JP2021018946A - Battery monitoring device - Google Patents

Abstract

To provide a battery monitoring device capable of downsizing and capable of improving calculation accuracy of complex impedance.SOLUTION: A battery monitoring device 50 monitors a status of a battery cell 42 including a plurality of electrodes and electrolyte. The battery monitoring device 50 includes a voltage measurement unit 52 for measuring a voltage across the battery cell 42, a low-pass filter 55c provided between the battery cell 42 and the voltage measurement unit 52, a current modulation circuit 56 for outputting a sine wave signal, a response signal input unit 52 connected to the battery cell 42 for inputting a response signal of the battery cell 42 against the sine wave signal, a high-pass filter 70 provided between the battery cell 42 and an input/output unit 52, and a microcontroller 53 for calculating complex impedance of the battery cell 42 based on the response signal. The high-pass filter 70 is connected between the low-pass filter 55c and the voltage measurement unit 52, and connected to the battery cell 42 through the low-pass filter 55c.SELECTED DRAWING: Figure 2

Description

The present invention relates to a battery monitoring device.

Conventionally, in order to monitor the state of a storage battery, the complex impedance of the storage battery has been measured (for example, Patent Document 1). In the invention described in Patent Document 1, a square wave signal is applied to the storage battery by the power controller, and the complex impedance characteristic is calculated based on the response signal. Then, based on this complex impedance characteristic, the deterioration state of the storage battery and the like were determined.

Japanese Patent No. 6226261

In this complex impedance measurement method, in order to improve the calculation accuracy of the complex impedance, it is preferable to provide a bandpass filter that removes noise superimposed on the response signal. However, when the bandpass filter is provided, there arises a problem that the battery monitoring device becomes large and the cost increases due to the capacitors and resistors constituting the bandpass filter.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a battery monitoring device that can be miniaturized and can improve the calculation accuracy of complex impedance.

A means for solving the above problem is in a battery monitoring device that monitors the state of a storage battery including an electrolyte and a plurality of electrodes, between a voltage measuring unit that measures the voltage of the storage battery and the storage battery and the voltage measuring unit. A low-pass filter having a first cutoff frequency, a signal control unit that outputs a predetermined AC signal, a response signal input unit that is connected to the storage battery and inputs a response signal of the storage battery to the AC signal, and a response signal input unit. A high-pass filter provided between the storage battery and the response signal input unit and having a second cutoff frequency lower than the first cutoff frequency, and a calculation for calculating the complex impedance of the storage battery based on the response signal. The high-pass filter is connected between the low-pass filter and the voltage measuring unit, and is connected to the storage battery via the low-pass filter.

In the battery monitoring device, the voltage of the storage battery to be monitored is generally measured, and a low-pass filter for removing noise superimposed on the voltage of the storage battery is provided. In this means, a bandpass filter for a response signal is provided by using the lowpass filter. That is, the low-pass filter constituting the bandpass filter for the response signal and the low-pass filter among the high-pass filters have the same configuration as the low-pass filter for the voltage of the storage battery. Therefore, the number of parts of the battery monitoring device can be reduced, the size can be reduced, and the cost can be reduced as compared with the case where the configuration is different from that of the low-pass filter for the voltage of the storage battery.

Further, by making the low-pass filter a common configuration, the number of low-pass filters connected to the storage battery can be reduced, and the number of wirings and terminals for connecting the storage battery and the low-pass filter can be reduced.

Further, in this means, a response signal is input via a bandpass filter configured by using the lowpass filter. Therefore, it is possible to improve the calculation accuracy of the complex impedance as compared with the case where there is no bandpass filter.

Schematic block diagram of the power supply system. The block diagram of the battery monitoring apparatus of 1st Embodiment. The figure which shows the frequency characteristic of a filter. The flowchart of the complex impedance calculation process of 1st Embodiment. The block diagram of the battery monitoring apparatus of 2nd Embodiment. The block diagram of the battery monitoring apparatus of 3rd Embodiment. The flowchart of the complex impedance calculation process of 3rd Embodiment. The block diagram of the battery monitoring apparatus of 4th Embodiment. The figure which shows the frequency characteristic of a filter. The flowchart of the complex impedance calculation process of 4th Embodiment. The block diagram of another example battery monitoring device. The block diagram of another example battery monitoring device.

(First Embodiment)
Hereinafter, a first embodiment in which the “battery monitoring device” is applied to a power supply system of a vehicle (for example, a hybrid vehicle or an electric vehicle) will be described with reference to the drawings.

As shown in FIG. 1, the power supply system 10 includes a motor 20 as a rotary electric machine, an inverter 30 as a power converter for passing a three-phase current to the motor 20, a rechargeable battery 40, and a battery. It includes a battery monitoring device 50 that monitors the state of 40, and an ECU 60 that controls a motor 20 and the like.

The motor 20 is an in-vehicle main engine, and is capable of transmitting power to drive wheels (not shown). In this embodiment, a three-phase permanent magnet synchronous motor is used as the motor 20.

The inverter 30 is composed of a full bridge circuit having the same number of upper and lower arms as the number of phases of the phase windings, and the energizing current is generated in each phase winding by turning on / off the switch (semiconductor switching element) provided in each arm. It will be adjusted.

The inverter 30 is provided with an inverter control device (not shown), and the inverter control device controls energization by turning on / off each switch in the inverter 30 based on various detection information in the motor 20 and demands for power running drive and power generation. To carry out. As a result, the inverter control device supplies electric power from the assembled battery 40 to the motor 20 via the inverter 30 to drive the motor 20 by power running. Further, the inverter control device generates electric power based on the power from the drive wheels, converts the generated electric power through the inverter 30 and supplies the generated electric power to the assembled battery 40 to charge the assembled battery 40.

The assembled battery 40 is electrically connected to the motor 20 via the inverter 30. The assembled battery 40 has a terminal-to-terminal voltage of, for example, 100 V or more, and is configured by connecting a plurality of battery modules 41 in series. The battery module 41 is configured by connecting a plurality of battery cells 42 in series. As the battery cell 42, for example, a lithium ion storage battery or a nickel hydrogen storage battery can be used. Each battery cell 42 is a storage battery having an electrolyte and a plurality of electrodes.

The positive electrode side terminal of the electric load such as the inverter 30 is connected to the positive electrode side power supply path L1 connected to the positive electrode side power supply terminal of the assembled battery 40. Similarly, the negative electrode side terminal of the electric load such as the inverter 30 is connected to the negative electrode side power supply path L2 connected to the negative electrode side power supply terminal of the assembled battery 40. A relay switch SMR (system main relay switch) is provided in each of the positive electrode side power supply path L1 and the negative electrode side power supply path L2, and the relay switch SMR can switch between energization and energization cutoff.

The battery monitoring device 50 is a device that monitors the storage state (SOC), deterioration state (SOH), and the like of each battery cell 42. In the first embodiment, the battery monitoring device 50 is provided for each battery cell 42. The battery monitoring device 50 is connected to the ECU 60 and outputs the state of each battery cell 42 and the like. The configuration of the battery monitoring device 50 will be described later.

The ECU 60 requests the inverter control device for power running drive and power generation based on various information. The various information includes, for example, accelerator and brake operation information, vehicle speed, and the state of the assembled battery 40.

Next, the battery monitoring device 50 will be described in detail. As shown in FIG. 2, in the first embodiment, the battery monitoring device 50 is provided for each battery cell 42.

The battery monitoring device 50 includes an ASIC unit 50a, a filter unit 55, and a current modulation circuit 56. The ASIC unit 50a is formed as an integrated circuit, and includes a stabilized power supply unit 51, an input / output unit 52, a microcomputer unit 53 as a calculation unit, and a communication unit 54.

The stabilized power supply unit 51 is connected to the power supply line of the battery cell 42, and supplies the power supplied from the battery cell 42 to the input / output unit 52, the microcomputer unit 53, and the communication unit 54. The input / output unit 52, the microcomputer unit 53, and the communication unit 54 are driven based on this electric power.

The input / output unit 52 is connected to the battery cell 42 to be monitored. Specifically, the input / output unit 52 has a DC voltage input terminal 57 capable of inputting (measuring) a DC voltage from the battery cell 42. Therefore, the input / output unit 52 functions as a voltage measuring unit.

A filter unit 55 is provided between the battery cell 42 and the DC voltage input terminal 57. That is, between the positive electrode side terminal 57a and the negative electrode side terminal 57b of the DC voltage input terminal 57, an LC filter 55a as a filter circuit, a Zener diode 55b as a protective element, and a low-pass filter 55c as a first low-pass filter are provided. It is provided. That is, the LC filter 55a, the Zener diode 55b, and the low-pass filter 55c are connected in parallel to the battery cell 42.

Further, the input / output unit 52 is connected to the battery cell 42 and has a response signal input terminal 58 for inputting a response signal (voltage fluctuation) reflecting the internal complex impedance information of the battery cell 42. Therefore, the input / output unit 52 functions as a response signal input unit.

Further, the input / output unit 52 is connected to a current modulation circuit 56 as a signal control unit, and outputs an instruction signal for instructing the current modulation circuit 56 of a sine wave signal (AC signal) to be output from the battery cell 42. It has an instruction signal output terminal 59a for output. Further, the input / output unit 52 has a feedback signal input terminal 59b. The feedback signal input terminal 59b inputs a current signal actually output (flowing) from the battery cell 42 as a feedback signal via the current modulation circuit 56. Here, the DC voltage input terminal 57, the response signal input terminal 58, the instruction signal output terminal 59a, and the feedback signal input terminal 59b function as external connection terminals.

Further, the input / output unit 52 is connected to the microcomputer unit 53, and the DC voltage (measured voltage) input by the DC voltage input terminal 57, the response signal input by the response signal input terminal 58, and the feedback signal input terminal 59b It is configured to output the input feedback signal or the like to the microcomputer unit 53. The microcomputer unit 53 calculates the complex impedance of the battery cell 42 based on these signals output from the input / output unit 52. Based on the calculated complex impedance characteristics, it is possible to determine the deterioration state of the battery cell 42 and the like. The input / output unit 52 has an AD converter inside, and is configured to convert the input analog signal into a digital signal and output it to the microcomputer unit 53.

Further, the input / output unit 52 is configured to input an instruction signal from the microcomputer unit 53, and is configured to output an instruction signal from the instruction signal output terminal 59a to the current modulation circuit 56. The input / output unit 52 has a DA converter inside, and is configured to convert a digital signal input from the microcomputer unit 53 into an analog signal and output an instruction signal to the current modulation circuit 56. Has been done. Further, the sine wave signal instructed by the instruction signal to the current modulation circuit 56 is DC biased so that the sine wave signal does not become a negative current (backflow to the battery cell 42).

The current modulation circuit 56 is a circuit that outputs a predetermined AC signal (sine wave signal) using the battery cell 42 to be monitored as a power source. Specifically, the current modulation circuit 56 has a semiconductor switch element 56a (for example, MOSFET) and a resistor 56b connected in series with the semiconductor switch element 56a. The drain terminal of the semiconductor switch element 56a is connected to the positive electrode terminal of the battery cell 42, and the source terminal of the semiconductor switch element 56a is connected in series with one end of the resistor 56b. The other end of the resistor 56b is connected to the negative electrode terminal of the battery cell 42. The semiconductor switch element 56a is configured so that the amount of energization can be adjusted between the drain terminal and the source terminal.

The positive electrode terminal and the negative electrode terminal of the battery cell 42 are connected to electrodes (positive electrode or negative electrode), respectively. Then, it is desirable that the response signal input terminal 58 is connected to the portion closest to the electrode among the connectable portions of the positive electrode terminal and the negative electrode terminal. Similarly, it is desirable that the connection point of the DC voltage input terminal 57 is the place closest to the electrode or the place next to the connection point of the response signal input terminal 58. As a result, the influence of the voltage drop due to the main current or the equalizing current can be minimized.

Further, the current modulation circuit 56 is provided with a current detection amplifier 56c as a current detection unit connected to both ends of the resistor 56b. The current detection amplifier 56c is configured to detect a signal (current signal) flowing through the resistor 56b and output the detection signal as a feedback signal to the feedback signal input terminal 59b of the input / output unit 52.

Further, the current modulation circuit 56 is provided with a feedback circuit 56d. The feedback circuit 56d is configured to input an instruction signal from the instruction signal output terminal 59a of the input / output unit 52 and to input a feedback signal from the current detection amplifier 56c. Then, the instruction signal and the feedback signal are compared, and the result is output to the gate terminal of the semiconductor switch element 56a.

The semiconductor switch element 56a applies a voltage applied between the gate and the source so as to output a sine wave signal (a predetermined AC signal) instructed by the instruction signal from the battery cell 42 based on the signal from the feedback circuit 56d. Adjust to adjust the amount of current between the drain and source. When an error occurs between the waveform indicated by the instruction signal and the waveform actually flowing through the resistor 56b, the semiconductor switch element 56a corrects the error based on the signal from the feedback circuit 56d. Adjust the amount of current so that. As a result, the sinusoidal signal flowing through the resistor 56b is stabilized.

By the way, in the battery monitoring device 50, in order to improve the calculation accuracy of the complex impedance in the battery cell 42, it is preferable to provide a bandpass filter that removes noise superimposed on the response signal. For example, it is conceivable that the response signal input terminal 58 for inputting the response signal is directly connected to the battery cell 42, and a bandpass filter is provided on the electrical wiring connecting the response signal input terminal 58 and the battery cell 42. Be done. However, providing a bandpass filter leads to an increase in size and cost of the battery monitoring device 50.

In the power supply system 10 of the present embodiment, the low-pass filter and the high-pass filter constituting the band-pass filter are configured by the low-pass filter 55c of the filter unit 55. That is, the low-pass filter constituting the band-pass filter has the same configuration as the low-pass filter 55c of the filter unit 55. Therefore, as compared with the case where the filter unit 55 has a different configuration from the low-pass filter 55c, it is possible to reduce the number of parts of the battery monitoring device 50, reduce the size, and reduce the cost.

Specifically, the battery monitoring device 50 includes a high-pass filter 70 provided between the battery cell 42 and the response signal input terminal 58. The high-pass filter 70 is connected between the low-pass filter 55c and the DC voltage input terminal 57, and is connected to the battery cell 42 via the low-pass filter 55c.

FIG. 3 shows the frequency characteristics of the low-pass filter 55c and the high-pass filter 70. In the present embodiment, the first cutoff frequency FL of the low-pass filter 55c is set higher than the second cutoff frequency FH of the high-pass filter 70, and the low-pass filter 55c and the high-pass filter 70 constitute a bandpass filter. To. Here, the cutoff frequency indicates a frequency F in which the gain P of the signals input to these filters becomes the reference gain Pk. In the present embodiment, the response signal is input via this bandpass filter. Therefore, it is possible to improve the calculation accuracy of the complex impedance as compared with the case where there is no bandpass filter.

Next, a method of calculating the complex impedance of the battery cell 42 will be described. The microcomputer unit 53 executes the complex impedance calculation process shown in FIG. 4 at predetermined cycles.

In the complex impedance calculation process, the microcomputer unit 53 first sets the measurement frequency of the complex impedance (step S101). The measurement frequency is set from the frequencies within the predetermined measurement range.

Next, the microcomputer unit 53 determines the frequency of the sine wave signal (predetermined AC signal) based on the measurement frequency, and outputs an instruction signal instructing the input / output unit 52 to output the sine wave signal. (Step S102).

When the input / output unit 52 inputs the instruction signal, it is converted into an analog signal by the DA converter and output to the current modulation circuit 56. The current modulation circuit 56 uses the battery cell 42 as a power source to output a sine wave signal based on the instruction signal. Specifically, the semiconductor switch element 56a adjusts the amount of current so that the sine wave signal instructed by the instruction signal is output from the battery cell 42 based on the signal input via the feedback circuit 56d. As a result, a sine wave signal is output from the battery cell 42.

When a sine wave signal is output from the battery cell 42, that is, when a disturbance is applied to the battery cell 42, a voltage fluctuation reflecting the internal complex impedance information of the battery cell 42 occurs between the terminals of the battery cell 42. The input / output unit 52 inputs the voltage fluctuation via the response signal input terminal 58, and outputs the response signal to the microcomputer unit 53. At that time, it is converted into a digital signal by an AD converter and output.

After executing step S102, the microcomputer unit 53 inputs a response signal from the input / output unit 52 (step S103). Further, the microcomputer unit 53 acquires a signal flowing through the resistor 56b of the current modulation circuit 56 (that is, a signal output from the battery cell 42) as a current signal (step S104). Specifically, the microcomputer unit 53 inputs the feedback signal (detection signal) output from the current detection amplifier 56c as a current signal via the input / output unit 52. Instead of the feedback signal, a value proportional to the instruction signal instructed to the current modulation circuit 56 may be used as the current signal.

Next, the microcomputer unit 53 calculates the complex impedance based on the response signal and the current signal (step S105). That is, the microcomputer unit 53 calculates all or any of the real part, the imaginary part, the absolute value, and the phase of the complex impedance based on the amplitude of the response signal, the phase difference from the current signal, and the like. The microcomputer unit 53 outputs the calculation result to the ECU 60 via the communication unit 54 (step S106). Then, the calculation process is completed.

This calculation process is repeated until complex impedances for a plurality of frequencies within the measurement range are calculated. The ECU 60 creates, for example, a complex impedance plane plot (call call plot) based on the calculation result, and grasps the characteristics of the electrodes, the electrolyte, and the like. For example, the storage state (SOC) and deterioration state (SOH) are grasped.

It is not always necessary to create the entire call call plot, and attention may be paid to a part thereof. For example, the complex impedance of a specific frequency may be measured at regular time intervals during running, and changes in SOC, SOH, battery temperature, etc. during running may be grasped based on the time change of the complex impedance of the specific frequency. .. Alternatively, the complex impedance of a specific frequency may be measured at time intervals such as every day, every lap, or every year, and the change in SOH or the like may be grasped based on the time change of the complex impedance of the specific frequency.

The battery monitoring device 50 of the first embodiment has the following effects.

In the present embodiment, among the low-pass filter and the high-pass filter constituting the band-pass filter for the response signal, the low-pass filter has the same configuration as the low-pass filter 55c of the filter unit 55 provided for measuring the DC voltage. .. Therefore, the number of parts of the battery monitoring device 50 can be reduced, the size can be reduced, and the cost can be reduced as compared with the case where the filter unit 55 has a different configuration from the low-pass filter 55c.

Further, by making the low-pass filter 55c a common configuration, the number of low-pass filters connected to the battery cell 42 is reduced, and the number of wirings and terminals for connecting the battery cell 42 and the low-pass filter 55c is reduced. be able to.

Then, in the present embodiment, the response signal is input via the bandpass filter composed of the lowpass filter 55c and the highpass filter 70. Therefore, it is possible to improve the calculation accuracy of the complex impedance as compared with the case where there is no bandpass filter.

In the present embodiment, the current modulation circuit 56 uses the battery cell 42 to be monitored as a power source to output a sine wave signal (a predetermined AC signal). Therefore, an external power source for inputting the sine wave signal to the battery cell 42 is not required, and it is possible to reduce the number of parts of the battery monitoring device 50, reduce the size, and reduce the cost.

(Second Embodiment)
Next, the battery monitoring device 50 of the second embodiment will be described with reference to FIG. 5, focusing on the differences from the battery monitoring device 50 of the first embodiment. This embodiment differs from the battery monitoring device 50 of the first embodiment in that a part of the high-pass filter 70 is provided in the ASIC unit 50a. In the following, the parts that are the same or equal to each other in each embodiment are designated by the same reference numerals, and the description thereof will be incorporated for the parts having the same reference numerals.

As shown in FIG. 5, the ASIC unit 50a of the battery monitoring device 50 is provided with a differential amplifier 151 for measuring the DC voltage between the terminals of the battery cell 42. The differential amplifier 151 is connected to the DC voltage input terminal 57, and is configured to measure and output the DC voltage. Specifically, the high-voltage side measurement terminal 151a of the differential amplifier 151 is connected to the positive-voltage side terminal 57a of the DC voltage input terminal 57 via the internal wiring in the ASIC unit 50a, and is connected to the low-voltage side of the differential amplifier 151. The measurement terminal 151b is connected to the negative side terminal 57b of the DC voltage input terminal 57 via internal wiring.

Further, the ASIC unit 50a of the battery monitoring device 50 is provided with a preamplifier 152 as an amplifier that inputs the voltage fluctuation of the battery cell 42 at the time of outputting the sine wave signal via the response signal input terminal 58. The preamplifier 152 amplifies the voltage fluctuation input via the response signal input terminal 58 and outputs it as a response signal. That is, since the amplitude of the response signal is a weak signal as compared with the voltage of the battery cell 42, the preamplifier 152 is provided in order to improve the detection accuracy of the response signal. In the second embodiment, the preamplifier 152 has one stage, but it may have multiple stages.

Specifically, the high-voltage side input terminal 152a of the preamplifier 152 is connected to the response signal input terminal 58 via internal wiring. On the other hand, the low voltage side input terminal 152b of the preamplifier 152 is connected to the connection point M1 between the negative electrode side terminal 57b of the DC voltage input terminal 57 and the low voltage side measurement terminal 151b of the differential amplifier 151 via internal wiring. , It is connected to the low pass filter 55c via the negative electrode side terminal 57b. The connection point M1 may be the same as the negative electrode side terminal 57b. Therefore, the preamplifier 152 inputs a response signal via the negative electrode side terminal 57b of the DC voltage input terminal 57 and the response signal input terminal 58.

In the present embodiment, in the above configuration, a part of the high-pass filter 70 is provided in the ASIC unit 50a. Specifically, the high-pass filter 70 has a capacitor 71 and a resistor 72, and the capacitor 71 is provided on the electrical wiring connecting the response signal input terminal 58 and the low-pass filter 55c. .. On the other hand, the resistor 72 is connected between the high-voltage side input terminal 152a and the low-voltage side input terminal 152b of the preamplifier 152 in the ASIC unit 50a. That is, in the high-pass filter 70, the capacitor 71 is provided outside the ASIC section 50a, and the resistor 72 is provided inside the ASIC section 50a.

The battery monitoring device 50 of the second embodiment has the following effects.

In the present embodiment, the low-voltage side input terminal 152b of the preamplifier 152 is connected to the low-voltage side measurement terminal 151b of the differential amplifier 151, and the preamplifier 152 is the negative voltage side terminal 57b and the response signal input terminal of the DC voltage input terminal 57. The response signal is input via 58. Therefore, only one response signal input terminal 58 for inputting the response signal is required, and the number of response signal input terminals 58 required for the ASIC unit 50a can be reduced.

In the present embodiment, of the high-pass filter 70, the capacitor 71 is provided outside the ASIC section 50a, and the resistor 72 is provided inside the ASIC section 50a. By providing the resistor 72 in the ASIC unit 50a, it is possible to reduce the number of parts of the battery monitoring device 50. On the other hand, if the capacitor 71 is provided in the ASIC section 50a, the area of the ASIC section 50a may increase depending on the capacity of the capacitor 71. By providing the capacitor 71 outside the ASIC unit 50a, it is possible to suppress the increase in size of the battery monitoring device 50.

(Third Embodiment)
Next, the battery monitoring device 50 of the third embodiment will be described with reference to FIGS. 6 and 7, focusing on the differences from the battery monitoring device 50 of the second embodiment. This embodiment differs from the battery monitoring device 50 of the second embodiment in that all of the high-pass filter 70 is provided in the ASIC unit 50a.

As shown in FIG. 6, in the present embodiment, the high-voltage side input terminal 152a of the preamplifier 152 is formed by connecting the positive voltage side terminal 57a of the DC voltage input terminal 57 and the high-voltage side measurement terminal 151a of the differential amplifier 151 via internal wiring. It is connected to the connection point M2 between them, and is connected to the low-pass filter 55c via the positive-voltage side terminal 57a. The connection point M2 may be the same as the positive electrode side terminal 57a. Therefore, the preamplifier 152 inputs a response signal via the positive electrode side terminal 57a and the negative electrode side terminal 57b of the DC voltage input terminal 57.

In the present embodiment, in the above configuration, the entire high-pass filter 70 is provided in the ASIC unit 50a. Specifically, the capacitor 71 is provided on the internal wiring that connects the connection point M2 and the high-voltage side input terminal 152a. The resistor 72 is connected between the high-voltage side input terminal 152a and the low-voltage side input terminal 152b of the preamplifier 152 on the high-voltage side input terminal 152a side of the capacitor 71.

Further, the resistor 72 is provided as a variable resistor whose resistance value is variable. In the present embodiment, the microcomputer unit 53 sets (controls) the resistance value of the resistor 72 to the resistance value according to the frequency of the sinusoidal signal in the complex impedance calculation process. Specifically, as shown in FIG. 7, after setting the measurement frequency of the complex impedance in step S101, the resistance value of the resistor 72 is set based on the set measurement frequency (step S110).

The battery monitoring device 50 of the third embodiment has the following effects.

In the present embodiment, the high-voltage side input terminal 152a of the preamplifier 152 is connected to the high-voltage side measurement terminal 151a of the differential amplifier 151, and the low-voltage side input terminal 152b of the preamplifier 152 is connected to the low-voltage side measurement terminal 151b of the differential amplifier 151. It is connected. Then, the preamplifier 152 inputs a response signal via the positive electrode side terminal 57a and the negative electrode side terminal 57b of the DC voltage input terminal 57. Therefore, the response signal input terminal 58 for inputting the response signal is not required, and the number of response signal input terminals 58 required for the ASIC unit 50a can be reduced.

In the present embodiment, the capacitor 71 and the resistor 72 constituting the high-pass filter 70 are provided in the ASIC unit 50a. By providing the capacitor 71 and the resistor 72 in the ASIC unit 50a, it is possible to reduce the number of parts of the battery monitoring device 50.

Then, in the present embodiment, the resistor 72 is provided as a variable resistor, and the resistance value of the resistor 72 is set to a resistance value corresponding to the frequency of the sinusoidal signal. Therefore, the second cutoff frequency FH of the high-pass filter 70 can be controlled to a frequency corresponding to the frequency of the sine wave signal, and the calculation accuracy of the complex impedance can be improved.

(Fourth Embodiment)
Next, the battery monitoring device 50 of the fourth embodiment will be described with reference to FIGS. 8 to 10 focusing on the differences from the battery monitoring device 50 of the second embodiment. This embodiment differs from the battery monitoring device 50 of the second embodiment in that so-called two-phase lock-in detection is performed.

As shown in FIG. 5, the ASIC unit 50a of the battery monitoring device 50 is provided with a signal switching unit 153 that switches between the DC voltage output from the differential amplifier 151 and the response signal output from the preamplifier 152. .. An AD converter 154 is connected to the signal switching unit 153, and the switched signal (analog signal) is converted into a digital signal and output.

The AD converter 154 is a delta-sigma type AD converter, and has a delta-sigma modulator 154a that functions as a low-bit AD converter such as 1 bit, and a digital filter 154b as a second low-pass filter. The digital filter 154b is a digital low-pass filter, and removes the quantization noise generated by the delta-sigma modulator 154a.

The AD converter 154 converts the input analog signal into a digital signal by repeatedly executing a conversion process, and is configured to be able to switch the number of conversions, which is the number of such processes. In the AD converter 154, the larger the number of conversions, the lower the third cutoff frequency FD (see FIG. 9) of the digital filter 154b.

Specifically, the AD converter 154 is configured to input a DC voltage to the signal processing unit 155 as the calculation unit in the fourth embodiment. In this case, as shown in FIG. 9, the AD converter 154 increases the number of conversions and sets the third cutoff frequency FD of the digital filter 154b to be lower than the second cutoff frequency FH of the high-pass filter 70. .. Further, the AD converter 154 is connected to the first multiplier 156 and the second multiplier 157, and is configured to input a response signal, respectively. In this case, the AD converter 154 reduces the number of conversions.

An oscillation circuit 158, which will be described later, is connected to the first multiplier 156 so that a first reference signal can be input. The first multiplier 156 multiplies the first reference signal by the response signal to calculate a value proportional to the real part of the response signal, and passes through the low-pass filter 159 to calculate a value proportional to the real part of the response signal. Is output to the signal processing unit 155. In FIG. 8, the real part of the response signal is shown as Re | Vr |.

The second multiplier 157 is connected to the oscillation circuit 158 via the phase shift circuit 160, and a second reference signal is input to the second multiplier 157. The second reference signal is a signal obtained by advancing the phase of the first reference signal by 90 degrees (π / 2). The phase shift circuit 160 advances the phase of the sine wave signal (first reference signal) input from the oscillation circuit 158 and outputs it as a second reference signal.

The second multiplier 157 multiplies the second reference signal by the response signal to calculate a value proportional to the imaginary part of the response signal, and passes through the low-pass filter 161 to calculate a value proportional to the imaginary part of the response signal. Is output to the signal processing unit 155. In FIG. 8, the imaginary part of the response signal is indicated by Im | Vr |.

The oscillation circuit 158 is a circuit that outputs a set sine wave signal, and functions as a waveform indicator. As described above, the oscillator circuit 158 outputs a sine wave signal as the first reference signal to the first multiplier 156 and the phase shift circuit 160. Further, the oscillation circuit 158 is connected to the instruction signal output terminal 59a via the DA converter 162, and outputs a sine wave signal as an instruction signal.

The feedback signal input terminal 59b is connected to the signal processing unit 155 via the AD converter 163. The signal processing unit 155 inputs a feedback signal (detection signal) from the feedback signal input terminal 59b via the AD converter 163.

The signal processing unit 155 inputs a value proportional to the real part of the response signal and a value proportional to the imaginary part of the response signal, and calculates the real part and the imaginary part of the complex impedance based on these values. At that time, the signal processing unit 155 calculates the real part and the imaginary part of the complex impedance using the input DC voltage and the feedback signal, taking into account the amplitude of the signal actually flowing and the phase shift from the reference signal ( to correct. Therefore, it can be said that the signal processing unit 155 calculates the complex impedance based on the response signal and the DC voltage.

Further, the signal processing unit 155 calculates the absolute value and the phase of the complex impedance. Explaining in detail, since the real part and the imaginary part of the response signal can be known by the two-phase lock-in detection, if the phase of the response signal is θv, it can be shown as | Vr | e ^ jθv in the polar coordinate display of the complex plane. it can. Similarly, the current can be expressed as shown in | I | e ^ jθi. From this, assuming that the polar coordinate display of the complex impedance is | Z | e ^ jθz, it can be expressed from V = ZI as in the mathematical formula (1). Further, "j" is an imaginary unit satisfying j ^ 2 = -1.

よって、複素インピーダンスの絶対値は｜Ｚ｜＝｜Ｖｒ｜／｜Ｉ｜、位相はθｖ−θｉから求めることができる。そして、シグナルプロセッシング部１５５は、通信部５４を介して、ＥＣＵ６０に算出結果を出力する。なお、図８では、複素インピーダンスの絶対値を｜Ｚ｜と示し、その位相をａｒｇ（Ｚ）と示す。

Therefore, the absolute value of the complex impedance can be obtained from | Z | = | Vr | / | I |, and the phase can be obtained from θv−θi. Then, the signal processing unit 155 outputs the calculation result to the ECU 60 via the communication unit 54. In FIG. 8, the absolute value of the complex impedance is indicated by | Z |, and the phase thereof is indicated by arg (Z).

Next, the complex impedance calculation process according to the fourth embodiment will be described with reference to FIG. The complex impedance calculation process is executed by the battery monitoring device 50 at predetermined intervals.

In the complex impedance calculation process, the oscillation circuit 158 first sets the measurement frequency of the complex impedance (step S201). The measurement frequency is set from the frequencies within the predetermined measurement range. In the fourth embodiment, the measurement frequency is determined by, for example, the signal processing unit 155.

Next, the number of conversions of the AD converter 154 is set (step S202). In the fourth embodiment, the number of conversions is determined by, for example, the signal processing unit 155. The signal processing unit 155 sets the number of conversions when smoothing the response signal output from the preamplifier 152 to be smaller than the number of conversions when smoothing the DC voltage output from the differential amplifier 151. In the AD converter 154, the third cutoff frequency FD of the digital filter 154b fluctuates depending on the number of conversions. Therefore, the process of step S202 can be said to be the process of setting the third cutoff frequency FD.

Next, the resistance value of the resistor 72 is set (step S203). The resistance value is determined by, for example, the signal processing unit 155.

Next, the signal switching unit 153 switches so that the response signal from the preamplifier 152 is output (step S204). The switching instruction is given by, for example, the signal processing unit 155.

Next, the oscillation circuit 158 determines the frequency of the sine wave signal (predetermined AC signal) based on the measurement frequency, and from the instruction signal output terminal 59a to the current modulation circuit 56 via the DA converter 162. An instruction signal instructing the output of the sine wave signal is output (step S205). The output instruction of the instruction signal is given by, for example, the signal processing unit 155. When converted to an analog signal by the DA converter 162, an appropriate offset value (DC bias) is set in consideration of the voltage of the battery cell 42, and the signal is converted. The offset value (DC bias) is set by, for example, the signal processing unit 155. It is desirable that the offset value (DC bias) is set based on the DC voltage of the battery cell 42. The DC voltage of the battery cell 42 may be measured by the differential amplifier 151.

The current modulation circuit 56 outputs a sine wave signal using the battery cell 42 as a power source based on the instruction signal (step S206). As a result, a sine wave signal is output from the battery cell 42.

When a sine wave signal is output from the battery cell 42, a voltage fluctuation that reflects the internal complex impedance information of the battery cell 42 occurs between the terminals of the battery cell 42. The preamplifier 152 inputs the voltage fluctuation thereof via the response signal input terminal 58 and outputs it as a response signal (step S207).

The preamplifier 152 amplifies a weak voltage fluctuation in which the DC component is cut, and outputs it as a response signal. At that time, the AD converter 154 converts the response signal input via the signal switching unit 153 into a digital signal and outputs it. It is desirable to adjust how much the voltage fluctuation is amplified based on the DC voltage of the battery cell 42.

The first multiplier 156 uses the sine wave signal input from the oscillation circuit 158 as the first reference signal, multiplies the response signal input from the AD converter 154, and calculates a value proportional to the real part of the response signal. (Step S208). Similarly, the second multiplier 157 multiplies the second reference signal input from the phase shift circuit 160 with the response signal to calculate a value proportional to the imaginary part of the response signal.

These values are input to the signal processing unit 155 via the low-pass filter 159 and the low-pass filter 161. When passing through the low-pass filter 159 and the low-pass filter 161, signals other than the DC component (DC component) are attenuated and removed.

The signal processing unit 155 inputs a feedback signal (detection signal) from the feedback signal input terminal 59b (step S209). When the feedback signal is input to the signal processing unit 155, it is converted into a digital signal by the AD converter 163.

The signal processing unit 155 is of the real part, the imaginary part, the absolute value, and the phase of the complex impedance based on the feedback signal and the signal (proportional value of the real part and the imaginary part) input from the low-pass filters 159 and 161. Calculate all or either (step S210). The feedback signal is used to correct the amplitude or phase shift between the current actually flowing from the battery cell 42 (that is, the feedback signal) and the value proportional to the reference signal.

After that, the signal processing unit 155 outputs the calculation result to the ECU 60 via the communication unit 54 (step S211). Then, the calculation process is completed.

This calculation process is repeated until complex impedances for a plurality of frequencies within the measurement range are calculated. The ECU 60 creates a complex impedance plane plot (call call plot) based on the calculation result, and grasps the characteristics of the electrodes, the electrolyte, and the like. For example, the storage state (SOC) and deterioration state (SOH) are grasped.

It is not always necessary to create the entire call call plot, and attention may be paid to a part thereof. For example, the complex impedance of a specific frequency may be measured at regular time intervals during running, and changes in SOC, SOH, battery temperature, etc. during running may be grasped based on the time change of the complex impedance of the specific frequency. .. Alternatively, the complex impedance of a specific frequency may be measured at time intervals such as every day, every lap, or every year, and the change in SOH or the like may be grasped based on the time change of the complex impedance of the specific frequency.

The battery monitoring device 50 of the fourth embodiment has the following effects.

In the present embodiment, the signal processing unit 155 calculates a value proportional to the actual part of the response signal based on the value obtained by multiplying the response signal input from the response signal input terminal 58 and the first reference signal. Further, the signal processing unit 155 uses a signal obtained by shifting the phase of the sine wave signal as the second reference signal, and sets the imaginary part of the response signal based on the value obtained by multiplying the response signal and the second reference signal. Calculate a proportional value. Then, the complex impedance is calculated based on these values.

As described above, in the present embodiment, by performing so-called lock-in detection, only the frequency component having the same frequency as the frequency of the sinusoidal signal indicated by the oscillation circuit 158 can be extracted from the response signal. Therefore, it becomes resistant to white noise and pink noise, and the complex impedance can be calculated with high accuracy. In particular, when it is used in a vehicle, noise increases, so that the complex impedance can be preferably calculated. Further, since it becomes resistant to noise, the current (sine wave signal) output from the battery cell 42 can be reduced. Therefore, it is possible to suppress the power consumption and the temperature rise of the battery cell 42 and the semiconductor switch element 56a.

Further, the signal processing unit 155 inputs a feedback signal (detection signal) that detects the current actually flowing from the battery cell 42 by the current modulation circuit 56, and corrects the amplitude and phase deviation from the value proportional to the reference signal. ing. Thereby, the calculation accuracy of the complex impedance can be improved.

Further, since the amplitude and phase shift are corrected by the DC voltage and the feedback signal of the battery cell 42, even if an error occurs when the instruction signal is converted into an analog signal, the error can be suppressed. Therefore, it is not necessary to provide a filter circuit or the like between the current modulation circuit 56 and the DA converter 162, and the size can be reduced.

In the present embodiment, the AD converter 154 is provided between the differential amplifier 151 and the signal processing unit 155, and between the preamplifier 152 and the signal processing unit 155. The AD converter 154 is configured so that the number of conversions can be switched. In this way, the AD converter 154 is configured so that the number of conversions can be switched, so that the AD converter smoothes the DC voltage input from the differential amplifier 151 and the response signal input from the preamplifier 152. Can be configured in common with an AD converter that smoothes the above. Therefore, the number of parts of the battery monitoring device 50 can be reduced, the size can be reduced, and the cost can be reduced as compared with the case where these AD converters have different configurations.

Specifically, the AD converter 154 sets the third cutoff frequency FD to be lower than the second cutoff frequency FH of the high-pass filter 70 by increasing the number of conversions when smoothing the DC voltage. To do. As a result, the AC component of the DC voltage can be suitably removed by the digital filter 154b while using the low-pass filter 55c as the anti-aliasing filter. Then, by using the low-pass filter 55c as an anti-aliasing filter, the first cutoff frequency FL of the low-pass filter 55c can be set higher than the second cutoff frequency FH. That is, the low-pass filter 55c can form an anti-aliasing filter for DC voltage and a band-pass filter for response signals, reducing the number of parts of the battery monitoring device 50, reducing the size, and reducing the cost. Can be realized.

Further, the AD converter 154 reduces the number of conversions when smoothing the response signal. As a result, it is possible to prevent the AD converter 154 from removing the internal complex impedance information included in the response signal.

(Other embodiments)
In the above embodiment, the battery monitoring device 50 is provided for each battery cell 42, but the battery monitoring device 50 may be provided for each of the plurality of battery cells 42 (for example, for each battery module 41 and for each assembled battery 40). .. At that time, a part of the functions of the battery monitoring device 50 may be shared.

Further, for example, as shown in FIG. 11, a stabilized power supply unit 301, a communication unit 54, a differential amplifier 151, a preamplifier 152, a signal switching unit 153, an AD converter 154, 163, a signal processing unit 155, and a first multiplication. The device 156, the second multiplier 157, the low-pass filters 159, 161, the oscillation circuit 158, the phase shift circuit 160, the DA converter 162, the feedback circuit 56d, and the current detection amplifier 56c may be shared.

In this case, various signals such as DC voltage, response signal, and instruction signal may be configured so that the signals can be switched by a multiplexing device such as multiplexers 302 to 304.

-In the above embodiment, the battery monitoring device 50 may perform an equalization process for equalizing the storage state and voltage of each battery cell 42. The equalization process is a process of discharging a part of the battery cells 42 having a higher electricity storage state than the other battery cells 42 so that the electricity storage states of the battery cells 42 are aligned. As a result, it is possible to align the storage states of the battery cells 42 and prevent a part of the battery cells 42 from being overcharged. Then, when the battery monitoring device 50 performs the equalization process, the battery cell 42 may be discharged by using the current modulation circuit 56.

More specifically, in the first to third embodiments, the microcomputer unit 53 receives a discharge instruction from the ECU 60 or the like based on the storage state of each battery cell 42, or the storage state or voltage of the battery cell 42. Is equal to or greater than a predetermined value, an instruction signal is output to the current modulation circuit 56, and a periodic function such as a sine wave signal or a square wave or a DC signal is output from the battery cell 42. Then, the microcomputer unit 53 continues to output the signal until the discharge instruction is completed or the storage state or voltage of the battery cell 42 becomes smaller than a predetermined value. As a result, the equalization process is carried out. Similarly in the fourth embodiment, the signal processing unit 155 may carry out the equalization process.

Then, for the equalization process, when discharging from the battery cell 42, a sine wave signal may be output to calculate the complex impedance. As a result, power consumption can be suppressed. The current output for the equalization process is generally a weak current in order to suppress power consumption and to reduce the size of the device. Therefore, it is preferable to perform the equalization process in the battery monitoring device 50 capable of accurately calculating the complex impedance by lock-in detection even with a weak current as in the fourth embodiment.

-In the above embodiment, the filter unit 55 does not have to be composed of only elements. For example, the wiring, the connector contact portion, the pattern wiring of the printed circuit board, or the solid pattern may be used, or these configurations and the elements may be mixed.

-In the above embodiment, a filter circuit may be provided between the current modulation circuit 56 and the input / output unit 52 (or DA converter 162). As a result, it is possible to suppress an error in converting the instruction signal into an analog signal.

In the above embodiment, the differential amplifier 151, the preamplifier 152, the signal switching unit 153, the AD converter 154, 163, the signal processing unit 155, the first multiplier 156, the second multiplier 157, the low-pass filter 159, 161 and the oscillation The circuit 158, the phase shift circuit 160, the DA converter 162, the feedback circuit 56d, and a part or all of the current detection amplifier 56c may be realized by software.

-In the third embodiment and the fourth embodiment, the determination of the resistance value in the resistor 72 may be executed by the resistor 72. Specifically, the resistor 72 stores correspondence information in which the measurement frequency and the resistance value are associated with each other, and when the set measurement frequency is input to the resistor 72, the resistor 72 itself becomes The resistance value may be set.

-In the above embodiment, the feedback circuit 56d may not be provided. Further, the current detection amplifier 56c does not have to detect the current flowing through the resistor 56b. Further, the microcomputer unit 53 and the signal processing unit 155 do not have to input a feedback signal.

-In the fourth embodiment, the signal switching unit 153 may not be provided.

-In the fourth embodiment, the feedback signal may also be switched by the signal switching unit 153. As a result, the AD converters 154 and 163 can be shared.

-In the fourth embodiment, the conversion method of the AD converter is not limited to the delta-sigma method, and may be a sequential comparison method, a pipeline method, or a flash method.

-In the fourth embodiment, the cutoff frequency of the digital filter is switched by switching the number of conversions of the AD converter 154, but the present invention is not limited to this. For example, as shown in FIG. 12, first and second AD converters 154c and 154d may be provided, which include digital filters having different cutoff frequencies. The signal processing unit 155 can switch the cutoff frequency of the digital filter by switching the first and second AD converters 154c and 154d to be used.

-The battery monitoring device 50 of the above embodiment may be adopted as a vehicle for HEVs, EVs, PHVs, auxiliary batteries, electric airplanes, electric motorcycles, and electric ships.

-In the above embodiment, the battery cells 42 may be connected in parallel.

-In the above embodiment, the state may be monitored for each battery module 41. At this time, when the communication unit 54 is provided for each battery module 41, the communication from each communication unit 54 to the ECU 60 may be isolated communication having a different potential reference. For example, isolation communication may be performed using an isolation transformer or a capacitor.

-In the above embodiment, the current signal output from the battery cell 42 is not limited to the sine wave signal. For example, if it is an AC signal, it may be a signal such as a rectangular wave or a triangular wave.

-In the above embodiment, the ECU 60 may be composed of a plurality of ECUs. For example, a plurality of ECUs may be provided for each function, or a plurality of ECUs may be provided for each control target. For example, it may be divided into a battery ECU and an inverter control ECU.

-In the above embodiment, when the lock-in detection is performed, the sine wave signal instructed by the oscillation circuit 158 is used as a reference signal (first reference signal), but the detection signal (feedback signal) may be used as a reference signal. Further, when performing two-phase lock-in detection, the phase of the detection signal (feedback signal) may be shifted to be the second reference signal.

In the above embodiment, the battery cell 42 (battery module 41, assembled battery 40) is used as a power source for peripheral circuits when outputting a sine wave signal based on an instruction (when outputting a response signal). May be good. On the contrary, the battery cell 42 (battery module 41, assembled battery 40) is configured so as not to be used as a power source for peripheral circuits when outputting a sine wave signal based on an instruction (when outputting a response signal). You may.

42 ... Battery cell, 50 ... Battery monitoring device, 52 ... Input / output unit, 53 ... Microcomputer unit, 55c ... Low-pass filter, 56 ... Current modulation circuit, 70 ... High-pass filter.

Claims (9)

In the battery monitoring device (50) that monitors the state of the storage battery (42) including the electrolyte and a plurality of electrodes.
A voltage measuring unit (52) for measuring the voltage of the storage battery and
A low-pass filter (55c) provided between the storage battery and the voltage measuring unit and having a first cutoff frequency,
A signal control unit (56) that outputs a predetermined AC signal, and
A response signal input unit (52) connected to the storage battery and inputting a response signal of the storage battery to the AC signal,
A high-pass filter (70) provided between the storage battery and the response signal input unit and having a second cutoff frequency lower than the first cutoff frequency.
A calculation unit (53) for calculating the complex impedance of the storage battery based on the response signal is provided.
A battery monitoring device in which the high-pass filter is connected between the low-pass filter and the voltage measuring unit, and is connected to the storage battery via the low-pass filter. The voltage measuring unit and the response signal input unit are provided in an integrated circuit (50a) having a plurality of external connection terminals (57, 58, 59a, 59b), and electricity extending from the low-pass filter. Wiring is connected to the plurality of external connection terminals,
The voltage measuring unit has a high-voltage side measuring terminal (151a) and a low-voltage side measuring terminal (151b) connected to the external connection terminal via internal wiring in the integrated circuit.
The response signal input unit has a high voltage side input terminal (152a) and a low voltage side input terminal (152b) connected to the external connection terminal via the internal wiring.
The battery monitoring device according to claim 1, wherein the low-voltage side measurement terminal and the low-voltage side input terminal are connected to each other and are connected to the low-pass filter via a common external connection terminal. The high-voltage side measurement terminal and the high-voltage side input terminal are connected to the low-pass filter via the external connection terminals that are different from each other.
The high-pass filter includes a capacitor (71) and a resistor (72), and the capacitor is provided on the electrical wiring connecting the external connection terminal to which the high-voltage side input terminal is connected and the low-pass filter. The battery monitoring device according to claim 2, wherein the resistor is connected between the high-voltage side input terminal and the low-voltage side input terminal in the integrated circuit. The high-voltage side input terminal is connected to a connection point (M2) between the external connection terminal to which the high-voltage side measurement terminal is connected and the high-voltage side measurement terminal, and is connected via the common external connection terminal. It is connected to the low-pass filter and
The high-pass filter includes a capacitor (71) and a resistor (72), and the capacitor is provided on the internal wiring connecting the connection point and the high voltage side input terminal, and the resistor is provided. The battery monitoring device according to claim 2, which is connected between the high voltage side input terminal and the low voltage side input terminal on the high voltage side input terminal side of the capacitor. The resistor is a variable resistor having a variable resistance value.
The battery monitoring device according to claim 3 or 4, wherein the calculation unit controls the resistance value of the resistor to a resistance value corresponding to the frequency of the AC signal. The low-pass filter is a first low-pass filter (55c).
Any one of claims 1 to 5 including a second low-pass filter (154b) provided between the voltage measuring unit and the arithmetic unit and having a third cutoff frequency lower than the first cutoff frequency. The battery monitoring device described in the section. The calculation unit calculates the complex impedance based on the response signal and the measurement voltage measured by the voltage measurement unit.
The second low-pass filter is provided between the voltage measuring unit and the calculation unit, and is provided between the response signal input unit and the calculation unit.
The second low-pass filter can set the third cutoff frequency.
The battery monitoring device according to claim 6, wherein the calculation unit sets the third cutoff frequency lower when smoothing the measured voltage than when smoothing the response signal. The battery monitoring device according to any one of claims 1 to 7, wherein the signal control unit outputs a predetermined AC signal using the storage battery to be monitored as a power source. It has a waveform indicating unit (158) for instructing the waveform of the AC signal to the signal control unit.
The calculation unit uses the AC signal instructed by the waveform indicating unit as the first reference signal, and based on a value obtained by multiplying the response signal input from the response signal input unit and the first reference signal. The real part of the response signal is calculated
The phase-shifted signal of the AC signal indicated by the waveform indicator is used as the second reference signal, and is based on the value obtained by multiplying the response signal input from the response signal input unit and the second reference signal. The battery monitoring device according to any one of claims 1 to 8, wherein the imaginary part of the response signal is calculated.

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