Battery-monitoring system and identifying-information setting method

Each of a plurality of monitoring units (10) that monitor the states of batteries allocates, as identifying information for itself, identifying information corresponding to an input signal inputted from a preceding control unit (3) or monitoring unit (10); outputs, to a subsequent monitoring unit (10), a signal that differs from the input signal corresponding to the identifying information the monitoring unit (10) in question has allocated to itself; and, if and when identifying information corresponding to an input signal differs from the identifying information the monitoring unit (10) in question had allocated to itself, reallocates identifying information corresponding to said input signal as identifying information for itself.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No. PCT/JP2014/052043 filed Jan. 30, 2014, claiming priority based on Japanese Patent Application No. 2013-078427 filed Apr. 4, 2013, the contents of all of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present invention discussed herein is related to a technology for monitoring states of a plurality of batteries.

BACKGROUND ART

In recent years, batteries that are obtained by connecting a plurality of batteries in parallel in order to stably supply to a load a large amount of power have been mounted on vehicles such as electric forklift trucks, hybrid vehicles, or electric vehicles.

In addition, some battery-monitoring systems that monitor the state of each battery include control units that allow charging and discharging of each battery according to the monitoring result of each battery. In such a battery-monitoring system, the control unit requires identifying information that is individually allocated to each of a plurality of monitoring units that monitor the states of the batteries in order to obtain the monitoring result from each monitoring unit.

In a case in which positions of two of the batteries are swapped or at least one of the batteries is replaced with a new battery, when identifying information for the monitoring unit that corresponds to the battery after swapping or after replacement has been changed, the monitoring unit that corresponds to the battery after swapping or after replacement cannot communicate normally with the control unit.

Therefore, resetting of the identifying information for the monitoring unit that corresponds to the battery after swapping or after replacement is required (For example, see Patent documents 1 and 2).

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

However, in a case in which all the monitoring units are connected in series, that is, are daisy-chain connected, even when in-between monitoring units have been swapped or an in-between monitoring unit is replaced, identifying information for all the monitoring units has to be reset, and therefore there is concern that resetting of identifying information will require a lot of time and trouble.

Therefore, the present invention aims to provide a battery-monitoring system and an identifying-information setting method that enable easy resetting of identifying information for a monitoring unit in a case in which monitoring units that monitor states of batteries that are connected in parallel are connected in series.

Solution to Problem

The battery-monitoring system of the present invention includes a plurality of monitoring units to monitor the states of batteries, and a control unit to communicate with the plurality of monitoring units by using identifying information that has been allocated to each of the plurality of monitoring units that are connected in series.

Each of the plurality of monitoring units allocates as identifying information for itself identifying information that corresponds to a first signal that has been output from a preceding control unit or monitoring unit, outputs to a subsequent monitoring unit a second signal that differs from the first signal that corresponds to the identifying information that the monitoring unit in question has allocated to itself, and in a case in which identifying information that corresponds to the first signal differs from the identifying information that the monitoring unit in question has allocated to itself, reallocates identifying information that corresponds to the first signal as identifying information for itself.

Thus, in a case in which an in-between monitoring unit among the plurality of monitoring units that are connected in series is replaced with a new monitoring unit, since a resetting of identifying information for subsequent monitoring units in addition to identifying information for the new monitoring unit is required, resetting of identifying information for the monitoring units may be performed in an easier way in comparison with the case of resetting identifying information for all the monitoring units after replacement of the monitoring unit.

Advantageous Effects of Invention

According to the present invention, in a case in which monitoring units that monitor the states of batteries that are connected in parallel are connected in series, resetting of identifying information for the monitoring unit may be easily performed.

DESCRIPTION OF EMBODIMENTS

FIG. 1is a diagram illustrating a battery-monitoring system of an embodiment.

The battery-monitoring system1illustrated inFIG. 1includes a plurality of battery modules2(2-1to2-5), a control unit (battery ECU)3, and a main relay4. Note that the battery-monitoring system1is mounted on a vehicle such as an electric forklift truck, a hybrid vehicle, or an electric vehicle. In addition, the number of battery modules2is not limited to 5.

Each of the battery modules2-1to2-5includes a battery5, a relay6, a voltage detection unit7, a current detection unit8, a temperature detection unit9, and a monitoring unit (monitoring ECU)10.

The battery5is a rechargeable battery, and is, for example, a lithium-ion secondary battery or a nickel hydride battery. The battery5may be configured by including a plurality of batteries that are connected in series. The batteries5are connected in parallel and supply power to a load11.

The relay6is provided between the main relay4and the battery5. When the main relay4is turned on while the relay6is on, power may be supplied from the battery5to the load11.

The voltage detection unit7detects the voltage of the battery5and is, for example, a voltmeter.

The current detection unit8detects a current that flows to the battery5during charging and a current that flows from the battery5during discharging, and is, for example, an ammeter.

The temperature detection unit9detects ambient temperature of the battery5, and is, for example, a thermistor.

The monitoring unit10includes a relay control unit12, a storage unit13, an identifying-information setting unit14, and a communication unit15. Note that the relay control unit12, the identifying-information setting unit14, and the communication unit15are configured, for example, by using a CPU (Central Processing Unit), a multi-core CPU, a programmable device (FPGA (Field Programmable Gate Array), PLD (Programmable Logic Device), etc.) and are realized by reading and executing by the CPU, the programmable device, or the PLD a program that has been stored in the storage unit13.

The relay control unit12controls on and off of the relay6.

The storage unit13is, for example, a ROM (Read Only Memory) or a RAM (Random Access Memory), and stores various pieces of information and various programs.

The identifying-information setting unit14sets identifying information for itself and causes the storage unit13to store therein the identifying information. For example, in a case in which five pieces of identifying information, “101”, “102”, “103”, “104”, and “105” are allocated to the battery modules2-1to2-5, respectively, the identifying-information setting unit14of the leading battery module2-1allocates “101” as identifying information for itself and causes the storage unit13to store therein the information. The identifying-information setting unit14of the battery module2-2that is arranged subsequent to the battery module2-1allocates “102” as identifying information for itself and causes the storage unit13to store therein the information. The identifying-information setting unit14of the battery module2-3that is arranged subsequent to the battery module2-2allocates “103” as identifying information for itself and causes the storage unit13to store therein the information. The identifying-information setting unit14of the battery module2-4that is arranged subsequent to the battery module2-3allocates “104” as identifying information for itself and causes the storage unit13to store therein the information. The identifying-information setting unit14of the battery module2-5that is arranged subsequent to the battery module2-4allocates “105” as identifying information for itself and causes the storage unit13to store therein the information.

The communication unit15inputs (receives) a signal that has been output (transmitted) from the preceding control unit3or the preceding monitoring unit10and outputs (transmits) a signal to the subsequent monitoring unit10.

The control unit3includes a relay control unit16that controls on and off of the main relay4, a storage unit17, an abnormity determination unit18, and a communication unit19that communicates with the monitoring units10of the battery modules2-1to2-5. Note that the storage unit17is, for example, a ROM or a RAM, and stores various pieces of information and various programs. The relay control unit16, the abnormity determination unit18, and the communication unit19are configured, for example, by using a CPU, a multi-core CPU, and a programmable device (FPGA, PLD, etc.), and are realized by reading and executing by the CPU, the programmable device, or the PLD a program that has been stored in the storage unit17. When the control unit3receives by means of the communication unit19identifying information that has been transmitted from each of the battery modules2-1to2-5, the control unit3causes the storage unit17to store therein identifying information in association with the order of the battery modules2-1to2-5. The control unit3uses the identifying information that has been stored in the storage unit17so as to receive by means of the communication unit19information that has been transmitted from each of the battery modules2-1to2-5and that indicates the state of the battery5(for example, the voltage, current, and temperature of the battery5). When the state of the battery5that is indicated in the received information falls under a condition that has been specified in advance (for example, when at least one of the voltage, current, and temperature of the battery5is higher than a threshold), the control unit3judges that the state of at least one battery5among the batteries5of the battery modules2-1to2-5is anomalous, and transitions to an evacuation running mode (for example, a process for transmitting to a host control unit that controls the travel of the vehicle an instruction to gradually decelerate and stop the vehicle within a fixed time period and turning off the main relay4by means of the relay control unit16after a fixed time has passed). In a case in which at least one piece of identifying information among the pieces of identifying information that have been transmitted from the battery modules2-1to2-5has already been stored in the storage unit17and at the same time the main relay4is turned on, the control unit3judges that swapping or replacement of the battery modules2-1to2-5has been performed when power is supplied from the battery5to the load11, and transitions to the evacuation running mode. In a case in which at least one battery module2among the battery modules2-1to2-5transmits information indicating that a communication abnormity has occurred, the control unit3transitions to the evacuation running mode.

The control unit3and the monitoring units10of the battery modules2-1to2-5are connected in series via the communication units15and19, which is referred to as daisy chain connection.

Note that signals that are used for setting identifying information are not limited to square waves whose duty ratios are varied; however, in a case in which identifying information is set according to the duty ratio of a square wave in the same manner as above, configuration of the communication unit15may be made simpler in comparison with that in the case of setting identifying information by using a signal that requires a complicated process such as a modulation process or an encoding process.

The identifying-information setting unit14of each of the battery modules2-1to2-5may set identifying information by using the frequency of an input signal or the number of pulses of an input signal per unit time. In addition to a square wave, a numerical value or character information may be used as a signal that is used for setting identifying information.

When a communication line that interconnects the control unit3and the monitoring units10of the battery modules2-1to2-5is not used in an identifying-information setting process, the communication line may be used for transmitting to the control unit3information indicating that a communication abnormity has occurred.

FIG. 2is a flowchart illustrating operations of the monitoring unit10.

First, when identifying-information setting timing has come, the identifying-information setting unit14of the monitoring unit10refers to information that is stored in the storage unit13and is obtained by associating an input signal, identifying information, and an output signal with one another (hereinafter referred to as identifying-information setting information), acquires an input signal that corresponds to identifying information for itself that has been stored in the storage unit13, and judges whether or not the acquired input signal and a signal that has been input to the communication unit15for itself match with each other (S21). Note that the identifying information setting timing is set, for example, at fixed time intervals after initial setting, or when the communication line is connected to a communication connector of the communication unit15for itself due to swapping or replacement of the battery module2. Operations in the initial setting of identifying information will be described later. Note that judgment on matching is not limited to making a judgment by comparing input signals. The identifying-information setting unit14may acquire with reference to the identifying-information setting information identifying information for itself that has been stored in the storage unit13and identifying information that corresponds to the signal that has been input to the communication unit15for itself, may compare both pieces of identifying information with each other, and may judge whether or not they match with each other.

Next, in a case in which the identifying-information setting unit14judges that the input signal that corresponds to the identifying information for itself and the signal that has been input to the communication unit15match with each other (Yes in S21), when the relay6is not turned on (No in S22), the identifying-information setting unit14turns on the relay6by means of the relay control unit12(S23).

Next, when the relay6is in an on-state (Yes in S22, or S23), the identifying-information setting unit14refers to the identifying-information setting information, acquires an output signal that corresponds to the identifying information for itself, outputs to the subsequent monitoring unit10the acquired output signal (S24), and thereafter transmits to the control unit3the identifying information for itself (S25), and terminates the identifying-information setting process.

In a case in which the identifying-information setting unit14judges that the input signal that corresponds to the identifying information for itself and the signal that has been input to the communication unit15do not match with each other (No in S21), when the relay6is turned on (Yes in S26), the identifying-information setting unit14turns off the relay6by means of the relay control unit12.

Next, when the relay6is in an off-state (No in S26, or S27) and at the same time the signal that has been input to the communication unit15of the monitoring unit10in question is included in the identifying-information setting information (Yes in S28), the identifying-information setting unit14causes the storage unit13to store therein as identifying information for itself identifying information that corresponds to the signal (S29), and thereafter turns on the relay6by means of the relay control unit12(S23). In regard to subsequent operations, as described above, the identifying-information setting unit14refers to the identifying-information setting information, acquires an output signal that corresponds to the identifying information for itself, outputs to the subsequent monitoring unit10the acquired output signal (S24), and thereafter transmits to the control unit3the identifying information for itself (S25), and terminates the identifying-information setting process.

When the signal that has been input to the communication unit15is not included in the identifying-information setting information (No in S28), the identifying-information setting unit14transmits to the control unit3information indicating that a communication abnormity has occurred (S30).

For example, at the initial setting of identifying information, when the duty ratio of a square wave as a signal that has been output from the control unit3and has been input to the communication unit15of the battery module2-1is “10%”, the battery module2-1refers to the identifying-information setting information illustrated inFIG. 3, acquires identifying information (“101”) that corresponds to the “10%”, causes the storage unit13to store therein the identifying information (“101”) as identifying information for itself, and thereafter turns on the relay6by means of the relay control unit12. Then, the battery module2-1refers to the identifying-information setting information illustrated inFIG. 3, acquires duty ratio “20%” of a square wave as an output signal that corresponds to the identifying information (“101”) for itself, outputs to the monitoring unit10of the subsequent battery module2-2the square wave of the acquired duty ratio “20%”, and thereafter transmits to the control unit3the identifying information (“101”) for itself. At the initial setting of identifying information, when the duty ratio of a square wave as a signal that has been output from the battery module2-1and has been input to the communication unit15of the battery module2-2is “20%”, the battery module2-2refers to the identifying-information setting information illustrated inFIG. 3, acquires identifying information (“102”) that corresponds to the duty ratio “20%”, causes the storage unit13to store therein the identifying information (“102”) as identifying information for itself, and thereafter turns on the relay6by means of the relay control unit12. Then, the battery module2-2refers to the identifying-information setting information illustrated inFIG. 3, acquires duty ratio “30%” of a square wave as an output signal that corresponds to the identifying information (“102”) for itself, outputs to the monitoring unit10of the subsequent battery module2-3the square wave of the acquired duty ratio “30%”, and thereafter transmits to the control unit3the identifying information (“102”) for itself. At the initial setting of identifying information, when the duty ratio of a square wave as a signal that has been output from the battery module2-2and has been input to the communication unit15of the battery module2-3is “30%”, the battery module2-3refers to the identifying-information setting information illustrated inFIG. 3, acquires identifying information (“103”) that corresponds to the duty ratio “30%”, causes the storage unit13to store therein the identifying information (“103”) as identifying information for itself, and thereafter turns on the relay6by means of the relay control unit12. Then, the battery module2-3refers to the identifying-information setting information illustrated inFIG. 3, acquires duty ratio “40%” of a square wave as an output signal that corresponds to the identifying information (“103”) for itself, outputs to the monitoring unit10of the subsequent battery module2-4the signal of the acquired duty ratio “40%”, and thereafter transmits to the control unit3the identifying information (“103”) for itself. At the initial setting of identifying information, when the duty ratio of a square wave as a signal that has been output from the battery module2-3and has been input to the communication unit15of the battery module2-4is “40%”, the battery module2-4refers to the identifying-information setting information illustrated inFIG. 3, acquires identifying information (“104”) that corresponds to the duty ratio “40%”, causes the storage unit13to store therein the identifying information (“104”) as the identifying information for itself, and thereafter turns on the relay6by means of the relay control unit12. Then, the battery module2-4refers to the identifying-information setting information illustrated inFIG. 3, acquires duty ratio “50%” of a square wave as an output signal that corresponds to the identifying information (“104”) for itself, outputs to the monitoring unit10of the subsequent battery module2-5the signal of the acquired duty ratio “50%”, and thereafter transmits to the control unit3the identifying information (“104”) for itself. At the initial setting of identifying information, when the duty ratio of a square wave as a signal that has been output from the battery module2-4and has been input to the communication unit15of the battery module2-5is “50%”, the battery module2-5refers to the identifying-information setting information illustrated inFIG. 3, acquires identifying information (“105”) that corresponds to the duty ratio “50%”, causes the storage unit13to store therein the identifying information (“105”) as identifying information for itself, and thereafter turns on the relay6by means of the relay control unit12, and transmits to the control unit3the identifying information (“105”) for itself.

Thus, in comparison with the case of setting identifying information by transmitting and receiving numerical information, the configuration of the monitoring unit10may be made simpler because it is possible to set identifying information only by transmitting and receiving signals whose duty ratios have been varied. The control unit3may recognize the number of connected monitoring units10by receiving identifying numbers from the monitoring units10.

For example, in a case in which the battery module2-4whose identifying information is “104” is replaced with a new battery module2whose identifying information is “102”, when the identifying-information setting timing has come, the identifying-information setting unit14of the battery module2after replacement refers to the identifying-information setting information illustrated inFIG. 3and acquires “20%” as the duty ratio of a square wave as an input signal that corresponds to “102”, which is the identifying information for itself. Next, when the identifying-information setting unit14judges that the acquired duty ratio “20%” and the duty ratio “40%” of a signal that has been input to the communication unit15for itselfdo not match with each other, if the relay6is not turned off, the identifying-information setting unit14turns off the relay6by means of the relay control unit12. Next, the identifying-information setting unit14refers to the identifying-information setting information illustrated inFIG. 3, acquires “104” as identifying information that corresponds to the duty ratio “40%” of the signal that has been input to the communication unit15, causes the storage unit13to store therein the acquired identifying information (“104”) as identifying information for itself, and thereafter turns on the relay6by means of the relay control unit12. Then, the identifying-information setting unit14refers to the identifying-information setting information illustrated inFIG. 3, acquires “50%” as the duty ratio of a square wave as an output signal that corresponds to “104”, which is the identifying information for itself, outputs to the monitoring unit10of the subsequent battery module2-5the square wave of the acquired duty ratio 50%, and thereafter transmits to the control unit3“104” as the identifying information for itself, and terminates an identifying-information resetting process. Note that when the battery module2-4is replaced with a new battery module2, the identifying-information setting unit14of the subsequent battery module2-5might set wrong identifying information according to a signal before a resetting that has been transmitted from the new battery module2. In such a case, after a resetting of the identifying information for the new battery module2has been completed, the identifying information for the subsequent battery module2-5is set again.

For example, in a case in which a signal of duty ratio “100%” or a signal of duty ratio “0%” has been input from the communication unit15of the battery module2-3to the communication unit15of the battery module2-4because the communication unit15of the battery module2-3becomes anomalous or the communication line is extracted from a communication connector of the communication unit15of the battery module2-3, the identifying-information setting unit14of the battery module2-4judges that the input signal of duty ratio “100%” or the input signal of the duty ratio “0%” is not included in the identifying-information setting information illustrated inFIG. 3and transmits to the control unit3information indicating that a communication abnormity has occurred.

FIG. 4is a flowchart illustrating operations of the control unit3.

First, when the abnormity determination unit18of the control unit3receives from at least one battery module2among the battery modules2-1to2-5information indicating that a communication abnormity has occurred (Yes in S41), the abnormity determination unit18transitions to the evacuation running mode (S42). In addition, when the abnormity determination unit18receives identifying information from the battery modules2-1to2-5(No in S41and Yes in S43), if at least one piece of the received identifying information has already been stored in the storage unit17(Yes in S44) and the main relay4is turned on (Yes in S45), the abnormity determination unit18transitions to the evacuation running mode (S42). Thus, in a case in which a communication abnormity occurs and in a case in which the battery module2has been replaced while the battery5is being used, the mode may transition to the evacuation running mode and thus safety of the vehicle may be enhanced.

As described, according to the battery-monitoring system1of the embodiment, each of the monitoring units10of the battery modules2-1to2-5allocates as identifying information for itself identifying information that corresponds to an input signal that has been input from the preceding control unit3or monitoring unit10, outputs to the subsequent monitoring unit10an output signal that differs from the input signal that corresponds to the identifying information that the monitoring unit10in question has allocated to itself, and in a case in which identifying information that corresponds to an input signal differs from the identifying information that the monitoring unit10in question has allocated to itself, reallocates the identifying information that corresponds to the input signal as identifying information for itself. Thus, in a case in which the battery module2-4among the battery modules2-1to2-5is replaced with a new battery module2, since it is only necessary to reset the identifying information for the new battery module2or to reset the identifying information for the subsequent battery module2-5in addition to the identifying information for the new battery module2, the identifying information may be reset in an easier way in comparison with the case of resetting the identifying information for all the battery modules2-1to2-5after replacement of the battery module2-4.

FIG. 5is a flowchart illustrating operations of the control unit3for confirming the number of battery modules2. Note that, as described above, it is assumed that when the control unit3receives identifying information that has been transmitted from each of the battery modules2-1to2-5, the control unit3causes the storage unit17to store therein the identifying information.

For example, when a time specified in advance has come or when an instruction to confirm the number of battery modules2has been input from outside, the control unit3sets as the number of battery modules2the number of pieces of identifying information that have been stored in the storage unit17(S51), and causes the storage unit17to store therein the number of battery modules2(S52).

Note that the control unit3may set as the number of monitoring units10the number of pieces of identifying information that have been stored in the storage unit17.

In addition, the control unit3may obtain the number of battery modules2by obtaining the number of monitoring units10and thereafter dividing the number of monitoring units10by the number of monitoring units10that are provided in each battery module2. In this case, even when a plurality of monitoring units10are provided in one battery module2, the number of battery modules2may be obtained.

Consequently, even when the number of battery modules2or the number of monitoring units10is changed in order to increase or decrease the overall capacity of the batteries5that are connected in parallel, the control unit3may grasp the number of battery modules2or the number of monitoring units10. Thus, it is not necessary to change constants of the program according to the change in the number of battery modules2or the number of monitoring units10nor is it necessary to prepare another program. Therefore, it is possible to suppress an increase in management cost and an increase in manufacturing cost.

EXPLANATION OF THE CODES