Management device and power system

Abstract

In a management device (20), a voltage measuring circuit (30) measures the voltage of each of a plurality of cells (E1-E12) connected in series. A plurality of voltage measuring lines (L1, L2, L3, ...) connects each node of the plurality of cells (E1-E12) to each voltage measuring terminal of the voltage measuring circuit (30). A lower reference potential line (ground line Lg) connects a lower node of the lowest cell (E1) of the plurality of cells (E1-E12) to a lower reference terminal of the voltage measuring circuit (30). Voltage dividing resistors (Rv1, Rv2) are connected between a predetermined fixed potential and the lowest voltage measuring line (L1). A control circuit (40) monitors the voltage between the voltage dividing point potential of the voltage dividing resistors (Rv1, Rv2) and the lower reference potential of the voltage measuring circuit (30) to diagnose whether the lowest voltage measuring line (L1) or the lower reference potential line (ground line Lg) is broken.

Description

Technical Field

[0001] The present disclosure relates to a management device and a power supply system for managing the states of a plurality of cells connected in series. Background Art

[0002] Hybrid vehicles (HVs), plug-in hybrid vehicles (PHVs), and electric vehicles (EVs) have become increasingly popular in recent years. These electric vehicles are equipped with secondary batteries as key components. Nickel-metal hydride batteries and lithium-ion batteries are the most popular secondary batteries used in vehicles. Lithium-ion batteries, with their high energy density, are expected to see accelerated adoption.

[0003] Typically, automotive secondary batteries are constantly monitored for voltage, temperature, and current to ensure safety. Lithium-ion batteries, in particular, require strict voltage management due to the proximity between normal use and prohibited use areas. Voltage is measured on a cell-by-cell basis. This measured cell voltage is used for SOC (State of Charge) management and equalization control.

[0004] A cell voltage measurement circuit (e.g., comprised of an ASIC (Application Specific Integrated Circuit)) is connected to each node of the plurality of cells connected in series that make up the battery module via voltage measurement lines. The voltage measurement circuit measures the voltage of each cell by measuring the voltage between two adjacent voltage measurement lines.

[0005] In a configuration where the battery module and the voltage measurement circuit share a common ground, in order to accurately measure the voltage of the lowest cell, it is necessary to connect a voltage measurement line (hereinafter referred to as the lowest voltage measurement line) to the node below the lowest cell, separate from the ground line (see, for example, Patent Document 1). This eliminates the influence of the voltage drop caused by the current flowing in the ground line from the measured voltage of the lowest cell.

[0006] In a typical voltage measurement circuit that measures the voltage of each cell by switching multiple measurement channels and sharing a single A / D converter, the switching circuit is configured with ground potential as the reference. The parasitic diodes of the FETs, for example, create a path for current to flow from the lowest voltage measurement line to the ground line. Even if current flows from the lowest voltage measurement line to the ground line, the potential of the lowest voltage measurement line does not exceed a certain voltage (e.g., the forward voltage Vf of the diode). Even if a large current flows, the potential of the lowest voltage measurement line remains clamped at a certain voltage above the ground line.

[0007] To ensure proper cell voltage measurement, a mechanism is required to detect a voltage measurement line break. For example, one method involves flowing current through the voltage measurement line and detecting changes in the measured voltage to detect a voltage measurement line break. If a voltage measurement line break occurs, the measured voltage drops significantly when current flows. Methods for flowing current through the voltage measurement line include using a discharge circuit connected in parallel with the cell for equalization or using a specified current source.

[0008] If a current path is established from the lowest voltage measurement line to the ground line, the measured voltage of the lowest cell will not drop significantly even if the lowest voltage measurement line breaks. Only the forward voltage Vf of the diode between the lowest voltage measurement line and the ground line (typically ~0.7V) will drop. While the vehicle is running, the cell voltage may fluctuate within a range of approximately 4.2V to 3V. In this case, it is difficult to determine whether the drop in the measured voltage of the lowest cell is due to the break or to voltage fluctuations during vehicle operation.

[0009] In addition, protection diodes are generally inserted in opposite directions between each voltage measurement terminal of the voltage measurement circuit and ground. In addition, filter resistors for forming filters and discharge resistors for equalizing discharge are connected to each voltage measurement terminal of the voltage measurement circuit.

[0010] When the ground wire is disconnected, the current consumed by the voltage measurement circuit itself flows through the protection diode and into the voltage measurement terminal. This current then flows through the filter resistor and discharge resistor into the cell. As a result, the measured voltage of the lowest cell drops by an amount equivalent to the voltage drop caused by the current flowing through the filter resistor and discharge resistor. In this case, it is difficult to determine whether the drop in the measured voltage of the lowest cell is due to the disconnection or voltage fluctuations during vehicle operation.

[0011] Prior art literature

[0012] Patent Literature

[0013] Patent Document 1: International Publication No. 2017 / 208740 Summary of the Invention

[0014] Problems to be solved by the invention

[0015] The present disclosure has been made in view of such circumstances, and an object of the present disclosure is to provide a technology capable of detecting a disconnection of a lowest voltage measurement line or a ground line of a voltage measurement circuit with high accuracy.

[0016] Solutions for solving problems

[0017] In order to solve the above-mentioned problem, a management device of a certain embodiment of the present invention comprises: a voltage measuring circuit, which measures the voltage of each of a plurality of monomers connected in series; a plurality of voltage measuring lines, which connect each node of the plurality of monomers with each voltage measuring terminal of the voltage measuring circuit; a lower reference potential line, which connects the lower node of the lowest monomer of the plurality of monomers with the lower reference terminal of the voltage measuring circuit; a voltage dividing resistor, which is connected between a prescribed fixed potential and the lowest voltage measuring line; and a control circuit, which monitors the voltage between the voltage dividing point potential of the voltage dividing resistor and the lower reference potential of the voltage measuring circuit to diagnose whether the lowest voltage measuring line or the lower reference potential line is broken.

[0018] Effects of the Invention

[0019] According to the present disclosure, a disconnection of the lowest voltage measurement line or the ground line of a voltage measurement circuit can be detected with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a diagram showing the configuration of a power supply system according to a comparative example.

[0021] Figure 2 It is shown in Figure 1 This diagram shows the current flowing in the diagnostic mode when a disconnect occurs in the lowest voltage measurement line in the power supply system.

[0022] Figure 3 It is shown in Figure 1 A diagram showing the current that flows when the ground wire is disconnected in a power supply system.

[0023] Figure 4 It is a diagram showing the configuration of a power supply system according to the embodiment.

[0024] Figure 5 It is shown in Figure 4 This diagram shows the current that flows when a disconnect occurs in the lowest voltage measurement line in the power supply system.

[0025] Figure 6 It is shown in Figure 4 A diagram showing the current that flows when the ground wire is disconnected in a power supply system. DETAILED DESCRIPTION

[0026] (Comparative Example)

[0027] Figure 1This is a diagram showing the structure of a power supply system 1 involved in a comparative example. The power supply system 1 is mounted on an electric vehicle and used as a driving battery for the electric vehicle. The power supply system 1 includes a storage module 10 and a management device 20. The storage module 10 includes a plurality of cells E1-E12 connected in series. Cells can use lithium-ion battery cells, nickel-metal hydride battery cells, lead battery cells, double-layer capacitor cells, lithium-ion capacitor cells, etc. In the following, in this specification, it is assumed that an example of a lithium-ion battery cell (nominal voltage: 3.6V-3.7V) is used. In Figure 1 In FIG, 12 cells E1 to E12 are connected in series, thereby constructing a 48V power supply system 1. The number of cells connected in series is not limited to 12.

[0028] The management device 20 includes a voltage measurement circuit 30 and a control circuit 40. In this specification, the voltage measurement circuit 30 is comprised of an ASIC, a dedicated custom IC. The voltage measurement circuit 30 measures the voltage of each cell E1-E12 by measuring the voltage between two adjacent voltage measurement lines. This is described in detail below.

[0029] The voltage measurement circuit 30 has a plurality of voltage measurement terminals. Each node of the plurality of cells E1 to E12 connected in series is connected to each voltage measurement terminal of the voltage measurement circuit 30 via a voltage measurement line. Figure 1 In order to simplify the drawing, only the first voltage measurement line L1 connected to the negative node of the first cell E1, the second voltage measurement line L2 connected to the node between the first cell E1 and the second cell E2, and the third voltage measurement line L3 connected to the positive node of the second cell E2 are depicted.

[0030] Filter resistors Rf1-Rf3 are inserted into the voltage measurement lines L1-L3, respectively. Capacitors Cf1-Cf2 are connected between two adjacent voltage measurement lines. Filter resistors Rf1-Rf3 and capacitors Cf1-Cf2 form a low-pass filter to suppress aliasing.

[0031] The voltage measurement circuit 30 has a plurality of discharge terminals. Each node of the plurality of cells E1 to E12 connected in series is connected to each discharge terminal of the voltage measurement circuit 30 via a discharge line. Figure 1 In order to simplify the drawing, only the first discharge line Ld1 connected to the node on the negative side of the first cell E1, the second discharge line Ld2 connected to the node between the first cell E1 and the second cell E2, and the third discharge line Ld3 connected to the node on the positive side of the second cell E2 are depicted.

[0032] Discharge resistors Rd1-Rd3 are inserted into the multiple discharge lines Ld1-Ld3, respectively. The two ends of a first cell E1 are connected via a second discharge resistor Rd2, a first discharge switch Sd1, and the first discharge resistor Rd1. The second discharge resistor Rd2, the first discharge switch Sd1, and the first discharge resistor Rd1 form a discharge circuit connected in parallel with the first cell E1. The two ends of a second cell E2 are connected via a third discharge resistor Rd3, the second discharge switch Sd2, and the second discharge resistor Rd2. The third discharge resistor Rd3, the second discharge switch Sd2, and the second discharge resistor Rd2 form a discharge circuit connected in parallel with the second cell E2. Capacitors Cd1-Cd2 are connected between two adjacent discharge lines, respectively.

[0033] The first discharge switch Sd1 and the second discharge switch Sd2 can use semiconductor switches such as MOSFET (Metal Oxide Semiconductor Field Effect Transistor). Figure 1 In the example shown, the first discharge switch Sd1 and the second discharge switch Sd2 are provided in the ASIC.

[0034] The voltage measurement circuit 30 includes a power supply terminal connected to the positive terminal of the power storage module 10 via a power supply line and a ground terminal connected to the negative terminal of the power storage module 10 via a ground line Lg.

[0035] The voltage measurement circuit 30 includes a power switch Ss1, an LDO (Low Drop Out) 31, and a measurement unit 32. The positive reference potential terminal of the LDO 31 is connected to the power terminal of the voltage measurement circuit 30 via the power switch Ss1. The negative reference potential terminal of the LDO 31 is connected to the ground terminal of the voltage measurement circuit 30. The LDO 31, a type of linear regulator, steps down the voltage of the power storage module 10 (48V in this specification) to generate the operating voltage of the voltage measurement circuit 30 (5V in this specification). The LDO 31 supplies this generated voltage to the measurement unit 32.

[0036] In addition, other types of DC-DC converters may be used instead of the LDO 31. Furthermore, the DC-DC converter such as the LDO 31 that generates the operating voltage of the voltage measurement circuit 30 may be provided outside the ASIC.

[0037] The positive reference potential terminal of the measurement unit 32 is connected to the output terminal of the LDO 31. The negative reference potential terminal of the measurement unit 32 is connected to the ground terminal of the voltage measurement circuit 30. The negative electrode potential of the power storage module 10, the negative reference potential of the LDO 31, and the negative reference potential of the measurement unit 32 are fixed to a common potential via the ground line Lg, which serves as the lower reference potential line.

[0038] The measurement unit 32 includes a multiplexer and an A / D converter. The multiplexer outputs the voltages input to the measurement channels of the multiple cells E1-E12 to the A / D converter in a specified order. The A / D converter samples the analog voltages input from the multiplexer at a specified timing and converts the sampled analog voltages into digital values. The converted digital voltage values ​​of the multiple cells E1-E12 are transmitted to the control circuit 40. Because the voltage measurement circuit 30 is at a higher voltage than the control circuit 40, the two circuits are connected in an insulated manner via a communication line.

[0039] Forward diode Df is formed between the lowest voltage measurement line L1 and ground line Lg, with the anode being the lowest voltage measurement line L1 and the cathode being the ground line Lg. For example, forward diode Df is formed by a parasitic diode of a FET that forms part of a multiplexer.

[0040] Furthermore, in a design where a multiplexer is not provided within the measurement unit 32 and an A / D converter is provided for each measurement channel, no parasitic diode is formed between the lowest voltage measurement line L1 and the ground line Lg. In this case, a diode element is connected between the lowest voltage measurement line L1 and the ground line Lg as a forward diode Df.

[0041] In the voltage measurement circuit 30, a first protection diode D1 is connected between each of the plurality of voltage measurement lines and the ground line Lg, with the voltage measurement line side as the cathode and the ground line Lg side as the anode. Furthermore, in the voltage measurement circuit 30, a second protection diode D2 is connected between each of the plurality of discharge lines and the ground line Lg, with the discharge line side as the cathode and the ground line Lg side as the anode. Figure 1 In order to simplify the drawing, only the first protection diode D1 between the first voltage measurement line L1 and the ground line Lg and the second protection diode D2 between the first discharge line Ld1 and the ground line Lg are depicted.

[0042] In this specification, the control circuit 40 is composed of a microcomputer and non-volatile memory (e.g., EEPROM, flash memory). The control circuit 40 is capable of performing equalization processing among the multiple cells E1-E12 based on the voltage values ​​of the multiple cells E1-E12 received from the voltage measurement circuit 30. In a typical passive cell balancing method, the cells other than the cell with the smallest capacity among the multiple cells E1-E12 are discharged to the capacity of the cell with the smallest capacity (hereinafter referred to as the target value). In addition, the target value can also be specified by the actual capacity, SOC (State of Charge), or voltage. In addition, the target value can also be specified by the dischargeable capacity or the chargeable capacity.

[0043] The control circuit 40 sets the measured value of the cell with the smallest capacity among the multiple cells E1-E12 as a target value and calculates the difference between this target value and the measured values ​​of the other multiple cells. Based on the calculated differences, the control circuit 40 calculates the discharge capacity of each of the other multiple cells. Based on the calculated discharge capacity, the control circuit 40 calculates the discharge time of each of the other multiple cells. The control circuit 40 generates a control signal that includes equalization processing for the discharge times of the multiple cells and transmits it to the voltage measurement circuit 30. Based on the control signal received from the control circuit 40, the voltage measurement circuit 30 controls the multiple discharge switches to be turned on and maintain them for a specified time.

[0044] The control circuit 40 has a diagnostic mode for diagnosing whether the multiple voltage measurement lines and the ground line Lg are disconnected. In this specification, disconnection is not limited to physical severance of the wiring but also includes electrical disconnection. For example, disconnection also includes a poor connection between the wiring harness and the connector that constitutes the voltage measurement line. In diagnostic mode, the multiple discharge switches are sequentially switched on.

[0045] When the discharge switch is turned on to establish electrical continuity between a broken voltage measurement line and the next-lowest voltage measurement line, the measured voltage of the cells connected to these two voltage measurement lines drops to approximately 0 V. For example, if the third voltage measurement line L3 is broken, turning on the second discharge switch Sd2 pulls the potential of the third voltage measurement line L3 to the potential of the second voltage measurement line L2, and the measured voltage V2 of the second measurement channel drops to approximately 0 V. If no breakage has occurred, the measured voltage V2 of the second measurement channel is the voltage obtained by directly measuring the voltage of the second cell E2.

[0046] Figure 2 It is shown in Figure 1This diagram shows the current flowing in diagnostic mode when the lowest voltage measurement line L1 in power supply system 1 is disconnected. When the first discharge switch Sd1 is turned on while the lowest voltage measurement line L1 is disconnected, current flows from the positive terminal of the first cell E1 through the second discharge resistor Rd2, the first discharge switch Sd1, the first discharge resistor Rd1, the first filter resistor Rf1, and the forward diode Df to the ground line Lg. In this case, the measured voltage V1 of the first measurement channel is the voltage obtained by subtracting the forward voltage Vf of the forward diode Df from the voltage of the first cell E1. When the lowest voltage measurement line L1 is not disconnected, the measured voltage V1 of the first measurement channel is the voltage obtained by directly measuring the voltage of the first cell E1.

[0047] For example, if the forward voltage Vf of forward diode Df is approximately 0.7V, the voltage difference between a break in the lowest voltage measurement line L1 and a break in the lowest voltage measurement line L1 is approximately 0.7V. In this case, it is difficult to determine whether the drop in the measured voltage V1 of the lowest cell E1 is due to the break in the lowest voltage measurement line L1 or to load fluctuations. In electric vehicles, load fluctuations are significant, and cell voltages can fluctuate between approximately 4.2V and 3V during driving.

[0048] Figure 3 It is shown in Figure 1 Figure 1 shows the current flowing when the ground line Lg is broken in the power supply system 1. If the ground line Lg is broken, the current consumed by the measuring unit 32 flows to the negative terminal of the first cell E1 through two paths: the path between the first protection diode D1 and the first filter resistor Rf1, and the path between the second protection diode D2 and the first discharge resistor Rd1.

[0049] For example, consider a case where the value of the first filter resistor Rf1 is 1 kΩ, the value of the first discharge resistor Rd1 is 100 Ω, and the current consumption of the measurement unit 32 is 10 mA. In this case, a current of approximately 0.9 mA flows through the first filter resistor Rf1, and a current of approximately 9.1 mA flows through the first discharge resistor Rd1. Hereinafter, the first filter resistor Rf1 and the first discharge resistor Rd1 are collectively referred to as terminal resistances. The current flowing through the terminal resistances generates a voltage drop of approximately 0.9 V. Consequently, the potential of the lowest voltage measurement line L1 rises by approximately 0.9 V. Furthermore, the magnitude of the potential increase of the lowest voltage measurement line L1 varies depending on the current consumption of the measurement unit 32 and the value of the terminal resistance.

[0050] Thus, if the ground wire Lg is broken, the measured voltage V1 of the first measurement channel is the voltage obtained by subtracting the voltage drop caused by the terminal resistance (approximately 0.9 V in the above example) from the voltage of the first cell E1. If the ground wire Lg is not broken, the measured voltage V1 of the first measurement channel is the voltage obtained by directly measuring the voltage of the first cell E1. Therefore, even if the ground wire Lg is broken, it is difficult to determine whether the drop in the measured voltage V1 of the lowest cell E1 is due to the break in the ground wire Lg or to load fluctuations.

[0051] (Implementation Method)

[0052] Figure 4 This is a diagram showing the configuration of a power supply system 1 according to an embodiment. Figure 1 The differences in the structure of the power supply system 1 involved in the comparative example shown. A voltage-dividing resistor, formed by connecting a first voltage-dividing resistor Rv1 and a second voltage-dividing resistor Rv2 in series, is connected between the output potential of the LDO 31 and the lowest voltage measurement line L1. The lower side of the voltage-dividing resistor is connected to a node N1 on the lowest voltage measurement line L1, which is closer to the lowest cell E1 than the first filter resistor Rf1. The voltage-dividing point of the voltage-dividing resistor is connected to the analog general-purpose input / output terminal GPIO (GPIO) of the voltage measurement circuit 30. The measuring unit 32 constantly measures the voltage between the voltage-dividing point potential of the voltage-dividing resistor and the lower reference potential (ground potential) of the voltage measurement circuit 30 as the monitoring voltage Vm.

[0053] The control circuit 40 monitors the measured monitor voltage Vm to diagnose whether the lowest voltage measurement line L1 or the ground line Lg is broken. If the measured monitor voltage Vm is higher than the normal monitor voltage Vm by a first set value or more, the control circuit 40 diagnoses that the lowest voltage measurement line L1 is broken. If the measured monitor voltage Vm is lower than the normal monitor voltage Vm by a second set value or more, the control circuit 40 diagnoses that the ground line Lg is broken.

[0054] Next, consider an example where both the first and second voltage-dividing resistors Rv1 and Rv2 are 100 kΩ resistors. Furthermore, the output potential of LDO 31 is set to 5 V. When the lowest voltage measurement line L1 and ground line Lg are intact, they maintain the same potential. Even with load fluctuations, the voltage generated by LDO 31 remains stable, so the monitor voltage Vm remains approximately 2.5 V, as shown in the following (Equation 1).

[0055] Vm = VDD × Rv2 / (Rv1 + Rv2) = 5V × 100kΩ × 200kΩ = 2.5V (Formula 1)

[0056] Figure 5 It is shown in Figure 4 This diagram shows the current flowing when the lowest voltage measurement line L1 in power supply system 1 is disconnected. When the lowest voltage measurement line L1 is disconnected, current flows from the output terminal of LDO 31 through the first voltage divider resistor Rv1, the second voltage divider resistor Rv2, the first filter resistor Rf1, and the forward diode Df to ground line Lg. When the lowest voltage measurement line L1 is disconnected, the potential of the lowest voltage measurement line L1 rises above the lower reference potential (ground potential) of the voltage measurement circuit 30 by an amount equivalent to the forward voltage Vf of the forward diode Df.

[0057] For example, consider a case where the value of the first filter resistor Rf1 is 1 kΩ and the forward voltage Vf of the forward diode Df is 0.7 V. When the lowest voltage measurement line L1 is disconnected, the monitor voltage Vm is 2.861 V, as shown in the following (Equation 2). Specifically, the monitor voltage Vm when the lowest voltage measurement line L1 is disconnected is approximately 0.36 V higher than the monitor voltage Vm when the lowest voltage measurement line L1 is normal.

[0058] Vm=Vf+(VDD-Vf)×(Rv2+Rf1) / (Rv1+Rv2+Rf1)=0.7V+(4.3V×101kΩ / 201kΩ)=2.861V···(Formula 2)

[0059] The first set value is set to a value that allows for a margin of approximately 0.36 V. When the measured monitor voltage Vm is higher than the normal monitor voltage Vm by the first set value or more, the control circuit 40 determines that the lowest voltage measurement line L1 is broken.

[0060] Figure 6 It is shown in Figure 4 The current flowing when the ground line Lg is broken in the power supply system 1 is shown in FIG. Figure 3 Similarly to the comparative example shown, the consumption current of the measuring unit 32 flows to the negative terminal of the first cell E1 through two paths: the path between the first protection diode D1 and the first filter resistor Rf1 and the path between the second protection diode D2 and the first discharge resistor Rd1 .

[0061] Next, consider a case where the value of the first filter resistor Rf1 is 1 kΩ, the value of the first discharge resistor Rd1 is 100 Ω, the current consumption of the measurement unit 32 is 10 mA, the forward voltage Vf of the first protection diode D1 is 0.7 V, and the forward voltage Vf of the second protection diode D2 is 0.7 V. Hereinafter, the first filter resistor Rf1 and the first discharge resistor Rd1 are collectively referred to as the terminal resistance Rt, and the voltage drop caused by the current flowing through the terminal resistance Rt is denoted as Vrt.

[0062] When ground line Lg is disconnected, the monitor voltage Vm is 1.7V, as shown in the following (Equation 3). Specifically, when ground line Lg is disconnected, the potential of the lowest voltage measurement line L1 drops below the lower reference potential (ground potential) of voltage measurement circuit 30 by an amount equivalent to the forward voltage Vf of protection diodes D1 and D2 and the voltage drop Vrt across terminal resistance Rt. Under these conditions, the drop is approximately 1.6V. Therefore, the monitor voltage Vm when ground line Lg is disconnected drops by approximately 0.8V compared to the normal monitor voltage Vm.

[0063] Vm=(Vf+Vrt)+(VDD-(Vf+Vrt))×Rv2 / (Rv1+Rv2)=(-0.7V-0.9V)+(5V-(-0.7V-0.9V))×100kΩ / 200kΩ)=1.7V···(Formula 3)

[0064] The second set value is set to a value that allows for a margin of approximately 0.8 V. When the measured monitor voltage Vm is lower than the normal monitor voltage Vm by at least the second set value, the control circuit 40 determines that the ground line Lg is disconnected.

[0065] As described above, according to this embodiment, a disconnection in the lowest voltage measurement line L1 or ground line Lg of the voltage measurement circuit 30 can be detected with high accuracy. While the fluctuation in the monitored voltage Vm when the lowest voltage measurement line L1 or ground line Lg is disconnected is smaller than the fluctuation in the voltages of the other voltage measurement lines, the likelihood of false detection is low because the monitored voltage Vm is stable during normal operation. Specifically, the voltage obtained by resistor-dividing the output voltage of the LDO 31 is monitored, and even cell voltage fluctuations due to, for example, the electric vehicle's operation have little effect on the monitored voltage Vm. Therefore, a disconnection in the lowest voltage measurement line L1 or ground line Lg can be easily and accurately determined based on fluctuations in the monitored voltage Vm.

[0066] Furthermore, unlike conventional voltage measurement line disconnection detection, there is no need to switch on / off a cell's discharge circuit, current source, or the like, allowing for constant disconnection detection of the lowest voltage measurement line L1 or ground line Lg. While disconnection detection requiring switch switching may result in periods during which cell voltage measurement is unavailable, disconnection detection according to the present embodiment generally avoids these periods.

[0067] Furthermore, the GPIO terminals provided in a typical ASIC can be utilized, requiring only two additional components: the first and second voltage-dividing resistors Rv1 and Rv2. This allows for a simple addition of a circuit to diagnose a break in the lowest voltage measurement line L1 or ground line Lg. Since the ability to measure 2.5V determines whether the diagnostic circuit is operating properly, a fault can be easily detected without requiring additional fault detection circuitry.

[0068] Furthermore, by supplying current from the LDO 31 to the voltage-dividing resistor, current does not flow through the voltage-dividing resistor during periods when the voltage measurement circuit 30 is not operating, preventing excess current consumption. Furthermore, since the LDO 31 generates the operating voltage by reducing the voltage across the battery module 10, the current consumed by the voltage-dividing resistor does not disrupt the capacity balance of the multiple cells E1-E12 that comprise the battery module 10. Furthermore, since the lower side of the voltage-dividing resistor is connected to the outer side of the first filter resistor Rf1, current flowing through the voltage-dividing resistor does not flow into the first filter resistor Rf1 during normal operation. Consequently, under normal conditions, the voltage measurement accuracy of the lowest cell E1 is not degraded by current flowing through the voltage-dividing resistor.

[0069] Furthermore, the direction of change in the monitored voltage Vm can be used to determine whether the lowest voltage measurement line L1 or the ground line Lg has been broken. Specifically, if the monitored voltage Vm rises, it can be determined that the lowest voltage measurement line L1 has been broken, whereas if the monitored voltage Vm falls, it can be determined that the ground line Lg has been broken.

[0070] While the present disclosure has been described above based on the embodiments, those skilled in the art will appreciate that the embodiments are merely illustrative and that various modifications may exist for combinations of their constituent elements and processing steps, and that these modifications are also encompassed within the scope of the present disclosure.

[0071] In the above embodiment, an example is described in which the voltage generated by the LDO 31 is used as the voltage applied to the voltage-dividing resistor. However, a fixed voltage generated by another power supply circuit may also be applied to the voltage-dividing resistor. For example, a fixed voltage generated by a DC-DC converter that steps down the voltage of a 12V lead-acid battery to 5V may be applied. Furthermore, the LDO 31 may be omitted, and the fixed voltage generated by the DC-DC converter may be used as the operating voltage of the voltage measurement circuit 30.

[0072] In addition, it can also be set to Figure 4 The forward diode Df is omitted in this configuration. In this configuration, if the lowest voltage measurement line L1 is broken, the monitoring voltage Vm rises to 5V. In this configuration, it is difficult to determine whether the diagnostic circuit is operating normally based solely on whether 2.5V can be measured. Otherwise, this configuration is the same as the description of the above embodiment.

[0073] The above embodiment describes an example in which power supply system 1 is used in an electric vehicle. However, power supply system 1 can also be used in electric flying vehicles such as drones, electric ships, stationary power storage systems, notebook PCs, smartphones, and other electronic devices.

[0074] Furthermore, the embodiment can be determined by the following items.

[0075] [Project 1]

[0076] A management device (20), characterized by comprising:

[0077] A voltage measuring circuit (30) for measuring the voltage of each of a plurality of cells (E1-E12) connected in series;

[0078] a plurality of voltage measurement lines (L1, L2, L3, ...), the plurality of voltage measurement lines (L1, L2, L3, ...) connecting the respective nodes of the plurality of cells (E1-E12) and the respective voltage measurement terminals of the voltage measurement circuit (30);

[0079] a lower reference potential line (Lg) connecting a lower node of the lowest cell (E1) of the plurality of cells (E1-E12) to a lower reference terminal of the voltage measuring circuit (30);

[0080] voltage-dividing resistors (Rv1, Rv2), the voltage-dividing resistors (Rv1, Rv2) being connected between a predetermined fixed potential and a lowest voltage measurement line (L1); and

[0081] A control circuit (40) monitors the voltage between the voltage dividing point potential of the voltage dividing resistors (Rv1, Rv2) and the lower reference potential of the voltage measuring circuit (30) to diagnose whether the lowest voltage measuring line (L1) or the lower reference potential line (Lg) is broken.

[0082] Thus, a disconnection of the lowest voltage measurement line (L1) or the lower reference potential line (Lg) can be detected with high accuracy.

[0083] [Project 2]

[0084] The management device (20) according to item 1 is characterized in that:

[0085] When the voltage between the voltage dividing point potential of the voltage dividing resistors (Rv1, Rv2) and the lower reference potential of the voltage measuring circuit (30) is higher than the normal voltage by a first set value or more, the control circuit (40) diagnoses that the lowest voltage measuring line (L1) is broken.

[0086] Thus, a disconnection of the lowest voltage measurement line (L1) can be detected with high accuracy.

[0087] [Item 3]

[0088] The management device (20) according to item 1 or 2 is characterized in that

[0089] When the voltage between the voltage dividing point potential of the voltage dividing resistors (Rv1, Rv2) and the lower reference potential of the voltage measuring circuit (30) is lower than the normal voltage by a second set value or more, the control circuit (40) diagnoses that the lower reference potential line (Lg) is broken.

[0090] This makes it possible to detect a break in the lower reference potential line (Lg) with high accuracy.

[0091] [Item 4]

[0092] The management device (20) according to any one of items 1 to 3 is characterized in that

[0093] further comprising a plurality of filter resistors (Rf1, Rf2, Rf3, ...) respectively inserted into the plurality of voltage measurement lines (L1, L2, L3, ...),

[0094] The lower sides of the voltage dividing resistors (Rv1, Rv2) are connected to a node on the lowermost voltage measurement line (L1) that is closer to the lowermost cell (E1) than the filter resistor (Rf1).

[0095] This can prevent adverse effects on the accuracy of voltage measurement of the lowest cell ( E1 ).

[0096] [Item 5]

[0097] The management device (20) according to any one of items 1 to 4, characterized in that

[0098] It also includes a DC-DC converter (31) that reduces the voltage across the plurality of cells (E1-E12) to generate a power supply voltage for the voltage measuring circuit (30).

[0099] The output potential of the DC-DC converter (31) is applied to the upper side of the voltage dividing resistors (Rv1, Rv2).

[0100] This reduces the influence of load fluctuations and enables stable divided voltage measurement.

[0101] [Item 6]

[0102] The management device (20) according to any one of items 1 to 5, characterized in that

[0103] A forward diode (Df) is further provided, the forward diode (Df) being connected or formed between the lowest voltage measurement line (L1) and the lower reference potential line (Lg) with the lower reference potential line (Lg) side serving as a cathode.

[0104] This makes it possible to detect whether the voltage-dividing resistors ( Rv1 , Rv2 ) are faulty.

[0105] [Item 7]

[0106] The management device (20) according to any one of items 1 to 6 is characterized in that

[0107] It also includes a plurality of protection diodes (D1), which are respectively connected between the plurality of voltage measurement lines (L1, L2, L3, . . . ) and the lower reference potential line (Lg) with the lower reference potential line (Lg) side as the anode.

[0108] Thus, the voltage measuring circuit (30) can be protected from the influence of overvoltage and the like.

[0109] [Item 8]

[0110] A power supply system (1), characterized by comprising:

[0111] a plurality of monomers (E1-E12) connected in series; and

[0112] The management device (20) according to any one of items 1 to 7, which manages the plurality of cells (E1-E12).

[0113] Thus, a power supply system (1) capable of detecting a disconnection of a lowest voltage measurement line (L1) or a lower reference potential line (Lg) with high accuracy can be constructed.

[0114] Description of Reference Numerals

[0115] 1: Power supply system; 10: Battery module; 20: Management device; 30: Voltage measurement circuit; 31: LDO; 32: Measuring unit; 40: Control circuit; E1-E12: Cells; L1-L3: Voltage measurement lines; Ld1-Ld3: Discharge lines; Lg: Ground line; Rf1-Rf3: Filter resistors; Rd1-Rd3: Discharge resistors; Rv1-Rv2: Voltage divider resistors; Cf1, Cf2, Cd1, Cd2: Capacitors; Sd1-Sd2: Discharge switches; Ss1: Power switch; D1: First protection diode; D2: Second protection diode; Df: Forward diode.

Claims

1. A management device, characterized in that: have: a voltage measuring circuit for measuring the voltage of each of the plurality of cells connected in series; a plurality of voltage measurement lines connecting respective nodes of the plurality of cells and respective voltage measurement terminals of the voltage measurement circuit; a lower reference potential line connecting a lower node of a lowermost cell of the plurality of cells and a lower reference terminal of the voltage measurement circuit; A voltage dividing resistor connected between a specified fixed potential and the lowest voltage measurement line; as well as The control circuit monitors the voltage between the potential of the voltage dividing point of the voltage dividing resistor and the lower reference potential of the voltage measuring circuit to diagnose whether the lowest voltage measuring line or the lower reference potential line is broken.

2. The management device according to claim 1, characterized in that The control circuit diagnoses that the lowest voltage measurement line is disconnected when the voltage between the voltage dividing point potential of the voltage dividing resistor and the lower reference potential of the voltage measurement circuit is higher than the normal voltage by a first set value or more.

3. The management device according to claim 1 or 2, characterized in that: The control circuit diagnoses that the lower reference potential line is broken when the voltage between the voltage dividing point potential of the voltage dividing resistor and the lower reference potential of the voltage measuring circuit is lower than the normal voltage by a second set value or more.

4. The management device according to claim 1 or 2, characterized in that: further comprising a plurality of filter resistors respectively inserted into the plurality of voltage measurement lines, The lower side of the voltage-dividing resistor is connected to a node on the lowermost voltage measurement line that is closer to the lowermost cell than the filter resistor.

5. The management device according to claim 1 or 2, characterized in that: The device further includes a DC-DC converter configured to reduce the voltage across both ends of the plurality of cells to generate a power supply voltage for the voltage measuring circuit. An output potential of the DC-DC converter is applied to the upper side of the voltage-dividing resistor.

6. The management device according to claim 1 or 2, characterized in that: A forward diode is further provided, the forward diode being connected or formed between the lowest voltage measurement line and the lower reference potential line in an orientation with the lower reference potential line side as a cathode.

7. The management device according to claim 1 or 2, characterized in that: The device further includes a plurality of protection diodes connected between the plurality of voltage measurement lines and the lower reference potential line, with the anode facing the lower reference potential line.

8. A power supply system, characterized in that: have: a plurality of cells connected in series; and The management device according to any one of claims 1 to 7, which manages the plurality of units.

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