JP7491781B2 - Charging connection cable and DC power supply method - Google Patents

Description

The present invention relates to a charging connection cable and a DC power supply method that can charge a battery in a power storage system such as a home from a vehicle battery in an electric vehicle or other vehicle with a simple configuration and reduce power conversion loss.

In recent years, electric vehicles such as plug-in hybrid vehicles (PHVs) and battery electric vehicles (BEVs) are becoming more common. When charging these electric vehicles, a commercial AC power source is supplied to the electric vehicle, and the AC is converted to DC inside the electric vehicle to charge the battery. Also, when discharging the electric vehicle, the DC power stored in the battery can be converted back to AC power and supplied to the house.

Patent document 1 discloses a system that can charge a residential storage battery with DC power discharged from an electric vehicle battery.

JP 2015-8626 A

However, the system described in Patent Document 1 requires a DC/DC converter to convert the voltage of the electric vehicle battery to the voltage of the home battery, resulting in power conversion loss.

Generally, when trying to charge a home battery from an electric vehicle, a power converter compatible with V2L (Vehicle to Load) or V2H (Vehicle to Home) is required. This power converter is a DC/AC inverter that converts the voltage of the electric vehicle's battery into AC. When charging a home battery, an AC/DC converter that further converts AC to DC must be installed downstream of this power converter, which generates a large power conversion loss.

The present invention has been made to solve the above problems, and aims to provide a charging connection cable and a DC power supply method that can charge a battery in a power storage system such as a home from a vehicle battery in an electric vehicle or other vehicle with a simple configuration and reduce power conversion loss.

In order to solve the above problems and achieve the object, the present invention provides a charging connection cable for connecting a vehicle battery of a vehicle having a generator, a vehicle battery, and a charging control unit that controls charging of the vehicle battery to a battery in an energy storage system and charging the battery from the vehicle side, the charging connection cable being characterized in that it is provided with a switch unit having a switch that opens and closes the connection of a positive side electric wire connecting plugs at both ends of the charging connection cable, a vehicle side voltage sensor that detects the system voltage on the vehicle battery side of the switch, a charging side voltage sensor that detects the voltage on the battery side of the switch, and a switch control unit that opens the switch as an initial state and closes the switch when the difference voltage between the system voltage detected by the vehicle side voltage sensor and the voltage detected by the charging side voltage sensor is within a predetermined range after the charging connection cable is connected.

The present invention is also characterized in that, in the above invention, the switch unit is provided on one plug of the charging connection cable.

The present invention also provides a DC power supply method for connecting a vehicle battery of a vehicle having a generator, a vehicle battery, and a charging control unit that controls charging of the vehicle battery to a battery in a power storage system, and charging the battery from the vehicle side, the method comprising the steps of: providing a switch for opening and closing a connection of a positive wire connecting plugs at both ends of a charging connection cable that connects the vehicle battery to the battery; opening the switch as an initial state; and closing the switch to start supplying power to the battery when the voltage difference between the system voltage on the vehicle side of the switch and the voltage on the battery side of the switch is within a predetermined range after the charging connection cable is connected.

The present invention makes it possible to charge a battery in a power storage system such as a home from a vehicle battery in an electric vehicle using a simple configuration, and also reduces power conversion losses.

FIG. 1 is a diagram showing a schematic diagram of a system configuration to which a charging connection cable according to the present embodiment is applied. FIG. 2 is a flowchart showing a switch control process performed by the switch control unit. FIG. 3 is a flowchart showing a charging control process performed by the charging control unit. FIG. 4 is an explanatory diagram for explaining the vehicle battery and the charging state of the battery after the switch is turned on. FIG. 5 is a diagram showing the configuration of a modified charging connection cable in which a switch unit is connected to a plug.

The charging connection cable and DC power supply method according to this embodiment will be described below with reference to the attached drawings.

<Overview of the Structure>
Fig. 1 is a diagram showing a schematic diagram of a system configuration to which a charging connection cable 1 according to the present embodiment is applied. As shown in Fig. 1, the charging connection cable 1 connects between a vehicle battery 14 of a vehicle 10 such as an electric vehicle and a battery 24 in an electricity storage system 20 of a house 100, and is used to charge the battery 24 from the vehicle 10 side.

The vehicle 10 has a charging function 11 and controls charging of the vehicle battery 14. The vehicle battery 14 is a high-voltage battery, for example, with a rated voltage of 200V. The charging function 11 has a charging control unit 12 and a generator 13. The generator 13 is an engine-driven or fuel cell, and power generation is controlled by the charging control unit 12. The charging control unit 12 uses the voltage or SOC (State of Charge) of the vehicle battery 14. When using the voltage, the charging control unit 12 drives the generator to charge when the voltage becomes equal to or lower than the lower discharge voltage, and stops charging when the voltage becomes equal to or higher than the upper charge voltage. The SOC (%) is an index indicating the charging state, and is expressed, for example, as remaining capacity [Ah] ÷ full charge capacity [Ah] × 100. The method of calculating or estimating the SOC is not particularly limited, but the SOC is calculated or estimated based on, for example, at least one of the measurement results of the voltage of the vehicle battery 14, the I-V characteristic data of the voltage of the vehicle battery 14, and the integrated value of the current value of the vehicle battery 14. The SOC may be a value converted into a value under a predetermined temperature condition using any conversion formula or the like.

The power storage system 20 has a battery 24 and is used as a commercial power source in the home by a power converter 21 acting as a DC/AC inverter. The battery 24 has a rated voltage of, for example, 200V. The power converter 21 converts the DC voltage of the battery 24 into an AC voltage of 100V.

The charging connection cable 1 has a switch unit 3 provided on the cable 2. Plugs P1 and P2 are provided on both ends of the cable 2. The plug P1 is detachably connected to a receptacle R1 on the vehicle side, and the plug P2 is detachably connected to a receptacle R2 on the power storage system 20 side.

The switch unit 3 has a switch SW, a vehicle-side voltage sensor 4, a charging-side voltage sensor 5, and a switch control unit 6. The switch SW is a switch that opens and closes the connection of the positive wire of the cable 2. The vehicle-side voltage sensor 4 detects the system voltage V1 on the vehicle battery 14 side of the switch SW. The charging-side voltage sensor 5 detects the voltage V2 on the battery 24 side of the switch SW. The switch control unit 6 opens the switch SW as the initial state, and after the charging connection cable 1 is connected, if the difference voltage between the system voltage V1 detected by the vehicle-side voltage sensor 4 and the voltage V2 detected by the charging-side voltage sensor 5 is within a predetermined range, it closes the switch SW to allow charging of the battery 24 to begin.

That is, the switch control unit 6 turns on the switch SW only when the system voltage V1 and voltage V2 are almost the same, and maintains this on state to maintain a state that allows charging of the battery 24 from the vehicle 10 side. When the switch SW is on, the vehicle battery 14 and the battery 24 are connected in parallel from the perspective of the charging function 11, and the charging function 11 performs charging control on the vehicle battery 14 and the battery 24 as a single battery, resulting in charging of the battery 24. Note that when the system voltage V1 and voltage V2 are not almost the same, the switch SW is off, and neither charging nor discharging occurs between the vehicle 10 side and the battery 24.

The switch control unit 6 may be realized by software, but may also be realized by a circuit (hardware).

<Switch control process>
Fig. 2 is a flowchart showing a switch control process performed by the switch control unit 6. As shown in Fig. 2, the switch control unit 6 first sets the switch SW in an OFF state (step S110). This OFF state of the switch SW can be achieved by turning off the switch SW when the power supply to the switch control unit 6 is turned off.

Then, the switch control unit 6 judges whether the differential voltage ΔV between the system voltage V1 and the voltage V2 is within a predetermined range ΔVa (step S120). This differential voltage ΔV is the absolute value of the difference between the system voltage V1 and the voltage V2. If the differential voltage ΔV is not within the predetermined range ΔVa (step S120: No), this judgment process is repeated.

On the other hand, if the voltage difference ΔV is within the predetermined range ΔVa (step S120: Yes), the switch SW is turned on (step S130), charging of the battery 24 is permitted, and this process is terminated.

<Charging control process>
3 is a flowchart showing a charging control process procedure by the charging control unit 12. The charging control unit 12 performs charging control based on the voltage (system voltage V1) or SOC of the vehicle battery 14, but for convenience of explanation, a case where charging control is performed based on the system voltage V1 of the vehicle battery 14 will be described here. As shown in FIG. 3, the charging control unit 12 determines whether the system voltage V1 is equal to or lower than the lower limit voltage of discharge (step S210). If the system voltage V1 is not equal to or lower than the lower limit voltage of discharge (step S210: No), this process ends.

On the other hand, if the system voltage V1 is equal to or lower than the lower discharge voltage limit (step S210: Yes), charging by the generator 13 is turned on to start charging (step S220). After that, the charging control unit 12 determines whether the system voltage V1 is equal to or higher than the upper charge voltage limit (step S230). If the system voltage V1 is not equal to or higher than the upper charge voltage limit (step S230: No), the process proceeds to step S220 and charging continues.

If the system voltage V1 is equal to or higher than the upper charging voltage limit (step S230: Yes), the charging control unit 12 turns off and stops charging, and ends this process. Note that the above process is repeated at predetermined time intervals.

The charging control by the charging control unit 12 is performed as a process on the vehicle 10 side, regardless of the state of the switch SW.

In this embodiment, as shown in FIG. 4(a), when the system voltage V1 of the vehicle battery 14 and the voltage V2 of the battery 24 are almost the same, the switch SW is turned on, the vehicle battery 14 and the battery 24 are connected in parallel, and charging of the battery 24 is permitted. Then, as shown in FIG. 4(b), the charging function 11 charges the vehicle battery 14 and the battery 24 equally, and as a result, the external battery 24 is charged. Then, the charging control unit 12 stops charging when the system voltage V1 becomes the charging upper limit voltage V1a. Here, the battery 24 is charged in the same way as the vehicle battery 14, so the voltage V2a when charging is stopped is the same as the charging upper limit voltage V1a.

In this embodiment, with a simple configuration in which only a switch unit 3 is provided on the charging connection cable 1, charging can be performed from the vehicle battery 14 of a vehicle 10 such as an electric vehicle to the battery 24 in the power storage system 20 of a house 100, and since a power converter is not required, power conversion loss can be reduced. Furthermore, since the vehicle battery 14 and the battery 24 are connected when the system voltage V1 and the voltage V2 are approximately equal, no large current flows due to the voltage difference, and the cable connection can be performed safely.

<Modification>
In the above embodiment, the position of the switch unit 3 on the cable 2 was arbitrary, but in this modified example 2, the switch unit 3 is provided by being connected to either the plug P1 or the plug P2. In Fig. 5, the switch unit 3 is provided by being connected to the plug P2.

This allows the switch unit 3 to be integrated with the plug P2, improving the robustness of the switch unit 3.

Note that the configurations illustrated in the above embodiments and variations are merely functional schematics, and do not necessarily have to be physically configured as illustrated. In other words, the form of distribution and integration of each device is not limited to that illustrated, and all or part of the devices can be functionally or physically distributed and integrated in any unit depending on various loads, usage conditions, etc.

The charging connection cable and DC power supply method of the present invention are useful for charging a battery in a power storage system such as a home from a vehicle battery in an electric vehicle or other vehicle with a simple configuration and for reducing power conversion loss.

REFERENCE SIGNS LIST 1 Charging connection cable 2 Cable 3 Switch unit 4 Vehicle-side voltage sensor 5 Charging-side voltage sensor 6 Switch control unit 10 Vehicle 11 Charging function 12 Charging control unit 13 Generator 14 Vehicle battery 20 Energy storage system 21 Power converter 24 Battery 100 House P1, P2 Plug R1, R2 Receptacle SW Switch V1 System voltage V2 Voltage ΔV Voltage difference ΔVa Predetermined range

Claims (3)

A charging connection cable for connecting a vehicle battery of a vehicle having a generator, a vehicle battery, and a charging control unit that controls charging of the vehicle battery to a battery in a power storage system, and for charging the battery from the vehicle side,
a switch for opening and closing a connection of a positive side electric wire that connects between plugs at both ends of the charging connection cable;
a vehicle-side voltage sensor for detecting a system voltage on the vehicle battery side of the switch;
a charge-side voltage sensor for detecting a voltage on the battery side of the switch;
a switch control unit that opens the switch in an initial state, and closes the switch when a differential voltage between the system voltage detected by the vehicle-side voltage sensor and the voltage detected by the charging-side voltage sensor is within a predetermined range after the charging connection cable is connected. The charging connection cable according to claim 1, characterized in that the switch unit is provided on one plug of the charging connection cable. A DC power supply method for connecting a vehicle battery of a vehicle having a generator, a vehicle battery, and a charge control unit that controls charging of the vehicle battery to a battery in a power storage system, and charging the battery from the vehicle side, comprising:
a switch for opening and closing a connection of a positive electric wire connecting plugs at both ends of a charging connection cable that connects the vehicle battery and the battery;
a DC power supply method comprising: opening the switch as an initial state; and, after the charging connection cable is connected, when a differential voltage between a system voltage on the vehicle side of the switch and a voltage on the battery side of the switch is within a predetermined range, closing the switch to start supplying power to the battery.

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