CHARGING SYSTEM

The automobile controller notifies the controller of the power feed device (power supply controller) of the charging voltage prior to charging the battery. After receiving the charging voltage, the power feed controller raises the voltage at the output end of the power supply device to the supply voltage that is lower than its own rated output voltage and the charging voltage. The automobile controller monitors the voltage at the output end to identify the supply voltage while the power feed controller performs a ground fault check. The automobile controller (1) charges the battery with electric power of the supply voltage if the supply voltage is equal to the charge voltage, and (2) drives a boost converter to reduce the supply voltage to the charge voltage if the supply voltage is lower than the charge voltage, and then charge the battery with electric power from the power feed device.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2023-041714 filed on Mar. 16, 2023, incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The technology disclosed in this specification relates to a charging system including an automobile having a battery, and a power feed device for charging the battery. Battery vehicles are included.

2. Description of Related Art

Battery electric vehicles equipped with batteries are rapidly becoming commonplace. As battery electric vehicles become widespread, it is expected that power feed devices (charging stations) will also become widespread. In the future, in a plurality of battery electric vehicles connected to power feeding devices, there is a possibility that rated voltages of batteries installed in the battery electric vehicles will be different from each other. There is also a possibility that old type power feed devices will have a low power feed voltage, and new type power feed devices will have a high power supply voltage. Information needs to be exchanged between power feed devices and battery electric vehicles prior to charging, in order to match output voltage of the power feed devices to voltage that is acceptable to the battery electric vehicles receiving electric power. In general, adjusting variables for data communication (or variables related to electric power that is transmitted) prior to data communication (or transmission/reception of electric power) is called a handshake. A handshake is also performed between a power feed device and an automobile prior to charging (for example, Japanese Unexamined Patent Application Publication No. 2019-47677 (JP 2019-47677 A)).

SUMMARY

In a battery electric vehicle, when voltage (supply voltage) of electric power obtained from a power feed device is equal to a voltage suitable for charging a battery (charging voltage), the electric power sent from the power feed device can be directly sent to the battery. When the supply voltage is lower than the charging voltage, the battery electric vehicle must boost the voltage of the electric power sent from the power feed device before charging the battery. The battery electric vehicle needs to know the supply voltage of the power feed device prior to charging. The battery electric vehicle learns the power feed voltage through the handshake described above. The present specification provides technology for simplifying a handshake protocol between the battery electric vehicle and the power feed device prior to charging.

The present specification discloses a charging system including an automobile including a battery, and a power feed device for charging the battery.

The automobile notifies the power feed device of a voltage suitable for charging the battery (charging voltage), prior to charging the battery.

The power feed device, upon receiving the charging voltage, raises voltage at an output end (electric power output end) of the power feed device to a lower supply voltage of a rated output voltage of itself (greatest output voltage), and the charging voltage, and concurrently executes a leakage check of checking for presence or absence of leakage between a positive electrode and a negative electrode of the output end.

Such a leakage check is stipulated, for example, in the international standard (GB/T18487), relating to battery charging of battery electric vehicles, and so forth.

The power feed device starts power feed to the battery at the supply voltage when no leakage is detected by the leakage check.

The automobile monitors the voltage at the output end while the power feed device is executing the leakage check, to identify the supply voltage.

(1) The automobile charges the battery with electric power at the supply voltage when the supply voltage is equal to the charging voltage.

Alternatively, (2) the automobile raises the supply voltage to the charging voltage using a boost converter when the supply voltage is lower than the charging voltage, and charges the battery with electric power from the power feed device.

According to the technology disclosed in the present specification, the automobile monitors output end voltage of the power feed device when the power feed device performs the leakage check, and identifies the supply voltage. According to the technology disclosed in the present specification, the protocol in the handshake for the power feed device to notify the automobile of the supply voltage can be omitted.

Details of the technology disclosed in the present specification, and further modifications, will be described in the “DETAILED DESCRIPTION OF EMBODIMENTS” below.

DETAILED DESCRIPTION OF EMBODIMENTS

A charging system2of an embodiment will be described with reference to the drawings.FIG.1shows a block diagram of the charging system2. A charging system2of the embodiment includes a battery electric vehicle100and a power feed device200.

Battery103sends electric power to an inverter (not shown). The inverter converts the DC electric power of the battery103into drive power for the drive motor and sends it to the drive motor. The controller108determines the target output of the inverter (running motor) from the vehicle speed and accelerator operation amount, and controls the inverter so as to achieve the target output.

The battery103can be charged with electric power supplied from an external power feed device200. A boost converter110is connected between the battery103and the charging inlet107. Boost converter110includes reactor114, switching element115, and diodes116and117. One end of the reactor114is connected to the input end positive electrode111pand the other end is connected to the high potential side of the switching element115. A low potential side of the switching element115is connected to the ground line113. A ground line113connects the input end negative electrode111nand the output end negative electrode112n. A diode116is connected in antiparallel to the switching element115.

A diode117is connected between the other end of the reactor114and the output end positive electrode112p. The diode117allows current to flow from the input end positive electrode111pto the output end positive electrode112pand blocks current flow in the opposite direction. In other words, diode117is provided to prevent backflow of current.

Switching element115is controlled by controller108. When the controller108appropriately turns on and off the switching element115, the voltage input to the input terminal111is boosted and output from the output end112. A voltage sensor106is connected between the input end positive electrode111pand the input end negative electrode111n. A voltage sensor105is also connected between the output end positive electrode112pand the output end negative electrode112n. The measured values of voltage sensors105and106are sent to controller108. The controller108drives the switching element115so that the ratio of the measured values of the voltage sensors105and106(that is, the ratio of the voltage at the output end112to the voltage at the input terminal111) becomes the target step-up ratio.

A charging relay109is connected between the boost converter110and the charging inlet107. The charging relay109is also controlled by the controller108.

The power feed device200includes a DC power supply202, an earth leakage detector203, a voltage sensor204and a controller205. Controller205controls DC power supply202. The leakage detector203checks whether or not leakage occurs between the output end positive electrode201pand the output end negative electrode201nof the power feed device200. The positive output end201pand the negative output end201nare electric power output ends for outputting power for charging the battery103. Hereinafter, the output end positive electrode201pand the output end negative electrode201nmay be collectively referred to as the output end201.

The result of the leakage check is notified to the controller205. When the earth leakage detector203detects the earth leakage, the controller205immediately stops the DC power supply202. Controller205also monitors the voltage at output end201by voltage sensor204. The controller205monitors the measured value of the voltage sensor204to check whether the DC power supply202is outputting the desired voltage.

Power feed device200and battery electric vehicle100are connected by charging cable210. A connector213at the tip of charging cable210is connected to charging inlet107. Charging cable210includes electric power cable211that transmits electric power and communication cable212. An electric power cable211transmits electric power from the power feed device200(DC power supply202) to the battery electric vehicle100(battery103).

A communication cable212connects the controller108of the battery electric vehicle100and the controller205of the power feed device200. Communication cable212allows controller108of battery electric vehicle100and controller205of power feed device200to exchange information.

Battery electric vehicle100and power feed device200charge battery103while exchanging data via communication cable212.FIG.2shows a flow diagram of the charging process performed by controller108of battery electric vehicle100and controller205of power feed device200. Also depicted inFIG.2is the handshake protocol exchanged between controller108of battery electric vehicle100and controller205of power feed device200. InFIG.2, “SPx” (where “x” is a number) denotes processing performed by the controller205of the power feed device200, and “SVx” (where “x” is a number) denotes processing performed by the controller108of the battery electric vehicle100. InFIG.2. “Psignal-0x” (“x” is a number) means a signal (data) sent from the controller205to the controller108, and “Vsignal-0x” (“x” is a number) is a signal (data) that the controller108sends to the controller205.

For convenience of explanation, a voltage suitable for charging the battery103is called a charging voltage, and a voltage of electric power provided by the power feed device200is called a supply voltage.

Controller108of battery electric vehicle100does not activate boost converter110when the supply voltage is equal to the charging voltage. Input terminal positive terminal111pand output end positive terminal112pof boost converter110are connected via reactor114and diode117. If the switching element115is stopped, the reactor114and the diode117flow the electric power input to the input end positive electrode111pas it is to the output end positive electrode112p. That is, the electric power of the supply voltage is sent to the battery103as it is. The controller108charges the battery103with the electric power of the supply voltage when the supply voltage is equal to the charge voltage.

When the supply voltage is lower than the charging voltage, controller108drives boost converter110(switching element115) to boost the supply voltage to the charging voltage and charge battery103.

Controller108of battery electric vehicle100does not know the supply voltage provided by power feed device200before power feed device200is connected to charging inlet107. Prior to charging, controller108needs to know the supply voltage. On the other hand, controller205of electric power feed device200needs to know the voltage acceptable to battery electric vehicle100prior to supplying power. The processing ofFIG.2includes a protocol for the controllers108,205to input and output necessary information to each other.

The processing inFIG.2is started when power feed device200is connected to charging inlet107. First, the controller205of the power feed device200sends a signal Psignal-01 to the controller108of the battery electric vehicle100(SP1). The signal Psignal-01 is a handshake message from controller205to controller108and includes the protocol version of power feed device200.

Upon receiving signal Psignal-01, controller108sends signal Vsignal-01 to controller205(SV1). A signal Vsignal-01 is a handshake message from the controller108to the controller205and contains information on a voltage suitable for charging the battery103(charging voltage). That is, the controller108notifies the charging voltage to the controller205prior to charging the battery103.

Upon receiving the signal Vsignal-01, the controller205checks for electric leakage (SP2). The power feed device200performs an electric leakage check in the following procedure. The controller205raises the voltage of the output end201to the lower voltage (supply voltage) of its own rated output voltage and the charging voltage, and checks whether or not an electric leakage occurs between the output end positive electrode201pand the output end negative electrode201n. The rated output voltage of the power feed device200is equal to the maximum output voltage that the power feed device200can output.

As described above, the leakage detector203is connected between the output end positive electrode201pand the output end negative electrode201n. Leakage detector203checks the difference between the current flowing from output end positive electrode201pand the current returning to output end negative electrode201n, and determines that an electric leak has occurred if the current difference exceeds a predetermined allowable value.

If the electric leakage is detected, the controller205stops the charging process (SP3: YES). If no electric leakage is detected, controller205sends signal Psignal-02 to controller108(SP4). Signal Psignal-02 contains a message indicating that charging can be started.

Upon receiving the signal Psignal-02, the controller108closes the charging relay109(SV3) when the battery electric vehicle side is ready for charging, and sends the signal Vsignal-02 to the controller205(SV4). The signal Vsignal-02 contains a message indicating that the battery electric vehicle has finished preparations for charging.

The controller205that has received the signal Vsignal-02 sends Psignal-03 including a message to start electric power output to the controller108(SP5). Subsequently, the controller205starts outputting electric power of the supply voltage (SP6).

Upon receiving signal Psignal-03, controller108drives boost converter110if the supply voltage is lower than the charging voltage (SV5). The controller108has already identified the supply voltage in the process of SV2. The target boost ratio of boost converter110is determined by “charging voltage/supply voltage”. Controller108drives switching element115so that the target voltage ratio is achieved.

If the supply voltage is equal to the charging voltage, controller108will not activate boost converter110. The charging inlet107(power feed device200) and the battery103are directly connected, and the electric power of the supply voltage is sent to the battery103. That is, battery103is charged.

After that, the power feed device200continues to output the electric power of the supply voltage until the battery103reaches full charge. Since the processing after the battery103reaches full charge is the same as the conventional charging processing, the description is omitted.

As described above, in the processing ofFIG.2, the controller205of the power feed device200does not explicitly notify the controller108of the battery electric vehicle100of the supply voltage. Controller108can identify the supply voltage by monitoring the voltage at output end201during the leakage check performed by controller205. Pre-charging communication is simplified because no communication from controller205to controller108to explicitly inform the supply voltage is required.

The processing of the controller108and the controller205during charging is summarized as follows. The controller108of the battery electric vehicle100notifies the controller205of the power feed device200of the charging voltage prior to charging the battery103. The controller205that has received the charging voltage increases the voltage of the output end201to the supply voltage of the lower one of its own rated output voltage and the charging voltage, and checks whether there is a leakage between the output end positive electrode201pand the output end negative electrode201n. The controller205starts power feed to the battery103at the supply voltage if no leakage is detected by the leakage check. Controller108monitors the voltage at output end201to identify the supply voltage while controller205performs a ground fault check. The controller108then (1) charges the battery103with electric power at the supply voltage if the supply voltage is equal to the charge voltage. Alternatively, the controller108(2) drives the boost converter110to increase the supply voltage to the charging voltage when the supply voltage is lower than the charging voltage, and then charges the battery103with the electric power of the power feed device200.

The detailed procedure of the leakage check and the handshake protocol exchanged between the controller108and the controller205are defined in the international standard (GB/T18487) for battery charging of battery electric vehicles for reference.

To distinguish between controller108of battery electric vehicle100and controller205of power feed device200, controller108may be referred to as an automobile controller and controller205may be referred to as a power feed controller.

Although the specific examples have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and alternations of the specific example illustrated above. The technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the techniques illustrated in the present specification or drawings can achieve a plurality of objectives at the same time, and achieving one of the objectives itself has technical usefulness.