JP7192614B2 - POWER STORAGE DEVICE AND MANAGEMENT METHOD OF POWER STORAGE DEVICE - Google Patents

Description

The present invention relates to a power storage device and a management method of the power storage device.

In recent years, studies have been made to replace low-capacity batteries such as lead-acid batteries with high-capacity batteries such as lithium-ion batteries. For example, lead-acid batteries are generally used as power storage devices used to start engines in motorcycles, but Patent Document 1 discloses that power storage devices equipped with power storage elements such as lithium-ion secondary batteries are applied to motorcycles. Are listed.

Japanese Patent Application Laid-Open No. 2019-3846

When replacing a power storage device used in a certain device with another type of power storage device, it is desirable that the other type of power storage device can be applied without changing the design of the device. For example, when a lead-acid battery of a motorcycle is replaced with an electricity storage device having an electricity storage element such as a lithium-ion battery, so-called retrofitting is required in which the electricity storage device can be applied without changing the design of the motorcycle.

Some power storage devices including power storage elements such as lithium ion batteries do not have a function of communicating with an external device. Conventionally, studies have been made on problems when a power storage device used in a certain device is replaced with another type of power storage device that does not have a function of communicating with an external device without changing the design of the device. was not

In this specification, when a power storage device used in a certain device is replaced with another power storage device that does not have a function of communicating with an external device without changing the design of the device, the other power storage device Disclosed is a technique for reducing frequent foreseeable overcharging of a storage element included in a power storage device while suppressing an increase in the size of the power storage device that accompanies an increase in the output of an equalization circuit.

A power storage device having no function of communicating with a charger, comprising a plurality of power storage elements, a circuit breaker connected in series with the plurality of power storage elements, and equalization for equalizing the voltages of the plurality of power storage elements. and a management unit, wherein the management unit equalizes the voltage of each storage element by the equalization circuit when the circuit breaker is off, and after equalizing the voltage of each storage element, the Turn on the circuit breaker.

When a power storage device used in a certain device is replaced with another power storage device that does not have a function to communicate with an external device without changing the design of the device, the power storage device provided by the other power storage device Frequent overcharging of the element can be foreseen, while suppressing an increase in size of the power storage device due to an increase in the output of the equalization circuit.

motorcycle side view Vehicle system block diagram Battery exploded perspective view Plan view of secondary battery Sectional view of AA line of FIG. Battery block diagram Graph showing relationship between state of charge and open circuit voltage Flowchart of charge control processing A graph showing when to start the equalization process Schematic diagram showing equalization processing Graph showing the state where the voltage of one of the secondary batteries (cells) rises above the threshold at which overcharging is foreseen A graph showing the voltage of the secondary battery when the voltage of all secondary batteries (cells) is equalized and charging is completed. Schematic diagram showing a state in which equalization processing is being performed with the circuit breaker on Schematic diagram showing a state in which equalization processing is being performed with the circuit breaker turned off Schematic diagram showing a state in which equalization processing is completed and charging is restarted Graph showing, as a comparative example, a case where a power storage device in which four secondary batteries are connected in series is charged with a lead-acid battery charger while only the power storage element 1 is in an uneven state.

(Outline of this embodiment)
A power storage device having no function of communicating with a charger, comprising a plurality of power storage elements, a circuit breaker connected in series with the plurality of power storage elements, and equalization for equalizing the voltages of the plurality of power storage elements. and a management unit, wherein the management unit equalizes the voltage of each storage element by the equalization circuit when the circuit breaker is off (open, open), and equalizes the voltage of each storage element. After equalization, turn on (close, close) the circuit breaker.

For example, consider a case where a lead-acid battery used to start an engine of a motorcycle is replaced with a power storage device having a power storage element such as a lithium-ion battery. Lead-acid batteries used in motorcycles are generally rated at 12V [volts] and are float-charged at 15V. Float charging is a charging method that maintains full charge by continuously applying a constant voltage. When the lead-acid battery is float-charged at 15V, constant-current charging is performed until the voltage of the lead-acid battery reaches 15V, and constant-voltage charging is performed at 15V when the voltage rises to 15V.
On the other hand, a power storage device including a power storage element such as a lithium ion battery is generally charged at a voltage lower than 15V, given that the power storage device has a rating of 12V. Assume that the voltage of a storage element such as a lithium-ion battery is 3V, and that the storage device has four such storage elements connected in series. Assume that the voltage at which overcharging of the storage element is predicted (the voltage at which overcharging is approaching, although overcharging has not yet occurred) is 4V. In this case, assuming that the voltage for charging the power storage device is 14V (a voltage lower than 15V), the voltage of each power storage element when charging is completed is ideally 3.5V, and all power storage elements are 4V. does not become
However, in reality, the voltage does not always reach 3.5 V because there is variation in the voltage among the storage elements. However, since there is a margin of 0.5V between 3.5V and 4V, it is unlikely that the voltage of any one of the storage elements will exceed 4V even if the voltage varies somewhat among the storage elements.
When a power storage device including a power storage element such as a lithium ion battery described above is applied to a motorcycle without changing the design of the motorcycle, the power storage device is charged at 15V. In this case, the voltage of each storage element is ideally 3.75 V when charging is completed. Since the difference between 3.75V and 4V is only 0.25V, as shown in FIG. 11, even a slight variation in voltage may cause the voltage of any storage element to exceed 4V.
In float charging, charging occurs as soon as the voltage drops, so overcharging of the storage element is frequently foreseen if any storage element exceeds 4V due to a slight voltage variation. Therefore, the circuit breaker is frequently turned on and off to prevent overcharging, increasing the possibility of breakage of the circuit breaker.
It is also conceivable to suppress the variation by equalizing the voltage of each storage element by an equalization circuit in parallel with charging. However, when miniaturization and cost reduction of the power storage device are required, the equalization circuit is also small, and it is difficult to mount a large resistive load and accompanying heat dissipation components. In other words, it is difficult to suppress variations by increasing the output by increasing the size of the equalization circuit. For example, if the charging current is 30A at maximum, the current flowing through the small equalization circuit is about 36mA. For this reason, the discharge cannot catch up, and it is difficult to equalize the voltages before any of the storage elements becomes overcharged.
If the power storage device has a function of communicating with an ECU (Engine Control Unit) of a motorcycle, the management section of the power storage device can request the ECU to lower the charging voltage. However, in the case of a power storage device that does not have a function of communicating with the ECU, it is not possible to request that the charging voltage be lowered.
According to the power storage device, the equalization circuit equalizes the voltage of each power storage element while the circuit breaker is off. Therefore, it is not necessary to increase the size of the equalization circuit.
According to the power storage device described above, the circuit breaker is turned on after equalizing the voltages of the power storage elements, so that the power storage elements are charged by the charger. Since the voltages of the storage elements are equalized, there is a high possibility that the voltages of the storage elements will be less than the voltage at which overcharging is foreseen when charging is terminated thereafter.
Therefore, according to the power storage device described above, a power storage device used in a certain device can be replaced with another power storage device that does not have a function of communicating with an external device (the power storage device described above) without changing the design of the device. ), frequent foreseeable overcharging of the storage element included in the other storage device can be reduced while suppressing increase in size of the storage device due to higher output of the equalization circuit. In other words, according to the power storage device described above, it is possible to reduce the possibility that the circuit breaker will fail due to frequent ON/OFF of the circuit breaker while suppressing an increase in the size of the power storage device.

The management unit may turn off the circuit breaker if overcharging of any of the storage elements is foreseen while the plurality of storage elements are being charged by the charger.

It is possible to turn off the circuit breaker before overcharging of any of the storage elements is foreseen, but in that case the time from the completion of equalization to the end of charging will be longer. variation may occur again.
According to the power storage device described above, since the circuit breaker is turned off when overcharging of any of the power storage elements is foreseen, the time from the completion of equalization to the end of charging is short. Therefore, it is possible to reduce the possibility that variations will occur again during that time.

The circuit breaker includes a discharge circuit breaker in which a rectifying element and a switch that allow current to flow only in the charging direction of the storage element are connected in parallel, and a rectifying element that allows current to flow only in the discharging direction and a switch that are connected in parallel. A charging circuit breaker connected thereto is provided in series, and the control unit predicts overcharging of any one of the storage elements when the plurality of storage elements are being charged by the charger. and the switch of the charging circuit breaker may be turned off while the switch of the discharging circuit breaker remains on.

According to the power storage device described above, even if the switch of the charging circuit breaker is turned off, the switch of the discharging circuit breaker remains on, so discharging is permitted. Therefore, it is possible to suppress a so-called power failure in which power is not supplied to an external device.

The control unit starts equalization by the equalization circuit when the state of charge (SOC: State Of Charge) of the storage element rises to a predetermined value smaller than a threshold at which overcharging of the storage element is predicted. good too.

According to the power storage device described above, since equalization is started before overcharging of the power storage elements is foreseen, there is a high possibility that charging will end without foreseeing overcharge of any of the power storage elements.

The storage element may have a plateau region in which a change in open circuit voltage (OCV) with respect to a change in state of charge (SOC) is small.

As shown in FIG. 7, some energy storage elements have a plateau region in which the change in OCV with respect to the change in SOC is small (for example, an iron-based energy storage element in which the positive electrode active material contains iron). . Specifically, the plateau region is, for example, a region in which the amount of change in OCV with respect to the amount of change in SOC is 2 [mV/%] or less.
In the case of a storage element having a plateau region, the OCV is almost constant when the SOC is in the plateau region, so it is difficult to detect the voltage difference of the storage element from the SOC and start equalization. Therefore, the voltage difference is detected and equalization is started after passing through the plateau region (section indicated by circle 40 in FIG. 9A).
However, as can be seen from FIG. 7, there is a steep region where the OCV sharply rises to the right of the plateau region. Since the steep region exists at the end of charging, the time from when the SOC exits the plateau region to when one of the storage elements becomes overcharged is short. For this reason, the equalization was delayed, and it was difficult to end the equalization before any of the storage elements became overcharged.
According to the power storage device described above, equalization is performed while the circuit breaker is off. Therefore, even if equalization is started immediately before overcharging occurs, equalization can be performed over time. Therefore, even if the power storage device has a plateau region, frequent overcharging of the power storage device can be foreseen while suppressing an increase in the size of the power storage device. Therefore, it is particularly useful in the case of an electric storage device having a plateau region.

The storage element may be a lithium-ion battery, and the charger may be a lead-acid battery charger.

As described above, chargers for charging lead-acid batteries generally charge at a higher voltage than chargers for charging lithium-ion batteries. According to the power storage device described above, when a lead-acid battery charger is used to charge a lithium-ion battery, frequent overcharging of the lithium-ion battery can be foreseen while suppressing an increase in the size of the power storage device.

The invention disclosed in this specification can be realized in various forms such as an apparatus, a method, a computer program for realizing the functions of these apparatuses or methods, a recording medium recording the computer program, and the like.

<Embodiment 1>
Embodiment 1 will be described with reference to FIGS. 1 to 10. FIG.

As shown in FIG. 1 , a battery 50 (an example of a power storage device) according to Embodiment 1 is a battery for a motorcycle mounted on a motorcycle 10 . Battery 50 is rated at 12V.

As shown in FIG. 2, the battery 50 is connected to a starter 10A, an alternator 10B (an example of a charger), and accessories 10C (headlight, air conditioner, audio, etc.) mounted on the motorcycle 10. The battery 50 is an engine starting battery that supplies electric power to the starter 10A to start the engine. Battery 50 is charged by alternator 10B during engine operation. Alternator 10B is designed for charging lead-acid batteries and float charges battery 50 at 15V.

While the engine of the motorcycle 10 is operating, electric power is supplied from the alternator 10B to the accessories 10C. Therefore, the battery 50 does not supply power to the accessories 10C while the engine is operating, but supplies power to the accessories 10C when the accessories 10C are used while the engine is stopped.
Generally, a motorcycle battery does not have a function of communicating with the ECU of the motorcycle 10 . The battery 50 for a two-wheeled vehicle according to Embodiment 1 also does not have the function of communicating with the ECU.

(1) Configuration of Battery As shown in FIG.
The container 71 includes a main body 73 and a lid 74 made of synthetic resin material. The main body 73 has a cylindrical shape with a bottom. The main body 73 has a bottom portion 75 and four side portions 76 . An upper opening 77 is formed at the upper end portion by the four side portions 76 .

The housing body 71 houses the assembled battery 60 and the circuit board unit 65 . The assembled battery 60 has 12 secondary batteries 62 (an example of power storage elements). The secondary battery 62 is, for example, an iron-based lithium ion battery containing iron in the positive electrode active material. The 12 secondary batteries 62 are connected in 3-parallel and 4-series. In the following description, the secondary battery 62 may also be called a cell.
Circuit board unit 65 includes circuit board 100 and electronic components mounted on circuit board 100 , and is arranged above assembled battery 60 .

The lid 74 closes the upper opening 77 of the main body 73 . An outer peripheral wall 78 is provided around the lid body 74 . The lid 74 has a projecting portion 79 that is substantially T-shaped in plan view. A positive electrode external terminal 51 is fixed to one corner of the front portion of the lid 74 , and a negative electrode external terminal 52 is fixed to the other corner.

As shown in FIGS. 4 and 5, the secondary battery 62 includes an electrode assembly 83 and a non-aqueous electrolyte housed in a rectangular parallelepiped case 82 . The case 82 has a case main body 84 and a lid 85 that closes the upper opening.
The electrode body 83, although not shown in detail, is provided between a negative electrode element in which an active material is applied to a base material made of copper foil and a positive electrode element in which an active material is applied to a base material made of aluminum foil. A separator made of a resin film is arranged. Each of these is strip-shaped, and is wound flat so as to be accommodated in the case main body 84 with the negative electrode element and the positive electrode element shifted to opposite sides in the width direction with respect to the separator. .

A positive terminal 87 is connected to the positive element through a positive current collector 86, and a negative terminal 89 is connected to the negative element through a negative current collector 88, respectively. The positive electrode current collector 86 and the negative electrode current collector 88 are composed of a flat plate-shaped pedestal portion 90 and leg portions 91 extending from the pedestal portion 90 . A through hole is formed in the base portion 90 . Leg 91 is connected to the positive or negative element. The positive electrode terminal 87 and the negative electrode terminal 89 are composed of a terminal main body portion 92 and a shaft portion 93 projecting downward from the center portion of the lower surface thereof. Among them, the terminal body portion 92 and the shaft portion 93 of the positive electrode terminal 87 are integrally formed of aluminum (single material). In the negative electrode terminal 89, the terminal body portion 92 is made of aluminum and the shaft portion 93 is made of copper, and these are assembled together. The terminal body portions 92 of the positive electrode terminal 87 and the negative electrode terminal 89 are arranged at both ends of the lid 85 via gaskets 94 made of an insulating material and are exposed to the outside through the gaskets 94 .

The lid 85 has a pressure relief valve 95 . Pressure relief valve 95 is located between positive terminal 87 and negative terminal 89 as shown in FIG. The pressure release valve 95 opens to reduce the internal pressure of the case 82 when the internal pressure of the case 82 exceeds the limit value.

(2) Electrical Configuration of Battery As shown in FIG. 6 , the battery 50 includes an assembled battery 60 and a BMU 101 (Battery Management Unit) that manages the assembled battery 60 . BMU 101 is an example of a management device.

As described above, the assembled battery 60 is composed of 12 secondary batteries 62, which are connected in 3-parallel and 4-series. In FIG. 6, three secondary batteries 62 connected in parallel are represented by one battery symbol.
The power line 70</b>P is a power line that connects the positive external terminal 51 and the positive electrode of the assembled battery 60 . The power line 70N is a power line that connects the negative external terminal 52 and the negative electrode of the assembled battery 60 . The negative electrode of the assembled battery 60 is connected to the signal ground G1. The assembled battery 60 uses the signal ground G1 as a reference potential. The negative external terminal 52 is connected to the body ground G2. A body ground G2 is the body of the motorcycle 10 . A body ground G2 is a reference potential of the motorcycle 10 .

BMU 101 comprises current sensor 53 , voltage sensor 110 , circuit breaker 55 , four equalization circuits 25 and manager 130 . The assembled battery 60, current sensor 53 and circuit breaker 55 are connected in series via power lines 70P and 70N. The circuit breaker 55, current sensor, and management unit 130 are mounted on the circuit board 100, and the signal ground G1 of the circuit board 100 is used as a reference potential (operation reference).

The current sensor 53 is positioned at the negative electrode of the assembled battery 60 and provided on the power line 70N on the negative electrode side. The current sensor 53 detects the current value and direction (charging direction/discharging direction) of the current flowing through the assembled battery 60 .
A voltage sensor 110 detects the voltage V of each secondary battery 62 and the total voltage of the assembled battery 60 . The total voltage of the assembled battery 60 is the total voltage of the four secondary batteries 62 .

The circuit breaker 55 is positioned at the negative electrode of the assembled battery 60 and provided on the negative power line 70N. The circuit breaker 55 has a charging FET 55A (an example of a charging circuit breaker) and a discharging FET 55B (an example of a discharging circuit breaker). The charging FET 55A and the discharging FET 55B are power semiconductor switches, more specifically N-channel field effect transistors (FETs). The source S of the charge FET 55A and discharge FET 55B is a reference terminal. Gates G of the charging FET 55A and the discharging FET 55B are control terminals. Drains D of the charge FET 55A and the discharge FET 55B are connection terminals.

The source S of the charging FET 55A is connected to the negative electrode of the assembled battery 60 . The discharge FET 55B has the source S connected to the negative external terminal 52 . The charging FET 55A and the discharging FET 55B are connected back-to-back by connecting the drains D to each other.
The charging FET 55A has a parasitic diode 56A (an example of a rectifying element that allows current to flow only in the discharging direction). The forward direction of the parasitic diode 56A is the same as the discharging direction. The discharging FET 55B has a parasitic diode 56B (an example of a rectifying element that allows current to flow only in the charging direction). The forward direction of the parasitic diode 56B is the same as the charging direction.

Since the source S of the discharge FET 55B is connected to the negative external terminal 52, the body ground G2 is the reference potential. The source S of the charging FET 55A is connected to the negative electrode of the assembled battery 60 . Since the negative electrode of the assembled battery 60 is connected to the signal ground G1 of the circuit board 100, the signal ground G1 is the reference potential of the charging FET 55A.
The charging FET 55A is turned on by applying an H level voltage to the gate G, and turned off by applying an L level voltage to the gate G. The same applies to the discharge FET 55B.

The four equalization circuits 25 are for equalizing the voltages of the secondary batteries 62, and are connected in parallel to different secondary batteries 62, respectively. Each equalization circuit 25 has a discharge resistor 25A and a switch 25B such as an FET or a relay.

The management unit 130 has a CPU 131 , a ROM 132 and a RAM 133 . Management unit 130 manages battery 50 based on the outputs of voltage sensor 110 , current sensor 53 , and temperature sensor 111 . The management unit 130 normally applies an H level voltage to the gate G of the charging FET 55A and the gate G of the discharging FET 55B to turn on the charging FET 55A and the discharging FET 55B. When both the charging FET 55A and the discharging FET 55B are on, the assembled battery 60 can be both charged and discharged.

(3) Processing Executed by Management Unit Of the processing executed by management unit 130, SOC estimation processing and charging control processing will be described.

(3-1) SOC estimation processing The SOC estimation processing is processing for estimating the state of charge of the assembled battery 60 by the current integration method. In the current integration method, the current sensor 53 measures the charge/discharge current of the assembled battery 60 at predetermined time intervals to measure the amount of power flowing in and out of the assembled battery 60, and the SOC is estimated by adjusting this from the initial capacity. It is a way to

The current integration method has the advantage of being able to estimate the SOC even while the assembled battery 60 is in use. have a nature. Therefore, management unit 130 may reset the SOC estimated by the current integration method based on the open circuit voltage (OCV) of assembled battery 60 .

Specifically, as shown in FIG. 7, since there is a relatively accurate correlation between OCV and SOC, SOC is estimated from OCV, and SOC estimated by the current integration method is estimated from OCV. It may be reset at the SOC that is set.
OCV is not limited to the open circuit voltage. For example, OCV may be the voltage when the current value of the current flowing through the secondary battery 62 is less than a minute reference value.

(3-2) Charging Control Processing The charging control processing executed by management unit 130 will be described with reference to FIGS. 8 to 10. FIG. This process is executed each time the SOC of the assembled battery 60 is estimated by the SOC estimation process.
As described above, the battery 50 includes 12 secondary batteries 62, but for ease of understanding, a case where four 3V secondary batteries 62 are connected in series will be described as an example. As described above, the alternator 10B charges the battery 50 at 15V, so when charging is completed, the voltage of each secondary battery 62 ideally becomes 3.75V (=15V/4).

In S101, the management unit 130 determines whether the SOC of the assembled battery 60 is equal to or greater than a predetermined value S2 (eg, 90%) smaller than the threshold S1 (eg, 95%) at which overcharging is predicted (FIG. 9A). ). The management unit 130 proceeds to S102 when the SOC is equal to or greater than the predetermined value S2, and terminates this process when the SOC is less than the predetermined value S2.

In S102, the management unit 130 starts the equalization process with the charging FET 55A turned on (FIGS. 9B and 10A). For convenience, the four secondary batteries 62 are indicated by cells 1 to 4 in FIG. 9B.
In the equalization process, the voltage of the secondary battery 62 with the lowest voltage among the four secondary batteries 62 is used as the reference voltage, and the voltage of the other secondary batteries 62 is adjusted until the voltage of the other secondary batteries 62 matches the reference voltage. is discharged by the discharge resistor 25A to equalize the voltage of each secondary battery 62. FIG.

In S103, the management unit 130 determines whether or not the voltage of any of the secondary batteries 62 is equal to or higher than a threshold voltage (for example, 4 V) at which overcharging is foreseen (FIG. 9C). If the voltage of any of the secondary batteries 62 is equal to or higher than the threshold voltage, the management unit 130 proceeds to S104, and if the voltage of any of the secondary batteries 62 is less than the threshold voltage, executes S103 again after a predetermined time has elapsed. do.

In S104, the management unit 130 turns off the charging FET 55A while keeping the discharging FET 55B on (FIG. 10B). When the charging FET 55A is turned off, charging is interrupted, but discharging is allowed because the discharging FET 55B is kept on.
In S105, the management unit 130 determines whether or not the equalization process started in S102 has ended (whether or not the voltages of the secondary batteries 62 have been equalized). When finished, the process proceeds to S107.

In S106, the management unit 130 determines whether or not the current in the discharge direction is detected by the current sensor. If the current in the discharge direction is detected, the process proceeds to S107.
In S107, the management unit 130 turns on the charging FET 55A (FIG. 10C). As a result, charging of each secondary battery 62 is restarted.

(4) Effect of the Embodiment According to the battery 50, the voltage of each secondary battery 62 is equalized by the equalization circuit 25 while the charge FET 55A is off (FIG. 10B), so that equalization can be achieved over time. Therefore, it is not necessary to increase the size of the equalization circuit 25 .
According to the battery 50, after equalizing the voltage of each secondary battery 62, the charging FET 55A is turned on (FIG. 10C), so charging of the secondary battery 62 by the alternator 10B is resumed. Since the voltage of each secondary battery 62 is equalized, there is a possibility that the voltage of each secondary battery 62 will be less than the voltage (4 V) at which overcharging is foreseen when charging is terminated thereafter. higher (Fig. 9D).
Therefore, according to the battery 50, when the lead-acid battery used in the motorcycle 10 is replaced with the battery 50 (a power storage device having no function of communicating with an external device) without changing the design of the motorcycle 10, , frequent foreseeable overcharging of the secondary battery 62 can be reduced while suppressing an increase in the size of the battery 50 due to an increase in the output of the equalization circuit 25 . In other words, according to the battery 50, the possibility of the charging FET 55A failing due to frequent ON/OFF of the charging FET 55A can be reduced while suppressing an increase in the size of the battery 50.

According to the battery 50, when overcharging of any of the secondary batteries 62 is foreseen while the plurality of secondary batteries 62 are being charged by the alternator 10B, the charging FET 55A is turned off, so equalization is completed. It takes a short time to finish charging. Therefore, it is possible to reduce the possibility that variations will occur again during that time.

According to the battery 50, even if the charging FET 55A is turned off, the discharging FET 55B is kept on, so discharging is permitted. Therefore, it is possible to suppress a so-called power failure in which power is not supplied to the starter 10A and the auxiliary equipment 10C.

According to the battery 50, since equalization is started before overcharging of the secondary batteries 62 is foreseen, there is a high possibility that charging of any of the secondary batteries 62 will be completed without overcharging being foreseen.

According to the battery 50, the charge FET 55A is equalized in the OFF state, so even if the equalization is started just before overcharging, the equalization can take time. Therefore, even if the secondary battery 62 has a plateau region, the possibility of the secondary battery 62 being overcharged can be reduced while suppressing an increase in the size of the battery 50 . Therefore, it is particularly useful for the secondary battery 62 having a plateau region.

According to the battery 50, the secondary battery 62 is a lithium-ion battery, and the alternator 10B is a charger for lead-acid batteries. According to the battery 50 , frequent overcharging of the lithium ion battery can be foreseen when the lithium ion battery is charged by a lead-acid battery charger, while suppressing an increase in the size of the battery 50 .

According to the battery 50, when a discharging current is detected after the charging FET 55A is turned off, the charging FET 55A is turned on even before the voltages of the secondary batteries 62 are equalized. , the failure of the parasitic diode 56A can be suppressed even if a large discharge current flows before the equalization process ends.

<Other embodiments>
The technology disclosed in this specification is not limited to the embodiments described in the above description and drawings, and the following embodiments are also included in the technical scope disclosed in this specification.

(1) In the above embodiment, the alternator 10B of the motorcycle 10 is used as the charger, but the charger may be a charger different from the motorcycle 10.

(2) In the above embodiment, an iron-based secondary battery 62 was described as an example of the secondary battery 62. It may be a battery.

(3) In the above embodiment, the secondary battery 62 having a plateau region was described as an example, but the secondary battery 62 is not limited to one having a plateau region.

(4) In the above embodiment, when the SOC of the assembled battery 60 is equal to or greater than the predetermined value S2 which is smaller than the threshold value S1 at which overcharging is foreseen, the equalization process is performed even if overcharging of the assembled battery 60 is not foreseen. Start (S101 and S102). On the other hand, if the SOC of the assembled battery 60 is smaller than the threshold value S1, the equalization process is not started, and if overcharging of any of the secondary batteries 62 is predicted in S103, the equalization process is started in S105. may

(5) In the above embodiment, the charging FET 55A is turned off while the discharging FET 55B is kept on in S104. may not have

(6) In the above embodiment, the charging FET 55A was used as the charging circuit breaker, but the charging circuit breaker may have a rectifying element and a relay connected in parallel. The same applies to discharge circuit breakers.

(7) In the above embodiment, the circuit breaker includes the charge FET 55A and the discharge FET 55B, but the circuit breaker may be a single relay.

(8) In the above embodiment, it is determined in S106 whether or not a current in the discharge direction has been detected. If so, the process may proceed to S107.

(9) In the above embodiments, a lithium ion battery was used as an example of the storage element, but the storage element is not limited to this. For example, the storage element may be a capacitor that involves an electrochemical reaction.
(10) In the above embodiment, the battery for starting the engine of the motorcycle 10 has been described as an example of the battery 50, but the application of the battery 50 is not limited to this. For example, the battery 50 may be a battery for starting the engine of a four-wheeled vehicle, or may be a battery for auxiliary equipment that is mounted on an electric vehicle or a plug-in hybrid vehicle and supplies power to auxiliary equipment. . The battery 50 may be a battery used in an uninterruptible power supply (UPS).

10 Motorcycle 10B Alternator (an example of a charger)
25 equalization circuit 50 battery (an example of a power storage device)
55 Breaker 55A Charging FET (charging breaker, example of switch)
55B Discharge FET (an example of a discharge circuit breaker or switch)
56A Parasitic diode (an example of a rectifying element)
56B Parasitic diode (an example of a rectifying element)
62 secondary battery (an example of a storage element)
130 Administration Department

Claims (6)

A power storage device that does not have a function of communicating with a charger,
a plurality of power storage elements;
a circuit breaker connected in series with the plurality of storage elements;
an equalization circuit that equalizes the voltages of the plurality of storage elements;
management department and
with
The management unit causes the equalization circuit to start equalizing the voltage of each of the storage elements in a state in which the circuit breaker is turned on and the plurality of storage elements are being charged by the charger ,
If overcharging of any of the storage elements is foreseen during equalization, the circuit breaker is turned off to continue equalization;
An electricity storage device that turns on the circuit breaker after equalizing the voltage of each of the electricity storage elements. The power storage device according to claim 1 ,
The circuit breaker includes a discharge circuit breaker in which a rectifying element and a switch that allow current to flow only in the charging direction of the storage element are connected in parallel, and a rectifying element that allows current to flow only in the discharging direction and a switch that are connected in parallel. The connected charging circuit breaker is provided in series,
The control unit turns off the switch of the charging breaker when overcharging of any of the storage elements is foreseen while the plurality of storage elements are being charged by the charger, A power storage device that keeps the switch of the circuit breaker on. The power storage device according to claim 1 or claim 2 ,
The power storage device, wherein the control unit starts equalization by the equalization circuit when the state of charge of the power storage element rises to a predetermined value or more that is smaller than a threshold value at which overcharging of the power storage element is predicted. The power storage device according to any one of claims 1 to 3 ,
The power storage device, wherein the power storage element has a plateau region in which a change in open-circuit voltage with respect to a change in state of charge is small. The power storage device according to any one of claims 1 to 4 ,
The power storage device, wherein the power storage element is a lithium-ion battery, and the charger is a lead-acid battery charger. A method for managing a power storage device that does not have a function of communicating with a charger,
In a state in which a circuit breaker connected in series with a plurality of storage elements provided in the power storage device is turned on and the plurality of storage elements are charged by the charger, the voltage of each storage element is adjusted by an equalization circuit. When equalization is started and overcharging of any of the storage elements is foreseen during equalization, the circuit breaker is turned off to continue equalization and equalize the voltage of each storage element. a step of turning on said circuit breaker after it has been turned on.

Images