JP2012049087A - Secondary battery device and vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery device and a vehicle which reduce a load on a communication network to achieve stable power supply.SOLUTION: The secondary battery device comprises: a battery pack 10 including a plurality of secondary battery cells BT; a voltage measuring unit 22 for measuring inter-terminal voltages of the secondary battery cells BT; and an encoding circuit 50 which receives a plurality of pieces of measurement data measured by the voltage measuring unit 22, converts a measurement value of the first piece of measurement data among the plurality of pieces of measurement data into a binary value, calculates a difference value between a measurement value of a subsequent piece of measurement data and an immediately preceding measurement value, and converts the difference value into a preset code word.

Description

  Embodiments described herein relate generally to a secondary battery device and a vehicle.

  In recent years, power generation equipment using renewable energy that does not emit greenhouse gases during power generation has been installed, and the reduction of carbon in power supply systems has been studied. In power generation using renewable energy, it is difficult to control the amount of power supply, and it is difficult to realize stable power supply.

  In the future, if the number of power generation facilities that use renewable energy expands, the short-term balance between power supply and demand will be disrupted, and the frequency of power will deviate from the appropriate value. The quality may deteriorate.

  Therefore, in addition to installing secondary batteries that store surplus power in power generation facilities that use renewable energy in the distribution system, it is also possible to store and distribute electricity using power storage facilities installed in consumers, etc. It is being considered. For this purpose, a mechanism for integrating the energy management systems (EMSs) of the respective layers in an integrated manner is necessary.

Toward the construction of next-generation power transmission and distribution networks for the realization of a low-carbon society: Report on the Next Generation Power Transmission and Distribution Network Study Group (URL: http://www.meti.go.jp/report/data/g100426aj.html ) Announcement of “International Standardization Roadmap for Smart Grids”-Toward International Standardization for Next Generation Energy Systems (URL: http://www.meti.go.jp/press/20100128003/20100128003.html)

  Conventionally, in a secondary battery device including a plurality of secondary battery cells, the inter-terminal voltage and temperature of the secondary battery cell are monitored to control the operation of the secondary battery device. In addition, the host system is notified of the state of the secondary battery device, and is notified of data such as voltages between terminals of a plurality of secondary battery cells as necessary.

  In the future, it is expected that the number of secondary battery cells mounted on the secondary battery device will increase as the voltage required by consumers, vehicles, etc. increases. As a result, when it becomes necessary to perform two-way communication individually from each customer and each vehicle, a large amount of data is transmitted to and received from the EMS. Furthermore, a large amount of time-series data is transmitted / received to / from the EMS in order to predict failure of the secondary battery cell. In such a situation, a large amount of data on information (secondary terminal voltage, temperature, etc.) related to the secondary battery cell is transmitted and received, which increases the load on the communication network and may make it difficult to stably supply power. .

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a secondary battery device and a vehicle that perform stable power supply by reducing the load on a communication network.

  A secondary battery device according to an embodiment includes an assembled battery including a plurality of secondary battery cells, a voltage measurement unit that measures a voltage between terminals of the secondary battery cell, and a plurality of measurement data measured by the voltage measurement unit. The first measurement value of the plurality of measurement data is converted into a binary value, a difference value between the measurement value of the subsequent measurement data and the previous measurement value is calculated, and the difference value is set in advance as a codeword. And an encoding circuit configured to convert the data into

It is a figure for explaining an example of 1 composition of vehicles concerning an embodiment. It is a block diagram for demonstrating the example of 1 structure of the secondary battery apparatus which concerns on embodiment. It is a figure for demonstrating the 1st example of the data compression method of the secondary battery apparatus which concerns on embodiment. It is a figure for demonstrating an example after the code | symbol corresponding to the difference value shown in FIG. 4 is a flowchart for explaining an example of a data compression method shown in FIG. 3. 4 is a flowchart for explaining another example of the data compression method shown in FIG. 3. 4 is a flowchart for explaining another example of the data compression method shown in FIG. 3. 6 is a flowchart for explaining a second example of the data compression method of the secondary battery device according to the embodiment. 6 is a flowchart for explaining a third example of the data compression method of the secondary battery device according to the embodiment.

  Hereinafter, the secondary battery device and the vehicle according to the first embodiment will be described with reference to the drawings.

  FIG. 1 schematically shows a configuration example of a vehicle according to an embodiment of the present invention. The vehicle according to the present embodiment is, for example, an electric vehicle or a hybrid vehicle, and has a secondary battery device mounted thereon.

  The vehicle includes an assembled battery module 400, a battery management device 300 that controls the operation of the assembled battery module 400, an operation control unit 500, a motor 600 to which power is supplied from the assembled battery module 400, a host system 70, and a chassis. 1000 and drive wheels WR and WL.

  The assembled battery module 400 includes the assembled battery 10 (shown in FIG. 2) including a plurality of secondary battery cells BT. The positive terminal and the negative terminal of the assembled battery module 400 are connected to the operation control unit 500.

  The battery management device 300 includes a voltage value between terminals of the plurality of secondary battery cells BT from the assembled battery module 400 (value of a voltage difference between the positive terminal and the negative terminal), a current value flowing through the assembled battery 10, and the assembled battery 10 A temperature value in the vicinity is supplied, and charging and discharging of the assembled battery 1 are managed.

  The operation control unit 500 includes an inverter, converts the voltage supplied from the assembled battery module 400, and receives an operation command to perform output current / voltage level control and phase control. The output of the operation control unit 500 is supplied to the motor 600 as drive power. The rotation of the motor 600 is transmitted to the drive wheels WR and WL via, for example, a differential gear unit.

  The host system 70 is configured to receive measurement data and the like of a plurality of secondary battery cells BT from the battery management device 300 and control the operation of the battery management device 300.

  FIG. 2 schematically shows a configuration example of the secondary battery device according to the present embodiment. The secondary battery device shown in FIG. 2 includes an assembled battery 10 including a plurality of secondary battery cells BT, a measurement circuit 20, a cell balance circuit 30, a control circuit 40, and an encoding circuit 50. . The measurement circuit 20 includes a voltage measurement unit 22, a current measurement unit 24, and a temperature measurement unit 26. The secondary battery cell BT is, for example, a nickel metal hydride battery or a lithium ion battery. When the secondary battery device is mounted on a vehicle, the assembled battery 10, the measurement circuit 20, and the cell balance circuit 30 are mounted on the assembled battery module 400, and the control circuit 40 and the encoding circuit 50 are included in the battery management device 300. Installed.

  The voltage measurement part 22 acquires the voltage of the positive electrode terminal and the voltage of a negative electrode terminal of each secondary battery cell BT, and measures the voltage between terminals. The voltage measurement unit 22 outputs the measured value of the terminal voltage to the control circuit 40.

  The current measuring unit 24 is installed in the current path of the assembled battery 10 and measures the charge / discharge current of the assembled battery 10. The current measuring unit 24 outputs the measured charge / discharge current value to the control circuit 40.

  The temperature measurement unit 26 includes a temperature sensor (not shown) that is disposed in the vicinity of the plurality of secondary battery cells BT and detects the temperature of the plurality of secondary battery cells BT. The temperature measurement unit 26 outputs the temperature value detected by the temperature sensor to the control circuit 40.

  The cell balance circuit 30 individually charges or discharges the plurality of secondary battery cells BT so that the voltages (or charge amounts) between the terminals of the plurality of secondary battery cells BT are equal. Variations exist in each secondary battery cell BT. For example, even when a plurality of fully charged secondary battery cells BT are connected in series, due to variations in the internal resistance of each secondary battery cell BT, the voltage between terminals of each secondary battery cell BT (or A difference occurs in the charge amount. Thus, when the voltage (or charge amount) between the terminals of each secondary battery cell BT is different, it causes overcharge and overdischarge, and the discharge capacity that can be used as a whole decreases. The cell balance circuit 30 is configured to individually charge or discharge the secondary battery cells BT so that there is no difference in the amount of charge due to such variations in the plurality of secondary battery cells BT.

  The control circuit 40 controls the operations of the measurement circuit 20 and the cell balance circuit 30. The control circuit 40 receives the terminal-to-terminal voltage, charge / discharge current, and temperature measurement data from the voltage measurement unit 22, the current measurement unit 24, and the temperature measurement unit 26, and records them in a memory (not shown). And output to the encoding circuit 50. Further, the control circuit 40 calculates the cell balance time of each secondary battery cell BT from the inter-terminal voltage received from the measurement circuit 20 and controls the operation of the cell balance circuit 30.

  The encoding circuit 50 encodes and outputs the measurement data received from the control circuit 40. The encoding circuit 50 is configured to calculate a difference value between the received measurement data and the immediately preceding data, convert the difference value into a preset code word, and output the result. The encoding circuit 50 may be configured to run-length encode the difference value, or may be configured to perform Huffman encoding.

  FIG. 3 shows an example in which the measurement data of the inter-terminal voltage is encoded in the encoding circuit 50. In FIG. 3, for the sake of explanation, the first to tenth values are shown in the order in which the measurement data is received.

  FIG. 5 shows a flowchart for explaining an operation example of compressing measurement data in the encoding circuit 50. When receiving the measurement data of the 10 inter-terminal voltages serially, the encoding circuit 50 converts the first inter-terminal voltage value into a binary value (step STA1). In the case illustrated in FIG. 3, the initial voltage value between terminals of 2.560 V (2560 mV) is converted to a binary value of 1010 — 0000 — 0000.

  Next, the encoding circuit 50 calculates a difference value between the second and subsequent terminal voltage values from the immediately preceding terminal voltage value (step STA2). In the case shown in FIG. 3, for example, the difference value of 1 mV is calculated by subtracting the first inter-terminal voltage value of 2.560 V from the second inter-terminal voltage value of 2.561 V. The encoding circuit 50 similarly calculates a difference value for the third to tenth terminal voltages. Subsequently, the encoding circuit 50 converts the calculated difference value into a preset code word (step STA3).

  FIG. 4 shows an example of a code word corresponding to the difference value. In FIG. 4, when the difference value is 0 mV, the code word is 0, when the difference value is 1 mV, the code word is 01, when the difference value is −1 mV, the code word is 001, and when the difference value is 2 mV. The code word is 0001, and the code word is 00001 when the difference value is −2 mV.

  When the measurement data is encoded by the encoding circuit 50 as described above, the total number of bits of the compressed data after encoding is 35 bits. For example, when each data is converted into a binary value, it becomes 12-bit data, and the total number of bits becomes 120 bits. Therefore, by encoding the measurement data as described above, the data output to the host system 70 can be compressed to about 29%.

  The host system 70 includes a composite circuit 60 that receives the compressed data output from the encoding circuit 50.

  The composite circuit 60 first converts the first binary value from the received compressed data to obtain measurement data of the first inter-terminal voltage value. Subsequently, the composite circuit 60 composites the difference value from the bit string following the first binary value based on the difference value set in advance corresponding to the code word, and uses the first terminal voltage value. The second to tenth terminal voltage values are sequentially combined.

  In this way, the encoding circuit 50 reduces the load on the communication network by losslessly compressing and encoding the measurement data so that it can be combined by the combining circuit 60 and reducing the amount of transmission data.

  Furthermore, in the secondary battery device according to the present embodiment, the plurality of secondary battery cells BT are charged or discharged by the cell balance circuit 30 so that there is no difference in the inter-terminal voltage value. Therefore, measurement data can be effectively compressed by encoding using the code word corresponding to a difference value.

  Hereinafter, another example of the operation in which the encoding circuit 50 encodes the measurement data will be described.

    FIG. 6 shows a flowchart for explaining another example of the operation for compressing the measurement data in the encoding circuit 50. The encoding circuit 50 first arranges the measurement data in descending or ascending order (step STB1), and then converts the first inter-terminal voltage value of the measurement data arranged in descending or ascending order into a binary value (step STB2). Next, the encoding circuit 50 calculates a difference value between the second and subsequent terminal voltage values from the immediately preceding terminal voltage value (step STB3). Subsequently, the encoding circuit 50 converts the calculated difference value into a preset code word (step STB4), similarly to step STA3.

  When the measurement data is first sorted in descending order, the difference value is always zero or a negative number. Therefore, for example, the code word when the difference value is 0 mV is set to 0, the code word when the difference value is −1 mV is set to 01, and the code word when the difference value is −2 mV is set to 001. Measurement data can be compressed.

  Further, when the measurement data is first sorted in ascending order, the difference value is always zero or a positive number. Therefore, for example, the code word when the difference value is 0 mV is set to 0, the code word when the difference value is 1 mV is set to 01, and the code word when the difference value is 2 mV is set to 001. Measurement data can be compressed.

  FIG. 7 shows a flowchart for explaining another operation example of compressing measurement data in the encoding circuit 50. The encoding circuit 50 converts the first terminal voltage value of the measurement data into a binary value (step STC1). Next, the encoding circuit 50 calculates a difference value between the second and subsequent terminal voltage values from the immediately preceding terminal voltage value (step STC2). Subsequently, the encoding circuit 50 determines whether or not the calculated difference value is greater than or equal to a threshold value (step STC3).

  If the calculated difference value is greater than or equal to the threshold value, the encoding circuit 50 converts the difference value into a binary value without encoding (step STC5). If the calculated difference value is less than the threshold value, the encoding circuit 50 converts the calculated difference value into a preset codeword in the same manner as in step STA3 (step STC4).

  At this time, when the difference value is converted into a code word and the code length after encoding becomes longer than the code length after the difference value is converted into a binary value, the encoding circuit 50 encodes the difference value. Without converting to binary value. Thus, when the threshold value is set, the measurement data can be effectively compressed even when the difference value becomes large.

  When the measurement data is not encoded, the encoding circuit 50 inserts a marker bit indicating that the measurement data is not encoded into the header and outputs the header. By inserting such marker bits, the composite circuit 60 can composite compressed data.

  As described above, according to the secondary battery device and the vehicle according to the present embodiment, it is possible to provide the secondary battery device and the vehicle that reduce the load of the communication network and perform stable power supply.

  Next, a secondary battery device according to a second embodiment will be described with reference to the drawings. In the following description, the same components as those in the secondary battery device according to the above-described first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In the present embodiment, the operation in which the encoding circuit 50 encodes the difference value is different from that in the first embodiment. For example, when the difference value of the measurement data is large, if encoding is performed by setting a code word corresponding to each difference value, the code length may be significantly increased and the compression rate may be deteriorated. Therefore, in the present embodiment, when the measurement data is encoded, the compressed data is configured by a data bit length portion and a data portion, and entropy encoding is performed only for the data bit length portion.

  First, the encoding circuit 50 receives the measurement data of the ten inter-terminal voltages serially, and converts the first inter-terminal voltage value into a binary value (step STA1). Next, the encoding circuit 50 calculates a difference value between the second and subsequent terminal voltage values and the immediately preceding terminal voltage value (step STA2). Subsequently, the encoding circuit 50 converts the calculated difference value into a preset code word (step STA3).

  FIG. 8 is a diagram for explaining an example of the data compression method of the secondary battery device according to this embodiment. In FIG. 8, the calculated difference values are classified into groups of 0 to 8 for each data bit length when converted into binary values. The encoding circuit 50 sets the data bit length portion as a code word corresponding to each of the groups 0 to 8. Further, the encoding circuit 50 converts the calculated difference value into a binary value and sets it as a data portion of the compressed data. For example, when the difference value is 30 mV, the data bit length portion of the compressed data is 110 and the data portion is 11110. The encoding circuit 50 outputs the compressed data composed of the data bit length part and the data part to the composite circuit 60 of the host system 70.

  The composite circuit 60 first converts the first binary value from the received compressed data to obtain measurement data of the first inter-terminal voltage value. Subsequently, the composite circuit 60 composites the data bit length of the difference value from the bit string following the first binary value based on the data bit length set in advance corresponding to the code word, and further combines the composite data bits. Combines the difference value from the binary value of the long bit string. As described above, the composite circuit 60 composites the difference value from the bit string following the first binary value, and sequentially composites the second to tenth terminal voltage values using the first terminal voltage value.

  In this way, the encoding circuit 50 reduces the load on the communication network by losslessly compressing and encoding the measurement data so that it can be combined by the combining circuit 60 and reducing the amount of transmission data. That is, according to the secondary battery device and the vehicle according to the present embodiment, it is possible to provide the secondary battery device and the vehicle that reduce the load on the communication network and perform stable power supply.

  Furthermore, in the secondary battery device and the vehicle according to the present embodiment, the compression rate can be improved more than in the case according to the above-described first embodiment when measurement data having a certain difference value is obtained to some extent.

  Next, a secondary battery device according to a third embodiment will be described with reference to the drawings. The secondary battery device according to the present embodiment is different from the above-described first embodiment in that the encoding circuit 50 encodes measurement data. In the following description, the same reference numerals are assigned to the same configurations as those of the secondary battery device according to the first embodiment described above, and the description thereof is omitted.

  FIG. 9 is a diagram for explaining an example of the data compression method of the secondary battery device according to the present embodiment.

First, the encoding circuit 50 receives the measurement data of the 10 terminal voltages serially,
An average value of the values of the 10 terminal voltages is calculated (step STD1). Next, the encoding circuit 50 calculates the absolute value (difference absolute value) of the difference between the calculated difference value and each inter-terminal voltage (step STD2).

  The encoding circuit 50 sorts the difference absolute values in ascending order with the calculated average value as the head (step STD3). At this time, the absolute difference values may be rearranged in descending order. Subsequently, the encoding circuit 50 calculates the difference between the second absolute difference value and the previous absolute difference value, and similarly calculates the difference for the third to tenth absolute difference values (step STD4). . The encoding circuit 50 converts the calculated difference value into a preset code word (step STD5). The encoding circuit 50 converts the average value and the first absolute difference value into a binary value, and outputs compressed data including the binary value and the code word.

  The composite circuit 60 first converts the first binary value and the second binary value from the received compressed data to obtain an average value and a first difference absolute value of the ten pieces of measurement data. Subsequently, the compounding circuit 60 combines the difference value of the absolute difference value from the bit string following the second binary value based on the difference value of the absolute difference value set in advance corresponding to the code word. The second to tenth absolute difference values are sequentially combined using the average difference value. The host system 70 can monitor the variation of the measurement data from the average value and the absolute difference value of the measurement data.

  In this way, the encoding circuit 50 reduces the load on the communication network by losslessly compressing and encoding the measurement data so that it can be combined by the combining circuit 60 and reducing the amount of transmission data. That is, according to the secondary battery device and the vehicle according to the present embodiment, it is possible to provide the secondary battery device and the vehicle that reduce the load on the communication network and perform stable power supply.

  In the above-described first to third embodiments, the example in which the measurement data of the inter-terminal voltage value is encoded has been described. However, the temperature value and the current value can be encoded in the same manner. When the encoding circuit 50 encodes a plurality of types of data of the voltage value between terminals, the temperature value, and the current value, a composite bit is inserted by inserting a marker bit indicating the type of data into the header of the compressed data. At 60, a plurality of types of data can be combined.

  In addition, when a plurality of pieces of data having different measurement times are encoded, the encoding circuit 50 may be configured to insert a time stamp bit indicating the measurement time into the compressed data.

In the first to third embodiments described above, the host system includes the decryption circuit 60. However, the host system is configured to transmit the received compressed data to the host system without decrypting. May be. The composite circuit 60 manages a plurality of secondary battery devices. While several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. Not intended. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  BT ... secondary battery cell, 10 ... assembled battery, 20 ... measurement circuit, 22 ... voltage measurement unit, 24 ... current measurement unit, 26 ... temperature measurement unit, 30 ... cell balance circuit, 40 ... control circuit, 50 ... encoding Circuit, 60... Composite circuit, 70.

Claims (6)

An assembled battery including a plurality of secondary battery cells;
A voltage measuring unit for measuring a voltage between terminals of the secondary battery cell;
Receives a plurality of measurement data measured by the voltage measurement unit, converts the first measurement value of the plurality of measurement data into a binary value, and calculates a difference value between the measurement value of the subsequent measurement data and the previous measurement value And a coding circuit configured to convert the difference value into a preset code word.   The secondary battery device according to claim 1, wherein the encoding circuit is configured not to be converted into a code word.   The encoding circuit is configured to insert a marker bit indicating that the difference value is converted into a binary value and not converted into a code word when the calculated difference value is equal to or greater than a threshold value. Secondary battery device. An assembled battery including a plurality of secondary battery cells;
A voltage measuring unit for measuring a voltage between terminals of the secondary battery cell;
Receives a plurality of measurement data measured by the voltage measurement unit, converts the first measurement value of the plurality of measurement data into a binary value, and calculates a difference value between the measurement value of the subsequent measurement data and the previous measurement value The difference value is converted into a binary value, the data bit length of the binary value is converted into a preset code word, and data including the binary value and the code word is output. A secondary battery device. An assembled battery including a plurality of secondary battery cells;
A voltage measuring unit for measuring a voltage between terminals of the secondary battery cell;
Receives a plurality of measurement data measured by the voltage measurement unit, calculates an average value of the measurement values of the plurality of measurement data, and calculates an absolute difference between the average value and the measurement values of the plurality of measurement data The difference absolute values are rearranged in ascending order, the average value and the first difference absolute value are converted into binary values, a difference value between the subsequent difference absolute value and the immediately preceding difference absolute value is calculated, and the difference value A rechargeable battery device comprising: an encoding circuit configured to convert a code word into a preset code word.   A vehicle comprising the secondary battery device according to any one of claims 1 to 5.

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