Charging system

Abstract

To provide a charging system where an AC charging inlet and a DC charging inlet are shared, the charging system which detects fastening of a relay in a simple structure.SOLUTION: A charging system comprises: a battery; a charging inlet to which an external charging power source can be attached or detached; a DC charging path; an AC charging path; a first relay; a second relay; a first voltage sensor; and a controller. The controller is constituted to be capable of executing fastening detection processing of the second relay. The fastening detection processing comprises the processing of: giving an open command to at least the second relay; electrically blocking one of the DC charging path and the AC charging path from the battery and applying voltage through the other to the second relay from the battery; and determining, when the difference of detection voltage of the first voltage sensor and detection voltage of a second voltage sensor is within a prescribed range during execution of applying voltage, fastening of the second relay.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a charging system. [Background technology]

[0002] Patent Document 1 describes a charging system that includes a battery, an AC charging inlet, a DC charging inlet, a first relay provided in a first path connecting the battery and the AC charging inlet, a second relay provided in a second path connecting the battery and the DC charging inlet, and a control device that controls the operation of the first relay and the second relay.

[0003] The above-described relay may become inoperable and remain in the closed state due to the end of its life or due to welding caused by an excessive current flowing through it. In this specification, such a relay abnormality is referred to as being stuck. In this regard, the control device of Patent Document 1 determines that the second relay is stuck when an open command is given to the second relay but the second path remains in a conducting state. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-95916 Summary of the Invention [Problem to be solved by the invention]

[0005] In the charging system described above, the AC charging inlet and the DC charging inlet may be shared. External AC power is converted to DC power by a power converter and then supplied to the battery. This power converter has an allowable voltage value of the AC power supply voltage (e.g., 240 V), and it is necessary to prevent a DC power supply voltage exceeding this limit (e.g., 800 V) from being applied to the power converter. In this regard, it is conceivable to interpose a relay between the DC charging path that supplies DC power to the battery and the AC charging path that supplies AC power to the battery. However, if the relay is stuck, there is a risk that the DC power supply voltage will be applied to the power converter.

[0006] In view of the above circumstances, this specification provides a technique for detecting a stuck relay with a simple configuration in a charging system that shares an AC charging inlet and a DC charging inlet. [Means for solving the problem]

[0007] The technology disclosed in this specification is embodied in a charging system. The charging system includes a battery, a charging inlet to which an external charging power source can be attached, a DC charging path connecting the battery and the charging inlet, an AC charging path connecting the battery and the charging inlet via a power converter and connected in parallel to the DC charging path, a first relay provided in the DC charging path and electrically connecting and disconnecting the battery from the charging inlet, a second relay provided in the AC charging path and electrically connecting and disconnecting the power converter from the charging inlet, a first voltage sensor provided in the DC charging path between the charging inlet and the first relay, a second voltage sensor provided in the AC charging path between the second relay and the power converter, and a control device connected to the first voltage sensor and the second voltage sensor and controlling the first relay, the second relay, and the power converter. The control device is configured to perform a process for detecting a sticking of the second relay. The fixation detection process includes a process of issuing an open command to at least the second relay, a process of electrically disconnecting one of the DC charging path and the AC charging path from the battery while applying a voltage from the battery to the second relay via the other path, and a process of determining that the second relay is stuck when a difference between a voltage detected by the first voltage sensor and a voltage detected by the second voltage sensor is within a predetermined range during the execution of the voltage application process.

[0008] In the charging system described above, the control device executes a process for detecting whether the second relay is stuck. In this process, after an open command is issued to at least the second relay, for example, a voltage is applied from the battery to the second relay via the AC charging path while electrically disconnecting the DC charging path from the battery. If the second relay is stuck, the second voltage sensor provided in the AC charging path remains electrically connected to the first voltage sensor provided in the DC charging path via the second relay. Therefore, the voltages detected by the first voltage sensor and the second voltage sensor are approximately equal. In contrast, if the second relay is not stuck, the first voltage sensor and the second voltage sensor are electrically disconnected by the second relay. Therefore, a significant difference should occur between the voltages detected by the first voltage sensor and the second voltage sensor. In light of this, in the above-described sticking detection process, when the difference between the voltage detected by the first voltage sensor and the voltage detected by the second voltage sensor is within a predetermined range during the execution of the voltage application process, it is determined that the second relay is stuck. With this configuration, it is possible to detect a stuck relay with a simple configuration. Similarly, it is possible to detect a stuck relay even if a voltage is applied to the second relay from the battery via the DC charging path while electrically disconnecting the AC charging path from the battery.

[0009] In the above-described embodiment, the process of issuing an open command may also issue an open command to the first relay. In this case, the process of applying a voltage may apply a voltage from the battery to the second relay via the AC charging path by operating a power converter. With this configuration, in the sticking detection process, a voltage is applied from the battery to the second relay via the AC charging path while electrically disconnecting the DC charging path from the battery.

[0010] In some of the above-described embodiments, the sticking detection process may further include a process of issuing a close command to the first relay before the process of applying a voltage. In this case, the process of applying a voltage may apply a voltage from the battery to the second relay via the DC charging path. According to this configuration, in the sticking detection process, a voltage is applied from the battery to the second relay via the DC charging path while electrically disconnecting the AC charging path from the battery.

[0011] In the above-described embodiment, the DC charging path may be configured to selectively connect the entire battery or a portion of the battery to the first relay. In this case, in the voltage application process, a portion of the battery may be electrically connected to the first relay. With this configuration, in the stuck-state detection process, the voltage of only a portion of the battery, rather than the entire battery voltage, can be applied to the second relay via the DC charging path. This makes it possible to prevent an excessive voltage from being applied to the power converter even if the entire battery voltage (i.e., the nominal voltage of the battery) is higher than the voltage that the power converter can tolerate (i.e., the rated voltage of the power converter). [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram illustrating a schematic configuration of a charging system 10 and a vehicle 100 according to a first embodiment. [Figure 2] 10 is a flowchart showing an example of a first sticking detection process. [Figure 3] FIG. 10 is a diagram schematically illustrating the configuration of a charging system and a vehicle according to a second embodiment. [Figure 4] 10 is a flowchart showing an example of a second sticking detection process. DETAILED DESCRIPTION OF THE INVENTION

[0013] A charging system 10 according to a first embodiment will be described with reference to the drawings. The charging system 10 according to the first embodiment is mounted on a vehicle 100. The vehicle 100 is a rechargeable electric vehicle having a battery 12 that is charged by an external charging power source 2. However, the vehicle 100 may also be a hybrid vehicle (i.e., a plug-in hybrid vehicle) having a battery 12 that is charged by the external charging power source 2.

[0014] As shown in FIG. 1 , the vehicle 100 includes a load 102, a power converter 104, and a system main relay 106. The load 102 is, for example, a traction motor that drives the wheels of the vehicle 100. In this embodiment, the load 102 is a three-phase motor generator having a U phase, a V phase, and a W phase. The power converter 104 in this embodiment is an inverter. The power converter 104 is provided between the battery 12 and the load 102 and converts DC power from the battery 12 into three-phase AC power and supplies it to the load 102, or converts three-phase AC power from the load 102 into DC power and supplies it to the battery 12. The system main relay 106 is electrically interposed between the battery 12 and the load 102. Therefore, the battery 12 and the load 102 are electrically connected and disconnected by closing and opening the system main relay 106. The operation of the system main relay 106 is controlled by a control device (not shown).

[0015] As shown in FIG. 1, the charging system 10 includes a battery 12, a charging inlet 14, and a power supply outlet 16. The battery 12 has multiple built-in secondary battery cells and is configured to be repeatedly charged using external power and regenerative power from the motor of the vehicle 100. The charging inlet 14 is configured to allow an external charging power source 2 to be attached / detached. The external charging power source 2 is, for example, a DC charging stand, an AC charging stand, or a power outlet installed in a home or the like. The charging inlet 14 receives charging power for charging the battery 12 from the external charging power source 2. The power supply outlet 16 is configured to allow an electrical device to be attached / detached. The power supply outlet 16 outputs AC power to electrical devices such as home appliances, personal computers, smartphones, tablet devices, etc.

[0016] 1 , the charging system 10 further includes a DC charging path 18, an AC charging path 20, and an AC power supply path 22. The DC charging path 18 connects the battery 12 and the charging inlet 14. The AC charging path 20 connects the battery 12 and the charging inlet 14 via a charging power converter 28. The AC charging path 20 is connected in parallel to the DC charging path 18. The AC power supply path 22 connects the battery 12 and the power supply outlet 16.

[0017] 1 , the charging system 10 further includes a first relay 24, a second relay 26, and a charging power converter 28. The first relay 24 is provided in the DC charging path 18 and is interposed between the charging inlet 14 and the battery 12. Therefore, the battery 12 is electrically connected to and disconnected from the charging inlet 14 by closing and opening the first relay 24.

[0018] The second relay 26 is provided in the AC charging path 20 and is interposed between the charging inlet 14 and the charging power converter 28. In addition, the second relay 26 is connected to the power supply outlet 16 via the AC power supply path 22. When the second relay 26 is in a first closed state, the charging power converter 28 (and the battery 12) is electrically connected to the charging inlet 14. When the second relay 26 is in a second closed state, the charging power converter 28 is electrically connected to the power supply outlet 16 and electrically disconnected from the charging inlet 14. When the second relay 26 is in an open state, the charging power converter 28 is electrically disconnected from the charging inlet 14 and the power supply outlet 16.

[0019] DC charging path 18 is configured by a pair of lines including a high-voltage line and a low-voltage line. In this specification, this pair of lines is collectively referred to as DC charging path 18. Similarly, AC charging path 20 and AC power supply path 22 each have a pair of lines. In each of DC charging path 18 and AC charging path 20, first relay 24 or second relay 26 described above may be a pair of relays provided on each of the pair of lines, or may be a single relay provided on one of the pair of lines.

[0020] The charging power converter 28 is electrically interposed between the charging inlet 14 and the battery 12 in the AC charging path 20. The charging power converter 28 can convert AC power supplied from the external charging power source 2 into DC power supplied to the battery 12. As a result, the charging power converter 28 can charge the battery 12 using the externally supplied AC power. In addition, the charging power converter 28 is electrically interposed between the power supply outlet 16 and the battery 12 in the AC power supply path 22. The charging power converter 28 can convert DC power supplied from the battery 12 into AC power supplied to the power supply outlet 16. As a result, the charging power converter 28 can convert DC power supplied from the battery 12 into AC power and supply it to an electrical device connected to the power supply outlet 16. In other words, the charging power converter 28 is a charger that has not only a charging function but also a power supply function, and is also called a bidirectional charger.

[0021] As shown in FIG. 1 , the charging system 10 further includes a charging control device 30. The charging control device 30 is a computer device having a processor, memory, and the like. The charging control device 30 is communicatively connected to each of the first relay 24, the second relay 26, and the charging power converter 28, and controls their operation. For example, when an AC charging power source 2 is connected to the charging inlet 14, the charging control device 30 places the second relay 26 in a first closed state and issues an operation command to the charging power converter 28. This causes the battery 12 to be charged. When a DC charging power source 2 is connected to the charging inlet 14, the charging control device 30 closes the first relay 24. This causes the battery 12 to be charged.

[0022] As shown in FIG. 1 , the charging system 10 further includes a first voltage sensor 32 and a second voltage sensor 34. The first voltage sensor 32 is provided in the DC charging path 18 between the charging inlet 14 and the first relay 24. This allows the first voltage sensor 32 to detect the voltage applied to the section of the DC charging path 18 between the charging inlet 14 and the first relay 24. The second voltage sensor 34 is provided in the AC charging path 20 between the second relay 26 and the charging power converter 28. This allows the second voltage sensor 34 to detect the voltage applied to the section of the AC charging path 20 between the second relay 26 and the charging power converter 28. The charging control device 30 is communicatively connected to each of the voltage sensors 32, 34 and is able to monitor the voltages detected by each of the voltage sensors 32, 34.

[0023] Next, the first fixation detection process will be described with reference to Fig. 2. The charging control device 30 of this embodiment is configured to be able to execute the first fixation detection process. In this first fixation detection process, when the second relay 26 remains in the first closed state even after receiving an open command, the second relay 26 is detected as being fixed. The charging control device 30 is configured to start the first fixation detection process before starting charging by the external charging power source 2.

[0024] As shown in FIG. 2 , the charging control device 30 first issues an open command to the first relay 24 and the second relay 26 (S10). As a result, in the DC charging path 18, the first relay 24 is opened, disconnecting the battery 12 from the charging inlet 14. If the second relay 26 is stuck, the second relay 26 is maintained in the first closed state, and the second voltage sensor 34 provided in the AC charging path 20 remains electrically connected to the first voltage sensor 32 provided in the DC charging path 18 via the second relay 26. On the other hand, if the second relay 26 is not stuck, the second relay 26 is opened, and the first voltage sensor 32 and the second voltage sensor 34 are electrically disconnected by the second relay 26. At this time, the DC charging path 18 is electrically disconnected from the battery 12, while the AC charging path 20 is electrically connected to the battery 12. The opening command to second relay 26 is not limited to a command to open second relay 26, but may be a command to switch second relay 26 to the second closed state. That is, the opening command may be a command to electrically disconnect charging power converter 28 from the section of AC charging path 20 that is provided between second relay 26 and DC charging path 18.

[0025] Next, the charging control device 30 activates the charging power converter 28 (S12). This causes a voltage to be applied from the battery 12 to the second relay 26 via the AC charging path 20. If the second relay 26 is stuck, the voltage V1 detected by the first voltage sensor 32 and the voltage V2 detected by the second voltage sensor 34 will be approximately equal. In contrast, if the second relay 26 is not stuck, there should be a significant difference between the voltage V1 detected by the first voltage sensor 32 and the voltage V2 detected by the second voltage sensor 34.

[0026] Therefore, during execution of step S12, the charging control device 30 determines whether the difference between the voltage V1 detected by the first voltage sensor 32 and the voltage V2 detected by the second voltage sensor 34 is within a predetermined range (S14). Here, the predetermined range can be determined taking into consideration the detection error of each voltage sensor 32, 34, etc. The predetermined range may be constant or may vary depending on specific conditions. If the answer is YES in step S14, the charging control device 30 determines that the second relay 26 is locked (S16). If the answer is NO in step S14, the charging control device 30 determines that the second relay 26 is in a normal state (S18). After processing step S16 or step S18, the charging control device 30 ends the first lock-up detection process.

[0027] As described above, in the charging system 10 having the charging inlet 14 to which an external DC power supply and an AC power supply can be detachably attached, it is possible to detect whether the second relay 26 is stuck with a simple configuration.

[0028] (Embodiment 2) Next, a charging system of embodiment 2 will be described with reference to Fig. 3. In embodiment 2, the DC charging path 18 is modified compared to embodiment 1. Specifically, the DC charging path 18 further includes a connection path 36 that connects the midpoint 12a of the battery 12 and the low-voltage path of the first relay 24, and a third relay 38 provided on the connection path 36. The remaining configuration is the same as that of the charging system 10 of embodiment 1, so a duplicated description will be omitted here.

[0029] The charge control device 30 of the second embodiment is configured to be able to execute the second fixation detection process shown in Fig. 4. In the second fixation detection process, as in the first fixation detection process, the second relay 26 is detected as being stuck when the second relay 26 remains in the first closed state even after receiving an open command. However, the first fixation detection process and the second fixation detection process differ in the path through which voltage is applied from the battery 12 to the second relay 26. Specifically, in the first fixation detection process, voltage is applied from the battery 12 to the second relay 26 via the AC charging path 20, whereas in the second fixation detection process, voltage is applied from the battery 12 to the second relay 26 via the DC charging path 18.

[0030] 4, the charge control device 30 first issues a close command to the first relay 24 and the third relay 38 (S20). As a result, the first relay 24 and the third relay 38 are closed in the DC charging path 18, and the midpoint 12a of the battery 12 and the charging inlet 14 are connected to each other.

[0031] Next, the charge control device 30 issues an open command to the second relay 26 (S22). If the second relay 26 is stuck, the second relay 26 is maintained in the first closed state. On the other hand, if the second relay 26 is not stuck, the second relay 26 is opened, and the AC charging path 20 is electrically disconnected from the battery 12, while the DC charging path 18 is electrically connected to the battery 12. Here, as in the first embodiment, the open command to the second relay 26 may be any command that electrically disconnects the charging power converter 28 from the section of the AC charging path 20 that is provided between the second relay 26 and the DC charging path 18, and may be, for example, a command to switch the second relay 26 to the second closed state.

[0032] Then, the charging control device 30 applies a voltage from the battery 12 to the second relay 26 via the DC charging path 18 (S24). While executing step S24, the charging control device 30 determines whether the difference between the voltage V1 detected by the first voltage sensor 32 and the voltage V2 detected by the second voltage sensor 34 is within a predetermined range (S26). If the answer is YES in step S26, it is determined that the second relay 26 is stuck (S28), whereas if the answer is NO in step S26, it is determined that the second relay 26 is in a normal state (S30). Here, the predetermined range can be determined taking into consideration detection errors by the voltage sensors 32, 34, etc. The predetermined range may be constant or may vary depending on specific conditions.

[0033] According to the above-described configuration, in the sticking detection process, the voltage of only a portion of the battery 12, rather than the entire voltage of the battery 12, can be applied to the second relay 26 via the DC charging path 18. This makes it possible to prevent an excessive voltage from being applied to the charging power converter 28, even if the entire voltage of the battery 12 (i.e., the nominal voltage of the battery 12) is higher than the voltage that the charging power converter 28 can tolerate (i.e., the rated voltage of the charging power converter 28).

[0034] 4, charging control device 30 may issue a close command only to first relay 24. In this case, voltage can be applied from battery 12 to second relay 26 via DC charging path 18 while AC charging path 20 is electrically disconnected from battery 12.

[0035] As described above, the first and second fixation detection processes use different paths when a voltage is applied from the battery 12 to the second relay 26. Therefore, the charge control device 30 in the first embodiment may be configured to be able to execute the second fixation detection process shown in Fig. 4 in addition to or instead of the first fixation detection process shown in Fig. 2.

[0036] Although several specific examples have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility either alone or in combination. [Explanation of symbols]

[0037] 2: Charging power source, 10: Charging system, 12: Battery, 12a: Neutral point, 14: Charging inlet, 16: Power supply outlet, 18: DC charging path, 20: AC charging path, 22: AC power supply path, 24: First relay, 26: Second relay, 28: Charging power converter, 30: Charging control device, 32: First voltage sensor, 34: Second voltage sensor, 36: Connection path, 38: Third relay, 100: Vehicle, 102: Load, 104: Power converter, 106: System main relay

Claims

[Claim 1] A battery, A charging inlet that allows an external charging power source to be attached or detached, a DC charging path connecting the battery and the charging inlet; an AC charging path that connects the battery and the charging inlet via a power converter and is connected in parallel to the DC charging path; a first relay provided in the DC charging path and configured to electrically connect and disconnect the battery to and from the charging inlet; a second relay provided in the AC charging path and configured to electrically connect and disconnect the power converter to and from the charging inlet; a first voltage sensor provided in the DC charging path between the charging inlet and the first relay; a second voltage sensor provided in the AC charging path between the second relay and the power converter; a control device connected to the first voltage sensor and the second voltage sensor and controlling the first relay, the second relay, and the power converter; Equipped with the control device is configured to be able to execute a process for detecting a sticking of the second relay, The sticking detection process includes: a process of giving an opening command to at least the second relay; a process of electrically disconnecting one of the DC charging path and the AC charging path from the battery, and applying a voltage from the battery to the second relay via the other of the DC charging path and the AC charging path; a process of determining that the second relay is stuck when a difference between a voltage detected by the first voltage sensor and a voltage detected by the second voltage sensor is within a predetermined range during the process of applying the voltage; Including, charging system.

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