Control unit

Abstract

To provide a control unit capable of improving DC-DC converter efficiency, in which a solar power generation device is connected to one side of the DC-DC converter and multiple secondary batteries are connected to the other side of the DC-DC converter.SOLUTION: A control unit 27 is a control unit capable of selectively charging multiple secondary batteries with the power generated by a solar power generation system. When the amount of power generated by the photovoltaic power generation device is at or below a predetermined value, the multiple secondary batteries are selected and charged so as to reduce auxiliary power consumption.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a control device. [Background technology]

[0002] In order to improve the conversion efficiency of a DC-DC converter, a power supply system that switches the connection state of a plurality of batteries has been proposed (see Patent Document 1 below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-30050 A Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, it is assumed that a first battery connected to one side of the DC-DC converter is on the low-voltage side, and a second battery connected to the other side of the DC-DC converter is on the high-voltage side. Based on this assumption, Patent Document 1 adjusts the output voltage from the second battery by switching the connection state of the second battery so that the conversion efficiency of the DC-DC converter is increased according to the power required by the load connected to one side of the DC-DC converter.

[0005] However, the invention described in Patent Document 1 does not disclose how the connection state of the multiple secondary batteries should be configured according to the amount of power generated by the solar power generation device to improve the efficiency of the DCDC converter when a solar power generation device is connected to one side of the DCDC converter and multiple secondary batteries are connected to the other side of the DCDC converter.

[0006] The present disclosure aims to improve the efficiency of a DC-DC converter when a solar power generation device is connected to one side of the DC-DC converter and multiple secondary batteries are connected to the other side of the DC-DC converter. [Means for solving the problem]

[0007] The present disclosure provides a control device that selectively charges multiple secondary batteries with electricity generated by a solar power generation device, and when the amount of electricity generated by the solar power generation device is below a predetermined value, selects and charges multiple secondary batteries so as to reduce auxiliary power consumption. [Effects of the Invention]

[0008] According to the present disclosure, the efficiency of a DC-DC converter is improved when a solar power generation device is connected to one side of the DC-DC converter and a plurality of secondary batteries are connected to the other side of the DC-DC converter. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating the configuration of a power supply system according to this embodiment. [Figure 2] FIG. 2 is a diagram for explaining a charging mode in the power supply system shown in FIG. [Figure 3] FIG. 3 is a flowchart for explaining the control process performed by the control device shown in FIG. [Figure 4] FIG. 4 is a diagram illustrating the relationship between the amount of solar power generation and the battery to be charged. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicated descriptions will be omitted.

[0011] As shown in FIG. 1, the power supply system 2 includes a solar power generation device 21, a DC-DC converter 22, an inverter 23, high-voltage batteries 24 and 25, relays 26a, 26b, 26c, 26d, and 26e, and a control device 27.

[0012] The solar power generation device 21 is a photovoltaic power generation device that is installed outdoors and generates power by receiving sunlight. The solar power generation device 21 generates power by converting the light energy of sunlight into electrical energy using a solar cell. The electrical energy generated by the solar power generation device 21 is transmitted to the DC-DC converter 22.

[0013] The DC-DC converter 22 converts and outputs the voltage of the power input from the solar power generation device 21. The DC-DC converter 22 boosts the voltage of the power input from the solar power generation device 21 and outputs it to the high-voltage batteries 24, 25 and the inverter 23 side.

[0014] The inverter 23 converts DC power input from the DC-DC converter 22 and the high-voltage batteries 24, 25 into AC power and outputs it.

[0015] The high-voltage batteries 24, 25 are charged with low-cost electricity such as late-night electricity supplied from the grid or with electricity generated by the solar power generation device 21. The high-voltage batteries 24, 25 are secondary batteries.

[0016] The high-voltage batteries 24, 25 are provided between the DC-DC converter 22 and the inverter 23. The DC-DC converter 22 and the inverter 23 are connected by power lines L1, L2. A connection point P1 of the power line L1 and a connection point P2 of the power line L2 are connected by a power line L3. The high-voltage batteries 24, 25 are arranged in series on the power line L3.

[0017] In the power line L3, connections P3 and P4 are provided between the high-voltage battery 24 and the high-voltage battery 25. The connection P4 and the inverter 23 are connected by the power line L4. In the power line L2, a connection P5 is provided between the connection P2 and the DC-DC converter 22. The connection P3 and the connection P5 are connected by the power line L5.

[0018] A relay 26a is provided on the power line L1 between the connection point P1 and the inverter 23. A relay 26b is provided on the power line L3 between the connection point P3 and the connection point P4. A relay 26c is provided on the power line L4. A relay 26d is provided on the power line L5. A relay 26e is provided on the power line L2 between the connection point P2 and the inverter 23.

[0019] The control device 27 is a control device that controls the power supply system 2. Solar power generation information is input to the control device 27 from the solar power generation device 21. The solar power generation information includes, for example, information about the amount of power generated by the solar power generation device 21. Battery state information indicating the charge state of the high-voltage batteries 24, 25 is input to the control device 27. The control device 27 outputs an ON / OFF signal to each of the relays 26a, 26b, 26c, 26d, and 26e.

[0020] Next, the operation of the power supply system 2 will be described with reference to Fig. 2. Fig. 2 is a diagram illustrating the circuit state and the efficiency of the DC-DC converter 22 when the high-voltage battery 24 and the high-voltage battery 25 are charged.

[0021] 2, when charging the high-voltage battery 24, the relay 26d is turned ON and the other relays 26a, 26b, 26c, and 26e are turned OFF. Whether the amount of power generated by the solar power generation device 21 is high or low, only one relay is turned ON, so the efficiency of the DC-DC converter 22 is not significantly affected.

[0022] When charging the high-voltage battery 25, the relays 26a and 26c are turned ON, and the other relays 26b, 26d, and 26e are turned OFF. When the amount of power generated by the solar power generation device 21 is large, this does not have a significant impact on the efficiency of the DC-DC converter 22. On the other hand, when the amount of power generated by the solar power generation device 21 is small, two relays are turned ON, which significantly impacts the efficiency of the DC-DC converter 22.

[0023] Next, the control processing of the control device 27 will be described with reference to Fig. 3. In step S01, the control device 27 determines whether solar power generation is being performed in the solar power generation device 21 and whether the high-voltage batteries 24, 25 are being charged. If it is determined that solar power generation is being performed and the high-voltage batteries 24, 25 are being charged (step S01: YES), the process proceeds to step S02. If it is not determined that solar power generation is being performed and the high-voltage batteries 24, 25 are being charged (step S01: NO), the process ends.

[0024] In step S02, the control device 27 calculates the charging loss when the high-voltage batteries 24, 25 are connected in series and charged, and the charging loss when the high-voltage batteries 24, 25 are connected individually and charged. The charging loss is calculated by multiplying the charging power by the power conversion efficiency and adding the auxiliary power consumption. The relay connection mode when the high-voltage batteries 24, 25 are connected individually and charged is as described with reference to FIG. 2. When the high-voltage batteries 24, 25 are connected in series and charged, the relay 26b is turned ON and the other relays 26a, 26c, 26d, and 26e are turned OFF. The auxiliary power consumption is calculated including the power for turning the relays ON.

[0025] In step S03 following step S02, the control device 27 determines whether the charging loss when the high-voltage batteries 24, 25 are connected separately and charged is greater than the charging loss when the high-voltage batteries 24, 25 are connected in series and charged. If the charging loss when the high-voltage batteries 24, 25 are connected separately and charged is greater than the charging loss when the high-voltage batteries 24, 25 are connected in series and charged (step S03: YES), the process proceeds to step S04. If the charging loss when the high-voltage batteries 24, 25 are connected separately and charged is not greater than the charging loss when the high-voltage batteries 24, 25 are connected in series and charged (step S03: NO), the process proceeds to step S05.

[0026] In step S04, the control device 27 switches the series connection between the high-voltage batteries 24 and 25. Specifically, the control device 27 turns on the relay 26b and turns off the other relays 26a, 26c, 26d, and 26e.

[0027] In step S05, the control device 27 switches the high-voltage batteries 24, 25 to individual connection. In step S06 following step S05, the control device 27 determines whether the amount of solar power generated by the solar power generation device 21 is equal to or less than a predetermined value. The predetermined value may be changed depending on the season, weather, etc., in order to level out the amount of charge to each battery throughout the day. If the amount of solar power generated by the solar power generation device 21 is equal to or less than the predetermined value (step S06: YES), the process proceeds to step S07. If the amount of solar power generated by the solar power generation device 21 is not equal to or less than the predetermined value (step S06: NO), the process proceeds to step S08.

[0028] In step S07, control device 27 switches the relays so as to charge the battery that consumes relatively little auxiliary power when connected. In this embodiment, the battery that consumes relatively little auxiliary power when connected is high-voltage battery 24, so control device 27 turns relay 26d ON and turns the other relays 26a, 26b, 26c, and 26e OFF. After step S07 is completed, the process proceeds to step S09.

[0029] In step S08, control device 27 switches the relays so as to charge the battery that consumes relatively more power than the other batteries when connected. In this embodiment, the battery that consumes relatively more power than the other batteries when connected is high-voltage battery 25, so control device 27 turns relays 26a and 26c ON and turns the other relays 26b, 26d, and 26e OFF. When the processing of step S08 is completed, the process proceeds to step S09.

[0030] In step S09, the control device 27 determines whether there is a large variation in the state of the batteries. An example of the variation in state of the batteries is the variation in the SOC of each battery. The variation in state of the batteries is not limited to this, and may be, for example, the variation in temperature of each battery. If there is a large variation in state of the batteries (step S09: YES), the process proceeds to step S10. If there is not a large variation in state of the batteries (step S09: NO), the process ends.

[0031] In step S10, the control device 27 operates the relay to switch the battery to be charged.

[0032] Fig. 4 shows an example of a time series graph when the processing described with reference to Fig. 3 is executed and the high-voltage batteries 24, 25 are individually connected and charged. Fig. 4(A) shows the amount of solar power generated by the solar power generation device 21. Fig. 4(B) shows which of the high-voltage batteries 24, 25 is the battery being charged. Fig. 4(C) shows the SOC of the high-voltage batteries 24, 25.

[0033] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications to these specific examples made by a person skilled in the art as appropriate are also included within the scope of the present disclosure as long as they comprise the features of the present disclosure. The elements of the above-described specific examples, as well as their arrangement, conditions, shape, etc., are not limited to those exemplified and can be modified as appropriate. The elements of the above-described specific examples can be combined in various ways as appropriate, as long as no technical contradictions arise.

[0034] [Note] [Appendix 1] A control device that selectively charges a plurality of secondary batteries with power generated by a solar power generation device, A control device that, when the amount of power generated by a solar power generation device is equal to or less than a predetermined value, selects and charges a plurality of secondary batteries so as to reduce auxiliary power consumption.

[0035] In the present disclosure, the solar power generation device 21 is exemplified as the solar power generation device, and the high-voltage batteries 24, 25 are exemplified as the secondary battery.

[0036] According to Supplementary Note 1, when a solar power generation device 21 is connected to one side of a DC-DC converter 22 and multiple high-voltage batteries 24, 25 are connected to the other side of the DC-DC converter 22, if the amount of power generated by the solar power generation device 21 is equal to or less than a predetermined value, the multiple high-voltage batteries 24, 25 are selected and charged so as to reduce auxiliary power consumption. When the amount of power generated by the solar power generation device 21 is equal to or less than a predetermined value, the efficiency of the DC-DC converter 22 improves as the auxiliary power consumption decreases, so the efficiency of the DC-DC converter 22 can be improved even if the amount of power generated by the solar power generation device 21 fluctuates. According to Supplementary Note 1, it is possible to avoid a decrease in efficiency due to the DC-DC converter 22 being lightly loaded.

[0037] The configuration described with reference to Figure 1 is just one example, and other configurations may be used as long as the multiple secondary batteries, i.e., high-voltage batteries 24, 25, are connected in series, in parallel, or the connection of only each individual battery can be switched. [Explanation of symbols]

[0038] 2: Power system 21: Solar power generation equipment 22: DC-DC converter 23: Inverter 24,25: High voltage battery 26a, 26b, 26c, 26d, 26e: Relay 27: Control device L1,L2,L3,L4,L5: Power line P1, P2, P3, P4: Connection parts

Claims

[Claim 1] A control device that selectively charges a plurality of secondary batteries with power generated by a solar power generation device, a control device that, when the amount of power generated by the solar power generation device is equal to or less than a predetermined value, selectively charges the plurality of secondary batteries so as to reduce auxiliary power consumption;

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