power supply

Abstract

To provide a power unit which charges a secondary battery cell to restore to a normal charge / discharge operation even when the remaining amount of charge of the second battery cell decreases and an operation of a BMS stops.SOLUTION: A power unit (100) comprises: a solar cell (10) which generates power by light to output power; a secondary battery cell (40) which stores power; a battery management unit (30) which interrupts takeout of power stored in the secondary battery cell (40) to execute a protection operation when storage voltage of the secondary battery cell (40) is equal to or less than protection voltage; and an automatic restoration control unit (50) which is connected between the solar cell (10) and the battery management unit (30), converts a part of power output by the solar cell (10) into first voltage and a first current value to be supplied to the secondary battery cell (40) and executes a restoration charging operation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power supply device, and more particularly to a power supply device that stores the output from a solar cell in a secondary battery cell. [Background technology]

[0002] In recent years, solar cells that generate electricity using solar energy have become widespread, and it has become common to use the roofs of ordinary houses or unused land for solar power generation. In such solar power generation facilities, when the amount of electricity generated by sunlight is insufficient, power is also supplied from the power grid from the power plant. Also, when the amount of electricity generated by sunlight is greater than the amount of electricity consumed, the surplus electricity is sold through the power transmitter.

[0003] However, in remote areas or undeveloped areas where it is difficult to lay power transmission facilities, it is impossible to supply and sell power using a power transmission grid, making it difficult to install and utilize solar power generation facilities. Therefore, an independent power supply device has been proposed that combines solar cells and secondary batteries, temporarily stores power generated by the solar cells in the secondary batteries, and extracts the power stored in the secondary batteries as needed (see, for example, Patent Document 1).

[0004] FIG. 5 is a block diagram showing a schematic configuration of a conventional independent power supply device. As shown in FIG. 5, the conventional independent power supply device includes a solar cell 10, a charge / discharge control unit 20, a battery management system (BMS) 30, and a secondary battery cell 40. The output of the solar cell 10 is connected to the input of the charge / discharge control unit 20, and the output of the charge / discharge control unit 20 is connected to the battery management unit 30. The battery management unit 30 is connected to the electrode terminals of the secondary battery cell 40 and is driven by power from the secondary battery cell 40. It acquires the status of the secondary battery cell 40 and controls overcharge protection and overdischarge protection. The power stored in the secondary battery cell 40 is output to the load and charge / discharge control unit 20 via the battery management unit 30 and is used to drive the load and charge / discharge control unit 20.

[0005] In such a conventional independent power supply device, the charge / discharge control unit 20 and the battery management unit 30 are driven by power extracted from the secondary battery cell 40, and the charge / discharge control unit 20 controls the charge / discharge operation of the secondary battery cell 40. However, when the remaining charge of the secondary battery cell 40 decreases and the over-discharge protection function of the battery management unit 30 is activated, power is no longer supplied from the secondary battery cell 40 to the charge / discharge control unit 20, causing the charge / discharge control unit 20 to stop operating and prevent the charge operation from resuming. To address this issue, the present applicant has proposed a technology that restarts the charge / discharge operation by activating the charge / discharge control unit 20 with power supplied from the solar cell 10, even when the remaining charge of the secondary battery cell 40 decreases and the over-discharge protection function is activated (Patent Document 2). Furthermore, in Patent Document 2, even when the secondary battery cell 40 is in an over-discharge state, the charge / discharge control unit 20 acquires the status of the secondary battery cell 40 from the battery management unit 30 and performs a pre-charge operation to resume charging. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2017-017778 [Patent Document 2] Patent No. 6031721 Summary of the Invention [Problem to be solved by the invention]

[0007] The prior art disclosed in Patent Document 2 uses a highly replaceable and portable secondary battery module, allowing the secondary battery module to be replaced as needed. This prevents further discharging of a secondary battery module that has been protected from over-discharge, resulting in a deeply discharged state. Even if a secondary battery module were to reach a deeply discharged state, it could be easily replaced with another secondary battery module, allowing the charge / discharge operation to continue and the deeply discharged secondary battery module to be recovered.

[0008] However, for independent power supply devices installed in remote locations such as those described above, it is difficult to perform repeated maintenance on the equipment in a short period of time. During periods of prolonged lack of sunlight, such as during the rainy or snowy seasons, the independent power supply device in a remote location cannot continue charging the secondary battery. Therefore, the operation of the battery management unit 30 may cause further discharge in an over-discharged secondary battery cell 40, potentially leading to a deep discharge. Because the battery management unit 30 operates on power supplied from the secondary battery cell 40, the battery management unit 30 becomes inactive when a secondary battery cell 40 becomes deeply discharged, preventing the battery management unit 30 from resuming charging. Even with the technology described in Patent Document 2, the battery management unit 30 remains inactive when a secondary battery cell 40 becomes deeply discharged, making it impossible to obtain the status of the secondary battery cell 40 and perform a precharge operation.

[0009] As described above, in the prior art, when the remaining charge of the secondary battery cell 40 progresses to a deeply discharged state, the battery management unit 30 cannot be restarted even if sunlight returns, so the pre-charge operation and charge / discharge operation by the charge / discharge control unit 20 cannot be performed, and the storage and supply of the electricity generated by the solar cell 10 cannot be continued.

[0010] Therefore, the present invention has been made in consideration of the above-mentioned conventional problems, and aims to provide a power supply device that can charge secondary battery cells and return to normal charging and discharging operation even when the remaining charge of the secondary battery cells is low and the BMS operation has stopped. [Means for solving the problem]

[0011] In order to solve the above problems, a power supply device of the present invention includes a solar cell that generates power using light and outputs the power, a secondary battery cell that stores the power, a battery management unit that performs a protection operation by cutting off extraction of the power stored in the secondary battery cell when the stored voltage of the secondary battery cell is equal to or lower than a protection voltage, and an automatic return control unit that is connected between the solar cell and the battery management unit and converts a part of the power output from the solar cell into an automatic return current having a first voltage and a first current value, and supplies the automatic return current to the battery management unit to perform a return charging operation, and the automatic return control unit is Lifting The automatic recovery current output unit includes a first step-up / step-down unit, a step-up confirmation unit, a second step-up unit, and a constant current output unit, wherein the first step-up / step-down unit steps up or steps down power input from an input terminal, adjusts it to a predetermined planned voltage, and outputs it; the step-up confirmation unit monitors the first output voltage of the first step-up / step-down unit, and operates the second step-up unit when the first output voltage reaches the planned voltage; the second step-up unit further steps up the planned voltage to a second output voltage, and outputs it to the constant current output unit; and the constant current output unit operates at the second output voltage and outputs the automatic recovery current from an output terminal to the battery management unit.

[0012] In the power supply device of the present invention, even if the remaining charge of the secondary battery cell is low and the operation of the battery management unit (BMS) has stopped, the secondary battery cell can be gradually charged using the output of the solar cell until the secondary battery cell reaches or exceeds the protection voltage, and the battery management unit can be restored to normal charging and discharging operation.

[0013] In one aspect of the present invention, even if the battery management unit is performing the protection operation, the automatic recovery control unit continues the recovery charging operation.

[0014] In one aspect of the present invention, a charge / discharge control unit is provided that is connected between the solar cell and the battery management unit, converts the power output from the solar cell into a charging voltage and a charging current, and supplies the converted power to the battery management unit, and the charge / discharge control unit is operated by the power stored in the secondary battery cell.

[0015] In one aspect of the present invention, the automatic return control unit stops the return charging operation when the charging voltage reaches a predetermined maximum voltage.

[0016] In one aspect of the present invention, the charge / discharge control unit uses maximum power point tracking control.

[0017] In one aspect of the present invention, the automatic recovery control unit includes a temperature measurement unit that acquires the temperature of the secondary battery cell as a cell temperature, and stops the recovery charging operation when the temperature rise of the cell temperature is equal to or greater than a predetermined protection temperature.

[0018] In another aspect of the present invention, In the recovery charging operation, the battery management unit alternates between an operating state and a non-operating state, and the automatic recovery current charges the secondary battery cell in the temporary operating state of the battery management unit. . [Effects of the Invention]

[0020] The present invention provides a power supply device that can charge the secondary battery cells and return to normal charging and discharging operation even when the remaining charge of the secondary battery cells is low and the BMS operation has stopped. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a block diagram schematically showing the configuration of a power supply device 100 according to a first embodiment. [Figure 2] 3 is a circuit diagram showing an example of an automatic return control unit 50. FIG. [Figure 3] 3(a) and 3(d) are timing charts showing the operation of the power supply device 100, where FIG. 3(a) shows the output of the automatic recovery control unit 50, FIG. 3(b) shows the stored voltage of the secondary battery cell 40, FIG. 3(c) shows the operating state of the battery management unit 30, and FIG. 3(d) shows the charging voltage of the charge / discharge control unit 20. [Figure 4] 3 is a flowchart showing the operation of the automatic return control unit 50 shown in FIG. 2. [Figure 5] FIG. 1 is a block diagram schematically illustrating the configuration of a conventionally proposed independent power supply device. DETAILED DESCRIPTION OF THE INVENTION

[0022] (First embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The same or equivalent components, members, and processes shown in each drawing will be assigned the same reference numerals, and duplicate explanations will be omitted where appropriate. FIG. 1 is a block diagram showing a schematic configuration of a power supply device 100 according to this embodiment. As shown in FIG. 1, the power supply device 100 of this embodiment includes a solar cell 10, a charge / discharge control unit 20, a battery management unit (BMS: Battery Management System) 30, a secondary battery cell 40, and an automatic return control unit 50.

[0023] Solar cell 10 is a photoelectric conversion device that generates electricity using light and outputs the power. The configuration of solar cell 10 is not limited, and compound semiconductor solar cells such as monocrystalline silicon, polycrystalline silicon, amorphous silicon, dye-sensitized silicon, and CIGS-based solar cells can be used. Furthermore, the solar cell may be configured to be placed on a stand, or may be installed on a road surface or a wall. The output of solar cell 10 is electrically connected to the input of charge / discharge control unit 20, and the power generated by solar cell 10 is input to charge / discharge control unit 20.

[0024] The charge / discharge control unit 20 is electrically connected between the solar cell 10 and the battery management unit 30, and converts the power output from the solar cell 10 into a charging voltage and a charging current, and supplies the converted power to the battery management unit 30. The charge / discharge control unit 20 is configured with electronic circuits including an integrated circuit (IC) and is operated by the power stored in the secondary battery cell 40. The specific operation of the charge / discharge control unit 20 is not limited, and a pulse width modulation (PWM) method or a maximum power point tracking (MPPT) method can be used. To efficiently store the power generated by the solar cell 10 in the secondary battery cell 40, it is preferable to use the maximum power point tracking method.

[0025] The battery management unit 30 is electrically connected to the electrode terminals of the secondary battery cells 40 and is a part that acquires the status of the secondary battery cells 40 and manages over-discharge protection, over-charge protection, etc. The battery management unit 30 is composed of electronic circuits including ICs and is operated by power stored in the secondary battery cells 40. When the stored voltage of the secondary battery cells 40 is equal to or lower than the protection voltage, the battery management unit 30 performs an over-discharge protection operation by cutting off the extraction of power stored in the secondary battery cells 40. Furthermore, when the stored voltage of the secondary battery cells 40 is equal to or higher than a predetermined value, the battery management unit 30 performs an over-charge protection operation by cutting off the charging operation to the secondary battery cells 40. The specific operation of the battery management unit 30 is not limited, and a known battery management system (BMS) can be used.

[0026] The secondary battery cell 40 stores the power supplied from the charge / discharge control unit 20 and the automatic return control unit 50 via the battery management unit 30, and also extracts the stored power via the battery management unit 30 and supplies it to the load and the charge / discharge control unit 20. The specific configuration of the secondary battery cell 40 is not limited, and a lithium-ion battery, a nickel-metal hydride battery, a nickel-cadmium battery, an all-solid-state battery, or the like can be used. In order to reuse resources, it is preferable to reuse lithium-ion batteries used in electric vehicles or hybrid cars as the secondary battery cell 40.

[0027] The automatic return control unit 50 is connected in parallel with the charge / discharge control unit 20 between the solar cell 10 and the battery management unit 30, and converts a portion of the power output by the solar cell 10 and supplies it to the battery management unit 30. As will be described in detail later, the automatic return control unit 50 supplies current at a first voltage and a first current value to the battery management unit 30 and the secondary battery cell 40 even when the battery management unit 30 is in a stopped state (non-operating state), and performs a return charging operation on the secondary battery cell 40 until the operation of the battery management unit 30 resumes. The automatic return control unit 50 also continues the return charging operation even when the battery management unit 30 is performing a protection operation to block the extraction of power from the secondary battery cell 40 in an over-discharged state. The automatic return control unit 50 also stops the return charging operation when the charging voltage of the charge / discharge control unit 20 reaches a predetermined maximum voltage.

[0028] Fig. 2 is a circuit diagram showing an example of the automatic return control unit 50. As shown in Fig. 2, the automatic return control unit 50 includes a first step-up / step-down unit 51, a step-up confirmation unit 52, a second step-up unit 53, and a constant current output unit 54. In this embodiment, the combination of the first step-up / step-down unit 51, the step-up confirmation unit 52, and the second step-up unit 53 adjusts and outputs the power from the solar cell 10, and therefore corresponds to the voltage adjustment unit in the present invention.

[0029] The first step-up / step-down unit 51 is a circuit that boosts or lowers the power input from the input terminals LP1 and LP2, adjusting it to a predetermined voltage and outputting it. Since the output voltage of the solar cell 10 fluctuates from approximately 5 V to approximately 40 V, adjusting the output to a predetermined voltage (e.g., 12 V) stabilizes the operation of the constant current output unit 54, which will be described later. In the example shown in FIG. 2, the first step-up / step-down unit 51 includes a resistor R1, a Zener diode ZD1, a DC-DC converter U1, and capacitors C1 and C2. The first step-up / step-down unit 51 boosts the output of approximately several volts from the solar cell 10 to, for example, 12 V and outputs it to the second step-up unit 53.

[0030] In the event that large voltage or current fluctuations occur on the solar cell 10 side connected to input terminals LP1 and LP2, it is preferable to use an insulated type DC-DC converter U1 in order to reduce the impact on the interior of the automatic return control unit 50. By using an insulated type DC-DC converter U1 and connecting the input terminals LP1 and LP2 with a Zener diode ZD1, if an excessive voltage difference occurs on the solar cell 10 side, the current is short-circuited via the Zener diode ZD1, thereby reducing adverse effects on circuits located downstream of the DC-DC converter U1.

[0031] The boost confirmation unit 52 is a circuit that monitors the output voltage of the first step-up / step-down unit 51 and activates the second step-up unit 53 when the output voltage reaches a predetermined voltage (12 V in the above example). In the example shown in FIG. 2, the step-up confirmation unit 52 includes capacitors C3, C4, and C5, a control chip IC1, resistors R2 and R3, and a transistor Q1. In this embodiment, since the step-up confirmation unit 52 confirms the output voltage of the first step-up / step-down unit 51, if the first step-up / step-down unit 51 does not sufficiently boost the voltage and does not reach the target output, the second step-up unit 53 does not perform the boost operation, and the output from the constant current output unit 54 is also stopped, as described below. This allows the second step-up unit 53 and the constant current output unit 54 to be driven in a stable state, thereby enabling a stable output current to be continuously generated.

[0032] Second boost unit 53 is a circuit that further boosts the output from first boost / buck unit 51 and outputs the boosted voltage to constant current output unit 54. In the example shown in FIG. 2, second boost unit 53 includes capacitors C6 and C7 and DC-DC converter U2. The on / off operation of DC-DC converter U2 is controlled by a control signal from boost confirmation unit 52, and DC-DC converter U2 boosts the input voltage by a predetermined factor and outputs the boosted voltage. For example, if the output of DC-DC converter U1 is 12V and the factor is 2, DC-DC converter U2 outputs 24V.

[0033] The constant current output unit 54 is a circuit that operates on the voltage output from the DC-DC converter U2 and outputs a constant current from output terminals LP3 and LP4 to the battery management unit 30. In the example shown in FIG. 2, the constant current output unit 54 includes a control chip IC2, resistors R4 and R5, and a variable resistor BLK1. In the example shown in FIG. 2, a backflow prevention diode SD1 is connected between the constant current output unit 54 and the output terminal LP3. As an example, when the output from the DC-DC converter U2 is 24 V (first voltage), a constant current of 70 mA (first current value) is output from the constant current output unit 54.

[0034] Next, the operation of the power supply device 100 according to this embodiment will be described with reference to Figures 3 and 4. Figure 3 is a timing chart showing the operation of the power supply device 100, where Figure 3(a) shows the output of the automatic return control unit 50, Figure 3(b) shows the stored voltage of the secondary battery cell 40, Figure 3(c) shows the operating state of the battery management unit 30, and Figure 3(d) shows the charging voltage of the charge / discharge control unit 20. Figure 4 is a flowchart showing the operation of the automatic return control unit 50 shown in Figure 2. Figures 3 and 4 assume a situation in which insufficient sunlight continues for a long period of time, causing the state of charge of the secondary battery cell 40 to progress to a deeply discharged state, putting the battery management unit 30 in an inactive state, and sunlight reaching the solar cell 10.

[0035] The horizontal axis of Figures 3(a) to 3(d) represents a common time axis, with the time when sunlight reaches the solar cell 10 being set as 0. The vertical axis of Figure 3(a) represents the current value supplied from the automatic return control unit 50 to the battery management unit 30. The vertical axis of Figure 3(b) represents the stored voltage of the secondary battery cell 40, with Vmin representing the protection voltage at which the battery management unit 30 activates over-discharge protection, and Vmax representing the voltage at which the battery management unit 30 activates over-charge protection. The vertical axis of Figure 3(c) represents the operating state of the battery management unit 30, with OFF representing a non-operating state and ON representing an operating state. The vertical axis of Figure 3(d) represents the charging voltage output by the charge / discharge control unit 20 to the battery management unit 30, with max representing the maximum charging voltage set in the charge / discharge control unit 20.

[0036] In Figure 3, the period from time t = 0 to t = t1 is the voltage adjustment preparation period. As shown in Figures 3(a) to 3(d), during the voltage adjustment preparation period, the output current of the automatic return control unit 50 is 0. Also, the stored voltage of the secondary battery cell 40 is in a deep discharge state. Also, the battery management unit 30 is in an inactive state. Also, the charge / discharge control unit 20 is in an inactive state and its output is 0.

[0037] The period from time t=t1 to t=t2 is the automatic return period. As shown in FIGS. 3(a) to 3(d), during the automatic return period, the output current of the automatic return control unit 50 is I1. The stored voltage of the secondary battery cell 40 gradually rises from a deep discharge state to the over-discharge protection voltage Vmin. The battery management unit 30 alternates between a non-operating state and an operating state. The charge / discharge control unit 20 is non-operating and its output is 0.

[0038] The normal charging period is from time t=t2 to t=t3. As shown in FIGS. 3(a) to 3(d), during the normal charging period, the output current of the automatic return control unit 50 is I1. The stored voltage of the secondary battery cell 40 exceeds the over-discharge protection voltage Vmin. The battery management unit 30 is in an operating state. The charge / discharge control unit 20 is also operating, and supplies the output of the solar cell 10 to the secondary battery cell 40 as a charging voltage. Here, in FIGS. 3(b) and 3(d), a constant rate of increase is shown as an example of the change in the graph during the normal charging period, but because the power generated by the solar cell 10 is supplied as a charging voltage by the charge / discharge control unit 20, the rate of increase and the increase / decrease are not necessarily constant.

[0039] The period from time t=t3 onwards is the end of the automatic return period. When the charging voltage output by the charge / discharge control unit 20 reaches its maximum, the output current of the automatic return control unit 50 becomes zero.

[0040] As shown in Fig. 4, when the automatic return operation starts, the automatic return control unit 50 adjusts the output from the solar cell 10 to a predetermined expected voltage as a pre-adjustment operation in step S1. In the example circuit shown in Fig. 2, the pre-adjustment operation is performed by the DC-DC converter U1 of the first step-up / step-down unit 51, and continues after step S2 as long as power is being supplied from the solar cell 10.

[0041] Step S2 is a boost confirmation operation, which verifies whether the result of the preliminary adjustment operation has been adjusted to the expected voltage. In the circuit example shown in Figure 2, the boost confirmation operation is performed by control chip IC1, and a control signal is sent to DC-DC converter U2. As a specific example, boost confirmation unit 52 monitors the output from first boost / buck unit 51 and verifies whether the output of DC-DC converter U1 has been adjusted to a predetermined voltage value (expected voltage, for example 12V). If the output of DC-DC converter U1 has not reached the expected voltage, boost confirmation unit 52 sends an OFF signal and repeats the preliminary adjustment operation of step S1; if the output has reached the expected voltage, it sends an ON signal and proceeds to step S3.

[0042] Step S3 is the boost output operation, which further boosts the voltage adjusted to the target voltage in the pre-adjustment operation and outputs a constant current at a first current value. In the circuit example shown in FIG. 2, the boost output operation is performed by the DC-DC converter U2 of the second boost unit 53 and the control chip IC2. As a specific example, when the boost confirmation unit 52 sends an ON signal as a control signal to the DC-DC converter U2, the DC-DC converter U2 performs a boost operation, boosting the target voltage (12V) to the first voltage (24V). The constant current output unit 54 is driven by the first voltage boosted by the second boost unit 53 and outputs the first current value.

[0043] In the example circuit shown in Figure 2, in steps S2 and S3, if the output of DC-DC converter U1 is not the expected voltage (12V), boost confirmation unit 52 sends an OFF signal to DC-DC converter U2. Therefore, DC-DC converter U2 does not perform boost operation, and the output is 0V and 0mA. When the output of DC-DC converter U2 reaches the expected voltage, boost confirmation unit 52 sends an ON signal to DC-DC converter U2, and DC-DC converter U2 performs boost operation and outputs a first current value (70mA) at a first voltage (24V).

[0044] During the voltage adjustment preparation period from t=0 to t=t1 in FIG. 3(a), the first step-up / step-down unit 51 is unable to adjust the voltage to the planned voltage, so the second step-up unit 53 does not boost the voltage and the constant current output unit 54 does not output a current, resulting in an output current of 0. When t=t1 arrives and the step-up confirmation unit 52 confirms that the voltage has been adjusted to the planned voltage, the second step-up unit 53 boosts the voltage and the constant current output unit 54 outputs a current, and a constant current of the first current value (I1) is output from the output terminals LP3 and LP4 to the battery management unit 30. This allows the constant current output from the automatic return control unit 50 to quickly change from 0 to the first current value at time t=t1, enabling a stable constant current to be output. Furthermore, the output of the solar cell 10 is not directly supplied to the battery management unit 30.

[0045] During the automatic recovery period from t=t1 to t=t2 in FIG. 3 , the automatic recovery control unit 50 supplies the automatic recovery current of the first voltage and the first current to the battery management unit 30, and the recovery charge operation continues. When the secondary battery cell 30 is in a deeply discharged state, the battery management unit 30 is in an inactive state, but when the automatic recovery current is supplied, it temporarily enters an active state. At this time, the battery management unit 30 manages the secondary battery cell 30, but because the stored voltage is below the over-discharge protection voltage Vmin and the secondary battery cell 30 is in a deeply discharged state, it transitions back to an inactive state. However, even during this temporary recovery of the battery management unit 30 to an active state, the automatic recovery current is supplied to the secondary battery cell 40 in the charging direction for a short time, and the stored voltage rises slightly due to the recovery charge operation.

[0046] During the automatic return period, the automatic return current continues to be supplied from the automatic return control unit 50 to the battery management unit 30, so that the non-operation and temporary return of the battery management unit 30 are repeated. During this repetition, short-term charging and slight increases in the stored voltage are repeated due to the return charge operation, and when the stored voltage of the secondary battery cell 40 reaches the over-discharge protection voltage Vmin at time t=t2, the battery management unit 30 permits the extraction of power from the secondary battery cell 40, and the operating state can be continued.

[0047] After time t=t2, the stored voltage of the secondary battery cell 40 is greater than the over-discharge protection voltage Vmin, and the battery management unit 30 permits power to be drawn from the secondary battery cell 40. Therefore, the battery management unit 30 and the charge / discharge control unit 20 are operated by the output of the secondary battery cell 40, and it is possible to continue charging the secondary battery cell 40 with power from the solar cell 10 and supplying power from the secondary battery cell 40 to the load.

[0048] Step S4 is a maximum output check operation, and if the charging voltage output by the charge / discharge control unit 20 has not reached the maximum voltage max, the process proceeds to step S3, and if it has reached the maximum voltage max, the process proceeds to step S5. As shown in Fig. 1, the output of the charge / discharge control unit 20 and the output of the automatic recovery control unit 50 are both connected to the battery management unit 30, so that the automatic recovery control unit 50 can obtain the charging voltage output by the charge / discharge control unit 20 by monitoring the voltage applied to the output terminals LP3 and LP4 of the automatic recovery control unit 50.

[0049] Step S5 is an output stop operation, in which the automatic return control unit 50 stops supplying current to the battery management unit 30 at the first voltage and first current value. In the example circuit shown in FIG. 2, when a voltage greater than the voltage set by the backflow prevention diode SD1 is applied to the output terminal unit LP3, the constant current output unit 54 stops outputting at a constant current. As a specific example, when the charging voltage of the charge / discharge control unit 20 is greater than the first voltage (24 V), the automatic return control unit 50 performs an output stop operation.

[0050] After time t=t3, the charge / discharge control unit 20 can supply the charging voltage to the battery management unit 30 at the set maximum voltage, and the current value output from the automatic recovery control unit 50 becomes 0. In addition, the stored voltage of the secondary battery cell 40 is managed by the battery management unit 30 and controlled between the over-discharge protection voltage Vmin and the over-charge protection voltage Vmax. The charge / discharge control unit 20 is operated by the power supplied from the secondary battery cell 40, and charges the secondary battery cell 30 with the power generated by the solar cell 10 via the battery management unit 30.

[0051] As described above, in the power supply device 100 of this embodiment, the automatic return control unit 50 is connected between the solar cell 10 and the battery management unit 30, and even when the battery management unit 30 is in a stopped state, a portion of the power output by the solar cell 10 is converted to a first voltage and a first current value and supplied to the battery management unit to perform a return charge operation. As a result, even when the secondary battery cell 30 is in a deeply discharged state and the battery management unit 30 is unable to extract power or acquire information from the secondary battery cell 30, the secondary battery cell 40 can be gradually charged by the return charge operation. Furthermore, the power consumed by the operation of the battery management unit 30 can be reduced, allowing the return charge operation to be continued efficiently.

[0052] Furthermore, the automatic return control unit 50 is connected in parallel with the charge / discharge control unit 20, and no power is consumed by the automatic return control unit 50 when it is operating. Therefore, even if the output of the solar cell 10 is relatively small, the automatic return charge operation can be continued efficiently to gradually charge the secondary battery cell 40.

[0053] (Second embodiment) Next, a second embodiment of the present invention will be described. Descriptions of content that overlaps with the first embodiment will be omitted. In the first embodiment, the automatic recovery control unit 50 continued the recovery charge operation until the charging voltage output from the charge / discharge control unit 20 reached the maximum voltage max. In this embodiment, if the secondary battery cell 40 is short-circuited, the automatic recovery control unit 50 stops the recovery charge operation at the first voltage and first current value.

[0054] In this embodiment, the automatic return control unit 50 includes a temperature measurement unit that measures the temperature of the secondary battery cell 40 to acquire cell temperature information. The automatic return control unit 50 also records in advance the allowable temperature rise of the secondary battery cell 40 as a protection temperature.

[0055] At time t=t1 when the automatic recovery control unit 50 starts to output the first current value to the battery management unit 30, the temperature measurement unit measures the temperature of the secondary battery cell 40 and acquires cell temperature information at the start of the recovery charging operation. Additionally, the automatic recovery control unit 50 continues to acquire cell temperature information of the secondary battery cell 40 by the temperature measurement unit while continuing the recovery charging operation and outputting the first current value to the battery management unit 30.

[0056] The automatic recovery control unit 50 calculates the temperature rise from the start of the recovery charging operation from the acquired cell temperature information, and stops the recovery charging operation if the temperature rise exceeds the protection temperature. This is because if a fault such as a short circuit occurs inside the secondary battery cell 40, the power supplied during the recovery charging operation is not stored in the secondary battery cell 40, and the power is consumed inside the secondary battery cell 40, causing the cell temperature to rise.

[0057] As described above, in the power supply device 100 of this embodiment, the automatic recovery control unit 50 stops the recovery charging operation when the temperature rise of the cell exceeds the protection temperature, thereby protecting the secondary battery cell 40 where a failure has occurred.

[0058] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0059] 100...Power supply device 10...Solar cell 20...Charge / discharge control unit 30...Battery management section 40...Secondary battery cell 50...Automatic return control unit 51...First step-up / step-down section 52...Boost confirmation section 53...Second booster section 54...Constant current output section

Claims

1. a solar cell that generates electricity using light and outputs power; a secondary battery cell that stores the power; a battery management unit that performs a protection operation by cutting off extraction of the power stored in the secondary battery cell when the stored voltage of the secondary battery cell is equal to or lower than a protection voltage; an automatic recovery control unit connected between the solar cell and the battery management unit, converting a portion of the power output by the solar cell into an automatic recovery current having a first voltage and a first current value, and supplying the automatic recovery current to the battery management unit to perform a recovery charging operation; the automatic return control unit has a first step-up / step-down unit, a step-up confirmation unit, a second step-up unit, and a constant current output unit, the first voltage step-up / step-down unit steps up or steps down the power input from an input terminal, adjusts the power to a predetermined expected voltage, and outputs the adjusted voltage; the boost confirmation unit monitors the first output voltage of the first boost / buck unit, and operates the second boost unit when the first output voltage reaches the expected voltage; the second booster further boosts the scheduled voltage to a second output voltage and outputs the second output voltage to the constant current output unit; The power supply device according to claim 1, wherein the constant current output unit operates at the second output voltage and outputs the automatic recovery current from an output terminal to the battery management unit.

2. 2. The power supply device according to claim 1, Even if the battery management unit is performing the protection operation, The power supply device, wherein the automatic return control unit continues the return charging operation.

3. 3. The power supply device according to claim 1, a charge / discharge control unit connected between the solar cell and the battery management unit, converting the power output from the solar cell into a charging voltage and a charging current, and supplying the charging voltage and the charging current to the battery management unit; The power supply device, wherein the charge / discharge control unit is operated by the power stored in the secondary battery cell.

4. 4. The power supply device according to claim 3, The power supply device, wherein the automatic recovery control unit stops the recovery charging operation when the charging voltage reaches a predetermined maximum voltage.

5. 5. The power supply device according to claim 3, The power supply device is characterized in that the charge / discharge control unit uses maximum power point tracking control.

6. 6. The power supply device according to claim 1, the automatic return control unit includes a temperature measurement unit that acquires the temperature of the secondary battery cell as a cell temperature; A power supply device characterized in that, when the temperature rise of the cell temperature reaches or exceeds a predetermined protection temperature, the return charging operation is stopped.

7. 7. The power supply device according to claim 1, The power supply device is characterized in that the recovery charging operation is performed by the battery management unit repeatedly switching between an operating state and a non-operating state, and the automatic recovery current charges the secondary battery cell when the battery management unit is temporarily in the operating state.

Images