Solar charging system

Abstract

This solar charging system provides efficient charging control while considering factors such as the charging current and charging speed of the auxiliary battery to suppress the progression of degradation. [Solution] A solar charging system mounted on a vehicle, comprising a solar panel, an auxiliary battery and a drive battery that can be charged using the power generated by the solar panel, and a control unit that controls the destination of the generated power based on a first threshold power that the solar panel can output and the amount of charge stored in the auxiliary battery, wherein the control unit sets the first threshold based on the charging current and charging speed of the auxiliary battery.

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 Art

[0002] Patent Document 1 discloses a solar charging system that controls the supply of electric power generated by a solar panel mounted on a vehicle. In this solar charging system, when the generated electric power of the solar panel is equal to or greater than a predetermined value and the stored electric quantity of the auxiliary battery is also equal to or greater than a predetermined value, power transfer from the solar panel and the auxiliary battery to the drive battery is performed to improve the charging efficiency by solar power generation.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the solar charging system described in Patent Document 1 above, since the charging current and charging speed when charging the auxiliary battery are not considered, there is a risk of accelerating the deterioration of the auxiliary battery (deteriorating the usability). Therefore, there is room for further consideration regarding a method for implementing efficient charging control while suppressing the progress of deterioration.

[0005] The present disclosure has been made in view of the above problems, and an object thereof is to provide a solar charging system that can perform efficient charging control while considering the charging current and charging speed of the auxiliary battery for suppressing the progress of deterioration.

Means for Solving the Problems

[0006] To solve the above problems, one aspect of the disclosed technology is a solar charging system mounted on a vehicle, comprising a solar panel, an auxiliary battery and a drive battery that can be charged using the power generated by the solar panel, and a control unit that controls the destination of the generated power based on a first threshold power that the solar panel can output and the amount of charge stored in the auxiliary battery, wherein the control unit sets the first threshold based on the charging current and charging speed of the auxiliary battery. [Effects of the Invention]

[0007] According to the solar charging system of this disclosure, the destination of the power generated by the solar panel is controlled according to a first threshold power based on the charging current and charging speed of the auxiliary battery and the amount of charge stored in the auxiliary battery, thereby enabling efficient charging control that suppresses the progression of deterioration of the auxiliary battery. [Brief explanation of the drawing]

[0008] [Figure 1] Block diagram of a solar charging system and its surrounding area according to one embodiment of the present disclosure. [Figure 2] Flowchart of the solar charging control process performed by the solar charging system [Figure 3] This figure shows an example of the boost efficiency characteristics of a DC-DC converter. [Figure 4] Diagram illustrating the charging path in state [A1] [Figure 5] Diagram illustrating the charging path in state [A2] [Figure 6] Diagram illustrating the charging path in state [B2] [Figure 7] Diagram illustrating the charging path in state [C2] [Figure 8] A diagram showing a list of each state in solar charging control. [Modes for carrying out the invention]

[0009] The solar charging system disclosed herein controls the charge levels of the drive battery and the auxiliary battery by controlling the power output from the solar power generation module and the power converted from the primary side to the secondary side by the DC-DC converter, in accordance with the power generated by the solar panel and the amount of charge stored in the auxiliary battery. Hereinafter, one embodiment of this disclosure will be described in detail with reference to the drawings.

[0010] <Embodiment> [composition] Figure 1 is a block diagram illustrating the schematic configuration of a solar charging system 100 and its surrounding parts according to one embodiment of the present disclosure. The solar charging system 100 illustrated in Figure 1 comprises a solar power generation module 110, a drive battery 120, an auxiliary battery 130, and a DC-DC converter 140. This solar charging system 100 is installed in vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs).

[0011] 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 or auxiliary load 200 connected to the solar power generation module 110. This solar power generation module 110 includes a solar panel 111, which is an assembly of solar cells, and outputs the power generated by the solar panel 111 at a predetermined voltage, obtained by Maximum Power Point Tracking (MPPT) control or the like. The power generated by the solar panel 111 is calculated from measurements taken by sensors (not shown).

[0012] The drive battery 120 is a rechargeable secondary battery, such as a lithium-ion battery. This drive battery 120 is connected to a main engine (not shown) for driving the vehicle and can supply the power necessary for the operation of this main engine. Examples of main engines include an electric motor for driving. The drive battery 120 is also connected to the solar power generation module 110 via a DC-DC converter 140 so that it can be charged by the power generated by the solar panel 111. The drive battery 120 is a high-voltage battery with a higher rated voltage than the auxiliary battery 130.

[0013] The auxiliary battery 130 is a rechargeable secondary battery, such as a lithium-ion battery. This auxiliary battery (auxiliary LiB) 130 can supply the power necessary for the operation of the auxiliary load 200. The auxiliary battery 130 is connected to the solar power generation module 110 so that it can be charged by the power generated by the solar panel 111. The auxiliary battery 130 is also connected to the DC-DC converter 140 so that it can be charged by the power stored in the drive battery 120. The amount of charge stored in the auxiliary battery 130 is monitored by a sensor (not shown). A small-capacity battery smaller in size, cost, and weight than a normal battery may be used for this auxiliary battery 130.

[0014] The DCDC converter 140 is a power converter that can convert the input power into power of a predetermined voltage and output it. This DCDC converter 140 has its primary side connected to the solar power generation module 110, the auxiliary battery 130, and the auxiliary load 200, and its secondary side connected to the driving battery 120. The DCDC converter 140 can supply the power output by the solar power generation module 110 connected to the primary side to the driving battery 120 connected to the secondary side. Also, the DCDC converter 140 can supply the power of the driving battery 120 connected to the secondary side to the auxiliary battery 130 and the auxiliary load 200 connected to the primary side. Therefore, this DCDC converter 140 can be a so-called bidirectional DCDC converter that boosts the input voltage on the primary side to the output voltage on the secondary side (during boost operation) and降压 the input voltage on the secondary side to the output voltage on the primary side (during buck operation).

[0015] The above-mentioned DCDC converter 140 constitutes a control unit that controls the power transfer between the driving battery 120 and the auxiliary battery 130 together with an electronic control unit (not shown) that controls the buck-boost operation. This control unit can acquire the power generated by the solar panel 111 of the solar power generation module 110 (solar power generation power), the stored power of the auxiliary battery 130, and the like.

[0016] The auxiliary load 200 is various auxiliary devices mounted on the vehicle. The auxiliary load 200 operates by receiving the supply of the power generated by the solar power generation module 110 or the power stored in the auxiliary battery 130. Examples of such auxiliary devices include lighting devices such as headlamps and interior lights, air conditioning devices such as heaters and air conditioners, and systems for autonomous driving and advanced driving assistance.

[0017] [Control] Next, referring further to FIGS. 2 and 3, the control performed in the solar charging system 100 according to the present embodiment will be described. FIG. 2 is a flowchart for explaining the processing procedure of solar charging control executed by the solar charging system 100. FIG. 3 is a diagram showing an example of the boost efficiency characteristics of the DCDC converter 140.

[0018] The solar charging control illustrated in FIG. 2 is started, for example, when the power generated by the solar panel 111 of the solar power generation module 110 is greater than the power consumption of an ECU or the like necessary to operate the solar charging control.

[0019] (Step S201) The solar charging system 100 determines whether the generated power of the solar panel 111 of the solar power generation module 110 is equal to or greater than a predetermined threshold value (hereinafter referred to as "third threshold value"). This determination is made to confirm whether solar charging can be efficiently performed on the driving battery 120. Therefore, the third threshold value is set with power for ensuring a high boost efficiency (charging efficiency) in consideration of the boost efficiency characteristics of the DCDC converter 140. For example, when the DCDC converter 140 has a boost efficiency characteristic in which the boost efficiency is higher as the input voltage from the primary side is higher, power corresponding to the desired boost efficiency is set as the third threshold value. In the example of FIG. 3, a predetermined value of power X or more at which the boost efficiency is equal to or higher than the high efficiency b is the third threshold value.

[0020] When the solar charging system 100 determines that the generated power of the solar panel 111 is equal to or greater than the third threshold value (Step S201, Yes), the process proceeds to Step S203. On the other hand, when the solar charging system 100 determines that the generated power of the solar panel 111 is less than the third threshold value (Step S201, No), the process proceeds to Step S202.

[0021] (Step S202) The solar charging system 100 determines whether the power generated by the solar panel 111 of the solar power generation module 110 is equal to or greater than a predetermined threshold (hereinafter referred to as the "first threshold"). This determination is made to confirm whether solar charging can be performed on the auxiliary battery 130 when high-efficiency operation of the DC-DC converter 140 cannot be ensured. Therefore, the first threshold is set to a power value based on a limit value for the charging current that minimizes the impact on the degradation of the auxiliary battery 130. Specifically, since lithium-ion batteries degrade and their capacity decreases as the number of charge-discharge cycles increases, it is desirable to set a power value that can suppress the number of charge-discharge cycles by considering the balance between the charging current to be limited to the auxiliary battery 130 and the charging speed to be ensured. The first threshold is a smaller value than the third threshold mentioned above.

[0022] If the solar charging system 100 determines that the power generated by the solar panel 111 is equal to or greater than the first threshold (step S202, yes), the process proceeds to step S204. On the other hand, if the solar charging system 100 determines that the power generated by the solar panel 111 is less than the first threshold (step S202, no), the process proceeds to step S205.

[0023] (Step S203) The solar charging system 100 determines whether the amount of charge stored in the auxiliary battery 130 is equal to or greater than a second threshold. This determination is made to determine whether there is enough power stored in the auxiliary battery 130 to eliminate the need for charging. The second threshold is set based on whether the auxiliary battery 130 alone can cover the standby current (dark current) consumed by the auxiliary load 200 while the vehicle is parked. More specifically, the second threshold is set to the amount of charge obtained by adding the power corresponding to the total amount of standby current consumed by the auxiliary load 200 during the expected parking period to the minimum power that needs to be secured to start the vehicle.

[0024] If the solar charging system 100 determines that the amount of charge stored in the auxiliary battery 130 is equal to or greater than the second threshold (step S203, yes), the process proceeds to step S206. On the other hand, if the solar charging system 100 determines that the amount of charge stored in the auxiliary battery 130 is less than the second threshold (step S203, no), the process proceeds to step S207.

[0025] (Step S204) The solar charging system 100 determines whether the amount of charge stored in the auxiliary battery 130 is equal to or greater than a second threshold. This determination and the second threshold are the same as those described in step S203 above.

[0026] If the solar charging system 100 determines that the amount of charge stored in the auxiliary battery 130 is equal to or greater than the second threshold (step S204, yes), the process proceeds to step S208. On the other hand, if the solar charging system 100 determines that the amount of charge stored in the auxiliary battery 130 is less than the second threshold (step S204, no), the process proceeds to step S209.

[0027] (Step S205) The solar charging system 100 determines whether the amount of charge stored in the auxiliary battery 130 is equal to or greater than a second threshold. This determination and the second threshold are the same as those described in step S203 above.

[0028] If the solar charging system 100 determines that the amount of charge stored in the auxiliary battery 130 is equal to or greater than the second threshold (step S205, yes), the process proceeds to step S208. On the other hand, if the solar charging system 100 determines that the amount of charge stored in the auxiliary battery 130 is less than the second threshold (step S205, no), the process proceeds to step S210.

[0029] (Step S206) The solar charging system 100 performs charge control (state [A1]) that outputs the power generated by the solar panel 111 only to the drive battery 120. Figure 4 shows the charging path in state [A1] with arrows. As shown in Figure 4, in this state [A1], all of the power generated by the solar panel 111 is used to charge the drive battery 120 through the control of the DC-DC converter 140.

[0030] When the solar charging system 100 performs charging control according to state [A1], this solar charging control ends.

[0031] (Step S207) The solar charging system 100 performs charge control (state [A2]) that distributes the power generated by the solar panel 111 to the drive battery 120 and the auxiliary battery 130. Figure 5 shows the charging path in state [A2] with arrows. As shown in Figure 5, in this state [A2], the portion of the power generated by the solar panel 111 corresponding to the third threshold is used to charge the drive battery 120, and the surplus power is used to charge the auxiliary battery 130.

[0032] When the solar charging system 100 performs charging control according to state [A2], this solar charging control ends.

[0033] (Step S208) Since the solar charging system 100 cannot charge either the drive battery 120 or the auxiliary battery 130, the solar power generation module 110 does not output power from the solar panel 111 (state [B1], state [C1]).

[0034] When the solar charging system 100 performs charging control based on state [B1] and state [C1], this solar charging control ends.

[0035] (Step S209) The solar charging system 100 performs charge control (state [B2]) that outputs the power generated by the solar panel 111 to the auxiliary battery 130 only, with a current limit. Figure 6 shows the charging path in state [B2] with arrows. As shown in Figure 6, in this state [B2], all of the power generated by the solar panel 111 is used to charge the auxiliary battery 130, while the power output by the solar power generation module 110 is controlled so that the charging current to the auxiliary battery 130 does not exceed a limit.

[0036] When the solar charging system 100 performs charging control according to state [B2], this solar charging control terminates.

[0037] (Step S210) The solar charging system 100 performs charge control (state [C2]) that outputs the power generated by the solar panel 111 to the auxiliary battery 130 without current limiting. Figure 7 shows the charging path in state [C2] with arrows. As shown in Figure 7, in this state [C2], all of the power generated by the solar panel 111 is used to charge the auxiliary battery 130 without limiting the charging current to the auxiliary battery 130.

[0038] When the solar charging system 100 performs charging control according to state [C2], this solar charging control ends.

[0039] In the above processing flow, solar charging control is terminated when charging control is performed in any of the states from step S206 to step S210. However, it is also possible to return to step S201 and repeatedly execute solar charging control.

[0040] Furthermore, Figure 8 shows a list of the states in the solar charging control described above. In this embodiment, a first threshold and a third threshold are set as judgment thresholds for the power generated by the solar panel 111, and a second threshold is set as a judgment threshold for the amount of charge stored in the auxiliary battery 130, thereby achieving efficient charging control.

[0041] <Effects and Actions> As described above, according to the solar charging system 100 according to one embodiment of the present disclosure, the destination of the power generated by the solar panel 111 is dynamically controlled based on a first threshold for the power generated by the solar panel 111, which is set based on the charging current and charging speed of the auxiliary battery 130, and a second threshold for the amount of charge stored in the auxiliary battery 130, which is set based on the current consumption of the auxiliary load 200 while parked. This control enables efficient charging control that suppresses the progression of deterioration of the auxiliary battery 130.

[0042] Although one embodiment of the disclosed technology has been described above, the disclosure can be understood not only as a solar charging system, but also as a method for controlling solar charging, a program for the method, a computer-readable non-temporary storage medium storing the program, a vehicle equipped with a solar charging system, and so on. [Industrial applicability]

[0043] The solar charging system described herein can be used in vehicles equipped with solar panels, etc. [Explanation of symbols]

[0044] 100 Solar Charging Systems 110 Solar Power Modules 111 Solar Panels 120 Power Battery 130 Auxiliary Battery 140 DC-DC converters 200 Auxiliary load

Claims

1. A solar charging system mounted on a vehicle, Solar panels and An auxiliary battery and a drive battery that can be charged using the power generated by the solar panel, The system includes a control unit that controls the destination of the generated power based on a first threshold power output by the solar panel and the amount of charge stored in the auxiliary battery, The control unit sets the first threshold based on the charging current and charging speed of the auxiliary battery. Solar charging system.

2. The control unit supplies all of the generated power to the auxiliary battery if the generated power is less than the first threshold and the stored energy is less than the second threshold set based on the load current consumption while parked. The solar charging system according to claim 1.

3. The control unit supplies all of the generated power to the auxiliary battery with current limiting when the generated power is equal to or greater than the first threshold and less than the third threshold set based on the charging efficiency of the drive battery, and the amount of stored energy is less than the second threshold set based on the load current consumption while parked. The solar charging system according to claim 1.

4. The control unit supplies all or part of the generated power to the drive battery if the generated power is equal to or greater than a third threshold value set based on the charging efficiency of the drive battery. The solar charging system according to claim 1.

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