JP2018105801A - Battery management device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery management device with which it is possible to obtain almost the same filter characteristic for each battery cell in an asymmetric filter configuration, and which excels in anti-aliasing filter performance.SOLUTION: A battery management device comprises: an integrated circuit for detecting the terminal voltage of each of the plurality of battery cells and electrically connected to both poles of each of n battery cells via a voltage detection line; an integrated circuit having a voltage detection part that detects the terminal voltage of each of n plurality of battery cells; n+1 resistors electrically connected to a voltage detection line; n capacitors Cn interconnected to a voltage detection line between the resistors and the voltage detection part; and one capacitor between the resistor of the lowest potential connected to the integrated circuit and the voltage detection part and between the GND of the integrated circuit. Assuming that k represents the position of a capacitor on the lowest potential side of the capacitor Cn, the ratio of the value of each capacitor Cn satisfies a prescribed numerical expression.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a storage battery management device.

  In a hybrid vehicle, an electric vehicle, and the like, in order to secure a desired high voltage, an assembled battery configured by connecting a number of secondary battery cells in series is used. In such an assembled battery, the battery cell is managed by a battery management device (Battery Management System, hereinafter abbreviated as BMS) that monitors the state of the battery cell. BMS acquires the voltage of each battery cell as one piece of monitoring information. In general, since the voltage of the battery cell applied to the BMS includes a noise component, an anti-aliasing filter may be applied.

  It is known that when this anti-aliasing filter is mounted with a resistor and a capacitor (RC filter) arranged for each battery cell, different filter characteristics are obtained for each battery cell. In order to solve this problem, Patent Document 1 discloses a technique for setting the value of a capacitor arranged in each battery cell to an individual value.

  In particular, in the case of an assembled battery using a lithium ion battery as a battery cell, since the lithium ion battery has a high energy density, it is dangerous that the battery management device does not operate normally and becomes overcharged. Therefore, a circuit fault diagnosis for avoiding an overcharge state is implemented even when a circuit fault occurs. As a circuit failure diagnosis technique, Patent Document 2 devised by the inventors is disclosed.

JP 2009-150867 A WO2016 / 143679

  However, as a first problem, the technique disclosed in Patent Document 1 discloses only a technique for a target filter configuration, and it is for a non-target filter configuration as shown in FIG. Since there was no technology, the problem of different filter characteristics for each battery cell with respect to the non-target filter configuration could not be solved.

  Moreover, as 2nd subject, as FIG. 26 of patent document 1 shows, there exists a subject that the cutoff frequency raises significantly in the case of 12 battery cells compared with the case of 1 battery cell. If the capacitor capacity is increased, the cutoff frequency can be lowered. However, when a capacitor having a large capacity is used, there is a problem that the use of a large capacitor or a plurality of capacitors increases the size and cost of the BMS.

  The failure diagnosis disclosed in Patent Document 2 utilizes the fact that voltage fluctuation occurs by charging / discharging a capacitor of the RC filter with a current source in response to an open failure of the resistance of the RC filter. When charging / discharging with the same current, as disclosed in Patent Document 1, if the capacitance value is different at each terminal, there is a problem that the speed of voltage fluctuation is different and the time during which failure diagnosis is possible differs depending on the terminal. Further, if the capacitance value of each terminal is large, it takes time until the desired voltage is changed, and thus high-speed failure diagnosis cannot be performed. While charging / discharging control is performed based on an erroneous cell voltage measurement result while a failure cannot be determined at the time of failure, there is a possibility of overcharging and overdischarging. In other words, when high-speed failure diagnosis cannot be performed, it is impossible to satisfy the requirements of FTTI (Fault tolerant time interval) defined in the functional safety standard ISO26262. In addition, if the requirements of FTTI can be satisfied, the technique of Patent Document 1 can be applied.

  In order to solve the problem 1, a battery management apparatus according to an aspect of the present invention is electrically connected to both electrodes of n battery cells via voltage detection lines, and terminals of each of the n battery cells. An integrated circuit (CC-IC) having a voltage detection unit for detecting a voltage, n + 1 resistors electrically connected to the voltage detection line, and voltage detection between the resistor and the voltage detection unit N capacitors Cn connected between the lines and one resistor connected between the resistance of the lowest potential detection line connected to the CC-IC and the voltage detection unit and between the GND of the previous CC-IC When the position of the capacitor on the lowest potential side of the capacitor Cn is k, the ratio of the values of the capacitors Cn is set to satisfy (Equation 1).

  In order to solve the problem 2, a battery management device according to an aspect of the present invention is electrically connected to both electrodes of n battery cells via voltage detection lines, and terminals of each of the n battery cells. An integrated circuit having a voltage detection unit for detecting a voltage; n + 1 resistors electrically connected to the voltage detection line; and a voltage detection line between the resistor and the voltage detection unit. N capacitors Cn, the resistance of the lowest potential detection line connected to the integrated circuit and the voltage detector, and the resistance of the highest potential detection line connected to the integrated circuit and the voltage detection It is made up of one capacitor C0 connected between the sections.

  In addition, the value of Cn is a fixed value, and the value of C0 is 1 / n of the value of Cn.

  With respect to the above problem 1, it is possible to obtain substantially the same filter characteristics for each battery cell with respect to the non-target filter configuration, and it is possible to provide a battery management device having excellent anti-aliasing filter performance.

  Moreover, since the problem 2 can be diagnosed at high speed, it is possible to detect a failure within the FTTI. In addition, since a small capacitor can be used, the battery management device can be reduced in size and cost.

Battery management apparatus according to Example 1 and Example 2 Capacitor capacity of battery management devices according to comparative example, example 1 and example 2 Attenuation ratio at τ = 10msec Damping ratio for the comparative example Damping ratio according to Example 1 Damping ratio according to Example 2 FIG. 2 of Patent Document 2 Battery management apparatus according to Example 3 and Example 4 Capacitor capacity of battery management devices according to Example 3 and Example 4 Damping ratio according to Example 3 Damping ratio according to Example 4

  FIG. 1 shows a battery management apparatus 1 according to the first embodiment. The battery management device 1 includes a microcomputer 6 that controls the charge / discharge state, a semiconductor device 2 (CC-IC) that monitors the battery cell state, and RC filters that remove noise from the cells Ce1 to Ce12, R0 to R12, and C0 to C12. Composed. The CC-IC includes at least a multiplexer 3 (MUX) for selecting a cell, an AD converter 5 (ADC) for converting the cell voltage into a digital value, and an LS Amp 4 for converting the cell voltage selected by the MUX into an input voltage range of the ADC. Composed. With this configuration, the microcomputer 6 acquires the cell voltage and manages the battery cell.

  It has a current source 7 that can be applied from HV (High Voltage), which is the highest potential of CC-IC2, between MUX3 and ADC5. A pseudo voltage is generated at the input portion of the MUX by applying a current to the circuit to diagnose abnormalities in various circuits.

  The values shown in FIG. 2 were used for C0 to C12. The ratio of the value of (Equation 1) is applied to C1 to C12.

FIG. 2 shows the capacities of the capacitors C1 to C12 used in the comparative example, the example 1, and the example 2 described later. For the resistors R0 to R12, 100 kΩ was used in both the example and the comparative example. For reference, FIG. 3 shows the attenuation ratio when the time constant τ = 10 msec. The time constant value is 100 kΩ resistance used in the comparative example × capacitance 1 uF = 10 msec. FIG. 4 shows the attenuation ratio in the case of the comparative example. Here, Ce1 to Ce12 are the twelve battery cells shown in FIG. In Patent Document 1, because of the target RC filter configuration, the target cell has the same attenuation characteristics, but because this comparative example is a non-target RC filter configuration, the impedance of each terminal is all different, It can be seen that the attenuation characteristics of all the cells are different. Further, it can be seen that the cut-off frequency is higher in the comparative example than the attenuation characteristic of FIG. 3 using the same resistor and capacitor, and the anti-aliasing filter performance is deteriorated. FIG. 5 shows the attenuation ratio when this embodiment is applied. Since (Equation 1) is applied in the present embodiment, the impedance of each terminal can be adjusted, and almost the same filter performance can be obtained at each terminal, and a battery management device with excellent anti-aliasing filter performance is provided. I can do things.
The present invention will be briefly described above. In the battery management device 1 of the present invention, an integrated circuit (CC-IC) that is electrically connected to both electrodes of n battery cells via a voltage detection line and detects terminal voltages of a plurality of battery cells, , An integrated circuit having a voltage detection unit for detecting a terminal voltage of each of n battery cells, n + 1 resistors electrically connected to a voltage detection line, and a voltage between the resistor and the voltage detection unit N capacitors Cn connected between the detection lines, one capacitor C0 connected between the resistance of the lowest potential detection line connected to the integrated circuit and the voltage detection unit, and between the GND of the integrated circuit, When the position of the capacitor on the lowest potential side of the capacitor Cn is k, the ratio of the values of the capacitors Cn satisfies (Equation 1).

With such a configuration, the impedance of each terminal can be adjusted, almost the same filter performance can be obtained at each terminal, and a battery management device with excellent anti-aliasing filter performance can be provided. .

  Next, Example 2 will be described. In the present embodiment, only the portion using the E12 series for the capacitance of the capacitor shown in FIG. Since others are the same as those of the first embodiment, the description thereof is omitted. FIG. 6 shows the attenuation ratio. Even when the E12 series is used, almost the same filter performance can be obtained at each terminal, and a battery management device with excellent anti-aliasing filter performance can be provided. Furthermore, since the E12 series is used for the capacitor capacity, parts with a large production volume can be used, and production efficiency and cost reduction can be achieved.

  As described above, the effect of the present invention can be taught even by using parts with a large production amount close to the capacitor value calculated from (Equation 1). Moreover, although it adjusted with the capacitor | condenser, you may adjust with a filter resistance and both a filter resistance and a filter capacitor.

  Next, a third embodiment will be described. In the present embodiment, the diagnosis function disclosed in Patent Document 2 is implemented in the inventions described in the first and second embodiments. That is, a current is applied to each terminal by a current source. If the current source is kept on, a drop voltage is generated at the filter resistor, and voltage measurement cannot be performed. Therefore, the current source is turned on for a short period, and then the cell voltage is repeatedly measured when the terminal voltage returns to the cell voltage. This control technique is disclosed in FIG. 2 of Patent Document 2 as shown in FIG. When the filter resistor is opened, this control causes a voltage fluctuation only at that terminal, and a failure can be detected.

  On the other hand, when the filter resistor has an open failure, the voltage at the terminal cannot be obtained accurately, and charge / discharge control is performed with an incorrect voltage. For this reason, a battery cell may reach overdischarge and overcharge. For this reason, when it becomes a state which cannot acquire cell voltage correctly by a circuit failure, the measure which shifts to a safe state, such as prohibiting charging / discharging, is taken using the above diagnostic techniques. Here, the time from the occurrence of a failure to a dangerous event is defined, and is called FTTI (Fault tolerant time interval) in the functional safety standard ISO26262. Therefore, when a failure occurs, it is necessary to shift to a safe state within FTTI.

  In Patent Document 1 and Examples 1 and 2, since the capacitance of each capacitor is different at each terminal, when the filter resistor has an open failure, if the same current value is applied to each terminal as in Patent Document 2, the speed of voltage change is increased. It will be different. The threshold value for detecting the filter open failure is set in consideration of the amount of noise in order to prevent misdiagnosis to be determined as a failure when there is no failure. For this reason, the time from failure occurrence to failure detection differs at each terminal. Therefore, the current value is designed so as to shift to the safe state within the FTTI at the location where the maximum failure detection time is reached. If the normal voltage fluctuation returns to the cell voltage at this current value, there is no problem, but if it does not return, the techniques of Examples 1 and 2 cannot be used. In order to cope with the high-speed voltage measurement period accompanying the high accuracy of the future control, there is a possibility that it becomes a problem in particular.

  In order to solve such a problem, in the third embodiment, as shown in FIG. 8, the capacitor C0 is arranged between the lowest and highest terminals of the CC-IC. FIG. 9 shows the capacitor capacities of C0 to C12. The capacitor capacity of Example 4 to be described later is also shown. The filter resistance used in Examples 3 and 4 was 100 kΩ. Since others are the same as those of the first and second embodiments, the description thereof is omitted.

With such a configuration, since the capacitor looks the same from any terminal, it becomes possible to suppress the voltage fluctuation amount difference between the terminals when the filter resistor is open. FIG. 10 shows the attenuation ratio. According to this configuration, although the same capacitor is used in FIG. 4, the 1 KHz attenuation ratio is −8 db, but in the case of this embodiment, it is possible to provide a battery management device with improved antialiasing filter performance of −19 dB.
The present invention will be briefly described above. In the present invention, an integrated circuit (CC-IC) that is electrically connected to both electrodes of each of n battery cells via a voltage detection line and detects a terminal voltage of each of the plurality of battery cells, and n batteries An integrated circuit having a voltage detection unit for detecting a terminal voltage of each cell, n + 1 resistors electrically connected to the voltage detection line, and a voltage detection line between the resistor and the voltage detection unit The n capacitors Cn connected, the resistance of the lowest potential detection line connected to the integrated circuit and the voltage detection unit, and the resistance of the highest potential detection line connected to the integrated circuit and the voltage And a single capacitor C0 connected between the detectors. By adopting such a configuration, the capacitor looks the same from any terminal, so that it is possible to suppress the voltage fluctuation amount difference between the terminals when the filter resistor is open.

  Next, a fourth embodiment will be described. In the present embodiment, a phenomenon that the attenuation ratio becomes positive when the attenuation ratio of Embodiment 3 (FIG. 10) is about 10 Hz appears, which may be a problem. This characteristic is due to the fact that 12 times the voltage is applied only to C0. As shown in FIG. 9, in Example 4, only C0 has a capacitance value that is 1/12 of the capacitance of the other terminals. FIG. 11 shows the attenuation ratio in the case of the fourth embodiment. It can be seen that the phenomenon in which the attenuation ratio seen at 10 Hz is positive is suppressed. Further, the attenuation ratio at 1 kHz is −13 dB, which is smaller than −8 dB in FIG. Therefore, it is possible to provide a battery management device having anti-aliasing filter performance that is balanced overall.

  In this embodiment, since there are twelve capacitors, such a configuration is adopted. However, when the number of capacitors is n, n times the voltage is applied to C0. Therefore, in such a case, only C0 may be set to 1 / n of the capacitance of the capacitor connected to the other terminal.

  The present invention has been summarized above. In the present invention, the capacitance value of one capacitor C0 is 1 / n of the capacitance value of Cn. With such a configuration, it is possible to provide a battery management device having a balanced anti-aliasing filter performance as a whole.

  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 designs can be made without departing from the spirit of the present invention described in the claims. It can be changed. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. Furthermore, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

Claims (4)

an integrated circuit that is electrically connected to both electrodes of each of the n battery cells via a voltage detection line, and detects a terminal voltage of each of the plurality of battery cells;
An integrated circuit having a voltage detection unit for detecting a terminal voltage of each of the n battery cells;
N + 1 resistors electrically connected to the voltage detection line;
N capacitors Cn connected between voltage detection lines between the resistor and the voltage detection unit;
A capacitor connected between the resistor of the lowest potential detection line connected to the integrated circuit and the voltage detection unit and between the GND of the integrated circuit, on the lowest potential side of the capacitor Cn When the position of the capacitor is k, the ratio of the values of the capacitors Cn satisfies (Equation 1).

A battery management device. an integrated circuit that is electrically connected to both electrodes of each of the n battery cells via a voltage detection line, and detects a terminal voltage of each of the plurality of battery cells;
An integrated circuit having a voltage detection unit for detecting a terminal voltage of each of the n battery cells;
N + 1 resistors electrically connected to the voltage detection line;
N capacitors Cn connected between voltage detection lines between the resistor and the voltage detection unit;
1 connected between the resistor of the lowest potential detection line connected to the integrated circuit and the voltage detector and between the resistor of the highest potential detection line connected to the integrated circuit and the voltage detector. A battery management device. 2. The battery management apparatus according to claim 1, wherein all of the n capacitors Cn have the same capacitance value. The battery management device according to claim 3, wherein a capacitance value of the one capacitor is 1 / n of a capacitance value of the Cn.

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