Solar charging system

Abstract

To provide a solar charging system capable of inhibiting operation of charging being started but immediately suspended from being repeated.SOLUTION: A solar charging system 100 comprises a solar panel 110 and a control unit 120. The control unit 120 stops power supply to an auxiliary system 20 and charging to a driving battery 31 when a state in which supply power to the auxiliary system 20 is lower than the previous average value is continued for a first time, in the case that a lapse time from the power supply to the auxiliary system 20 and the charging to the driving battery 31 is shorter than a predetermined time. The control unit 120 stops the power supply to the auxiliary system 20 and the charging to the driving battery 31 when a state in which the charge power to the driving battery 31 is lower than a threshold value is continued for a second time, in the case that the lapse time is equal to or longer than the predetermined time.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to a solar charging system mounted on a vehicle.

Background Art

[0002] Patent Document 1 discloses a solar charging system mounted on a vehicle. This solar power generation system includes a solar panel, a driving battery, an auxiliary machine system, and a control unit. The auxiliary machine system is configured to include one or more auxiliary machines. The control unit controls the destination of the power generated by the solar panel.

[0003] The solar charging system disclosed in Patent Document 1 supplies power to the auxiliary machine system when the solar panel is generating power. And when the generated power of the solar panel is equal to or greater than a first power, charging of the driving battery is started. And the solar charging system disclosed in Patent Document 1 stops charging the driving battery when the generated power of the solar panel becomes equal to or less than a second power.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When the solar charging system starts up, various devices in the auxiliary system also start up. Therefore, the power consumption of the auxiliary system is high immediately after the solar charging system starts up. When the power consumption of the auxiliary system is high, most of the power generated by the solar panel is consumed by the auxiliary system. As a result, the above solar charging system stops charging the drive battery immediately after startup. If this operation of starting and stopping charging is repeated, it will lead to deterioration of the drive battery. [Means for solving the problem]

[0006] The following describes the means and effects of solving the above problems. The solar charging system for solving the above problems is a solar charging system mounted on a vehicle equipped with a drive system that drives the vehicle using electricity stored in a drive battery, and an auxiliary system comprising one or more auxiliary devices. This solar charging system comprises a solar panel and a control unit. In this solar charging system, if the elapsed time since the start of supplying power to the auxiliary system and charging the drive battery is less than a predetermined time, the control unit stops supplying power to the auxiliary system and charging the drive battery if the power supplied to the auxiliary system remains less than the average value of the power consumed by the auxiliary system during the previous charge of the drive battery for a first hour. If the elapsed time is equal to or greater than the predetermined time, the control unit stops supplying power to the auxiliary system and charging the drive battery if the power being charged to the drive battery remains less than a threshold for a second hour. [Effects of the Invention]

[0007] The solar charging system described above can prevent repeated cycles of starting and immediately stopping charging. [Brief explanation of the drawing]

[0008] [Figure 1]Figure 1 is a schematic diagram showing the configuration of a solar charging system according to an embodiment. [Figure 2] Figure 2 is an explanatory diagram illustrating the manner in which power is supplied to the auxiliary system and the drive battery is charged in the solar charging system of the embodiment. [Figure 3] Figure 3 is a time chart showing the changes in the commanded power values ​​supplied to the auxiliary equipment system. [Figure 4] Figure 4 is a flowchart showing the sequence of processes performed by the control unit of the solar charging system. [Modes for carrying out the invention]

[0009] An embodiment of the solar charging system will be described below with reference to Figures 1 to 4. <Configuration of Solar Charging System 100> As shown in Figure 1, the solar charging system 100 includes a solar panel 110 and a control unit 120. The solar panel 110 is made up of multiple solar cells arranged in a panel shape, which generate electricity from sunlight. The solar charging system 100 is installed on a vehicle that is equipped with a drive system 30 that drives the vehicle using electricity stored in a drive battery 31, and an auxiliary system 20 which includes one or more auxiliary devices.

[0010] The solar panel 110 may be installed, for example, on the roof of a vehicle. The solar panel 110 may also be installed on the hood of a vehicle. The vehicle's auxiliary system 20 includes an auxiliary battery 21. The auxiliary system 20 consists of multiple auxiliary devices and multiple control devices that operate using the power from the auxiliary battery 21 and the power generated by the solar panel 110. The multiple auxiliary devices include, for example, an electric oil pump, a navigation system, lamps, and various sensors. The multiple control devices include, for example, control devices for controlling each auxiliary device, a control device for the driver assistance system, and a control device for the authentication system. The vehicle's drive system 30 includes one or more motors for driving the vehicle. The vehicle's drive system 30 includes a drive battery 31 that supplies power to the motors.

[0011] The auxiliary battery 21 is charged with electricity generated by the solar panel 110. The auxiliary battery 21 is, for example, a nickel-metal hydride battery. The auxiliary battery 21 is not limited to a nickel-metal hydride battery and may be of other types. The drive battery 31 is a lithium-ion battery. The drive battery 31 is not limited to a lithium-ion battery and may be of other types.

[0012] <Configuration of control unit 120> As shown in Figure 1, the solar panel 110 is connected to the control unit 120. The auxiliary system 20 and the drive system 30 are also connected to the control unit 120. The control unit 120 comprises a first DC-DC converter 121, a second DC-DC converter 122, a third DC-DC converter 123, and a control device 124.

[0013] The first DC-DC converter 121 converts the electricity generated by the solar panel 110. The second DC-DC converter 122 converts the electricity converted by the first DC-DC converter 121 and supplies it to the auxiliary system 20. The third DC-DC converter 123 converts the electricity converted by the first DC-DC converter 121 and supplies it to the drive system 30.

[0014] The control device 124 controls the first DC-DC converter 121, the second DC-DC converter 122, and the third DC-DC converter 123. The control unit 120 is connected to the vehicle control unit 10. The vehicle control unit 10 includes a vehicle control device 11. The control unit 120 and the vehicle control unit 10 are connected to each other so that they can communicate with one another. The vehicle control unit 10 controls the auxiliary equipment system 20 and the drive system 30.

[0015] The vehicle control device 11 acquires the input current to the auxiliary battery 21 and the output current from the auxiliary battery 21 in the auxiliary system 20. The vehicle control device 11 calculates the power consumption in the auxiliary system 20 based on the acquired input current or output current, the voltage of the auxiliary battery 21, and the power supplied from the solar panel 110. The vehicle control device 11 calculates the charge level of the auxiliary battery 21. The vehicle control device 11 acquires the input current to the drive battery 31 and the output current from the drive battery 31 in the drive system 30. The vehicle control device 11 calculates the power consumption in the drive system 30 based on the acquired input current or output current and the voltage of the drive battery 31. The vehicle control device 11 calculates the charge level of the drive battery 31.

[0016] The vehicle control unit 10 sets a target value for the charge level of the auxiliary battery 21. The vehicle control unit 10 then calculates a command value for the power supply Waux to maintain the charge level at a target level within a certain range including the target value, and transmits it to the control unit 120. The control unit 120 measures the current and voltage of the power input to the first DC-DC converter 121 and calculates the power generated by the solar panel 110, Wgen.

[0017] As shown in Figure 2, the generated power Wgen is the power generated by the solar panel 110. The supplied power Waux is the power converted by the second DC-DC converter 122 and supplied to the auxiliary system 20. The control unit 120, having received a command value from the vehicle control unit 10, controls the second DC-DC converter 122 based on the command value to control the power supplied to the auxiliary system 20 in order to realize the supplied power Waux according to the command value.

[0018] The control unit 120 calculates the difference by subtracting the supply power Waux from the generated power Wgen. The control unit 120 uses the calculated difference as the charging power Wchg for the driving battery 31. As shown in FIG. 2, the charging power Wchg is the power that is converted by the third DC-DC converter 123 and used to charge the driving battery 31. The control unit 120 controls the third DC-DC converter 123 to charge the driving battery 31 so as to achieve the charging power Wchg.

[0019] As shown in FIG. 2, the solar charging system 100 divides the generated power Wgen generated by the solar panel 110 into the supply power Waux and the charging power Wchg, and supplies them to the auxiliary system 20 and the drive system 30. The charging power Wchg supplied to the driving battery 31 is the remaining power obtained by subtracting the supply power Waux supplied to the auxiliary system 20 from the generated power Wgen, as described above.

[0020] <Transition of the command value of the supply power Waux> FIG. 3 shows the transition of the command value of the supply power Waux to the auxiliary system 20. The time t_0 in FIG. 3 indicates the time when the control unit 120 is activated. When the control unit 120 is activated, together with the control device 124, each control device mounted on the vehicle is activated simultaneously. Then, each activated control device diagnoses whether it needs to continue operating. The control device diagnosed as not needing to continue operating shifts to the sleep state. In this way, the control devices not related to the control of the solar charging system 100 shift to the sleep state. And the control devices related to the control of the solar charging system 一百 continue to operate. The control devices related to the control of the solar charging system 100 are, for example, the control device 124 of the control unit 120 and the vehicle control device 11 of the vehicle control unit 10. Immediately after the control unit 120 is activated in this way, since many control devices are activated simultaneously, the power consumption of the auxiliary system 20 increases.

[0021] When the control unit 120 transitions to sleep mode, all control devices installed in the vehicle are simultaneously activated, just as when it is started up. Each activated control device then diagnoses whether or not it needs to continue operating. Control devices that are diagnosed as not needing to continue operating transition to sleep mode. Therefore, the power consumption of the auxiliary system 20 increases even when the control unit 120 transitions to sleep mode. The control unit 120 transitions to sleep mode when the solar panel 110 can no longer generate sufficient power. At this time, power from the auxiliary battery 21 is consumed. Therefore, the auxiliary battery 21 needs to be pre-charged with the power that will be consumed at this time.

[0022] Therefore, as shown in Figure 3, the vehicle control unit 10 sets the command value of the power supply Waux to a large value for a certain period after the control unit 120 is started, in order to cover the large power consumption and charge the auxiliary battery 21. This period after the control unit 120 is started, during which the command value of the power supply Waux is set to a large value, is called the post-startup charging period.

[0023] Then, when the control devices that do not need to continue operating enter a sleep state and power consumption decreases, and when charging of the auxiliary battery 21 is complete, the vehicle control unit 10 reduces the command value of the supplied power Waux. As shown in Figure 3, the vehicle control unit 10 gradually reduces the command value of the supplied power Waux as charging of the auxiliary battery 21 approaches completion, thereby ending the post-startup charging period.

[0024] After the charging period following startup, the vehicle control unit 10 calculates a command value for the power supply Waux to maintain the charge level of the auxiliary battery 21 at the target level, as described above. As described above, during the initial startup charging period of the solar charging system 100, the power Waux supplied to the auxiliary system 20 is high. As a result, almost all of the power Wgen generated by the solar panel 110 is consumed by the auxiliary system 20. This makes it difficult to secure enough power Wchg to charge the drive battery 31, causing charging to stop quickly. Repeated cycles of starting and stopping charging will lead to deterioration of the drive battery 31.

[0025] Therefore, the solar charging system 100 relaxes the requirements for continuing charging during a predetermined period immediately after startup, so that charging of the drive battery 31 can be continued even if the charging power Wchg is low.

[0026] <Routine executed by control unit 120> Next, the routine executed by the control unit 120 will be described with reference to Figure 4. The routine shown in Figure 4 is activated and executed by the control device 124 of the control unit 120 whenever the sleep state period reaches a certain time. When this routine is started, first in the process of step S100, the control device 124 calculates the generated power Wgen. The control device 124 calculates the generated power Wgen based, for example, on the closed-circuit voltage and outflow current of the solar panel 110.

[0027] In the next step S110, the control device 124 determines whether the generated power Wgen is greater than the first threshold Wx. The first threshold Wx is a threshold used to determine whether the solar panel 110 is generating enough power to charge the drive battery 31. The magnitude of the first threshold Wx is set in advance so that it can be determined that charging of the drive battery 31 is possible based on the generated power Wgen being greater than the first threshold Wx.

[0028] In step S110, if the control device 124 determines that the generated power Wgen is greater than the first threshold Wx (step S110: YES), the process proceeds to step S120.

[0029] In step S120, the control device 124 starts supplying power to the auxiliary system 20 and charging the drive battery 31. Specifically, the control device 124 controls the first DC-DC converter 121 and the second DC-DC converter 122 to start supplying power to the auxiliary system 20. The control device 124 controls the power supply to the auxiliary system 20 based on the command value received from the vehicle control unit 10. As described above, the control device 124 controls the second DC-DC converter 122 according to the command value in order to realize the supplied power Waux according to the command value.

[0030] The control device 124 controls the third DC-DC converter 123 to charge the drive battery 31. As described above, the control device 124 controls the third DC-DC converter 123 to supply the drive battery 31 with the remaining power after deducting the power supplied to the auxiliary system 20 (Waux) from the generated power Wgen.

[0031] In the next step, S130, the control device 124 counts the charging time Tchg. The charging time Tchg is the elapsed time since charging of the drive battery 31 began. In the next step, S140, the control device 124 determines whether the charging time Tchg is less than a predetermined time Tx.

[0032] In Figure 3, the period from time t_0 to time t_1 corresponds to the default time Tx. As shown in Figure 3, the length of the default time Tx is set to a length that allows it to be determined that the post-startup charging period has ended, in which the command value of the supplied power Waux is set to a large value based on the charging time Tchg being greater than or equal to the default time Tx.

[0033] In step S140, if the control device 124 determines that the charging time Tchg is less than the predetermined time Tx (step S140: YES), the process proceeds to step S150.

[0034] In step S150, the control device 124 determines whether the supplied power Waux has remained lower than the average value Waux_old for the first hour. The average value Waux_old is the average power consumption of the auxiliary system 20 during the previous charge of the drive battery 31. The average value Waux_old is calculated in step S180, which will be described later. In step S150, the average value Waux_old is used as a value that indicates the level of power consumption in the auxiliary system 20 under normal conditions, when it is not the post-startup charging period. In other words, step S150 is a process that determines whether it is not possible to supply a supplied power Waux that exceeds the power consumption of the auxiliary system 20 under normal conditions, or in other words, whether there is no power to allocate to charging the drive battery 31.

[0035] The power supply Waux used in step S150 is obtained by the control unit 120 from the vehicle control unit 10 by receiving the value of the power supplied to the auxiliary system 20. In other words, the power supply Waux used in step S150 is the measured value of the power supplied to the auxiliary system 20. The power supply Waux used in step S150 can also be a target value used by the control unit 120 to control the power supply Waux.

[0036] The first hour is a threshold used to determine if the supplied power (Waux) remains below the average value (Waux_old). For example, the length of the first hour can be preset to a range of a few seconds to a few minutes.

[0037] In step S150, if the control device 124 determines that the state in which the supplied power Waux is less than the average value Waux_old has not continued for the first time (step S150: NO), the process returns to step S130. In this case, the control device 124 executes the process from step S130 onward again.

[0038] In step S150, if the control device 124 determines that the supplied power Waux has remained below the average value Waux_old for the first time (step S150: YES), the process proceeds to step S170.

[0039] In step S170, the control device 124 terminates the supply of power to the auxiliary system 20 and the charging of the drive battery 31. In the next step, S180, the control device 124 updates the average value Waux_old. Specifically, the control device 124 calculates the average value of multiple supplied power Waux values ​​received from the vehicle control unit 10 while charging the drive battery 31. Then, the control device 124 substitutes the calculated average value into the average value Waux_old and updates the average value Waux_old.

[0040] In the next step, S190, the control device 124 puts the control unit 120 into a sleep state. Then, the control device 124 terminates this routine. In step S140, if the control device 124 determines that the charging time Tchg is equal to or greater than the predetermined time Tx (step S140: NO), the process proceeds to step S160.

[0041] In step S160, the control device 124 determines whether the state in which the charging power Wchg is less than the second threshold Wy has continued for two hours. The charging power Wchg used in step S160 is a value calculated by the vehicle control unit 10 based on information obtained from the drive system 30. In other words, the charging power Wchg used in step S160 is the measured value of the power being charged to the drive battery 31.

[0042] The control device 124 may use the difference between the generated power Wgen and the power consumption of the auxiliary system 20 as the charging power Wchg used in the processing of step S160. The power consumption of the auxiliary system 20 can be received from the vehicle control unit 10. In this case, the control device 124 determines that the charging power Wchg is less than the second threshold Wy when the difference between the generated power Wgen and the power consumption of the auxiliary system 20 is less than the second threshold Wy.

[0043] The second time period is a threshold used to determine if the charging power Wchg remains below the second threshold Wy. For example, the length of the second time period can be preset to a length of a few seconds to a few minutes. The length of the second time period may also be the same as the length of the first time period.

[0044] In step S160, if the control device 124 determines that the state in which the charging power Wchg is less than the second threshold Wy has not continued for two hours (step S160: NO), the process returns to step S130. In this case, the control device 124 executes the processes from step S130 onward again.

[0045] In step S160, if the control device 124 determines that the charging power Wchg has remained below the second threshold Wy for a second time (step S160: YES), the process proceeds to step S170.

[0046] In step S170, the control device 124 terminates the power supply to the auxiliary system 20 and the charging of the drive battery 31. In the next step, S180, the control device 124 updates the average value Waux_old.

[0047] In the next step, S190, the control device 124 puts the control unit 120 into a sleep state. Then, the control device 124 terminates this routine. In step S110, if the control device 124 determines that the generated power Wgen is less than or equal to the first threshold Wx (step S110: NO), the process proceeds to step S190. In this case, the control device 124 does not supply power to the auxiliary system 20 or charge the drive battery 31, and instead puts the control unit 120 into sleep mode. The control device 124 then terminates this routine.

[0048] <Operation of this embodiment> If the charging time Tchg is less than a predetermined time Tx, the control unit 120 stops supplying power to the auxiliary system 20 and charging the drive battery 31 if the power supplied to the auxiliary system 20 Waux remains less than the average value Waux_old for the first hour.

[0049] If the charging time Tchg is equal to or greater than a predetermined time Tx, the control unit 120 stops supplying power to the auxiliary system 20 and charging the drive battery 31 if the charging power Wchg to the drive battery 31 remains below the second threshold Wy for a second period of time.

[0050] If the power Waux supplied to the auxiliary system 20 is less than the average power consumption Waux_old of the auxiliary system 20 during the previous charge, it is highly probable that the power Waux supplied from the solar charging system 100 alone is insufficient to meet the power consumption. In other words, at this time, it is highly probable that the electricity generated by the solar panel 110 cannot be allocated to charging the drive battery 31.

[0051] In the solar charging system 100, the control unit 120 switches the conditions for stopping charging the drive battery 31 according to the charging time Tchg. Once the charging time Tchg exceeds a predetermined time Tx, the control unit 120 stops supplying power to the auxiliary system 20 and charging the drive battery 31 if the charging power Wchg to the drive battery 31 remains below the second threshold Wy for a second period of time. In other words, at this point, the control unit 120 requires that a stable level of charging power Wchg above a certain level be maintained in order to continue charging.

[0052] On the other hand, if the charging time Tchg is less than the predetermined time Tx, the control unit 120 stops supplying power to the auxiliary system 20 and charging the drive battery 31 if the power supplied to the auxiliary system 20 Waux remains less than the average value Waux_old for the first hour. In other words, at this time, the control unit 120 determines that there is a high probability that the electricity generated by the solar panel 110 cannot be allocated to charging the drive battery 31 and stops charging.

[0053] In short, the solar charging system 100 relaxes the requirements for continuing charging so that charging is more likely to continue if the charging time Tchg is less than the predetermined time Tx. <Effects of this embodiment> (1) In the solar charging system 100, even if the charging power Wchg falls below the second threshold Wy when the power consumption of the auxiliary equipment system 20 is high immediately after startup, charging will continue. In other words, the solar charging system 100 can suppress repeated operation of starting and immediately stopping charging.

[0054] (2) The drive system 30 may be equipped with a relay that cuts off the power supply from the third DC-DC converter 123 to the drive battery 31. If the operation of starting and immediately stopping charging is repeated, the relay will be opened and closed many times, which will cause the relay to deteriorate. The solar charging system 100 can suppress the number of times the relay is opened and closed.

[0055] (3) Repeated short-term charging of the drive battery 31 may cause the drive battery 31 to deteriorate. In contrast, the solar charging system 100 can prevent the charging from stopping immediately after it has started. Therefore, the deterioration of the drive battery 31 can be suppressed.

[0056] (4) In the solar charging system 100, the control unit 120 stops charging the drive battery 31, calculates the average value Waux_old, and then enters a sleep state.

[0057] According to the solar charging system 100, after stopping charging the drive battery 31, it enters a sleep state, which reduces power consumption compared to when the solar charging system 100 is kept running.

[0058] (5) In the solar charging system 100, the control unit 120 wakes up from sleep mode whenever a certain period of time has passed since the sleep mode. The control unit 120 calculates the power generated by the solar panel 110, Wgen. When the control unit 120 determines that the power generated Wgen is greater than the first threshold Wx, the control unit 120 starts supplying power to the auxiliary system 20 and charging the drive battery 31.

[0059] According to the solar charging system 100, even after entering sleep mode, if the power generated by the solar panel 110 (Wgen) increases, power supply to the auxiliary system 20 and charging of the drive battery 31 can be resumed.

[0060] (6) In the solar charging system 100, the control unit 120 controls the supplied power Waux based on a command value in order to maintain the charge level of the auxiliary battery 21 calculated by the vehicle control unit 10 at a target level. Therefore, the solar charging system 100 can control the supplied power Waux to maintain the charge level of the auxiliary battery 21 at a target level.

[0061] (7) The power consumption of the auxiliary system 20 varies depending on the number and type of options installed in the vehicle. The power consumption of the auxiliary system 20 also varies depending on how the vehicle is used by the user. For example, if a user frequently uses the air conditioner, the power consumption of the auxiliary system 20 will be high. The power consumption of the auxiliary system 20 also gradually changes due to aging. In the solar charging system 100, the average value Waux_old is used as an indicator value for the power consumption of the auxiliary system 20 under normal conditions in the processing of step S150. The solar charging system 100 updates the average value Waux_old when the control unit 120 is put into sleep mode. In this way, the solar charging system 100 executes the processing of step S150 using the latest average value Waux_old, which is close to the actual power consumption under normal conditions. Therefore, the solar charging system 100 can make accurate judgments in response to changes in power consumption under normal conditions due to the number and type of options in the vehicle, how the user uses the vehicle, and aging.

[0062] <Example of changes> This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0063] The solar charging system 100 may include multiple solar panels 110. In that case, the control unit 120 is provided with multiple DC-DC converters similar to the first DC-DC converter 121, each corresponding to one of the multiple solar panels 110.

[0064] The control device 124 and the vehicle control device 11 may be configured as a circuit including one or more processors that execute various processes according to a computer program (software). The control device 124 and the vehicle control device 11 may also be configured as a circuit including one or more dedicated hardware circuits, such as application-specific integrated circuits (ASICs), or a combination thereof, that execute at least some of the various processes. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions configured to cause the CPU to execute processes. Memory, or computer-readable media, includes any available media that can be accessed by a general-purpose or dedicated computer. [Explanation of symbols]

[0065] 10... Vehicle control unit 11... Vehicle control system 20... Auxiliary equipment system 21…Auxiliary battery 30…Drive System 31…Power battery 100... Solar charging system 110…Solar panels 120... Control Unit 121...First DC-DC converter 122...Second DC-DC converter 123...Third DC-DC converter 124...Control device

Claims

1. A solar charging system mounted on a vehicle equipped with a drive system that uses electricity stored in a drive battery to drive the vehicle, and an auxiliary system comprising one or more auxiliary devices, Equipped with solar panels and a control unit, If the control unit has started supplying power to the auxiliary system and charging the drive battery, and the elapsed time since the start of charging the drive battery is less than a predetermined time, the power supplied to the auxiliary system will remain lower than the average power consumption of the auxiliary system during the previous charge of the drive battery for a first hour, then the power supply to the auxiliary system and charging of the drive battery will be stopped. The control unit, when the elapsed time is equal to or greater than the predetermined time, stops supplying power to the auxiliary system and charging the drive battery if the charging power to the drive battery remains below a threshold for a second period of time. Solar charging system.

2. The control unit stops charging the drive battery, calculates the average value, and then enters a sleep state. The solar charging system according to claim 1.

3. The control unit wakes up from the sleep state each time the sleep state period reaches a certain time and starts supplying power to the auxiliary system and charging the drive battery if the power generated by the solar panel is greater than a threshold. The solar charging system according to claim 2.

4. The control unit determines that the charging power is less than the threshold when the difference between the power generated by the solar panel and the power consumed by the auxiliary system is less than the threshold. The solar charging system according to claim 1.

5. The vehicle is equipped with a vehicle control unit that controls the auxiliary system and the drive system, and the auxiliary system is equipped with an auxiliary battery. The vehicle control unit calculates the charge level of the auxiliary battery and calculates the command value of the power supply to maintain the charge level at a target level. Based on the command value calculated by the vehicle control unit, the control unit controls the power supply. The solar charging system according to claim 1.

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