Battery management unit and power storage device

Abstract

To improve the accuracy of temperature measurement.SOLUTION: A battery management unit 53 includes: a shunt resistor 20; and a temperature measuring device 70 that measures a temperature in the vicinity of the shunt resistor 20. The temperature measuring device 70 includes: a diode 72 that is arranged in the vicinity of the shunt resistor 20; an amplifier circuit 80 that amplifies a forward voltage of the diode 72; and a control unit 90 that calculates the temperature in the vicinity of the shunt resistor 20 based on an output voltage of the amplifier circuit 80.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to a battery management unit and a power storage device. [Background technology]

[0002] Conventionally, a battery sensor device described in International Publication No. 2017 / 135024 (Patent Document 1 below) is known. The battery sensor device described in Patent Document 1 includes a sensor unit and a sensor substrate. The sensor unit includes a bus bar with resistor, a thermistor, and a casing that holds the bus bar with resistor. The bus bar with resistor is arranged in a power supply path of the battery. The bus bar with resistor includes a first bus bar, a second bus bar, and a shunt resistor arranged between the first bus bar and the second bus bar in the current flow direction. The thermistor detects the temperature around the bus bar with resistor. The thermistor is formed integrally with the casing. The sensor substrate is housed in the casing. The sensor substrate detects a current flowing through the shunt resistor, and generates battery information (SOC, SOH, etc.) based on the detected current and temperature information from the thermistor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2017 / 135024 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above configuration, the temperature around the resistor busbar is calculated based on the temperature characteristics of the thermistor resistance. Since the temperature characteristics of the thermistor resistance are not linear, the temperature is calculated based on table data that is created in advance and shows the correlation between the resistance and temperature. However, when the variation in the thermistor resistance is taken into account, the error between the measured resistance and the table data becomes large, and the temperature may not be calculated accurately. Furthermore, in a temperature range where the thermistor resistance varies only slightly, the accuracy of the temperature measurement may deteriorate. [Means for solving the problem]

[0005] The battery management unit of the present disclosure is a battery management unit that includes a shunt resistor and a temperature measuring device that measures the temperature in the vicinity of the shunt resistor, the temperature measuring device including a diode arranged in the vicinity of the shunt resistor, an amplifier circuit that amplifies the forward voltage of the diode, and a control unit that calculates the temperature in the vicinity of the shunt resistor based on the output voltage of the amplifier circuit. Effect of the Invention

[0006] According to the present disclosure, the accuracy of temperature measurement can be improved. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a conceptual diagram showing a simplified configuration of a battery in a vehicle system. [Diagram 2] FIG. 2 is an exploded perspective view showing an example of the configuration of a battery. [Diagram 3] FIG. 2 is a plan view of the shunt resistor according to the first embodiment. [Figure 4] FIG. 2 is an enlarged bottom view of the temperature measuring device according to the first embodiment. [Diagram 5] 5 is a cross-sectional view taken along line AA in FIG. 4. [Figure 6] FIG. 2 is a diagram showing the electrical configuration of the temperature measuring device according to the first embodiment. [Figure 7] FIG. 11 is an enlarged bottom view of the temperature measuring device according to the second embodiment. [Figure 8] 8 is a cross-sectional view of FIG. 7 taken along line B-B. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] (Outline of this embodiment) (1) A battery management unit disclosed herein includes a shunt resistor and a temperature measuring device that measures a temperature in the vicinity of the shunt resistor. The temperature measuring device includes a diode arranged in the vicinity of the shunt resistor, an amplifier circuit that amplifies a forward voltage of the diode, and a control unit that calculates the temperature in the vicinity of the shunt resistor based on the output voltage of the amplifier circuit.

[0009] The temperature characteristic of the forward voltage of the diode is linear, and the voltage fluctuation due to temperature change is approximately constant. Furthermore, the temperature is measured based on the output voltage obtained by amplifying the forward voltage of the diode by the amplifier circuit. Therefore, the above configuration can improve the accuracy of temperature measurement.

[0010] (2) In the battery management unit of (1) above, the control unit may turn off the power supply to the diode when the temperature is not being measured.

[0011] According to the above configuration, it is possible to suppress the power consumption of the diode and reduce heat generation of the diode.

[0012] (3) In the battery management unit of (1) or (2) above, the temperature measuring device may further include a substrate on which the diode, the amplifier circuit, and the control unit are mounted, and an opening is formed in the substrate so as to face the shunt resistor, and at least a portion of the diode may be disposed inside the opening.

[0013] According to the above configuration, by providing an opening in the substrate and arranging at least a part of the diode in the opening, the diode can be easily placed close to the shunt resistor. This can further improve the accuracy of temperature measurement. In addition, compared to a configuration in which the diode is placed on the substrate and placed close to the shunt resistor, the temperature measurement device can be made thinner.

[0014] (4) The energy storage device of the present disclosure includes a plurality of energy storage elements and any one of the battery management units described above in (1) to (3).

[0015] <Embodiment 1> 1. Battery Configuration 1, a battery 50 (an example of a power storage device) according to this embodiment is mounted on a vehicle such as a four-wheeled vehicle, a motorcycle, etc. The battery 50 according to this embodiment has a rated voltage of 12 volts (V).

[0016] A starting system 10A such as a starter, a vehicle charger 10B such as an alternator, and auxiliary devices 10C (headlights, car navigation system, etc.) mounted on the vehicle are connected to the battery 50. The battery 50 supplies 12V power to the starting system 10A to start the engine (internal combustion engine). The battery 50 is charged by the vehicle charger 10B while the engine is operating.

[0017] Alternatively, the battery 50 may be mounted on an electric vehicle (EV) or an electric motorcycle that does not have an engine. The battery 50 supplies 12V power to a starting system 10A for starting a high-voltage battery (main battery) for driving the vehicle, in place of a starter. The battery 50 is charged by a vehicle charger 10B such as a DC-DC converter, in place of an alternator.

[0018] 2, the battery 50 includes a management unit 53, a plurality of storage cells 3 (an example of a storage element), and a rectangular parallelepiped storage case 40 that houses them. The storage cells 3 may be battery cells such as lithium ion secondary batteries, or may be electrochemical cells such as capacitors. In this embodiment, the management unit 53 is a battery management unit (BMU).

[0019] Four storage cells 3 are connected in series to configure the assembled battery 30. Alternatively, some of the storage cells 3 may be connected in parallel. For example, the assembled battery 30 may have eight storage cells 3 connected in four series and two in parallel, or twelve storage cells 3 connected in four series and three in parallel.

[0020] The storage case 40 is made of synthetic resin. The storage case 40 includes a case body 41, a lid portion 42 that closes the opening of the case body 41, a storage portion 43 provided in the lid portion 42, a cover 44 that covers the storage portion 43, an inner lid (bus bar frame) 45, and a partition plate 46. The inner lid 45 and the partition plate 46 do not necessarily have to be provided. The storage cell 3 is inserted between the partition plates 46 of the case body 41.

[0021] A plurality of metal bus bars 61 (conductive members) are placed on the inner lid 45. The inner lid 45 is disposed near the terminal surface on which the cell terminals 32 of the storage cells 3 are provided, and adjacent cell terminals 32 of adjacent storage cells 3 are connected by the bus bars 61, so that the storage cells 3 are connected in series.

[0022] The storage section 43 of the lid section 42 is box-shaped and has a protruding section 43A that protrudes outward from the center of one long side in a plan view. A positive terminal (positive external terminal) 51 and a negative terminal (negative external terminal) 52 made of metal such as a lead alloy are provided on both sides of the protruding section 43A of the lid section 42. The positive terminal 51 is connected to the positive electrode of the battery pack 30 via a first power line. The negative terminal 52 is connected to the negative electrode of the battery pack 30 via a second power line.

[0023] The BMU 53 is accommodated in the accommodation section 43. The BMU 53 is connected to the power storage cells 3 via wiring members. Instead of being accommodated in the accommodation section 43, the BMU 53 may be disposed adjacent to the upper or lateral side of the battery pack 30. The lid section 42, the accommodation section 43, the cover 44, and the BMU 53 which is the board itself may be assembled as an integrated unit.

[0024] The energy storage cell 3 includes a hollow rectangular parallelepiped case 31 and a pair of cell terminals 32, 32 with opposite polarities provided on one side (terminal surface, top surface) of the case 31. The case 31 accommodates an electrode assembly 33 formed by stacking a positive electrode, a separator, and a negative electrode, and an electrolyte (electrolytic solution) (not shown).

[0025] Although not shown in detail, the electrode body 33 is constructed by stacking a sheet-shaped positive electrode and a sheet-shaped negative electrode with two sheet-shaped separators between them and winding them (vertically or horizontally). The separators are formed of a porous resin film. As the porous resin film, a porous resin film made of a resin such as polyethylene (PE) or polypropylene (PP) can be used.

[0026] The positive electrode is an electrode plate in which a positive electrode active material layer is formed on the surface of a long strip-shaped positive electrode substrate made of, for example, aluminum, an aluminum alloy, or the like. The positive electrode active material layer includes a positive electrode active material. As the positive electrode active material, a material capable of absorbing and releasing lithium ions can be used. For example, LiFePO4 is used, but is not limited thereto, and a so-called ternary positive electrode active material may be used. The positive electrode active material layer may further include a conductive assistant, a binder, and the like.

[0027] The negative electrode is an electrode plate in which a negative electrode active material layer is formed on the surface of a long strip-shaped negative electrode substrate made of, for example, copper or a copper alloy. The negative electrode active material layer contains a negative electrode active material. As the negative electrode active material, a material capable of absorbing and releasing lithium ions can be used. As the negative electrode active material, for example, graphite, hard carbon, soft carbon, etc. can be mentioned. The negative electrode active material layer may further contain a binder, a thickener, etc.

[0028] The electrolyte housed in the case 31 together with the electrode body 33 may be the same as that used in conventional lithium ion secondary batteries. For example, an electrolyte containing a supporting salt in an organic solvent may be used. As the organic solvent, for example, aprotic solvents such as carbonates, esters, and ethers are used. As the supporting salt, for example, lithium salts such as LiPF6, LiBF4, and LiClO4 are suitably used. The electrolyte may contain various additives such as a gas generating agent, a film forming agent, a dispersing agent, and a thickening agent.

[0029] 2 shows a rectangular lithium ion battery including a wound electrode body 33 as an example of the storage cell 3. Alternatively, the storage cell 3 may be a cylindrical lithium ion battery or a laminated (pouch) lithium ion battery. The storage cell 3 may be a lithium ion battery including a laminated electrode body. The storage cell 3 may be an all-solid-state lithium ion battery using a solid electrolyte.

[0030] The BMU 53 of this embodiment includes a shunt resistor 20 and a temperature measuring device 70 that measures the temperature in the vicinity of the shunt resistor 20. The shunt resistor 20 is incorporated in series in the second power line. The current of the battery 50 can be measured from the voltage across the shunt resistor 20.

[0031] The shunt resistor 20 has a plate shape. As shown in Fig. 3, the shunt resistor 20 includes a resistance portion 21 and a pair of electrode portions 22A, 22B. The pair of electrode portions 22A, 22B are provided on both sides of the resistance portion 21. The resistance portion 21 is an alloy having a small temperature change rate of electrical resistance (one example is manganin: an alloy of copper, manganese, and nickel). The electrode portions 22A, 22B are, for example, a metal such as copper. The resistance portion 21 and each of the electrode portions 22A, 22B are joined by, for example, welding. Specific welding methods that can be used include electron beam welding and resistance welding.

[0032] Each of the electrode portions 22A, 22B has a fixing hole 23 and a connection hole 24 penetrating the electrode portion 22A, 22B in the thickness direction (perpendicular to the paper surface of FIG. 3). The fixing hole 23 is disposed in a portion of each of the electrode portions 22A, 22B closer to the resistance portion 21. The connection hole 24 is disposed in a portion of each of the electrode portions 22A, 22B spaced apart from the resistance portion 21. The connection hole 24 is used to electrically connect the bus bar 61 constituting the second power line to each of the electrode portions 22A, 22B. That is, the bus bar 61 and each of the electrode portions 22A, 22B are connected by inserting a bolt through the through hole and the connection hole 24 provided in the bus bar 61 and screwing the bolt into a nut.

[0033] 2. Temperature measurement device configuration As shown in Figs. 4 and 5, the temperature measuring device 70 includes a substrate 71 and a diode 72. The temperature measuring device 70 may be included in the BMU 53 of Fig. 2, for example. The shunt resistor 20 is fixed to the substrate 71. The thickness direction of the shunt resistor 20 coincides with the thickness direction of the substrate 71. As shown in Fig. 5, the substrate 71 has an insertion hole 73 formed at a position corresponding to the fixing hole 23 of the pair of electrodes 22A, 22B. A fixing bolt B is inserted into the fixing hole 23 and the insertion hole 73 of each electrode 22A, 22B, and the fixing bolt B is screwed into a fixing nut N, whereby the shunt resistor 20 is fixed to the substrate 71. The substrate 71 has an opening 74 formed at a position facing the resistor 21.

[0034] Two first land portions 75 are formed on the first surface S1 of the substrate 71 facing the shunt resistor 20. The first land portions 75 are made of copper foil or the like. Each of the first land portions 75 is connected to each of the electrode portions 22A, 22B by soldering. The two first land portions 75 are electrically connected to a voltage measuring device (not shown) for measuring the voltage of the shunt resistor 20. The BMU 53 measures the voltage applied to the shunt resistor 20, and measures the current of the battery 50 (the current flowing through the shunt resistor 20) based on the measured voltage value and the known resistance value of the shunt resistor 20. The BMU 53 monitors the state of the battery 50 based on information such as the measured value of the current of the battery 50. Since the resistance value of the shunt resistor 20 changes depending on the temperature, the temperature in the vicinity of the shunt resistor 20 is measured, and the resistance value of the shunt resistor 20 is corrected.

[0035] The surface of the substrate 71 opposite to the first surface S1 is the second surface S2. As shown in Fig. 4, three second land portions 76 are formed on the second surface S2. The second land portions 76 are made of copper foil or the like. The three second land portions 76 are disposed on the rim of the opening 74.

[0036] The diode 72 includes a main body 72A and three lead portions 72B extending from the main body 72A. The main body 72A is configured by covering a semiconductor element with an insulating resin. The lead portions 72B are made of a conductive metal and are connected to the semiconductor element. As shown in FIG. 5, the diode 72 is a so-called gull-wing lead type, and the lead portions 72B are substantially L-shaped. Each lead portion 72B is connected to each second land portion 76 by soldering. The second land portion 76 is electrically connected to an amplifier circuit 80, which will be described later.

[0037] The diode 72 is disposed adjacent to the resistance portion 21 of the shunt resistor 20. The diode 72 is mounted on the substrate 71 with substantially the entire body portion 72A disposed inside the opening 74. With this arrangement, it is easy to dispose the body portion 72A and the resistance portion 21 adjacent to each other, and therefore it is easy to bring the temperature of the body portion 72A close to the temperature of the resistance portion 21. Therefore, the accuracy of temperature measurement of the resistance portion 21 can be improved.

[0038] It is preferable that the main body portion 72A is in direct contact with the resistance portion 21. With such an arrangement, the main body portion 72A and the resistance portion 21 are in thermal contact with each other, thereby improving the accuracy of temperature measurement of the resistance portion 21. Although not shown, the main body portion 72A may be in indirect contact with the resistance portion 21 via a thermally conductive material.

[0039] Next, a description will be given of the electrical configuration of the temperature measuring device 70. As shown in Fig. 6, the temperature measuring device 70 includes an amplifier circuit 80 that amplifies the forward voltage of the diode 72, and a control unit 90. The amplifier circuit 80 and the control unit 90 are mounted on a substrate 71.

[0040] The amplifier circuit 80 includes an operational amplifier 81, a first resistor 82 connected to the inverting input terminal of the operational amplifier 81, and a second resistor 83 connected in parallel between the inverting input terminal and the output terminal of the operational amplifier 81. The amplifier circuit 80 is a non-inverting amplifier circuit. If R1 is the resistance value of the first resistor 82 and R2 is the resistance value of the second resistor 83, the amplification factor of the amplifier circuit 80 is theoretically (1+R2 / R1). The non-inverting input terminal of the operational amplifier 81 is connected to the anode of the diode 72. The output terminal of the operational amplifier 81 is connected to the control unit 90. The anode of the diode 72 is connected to the power supply 79 via a third resistor 77 and a switch (PMOS in this example) 78. The gate electrode of the switch 78 is connected to the control unit 90. The cathode of the diode 72 is grounded.

[0041] The control unit 90 is an arithmetic circuit including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. The CPU included in the control unit 90 executes various computer programs stored in the ROM and storage unit, and controls the operation of semiconductor switches and other hardware provided on the substrate 71.

[0042] Alternatively, the control unit 90 may be an integrated circuit (IC) that does not include a CPU or the like, or may be a hardware circuit that includes transistors and the like.

[0043] The control unit 90 applies a gate voltage to the switch 78 to turn on the switch 78 and energize the diode 72. As a result, a forward voltage is generated across the diode. The forward voltage of the diode 72 is then amplified by the amplifier circuit 80 and output to the control unit 90. The control unit 90 calculates the temperature of the diode 72, i.e., the temperature in the vicinity of the shunt resistor 20, based on the output voltage of the amplifier circuit 80.

[0044] It is known that the forward voltage of the diode 72 varies linearly with respect to temperature. In addition, the forward voltage of the diode 72 is amplified by the amplifier circuit 80. Therefore, according to the temperature measuring device 70 of this embodiment, the accuracy of temperature measurement of the shunt resistor 20 can be improved.

[0045] In this embodiment, the control unit 90 applies a square wave gate voltage to the switch 78. This causes the switch 78 to periodically turn on and off, periodically switching the diode 72 between conductive and non-conductive states. This makes it possible to measure the temperature of the shunt resistor 20 at a predetermined cycle.

[0046] 3.Effects As described above, the temperature measuring device 70 included in the BMU 53 of this embodiment includes the diode 72 arranged close to the shunt resistor 20, the amplifier circuit 80 that amplifies the forward voltage of the diode 72, and the control unit 90 that calculates the temperature near the shunt resistor 20 based on the output voltage of the amplifier circuit 80. The temperature characteristic of the forward voltage of the diode 72 is linear, and the voltage fluctuation due to temperature change is approximately constant. Furthermore, the temperature is measured based on the output voltage obtained by amplifying the forward voltage of the diode 72 by the amplifier circuit 80. Therefore, according to the configuration of this embodiment, the accuracy of temperature measurement can be improved. By improving the accuracy of temperature measurement, the temperature measurement error of the shunt resistor 20 can be suppressed, and the current of the battery 50 can be measured with high accuracy.

[0047] In this embodiment, a switch 78 is provided in the current path of the diode 72. Therefore, by controlling the switch, it is possible to conduct electricity through the diode 72 at any timing and measure the temperature of the shunt resistor 20. In addition, when the temperature is not being measured, the switch 78 is turned off to make the diode 72 non-conductive, thereby reducing the power consumption of the diode 72.

[0048] Furthermore, in this embodiment, an opening 74 is provided in the substrate 71, and at least a part of the diode 72 is disposed within this opening 74, so that the diode 72 is disposed close to the shunt resistor 20, thereby further improving the accuracy of temperature measurement. Also, unlike this embodiment, it is easier to reduce the height of the temperature measuring device 70 compared to a configuration in which a diode disposed on a substrate is disposed close to a shunt resistor.

[0049] <Embodiment 2> 7 and 8 show a temperature measuring device 170 and a shunt resistor 120 according to the second embodiment. Hereinafter, the same components as those in the first embodiment are denoted by the same reference numerals, and duplicated explanations may be omitted. The shunt resistor 120 is configured similarly to the shunt resistor 20 according to the first embodiment, except that the electrode portions 122A and 122B do not have the fixing holes 23.

[0050] Unlike the first embodiment, the substrate 171 of the temperature measuring device 170 does not have an insertion hole 73. Furthermore, two fixing lands FL are formed on the first surface S1 of the substrate 171. The fixing lands FL are made of copper foil or the like. Each fixing land FL is connected to each electrode portion 122A, 122B by soldering. In this way, the shunt resistor 120 is fixed to the substrate 171.

[0051] <Other embodiments> The present disclosure is not limited to the embodiments described above and illustrated in the drawings, but is intended to include all modifications within the scope of the claims and their equivalent meanings. The technical scope of the present disclosure also includes, for example, the following embodiments.

[0052] The battery may be installed in other mobile vehicles such as aircraft, railroad trains, ships, etc. The rated voltage of the battery does not have to be 12V, but may be, for example, 48V or other voltages in the so-called "low voltage" range.

[0053] The substrate may not have an opening. In this case, the diode may be disposed on the substrate, for example.

[0054] The control unit does not need to periodically turn on and off the current to the diode. [Explanation of symbols]

[0055] 3. Energy storage cell (energy storage element) 50 Battery (energy storage device) 53 BMU (Battery Management Unit) 20,120 Shunt resistor 70,170 Temperature measuring device 71,171 PCBs 72 Diode 74 Opening 80 Amplification circuit 90 Control section

Claims

1. A shunt resistor, a temperature measuring device that measures a temperature in the vicinity of the shunt resistor; The temperature measuring device is a diode disposed adjacent to the shunt resistor; an amplifier circuit for amplifying a forward voltage of the diode; a control unit that calculates a temperature in the vicinity of the shunt resistor based on an output voltage of the amplifier circuit.

2. The battery management unit according to claim 1 , wherein the control unit turns off the power supply to the diode when the temperature is not being measured.

3. The temperature measuring device further includes a substrate on which the diode, the amplifier circuit, and the control unit are mounted, an opening is formed in the substrate so as to face the shunt resistor; The battery management unit according to claim 1 or 2, wherein at least a portion of the diode is disposed inside the opening.

4. A plurality of storage elements; A power storage device comprising: the battery management unit according to claim 1 or 2.

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