JP7635683B2 - Charging Control System - Google Patents

Description

The present invention relates to a charging control system.

The charging time of a secondary battery mounted on an electric vehicle (EV) or a plug-in hybrid electric vehicle (PHEV) is shortened as the amount of current passing therethrough increases.
However, there is a limit to the current carrying capacity of a single vehicle-mounted charger, which is one of the reasons why it is not possible to shorten the charging time for an in-vehicle secondary battery.
To solve this problem, for example, Patent Document 1 discloses a technique for charging an on-board secondary battery by using a plurality of on-board chargers connected in parallel.

JP 2018-201328 A

The leakage current during vehicle charging must be controlled below a specified value. For this reason, charging systems for vehicles such as EVs and PHEVs have a function that stops charging if a leakage current above a specified value is detected.

When multiple chargers connected in parallel are installed on a vehicle, as in the technology described in Patent Document 1, the leakage current increases when the vehicle is being charged, making it easier to detect leakage currents above a specified value. As a result, when multiple chargers connected in parallel are installed on a vehicle, there is an issue that vehicle charging frequently stops.

The present invention has been made to solve these problems, and aims to provide a charging control system that can reduce the frequency of charging stops for a vehicle equipped with multiple chargers connected in parallel.

A charging control system according to one aspect of the present invention includes:
A vehicle having a secondary battery and a plurality of chargers for charging the secondary battery;
a charging control device that detects leakage current during charging of the vehicle,
When the charging control device detects a leakage current exceeding a first threshold, the vehicle stops charging by some of the chargers;
When the charging control device detects a leakage current exceeding a second threshold, the charging control system stops charging of the vehicle by all of the chargers.

With this configuration, even if the leakage current value during vehicle charging exceeds a specified value, charging can be continued if the leakage current value can be suppressed to below the specified value by stopping charging using some chargers. As a result, the frequency of vehicle charging stops can be reduced.

The present invention provides a charging control system that can reduce the frequency of charging stops for a vehicle equipped with multiple chargers connected in parallel.

1 is a block diagram showing a configuration of a charging control system 1001 according to a first embodiment. FIG. 11 is a circuit diagram for explaining the role of a PP terminal. 10 is a circuit diagram for explaining a mechanism by which a charger 13 generates a leakage current. FIG. 2 is a circuit diagram showing a charger 13 connected in parallel. FIG. 2 is a block diagram for illustrating a configuration of an external charging control device 23. 4 is a flowchart showing an operation of the charge control system according to the first embodiment.

(First embodiment)
<Charging control system configuration>
Hereinafter, a charging control system according to the present embodiment will be described in detail with reference to the drawings. Fig. 1 is a block diagram showing a configuration of a charging control system 1001 according to a first embodiment. The charging control system according to the present embodiment includes a vehicle 1 and an external charging facility 2.

The vehicle 1 is a vehicle equipped with a secondary battery that is charged by an external power supply, and is typically an EV or a PHEV.
The vehicle 1 includes an inlet 11 , first and second charger connection relays 12 a and 12 b , first and second chargers 13 a and 13 b , a secondary battery 14 , and a vehicle charging control unit 15 .
In the following description, the first and second charger connection relays 12a and 12b will be simply referred to as the charger connection relays 12 unless there is a need to distinguish between them.
Moreover, the first and second chargers 13a and 13b will be simply referred to as charger 13 unless there is a particular need to distinguish between them.

In this embodiment, for simplicity, the vehicle 1 is equipped with two charger connection relays 12 and two chargers 13, but the number of charger connection relays 12 and chargers 13 is not limited to two and may be three or more.

The inlet 11 is a connection point between the vehicle 1 and the external charging equipment 2, which will be described later. Specifically, the vehicle 1 and the external charging equipment 2 are connected by inserting the inlet plug 22 of the external charging equipment 2 into the inlet 11. The vehicle 1 is supplied with power from the external charging equipment 2 via the inlet 11, and charges the secondary battery 14. The vehicle 1 also receives signals related to charging control, such as a CPLT (Control Pilot) signal, from the external charging equipment 2 via the inlet 11.

The inlet 11 according to this embodiment may be compliant with, for example, the US charger standard "SAE J1772 (SAE Electric Vehicle Conductive Charge Coupler)". In this case, the inlet 11 includes a grounded terminal (hereinafter referred to as the L terminal), a grounded terminal (hereinafter referred to as the N terminal), a protective ground terminal (hereinafter referred to as the PE terminal), a CP (Control Pilot) terminal, and a PP (Proximity Pilot) terminal (not shown).

The L terminal, N terminal, and PE terminal are connected to the charger 13 via the charger connection relay 12. The L terminal and N terminal output the power supplied from the external charging equipment 2 to the charger 13. The PE terminal is also connected to earth, and allows leakage current generated by the charger 13 to escape to the ground.

The CP terminal outputs the CPLT signal received from the external charging equipment 2 to the vehicle charging control unit 15. However, the CPLT signal is a signal exchanged between the vehicle 1 and the external charging equipment 2 to control the charging of the vehicle 1.

2 is a circuit diagram for explaining the role of the PP terminal. Note that in FIG. 2, some components of the vehicle 1 and the external charging equipment 2 are omitted as appropriate.
The vehicle 1 includes a circuit including a PP terminal, a vehicle charging control unit 15, and a resistor Ra, and the vehicle charging control unit 15 oscillates a PISW signal. The PISW signal is oscillated from the vehicle charging control unit 15, passes through the resistor Ra and the PP terminal, and returns to the vehicle charging control unit 15 again.
Here, the PP terminal is connected to a variable resistor Rc that is provided in the external charging equipment 2 and is connected to earth. When the PP terminal is connected to the variable resistor Rc that is connected to earth, the potential of the PISW signal changes depending on the resistance value of the variable resistor Rc. The change in the potential of the PISW signal allows the vehicle charging control unit 15 to recognize the connection to the external charging equipment 2.
Furthermore, the changed potential of the PISW signal includes information on the magnitude of the rated current that the external charging equipment 2 passes through the vehicle 1. In other words, the changed potential of the PISW signal includes information on the maximum value of the current that the external charging equipment 2 can pass through the vehicle 1.
In other words, the PP terminal obtains connection information with the external charging equipment 2 and information indicating the magnitude of the rated current from the resistance value of the variable resistor Rc, and outputs this information to the vehicle charging control unit 15.

Returning to the explanation of FIG.
The charger connection relay 12 is a relay that connects the inlet 11 and the charger 13. More specifically, the charger connection relay 12 is a relay that connects and disconnects the L terminal, the N terminal, and the PE terminal of the inlet 11 to and from the charger 13 based on control by the vehicle charging control unit 15. When the inlet 11 and the charger 13 are connected by the charger connection relay 12, charging of the vehicle 1 is performed, and when the inlet 11 and the charger 13 are disconnected, charging of the vehicle 1 is stopped.

The charger 13 is a device for converting the current passed from the external charging equipment 2 into an appropriate current and supplying it to the secondary battery 14. More specifically, the charger 13 is internally provided with, for example, a converter, a power factor correction circuit, a power conversion circuit, and the like, and these circuits convert the current passed from the external charging equipment 2 into a current appropriate for charging the secondary battery 14.
Furthermore, the charger 13 generates a leakage current when converting the current.

Fig. 3 is a circuit diagram for explaining a mechanism by which leakage current occurs in the charger 13. More specifically, Fig. 3 shows a part of the circuit of a converter 131 included in the charger 13 and a Y capacitor 132 connected to the converter.
In the figure, C1 to C4 are capacitors having appropriate capacitances, Tr is a transformer, and I is a leakage current.

Converter 131 is connected to the L terminal and the N terminal, and receives AC current from external charging equipment 2. Converter 131 converts the AC current into DC current. The converted DC current is output to a power factor correction circuit, a power conversion circuit, and the like (not shown), and is finally supplied to secondary battery 14.
The Y capacitor 132 removes a noise current that occurs when the converter 131 converts AC current into DC current. The removed noise current is released to the ground as a leakage current I via the earth-connected PE terminal.
However, the leakage current is not limited to the noise current generated from the charger 13 described above, but also includes, for example, a noise current caused by the vibration of the AC current and a noise current caused by the cable structure.

FIG. 4 is a circuit diagram showing chargers 13 connected in parallel.
When the chargers 13a and 13b are connected in parallel, the Y capacitor 132a of the charger 13a and the Y capacitor 132b of the charger 13b are also connected in parallel. Therefore, the leakage current released to the ground via the PE terminal is expressed as the sum of the leakage current Ia generated from the charger 13a and the leakage current Ib generated from the charger 13b.
In other words, when the chargers 13a and 13b are connected in parallel, the leakage current that is released to the ground via the PE terminal increases.

Returning to the explanation of FIG.
The secondary battery 14 is a secondary battery provided in the vehicle 1, and is, for example, a nickel-metal hydride battery. The secondary battery 14 is connected to a power source of the vehicle 1 (not shown), and supplies electric power to the power source of the vehicle 1. The secondary battery 14 is charged by a current appropriately converted by the charger 13.

The vehicle charging control unit 15 controls the charging of the vehicle 1. Specifically, the vehicle charging control unit 15 controls the charging of the secondary battery 14 based on the above-mentioned CPLT signal and PISW signal.
The vehicle charging control unit 15 detects a change in potential of the PISW signal caused by the connection between the PP terminal and the external charging equipment 2, and when it receives a CPLT signal oscillated by the external charging equipment 2, starts charging the secondary battery 14.

The vehicle charging control unit 15 recognizes the magnitude of the rated current passed by the external charging equipment 2 based on the change in potential of the PISW signal, and determines the number of chargers 13 to use based on the magnitude of the rated current. For example, if the magnitude of the rated current used is a magnitude that can be converted by one charger 13, the vehicle charging control unit 15 charges the secondary battery 14 using one charger 13. Also, if the magnitude of the rated current exceeds the magnitude that can be converted by one charger 13, the vehicle charging control unit 15 charges the secondary battery 14 using multiple chargers 13.

When the vehicle charging control unit 15 determines the number of chargers 13 to be used, it connects the chargers 13 to the inlets 11 based on the determined number of chargers 13 to be used. Specifically, the vehicle charging control unit 15 controls the charger connection relay 12 to connect the chargers 13 to the inlets 11.

In addition, if the potential of the PISW signal changes during charging and the magnitude of the rated current supplied from the external charging equipment 2 changes, the vehicle charging control unit 15 changes the number of chargers 13 connected to the inlet 11 based on the magnitude of the changed rated current.

In addition, when the vehicle charging control unit 15 is no longer able to receive the CPLT signal emitted from the external charging equipment 2, it controls the charger connection relay 12 to disconnect all chargers 13 from the inlets 11 and stop charging the secondary battery 14.

The vehicle charging control unit 15 also includes a calculation unit, such as a CPU (Central Processing Unit) (not shown), and a storage unit, such as a RAM (Random Access Memory) or a ROM (Read Only Memory), in which programs and data for controlling the charging of the secondary battery 14 are stored. In other words, the vehicle charging control unit 15 functions as a computer and controls the welding device based on the above-mentioned programs.

Therefore, the vehicle charging control unit 15 shown in FIG. 1 can be realized in hardware terms by the above-mentioned CPU, memory unit, other circuits, etc., and in software terms by a program for controlling the charging of the secondary battery 14 stored in the memory unit. In other words, the vehicle charging control unit 15 can be realized in various forms by hardware, software, or a combination of both.

With this configuration, the vehicle 1 can charge the secondary battery 14 using the number of chargers 13 determined based on the magnitude of the rated current set by the external charging facility 2 .
Furthermore, the vehicle 1 can stop charging the secondary battery 14 when the external charging facility 2 determines to stop charging.

The external charging equipment 2 is equipment for charging the vehicle 1, and may be, for example, a combination of a household outlet and a charging cable, or a charging station installed for EVs or PHEVs.

The external charging facility 2 includes an external AC power supply 21 , an inlet plug 22 , and an external charging control device 23 .
The external AC power supply 21 is a source of AC current supplied to the vehicle 1, and may be, for example, a household outlet.

The inlet plug 22 is a connector having a shape corresponding to the inlet 11 of the vehicle 1, and like the inlet 11, may conform to, for example, the US charger standard "SAE J1772 (SAE Electric Vehicle Conductive Charge Coupler)."

The inlet plug 22 has connection ports that can be connected to the L terminal, the N terminal, the PE terminal, the CP terminal, and the PP terminal of the inlet 11, respectively.
The connection ports corresponding to the L terminal and the N terminal are connected to an external AC power supply 21 via an external charging control device 23, and power output from the external AC power supply 21 is supplied to the L terminal and the N terminal.
The connection port corresponding to the PE terminal is earthed, and the leakage current output from the PE terminal is released to the ground.
The connection port corresponding to the CP terminal is connected to a CPLT signal oscillation circuit provided in the external charging control device 23 described later, and exchanges CPLT signals with the vehicle 1.
The connection port corresponding to the PP terminal is connected to a variable resistor Rc which is connected to earth.

The external charging control device 23 is a device for controlling the charging of the vehicle 1, and for example, in a case where the external charging equipment 2 is a combination of a household outlet and a charging cable, it is provided as a control box in the charging cable.
Furthermore, when the external charging equipment 2 is a charging station, the external charging control device 23 may be a device provided within the charging station, or may be provided as a functional block on a control unit of the charging station.

FIG. 5 is a block diagram for explaining the configuration of the external charging control device 23.
The external charging control device 23 includes a CPLT signal oscillation circuit 231, a leakage current detector 232, a threshold determination unit 233, and a variable resistor Rc.

The CPLT signal oscillation circuit 231 is a circuit that oscillates the above-mentioned CPLT signal, and transmits the CPLT signal to the vehicle 1 via the CP terminal.
Furthermore, the CPLT signal oscillation circuit 231 stops transmitting the CPLT signal based on the determination of a threshold determination unit 233, which will be described later.

The leakage current detector 232 is a device connected to the L terminal, the N terminal, and the external AC power supply 21, and measures the value of the leakage current output from the vehicle 1. For example, the leakage current detector 232 may be a zero-phase current transformer (ZCT). The leakage current detector 232 outputs the measured leakage current value to the threshold determination unit 233.

As described above, the variable resistor Rc is a variable resistor connected to the earth and is connected to the PP terminal. As described above, the resistance value of the variable resistor Rc includes information on the magnitude of the rated current passed through the vehicle 1, and is changed based on the control by the threshold determination unit 233.
For example, in this embodiment, the value of the variable resistor Rc is increased to reduce the magnitude of the rated current.

The threshold determination unit 233 determines whether or not the value of the leakage current detected by the leakage current detector 232 exceeds a predetermined threshold. Here, a first and a second threshold are set in the threshold determination unit 233, and a relationship of (first threshold)<(second threshold) is established.
When the value of the leakage current is equal to or less than the first threshold while the vehicle 1 is being charged, the threshold determination unit determines that charging is being performed normally, and allows charging to continue.

When the value of the leakage current during charging of the vehicle 1 is equal to or greater than the first threshold and less than the second threshold, the threshold determination unit 233 controls the variable resistor Rc to increase its resistance value in order to suppress the leakage current. When the value of the variable resistor Rc increases, the potential of the PISW signal oscillated in the vehicle 1 increases, and the vehicle charging control unit 15 in the vehicle 1 recognizes a decrease in the value of the rated current. When the vehicle charging control unit 15 in the vehicle 1 recognizes the decrease in the value of the rated current, it controls the charger connection relay 12 to stop the use of the second charger 13b. When the use of the second charger 13b is stopped, the leakage current decreases.
Of course, there is no problem if the first charger 13a is stopped instead of the second charger 13b.

In other words, when the threshold determination unit 233 detects a leakage current that is equal to or greater than the first threshold and less than the second threshold, the vehicle 1 stops charging by some of the chargers 13. As a result, the leakage current is suppressed.
Here, the first threshold value may be a value equal to or less than a limit value of leakage current defined for safety reasons, and by setting it in this manner, it is possible to prevent the occurrence of leakage current of a magnitude that is dangerous to the surroundings.

After the charging by the second charger 13b is stopped, the threshold determination unit 233 may determine whether the leakage current is equal to or greater than a third threshold. When the leakage current value exceeds the third threshold, the threshold determination unit 233 controls the CPLT signal oscillation circuit 231 to stop the oscillation of the CPLT signal and causes the vehicle charging control unit 15 to stop charging by all the chargers 13.
Here, the third threshold value may be the same as the first threshold value, or may be a value different from the first threshold value that is equal to or less than the limit value of the leakage current.
By setting the third threshold value in this manner, when the leakage current cannot be sufficiently suppressed due to the stopping of charging by some of the chargers 13, it is possible to stop charging the secondary batteries 14.

When the leakage current value during charging of the vehicle 1 is equal to or greater than the second threshold, the threshold determination unit 233 controls the CPLT signal oscillation circuit 231 to stop the oscillation of the CPLT signal. When the oscillation of the CPLT signal is stopped, the vehicle charging control unit 15 stops charging by all chargers 13.

In other words, when the threshold determination unit 233 detects a leakage current equal to or greater than the second threshold, the vehicle 1 stops charging by all of the on-board chargers 13 .
Here, the second threshold value may be a value obtained by adding an approximate value of the leakage current generated from one charger 13 to a limit value of the leakage current defined for safety reasons. By setting it in this way, charging can be continued if the leakage current can be suppressed to within the limit value by stopping one charger, and charging can be stopped if the leakage current cannot be suppressed to within the limit value by stopping one charger.

As described above, the charging control system according to this embodiment has a configuration that can suppress the occurrence of leakage current that exceeds a specified value established for safety. Even if the leakage current value is equal to or exceeds the specified value, if the leakage current value can be suppressed to within the specified value by stopping some of the chargers, some of the chargers can be stopped and charging can be continued. In other words, the charging control system according to this embodiment can suppress the frequency of charging stoppages in a vehicle equipped with multiple chargers connected in parallel.

<Charging control system operation>
Hereinafter, the operation of the charge control system according to the first embodiment, that is, the charge control method according to the first embodiment will be described in detail with reference to the drawings.
FIG. 6 is a flowchart showing the operation of the charge control system according to the first embodiment.
In the following description, reference will be made to FIGS. 1 and 5 as appropriate.

First, charging is started by the first and second chargers 13a and 13b (step ST1). Specifically, the vehicle charging control unit 15 first recognizes the connection between the inlet plug 22 and the inlet 11 by the potential change of the PISW signal and the CPLT signal oscillated by the external charging equipment 2. Then, it controls the charger connection relay 12 to connect the charger 13 to the L terminal and N terminal, and starts charging by the first and second chargers 13a and 13b.

Next, the leakage current detector 232 starts measuring the value of the leakage current, and the threshold determination unit 233 determines whether the leakage current is less than the first threshold (step ST2). If the leakage current is less than the first threshold (step ST2: Yes), the threshold determination unit 233 continues to repeat step ST2. That is, the threshold determination unit 233 repeats step ST2 until the leakage current becomes equal to or greater than the first threshold.
When charging is completed while the leakage current remains below the first threshold (that is, when charging is completed normally), the charging control system 1001 ends the operation.

If the leakage current is equal to or greater than the first threshold (step ST2: No), the threshold determination unit 233 determines whether the leakage current is less than the second threshold (step ST3). If the leakage current is equal to or greater than the second threshold (step ST3: No), the vehicle charging control unit 15 stops charging by the first and second chargers 13a and 13b (step ST4).

Specifically, in step ST4, the CPLT signal oscillator circuit first stops oscillating the CPLT signal. Then, the vehicle charging control unit 15, which no longer receives the CPLT signal, disconnects the charger connection relays 12a and 12b, and stops charging by the first and second chargers 13a and 13b.

If the leakage current is less than the second threshold (step ST3: Yes), the vehicle charging control unit 15 stops charging using the second charger 13b (step ST5) and continues charging using only the first charger 13a.

Specifically, in step ST5, the threshold determination unit 233 first increases the resistance value of the variable resistor Rc to suppress the rated current of the external charging equipment 2. Then, the vehicle charging control unit 15, which recognizes the suppression of the rated current due to the change in the potential of the PISW signal, disconnects the second charger connection relay 12b and stops charging by the second charger 13b.

Next, the threshold determination unit 233 determines whether the value of the leakage current is less than the third threshold (step ST6). If the leakage current is less than the third threshold (step ST6: Yes), the threshold determination unit 233 continues to repeat step ST6. That is, the threshold determination unit 233 repeats step ST6 until the leakage current becomes equal to or greater than the third threshold.
When charging is completed while the leakage current remains below the third threshold, the charging control system 1001 ends the operation.

If the leakage current is equal to or greater than the third threshold (step ST6: No), execute step ST4 and stop charging the vehicle 1.

By using the charging control method described above, the charging control system according to this embodiment can accurately determine whether to continue or stop charging. Furthermore, if charging can be continued by stopping some of the chargers, it can determine to stop some of the chargers. As a result, the charging control system according to this embodiment can reduce the frequency of stopping charging in a vehicle equipped with multiple chargers connected in parallel.

Other Embodiments
The vehicle 1 according to the first embodiment is provided with two chargers 13, but may be provided with three or more chargers 13 as described above.
For example, in a case where the vehicle 1 is equipped with three chargers 13, charging by one charger 13 may be stopped when the leakage current is equal to or greater than a first threshold value and less than a second threshold value, and charging by two chargers 13 may be stopped when the leakage current is equal to or greater than the second threshold value and less than a third threshold value. And, charging by all chargers 13 may be stopped when the leakage current is equal to or greater than the third threshold value.

In addition, when the vehicle 1 is equipped with three or more chargers 13, the chargers 13 may be divided into two groups. Then, when the leakage current is equal to or greater than the first threshold and less than the second threshold, charging by the chargers 13 belonging to one group may be suspended, and when the leakage current is equal to or greater than the second threshold, charging by all the chargers 13 may be suspended.

The present invention has been described above in accordance with the above embodiment, but the present invention is not limited to the configuration of the above embodiment, and of course includes various modifications, alterations, and combinations that a person skilled in the art could make within the scope of the invention of the claims of this application.

1 Vehicle 2 External charging equipment 11 Inlet 12, 12a, 12b Charger connection relay 13, 13a, 13b Charger 14 Secondary battery 15 Vehicle charging control unit 21 External AC power source 22 Inlet plug 23 External charging control device 131, 131a, 131b Converter 132, 132a, 132b Y capacitor 231 CPLT signal oscillation circuit 232 Leakage current detector 233 Threshold determination unit 1001 Charging control system Ra Resistor Rc Variable resistors C1 to C4, C1a to C4a, C1b to C4b Capacitors Tr, Tra, Trb Transformers I, Ia, Ib Leakage current

Claims (1)

A vehicle having a secondary battery and a plurality of chargers for charging the secondary battery;
a charging control device that detects leakage current during charging of the vehicle,
When the charging control device detects a leakage current exceeding a first threshold, the vehicle stops charging by some of the chargers;
When the charging control device detects a leakage current exceeding a second threshold, the vehicle stops charging by all of the chargers.
Charging control system.

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