Charging system

Abstract

Even if auxiliary equipment is operating during charging, the battery will continue to charge until it is fully charged. [Solution] The ECU performs a process that includes the steps of: reducing the charging current to the battery (S110) when charging is in progress (YES in S100), when an auxiliary device is operating (NO in S102), or when there is a request to stop the auxiliary device (YES in S108); stopping the operation of the auxiliary device (S114) when the charging current becomes zero (YES in S112); gradually increasing the charging current to the battery (S116); and stopping charging (S120) when the voltage becomes greater than a threshold (YES in S118).

Description

Technical Field

[0001] The present disclosure relates to a charging system.

Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2021-097569 (Patent Document 1) discloses a technique in which input power and output power of a battery pack including a battery (secondary battery) and a battery sensor that detects a state of the battery are controlled using Win and Wout converted from IWin and IWout obtained using detection values of the battery sensor.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] During charging using a charging station external to a vehicle, the voltage threshold for determining whether to terminate charging of the battery is set to a threshold corresponding to a fully charged state. However, when power is consumed due to, for example, the operation of an auxiliary machine, when the operation of the auxiliary machine stops, the current that had been flowing from the charging station to the auxiliary machine instantaneously flows into the battery, causing the voltage of the battery to rise and exceed the threshold, leading to an erroneous determination that the battery is in a fully charged state. In order to suppress such erroneous determination of a fully charged state, when an auxiliary machine is operating, the voltage threshold for determining whether to terminate charging of the battery is lowered compared to when the auxiliary machine is stopped. As a result, when the auxiliary machine is operating, charging of the battery is terminated before the battery reaches a fully charged state.

[0005] This disclosure was made to solve the above-mentioned problems, and its purpose is to provide a charging system that can charge the energy storage device until it is fully charged, even when auxiliary equipment is operating during charging. [Means for solving the problem]

[0006] A charging system according to one aspect of the present disclosure comprises a vehicle equipped with a power storage device and an auxiliary device, and a charging station that supplies power to the vehicle from outside the vehicle. The vehicle includes a control device that controls the power supplied from the charging station to supply a portion of the power supplied from the charging station to the auxiliary device when the operation of the auxiliary device is required while the power storage device is being charged using the charging station. When it is required that the operation of the auxiliary device be stopped, the control device reduces the charging current to the power storage device until it becomes zero, and allows the operation of the auxiliary device to continue until the charging current becomes zero.

[0007] In this way, when stopping the operation of an auxiliary device while it is running, the voltage will not rise to near the voltage corresponding to a fully charged state even if the current that was supplied to the auxiliary device flows to the energy storage device. Therefore, it becomes unnecessary to lower the voltage threshold for terminating charging to avoid misjudgment, and it becomes possible to charge the energy storage device until it reaches a fully charged state.

[0008] In one embodiment, the control device stops the auxiliary equipment after the charging current drops to zero, and then gradually increases the charging current after the auxiliary equipment has been stopped.

[0009] This method allows the charging of the energy storage device to continue while avoiding a sudden voltage surge, making it possible to charge the energy storage device until it is fully charged.

[0010] In one further embodiment, the control device terminates charging when the voltage of the energy storage device reaches a threshold corresponding to the fully charged state of the energy storage device.

[0011] This method allows the battery storage system to be fully charged regardless of whether the auxiliary equipment is operating or not. [Effects of the Invention]

[0012] According to this disclosure, it is possible to provide a charging system that can charge the energy storage device until it is fully charged, even when auxiliary equipment is operating during charging. [Brief explanation of the drawing]

[0013] [Figure 1] This is a diagram showing an example of the configuration of the charging system according to this embodiment. [Figure 2] This diagram illustrates the power flow during operation of an auxiliary device while it is being externally charged. [Figure 3] This diagram illustrates the power flow when an auxiliary device that is in operation stops while external charging is in progress. [Figure 4] This diagram illustrates the change in battery voltage during external charging in the comparative example. [Figure 5] This flowchart shows an example of a process performed by the ECU. [Figure 6] This figure shows an example of the change in battery voltage in this embodiment. [Modes for carrying out the invention]

[0014] The embodiments of this disclosure will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated.

[0015] Hereinafter, the configuration of the charging system 1 according to the present embodiment will be described. FIG. 1 is a diagram showing an example of the configuration of the charging system 1 according to the present embodiment. As shown in FIG. 1, the charging system 1 includes a vehicle 200 and a charging station 10 which is a power supply facility external to the vehicle 200. The vehicle 200 may be any vehicle on which a power storage device that can be charged using electric power supplied from an external power source is mounted, and for example, may be an electric vehicle such as an electric vehicle or a plug-in hybrid vehicle.

[0016] The vehicle 200 includes an ECU (Electronic Control Unit) 100 serving as a control device, a battery 214, an inverter 216, an MG (Motor Generator) 218, an inlet 220, a DC / DC converter 222, and an auxiliary machine 224.

[0017] The battery 214 only needs to be a rechargeable power storage device, and includes, for example, a nickel-metal hydride battery or a secondary battery such as a lithium ion battery having a liquid electrolyte or a solid electrolyte. Note that a capacitor may be used as the power storage device instead of the battery 214.

[0018] The inverter 216 is configured to be capable of bidirectionally converting DC power of the battery 214 and AC power of the MG 218 in accordance with a control signal from the ECU 100.

[0019] The MG 218 is a drive source that drives drive wheels of the vehicle 200, and is configured by, for example, a three-phase AC rotating electric machine or the like.

[0020] The inlet 220 has a shape to which the connector 17 of the charging station 10 can be attached. The inlet 220 is electrically connected to the battery 214.

[0021] The DC / DC converter 222 transforms DC power between the battery 214 or the inlet 220 and an auxiliary battery (not shown) or an auxiliary device 224. Specifically, the DC / DC converter 222 steps down the DC power supplied from the battery 214 or the inlet 220 and outputs the stepped-down DC power to at least one of the auxiliary battery and the auxiliary device 224. The auxiliary device 224 includes, for example, interior lighting, an air conditioner, an audio system, a car navigation system, instruments, a drive recorder, and the like.

[0022] Both the DC / DC converter 222 and the auxiliary device 224 operate in accordance with control signals from the ECU 100.

[0023] Connected to the ECU 100 are a voltage sensor 102 for acquiring the voltage of the battery 214, a current sensor 104 for acquiring the current flowing through the battery 214, and a temperature sensor 106 for acquiring the temperature of the battery 214. The ECU 100 includes a CPU (Central Processing Unit) and a memory (neither is shown). The ECU 100 controls each device (including the DC / DC converter 222 and the auxiliary device 224) based on signals received from each sensor and information such as maps and programs stored in the memory so that the vehicle 200 enters a desired state. Further, the ECU 100 further includes a communication unit (not shown) and is configured to be able to communicate with a communication unit 13 of a charging station 10, which will be described later.

[0024] The ECU 100 has a function of sequentially calculating the SOC (State Of Charge) of the battery 214 based on detection values from the voltage sensor 102, the current sensor 104, and the temperature sensor 106. As a method for calculating SOC, various known methods can be employed, such as, for example, a method based on current value integration (coulomb counting) or a method based on estimation of open circuit voltage (OCV: Open Circuit Voltage).

[0025] The charging station 10 includes a communication unit 13, a control unit 14, a charging unit 15, a cable 16, and a connector 17. The charging station 10 includes, for example, a fast charger that completes charging in a shorter time than normal charging by supplying higher charging power than normal charging.

[0026] The communication unit 13 communicates with the ECU 100 of the vehicle 200 via cable 16 when the connector 17 is connected to the inlet 220 of the vehicle 200. Wired communication includes, for example, power line communication, CAN (Control Area Network) communication, or LAN communication. The communication unit 13 may also communicate with the ECU 100 of the vehicle 200 using, for example, wireless communication of various standards (for example, Wi-Fi).

[0027] The control unit 14 controls the operation of the charging unit 15 (for example, charging power and charging current). The control unit 14 includes, for example, a CPU and memory (neither of which are shown). The control unit 14 controls the charging unit 15 based on information received from the vehicle 200 using the communication unit 13 (such as the requested current value and requested power, which will be described later) and information such as maps and programs stored in memory. When the connector 17 is attached to the inlet 220, the control unit 14 uses the communication unit 13 to acquire information about the battery 214 (for example, information about the SOC, charging power and requested current value) and to transmit information about the charging station 10 (for example, information about the available time and the lower limit of the charging power and output current that can be supplied).

[0028] The charging unit 15 converts AC power from the grid power supply 400 into DC power according to a control signal from the control unit 14. One end of the cable 16 is connected to the charging unit 15. The other end of the cable 16 is connected to a connector 17.

[0029] The connector 17 has a shape that allows it to be attached to the inlet 220. When the connector 17 is attached to the inlet 220, DC power can be supplied from the charging unit 15 to the battery 214 in response to a control signal from the control unit 14.

[0030] For example, when the connector 17 is connected to the inlet 220 of a stationary vehicle 200, the charging station 10 operates the charging unit 15 to convert AC power from the grid power supply 400 into DC power and supplies the converted DC power to the battery 214. While the battery 214 is being charged, the ECU 100 transmits information about the State of Charge (SOC) and the requested current value calculated using the detection values ​​of the voltage sensor 102, the current sensor 104, and the temperature sensor 106 to the control unit 14. For example, when the SOC is calculated, the ECU 100 calculates the requested current value corresponding to the calculated SOC, the full charge capacity of the battery 214, or the battery temperature of the battery 214, and transmits information about the SOC and the requested current value to the control unit 14.

[0031] However, if power is consumed during charging using the charging station 10, such as when the auxiliary equipment 224 is operating, the voltage threshold for determining whether or not the battery 214 is fully charged is lowered compared to when the auxiliary equipment 224 is not operating. This is because when the state changes from one in which the auxiliary equipment 224 is consuming power to one in which it is not, the current that was flowing from the charging station 10 to the auxiliary equipment 224 momentarily flows to the battery 214, causing the voltage to rise and reach the voltage threshold for charging completion, leading to a false determination that the battery is fully charged.

[0032] Figure 2 is a diagram illustrating the power flow during the operation of the auxiliary unit 224 while it is being externally charged. As shown in Figure 2, when the auxiliary unit 224 is operating while it is being externally charged, for example, if 50 kW of power is supplied to the vehicle 200 from the charging station 10, then 10 kW of the supplied power will be supplied to the auxiliary unit 224 to operate it, and the remaining 40 kW will be supplied to the battery 214.

[0033] Figure 3 illustrates the power flow when the auxiliary unit 224, which is in operation, stops during external charging. When the auxiliary unit 224, which is in operation, stops during external charging, the 10kW of power that was supplied to the auxiliary unit 224 at the moment of stopping is added to the 40kW supplied to the battery 214. As a result, the voltage of the battery 214 rises sharply.

[0034] Figure 4 is a diagram illustrating the change in the voltage of the battery 214 during external charging in a comparative example. The vertical axis of Figure 4(A) shows the voltage of the battery 214. The horizontal axis of Figure 4(A) shows time. LN1 in Figure 4(A) shows the change in the voltage of the battery 214 when the auxiliary equipment 224, which was in operation, stops.

[0035] As shown in LN1 of Figure 4(A), for example, let's assume that the auxiliary device 224 is in operation and external charging starts at time T(0). During external charging, the voltage increases as time passes. If the operation of the auxiliary device 224 is stopped at time T(1), the voltage of the battery 214 will rise rapidly, as explained in Figure 3. As a result, it will rise to near the threshold V(0) for determining a fully charged state, and at time T(2), when the voltage of the battery 214 reaches the threshold V(0), the battery 214, which is not fully charged, will be incorrectly determined to be fully charged. To suppress this incorrect determination, if the auxiliary device 224 is in operation, it is conceivable to terminate the charging of the battery 214 when the voltage of the battery 214 reaches a threshold V(1) which is lower than the threshold V(0) for determining a fully charged state.

[0036] In this case, if the auxiliary unit 224 is stopped, as shown in LN2 of Figure 4(B), charging starts at time T(3) and ends when the voltage of the battery 214 reaches the threshold V(0) at time T(4), thus the battery 214 can be fully charged. On the other hand, if the auxiliary unit 224 is operating, as shown in LN3 of Figure 4(B), charging starts at time T(3) and ends when the voltage of the battery 214 reaches the threshold V(1) at time T(4), so the battery 214 cannot be fully charged.

[0037] Therefore, in this embodiment, when the ECU 100 requests that the operation of the auxiliary equipment 224 be stopped while it is running, it reduces the charging current to the battery 214 until it becomes zero, and allows the operation of the auxiliary equipment 224 to continue until the charging current becomes zero.

[0038] In this way, when the operation of the auxiliary device 224 is stopped while it is running, the voltage can be avoided even if the current that was supplied to the auxiliary device 224 flows to the battery 214. Therefore, it is possible to determine when charging is complete without lowering the threshold for charging completion. As a result, it becomes possible to charge the battery 214 until it is fully charged.

[0039] The following describes an example of the processes performed in the ECU100, with reference to Figure 5. Figure 5 is a flowchart showing an example of the processes performed in the ECU100. The series of processes shown in this flowchart are repeatedly executed at predetermined intervals.

[0040] In step 100 (hereinafter referred to as S), the ECU 100 determines whether or not charging is in progress. The ECU 100 may determine that charging is in progress when, for example, the connector 17 is connected to the inlet 220 and power is being supplied to the battery 214. The ECU 100 may also determine that charging is in progress when, for example, it receives an ON signal output from a connection detection circuit (not shown) provided in the inlet 220 when the connector 17 is attached to the inlet 220, and the charging current detected by the current sensor is greater than zero. If it is determined that charging is in progress (YES in S100), the process moves to S102.

[0041] In S102, the ECU 100 determines whether the auxiliary equipment 224 is stopped or not. The ECU 100 may determine that the auxiliary equipment 224 is stopped if, for example, the flag indicating that the auxiliary equipment 224 is operating is in the off state, or it may determine that the auxiliary equipment 224 is stopped if it is detected using various sensors that power is not being supplied to the auxiliary equipment 224. If it is determined that the auxiliary equipment 224 is stopped (YES in S102), the process moves to S104.

[0042] In S104, the ECU 100 determines whether or not there is a request to operate the auxiliary equipment 224. The ECU 100 may determine that there is a request to operate the auxiliary equipment 224 if, for example, it receives an operation to operate the auxiliary equipment 224. Alternatively, the ECU 100 may determine that there is a request to operate the auxiliary equipment 224 (for example, the air conditioning system or the cooling system for the battery 214) when a predetermined condition (for example, the temperature is higher than a threshold or the temperature is lower than a threshold) is met regarding the state of the vehicle 200 (for example, the room temperature or battery temperature). If it is determined that there is a request to operate the auxiliary equipment 224 (YES in S104), the process moves to S106.

[0043] In S106, ECU100 activates auxiliary device 224. At this time, ECU100 may set a flag indicating that auxiliary device 224 is operating to the ON state. The process then moves to S108.

[0044] In S108, the ECU 100 determines whether or not there is a request to stop the auxiliary equipment 224. The ECU 100 may determine that there is a request to stop the auxiliary equipment 224 if, for example, it receives an operation to stop the operation of the auxiliary equipment 224. Alternatively, the ECU 100 may determine that there is a request to stop the auxiliary equipment 224 if, for example, the above-mentioned predetermined conditions regarding the state of the vehicle 200 are not met. If it is determined that there is a request to stop the auxiliary equipment 224 (YES in S108), the process moves to S110.

[0045] In S110, the ECU 100 reduces the charging current to the battery 214. The ECU 100 may, for example, reduce the charging current to the battery 214 at a predetermined slope (a predetermined decrease per unit time), or it may reduce the charging current nonlinearly with respect to the passage of time. The process then moves to S112.

[0046] In S112, the ECU 100 determines whether the charging current is zero. The ECU 100 may, for example, determine whether the value detected by the current sensor 104 is zero, or it may determine that the charging current is zero if the value detected by the current sensor 104 is below a threshold. If it is determined that the charging current is zero (YES in S112), the process moves to S114.

[0047] In S114, ECU100 stops the operation of auxiliary unit 224. The process then moves to S116.

[0048] In S116, the ECU 100 gradually increases the charging current to the battery 214. The battery 214 may increase its charging current by a predetermined value each time a predetermined period of time has elapsed since the auxiliary equipment 224 was stopped. For example, if the charging current reaches a value that existed before the request to stop the auxiliary equipment 224 was determined, the battery 214 maintains the charging current at that value. The process then moves to S118.

[0049] In S118, the ECU 100 determines whether the voltage of the battery 214 is greater than the threshold V(0). The ECU 100 obtains the voltage of the battery 214 using the voltage sensor 102. The threshold V(0) is set to the voltage when the battery 214 is fully charged. If it is determined that the voltage of the battery 214 is greater than the threshold V(0) (YES in S118), the process moves to S120.

[0050] In S120, the ECU 100 stops charging. The ECU 100 stops charging, for example, by requesting the charging station 10 to stop charging. The process then ends. If it is determined that charging is not in progress (NO in S100), this process ends. Furthermore, if it is determined that the auxiliary equipment 224 is not stopped (NO in S102), the process moves to S108. Furthermore, if it is determined that there is no request to operate the auxiliary equipment 224 (NO in S104), the process moves to S118. Furthermore, if it is determined that there is no request to stop the auxiliary equipment 224 (NO in S108), the process moves to S118. Furthermore, if it is determined that the charging current is not zero (NO in S112), the process returns to S110. Furthermore, if it is determined that the voltage is below the threshold V(0) (NO in S118), the process returns to S102.

[0051] An example of the operation of the ECU 100 based on the structure and flowchart described above will be explained with reference to Figure 6. Figure 6 is a diagram showing an example of the change in the voltage of the battery 214 in this embodiment. The vertical axis of Figure 6 represents the voltage of the battery 214. The horizontal axis of Figure 6 represents time. LN4 in Figure 6 shows an example of the change in the voltage of the battery 214 when the auxiliary equipment 224 is operating. LN5 in Figure 6 shows an example of the change in the voltage of the battery 214 when the auxiliary equipment 224 is stopped.

[0052] If charging is performed using the charging station 10 (YES in S100), the auxiliary equipment 224 is stopped (YES in S102), and there is no request to operate the auxiliary equipment 224 (NO in S104), charging continues until the voltage reaches the threshold V(0) (NO in S118). Similarly, if the auxiliary equipment 224 is operating (NO in S102), and there is no request to stop the auxiliary equipment 224 (NO in S108), charging continues until the voltage of the battery 214 reaches the threshold V(0) (NO in S118).

[0053] If charging is in progress (YES in S100), the auxiliary unit 224 is stopped (YES in S102), and the user performs an operation to activate the auxiliary unit 224, and it is determined that there is a request to activate the auxiliary unit 224 (YES in S104), the ECU 100 activates the auxiliary unit 224 (S106).

[0054] If, while the auxiliary device 224 is operating, the user performs an operation to stop the auxiliary device 224, and it is determined that there is a request to stop the auxiliary device 224 (YES in S108), the charging current to the battery is reduced by a predetermined slope (S110). Then, when the charging current becomes zero (YES in S112), the operation of the auxiliary device 224 is stopped (S114). After that, the charging current to the battery 214 is increased in stages (S116). Performing these operations prevents a rapid increase in the voltage of the battery 214. Therefore, as shown in LN4 and LN5 in Figure 6, for example, even if charging starts at time T(5), regardless of whether the auxiliary device 224 is operating or not, charging ends at time T(6) when the voltage of the battery 214 reaches the threshold V(0) (YES in S118) (S120), so that the battery 214 can be fully charged.

[0055] As described above, with the charging system 1 according to this embodiment, when the operation of the auxiliary equipment 224 is stopped while it is running, the voltage rise can be avoided even if the current that was supplied to the auxiliary equipment 224 flows to the battery 214. Therefore, it is possible to determine when charging is complete without lowering the voltage threshold for charging completion. As a result, it is possible to charge the battery 214 until it is fully charged. Thus, it is possible to provide a charging system that can charge the energy storage device until it is fully charged even when the auxiliary equipment is operating during charging.

[0056] Furthermore, by stopping the auxiliary unit 224 after the charging current drops to zero, and then gradually increasing the charging current after stopping the auxiliary unit 224, it is possible to continue charging the battery 214 while avoiding a sudden rise in the battery voltage, thus allowing the battery 214 to be charged until it is fully charged.

[0057] In the above embodiment, the case in which DC power is supplied to the battery 214 from the charging station 10 was described as an example. However, AC power may be supplied from the charging station 10, and the AC power may be converted to DC power using a charging device (not shown) mounted on the vehicle 200 and supplied to the battery 214.

[0058] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0059] 1 Charging system, 10 Charging station, 13 Communication unit, 14 Control unit, 15 Charging unit, 16 Cable, 17 Connector, 100 ECU, 102 Voltage sensor, 104 Current sensor, 106 Temperature sensor, 200 Vehicle, 214 Battery, 216 Inverter, 220 Inlet, 222 DC / DC converter, 224 Auxiliary equipment, 400 System power supply.

Claims

1. A vehicle equipped with an energy storage device and auxiliary equipment, The vehicle is equipped with a charging station that supplies power to the vehicle from outside the vehicle, The vehicle includes a control device that controls the power supplied from the charging station to supply a portion of the power supplied from the charging station to the auxiliary equipment when the operation of the auxiliary equipment is required while the power storage device is being charged using the charging station. A charging system in which, when the control device is required to stop the operation of the auxiliary device, it reduces the charging current to the energy storage device until it becomes zero, and continues the operation of the auxiliary device until the charging current becomes zero.

2. The charging system according to claim 1, wherein the control device stops the auxiliary equipment after the charging current has decreased to zero, and then gradually increases the charging current after the auxiliary equipment has been stopped.

3. The charging system according to claim 1 or 2, wherein the control device terminates charging when the voltage of the energy storage device reaches a threshold corresponding to the fully charged state of the energy storage device.

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