JP2019169471A - Battery system monitoring device - Google Patents

Abstract

To achieve management control of a battery pack using an accurate cell voltage measurement value.SOLUTION: A battery system monitoring device 10 for monitoring and controlling a battery system includes a battery monitoring circuit 100 provided to each cell group 120. Each battery monitoring circuit 100 has a cell voltage measurement section 6 that is connected to both electrodes of a unit battery cell 110 of corresponding one of the cell groups 120 via a voltage detection line 2 and measures a cell voltage of each unit battery cell 110 at each predetermined timing. An RC filter 4 having a resistor and a capacitor is connected to the voltage detection line 2. The cell voltage measurement section 6 makes a measurement interval of the cell voltage longer when an accumulated charge amount of the capacitor of the RC filter 4 changes.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an apparatus for monitoring a battery system.

  In a hybrid vehicle (HEV), an electric vehicle (EV), etc., in order to secure a desired high voltage, an assembled battery (battery system) configured by connecting a large number of single battery cells of a secondary battery is generally used. It has been. Conventionally, a battery monitoring circuit using an integrated circuit or the like is connected to such an assembled battery for every predetermined number of unit cells. This battery monitoring circuit measures the voltage between each battery cell (cell voltage) and performs balancing discharge to equalize the remaining capacity of each battery cell. Monitor and manage. During balancing, each single battery cell is discharged according to the remaining capacity, and a discharge current flows through the balancing resistor via a voltage detection line provided between each single battery cell and the battery monitoring circuit. At this time, a voltage drop corresponding to the magnitude of the impedance occurs in the voltage detection line.

  In recent years, a single battery cell in which voltage fluctuation with respect to a change in remaining capacity is smaller than in the past has been put into practical use. When such a single battery cell is used, higher measurement accuracy than before is required to accurately estimate the remaining capacity by measuring the cell voltage. Therefore, in the measurement of the cell voltage during balancing, the influence of the voltage drop on the voltage detection line as described above cannot be ignored. In view of this, a method has been proposed in which the cell voltage is accurately measured by correcting the voltage drop in the voltage detection line (see Patent Document 1).

JP 2011-75504 A

  In a general assembled battery, an RC filter is inserted between the single battery cell and the battery monitoring circuit in order to suppress an aliasing error caused by noise, voltage fluctuation or the like. Therefore, when balancing is started or stopped, a transient response corresponding to the time constant of the RC filter is generated in the cell voltage accordingly. However, in the method described in Patent Document 1, it is possible to accurately measure the cell voltage when a stable state is reached after the start of balancing and after a transient response has elapsed, but the cell voltage within the transient response period can be measured. Cannot be measured accurately. For this reason, it is difficult to realize management control of the assembled battery using accurate cell voltage measurement values.

  A battery system monitoring apparatus according to the present invention is for monitoring and controlling a battery system including a plurality of cell groups in which a plurality of single battery cells are connected in series, and a plurality of batteries provided for each cell group. A cell voltage measurement is provided that includes a monitoring circuit, the battery monitoring circuit being connected to both electrodes of each unit cell of the corresponding cell group via a voltage detection line, and measuring the cell voltage of each unit cell at a predetermined timing. A filter circuit having a resistor and a capacitor is connected to the voltage detection line, and the cell voltage measurement unit is configured to change the cell voltage when the accumulated charge amount of the capacitor of the filter circuit changes. This increases the measurement interval.

  According to the present invention, it is possible to realize management control of a battery pack using accurate cell voltage measurement values.

It is a figure which shows the structure of the battery system monitoring apparatus by one Embodiment of this invention. It is the figure which showed the detail of the connection circuit between the cell group and battery monitoring circuit in the 1st Embodiment of this invention. It is the figure which showed an example of the measurement timing of a cell voltage, and the mode of a change of balancing current and cell voltage. It is a figure which shows the example of the correction | amendment result of a cell voltage. It is a characteristic diagram which shows an example of the correction | amendment error of the cell voltage by the influence of the dispersion | variation in the time constant of RC filter. It is the figure which showed an example of the cell voltage measurement timing in this invention, and balancing control timing. It is the figure which showed the detail of the connection circuit between the cell group and battery monitoring circuit in the 2nd Embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following embodiments, an example in which the present invention is applied to a battery system monitoring device that monitors a battery system used in a hybrid vehicle (HEV) or the like will be described. The application range of the battery system monitoring device according to the present invention is not limited to monitoring the battery system mounted on the HEV. For example, the present invention can be widely applied to devices that monitor battery systems mounted on plug-in hybrid vehicles (PHEV), electric vehicles (EV), railway vehicles, and the like.

  In the following embodiment, a predetermined output voltage range, for example, 3.0 to 4.2 V (average output voltage: 3.2. A lithium ion battery having an output voltage range of 6V) is assumed. However, the battery system monitoring apparatus according to the present invention may control and monitor a battery system configured using a power storage / discharge device other than a lithium ion battery. In other words, if the SOC (State Of Charge) is too high (overcharge) or too low (overdischarge), it is necessary to limit its use, and any battery storage / discharge device is used to configure the battery system. May be. In the following description, the electricity storage / discharge device as a component of such a battery system is generically referred to as a single battery cell.

  In the embodiments described below, a plurality of (approximately several to a dozen) battery cells connected in series are called cell groups, and a plurality of cell groups connected in series are called battery systems. It is out. These may be collectively referred to as an assembled battery.

-First embodiment-
FIG. 1 is a diagram showing a configuration of a battery system monitoring apparatus 10 according to an embodiment of the present invention. The battery system monitoring apparatus 10 includes a battery controller 200 and a plurality of battery monitoring circuits 100 connected to each other according to a predetermined communication order. The battery system monitoring device 10 is mounted on an electric vehicle such as an electric vehicle or a hybrid vehicle together with the vehicle controller 400, the motor controller 300, the battery system 130, the inverter 340, the motor 350, and the like.

  The battery system 130 has a plurality of cell groups 120 connected in series. Each cell group 120 is configured by connecting a plurality of single battery cells 110 (hereinafter also simply referred to as cells) in series. For each cell 110, for example, a secondary battery such as a lithium ion battery is used.

  In the battery system monitoring apparatus 10, a loop communication circuit is provided between the battery controller 200 and each battery monitoring circuit 100. The battery controller 200 transmits a communication signal via the insulating element 201 to the battery monitoring circuit 100 having the highest communication order. Upon receiving this communication signal, the uppermost battery monitoring circuit 100 transfers the communication signal to the battery monitoring circuit 100 that is one order lower in the communication order. By sequentially performing these operations in each battery monitoring circuit 100, communication signals are transmitted in series in order from the highest battery monitoring circuit 100 to the lowest battery monitoring circuit 100. The battery monitoring circuit 100 that is the lowest in the communication order transmits a communication signal to the battery controller 200 via the insulating element 202. In this manner, communication signals are exchanged between the battery controller 200 and each battery monitoring circuit 100 via the loop communication circuit.

  The vehicle controller 400 determines the vehicle running speed, braking / driving force, and the like based on an operation signal from a vehicle driving operation device (not shown) such as an accelerator pedal, a brake pedal, or a shift lever operated by a driver of the electric vehicle. Control. Motor controller 300 controls battery controller 200 and inverter 340 based on the speed command and braking / driving force command from vehicle controller 400 to control the rotational speed and torque of motor 350.

  Battery controller 200 controls charging / discharging and SOC (State Of Charge) of battery system 130 based on the voltage, current, and temperature of battery system 130 detected by voltage sensor 210, current sensor 220, and temperature sensor 230, respectively. . The battery controller 200 controls the operation of each battery monitoring circuit 100 by exchanging communication signals with each battery monitoring circuit 100 as described above, and configures each cell group 120 in the battery system 130. The SOC of a plurality of cells 110 to be estimated is estimated. Based on this estimation result, a discharge (hereinafter referred to as balancing discharge) for correcting the variation in SOC between the cells 110 is performed so that the SOC of each cell 110 does not become non-uniform. In this way, the battery system monitoring device 10 monitors and controls the battery system 130.

  When the communication signal is exchanged with each battery monitoring circuit 100 as described above, the battery controller 200 outputs an activation signal (not shown) to each battery monitoring circuit 100 before that. The battery monitoring circuit 100 is activated. The activation signal is output via a signal path different from the communication signal. And if it confirms that each battery monitoring circuit 100 started, transmission of a communication signal will be started.

  In FIG. 1, as the battery system 130, an assembled battery is illustrated in which a plurality of cell groups 120 in which four cells 110 are connected in series are connected in series. However, the number of cells 110 constituting the cell group 120 is not limited to this, and may be less than four or four or more. In an electric vehicle such as an electric vehicle or a hybrid vehicle, many cells or cell groups are connected in series and parallel, and a high-voltage, high-capacity battery module having a voltage at both ends of about several hundred volts is generally used. The present invention can also be applied to such a high voltage, high capacity battery module.

  The battery monitoring circuit 100 is provided for each cell group 120 in which a plurality of cells 110 constituting the battery system 130 are grouped into a predetermined number (four in FIG. 1). For example, when 100 cells 110 are connected in series in the battery system 130 and are divided into groups of 4 cells, 25 cell groups 120 are provided in the battery system 130, and 25 cells are provided accordingly. The battery monitoring circuit 100 is arranged in the battery system monitoring apparatus 10.

  Each battery monitoring circuit 100 measures the cell voltage by detecting the voltage between each terminal of the positive electrode and the negative electrode for each cell 110 constituting the corresponding cell group 120 and transmits the cell voltage to the battery controller 200. The battery controller 200 estimates the SOC of each cell 110 based on the measurement result of the cell voltage of each cell 110 transmitted from each battery monitoring circuit 100 and outputs a balancing command to each battery monitoring circuit 100. Each battery monitoring circuit 100 performs energization control of the balancing current for each cell 110 in accordance with a balancing command from the battery controller 200. A balancing resistor 102 for limiting and determining the balancing current is provided for each cell 110 between each battery monitoring circuit 100 and the corresponding cell group 120.

  When the vehicle is driven, DC power charged in the battery system 130 is supplied to the smoothing capacitor 330 and the inverter 340 via the positive electrode side contactor 310 and the negative electrode side contactor 320. The inverter 340 converts the DC power supplied from the battery system 130 into AC power and applies it to the motor 350. The motor 350 is driven using this AC power. The inverter 340 is provided with a switching element (not shown), and switching from DC power to AC power is performed by switching the switching element. On the other hand, during braking of the vehicle, AC power generated by the motor 350 is converted into DC power by a diode element (not shown) provided in the inverter 340 and the smoothing capacitor 330. This DC power is applied to the battery system 130 through the positive electrode side contactor 310 and the negative electrode side contactor 320, and the battery system 130 is charged. In this way, direct-current power is exchanged between the battery system 130 and the inverter 340.

  Note that ripple noise and switching noise are generated with the operation of the inverter 340. These noises are reduced to some extent by the smoothing capacitor 330, but cannot be completely removed and flow into the battery system 130 to generate noise current. In proportion to the noise current, the noise voltage is superimposed on the voltage between the terminals of each cell 110 in the battery system 130. Since this noise becomes a cell voltage detection error, the input to the battery monitoring circuit 100 is suppressed by using the RC filter 4 shown in FIG.

  Next, details of a connection circuit between the cell group 120 and the battery monitoring circuit 100 in the battery system monitoring apparatus 10 of FIG. 1 will be described. FIG. 2 is a diagram showing details of a connection circuit between the cell group 120 and the battery monitoring circuit 100 according to the first embodiment of the present invention. Each cell group 120 and each battery monitoring circuit 100 arranged in correspondence in FIG. 1 are connected to each other via a connection circuit as shown in FIG. In FIG. 2, the six cells 110 constituting the cell group 120 are represented as cells 110a to 110f. However, the number of cells 110 constituting the cell group 120 is not limited to this. For example, as shown in FIG. 1, four cells 110 may be connected in series.

  Outside the battery system monitoring device 10, voltage detection lines 2 having a resistance component 3 are connected between the cells 110 a to 110 f of the cell group 120 and the battery monitoring circuit 100. In addition, the balancing resistor 102 and the RC filter 4 are connected between the cells 110 a to 110 f and the battery monitoring circuit 100 inside the battery system monitoring device 10. As described above, the RC filter 4 is for suppressing noise that becomes a measurement error of the cell voltage, and is configured using a resistor and a capacitor.

  The battery monitoring circuit 100 functionally includes a cell voltage measurement unit 6, a balancing control unit 7, and a discharge switch 8. The cell voltage measurement unit 6 measures the cell voltages of the cells 110a to 110f input via the voltage detection line 2 and the RC filter 4 at every predetermined timing. The cell voltage measured by the cell voltage measuring unit 6 is transmitted to the battery controller 200 by the communication signal described above.

  The discharge switch 8 is provided for each of the cells 110a to 110f. In FIG. 2, each discharge switch 8 is represented by reference numerals 8a to 8f in association with the cells 110a to 110f. The balancing control unit 7 switches the open / close states of the discharge switches 8a to 8f according to instructions from the battery controller 200, respectively. Thus, the switching state of the discharge switches 8a to 8f is switched by the balancing control unit 7, thereby switching the state of the discharge current flowing from the cells 110a to 110f via the balancing resistor 102, and the balancing discharge of the cells 110a to 110f. Is done.

  Next, a method for measuring the cell voltage by the cell voltage measuring unit 6 will be described. FIG. 3 is a diagram showing an example of cell voltage measurement timing by the cell voltage measurement unit 6 and how the balancing current and cell voltage change. In FIG. 3, a waveform 31 indicated by a solid line on the upper side represents the cell voltage of the upper cell, and a waveform 32 indicated by a broken line represents the cell voltage of the lower cell. A waveform 33 indicated by a solid line on the lower side indicates a balancing current flowing from the upper cell through the balancing resistor 102, and a waveform 34 indicated by a broken line indicates a balancing current flowing from the lower cell via the balancing resistor 102. Is shown. The remaining waveform 35 shows the measurement timing of the cell voltage. Note that the upper cell is a cell 110 that corresponds to an odd number when counted from the high voltage side in the cell group 120, and corresponds to the cells 110a, 110c, and 110e in FIG. On the other hand, the lower cells are the cells 110 that are even-numbered when counted from the high voltage side in the cell group 120, and correspond to the cells 110b, 110d, and 110f in FIG.

  In FIG. 3, the value on the left vertical axis represents the cell voltage value indicated by the waveforms 31 and 32. On the other hand, the values on the right vertical axis indicate the balancing current values indicated by the waveforms 33 and 34, respectively. The value on the horizontal axis indicates time, which is commonly used for the waveforms 31-35.

  The cell voltage measurement unit 6 measures each cell voltage of the cells 110a to 110f every 0.02 seconds, as shown by the waveform 35. The balancing control unit 7 controls the discharge switches 8a to 8f at a timing synchronized with the cell voltage measurement timing.

  When the operation of the battery monitoring circuit 100 is started at time 0, the balancing control unit 7 shortens the discharge switches 8a, 8c and 8e corresponding to the upper cell immediately after the cell voltage measurement performed 0.02 seconds later. Close only time. Thereafter, immediately after the next cell voltage measurement timing, the discharge switches 8b, 8d and 8f corresponding to the lower cells are closed for a short time. At this time, as indicated by waveforms 33 and 34, balancing currents flow alternately in the upper cell and the lower cell. By detecting this balancing current, the battery monitoring circuit 100 can detect disconnection of the voltage detection line 2.

  Subsequently, the balancing control unit 7 controls the discharge switch corresponding to the cell to be balanced among the discharge switches 8a, 8c and 8e corresponding to the higher-order cell and switches it to the closed state. As a result, among the cells 110a, 110c, and 110e, which are upper cells, the positive electrode and the negative electrode of the balancing target cell are connected via the balancing resistor 102, and the cell is discharged and balanced as shown by the waveform 33. Current flows.

  When the balancing discharge of the upper cell is completed, the disconnection detection of the voltage detection line 2 is performed again in the battery monitoring circuit 100. At this time, as described above, the balancing control unit 7 alternately closes the discharge switches 8a, 8c and 8e corresponding to the upper cell and the discharge switches 8b, 8d and 8f corresponding to the lower cell for a short time. . Thereafter, the balancing control unit 7 performs the same control as the discharge switches 8a, 8c, and 8e corresponding to the upper cell on the discharge switches 8b, 8d, and 8f corresponding to the lower cell. That is, among the discharge switches 8b, 8d and 8f corresponding to the lower cells, the discharge switch corresponding to the cell to be balanced is controlled to be switched to the closed state. As a result, among the cells 110b, 110d, and 110f, which are lower cells, the positive electrode and the negative electrode of the balancing target cell are connected via the balancing resistor 102, and the cell is discharged and balanced as shown by the waveform 34. Current flows.

  When the discharge switches 8a to 8f are switched at the timing described above, the cell voltages of the upper cell and the lower cell change as shown by waveforms 31 and 32, respectively. That is, in order to detect disconnection of the voltage detection line 2, first, when the discharge switches 8a, 8c and 8e corresponding to the upper cell are closed for a short time and a balancing current is supplied to the cells 110a, 110c and 110e, As a result, the cell voltage of the upper cell decreases, and the cell voltage of the lower cell increases. When these discharge switches are returned to the open state, the balancing current becomes 0, and the cell voltages of the upper cell and the lower cell change toward the original level. Subsequently, when the discharge switches 8b, 8d and 8f corresponding to the lower cells are closed for a short time and a balancing current is supplied to the cells 110b, 110d and 110f, the cell voltage of the lower cells is reduced accordingly, The cell voltage of the cell increases. When these discharge switches are returned to the open state, the balancing current becomes 0, and the cell voltages of the upper cell and the lower cell change toward the original level.

  After the disconnection of the voltage detection line 2 is detected, balancing discharge of the upper cell or the lower cell is performed. In the balancing discharge of the upper cell, if the cell to be balanced is discharged by closing the discharge switch 8a, 8c, or 8e and the balancing current is supplied, the cell voltage of the upper cell decreases accordingly, and the lower cell The cell voltage increases. When a predetermined time elapses after the balancing current starts to flow, these cell voltages are stabilized at a certain level. Thereafter, when the discharge switch is returned to the open state, the balancing current is cut off, and the cell voltages of the upper cell and the lower cell change toward the original level.

  On the other hand, in the balancing discharge of the lower cell, when the cell to be balanced is discharged by closing the discharge switch 8b, 8d or 8f and the balancing current is supplied, the cell voltage of the lower cell is lowered accordingly, The cell voltage of the side cell increases. When a predetermined time elapses after the balancing current starts to flow, these cell voltages are stabilized at a certain level. Thereafter, when the discharge switch is returned to the open state, the balancing current is cut off, and the cell voltages of the upper cell and the lower cell change toward the original level.

  As described above, when the discharge switches 8a to 8f are switched from the open state to the closed state or from the closed state to the open state, the cell voltage fluctuates transiently for a certain period thereafter. Such a period in which the cell voltage fluctuates transiently is hereinafter referred to as a transient response period. In the example of FIG. 3, the period shown in the figure corresponds to the transient response period. During this period, in order to detect disconnection of the voltage detection line 2, the discharge switches 8a, 8c and 8e corresponding to the upper cell are switched from the open state to the closed state, and then the balancing discharge of the upper cell or the lower cell is performed. This is the period until the cell voltage stabilizes. The length of this transient response period is determined according to the time constant of the RC filter 4.

  In the battery system monitoring apparatus 10 of the present embodiment, the cell voltage measurement unit 6 corrects the measurement result of the cell voltage in consideration of the fluctuation of the cell voltage during the transient response period. This point will be described in detail below.

  FIG. 4 is a diagram illustrating an example of the correction result of the cell voltage. In FIG. 4, each point represented by a point denoted by reference numeral 41 represents a measured value of the cell voltage before correction. The measured value of the cell voltage before correction includes an error due to a voltage drop caused by the balancing current flowing through the resistance component 3 shown in FIG. On the other hand, the broken line shown with the code | symbol 42 represents the cell voltage after correction | amendment by the conventional correction method. The corrected cell voltage is obtained by correcting the voltage drop of the resistance component 3 from the measured value of the cell voltage before correction. In this way, by correcting the voltage drop due to the resistance component 3, it is possible to reduce an error included in the measured value of the cell voltage.

  On the other hand, the solid line indicated by reference numeral 43 represents the corrected cell voltage obtained in the battery system monitoring apparatus 10 of the present embodiment. In the battery system monitoring device 10, the cell voltage measurement unit 6 of the battery monitoring circuit 100 corrects the voltage drop of the resistance component 3 with respect to the measured value of the cell voltage of each cell 110. At this time, for the cell voltage measured within the transient response period, a correction value taking into consideration the fluctuation of the cell voltage as shown in FIG. 3 is used. Thereby, the error contained in the measured value of the cell voltage can be further reduced as compared with the conventional correction method.

  However, if the time constant of the RC filter 4 varies, the cell voltage measured within the transient response period varies under the influence of the variation of the time constant of the RC filter 4. Therefore, when the cell voltage is corrected as described above, it is difficult to obtain an accurate correction value for the cell voltage.

  FIG. 5 is a characteristic diagram showing an example of a cell voltage correction error due to the influence of variations in the time constant of the RC filter 4. In FIG. 5, a diagram 51 shows the relationship between the time from the switching of the balancing current to the cell voltage measurement and the worst value of the correction error of the cell voltage when the time constant of the RC filter 4 varies to the plus side. . Further, the diagram 52 shows the relationship between the time from switching of the balancing current to the cell voltage measurement and the worst value of the correction error of the cell voltage when the time constant of the RC filter 4 varies on the negative side. FIG. 5 shows an example where the time constant of the RC filter 4 varies in the range of 10 ms ± 5 ms. As shown in FIG. 5, when the cell voltage is measured after about 10 ms has elapsed since the switching of the balancing current, it can be seen that a cell voltage correction error occurs in the range of about +4.5 mV to −1 mV.

  Therefore, in the battery system monitoring apparatus 10 of the present embodiment, the cell voltage measurement timing is changed so that the cell voltage is not measured within a certain time from the switching of the balancing current that increases the cell voltage correction error. The specific method will be described below.

  FIG. 6 is a diagram showing an example of the relationship between the cell voltage measurement timing and the balunsin control timing in one embodiment of the present invention. The balancing controller 7 controls the discharge switches 8a to 8f as described above, thereby performing disconnection diagnosis and balancing discharge of the voltage detection line 2 at the timings shown in FIGS. 6 (a) and 6 (b). On the other hand, the cell voltage measurement unit 6 measures the cell voltage of each cell 110 every 20 ms. At this time, the cell voltage measuring unit 6 changes the measurement timing of the cell voltage within a certain time from the switching of the balancing current by a method as shown in either FIG. 6A or FIG. 6B.

  FIG. 6A shows an example of delaying the cell voltage measurement timing. For example, as shown in FIG. 6A, the cell voltage measurement unit 6 performs cell voltage measurement at the start of disconnection diagnosis indicated by reference numeral 61 and cell voltage measurement at the start of balancing discharge indicated by reference numeral 62, respectively. Delay by the delay time. As a result, the cell voltage measurement timing immediately after the disconnection diagnosis is started changes from the original measurement timing indicated by reference numeral 61 to the delayed measurement timing indicated by reference numeral 61a. In addition, the cell voltage measurement timing immediately after the start of balancing discharge changes from the original measurement timing indicated by reference numeral 62 to the delayed measurement timing indicated by reference numeral 62a.

  As described above, the cell voltage measurement unit 6 performs the cell voltage measurement timing within the transient response period in which the accumulated charge amount of the capacitor of the RC filter 4 is changed by switching the state of the discharge current by the discharge switches 8a to 8f. Is changed so that the cell voltage measurement interval is increased. Thereby, in the transient response period, the correction error can be reduced by preventing the measurement of the cell voltage at the timing when the correction error of the cell voltage becomes large. Furthermore, by using the accurate cell voltage measurement value thus obtained, the battery monitoring circuit 100 can appropriately perform monitoring and control of the corresponding cell group 120.

  FIG. 6B shows an example in which the measured value of the cell voltage is invalidated. For example, as shown in FIG. 6B, the cell voltage measurement unit 6 invalidates the cell voltage measurement at the start of the disconnection diagnosis indicated by reference numeral 61 and the cell voltage measurement at the start of balancing discharge indicated by reference numeral 62, respectively. To do. At this time, the cell voltage measurement may be invalidated by skipping the measurement of the cell voltage, that is, by not performing the measurement itself. Alternatively, the cell voltage measurement may be invalidated by invalidating the obtained cell voltage measurement value so that it is not used in the subsequent processing. As a result, the cell voltage measurement timing immediately after the disconnection diagnosis is started changes from the original measurement timing indicated by reference numeral 61 to the next measurement timing indicated by reference numeral 61b. Further, the cell voltage measurement timing immediately after the start of the balancing discharge changes from the original measurement timing indicated by reference numeral 62 to the next measurement timing indicated by reference numeral 62b.

  As described above, the cell voltage measurement unit 6 measures the cell voltage within the transient response period in which the accumulated charge amount of the capacitor of the RC filter 4 is changed by switching the state of the discharge current by the discharge switches 8a to 8f. Is invalidated to increase the cell voltage measurement interval. Thereby, in the transient response period, the correction error can be reduced by preventing the measurement of the cell voltage at the timing when the correction error of the cell voltage becomes large. Furthermore, by using the accurate cell voltage measurement value thus obtained, the battery monitoring circuit 100 can appropriately perform monitoring and control of the corresponding cell group 120.

  The cell voltage measurement unit 6 can measure the cell voltage at every predetermined measurement timing by executing a program stored in a memory (not shown) included in the battery monitoring circuit 100, for example. The change in the cell voltage measurement timing as described above can be realized by this program setting. For example, the measurement timing corresponding to the transient response period is specified by counting the number of measurements, and the cell voltage is measured at the measurement timing by adding a preset delay time to the normal measurement timing. Thereby, as shown in FIG. 6A, the cell voltage measurement timing in the transient response period can be delayed. Alternatively, the cell voltage measured at the measurement timing is output with a predetermined invalidation flag. Thereby, as shown in FIG.6 (b), the measurement result of the cell voltage in a transient response period can be nullified. In addition to this, the measurement timing of the cell voltage can be changed by any method such as using a logic circuit.

  According to the 1st Embodiment of this invention demonstrated above, there exists the following effect.

(1) The battery system 130 includes a plurality of cell groups 120 in which a plurality of single battery cells 110 are connected in series. The battery system monitoring device 10 that monitors and controls the battery system 130 is provided for each cell group 120. The battery monitoring circuit 100 is provided. Each battery monitoring circuit 100 is connected to both poles of each unit cell 110 of the corresponding cell group 120 via the voltage detection line 2 and measures the cell voltage of each unit cell 110 at a predetermined timing. Part 6. An RC filter 4 having a resistor and a capacitor is connected to the voltage detection line 2. The cell voltage measurement unit 6 lengthens the cell voltage measurement interval when the amount of charge stored in the capacitor of the RC filter 4 changes. Since it did in this way, in the battery system monitoring apparatus 10, management control of the battery system 130 using an exact cell voltage measured value is realizable.

(2) The battery system monitoring device 10 is electrically connected to the voltage detection line 2 and the RC filter 4, and includes a balancing resistor 102 for discharging each single battery cell 110 of the cell group 120 corresponding to the battery monitoring circuit 100. Further prepare. The battery monitoring circuit 100 includes a discharge switch 8 that switches the state of the discharge current that flows from each unit cell 110 of the corresponding cell group 120 via the balancing resistor 102, and a balancing control unit 7 that controls the discharge switch 8. The cell voltage measurement unit 6 lengthens the cell voltage measurement interval when the amount of accumulated charge in the capacitor of the RC filter 4 changes by switching the state of the discharge current by the discharge switch 8. Specifically, the cell voltage measurement unit 6 is changed so as to delay the measurement timing of the cell voltage when the accumulated charge amount of the capacitor of the RC filter 4 changes, for example, as shown in FIG. Increase the cell voltage measurement interval. Further, the cell voltage measuring unit 6 measures the cell voltage by invalidating the measurement result of the cell voltage when the accumulated charge amount of the capacitor of the RC filter 4 changes, for example, as shown in FIG. Increase the interval. Since it did in this way, when measuring a cell voltage by a fixed space | interval, the measurement period of a cell voltage can be lengthened at arbitrary timings.

  As described above, when the cell voltage measurement unit 6 changes the measurement timing of the cell voltage, if the time from the cell voltage measurement to the switching of the balancing current is short, the balancing current is measured after the cell voltage measurement. You may make it switch. That is, the balancing control unit 7 may control the discharge switch 8 so that the state of the discharge current is switched after the cell voltage measurement unit 6 measures the cell voltage. In this way, it is possible to accurately measure the cell voltage while avoiding fluctuations in the cell voltage within the transient response period.

  When the cell voltage measurement timing is delayed as shown in FIG. 6A, the cell voltage measurement unit 6 delays the cell voltage measurement timing, and then the cell voltage measurement interval becomes the original measurement interval. Until then, the cell voltage measurement timing may be advanced in stages. For example, after delaying the measurement timing of the cell voltage by 15 ms, the measurement timing of the next cell voltage is delayed by 10 ms, and further the measurement timing of the next cell voltage is delayed by 5 ms, so that the original measurement interval is gradually increased by 5 ms. The cell voltage measurement timing is advanced. In this way, even when the measurement timing of the cell voltage is delayed, sudden fluctuations in the subsequent measurement timing can be suppressed and adverse effects on the management control of the battery system 130 can be reduced.

-Second Embodiment-
Next, a second embodiment of the present invention will be described. In the first embodiment, the example in which the cell voltage measurement timing is changed when switching the balancing current has been described. On the other hand, in the second embodiment, an example will be described in which the cell voltage measurement timing is changed when the connection state between the voltage detection lines is changed in the diagnosis of the cell voltage measurement unit.

  FIG. 7 is a diagram showing details of a connection circuit between the cell group 120 and the battery monitoring circuit 100a in the second embodiment of the present invention. In the battery system monitoring apparatus 10a of the present embodiment, a battery monitoring circuit 100a is provided corresponding to each cell group 120 instead of the battery monitoring circuit 100 described in the first embodiment. As shown in FIG. 7, the battery monitoring circuit 100 a includes a cell voltage measurement unit 6 a instead of the cell voltage measurement unit 6 of FIG. 2, and further includes a diagnosis control unit 80. For easy understanding of the configuration of the cell voltage measuring unit 6a, part of the wiring connected to the discharge switch 8 in the battery monitoring circuit 100a is omitted in FIG.

  The cell voltage measurement unit 6 a has a diagnostic circuit unit 70. The diagnostic circuit unit 70 is used for diagnosis of the cell voltage measurement unit 6a, and includes resistors 71a to 71f and diagnostic switches 72a to 72f provided corresponding to the cells 110a to 110f, respectively. The switching state of the diagnostic switches 72a to 72f is controlled by the diagnostic control unit 80 as follows.

  The battery monitoring circuit 100a diagnoses the cell voltage measuring unit 6a in response to an instruction from the battery controller 200. When diagnosing the cell voltage measurement unit 6a, the diagnosis control unit 80 controls any one of the diagnosis switches 72a to 72f so as to switch from the off state to the on state for a short time, thereby corresponding to the diagnosis switch. The connection state between the voltage detection lines 2 connected to both electrodes of the cell 110 is switched. Then, the cell voltage measurement unit 6a measures the cell voltage of the cell 110, that is, the potential difference between the voltage detection lines 2 connected to both electrodes of the cell 110. If the cell voltage measuring unit 6a can measure the cell voltage correctly at this time, a change in the measured value of the cell voltage occurs before and after switching due to a voltage drop in one of the resistors 71a to 71f. However, if the cell voltage measurement unit 6a cannot correctly measure the cell voltage due to the erroneous selection of the cell 110 that is not the measurement target, the measured value of the cell voltage does not change before and after switching. By using this, the battery monitoring circuit 100a can diagnose the cell voltage measurement unit 6a related to the cell voltage measurement of the cell 110. Further, by performing such a diagnosis on all the cells 110a to 110f of the cell group 120, the battery monitoring circuit 100a diagnoses whether or not the cell voltage measuring unit 6a is correctly measuring the cell voltage. Can do.

  However, in the diagnosis of the cell voltage measurement unit 6a described above, current flows through the capacitor of the RC filter 4 when the connection state between the voltage detection lines 2 is switched by the diagnosis switches 72a to 72f, so that an error occurs in the measured value of the cell voltage. Will occur. In order to avoid this, it is necessary not to measure the cell voltage until the transient response period corresponding to the time constant of the RC filter 4 elapses after the connection state between the voltage detection lines 2 is switched. Therefore, the diagnosis takes time. Further, it is conceivable to correct the measured value of the cell voltage by the method described in the first embodiment, but in this case as well, if the time constant of the RC filter 4 varies as described above, It becomes difficult to obtain an accurate cell voltage correction value.

  Therefore, in the battery system monitoring apparatus 10a of the present embodiment, the cell voltage is measured so that the cell voltage is not measured within a certain time from the switching of the connection state between the voltage detection lines 2 in which the correction error of the cell voltage becomes large. Change the measurement timing. Specifically, for example, as described with reference to FIG. 6A, the cell voltage measurement performed at the time of diagnosis of the cell voltage measurement unit 6a is delayed by a predetermined delay time. That is, in order to diagnose the cell voltage measuring unit 6a, the cell is measured in the transient response period in which the accumulated charge amount of the capacitor of the RC filter 4 is changed by switching the connection state between the voltage detection lines 2 by the diagnostic switches 72a to 72f. The cell voltage measurement interval is lengthened by changing the voltage measurement timing to be delayed. Alternatively, for example, as described with reference to FIG. 6B, the cell voltage measurement performed at the time of diagnosis of the cell voltage measurement unit 6a is invalidated. That is, in order to diagnose the cell voltage measuring unit 6a, the cell is measured in the transient response period in which the accumulated charge amount of the capacitor of the RC filter 4 is changed by switching the connection state between the voltage detection lines 2 by the diagnostic switches 72a to 72f. Invalidate the voltage measurement results and increase the cell voltage measurement interval. Thereby, in the transient response period, the correction error can be reduced by preventing the measurement of the cell voltage at the timing when the correction error of the cell voltage becomes large. Furthermore, by using the accurate cell voltage measurement value thus obtained, the battery monitoring circuit 100a can appropriately perform monitoring and control of the corresponding cell group 120.

  The cell voltage measurement unit 6a can measure the cell voltage at every predetermined measurement timing by executing a program stored in a memory (not shown) included in the battery monitoring circuit 100a, for example. The change in the cell voltage measurement timing as described above can be realized by this program setting. In addition to this, the measurement timing of the cell voltage can be changed by any method such as using a logic circuit.

  According to the 2nd Embodiment of this invention demonstrated above, there exist the following effects.

(1) Similar to the cell voltage measurement unit 6 described in the first embodiment, the cell voltage measurement unit 6a increases the cell voltage measurement interval when the accumulated charge amount of the capacitor of the RC filter 4 changes. . Since it did in this way, management control of the battery system 130 using an exact cell voltage measured value is realizable in the battery system monitoring apparatus 10a.

(2) The battery monitoring circuit 100a diagnoses the cell voltage measurement unit 6a, and a diagnostic switch 72a that switches a connection state between the voltage detection lines 2 connected to both electrodes of each single battery cell 110 of the corresponding cell group 120. To 72f and a diagnosis control unit 80 for controlling the diagnosis switches 72a to 72f. The cell voltage measurement unit 6a increases the measurement interval of the cell voltage when the accumulated charge amount of the capacitor of the RC filter 4 changes by switching the connection state between the voltage detection lines 2 using the diagnostic switches 72a to 72f. Specifically, the cell voltage measurement unit 6a is changed so as to delay the measurement timing of the cell voltage when the accumulated charge amount of the capacitor of the RC filter 4 changes, for example, as shown in FIG. This increases the cell voltage measurement interval. The cell voltage measurement unit 6a invalidates the cell voltage measurement result when the accumulated charge amount of the capacitor of the RC filter 4 changes, for example, as shown in FIG. Increase the voltage measurement interval. Since it did in this way, when measuring a cell voltage by a fixed space | interval, the measurement period of a cell voltage can be lengthened at arbitrary timings.

  The embodiments and modifications described above are merely examples, and the present invention is not limited to these contents as long as the features of the invention are not impaired.

2 Voltage detection line 3 Resistance component 4 RC filter 6, 6a Cell voltage measurement unit 7 Balancing control unit 8 Discharge switch 10, 10a Battery system monitoring device 70 Diagnosis circuit unit 80 Diagnosis control unit 100, 100a Battery monitoring circuit 102 Balancing resistor 110 Cell 120 cell group 130 battery system 200 battery controller 210 voltage sensor 220 current sensor 230 temperature sensor 300 motor controller 310 positive side contactor 320 negative side contactor 330 smoothing capacitor 340 inverter 350 motor 400 vehicle controller

A battery system monitoring apparatus according to the present invention is for monitoring and controlling a battery system including a plurality of cell groups in which a plurality of single battery cells are connected in series, and a plurality of batteries provided for each cell group. A cell voltage measurement is provided that includes a monitoring circuit, the battery monitoring circuit being connected to both electrodes of each unit cell of the corresponding cell group via a voltage detection line, and measuring the cell voltage of each unit cell at a predetermined timing. A filter circuit having a resistor and a capacitor is connected to the voltage detection line, and the cell voltage measurement unit is configured to perform the transient response period in which the accumulated charge amount of the capacitor of the filter circuit changes. The cell voltage measurement interval is lengthened and the cell voltage measurement is performed at least once within the transient response period .

Claims (7)

A battery system monitoring device for monitoring and controlling a battery system including a plurality of cell groups in which a plurality of single battery cells are connected in series,
A plurality of battery monitoring circuits provided for each cell group,
The battery monitoring circuit has a cell voltage measurement unit that is connected to both electrodes of each single battery cell of the corresponding cell group via a voltage detection line and measures the cell voltage of each single battery cell at a predetermined timing,
A filter circuit having a resistor and a capacitor is connected to the voltage detection line,
The cell voltage measuring unit is a battery system monitoring device that lengthens a measurement interval of the cell voltage when an accumulated charge amount of a capacitor of the filter circuit changes. The battery system monitoring device according to claim 1,
The battery further includes a balancing resistor that is electrically connected to the voltage detection line and the filter circuit, and discharges each single battery cell of the cell group corresponding to the battery monitoring circuit,
The battery monitoring circuit includes a discharge switch that switches a state of a discharge current flowing from each single battery cell of a corresponding cell group via the balancing resistor, and a balancing control unit that controls the discharge switch,
The cell voltage monitoring unit extends the cell voltage measurement interval when the accumulated charge amount of the capacitor of the filter circuit changes by switching the state of the discharge current by the discharge switch. The battery system monitoring device according to claim 1,
The battery monitoring circuit includes a diagnostic switch for switching a connection state between the voltage detection lines connected to both electrodes of each single battery cell of a corresponding cell group in order to diagnose the cell voltage measurement unit, and the diagnostic switch. A diagnostic control unit for controlling,
The cell voltage measurement unit extends the cell voltage measurement interval when the accumulated charge amount of the capacitor of the filter circuit changes by switching a connection state between the voltage detection lines by the diagnostic switch. apparatus. In the battery system monitoring device according to any one of claims 1 to 3,
The battery voltage monitoring unit extends the cell voltage measurement interval by changing the cell voltage measurement unit so as to delay the measurement timing of the cell voltage when the accumulated charge amount of the capacitor of the filter circuit changes. In the battery system monitoring device according to any one of claims 1 to 3,
The cell voltage monitoring unit extends the cell voltage measurement interval by invalidating the measurement result of the cell voltage when the accumulated charge amount of the capacitor of the filter circuit changes. The battery system monitoring device according to claim 2,
The balancing control unit is a battery system monitoring device that controls the discharge switch so that the state of the discharge current is switched after the cell voltage measurement unit measures the cell voltage. The battery system monitoring device according to claim 4,
The cell voltage monitoring unit is a battery system monitoring device that delays the measurement timing of the cell voltage and then advances the measurement timing of the cell voltage stepwise until the measurement interval of the cell voltage becomes the original measurement interval.

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