Charging Control System

Abstract

To provide a charge control system that can control a charge stop frequency of a vehicle equipped with parallelly connected multiple battery chargers.SOLUTION: A charge control system relating to the present invention comprises: a vehicle 1 having a secondary battery 14 and multiple battery chargers 13; and an external charge control device 23 for detecting a leakage current when charging the vehicle 1. When the external charge control device 23 detects the leakage current exceeding a first threshold level, the vehicle 1 stops the charging by some of the battery chargers 13. When the charge control device detects the leakage current exceeding a second threshold level, the vehicle 1 stops the charging by all of the battery chargers 13.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a charging control system. [Background technology]

[0002] The charging time for secondary batteries installed in electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) is shortened as the amount of current flow increases. However, there is a limit to the current capacity of an on-board charger, which is one of the reasons why it is not possible to shorten the charging time for on-board secondary batteries. 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. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-201328 A Summary of the Invention [Problem to be solved by the invention]

[0004] The leakage current during vehicle charging must be controlled below a certain 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.

[0005] 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. Therefore, when multiple chargers connected in parallel are installed on a vehicle, there is an issue that charging of the vehicle frequently stops.

[0006] The present invention has been made to solve such problems, and aims to provide a charging control system that can reduce the frequency of charging stops in a vehicle equipped with multiple chargers connected in parallel. [Means for solving the problem]

[0007] 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.

[0008] With this configuration, even if the leakage current exceeds a specified value during charging of the vehicle, if the leakage current can be suppressed to below the specified value by stopping charging using some of the chargers, charging can be continued, thereby reducing the frequency of stopping charging of the vehicle. Effect of the Invention

[0009] According to the present invention, it is possible to provide a charging control system that can reduce the frequency of charging stops in a vehicle equipped with a plurality of chargers connected in parallel. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing a configuration of a charge control system 1001 according to a first embodiment. [Diagram 2] FIG. 11 is a circuit diagram for explaining the role of a PP terminal. [Diagram 3] 10 is a circuit diagram for explaining a mechanism by which a charger 13 generates a leakage current. [Figure 4] FIG. 2 is a circuit diagram showing a charger 13 connected in parallel. [Diagram 5] FIG. 2 is a block diagram for explaining the configuration of an external charging control device 23. [Figure 6] 4 is a flowchart showing the operation of the charge control system according to the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (First embodiment) <Charging control system configuration> Hereinafter, the 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 the 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.

[0012] 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 12a and 12b, first and second chargers 13a and 13b, 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.

[0013] In this embodiment, for simplicity, the vehicle 1 includes two charger connection relays 12 and two chargers 13, but the numbers of the charger connection relays 12 and the chargers 13 are not limited to two, and may be three or more.

[0014] The inlet 11 is a connection point between the vehicle 1 and the external charging equipment 2 described later. Specifically, the vehicle 1 and the external charging equipment 2 are connected by inserting an 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 a signal related to charging control, for example a CPLT (Control Pilot) signal, from the external charging equipment 2 via the inlet 11.

[0015] The inlet 11 according to the present 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 an L terminal), a ground terminal (hereinafter referred to as an N terminal), a protective ground terminal (hereinafter referred to as a PE terminal), a CP (Control Pilot) terminal, and a PP (Proximity Pilot) terminal (not shown).

[0016] The L terminal, the N terminal, and the PE terminal are connected to the charger 13 via the charger connection relay 12. The L terminal and the N terminal output the power supplied from the external charging equipment 2 to the charger 13. In addition, the PE terminal is connected to earth and allows leakage current generated from the charger 13 to escape to the ground.

[0017] 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 for controlling the charging of the vehicle 1.

[0018] Fig. 2 is a circuit diagram for explaining the role of the PP terminal. Note that Fig. 2 omits some of the components of the vehicle 1 and the external charging equipment 2 as appropriate. 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 vehicle charging control unit 15, passes through resistor Ra and the PP terminal, and returns to 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 causes 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, from the resistance value of the variable resistor Rc, connection information with the external charging equipment 2 and information indicating the magnitude of the rated current, and outputs this information to the vehicle charging control unit 15.

[0019] Let us return to the explanation of Figure 1 again. 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.

[0020] 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.

[0021] Fig. 3 is a circuit diagram for explaining a mechanism by which leakage current occurs in charger 13. More specifically, Fig. 3 shows a part of the circuit of converter 131 included in charger 13 and Y capacitor 132 connected to the converter. In the figure, C1 to C4 are capacitors with appropriate capacitances, Tr is a transformer, and I is a leakage current.

[0022] 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.

[0023] 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 charger 13a and the charger 13b are connected in parallel, the leakage current that is released to the ground via the PE terminal increases.

[0024] Let us return to the explanation of Figure 1 again. 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 power to the power source of the vehicle 1. The secondary battery 14 is charged by a current appropriately converted by the charger 13.

[0025] 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 upon receiving the CPLT signal oscillated by the external charging equipment 2, starts charging the secondary battery 14.

[0026] The vehicle charging control unit 15 recognizes the magnitude of the rated current supplied by the external charging equipment 2 based on the change in potential of the PISW signal, and determines the number of chargers 13 to be used based on the magnitude of the rated current. For example, when 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. On the other hand, when 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.

[0027] When vehicle charging control unit 15 determines the number of chargers 13 to be used, it connects chargers 13 and inlets 11 based on the determined number of chargers 13 to be used. Specifically, vehicle charging control unit 15 controls charger connection relay 12 to connect chargers 13 and inlets 11.

[0028] 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.

[0029] 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 batteries 14.

[0030] 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) that stores programs and data for controlling charging of secondary battery 14. In other words, vehicle charging control unit 15 has a function as a computer and controls the welding device based on the above-mentioned programs.

[0031] 1 can be realized in terms of hardware by the above-mentioned CPU, storage unit, other circuits, etc., and in terms of software by a program stored in the storage unit for controlling the charging of the secondary battery 14. That is, the vehicle charging control unit 15 can be realized in various forms by hardware, software, or a combination of both.

[0032] 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 determined 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.

[0033] The external charging facility 2 is a facility 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 an EV or a PHEV.

[0034] 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.

[0035] 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 be compliant with, for example, the US charger standard "SAE J1772 (SAE Electric Vehicle Conductive Charge Coupler)".

[0036] 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 connected to earth, and allows leakage current output from the PE terminal to escape 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, which will be described later, and exchanges a CPLT signal with the vehicle 1. The connection port corresponding to the PP terminal is connected to a variable resistor Rc that is connected to earth.

[0037] The external charging control device 23 is a device for controlling the charging of the vehicle 1, and for example, when 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.

[0038] FIG. 5 is a block diagram for explaining the configuration of the external charging control device 23. As shown in FIG. The external charging control device 23 includes a CPLT signal oscillation circuit 231, a leakage current detector 232, a threshold value determination unit 233, and a variable resistor Rc.

[0039] 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 the transmission of the CPLT signal based on the determination of the threshold determination section 233, which will be described later.

[0040] 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 value of the leakage current to the threshold determination unit 233.

[0041] As described above, the variable resistor device 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 value 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.

[0042] 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.

[0043] 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 the 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. Naturally, there is no problem if the first charger 13a is stopped instead of the second charger 13b.

[0044] That is, when the threshold value determination unit 233 detects a leakage current that is equal to or greater than the first threshold value and less than the second threshold value, 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 leakage current of a magnitude that is dangerous to the surroundings.

[0045] 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 value of the leakage current 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, the charging of the secondary batteries 14 can be stopped.

[0046] When the value of the leakage current 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 oscillation of the CPLT signal. When oscillation of the CPLT signal is stopped, the vehicle charging control unit 15 stops charging by all the chargers 13.

[0047] That is, 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 the chargers 13 mounted on the vehicle 1. 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, if the leakage current can be suppressed to within the limit value by stopping one charger, charging can be continued, and if the leakage current cannot be suppressed to within the limit value by stopping one charger, charging can be stopped.

[0048] With the configuration described above, the charging control system according to this embodiment can suppress the occurrence of leakage current exceeding a specified value determined for safety. Even if the leakage current value is equal to or greater than the specified value, if the leakage current value can be suppressed to within the specified value by stopping some of the chargers, the charging control system according to this embodiment can stop some of the chargers and continue charging. 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.

[0049] <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 FIG. 1 and FIG. 5 as appropriate.

[0050] First, charging by the first and second chargers 13a and 13b is started (step ST1). Specifically, first, the vehicle charging control unit 15 recognizes the connection between the inlet plug 22 and the inlet 11 by a potential change of the PISW signal and the CPLT signal oscillated by the external charging equipment 2. Then, the vehicle charging control unit 15 controls the charger connection relay 12 to connect the charger 13 to the L terminal and the N terminal, and charging by the first and second chargers 13a and 13b is started.

[0051] Next, the leakage current detector 232 starts measuring the value of the leakage current, and the threshold value determination unit 233 determines whether the leakage current is less than the first threshold value (step ST2). If the leakage current is less than the first threshold value (step ST2 Yes), the threshold value determination unit 233 continues to repeat step ST2. That is, the threshold value determination unit 233 repeats step ST2 until the leakage current becomes equal to or greater than the first threshold value. 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.

[0052] 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).

[0053] Specifically, in step ST4, first, the CPLT signal oscillation circuit 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.

[0054] If the leakage current is less than the second threshold value (Yes in step ST3), the vehicle charging control unit 15 stops charging by the second charger 13b (step ST5) and continues charging only by the first charger 13a.

[0055] Specifically, in step ST5, first, the threshold determination unit 233 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 from the potential change of the PISW signal, disconnects the second charger connection relay 12b and stops charging by the second charger 13b.

[0056] 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.

[0057] If the leakage current is equal to or greater than the third threshold value (No in step ST6), step ST4 is executed, and charging of the vehicle 1 is stopped.

[0058] By using the charge control method described above, the charge control system according to the present embodiment can accurately determine whether to continue or stop charging. In addition, if charging can be continued by stopping some of the chargers, it can determine to stop some of the chargers. As a result, the charge control system according to the present embodiment can reduce the frequency of stopping charging in a vehicle equipped with multiple chargers connected in parallel.

[0059] (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 and less than a second threshold, and charging by two chargers 13 may be stopped when the leakage current is equal to or greater than the second threshold and less than a third threshold. And, charging by all chargers 13 may be stopped when the leakage current is equal to or greater than the third threshold.

[0060] Furthermore, 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 a first threshold and less than a 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.

[0061] While the present invention has been described above with reference to the above-described embodiment, the present invention is not limited to the configuration of the above-described embodiment, and of course includes various modifications, alterations, and combinations that may be made by a person skilled in the art within the scope of the invention as defined in the claims of the present application. [Explanation of symbols]

[0062] 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 supply 22 Inlet plug 23 External charging control device 131, 131a, 131b Converter 132, 132a, 132b Y capacitor 231 CPLT signal oscillator circuit 232 Leakage Current Detector 233 Threshold Judgment Unit 1001 Charging control system Ra resistor Rc variable resistor C1~C4, C1a~C4a, C1b~C4b capacitors Tr, Tra, Trb transformers I, Ia, Ib Leakage current

Claims

[Claim 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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