Vehicle-mounted charging device and vehicle-mounted charging system

Abstract

An on-board charging device and an on-board charging system according to the present invention comprise: a power converter connectable to an AC power supply outside a first vehicle, the power converter converting AC power input from the AC power supply into first DC power; the voltage converter is used for transforming an input direct-current voltage into a charging voltage of the first battery; a voltage conversion control unit that controls the voltage converter; and a DC input terminal connectable to a DC power source outside the first vehicle, the DC input terminal inputting a DC voltage of a second DC power input from the DC power source to the voltage converter, the voltage converter transforms the DC voltage of at least one of the first DC power and the second DC power into a charging voltage of the first battery in accordance with an instruction from the voltage conversion control unit.

Description

Technical Field

[0001] The invention relates to a vehicle-mounted charging device and a vehicle-mounted charging system. Background Art

[0002] As electric vehicles become more prevalent, there is an increasing possibility that the vehicle will become unable to drive due to a depleted battery. Therefore, as a method of charging vehicles outside power supply locations, wireless power supply on the road and battery charging between vehicles are considered as one of the power supply methods. This is a method of charging the vehicle battery by using an OBC (On Board Charger) installed in the vehicle and using the output conversion unit and voltage conversion unit of the OBC to convert the voltage input from other vehicles or external power sources. In such a charging method, a charging device that can charge stably is important. For example, Patent Document 1 discloses a structure of a charging device in which a power conversion unit controls the DC voltage, and during this period, the frequency of the voltage conversion unit is kept constant, thereby achieving stable charging.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2021-93788 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] Conventional inter-vehicle charging often involves short circuits when power is supplied and charged between batteries with different voltages, preventing charging from proceeding. The present invention addresses this issue and aims to provide an on-vehicle charging device and system that enable inter-vehicle charging from batteries with DC power supplies of different voltages.

[0008] Technical solutions to problems

[0009] A vehicle-mounted charging device and a vehicle-mounted charging system for charging a first battery mounted on a first vehicle, comprising: a power converter capable of being connected to an AC power source external to the first vehicle, which converts AC power input from the AC power source into a first DC power; a voltage converter that transforms the input DC voltage into a charging voltage for the first battery; a voltage conversion control unit that controls the voltage converter; and a DC input terminal capable of being connected to a DC power source external to the first vehicle, the DC input terminal inputting a DC voltage of a second DC power input from the DC power source to the voltage converter, and the voltage converter transforms the DC voltage of at least either the first DC power or the second DC power into a charging voltage for the first battery in accordance with instructions from the voltage conversion control unit.

[0010] Effects of the Invention

[0011] Provided is an on-vehicle charging device and an on-vehicle charging system that enable charging of batteries from DC power supplies of different voltages during inter-vehicle charging. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is an explanatory diagram of an in-vehicle charging device according to one embodiment of the present invention.

[0013] Figure 2 This is a circuit diagram of an in-vehicle charging device according to one embodiment of the present invention.

[0014] Figure 3 A first modification example is shown.

[0015] Figure 4 A second modified example is shown.

[0016] Figure 5 A third modified example is shown.

[0017] Figure 6 This is a flowchart of a control unit of an on-vehicle charging device according to one embodiment of the present invention. DETAILED DESCRIPTION

[0018] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following description and drawings are examples for illustrating the present invention and have been omitted or simplified as appropriate for clarity. The present invention may also be implemented in various other ways. Unless otherwise specified, each component may be single or multiple.

[0019] The positions, sizes, shapes, and ranges of the components shown in the drawings may not represent their actual positions, sizes, shapes, and ranges in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the positions, sizes, shapes, and ranges disclosed in the drawings.

[0020] (One embodiment and overall structure of the present invention)

[0021] ( Figure 1 )

[0022] As one embodiment of a vehicle employing the present invention, vehicle 1 includes a battery 1b and an on-vehicle charging device 10. The on-vehicle charging device 10 is, for example, a charging device that charges the vehicle 1 by connecting it to a charger 3 external to the vehicle 1. Furthermore, the on-vehicle charging device 10 is, for example, a charging device that connects the vehicle 1 to another vehicle 2 to enable bidirectional charging between the batteries mounted on the vehicles.

[0023] The on-vehicle charging device 10 includes a power converter 4 that is connected to an AC power source 3a of an AC charger 3 external to the vehicle 1 and converts AC power input from the AC power source 3a into DC power; a voltage converter 5 that converts the input DC voltage into a charging voltage for the battery 1b; and a voltage conversion control unit 7 that controls the voltage converter 5. The on-vehicle charging device 10 also includes a DC input terminal 1a that can be connected to a DC power source 2a external to the vehicle 1. The AC power source 3a is, for example, a commercial AC power source. The DC power source 2a outputs a variable or constant DC voltage.

[0024] The power converter 4 rectifies and smoothes the AC power using an EMC filter 4 a and improves the power factor and suppresses higher harmonics using a PFC (Power Factor Correction) module 4 b .

[0025] The following describes a system in which power converter 4 converts AC power input from AC power source 3a into DC power, which is defined as first DC power. The DC power input from DC input terminal 1a is defined as second DC power. DC input terminal 1a inputs the DC voltage of the second DC power input from DC power source 2a to voltage converter 5. Voltage converter 5 converts the DC voltage of at least one of the first and second DC powers into a charging voltage for first battery 1b, in accordance with instructions from voltage conversion control unit 7.

[0026] The voltage conversion control unit 7 obtains information about the charging voltage of the battery 1b. When the DC voltage of the second DC power input from the DC input terminal 1a to the voltage converter 5 is converted into an AC voltage by using the H-bridge converter 5a, the AC voltage obtained by the transformation is converted back into a DC voltage by using the H-bridge converter 5b, reflecting the control content of the transformation into the charging voltage of the battery 1b, thereby realizing the charging of the battery 1b.

[0027] The on-vehicle charging device 10 has such a configuration that, during normal charging, the battery 1b is charged with power from the commercial power source (AC power source 3a). Furthermore, during inter-vehicle charging, even if a DC voltage different from the voltage of the battery 1b is input, it can be converted to the charging voltage of the battery 1b by the voltage converter 5. Furthermore, the vehicle 1 may be connected to multiple other vehicles 2 and DC power sources 2a.

[0028] Furthermore, the onboard charging device 10 is configured to input DC power from the DC input terminal 1a to the HB circuit of the voltage converter 5 and to discharge DC power from the battery 1b to the DC power supply 2a. When bidirectionally charging is performed, the other vehicle 2 is equipped with a DC power supply 2a and an onboard charging device (not shown) having the same configuration as the host vehicle 1, thereby enabling the input and output of a second DC power between the host vehicle 1 and the other vehicle 2.

[0029] ( Figure 2 )

[0030] AC power supply 3a is composed of, for example, a grounded three-phase four-wire commercial AC power supply 108 and a common-mode choke coil 106. AC power supply 3a is connected to power converter 4 via choke coil 105. Voltage converter 5 is composed of, for example, a SiC-MOSFET (Silicon Carbide Metal-Oxide-Semiconductor Field-Effect Transistor) and includes an isolation transformer 100.

[0031] Vehicle 1 can be connected to an AC power source other than AC power source 3a for voltage conversion. For example, it can be connected to a single-line three-phase AC load 406 and charged via a voltage converter 5. AC load 406 includes, for example, multiple commercial AC power sources 108, which are connected to vehicle 1 via an onboard power outlet 405. AC power input from onboard power outlet 405 is converted to DC power by power converter 402 via common mode choke coil 106 and choke coil 408. The DC power converted from the AC power by power converter 402 is converted to a charging voltage for battery 1b by voltage converter 5 via capacitor 403 and choke coil 408.

[0032] DC input terminal 1a is connected to the wiring between power converter 4 and voltage converter 5. DC input terminal 1a is connected to a DC power supply (not shown). Thus, voltage converter 5 receives either the first DC power converted from AC power by power converter 4 or the second DC power input from DC input terminal 1a.

[0033] (First Modification)

[0034] ( Figure 3 )

[0035] The vehicle-mounted charger 10 includes a voltage detector 8 between the DC input terminal 1a and the voltage converter 5. The vehicle-mounted charger 10 also includes a voltage conversion control unit 7 that acquires information detected by the voltage detector 8 and information from the battery 1b and functions as a control unit for the voltage converter 5.

[0036] The voltage detection device 8 detects the DC voltage of the first DC power or the second DC power input to the voltage converter 5, and transmits information regarding the detected DC voltage to the voltage conversion control unit 7. Based on the difference between the DC voltage detected by the voltage detection device 8 and the charging voltage of the battery 1b, the voltage conversion control unit 7 controls at least one of the frequency and phase of the AC voltage converted in the process of converting the input DC voltage into the charging voltage of the first battery 1b in the voltage converter 5.

[0037] The frequency control in voltage converter 5 will be described in detail. For example, if the DC voltage (battery 2a of other vehicle 2) detected by voltage detection device 8 relative to the DC voltage input from DC power supply 2a is 800V, and the charging voltage of battery 1b is 400V, and the voltage systems are different, voltage converter 5 controls the resonant frequency of the AC voltage converted from the input 800V DC voltage to a higher frequency than the resonant frequency of the charging voltage of 400V. This allows battery 1b of the host vehicle 1 to be charged even if there is a voltage difference.

[0038] On the other hand, the voltage conversion control unit 7 controls the frequency of the DC voltage input from the DC power supply 2a so that the resonant frequency of the AC voltage obtained by converting the input 400 V DC voltage to the resonant frequency of the AC voltage used for conversion to the charging voltage of 400 V approaches the resonant frequency of the AC voltage used for conversion to the charging voltage of 400 V, for example, in the case where the DC voltage detected by the voltage detection device 8 is 400 V and the charging voltage of the battery 1b is of the same voltage system. This enables inter-vehicle charging.

[0039] Furthermore, a structure that controls inrush current and prevents malfunctions by, for example, providing an inrush prevention circuit between the DC input terminal 1a and the voltage detection device 8 can be added. This not only enables charging at different voltages but also stabilizes the charging state.

[0040] (Second Modification)

[0041] ( Figure 4 )

[0042] The vehicle 1 also includes a communication device 11 for transmitting and receiving information about the charging voltage of the battery 1b, in addition to the onboard charging device 10, with a second vehicle 2 separate from the vehicle 1. The communication device 11 transmits and receives information about the charging voltage of the battery 1b and information about the DC voltage that the voltage converter 5 can convert into the charging voltage of the first battery 1b. The charging voltage of the battery 1b is measured by a battery voltage sensor (not shown).

[0043] The communication device 11 obtains information about the battery's charging voltage from sensors and information about the transformed voltage of the voltage converter 5. Furthermore, the communication device 11 obtains information about the discharge voltage of the DC power supply 2a of the other vehicle 2 via a communication device (not shown) and a sensor (not shown) for measuring the voltage of the DC power supply 2a, both mounted in the other vehicle 2. In the vehicle 1, the information received from the other vehicle 2 is used by the onboard charging device 10 to control the voltage converter 5 so that the voltage can be transformed to the charging voltage of the battery 1b.

[0044] In this way, the communication devices of the host vehicle 1 and the other vehicle 2 can transmit and receive various information on the acquired voltages through bidirectional wireless communication. Then, the other vehicle 2 having a battery capable of discharging at a voltage close to the charging voltage of the battery 1b of the host vehicle 1 can be selected from among the multiple other vehicles 2, enabling inter-vehicle charging even when there is a voltage difference.

[0045] (Third Modification)

[0046] ( Figure 5 )

[0047] A fast charging input terminal 13 for connection to the DC input terminal 1a is provided between the first battery 1b and the voltage converter 5. Accordingly, the DC input terminal 1a is a fast charging input terminal capable of directly inputting the second DC power to the first battery 1b.

[0048] In addition, a relay circuit 6 is provided between the fast charging input terminal 13 and the DC input terminal 1a, and between the voltage converter 5 and the DC input terminal 1a. The relay circuit 6 includes a first switch 6a that connects or disconnects the DC input terminal 1a and the voltage converter 5, and a second switch 6b that connects or disconnects the DC input terminal 1a and the fast charging input terminal 13. When the DC voltage of the second DC power is the same as the charging voltage of the first battery 1b, the relay circuit 6 switches the first switch 6a and the second switch 6b. In addition, the DC input terminal 1a and the fast charging input terminal 12a are, for example, CHAdeMO (registered trademark) input terminals.

[0049] When the discharge voltage of the DC power supply 2a (battery) of another vehicle 2 is the same as the charge voltage of the battery 1b of the vehicle 1, the onboard charging device 10 determines that the voltage converter 5 is not required to convert the voltage. The relay circuit 6 then switches from the first switch 6a to the second switch 6b in accordance with the control unit's instructions, allowing power to be supplied directly from the DC input terminal 1a to the battery 1b. This allows the relay circuit 6 to be switched according to the type of external power supply connected, thereby shortening charging time. The means for identifying the discharge voltage of the DC power supply 2a to instruct the switching of the relay circuit 6 is not limited; for example, the aforementioned communication device 11 may also be used.

[0050] ( Figure 6 )

[0051] In step S1, the voltage conversion control unit 7 detects the input DC voltage using the voltage detection device 8. In step S2, the control unit determines whether the detected DC voltage is a 400V system. If so, the control unit proceeds to step S3; otherwise, the control unit proceeds to step S6. In step S3, the control unit determines whether the vehicle 1 is a 400V system. If so, the control unit proceeds to step S4; otherwise, the control unit proceeds to step S5.

[0052] In step S4, since the input voltage is the same as the voltage system of the vehicle 1 (the input voltage and the vehicle 1 are both 400V systems), the resonant frequency Fsw of the AC voltage converted in the process of transforming the input DC voltage by the voltage converter 5 is close to the resonant frequency Fr used for converting the charging voltage of the battery 1b.

[0053] In step S5, because the input voltage is different from the voltage system of the vehicle 1, and it can be determined that the voltage system of the vehicle 1 is higher than the voltage system of the input voltage (the input voltage is a 400V system, and the vehicle 1 is an 800V system), the resonant frequency Fsw of the AC voltage converted in the process of transforming the input DC voltage by the voltage converter 5 is maintained lower than the resonant frequency Fr used to convert it into the charging voltage of the battery 1b.

[0054] In step S6, it is determined whether the vehicle 1 is a 400V system. If so, the process proceeds to step S7; if not, the process proceeds to step S8. In step S7, because the input voltage is different from the voltage system of the vehicle 1 and it can be determined that the voltage system of the input voltage is higher than the voltage system of the vehicle 1 (the input voltage is an 800V system, while the vehicle 1 is a 400V system), the resonant frequency Fsw of the AC voltage converted by the voltage converter 5 during the transformation of the input DC voltage is maintained higher than the resonant frequency Fr used for conversion to the charging voltage of the battery 1b.

[0055] In step S8, since the input voltage is the same as the voltage system of the vehicle 1 (the input voltage and the vehicle 1 are both 800V systems), the resonant frequency Fsw of the AC voltage converted in the process of transforming the input DC voltage by the voltage converter 5 is close to the resonant frequency Fr used for converting into the charging voltage of the battery 1b.

[0056] According to one embodiment of the present invention described above, the following effects can be achieved.

[0057] (1) An on-vehicle charging device 10 for charging a first battery 1b mounted on a first vehicle 1 includes: a power converter 4 connectable to an external AC power source 3a of the first vehicle 1, which converts AC power input from the AC power source 3a into a first DC power; a voltage converter 5 that converts the input DC voltage into a charging voltage for the first battery 1b; a voltage conversion control unit 7 that controls the voltage converter 5; and a DC input terminal 1a connected to an external DC power source 2a of the first vehicle 1. The DC input terminal 1a inputs a DC voltage of a second DC power input from the DC power source 2a to the voltage converter 5, and the voltage converter 5 converts the DC voltage of at least one of the first DC power and the second DC power into a charging voltage for the first battery 1b according to an instruction of the voltage conversion control unit 7. In this way, an on-vehicle charging device 10 can be provided that converts the discharge voltage of another vehicle into the charging voltage of the vehicle itself during inter-vehicle charging to achieve charging.

[0058] (2) A voltage detection device 8 is provided for detecting the DC voltage of either the first DC power or the second DC power input to the voltage converter 5. The voltage conversion control unit 7 controls at least one of the frequency and phase of the AC voltage converted from the DC voltage to the charging voltage of the first battery 1b in the voltage converter 5 based on the value of the DC voltage detected by the voltage detection device 8 and the charging voltage of the first battery 1b. In this way, the voltage converter 5 can be controlled in accordance with the difference between the voltage of the DC power source 2a (battery) of the other vehicle 2 and the charging voltage of the battery 1b of the host vehicle 1.

[0059] (3) The first vehicle 1 includes a communication device 11 for transmitting and receiving information about the first battery b1 between the first vehicle 1 and a second vehicle 2 that is different from the first vehicle 1 and is equipped with a second battery 2a. The onboard charging device 10 transmits and receives information about the charging voltage of the first battery and information about the DC voltage that the voltage converter 5 can convert to the charging voltage of the first battery via the communication device 11. In this way, a vehicle equipped with a battery 2a having a discharge voltage close to the charging voltage of the battery 1b can be selected from a plurality of other vehicles 2 for charging.

[0060] (4) The DC input terminal 1a is a terminal for directly inputting the second DC power to the first battery 1b, and a fast charging input terminal 13 for connecting to the DC input terminal 1a is provided between the first battery 1b and the voltage converter 5. A relay circuit 6 is provided between the fast charging input terminal 13 and the DC input terminal 1a, and between the voltage converter 5 and the DC input terminal 1a, and includes a first switch 6a for connecting or disconnecting the DC input terminal 1a and the voltage converter 5, and a second switch 6b for connecting or disconnecting the DC input terminal 1a and the fast charging input terminal 13. When the DC voltage of the second DC power is the same as the charging voltage of the first battery 1b, the relay circuit 6 switches the first switch 6a and the second switch 6b in such a manner that the DC input terminal 1a is disconnected from the voltage converter 5 and the DC input terminal 1a is connected to the fast charging input terminal 13. In this way, the relay circuit 6 can be switched according to the type of external power supply connected to the vehicle 1.

[0061] (5) The DC input terminal 1a can be connected to a plurality of second vehicles 2 that are different from the first vehicle 1 and have second batteries 2a installed, respectively, so that the second DC power can be input and output between the first vehicle 1 and the plurality of second vehicles 2. In this way, power can be supplied to the host vehicle 1 from two or more vehicles, and conversely, power can be supplied from the host vehicle 1 to a plurality of other vehicles 2.

[0062] (6) An on-vehicle charging system including the above-mentioned on-vehicle charging device 10 and the first battery 1 b is employed. In this way, the discharge voltage of the other vehicle 2 can be converted into the charging voltage of the own vehicle 1 during inter-vehicle charging.

[0063] In addition, the present invention is not limited to the above-mentioned embodiment, and various modifications and combinations of other structures are possible within the scope of the present invention. In addition, the present invention is not limited to having all the structures described in the above-mentioned embodiment, and also includes deleting part of the structure.

[0064] Description of Reference Numerals

[0065] 1 vehicle

[0066] 1a DC input terminal

[0067] 1b Battery

[0068] 2 Other vehicles

[0069] 2A DC power supply

[0070] 3 AC charger

[0071] 3a AC power supply

[0072] 4 Power Converters

[0073] 4a EMC filter

[0074] 4b PFC module

[0075] 5 Voltage Converter

[0076] 6 Relay circuit

[0077] 6a First switch

[0078] 6b Second switch

[0079] 7 Voltage conversion control unit

[0080] 8 Voltage detection device

[0081] 10. On-board charging device

[0082] 11 Control device

[0083] 13 Fast charging input terminal

[0084] 100 Isolation transformer

[0085] 105 choke coil (primary side switching circuit)

[0086] 106 Common Mode Choke Coil

[0087] 108 Commercial AC Power Supply

[0088] 206 choke coil (secondary side switching circuit)

[0089] 402 voltage converter (tertiary side switching circuit)

[0090] 403 capacitor

[0091] 405 Car power socket

[0092] 406 AC load

[0093] 408 Choke Coil.

Claims

1. A vehicle-mounted charging device for charging a first battery mounted on a first vehicle, characterized in that: include: a power converter connectable to an AC power source external to the first vehicle, configured to convert AC power input from the AC power source into a first DC power; a voltage converter for converting an input DC voltage into a charging voltage for the first battery; a voltage conversion control unit for controlling the voltage converter; and a DC input terminal connectable to a DC power source external to the first vehicle, The DC input terminal inputs a DC voltage of the second DC power input from the DC power supply to the voltage converter. The voltage converter converts the DC voltage of at least one of the first DC power and the second DC power into a charging voltage for the first battery according to an instruction of the voltage conversion control unit.

2. The vehicle-mounted charging device according to claim 1, wherein: A voltage detection device is provided for detecting the DC voltage of either the first DC power or the second DC power input to the voltage converter. The voltage conversion control unit controls at least either the frequency or the phase of the AC voltage converted from the DC voltage to the charging voltage of the first battery in the voltage converter based on the DC voltage detected by the voltage detection device and the charging voltage of the first battery.

3. The vehicle-mounted charging device according to claim 1, wherein: The first vehicle includes a communication device that transmits and receives information about the first battery between the first vehicle and a second vehicle that is different from the first vehicle and has a second battery installed thereon. Information on the charging voltage of the first battery and information on the DC voltage that can be converted by the voltage converter into the charging voltage of the first battery are transmitted and received with the second vehicle via the communication device.

4. The vehicle-mounted charging device according to claim 1, wherein: The DC input terminal is a terminal for directly inputting the second DC power into the first battery. A fast charging input terminal for connecting to the DC input terminal is provided between the first battery and the voltage converter. A relay circuit is provided between the fast charging input terminal and the DC input terminal, and between the voltage converter and the DC input terminal. The relay circuit includes a first switch for connecting or disconnecting the DC input terminal and the voltage converter, and a second switch for connecting or disconnecting the DC input terminal and the fast charging input terminal. The relay circuit switches the first switch and the second switch in a manner that disconnects the DC input terminal from the voltage converter and connects the DC input terminal to the fast charging input terminal when the DC voltage of the second DC power is the same as the charging voltage of the first battery.

5. The vehicle-mounted charging device according to claim 1, wherein: The DC input terminal is connectable to a plurality of second vehicles that are different from the first vehicle and have second batteries installed thereon, respectively, and inputs and outputs the second DC power between the first vehicle and the plurality of second vehicles.

6. A vehicle-mounted charging system, characterized in that: The vehicle-mounted charging device comprises the vehicle-mounted charging device according to any one of claims 1 to 5 and the first battery.

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