Solar Charging System

Abstract

To provide a solar charging system in which an energy conversion efficiency of a DC / DC converter in a process (pumping charging process) for transferring power of a high-voltage battery to an auxiliary battery in a vehicle can be improved.SOLUTION: There is provided a solar charging system mounted on a vehicle, which includes: a power generation module in which a solar panel is used; an auxiliary system including an auxiliary battery in which generated power of the power generation module is stored, and an auxiliary load to which power is supplied from the auxiliary battery; a high-voltage battery used to drive the vehicle; and a control unit provided between the high-voltage battery and the auxiliary system and controlling power transfer between the high-voltage battery and the auxiliary system. When power transfer from the high-voltage battery to the auxiliary system is required, the control unit supplies power of the high-voltage battery to the auxiliary system if generated power of the power generation module is not supplied to the auxiliary system.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 a high-voltage 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 not in operation (for example, when parked), a process known as pumping charge, which transfers power from the high-voltage battery to the auxiliary battery, may be performed to prevent the auxiliary battery from running out, which supplies power to devices that operate services provided while the vehicle is parked. This pumping charge process is usually performed via a DC-DC converter that controls the vehicle's power.

[0005] However, this DC-DC converter is generally designed to transfer large amounts of power from the high-voltage battery to the auxiliary battery while the vehicle is in operation. Therefore, there is a problem that the energy conversion efficiency is low when transferring small amounts of power, such as when pumping and charging while the vehicle is parked. Therefore, there is room for further study on the charging method of solar-generated power implemented in solar charging systems.

[0006] 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 conversion efficiency of a DC-DC converter in the pumping charging process. [Means for solving the problem]

[0007] In order to solve the above problems, one aspect of the disclosed technology is a solar charging system mounted on a vehicle, comprising: a power generation module using a solar panel; an auxiliary system including an auxiliary battery that stores the power generated by the power generation module and an auxiliary load that is supplied with power from the auxiliary battery; a high-voltage battery used to drive the vehicle; and a control unit provided between the high-voltage battery and the auxiliary system that controls the transfer of power between the high-voltage battery and the auxiliary system, wherein when power transfer from the high-voltage battery to the auxiliary system is requested, the control unit supplies power from the high-voltage battery to the auxiliary system if the power generated by the power generation module is not being supplied to the auxiliary system. [Effects of the Invention]

[0008] According to the solar charging system of the present disclosure, the energy conversion efficiency of the DC-DC converter in the pumping charging process can be improved. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram of a solar charging system and its peripheral components according to an embodiment of the present disclosure. [Figure 2] Processing flowchart of charging control executed by the solar charging system [Figure 3] Diagram of the power path when pumping and charging is not performed [Figure 4] Diagram of the power path when pumping and charging (with solar power generation) [Figure 5] Diagram of the power path when pumping and charging (without solar power generation) DETAILED DESCRIPTION OF THE INVENTION

[0010] The solar charging system according to the present disclosure supplies power from the high-voltage battery to the auxiliary system when the power generated by the power generation module is not being supplied to the auxiliary system (auxiliary battery and auxiliary load). This allows a large amount of power to be taken out from the high-voltage battery to the auxiliary system, thereby improving the energy conversion efficiency of the DC-DC converter. Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0011] <Embodiment> [composition] Fig. 1 is a block diagram showing a schematic configuration of a solar charging system 100 and its peripheral parts according to an embodiment of the present disclosure. The solar charging system 100 shown in Fig. 1 includes a solar power generation module 110, a high-voltage battery 120, an auxiliary battery 130, and a bidirectional DC-DC converter 140. The solar charging system 100 is also connected to an auxiliary load 200 so as to be able to supply power.

[0012] The solar charging system 100 can be installed in vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs), for example.

[0013] The solar power generation module 110 is a power generation device that generates electricity when exposed to sunlight and outputs the generated power to an auxiliary battery 130 and an auxiliary load 200 that are connected to the solar power generation module 110. The solar power generation module 110 includes a solar panel which is an assembly of solar battery cells, a solar DC-DC converter that outputs the power generated by the solar panel at a predetermined voltage, and a solar control unit that performs maximum power point tracking (MPPT) control (not shown). The power generated by the solar panel is calculated from measurements of sensors and measuring instruments (not shown).

[0014] The high-voltage battery 120 is a rechargeable secondary battery, such as a lithium-ion battery or a nickel-metal hydride battery. The high-voltage battery 120 is connected to a main device (not shown) for driving the vehicle and can supply the power necessary for the operation of the main device. Examples of the main device include a starter motor and a traction electric motor. The high-voltage battery 120 is connected to the solar power generation module 110 via a bidirectional DC-DC converter 140 so that it can be charged with power generated by a solar panel of the solar power generation module 110. The high-voltage battery 120 is also connected to the auxiliary battery 130 via the bidirectional DC-DC converter 140 so that it can supply its own stored power to the auxiliary battery 130 and can be charged with power stored in the auxiliary battery 130. The high-voltage battery 120 is, for example, a drive battery with a higher rated voltage than the auxiliary battery 130.

[0015] The auxiliary battery 130 is a secondary battery configured to be chargeable and dischargeable, such as a lithium-ion battery or a lead-acid battery. The auxiliary battery 130 can supply the auxiliary load 200 with the power required for the operation of the auxiliary load 200. The auxiliary battery 130 is connected to the solar power generation module 110 so as to be chargeable with power generated by a solar panel of the solar power generation module 110. The auxiliary battery 130 is also connected to the high-voltage battery 120 via a bidirectional DC-DC converter 140 so as to be chargeable with power stored in the high-voltage battery 120 and to be able to supply its own stored power to the high-voltage battery 120. The charge amount (amount of stored power) of the auxiliary battery 130 and the current flowing in and out of the auxiliary battery 130 are monitored by sensors, measuring instruments, etc. (not shown).

[0016] The bidirectional DC-DC converter 140 is a bidirectional power converter that can convert input power into power of a predetermined voltage and output it. One end (called the primary side) of this bidirectional DC-DC converter 140 is connected to the solar power generation module 110, the auxiliary battery 130, and the auxiliary load 200, and the other end (called the secondary side) is connected to the high-voltage battery 120. The bidirectional DC-DC converter 140 can supply (pumping charge) the power output by the solar power generation module 110 and the auxiliary battery 130 connected to the primary side to the high-voltage battery 120 connected to the secondary side. The bidirectional DC-DC converter 140 can also supply (pumping charge) the power of the high-voltage battery 120 connected to the secondary side to the auxiliary battery 130 and the auxiliary load 200 connected to the primary side. During this power supply, the bidirectional DC-DC converter 140 boosts the voltage of the auxiliary battery 130 input to the primary side to produce the output voltage on the secondary side (in boost operation), and also drops the voltage of the high-voltage battery 120 input to the secondary side to produce the output voltage on the primary side (in step-down operation). Note that instead of the bidirectional DC-DC converter 140, two unidirectional DC-DC converters may be provided with power transfer directions opposite to each other.

[0017] The above-described bidirectional DC-DC converter 140, together with an electronic control unit (not shown) that controls the power conversion operation, constitutes a control unit that controls power transfer between the high-voltage battery 120 and the auxiliary battery 130. This control unit can acquire the power (solar-generated power) generated by the solar panel of the solar power generation module 110, the amount of power stored in the auxiliary battery 130, and the current flowing in and out of the auxiliary battery 130. The control performed by the control unit will be described later. Note that this control unit may be provided as a configuration independent of the bidirectional DC-DC converter 140.

[0018] The auxiliary load 200 is a variety of auxiliary equipment mounted on the vehicle. The auxiliary load 200 operates by receiving power generated by the solar power generation module 110 and power stored in the auxiliary battery 130. Examples of such auxiliary equipment include lighting equipment such as headlamps and interior lights, air conditioning equipment such as heaters and air conditioners, and systems for autonomous driving and advanced driving assistance. The auxiliary load 200 and the above-mentioned auxiliary battery 130 form an "auxiliary system."

[0019] [control] Next, control performed in the solar charging system 100 according to this embodiment will be described with further reference to Figures 2 to 5. Figure 2 is a flowchart illustrating the procedure for charging control executed by the solar charging system 100. Figure 3 is a diagram illustrating the power path when there is no power supply from the high-voltage battery 120 to the auxiliary battery 130 and the auxiliary load 200 (auxiliary system). Figure 4 is a diagram illustrating the power path when there is solar generated power and there is power supply from the high-voltage battery 120 to the auxiliary battery 130 and the auxiliary load 200. Figure 5 is a diagram illustrating the power path when there is no solar generated power and there is power supply from the high-voltage battery 120 to the auxiliary battery 130 and the auxiliary load 200.

[0020] The charging control illustrated in FIG. 2 is started when pumping charge, which transfers power from the high-voltage battery 120 to the auxiliary battery 130, is requested.

[0021] (Step S201) The solar charging system 100 determines whether the auxiliary battery 130 is capable of receiving electric power. This determination is made to ascertain whether the auxiliary battery 130 is in a state in which it can be charged. As an example, if the amount of charge stored in the auxiliary battery 130 is less than a predetermined value (fully charged state), it is determined that it is capable of receiving electric power. Also, if an abnormality is found in the auxiliary battery 130, such as the temperature of the auxiliary battery 130 being higher than a predetermined value, it is determined that it is not capable of receiving electric power. Such a state of the auxiliary battery 130 is determined based on physical quantities detected by sensors, measuring instruments, etc.

[0022] If the solar charging system 100 determines that the auxiliary battery 130 can receive power (step S201, Yes), the process proceeds to step S202. On the other hand, if the solar charging system 100 determines that the auxiliary battery 130 cannot receive power (step S201, No), the process proceeds to step S204.

[0023] (Step S202) The solar charging system 100 determines whether or not a "solar charging process" is currently being executed, in which power generated by the solar panel of the solar power generation module 110 is output to the auxiliary battery 130 and the auxiliary load 200 (auxiliary system). This determination is made to determine whether or not a more efficient pumping charge can be performed. For example, if the solar power generation module 110 is already supplying solar-generated power to the auxiliary battery 130, this solar-generated power may limit the power that can be transferred from the high-voltage battery 120 to the auxiliary battery 130, and high energy conversion efficiency may not be achieved.

[0024] If the solar charging system 100 determines that the solar charging process is being executed (step S202, Yes), the process proceeds to step S203. On the other hand, if the solar charging system 100 determines that the solar charging process is not being executed (step S202, No), the process proceeds to step S206.

[0025] (Step S203) The solar charging system 100 determines whether the auxiliary battery 130 is in a predetermined state. This predetermined state refers to a state that may lead to an undesirable state (affecting deterioration) of the auxiliary battery 130 in the future if the auxiliary battery 130 continues to receive solar-generated power from the solar power generation module 110, such as a significant decrease (depletion) in the amount of stored power in the auxiliary battery 130 or a significant drop in the output voltage of the auxiliary battery 130. Specifically, examples of the predetermined state include a state in which the amount of stored power in the auxiliary battery 130 decreases at a predetermined rate, or a state in which the voltage of the auxiliary battery 130 decreases at a predetermined rate. Whether the auxiliary battery 130 is in the predetermined state can be determined based on the remaining amount of stored power, temperature (heat generation), and limits on the inflow and outflow current of the auxiliary battery 130, the current consumption of the auxiliary load 200, the ambient temperature, and the like.

[0026] If the solar charging system 100 determines that the auxiliary battery 130 is in a predetermined state (step S203, Yes), the process proceeds to step S205. On the other hand, if the solar charging system 100 determines that the auxiliary battery 130 is not in a predetermined state (step S203, No), the process proceeds to step S204.

[0027] (Step S204) The solar charging system 100 does not supply power from the high-voltage battery 120 to the auxiliary battery 130 and the auxiliary load 200 (auxiliary system). With this control, only the power generated by the solar panel of the solar power generation module 110 is supplied to the auxiliary battery 130 and the auxiliary load 200. The state of power supply from the solar power generation module 110 to the auxiliary system is as shown in Figure 3. When the solar charging system 100 controls the power supply to the auxiliary system, this charging control ends.

[0028] (Step S205) The solar charging system 100 supplies power from the high-voltage battery 120 to the auxiliary battery 130 and the auxiliary load 200 (auxiliary system). Through this control, power from the high-voltage battery 120, together with power generated by the solar panel of the solar power generation module 110, is supplied to the auxiliary battery 130 and the auxiliary load 200 regardless of the energy conversion efficiency (even if low efficiency) in order to protect the auxiliary battery 130. The power supply state from the solar power generation module 110 and the high-voltage battery 120 to the auxiliary system is as shown in Figure 4. When the solar charging system 100 controls the power supply to the auxiliary system, this charging control ends.

[0029] (Step S206) The solar charging system 100 supplies power from the high-voltage battery 120 to the auxiliary battery 130 and the auxiliary load 200 (auxiliary system). This control allows only the power of the high-voltage battery 120 to be supplied to the auxiliary battery 130 and the auxiliary load 200 with high energy conversion efficiency (high efficiency). The state of power supply from the high-voltage battery 120 to the auxiliary system is as shown in Figure 5. When the solar charging system 100 controls the power supply to the auxiliary system, this charging control ends.

[0030] <Actions and Effects> As described above, when a request is made to transfer power (pumping charging process) from the high-voltage battery 120 to an auxiliary system including the auxiliary battery 130 and the auxiliary load 200, the solar charging system 100 according to one embodiment of the present disclosure supplies the power stored in the high-voltage battery 120 to the auxiliary system if the solar-generated power from the solar power generation module 110 is not being supplied to the auxiliary system.

[0031] This control allows a large amount of power to be drawn from the high-voltage battery 120 to the auxiliary system, thereby improving the energy conversion efficiency of the bidirectional DC-DC converter 140 inserted between the high-voltage battery 120 and the auxiliary battery 130 during the pumping charging process.

[0032] Furthermore, in the solar charging system 100 according to one embodiment of the present disclosure, when a pumping charging process is requested from the high-voltage battery 120 to the auxiliary system, even if the solar-generated power of the solar power generation module 110 is already being supplied to the auxiliary system, if it is predicted that the auxiliary battery 130 will fall into an unfavorable state (depletion, low voltage) in the future, the power stored in the high-voltage battery 120 will be supplied to the auxiliary system.

[0033] By this control, although the energy conversion efficiency of the bidirectional DC-DC converter 140 is low, the progression of deterioration of the lifespan, performance, and the like of the auxiliary battery 130 can be suppressed.

[0034] 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 charging control method, 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]

[0035] The solar charging system of the present disclosure can be used in vehicles equipped with solar panels. [Explanation of symbols]

[0036] 100 Solar Charging System 110 Solar power generation module 120 High Voltage Battery 130 Auxiliary Battery 140 Bidirectional DC / DC Converter 200 Auxiliary load

Claims

1. A solar charging system mounted on a vehicle, a power generation module using a solar panel; an auxiliary system including an auxiliary battery that stores the power generated by the power generation module and an auxiliary load to which power is supplied from the auxiliary battery; a high-voltage battery used to drive the vehicle; a control unit provided between the high-voltage battery and the auxiliary system to control power transfer between the high-voltage battery and the auxiliary system, The control unit When power transfer from the high-voltage battery to the auxiliary system is requested, if the power generated by the power generation module is not being supplied to the auxiliary system, the power of the high-voltage battery is supplied to the auxiliary system; A solar charging system that supplies power from the high-voltage battery to the auxiliary system when the auxiliary battery is in a predetermined state even if the power generated by the power generation module is supplied to the auxiliary system.

2. 2. The solar charging system according to claim 1, wherein the predetermined state is a state in which the amount of stored electricity in the auxiliary battery decreases at a predetermined rate.

3. 2. The solar charging system according to claim 1, wherein the predetermined state is a state in which the voltage of the auxiliary battery decreases at a predetermined rate.

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