JP5920154B2 - Voltage monitoring device - Google Patents

Description

  The present invention relates to a flying capacitor type voltage monitoring device that uses a capacitor to monitor the voltage of an assembled battery configured by connecting a plurality of battery cells in series.

  Conventionally, a device using a capacitor (flying device) as a voltage monitoring device for monitoring the voltage of an assembled battery formed by connecting a large number of battery cells in series, such as an in-vehicle high-voltage battery mounted on a hybrid vehicle or an electric vehicle. A capacitor-type voltage monitoring device) is known (for example, see Patent Document 1).

  In this type of voltage monitoring device, each input-side sampling switch connected to both terminals of the battery cell is turned on, the cell voltage of each battery cell is sequentially applied to the capacitor, and the stored voltage of the capacitor is used as the cell voltage of the battery cell. Is detected.

JP 2006-292516 A

  By the way, in the voltage monitoring device of the flying capacitor type, the polarity of the voltage (cell voltage) applied to the capacitor may be reversed when the input side sampling switch is switched on / off. Immediately after the polarity of the voltage (cell voltage) applied to the capacitor is reversed due to an increase in the voltage, there is a problem that the voltage detection accuracy is lower than when the polarity is not reversed.

  An object of the present invention is to provide a flying capacitor type voltage monitoring apparatus capable of improving the accuracy of voltage detection when the polarity of a voltage applied to a capacitor is reversed.

  The present invention is directed to a voltage monitoring device that monitors the voltage of a battery pack (1) configured by connecting a plurality of battery cells (V1 to V14) in series.

In order to achieve the above object, according to the first aspect of the present invention, a voltage detection circuit (24) having a plurality of detection terminals (B1 to B3) for detecting a voltage between the detection terminals, and at least one capacitor ( A capacitor circuit (22) having C1, C2), an input side switch circuit (21) for sequentially applying the cell voltages of a plurality of battery cells to the capacitor, and the storage voltage of the capacitor as a detection terminal of the voltage detection circuit An output side switch circuit (23) to be applied, a voltage correction means (25b) for correcting the voltage detected by the voltage detection circuit, and at the time of inversion indicating the charging characteristics when the polarity of the voltage applied to at least the capacitor is inverted Storage means (25a) in which the charging characteristics are stored, and the voltage correction means stores the memory when the polarity of the voltage applied to the capacitor by the input side switch circuit is inverted. Based on the stored inverted during charging characteristics, is characterized by correcting the voltage detected by the voltage detection circuit.

  According to this, since the detection value of the voltage detection circuit is corrected based on the charging characteristics when the polarity of the voltage applied to the capacitor is reversed, the polarity of the voltage applied to the capacitor is reversed. Can be accurately detected.

  In addition, the code | symbol in the parenthesis of each means described in this column and the claim shows an example of a correspondence relationship with the specific means described in the embodiment described later.

1 is a schematic configuration diagram of a monitoring system including a voltage monitoring device according to a first embodiment. It is a schematic block diagram of the monitoring system containing the voltage monitoring apparatus which concerns on 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
First, the first embodiment will be described. In the present embodiment, the voltage monitoring device 2 of the present invention is applied to a monitoring system that monitors a vehicle-mounted high-voltage battery that constitutes the assembled battery 1.

  As shown in the schematic configuration diagram of FIG. 1, the monitoring system of the present embodiment includes an assembled battery 1 and a flying capacitor type voltage monitoring device 2 as main elements.

  The assembled battery 1 supplies electric power to an electric motor for traveling (traveling motor) via an inverter, for example. The assembled battery 1 according to the present embodiment is a series connection body configured by connecting n (14 in the present embodiment) battery cells V1 to V14 that are the minimum units of charge and discharge in series. In addition, as battery cells V1-V14, the lithium ion battery which can be charged / discharged, a lead acid battery, etc. are used.

  The assembled battery 1 configured in this way is connected to the voltage monitoring device 2 via a plurality of detection lines connected to electrode terminals (positive and negative terminals) T1 to T15 of the battery cells V1 to V14. .

  The electrode terminals T1 to T15 of each battery cell V1 to V14 are electrode terminals T2 to T14 between the battery cells, the positive terminal T15 of the battery cell (high voltage side cell) V14 on the highest voltage side, and the electrode terminal T15 on the lowest voltage side. It is comprised by the negative electrode terminal T1 of the battery cell (low voltage side cell) V1. When the number of battery cells constituting the assembled battery 1 is n, the number of electrode terminals of each battery cell is n + 1.

  Next, the voltage monitoring apparatus 2 according to the present embodiment will be described. The voltage monitoring device 2 of the present embodiment employs a double flying capacitor method, and detects the voltages of the battery cells V1 to V14 in the assembled battery 1 using a pair of capacitors C1 and C2 connected in series. It has a configuration.

  The voltage monitoring device 2 of this embodiment includes an input side switch circuit 21, a capacitor circuit 22, an output side switch circuit 23, a voltage detection circuit 24, and a microcomputer 25 (hereinafter abbreviated as a microcomputer 25).

  The input side switch circuit 21 connects the electrode terminals T1 to T15 of the battery cells V1 to V14 to the independent ends A1 and A2 of the pair of capacitors C1 and C2 in the capacitor circuit 22 and the connection end A3 between the pair of capacitors C1 and C2. Are switching circuits sequentially connected to each other. By operating this input side switch circuit 21, it is possible to sequentially apply (charge) the voltage of at least one battery cell V1 to V14 to the capacitors C1 and C2.

  The input side switch circuit 21 of the present embodiment includes a plurality of input side switches SWi (i: 1 to 14) connected to the independent ends A1 and A2 of the capacitors C1 and C2 and the connection end A3 between the capacitors C1 and C2. ). The input side switch SWi is a switch that connects the independent terminals A1 and A2 and the connection terminal A3 of the capacitors C1 and C2 to the electrode terminals T1 to T15 of the battery cells V1 to V14.

  In the present embodiment, among the input side switches SWi, when the electrode terminals T1 to T15 of the battery cells V1 to V14 are counted in order from the lowest potential, the [4m−1] th (m: positive The input side switches SW3, SW7, SW11, SW15 connected to the electrode terminals T3, T7, T11, T15 of the integer) are connected to the independent end A1 of the first capacitor C1.

  In addition, among the input side switches SWi, the input side switches SW1, SW5, SW9, and SW13 connected to the [4m-3] th electrode terminals T1, T5, T9, and T13 are independent ends of the second capacitor C2. Connected to A2.

  Furthermore, among the input side switches SWi, the input side switches SW2, SW4, SW6, SW8, SW10, SW12 connected to the [2m] th electrode terminals T2, T4, T6, T8, T10, T12, T14, SW14 is connected to the connection end A3 of each of the capacitors C1 and C2.

  Each of the input side switches SW1 to SW15 is a semiconductor switch, and on / off switching is controlled according to a command signal from the microcomputer 25 described later.

  The capacitor circuit 22 is composed of a pair of capacitors C1 and C2 connected in series. The pair of capacitors C1 and C2 has the same capacitance. In the capacitor circuit 22, a contact point connecting the pair of capacitors C1 and C2 constitutes a connection end A3, and a side opposite to the connection end A3 between the capacitors C1 and C2 constitutes independent ends A1 and A2.

  The output side switch circuit 23 is a switching circuit that connects the independent ends A1 and A2 and the connection end A3 of the pair of capacitors C1 and C2 to first to third detection terminals B1 to B3 provided in the voltage detection circuit 24. is there.

  By operating the output side switch circuit 23, it is possible to apply the stored voltage (charge amount) charged to at least one of the capacitors C1 and C2 to the detection terminals B1 to B3 of the voltage detection circuit 24. It has become.

  The output side switch circuit 23 of the present embodiment includes a first output side switch SW16 connected to the independent end A1 of the first capacitor C1, a second output side switch SW17 connected to the independent end A2 of the second capacitor C2, and A third output-side switch SW18 is connected to the connection end A3 between the capacitors C1 and C2.

  The first output side switch SW16 is a switch that connects the independent end A1 of the first capacitor C1 to the first detection terminal B1 of the voltage detection circuit 24. The second output side switch SW17 is a switch that connects the independent end A2 of the second capacitor C2 to the second detection terminal B2 of the voltage detection circuit 24. The third output-side switch SW18 is a switch that connects the connection end A3 between the capacitors C1 and C2 to the third detection terminal B3 of the voltage detection circuit 24.

  These output-side switches SW16 to SW18 are semiconductor switches, and are switched on and off in accordance with a command signal from a microcomputer 25 described later.

  The voltage detection circuit 24 includes a first detection terminal B1, a second detection terminal B2, and a third detection terminal B3, and is voltage detection means that detects a voltage between the detection terminals. The voltage detection circuit 24 of the present embodiment is configured to detect the voltage between the first differential voltage detection unit 241 that detects the voltage between the first and third detection terminals B1 and B3, and the voltage between the second and third detection terminals B2 and B3. And a second differential voltage detector 242 for detection.

  In the voltage detection circuit 24 of the present embodiment, the first and second differential voltage detection units 241 and 242 are provided corresponding to the capacitors C1 and C2, respectively, and the stored voltage stored in the corresponding capacitor. Are individually detected.

  The first differential voltage detector 241 includes a differential amplifier circuit that amplifies and outputs the stored voltage stored in the first capacitor C1 with a predetermined amplification factor. The second differential voltage detector 242 It is composed of a differential amplifier circuit that amplifies and outputs the stored voltage stored in the two capacitor C2 with a predetermined amplification factor.

  Each of the differential voltage detectors 241 and 242 includes an AD converter (not shown), converts a voltage signal (analog signal) input via each of the detection terminals B1 to B3 into a digital signal, and a microcomputer. It is configured to output to the 25 side.

  The microcomputer 25 is a microcomputer including a CPU, a memory 25a constituting a storage unit, and the like, and is a control unit that executes various processes according to a program stored in the memory 25a.

  The microcomputer 25 controls the operation (on / off of each switch) of the input side switch circuit 21 and the output side switch circuit 23, and each battery constituting the assembled battery 1 based on a signal output from the voltage detection circuit 24. A measurement process for measuring the voltages of the cells V1 to V14, a voltage diagnosis process for diagnosing the voltage state of each of the battery cells V1 to V14, and the like are executed.

  Specifically, the microcomputer 25 of the present embodiment turns on each input side switch of the input side switch circuit 21 according to the order stored in the memory 25a, so that the voltage of each battery cell V1 to V14 is set to the capacitor C1, It is comprised so that it may apply to C2.

  The microcomputer 25 turns on the output side switches SW16 to SW18 of the output side switch circuit 23 in the order stored in the memory, so that the independent ends A1 and A2 and the connection end A3 of the capacitors C1 and C2 are connected to the detection terminals. It connects to B1-B3, and it is comprised so that the electrical storage voltage stored in each capacitor C1-C3 may be applied to detection terminal B1-B3 of the voltage detection circuit 24. FIG.

  Here, when the input side switches of the input side switch circuit 21 are turned on in a predetermined order, the polarity of the voltage applied to the capacitors C1 and C2 may be reversed. Such polarity reversal occurs, for example, when the voltages of the battery cells V3 and V4 are detected after the voltages of the battery cells V1 and V2 are detected.

  Specifically, when charging the voltages of the battery cells V1 and V2 to the first and second capacitors C1 and C2, the input side switches SW1 to SW3 of the input side switch circuit 21 are simultaneously turned on. Thereby, the voltage of the battery cell V1 is charged in the second capacitor C2, and the voltage of the battery cell V2 is charged in the first capacitor C1. At this time, the independent end A1 of the first capacitor C1 has a positive polarity (+), and the independent end A2 of the second capacitor C2 has a negative polarity (−).

  On the other hand, when charging the voltages of the battery cells V3 and V4 to the first and second capacitors C1 and C2, the input side switches SW3 to SW5 of the input side switch circuit 21 are simultaneously turned on. Thereby, the voltage of the battery cell V3 is charged in the first capacitor C1, and the voltage of the battery cell V4 is charged in the second capacitor C2. At this time, the independent end A1 of the first capacitor C1 has a negative polarity (−), and the independent end A2 of the second capacitor C2 has a positive polarity (+).

  When the polarities of the capacitors C1 and C2 are reversed in this way, immediately after the polarity of the voltage (cell voltage) applied to the capacitors C1 and C2 is reversed due to an increase in charging time of the capacitors C1 and C2 before and after the polarity reversal. There is a problem in that the accuracy of voltage detection is reduced as compared with the case where the polarity is not reversed.

  Therefore, in the microcomputer 25 of the present embodiment, the charging characteristics at the time of inversion, which are the charging characteristics of the capacitors C1, C2 when the polarities of the capacitors C1, C2 are inverted, and the capacitors when the polarities of the capacitors C1, C2 are not inverted The non-reverse charging characteristics, which are the charging characteristics of C1 and C2, are stored in the memory 25a in advance, and a voltage correction process is performed to correct the voltage detected by the voltage detection circuit 24 based on the charging characteristics stored in the memory 25a. To do.

  Here, the inversion charging characteristic and the non-inversion charging characteristic are set in advance based on the results of the product inspection process, simulation, and the like, and are stored in the memory 25a as different charging characteristics. Each charging characteristic is stored in the memory 25a as a correction value set according to the capacitances of the capacitors C1 and C2, resistance components in the circuit, and the like. In the present embodiment, the configuration for executing the voltage correction processing in the microcomputer 25 constitutes the voltage correction means 25b.

  Next, the operation of the voltage monitoring device 2 of this embodiment will be described. In the present embodiment, a specific operation example in the case where voltage monitoring of representative four battery cells V1 to V4 is performed using each of the pair of capacitors C1 and C2 will be described. In this operation example, the battery cells V1, V2, V3, and V4 are monitored in order from the battery cell on the low voltage side.

  First, the microcomputer 25 switches on the first and second input side switches SW1 to SW3 of the input side switch circuit 21.

  When the input side switches SW1 and SW2 are turned on, the second capacitor C2 is connected to the electrode terminals T1 and T2 of the battery cell V1, and the voltage of the battery cell V1 is applied to the second capacitor C2. When the input side switches SW2 and SW3 are turned on, the first capacitor C1 is connected to the electrode terminals T2 and T3 of the battery cell V2, and the voltage of the battery cell V2 is applied to the first capacitor C1. At this time, the independent end A1 of the first capacitor C1 has a positive polarity (+), and the independent end A2 of the second capacitor C2 has a negative polarity (−).

  Thereafter, the microcomputer 25 switches off the input side switches SW1 to SW3 of the input side switch circuit 21 and switches on the output side switches SW16 to SW18 of the output side switch circuit 23.

  When the first and third output switches SW16 and SW18 are turned on, the first capacitor C1 is connected to the first differential voltage detector 241 via the first and third detection terminals B1 and B3 of the voltage detection circuit 24. The Then, the first differential voltage detector 241 amplifies the voltage of the first capacitor C1 to which the voltage of the battery cell V2 is applied, and outputs the amplified voltage to the microcomputer 25 side.

  When the second and third output switches SW17 and SW18 are turned on, the second capacitor C2 is connected to the second differential voltage detection unit 242 via the second and third detection terminals B2 and B3 of the voltage detection circuit 24. Connected. Then, the second differential voltage detection unit 242 amplifies the voltage of the second capacitor C2 to which the voltage of the battery cell V1 is applied, and outputs the amplified voltage to the microcomputer 25 side.

  In the microcomputer 25, the voltage of the battery cells V1 and V2 is detected by correcting the signal output from the voltage detection circuit 24 with the non-inversion charging characteristic stored in the memory 25a. Based on the detected voltage, the battery The presence or absence of abnormalities such as overcharge / discharge or deterioration of the cells V1, V2 is diagnosed.

  Subsequently, the microcomputer 25 switches on the first and second input side switches SW <b> 3 to SW <b> 5 of the input side switch circuit 21.

  When the input side switches SW3 and SW4 are turned on, the first capacitor C1 is connected to the electrode terminals T3 and T4 of the battery cell V3, and the voltage of the battery cell V3 is applied to the first capacitor C1. When the input side switches SW4 and SW5 are turned on, the second capacitor C2 is connected to the electrode terminals T4 and T5 of the battery cell V4, and the voltage of the battery cell V4 is applied to the second capacitor C2. At this time, the independent end A2 of the second capacitor C2 has a positive polarity (+), and the independent end A1 of the first capacitor C1 has a negative polarity (−). That is, the polarity of the voltage applied to each of the capacitors C1 and C2 is inverted.

  Thereafter, the microcomputer 25 switches off the input side switches SW3 to SW5 of the input side switch circuit 21 and switches on the output side switches SW16 to SW18 of the output side switch circuit 23.

  When the first and third output switches SW16 and SW18 are turned on, the first capacitor C1 is connected to the first differential voltage detector 241 via the first and third detection terminals B1 and B3 of the voltage detection circuit 24. The Then, the first differential voltage detector 241 amplifies the voltage of the first capacitor C1 to which the voltage of the battery cell V3 is applied, and outputs the amplified voltage to the microcomputer 25 side.

  When the second and third output switches SW17 and SW18 are turned on, the second capacitor C2 is connected to the second differential voltage detection unit 242 via the second and third detection terminals B2 and B3 of the voltage detection circuit 24. Connected. Then, the second differential voltage detection unit 242 amplifies the voltage of the second capacitor C2 to which the voltage of the battery cell V4 is applied, and outputs the amplified voltage to the microcomputer 25 side.

  In the microcomputer 25, the voltage of the battery cells V3 and V4 is detected by correcting the signal output from the voltage detection circuit 24 with the inversion charging characteristic stored in the memory 25a, and the battery cell is detected based on the detected voltage. Diagnose the presence or absence of abnormalities such as overcharge / discharge and deterioration of V3 and V4.

  According to the voltage monitoring device 2 according to the present embodiment described above, the detection value of the voltage detection circuit 24 is corrected based on the charging characteristics when the polarity of the voltage applied to each of the capacitors C1 and C2 is inverted. Therefore, the cell voltage when the polarity of the voltage applied to the capacitors C1 and C2 is inverted can be detected with high accuracy.

(Second Embodiment)
Next, a second embodiment will be described. This embodiment is different from the first embodiment in that the cell voltage of each of the battery cells V1 to V14 is detected in consideration of the change in the ambient temperature of the voltage monitoring device 2. In the present embodiment, description of the same or equivalent parts as in the first embodiment will be omitted or simplified.

  Here, the capacitors C1 and C2 constituting the capacitor circuit 22 tend to change in capacity or the like according to the ambient temperature, and the storage voltage at the time of voltage application changes due to the change in the capacity or the like. For this reason, in the present embodiment, the microcomputer 25 corrects the detection result of the voltage detection circuit 24 in accordance with the change in the ambient temperature of the voltage monitoring device 2.

  Specifically, the voltage monitoring device 2 of the present embodiment includes a temperature detection circuit 26 as temperature detection means for detecting the ambient temperature of the voltage monitoring device 2 as shown in the schematic configuration diagram of FIG.

  The temperature detection circuit 26 of the present embodiment detects an ambient temperature by using a VF characteristic (forward voltage characteristic: voltage drop according to temperature rise) of a diode having temperature dependence, and includes a plurality of Zener diodes. A pair of temperature detection units 261 connected in series, a multiplexer 262 for selectively switching the pair of temperature detection units 261, and the like. Note that the temperature detection circuit 26 of the present embodiment has a redundant circuit configuration including a plurality of temperature detection units 261, thereby improving the fault tolerance.

  The microcomputer 25 further corrects a correction value obtained by correcting the signal output from the voltage detection circuit 24 with each charging characteristic stored in the memory 25a at the time of executing the voltage correction process based on the temperature detected by the temperature detection circuit 26. To do.

  Specifically, the microcomputer 25 calculates a voltage change amount ΔV considering the capacitance change amount of the capacitors C 1 and C 2 based on the ambient temperature detected by the temperature detection circuit 26, and is output from the voltage detection circuit 24. A correction value obtained by correcting the signal with each charging characteristic stored in the memory 25a is corrected with the voltage change amount ΔV.

  Other configurations and operations are the same as those in the first embodiment. Therefore, according to the configuration of the present embodiment, as in the first embodiment, the cell voltage when the polarity of the voltage applied to the capacitors C1 and C2 is inverted can be accurately detected.

  Furthermore, in this embodiment, since the correction value corrected by each charging characteristic stored in the memory 25a is corrected based on the ambient temperature detected by the temperature detection circuit 26, the cell voltage can be detected more accurately. Is possible.

(Other embodiments)
The present invention is not limited to the embodiment described above, and can be appropriately changed within the scope described in the claims. For example, various changes can be made as follows.

  (1) In each of the above-described embodiments, the signal output from the voltage detection circuit 24 by the microcomputer 25 both when the polarity of the capacitors C1 and C2 is inverted and when the polarity of the capacitors C1 and C2 is not inverted. Although the example which correct | amends by the charge characteristic memorize | stored in the memory 25a was demonstrated, it is not limited to this. For example, the signal output from the voltage detection circuit 24 may be corrected with the charging characteristics stored in the memory 25a only when the polarities of the capacitors C1 and C2 are inverted.

  (2) In the above-described second embodiment, the example in which the temperature detection unit is configured by the temperature detection circuit 26 using a Zener diode has been described. However, other types of temperature sensors may be employed as the temperature detection unit. Good. Further, the temperature detection circuit 26 may be configured by a single temperature detection unit 261.

  (3) In each of the above-described embodiments, the example in which the capacitor circuit 22 is configured by the pair of capacitors C1 and C2 connected in series has been described. However, the present invention is not limited to this. The capacitor circuit 22 may be configured by a single capacitor, or the capacitor circuit 22 may be configured by a circuit in which a plurality of three or more capacitors are connected in series.

  (4) In each of the above-described embodiments, the example in which the voltage monitoring device 2 is applied to the assembled battery 1 configured by connecting 14 battery cells in series has been described as a specific example. The target is not limited to the number of battery cells constituting the assembled battery 1.

  (5) In each of the above-described embodiments, the example in which the voltage monitoring device 2 is applied to the in-vehicle high voltage battery has been described. However, the present invention is not limited to the in-vehicle high voltage battery, and may be applied to other batteries.

  (6) In each of the above-described embodiments, elements constituting the embodiment are not necessarily indispensable unless explicitly stated as essential and clearly considered essential in principle. Needless to say. Further, in each of the above embodiments, when numerical values such as the number, numerical value, quantity, range, etc. of the constituent elements of the embodiment are mentioned, it is clearly limited to a specific number when clearly indicated as essential and in principle. It is not limited to the specific number except where it is done.

DESCRIPTION OF SYMBOLS 1 Battery assembly 21 Input side switch circuit 22 Capacitor circuit 23 Output side switch circuit 24 Voltage detection circuit 25a Memory (memory | storage means)
25b Voltage correction means V1-V14 Battery cell C1, C2 Capacitor

Claims (4)

A voltage monitoring device that monitors the voltage of a battery pack (1) configured by connecting a plurality of battery cells (V1 to V14) in series,
A voltage detection circuit (24) having a plurality of detection terminals (B1 to B3) and detecting a voltage between the detection terminals;
A capacitor circuit (22) having at least one capacitor (C1, C2);
An input side switch circuit (21) for sequentially applying cell voltages of the plurality of battery cells to the capacitor;
An output side switch circuit (23) for applying a storage voltage of the capacitor to a detection terminal of the voltage detection circuit;
Voltage correction means (25b) for correcting the voltage detected by the voltage detection circuit;
Storage means (25a) in which charging characteristics at the time of reversal indicating charging characteristics when the polarity of the voltage applied to the capacitor is reversed are stored;
When the polarity of the voltage applied to the capacitor is inverted by the input side switch circuit, the voltage correction unit detects the voltage detection circuit based on the inversion charging characteristics stored in the storage unit. A voltage monitoring device that corrects a voltage. The storage means stores characteristics that are different from the charging characteristics at the time of inversion, and non-inversion charging characteristics that indicate the charging characteristics when the polarity of the capacitor is not inverted,
When the polarity of the voltage applied to the capacitor by the input-side switch circuit is not reversed, the voltage correction unit is detected by the voltage detection circuit based on the non-inversion charging characteristic stored in the storage unit. The voltage monitoring apparatus according to claim 1, wherein the voltage is corrected. Temperature detection means (26) for detecting the ambient temperature;
The voltage correction means calculates a voltage change amount in consideration of the capacitance change amount of the capacitor based on the ambient temperature detected by the temperature detection means, and the voltage detected by the voltage detection circuit based on the voltage change amount The voltage monitoring device according to claim 1 or 2, wherein   4. The voltage monitoring device according to claim 1, wherein the capacitor circuit is configured by connecting a plurality of the capacitors in series. 5.

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