Voltage detection device and battery management system

Abstract

To provide a voltage detection device and a battery management system capable of reducing the processing load on the voltage detection device compared to conventional methods.SOLUTION: A voltage detection device detects the inter-electrode voltages of multiple battery cells in a battery pack in chronological order as cell voltages, and wirelessly transmits the cell voltages, to which a device time measured by a timing unit has been added, to an external device as voltage data with the device time attached. The voltage detection device is equipped with a time adjustment unit that performs a time adjustment process on the device time on the timing unit on the basis of a reference time wirelessly received from an external device at the time of startup.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a voltage detection device and a battery management system. [Background technology]

[0002] The following Patent Document 1 discloses a clock adjustment circuit that suppresses jitter generation in a communication terminal and continues communication even when the adjustment width of the synchronization clock of a gateway device becomes large. This clock adjustment circuit includes an acquisition means for acquiring information about the external clock of an external device, a detection means for detecting a required delay time required for phase synchronization between the clock of the device and the external clock based on the information, and a delay means for delaying the clock of the device by the required delay time multiple times so that each delay is equal to or less than a predetermined length, thereby suppressing jitter generation in the communication terminal and continuing communication between the gateway device and the communication terminal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-026994 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the background art, whether or not to execute delay processing by a delay means is determined during normal communication between a gateway device and a communication terminal. In other words, in the background art, the communication terminal sequentially monitors the necessity of delay processing at a predetermined timing during operation of a communication system consisting of a gateway device and a communication terminal.

[0005] If such a communication system is applied to a voltage detection device that detects inter-electrode voltages of multiple battery cells as cell voltages in a time series manner and sequentially transmits the cell voltages wirelessly to a battery management device, the battery management device will sequentially monitor the need for delay processing at a predetermined timing during normal processing of detecting and wirelessly transmitting the cell voltages. Such monitoring of the need for delay processing during normal processing imposes a large burden on the voltage detection device.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a voltage detection device and a battery management system that can reduce the processing load on the voltage detection device compared to conventional methods. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the present invention employs a solution relating to a voltage detection device, which detects the inter-electrode voltages of multiple battery cells in a battery pack in chronological order as cell voltages, and wirelessly transmits the cell voltages, to which the device time measured by a timing unit is added, to the outside as device-time-attached voltage data, and which is equipped with a time adjustment unit that performs a time adjustment process on the device time on the timing unit based on a reference time wirelessly received from the outside at the time of startup. Effect of the Invention

[0008] According to the present invention, it is possible to provide a voltage detection device and a battery management system that can reduce the processing load on the voltage detection device as compared to the conventional art. [Brief description of the drawings]

[0009] [Figure 1] 1 is a block diagram showing a system configuration of a battery management system according to an embodiment of the present invention; [Diagram 2] 4 is a flowchart showing the operation of a battery management system according to an embodiment of the present invention. [Diagram 3] FIG. 4 is a communication sequence diagram showing the operation of a battery management system according to an embodiment of the present invention. [Figure 4] 11 is a table showing process contents of a stage process in one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The battery management system A of this embodiment is installed in electric vehicles, hybrid vehicles, and other electric vehicles that convert DC power supplied from a battery pack into AC power using an inverter or the like, and generate driving power by supplying this AC power to a driving motor.

[0011] 1, this battery management system A includes a plurality of CVS (Cell Voltage Sensors) 1A-1X and a single BMU (Battery Management Unit) 2. The battery management system A manages the assembled battery (subject to management) of the electric vehicle as a whole by wirelessly communicating between these CVSs 1A-1X and the BMU 2.

[0012] The multiple CVS1A-1X are provided corresponding to the battery modules that make up the assembled battery to be managed. That is, the number of CVS1A-1X corresponds to the number of battery modules. The multiple CVS1A-1X are voltage detection devices that detect inter-electrode voltages, i.e., cell voltages, of the multiple battery cells that make up each battery module in a time-series manner at a predetermined time interval.

[0013] As shown in the figure, each of the CVSs 1A to 1X includes a communication unit 1a, a timer unit 1b (RTC: Real Time Clock), and a time adjustment unit 1c. The communication unit 1a wirelessly communicates with the BMU 2. That is, the communication units 1a wirelessly transmit the cell voltages (voltage detection data) detected by the CVSs 1A to 1X from moment to moment to the BMU 2 in sequence for each piece of voltage detection data.

[0014] The clock unit 1b measures the time (CVS time) specific to each of the CVS 1A to 1X as the device time. That is, each of the clock units 1b is provided with a crystal oscillator, and measures the time based on the reference clock signal output by the crystal oscillator. The crystal oscillator is well known as an electronic component that generates a reference clock signal with relatively high timing accuracy, but the timing accuracy inevitably includes errors.

[0015] In this way, the multiple CVS times in the multiple CVSs 1A-1X have the tendency that the deviation increases over time even if they are coincident (synchronized) at a certain time. When each communication unit 1a in the CVSs 1A-1X wirelessly transmits voltage detection data to the BMU 2, it adds the CVS time output by each clock unit 1b as detection time data. That is, each CVS 1A-1X wirelessly transmits the voltage detection data with the CVS time added to it as CVS time-added voltage data to the BMU 2 in chronological order.

[0016] The time adjustment unit 1c performs a time adjustment process of the CVS time on the clock unit 1b based on the reference time (BMU time) wirelessly received by the communication unit 1a from the BMU 2 (external) when the battery management system A starts operating, that is, when the CVS 1A to 1X are started up. The details of this time adjustment process will be described later, but the time adjustment unit 1c performs the time adjustment process of the CVS time on the clock unit 1b with priority when the CVS 1A to 1X are started up.

[0017] The BMU 2 is a battery management device that manages the assembled battery (subject to management) by wirelessly communicating with multiple CVS 1A-1X. That is, the BMU 2 manages the assembled battery (subject to management) by grasping the state of each battery cell in each battery module based on the CVS time-stamped voltage data wirelessly received in sequence from the multiple CVS 1A-1X.

[0018] As shown in the figure, each of such BMUs 2 includes a communication unit 2a and a clock unit 2b (RTC: Real Time Clock). The communication unit 2a wirelessly communicates with each of the multiple CVSs 1A-1X (more precisely, each communication unit 1a of the CVSs 1A-1X). These communication units 2a sequentially receive CVS time-stamped voltage data from the multiple CVSs 1A-1X. Furthermore, each communication unit 2a wirelessly transmits the time (BMU time) clocked by the above-mentioned clock unit 2b to each communication unit 1a of the CVSs 1A-1X as the above-mentioned reference time.

[0019] The clock unit 2b clocks the BMU time specific to the BMU 2. That is, each of the clock units 2b is equipped with a crystal oscillator, and clocks the BMU time based on the reference clock signal output by the crystal oscillator. The reference clock signal generated by the crystal oscillator of the BMU 2 has relatively high timing accuracy, like the crystal oscillators of the above-mentioned CVS 1A to 1X, but contains unavoidable errors.

[0020] That is, a plurality of CVS times and BMU times in a plurality of CVSs 1A to 1X coincide (synchronize) at a certain time, and have the property that the deviation increases over time.

[0021] Here, the BMU2 grasps the relationship of the detection times of the cell voltages among the multiple CVS1A-1X based on the CVS times included in the CVS time-stamped voltage data. Therefore, the deviation of the CVS times of the CVS time-stamped voltage data among the CVS1A-1X needs to be suppressed to a predetermined value or less when the BMU2 manages the assembled battery (subject to management).

[0022] Next, the operation of the battery management system A according to this embodiment, in particular the time adjustment process in each of the CVSs 1A to 1X, will be described in detail with reference to FIGS.

[0023] When the battery management system A starts operating, each of the CVSs 1A to 1X judges whether its own state is at the start of startup (step S1). Each of the CVSs 1A to 1X sets a startup end flag at a predetermined address of a non-volatile memory at the time of the previous startup end, for example, and checks the value of this startup end flag to judge whether its own state is at the start of startup.

[0024] The start of operation of the battery management system A, that is, the start-up of each of the CVSs 1A to 1X, occurs when the driver turns the ignition switch of the electric vehicle from an OFF state to an ON state. That is, when the ignition switch is set to the ON state, each of the CVSs 1A to 1X determines whether or not it is time to start up.

[0025] If the determination in step S1 is "Yes," that is, when each CVS1A-1X is starting to boot up, it wirelessly receives the BMU time from the BMU2 multiple times (step S2). That is, when the BMU2 starts up in the same way as each CVS1A-1X, it wirelessly transmits the BMU time to each CVS1A-1X multiple times, as shown in FIG.

[0026] In the BMU 2, when the communication unit 2a acquires the BMU time from the clock unit 2b, it generates a communication packet with the BMU time as transmission data and wirelessly transmits it to each communication unit 1a of the CVS 1A to 1X. When each communication unit 2a completes the first transmission of the BMU time, it repeatedly acquires a new BMU time from the clock unit 2b and wirelessly transmits it to each CVS 1A to 1X.

[0027] In other words, the multiple BMU times wirelessly transmitted in sequence from BMU 2 to each of CVS 1A-1X have a deviation equivalent to the transmission interval of the communication packets. The BMU time of the first communication packet wirelessly transmitted is the earliest time, and the BMU time of the last communication packet wirelessly transmitted is the latest time.

[0028] 3, variations in the wireless reception state of each CVS1A-1X when multiple BMU times are wirelessly transmitted in sequence from BMU 2 to each CVS1A-1X are shown as three patterns P1-P3. Pattern P1 shows a state in which the four BMU times are wirelessly received normally by each CVS1A-1X.

[0029] When each CVS1A-1X receives the first BMU time wirelessly, it compares the BMU time with its own CVS time. Then, if the deviation between the BMU time and the CVS time is within a predetermined time threshold, each CVS1A-1X considers the confirmation OK and provisionally sets the BMU time as the reference time. Note that the time threshold is a value estimated as a normal communication delay time in wireless communication between each CVS1A-1X and BMU2.

[0030] Then, when the three BMU times are subsequently "confirmed OK," each CVS 1A-1X matches (synchronizes) the BMU time provisionally set as the reference time with the CVS time (step S3). That is, the time adjustment unit 1c in each CVS 1A-1X compares the BMU time acquired from the communication unit 1a with the CVS time acquired from the clock unit 1b, and synchronizes the BMU time with the CVS time if the deviation is within a predetermined time threshold. This synchronization process is one form of the time adjustment process in this embodiment.

[0031] Pattern P2 shows a state where the BMU time is not normally received by each of CVS1A-1X due to an abnormal delay of the second communication packet. Pattern P3 shows a state where the first and second BMU times are not normally received by each of CVS1A-1X due to an abnormal delay of the first communication packet.

[0032] When each CVS 1A-1X completes the synchronization of the CVS time with the BMU time (reference time) at startup in this way, it wirelessly transmits voltage data with the CVS time in chronological order to the BMU 2. The BMU 2 determines the state of the assembled battery (subject to management) based on the voltage data with the CVS time wirelessly received in turn from each CVS 1A-1X, and performs management according to this state.

[0033] On the other hand, if the determination in step S1 is "No," that is, if the CVS 1A to 1X is not at startup but is in normal operation, it executes stage processing at regular intervals. This stage processing is the processing of stages No. 1 to No. 10 as shown in Fig. 4. Stage No. 1 is RTC synchronization, that is, processing (synchronization processing) to synchronize (match) the CVS time with the BMU time (reference time).

[0034] Stage No. 2 is a process (adjustment process) in which the CVS time is adjusted based on the BMU time (reference time). This adjustment process is another form of the time adjustment process in this embodiment. That is, stage No. 2 is a process in which the CVS time (device time) is adjusted to 1 / 2 or less of the allowable time discrepancy between the BMU time (reference time) and the CVS time (device time) in one time adjustment process. Stages No. 3 to No. 10 are processes A to G with different contents from stages No. 1 and No. 2.

[0035] Specifically, if the determination in step S1 is "No," each of the CVSs 1A to 1X determines whether or not to execute stage No. 2 first (step S4). That is, the determination in step S4 is "Yes" if the deviation between the BMU time (reference time) and the CVS time exceeds the time deviation tolerance.

[0036] Next, if the determination in step S4 is "Yes," each CVS 1A-1X determines whether the BMU time (reference time) and the CVS time are the same, that is, whether the BMU time (reference time) and the CVS time are synchronized (step S5). If the determination in step S5 is "No," that is, if the BMU time (reference time) and the CVS time are not synchronized, each CVS 1A-1X evaluates the chronological relationship between the BMU time (reference time) and the CVS time (step S6).

[0037] That is, in step S6, each CVS 1A to 1X judges whether the BMU time (reference time) is earlier than the CVS time (device time). Then, if the judgment in step S6 is "Yes", that is, if the BMU time (reference time) is earlier than the CVS time (device time), each CVS 1A to 1X executes stage No. 3 without executing stage No. 2 (step S7).

[0038] That is, when the BMU time (reference time) is earlier than the CVS time (device time), each CVS 1A-1X executes process A without executing the time adjustment process. In this case, the deviation of the CVS time (device time) from the BMU time (reference time) does not interfere with the management of the battery pack in BMU 2 based on the voltage data with the CVS time.

[0039] On the other hand, if the judgment in step S6 is "No", that is, if the BMU time (reference time) is slower than the CVS time (equipment time), each CVS 1A to 1X executes stage No. 2 to adjust the CVS time (equipment time) to less than half of the time discrepancy tolerance between the BMU time (reference time) and the CVS time (equipment time).

[0040] If the determination in step S4 is "No" and if the determination in step S5 is "Yes", each of the CVSs 1A to 1X ends the process relating to time adjustment without executing the stage process.

[0041] According to this embodiment, each CVS1A-1X (voltage detection device) is equipped with a time adjustment unit 1c that performs time adjustment processing of the CVS time (device time) in the timing unit 1b based on the BMU time (reference time) wirelessly received from the BMU2 (external) at startup, so that it is possible to reduce the processing burden during normal processing of the CVS1A-1X (voltage detection device) more than in the conventional case.

[0042] That is, according to this embodiment, it is possible to provide the CVS 1A to 1X (voltage detection devices) and the battery management system A that can reduce the processing load during normal operation of each of the CVS 1A to 1X (voltage detection devices) compared to the conventional art.

[0043] Furthermore, according to this embodiment, when each CVS1A-1X (voltage detection device) is operating normally, the CVS time (device time) is adjusted by half the time deviation tolerance between the BMU time (reference time) and CVS time (device time) in one time adjustment process. In other words, the time deviation between the BMU time (reference time) and CVS time (device time) is adjusted in steps of less than half the time deviation tolerance, thereby preventing over-adjustment of the CVS time (device time).

[0044] In other words, even if the CVS time (device time) is erroneously adjusted due to an abnormal communication delay caused by a disturbance in the wireless communication between each CVS1A-1X (voltage detection device) and BMU2, the adjustment amount of the CVS time (device time) is less than half the time deviation tolerance, so the deviation between the BMU time (reference time) and the CVS time (device time) will not exceed the time deviation tolerance.

[0045] The present invention is not limited to the above embodiment, and the following modifications are possible. For example, in the above embodiment, different time adjustment processes are executed at the start of each CVS 1A to 1X (voltage detection device) and during normal operation, but the present invention is not limited to this. The same time adjustment process may be executed at the start of each CVS 1A to 1X and during normal operation.

[0046] [Appendix 1] A voltage detection device that detects inter-electrode voltages of a plurality of battery cells in a battery pack in a time series manner as cell voltages, and wirelessly transmits the cell voltages, to which a device time measured by a timer unit has been added, to an external device as device time-appended voltage data, A voltage detection device comprising a time adjustment unit that performs a time adjustment process on the device time in the timing unit based on a reference time wirelessly received from an external device at startup.

[0047] [Appendix 2] 2. The voltage detection device according to claim 1, wherein the time adjustment unit adjusts the device time to less than or equal to half of a time deviation tolerance between the reference time and the device time in one time adjustment process.

[0048] [Appendix 3] 3. The voltage detection device according to claim 1, wherein the time adjustment unit sets the number of times the time adjustment process is performed in accordance with a deviation between the reference time and the device time.

[0049] [Appendix 4] 3. The voltage detection device according to claim 1, wherein the time adjustment unit sets the number of times the time adjustment process is performed depending on a time relationship between the reference time and the device time.

[0050] [Appendix 5] A voltage detection device according to any one of appendix 1 to 4, a battery pipeline device that wirelessly receives the device time-stamped voltage data and wirelessly receives the reference time; A battery management system comprising: [Explanation of symbols]

[0051] A Battery Management System 1A~1X CVS (voltage detector) 1a Communications Department 1b Clock part 1c Time adjustment section 2 BMU (Battery Management Unit) 2a Communication Department 2b Clock part

Claims

1. A voltage detection device that detects inter-electrode voltages of a plurality of battery cells in a battery pack in a time series manner as cell voltages, and wirelessly transmits the cell voltages, to which a device time measured by a timer unit has been added, to an external device as device time-appended voltage data, A voltage detection device comprising a time adjustment unit that performs a time adjustment process on the device time in the timing unit based on a reference time wirelessly received from an external device at startup.

2. 2 . The voltage detection device according to claim 1 , wherein the time adjustment section adjusts the device time by half an allowable time deviation between the reference time and the device time in each time of the time adjustment process.

3. 3. The voltage detection device according to claim 1, wherein the time adjustment unit sets the number of times the time adjustment process is performed in accordance with a deviation between the reference time and the device time.

4. 3. The voltage detection device according to claim 1, wherein the time adjustment unit sets the number of times the time adjustment process is performed depending on a relationship between the reference time and the device time.

5. A voltage detection device according to claim 1 or 2; a battery pipeline device that wirelessly receives the device time-stamped voltage data and wirelessly receives the reference time; A battery management system comprising:

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