Solar Charging System

Abstract

To provide a solar charging system enabling improvement of energy charging efficiency of pumping charging processing.SOLUTION: A solar charging system mounted on a vehicle is provided, comprising: a solar panel; a battery for driving; a battery for an auxiliary machine; a first DCDC converter capable of supplying generated power of the solar panel to the battery for the auxiliary machine; a second DCDC converter capable of supplying generated power of the solar panel to the battery for driving and capable of supplying power of the battery for driving to the battery for auxiliary machine through the first DCDC converter; and a control unit controlling the first DCDC converter and the second DCDC converter. When generated power of the solar panel is lower than predetermined power in processing of supplying the predetermined power to the battery for the auxiliary machine, the control unit supplies power of the battery for the driving to the battery for the auxiliary machine through the first DCDC converter and the second DCDC converter.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a solar charging system that controls the supply of electric power generated by a solar panel mounted on a vehicle. [Background technology]

[0002] Patent Document 1 discloses a solar charging system in which, when the solar panel is in a state where it can generate power, the solar panel supplies power to an auxiliary system, deriving the power actually generated by the solar panel, and if this derived actual generated power is equal to or greater than a specified value, the power generated by the solar panel is used to further charge the drive battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-083248 Summary of the Invention [Problem to be solved by the invention]

[0004] When a vehicle is parked, the auxiliary battery supplies power to devices that operate services provided while the vehicle is parked. To prevent this, a process (hereinafter referred to as "pumping charging process") is sometimes performed to transfer power from the drive battery to the auxiliary battery. This pumping charging process is performed via the main DC-DC converter that controls the vehicle's power, which poses a problem: the power consumption required to start the main DC-DC converter increases, reducing energy charging efficiency. Therefore, there is room for further study of pumping charging process methods using solar charging systems.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a solar charging system that can improve the energy charging efficiency of the pumping charging process. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the disclosed technology is a solar charging system mounted on a vehicle, comprising a solar panel, a drive battery, an auxiliary battery, a first DCDC converter capable of supplying the power generated by the solar panel to the auxiliary battery, a second DCDC converter capable of supplying the power generated by the solar panel to the drive battery and of supplying the power of the drive battery to the auxiliary battery via the first DCDC converter, and a control unit that controls the first DCDC converter and the second DCDC converter, wherein, during a process of supplying a predetermined power to the auxiliary battery, if the power generated by the solar panel is less than the predetermined power, the control unit supplies the power of the drive battery to the auxiliary battery via the first DCDC converter and the second DCDC converter. [Effects of the Invention]

[0007] According to the solar charging system of the present disclosure, it is possible to improve the energy charging efficiency of the pumping charging process from the drive battery to the auxiliary battery. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a solar charging system according to an embodiment of the present invention. [Figure 2A] Flowchart of pumping charge control executed by the solar charging system [Figure 2B] Flowchart of pumping charge control executed by the solar charging system [Figure 3] A diagram explaining the flow of power during pumping charge control when there is surplus solar power generation. [Figure 4] Diagram explaining the flow of power during pumping charge control when solar power generation is insufficient DETAILED DESCRIPTION OF THE INVENTION

[0009] The solar charging system according to the present disclosure uses a bidirectional high-voltage DC-DC converter connecting a solar panel and a drive battery. For example, when pumping power from the solar panel to charge the auxiliary battery, if the power generated by the solar panel is less than the power required to charge the auxiliary battery, power from the drive battery is supplied to the auxiliary battery via the high-voltage DC-DC converter and the auxiliary DC-DC converter. This supply process improves energy charging efficiency compared to pumping power via the main DC-DC converter, which consumes a lot of power during startup. Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0010] <Embodiment> [composition] Fig. 1 is a block diagram showing an example of a power supply configuration including a solar charging system 1 according to an embodiment of the present disclosure. The solar charging system 1 shown in Fig. 1 includes a solar panel 10, a solar DDC 20, a high-voltage DDC 30, an auxiliary DDC 40, a drive battery 50, an auxiliary battery 60, and a control unit 100.

[0011] This solar charging system 1 can be mounted on vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs), for example.

[0012] The solar panel 10 is a power generation device that generates electricity when exposed to sunlight, and is typically a solar cell module that is an assembly of solar cells. This solar panel 10 can be installed, for example, on the roof of a vehicle (solar roof). The number of solar panels 10 installed on a vehicle is not limited to one, and may be multiple.

[0013] The solar DDC 20 is a DC-DC converter that outputs the power generated by the solar panel 10 to the high-voltage DDC 30 and the auxiliary DDC 40. This solar DDC 20 can convert the output voltage of the solar panel 10, which is the input voltage, into a predetermined voltage and output it to the high-voltage DDC 30 and the auxiliary DDC 40. The power generated by this solar panel 10 is calculated using measurements from sensors and measuring instruments (not shown) provided in the solar DDC 20 and the like.

[0014] The high-voltage DDC 30 is a bidirectional DCDC converter (second DCDC converter) connected to the solar DDC 20. The high-voltage DDC 30 can input the output power of the solar DDC 20, convert (boost) it to a predetermined voltage, and output it to the drive battery 50. The high-voltage DDC 30 can also input the power of the drive battery 50, convert (step down) it to a predetermined voltage, and output it to the auxiliary DDC 40.

[0015] The auxiliary DDC 40 is a unidirectional DC-DC converter (first DC-DC converter) connected to the solar DDC 20. The auxiliary DDC 40 can receive the output power of the solar DDC 20, convert it into power of a predetermined voltage (step down), and output it to the auxiliary battery 60.

[0016] The drive battery 50 is a rechargeable secondary battery, such as a lithium-ion battery or a nickel-metal hydride battery. The drive battery 50 is connected to a main device (not shown) for driving the vehicle and can supply the power necessary to operate the main device. Examples of main devices include a starter motor and a traction electric motor. The drive battery 50 is connected to the solar panel 10 via the solar DDC 20 and the high-voltage DDC 30 so that it can be charged by power generated by the solar panel 10. The drive battery 50 is also connected to the main DDC 200 so that it can be charged and discharged between the drive battery 50 and the auxiliary battery 60. The drive battery 50 has a higher rated voltage than the auxiliary battery 60.

[0017] The auxiliary battery 60 is a rechargeable secondary battery, such as a lithium-ion battery or a lead-acid battery. The auxiliary battery 60 is connected to auxiliary devices (not shown) other than those used to drive the vehicle, and can supply the power necessary to operate the auxiliary devices. Examples of auxiliary devices include lighting devices such as headlamps and interior lights, air conditioning devices such as heaters and coolers, and devices for autonomous driving and advanced driving assistance. The auxiliary battery 60 is connected to the solar panel 10 via the solar DDC 20 and the auxiliary DDC 40 so that it can be charged using power generated by the solar panel 10. The auxiliary battery 60 is also connected to the main DDC 200 so that it can be charged and discharged between the auxiliary battery 60 and the drive battery 50. The auxiliary battery 60 has a lower rated voltage than the drive battery 50.

[0018] The solar DDC 20, high-voltage DDC 30, and auxiliary DDC 40 described above typically constitute a solar ECU (Electronic Control Unit) 70. In this solar ECU 70, the function of the auxiliary DDC 40 may be included in the solar DDC 20. Furthermore, when multiple solar panels 10 are installed in the vehicle, multiple solar DDCs 20 may be provided in parallel to individually control each solar panel 10. Furthermore, the solar ECU 70 may be configured integrally with the solar panel 10, or may be configured integrally with other powertrain components.

[0019] The control unit 100 controls the power states of the solar panel 10, the drive battery 50, and the auxiliary battery 60 by controlling the solar DDC 20, the high-voltage DDC 30, the auxiliary DDC 40, and the main DDC 200. Specifically, the control unit 100 controls the power supply from the solar panel 10 to the drive battery 50 by controlling the high-voltage DDC 30 to a step-up operation state. The control unit 100 also controls the power supply from the drive battery 50 to the auxiliary battery 60 by controlling the high-voltage DDC 30 to a step-down operation state and controlling the auxiliary DDC 40 to a step-down operation state.

[0020] The control unit 100 may be realized as a function of an HV-ECU (not shown) that performs hybrid control of the vehicle, or may be realized as a function of the solar ECU 70, or may be realized by an ECU other than the HV-ECU and the solar ECU 70. The ECU that realizes the control unit 100 typically includes a processor, memory, an input / output interface, and the like, and can perform the various controls described above by having the processor read and execute programs stored in the memory.

[0021] The main DDC 200 is a DC-DC converter that supplies power from the drive battery 50 to the auxiliary battery 60 and auxiliary devices, and supplies power from the auxiliary battery 60 to the drive battery 50, when the solar ECU 70 is not in use, such as when the battery is not being charged with power generated by the solar panel 10. The main DDC 200 consumes more power for startup than the high-voltage DDC 30 and the auxiliary DDC 40.

[0022] [control] Next, the control executed by the solar charging system 1 will be described with further reference to Figures 2A, 2B, 3, and 4. Figures 2A and 2B are flowcharts explaining the pumping charge control process executed by the control unit 100 and solar ECU 70 of the solar charging system 1. The process of Figure 2A and the process of Figure 2B are connected by connectors X and Y. Figure 3 is a diagram explaining the power flow of the pumping charge control when there is a surplus of power generated by the solar panel 10 in the solar charging system 1. Figure 4 is a diagram explaining the power flow of the pumping charge control when there is a shortage of power generated by the solar panel 10 in the solar charging system.

[0023] The pumping charge control illustrated in Figures 2A and 2B is initiated, for example, when the solar ECU 70, which has had some or all of its functions stopped (sleep) while the vehicle is parked, starts (wakes up) the stopped functions as the solar panel 10 becomes capable of generating electricity due to irradiation with sunlight.

[0024] (Step S201) The solar ECU 70 acquires the generated power Wgen, which is the power generated by the solar panel 10. This generated power Wgen can be derived from the voltage and current output by the solar panel 10. The generated power Wgen may be notified to the control unit 100. Once the generated power Wgen of the solar panel 10 is acquired by the solar ECU 70, the process proceeds to step S202.

[0025] (Step S202) The solar ECU 70 determines whether the power generation Wgen of the solar panel 10 exceeds a predetermined threshold Wsol. This determination is made to determine whether the solar panel 10 is generating enough power to perform efficient pumping charge control. For example, if the power generation Wgen of the solar panel 10 is less than the power required for the pumping charge operation of the solar charging system 1, the auxiliary battery 60 will discharge, resulting in more battery power being consumed than the power obtained through solar power generation, making the pumping charge control meaningless. Therefore, the threshold Wsol can be set to a value equal to or greater than the power at which pumping charge control is possible without causing discharge from the auxiliary battery 60.

[0026] If the solar ECU 70 determines that the generated power Wgen exceeds the threshold value Wsol (Wgen>Wsol) (step S202, Yes), the process proceeds to step S204. On the other hand, if the solar ECU 70 determines that the generated power Wgen does not exceed the threshold value Wsol (Wgen≦Wsol) (step S202, No), the process proceeds to step S203.

[0027] (Step S203) Since the solar ECU 70 cannot perform efficient pumping charge control using the power Wgen generated by the solar panel 10, it stops the operation of some or all of the predetermined functions and goes into sleep mode, thereby ending the pumping charge control.

[0028] (Step S204) The solar ECU 70 starts power generation by the solar panel 10. That is, the solar ECU 70 starts outputting the power Wgen generated by the solar panel 10 to the auxiliary battery 60 or the like. This power generation uses well-known maximum power point tracking (MPPT) control or the like. When the solar ECU 70 starts power generation by the solar panel 10, the process proceeds to step S205.

[0029] (Step S205) The control unit 100 acquires the processing power Waux consumed in the process of charging the auxiliary battery 60 (hereinafter referred to as the "solar charging process"). More specifically, the processing power Waux is the power required for the control operations of the ECUs and other devices involved in the execution of the solar charging process. This processing power Waux can be derived from the outflow current and output voltage of the auxiliary battery 60 detected by the control unit 100 and other devices. The processing power Waux is also notified to the solar ECU 70. Once the processing power Waux has been acquired by the control unit 100, the process proceeds to step S206.

[0030] (Step S206) The control unit 100 acquires the required power Wpomp consumed in the pumping charging process that supplies a predetermined amount of power to the auxiliary battery 60. More specifically, the required power Wpomp is the sum of the power charged to the auxiliary battery 60 and the power consumed by auxiliary devices (not shown) (power consumption of the auxiliary system). This required power Wpomp can be derived from the state of charge (SOC), outflow current, output voltage, and the like of the auxiliary battery 60 detected by the control unit 100 or the like. Once the required power Wpomp has been acquired by the control unit 100, the process proceeds to step S207.

[0031] (Step S207) The control unit 100 notifies the solar ECU 70 of the processing power Waux and the required power Wpomp. When the processing power Waux and the required power Wpomp are notified to the solar ECU 70 by the control unit 100, the process proceeds to step S208.

[0032] (Step S208) The solar ECU 70 determines whether the generated power Wgen of the solar panel 10 is greater than or equal to the total power of the processing power Waux consumed in the solar charging process and the required power Wpomp consumed in the pumping charging process. This determination is made to determine whether the pumping charge of the auxiliary battery 60 can be performed only with the generated power Wgen of the solar panel 10.

[0033] When the solar ECU 70 determines that the generated power Wgen is greater than or equal to the total power of the processing power Waux and the required power Wpomp (Wgen ≧ Waux + Wpomp) (step S208, yes), the process proceeds to step S209. On the other hand, when the solar ECU 70 determines that the generated power Wgen is less than the total power of the processing power Waux and the required power Wpomp (Wgen < Waux + Wpomp) (step S208, no), the process proceeds to step S210.

[0034] (Step S209) The control unit 100 and the solar ECU 70 supply the total power of the processing power Waux and the required power Wpomp among the generated power Wgen of the solar panel 10 to the auxiliary battery 60. The power flow in this case is shown by the solid line in FIG. 3. When the total power of the processing power Waux and the required power Wpomp is supplied to the auxiliary battery 60 by the control unit 100 and the solar ECU 70, the process proceeds to step S211.

[0035] (Step S210) The control unit 100 and the solar ECU 70 supply all of the generated power Wgen of the solar panel 10 to the auxiliary battery 60. The flow of power in this case is indicated by the solid lines in Fig. 4. When all of the generated power Wgen has been supplied to the auxiliary battery 60 by the control unit 100 and the solar ECU 70, the process proceeds to step S212.

[0036] (Step S211) The control unit 100 and the solar ECU 70 control the high-voltage DDC 30 to a boost operation state, thereby enabling the power Wgen generated by the solar panel 10 to be supplied to the drive battery 50. When the control unit 100 and the solar ECU 70 control the high-voltage DDC 30 to a boost operation state, the process proceeds to step S213.

[0037] (Step S212) The control unit 100 and the solar ECU 70 control the high-voltage DDC 30 to a step-down operation state. This allows power from the drive battery 50 to be supplied to the auxiliary battery 60 via the auxiliary DDC 40, which is in step-down operation. When the control unit 100 and the solar ECU 70 control the high-voltage DDC 30 to a step-down operation state, the process proceeds to step S214.

[0038] (Step S213) The control unit 100 and solar ECU 70 supply surplus power Wrem, which is not supplied to the auxiliary battery 60, out of the power generated by the solar panel 10, to the drive battery 50. This surplus power Wrem is the power obtained by subtracting the processing power Waux and the required power Wpomp from the power generated Wgen (Wrem = Wgen - (Waux + Wpomp)). The flow of power in this case is shown by the dashed line in Figure 3. Once the control unit 100 and solar ECU 70 have supplied surplus power Wrem of the power generated Wgen to the drive battery 50, the process proceeds to step S201.

[0039] (Step S214) The control unit 100 and solar ECU 70 supply the power deficit Wlack, which is the power required for the auxiliary battery 60 that is not met by the power generated by the solar panel 10 alone, from the drive battery 50 to the auxiliary battery 60 (dashed line in FIG. 4). This power deficit Wlack is the power obtained by adding the processing power Waux to the required power Wpomp and subtracting the generated power Wgen from the sum (Wlack = (Waux + Wpomp) - Wgen). The flow of power in this case is shown by the dashed line in FIG. 4. Once the control unit 100 and solar ECU 70 have supplied the power deficit Wlack of the auxiliary battery 60 from the drive battery 50 to the auxiliary battery 60, the process proceeds to step S201.

[0040] <Actions and Effects> As described above, in the solar charging system 1 according to one embodiment of the present disclosure, the high-voltage DDC 30 provided in the solar ECU 70 is configured as a bidirectional DC-DC converter. When it is necessary to perform pumping charging from the drive battery 50 to the auxiliary battery 60, such as when the power generated by the solar panel 10 alone is insufficient, the control unit 100 controls the power transfer to be via the high-voltage DDC 30 and the auxiliary DDC 40 of the solar ECU 70, rather than via the main DDC 200.

[0041] This control enables pumping charging of the auxiliary battery 60 by activating the high-voltage DDC 30 and the auxiliary DDC 40, which consume less power for startup than the main DDC 200, without activating the main DDC 200, which consumes a lot of power for startup. This reduces the power consumed in the pumping charging process, reduces energy loss throughout the vehicle, and improves energy charging efficiency.

[0042] The above describes one embodiment of the disclosed technology, but the present disclosure can be understood as not only a solar charging system, but also a method performed by a solar charging system, a program for that method, a computer-readable non-transitory storage medium storing the program, a vehicle equipped with a solar charging system, and the like. [Industrial Applicability]

[0043] The solar charging system of the present disclosure can be used in vehicles that charge their batteries using power generated by a solar panel. [Explanation of symbols]

[0044] 1 Solar charging system 10. Solar Panels 20 Solar DDC 30 High-voltage DDC 40 Auxiliary DDC 50 Drive battery 60 Auxiliary battery 70 Solar ECU 100 control section 200 Main DDC

Claims

1. A solar charging system mounted on a vehicle, Solar panels and A drive battery; An auxiliary battery; a first DC-DC converter capable of supplying power generated by the solar panel to the auxiliary battery; a second DC-DC converter that can supply power generated by the solar panel to the drive battery and can supply power from the drive battery to the auxiliary battery via the first DC-DC converter; a control unit that controls the first DC-DC converter and the second DC-DC converter, the control unit, in the process of supplying a predetermined power to the auxiliary battery, supplies power from the drive battery to the auxiliary battery via the first DC-DC converter and the second DC-DC converter when the power generated by the solar panel is less than the predetermined power. Solar charging system.

2. When the power generated by the solar panel is less than the predetermined power, the control unit supplies the power that is insufficient to be generated by the solar panel from the drive battery to the auxiliary battery. The solar charging system according to claim 1 .

3. In the process of supplying the predetermined power to the auxiliary battery, if the power generated by the solar panel is equal to or greater than the predetermined power, the control unit supplies the power generated by the solar panel to the auxiliary battery and supplies surplus power, which is obtained by excluding the predetermined power from the power generated by the solar panel, to the drive battery. The solar charging system according to claim 1 or 2.

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