Power supply control device for on-board solar power generation system

Abstract

To enable effective use of electricity generated by on-board solar power systems. [Solution] A power supply control device 20 for an on-board solar power generation device 10, which is equipped on an electric vehicle 1 and comprises a solar panel 11 and a solar battery 12 for storing electricity generated by the solar panel 11, controls the power supply to the on-board solar power generation device 10, and the targets of power supply include a traction battery 6 that supplies power to a traction motor 5, a heater 7 that raises the temperature of the traction battery 6, and other on-board equipment 8, and includes a determination unit 21 that determines whether or not it is necessary to raise the temperature of the traction battery 6, and a power supply control unit 22 that, when it is determined that it is necessary to raise the temperature, preferentially supplies the electricity stored in the solar battery 12 to the heater 7, supplies any surplus electricity after supplying the heater 7 to the on-board equipment 8, and supplies any surplus electricity after supplying the on-board equipment 8 for charging the traction battery 6.

Description

Technical Field

[0001] The present invention relates to a power supply control device for an in-vehicle solar power generation device equipped on an electric vehicle.

Background Art

[0002] In recent years, various technologies have been developed for mounting solar panels on vehicles and using the electric power generated by these solar panels. For example, in Patent Document 1, in a truck equipped with a wing body type van body on a chassis frame behind the cab, solar panels for power generation are provided on the ceiling plate portion and side plate portion of the wing, and a battery for storing the electric power generated by these solar panels is provided.

[0003] Further, in Patent Document 2, in a charging system for an electric vehicle provided with a battery charged with electric power from a solar panel, when charging and discharging are performed at low temperature or extremely low temperature, a battery such as a lithium ion battery deteriorates or the charge and discharge amount is limited, or to avoid the difficulty of starting the driving battery due to extremely low temperature, there is disclosed a device that uses the electric power from the solar panel to raise the temperature of the driving battery with a heater.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in electric vehicles, increasing the capacity of the traction battery and improving the energy efficiency (distance traveled per unit of energy) are effective ways to increase the driving range without external charging, but there are limits to these methods. In this respect, equipping the vehicle with solar panels and using the electricity generated by these panels to power the vehicle is an effective approach.

[0006] However, electric vehicles are equipped with various on-board electrical devices, such as auxiliary equipment that operates on electricity, in addition to the drive motor. As described in Patent Document 2, the heater that warms the drive battery is also one of the auxiliary devices that operates on electricity. Therefore, we would like to make more effective use of the electricity generated by solar panels, including these auxiliary devices in addition to the drive battery.

[0007] This invention was conceived in response to these challenges, and one of its objectives is to provide a power supply control device for an on-board solar power generation system that can effectively utilize the power generated by the on-board solar power generation system while avoiding the need to protect the traction battery or the restrictions on the use of the traction battery. [Means for solving the problem]

[0008] This project was undertaken to solve at least some of the above-mentioned problems and can be implemented in the following forms or applications. The power supply control device for an on-board solar power generation system according to this application example is a power supply control device for an on-board solar power generation system that is installed on an electric vehicle that runs on a drive motor and controls the power supply of the on-board solar power generation system which comprises a solar panel and a solar battery that stores the electricity generated by the solar panel, wherein the targets of the power supply include a drive battery that supplies power to the drive motor, a heater that uses electricity to raise the temperature of the drive battery, and other on-board equipment that operates on electricity, and comprises a determination unit that determines whether or not it is necessary to raise the temperature of the drive battery, and a power supply control unit that, when the determination unit determines that it is necessary to raise the temperature, preferentially supplies the electricity stored in the solar battery to the heater, supplies any surplus electricity after supplying the heater to the on-board equipment, and supplies any surplus electricity after supplying the on-board equipment to charge the drive battery.

[0009] According to this application example, when it is necessary to raise the temperature of the traction battery, the power stored in the solar battery is preferentially supplied to the heater, and this heater raises the temperature of the traction battery. This prevents the traction battery from being charged or discharged while it is at a low temperature, suppresses the degradation of the traction battery, and avoids situations where the traction battery is used by limiting the amount of charging and discharging. Furthermore, the surplus power is supplied to on-board equipment and to charge the traction battery, so that the power generated by the on-board solar power generation system can be effectively utilized while avoiding the need to protect the traction battery or restrict its use. [Effects of the Invention]

[0010] According to this proposal, it will be possible to effectively utilize electricity generated by on-board solar power generation systems while avoiding the need to protect the traction battery or restricting its use. [Brief explanation of the drawing]

[0011] [Figure 1]This figure shows a vehicle and an on-board solar power generation system and its power supply control device according to one embodiment, where (a) is a schematic side view of the vehicle and (b) is a block diagram of the on-board solar power generation system and power supply control device. [Figure 2] This flowchart shows the control by the power supply control device of an on-board solar power generation system according to one embodiment. [Modes for carrying out the invention]

[0012] The embodiments of this invention will be described with reference to the drawings. The following embodiments are merely illustrative examples, and there is no intention to exclude various modifications or applications of techniques not explicitly shown in these embodiments. Each configuration of the embodiments described below can be modified in various ways without departing from their spirit. Furthermore, they can be selected or combined as needed.

[0013] [1. Structure] As shown in Figures 1(a) and 1(b), the electric vehicle 1 is equipped with a drive motor (electric motor for driving) 5 that rotates the drive wheels 4, a drive battery 6 that supplies power to the drive motor 5, a heater (electric heater that operates on electricity) 7 that raises the temperature of the drive battery 6, other on-board equipment (other than the drive motor 5) that operates on electricity (such as a PTC heater, air conditioner, heater, and other auxiliary equipment) 8, and an on-board equipment battery (auxiliary battery) 9 that supplies power to the on-board equipment 8. An electric truck (hereinafter also referred to as "electric truck 1" or simply "vehicle 1") is given as an example of electric vehicle 1. However, the electric vehicle 1 to which this invention can be applied is not limited to this. A lithium-ion battery is used for the drive battery 6, and a lead-acid battery is used for the on-board equipment battery 9.

[0014] Vehicle 1 is further equipped with an on-board solar power generation device 10 and a power supply control device 20 that controls the power supply from the on-board solar power generation device 10. The vehicle-mounted solar power generation device 10 includes a solar panel 11 for generating solar power and a solar battery (a battery for storing solar power) 12 for storing the electricity generated by the solar panel 11. Various types of batteries can be used for the solar battery 12; in this case, a lithium-ion battery is used, but it is also preferable to use a type of battery that can be used even at low temperatures. The power supply control device 20 includes a CPU, RAM, and a storage device (none of which are shown). The storage device stores the program as well as information used by the program.

[0015] The electric truck 1 of this embodiment is a cab-tilt vehicle in which the cab 2 located at the front of the vehicle tilts, and the solar panel 11 is installed at least on the roof portion 2R of the cab 2. In a cab-tilt vehicle, when the cab 2 tilts (see the dashed line in Figure 1(a)), the roof portion 2R also tilts forward along with the forward tilt of the cab 2, so if there is snow on the solar panel 11 on the roof portion 2R, it can be removed by tilting the cab.

[0016] The solar panels 11 may also be installed on other parts of the electric truck 1. For example, if a van body 3 is mounted, as in the electric truck 1 of this embodiment, the solar panels 11 may be installed on the walls or roof of the van body 3.

[0017] The power supply control device 20 controls the following items to be powered from the solar battery 12: the traction battery 6, the heater 7, and the on-board equipment (auxiliary equipment, etc.) 8 or the battery 9 for the on-board equipment. The power supply control device 20 monitors the charge status (remaining capacity) of the solar battery 12 and controls the power supply while prioritizing these items.

[0018] Batteries that repeat charging and discharging, such as lithium-ion batteries, deteriorate due to charging and discharging and the amount of charge and discharge may be limited when the temperature Tb of the battery becomes low (here, it is assumed that the temperature is lower than the lower limit temperature Tb0). Since the deterioration of the traction battery 6 and the limitation of the amount of charge and discharge will reduce the driving performance of the vehicle 1, it is extremely important for the electric vehicle 1 to use the traction battery 6 with the temperature Tb above the lower limit temperature Tb0. Therefore, it is effective to appropriately raise the temperature of the traction battery 6 by the heater 7.

[0019] Therefore, the power supply control device 20 includes a determination unit 21 that determines whether it is necessary to raise the temperature of the traction battery 6, and a power supply control unit 22 that preferentially supplies the power stored in the solar battery 12 to the heater 7 when the determination unit 21 determines that it is necessary to raise the temperature of the traction battery 6.

[0020] Specifically, the traction battery 6 is equipped with a temperature sensor 23 that detects the temperature of the traction battery 6. When the temperature Tb of the traction battery 6 detected by the temperature sensor 23 becomes equal to or lower than a preset temperature rise start temperature Tbs, the determination unit 21 determines that it is necessary to raise the temperature of the traction battery 6. Also, during the temperature rise of the traction battery 6, when the detected temperature Tb of the traction battery 6 reaches a preset temperature rise end temperature Tbe, it is determined that it is not necessary to raise the temperature of the traction battery 6. In this case, the temperature rise start temperature Tbs may be the above-mentioned lower limit temperature Tb0, or may be a temperature slightly higher (a small amount) than the lower limit temperature Tb0 by a margin. Also, the temperature rise end temperature Tbe is set to a temperature higher than the temperature rise start temperature Tbs. How much higher than the temperature rise start temperature Tbs can be set as appropriate.

[0021] Therefore, as shown in the flowchart of FIG. 2, the power supply control unit 22 controls the power supply from the solar battery 12. Note that the flow in FIG. 2 is always executed at a predetermined cycle even when the vehicle 1 is stopped if the control is on.

[0022] As shown in Figure 2, the power supply control unit 22 determines in the determination unit 21 whether or not it is necessary to raise the temperature of the traction battery 6 (step S10). If it is determined that it is necessary to raise the temperature of the traction battery 6, the power stored in the solar battery 12 is preferentially supplied to the heater 7 to raise the temperature of the traction battery 6 (step S20). Then the process proceeds to step S30. If it is not determined that it is necessary to raise the temperature of the traction battery 6, the process proceeds from step S10 to step S30.

[0023] In step S30, it is determined whether there is any surplus power (remaining capacity) in the solar battery 12 even after supplying power from the solar battery 12 to the heater 7 for a predetermined period to raise the temperature of the traction battery 6. This determination can be made, for example, by estimating the amount of power required for the heater 7 to raise the temperature of the traction battery 6 for a predetermined period, and then determining the amount of power stored in the solar battery 12 from the amount of power required for the heater 7.

[0024] If the solar battery 12 has remaining capacity even after supplying power to the heater 7, the process proceeds to step S40 to determine whether there is a power supply request for the in-vehicle equipment 8 or the battery for the in-vehicle equipment 9 (step S40). Here, for example, if the in-vehicle equipment 8 is operating or if the remaining capacity of the battery for the in-vehicle equipment 9 falls below a predetermined capacity, it is determined that there is a power supply request. If there is a power supply request, power is supplied from the solar battery 12 to the in-vehicle equipment 8 or the battery for the in-vehicle equipment 9 (step S50), and the process proceeds to step S60. On the other hand, if it is determined in step S30 that there is no remaining capacity, the process proceeds to return and terminates.

[0025] Furthermore, if it is not determined in step S40 that there is a power supply request for the in-vehicle equipment 8 or the battery 9 for the in-vehicle equipment, the process proceeds from step S40 to step S70. In step S60, it is determined whether the solar battery 12 has remaining capacity even after supplying power to the in-vehicle equipment 8 or the battery 9 for the in-vehicle equipment. If it is determined that the solar battery 12 has remaining capacity even after supplying power to the in-vehicle equipment 8 or the battery 9 for the in-vehicle equipment, the process proceeds to step S70. If it is determined in step S60 that there is no remaining capacity, the process proceeds to return and terminates.

[0026] Step S70 determines whether the traction battery 6 is rechargeable. If the traction battery 6 is rechargeable, power from the solar battery 12 is supplied to the traction battery 6 to charge it. Therefore, even if power is supplied to the heater 7 and to the on-board equipment 8 or the battery for the on-board equipment 9, if the solar battery 12 has remaining capacity, the traction battery 6 will be charged with power from the solar battery 12 if it is rechargeable.

[0027] Furthermore, it is assumed that the heating of the traction battery 6, that is, the power supply to the heater 7, will mainly occur when the vehicle 1 is stopped at night until the following morning. Also, while the vehicle 1 is running, the traction battery 6 will heat up due to charging and discharging, so the heating operation of the traction battery 6 by the heater 7 will not be necessary. For this reason, the power supply control unit 22 can determine whether or not there is a surplus of power from the amount of charge stored in the solar battery 12 and the estimated amount of power that should be supplied to the heater 7 during the period until the vehicle 1 starts running the following morning (a predetermined period).

[0028] Furthermore, for example, during the day, the electricity generated by the solar panel 11 is stored in the solar battery 12, so the amount of electricity stored in the solar battery 12 increases. Consequently, the amount of electricity stored in the solar battery 12 may reach its upper limit. In this case, the power supply control unit 22 controls the supply of the electricity stored in the solar battery 12 to the on-board equipment 8 or the battery for the on-board equipment 9, and further supplies any surplus electricity that remains after supplying the on-board equipment 8, etc., to charge the traction battery 6. However, afterwards (for example, at night), the amount of electricity to be supplied to the heater 7 is estimated from the expected nighttime temperature, etc., and this estimated amount of electricity to be supplied to the heater 7 is left in the solar battery 12.

[0029] Furthermore, if the season or region is warm and there is no need to raise the temperature of the traction battery 6, the power stored in the solar battery 12 is first controlled to be supplied to the on-board equipment 8 or the battery for the on-board equipment 9, and any surplus power remaining after supplying the on-board equipment 8, etc., is then supplied to charge the traction battery 6. Also, if it is determined that there is no need to supply power to the heater 7, the power from the solar battery 12 is supplied to the on-board equipment 8, the battery for the on-board equipment 9, or the traction battery 6 until the remaining capacity of the solar battery 12 reaches its lower limit.

[0030] [2. Action and Effects] Since the power supply control device 20 of the vehicle-mounted solar power generation device 10 according to this embodiment is configured as described above, the following operations and effects can be obtained. When it is necessary to raise the temperature of the traction battery 6, the power stored in the solar battery 12 is preferentially supplied to the heater 7, and this heater 7 raises the temperature of the traction battery 6. Therefore, the traction battery 6 is maintained above its lower limit temperature Tb0, preventing degradation of the traction battery 6 due to charging and discharging at low temperatures, avoiding situations where the amount of charging and discharging is limited, and ensuring good driving performance of the vehicle 1.

[0031] Furthermore, the surplus power is used to charge the on-board equipment 8, the batteries for the on-board equipment 9, and the traction battery 6. This allows for the effective use of power generated by the on-board solar power generation device 10 while avoiding the need to protect the traction battery 6 or restricting its use.

[0032] For example, by supplying power from the solar battery 12 to PTC heaters, air conditioners, and heating systems, which are relatively power-consuming components of the in-vehicle equipment 8, these devices can be used sufficiently without causing power shortages. Furthermore, by supplying power from the solar battery 12 to charge the traction battery 6, the driving range of the electric vehicle 1 can be extended.

[0033] Furthermore, when the traction battery 6 reaches its lower limit temperature state Tb0, the solar battery 12 also reaches its lower limit temperature state. However, at this time, the solar battery 12 itself heats up due to discharge from supplying power to the heater 7, thus avoiding the lower limit temperature state.

[0034] [3. Others] Although embodiments have been described above, the power supply control device in this case can also be implemented by appropriately modifying these embodiments. In the above embodiment, an electric truck 1 was used as an example of an electric vehicle, but the application of the power supply control device in this invention is not limited to this, and can be applied to various electric vehicles such as buses and passenger cars. Furthermore, the solar battery 12 may be configured to supply power to the outside of the electric vehicle 1. This allows power to be supplied to the outside of the electric vehicle 1 as needed, for example, during a disaster. In addition, since the solar battery 12 is capable of generating solar power, it can also continuously supply power in disaster areas. [Explanation of Symbols]

[0035] 1. Electric vehicles (vehicles, electric trucks) 2 Cab 2R Cab 2 roof section 3 Van Body 4 drive wheels 5. Motor for propulsion (electric motor for propulsion) 6. Battery for driving 7 Heater 8. In-vehicle equipment (auxiliary equipment, etc.) 9. Batteries for in-vehicle equipment (auxiliary batteries) 10. Vehicle-mounted solar power generation system 11 Solar Panels 12 Solar Batteries 20 Power supply control device 21 Judgment section 22 Power supply control unit 23 Temperature Sensor

Claims

[Claim 1] A power supply control device for an on-board solar power generation system, which is equipped on an electric vehicle that runs on a drive motor and comprises a solar panel and a solar battery for storing electricity generated by the solar panel, controls the power supply of the on-board solar power generation system, The objects of the power supply include a traction battery that supplies power to the traction motor, a heater that uses electricity to raise the temperature of the traction battery, and other on-board equipment that operates on electricity. A determination unit for determining whether or not it is necessary to raise the temperature of the traction battery, The power supply control unit, when the determination unit determines that heating is necessary, preferentially supplies power stored in the solar battery to the heater, supplies any surplus power remaining after supplying the heater to the in-vehicle equipment, and supplies any surplus power remaining after supplying the in-vehicle equipment to charge the traction battery. A power supply control device for an on-board solar power generation system, characterized by the following features.

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