Energy storage devices

Abstract

To provide a power storage device capable of charging accumulator batteries by using various power supplies while suppressing heat generation of a DCDC converter.SOLUTION: A power storage device comprises: an accumulator battery unit that includes a plurality of parallel-connected accumulator batteries; a plurality of constant current circuits that supply current to the plurality of accumulator batteries; a DCDC converter that outputs voltage required for charging the accumulator battery unit to the accumulator battery unit; a detection unit that detects a parameter related to heat generation of the DCDC converter; a plurality of switches provided so as to correspond to the plurality of accumulator batteries, switching charging and charging stop to the corresponding accumulator batteries; and a control unit that controls the plurality of switches to increase or decrease the number of the accumulator batteries to be charged. The control unit controls the number of the accumulator batteries to be charged so as to suppress heat generation of the DCDC converter, on the basis of the parameter.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electricity storage device. [Background technology]

[0002] Charging methods for storage batteries include constant current charging, float charging, etc. An appropriate charging method is adopted depending on the type of storage battery.

[0003] Patent Document 1 discloses an electricity storage device including a storage battery unit in which multiple storage batteries are connected in parallel to a power source. When the electricity storage device of Patent Document 1 is connected to a power source, the storage battery unit is charged using power supplied from the power source. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-254063 Summary of the Invention [Problem to be solved by the invention]

[0005] In general, a power storage device is provided with a DC-DC converter, and during charging, power from a power source is supplied to the storage battery via the DC-DC converter.

[0006] In such an energy storage device, when multiple storage batteries connected in parallel are charged using a constant current charging method, the power required to charge the storage battery unit increases as the number of storage batteries increases. Also, the input voltage to the energy storage device, i.e., the input voltage to the DC-DC converter, varies depending on the output of the power source used to charge the energy storage device.

[0007] Therefore, the smaller the output of the power supply, the greater the step-up amount of the input voltage by the DC-DC converter, which in turn makes the DC-DC converter more likely to generate heat.

[0008] For this reason, the input voltage to the DC-DC converter is limited to a certain range to prevent heat generation in the DC-DC converter, and a power supply that outputs a voltage within this range is used to charge the storage battery unit.

[0009] An object of the present disclosure is to provide an electricity storage device that can charge a storage battery using various power sources while suppressing heat generation in a DC-DC converter. [Means for solving the problem]

[0010] The electricity storage device according to the present disclosure comprises: a storage battery unit including a plurality of storage batteries connected in parallel; a plurality of constant current circuits for supplying current to the plurality of storage batteries; a DC-DC converter that outputs a voltage required for charging the storage battery unit to the storage battery unit; A detection unit that detects parameters related to heat generation of the DC-DC converter; a plurality of switches provided corresponding to the plurality of storage batteries, for switching between charging and stopping the corresponding storage batteries; a control unit that controls the plurality of switches to increase or decrease the number of storage batteries to be charged; Equipped with The control unit controls the number of the storage batteries to be charged based on the parameters so as to suppress heat generation in the DC-DC converter. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to provide an electricity storage device that can charge a storage battery using various power sources while suppressing heat generation in a DC-DC converter. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a circuit diagram illustrating an electricity storage device according to an embodiment. [Figure 2] 4 is an example of a flowchart illustrating an operation of the power storage device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an electricity storage device according to an embodiment of the present disclosure will be described with reference to the drawings.

[0014] (Circuit configuration) 1 is a circuit diagram showing an energy storage device 1 according to an embodiment. The energy storage device 1 is a device that stores therein power supplied from an external power source and supplies the stored power to a power supply target device. The external power source is, for example, a device that converts commercial AC power into DC power and outputs the DC power.

[0015] The power storage device 1 includes a storage battery unit 100 and a control circuit 200.

[0016] The storage battery unit 100 includes a plurality of storage batteries. In Fig. 1, the storage battery unit 100 includes three storage batteries 111 to 113, which are connected in parallel.

[0017] The storage batteries 111 to 113 are suitable for charging by a constant current charging method, and may be, for example, nickel-metal hydride batteries. However, the storage batteries 111 to 113 may be, for example, lithium-ion batteries or other storage batteries other than nickel-metal hydride batteries.

[0018] The control circuit 200 has a function of controlling the charging of the storage battery unit 100. The control circuit 200 is connected to an external power supply via input / output terminals 301 and 302, and charges the storage battery unit 100 with power from the external power supply.

[0019] The control circuit 200 includes a DC-DC converter 210, constant current circuits 221 to 223, charge control switches 241 to 243, a detection unit 270, and a control unit 280.

[0020] The DC-DC converter 210 is a power conversion device that converts the voltage supplied from an external power source. In this embodiment, the DC-DC converter 210 functions as a device that outputs a voltage required for charging to the storage battery unit 100 based on the voltage of the external power source. In this embodiment, the DC-DC converter 210 is a step-up DC / DC converter that boosts the voltage supplied from the external power source and outputs the boosted voltage to the storage battery unit 100. Note that the DC-DC converter 210 may be a high-performance DC-DC converter that will not break down even if all the storage batteries 111 to 113 in the storage battery unit 100 are simultaneously charged when the upper limit voltage that can be input is input, for example.

[0021] The constant current circuits 221 to 223 are provided corresponding to the storage batteries 111 to 113. The constant current circuits 221 to 223 output a constant current to the corresponding storage batteries 111 to 113 regardless of the voltage supplied from the DC-DC converter 210.

[0022] The charge control switches 241 to 243 are provided corresponding to the storage batteries 111 to 113. In FIG. 1, the charge control switches 241 to 243 are arranged on a power supply path connecting the DC-DC converter 210 and each of the constant current circuits 221 to 223. The charge control switches 241 to 243 switch between connecting and disconnecting the power supply path under the control of the control unit 280. This switches between charging and stopping the charging of each of the storage batteries 111 to 113.

[0023] The charge control switches 241 to 243 only need to be arranged on the power supply path connecting the DC-DC converter 210 and each of the storage batteries 111 to 113, and may also be arranged on multiple power supply paths connecting the constant current circuits 221 to 223 and the storage batteries 111 to 113.

[0024] The control circuit 200 also has a function of controlling the discharge of the storage battery unit 100. The control circuit 200 further includes discharge control switches 261-263. The discharge control switches 261-263 switch between connecting and disconnecting the storage batteries 111-113 to the input / output terminals 301, 302 under the control of the control unit 280. As a result, when a power supply target device is connected to the control circuit 200 via the input / output terminals 301, 302, the storage batteries 111-113 are switched between discharging and stopping discharging with respect to the power supply target device.

[0025] The detection unit 270 is, for example, a sensor group made up of various sensors, which detects various parameters and outputs them to the control unit 280. The parameters to be detected are parameters that are correlated with the amount of heat generated by the DCDC converter 210, such as the voltage input to the DCDC converter 210 (hereinafter also referred to as "input voltage"), the current flowing through the DCDC converter 210, and the temperature of the DCDC converter 210. The detection unit 270 also detects parameters related to the charging status, such as the charging rate of the storage batteries 111 to 113, and outputs them to the control unit 280.

[0026] The control unit 280 is, for example, a computer, and performs overall control of the power storage device 1. The control unit 280 has a storage unit (not shown). The storage unit stores charge control data used for charge control. The charge control data will be described in detail later.

[0027] The control unit 280 controls the charge control switches 241-243 based on the detection result (input voltage in this case) of the detection unit 270 and the charge control data, thereby controlling the charge of the power storage device 1. The charge control by the control unit 280 will be described in detail later. The control unit 280 also controls the discharge control switches 261-263, thereby controlling the discharge of the power storage device 1.

[0028] In the power storage device 1 having the circuit configuration shown in Fig. 1, a plurality of storage batteries 111 to 113 connected in parallel are charged by a constant current charging method. As the output of the external power supply becomes smaller, the DC-DC converter 210 increases the step-up amount during voltage conversion. In other words, the burden on the DC-DC converter 210 increases, and the DC-DC converter 210 is more likely to generate heat. Therefore, in order to charge the power storage device 1 while suppressing heat generation in the DC-DC converter 210, it is necessary to use an external power supply that can output a relatively large voltage.

[0029] In this embodiment, charging control, which will be described later, is executed. Therefore, while suppressing heat generation from the DC-DC converter 210, it is possible to charge the storage batteries 111 to 113 using various power supplies, from external power supplies that can output a relatively low voltage to external power supplies that can output a relatively high voltage.

[0030] (Charging control) The following describes the charging control of the power storage device 1. Fig. 2 is an example of a flowchart showing the charging control of the power storage device 1 according to the embodiment.

[0031] First, in step S1, the control unit 280 determines whether or not the power storage device 1 is connected to an external power supply. For example, if the detection unit 270 detects an input voltage to the DC-DC converter 210, the control unit 280 determines that the power storage device 1 is connected to an external power supply, and if the detection unit 270 does not detect an input voltage, the control unit 280 determines that the power storage device 1 is not connected to an external power supply.

[0032] If the power storage device 1 is not connected to an external power supply ("NO" in step S1), the control unit 280 repeats the process of step S1 until the power storage device 1 is connected to an external power supply.

[0033] When the power storage device 1 is connected to an external power source ( "YES" in step S1), the process proceeds to step S2. In step S2, the control unit 280 refers to the charging control data based on the input voltage detected by the detection unit 270 and determines the initial value N of the number of rechargeable batteries (hereinafter, may also be referred to as "initial value N").

[0034] The charging control data includes, for example, the number of rechargeable batteries at the same time and the threshold data of a plurality of voltages corresponding to the number of batteries. Also, the temperature data used in the process of step S5 described later is included. The initial value N is the maximum number of rechargeable batteries at the same time. In step S2, the control unit 280 determines the initial value N such that the smaller the input voltage, the fewer the number of rechargeable batteries. Hereinafter, step S2 will be described in detail.

[0035] First, in step S21, the control unit 280 acquires the input voltage value Vin from the detection unit 270. Then, in step S22, the control unit 280 compares the input voltage value Vin with the first threshold value Vth1 included in the charging control data and determines whether the input voltage value Vin is equal to or greater than the first threshold value Vth1.

[0036] When the input voltage value Vin is equal to or greater than the first threshold value Vth1 ( "YES" in step S₂₂), the process proceeds to step S₂₃, and the control unit 280 determines the initial value N to be "3". Then, the process proceeds to step S3.

[0037] When the input voltage value Vin is less than the first threshold value Vth1 ( "NO" in step S₂₂), the process proceeds to step S₂₄. In step S₂₄, the control unit 280 compares the input voltage value Vin with the second threshold value Vth2 (Vth2 < Vth1) included in the charging control data and determines whether the input voltage value Vin is equal to or greater than the second threshold value Vth2 and less than the first threshold value Vth1.

[0038] If the input voltage value Vin is equal to or greater than the second threshold value Vth2 and less than the first threshold value Vth1 (“YES” in step S24), the process proceeds to step S25, where the control unit 280 determines the initial value N to be “2.” Next, the process proceeds to step S3.

[0039] If the input voltage value Vin is less than the second threshold value Vth2 ("NO" in step S24), the process proceeds to step S26, where the control unit 280 determines the initial value N to be "1." Next, the process proceeds to step S3.

[0040] In step S3, the control unit 280 selects a storage battery to be charged from among the storage batteries 111-113 based on the determined initial value N and a predetermined selection rule, and starts charging the selected storage batteries 111-113. Specifically, the control unit 280 sets the charge control switches 241-243 corresponding to the selected storage batteries 111-113 to a connected state, and sets the charge control switches 241-243 corresponding to the non-selected storage batteries 111-113 (i.e., storage batteries not to be charged) to a disconnected state.

[0041] When step S3 is executed, if there is an unselected battery among the batteries 111 to 113, the control unit 280 completes charging of one of the selected batteries, then ends charging of the battery that has been fully charged, and starts charging of the unselected battery.

[0042] Examples of the predetermined selection rules include the following selection rules (A1) to (A3): For example, the control unit 280 may select the storage battery to be charged based on any of the selection rules (A1) to (A3). (A1) A battery with a high charging rate is preferentially selected from among the batteries 111 to 113 as a battery to be charged. (A2) Among the storage batteries 111 to 113, a storage battery with a low charging rate is preferentially selected as the storage battery to be charged. (A3) Based on the charging rates of the storage batteries 111 to 113, a storage battery to be charged is selected so that the total time required for all the storage batteries 111 to 113 to be fully charged (reach a charging rate of 100%) is shortest.

[0043] Next, the process proceeds to step S4. In step S4 and steps S5 to S6 described below, a process is performed to change the number of storage batteries to be charged from the already determined initial value N in accordance with the state of the power storage device 1 after charging has started. This process will be described in detail below.

[0044] The control unit 280 acquires the temperature T of the DC-DC converter 210 from the detection unit 270. Then, in step S5, the control unit 280 determines whether or not there is an abnormality based on the acquired temperature T. For example, if the acquired temperature T is equal to or higher than a predetermined temperature Tth included in the charging control data, the control unit 280 determines that there is an abnormality, and if the acquired temperature T is lower than the predetermined temperature Tth, the control unit 280 determines that there is no abnormality. Here, for example, the predetermined temperature Tth is 110°C.

[0045] If it is determined that there is no abnormality ("NO" in step S5), the process proceeds to step S7.

[0046] If it is determined that "an abnormality exists" ("YES" in step S5), the process proceeds to step S6, where the control unit 280 changes the number of storage batteries to be charged. For example, the control unit 280 reduces the number of storage batteries to be charged by one from the number of storage batteries being charged at the time when it is determined that "an abnormality exists" until the temperature T of the DC-DC converter 210 becomes less than a predetermined temperature Tth. Here, the control unit 280 selects storage batteries to stop charging one by one from among the storage batteries being charged, based on a predetermined change rule.

[0047] The predetermined change rules include, for example, the following change rules (B1) to (B3): For example, the control unit 280 may select a storage battery for which charging is to be stopped based on any of the change rules (B1) to (B3). (B1) Among the storage batteries 111 to 113 currently being charged, the storage battery with the highest charging rate is stopped with priority. (B2) Among the storage batteries 111 to 113 currently being charged, the charging of the storage battery with the lowest charging rate is stopped preferentially. (B3) Based on the charging rates of the batteries 111-113 being charged, a battery for which charging is to be stopped is selected so as to minimize the total time required for all the batteries 111-113 to be fully charged (reach 100% charging rate).

[0048] After the temperature T of the DC-DC converter 210 becomes lower than the predetermined temperature Tth and the number of storage batteries to be charged is determined, the process proceeds to step S7. In step S7, the control unit 280 determines whether charging of all of the storage batteries 111-113 in the storage battery unit 100 has been completed based on the detection result of the detection unit 270 (the charging status of the storage batteries 111-113).

[0049] If charging of all the storage batteries 111-113 has not been completed ("NO" in step S7), the control unit 280 proceeds to step S4. That is, the control unit 280 executes the processes of steps S4-S7 until charging of all the storage batteries 111-113 is completed.

[0050] If charging of all the storage batteries 111-113 is completed ("YES" in step S7), the process proceeds to step S8, where the control unit 280 turns off all the charge control switches 241-243 and ends charging of the storage batteries 111-113.

[0051] The control unit 280 determines that the power storage device 1 has a range of parameters that can be used as the power storage device 1. For example, there are upper and lower limits for each of the input voltage, input current, temperature, etc. to the DC-DC converter 210. In this embodiment, the control unit 280 controls the number of storage batteries to be charged so that the ranges do not fall outside the upper and lower limits.

[0052] Furthermore, when step S6 is executed and the number of storage batteries to be charged becomes smaller than the initial value N, and the temperature T becomes equal to or lower than another predetermined temperature Tth0 that is lower than the predetermined temperature Tth, the control unit 280 may increase the number of storage batteries to be charged up to the initial value N. In this case, the other lower predetermined temperature Tth0 is included in the charging control data.

[0053] Furthermore, the charging control data only needs to include data indicating the correspondence between the number of storage batteries to be charged simultaneously and parameters caused by heat generation in the DC-DC converter 210, and data used for the determination in step S5. Therefore, the charging control data does not necessarily need to include the first threshold value Vth1 and the second threshold value Vth2, which are voltage threshold values.

[0054] As described above, according to the embodiment, the device comprises a storage battery unit 100 including a plurality of storage batteries 111 to 113 connected in parallel, a plurality of constant current circuits 221 to 223 that supply current to the plurality of storage batteries 111 to 113, a DCDC converter 210 that outputs to the storage battery unit 100 the voltage required to charge the storage battery unit 100, a detection unit 270 that detects parameters related to heat generation of the DCDC converter 210, a plurality of switches (charge control switches 241 to 243) that are provided corresponding to the plurality of storage batteries 111 to 113 and that switch between charging and stopping charging of the corresponding storage batteries 111 to 113, and a control unit 280 that controls the charge control switches 241 to 243 to increase or decrease the number of storage batteries to be charged.

[0055] The control unit 280 controls the number of storage batteries to be charged based on the parameters so as to suppress heat generation in the DC-DC converter 210.

[0056] That is, since the number of storage batteries 111-113 to be charged can be increased or decreased depending on the output voltage of the external power supply, it is possible to increase or decrease the power required to charge the storage battery unit 100. In particular, when the output voltage of the external power supply is relatively small, it is possible to reduce the power required to charge the storage battery unit 100 by reducing the number of storage batteries 111-113 to be charged. Therefore, it is possible to reduce the step-up amount during voltage conversion in the DC-DC converter 210, thereby suppressing heat generation in the DC-DC converter 210.

[0057] Therefore, the storage battery can be charged using external power supplies with various output voltages while suppressing heat generation in the DC-DC converter 210.

[0058] If heat generation in the DC-DC converter 210 is to be suppressed without performing the charge control according to this embodiment, it is necessary to improve the performance of the DC-DC converter 210, which would result in an increase in the size of the DC-DC converter 210. According to this embodiment, it is not necessary to improve the performance and increase the size of the DC-DC converter 210, so it is possible to reduce the cost and size of the power storage device 1.

[0059] The DC-DC converter 210 is a boost converter that increases the voltage output to the storage battery unit 100 to be greater than the input voltage to the DC-DC converter 210.

[0060] That is, in the circuit of the power storage device 1 according to this embodiment, when the number of storage batteries to be charged is constant regardless of the external power supply, the DC-DC converter 210 is more likely to generate heat as the voltage that the external power supply can output decreases.

[0061] However, according to this embodiment, the above-described charging control is executed, so that the storage battery can be charged using external power supplies with various output voltages while suppressing heat generation in the DC-DC converter 210.

[0062] Specifically, the detection unit 270 detects the input voltage to the DC-DC converter 210, and the control unit 280 reduces the number of storage batteries 111 to 113 to be charged as the input voltage decreases.

[0063] When the power storage device 1 is connected to an external power source, the number of storage batteries to be charged can be determined based on easily detectable parameters.

[0064] The detection unit 270 detects the temperature of the DC-DC converter 210, and the control unit 280 changes the number of storage batteries 111-113 to be charged according to the temperature of the DC-DC converter while the storage batteries 111-113 are being charged.

[0065] Therefore, if the temperature of the DC-DC converter 210 becomes higher than expected after charging of the storage batteries 111 to 113 determined to be charged has started, it is possible to reduce the number of storage batteries to be charged afterwards and suppress heat generation in the DC-DC converter 210. Furthermore, after the temperature of the DC-DC converter 210 has dropped by reducing the number of storage batteries to be charged, it is possible to increase the number of storage batteries to be charged up to the initial value N, thereby shortening the total time until charging of all the storage batteries 111 to 113 is completed.

[0066] The storage batteries 111 to 113 are nickel-metal hydride storage batteries or lithium-ion storage batteries, that is, storage batteries that are suitable for charging by a constant current charging method are used.

[0067] (Variation) In the above embodiment, the storage battery unit 100 is described as having three storage batteries connected in parallel, but the present disclosure can also be applied to cases where the storage battery unit 100 has two or four or more storage batteries connected in parallel.

[0068] The detection unit 270 may detect the input current or input power instead of the input voltage to the DC-DC converter 210. In this case, in step S3 described above, the control unit 280 decreases the number of storage batteries to be charged as the input current or input power decreases, and increases the number of storage batteries to be charged as the input current or input power increases.

[0069] In addition, in the above-mentioned step S3, the control unit 280 may determine the number of storage batteries to be charged based on two or more parameters of the input voltage, input current, and input power to the DC-DC converter 210, and temperature.

[0070] The storage battery unit 100 may include, for example, a battery bank instead of the storage batteries. This battery bank is configured by connecting a plurality of storage batteries in series.

[0071] Furthermore, the control unit 280 may not execute the process of changing the number of storage batteries to be charged after determining the initial value N. That is, steps S4 to S6 may be omitted in the charge control. [Industrial Applicability]

[0072] The present disclosure is suitably used as an electricity storage device including a plurality of storage batteries. [Explanation of symbols]

[0073] 1. Energy storage devices 100 Battery Unit 200 Control circuit 210 DC-DC converter 221, 222, 223 constant current circuit 241, 242, 243 Charging control switch 261, 262, 263 Discharge control switch 270 Detector 280 Control Unit 301, 302 input / output terminals

Claims

1. a storage battery unit including a plurality of storage batteries connected in parallel; a plurality of constant current circuits for supplying current to the plurality of storage batteries; a DC-DC converter that outputs a voltage required for charging the storage battery unit to the storage battery unit; a detection unit that detects a parameter related to heat generation of the DC-DC converter; a plurality of switches provided corresponding to the plurality of storage batteries, for switching between charging and stopping the corresponding storage batteries; a control unit that controls the plurality of switches to increase or decrease the number of storage batteries to be charged; Equipped with the control unit controls the number of the storage batteries to be charged based on the parameter so as to suppress heat generation of the DC-DC converter. Energy storage device.

2. the DC-DC converter is a boost converter that increases the voltage output to the storage battery unit more than the input voltage to the DC-DC converter; The electricity storage device according to claim 1 .

3. the detection unit detects an input voltage to the DC-DC converter, the control unit reduces the number of the storage batteries to be charged as the input voltage decreases, The electricity storage device according to claim 1 or 2.

4. the detection unit detects a temperature of the DC-DC converter, the control unit changes the number of the storage batteries to be charged in accordance with the temperature of the DC-DC converter while the storage batteries are being charged. The electricity storage device according to claim 1 .

5. The storage battery is a nickel-metal hydride storage battery or a lithium-ion storage battery. The electricity storage device according to claim 1 .

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