Vehicle control system

Abstract

One aspect of the present invention provides a novel control system in which a lead-acid battery is used as a starter battery and which is capable of causing a vehicle to travel even when the lead-acid battery cannot be used. In a vehicle (hybrid vehicle) in which a third power supply and a DC / DC converter are newly provided and which has an internal combustion engine, a second power supply, which is a lead-acid battery, is used as a starter battery, and a lithium ion secondary battery the output voltage of which is 24-60 V is provided as the third power supply.

Description

Vehicle control system

[0001] One aspect of the present invention relates to an article, a method, or a manufacturing method. Alternatively, the present invention relates to a process, a machine, a manufacture, or a composition of matter. One aspect of the present invention relates to a semiconductor device, a display device, a light-emitting device, a power storage device, a lighting device, an electronic device, or a manufacturing method thereof. Also, one aspect of the present invention relates to a vehicle control device or a control system.

[0002] In this specification, the power storage device refers to elements and devices having a power storage function in general. For example, it includes storage batteries (also referred to as secondary batteries) such as lithium-ion secondary batteries, lithium-ion capacitors, nickel-hydrogen batteries, all-solid-state batteries, and electric double layer capacitors.

[0003] Electronic devices carried by users and electronic devices worn by users are being actively developed.

[0004] Both electronic devices carried by users and electronic devices worn by users are also called portable information terminals. The portable information terminal operates using a primary battery or a secondary battery, which is an example of a power storage device, as a power source. The portable information terminal is desired to be used for a long time, and for this purpose, a large-capacity secondary battery may be used. When a large-capacity secondary battery is incorporated into the portable information terminal, there is a problem that the large-capacity secondary battery is large and heavy. Therefore, the development of small or thin and large-capacity secondary batteries that can be incorporated into portable information terminals is underway.

[0005] In particular, lithium-ion secondary batteries with high output and high energy density are rapidly expanding in demand along with the development of the semiconductor industry, such as portable information terminals such as mobile phones, smartphones, or notebook computers, portable music players, digital cameras, medical devices, or next-generation clean energy vehicles such as hybrid vehicles (HV), electric vehicles (EV), or plug-in hybrid vehicles (PHV). It has become an essential source of rechargeable energy in modern information society.

[0006] Patent Document 1 discloses a control system and a vehicle for controlling two types of lithium-ion batteries mounted on an electric vehicle.

[0007] WO2024 / 095111

[0008] Conventional vehicles have a starter battery to supply a large current instantaneously when starting the engine, and 12V lead-acid batteries are the mainstream. In addition, electrical components installed in cars have traditionally been 12V-driven products. Examples of electrical components include headlamp parts, wiper drive parts, car navigation systems, and audio equipment.

[0009] Furthermore, even electric vehicles (EVs) that do not have an internal combustion engine have a starter battery, and 12V lead-acid batteries are mainly used for starting the motor and for electrical components.

[0010] Similarly, 12V lead-acid batteries are used as starter batteries in hybrid vehicles (HVs) and plug-in hybrid vehicles (PHVs).

[0011] While it is possible to use lithium-ion rechargeable batteries as starter batteries, lithium-ion batteries do not function well in low-temperature ranges, and considering cost and track record, lead-acid batteries remain advantageous.

[0012] Lead-acid batteries are superior to lithium-ion rechargeable batteries in that they can operate from low to high temperatures. However, lead-acid batteries have several drawbacks, including high self-discharge, a chemical reaction unique to lead-acid batteries called sulfation which reduces capacity, and the generation of flammable gases during charging. Because of the generation of flammable gases, they are placed outside the vehicle's interior rather than inside.

[0013] Another option is to keep a lead-acid battery in the vehicle's trunk or elsewhere as a spare. However, lead-acid batteries contain electrolyte and have openings for releasing gas, so if they are shaken or tip over and placed on their side, they may leak and become unusable.

[0014] If the lead-acid battery installed in a vehicle experiences natural discharge (also called self-discharge) and the output voltage falls below a certain value, the vehicle's internal combustion engine cannot be started, rendering it inoperable. This applies not only to vehicles with internal combustion engines, but also to electric vehicles that still have sufficient charge in the main secondary battery supplying power to the electric motor.

[0015] Lead-acid batteries, in particular, experience self-discharge, causing their capacity to decrease over time. It is said that if the vehicle is not driven and the battery is not charged for more than a month, the output voltage will fall below the standard value. Even when the engine or motor is not running, electrical components are connected to the lead-acid battery, causing a small current to flow. Therefore, lead-acid batteries require regular driving or charging. Furthermore, lead-acid batteries also require periodic replacement.

[0016] Furthermore, in recent years, vehicles have been equipped with many electrical components in addition to car navigation systems, such as driver assistance functions, dashcams, temperature control functions, and electronic mirrors, which increases the load on lead-acid batteries and accelerates their deterioration.

[0017] Furthermore, the starter batteries in hybrid vehicles or electric vehicles (EVs) have more electrical components and therefore a greater load than those in conventional vehicles with only internal combustion engines, which can cause them to deteriorate more easily and potentially render lead-acid batteries unusable.

[0018] One aspect of the present invention aims to provide a novel control system that uses a lead-acid battery as a starter battery and can operate a vehicle even if the lead-acid battery becomes unusable.

[0019] One configuration disclosed herein is a control system for a vehicle that runs on the output of a drive motor, the vehicle comprising: a first power supply that supplies power to the drive motor via a first DC / DC converter; a control unit that controls the first power supply; a second power supply with a lower output voltage than the first power supply; a third power supply with an output voltage between the output voltage of the first power supply and the output voltage of the second power supply; a control unit that controls the third power supply; and a second DC / DC converter for stepping down the output of the third power supply, wherein when the second power supply starts the drive motor, the power supply from the third power supply is stopped, and when the third power supply starts the drive motor using the second DC / DC converter, the power supply from the second power supply is stopped.

[0020] In the case of a hybrid vehicle, one of the configurations disclosed herein is a control system for a vehicle that runs on the output of an internal combustion engine or a drive motor, wherein the vehicle has a first power supply that supplies power to the drive motor via a first DC / DC converter, a second power supply that starts the internal combustion engine, a third power supply different from the first and second power supplies, a connection part that allows the third power supply to be attached to and detached from the passenger compartment of the vehicle, a control unit that controls the first and third power supplies, and a second DC / DC converter for stepping down the output of the third power supply, wherein when the second power supply starts the internal combustion engine, the third power supply can be disconnected from the connection part, and when the third power supply starts the internal combustion engine using the second DC / DC converter, the power supply from the second power supply is stopped.

[0021] In the above configuration, the control unit controls the charging of the third power supply at a SOC of 40% to 60%. The control unit controls the charging of the first power supply at a SOC of 0% to 100%. The control unit has at least a charging control circuit, but may also include an electronic control unit (also called an ECU (Electronic Control Unit)) or a communication control unit for the in-vehicle network. The in-vehicle network typically uses a standard called CAN (Controller Area Network), but is not particularly limited. The control unit may also have a motor control circuit (also called a PCU (Power Control Unit)) or an engine starting circuit.

[0022] In the above configuration, the second power source is a lead-acid battery, and the output voltage of the second power source is between 12V and 16V. In addition, in the above configuration, the output voltage of the third power source is between 24V and 60V.

[0023] In the above configuration, when the second power supply malfunctions, the power supply is switched from the second power supply to the third power supply by turning off the first switch located between the second power supply and the control unit, and turning on the second switch located between the third power supply and the control unit.

[0024] Hybrid vehicles or electric vehicles have a nickel-metal hydride or lithium-ion secondary battery as a first power source for motor drive and a lead-acid battery as a second power source for the starter battery. Therefore, a third power source and a DC / DC converter are newly added to such hybrid vehicles or electric vehicles, and in vehicles with an internal combustion engine (hybrid vehicles), a lead-acid battery is used as the second power source for the starter battery, and a lithium-ion secondary battery with an output voltage of 24V to 60V is used as the third power source. Voltages exceeding 60V are subject to strict safety standards due to the risk to human health. To meet these strict safety standards, costs increase, so the voltage is set to 60V or less, preferably 48V.

[0025] Lithium-ion secondary batteries have a lower self-discharge rate and a longer lifespan when stored unused compared to lead-acid batteries. However, lithium-ion secondary batteries degrade easily when stored fully charged. Therefore, the control unit maintains the State of Charge (SOC) at 40% to 60%, preferably around 50%, and uses it as an independent power source. Consequently, the output voltage of the fully charged lithium-ion secondary battery as the third power source is between 24V and 60V.

[0026] The second power source, a lead-acid battery used as a starter battery, has an output voltage of 12V and is constantly connected to the vehicle's electrical components, so a small amount of power is consumed. Lead-acid batteries used as starter batteries are susceptible to damage because they consume a large amount of instantaneous power when starting the engine, and the more times the engine is started, the faster they deteriorate. In addition, the second power source, a lead-acid battery, is controlled to always be fully charged, and if the State of Charge (SOC) falls below 70%, it will no longer function as a starter battery.

[0027] If the lead-acid battery becomes unusable as a starter battery for any reason, the system can switch to a third power source and use it as a starter battery with a DC / DC converter. Switching from the second power source to the third power source in the event of a malfunction in the second power source is done by turning off a first switch located between the second power source and the control unit, and turning on a second switch located between the third power source and the control unit. Because the third power source is connected via the second switch, it is not constantly connected to the vehicle's electrical components, and its capacity is preserved. Furthermore, the lithium-ion secondary battery of the third power source can be installed in the vehicle's cabin, and it is preferable that it be portable as a removable (also called detachable) battery cassette.

[0028] By using a battery cassette, the driver can carry the battery cassette to their home or a dealer and adjust the charge level to allow for long-term storage, specifically, a State of Charge (SOC) of 40% to 60%, preferably around 50%. Furthermore, by connecting a connector to the battery cassette, the driver can use it as an emergency power source at home.

[0029] The battery cassette preferably has a structure in which multiple cylindrical batteries are connected in series. For example, it may consist of 12 cylindrical batteries, each with an average output voltage of 4V or more. Alternatively, the battery cassette may be designed so that each cylindrical battery can be removed by the user.

[0030] Furthermore, in electric vehicles, a second power source, which is a lead-acid battery, is used as the starter battery; a third power source is a lithium-ion secondary battery with an output voltage of 24V to 60V; and a first power source, which is the main battery, is a lithium-ion secondary battery with an output voltage of 300V to 800V.

[0031] The starter battery refers to a battery other than the main battery. In hybrid vehicles, the starter battery is the secondary battery that starts the starter motor when the driver presses the start switch (also called the ignition switch) to start the internal combustion engine. In electric vehicles, the starter battery is the secondary battery used before the main battery starts the motor after the driver presses the start switch to turn on the system main relay (also called the SMR) and turn on the power line.

[0032] In this specification, output voltage refers to the open-circuit voltage in a current-free state.

[0033] While lead-acid batteries have a lifespan of less than four years, lithium-ion rechargeable batteries can have a lifespan equal to that of the vehicle itself, potentially eliminating the need for replacement.

[0034] In this specification, SOC stands for State Of Charge and is a value representing the charge state of a battery (between 0% and 100%). In this specification, SOC is defined as 100% when the battery is fully charged at the time of shipment. SOC is also called the charge rate or estimated remaining charge. In charging and discharging in a vehicle equipped with a battery, the upper limit SOC, which is the SOC at which charging of the battery ends, is set lower than the full charge SOC. The SOC at which charging of the battery ends is determined by the charging control circuit. A single battery has a defined range of open-circuit voltage values ​​(output voltage) for normal use, and the charging control circuit controls charging and discharging to occur between the lower limit voltage value and the upper limit voltage value. The lower limit voltage value is defined as SOC 0%, and the upper limit voltage value is defined as SOC 100%.

[0035] Even if the lead-acid starter battery becomes unusable for any reason, a switch can be used to switch to a lithium-ion secondary battery as a third power source, allowing the hybrid vehicle (HV), electric vehicle (EV), or plug-in hybrid vehicle (PHV) to be started.

[0036] Figure 1 is a block diagram showing one embodiment of the present invention. Figure 2 is a block diagram showing one embodiment of the present invention. Figure 3 is a block diagram showing one embodiment of the present invention. Figure 4 is a block diagram showing one embodiment of the present invention. Figure 5 is a block diagram of a conventional EV vehicle. Figure 6 is a photograph of the external appearance of a cylindrical secondary battery. Figures 7A and 7B are schematic diagrams showing the structure of a cylindrical secondary battery, and Figure 7C is a diagram showing the dimensions of a cylindrical secondary battery. Figure 8A is a diagram showing the charge and discharge characteristics of a cylindrical secondary battery, and Figure 8B is a diagram showing the cycle characteristics.

[0037] Embodiments of the present invention will be described in detail below with reference to the drawings. However, it will be readily apparent to those skilled in the art that the present invention is not limited to the following description, and its form and details can be modified in various ways. Furthermore, the present invention is not to be interpreted as being limited to the embodiments described below.

[0038] In this specification, the terms "first" and "second" may be used for convenience to understand the technical content or to identify each component. Therefore, the terms "first" and "second" do not limit the number of each component. Nor do the terms "first" and "second" limit the order of each component. Furthermore, the terms "first" and "second" or identification codes used in this specification may not correspond to the terms or identification codes in the claims of this patent.

[0039] (Embodiment 1) Figure 1 is an example of a block diagram showing the schematic configuration of an electric vehicle (EV) as one embodiment.

[0040] The electric vehicle (EV) of this embodiment has a first secondary battery 101 of the main battery, a second secondary battery 102 of the starter battery, and a third secondary battery 103.

[0041] When the second secondary battery 102 fails to function as a starter battery for some reason, it has a first switch 131 for turning off the connection of the second secondary battery 102 and a second switch 132 for switching the third secondary battery 103 as a starter battery. The first switch 131 is connected to the control unit 120 via a diode. Also, the second switch 132 is connected to the control unit 120 via a diode. The control unit 120 controls so that either one of the first switch 131 and the second switch 132 is in the on state and the other is in the off state. Specifically, when there is an abnormality in the second secondary battery 102, the power supply voltage drops, and when it falls below the threshold value, the second switch 132 switches to the on state, and power is supplied from the third secondary battery 103.

[0042] The second secondary battery 102 is a lead-acid battery with an output voltage of 12 V or more and 16 V or less.

[0043] The third secondary battery 103 is a lithium-ion secondary battery with an output voltage of 24 V or more and 60 V or less. The third secondary battery 103 is stepped down by the second DC-DC 112 (also called the second DC / DC converter), and power is supplied to the electrical component 108. Note that the third secondary battery 103 is not always connected, and when the second switch 132 is in the on state, power is supplied to the electrical component 108.

[0044] When the second secondary battery 102 fails to function as a starter battery for some reason, when the user turns on the start switch 121, the control unit 120 turns on the second switch 132, and power from the third secondary battery 103 is supplied to the electrical component 108 via the second DC-DC 112. Also, when the second switch 132 is turned on, the control unit 120 turns on the SMR 122, and power from the first secondary battery 101 is supplied via the fourth DC-DC 114 and the inverter 107, enabling the motor 105 to be driven.

[0045] Note that the SMR 122 is a system main relay that electrically disconnects the main battery in the off state of the system for safety.

[0046] Normally, the control unit 120 controls the third DC-DC 113 (also referred to as the third DC / DC converter), and during regenerative charging, the charging amount is adjusted so that the SOC of the third secondary battery 103 is 40% or more and 60% or less, preferably about 50%.

[0047] On the other hand, the second secondary battery 102 is charged via the first DC-DC 111 (also referred to as the first DC / DC converter) so that the SOC of the second secondary battery 102 becomes 100% during regenerative charging.

[0048] Also, the output voltage of the first secondary battery 101 is 300V or more and 800V or less, and during regenerative charging, it is charged so that the SOC approaches 100%.

[0049] The third secondary battery 103 is a lithium-ion secondary battery with an output voltage of 24V or more and 60V or less. For example, if it is 48V, electrical components driven by 48V can be mounted on the vehicle. Therefore, a power supply line for the third system can be provided in the vehicle.

[0050] In addition, the third secondary battery 103 can be made detachable so that it can be carried as a battery cassette.

[0051] For comparison, FIG. 5 shows a block diagram schematically showing the configuration of a conventional electric vehicle (EV).

[0052] An electric vehicle (EV) has a first secondary battery 101 as a main battery and a second secondary battery 102 as a starter battery.

[0053] In the conventional second secondary battery 102, a lead-acid battery of 12V or more and 16V or less is used and is constantly connected to the electrical component 108. When the start switch 121 is turned on, the control unit 520 turns on the SMR 122, and the power from the first secondary battery 101 is supplied via the fourth DC-DC 114 (also referred to as the fourth DC / DC converter) and the inverter 107, enabling the motor 105 to be driven.

[0054] The second secondary battery 102 is charged via the first DC-DC 111 so that the SOC of the second secondary battery 102 becomes 100% during regenerative charging.

[0055] Furthermore, the first secondary battery 101 has an output voltage of 300V to 800V, and is charged during regenerative charging so that the State of Charge (SOC) approaches 100%.

[0056] Therefore, conventional electric vehicles (EVs) have a first power line system for the second secondary battery 102 and a second power line system for the first secondary battery 101.

[0057] In conventional vehicles, the secondary battery 102 is constantly connected to the electrical components 108 and also supplies power to the control unit 520. As a result, the lead-acid battery, which is the secondary battery 102, is easily depleted, and when the SOC falls below 70%, even if the SOC of the primary battery 101 is 100%, the control unit 520 cannot turn on the SMR 122, making it impossible to move the vehicle.

[0058] Furthermore, in conventional vehicles, the secondary battery 102 would self-discharge if not used for a long period of time, such as more than one month, rendering the vehicle unable to operate.

[0059] In this embodiment, even if the lead-acid battery, which is the second secondary battery 102, falls below 70%, the system can switch to the third secondary battery 103 and the control unit 520 can turn on the SMR 122. Furthermore, even if the lead-acid battery self-discharges due to long-term non-use of more than one month, the charge level of the third secondary battery 103 is adjusted so that its SOC is between 40% and 60%, preferably around 50%. This allows the charge level of the third secondary battery 103 to be maintained even if it is not used for another month or more, thus enabling the vehicle to be operated.

[0060] Furthermore, Figure 2 shows a block diagram of an electric vehicle (EV) under normal conditions, and Figure 3 shows a block diagram of an electric vehicle (EV) in an emergency situation where the second secondary battery 102 cannot be used.

[0061] As shown in Figure 2, under normal circumstances, the second switch 132 is in the OFF state, so power is not supplied from the third secondary battery 103 to the electrical components 108, and only regenerative charging is performed on the third secondary battery 103.

[0062] As shown in Figure 3, in an emergency, the second switch 132 is turned ON, and power is supplied to the electrical components 108 from the third secondary battery 103. Regenerative charging of the third secondary battery 103 can also be performed.

[0063] Furthermore, in an emergency, regenerative charging can be performed on the second secondary battery 102. Once the second secondary battery 102 becomes usable again, the second switch 132 is turned OFF, and only regenerative charging is performed on the third secondary battery 103.

[0064] Furthermore, in the event of an emergency, if the secondary battery 102 needs to be replaced with a new one, the first switch 131 is in the off state, allowing for replacement without the risk of electric shock. Conventionally, when the old secondary battery 102 is removed, power to the control unit is lost, causing stored information such as the control unit's memory to be reset and erased. However, in this embodiment, power can be supplied by turning the second switch 132 on, thus preventing data loss in memory due to power loss. After replacing the secondary battery 102 with a new one in an emergency, the device can be used normally by turning the first switch 131 on.

[0065] Although this embodiment uses an electric vehicle (EV) as an example, it is not limited to electric vehicles (EVs) and can also be applied to hybrid vehicles (HVs), plug-in hybrid vehicles (PHVs), or gasoline-powered vehicles.

[0066] (Embodiment 2) Figure 4 is a block diagram showing a schematic configuration of a hybrid vehicle (HV) as one embodiment.

[0067] While Embodiment 1 showed an example of an electric vehicle (EV), this embodiment shows an example of a hybrid vehicle (HV) having an internal combustion engine 106 below.

[0068] Since this embodiment is almost identical to Embodiment 1, except that it has an internal combustion engine 106 and the capacity of the first secondary battery 101 is smaller than that of an electric vehicle (EV), the same reference numerals are used for the same parts as in Figure 1.

[0069] In the case of a hybrid vehicle (HV), when the start switch 121 is turned ON, the power from the second secondary battery 102 is used to start the starter motor and operate the internal combustion engine 106. In addition, a hybrid vehicle (HV) can also be driven by using only the power from the first secondary battery 101 to power the motor 105 without using the internal combustion engine 106.

[0070] Even in the case of a hybrid vehicle (HV), if the second secondary battery 102 is unusable, the third secondary battery 103 can supply power to the starter motor and operate the internal combustion engine 106.

[0071] Furthermore, this technology is not limited to hybrid vehicles (HVs) but can also be applied to plug-in hybrid vehicles (PHVs). Plug-in hybrid vehicles (PHVs) differ from hybrid vehicles in that they support external charging.

[0072] Furthermore, this embodiment can also be applied to vehicles called mild hybrid vehicles. In mild hybrid vehicles, the capacity of the first secondary battery 101 in Figure 4 is small, and it has the same output voltage as the second secondary battery 102 (for example, 12V). Mild hybrid vehicles are configured to use the capacity of the first secondary battery 101 only to assist with driving, and the driving is mainly performed by the internal combustion engine.

[0073] In this embodiment, by setting the third secondary battery 103 to 48V, it is also possible to supply power to the motor, which acts as both a starter and a generator, at its output voltage without going through a DC / DC converter.

[0074] This embodiment shows an example of creating a 48V power supply using multiple cylindrical batteries suitable for manufacturing the third secondary battery 103 shown in Figure 1.

[0075] Figure 6 shows a photograph of the exterior of a cylindrical battery. This size of cylindrical battery is also called an 18650 battery.

[0076] An example of a cylindrical lithium-ion battery will be described with reference to Figure 7A. As shown in Figure 7A, the cylindrical lithium-ion battery 616 has a positive electrode cap (battery cover) 601 on the top surface and a battery casing (outer casing) 602 on the sides and bottom. The positive electrode cap 601 and the battery casing (outer casing) 602 are insulated from each other by a gasket (insulating packing) 610.

[0077] Figure 7B is a schematic diagram showing a cross-section of a cylindrical lithium-ion battery. The cylindrical lithium-ion battery shown in Figure 7B has a positive electrode cap (battery cover) 601 on the top surface and a battery casing (outer casing) 602 on the sides and bottom. The positive electrode cap and the battery casing (outer casing) 602 are insulated from each other by a gasket (insulating packing) 610.

[0078] Inside the hollow cylindrical battery can 602, a battery element is provided, in which a strip-shaped positive electrode 604 and a negative electrode 606 are wound with a separator 605 in between. Although not shown, the battery element is wound around a central axis. The battery can 602 is closed at one end and open at the other end. Inside the battery can 602, the battery element, in which the positive electrode, negative electrode, and separator are wound, is sandwiched between a pair of opposing insulating plates 608 and 609. Furthermore, the inside of the battery can 602 in which the battery element is provided is filled with an electrolyte (not shown).

[0079] Since the positive and negative electrodes used in cylindrical storage batteries are wound, it is preferable to form the active material on both sides of the current collector. Figures 7A and 7B illustrate a lithium-ion battery 616 in which the height of the cylinder is greater than the diameter of the cylinder, but the battery is not limited to this. A lithium-ion battery in which the diameter of the cylinder is greater than the height of the cylinder is also possible. With such a configuration, for example, it is possible to miniaturize the lithium-ion battery.

[0080] A positive electrode terminal (positive electrode current collector lead) 603 is connected to the positive electrode 604, and a negative electrode terminal (negative electrode current collector lead) 607 is connected to the negative electrode 606. Metal materials can be used for the positive electrode terminal 603 and the negative electrode terminal 607. The positive electrode terminal 603 is resistance-welded to the safety valve mechanism 613, and the negative electrode terminal 607 is resistance-welded to the bottom of the battery can 602. The safety valve mechanism 613 is electrically connected to the positive electrode cap 601 via a PTC element (Positive Temperature Coefficient) 611. The safety valve mechanism 613 disconnects the electrical connection between the positive electrode cap 601 and the positive electrode 604 when the rise in the internal pressure of the battery exceeds a predetermined threshold. The PTC element 611 is a thermosensitive resistance element whose resistance increases when the temperature rises, and it prevents abnormal heat generation by limiting the amount of current through the increase in resistance. PTC elements include barium titanate (BaTiO ３ ) ceramic materials and the like can be used.

[0081] Figure 7C shows a drawing relating to the dimensions of the cylindrical shape. In Figure 7C, the core outer diameter d, the winding outer diameter D, and the winding thickness T are shown. In this embodiment, the core outer diameter d was set to 4 mm.

[0082] In this embodiment, the current collector foil used for the positive electrode current collector is 20 μm thick aluminum foil, with a positive electrode active material layer on both sides for a total thickness of 86 μm, and an active material load of 10.5 mg / cm². ２ The device was prepared with an active material content of 8.4 g. Furthermore, a 10 μm thick copper foil was used as the negative electrode current collector foil, with negative electrode active material layers on both sides, for a total thickness of 133 μm.

[0083] A 25 μm thick porous polypropylene film was used as the separator.

[0084] The electrolyte is 1 mol / L lithium hexafluoride phosphate (LiPF) as the electrolyte. ６ The electrolyte used was a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of EC:DEC = 3:7.

[0085] Furthermore, the positive electrode active material used was obtained according to the manufacturing process disclosed in the example of international publication number WO2024 / 184744. When preparing the slurry, the positive electrode active material, binder, solvent, and conductive additive were mixed. Polyvinylidene fluoride (PVDF) was used as the binder, N-methyl-2-pyrrolidone (NMP) as the solvent, and acetylene black (AB) as the conductive additive. The weight ratio of the mixture was adjusted so that the ratio of positive electrode active material:AB:PVDF was 96:2:2. The slurry was coated onto aluminum foil. NMP was used as the solvent for the slurry. After coating the aluminum foil with the slurry, the solvent was evaporated.

[0086] Figure 8 shows the electrical characteristics of a single cylindrical secondary battery. Figure 8A shows the charge-discharge characteristics for the first cycle, which is the result of a charge-discharge cycle test, and Figure 8B shows the cycle characteristics up to the 200th cycle. The conditions for the charge-discharge cycle test of a single cylindrical secondary battery are described below. Coin cell A was placed in a constant temperature bath maintained at 25°C, and the following cycles were repeated 200 times under the charge-discharge conditions. No aging was performed before this test. The charging conditions for the charge-discharge cycle test were CCCV charging, 0.2C rate, 4.5V, and 0.02C cutoff. The discharge conditions for the charge-discharge cycle test were CC discharge, 0.2C rate, and 3.0V cutoff. After the completion of charging, a 60-minute rest period was provided before the next discharge. In the charging conditions of the charge-discharge cycle test, 4.5V is called the upper limit voltage, and the voltage is maintained at the upper limit voltage during the CV charging period. The 3.0V in the discharge conditions is called the lower limit voltage. The cumulative amount of discharge current that flowed during the first discharge cycle can be called the discharge capacity of the first cycle, and the cumulative amount of discharge current that flowed during the 50th discharge cycle can be called the discharge capacity of the 50th cycle. The discharge capacity retention rate (%) after n cycles was calculated as (discharge capacity after n cycles / maximum value of discharge capacity from cycle 1 to n) × 100. n is a natural number excluding zero, and in this embodiment, n = 70. The discharge capacity retention rate after 70 cycles was 95.95%. A higher discharge capacity retention rate at the end of 70 cycles is desirable as a battery characteristic because it suppresses the decrease in battery capacity after repeated charging and discharging.

[0087] The cylindrical secondary battery fabricated in this embodiment has an output voltage higher than 4V compared to commercially available secondary batteries (average voltage 3.6V). Therefore, by using the cylindrical secondary battery fabricated in this embodiment, a 48V power supply can be constructed with fewer batteries than commercially available secondary batteries.

[0088] Although the upper voltage limit exceeds 4V, the upper voltage limit should be set to 4V when in use. Since the state of charge (SOC) of a cylindrical secondary battery with an upper voltage limit of 4V is approximately 59%, setting the upper voltage limit to 4V allows for long-term storage and reduces self-discharge.

[0089] Twelve cylindrical secondary batteries, each with an upper voltage limit of 4V, can be connected in series to produce approximately 48V. By connecting at least 12 or more batteries in series or parallel and bundling them together into a cassette, the third secondary battery 103 shown in Figure 1 can be manufactured.

[0090] 101: Primary secondary battery, 102: Secondary secondary battery, 103: Tertiary secondary battery, 105: Motor, 106: Internal combustion engine, 107: Inverter, 108: Electrical components, 111: First DC-DC converter, 112: Second DC-DC converter, 113: Third DC-DC converter, 114: Fourth DC-DC converter, 120: Control unit, 121: Start switch, 122: SMR, 131: First switch, 132: Second switch, 520: Control unit

Claims

This is a control system for a vehicle that moves using the output of a drive motor. The aforementioned vehicle is A first power supply that supplies power to the drive motor via a first DC / DC converter, A control unit that controls the first power supply, A second power supply with an output voltage lower than the first power supply, A third power supply, the output voltage of which is between the output voltage of the first power supply and the output voltage of the second power supply, The control unit that controls the aforementioned power supply, The system includes a second DC / DC converter for stepping down the output of the third power supply, When the second power supply starts the drive motor, the power supply from the third power supply is stopped. A vehicle control system in which, when the third power supply starts the drive motor using the second DC / DC converter, the power supply from the second power supply is stopped. 　 A control system for a vehicle that runs on the output of an internal combustion engine or a drive motor. The aforementioned vehicle is A first power supply that supplies power to the drive motor via a first DC / DC converter, A second power source for starting the internal combustion engine, A third power supply different from the first and second power supplies, A connection part that allows the third power supply to be detachably attached to the interior of the vehicle, A control unit that controls the first power supply and the third power supply, The system includes a second DC / DC converter for stepping down the output of the third power supply, A vehicle control system in which, when the second power source starts the internal combustion engine, the third power source can be disconnected from the connection, and when the third power source starts the internal combustion engine using the second DC / DC converter, the power supply from the second power source is stopped. 　 The vehicle control system according to claim 1 or claim 2, wherein the control unit controls the charging of the third power supply at a SOC of 40% or more and 60% or less. 　 The vehicle control system according to claim 1 or claim 2, wherein the control unit controls the charging of the first power supply at a SOC of 0% or more and 100% or less. 　 A vehicle control system according to claim 1 or claim 2, wherein the second power source is a lead-acid battery and the output voltage of the second power source is 12V or more and 16V or less. 　 A vehicle control system according to claim 1 or claim 2, wherein the third power source is a lithium-ion secondary battery, and the output voltage of the third power source is 24V, 48V, 54V, or 60V. 　 A vehicle control system according to claim 1 or claim 2, wherein when the second power supply is abnormal, the power supply is switched from the second power supply to the third power supply by turning off a first switch provided between the second power supply and the control unit, and turning on a second switch provided between the third power supply and the control unit.

Images