JP7653333B2 - Secondary battery control device and control method, and rechargeable vacuum cleaner equipped with said control device - Google Patents

Description

The present invention relates to a control device and control method for a secondary battery, and a rechargeable vacuum cleaner equipped with the control device.

The development of devices that use secondary batteries is progressing in various fields. Secondary batteries deteriorate with repeated charge and discharge cycles, so it is necessary to calculate the degree of deterioration and provide appropriate control, and in practice, they must be used in combination with a control device.

Patent Document 1 discloses that the electric vehicle accumulates usage history data of a secondary battery installed as its power source in a memory unit, and controls the charging and discharging of the secondary battery so as to maintain the SOC of the secondary battery within a control range using a control device; the electric vehicle is capable of communicating with an external data center; the data center is configured to receive information about the on-board secondary batteries from multiple vehicles having on-board secondary batteries and to calculate a standard degree of deterioration of the secondary battery over time using the information from the multiple vehicles; the control device of the electric vehicle obtains the standard degree of deterioration from the data center, and further, when the degree of deterioration estimated from the usage history data of the electric vehicle is lower than the standard degree of deterioration, the upper limit of the SOC control range is raised. Patent Document 1 also discloses that the controller 30 has a control unit 31 and a memory unit 32, that the controller 30 is capable of diagnosing the deterioration of the vehicle's battery using battery usage history data from the start of use of the main battery 10 (when the battery was new) stored in the memory unit 32, and that when the controller 30 determines that the deterioration level of the vehicle's battery is lower than the standard, it notifies the user that the deterioration level of the vehicle's battery is low and therefore the upper limit SOC can be increased, and outputs a message to confirm with the user whether or not to allow the increase in the upper limit SOC.

Patent Document 2 discloses that in a life-control type secondary battery system, at least one of the current, voltage, and temperature of a secondary battery group is accumulated in a time series, and analyzed; information identifying the operating condition parameters and a relational equation between the secondary battery voltage and the reference electrode, the positive electrode voltage and positive electrode capacity, and the negative electrode voltage and negative electrode capacity, are used to calculate internal deterioration state parameters from a number of open circuit voltages under no load and the battery surface temperature or internal temperature; a deterioration database is referenced, and the relationship between the internal deterioration state parameters and the battery operating condition parameters is used to change the battery operating conditions; the current capacity is calculated from the current value parameters, and the battery deterioration level SOH is calculated by comparing it with the initial value.

JP 2018-029430 A JP 2017-069011 A

To improve the accuracy of estimating the deterioration level of a secondary battery, it is usually necessary to accumulate data on the voltage, current, temperature, etc. of the secondary battery over a long period of time, and to calculate the state of charge (SOC) etc. using this data. For this purpose, it is difficult for the memory and arithmetic unit of a device that uses a secondary battery to perform calculations at a sufficient calculation speed and with high accuracy, and providing hardware for this purpose increases the size and cost of the device, making it impractical as a product.

In particular, in the field of home appliances, there is a limit to the computing power of the battery management system (BMS) that processes data, so an algorithm with a low computational load is required to control the secondary battery. Also, when using devices at home, it can sometimes be difficult to communicate with the outside world.

The technology described in Patent Document 1 assumes communication with an external data center, so there is little need to reduce the computational load.

The technology described in Patent Document 2 is based on a battery storage system that is based on the need to mitigate fluctuations in the amount of power generated by large secondary batteries, wind power generation, solar power generation, etc., which are used as power sources for hybrid electric vehicles and electric vehicles, and similarly has little need to reduce the calculation load.

In addition, when it comes to home appliances, the ease of use for the user must also be taken into consideration. For example, in the case of rechargeable vacuum cleaners, some users tend to use high output, while others do not place importance on high output and place importance on a long usable time. Since usage methods differ from user to user in this way, controlling the deterioration factors of secondary batteries in the same way may result in dissatisfaction with usability. For this reason, deterioration suppression control that is tailored to the user's usage tendencies is necessary.

The objective of the present invention is to reduce the computational load required to suppress deterioration of secondary batteries, and to suppress deterioration in accordance with the user's usage method.

The control device for a secondary battery of the present invention has a deterioration level detection unit that calculates a detection value of the deterioration level of the secondary battery, a memory unit that stores historical information on the deterioration factors of the secondary battery and data used to calculate a reference value of the deterioration level of the secondary battery, and a deterioration determination unit that determines whether the detection value is greater than or equal to the reference value for the deterioration level of the secondary battery, and the deterioration determination unit is capable of selecting deterioration suppression control when the detection value is equal to or less than the reference value.

The present invention reduces the computational load required to suppress deterioration of a secondary battery, and can suppress deterioration in accordance with the user's usage method.

1 is a configuration diagram showing a control device for a secondary battery according to an embodiment; 4 is a flowchart showing a determination method in a deterioration determination unit 240 of FIG. 1 . 3 is a flowchart showing a method for suppressing deterioration of a battery in step s107 of FIG. 2. 4 is a graph showing an overview of degradation suppression control in the control device for a secondary battery according to an embodiment. 1 is an external perspective view showing an example of a vacuum cleaner incorporating a control device for a secondary battery according to an embodiment;

Embodiments of the present disclosure will be described below with reference to the drawings. Note that the secondary battery control device and control method of the present disclosure can be applied to any product or device, but the following description will be given using a household rechargeable vacuum cleaner as an example.

Figure 1 is a diagram showing the configuration of a secondary battery control device according to an embodiment.

In this figure, the control device 200 includes an SOC/SOH detection unit 210 (deterioration detection unit), an operating information collection and analysis unit 220, a time and storage temperature management unit 230, a deterioration prediction unit 235, and a deterioration determination unit 240. The control device 200 is connected to a battery 100 (secondary battery) installed in the vacuum cleaner, a memory unit 300, and a vacuum cleaner control unit 400. The control device 200 is also connected to a current time measurement unit 500 (clock) that measures the actual time, a temperature sensor 600 that measures the ambient temperature, and a user input unit 700 such as a switch. The control device 200 is also connected to a display unit 260 that notifies the user of information about the battery, etc. The memory unit 300 may be configured to be built into the control device 200.

The SOC/SOH detection unit 210 detects the state of charge (SOC) and state of health (SOH) of the battery from the battery voltage (V), current (I) and surface temperature (T). The SOH may be either the state of health quality (SOHQ) or the state of health resistance (SOHR). In this embodiment, the explanation will be given using SOHQ.

The vacuum cleaner control unit 400 is composed of a computing device that controls the operation of the vacuum cleaner.

Any method may be used to detect the SOC and SOHQ, but the Kalman filter method is preferred because it has a small calculation load and high accuracy. Alternatively, the current integration method may be used.

The detected SOC and SOHQ values are collected by the driving information collection and analysis unit 220 and stored in the memory unit 300. The driving information collection and analysis unit 220 also simultaneously collects information on V, I, and T during charging and discharging for each number of charge/discharge cycles of the battery 100 and stores this in the memory unit 300. Hereinafter, the number of charge/discharge cycles refers to the number of times that charging and discharging are alternately performed. In other words, if charging and discharging are performed once each, the number of charge/discharge cycles is one. If charging and discharging are performed n times each, the number of charge/discharge cycles is n. Hereinafter, the number of charge/discharge cycles is also simply referred to as the "number of cycles."

In this embodiment, the user's usage tendency is determined by analyzing information on V, I, and T for each number of charge/discharge cycles of the battery 100 for controlling the battery 100 used as the power source for the vacuum cleaner. The user's usage tendency serves as a criterion for selecting deterioration factors when applying the deterioration prediction formula described below.

The arithmetic units and memory units built into home appliances such as household vacuum cleaners are usually small, and it is not possible to store data from all charge/discharge cycles in the memory unit, making large-scale calculations difficult. For this reason, a method of averaging past data and overwriting it can also be used in the memory unit.

In the case of vacuum cleaners, for example, users' usage trends can be divided into those who frequently use high power for thorough cleaning with strong suction power, and those who frequently use low power for more restrained cleaning functions, prioritizing long-term use. The definition of high-power users and low-power users can be adjusted according to how the device is used, but the following method can be considered as an example.

(1) The current values during discharge per cycle are averaged to calculate the average discharge current (I _ave,i ), where the subscript i represents the cycle number.

(2) The average discharge current is averaged over a specified number of cycles (n), and the n-cycle average discharge current (I _cy ) is calculated using the following formula:

I _cy = (I _{ave, 1} + I _{ave, 2} +...+I _{ave, n} )/n
The specified number of cycles may be set arbitrarily.

In this case, the determination of whether the user is a high-power user or a low-power user can be made based on a threshold value set for _Icy . The threshold value can be set arbitrarily in accordance with the vacuum cleaner.

It is desirable to store in the memory unit 300 the detected SOC/SOHQ values, the history of battery usage conditions, and the user's usage trends, as well as the shipping time and storage temperature of the battery, and target deterioration curve data.

The shipping time and storage temperature of the battery are input to the time and storage temperature management unit 230 from the current time measurement unit 500 (clock) and temperature sensor 600 provided in the vacuum cleaner or control device 200, and then stored in the memory unit 300.

Here, the target deterioration curve data includes, for example, the correspondence between the number of cycles and the SOHQ value. The reference value of the target deterioration curve data is a value that can be arbitrarily set by the manufacturer.

The deterioration prediction unit 235 calculates the SOHQ using various factors and sends the value to the deterioration determination unit 240.

Figure 2 is a flowchart showing the determination method in the deterioration determination unit 240 of Figure 1.

As shown in FIG. 2, first, the deterioration determination unit 240 determines whether a predetermined number of cycles has elapsed, in other words, whether the number of charge/discharge cycles has reached a predetermined value, based on information from the memory unit 300 (step s101).

When a predetermined number of cycles have elapsed, the degradation determination unit 240 acquires the SOHQ detection value from the memory unit 300 (step s102). Here, the SOHQ detection value is the current actual SOHQ detected.

The deterioration determination unit 240 also acquires the SOHQ reference value calculated by the deterioration prediction unit 235 using a deterioration prediction formula based on the shipping time, storage temperature, number of cycles, and usage condition history stored in the memory unit 300 (step s103).

If the specified cycle has not been completed in step S101, the process ends without proceeding to step S102.

After step s103, the degradation determination unit 240 compares the SOHQ detection value with the SOHQ reference value (step s104).

If the SOHQ detection value > the SOHQ reference value in step s104, it can be assumed that the battery is not deteriorating, so the operation continues until the next specified cycle without performing degradation suppression control (step s105). In this case, the degradation determination unit 240 does not need to send a special command such as output suppression to the vacuum cleaner control unit 400. In this case, the user may be notified that the secondary battery is expected to last a long time.

If the SOHQ detection value is not greater than the SOHQ reference value in step s104, i.e., if the SOHQ detection value is equal to or less than the SOHQ reference value, the user is asked whether or not he/she wishes to perform deterioration suppression control (step s106). In other words, if the SOHQ detection value is equal to or less than the SOHQ reference value, deterioration suppression control can be selected. As a method of asking the user, a signal from the deterioration determination unit 240 may be displayed in text on the display unit 260 of the vacuum cleaner, or the user may be notified by lighting or blinking a light-emitting diode (LED) provided on the vacuum cleaner. The user may also be notified by a sound from a speaker provided on the vacuum cleaner, a vibration of the handle of the vacuum cleaner, etc.

When a user receives a question from the vacuum cleaner, they are likely to make two major choices:

The first option is when you want to use degradation suppression control to extend the battery life. The second option is when you are not too concerned about battery life, you prioritize performance, you want to use the vacuum cleaner at high power, and you are okay with changing the batteries more frequently.

By having the user make a selection based on the question in step S106, the output of the vacuum cleaner is adjusted to meet the user's wishes, which has the effect of increasing user satisfaction.

In step s106, the user can transmit the above selection to the control device 200 using a user input unit 700 (FIG. 1), such as a switch provided on the vacuum cleaner. The user input unit 700 is not limited to a switch, and may be configured, for example, so that the user applies a predetermined vibration or the like to the handle of the vacuum cleaner, causing an acceleration sensor or the like provided on the vacuum cleaner to detect the selection corresponding to the vibration or the like and transmit it to the control device 200. In other words, the user input unit 700 accepts the user's response to a question from the vacuum cleaner as an input.

If the user requests degradation prevention control in step S106, a command is sent to the vacuum cleaner control unit 400 to perform degradation prevention operation (step S107).

If the user does not want degradation suppression control in step s106, the degradation determination unit 240 continues normal operation of the vacuum cleaner without sending a command to the cleaner control unit 400 to suppress output, etc. (step s108). In this case, since degradation suppression operation is not performed, there is a possibility that the battery will deteriorate early. For this reason, when it is determined that the SOHQ calculated by the degradation prediction unit 235 using the degradation prediction formula while taking into account the subsequent battery usage status, etc., will fall to a predetermined value, an early deterioration alert for the battery is displayed on the display unit 260 (step s109). This has the effect of allowing the user to recognize the need to replace the battery early and to prepare a replacement battery in advance.

By comparing the presence or absence of degradation suppression control with the target degradation curve, it is possible to reduce the frequency of application of the degradation prediction formula, which places a heavy burden on calculations. By applying an algorithm that makes such a judgment, it is possible to reduce the calculation load on small computing devices built into home appliances, including vacuum cleaners. In other words, the degradation suppression control of this embodiment can be applied even to devices that only have a small computing device, such as home appliances.

In this embodiment, deterioration suppression control is performed by using a deterioration prediction formula and selecting deterioration factors.

There are various types of deterioration prediction formulas, and there are no particular limitations as long as the prediction accuracy is guaranteed.

Here, the following formulas (1) and (2) are used to predict deterioration. The capacity maintenance rate SOHQ is used to indicate the degree of deterioration.

SOHQ (%) = 100-ΔQ...(1)
ΔQ is the capacity reduction rate (%), and ΔQ is expressed by the following formula (2).

ΔQ=f(a, b, c, d)...(2)
In the formula, a is the upper limit voltage of the battery, b is the charging current, c is the discharging current, and d is the storage temperature of the battery. a, b, c, and d are battery deterioration factors, and from the viewpoint of suppressing battery deterioration, they can also be called "deterioration suppression factors".

Figure 3 is a flowchart showing the method for suppressing battery deterioration in step S107 of Figure 2.

All processing in Figure 3 is performed by the degradation determination unit 240.

First, the operating information of the battery or the vacuum cleaner is obtained from the memory unit 300 (step s301). Then, the deterioration prediction formula is used to calculate the current SOHQ reference value (step s302). Here, in step s302, the calculation is performed using the deterioration factors from the past to the present stored in the memory unit 300.

The SOHQ detection value is compared with the SOHQ reference value, and the next SOHQ target value (future value) is set (step s303). If there is no difference between the SOHQ detection value and the SOHQ target value, the value can be left as is, but if there is a difference, the future target degradation curve is corrected. Specifically, the output is suppressed to a degree that makes the user feel as little discomfort as possible from the deterioration in the vacuum cleaner's performance while in use, and adjustments are made so that the slope of the future target degradation curve becomes smaller. This extends the battery life.

Select candidates for deterioration suppression factors from the operation information stored in the memory unit 300 (step s304). Here, there may be multiple candidates.

The selected deterioration suppression factor is used as a parameter, and a deterioration prediction equation is used to calculate the parameter value that results in the target deterioration curve in a specified cycle (step S305).

Then, it is determined whether the SOHQ target value has been reached in the future after a predetermined number of cycles have elapsed (step s306). If the SOHQ target value has been reached, degradation suppression operation is started based on the suppressed degradation factors (step s307).

On the other hand, if the SOHQ target value is not reached, the process returns to step s304, a candidate deterioration suppression factor is selected again, and steps s305 and s306 are performed.

If the SOHQ target value is not ultimately reached, the candidate degradation suppression factor that comes closest to the SOHQ target value is adopted.

In summary, regardless of whether the SOHQ target value is reached or not, the deterioration factors that are effective for deterioration suppression control are selected using the historical information of the deterioration factors stored in the memory unit 300.

Figure 4 is a graph showing an overview of the degradation suppression control in the control device for a secondary battery according to the embodiment. The horizontal axis shows the number of charge/discharge cycles, and the vertical axis shows SOHQ.

In this figure, the past, present, and future target degradation curves are shown with dashed lines. The target degradation curves show the change in SOHQ when the vacuum cleaner is operated under conditions set so that the battery life is the period originally expected by the vacuum cleaner manufacturer.

The current SOHQ detection value calculated based on the actual operating conditions of the vacuum cleaner is also shown with a ● mark.

In this figure, as an example of the actual cycle number, the past is the 1st cycle, the present is the 10th cycle, and the future is the 20th cycle. Note that if deterioration is expected not only during cycles but also during storage, it is desirable to add the contribution of storage deterioration to the deterioration prediction formula.

In this figure, the current SOHQ detection value is lower than the current SOHQ reference value (circle). In such a state, the degradation suppression factor is selected so that the SOHQ gradually decreases from the present (10th cycle) to the future (20th cycle), as shown by the solid line, and approaches the target degradation curve.

In this embodiment, the method for selecting the degradation suppression factor is very important.

The main focus of the control method according to this embodiment is to suppress the deterioration of the secondary battery by controlling the deterioration suppression factor in a suppressive direction. However, if the suppression is strengthened, although the deterioration can be suppressed, there is a problem that the user's usability is affected, for example, in the case of a rechargeable vacuum cleaner, the suction power decreases, causing dissatisfaction among the user. In addition, there are various usage methods depending on the user, such as high-power users who frequently use high suction power, and users who do not need much suction power but use the device for long periods of time on a single charge. If the same deterioration suppression control is applied to each user, the users may be dissatisfied with the usability.

For this reason, (a) the user's usage status and tendencies are analyzed in advance, and the deterioration factors are selected in the control device, with a primary focus on controlling deterioration factors that the user does not use frequently. (b) Secondly, when suppressing control, it is important to control the controlled factors by gradually changing them rather than making large changes. When gradually changing the controlled factors, it is possible to control the initially set a, b, and c in the above formula (2) so as to gradually decrease them at a specified rate. The rate at which the deterioration is made can be changed as desired.

In the case of (a) above, a, b, c, and d in the above formula (2) are used to determine whether the user is a high-power user or a low-power user based on the usage trend information of the user stored in the memory unit 300, and degradation factors are selected.

For high-power users, power (W) is determined by voltage x discharge current, so a and c in the above formula (2) are important. For this reason, b is given priority as a factor for controlling deterioration suppression.

For low-power users, the usage time takes priority, so the factor c that suppresses the deterioration factor can be small. For this reason, a and b are controlled with priority. By selecting the factors to be controlled based on the user's usage trends, it becomes possible to apply the deterioration prediction formula more quickly and lightly.

In addition, if the battery is configured to be cooled by a cooling fan or the like, the deterioration factor d can also be controlled. Even if a cooling fan is not installed, the battery can be cooled by, for example, introducing some of the air sucked in by a vacuum cleaner around the battery.

In this way, the deterioration factors are selected and substituted into the deterioration prediction formula, and a, b, and c, or a, b, c, and d if a cooling mechanism is present, are calculated so that the future SOHQ becomes the value of the target deterioration curve in Figure 4.

In addition, the information stored in the memory unit 300 can be collected over a network, put into a database, and processed to use for understanding the usage status of devices such as vacuum cleaners and for predictive diagnosis of malfunctions. One specific example of a network is the Internet. In addition, by transmitting the processed information to the user over the network, it can be used for maintenance services, such as understanding the usage status of the device, calculating the SOHQ, and even automatically ordering batteries when the SOHQ drops. Furthermore, when the device breaks down, it is possible to analyze the usage history, determine the cause of the failure, and arrange for a repair order.

In other words, the control device 200 may further have a communication unit and be connected to an external computer such as a server via a wireless or wired electric communication line. With such a configuration, the computer may be capable of grasping the usage status of a device such as a vacuum cleaner that uses a secondary battery as a power source, performing calculations such as predictive failure diagnosis, calculating SOHQ, automatically ordering batteries, analyzing usage history, analyzing the cause of failure, and arranging for repair orders. With such a configuration, the computer may also be capable of statistically processing data such as the usage status and SOHQ of secondary batteries used in other vacuum cleaners, thereby improving the accuracy of deterioration prediction formulas, etc.

Figure 5 is an external perspective view showing an example of a vacuum cleaner incorporating the secondary battery control device of this embodiment.

As shown in this diagram, the vacuum cleaner 800 is configured in a stick shape by combining a vacuum cleaner main body 2 equipped with a hand-operated switch 7, an extension tube 5, and a suction body 6. The vacuum cleaner 800 also includes a rechargeable battery 24 (secondary battery) that serves as the power source for driving the vacuum cleaner main body 2 and the suction body 6.

The vacuum cleaner main body 2 includes an electric blower 1 that generates suction force, and a dust collection section 22 that collects dust collected by the suction force of the electric blower 1. The vacuum cleaner main body 2 also includes a built-in control device for a rechargeable battery 24.

One end of the extension tube 5 is connected to the connection port 23 of the vacuum cleaner body 2 so as to communicate with the dust collection section 22 of the vacuum cleaner body 2. The other end of the extension tube 5 is connected to the suction body 6. The extension tube 5 is also provided with a ventilation passage (not shown) and wiring (not shown) that electrically connects the rechargeable battery 24 to the electric motor (not shown) for the brush of the suction body 6.

When the hand-operated switch 7 is operated, a main body control circuit (not shown) controls the operation and stopping of the electric blower 1, switching of suction power, and the operation and stopping of the electric motor (not shown) provided in the suction mouth body 6. The main body control circuit is provided in the vacuum cleaner main body 2.

The vacuum cleaner is not limited to the stick type vacuum cleaner shown in the figure, but can be applied to rechargeable (cordless) vacuum cleaners such as handheld vacuum cleaners, canister vacuum cleaners (cylinder type vacuum cleaners), and robot vacuum cleaners. It can also be applied to corded vacuum cleaners with a similar configuration.

In the above embodiment, the secondary battery control device according to the present disclosure is described as being applied to a rechargeable vacuum cleaner, but the secondary battery control device according to the present disclosure is not limited to the above embodiment and includes other embodiments as long as they do not impair the features described in this specification. For example, the secondary battery control device according to the present disclosure can be applied to rechargeable personal computers (PCs), mobile terminals such as smartphones, home routers, electric vehicles that control secondary batteries without using external data centers (servers), etc.

1: Electric blower, 2: Vacuum cleaner body, 5: Extension tube, 6: Suction nozzle, 7: Hand-operated switch, 24: Rechargeable battery, 100: Battery, 200: Control device, 210: SOC/SOH detection unit, 220: Operation information collection and analysis unit, 230: Time and storage temperature management unit, 235: Deterioration prediction unit, 240: Deterioration determination unit, 260: Display unit, 300: Memory unit, 400: Vacuum cleaner control unit, 500: Current time measurement unit, 600: Temperature sensor, 700: User input unit, 800: Vacuum cleaner.

Claims (15)

a deterioration level detection unit that calculates a detection value of a deterioration level of the secondary battery;
a memory unit that stores history information of deterioration factors of the secondary battery and data used to calculate a reference value of the deterioration level of the secondary battery (excluding a reference value calculated by an external data center);
a deterioration determination unit that determines whether the detection value is larger than the reference value for the deterioration level of the secondary battery,
the deterioration determination unit is capable of selecting deterioration suppression control when the detection value is equal to or less than the reference value ,
A control device for a secondary battery , wherein the degradation suppression control selects a degradation suppression factor so that the detection value approaches a target degradation curve when the detection value is lower than the reference value. The control device for a secondary battery according to claim 1, wherein the deterioration determination unit prompts a user about the selection of the deterioration suppression control. The control device for a secondary battery according to claim 2, wherein the deterioration determination unit executes the deterioration suppression control when the user desires the deterioration suppression control. The control device for a secondary battery according to claim 2, wherein the deterioration determination unit continues normal operation and notifies the user of an early deterioration alert for the secondary battery if the user does not desire the deterioration suppression control. The secondary battery control device according to claim 2, further comprising a display unit that displays the question. The control device for a secondary battery according to claim 4, further comprising a display unit that displays the early deterioration alert. The secondary battery control device according to claim 2, further comprising a user input unit that accepts the user's response to the question as an input. The control device for a secondary battery according to claim 3, wherein the deterioration determination unit uses the history information of the deterioration factors of the secondary battery stored in the memory unit to select from among the deterioration factors those that are effective for the deterioration suppression control. The control device for a secondary battery according to claim 1, wherein the deterioration determination unit notifies a user that the secondary battery is expected to last a long time if the detection value is greater than the reference value. The control device for a secondary battery according to claim 1, further comprising a deterioration prediction unit that calculates the reference value of the degree of deterioration using a deterioration prediction formula. The secondary battery control device according to claim 1, further comprising a communication unit that can be connected to an external computer via an electric communication line. A deterioration level detection unit calculates a detection value of a deterioration level of the secondary battery;
A memory unit stores history information of deterioration factors of the secondary battery and data used for calculating a reference value of the deterioration degree of the secondary battery (excluding a reference value calculated by an external data center);
a deterioration determination unit determining whether the detected value is smaller than a reference value for the deterioration level of the secondary battery;
When the detection value is equal to or less than the reference value, the deterioration determination unit selects deterioration suppression control ,
The method for controlling a secondary battery , wherein the degradation suppression control selects a degradation suppression factor so that the detection value asymptotically approaches a target degradation curve when the detection value is lower than the reference value. The method for controlling a secondary battery according to claim 12, further comprising a step in which the degradation determination unit asks a user about the selection of the degradation suppression control. The method for controlling a secondary battery according to claim 13, further comprising a step in which the degradation determination unit executes the degradation suppression control when the user desires the degradation suppression control. A rechargeable vacuum cleaner comprising a secondary battery, an electric blower, and the control device for the secondary battery according to claim 1.

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