Battery Management System

Abstract

To prevent a battery from being insufficiently charged by preventing it from being erroneously determined that the battery is fully charged. [Solution] The battery management system 1 of the present invention has a charge detection unit 51 that determines that the lead battery 20 is fully charged when the charging current of the lead battery 20 falls below a predetermined current value when the lead battery 20 is being charged with power supplied by the battery pack 10, a regulation unit 53 that stops or suppresses the supply of power from the battery pack 10 to the lead battery 20 when the charge detection unit 51 determines that the lead battery 20 is fully charged, and a supply control unit 52 that controls the charge detection unit 51 to prohibit the charge detection unit 51 from determining that the battery is fully charged when an electrical load 30 is operating.

Description

[Technical Field]

[0001] The present invention relates to a battery management system for a vehicle. [Background technology]

[0002] Conventionally, vehicles are equipped with batteries for driving electrical loads. Patent Document 1 discloses a hybrid vehicle in which a lead-acid battery and a battery pack are electrically connected so that power is supplied from the battery pack to the lead-acid battery. In the hybrid vehicle of Patent Document 1, when the charging current of the lead-acid battery becomes equal to or lower than the charging current corresponding to the lead-acid battery voltage after power is supplied from the battery pack to the lead-acid battery, it is determined that the lead-acid battery is fully charged, and the supply of power from the battery pack to the lead-acid battery is stopped. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-131404 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the hybrid vehicle of Patent Document 1, if an electrical load connected to the lead-acid battery is being driven while power is being supplied from the battery pack to the lead-acid battery, current flows from the battery pack to the electrical load as well as the lead-acid battery, reducing the charging current flowing to the lead-acid battery. As a result, the lead-acid battery may be erroneously determined to be fully charged when it is not, resulting in insufficient charging of the lead-acid battery and an inability to supply power to electrical loads such as an ECU that are powered by the lead-acid battery, which may make it difficult to drive the vehicle.

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to prevent the battery from being insufficiently charged by preventing the battery from being erroneously determined to be fully charged. [Means for solving the problem]

[0006] The present invention is a battery management system having a battery, an electrical load driven by power from the battery, and a supply unit that supplies power to charge the battery, characterized in that it has a charge detection means that determines that the battery is fully charged when the charging current of the battery becomes equal to or less than a predetermined current value when the battery is being charged with power supplied by the supply unit, a regulation means that stops or suppresses the supply of power from the supply unit to the battery when the charge detection means determines that the battery is fully charged, and a control means that controls the charge detection means to prohibit the charge detection means from determining that the battery is fully charged when the electrical load is operating. [Effects of the Invention]

[0007] According to the present invention, by preventing the battery from being erroneously determined to be fully charged, it is possible to prevent the battery from being insufficiently charged. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of the configuration of a battery management system. [Figure 2] FIG. 2 is a diagram illustrating an example of a functional configuration of a control device. [Figure 3] 10 is a flowchart illustrating an example of processing by a control device. [Figure 4] 10 is a timing chart when the control device processes the data. DETAILED DESCRIPTION OF THE INVENTION

[0009] A battery management system 1 according to the present invention includes a lead-acid battery 20, an electrical load 30 driven by power from the lead-acid battery 20, and a battery pack 10 that supplies power to charge the lead-acid battery 20. The battery management system 1 includes a charge detection unit 51 that determines that the lead-acid battery 20 is fully charged when the charging current of the lead-acid battery 20 becomes equal to or less than a predetermined current value while the lead-acid battery 20 is being charged with power supplied from the battery pack 10, a regulation unit 53 that stops or suppresses the supply of power from the battery pack 10 to the lead-acid battery 20 when the charge detection unit 51 determines that the lead-acid battery 20 is fully charged, and a supply control unit 52 that controls the charge detection unit 51 to prohibit the charge detection unit 51 from determining that the lead-acid battery 20 is fully charged when the electrical load 30 is operating. By prohibiting the full charge determination when the electrical load 30 is operating, the lead-acid battery 20 is not erroneously determined to be fully charged, thereby preventing the lead-acid battery 20 from being insufficiently charged. [Example]

[0010] A battery management system 1 according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing an example of the configuration of a battery management system 1. As shown in FIG. The battery management system 1 is provided in a vehicle in which a passenger rides. The vehicle in which the battery management system 1 is provided is, for example, an electric vehicle (EV), and is provided with devices that are provided in general electric vehicles, and illustrations and descriptions of these devices will be omitted as appropriate.

[0011] The battery management system 1 according to the embodiment includes a battery pack 10, a lead battery 20, an electric load 30, a DC / DC converter 40, a control device 50, and the like.

[0012] The battery pack 10 is a high-voltage battery and corresponds to an example of a supply unit. The battery pack 10 supplies power to an electric motor that serves as a drive source for the electric vehicle. The battery pack 10 also supplies power to charge the lead battery 20 and also supplies power to an electric load 30 when the charge rate of the lead battery 20 is low. Specifically, the battery pack 10 is configured by connecting in series a plurality of battery modules, each of which has a plurality of battery cells connected in series. However, the battery pack 10 is not limited to the configuration of the battery pack 10 as long as it is a supply unit that can supply power at a higher voltage than the lead battery 20.

[0013] The lead battery 20 is a low-voltage battery and corresponds to an example of a battery. When the charge rate of the lead battery 20 is high, the lead battery 20 supplies power to the electric load 30 to drive the electric load 30. The lead battery 20 is also electrically connected to the battery pack 10, and when the charge rate of the lead battery 20 is low, the lead battery 20 is charged by being supplied with power from the battery pack 10. Specifically, the lead battery 20 is configured using lead for the electrodes. However, the lead battery 20 is not limited to the configuration of the lead battery 20 as long as it can supply power at a lower voltage than the battery pack 10.

[0014] The electric loads 30 are various electronic devices provided in the electric vehicle. The electric loads 30 are driven by power supplied from the lead battery 20. When the charge rate of the lead battery 20 is low, the electric loads 30 are driven by power supplied from the battery pack 10. Specifically, the electrical load 30 is, for example, an audio device such as a car audio system, a headlight device, a power window device, an ECU, or the like.

[0015] The DC / DC converter 40 converts the voltage of the power supplied from the battery pack 10 to the lead battery 20 and the electrical load 30 from a high voltage to a low voltage. The timing at which the DC / DC converter 40 converts the power supplied to the lead battery 20 and the electrical load 30 from a high voltage to a low voltage is controlled by the control device 50.

[0016] The control device 50 controls the entire battery management system 1. The control device 50 is, for example, an ECU (Electronic Control Unit). The control device 50 has a hardware configuration including a CPU, a ROM, a RAM, etc. The ROM pre-stores programs and predetermined information for controlling the electric vehicle or each component of the battery management system 1. The RAM is a work memory that temporarily stores programs and data. The CPU reads out the programs stored in the ROM, expands them in the RAM, and executes them to control the entire battery management system 1. The control device 50 may be the same as an ECU that controls the electric vehicle, or may be different from the ECU that controls the electric vehicle. Furthermore, the control device 50 is not limited to being configured by a single ECU, but may be configured by multiple ECUs working together.

[0017] FIG. 2 is a diagram illustrating an example of the functional configuration of the control device 50. As shown in FIG. The control device 50 controls the DC / DC converter 40 based on the information measured by the sensor unit 60, thereby controlling the entire battery management system 1. Here, the sensor unit 60 includes a lead battery voltage sensor 61 that measures the voltage of the lead battery 20, a lead battery current sensor 62 that measures the current flowing toward the lead battery 20, a lead battery temperature sensor 63 that measures the temperature of the lead battery 20, a supply voltage sensor 64 that measures the voltage of the battery pack 10, a supply current sensor 65 that measures the current flowing from the battery pack 10, and a load current sensor 66 that measures the current flowing toward the electrical load 30.

[0018] The control device 50 includes a charge detection unit 51, a supply control unit 52, and a regulation unit 53. The charge detection unit 51 detects the charging rate as the charging state of the lead battery 20 and determines whether the lead battery 20 is fully charged. Specifically, the charge detection unit 51 can detect the charging rate of the lead battery 20 based on the voltage of the lead battery 20 measured by the lead battery voltage sensor 61, the current measured by the lead battery current sensor 62, and the temperature of the lead battery 20 measured by the lead battery temperature sensor 63. Furthermore, when the lead battery 20 is being charged with power supplied by the battery pack 10, the charge detection unit 51 determines that the lead battery 20 is fully charged when the current value of the charging current of the lead battery 20 becomes equal to or less than a full charge determination threshold (first predetermined current value).

[0019] Here, the charging current of the lead battery 20 refers to a current that flows toward the lead battery 20 when the lead battery 20 is being charged, and is measured by the lead battery current sensor 62. Specifically, the charging current of the lead battery 20 corresponds to a current that flows along arrow A shown in FIG. 1. When the lead battery 20 is being charged, the charging current decreases as the lead battery 20 becomes more fully charged. Therefore, when the current value of the charging current measured by the lead battery current sensor 62 is equal to or less than a full charge determination threshold value when the lead battery 20 is fully charged or nearly fully charged, it can be determined that the lead battery 20 is fully charged. The full charge determination threshold value can be calculated experimentally, empirically, or theoretically. Note that the full charge determination threshold value is not limited to a fixed value, and may be a value determined according to the voltage, temperature, etc. of the lead battery 20.

[0020] When the charging rate of the lead battery 20 is low, the supply control unit 52 controls the DC / DC converter 40 to convert the voltage of the power from the battery pack 10 from high to low and supply the power to the lead battery 20. Furthermore, when the charging rate of the lead battery 20 is low and the electrical load 30 is operating, the supply control unit 52 supplies power to the electrical load 30 in addition to the lead battery 20. By controlling the supply control unit 52 in this way, the lead battery 20 can be charged by being supplied with power, and when the electrical load 30 is operating, power can also be supplied to the electrical load 30.

[0021] When the lead battery 20 is fully charged, the regulating unit 53 controls to stop or suppress the power supplied from the battery pack 10 to the lead battery 20. Specifically, when the charge detecting unit 51 determines that the lead battery 20 is fully charged, the regulating unit 53 regulates to stop or suppress the power supply from the battery pack 10 to the lead battery 20 by causing the supply control unit 52 to prevent the DC / DC converter 40 from converting the voltage of the power supplied from the battery pack 10 to the lead battery 20 from a high voltage to a low voltage.

[0022] In this way, when the lead battery 20 is fully charged, the supply of power from the battery pack 10 to the lead battery 20 is stopped or suppressed, thereby suppressing the unnecessary supply of power from the battery pack 10 to the lead battery 20. Such a function of suppressing the unnecessary supply of power from the battery pack 10 to the lead battery 20 is called an electricity efficiency improvement function. That is, the regulating unit 53 executes the electricity efficiency improvement function when the lead battery 20 is fully charged.

[0023] In the battery management system 1 configured as described above, if the electrical load 30 is operating while power is being supplied from the battery pack 10 to the lead battery 20, current flows from the battery pack 10 to the electrical load 30 in addition to the lead battery 20, and the charging current flowing to the lead battery 20 becomes small. At this time, if no measures are taken, when the current value of the charging current of the lead battery 20 falls below the full charge determination threshold, the charge detection unit 51 will erroneously determine that the lead battery 20 is fully charged even though it is not, and the regulation unit 53 will execute the power efficiency improvement function, stopping or suppressing the supply of power to the lead battery 20, resulting in insufficient charging of the lead battery 20.

[0024] Therefore, the control device 50 of this embodiment controls the lead battery 20 to be prevented from being insufficiently charged by preventing it from being erroneously determined that the lead battery 20 is fully charged when the electrical load 30 is operating. The processing by the control device 50 of this embodiment will be described below with reference to the flowchart of Fig. 3. The flowchart of Fig. 3 starts when power is supplied from the battery pack 10 to the lead battery 20.

[0025] In S11, the supply control unit 52 determines whether the supply current of the battery pack 10 is equal to or greater than a full charge determination prohibition threshold (second predetermined current value). The full charge determination prohibition threshold is stored in the control device 50. This determination corresponds to a determination whether the electrical load 30 is operating. The supply current of the battery pack 10 is the current flowing from the battery pack 10 and is measured by the supply current sensor 65. Specifically, the supply current of the battery pack 10 corresponds to the current flowing along the arrow B shown in FIG. 1. The full charge determination prohibition threshold (second predetermined current value) is the maximum current value of the supply current flowing from the battery pack 10 when the lead battery 20 is being charged with the electrical load 30 not in operation. Therefore, when the supply current of the battery pack 10 is equal to or greater than the full charge determination prohibition threshold (second predetermined current value), this is because there is a current flowing toward the electrical load 30, and it can be determined that the electrical load 30 is in operation. On the other hand, when the supply current is smaller than the full charge determination prohibition threshold, i.e., when the electrical load 30 is not in operation, the process proceeds to S12.

[0026] In S12, the charge detection unit 51 determines whether the charging current of the lead battery 20 is equal to or less than the full charge determination threshold (first predetermined current value). This determination corresponds to determining whether the lead battery 20 is fully charged. As described above, when the charging current of the lead battery 20 is equal to or less than the full charge determination threshold (first predetermined current value), it can be determined that the lead battery 20 is fully charged. When the charging current is equal to or less than the full charge determination threshold, i.e., when it is determined that the lead battery 20 is fully charged, the process proceeds to S13. On the other hand, when the charging current is greater than the full charge determination threshold (first predetermined current value), i.e., when it is determined that the lead battery 20 is not fully charged, the process returns to S11, and charging of the lead battery 20 continues.

[0027] In S13, the charge detection unit 51 determines that the lead battery 20 is fully charged. In S14, the regulating unit 53 executes an electricity efficiency improvement function of stopping or suppressing the power supplied from the battery pack 10 to the lead battery 20. Specifically, when the charge detecting unit 51 determines that the lead battery 20 is fully charged, the regulating unit 53 regulates so as to stop or suppress the supply of power from the battery pack 10 to the lead battery 20 by preventing the supply control unit 52 from converting the voltage of the power supplied from the battery pack 10 to the lead battery 20 by the DC / DC converter 40 from a high voltage to a low voltage.

[0028] On the other hand, if the current value is equal to or greater than the full charge determination prohibition threshold (second predetermined current value) in S11, that is, if the electrical load 30 is being driven, the process proceeds to S15. In S15, the supply control unit 52 prohibits the charge detection unit 51 from determining whether the lead battery 20 is fully charged. That is, regardless of whether the charging current of the lead battery 20 is equal to or less than the full charge determination threshold (first predetermined current value), the charge detection unit 51 does not determine whether the lead battery 20 is fully charged. In S16, the regulating unit 53 stops the execution of the power efficiency improving function of stopping or suppressing the power supplied from the battery pack 10 to the lead battery 20. Therefore, the supply control unit 52 continues charging the lead battery 20.

[0029] When the process of S16 and the process of S14 are completed, the flowchart of Fig. 3 is terminated. Note that the flowchart of Fig. 3 is periodically executed while power is being supplied from the battery pack 10 to the lead battery 20. In this way, when the electrical load 30 is operating, the charging current decreases as the lead battery 20 becomes more fully charged, which may result in an erroneous determination that the lead battery 20 is fully charged. Therefore, by prohibiting the determination of whether the lead battery 20 is fully charged when the electrical load 30 is operating, it is possible to prevent erroneous determination. Furthermore, by not stopping or restricting the power supplied from the battery pack 10 to the lead battery 20 when the electrical load 30 is operating, the lead battery 20 continues to be charged, thereby preventing the lead battery 20 from being insufficiently charged.

[0030] FIG. 4 is a timing chart when the flowchart of FIG. 3 is executed. Fig. 4(a) shows the supply current of the battery pack 10, Fig. 4(b) shows the load current of the electrical load 30, Fig. 4(c) shows the charging current of the lead battery 20, Fig. 4(d) shows the charging determination of the lead battery 20, and Fig. 4(e) shows the power efficiency improvement function. The load current of the electrical load 30 corresponds to the current flowing along the arrow C shown in Fig. 1.

[0031] From time T0 to time T1 shown in Fig. 4, power is supplied from the battery pack 10 to the lead battery 20, and the lead battery 20 is being charged, so the supply current in Fig. 4(a) and the charging current in Fig. 4(c) gradually decrease. That is, the rates of change of the supply current and the charging current are negative.

[0032] From time T1 to time T2, power continues to be supplied from the battery pack 10 to the lead battery 20, and the load current of the electrical load 30 in Fig. 4(b) gradually increases, so that the supply current in Fig. 4(a) also gradually increases, i.e., the rate of change of the supply current changes to a positive value. On the other hand, the rate of change of the charging current in Fig. 4(c) becomes equal to or less than a predetermined rate of change from time T0 to time T1, but the charging current continues to decrease.

[0033] At time T2, the charging current in Fig. 4(c) becomes equal to or less than the full charge determination threshold (first predetermined current value), and the lead battery 20 is determined to be fully charged in Fig. 4(d), and the power efficiency improvement function is executed in Fig. 4(e). However, since the electric load 30 is driven in Fig. 4(b) and a load current is generated in the electric load 30, even after time T2, a portion of the electric power from the battery pack 10 is supplied to the lead battery 20, and the charging current in Fig. 4(c) continues to be generated.

[0034] Next, at time T3, the generated current in Fig. 4(a) gradually increases and reaches or exceeds the full charge determination prohibition threshold (second predetermined current value), and it is determined that the electric load 30 is being driven. Here, in this embodiment, when the charging current in Fig. 4(c) decreases and reaches the full charge determination threshold (first predetermined current value), it is possible that the electric load 30 is being driven, so in Fig. 4(d), determination of whether the lead battery 20 is fully charged is prohibited. Furthermore, in Fig. 4(e), the execution of the electric efficiency improvement function is stopped. Therefore, even if the lead battery 20 is not fully charged after time T3, power is supplied from the battery pack 10 to the lead battery 20 so that the charging current of Figure 4(c) continues to be generated, thereby preventing the lead battery 20 from being insufficiently charged.

[0035] 4(a) gradually increases and becomes equal to or greater than the full charge determination prohibition threshold (second predetermined current value), and thus it is determined that the electric load 30 is operating. However, this is not the only case. For example, when the rate of change of the supply current flowing from the battery pack 10 is positive, if the rate of change of the charging current of the lead battery 20 is equal to or less than a predetermined rate of change and the charging current of the lead battery 20 becomes the full charge determination threshold (first predetermined current value), that is, at time T2, it may be determined that the electric load 30 is operating, and determination of whether the lead battery 20 is fully charged or not may be prohibited.

[0036] As described above, the battery management system 1 of this embodiment includes the charge detection unit 51 that determines that the lead battery 20 is fully charged when the value of the charging current of the lead battery 20 becomes equal to or less than a predetermined current value (equal to or less than the full charge determination threshold) when the lead battery 20 is being charged with power supplied from the battery pack 10, the regulation unit 53 that stops or suppresses the supply of power from the battery pack 10 to the lead battery 20 when the charge detection unit 51 determines that the lead battery 20 is fully charged, and the supply control unit 52 that controls the charge detection unit 51 to prohibit the charge detection unit 51 from determining that the lead battery 20 is fully charged when the electrical load 30 is operating. By prohibiting the full charge determination when the electrical load 30 is operating, the lead battery 20 is not erroneously determined to be fully charged, and therefore insufficient charging of the lead battery 20 can be prevented.

[0037] In addition, in this embodiment, the maximum current value of the supply current flowing from the battery pack 10 when the lead battery 20 is being charged with the electrical load 30 not being driven is stored. When the current value of the supply current flowing from the battery pack 10 is equal to or greater than the maximum current value (equal to or greater than the full charge determination prohibition threshold), the supply control unit 52 determines that the electrical load 30 is being driven and prohibits the charge detection unit 51 from determining full charge. Therefore, it is possible to accurately identify situations where an erroneous determination may occur.

[0038] Furthermore, in this embodiment, when the rate of change of the supply current flowing from the battery pack 10 is positive, the supply control unit 52 determines that the electric load 30 is operating when the rate of change of the charging current of the lead battery 20 is equal to or less than a predetermined rate of change and the charging current of the lead battery 20 becomes equal to or less than a predetermined current value (equal to or less than the full charge determination threshold), and prohibits the charge detection unit 51 from determining full charge. Therefore, it is possible to accurately identify situations where an erroneous determination may occur.

[0039] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and modifications and the like are possible within the scope of the present invention.

[0040] In the above-described embodiment, the vehicle is an electric vehicle, but the vehicle may be a hybrid vehicle or an engine vehicle. If the vehicle is an engine vehicle, the battery pack 10 and the DC / DC converter 40 can be replaced with an alternator that generates electric power by driving the engine, and the present invention can be similarly applied. In this case, the alternator corresponds to an example of a supply unit. [Explanation of symbols]

[0041] 1: Battery management system 10: Battery pack (supply unit) 20: Lead battery (battery) 30: Electric load 40: DC / DC converter 50: Control device 51: Charging detection unit (charging detection means) 52: Supply control unit (control means) 53: Regulation unit (regulation means)

Claims

1. A battery management system including a battery, an electric load driven by power from the battery, and a supply unit that supplies power to charge the battery, a charge detection means for determining that the battery is fully charged when a charging current of the battery becomes equal to or less than a predetermined current value while the battery is being charged with the power supplied by the supply unit; a regulating means for halting or restricting the supply of power from the supply unit to the battery when the charge detecting means determines that the battery is fully charged; and a control means for controlling the charge detection means to prohibit the determination of full charge when the electric load is being driven.

2. a maximum current value of the supply current flowing from the supply unit when the battery is being charged in a state in which the electric load is not being driven is stored; The control means 2. The battery management system according to claim 1, wherein when the supply current flowing from the supply unit is equal to or greater than the maximum current value, it is determined that the electrical load is being driven, and control is performed so as to prohibit the charge detection means from determining whether the electrical load is fully charged.

3. The control means 3. The battery management system according to claim 1, wherein when the rate of change of the supply current flowing from the supply unit is positive, it is determined that the electric load is being driven when the rate of change of the charging current of the battery is equal to or less than a predetermined rate of change and the charging current of the battery becomes equal to or less than the predetermined current value, and the charge detection means is controlled to prohibit the determination of full charge by the charge detection means.

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