Internal resistance measurement system, internal resistance measurement device, and internal resistance measurement method

Abstract

To measure the internal resistance of a battery that is chargeable by avoiding a discharge path in which abnormality exists.SOLUTION: An internal resistance measuring system comprises: a measurement unit that measures the voltage of a chargeable battery and a current flowing from the battery in a plurality of discharge paths that include a switch connected to the battery and a resistive element connected in series to the switch and that cause the battery to be discharged when the switch is on; a determination unit that determines the presence of abnormality in the discharge paths on the basis of the current value measured in the discharge paths by the measurement unit when the switch is off and the current value measured in the discharge paths by the measurement unit when the switch is on; and an internal resistance calculation unit that causes the battery to be discharged in a prescribed discharge pattern in a discharge path having been determined to be free of abnormality by the determination unit, and calculates the internal resistance value of the battery from the voltage and current that are measured by the measurement unit when the battery has been discharged in the discharge pattern.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an internal resistance measurement system, an internal resistance measurement device, and an internal resistance measurement method.

Background Art

[0002] As inventions related to the state detection of rechargeable batteries, there are, for example, the deterioration determination device disclosed in Patent Document 1 and the state detection device disclosed in Patent Document 2. These devices obtain the internal impedance from the response voltage and current when the battery is discharged, and determine the degree of deterioration of the battery from the obtained internal impedance.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a device that obtains the internal impedance of a battery by discharging, if there is an abnormality in the discharge path for discharging the battery for measuring the internal impedance, the voltage value and current value due to the discharge cannot be accurately obtained, and the measurement of the internal impedance will be incorrect.

[0005] The present invention has been made in view of the above, and an object thereof is to provide a technique for measuring the internal resistance of a rechargeable battery while avoiding an abnormal discharge path.

[0006] ​To solve the above-mentioned problems and achieve the objective, an internal resistance measurement system according to one aspect of the present invention includes: a measurement unit that measures the voltage of a rechargeable battery and the current flowing from the battery in a plurality of discharge paths that include a switch connected to the battery and a resistive element connected in series with the switch, and which discharge the battery when the switch is ON; a determination unit that determines whether or not there is an abnormality in the discharge path based on the current value measured by the measurement unit when the switch is OFF in the discharge path and the current value measured by the measurement unit when the switch is ON in the discharge path; and an internal resistance calculation unit that discharges the battery in a predetermined discharge pattern in the discharge path determined by the determination unit to be free of abnormalities, and calculates the internal resistance value of the battery from the voltage and current measured by the measurement unit when the battery is being discharged in the discharge pattern.

[0007] In an internal resistance measurement system according to one aspect of the present invention, the internal resistance calculation unit may, when the determination unit determines that there are no abnormalities in the plurality of discharge paths, select a discharge path that discharges the battery in a predetermined pattern according to a predetermined rule.

[0008] In an internal resistance measurement system according to one aspect of the present invention, the internal resistance calculation unit may calculate the average value of the internal resistance values ​​calculated for each of the discharge paths as the internal resistance value of the battery when the determination unit determines that there is no abnormality in the plurality of discharge paths.

[0009] In an internal resistance measurement system according to one aspect of the present invention, the internal resistance calculation unit may switch the discharge path each time the battery is discharged if the determination unit determines that there is no abnormality in the plurality of discharge paths.

[0010] An internal resistance measuring device according to one aspect of the present invention includes: a measuring unit that measures the voltage of a rechargeable battery and the current flowing from the battery in a plurality of discharge paths that include a switch connected to the battery and a resistive element connected in series with the switch, and which discharge the battery when the switch is ON; a determination unit that determines whether or not there is an abnormality in the discharge path based on the current value measured by the measuring unit when the switch is OFF in the discharge path and the current value measured by the measuring unit when the switch is ON in the discharge path; and an internal resistance calculation unit that discharges the battery in a predetermined discharge pattern in the discharge path determined by the determination unit to be free of abnormalities, and calculates the internal resistance value of the battery from the voltage and current measured by the measuring unit when the battery is being discharged in the discharge pattern.

[0011] An internal resistance measurement method according to one aspect of the present invention comprises: a measurement step of measuring the voltage of a rechargeable battery and the current flowing from the battery in a plurality of discharge paths that include a switch connected to the battery and a resistive element connected in series with the switch, and which discharge the battery when the switch is ON; a determination step of determining whether or not there is an abnormality in the discharge path based on the current value measured in the measurement step when the switch is OFF in the discharge path and the current value measured in the measurement step when the switch is ON in the discharge path; and an internal resistance calculation step of discharging the battery in a predetermined discharge pattern in the discharge path determined to be free of abnormalities in the determination step, and calculating the internal resistance value of the battery from the voltage and current measured in the measurement step while the battery is being discharged in the discharge pattern. [Effects of the Invention]

[0012] The present invention offers the advantage of being able to measure the internal resistance of a rechargeable battery while avoiding abnormal discharge paths. [Brief explanation of the drawing]

[0013] [Figure 1]FIG. 1 is a diagram showing a power supply system of a vehicle according to the first embodiment. [Figure 2] FIG. 2 is a block diagram showing the configuration of an internal resistance measuring device. [Figure 3] FIG. 3 is a block diagram showing the functional configuration realized in the control unit. [Figure 4] FIG. 4 is a flowchart showing the flow of processing executed by the control unit. [Figure 5] FIG. 5 is a flowchart showing the flow of processing executed by the control unit. [Figure 6] FIG. 6 is a time chart of the test discharge process. [Figure 7] FIG. 7 is a flowchart showing the flow of processing executed by the control unit. [Figure 8] FIG. 8 is a flowchart showing the flow of processing executed by the control unit. [Figure 9] FIG. 9 is a diagram showing an example of a time chart of a control signal and a discharge current. [Figure 10] FIG. 10 is a diagram showing an example of a time chart of a control signal and a discharge current. [Figure 11] FIG. 11 is a diagram showing a power supply system of a vehicle according to the second embodiment. [Figure 12] FIG. 12 is a flowchart showing the flow of processing executed by the control unit according to the second embodiment. [Figure 13] FIG. 13 is a diagram showing a power supply system of a vehicle according to the third embodiment. [Figure 14] FIG. 14 is a flowchart showing the flow of processing executed by the control unit according to the third embodiment. [Figure 15] FIG. 15 is a diagram showing a power supply system of a vehicle according to the fourth embodiment. [Figure 16] FIG. 16 is a flowchart showing the flow of processing executed by the control unit according to the fourth embodiment. [Figure 17] FIG. 17 is a diagram showing the configuration of an ECU according to a modification. [Figure 18]FIG. 18 is a diagram showing the configuration of a server device according to a modified example.

Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described in detail based on the drawings. Note that the present invention is not limited to the embodiments described below. Also, in the description of the drawings, the same or corresponding elements are given the same reference numerals as appropriate.

[0015] [First Embodiment] (Configuration of Embodiment) FIG. 1 is a diagram showing the power supply system of a vehicle 2A according to the first embodiment of the present invention. The battery 20 is a rechargeable battery having an electrolyte, and is constituted by, for example, a lead storage battery, a lithium ion battery, a nickel cadmium battery, or a nickel hydrogen battery. The battery 20 is charged by the alternator 25, drives the starter motor 27, and supplies power to the load 28. The starter motor 27 is constituted by, for example, a DC motor, generates a rotating force by the power supplied from the battery 20, and starts the engine 26. The engine 26 is constituted by, for example, a reciprocating engine such as a gasoline engine and a diesel engine, or a rotary engine. The engine 26 is started by the starter motor 27, drives the drive wheels via the transmission, gives a propulsive force to the vehicle 2A, and drives the alternator 25. The alternator 25 is driven by the engine 26 to generate AC power, converts the generated AC power into DC power by a rectifier circuit, and charges the battery 20. The load 28 is constituted by, for example, an electric power steering motor, a defroster, a seat heater, an ignition coil, a car audio, and a car navigation, and operates by the power supplied from the battery 20.

[0016] The first switch SW1 and the first resistor R1, connected in series, constitute a first discharge circuit 21A that discharges the battery 20 in a predetermined discharge pattern. The first discharge circuit 21A is an example of a discharge path that discharges the battery 20 in a predetermined pattern. Here, the "predetermined discharge pattern" has a predetermined discharge current and a predetermined discharge time. The first switch SW1 is composed of a semiconductor switch such as an FET (Field Effect Transistor) or IGBT (Insulated Gate Bipolar Transistor), or an electromagnetic switch such as a relay. One end of the first switch SW1 is connected to the positive terminal of the battery 20, and the other end is connected to the first resistor R1. One end of the first resistor R1 is connected to the first switch SW1, and the other end is connected to terminal T3 of the internal resistance measuring device 1 and the second resistor R2, and is grounded. The first switch SW1 is turned on or off in response to a control signal supplied from terminal T4 of the internal resistance measuring device 1. The first discharge circuit 21A discharges the battery 20 via the first resistor R1 when the first switch SW1 is ON, and stops the discharge of the battery 20 via the first discharge circuit 21A when the first switch SW1 is OFF. When the first switch SW1 is ON, a predetermined discharge current flows from the battery 20 through the first resistor R1.

[0017] The second switch SW2 and the third resistor R3, connected in series, constitute a second discharge circuit 21B that discharges the battery 20 in a predetermined discharge pattern. The second discharge circuit 21B is an example of a discharge path that discharges the battery 20 in a predetermined pattern. The second switch SW2 is composed of, for example, a semiconductor switch such as an FET or IGBT, or an electromagnetic switch such as a relay. One end of the second switch SW2 is connected to the positive terminal of the battery 20, and the other end is connected to the third resistor R3. One end of the third resistor R3 is connected to the second switch SW2, and the other end is connected to terminal T3 of the internal resistance measuring device 1 and the second resistor R2 and grounded. The second switch SW2 is turned on or off in response to a control signal supplied from terminal T5 of the internal resistance measuring device 1. When the second switch SW2 is on, the second discharge circuit 21B discharges the battery 20 via the third resistor R3, and when the second switch SW2 is off, it stops the discharge of the battery 20 via the second discharge circuit 21B. In this embodiment, the resistance value of the third resistor R3 is the same as that of the first resistor R1. When the second switch SW2 is turned on, a predetermined discharge current flows from the battery 20 through the third resistor R3.

[0018] The second resistive element R2 has one end connected to terminal T2 of the internal resistance measuring device 1 and the negative terminal of the battery 20, and the other end connected to terminal T3 of the internal resistance measuring device 1, the first resistive element R1, and the third resistive element R3, and is grounded. The second resistive element R2 constitutes a current sensor and generates a voltage corresponding to the current flowing through it, which is supplied to terminals T2 and T3 of the internal resistance measuring device 1. By converting the voltage generated in the second resistive element R2 with the AD converter 13 described later, the current flowing through the second resistive element R2 can be determined. The internal resistance measuring device 1 also functions as a voltage sensor by converting the voltage applied to terminals T1 and T2 with the AD converter 13 described later, and detects the voltage of the battery 20.

[0019] The internal resistance measuring device 1, which measures the internal resistance value of the battery 20, discharges the battery 20 in a predetermined discharge pattern by controlling the first switch SW1 on and off using a control signal output from terminal T4. The internal resistance measuring device 1 also discharges the battery 20 in a predetermined discharge pattern by controlling the second switch SW2 on and off using a control signal output from terminal T5. The internal resistance measuring device 1 determines the internal resistance value of the battery 20 from the voltage and current measured while the battery 20 is discharging in this predetermined discharge pattern, and detects the state of the battery 20 based on the determined internal resistance value. Note that the internal resistance measuring device 1, the first discharge circuit 21A, the second discharge circuit 21B, the second resistive element R2, and the temperature sensor 23 may not be separate configurations, but rather a configuration combining some or all of these components may be designated as the internal resistance measuring device 1.

[0020] Figure 2 is a block diagram showing an example of the configuration of the internal resistance measuring device 1. The internal resistance measuring device 1 includes a control unit 10 containing a CPU (Central Processing Unit) 10a, a ROM (Read Only Memory) 10b, and a RAM (Random Access Memory) 10c, a storage unit 11, a communication unit 12, an AD converter 13, and a bus 14. The control unit 10 may be configured using a DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), or ASIC (Application Specific Integrated Circuit) instead of the CPU 10a. Here, it is not necessary for all the elements of the internal resistance measuring device 1 (control unit 10, storage unit 11, communication unit 12, AD converter 13) to be grouped together; for example, each element may be distributed inside the vehicle 2 as an internal resistance measuring system.

[0021] Bus 14 is a group of signal lines that interconnect the CPU 10a, ROM 10b, RAM 10c, memory unit 11, communication unit 12, and AD converter 13, enabling the exchange of information between them. The memory unit 11 is composed of non-volatile memory and stores, for example, the resistance values ​​of the first resistor R1, the second resistor R2, and the third resistor R3, as well as various threshold values ​​described later. The AD converter 13 is a converter that converts analog signals into digital signals, converting the voltages applied to terminals T1, T2, and T3 into digital signals. The communication unit 12 communicates with the ECU (Electronic Control Unit) 3, which is a higher-level device that controls the main drive system of the vehicle 2A, and notifies the ECU 3 of various information.

[0022] ROM 10b is composed of non-volatile semiconductor memory and stores the program 10ba, etc. RAM 10c is composed of semiconductor memory and stores data generated when the CPU 10a executes the program 10ba, various measurement results, and various values ​​calculated by the CPU 10a using the measurement results.

[0023] The CPU 10a controls each part based on the program 10ba stored in the ROM 10b. The functions of the control unit 10 are realized as a functional unit when the CPU 10a reads and executes the program 10ba from the ROM 10b.

[0024] Figure 3 is a functional block diagram showing the configuration of the functions realized in the control unit 10 when the CPU 10a executes the program 10ba. The control unit 10 includes a measurement unit 101, a determination unit 102, and an internal resistance calculation unit 103.

[0025] The measurement unit 101 uses the resistance values ​​of the first resistor R1, second resistor R2, and third resistor R3, obtained from the AD conversion performed by the AD converter 13, to measure the voltage of the battery 20 and the current flowing from the battery 20 in a predetermined discharge path. The determination unit 102 determines whether there is an abnormality in the discharge path that discharges the battery 20 in a predetermined pattern, based on the measurement results of the measurement unit 101. The internal resistance calculation unit 103 calculates the internal resistance value of the battery 20 based on the measurement results of the measurement unit 101 when the battery 20 is discharged in a predetermined pattern in the discharge path that the determination unit 102 determined to be free of abnormalities. The first discharge circuit 21A, the second discharge circuit 21B, the measurement unit 101, the determination unit 102, and the internal resistance calculation unit 103 function as an internal resistance measurement system.

[0026] (Example of operation of the embodiment) Next, an example of operation of this embodiment will be described. Figure 4 is a flowchart showing the flow of processing performed by the control unit 10 when measuring the internal resistance value of the battery 20. The processing shown in Figure 4 is performed periodically, for example, every time the ignition is turned off in the vehicle 2A, every few days, every few weeks, or every few months. Note that the processing shown in Figure 4 may also be performed upon request from the user or irregularly.

[0027] First, the control unit 10 performs a test discharge of the battery 20 (step S101). Figure 5 shows the flow of the process performed by the control unit 10 in step S101. Figure 6 shows the time chart for the process in step S101. Figure 6 illustrates the on / off timing of the first switch SW1 based on the control signal output from terminal T4, the on / off timing of the second switch SW2 based on the control signal output from terminal T5, and the change in current measured by the control unit 10.

[0028] First, the control unit 10 turns off the first switch SW1 and the second switch SW2 as shown in Figure 6 (step S201). Next, the control unit 10 measures a reference current value, which is the reference value of the current flowing from the battery 20 when the first switch SW1 and the second switch SW2 are off (step S202). In the current change shown in Figure 6, the case when the battery 20 is being charged is defined as positive, and the case when the battery 20 is being discharged is defined as negative, so when a discharge current flows, the current flows in the negative direction. Here, the control unit 10 calculates the current value of the current flowing through the second resistive element R2 from the resistance value of the second resistive element R2 which is stored in the memory unit 11 in advance and the voltage applied to the second resistive element R2 converted by the AD converter 13, and uses the calculated current value as the reference current value. Specifically, the control unit 10 measures the voltage applied to the second resistive element R2 multiple times at a predetermined period, calculates the current value for each measured voltage, and uses the average value of the calculated current values ​​as the reference current value.

[0029] Next, the control unit 10 measures the off-current value I1, which is the current value of the current flowing from the battery 20 after step S202 when the first switch SW1 and the second switch SW2 are off (step S203). Here, the control unit 10 calculates the current value of the current flowing through the second resistive element R2 from the resistance value of the second resistive element R2 stored in the memory unit 11 and the voltage value of the voltage applied to the second resistive element R2 converted by the AD converter 13, and sets the calculated current value as the off-current value I1. Specifically, the control unit 10 measures the voltage value applied to the second resistive element R2 multiple times at a predetermined period, calculates the current value for each measured voltage value, and sets the average value of the calculated current values ​​as the off-current value I1. Here, if the voltage fluctuates after step S202, for example due to the load 28, the off-current value I1 will be a different value from the reference current value.

[0030] Next, the control unit 10 turns off the first switch SW1 and the second switch SW2 as shown in Figure 6 (step S204). The control unit 10 measures the on-current value I11, which is the current value of the current flowing from the battery 20 when the first switch SW1 is on and the second switch SW2 is off, as shown in Figure 6 (step S205). Here, the control unit 10 calculates the current value of the current flowing through the first resistor R1 from the resistance value of the first resistor R1 which is stored in the memory unit 11 in advance and the voltage value of the voltage applied to the first resistor R1 which has been converted by the AD converter 13, and sets the calculated current value as the on-current value I11. Specifically, the control unit 10 measures the voltage value applied to the first resistor R1 multiple times at a predetermined period, calculates the current value for each measured voltage value, and sets the average value of the calculated current values ​​as the on-current value I11. Although a voltage is also generated across the second resistive element R2, the resistance of the second resistive element R2 is negligibly small compared to the resistance of the first resistive element R1. Therefore, the voltage generated across the second resistive element R2 can be ignored, and the on-current value I11 may be calculated using the voltage of the battery 20 instead of the voltage across the first resistive element R1.

[0031] Next, as shown in Figure 6, the control unit 10 measures the on-voltage value V11, which is the voltage value across the first resistor R1, when the first switch SW1 is ON and the second switch SW2 is OFF (step S206). Here, the control unit 10 uses the voltage value across the first resistor R1 converted by the AD converter 13 as the on-voltage value V11. Next, as shown in Figure 6, the control unit 10 turns off the first switch SW1 and the second switch SW2 (step S207).

[0032] Next, the control unit 10 waits for a predetermined time with the first switch SW1 and the second switch SW2 in the OFF state (step S208). After waiting for the predetermined time, the control unit 10 turns off the first switch SW1 and turns on the second switch SW2 as shown in Figure 6 (step S209). As shown in Figure 6, the control unit 10 measures the ON current value I12, which is the current value of the current flowing from the battery 20 when the first switch SW1 is OFF and the second switch SW2 is ON (step S210). Here, the control unit 10 calculates the current value of the current flowing through the third resistor R3 from the resistance value of the third resistor R3 stored in the memory unit 11 and the voltage value of the voltage applied to the third resistor R3 converted by the AD converter 13, and sets the calculated current value as the ON current value I12. Specifically, the control unit 10 measures the voltage value applied to the third resistor R3 multiple times at a predetermined period, calculates the current value for each measured voltage value, and sets the average value of the calculated current values ​​as the ON current value I12. Although a voltage is also generated across the second resistive element R2, the resistance of the second resistive element R2 is negligibly small compared to the resistance of the third resistive element R3. Therefore, the voltage generated across the second resistive element R2 can be ignored, and the on-current value I12 may be calculated using the voltage of the battery 20 instead of the voltage across the third resistive element R3.

[0033] Next, as shown in Figure 6, the control unit 10 measures the on-voltage value V12, which is the voltage value across the third resistor R3, when the first switch SW1 is off and the second switch SW2 is on (step S211). Here, the control unit 10 sets the on-voltage value V12 to the voltage value across the third resistor R3 converted by the AD converter 13. Next, as shown in Figure 6, the control unit 10 turns off the first switch SW1 and the second switch SW2 (step S212), ending the test discharge process.

[0034] Returning to Figure 4, the control unit 10 then determines whether there is any abnormality in the AD converter 13 (step S102). Here, the control unit 10 determines that there is an abnormality in the AD converter 13 if, for example, the output value of the AD converter 13 was outside the range when measuring the voltage in step S101, or if the AD conversion did not finish within a predetermined time and timed out (NO in step S102). Also, the control unit 10 determines that there is no abnormality in the AD converter 13 if no range over or timeout occurred in the AD converter 13 (YES in step S102). If there is an abnormality in the AD converter 13, the control unit 10 terminates the process shown in Figure 4. Note that the control unit 10 may skip the process in step S102 and perform the process in step S103 after step S101.

[0035] If there is no abnormality in the AD converter 13, the control unit 10 performs a discharge circuit diagnosis process (step S103). Figure 7 shows the flow of processing performed by the control unit 10 in step S103. First, the control unit 10 determines whether the off-current value I1 measured in step S203 is within a predetermined range (step S301). Here, for example, if threshold A < (off-current value I1 - reference current value), the control unit 10 determines that it is outside the predetermined range (NO in step S301), and if threshold A ≥ (off-current value I1 - reference current value), it determines that it is within the predetermined range (YES in step S301).

[0036] If the control unit 10 determines in step S301 that the range is outside the predetermined range, it turns on the first flag and the second flag (step S302). The control unit 10 also counts the number of times the first flag and the second flag have been turned on. The threshold A is a value determined in advance through experimentation.

[0037] If the control unit 10 determines in step S301 that the value is within a predetermined range, it then determines in step S205 whether the measured on-current value I11 is within the predetermined range (step S303). Here, for example, if threshold C ≤ (on-current value I11 - reference current value) ≤ threshold D, the control unit 10 determines that the value is within the predetermined range (YES in step S303), and if threshold C ≤ (on-current value I11 - reference current value) ≤ threshold D is not true, it determines that the value is outside the predetermined range (NO in step S303). Alternatively, the control unit 10 may determine that the value is within the predetermined range if threshold E ≤ on-current value I11 ≤ threshold F (YES in step S303), and if threshold E ≤ on-current value I11 ≤ threshold F is not true, it may determine that the value is outside the predetermined range (NO in step S303). Note that thresholds C, D, E, and F are values ​​determined in advance by experiment. If the control unit 10 determines in step S303 that the value is outside the predetermined range, it turns on the first flag (step S305). The control unit 10 also counts the number of times the first flag has been turned on. If the control unit 10 determines in step S303 that the value is within the predetermined range, it turns off the first flag (step S304).

[0038] Next, the control unit 10 determines whether the ON current value I12 measured in step S210 is within a predetermined range (step S306). Here, the control unit 10 determines that it is within the predetermined range if, for example, threshold C ≤ (ON current value I12 - reference current value) ≤ threshold D (YES in step S306), and determines that it is outside the predetermined range if threshold C ≤ (ON current value I12 - reference current value) ≤ threshold D is not true (NO in step S306). The control unit 10 may also determine that it is within the predetermined range if, for example, threshold E ≤ ON current value I12 ≤ threshold F (YES in step S306), and determine that it is outside the predetermined range if threshold E ≤ ON current value I12 ≤ threshold F is not true (NO in step S306). If the control unit 10 determines in step S306 that it is outside the predetermined range, it turns on the second flag (step S308). The control unit 10 also counts the number of times the second flag has been turned on. Furthermore, if the control unit 10 determines in step S306 that the value is within a predetermined range, it turns off the second flag (step S307).

[0039] Returning to Figure 4, the control unit 10 then performs a current abnormality diagnosis (step S104). Figure 8 shows the flow of processing performed by the control unit 10 in step S104. First, the control unit 10 obtains the resistance value of the first resistor R1 from the storage unit 11 (step S401). If the resistance value of the first resistor R1 is temperature dependent, the resistance value of the first resistor R1 may be corrected based on the temperature measured by the temperature sensor 23. For example, the temperature coefficient can be stored in the storage unit 11, and the resistance value can be corrected by multiplying the temperature T by this temperature coefficient. Of course, if the temperature coefficient is sufficiently small, the change in resistance value due to temperature may be ignored.

[0040] Next, the control unit 10 calculates the estimated current value Ie1 by dividing the on-voltage value V11 measured in step S206 by the resistance value obtained in step S401 (step S402). The control unit 10 also calculates ΔI1 (=|on-current value I11 - estimated current value Ie1|), which is the absolute value of the difference between the on-current value I11 measured in step S205 and the estimated current value Ie1 calculated in step S402 (step S403).

[0041] Next, the control unit 10 determines whether the calculated ΔI1 is greater than or equal to a predetermined threshold (step S404). If ΔI1 is greater than or equal to the threshold (YES in step S404), the control unit 10 turns on the third flag (step S405). The threshold used in step S404 is a value determined in advance through experimentation. The control unit 10 also counts the number of times the third flag has been turned on. If ΔI1 is less than the threshold (NO in step S404), the control unit 10 turns off the third flag (step S406).

[0042] Next, the control unit 10 obtains the resistance value of the third resistor R3 from the storage unit 11 (step S407). If the resistance value of the third resistor R3 is temperature-dependent, the resistance value of the third resistor R3 may be corrected based on the temperature measured by the temperature sensor 23, similar to step S401.

[0043] Next, the control unit 10 calculates the estimated current value Ie2 by dividing the on-voltage value V12 measured in step S211 by the resistance value obtained in step S407 (step S408). The control unit 10 also calculates ΔI2 (=|on-current value I12 - estimated current value Ie2|), which is the absolute value of the difference between the on-current value I12 measured in step S210 and the estimated current value Ie2 calculated in step S408 (step S409).

[0044] Next, the control unit 10 determines whether the calculated ΔI2 is greater than or equal to a predetermined threshold (step S410). If ΔI2 is greater than or equal to the threshold (YES in step S410), the control unit 10 turns on the fourth flag (step S411). The threshold used in step S410 is a value determined in advance through experimentation. The control unit 10 also counts the number of times the fourth flag has been turned on. If ΔI2 is less than the threshold (NO in step S410), the control unit 10 turns off the fourth flag (step S412).

[0045] Returning to Figure 4, the control unit 10 then determines whether the first to fourth flags are off (step S105). If not all of the first to fourth flags are off (NO in step S105), the control unit 10 determines whether the diagnosis in step S103 and the diagnosis in step S104 have been performed a predetermined number of times (step S106). The predetermined number of times is, for example, any number of 1 or more. If the number of diagnoses has not reached the predetermined number (NO in step S106), the control unit 10 returns the process to step S101.

[0046] If the number of diagnostic checks reaches a predetermined number (YES in step S106), the control unit 10 sets a circuit abnormality flag (step S107). Here, if the number of times the first flag and the second flag were turned on in the process of Figure 7 is not the predetermined number, the control unit 10 determines that there is no abnormality in the first discharge circuit 21A and the second discharge circuit 21B, and turns off the first circuit abnormality flag and the second circuit abnormality flag. If the number of times the first flag was turned on in the process of Figure 7 is the predetermined number, the control unit 10 turns on the first circuit abnormality flag. Also, if the number of times the second flag was turned on in the process of Figure 7 is the predetermined number, the control unit 10 turns on the second circuit abnormality flag. If the first circuit abnormality flag is on, the control unit 10 determines that there is an abnormality in the first discharge circuit 21A, and if the second circuit abnormality flag is on, it determines that there is an abnormality in the second discharge circuit 21B.

[0047] Next, the control unit 10 sets a current abnormality flag (step S108). Here, if the number of times the third flag and the fourth flag were turned on in the process of Figure 7 is not a predetermined number, the control unit 10 determines that there is no abnormality in the current flowing through the first discharge circuit 21A and the current flowing through the second discharge circuit 21B, and turns off the first current abnormality flag and the second current abnormality flag. If the number of times the third flag was turned on in the process of Figure 8 is a predetermined number, the control unit 10 turns on the first current abnormality flag. Also, if the number of times the fourth flag was turned on in the process of Figure 8 is a predetermined number, the control unit 10 turns on the second current abnormality flag. If the first current abnormality flag is on, the control unit 10 determines that there is an abnormality in the first discharge circuit 21A, and if the second current abnormality flag is on, it determines that there is an abnormality in the second discharge circuit 21B.

[0048] Next, the control unit 10 determines whether the internal resistance value of the battery 20 can be measured (step S109). If the first circuit abnormality flag is off and the first current abnormality flag is off, the control unit 10 determines that the internal resistance value of the battery 20 can be measured (YES in step S109) and moves the process to step S112. Also, if the second circuit abnormality flag is off and the second current abnormality flag is off, the control unit 10 determines that the internal resistance value of the battery 20 can be measured (YES in step S109) and moves the process to step S112. If the first circuit abnormality flag, the second circuit abnormality flag, the first current abnormality flag, and the second current abnormality flag are on, the control unit 10 determines that the internal resistance value of the battery 20 cannot be measured (NO in step S109) and terminates the process shown in Figure 4. Furthermore, if either the first circuit abnormality flag or the first current abnormality flag is on, and either the second circuit abnormality flag or the second current abnormality flag is on, the control unit 10 determines that the internal resistance value of the battery 20 cannot be measured (NO in step S109), and terminates the process shown in Figure 4.

[0049] Returning to step S105, the control unit 10 sets the circuit abnormality flag (step S110) if all of the first to fourth flags are off (YES in step S105). Here, the control unit 10 turns off the first circuit abnormality flag and the second circuit abnormality flag. After step S110, the control unit 10 sets the current abnormality flag (step S111). Here, the control unit 10 turns off the first current abnormality flag and the second current abnormality flag. If the first circuit abnormality flag and the first current abnormality flag are off, the control unit 10 determines that there is no abnormality in the first discharge circuit 21A, and if the second circuit abnormality flag and the second current abnormality flag are off, the control unit 10 determines that there is no abnormality in the second discharge circuit 21B.

[0050] In step S112, the control unit 10 measures the internal resistance of the battery 20. Here, if, for example, the first circuit abnormality flag, the first current abnormality flag, the second circuit abnormality flag, and the second current abnormality flag are all off, the control unit 10 selects one of the first discharge circuit 21A and the second discharge circuit 21B according to a predetermined rule, and measures the internal resistance of the battery 20 using the selected discharge circuit. For example, when the control unit 10 selects one of the first discharge circuit 21A and the second discharge circuit 21B, it may select a discharge circuit different from the one used in the previous measurement of the internal resistance. Alternatively, when the control unit 10 selects one of the first discharge circuit 21A and the second discharge circuit 21B, it may always select the same discharge circuit.

[0051] Furthermore, if the first circuit abnormality flag, the first current abnormality flag, the second circuit abnormality flag, and the second current abnormality flag are all off, the internal resistance value may be measured using both the first discharge circuit 21A and the second discharge circuit 21B, and the measurement result of one of the discharge circuits may be adopted according to a predetermined rule. For example, when the control unit 10 adopts either the measurement result using the first discharge circuit 21A or the measurement result using the second discharge circuit 21B, it may adopt the measurement result when a different discharge circuit was used than the one used in the previous measurement of the internal resistance value. Also, when the control unit 10 adopts either the measurement result using the first discharge circuit 21A or the measurement result using the second discharge circuit 21B, it may always adopt the measurement result from the same discharge circuit.

[0052] Furthermore, the control unit 10 may perform measurements using the first discharge circuit 21A and measurements using the second discharge circuit 21B before setting the first circuit abnormality flag, first current abnormality flag, second circuit abnormality flag, and second current abnormality flag for measuring the internal resistance value. In this case, the control unit 10 will determine whether to adopt the measurement results using the first discharge circuit 21A and the measurement results using the second discharge circuit 21B, depending on the status of the first circuit abnormality flag, first current abnormality flag, second circuit abnormality flag, and second current abnormality flag.

[0053] For example, if all of the aforementioned abnormality flags are off, the control unit 10 may adopt the measurement result of one of the discharge circuits according to the predetermined rules as described above. Also, if both the first circuit abnormality flag and the first current abnormality flag are off and one of the second circuit abnormality flag and the second current abnormality flag is on, the control unit 10 may adopt the measurement result using the first discharge circuit 21A, and if one of the first circuit abnormality flag and the first current abnormality flag is on and both the second circuit abnormality flag and the second current abnormality flag are off, the control unit 10 may adopt the measurement result using the second discharge circuit 21B. Furthermore, if the control unit 10 determines NO in step S109, it may not adopt the most recent internal resistance value measured before the setting of the abnormality flags, but instead adopt the internal resistance value that was previously adopted when the determination in step S109 was YES. Also, if the control unit 10 determines NO in step S109, it may invalidate the measurement value of the most recent internal resistance value measured before the setting of the abnormality flags.

[0054] If the first circuit abnormality flag and the first current abnormality flag are off, and at least one of the second circuit abnormality flag and the second current abnormality flag is on, the control unit 10 selects the first discharge circuit 21A and measures the internal resistance of the battery 20 using the selected first discharge circuit 21A. If at least one of the first circuit abnormality flag and the first current abnormality flag is on, and the second circuit abnormality flag and the second current abnormality flag are off, the control unit 10 selects the second discharge circuit 21B and measures the internal resistance of the battery 20 using the selected second discharge circuit 21B.

[0055] Furthermore, the control unit 10 may measure the internal resistance using the first discharge circuit 21A and the second discharge circuit 21B, and if the first circuit abnormality flag and the first current abnormality flag are off, and at least one of the second circuit abnormality flag and the second current abnormality flag is on, it may adopt the measurement result using the first discharge circuit 21A. Also, the control unit 10 may measure the internal resistance using the first discharge circuit 21A and the second discharge circuit 21B, and if at least one of the first circuit abnormality flag and the first current abnormality flag is on, and the second circuit abnormality flag and the second current abnormality flag are off, it may adopt the measurement result using the second discharge circuit 21B.

[0056] The internal resistance of the battery 20 can be obtained, for example, by controlling the selected first discharge circuit 21A or second discharge circuit 21B so that the battery 20 is discharged in a predetermined pattern, and the changes in the voltage and current of the battery 20 when the discharge is performed in the predetermined pattern are measured by the voltage sensor 21 and the current sensor 22, and the internal resistance is calculated from the measurement results. When the first discharge circuit 21A is selected, the control unit 10 measures the voltage and current of the battery 20 when the battery 20 is discharged in a predetermined pattern by alternately turning the first switch SW1 on and off with a control signal from terminal T4, and determines the internal resistance of the battery 20 from the measurement results. When the second discharge circuit 21B is selected, the control unit 10 measures the voltage and current of the battery 20 when the battery 20 is discharged in a predetermined pattern by alternately turning the second switch SW2 on and off with a control signal from terminal T5, and determines the internal resistance of the battery 20 from the measurement results.

[0057] Methods for calculating the internal resistance value by discharging the battery 20 in a predetermined pattern include, for example, the method disclosed in Japanese Patent Publication No. 3960998 and the method disclosed in Japanese Patent Publication No. 4494904, but other known methods may also be used. When measuring the internal resistance value of the battery 20, if the battery 20 is discharged in a predetermined pattern, multiple patterns with different discharge frequencies may be provided, and the internal resistance value may be measured based on the current and voltage response results for each pattern.

[0058] The control unit 10 can calculate or estimate the state of the battery 20, such as OCV (Open Circuit Voltage), SOC (State of Charge), SOH (State of Health), and SOF (State of Function), based on the measured internal resistance value. Furthermore, since the internal resistance value of the battery 20 is related to the temperature of the battery 20, the control unit 10 may estimate the temperature of the battery 20 using a predetermined calculation formula based on the measured internal resistance value. The calculation or estimation of OCV, SOC, SOH, and SOF can be performed using an equivalent circuit model of the battery 20, as disclosed, for example, in Japanese Patent Application Publication No. 2021-196174. For example, for OCV, the control unit 10 uses the terminal voltage of the battery 20 measured immediately before starting up, or a voltage value estimated from the charge / discharge state of the battery 20, as the OCV. For SOC, the control unit 10 estimates it based, for example, the internal resistance calculated from the measured current and voltage values, or a combination of OCV and the integrated current value. Furthermore, the control unit 10 obtains SOH and SOF by estimation based on OCV, estimation using constants and relational formulas of the equivalent circuit model, etc.

[0059] Furthermore, if the control unit 10 has all four flags (first discharge circuit abnormality flag, first current abnormality flag, second discharge circuit abnormality flag, and second current abnormality flag) turned off, it may use both the first discharge circuit 21A and the second discharge circuit 21B to measure the internal resistance of the battery 20. Figure 9 shows an example of the control signal and a time chart of the discharge current flowing from the battery 20 when measuring the internal resistance using both the first discharge circuit 21A and the second discharge circuit 21B.

[0060] First, as shown in Figure 9, the control unit 10 outputs a control signal from terminal T4 to turn the first switch SW1 on and off, thereby discharging the battery 20 in a predetermined pattern and measuring the internal resistance of the battery 20. When the control unit 10 is controlling the first switch SW1, it turns off the second switch SW2. Next, as shown in Figure 9, the control unit 10 outputs a control signal from terminal T5 to turn the second switch SW2 on and off, thereby discharging the battery 20 in a predetermined pattern and measuring the internal resistance of the battery 20. When the control unit 10 is controlling the second switch SW2, it turns off the first switch SW1. The control unit 10 may use the average value of the internal resistance measured using the first discharge circuit 21A and the internal resistance measured using the second discharge circuit 21B as the internal resistance of the battery 20. By using the average value of the internal resistance measured using the first discharge circuit 21A and the internal resistance measured using the second discharge circuit 21B as the internal resistance of the battery 20, the accuracy of the measurement of the internal resistance can be improved.

[0061] Figure 10 shows another example of the control signals and a time chart of the discharge current flowing from the battery 20 when measuring the internal resistance using both the first discharge circuit 21A and the second discharge circuit 21B. The control unit 10 outputs control signals from terminals T4 and T5 so that the first switch SW1 and the second switch SW2 are turned on alternately. The control unit 10 measures the internal resistance based on the measurement results of the voltage sensor 21 and the current sensor 22 acquired when the battery 20 is being discharged with the first switch SW1 and the second switch SW2 turned on alternately.

[0062] By discharging the battery 20 using the first discharge circuit 21A and the second discharge circuit 21B, current flows through the first resistive element R1 and the third resistive element R3, causing them to heat up. However, by alternately turning on the first switch SW1 and the second switch SW2, the periods during which current flows through the first resistive element R1 and the periods during which current flows through the third resistive element R3 are lengthened, thereby suppressing the temperature rise of the first resistive element R1 and the third resistive element R3.

[0063] Furthermore, the control unit 10 may notify the ECU 3 that there is no abnormality if the first discharge circuit abnormality flag, the first current abnormality flag, the second discharge circuit abnormality flag, and the second current abnormality flag are all off. Also, if the first discharge circuit abnormality flag and the first current abnormality flag are off, the control unit 10 may notify the ECU 3 that there is no abnormality in the first discharge circuit 21A, and if the second discharge circuit abnormality flag and the second current abnormality flag are off, the control unit 10 may notify the ECU 3 that there is no abnormality in the second discharge circuit 21B.

[0064] Furthermore, the control unit 10 may also notify the ECU 3 of the occurrence of an abnormality as an alert if both the first discharge circuit abnormality flag and the second discharge circuit abnormality flag are on, or if both the first current abnormality flag and the second current abnormality flag are on. As a result, the ECU 3 can notify the user of the occurrence of the abnormality, for example, by displaying it on the instrument panel or by sounding it through a speaker. The ECU 3 may also perform a fail-safe operation when it is notified of the occurrence of an abnormality by the control unit 10. In addition, if the ECU 3 has control using internal resistance, it may switch the control, such as stopping the control using internal resistance, when it is notified of the occurrence of an abnormality by the control unit 10.

[0065] Furthermore, the control unit 10 may notify the ECU 3 of the estimated SOC, SOH, and SOF, and the ECU 3 may notify the user of the battery 20's charge level, degradation state, and discharge performance on the instrument panel based on the notified SOC, SOH, and SOF. In addition, the control unit 10 may determine whether or not to enable idle stop or replace the battery 20 based on the notified SOH and SOF, and may notify the user of the battery 20 replacement based on the determination result on the instrument panel.

[0066] According to this embodiment, in order to determine whether there is an abnormality in the first discharge circuit 21A and the second discharge circuit 21B, which are discharge paths for measuring the internal resistance value of the battery 20, it is possible to detect abnormalities in the discharge paths for detecting the state of the battery 20. Furthermore, according to this embodiment, if there is an abnormality in either the first discharge circuit 21A or the second discharge circuit 21B, the discharge path without the abnormality is used to measure the internal resistance value of the battery 20, and the discharge path with the abnormality is not used to measure the internal resistance value of the battery 20. This avoids measuring the internal resistance value using the discharge path with the abnormality, thereby improving the accuracy of measuring the internal resistance value of the battery 20. In addition, according to this embodiment, the abnormality in the first discharge circuit 21A and the second discharge circuit 21B is notified to the ECU 3, and the ECU 3 can notify the user of the occurrence of the abnormality through a display on the instrument panel or an audible sound from the speaker. Note that if there is processing in the ECU 3 that uses the internal resistance value, it may be configured to switch to processing that takes into account the abnormality of the battery 20 in response to notification from the control unit 10.

[0067] Furthermore, the control unit 10 may determine that both discharge circuits are functioning normally if the difference between the internal resistance value of the battery 20 measured using the first discharge circuit 21A and the internal resistance value of the battery 20 measured using the second discharge circuit 21B is within a predetermined range. This predetermined range is set in advance by checking for variations through testing.

[0068] For example, if the control unit 10 determines that there is no abnormality in either the first discharge circuit 21A or the second discharge circuit 21B, and the internal resistance value of the battery 20 measured using the other discharge circuit is within a predetermined range compared to the internal resistance value of the battery 20 measured using the one discharge circuit, the control unit 10 may determine that there is no abnormality in the other discharge circuit and use it to measure the internal resistance value of the battery 20. Alternatively, if one of the first discharge circuit 21A or the second discharge circuit 21B is determined to be normal, the control unit 10 may determine that there is no abnormality in the other discharge circuit if the difference between the measured reference current value, off current value, on current value, and on voltage and the reference current value, off current value, on current value, and on voltage measured using the discharge circuit that was determined to be normal is within a predetermined range.

[0069] [Second Embodiment] Figure 11 shows the power supply system of vehicle 2B according to a second embodiment of the present invention. Vehicle 2B differs in that it has a third discharge circuit 21C instead of the first discharge circuit 21A and the second discharge circuit 21B. In the following description, components that are the same as those in vehicle 2A are denoted by the same reference numerals and their descriptions are omitted, and the differences from vehicle 2A will be described.

[0070] The third discharge circuit 21C comprises a first switch SW1, a second switch SW2, and a first resistor R1. One end of the first switch SW1 is connected to the positive terminal of the battery 20, and the other end is connected to the first resistor R1. One end of the second switch SW2 is connected to the positive terminal of the battery 20, and the other end is connected to the first resistor R1. One end of the first resistor R1 is connected to the first switch SW1 and the second switch SW2, and the other end is connected to terminal T3 of the internal resistance measuring device 1 and the second resistor R2 and grounded. One end of the second resistor R2 is connected to terminal T2 of the internal resistance measuring device 1 and the negative terminal of the battery 20, and the other end is connected to terminal T3 of the internal resistance measuring device 1 and the first resistor R1 and grounded.

[0071] The first switch SW1 is turned on or off in response to a control signal supplied from terminal T4 of the internal resistance measuring device 1. The second switch SW2 is turned on or off in response to a control signal supplied from terminal T5 of the internal resistance measuring device 1. The third discharge circuit 21C discharges the battery 20 via the first resistive element R1 when the first switch SW1 or the second switch SW2 is on, and stops the discharge of the battery 20 via the third discharge circuit 21C when the first switch SW1 and the second switch SW2 are off. When the first switch SW1 is turned on or the second switch SW2 is turned on, a predetermined discharge current flows from the battery 20 through the first resistive element R1. The path consisting of the first switch SW1 and the first resistive element R1, and the path consisting of the second switch SW2 and the third resistive element R3 are examples of discharge paths for discharging the battery 20.

[0072] The processing performed by the control unit 10 in the second embodiment differs from that of the first embodiment in the test discharge processing in step S101 and the current abnormality diagnosis processing in step S104. In the test discharge processing, when the control unit 10 measures the on-current value I12 in step S210, it calculates the current value of the current flowing through the first resistive element R1 from the resistance value of the first resistive element R1 which is stored in the storage unit 11 in advance and the voltage applied to the first resistive element R1 which has been converted by the AD converter 13, and sets the calculated current value as the on-current value I12. Also, when the control unit 10 measures the on-voltage value V12 in step S211, it sets the voltage applied to the first resistive element R1 which has been converted by the AD converter 13 as the on-voltage value V12.

[0073] Figure 12 is a flowchart showing the processing flow for current abnormality diagnosis performed in step S104 in the second embodiment. First, the control unit 10 obtains the resistance value of the first resistor R1 from the storage unit 11 (step S501). If the resistance value of the first resistor R1 is temperature dependent, the resistance value of the first resistor R1 may be corrected based on the temperature measured by the temperature sensor 23. Next, the control unit 10 calculates the estimated current value Ie1 by dividing the on voltage value V11 measured in step S206 by the resistance value obtained in step S501 (step S502). The control unit 10 also calculates ΔI1 (=|on current value I11 - estimated current value Ie1|), which is the absolute value of the difference between the on current value I11 measured in step S205 and the estimated current value Ie1 calculated in step S502 (step S503).

[0074] Next, the control unit 10 determines whether the calculated ΔI1 is greater than or equal to a predetermined threshold (step S504). If ΔI1 is greater than or equal to the threshold (YES in step S504), the control unit 10 turns on the third flag (step S505). The threshold used in step S504 is a value determined in advance through experimentation. The control unit 10 also counts the number of times the third flag has been turned on. If ΔI1 is less than the threshold (NO in step S504), the control unit 10 turns off the third flag (step S506).

[0075] Next, the control unit 10 calculates the estimated current value Ie2 by dividing the on-voltage value V12 measured in step S211 by the resistance value obtained in step S501 (step S507). The control unit 10 also calculates ΔI2 (=|on-current value I12 - estimated current value Ie2|), which is the absolute value of the difference between the on-current value I12 measured in step S210 and the estimated current value Ie2 calculated in step S507 (step S508).

[0076] Next, the control unit 10 determines whether the calculated ΔI2 is greater than or equal to a predetermined threshold (step S509). If ΔI2 is greater than or equal to the threshold (YES in step S509), the control unit 10 turns on the fourth flag (step S510). The threshold used in step S509 is a value determined in advance through experimentation. The control unit 10 also counts the number of times the fourth flag has been turned on. If ΔI2 is less than the threshold (NO in step S509), the control unit 10 turns off the fourth flag (step S511).

[0077] In the second embodiment, the control unit 10 determines that there is an abnormality in the path between the first switch SW1 and the first resistor R1 when the first circuit abnormality flag is on, and determines that there is an abnormality in the path between the second switch SW2 and the first resistor R1 when the second circuit abnormality flag is on. Furthermore, the control unit 10 determines that there is an abnormality in the path between the first switch SW1 and the first resistor R1 when the first current abnormality flag is on, and determines that there is an abnormality in the path between the second switch SW2 and the first resistor R1 when the second current abnormality flag is on. Furthermore, the control unit 10 determines that there is no abnormality in the path between the first switch SW1 and the first resistor R1 when the first circuit abnormality flag and the first current abnormality flag are off, and determines that there is no abnormality in the path between the second switch SW2 and the first resistor R1 when the second circuit abnormality flag and the second current abnormality flag are off.

[0078] For example, if there are no abnormalities in the paths between the first switch SW1 and the first resistor R1, and between the second switch SW2 and the first resistor R1, the control unit 10 selects either the first switch SW1 or the second switch SW2, and uses the selected switch to discharge the battery 20 in a predetermined pattern to measure its internal resistance. The control unit 10 may select a different switch from the one used in the previous measurement of the internal resistance when selecting either the first switch SW1 or the second switch SW2. Alternatively, the control unit 10 may always select the same switch when selecting either the first switch SW1 or the second switch SW2.

[0079] If there is no abnormality in the path between the first switch SW1 and the first resistor R1, but there is an abnormality in the path between the second switch SW2 and the first resistor R1, the control unit 10 selects the first switch SW1 and uses the selected first switch SW1 to discharge the battery 20 in a predetermined pattern and measure its internal resistance. Also, if there is no abnormality in the path between the second switch SW2 and the first resistor R1, but there is an abnormality in the path between the first switch SW1 and the first resistor R1, the control unit 10 selects the second switch SW2 and uses the selected second switch SW2 to discharge the battery 20 in a predetermined pattern and measure its internal resistance.

[0080] According to this embodiment, in order to determine whether or not there is an abnormality in the third discharge circuit 21C for measuring the internal resistance value of the battery 20, it is possible to detect abnormalities in the configuration for detecting the state of the battery 20. Furthermore, according to this embodiment, if there is an abnormality in either the discharge path between the first switch SW1 and the first resistor R1, or the discharge path between the second switch SW2 and the first resistor R1, the switch related to the discharge path without an abnormality is used to measure the internal resistance value of the battery 20, and the switch related to the discharge path with an abnormality is not used to measure the internal resistance value of the battery 20. This avoids measuring the internal resistance value in the discharge path with an abnormality, thereby improving the accuracy of measuring the internal resistance value of the battery 20. Furthermore, according to this embodiment, the abnormality in the third discharge circuit 21C is notified to the ECU3, and the ECU3 can notify the user of the occurrence of the abnormality through a display on the instrument panel or an audible sound from the speaker. Note that if there is processing in the ECU3 that uses the internal resistance value, it may be configured to switch to processing that takes into account the abnormality of the battery 20 in response to notification from the control unit 10.

[0081] [Third Embodiment] Figure 13 shows the power supply system of vehicle 2C according to the third embodiment of the present invention. Vehicle 2C differs in that it has a fourth discharge circuit 21D instead of the first discharge circuit 21A and the second discharge circuit 21B. In the following description, components that are the same as those in vehicle 2A are denoted by the same reference numerals and their descriptions are omitted, and the differences from vehicle 2A will be described.

[0082] The fourth discharge circuit 21D comprises a first switch SW1, a third switch SW3, a first resistor R1, and a third resistor R3. One end of the first switch SW1 is connected to the positive terminal of the battery 20, and the other end is connected to the common terminal of the third switch SW3. The third switch SW3 is a double-throw switch, and its common terminal is connected to the first switch SW1. On the third switch SW3, one of the terminals not connected to the first switch SW1 is connected to the first resistor R1, and the other is connected to the third resistor R3. One end of the first resistor R1 is connected to the third switch SW3, and the other end is connected to the second resistor R2, the third resistor R3, and terminal T3 of the internal resistance measuring device 1, and is grounded. One end of the third resistor R3 is connected to the third switch SW3, and the other end is connected to the first resistor R1, the second resistor R2, and terminal T3 of the internal resistance measuring device 1, and is grounded. The second resistive element R2 has one end connected to terminal T2 of the internal resistance measuring device 1 and the negative terminal of the battery 20, and the other end connected to terminal T3 of the internal resistance measuring device 1, the first resistive element R1, and the third resistive element R3, and is grounded.

[0083] The first switch SW1 is turned on or off in response to a control signal supplied from terminal T4 of the internal resistance measuring device 1. The third switch SW3 is turned off in response to a control signal supplied from terminal T6 of the internal resistance measuring device 1, either connecting the first switch SW1 to the first resistance element R1, connecting the first switch SW1 to the third resistance element R3, or being turned off.

[0084] The fourth discharge circuit 21D discharges the battery 20 via the fourth discharge circuit 21D when the first switch SW1 is ON and the first switch SW1 and the first resistor R1 are connected by the third switch SW3, or when the first switch SW1 is ON and the first switch SW1 and the third resistor R3 are connected by the third switch SW3. The fourth discharge circuit 21D also stops discharging the battery 20 via the fourth discharge circuit 21D when the first switch SW1 is OFF or the third switch SW3 is OFF. When the first switch SW1 is ON and the first resistor R1 and the third resistor R3 are connected to the first switch SW1 by the third switch SW3, a predetermined discharge current flows from the battery 20. The path consisting of the first switch SW1, the third switch SW3, and the first resistor R1, and the path consisting of the first switch SW1, the third switch SW3, and the third resistor R3 are examples of discharge paths for discharging the battery 20.

[0085] The processing performed by the control unit 10 in the third embodiment differs from that of the first embodiment in the test discharge process in step S101. Figure 14 is a flowchart showing the flow of the test discharge process performed in step S101 in the third embodiment. First, the control unit 10 turns off the first switch SW1 and the third switch SW3 (step S601). Next, the control unit 10 measures a reference current value, which is the reference value of the current flowing from the battery 20 when the first switch SW1 and the third switch SW3 are off (step S602). Next, the control unit 10 measures an off current value I1, which is the current value of the current flowing from the battery 20 after step S602 when the first switch SW1 and the third switch SW3 are off (step S603).

[0086] Next, the control unit 10 turns on the first switch SW1 and the third switch SW3 to connect the first switch SW1 and the first resistor R1 (step S604). With the first switch SW1 turned on and the first switch SW1 and the first resistor R1 connected, the control unit 10 measures the on-current value I11, which is the current value of the current flowing from the battery 20 (step 605), and measures the on-voltage value V11, which is the voltage value of the voltage across the first resistor R1 (step S606).

[0087] Next, the control unit 10 turns off the first switch SW1 and then the third switch SW3 (step S607).

[0088] Next, the control unit 10 waits for a predetermined time with the first switch SW1 and the third switch SW3 in the OFF state (step S608). After waiting for the predetermined time, the control unit 10 turns on the first switch SW1 and the third switch SW3, thereby connecting the first switch SW1 and the third resistor R3 (step S609). With the first switch SW1 ON and the first switch SW1 and the third resistor R3 connected, the control unit 10 measures the ON current value I12, which is the current value of the current flowing from the battery 20 (step S610), and measures the ON voltage value V12, which is the voltage value of the voltage across the third resistor R3 (step S611). Next, the control unit 10 turns off the first switch SW1 and the third switch SW3 (step S612), ending the test discharge process.

[0089] In the third embodiment, the control unit 10 determines that there is an abnormality in the path between the first switch SW1 and the first resistor R1 when the first circuit abnormality flag is on, and determines that there is an abnormality in the discharge path between the first switch SW1, the third switch SW3, and the first resistor R1 when the first current abnormality flag is on. Furthermore, the control unit 10 determines that there is an abnormality in the discharge path between the first switch SW1, the third switch SW3, and the third resistor R3 when the second circuit abnormality flag is on, and determines that there is an abnormality in the discharge path between the first switch SW1, the third switch SW3, and the third resistor R3 when the second current abnormality flag is on. Furthermore, the control unit 10 determines that there is no abnormality in the discharge path between the first switch SW1, the third switch SW3, and the first resistor R1 when the first circuit abnormality flag and the first current abnormality flag are off, and determines that there is no abnormality in the discharge path between the first switch SW1, the third switch SW3, and the third resistor R3 when the second circuit abnormality flag and the second current abnormality flag are off.

[0090] In the third embodiment, the control unit 10, for example, if there are no abnormalities in both the discharge path including the first resistive element R1 and the discharge path including the third resistive element R3, selects one of the discharge paths and measures the internal resistance value of the battery 20 using the selected discharge path. The control unit 10 may also select a different discharge path from the one used in the previous measurement of the internal resistance value when selecting one of the two discharge paths. Alternatively, the control unit 10 may always select the same discharge path when selecting one of the two discharge paths.

[0091] If there is no abnormality in the discharge path including the first resistive element R1, but there is an abnormality in the discharge path including the third resistive element R3, the control unit 10 selects the discharge path including the first resistive element R1 and measures the internal resistance value of the battery 20 using the selected discharge path. If there is no abnormality in the discharge path including the third resistive element R3, but there is an abnormality in the discharge path including the first resistive element R1, the control unit 10 selects the discharge path including the third resistive element R3 and measures the internal resistance value of the battery 20 using the selected discharge path.

[0092] When the control unit 10 selects a discharge path including the first resistive element R1, it connects the first switch SW1 and the first resistive element R1 using a control signal from terminal T6, and alternately turns the first switch SW1 on and off using a control signal from terminal T4 to discharge the battery 20 in a predetermined discharge pattern. The control unit 10 then measures the voltage and current of the battery 20 and determines the internal resistance value of the battery 20 from the measurement results. Furthermore, when the control unit 10 selects a discharge path including the third resistive element R3, it connects the first switch SW1 and the third resistive element R3 using a control signal from terminal T6, and alternately turns the first switch SW1 on and off using a control signal from terminal T4 to discharge the battery 20 in a predetermined discharge pattern. The control unit 10 then measures the voltage and current of the battery 20 and determines the internal resistance value of the battery 20 from the measurement results.

[0093] According to this embodiment, in order to determine whether or not there is an abnormality in the fourth discharge circuit 21D for measuring the internal resistance value of the battery 20, it is possible to detect abnormalities in the configuration for detecting the state of the battery 20. Furthermore, according to this embodiment, if there is an abnormality in either the discharge path including the first resistive element R1 or the discharge path including the third resistive element R3, the discharge path without the abnormality is used to measure the internal resistance value of the battery 20, and the discharge path with the abnormality is not used to measure the internal resistance value of the battery 20. This avoids measuring the internal resistance value using the discharge path with the abnormality, and improves the accuracy of measuring the internal resistance value of the battery 20.

[0094] In the third embodiment, the fourth discharge circuit 21D may be configured not to have the first switch SW1. In this case, in steps S601 and S607, the control unit 10 sets the common terminal of the third switch SW3 to an off state, where it is not connected to either the first resistor R1 or the third resistor R3. In the configuration where the fourth discharge circuit 21D does not have the first switch SW1, the internal resistance value of the battery 20 is measured by switching between an off state, where the common terminal of the third switch SW3 is not connected to either the first resistor R1 or the third resistor R3, and a state, where the common terminal of the third switch SW3 is connected to either the first resistor R1 or the third resistor R3, thereby discharging the battery 20 in a predetermined pattern.

[0095] [Fourth Embodiment] Figure 15 shows the power supply system of vehicle 2D according to the fourth embodiment of the present invention. Vehicle 2D differs in that it has a fifth discharge circuit 21E instead of the first discharge circuit 21A and the second discharge circuit 21B. In the following description, components that are the same as those in vehicle 2A are denoted by the same reference numerals and their descriptions are omitted, and the differences from vehicle 2A will be described.

[0096] The fifth discharge circuit 21E includes a first switch SW1, a second switch SW2, a third switch SW3, a first resistor R1, and a third resistor R3. One end of the first switch SW1 and the second switch SW2 are connected to the positive terminal of the battery 20, and the other end is connected to the third switch SW3. The third switch SW3 is a double-throw switch, and its common terminal is connected to the first switch SW1 and the second switch SW2. On the third switch SW3, one of the terminals not connected to the first switch SW1 is connected to the first resistor R1, and the other is connected to the third resistor R3. One end of the first resistor R1 is connected to the third switch SW3, and the other end is connected to the second resistor R2, the third resistor R3, and terminal T3 of the internal resistance measuring device 1, and is grounded. The third resistor R3 has one end connected to the third switch SW3, and the other end connected to the first resistor R1, the second resistor R2, and terminal T3 of the internal resistance measuring device 1, and is grounded. The second resistor R2 has one end connected to terminal T2 of the internal resistance measuring device 1 and the negative terminal of the battery 20, and the other end connected to terminal T3 of the internal resistance measuring device 1, the first resistor R1, and the third resistor R3, and is grounded.

[0097] The first switch SW1 is turned on or off in response to a control signal supplied from terminal T4 of the internal resistance measuring device 1. The second switch SW2 is turned on or off in response to a control signal supplied from terminal T5 of the internal resistance measuring device 1. The third switch SW3 is turned off in response to a control signal supplied from terminal T6 of the internal resistance measuring device 1, either connecting the first switch SW1 to the first resistance element R1, connecting the first switch SW1 to the third resistance element R3, or being off.

[0098] The fifth discharge circuit 21E discharges the battery 20 via the fifth discharge circuit 21E when the first switch SW1 or the second switch SW2 is ON and the third switch SW3 is ON. The fifth discharge circuit 21E also stops discharging the battery 20 via the fifth discharge circuit 21E when the first switch SW1 is OFF and the second switch SW2 is OFF, or when the third switch SW3 is OFF. The first resistor R1 and the third resistor R3 allow a predetermined discharge current to flow from the battery 20 when the first switch SW1 or the second switch SW2 is ON and the third switch SW3 is not OFF. The path consisting of the first switch SW1, the third switch SW3, and the first resistor R1, and the path consisting of the second switch SW2, the third switch SW3, and the third resistor R3 are examples of discharge paths for discharging the battery 20.

[0099] The processing performed by the control unit 10 in the fourth embodiment differs from that of the first embodiment in the test discharge process in step S101. Figure 16 is a flowchart showing the flow of the test discharge process performed in step S101 in the fourth embodiment. First, the control unit 10 turns off the first switch SW1, the second switch SW2, and the third switch SW3 (step S701). Next, the control unit 10 measures a reference current value, which is the reference value of the current flowing from the battery 20 when the first switch SW1, the second switch SW2, and the third switch SW3 are off (step S702). Next, the control unit 10 measures an off current value I1, which is the current value of the current flowing from the battery 20 after step S702 when the first switch SW1, the second switch SW2, and the third switch SW3 are off (step S703).

[0100] Next, the control unit 10 turns on the first switch SW1, turns off the second switch SW2, and turns on the third switch SW3 to connect the first switch SW1 and the first resistor R1 (step S704). The control unit 10 measures the on-current value I11, which is the current value of the current flowing from the battery 20 when the first switch SW1 is on and the first switch SW1 and the first resistor R1 are connected (step 705).

[0101] Next, the control unit 10 turns on the first switch SW1, turns off the second switch SW2, and turns on the third switch SW3 to measure the on-voltage value V11, which is the voltage value across the first resistor R1 when the first switch SW1 and the first resistor R1 are connected (step S706). Next, the control unit 10 turns off the first switch SW1, the second switch SW2, and the third switch SW3 (step S707).

[0102] Next, the control unit 10 waits for a predetermined time with the first switch SW1, the second switch SW2, and the third switch SW3 in the OFF state (step S708). After waiting for the predetermined time, the control unit 10 turns off the first switch SW1, turns on the second switch SW2, and turns on the third switch SW3 to connect the second switch SW2 and the third resistor R3 (step S709). The control unit 10 measures the ON current value I12, which is the current value of the current flowing from the battery 20 when the second switch SW2 is ON and the second switch SW2 and the third resistor R3 are connected (step S710).

[0103] Next, the control unit 10 turns off the first switch SW1, turns on the second switch SW2, and turns on the third switch SW3 to measure the on-voltage value V12, which is the voltage value across the third resistor R3 when the second switch SW2 and the third resistor R3 are connected (step S711). Next, the control unit 10 turns off the first switch SW1, the second switch SW2, and the third switch SW3 (step S712) to end the test discharge process.

[0104] In the fourth embodiment, the control unit 10 determines that there is an abnormality in the discharge path including the first switch SW1, the third switch SW3, and the first resistor R1 when the first circuit abnormality flag is on, and determines that there is an abnormality in the discharge path including the second switch SW2, the third switch SW3, and the third resistor R3 when the second circuit abnormality flag is on. Furthermore, the control unit 10 determines that there is an abnormality in the discharge path including the first switch SW1, the third switch SW3, and the first resistor R1 when the first current abnormality flag is on, and determines that there is an abnormality in the discharge path including the second switch SW2, the third switch SW3, and the third resistor R3 when the second current abnormality flag is on. Furthermore, if the first circuit abnormality flag and the first current abnormality flag are off, the control unit 10 determines that there is no abnormality in the discharge path including the first switch SW1, the third switch SW3, and the first resistor R1, and if the second circuit abnormality flag and the second current abnormality flag are off, the control unit 10 determines that there is no abnormality in the discharge path including the second switch SW2, the third switch SW3, and the third resistor R3.

[0105] For example, if there are no abnormalities in either path, the control unit 10 selects one of the discharge paths and uses the selected discharge path to discharge the battery 20 in a predetermined pattern and measure its internal resistance. The control unit 10 may also select a different discharge path from the two abnormal discharge paths when selecting one of them, compared to the path used in the previous measurement of internal resistance. Furthermore, the control unit 10 may always select the same discharge path when selecting one of the discharge paths.

[0106] If there is no abnormality in the discharge path including the first switch SW1, the third switch SW3, and the first resistor R1, but there is an abnormality in the discharge path including the second switch SW2, the third switch SW3, and the third resistor R3, the control unit 10 selects the discharge path including the first switch SW1, the third switch SW3, and the first resistor R1, and uses the selected discharge path to discharge the battery 20 in a predetermined pattern and measure the internal resistance value. Alternatively, if there is no abnormality in the discharge path including the second switch SW2, the third switch SW3, and the third resistor R3, but there is an abnormality in the discharge path including the first switch SW1, the third switch SW3, and the first resistor R1, the control unit 10 selects the discharge path including the second switch SW2, the third switch SW3, and the third resistor R3, and uses the selected discharge path to discharge the battery 20 in a predetermined pattern and measure the internal resistance value.

[0107] According to this embodiment, in order to determine whether or not there is an abnormality in the fifth discharge circuit 21E for measuring the internal resistance value of the battery 20, it is possible to detect abnormalities in the configuration for detecting the state of the battery 20. Furthermore, according to this embodiment, if there is an abnormality in one of the two discharge paths, the discharge path without the abnormality is used to measure the internal resistance value of the battery 20, and the discharge path with the abnormality is not used to measure the internal resistance value of the battery 20. This avoids measuring the internal resistance value using the discharge path with the abnormality, and improves the accuracy of measuring the internal resistance value of the battery 20.

[0108] [Differentiation] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above and can be implemented in various other forms. For example, the present invention may be implemented by modifying the embodiments described above as follows. The embodiments described above and the following modifications may be combined with each other. The present invention is also included in configurations that appropriately combine the components of each embodiment and each modification described above. Furthermore, further effects and modifications can be easily derived by those skilled in the art. Therefore, broader embodiments of the present invention are not limited to the embodiments and modifications described above, and various modifications are possible.

[0109] In the embodiment described above, the resistance value of the first resistive element R1 and the resistance value of the third resistive element R3 may be different.

[0110] In this invention, the internal resistance measuring device 1 and each discharge circuit may be retrofitted to the battery 20.

[0111] In the embodiment described above, the processing in step S103 and the processing in step S104 may be executed in parallel.

[0112] In the embodiment described above, if the result in step S105 is NO, the process in step S103, i.e., the process in Figure 7, is executed multiple times. However, the threshold value used in step S301 may be different each time it is executed.

[0113] In the present invention, a determination may be made before step S103 whether or not to execute the processes from step S103 onward. For example, the control unit 10 may execute the processes from step S103 onward if the conditions that the ON voltage is greater than or equal to a predetermined voltage value and the OFF current value is less than or equal to a predetermined value are met, and terminate the process shown in Figure 4 if these conditions are not met.

[0114] In the present invention, if each switch is an Intelligent Power Device (IPD) having a semiconductor switch, the IPD may detect the state of its own semiconductor switch, and the control unit 10 may acquire the state of the semiconductor switch detected by the IPD. In this case, if the acquired state indicates that the semiconductor switch is abnormal, the control unit 10 may determine that the discharge path including the semiconductor switch is abnormal.

[0115] In the present invention, a current sensor for measuring a reference current value, an off-current value, and an on-current value, and a voltage sensor for measuring the voltage of the battery 20 may be provided externally to the internal resistance measuring device 1.

[0116] In the embodiment described above, the internal resistance measuring device 1 provided in the vehicle 2A performs various diagnoses and measures the internal resistance value of the battery 20, but these processes may also be performed by the ECU 3. Figure 17 is a block diagram showing the configuration of an embodiment in which the ECU 3 performs various diagnoses and detects the state of the battery 20.

[0117] ECU3 includes a control unit 30, a memory unit 31, a communication unit 32, an AD converter 33, and a bus (not shown). The control unit 30, like control unit 10, includes a CPU, ROM, and RAM. The control unit 30 may be configured with a DSP, FPGA, or ASIC instead of a CPU. The CPU, ROM, RAM, memory unit 31, communication unit 32, and AD converter 33 are interconnected by a bus, and information is exchanged between them. The memory unit 31 is composed of non-volatile memory and stores, for example, the resistance values ​​of each of the aforementioned resistor elements and the various threshold values ​​mentioned above.

[0118] When the CPU executes a program stored in ROM, the control unit 30 implements a measurement unit 301, a determination unit 302, and an internal resistance calculation unit 303. The measurement unit 301 measures the voltage of the battery 20 and the current flowing from the battery 20 in a predetermined pattern using an AD converter 33. The determination unit 302 determines whether there is an abnormality in the discharge path that discharges the battery 20 in a predetermined pattern, based on the measurement results of the measurement unit 301. The internal resistance calculation unit 303 calculates the internal resistance value of the battery 20 based on the measurement results of the measurement unit 301 when the battery 20 is discharged in a predetermined pattern in a discharge path that the determination unit 302 determined to be free of abnormalities. The first discharge circuit 21A, the second discharge circuit 21B, the measurement unit 301, the determination unit 302, and the internal resistance calculation unit 303 function as an internal resistance measurement system.

[0119] The control unit 30 performs the same processing as the control unit 10 in the first embodiment to determine whether there is an abnormality in the first discharge circuit 21A and the second discharge circuit 21B. Depending on the result of determining whether there is an abnormality in the first discharge circuit 21A and the second discharge circuit 21B, the control unit 30 selects one of the first discharge circuit 21A and the second discharge circuit 21B according to a predetermined rule, and measures the internal resistance value of the battery 20 using the selected discharge circuit.

[0120] In this configuration, since the presence or absence of abnormalities is determined for the first discharge circuit 21A and the second discharge circuit 21B used to measure the internal resistance of the battery 20, it is possible to detect abnormalities in the configuration for detecting the state of the battery 20. Furthermore, in this configuration, if there is an abnormality in either the first discharge circuit 21A or the second discharge circuit 21B, the discharge circuit without the abnormality is used to measure the internal resistance of the battery 20, and the discharge circuit with the abnormality is not used to measure the internal resistance of the battery 20. This avoids measuring the internal resistance using the discharge circuit with the abnormality, thereby improving the accuracy of measuring the internal resistance of the battery 20.

[0121] Furthermore, in the present invention, a server device connected to a communication network may perform various diagnoses and measure the internal resistance value of the battery 20. Figure 18 is a block diagram showing the configuration of an embodiment in which the server device 4 performs various diagnoses and detects the state of the battery 20.

[0122] The server device 4 includes a control unit 40, a storage unit 41, a communication unit 42, and a bus (not shown). The control unit 40, like the control unit 10, includes a CPU, ROM, and RAM. The CPU, ROM, RAM, storage unit 41, and communication unit 42 are interconnected by the bus and exchange information between them. The communication unit 42 communicates with the internal resistance measuring device 1 via the communication network 1000 and exchanges information with the internal resistance measuring device 1. The storage unit 41 stores, for example, the resistance values ​​of each of the aforementioned resistive elements and the various threshold values ​​mentioned above. The server device 4 may also have a user interface including a mouse or keyboard for inputting information and a display device for displaying information.

[0123] When the CPU executes a program stored in ROM, the control unit 40 realizes a determination unit 402 and an internal resistance calculation unit 403. The determination unit 402 determines whether there is an abnormality in the discharge path that discharges the battery 20 in a predetermined pattern, based on the measurement results of the measurement unit 101. The internal resistance calculation unit 403 calculates the internal resistance value of the battery 20 based on the measurement results of the measurement unit 101 when the battery 20 is discharged in a predetermined pattern using a discharge path that the determination unit 402 determined to be free of abnormalities. The measurement unit 101, determination unit 402, and internal resistance calculation unit 403 function as an internal resistance measurement system.

[0124] The control unit 10 performs the process shown in Figure 5 and transmits the reference current value, off current value, on current value, and on voltage value measured by the measurement unit 101 to the server device 4 via wireless communication from the communication unit 12 through the communication network 1000. The control unit 40 receives the transmitted reference current value, off current value, on current value, and on voltage value and uses the received reference current value, off current value, on current value, and on voltage value to perform the discharge circuit diagnosis process in step S103 and the current abnormality diagnosis process in step S104. Based on the results of the discharge circuit diagnosis process and the current abnormality diagnosis process, the control unit 40 sets a circuit abnormality flag and a current abnormality flag. Based on the set circuit abnormality flag and current abnormality flag, the control unit 40 selects a discharge path to be used to measure the internal resistance value of the battery 20. The control unit 40 transmits a measurement instruction for the internal resistance value on the selected discharge path to the internal resistance measuring device 1. Upon receiving the measurement instruction, the control unit 10 discharges the battery 20 in a predetermined pattern on the specified discharge path. The control unit 10 transmits the measurement results of the voltage and current values ​​when the battery 20 is discharging in a predetermined pattern to the server device 4. The control unit 40 calculates the internal resistance value of the battery 20 using the measurement results of the voltage and current values ​​transmitted from the internal resistance measuring device 1.

[0125] In this configuration, since the presence or absence of abnormalities is determined for the first discharge circuit 21A and the second discharge circuit 21B used to measure the internal resistance of the battery 20, it is possible to detect abnormalities in the configuration for detecting the state of the battery 20. Furthermore, in this configuration, if there is an abnormality in either the first discharge circuit 21A or the second discharge circuit 21B, the discharge circuit without the abnormality is used to measure the internal resistance of the battery 20, and the discharge circuit with the abnormality is not used to measure the internal resistance of the battery 20. This avoids measuring the internal resistance using the discharge circuit with the abnormality, thereby improving the accuracy of measuring the internal resistance of the battery 20. In addition, the processing performed by the server device 4 may be executed by a terminal device such as a personal computer connected to the communication network 1000.

[0126] Furthermore, the server device 4 may store the received reference current value, off current value, on current value, and on voltage as history, and update various thresholds by learning the stored values. Also, when the internal resistance measuring device 1 performs various diagnoses and measures the internal resistance value of the battery 20, the thresholds stored in the internal resistance measuring device 1 may be updated with the thresholds updated by the server device 4. If the thresholds stored in the internal resistance measuring device 1 are updated from the server device 4 at predetermined timings, the thresholds can be updated to values ​​suitable for diagnosis.

[0127] In the above-described embodiment, the vehicle has the internal resistance measuring device 1 and the aforementioned discharge circuit. However, mobile bodies such as motorboats and other vessels, drones and other aircraft, agricultural machinery, and construction machinery may also have the internal resistance measuring device 1 and the aforementioned discharge circuit, and the internal resistance measuring device 1 may diagnose the discharge circuit and measure the internal resistance value of the battery in the vessel, aircraft, agricultural machinery, or construction machinery. Furthermore, the devices having the internal resistance measuring device 1 and discharge circuit are not limited to mobile bodies. Devices using batteries 20 in gas, water, railway, communication, and power facilities may also have the internal resistance measuring device 1 and discharge circuit, and the internal resistance measuring device 1 may diagnose the discharge circuit and measure the internal resistance value of the battery.

[0128] In the embodiment described above, only the engine 26 outputs driving force in vehicles 2A to 2D. However, vehicles 2A to 2D may be electric vehicles such as hybrid vehicles equipped with an electric motor to assist the engine 26, or electric vehicles driven by an electric motor. In the case of a hybrid vehicle, the battery 20 starts a high-voltage system (a system that drives the electric motor) composed of a lithium battery or the like, and the high-voltage system starts the engine 26. Also, if vehicle 2 is an electric vehicle, the high-voltage system drives the electric motor to propel the vehicle. [Explanation of symbols]

[0129] 1. Internal resistance measuring device 2A, 2B, 2C, 2D vehicles 3 ECU 4 Server devices 10 Control Unit 11 Storage section 12 Communications Department 13, 33 AD converters 14 bus 20 batteries 21A 1st discharge circuit 21B 2nd discharge circuit 21C 3rd discharge circuit 21D 4th discharge circuit 21E 5th discharge circuit 101, 301 Measuring section 102, 302 Judgment section 103, 303, 403 Internal resistance calculation unit SW1 1st switch SW2 Second Switch SW3 3rd Switch R1 is the first resistor element. R2 is the second resistor element R3 is the third resistor element.

Claims

1. A measuring unit that measures the voltage of a rechargeable battery and the current flowing from the battery through a plurality of discharge paths that include a switch connected to the battery and a resistive element connected in series with the switch, and which discharge the battery when the switch is ON. A determination unit that determines whether or not there is an abnormality in the discharge path based on the current value measured by the measurement unit when the switch is off in the discharge path and the current value measured by the measurement unit when the switch is on in the discharge path. An internal resistance calculation unit discharges the battery in a predetermined discharge pattern along the discharge path determined by the determination unit to be free of abnormalities, and calculates the internal resistance value of the battery from the voltage and current measured by the measurement unit while the battery is being discharged in the discharge pattern. An internal resistance measurement system equipped with the following features.

2. If the determination unit determines that there are no abnormalities in the multiple discharge paths, the internal resistance calculation unit selects a discharge path that discharges the battery in a predetermined pattern according to a predetermined rule. The internal resistance measurement system according to claim 1.

3. If the determination unit determines that there are no abnormalities in the multiple discharge paths, the internal resistance calculation unit calculates the average value of the internal resistance values ​​calculated for each of the multiple discharge paths as the internal resistance value of the battery. The internal resistance measurement system according to claim 2.

4. The internal resistance calculation unit switches the discharge path each time the battery is discharged if the determination unit determines that there are no abnormalities in the multiple discharge paths. The internal resistance measurement system according to claim 2.

5. A measuring unit that measures the voltage of a rechargeable battery and the current flowing from the battery through a plurality of discharge paths that include a switch connected to the battery and a resistive element connected in series with the switch, and which discharge the battery when the switch is ON. A determination unit that determines whether or not there is an abnormality in the discharge path based on the current value measured by the measurement unit when the switch is off in the discharge path and the current value measured by the measurement unit when the switch is on in the discharge path. An internal resistance calculation unit discharges the battery in a predetermined discharge pattern along the discharge path determined by the determination unit to be free of abnormalities, and calculates the internal resistance value of the battery from the voltage and current measured by the measurement unit while the battery is being discharged in the discharge pattern. An internal resistance measuring device equipped with the following features.

6. A measurement step of measuring the voltage of a rechargeable battery and the current flowing from the battery through a plurality of discharge paths that include a switch connected to the battery and a resistive element connected in series with the switch, and which discharge the battery when the switch is on. A determination step that determines whether or not there is an abnormality in the discharge path based on the current value measured in the measurement step when the switch is off in the discharge path and the current value measured in the measurement step when the switch is on in the discharge path. An internal resistance calculation step in which the battery is discharged in a predetermined discharge pattern in the discharge path determined to be free of abnormalities in the determination step, and the internal resistance value of the battery is calculated from the voltage and current measured in the measurement step while the battery is being discharged in the discharge pattern, An internal resistance measurement method comprising the following features.

Images