JP2017070024A - Battery monitoring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery monitoring device comprising a function capable of diagnosing whether data obtained by detectors are correct or not, and mutually diagnosing circuits.SOLUTION: The battery monitoring device comprises: a voltage input circuit 22a for inputting a highest potential and a lowest potential of a battery pack 10 including a plurality of battery cells C electrically connected in series; a current input circuit 23a for inputting output of a current sensor 9 provided for measuring a current flowing in the battery pack 10; a first detection circuit 22b which detects a voltage of the battery pack 10 from output of the voltage input circuit; a second detection circuit 23b which detects a current of the battery pack 10 from output of the current input circuit; a third detection circuit 21b which detects voltages of the plurality of voltage cells C, respectively; and a circuit which includes the voltage input circuit, the current input circuit and the first to third detection circuits, and in which data obtained by the first detection circuit are compared with data obtained by the third detection circuit.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a battery monitoring device that monitors the state of a battery.

  An assembled battery in which a plurality of secondary battery battery cells such as lithium ion secondary batteries, nickel metal hydride batteries, and lead batteries are configured in series and parallel is usually used together with a battery monitoring device. The battery monitoring device detects the state of the battery by detecting the cell voltage of each battery cell constituting the assembled battery or detecting the current flowing through the battery cell. Thereby, it is monitored whether the assembled battery is in an appropriate state. Some battery monitoring devices may function as a control device, such as controlling an energized state in order to maintain an appropriate state.

In a general battery monitoring device, in order to know whether or not each cell is overcharged or overdischarged, the voltage or energization current of each battery cell is detected or measured. In addition, in order to know the deterioration state of the battery,
The internal resistance of the battery cell may be detected. When the battery deteriorates, the internal resistance increases.
This is because the deterioration state of the battery can be known by knowing the internal resistance.

The detection of the internal resistance of the battery is obtained from the measured value of the voltage of the battery cell and the measured value of the energization current.
However, at this time, it is necessary to synchronize the timing at which the voltage detection means detects the cell voltage of the battery cell and the current detection means to accurately detect the current flowing through the battery cell and detect the voltage. Furthermore, a battery capacity (SOC: State of Charge) and a battery deterioration state (SOH: State of Health) are calculated from the battery information, and the calculation result is notified to the vehicle controller or the like.

  As a configuration for detecting the cell voltage and detecting the current, a configuration in which a voltage detection circuit and a current detection circuit are provided in each of them, and a data transmission / reception is performed using a communication circuit between the calculation circuit that calculates SOC and SOH is considered. It is done.

  However, in such a configuration, there is a problem that it cannot be determined whether or not the data measured by the current sensor and the voltage sensor detection circuit is correct.

  On the other hand, Patent Document 1 discloses a configuration in which a detection circuit is diagnosed by fetching several types of data by using a single AD converter by using an analog selector.

International Publication No. 2010/106588

  However, there has been a problem that it is not possible to determine whether or not the device is truly malfunctioning by simply reading several types of data with an analog selector.

  The battery monitoring apparatus of the present invention is a voltage input circuit (second voltage input filter 22a) for inputting the highest potential and the lowest potential of the assembled battery 10 including a plurality of battery cells C electrically connected in series. A current input circuit (current input filter 23a) for inputting an output of a current sensor (current measurement element 9) provided for measuring a current flowing through the assembled battery 10, and a voltage input circuit (second voltage input) A first detection circuit (second voltage detection circuit 22b) for detecting the voltage of the assembled battery 10 from the output of the filter 22a), and a first detection circuit for detecting the current of the assembled battery 10 from the output of the current input circuit (current input filter 23a). 2 detection circuits (current detection circuit 23b), a third detection circuit (voltage detection circuit 21b) for detecting each voltage of the plurality of battery cells C, and a voltage input circuit (second voltage input filter 22a). It has a current input circuit (current input filter 23a), first to third detection circuits (voltage detection circuit 21b, second voltage detection circuit 22b, current detection circuit 23b), and includes a first detection circuit (second voltage detection). A circuit for comparing the data obtained by the circuit 22b) with the data obtained by the third detection circuit (voltage detection circuit 21b).

  By using the present invention, it is possible to diagnose a failure of the mutual detection circuit.

FIG. 1 is a diagram illustrating an example of the configuration of the electric vehicle drive device 100. FIG. 2 is a diagram illustrating an example of the configuration of the battery monitoring device 2.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
A battery monitoring device according to the present invention is a device that detects a battery state of an assembled battery provided in a battery system (also called a power storage device) and keeps the assembled battery in an appropriate state. FIG. 1 shows an electric vehicle drive device 100 equipped with a battery system 1 provided with a battery monitoring device 2 of the present embodiment. Here, the electric vehicle drive device is a rotating machine system that drives an electric vehicle such as a hybrid vehicle (HEV) or an electric vehicle (EV).

The electric vehicle drive device 100 includes a battery system 1 including the battery monitoring device 2 and the assembled battery 10, a vehicle controller 30 that controls the entire vehicle, an inverter 40, a rotating electrical machine 50, and the like. The battery system 1 is connected to the inverter 40 via relays 60 and 61. The battery monitoring device 2 communicates with the inverter 40 and the host vehicle controller 30 with C
This is performed via a communication bus of AN (Controller Area Network).

The rotating electrical machine 50 is driven by electric power from the inverter 40. When the vehicle starts and accelerates, discharge power is supplied from the battery system 1 to the rotating electrical machine 50 through the inverter 40, and an engine (not shown) is assisted by the driving force of the rotating electrical machine 50. When the vehicle is stopped and decelerated, regenerative electric power from the rotating electrical machine 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 drive control of the rotating electrical machine 50 and charge / discharge control of the assembled battery 10.

  The battery system 1 includes an assembled battery 10 and a battery monitoring device 2. The assembled battery 10 is configured by connecting a plurality of battery cells C (C (1) to C (N)) as a minimum unit in series. In addition, the assembled battery 10 of the present embodiment is configured by, for example, about 12 battery cells C connected in series, and has a voltage of about 48V as a whole. Moreover, the insulating element is not inserted. Accordingly, the GND of the entire battery monitoring device 2 is common. In the following description, the number of battery cells C constituting the assembled battery 10 is N, and in the following, the battery cell is represented in the case of representing one of the N battery cells C (1) to C (N). Sometimes called C. As the battery cell C which comprises the assembled battery 10, the lithium ion secondary battery which can be charged / discharged is used, for example. The assembled battery 10 including the battery cell C of the example shown in FIG. 1 may have a configuration of a connection body formed by connecting a plurality of cell blocks grouped into a predetermined number of battery cells in series. In this case, the cell voltage measurement unit 21 connected to the grouped assembled battery 10 is also a plurality of grouped blocks.

(Configuration of battery monitoring device 2)
Then, the structure of the battery monitoring apparatus 2 is demonstrated using FIG. 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 current voltage detection unit 400, a current measurement element 9, a control unit 24, and the like. The total current voltage detection unit 400 includes a second voltage measurement unit 22, a current measurement unit 23, an AD conversion control unit 250, and a first calculation unit 405.

  The cell voltage measurement unit 21 is a circuit that measures the voltage of each battery cell C constituting the assembled battery 10 (hereinafter referred to as cell voltage). The cell voltage measurement unit 21 is a circuit capable of measuring the cell voltages of about 4 to 12 battery cells C, and may be configured as an integrated circuit (IC).

The second voltage measurement unit 22 is a circuit that measures the voltage of all N battery cells constituting the assembled battery 10 (hereinafter referred to as the total voltage Vt). When N battery cells C are represented by symbols C (1), C (2),..., C (N-1), C (N) from the assembled battery negative electrode side, the second voltage measuring unit 22 The second voltage input terminal 220 is connected to the positive electrode of the battery cell C (N). The cell voltage measurement unit 21 measures the voltage of each battery cell. Although not shown, the cell voltage measurement unit 21 performs control by communicating with a balancing resistor and a balancing switch that perform the balancing operation of the cell voltages of the battery cells C (1) to C (N), and the control unit 24. The logic part which performs is provided.

A measurement signal (electric signal) is input from the current measurement element 9 to the current measurement unit 23 that measures the current flowing through the assembled battery 10. The current measuring element 9 is an element that converts the magnitude of the current into an electric signal, and specifically includes a Hall element sensor, a shunt resistance element, and the like. Current measuring element 9
Outputs an electric signal corresponding to the magnitude of the current, and the electric signal is measured by the current measuring unit 23.

The shunt resistor element is superior to the Hall element sensor in the following points. Since the shunt resistor element has a small offset current, the state of charge (SOC) of the assembled battery 10 can be accurately measured (with high accuracy). Further, 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 constant of the current measuring unit 23 is increased, the time resolution can be increased accordingly. That is, it is excellent in that it is easy to achieve simultaneity of measurement.

The second voltage measurement unit 22 includes a second voltage input filter 22a and a second voltage detection circuit 22b. The current measurement unit 23 includes a current input filter 23a and a current detection circuit 23b. In this case, it is preferable that the characteristic frequency of the second voltage input filter 22a included in the second voltage measurement unit 22 and the characteristic frequency of the current input filter 23a included in the current measurement unit 23 be equal to each other. Specifically, both filter circuits have the same time constant. By adopting such a configuration, if the current and voltage are measured at the same timing, there is no measurement delay due to the time constant of the filter circuit, and the simultaneity of voltage and current measurement can be ensured.

  The integrated circuit 25 includes a first calculation unit 405, an AD conversion control unit 250, a second voltage detection circuit 22b, and a current detection circuit 23b. The second voltage detection circuit 22b and the current detection circuit 23b each receive a trigger signal from the AD conversion control unit 250 and start AD conversion. The AD conversion control unit 250 generates a trigger signal so that the conversion timings of the voltage detection circuit 22b and the current detection circuit 23b are equal to each other. Furthermore, it is preferable that the voltage detection circuit 22b and the current detection circuit 23b are configured to start conversion with the same trigger signal.

  Further, it is preferable to use a ΔΣ AD converter for the voltage detection circuit 22b and the current detection circuit 23b. It is preferable to use a ΔΣ type AD converter because highly accurate AD conversion can be performed.

  More preferably, the decimation filter of the ΔΣ type AD converter is a decimation filter having the same characteristics in the voltage detection circuit 22b and the current detection circuit 23b, so that the transfer functions of these two AD converters are equal to each other. be able to. By adopting such a configuration, the simultaneity of voltage and current measurement can be further ensured. Accordingly, it is possible to calculate a more accurate value even in subsequent calculations.

  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 circuit. The control unit 24 receives signals sent from the cell voltage measurement unit 21 and the total current voltage detection unit 400, and uses the signal values to determine the internal resistances of the battery cells C (1) to C (N). Detect. In some cases, the relay 60 has an ON / OFF function.

  The current value and the voltage value detected at the same time by the second voltage measurement unit 22 and the current measurement unit 23 are averaged by a first calculation unit 405 built in the total current voltage detection unit 400, and IIR (Infinite Impulse). Processing such as Response) and FFT (Fast Fourier Transform) is performed. Since this calculation process takes time, the first calculation unit 405 occupies the calculation process. In addition, the calculation processing result of the voltage value and the current value also remains synchronized.

  The second calculation unit 502 built in the control unit 24 is configured to have a battery capacity (SOC) and a battery based on the calculation processing result signal sent from the first calculation unit 405 and the cell voltage value signal sent from the cell voltage measurement unit 21. Deterioration state (SOH) calculation processing is performed.

(Explanation of measurement time deviation for current change)
The influence of the time change of the energization current of the battery pack 10 in the battery system 1 on the measurement time deviation will be described. In the electric vehicle (HEV) shown in FIG. 1, the output torque of the rotating electrical machine 50 varies with time in accordance with the traveling state of the electric vehicle. For example, when the rotating electrical machine 50 needs to assist the engine, the output torque of the rotating electrical machine 50 increases, and the output power of the inverter 40 increases accordingly. And the input current to the inverter 40, that is,
The energization current of the assembled battery 10 also increases. Conversely, when the electric vehicle enters a regenerative state using the regenerative brake, the rotating electrical machine 50 operates as a generator, and regenerative power flows from the rotating electrical machine 50 (generator) to the inverter 40 and the assembled battery 10. For this reason, the charging current to the assembled battery 10 increases. Thus, in the battery system 1, the energization current to the assembled battery 10 changes with time.

  The second voltage measurement unit 22 measures the total voltage output from the assembled battery 10 and transmits it to the first calculation unit 405. On the other hand, each cell voltage signal measured by the cell voltage measurement unit 21 is transmitted to the second calculation unit 502. That is, the second calculation unit 502 can detect the total voltage by the sum of the cell voltages. Therefore, the first calculation unit 405 and the second calculation unit 502 perform diagnosis by comparing the total voltage data with each other. With this configuration, the total voltage data measured by the first calculation unit 405 and the total voltage data calculated from the voltage of each cell by the second calculation unit 502 can always be compared. Thus, it can be determined whether or not the actually measured current, each cell voltage, and the total voltage are accurate. Therefore, it is possible to diagnose each other whether the cell voltage measurement unit 21 and the total current voltage detection unit 400 are out of order. In addition, it is preferable that the current total voltage detection unit 400 and the cell voltage measurement unit 21 are formed on the same circuit board because the simultaneity of measurement can be ensured.

  A circuit (not shown) for detecting a power supply voltage or a reference voltage is provided in the first calculation unit 405, and a circuit (not shown) for detecting a power supply voltage or a reference voltage is also provided in the second calculation unit 502. Even if either the first calculation unit 405 or the second calculation unit 502 cannot detect the power supply voltage and the reference voltage due to a failure, it can be detected by the one calculation unit 405 or the second calculation unit 502. Improves.

  The present invention will be briefly described above.

  The battery monitoring device according to the present invention includes a voltage input circuit (second voltage input filter) for inputting the highest potential and the lowest potential of the assembled battery 10 including a plurality of battery cells C electrically connected in series. 22a), a current input circuit (current input filter 23a) for inputting the output of a current sensor (current measurement element 9) provided for measuring the current flowing through the assembled battery 10, and a voltage input circuit (second A first detection circuit (second voltage detection circuit 22b) for detecting the voltage of the assembled battery 10 from the output of the voltage input filter 22a) and a current of the assembled battery 10 from the output of the current input circuit (current input filter 23a) A second detection circuit (current detection circuit 23b), a third detection circuit (voltage detection circuit 21b) for detecting the respective voltages of the plurality of battery cells C, and a voltage input circuit (second voltage input filter 2). a), a current input circuit (current input filter 23a), first to third detection circuits (voltage detection circuit 21b, second voltage detection circuit 22b, current detection circuit 23b), and a first detection circuit (first detection circuit). A circuit for comparing the data obtained by the two voltage detection circuit 22b) with the data obtained by the third detection circuit (voltage detection circuit 21b). With this configuration, the total voltage data measured by the first calculation unit 405 and the total voltage data calculated from the voltage of each cell by the second calculation unit 502 can always be compared. Thus, it can be determined whether or not the actually measured current, each cell voltage, and the total voltage are accurate. Therefore, it is possible to diagnose each other whether the cell voltage measurement unit 21 and the total current voltage detection unit 400 are out of order.

  In the battery monitoring apparatus according to the present invention, the first detection circuit (second voltage detection circuit 22b) includes a voltage detection circuit for a power supply voltage or a reference voltage, and the third detection circuit (voltage detection circuit 21b). Has a voltage detection circuit for a power supply voltage or a reference voltage. With such a configuration, even when either the first calculation unit 405 or the second calculation unit 502 cannot detect the power supply voltage and the reference voltage due to a failure, the one calculation unit 405 or the second calculation unit Since it becomes detectable by 502, diagnostic property improves.

  In the battery monitoring device according to the present invention, the characteristic frequencies of the voltage input circuit (second voltage input filter 22a) and the current input circuit (current input filter 23a) are the same. By adopting such a configuration, if the current and voltage are measured at the same timing, there is no measurement delay due to the time constant of the filter circuit, and the simultaneity of voltage and current measurement can be ensured.

  In the battery monitoring device according to the present invention, the first detection circuit (second voltage detection circuit 22b) is connected to the first AD converter, and the second detection circuit (voltage detection circuit 21b) is the second. The first AD converter and the second AD converter have filters having the same characteristics (decimation filters having the same characteristics). By adopting such a configuration, the simultaneity of voltage and current measurement can be further ensured. Accordingly, it is possible to calculate a more accurate value even in subsequent calculations.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention described in the claims. The design can be changed.
Furthermore, the secondary battery module according to the present invention is applicable not only to the use of vehicles such as automobiles but also to the use of railway vehicles.

DESCRIPTION OF SYMBOLS 1 ... Battery system, 2 ... Battery monitoring apparatus, 9 ... Current measuring element, 10 ... Assembly battery, 21 ... Cell voltage measurement part, 21a ... Voltage input filter, 21b ... Voltage detection circuit, 22 ... 2nd voltage measurement part, 22a 2nd voltage input filter, 22b 2nd voltage detection circuit, 23a ... Current input filter, 23b ... Current detection circuit, 23 ... Current measurement unit, 24 ... Control unit, 25 ... Integrated circuit, 30 ... Vehicle controller, 40 ... Inverter, 41 ... motor controller, 50 ... rotating electric machine, 100 ... electric vehicle drive device, 250 ... AD conversion control unit, 400 ... current total voltage detection unit, 405 ... first calculation unit, 502 ... second calculation unit

Claims (4)

A voltage input circuit for inputting a maximum potential and a minimum potential of an assembled battery including a plurality of battery cells electrically connected in series;
A current input circuit for inputting an output of a current sensor provided to measure a current flowing through the assembled battery;
A first detection circuit for detecting a voltage of the assembled battery from an output of the voltage input circuit;
A second detection circuit for detecting a current of the assembled battery from an output of the current input circuit;
A third detection circuit for detecting a voltage of each of the plurality of battery cells;
In the battery monitoring device having the voltage input circuit, the current input circuit, and the first to third detection circuits,
A battery monitoring device comprising a circuit for comparing data obtained by the first detection circuit and data obtained by a third detection circuit.
Battery monitoring device. The battery monitoring device according to claim 1,
The first detection circuit includes a voltage detection circuit for a power supply voltage and a reference voltage,
The battery monitoring apparatus, wherein the third detection circuit includes a voltage detection circuit for a power supply voltage and a reference voltage. The battery monitoring device according to claim 2,
The battery monitoring device, wherein the voltage input circuit and the current input circuit have the same characteristic frequency. The battery monitoring device according to claim 3,
The first detection circuit is connected to a first AD converter;
The second detection circuit is connected to a second AD converter;
The battery monitoring apparatus, wherein the first AD converter and the second AD converter have filters having the same characteristics.

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