Solar charging system

Abstract

To provide a solar charging system that can reduce loss of electric power.SOLUTION: In a solar charging system 1, generated electric power of a solar panel 10 is supplied to an auxiliary battery 14. A two-way DC / DC converter 18 operates in a first state in which the generated power of the solar panel 10 and the power of the auxiliary battery 14 are supplied to a driving battery 20 of a vehicle, or a second state in which the power of the driving battery 20 is supplied to the auxiliary battery 14. A control unit 34 operates in a first control mode in which it controls the two-way DC / DC converter 18 so that a voltage or a SOC of the auxiliary battery 14 is within a first range, or a second control mode in which it controls the two-way DC / DC converter 18 so that the voltage or the SOC of the auxiliary battery 14 is within a second range wider than the first range. When solar charging is being performed by the solar panel 10, the control unit 34 operates in the second control mode.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a solar charging system. [Background technology]

[0002] There is a known technology for charging an auxiliary battery and a drive battery using power generated by a solar panel mounted on a vehicle. Patent Document 1 discloses a vehicle charging control system that distributes power to the drive battery and the auxiliary battery at a first distribution ratio when the voltage of the auxiliary battery is equal to or higher than a predetermined value, and distributes power to the drive battery and the auxiliary battery at a second distribution ratio that is higher than the first distribution ratio when the voltage of the auxiliary battery is lower than the predetermined value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-048286 A Summary of the Invention [Problem to be solved by the invention]

[0004] The inventor recognized that in a solar charging system for a vehicle, when solar radiation is unstable, repeated charging and discharging between the auxiliary battery and the drive battery can result in increased power loss.

[0005] An object of the present invention is to provide a solar charging system capable of reducing power loss. [Means for solving the problem]

[0006] In order to solve the above problems, a solar charging system according to an embodiment of the present invention includes a solar panel, an auxiliary battery to which power generated by the solar panel is supplied, a vehicle drive battery, a DC / DC converter that operates in a first state in which the power generated by the solar panel and the power of the auxiliary battery are supplied to the drive battery, or in a second state in which the power of the drive battery is supplied to the auxiliary battery, and a control unit that controls the DC / DC converter. The control unit operates in a first control mode in which the DC / DC converter is controlled so that the voltage or SOC of the auxiliary battery is within a first range, or in a second control mode in which the DC / DC converter is controlled so that the voltage or SOC of the auxiliary battery is within a second range wider than the first range, and operates in the second control mode when solar charging is performed by the solar panel. Effect of the Invention

[0007] According to the present invention, a solar charging system capable of reducing power loss can be provided. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a schematic configuration of a solar charging system according to an embodiment. [Diagram 2] 2 is a diagram showing an example of a first range and a second range of SOC (State Of Charge) of the auxiliary battery of FIG. 1. [Diagram 3] 3(a) to 3(c) are diagrams for explaining the charging operation of the auxiliary battery in the second control mode. [Figure 4] 4(a) and (b) are diagrams for explaining the pumping operation in the second control mode. [Diagram 5] 5(a) and (b) are diagrams for explaining the operation in the first control mode. [Figure 6] 4 is a flowchart showing a control process of the solar charging system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Fig. 1 shows a schematic configuration of a solar charging system 1 according to an embodiment. The solar charging system 1 is mounted on an electric vehicle (not shown). The electric vehicle may be, for example, a battery electric vehicle (BEV) that uses an electric motor as a power source, a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or a fuel cell electric vehicle (FCEV). The electric vehicle may be a vehicle driven by a driver or an autonomous vehicle.

[0010] The solar charging system 1 includes a solar panel 10, a DC / DC converter 12, an auxiliary battery 14, an auxiliary device 16, a bidirectional DC / DC converter 18, a drive battery 20, and a control device 30.

[0011] The solar panel 10 is a solar cell module that is an assembly of solar cell cells that generate power from irradiated sunlight. The power generated by the solar panel 10 depends on the solar radiation intensity. The solar panel 10 is connected to an input terminal of a DC / DC converter 12. The power generated by the solar panel 10 is output to the DC / DC converter 12. The solar panel 10 is installed, for example, on the roof of a vehicle.

[0012] An output terminal of the DC / DC converter 12 is connected to the auxiliary battery 14, the auxiliary device 16, and the bidirectional DC / DC converter 18. The DC / DC converter 12 is capable of converting the power generated by the solar panel 10 and supplying the power to the auxiliary battery 14, the auxiliary device 16, and the bidirectional DC / DC converter 18. The DC / DC converter 12 steps down or steps up the output voltage of the solar panel 10 to a predetermined voltage under the control of the control device 30, and outputs the stepped-down or stepped-up voltage to the auxiliary battery 14, etc. The DC / DC converter 12 performs MPPT (Maximum Power Point Tracking) control so that the output power of the solar panel 10 is maximized.

[0013] The auxiliary battery 14 is a chargeable and dischargeable secondary battery, such as a lithium ion battery. The auxiliary battery 14 is a low-voltage battery with a lower voltage than the drive battery 20. The auxiliary battery 14 can be charged with power generated by the solar panel 10. The auxiliary battery 14 may also be charged with power from the drive battery 20. The auxiliary battery 14 can supply power to the accessories 16. The auxiliary battery 14 may also charge the drive battery 20.

[0014] The auxiliary devices 16 are loads such as electronic devices provided in the vehicle. The auxiliary devices 16 may include, for example, headlamps, a navigation device, an audio device, an air conditioner, an automatic driving system, an advanced driving assistance system, etc. The auxiliary devices 16 operate using power supplied from the auxiliary battery 14.

[0015] Bidirectional DC / DC converter 18 has a first terminal and a second terminal. The first terminal is connected to the output terminal of DC / DC converter 12 and auxiliary battery 14. The second terminal is connected to driving battery 20. Bidirectional DC / DC converter 18 operates under the control of control device 30 in a first state in which it boosts the voltage at the first terminal and outputs the boosted voltage from the second terminal, or in a second state in which it lowers the voltage at the second terminal and outputs the lowered voltage from the first terminal.

[0016] The driving battery 20 is a chargeable and dischargeable secondary battery such as a lithium ion battery. The driving battery 20 can also be called a high voltage battery. The driving battery 20 can supply power to an electric motor that generates driving force for the vehicle via an inverter (not shown) or the like. The driving battery 20 can be charged with power supplied from a charging station or the like outside the vehicle via an on-board charging device (not shown).

[0017] The control device 30 controls the DC / DC converter 12 and the bidirectional DC / DC converter 18 based on the output voltage of the solar panel 10 detected by a voltage sensor and a current sensor (not shown), the voltage and current of the auxiliary battery 14, and the voltage of the drive battery 20. The control device 30 has a SOC estimator 32 and a controller 34.

[0018] The configuration of the control device 30 can be realized in hardware terms by the CPU, memory, and other LSI of any computer, and in software terms by programs loaded into memory, but here the functional blocks realized by the cooperation of these are depicted. Therefore, it will be understood by those skilled in the art that these functional blocks can be realized in various forms by hardware alone, software alone, or a combination of both.

[0019] The SOC estimating unit 32 sequentially estimates an estimated value of the SOC of the auxiliary battery 14 based on the voltage and current of the auxiliary battery 14, and sequentially supplies the estimated SOC value to the control unit .

[0020] The control unit 34 controls the bidirectional DC / DC converter 18 based on the received estimated value of SOC, the output voltage of the solar panel 10, the voltage and current of the auxiliary battery 14, and the voltage of the drive battery 20, thereby controlling the charging and discharging of the auxiliary battery 14. Hereinafter, the estimated value of SOC will be simply referred to as SOC.

[0021] The control unit 34 operates in a first control mode or a second control mode. The control unit 34 operates in the first control mode when the solar panel 10 is not performing solar charging and the bidirectional DC / DC converter 18 is not operating in the first state. The control unit 34 operates in the second control mode when the solar panel 10 is performing solar charging or the bidirectional DC / DC converter 18 is operating in the first state. Performing solar charging corresponds to the solar panel 10 generating power.

[0022] In the first control mode, the control unit 34 controls the bidirectional DC / DC converter 18 to the second state or a stopped state so that the SOC of the auxiliary battery 14 is within a first range. In the second control mode, the control unit 34 controls the bidirectional DC / DC converter 18 to the first state, the second state, or a stopped state so that the SOC of the auxiliary battery 14 is within a second range that is wider than the first range.

[0023] The control unit 34 may control the bidirectional DC / DC converter 18 so that the voltage of the auxiliary battery 14 is within a first range or a second range. Alternatively, the control unit 34 may control the bidirectional DC / DC converter 18 so that the voltage of the auxiliary battery 14 is within the first range or the second range of voltage and the SOC is within the first range or the second range of SOC.

[0024] Fig. 2 shows an example of a first range R1 and a second range R2 of the SOC of the auxiliary battery 14 in Fig. 1. An upper limit value S2H of the second range R2 is higher than an upper limit value S1H of the first range R1. A lower limit value S2L of the second range R2 is lower than a lower limit value S1L of the first range R1.

[0025] The upper limit value S2H of the second range R2 may be greater than the upper limit value S1H of the first range R1, and the lower limit value S2L of the second range R2 may be equal to the lower limit value S1L of the first range R1. Alternatively, the upper limit value S2H of the second range R2 may be equal to the upper limit value S1H of the first range R1, and the lower limit value S2L of the second range R2 may be smaller than the lower limit value S1L of the first range R1.

[0026] Next, the charging and discharging operations of the solar charging system 1 will be described with reference to Figures 3 to 5. In Figures 3 to 5, the control device 30 is omitted from the illustration.

[0027] (Second control mode) 3(a) to 3(c) are diagrams for explaining the charging operation of the auxiliary battery 14 in the second control mode. As described above, in the second control mode, the SOC of the auxiliary battery 14 is controlled within the second range.

[0028] FIG. 3(a) shows a state where the amount of solar radiation is relatively large and the power generated by the solar panel 10 is relatively large. The bidirectional DC / DC converter 18 is controlled to a stopped state. In the state of FIG. 3(a), the power generated by the solar panel 10 is greater than the power consumed by the auxiliary device 16. Therefore, the auxiliary battery 14 is charged with the generated power, and the SOC of the auxiliary battery 14 increases. This is highly convenient because the auxiliary battery 14 can be charged using solar energy. Note that in FIGS. 3 to 5, the arrows indicate the power supply paths, and the thickness of the arrows roughly indicates the magnitude of the power.

[0029] When the situation changes from one in which the amount of solar radiation is relatively high to one in which the amount of solar radiation is relatively low, the state transitions to that shown in Figure 3(b).

[0030] Fig. 3(b) shows a state where the solar radiation is relatively low and the power generated by the solar panel 10 is relatively small. The bidirectional DC / DC converter 18 is controlled to a stopped state. In the state of Fig. 3(b), the power generated by the solar panel 10 is assumed to be smaller than the power consumption of the auxiliary device 16. Therefore, the SOC of the auxiliary battery 14 decreases due to the power consumption of the auxiliary device 16. When the solar radiation recovers, the state returns to that of Fig. 3(a).

[0031] When the solar radiation does not recover and the SOC of the auxiliary battery 14 reaches the lower limit of the second range, the operation transitions to that shown in Fig. 3(c). That is, when solar charging is in progress and the SOC of the auxiliary battery 14 reaches the lower limit of the second range, the control unit 34 controls the bidirectional DC / DC converter 18 to the second state so as to charge the auxiliary battery 14. Specifically, when solar charging is in progress and the bidirectional DC / DC converter 18 is stopped, the control unit 34 controls the bidirectional DC / DC converter 18 to the second state when the SOC of the auxiliary battery 14 reaches the lower limit of the second range.

[0032] Fig. 3(c), which follows Fig. 3(b), shows a state in which the solar radiation is relatively low, the power generated by the solar panel 10 is relatively small, and the auxiliary battery 14 is charged using the power of the driving battery 20 as well. In the state of Fig. 3(c), the bidirectional DC / DC converter 18 operates in a second state in which the power of the driving battery 20 is supplied to the auxiliary battery 14. As a result, the auxiliary battery 14 is charged using the power of the driving battery 20 and the power generated by the solar panel 10, and the SOC of the auxiliary battery 14 increases. Therefore, the SOC of the auxiliary battery 14 can be increased even if the solar radiation is insufficient.

[0033] When the SOC of the auxiliary battery 14 reaches the upper limit of the second range due to charging, the operation shifts to the pumping operation shown in FIG. 4(a).

[0034] On the other hand, if the condition of relatively high solar radiation continues in the state of Figure 3(a) and the SOC of the auxiliary battery 14 reaches the upper limit of the second range due to charging using power generated by the solar panel 10, the pumping operation of Figure 4(a) will also be initiated.

[0035] Specifically, during solar charging, when the SOC of the auxiliary battery 14 reaches the upper limit value of the second range, the control unit 34 controls the bidirectional DC / DC converter 18 to the first state so that the driving battery 20 is charged with the power generated by the solar panel 10 and the power of the auxiliary battery 14.

[0036] 4(a) and (b) are diagrams for explaining the pumping operation in the second control mode. FIG. 4(a) shows a state where there is solar radiation and the solar panel 10 is generating power. In the state of FIG. 4(a), the bidirectional DC / DC converter 18 operates in a first state in which the power generated by the solar panel 10 and the power of the auxiliary battery 14 are supplied to the driving battery 20. As a result, the driving battery 20 is charged by the power of the auxiliary battery 14 and the power generated by the solar panel 10. This operation is called a pumping operation. The SOC of the driving battery 20 increases and the SOC of the auxiliary battery 14 decreases. Since the driving battery 20 can be charged by the power generated by the energy of sunlight and the power of the auxiliary battery 14 including the generated power, it is highly convenient and economical.

[0037] When the SOC of the auxiliary battery 14 reaches the lower limit of the second range in the state of FIG. 4(a), the operation transitions to the above-described operation of FIG. 3(a) and (b). That is, when the SOC of the auxiliary battery 14 reaches the lower limit of the second range during solar charging, the control unit 34 controls the bidirectional DC / DC converter 18 to a stopped state so that the auxiliary battery 14 is charged with the power generated by the solar panel 10. Specifically, when the bidirectional DC / DC converter 18 is operating in the first state during solar charging, the control unit 34 controls the bidirectional DC / DC converter 18 to a stopped state when the SOC of the auxiliary battery 14 reaches the lower limit of the second range. This allows the auxiliary battery 14 to be charged again using the power generated by the solar panel 10. When the solar radiation is sufficient, the states of FIG. 3(a) and FIG. 4(a) are alternately repeated, so that the driving battery 20 can be repeatedly charged with the power generated by the energy of the sun.

[0038] FIG. 4(b) shows a state in which the solar panel 10 stops generating power due to the absence of solar radiation in the state shown in FIG. 4(a). When the bidirectional DC / DC converter 18 is operating in the first state in the second control mode, i.e., during pumping operation, the control unit 34 continues the second control mode even after solar charging ends. Therefore, the bidirectional DC / DC converter 18, which continues operating in the first state, continues to supply power from the auxiliary battery 14 to the driving battery 20. Therefore, the SOC of the auxiliary battery 14 decreases. When the control unit 34 continues the second control mode even after solar charging ends, if the SOC of the auxiliary battery 14 reaches the lower limit of the second range in a state where there is no power generated by the solar panel 10, the control unit 34 switches to the first control mode.

[0039] With this control, even if solar charging ends during pumping operation, the pumping operation can be continued, and the power of the auxiliary battery 14, including the power generated by the solar panel 10, can be supplied to the driving battery 20 until the lower limit value of the second range is reached.

[0040] 3(a) to 3(c), if the generated power of the solar panel 10 runs out during the charging operation of the auxiliary battery 14, solar charging also ends at that point. If the bidirectional DC / DC converter 18 is not operating in the first state in the second control mode, that is, if the pumping operation is not in progress, the control unit 34 transitions to the first control mode when solar charging ends.

[0041] During solar charging, the battery is controlled within a second range that is wider than the first range, so when solar charging ends and the second control mode ends, the SOC of the auxiliary battery 14 may be in a relatively low depleted or low charged state, or the SOC of the auxiliary battery 14 may be in a relatively high charged state. If the auxiliary battery 14 is left in these states for a long period of time, it may deteriorate.

[0042] Therefore, when the second control mode ends, if the voltage of the auxiliary battery 14 is higher than a predetermined first voltage or lower than a predetermined second voltage, the control unit 34 controls the bidirectional DC / DC converter 18 to adjust the voltage of the auxiliary battery 14. The second voltage is lower than the first voltage.

[0043] The first voltage may be a value corresponding to the upper limit of the first range, or may be greater than the value corresponding to the upper limit of the first range and less than the value corresponding to the upper limit of the second range.

[0044] The second voltage may be a value corresponding to the lower limit of the first range, or may be less than the value corresponding to the lower limit of the first range and greater than the value corresponding to the lower limit of the second range.

[0045] The value corresponding to the upper limit value of the first range represents the voltage of the auxiliary battery 14 when the SOC is at the upper limit value of the first range. The same applies to the value corresponding to the lower limit value of the first range. Note that when the first range and the second range are voltage ranges, the value corresponding to the upper limit value of the first range represents the upper limit value of the first range. The same applies to the value corresponding to the lower limit value of the first range.

[0046] Specifically, when solar charging ends and the voltage of the auxiliary battery 14 is higher than the first voltage, the control unit 34 controls the bidirectional DC / DC converter 18 to the first state until the voltage of the auxiliary battery 14 drops to a predetermined third voltage. As a result, power from the auxiliary battery 14 is supplied to the driving battery 20, and the voltage of the auxiliary battery 14 drops. The third voltage is lower than the first voltage and higher than the lower limit of the first range.

[0047] When solar charging is completed, if the voltage of the auxiliary battery 14 is lower than the second voltage, the control unit 34 controls the bidirectional DC / DC converter 18 to the second state until the voltage of the auxiliary battery 14 rises to a predetermined fourth voltage. As a result, power from the driving battery 20 is supplied to the auxiliary battery 14, and the voltage of the auxiliary battery 14 rises. The fourth voltage is higher than the second voltage and lower than the upper limit of the first range. The first voltage, the second voltage, the third voltage, and the fourth voltage can be determined as appropriate by experiment or simulation.

[0048] This makes it possible to prevent the auxiliary battery 14 from remaining in a depleted state, a low charged state, or a high charged state, thereby making it possible to prevent deterioration of the auxiliary battery 14.

[0049] (First control mode) 5(a) and (b) are diagrams for explaining the operation in the first control mode. As described above, in the first control mode, the SOC of the auxiliary battery 14 is controlled within the first range.

[0050] Fig. 5(a) shows a state in which the bidirectional DC / DC converter 18 is stopped. In the state of Fig. 5(a), the solar panel 10 is not generating power, so the SOC of the auxiliary battery 14 decreases due to the power consumption of the auxiliary device 16.

[0051] When the SOC of the auxiliary battery 14 reaches the lower limit of the first range, the operation transitions to that shown in Fig. 5(b). Specifically, in the first control mode, when the SOC of the auxiliary battery 14 reaches the lower limit of the first range, the controller 34 controls the bidirectional DC / DC converter 18 to the second state.

[0052] Fig. 5(b) shows a state in which the auxiliary battery 14 is being charged. In the state of Fig. 5(b), the bidirectional DC / DC converter 18 operates in a second state in which the bidirectional DC / DC converter 18 supplies power from the driving battery 20 to the auxiliary battery 14. As a result, the auxiliary battery 14 is charged with power from the driving battery 20, and the SOC of the auxiliary battery 14 increases.

[0053] When the SOC of the auxiliary battery 14 reaches the upper limit of the first range due to charging, the operation returns to that shown in Fig. 5(a). Specifically, in the first control mode, when the SOC of the auxiliary battery 14 reaches the upper limit of the first range, the controller 34 controls the bidirectional DC / DC converter 18 to a stopped state.

[0054] In the first control mode, when the solar panel 10 starts generating power, solar charging starts. When solar charging starts in the first control mode, the control unit 34 transitions to the second control mode.

[0055] Here, a comparative example recognized by the present inventor will be described. The solar charging system of the comparative example has the same configuration as the solar charging system 1 of the embodiment, but the control is different. In the comparative example, the first control mode and the second control mode use a common first control range. In other words, even in the second control mode, charging and discharging are controlled in the first range, which is narrower than the second range of the embodiment.

[0056] In the comparative example, when the solar radiation is low and the power generated by the solar panel is low in the second control mode, the SOC of the auxiliary battery may decrease due to the power consumption of the auxiliary equipment, as in FIG. 3(b). In the comparative example, the upper limit value of the control range is low and the lower limit value is high in the second control mode, so that the SOC of the auxiliary battery may decrease to the lower limit in a shorter time than in the embodiment. When the SOC of the auxiliary battery decreases to the lower limit, the auxiliary battery is charged with the generated power and the power of the drive battery, as in FIG. 3(c). In other words, in a situation where the solar radiation is unstable, the power that is once boosted by the pumping operation when the solar radiation is high and stored in the drive battery from the auxiliary battery, as in FIG. 4(a), may be lowered when the solar radiation is low and used to charge the auxiliary battery again. At this time, losses occur in the bidirectional DC / DC converter in each of the boost operation and the step-down operation.

[0057] The inventor recognized that in the comparative example, in conditions of unstable solar radiation, such power interchange between the auxiliary battery and the drive battery is repeated relatively frequently, resulting in increased power loss.

[0058] In contrast to this comparative example, in the embodiment, the SOC of the auxiliary battery 14 during solar charging is controlled within a second range that is wider than the first range, so that in a situation where the solar radiation is unstable, the frequency of charging and discharging the auxiliary battery 14 during solar charging can be reduced compared to the comparative example. In other words, the frequency of power interchange between the auxiliary battery 14 and the driving battery 20 can be reduced compared to the comparative example. Therefore, the power loss caused by repeated charging and discharging can be reduced.

[0059] Specifically, since the upper limit of the second range is higher than the first range, the SOC of the auxiliary battery 14 can be made higher than that of the comparative example during solar charging shown in FIG. 3(a). Therefore, the power available to the auxiliary 16 increases. Therefore, even if the solar radiation decreases and the state shown in FIG. 3(b) is reached, there is a sufficient time until the SOC of the auxiliary battery 14 decreases and reaches the lower limit of the second range. Also, since the lower limit of the second range is lower than the first range, there is a sufficient time until the SOC of the auxiliary battery 14 decreases and reaches the lower limit of the second range in the state shown in FIG. 3(b) with reduced solar radiation.

[0060] From the above, the SOC of the auxiliary battery 14 is less likely to reach the lower limit of the second range than in the comparative example. Therefore, the operation of charging the auxiliary battery 14 with the power of the drive battery 20 shown in Fig. 3(c) is less likely to occur. If the solar radiation recovers during the state shown in Fig. 3(b), the SOC of the auxiliary battery 14 can be increased again with the power generated by the solar panel 10, so the operation shown in Fig. 3(c) may not occur.

[0061] Furthermore, when solar charging is not in progress, the SOC of the auxiliary battery 14 is controlled within a relatively narrow first range, so that the auxiliary battery 14 can be made less susceptible to deterioration.

[0062] Next, a description will be given of the overall operation of the solar charging system 1 configured as above. Fig. 6 is a flowchart showing the control process of the solar charging system 1. The process in Fig. 6 is executed repeatedly.

[0063] If the second control mode is not to be started (N in S10), the control unit 34 operates in the first control mode, controls the SOC of the auxiliary battery 14 within the first range (S20), and ends the process.

[0064] If the second control mode is to be started (Y in S10), the controller 34 operates in the second control mode and controls the SOC of the auxiliary battery 14 within the second range (S12). If the second control mode is not to be ended (N in S14), the process returns to S12.

[0065] When the second control mode is to be ended (Y in S14), if the voltage of the auxiliary battery 14 is higher than the first voltage or lower than the second voltage (Y in S16), the control unit 34 controls the bidirectional DC / DC converter 18 to adjust the voltage of the auxiliary battery 14 (S18), and the process proceeds to S20. If the condition in S16 is not satisfied (N in S16), the process proceeds to S20.

[0066] The present invention has been described above based on the embodiments. The embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component and each processing step, and that such modifications are also within the scope of the present invention. [Explanation of symbols]

[0067] 1...solar charging system, 10...solar panel, 12...DC / DC converter, 14...auxiliary battery, 16...auxiliary, 18...bidirectional DC / DC converter, 20...driving battery, 30...control device, 32...SOC estimating unit, 34...control unit.

Claims

1. Solar panels and an auxiliary battery to which the power generated by the solar panel is supplied; A vehicle drive battery; a DC / DC converter that operates in a first state in which the power generated by the solar panel and the power of the auxiliary battery are supplied to the driving battery, or in a second state in which the power of the driving battery is supplied to the auxiliary battery; A control unit that controls the DC / DC converter; Equipped with The control unit is a first control mode in which the DC / DC converter is controlled so that a voltage or SOC of the auxiliary battery falls within a first range, or a second control mode in which the DC / DC converter is controlled so that a voltage or SOC of the auxiliary battery falls within a second range wider than the first range; When the solar panel is used for solar charging, the control device operates in the second control mode. A solar charging system.

2. When the control unit is in the solar charging mode, When the voltage or the SOC of the auxiliary battery reaches a lower limit value of the second range, the DC / DC converter is controlled to the second state or a stopped state so as to charge the auxiliary battery; When the voltage or SOC of the auxiliary battery reaches an upper limit value of the second range, the DC / DC converter is controlled to the first state so that the driving battery is charged with the power generated by the solar panel and the power of the auxiliary battery.

2. The solar charging system according to claim 1 .

3. The control unit is When the auxiliary battery is being solar-charged and the DC / DC converter is stopped, when the voltage or the SOC of the auxiliary battery reaches a lower limit value of the second range, the DC / DC converter is controlled to the second state; When the auxiliary battery is being solar-charged and the DC / DC converter is operating in the first state, if the voltage or the SOC of the auxiliary battery reaches a lower limit value of the second range, the DC / DC converter is controlled to a stopped state; In the first control mode, when the voltage or SOC of the auxiliary battery reaches a lower limit value of the first range, the DC / DC converter is controlled to the second state, and when the voltage or SOC of the auxiliary battery reaches an upper limit value of the first range, the DC / DC converter is controlled to a stopped state.

3. The solar charging system according to claim 2.

4. When the second control mode is ended, the control unit When the voltage of the auxiliary battery is higher than a predetermined first voltage, the DC / DC converter is controlled to the first state; When the voltage of the auxiliary battery is lower than a predetermined second voltage that is lower than the first voltage, the DC / DC converter is controlled to the second state.

4. The solar charging system according to claim 1, wherein the solar charging system is a solar power supply system.

5. The control unit is When the DC / DC converter is not operating in the first state in the second control mode, the control mode is switched to the first control mode when solar charging is completed, When the DC / DC converter is operating in the first state in the second control mode, the second control mode is continued even after solar charging is terminated, and when the voltage or SOC of the auxiliary battery reaches a lower limit value of the second range, the control mode is switched to the first control mode.

4. The solar charging system according to claim 1, wherein the solar charging system is a solar power supply system.

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