JP7515569B2 - Battery monitoring device - Google Patents

Description

The present invention relates to a battery monitoring device.
This application claims priority based on Japanese Patent Application No. 2020-055526, filed in Japan on March 26, 2020, the contents of which are incorporated herein by reference.

The following Patent Document 1 discloses a voltage detection device in which multiple voltage detection circuits, each of which corresponds to one of the battery modules, are connected in series to a microcomputer via a communication line. In this voltage detection device, the multiple voltage detection circuits and the microcomputer communicate with each other via the communication line, so that the detected voltage of each voltage detection circuit is sent to the microcomputer.

Japanese Patent Publication No. 2015-136255

In DZ communication, the order in which a control device such as a microcomputer receives detected voltages depends on the connection order of each voltage detection circuit. Therefore, the control device can relatively easily determine the connection order of each voltage detection circuit, i.e., the connection order of each battery module.

However, in communication methods other than DZ communication, such as wireless communication, the order in which the control device receives the detected voltages does not have a fixed relationship to the connection order of each voltage detection circuit. This creates a problem in that the control device cannot easily grasp the connection order of each battery module.

The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a battery monitoring device that can easily grasp the connection order of multiple battery modules in communication methods other than DZ communication.

In order to achieve the above object, the present invention adopts the following aspects.
(1) In other words, a battery monitoring device according to one embodiment of the present invention comprises: a plurality of voltage detection circuits provided corresponding to each of a plurality of battery modules connected in series, each detecting the voltage of a plurality of battery cells constituting each of the battery modules as a cell voltage; a control circuit controlling the charging state of the plurality of battery cells by communicating with the voltage detection circuits using a communication method other than DZ communication; and a discharge means provided corresponding to each of the battery cells for discharging each of the battery cells. The control circuit instructs the voltage detection circuit to discharge the battery cell at the end by the discharge means in a connection relationship of each of the battery cells in one of the battery modules, thereby identifying other battery modules adjacent to the battery module so as to discharge the battery cell in the connection relationship.

(2) In the battery monitoring device described in (1) above, the following configuration may be adopted: each of the voltage detection circuits is provided with a non-volatile memory in which an identification code is stored; the control circuit receives the identification codes from all of the voltage detection circuits when connected to each of the voltage detection circuits; based on the identification codes, instructs each of the battery modules to discharge at least one of the battery cells at both ends in the connection relationship of each of the battery cells, and at that time, identifies the other adjacent battery modules based on fluctuations in parameters detected by the voltage detection circuits of the other battery modules other than the one to which the discharge instruction was given.

(3) In the battery monitoring device described in (1) or (2) above, the following configuration may be adopted: the voltage detection circuit includes an amplifier that amplifies a signal detecting the voltage of the battery cell at the end of each battery module; and the control circuit identifies other adjacent battery modules based on fluctuations in the voltage of the battery cell at the end of each battery module detected when the battery cell at the end of each battery module is discharged.

(4) In the battery monitoring device described in (1) or (2) above, the following configuration may be adopted: the voltage detection circuit includes a current detector arranged in parallel to the battery cell at the end of each battery module; and the control circuit identifies other adjacent battery modules based on a variation in a parameter based on the current detected by the current detector when the battery cell at the end of each battery module is discharged.

(5) In the battery monitoring device described in any one of (1) to (4) above, the communication method may be wireless communication.

According to the above aspect of the present invention, a battery monitoring device can be provided that can easily grasp the connection order of multiple battery modules in a communication method other than DZ communication.

1 is a block diagram showing a functional configuration of a battery monitoring device A according to an embodiment of the present invention. 4 is a flowchart showing the operation of the battery monitoring device A. 10 is a schematic diagram showing fluctuations in cell voltage when a specific battery cell Ca is forcibly discharged in the embodiment. FIG. 10 is a schematic diagram showing fluctuations in cell voltage when a specific battery cell Ca is forcibly discharged in the embodiment. FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A battery monitoring device according to an embodiment of the present invention will now be described with reference to the drawings.
1, a battery monitoring device A according to this embodiment includes a plurality of voltage detection circuits D1 to Dn and one control circuit M, and detects the voltage of a battery pack B to control the state of charge of the battery pack B. The battery monitoring device A controls the state of charge of a battery pack B mounted on a vehicle such as an electric vehicle or a hybrid vehicle. In the description of this embodiment, "n" represents a natural number.

Battery pack B is a secondary battery mounted on the vehicle as a high-voltage power source, and can be charged and discharged freely. Battery pack B is made up of multiple battery modules J1 to Jn connected in series, and outputs a DC voltage of, for example, several hundred volts. Each of the multiple battery modules J1 to Jn is made up of multiple battery cells C connected in series, and outputs a DC voltage according to the number of battery cells C. The multiple battery cells C are single cells, and each outputs a DC voltage of about several volts.

The battery pack B outputs a high voltage (DC voltage) of, for example, several hundred volts depending on the number of battery modules, i.e., the number of battery cells C. Unlike secondary batteries that output a relatively low DC voltage, such as lead-acid batteries mounted on typical vehicles, the battery pack B requires precise control of the charge and discharge state. The battery pack B is, for example, a lithium-ion battery.

The multiple voltage detection circuits D1 to Dn are provided corresponding to each of the multiple battery modules J1 to Jn described above. The multiple voltage detection circuits D1 to Dn detect the output voltage of the multiple battery cells C constituting each of the battery modules J1 to Jn, that is, the inter-terminal voltage (cell voltage) between the positive terminal and the negative terminal of each battery cell C. That is, the first voltage detection circuit D1 is connected to the first battery module J1, the second voltage detection circuit D2 is connected to the second battery module J2, ..., the nth voltage detection circuit Dn is connected to the nth battery module Jn.

Each of these voltage detection circuits D1 to Dn has a wireless communication function for wirelessly communicating with the control circuit M, and transmits the detected cell voltages to the control circuit M by a predetermined wireless communication method. That is, in this embodiment, a wireless communication method is adopted as a communication method other than DZ communication.
Each of the voltage detection circuits D1 to Dn includes a discharge circuit (discharge means) CH1 to CH8 associated with each individual battery cell C. When each of the voltage detection circuits D1 to Dn receives a control command from the control circuit M, it forcibly discharges each individual battery cell C.

Each of the voltage detection circuits D1 to Dn is provided with a fluctuation detection circuit K. As shown in the figure, these fluctuation detection circuits K are provided corresponding to the battery cell C (one) at the low-voltage end, and are either an amplifier for amplifying a signal that detects the voltage (cell voltage) of the battery cell C, or a current detector provided in parallel to the battery cell C. The fluctuation detection circuit K detects fluctuations in the cell voltage of the battery cell C (one) at the low-voltage end, or fluctuations in the cell current flowing through the battery cell C.

Each of the multiple voltage detection circuits D1 to Dn is assigned an individual identification number. This individual identification number is an identification code that is uniquely set in advance for each of the voltage detection circuits D1 to Dn, and is stored in advance in a non-volatile memory provided in each voltage detection circuit D1 to Dn. Each voltage detection circuit D1 to Dn is a communication node (CMU node) for wireless communication with the control circuit M, and by performing wireless communication with the control circuit M using the individual identification number, the control circuit M identifies itself (as an individual).

The control circuit M is a microcomputer that controls the charging state of the assembled battery B, i.e., the multiple battery cells C, by communicating with each voltage detection circuit D1-Dn (CMU node) using the above-mentioned predetermined wireless communication method. That is, the control circuit M detects the charging state of the assembled battery B, i.e., each battery cell C, based on the cell voltages received from each voltage detection circuit D1-Dn (CMU node) via wireless communication. Furthermore, the control circuit M controls the charging state of the assembled battery B by transmitting control commands generated based on this detection result to each voltage detection circuit D1-Dn (CMU node) via wireless communication.

The control circuit M includes a non-volatile memory in which a control program and various control data are stored, a calculation unit that executes calculations based on the control program, a volatile memory that temporarily stores the calculation results of the calculation unit, and a communication unit that performs wireless communication with each voltage detection circuit D1 to Dn (CMU node).

The control circuit M acquires the individual identification number described above from each of the voltage detection circuits D1 to Dn (CMU nodes) and performs wireless communication with each of the voltage detection circuits D1 to Dn (CMU nodes) individually based on this individual identification number. Although not shown, the control circuit M is connected to the vehicle's higher-level control system by wired communication.

As described above, the control circuit M can perform wireless communication by identifying (specifying) each individual voltage detection circuit D1-Dn (CMU node) by using the individual identification number. However, before performing wireless communication with each voltage detection circuit D1-Dn (CMU node), the control circuit M does not store control data indicating the individual identification number of each voltage detection circuit D1-Dn (CMU node). In addition, the control circuit M does not store control data indicating the connection position of each voltage detection circuit D1-Dn (CMU node) with respect to each battery module J1-Jn.

That is, the control circuit M does not initially recognize the individual identification number (first individual identification number) of the first voltage detection circuit D1 (CMU node), the individual identification number (second individual identification number) of the second voltage detection circuit D2 (CMU node), ..., the individual identification number (nth individual identification number) of the nth voltage detection circuit Dn (CMU node).
In addition, the control circuit M does not recognize the connection positions, such as that the first voltage detection circuit D1 (CMU node) is connected to the first battery module J1 and the second voltage detection circuit D2 (CMU node) is connected to the second battery module J2.

Therefore, the control circuit M cannot initially recognize which of the multiple serially connected battery modules J1 to Jn the cell voltage obtained from each voltage detection circuit D1 to Dn (CMU node) corresponds to. It is essential for the control circuit M to recognize the individual identification number and connection position in order to control the charge/discharge state of the battery pack B.

Next, the operation of the battery monitoring device A to recognize the above-mentioned connection position will be explained with reference to the flowchart in Figure 2.

When the vehicle's ignition switch (IG) changes from the "OFF" state to the "ON" state, this state change is notified from the higher-level control system to the control circuit M. When the control circuit M recognizes this "IG ON" (step S1), it determines whether the connection positions of each battery module J1 to Jn to each voltage detection circuit D1 to Dn have been recognized (step S2).

That is, since the process of FIG. 2 is executed when "IG ON" has been performed in the past, the control data (connection position data) indicating the above-mentioned connection position is stored in the non-volatile memory of the control circuit M. On the other hand, when "IG ON" is performed for the first time, the process of FIG. 2 is not executed.

For these reasons, the control circuit M checks whether or not the connection position data is stored in the non-volatile memory, and if the connection position data is stored, the determination in step S2 is "Yes," and if the connection position data is not stored, the determination in step S2 is "No." If the determination in step S2 is "Yes," the control circuit M ends all processing. On the other hand, if the determination in step S2 is "No," the control circuit M determines whether or not a pairing instruction has been received from the higher-level control system (step S3).

The judgment in step S3 is “Yes” if the control circuit M has already received a pairing instruction from the higher-level control system and stored it in non-volatile memory, and is “No” if the pairing instruction has not been stored in non-volatile memory.
If the determination in step S3 is "Yes", the process proceeds to step S4, where the control circuit M receives a pairing instruction (BMU pairing instruction) from the higher-level control system. The control circuit M then transmits a request to obtain individual identification numbers to all voltage detection circuits D1 to Dn (all CMU nodes) (step S5). On the other hand, if the determination in step S3 is "No", the determination in step 3 is performed again.

After step S5, the process proceeds to step S6. In step S6, if the control circuit M has received individual identification numbers from all of the voltage detection circuits D1 to Dn (all CMU nodes), the process judges the result as "Yes" and proceeds to step S7. On the other hand, if the judgment in step S6 is "No", the process repeats the judgment in step S6.
In step S7, one of the voltage detection circuits D1 to Dn (CMU nodes) is individually selected, and the discharge circuit corresponding to a specific battery cell C is activated for that selected voltage detection circuit (CMU node), thereby forcibly discharging the specific battery cell C.

The specific battery cell C is the battery cell C (one cell) at the high-voltage end in the connection relationship of the multiple battery cells C in each battery module J1 to Jn. For example, when the control circuit M individually selects the second voltage detection circuit D2 (second CMU node), it forcibly discharges the battery cell C at the high-voltage end in the second battery module J2 connected to the second voltage detection circuit D2, that is, the battery cell C located on the highest potential side among the multiple battery cells C connected in series, as the specific battery cell C.

Due to the forced discharge of such a specific battery cell C, in the connection relationship of the multiple battery modules J1 to Jn that make up the battery pack B, i.e., the multiple battery cells C, the cell voltage or cell current of the battery cell C adjacent to the specific battery cell C (adjacent battery cell) fluctuates from the original cell voltage or cell current.

As shown in FIG. 3A, for example, for the second voltage detection circuit D2 (second CMU node), when the battery cell Ca at the high-voltage end of the second battery module J2 is forcibly discharged as a specific battery cell C, the cell voltage or cell current of the battery cell C at the low-voltage end of the first battery module J1 (other battery module) adjacent to the high-voltage side of this battery cell Ca changes.

Following step S7, the process proceeds to step S8. In step S8, the control circuit M determines whether or not a fluctuation in cell voltage or cell current has occurred in the battery cell C at the high-voltage end based on the detection result of the fluctuation detection circuit K when discharging the battery cell C at the connection end of the one battery module connected to one voltage detection circuit (CMU node) individually selected from the voltage detection circuits D1 to Dn (CMU nodes).
When the voltage or cell current fluctuates (step S8: Yes), the control circuit M proceeds to step S9. In step S9, the control circuit M recognizes other battery modules (adjacent nodes) adjacent to the battery cell C that has fluctuated. After step S9, the control circuit M proceeds to step S11.

Here, as shown in FIG. 3B, when the battery cell C at the high-voltage end of the first battery module J1 connected to the first voltage detection circuit D1 (first CMU node) is forcibly discharged, there are no other battery modules adjacent to the high-voltage side of the battery cell C at the high-voltage end. Therefore, in this case, no fluctuations occur in the cell voltage or cell current of the battery cell C for the other battery modules. In other words, in this case, the judgment in step S8 is "No".

In such a case, the process proceeds from step S8 to step S10.
In step S10, the control circuit M recognizes one voltage detection circuit (CMU node) as the top node, that is, the MCU node connected to the battery module that is located at the topmost connection position among the multiple battery modules J1 to Jn in the battery pack B.

Then, when the control circuit M completes the process up to step S10 for one voltage detection circuit (CMU node) individually selected in step S7, it proceeds to step S11. In step S11, it determines whether the process up to step S10 has been completed for all of the battery modules J1 to Jn. If the answer is "No" in step S11, the process returns to step S7. On the other hand, if the answer is "Yes" in step S11, the process ends.
The control circuit M identifies the relative positions of all the battery modules J1 to Jn that constitute the battery pack B by repeating the processes in steps S7 to S10 for all the battery modules J1 to Jn (all CMU nodes).

According to this embodiment, by forcibly discharging the battery cell C at the end of the connection relationship of the battery cells C in one battery module among the multiple battery modules J1 to Jn that make up the battery pack B, it is possible to identify other battery modules adjacent to the one battery module in the above connection relationship. Therefore, according to this embodiment, it is possible to easily grasp the connection order of the multiple battery modules J1 to Jn in a wireless communication method other than DZ communication.

The present invention is not limited to the above-described embodiment, and the following modifications are possible.
(1) In the above embodiment, in the connection relationship of the plurality of battery cells C in the battery module, the battery cell C (one cell) at the high-voltage end is set as the specific battery cell C. However, the present invention is not limited to this. Instead of setting the battery cell C (one cell) at the high-voltage end in the connection relationship of the plurality of battery cells C in the battery module as the specific battery cell C, the battery cell C (one cell) at the low-voltage end in the connection relationship of the plurality of battery cells C in the battery module may be set as the specific battery cell C.

In this case, the cell voltage or cell current of the battery cell C at the high-voltage end of another battery module adjacent to the low-voltage side of the specific battery cell C changes. The control circuit M can identify the other battery module adjacent to the low-voltage side based on the fluctuation in the cell voltage or cell current of the battery cell C at the high-voltage end.

(2) In addition, instead of designating the battery cell C (one cell) located at the high-voltage end in the connection relationship of multiple battery cells C in a battery module as a specific battery cell C, the battery cells C (two cells) located at the high-voltage end and the low-voltage end in the connection relationship of multiple battery cells C in a battery module may be designated as a specific battery cell C.

In this case, the cell voltage or cell current of the battery cell C at the low-voltage end of the other battery module adjacent to the high-voltage side fluctuates, and the cell voltage or cell current of the battery cell C at the high-voltage end of the other battery module adjacent to the low-voltage side fluctuates. The control circuit M can simultaneously identify the two other battery modules adjacent to the high-voltage side and the low-voltage side based on the fluctuations in the cell voltage or cell current of these two other battery modules.

(3) In the above embodiment, other battery modules were identified based on the fluctuation in cell voltage or cell current detected when discharging a battery cell C at the end in the connection relationship of the multiple battery cells C in each battery module J1 to Jn, but the present invention is not limited to this. For example, other battery modules may be identified based on the fluctuation in the internal impedance of the battery cell C instead of or in addition to the fluctuation in cell voltage or cell current.

(4) In the above embodiment, a wireless communication method is used as a communication method other than DZ communication, but the present invention is not limited to this. For example, a network communication method such as CAN may be used.

According to the above aspect of the present invention, a battery monitoring device can be provided that can easily grasp the connection order of multiple battery modules in a communication method other than DZ communication.

A Battery monitoring device B Battery pack C Battery cell CH1 to CH8 Discharge circuit (discharge means)
D1 to Dn Voltage detection circuit J1 to Jn Battery module M Control circuit K Fluctuation detection circuit

Claims (5)

a plurality of voltage detection circuits provided corresponding to each of the plurality of battery modules connected in series, each detecting the voltage of a plurality of battery cells constituting each of the battery modules as a cell voltage;
a control circuit that controls the charging states of the battery cells by communicating with the voltage detection circuit using a communication method other than DZ communication;
Discharging means provided corresponding to each of the battery cells for discharging each of the battery cells;
Equipped with
the control circuit instructs the voltage detection circuit to cause the discharge means to discharge the battery cell at the end in a connection relationship of the battery cells in one battery module,
a battery monitoring device that identifies another battery module adjacent to the battery module so as to discharge the battery cell in the connection relationship. Each of the voltage detection circuits includes a non-volatile memory in which an identification code is stored;
the control circuit receives the identification codes from all of the voltage detection circuits when connected to each of the voltage detection circuits;
Based on the identification code, an instruction is issued to each of the battery modules to discharge at least one of the battery cells at either end in relation to a connection relationship of each of the battery cells, and at that time, an adjacent battery module is identified based on a variation in a parameter detected by the voltage detection circuit of the battery module other than the battery module to which the instruction to discharge has been issued;
2. The battery monitoring device according to claim 1 . The voltage detection circuit includes an amplifier that amplifies a signal detected by detecting a voltage of the battery cell at an end of each battery module;
The control circuit identifies the adjacent battery module based on a change in voltage of the battery cell at the end of each battery module detected when the battery cell at the end of each battery module is discharged;
3. The battery monitoring device according to claim 1 or 2. the voltage detection circuit includes a current detector disposed in parallel with the battery cells at the end of each battery module;
The control circuit identifies the adjacent battery module based on a change in a parameter based on a current detected by the current detector when the battery cell at the end of each battery module is discharged;
3. The battery monitoring device according to claim 1 or 2. 5. The battery monitoring device according to claim 1, wherein the communication method is wireless communication.

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