Vehicle comprising a rechargeable battery and means for determining a maximum allowed power for the battery during a charging phase - Patents.com

Abstract

The system for supplying power to a rechargeable storage battery for a motor vehicle driven by an electric or hybrid powertrain includes a first maximum power (BATPIN POWERMAP (t)) and the second maximum power corresponding to the battery charging phase (BATPCHG POWERMAP The device further comprises means for determining a maximum allowed power for the battery (BATPIN(t)), the maximum allowed power for the battery being dependent on BATPIN(t) and the

Description

[Technical field]

[0001] The subject of the present invention is an electric battery management system, in particular an on-board electric battery management system adapted to power an electric or hybrid motor vehicle. [Background technology]

[0002] Motor vehicle batteries can be recharged either at an electric station when the vehicle is stationary, or by using an electric motor to recover some of the kinetic energy from the vehicle as it decelerates. Recovering energy in this manner is commonly referred to as regenerative braking.

[0003] Batteries can degrade or age, which reduces the battery's capacity to store energy, and this aging is dependent on the conditions under which the battery is used when the vehicle is running.

[0004] In order to preserve the integrity of the battery, it has been proposed to limit the charging power of the battery.

[0005] This limitation becomes even more important when the battery has a high state of charge.

[0006] The charge capacity will gradually decrease towards 0 as the battery approaches full charge.

[0007] The same is true when the battery temperature generally falls below 0°C.

[0008] Furthermore, when the charging power exceeds a certain threshold that depends at least on the battery cell chemistry and battery cell dimensions, the battery loses its integrity.

[0009] Furthermore, if the battery is made of lithium ion, it has been observed that if the charging power is too high, a lithium layer will be deposited on the battery electrodes. To limit this phenomenon, the charging capacity of the battery is greatly reduced.

[0010] Therefore, manufacturers of such batteries provide maps indicating the maximum permissible power for a battery as a function of the battery's state of charge and its temperature during the phase of charging by a power supply station.

[0011] The battery may further be recharged during the running phase, during the braking phase, or when the foot is lifted, known as the regeneration phase.

[0012] The maximum allowable power is now higher, however, it can only be applied for a shorter duration, such as 10 seconds, in order not to damage the battery.

[0013] Therefore, manufacturers have developed a second map of the maximum allowable power for the battery depending on the temperature of the battery during the regeneration phase and on the state of charge of the battery.

[0014] However, if the regeneration phase proves to be longer than the duration defined by said second map, the battery is likely to be damaged.

[0015] Therefore, a so-called modulation strategy, described in reference FR 2 994 027, is implemented by the Battery Management System (BMS) in order to gradually limit the amount of power given to the battery.

[0016] Such a strategy consists in limiting the maximum allowed power at each time instant during the regeneration phase depending on both a value read from a first map of maximum allowed power values ​​during the charging phase and a value read from a second map of maximum allowed power values ​​during the regeneration phase.

[0017] In other words, it is a case of gradually switching from limiting the maximum allowed power value resulting from the second map to limiting the maximum allowed power value read from the first map.

[0018] Incidentally, this strategy is only used during the regeneration phase, never during the charging phase.

[0019] Thus, the battery is deprived of high charging power and if this is allowed for a predefined period of time, the battery is not damaged, so that the charging potential of the battery during the charging phase is only partially utilized.

[0020] It is therefore an object of the present invention to improve the power supply system for motor vehicle batteries during a charging phase. Summary of the Invention

[0021] In view of the above, the subject of the present invention is a power supply system for a rechargeable storage battery for an electric or hybrid motor vehicle, the battery being able to be recharged during a regeneration phase and during a charging phase, the system comprising means for determining the maximum permissible power for the battery.

[0022] The means for determining a maximum allowed power for the battery comprises a first map enabling a first maximum power to be read from the temperature of the battery and from the state of charge of the battery, a second map enabling a second maximum power to be read from the temperature of the battery and from the state of charge of the battery, the first map comprising a first maximum power value corresponding to a regeneration phase and the second map comprising a second maximum power value corresponding to a battery charging phase, and calculation means for calculating said maximum allowed power for the battery during the charging phase as a function of the first maximum power and the second maximum power.

[0023] In other words, the calculation means is configured to utilize the first map and the second map to implement the modulation strategy during the battery charging phase.

[0024] The modulation strategy therefore makes it possible to gradually increase the charging power until it reaches a first maximum allowed charging power value resulting from the first map and corresponding to the state of charge and temperature of the battery at time t.

[0025] Thus, at an equivalent temperature and charging state, the first maximum allowable charging power value is greater than a corresponding second maximum charging power value resulting from the second map.

[0026] The change in the maximum allowed charging power then substantially follows the value resulting from the first map for a predetermined duration and then gradually decreases to a second maximum power value resulting from the second map.

[0027] Finally, once the maximum allowed power reaches the second value, the maximum allowed power will substantially conform to the maximum power value indicated in the second map as charging occurs.

[0028] Advantageously, the calculation means are configured to calculate the sum of a first power assigned a first coefficient α(t) between 0 and 1 and a second power assigned a second coefficient equal to 1-α(t).

[0029] The first coefficient α(t) is selected to obtain a limit chosen between a first maximum power (if the coefficient is equal to 1), a second maximum power (if the coefficient is equal to 0), and a weighting of these two powers if the coefficient is between 0 and 1.

[0030] Preferably, the calculation means is configured to adjust the value of the first power so that it is below the predetermined threshold when the first coefficient α(t) is equal to one.

[0031] Battery durability is affected when there is a significant difference between the first and second charging powers at equivalent temperature and charging states.

[0032] It is therefore proposed to keep the maximum allowed charging power value smaller than or equal to said predefined threshold value.

[0033] Preferably, the calculation means is configured to keep the first coefficient α(t) at 1 for a predetermined duration.

[0034] In other words, it is the case when calculating the maximum allowed power for a battery depending only on a first maximum power for the predetermined duration.

[0035] Advantageously, the battery is composed of one or several cells, and the system comprises means for measuring the voltage across the terminals of the cell and means for limiting the maximum allowed power for the battery subject to a third maximum power value calculated as a function of the maximum voltage value and the measured cell voltage.

[0036] Calculating a third maximum power value depending on these two parameters makes it possible to protect the battery.

[0037] Another subject of the invention is an electric or hybrid motor vehicle comprising a rechargeable storage battery, a braking system making it possible to recover energy, the battery being able to be recharged during regeneration phases and during charging phases, and a power supply system for said battery as defined above.

[0038] Another subject of the invention is a method for controlling the charging of a rechargeable storage battery of an electric or hybrid motor vehicle equipped with a braking system making it possible to recover energy, the battery being able to be recharged during regeneration phases and during charging phases.

[0039] The method includes determining a first maximum power corresponding to a regeneration phase, determining a second maximum power corresponding to a battery charging phase, and calculating a maximum allowed power for the battery during the charging phase according to the first maximum power and the second maximum power.

[0040] Advantageously, calculating the maximum allowed power comprises summing a first power assigned a first coefficient α(t) between 0 and 1 and a second power assigned a second coefficient equal to 1-α(t).

[0041] Preferably, the first power value is adjusted to be less than or equal to a predetermined threshold when a first coefficient α(t) is equal to one.

[0042] Preferably, the first coefficient α(t) is kept at 1 for a predetermined duration.

[0043] Advantageously, when the battery consists of one or several cells, the voltage across the terminals of the cell is measured and the maximum allowed power for the battery is limited on the basis of a third maximum power value calculated as a function of the maximum voltage value and the measured cell voltage.

[0044] Other objects, features and advantages of the present invention will become apparent on reading the following description, given purely by way of non-limiting example and with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0045] [Figure 1] 1A and 1B are a first map and a second map, respectively, including maximum power values ​​during a regeneration phase and a charging phase of a battery of a motor vehicle according to the prior art; [Diagram 2] FIG. 1 shows a schematic diagram of a power supply system 2 for a battery according to an embodiment of the present invention. [Figure 3A-3B] 4A and 4B are first and second graphs of the variation of the maximum allowed power for a battery during a charging phase according to two implementations of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] In the case of a motor vehicle battery with one or several individual cells, a maximum permitted power map can be generated, for example, by a map of the internal resistance of one battery cell.

[0047] These maps, which can be obtained by a preliminary calibration step, make it possible to read this resistance depending on the state of charge of the battery and its temperature.

[0048] The state of charge of a battery depends directly on the open circuit voltage (OCV) of the cell and can therefore be measured by a voltage sensor.

[0049] The maximum permissible voltage V for a cell through which current flows during the regeneration phase with energy recovery LimitPIN , and the maximum allowable voltage V for a cell through which current flows during the charging phase LimitPCHG can also be obtained by calibration.

[0050] Together these data make it possible to determine the maximum allowable power for the battery during the charging phase and during the regeneration phase according to Equation 1. TIFF2024529920000002.tif32170, where TIFF2024529920000003.tif14170

[0051] As shown in Figure 1, depending on the battery state of charge SOC expressed as a percentage A first map C1 can be formed that includes TIFF2024529920000004.tif6170.

[0052] FIG. 1 further illustrates the relationship between the state of charge (SOC) of the battery and the A second map C2 containing TIFF2024529920000005.tif6170 is shown.

[0053] Thus, at each time instant (labeled t), the maximum allowed power for the battery is obtained using Equation 2. BATPIN(t) = α(t) * BATPIN POWERMAP (t)+(1-α(t))*BATPCHG POWERMAP (t) Equation 2 Where: BATPIN(t): the maximum allowable power for the battery at time t BATPIN POWERMAP (t): the first maximum allowable power during the regeneration phase at time t obtained on the first map C1 BATPCHG POWERMAP (t): A second maximum allowable power during the charging phase at time t obtained on the second map C2 α(t): the first coefficient between 0 and 1

[0054] Therefore, if the first coefficient α(t) is equal to 1, the maximum allowable power for the battery BATPIN(t) is the first maximum allowable power BATPIN POWERMAP (t), which is a high value.

[0055] In contrast, if the first coefficient α(t) is equal to 0, the maximum allowed power for the battery BATPIN(t) is equal to the second maximum allowed power during the charging phase BATPCHG POWERMAP (t), which is a low value and can be applied for a long time without damaging the battery.

[0056] FIG. 2 shows a power supply system 2 comprising means for determining the maximum allowed power BATPIN(t) during a battery charging phase.

[0057] Such means for determining the maximum allowed power BATPIN(t) is configured to calculate Equation 2.

[0058] On the one hand, the first maximum permitted power value BATPIN corresponds to the regeneration phase. POWERMAP(t), and on the other hand a second maximum allowable power value BATPCHG POWERMAP It is possible to use calculation or modulation means 5 arranged to give a value of the maximum allowed charging power BATPIN(t) for the battery by using a second map C2 containing (t).

[0059] Thus, as shown in FIG. 3A, a first solid curve V1 shows the variation of the maximum allowed charging power BATPIN(t) expressed in watts as a function of the battery's state of charge SOC or voltage for a given temperature.

[0060] The modulation strategy now makes it possible to gradually increase the maximum allowed charging power BATPIN(t) until it reaches a first charging power value P1, which results from a first map C1 and corresponds to a state of charge SOC at time t.

[0061] Thus, at an equivalent temperature and charging state, the first maximum allowable charging power value P1 is greater than the corresponding second maximum allowable charging power value P2 resulting from the second map C2.

[0062] The change in the maximum permitted charging power BATPIN(t) is then determined by the change in the value BATPIN(t) resulting from the first map C1 for a first predetermined duration D1. POWERMAP (t) and then gradually decreases to reach a third maximum power value P3 resulting from the second map C2.

[0063] By way of example, the first predetermined duration D1 is between 10 seconds and a few minutes.

[0064] Finally, as soon as the maximum permissible power BATPIN(t) reaches a third value P3, the latter is set to the second maximum power value BATPCHG(t) shown in the second map C2 when the battery charging is performed. POWERMAP (t)

[0065] Furthermore, the durability of the battery is evaluated by the first charging power BATPIN at equivalent temperature and state of charge SOC. POWERMAP (t) and the second charging power BATPCHG POWERMAP Note that this can be compromised when there is a significant difference between (t).

[0066] For example, the difference may be on the order of tens of kilowatts (kW).

[0067] Therefore, the calculation means 5 calculates the first maximum power BATPIN so as to be less than or equal to the predetermined threshold P4 when the coefficient α(t) is equal to 1. POWERMAP The value of (t) may be adjusted.

[0068] In this case, it is a second solid curve V2 which illustrates the variation of the maximum allowed charging power BATPIN(t) as a function of the state of charge SOC of the battery.

[0069] It should be noted that the modulation strategy can be applied to all temperature values.

[0070] As a variant, as shown in FIG. 3B, the calculation means 5 are configured to keep the coefficient α(t) at 1 for a second predetermined duration D2, between a few seconds and a few minutes, in order to protect the battery from high variability of the charging power BATPIN(t) during the charging phase.

[0071] Furthermore, the present invention is not limited to these embodiments and implementations, but encompasses all variations thereof.

[0072] The invention relates, for example, to applications equipped with batteries, where the ratio between the current and the charge capacity of the battery (C-rate) is greater than one.

Claims

1. A power supply system (2) for a rechargeable battery for an electric or hybrid motor vehicle, wherein the battery can be recharged during a regeneration phase and a charging phase, the system comprising means for determining a maximum allowable power (BATPIN(t)) for the battery, said means for determining said maximum allowable power for the battery, A first maximum power (BATPIN ＰＯＷＥＲＭＡＰ (t)) from the temperature of the battery and the state of charge (SOC) of the battery, a first map (C1) that enables reading, and a first maximum power value (BATPIN ＰＯＷＥＲＭＡＰ (t)) corresponding to the regeneration phase, the first map (C1) including A second maximum power (BATCHG ＰＯＷＥＲＭＡＰ (t)) that enables reading from the temperature of the battery and the state of charge (SOC) of the battery, the second map (C2) including a second maximum power value (BATCHG ＰＯＷＥＲＭＡＰ (t)) corresponding to the battery charging phase, and the second map (C2); said first maximum power (BATPIN ＰＯＷＥＲＭＡＰ (t)) and said second maximum power (BATCHG ＰＯＷＥＲＭＡＰ (t)), calculating means (5) for calculating said maximum allowable power (BATPIN(t)) for said battery during said charging phase characterized in that it comprises. Power supply system (2).

2. The calculation means (5) assigns a first maximum power (BATPIN ＰＯＷＥＲＭＡＰ (t)) with a first coefficient α(t) between 0 and 1, and a second maximum power (BATCHG ＰＯＷＥＲＭＡＰ (t)) with a second coefficient equal to 1-α(t), and calculates the sum thereof. The power supply system (2) according to claim 1, which is configured as such.

3. When the first coefficient α(t) is equal to 1, the calculation means (5) adjusts the value of the first maximum power (BATPIN ＰＯＷＥＲＭＡＰ (t)) so as to be equal to or less than a predetermined threshold value (P4). The power supply system (2) according to claim 2, which is configured as such.

4. The power supply system (2) according to claim 2, wherein the calculating means (5) is configured to keep the first coefficient α(t) equal to 1 for a predetermined duration (D2).

5. The battery is composed of one or several cells, and the system (2) comprises means for measuring the voltage across the terminals of the cell and means for limiting the maximum allowable power for the battery on condition of a third maximum power value calculated according to the maximum voltage value and the measured cell voltage. The power supply system (2) according to any one of claims 1 to 4.

6. An electric or hybrid motor vehicle comprising a rechargeable battery and a braking system capable of recovering energy, wherein the battery can be recharged during a regeneration phase and a charging phase, and further comprising the power supply system (2) for the battery according to any one of claims 1 to 4. Electric or hybrid motor vehicle.

7. A method for controlling the charging of a rechargeable battery of an electric or hybrid motor vehicle provided with a braking system capable of recovering energy, wherein the battery can be recharged during a regeneration phase and a charging phase, Step of determining a first maximum power (BATPIN ＰＯＷＥＲＭＡＰ (t)) corresponding to the regeneration phase, and Step of determining a second maximum power (BATPCHG ＰＯＷＥＲＭＡＰ (t)) corresponding to a battery charging phase ＰＯＷＥＲＭＡＰ and the maximum power of the first (BATPIN ＰＯＷＥＲＭＡＰ (t)) and the maximum power of the second (BATCHG ＰＯＷＥＲＭＡＰ (t)), calculating a maximum allowable power (BATPIN(t)) for the battery during the charging phase characterized in that it comprises. Method.

8. Calculating the maximum allowable power (BATPIN(t)) includes summing the first maximum power (BATPIN ＰＯＷＥＲＭＡＰ (t)) assigned a first coefficient α(t) between 0 and 1 and the second maximum power (BATCHG ＰＯＷＥＲＭＡＰ (t)) assigned a second coefficient equal to 1 - α(t). The method according to claim 7.

9. The first maximum power value (BATPIN ＰＯＷＥＲＭＡＰ (t)) is adjusted to be equal to or less than a predetermined threshold value (P4) when the first coefficient α(t) is equal to 1. The method according to claim 8.

10. The method according to claim 8, wherein the first coefficient α(t) is kept equal to 1 for a predetermined duration (D2).

11. When the battery is composed of one or several cells, the voltage across the terminals of the cell is measured, and the maximum allowable power for the battery is limited based on a third maximum power value calculated according to the maximum voltage value and the measured cell voltage. The method according to any one of claims 7 to 10.

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