery with iron-phosphate 2, with a reference voltage of this alternator which is always 14.2V, and the stronger resistance R2 'arranged in series in the charging circuit.

It is found that the current is limited well below the maximum possible production of the alternator 14, in absolute value at about 1 10A. The alternator is not saturated, and its voltage can reach the setpoint of 14.2V which allows to obtain the boost mode on the onboard network.

FIG. 11 presents a fifth electrical circuit 120, which is simplified with respect to the fourth circuit 50 shown in FIG. 5. It comprises only one downstream switch Kd, the positive voltage for supplying the on-board network 8 being taken after this switch .

The resistors R1 and R2 are deported out of this fifth circuit 120, they can advantageously be integrated into the starter 12.

The adaptation system can be used advantageously with batteries comprising lithium-ion cells, using in particular iron-phosphate technology, but also with all types of electrochemical batteries requiring impedance adaptations. This facilitates the integration of lithium-ion batteries by limiting the modifications on the vehicle, including the starter and the alternator.

Moreover, by grouping the adaptation system with other circuits, such as that of the battery protection device, a compact and economical solution can be obtained.

Claims

1 - Voltage and current adaptation system for a lithium-ion battery (2) intended for the electrical equipment of a motor vehicle, comprising a starter (12) for a heat engine, an alternator (14) and a network board (8) connected to the battery (2), characterized in that it comprises an electric circuit (10, 20, 30, 50, 120) arranged between on the one hand the battery (2), and other the starter (12) and the alternator (14), this circuit comprising resistors (R1, R2, R2 '), and switches (K1, K2, K3, K2', Kr, Kd) establishing different links in order to interposing certain resistances between the battery and the equipment, according to the modes of operation of these equipments.

2 - voltage and current matching system according to claim 1, characterized in that it comprises at least two possible connections which can be alternately interposed between the battery (2) and the starter (12). one with a weak resistance (R1) and the other with a stronger resistance (R2).

3 - voltage and current matching system according to claim 2, characterized in that the links are arranged in parallel, each having a resistor (R1, R2), and a switch (K1, Kd, K2) connected in series. to activate this resistance.

4 - voltage and current matching system according to any one of the preceding claims, characterized in that it comprises at least two possible connections which can be alternately interposed between the battery (2) and the alternator (14) at least one having a stronger resistance (R2, R2 ').

5 - voltage and current matching system according to claims 2 or 3, and 4, characterized in that some of the possible connections to the starter (12) and to the alternator (14), are common.

6 - voltage and current matching system according to any one of the preceding claims, characterized in that it integrates at least some of the components of a protection device of a lithium-ion battery (2), having from the positive terminal of the cells of that battery, an upstream protection switch (Kr), then a protection switch downstream (Kd), each switch comprising a switch function having an internal diode arranged in parallel.

7 - voltage and current matching system according to claims 3 and 6, characterized in that the downstream protection switch (Kd) comprises the low resistance (R1) arranged in series, to connect it between the battery (2) and the starter (12).

8 - voltage and current matching system according to claim 7, characterized in that the downstream protection switch (Kd) and its low resistance (R1) arranged in series, receive in parallel the stronger resistance (R2) and its switch (K2).

9 - voltage and current matching system according to any one of claims 6 to 8, characterized in that the upstream protection switch (Kr), receives in parallel a stronger resistance (R2 ') and its switch ( Κ2 ').

10 - voltage and current matching system according to any one of the preceding claims, characterized in that the approximate values of the resistors are as follows, for a resistance which is low (R1), 1 mOhms, for a resistance which is stronger (R2, R2 '), 6mOhms.

1 1 - voltage and current matching system according to any one of the preceding claims, characterized in that it is integrated at least partially in the battery (2).

12 - voltage and current matching system according to any one of the preceding claims, characterized in that some of its components are integrated in the starter (12).

13 - Motor vehicle equipped with a lithium-ion battery (2) for electrical equipment comprising a starter (12) for a heat engine, an alternator (14) and an on-board network (8), characterized in that it further comprises a voltage and current matching system made according to any one of the preceding claims.

14 - Motor vehicle according to claim 13, characterized in that the battery comprises cells using iron-phosphate technology.