JP2019161889A - Battery monitoring device and battery monitoring method - Google Patents

Abstract

To provide a battery monitoring device and a battery monitoring method, capable of simply synchronizing a measurement current and a measurement voltage.SOLUTION: A battery monitoring device 2 monitors a battery pack 10 constructed by a plurality of battery cells C serially connected. The battery monitoring device 2 comprises: a cell voltage measurement part 21 that sequentially measures an inter-terminal voltage of a plurality of division cells obtained by dividing the plurality of battery cells C into two or more with a prescribed time interval; a current measurement part 23 that measures repeatedly a current flowing in the battery pack 10 in the time interval shorter than the prescribed time interval of the cell voltage measurement part 21; a control part 24 that holds the plurality of currents measured repeatedly by the current measurement part 23, and in which the cell voltage measurement part 21 selects the current measured at the timing corresponding to the timing that the inter-terminal voltage of any one of division cells from the plurality of currents; and a monitoring part 240 that monitors a battery state on the basis of the inter-terminal voltage measured at the timing and the current selected by the control part 24.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a battery monitoring apparatus and a battery monitoring method for monitoring the state of a secondary battery.

  As said battery monitoring apparatus, what monitors the assembled battery which consists of secondary batteries, such as a lithium ion secondary battery and a nickel-hydrogen secondary battery, is known. The battery monitoring device detects the voltage between terminals of each battery cell constituting the assembled battery, or detects the current flowing through the battery cell based on the state of the battery cell. Monitor for appropriateness. For example, Patent Document 1 discloses an example of such a battery monitoring device.

  The battery monitoring device described in Patent Literature 1 monitors a battery pack in which a plurality of battery cells are connected in series. The battery monitoring device includes: a first voltage measuring unit that measures a voltage between terminals of each of a plurality of battery cells; and both ends of a battery cell group in which at least two of the plurality of battery cells are connected in series. A second voltage measurement unit that measures a voltage and a current measurement unit that measures a current flowing through the assembled battery are provided. In addition, the battery monitoring device includes a cell voltage ratio calculation unit that calculates a cell voltage ratio of each of the plurality of battery cells based on the inter-terminal voltage measured by the first voltage measurement unit, and the cell voltage ratio and the second voltage measurement. And a cell voltage calculation unit that calculates cell voltages of the plurality of battery cells at the time of measurement of the both-end voltage based on the both-end voltage measured by the unit. In addition, the battery monitoring device sends a trigger signal for obtaining a set of the both-end voltage measured by the second voltage measuring unit and the current value measured by the current measuring unit to the second voltage measuring unit and the current measuring unit. A trigger signal generator for inputting each of them is provided.

Japanese Patent Laying-Open No. 2015-203593

  According to the battery monitoring apparatus described in Patent Document 1, the voltage across the battery cell group and the current value flowing through the assembled battery are acquired as a set using a trigger signal. In addition, in order to calculate the cell voltage ratio, it is also necessary to acquire a voltage between terminals of the battery cells to be compared as a set. However, if the measurement current and the measurement voltage are to be synchronized, the measurement circuit and the arithmetic processing tend to be complicated.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a battery monitoring device and a battery monitoring method capable of easily synchronizing a measurement current and a measurement voltage.

  A battery monitoring apparatus that solves the above-described problem is a battery monitoring apparatus for an assembled battery including a plurality of battery cells connected in series, and a plurality of divided cells obtained by dividing the plurality of battery cells into two or more. A voltage measuring unit that sequentially measures the voltage between the terminals at a predetermined time interval, a current measuring unit that repeatedly measures the current flowing through the assembled battery at a time interval shorter than the predetermined time interval of the voltage measuring unit, and A plurality of currents that are repeatedly measured by a current measuring unit, and a plurality of currents that are measured at a timing corresponding to a timing at which the voltage measuring unit measures a voltage between terminals of any one of the divided cells. And a monitoring unit that monitors the battery state based on the inter-terminal voltage measured at the timing and the current selected by the synchronization unit.

  A battery monitoring method for solving the above problem is a battery monitoring method for monitoring an assembled battery composed of a plurality of battery cells connected in series, and a plurality of battery cells obtained by dividing the plurality of battery cells into two or more. A voltage measurement step of sequentially measuring the voltage between the terminals of the divided cells at a predetermined time interval; and a current measurement step of repeatedly measuring the current flowing through the assembled battery at a time interval shorter than the predetermined time interval of the voltage measurement step; Holding a plurality of currents repeatedly measured in the current measuring step, and holding the current measured at a timing corresponding to a timing at which a voltage between terminals of any one of the segmented cells is measured in the voltage measuring step. Monitoring a battery state based on a synchronization step selected from a plurality of currents, a voltage between terminals measured at the timing, and a current selected in the synchronization step And a degree.

  Since the current and voltage of the battery cell in use constantly change, it is necessary to synchronize the measurement timing of the voltage and the current when monitoring the state of the battery cell. In this respect, according to such a configuration or method, since the current is repeatedly measured at a time interval shorter than the predetermined time interval at which the voltage is measured, the current corresponding to the voltage measurement timing can be measured. Thus, a voltage and a current whose measurement timing is synchronized can be obtained. That is, since the current synchronized with the voltage measurement timing is measured, the voltage is measured for synchronization for each of the plurality of divided cells obtained by dividing the plurality of battery cells into two or more, for example, for each battery cell. And it is not necessary to memorize | store, and the process with respect to a voltage can be simplified. As a result, the measurement current and the measurement voltage can be easily synchronized.

  As a preferred configuration, the monitoring unit monitors the state of the assembled battery based on an internal resistance calculated based on the inter-terminal voltage measured at the timing and the current selected by the synchronization unit.

  According to such a configuration, even when the battery is in use, the internal resistance that is one index indicating the battery state is obtained with high accuracy. Then, the battery state can be monitored based on the acquired internal resistance.

  As a preferred configuration, the current measurement unit is a ΔΣ AD converter, and outputs a digital signal of the measured current, and the synchronization unit holds the digital signal of the measured current output from the current measurement unit. The current measured at the corresponding timing is selected from the held digital signal.

According to such a configuration, it is possible to easily select the current measured at the timing corresponding to the timing at which the voltage measurement unit measures the voltage.
As a preferred configuration, the battery cell is a lithium ion secondary battery.

  According to such a configuration, it is possible to easily monitor the internal resistance of a lithium ion secondary battery that is preferably monitored for each battery cell.

  According to the present invention, the measurement current and the measurement voltage can be easily synchronized.

The block diagram which shows the schematic structure about one Embodiment which actualized the battery monitoring apparatus. The time chart which shows the measurement timing of an electric current and a voltage in the same embodiment. The block diagram which shows the current measurement in a delta-sigma type AD converter in the same embodiment. The time chart which shows the aspect of the electric current measured in the embodiment.

An embodiment in which the battery monitoring device and the battery monitoring method are embodied will be described with reference to FIGS.
As shown in FIG. 1, the battery monitoring device 2 is provided in an electric vehicle drive device 100 on which the battery system 1 is mounted. The electric vehicle drive device is a system that drives an electric vehicle such as a hybrid vehicle.

  The electric vehicle drive device 100 includes a battery system 1 having a battery monitoring device 2 and an assembled battery 10, a vehicle controller 30 that controls the entire vehicle, an inverter 40, an electric motor 50, and the like. The battery system 1 is connected to the inverter 40 via relays 60 and 61. The battery monitoring device 2 performs communication with the inverter 40 and the vehicle controller 30 via a CAN (Controller Area Network) communication bus.

  The electric motor 50 is rotationally driven by the electric power from the inverter 40. When the vehicle starts and accelerates, discharge power is supplied from the battery system 1 to the electric motor 50 through the inverter 40, and an engine (not shown) is assisted by the driving force of the electric motor 50. When the vehicle is stopped and decelerated, the regenerative electric power from the electric motor 50 charges the assembled battery 10 provided in the battery system 1 through the inverter 40. The inverter 40 includes a motor controller 41, and controls the DC-AC conversion and AC-DC conversion of the inverter 40, thereby performing rotation drive control of the electric motor 50 and charge / discharge control of the assembled battery 10.

  The battery system 1 includes an assembled battery 10, a battery monitoring device 2, and a current measuring element 9. The assembled battery 10 is configured by electrically connecting a plurality of battery cells C (C (1) to C (N)) as segment cells, which are the minimum unit, in series. The assembled battery 10 includes, for example, about 50 to 100 battery cells C connected in series. Hereinafter, the number of the battery cells C constituting the assembled battery 10 is N, and the battery cell C is represented as a representative of one of the N battery cells C (1) to C (N). The battery cell C is a chargeable / dischargeable battery such as a lithium ion secondary battery. For example, the assembled battery 10 is configured by connecting a plurality of (L sets in FIG. 1) cell blocks B1 to BL grouped in a predetermined number (four in FIG. 1) of battery cells C in series. Yes.

  The battery monitoring device 2 is a device that monitors the state of the assembled battery 10. An overcharge / discharge detection function that detects overcharge and overdischarge of each battery cell C of the assembled battery 10, and each battery cell C of the assembled battery 10. It has an internal resistance detection function for detecting internal resistance. The battery monitoring device 2 includes a cell voltage measurement unit 21, a total voltage measurement unit 22, a current measurement unit 23, and a control unit 24 as a synchronization unit.

  The cell voltage measuring unit 21 measures a voltage for each cell of the battery cells C constituting the assembled battery 10 (hereinafter, cell voltage). The cell voltage measurement unit 21 includes a plurality (L pieces) of cell voltage measurement circuits CC1 to CCL corresponding to the cell blocks B1 to BL. The cell voltage measurement circuits CC1 to CCL are circuits that can measure the cell voltages of about 4 to 12 battery cells C, and may be configured as an integrated circuit (IC).

  The total voltage measurement unit 22 is a circuit that measures the voltage across the N battery cells C constituting the assembled battery 10 (hereinafter, the total voltage Vt). Assuming that N battery cells C are battery cells C (1), C (2),..., C (N-1), C (N) from the assembled battery negative electrode side, the total voltage of the total voltage measuring unit 22 The meter input terminals 220a and 220b are connected to the negative electrode of the battery cell C (1) and the positive electrode of the battery cell C (N), respectively.

  Each cell voltage measurement circuit CC1-CCL measures the voltage between the terminals of each battery cell C for every cell block B1-BL. Although not shown, the cell voltage measurement circuits CC1 to CCL communicate with the balancing resistors and balancing switches that perform the balancing operation of the cell voltages of the battery cells C (1) to C (N) and the control unit 24 to perform control. The logic part which performs is provided.

  The current measuring unit 23 measures the current flowing through the assembled battery 10. A measurement signal (electric signal) is input from the current measurement element 9 to the current measurement unit 23. The current measuring element 9 is an element that converts the magnitude of the current into an electric signal. An electric signal corresponding to the magnitude of the current is output from the current measuring element 9, and the electric signal is measured by the current measuring unit 23. The current measuring element 9 is, for example, a Hall element sensor or a shunt resistor element. For example, since the offset current of the shunt resistor element is small, the state of charge (SOC) of the assembled battery 10 can be accurately measured (with high accuracy). In addition, since the shunt resistance element has a fast response characteristic (trackability of the voltage value with respect to the current change), if the measurement time interval of the current measuring unit 23 is shortened (sampling interval is fast), the time resolution is increased accordingly. Can do. That is, it is easy to achieve the synchronization of the measurement timing between the measurement current and the measurement voltage.

  As shown in FIG. 2, the current measurement unit 23 is a ΔΣ AD converter that performs analog-digital conversion by a method called ΔΣ modulation. The current measuring unit 23 measures the assembled battery current Ia at a time interval I1 that is shorter than the time interval at which the cell voltage measuring unit 21 measures the voltage.

  As illustrated in FIG. 3, the ΔΣ AD converter includes functional blocks of a subtraction circuit 231, an addition circuit 232, a quantization circuit 233, and a switch circuit 234. The subtraction circuit 231 is a circuit for obtaining a difference (Ia−Io) between the value of the input signal (the assembled battery current Ia) and a certain fixed current value (fixed current Io). The adder circuit 232 is a circuit that adds (accumulates) the calculation results (Δi = Ia−Io) of the subtractor circuit 231 one after another. The quantization circuit 233 compares the input addition result (Σ (Δi)) with a reference value (for example, “0”) to determine the magnitude relationship, and when the input is a value smaller than the reference value, “0 Is a circuit that outputs “1” as a digital value when it is large. The switch circuit 234 is a circuit that operates according to the digital value output from the quantization circuit 233. For example, when “1” is input to the input “IN”, the switch circuit 234 outputs “Iref” as the fixed current Io, and when “0” is input to the input “IN”, the switch circuit 234 sets “−” as the fixed current Io. Iref "is output. Here, “Iref” is set to a value corresponding to the maximum value or a value larger than the maximum value as the measurement voltage of the assembled battery current Ia. As described above, the current measurement unit 23 outputs “1” or “0” at each measurement timing by repeating subtraction, addition, and quantization.

  As shown in FIG. 4, a sequence of digital values Id is obtained based on the output of the current measuring unit 23, and the value of the input signal (assembled battery current Ia) is determined from the appearance frequency of “1” and “0” in this sequence. Can be reproduced. Since the current measurement unit 23 only calculates a 1-bit digital value in one measurement, the sampling speed can be increased, that is, the measurement time interval can be shortened. In addition, as the digital value, a value of an input signal at a specific measurement timing can be calculated by acquiring a specific number of bits from the specific measurement timing toward the past, for example, 16 bits or 32 bits. For example, the assembled battery current Ia at the measurement timing t1 is obtained as the assembled battery current Ia (t1) by obtaining a 16-bit digital value Id from the measurement timing t1. For example, when it is desired to obtain the assembled battery current Ia at the measurement timing t2, the assembled battery current Ia (t2) is obtained by obtaining the 16-bit digital value Id from the measurement timing t2.

  Since the sequence of digital values Id output from the current measurement unit 23 is a one-dimensional sequence, the control unit 24 that holds the sequence has a simple structure for holding the sequence, and the processing related to the sequence is also simple. In addition, the battery pack current Ia corresponding to the specified measurement timing can be easily obtained.

  As shown in FIG. 1, the control unit 24 performs overall control of the battery monitoring device 2, and performs, for example, operation control and state determination of the cell voltage measurement circuits CC <b> 1 to CCL. The control unit 24 receives signals sent from each of the cell voltage measurement unit 21, the total voltage measurement unit 22, and the current measurement unit 23, and uses the signal values to each battery cell C (1) to C (N ) Internal resistance Rc.

  When the number N of battery cells C (1) to C (N) constituting the assembled battery 10 is large, electrical insulation is required for connection between the high voltage side and the low voltage side in the battery monitoring device 2. For example, when N = 96 lithium ion secondary batteries are connected in series, the voltage across the assembled battery 10 is about 400V. Therefore, a voltage difference of about 400 V is generated between the cell voltage measurement circuit CC1 to which the battery cell C (1) is connected and the cell voltage measurement circuit CCL to which the battery cell C (N) is connected. Therefore, it is necessary to electrically insulate the cell voltage measurement circuits CC1 to CCL from the control unit 24. Specifically, the insulating element 6 is inserted into each connection line (signal line) between the cell voltage measurement circuits CC <b> 1 to CCL and the control unit 24.

  Similarly, the insulating element 6 is also inserted between the total voltage measurement unit 22 and the control unit 24 and between the current measurement unit 23 and the control unit 24. The insulating element 6 may not be inserted when the voltage of the assembled battery 10 is not so high as to require electrical insulation.

  The influence of the time change of the current of the assembled battery 10 in the battery system 1 and the measurement timing shift will be described. In an electric vehicle, the output torque of the electric motor 50 varies with time in accordance with the traveling state of the electric vehicle. For example, when engine assistance by the electric motor 50 is required, the output power of the inverter 40 increases as the output torque of the electric motor 50 increases. And the input current to the inverter 40, that is, the discharge current of the assembled battery 10 also increases. Conversely, when the electric vehicle enters a regenerative state using the regenerative brake, the electric motor 50 operates as a generator, and regenerative power flows from the electric motor 50 to the assembled battery 10 via the inverter 40. For this reason, the charging current to the assembled battery 10 increases. Thus, in the battery system 1, the current of the assembled battery 10 changes over time.

  When the assembled battery current Ia (t) of the assembled battery 10 changes by a difference ΔI at a certain time, the change in cell voltage at this time is expressed by a component that immediately responds to the current change and a component that changes with time. Is done. The component that responds immediately is a DC internal resistance component (DCR, Direct-Current Resistance), and the component that changes with delay is a polarization component. The DC internal resistance component is a voltage change caused by the internal resistance Rc of the battery cell C, and is expressed by internal resistance Rc × difference ΔI. The polarization component is a voltage change component caused by factors such as the capacitance and inductance of the battery cell C, and further the behavior of ions in the electrolytic solution.

  Incidentally, the battery monitoring device 2 detects the internal resistance Rc of the battery cell C. Since the internal resistance Rc is calculated based on the cell voltage of the battery cell C and the current flowing through the battery cell C (the assembled battery current Ia), in order to accurately determine the internal resistance Rc, the cell voltage and current are accurately determined. It is necessary to measure.

  Referring to FIG. 2, it is assumed that cell voltage measurement timing t2 in cell voltage measurement unit 21 and current measurement timing t1 in current measurement unit 23 are shifted. At this time, the internal resistance Rc of the battery cell C (2) is calculated from the cell voltage measurement value vc (t2) of the battery cell C (2) at the measurement timing t2 and the assembled battery current Ia (t1) at the measurement timing t1. Can be calculated as “vc (t2) / Ia (t1)”. However, at the measurement timing t2, the cell voltage is “vc (t2)”. Therefore, “vc (t2) / Ia (t1)” calculated under a shift in measurement timing may be different from the correct internal resistance Rc (= “vc (t2) / Ia (t2)”). . That is, if there is a difference between the cell voltage measurement timing t2 and the current measurement timing t1, the correct internal resistance Rc cannot be obtained.

  Next, the measurement of the cell voltage in the battery monitoring device 2 will be described. Since the cell voltage measurement circuits CC1 to CCL have the same configuration, the cell voltage measurement circuit CC1 will be described as an example. In the example shown in FIG. 1, description will be made assuming that the number of battery cells C constituting the cell block B1 is four.

  The cell voltage measurement circuit CC1 can measure the cell voltages of about 4 to 12 battery cells C, and includes a selection circuit 210 and a voltage detection circuit 211 for selecting the battery cells C (1) to C (4) to be measured. I have. Specifically, a multiplexer or the like is used as the selection circuit 210, and the voltage detection circuit 211 is generally composed of an amplifier and an analog / digital converter.

  FIG. 2 is a diagram schematically showing a typical measurement sequence in the cell voltage measurement circuit CC1. FIG. 2 shows cell voltage measurement timings C1 to C4 of the battery cells C (1) to C (4). The selection circuit 210 selects the battery cell C in the order of battery cell C (1) → battery cell C (2) → battery cell C (3) → battery cell C (4). Then, the cell voltage is sequentially measured for each cell by the voltage detection circuit 211.

  Therefore, when measuring the cell voltages of the four battery cells C (1) to C (4), the time required for measuring the cell voltage (cell voltage measurement interval Tm) is one cell as a predetermined time interval. Four times as long as the required measurement interval Tn is required. For example, since the typical value of the measurement required interval Tn of one cell is 200 μs, the cell voltage measurement interval Tm is 800 μs.

  Here, when the current changes by the difference ΔI during the cell voltage measurement interval Tm, when the current is measured at the measurement timing t1, the battery cell C (1) measures the voltage and current at the same time. However, in the case of battery cell C (2), since the cell voltage is measured at measurement timing t2, the voltage and current are measured at different timings (measurement timing t2 and measurement timing t1), and the current changes by a difference ΔI during that time. is doing. Therefore, the correct internal resistance Rc cannot be measured for the battery cell C (2).

  Therefore, in this embodiment, the assembled battery current Ia is measured with a ΔΣ AD converter at a shorter interval than the voltage measurement interval (cell voltage measurement interval Tm, preferably the required measurement interval Tn of one cell). It was possible to measure voltage and current substantially simultaneously. Thereby, even when the assembled battery current Ia changes with time as shown in FIG. 2, the internal resistance Rc can be accurately measured for each cell.

(Function)
The control unit 24 detects the internal resistance Rc of each of the battery cells C (1) to C (N) based on the cell voltage from the cell voltage measurement unit 21 and the digital value Id of the current from the current measurement unit 23. In addition, a monitoring unit 240 that monitors the state of the assembled battery 10 based on the detected internal resistance Rc is provided. The monitoring unit 240 always monitors the assembled battery 10 while the battery is being used.

  As shown in FIGS. 2 and 3, when the battery is monitored, the current measurement unit 23 continues the current measurement at a short time interval (current measurement process) and outputs a digital value to the control unit 24. The control unit 24 acquires the digital value output from the current measurement unit 23 and stores it as a numerical sequence arranged in time series as shown in FIG. At this time, as shown in FIG. 2, the digital value Id of the current is measured at a time interval Ti that is short enough to perform a plurality of measurements during the required measurement interval Tn of one cell as the time interval of the cell voltage. .

  In addition, as shown in FIG. 2, the cell voltage measuring unit 21 measures the cell voltages of the four battery cells C sequentially by the cell voltage measuring circuit CC1 with the required measurement interval Tn per cell. Repeat (voltage measurement process).

  At this time, in the battery cell C, the internal resistance Rc is measured from the cell voltage and the current at the measurement timing when the cell voltage is measured. In the present embodiment, current measurement is performed a plurality of times at a time interval in which the cell voltage is measured (required measurement interval Tn of one cell). Therefore, the assembled battery current Ia measured at the measurement timing closest to the measurement timing at which the cell voltage was measured is held at the digital value Id. Therefore, the control unit 24 obtains the assembled battery current Ia measured at the closest measurement timing from the digital value Id, so that the measurement timing at which the cell voltage is measured matches the measurement timing at which the current is measured, Alternatively, the timing is very close (synchronization process). That is, as the short time interval Ti in which the current is measured is shorter, the probability that the cell voltage measurement timing and the current value measurement timing are closer to each other increases. At this time, since the current measuring unit 23 is a ΔΣ AD converter, high-speed sampling is possible, and the cell voltage measurement timing and the current value measurement timing can be substantially equalized. It is possible to reduce the deviation in measurement timing. That is, the measurement timing of the measurement current and the measurement voltage can be easily synchronized.

  Further, when the processing and the storage capacity are increased for the measurement of the cell voltage, it is necessary for N battery cells C, which increases the storage capacity of the control unit 24 and the processing load. On the other hand, since there is only one measurement of the assembled battery current Ia for one assembled battery 10, even if there is an increase in storage capacity or an increase in processing load for the assembled battery current Ia, the control unit The increase in the storage capacity and the increase in processing load at 24 are minimized. Further, the process of obtaining the assembled battery current Ia from the digital value Id of the current is also a simple process, and an increase in the processing load of the control unit 24 can be suppressed, while the sampling interval (short time interval Ti) of the assembled battery current Ia is Since it becomes shorter, it becomes synchronized with the measurement timing of the cell voltage. The assembled battery current Ia is maintained with high measurement accuracy by the ΔΣ AD converter. Therefore, the internal resistance Rc of the battery cell is calculated with high accuracy, and the monitoring unit 240 monitors the battery state of the assembled battery 10 based on the calculated internal resistance Rc (monitoring process). For example, the monitoring unit 240 determines that an abnormality has occurred in the battery cell C when the internal resistance Rc exceeds the upper limit value. Accordingly, it is possible to provide the battery monitoring device 2 that can suitably monitor the battery state of the assembled battery 10 based on the internal resistance Rc.

As described above, according to the battery monitoring apparatus and the battery monitoring method of the present embodiment, the effects listed below can be obtained.
(1) Since the current and voltage of the battery cell C in use constantly change, the voltage and current measurement timings must be synchronized when monitoring the state of the battery cell C. In this respect, according to such a configuration, the current is repeatedly measured at a time interval Ti shorter than the required measurement interval Tn of one cell in which the voltage is measured, so that the current corresponding to the voltage measurement timing can be measured. Thus, a voltage and a current whose measurement timing is synchronized can be obtained. That is, since the current synchronized with the voltage measurement timing is measured, for each battery cell as a plurality of divided cells obtained by dividing a plurality of battery cells into two or more, for synchronization Therefore, it is not necessary to measure and store the voltage, and the processing for the voltage can be simplified. As a result, the measurement current and the measurement voltage can be easily synchronized.

  (2) Even when the battery is in use, the internal resistance Rc, which is one index indicating the battery state, is obtained with high accuracy. The state of the battery can be monitored based on the acquired internal resistance Rc.

(3) It is possible to easily select the assembled battery current Ia measured at the timing corresponding to the measurement timing at which the cell voltage measurement unit 21 measures the voltage.
(4) For a lithium ion secondary battery that preferably monitors the internal resistance Rc for each battery cell, it is possible to easily monitor the internal resistance Rc.

(Other embodiments)
In addition, the said embodiment can also be implemented with the following aspects.
In the above embodiment, the case where the battery cell C is a lithium ion secondary battery is illustrated, but the battery cell C is not limited to this, and the battery cell C is an alkaline secondary battery such as a nickel hydride secondary battery or a nickel cadmium secondary battery. It may be.

  In the above embodiment, the case where the current measurement unit 23 is a ΔΣ AD converter is illustrated. However, the present invention is not limited to this, and if the current can be measured at an interval shorter than the required measurement interval of one cell where the voltage measurement unit measures the voltage, the current is measured in a manner different from that of the ΔΣ AD converter. Alternatively, the measured signal may not be a sequence of digital values. For example, even if it is a measured value itself, the storage capacity required for holding the current value can be made smaller than the storage capacity required for holding the voltage value.

  -In above-mentioned embodiment, the monitoring part 240 illustrated about the case where the state of the assembled battery 10 is monitored based on the internal resistance Rc of the battery cell C. FIG. However, the present invention is not limited to this, and the state of the assembled battery may be monitored based on the voltage measured by the cell voltage measurement unit or the current measured by the current measurement unit. For example, it may be determined whether or not the cell voltage or current is within the normal range set for each, and if the cell voltage or current is not within the normal range, it may be determined that an abnormality has occurred in the assembled battery.

  In the above embodiment, the case where the internal resistance Rc is calculated by sequentially measuring the voltage between the terminals of the plurality of battery cells C at a predetermined time interval is illustrated. However, the present invention is not limited to this, and the inter-terminal voltage of the plurality of divided cells obtained by dividing the plurality of battery cells into two or more is sequentially measured at predetermined time intervals to calculate the internal resistance for each divided cell. Also good. Thereby, the time required for calculating the internal resistance can be shortened.

  -In above-mentioned embodiment, the assembled battery 10 and the battery monitoring apparatus 2 were illustrated about the case where it mounts in the vehicle of a hybrid vehicle. However, the present invention is not limited to this, and the vehicle may be an electric vehicle equipped with an assembled battery. Further, it may be a gasoline vehicle or a diesel vehicle equipped with an assembled battery.

  In addition, the assembled battery 10 and the battery monitoring device 2 may be used as a mobile body other than an automobile, a fixed power source, or a power source other than an electric motor, as long as it is required as a power source. Also good. For example, it may be a moving body such as a railway, a ship, an aircraft or a robot, or a power source of an electrical product such as an information processing apparatus.

  DESCRIPTION OF SYMBOLS 1 ... Battery system, 2 ... Battery monitoring apparatus, 6 ... Insulating element, 9 ... Current measuring element, 10 ... Assembly battery, 21 ... Cell voltage measuring part, 22 ... Total voltage measuring part, 23 ... Current measuring part, 24 ... Control 30: Vehicle controller, 40 ... Inverter, 41 ... Motor controller, 50 ... Electric motor, 60, 61 ... Relay, 100 ... Electric vehicle drive device, 210 ... Selection circuit, 211 ... Voltage detection circuit, 220a, 220b ... Total voltage Meter input terminal, 231... Subtracting circuit, 232... Adding circuit, 233... Quantizing circuit, 234... Switching circuit, 240 ... monitoring unit, C, C (1) to C (N). Block, CC1 to CCL: Cell voltage measurement circuit.

Claims (5)

A battery monitoring device for an assembled battery composed of a plurality of battery cells connected in series,
A voltage measuring unit that sequentially measures a voltage between terminals of a plurality of divided cells obtained by dividing the plurality of battery cells into two or more; and a predetermined time interval;
A current measurement unit that repeatedly measures a current flowing through the assembled battery at a time interval shorter than the predetermined time interval of the voltage measurement unit;
The current measurement unit holds a plurality of currents repeatedly measured, and the voltage measurement unit holds the current measured at a timing corresponding to the timing at which the voltage between the terminals of any one of the divided cells is measured. A synchronizer for selecting from a plurality of currents;
A battery monitoring apparatus comprising: a monitoring unit that monitors a battery state based on a voltage between terminals measured at the timing and a current selected by the synchronization unit. The battery monitoring apparatus according to claim 1, wherein the monitoring unit monitors the state of the assembled battery based on an internal resistance calculated based on a voltage between terminals measured at the timing and a current selected by the synchronization unit. The current measuring unit is a ΔΣ AD converter, and outputs a digital signal of the measured current.
The synchronization unit holds a digital signal of the measured current output from the current measurement unit, and selects a current measured at the corresponding timing from the held digital signal. The battery monitoring device described. The battery monitoring device according to claim 1, wherein the battery cell is a lithium ion secondary battery. A battery monitoring method for monitoring an assembled battery composed of a plurality of battery cells connected in series,
A voltage measuring step of sequentially measuring the voltage between terminals of a plurality of divided cells obtained by dividing the plurality of battery cells into two or more, at a predetermined time interval;
A current measuring step of repeatedly measuring a current flowing through the assembled battery at a time interval shorter than the predetermined time interval of the voltage measuring step;
Holding a plurality of currents repeatedly measured in the current measurement step, holding the current measured at a timing corresponding to a timing at which a voltage between terminals of any one of the segmented cells is measured in the voltage measurement step; A synchronization step of selecting from a plurality of currents,
A battery monitoring method comprising: a monitoring step of monitoring a battery state based on the inter-terminal voltage measured at the timing and the current selected in the synchronization step.

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