Electric vehicle power transmission system

Abstract

The present invention provides an electric power transmission system for electric vehicles that reduces progression of degradation of a relay while also being able to respond to a quick cutoff request of a relay. Provided is an electric power transmission system for electric vehicles that is to be mounted on an electric vehicle having a battery which stores electric power for traveling and an electric device which receives electric power from the battery. The electric power transmission system comprises: an electric power reception unit which is capable of receiving electric power from a charging facility; a charger which charges the battery with received electric power; a first electric power line which transmits electric power between the electric device and the battery; a second electric power line which transmits electric power between the battery and the charger; a relay which is capable of cutting the first electric power line without cutting the second electric power line; and a controller which controls the relay. When a cutoff request from the relay based on an anomaly has occurred, the controller cuts of the relay after a current generation process. The current generation process for applying a current between the charger and the battery in the direction that the current of the relay decreases.

Description

[Technical Field]

[0001] The present invention relates to a power transmission system for an electric vehicle. [Background technology]

[0002] An electric vehicle is equipped with a system main relay that can disconnect the high-voltage battery from the system power line. Patent Document 1 describes that the system main relay is disconnected when no current is flowing through it in order to prevent welding or other problems from occurring at the relay contacts. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-223053 Summary of the Invention [Problem to be solved by the invention]

[0004] The system main relay carries current between the high-voltage battery and the electrical device. It takes some time to control the electrical device and reduce the current in the system main relay. Furthermore, situations may arise where it is difficult to reduce the current by controlling the electrical device. Therefore, when a request to quickly turn off the system main relay is made, it is not easy to reduce the current in the system main relay and then respond to the request.

[0005] An object of the present invention is to provide a power transmission system for an electric vehicle that can quickly respond to a request to turn off the relay while reducing the progression of relay deterioration. [Means for solving the problem]

[0006] A power transmission system for an electric vehicle according to one aspect of the present invention includes: A power transmission system for an electric vehicle that is mounted on an electric vehicle having a battery that stores electric power for driving and an electric device that receives electric power from the battery, a power intake unit capable of taking in power from a charging facility provided outside the electric vehicle; a charger that charges the battery using power taken in via the power taking-in unit; a first power line for transmitting power between the electrical device and the battery; a second power line for transmitting power between the battery and the charger; a relay capable of disconnecting the first power line without disconnecting the second power line; a controller for controlling the relay; Equipped with the controller, when a request to turn off the relay based on an abnormality is made, turns off the relay after a current generation process; The current generation process is a process of flowing a current between the charger and the battery in a direction that decreases the current in the relay. [Effects of the Invention]

[0007] According to the present invention, it is possible to quickly respond to a request to turn off the relay while reducing the progression of relay deterioration. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a block diagram illustrating an electric vehicle and a power transmission system according to an embodiment of the present invention. [Figure 2A] FIG. 10 is a diagram showing a first stage of a relay cutoff process based on an abnormality during battery discharge. [Figure 2B] FIG. 10 is a diagram showing a second stage of the relay cutoff process based on an abnormality during battery discharge. [Figure 2C] FIG. 10 is a diagram showing a third stage of the relay cutoff process based on an abnormality during battery discharge. [Figure 2D] FIG. 10 is a diagram showing a fourth stage of the relay cutoff process based on an abnormality during battery discharge. [Figure 3A] FIG. 10 is a diagram showing a first stage of a relay cutoff process based on an abnormality during battery charging. [Figure 3B] FIG. 10 is a diagram showing a second stage of the relay cutoff process based on an abnormality during battery charging. [Figure 3C] FIG. 10 is a diagram showing a third stage of the relay cutoff process based on an abnormality during battery charging. [Figure 3D] FIG. 10 is a diagram showing a fourth stage of the relay cutoff process based on an abnormality during battery charging. [Figure 4] 10 is a flowchart illustrating an example of a relay shutoff process based on an abnormality, which is executed by the controller. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this specification, opening of the relay contacts is referred to as "disconnecting" the relay, and closing of the relay contacts is referred to as "connecting" the relay. Furthermore, of the current of the battery 12, the current in the direction in which power is released from the battery 12 is referred to as "discharging current," and the current in the direction in which power is sent to the battery 12 is referred to as "charging current."

[0010] Fig. 1 is a block diagram showing an electric vehicle and a power transmission system according to an embodiment of the present invention. The electric vehicle 1 in Fig. 1 includes drive wheels 2, a battery 12 that stores electric power for driving, and an electric device 11 that is driven by the electric power of the battery 12. The electric device 11 includes an electric motor 11a that generates power for the drive wheels 2, and an inverter 11b that converts electric power between the battery 12 and the electric motor 11a. The electric vehicle 1 further includes a power transmission system 20.

[0011] The power transmission system 20 includes a power intake unit 21 capable of taking in power from a charging facility provided outside the electric vehicle 1, a charger 22 capable of charging the battery 12 using the power taken in via the power intake unit 21, a first power line 23 that transmits power between the electrical device 11 and the battery 12, a second power line 24 that transmits power between the battery 12 and the charger 22, relays 25a, 25b that can disconnect the first power line 23 without disconnecting the second power line 24, a current sensor 26 that detects the current of the battery 12, a voltage sensor 27 that detects the voltage of the battery 12, a controller 28 that controls the relays 25a, 25b, a charging controller 29 that controls the charger 22, and a current sensor 31 that detects the current flowing through the charger 22.

[0012] Controller 28 is a vehicle controller that controls the running of electric vehicle 1, and the vehicle controller also serves as controller 28 that controls relays 25a and 25b. Note that controller 28 that controls relays 25a and 25b and the vehicle controller may be configured separately and may communicate with each other to cooperate with each other.

[0013] In addition to the electric motor 11a and the inverter 11b, the electric device 11 may also include other devices such as a heater, an air conditioner, a DC / DC converter, and an on-board inverter.

[0014] The battery 12 is, for example, a lithium ion secondary battery, a nickel-metal hydride secondary battery, or the like, and outputs a high voltage of 80 V or more (for example, 100 V or 200 V).

[0015] The current sensor 26 is provided on a power line connected to the negative terminal of the battery 12 and detects the value of the current flowing through the negative terminal of the battery 12. The current sensor 26 may be a magnetic current sensor with a core, a coreless magnetic current sensor, or a resistive current sensor. The resistive current sensor refers to a method in which a current is passed through a resistor such as a shunt resistor and the current is detected from the voltage across the resistor. The current sensor 26 may also be provided on a power line connected to the positive terminal of the battery 12 and detect the value of the current flowing through the positive terminal of the battery 12. Alternatively, the current sensor 26 may be configured to detect current values ​​at multiple locations on a branching power line and perform calculations based on these current values ​​to determine the value of the current flowing through the battery 12.

[0016] Relays 25a and 25b are system main relays. Relays 25a and 25b are switched between disconnection and connection under the control of controller 28. Relays 25a and 25b are provided midway along first power line 23, closer to electric device 11 than the connection point between first power line 23 and second power line 24. Therefore, when relays 25a and 25b are disconnected, first power line 23 can be disconnected without disconnecting second power line 24.

[0017] The power intake unit 21 is configured to be able to receive power from an external charging facility 41 provided in the travel lane while the vehicle is traveling, and to transmit power to the external charging facility 41 while the vehicle is traveling. The power intake unit 21 is, for example, a power transmission coil, and transmits power to and from the charging facility 41 via electromagnetic action. The external charging facility 41 is, for example, configured with multiple coils arranged along the travel lane. The charging facility 41 may have any configuration as long as it can transmit power contactlessly to and from the traveling electric vehicle 1.

[0018] Charger 22 converts the power (e.g., AC power) taken in from charging facility 41 via power intake unit 21 into charging power (e.g., DC power) and outputs it to second power line 24, thereby charging battery 12. Hereinafter, this operation will be referred to as a "charging operation." Conversely, charger 22 receives power (e.g., DC power) from battery 12, converts the power into transmission power (e.g., AC power), and sends it to power intake unit 21, thereby sending the power to charging facility 41. Hereinafter, this operation will be referred to as a "discharging operation." The power sent to charging facility 41 is sent to an electrical load provided in charging facility 41, or to another electric vehicle traveling on the same charging facility 41.

[0019] The current sensor 31 is provided on a power line connected to the positive electrode of the charger 22 and detects the value of the current flowing through the positive electrode of the charger 22. The current sensor 31 may be located inside or outside the charger 22. The current sensor 31 may be a magnetic current sensor with a core, a coreless magnetic current sensor, or a resistive current sensor. The current sensor 31 may be provided on a power line connected to the negative electrode of the charger 22 and detect the value of the current flowing through the negative electrode of the charger 22. Alternatively, the current sensor 31 may be configured to detect current values ​​at multiple locations on a branching power line and perform calculations based on these current values ​​to determine the value of the current flowing through the charger 22.

[0020] The charge controller 29 is a microcomputer that operates according to a control program, and controls the operation of the charger 22. The charge controller 29 controls the charger 22, causing the charger 22 to perform a discharging operation and a charging operation.

[0021] The controller 28 is a microcomputer that operates according to a control program. As a vehicle controller, the controller 28 controls the inverter 11b to power the electric motor 11a based on an acceleration command from the driver or the automatic driving system. This control causes a discharge current to flow from the battery 12 to the inverter 11b, discharging the battery 12. Furthermore, as a vehicle controller, the controller 28 controls the inverter 11b to regenerate the electric motor 11a based on a deceleration command from the driver or the automatic driving system. This control causes a charge current to flow from the inverter 11b to the battery 12, charging the battery 12.

[0022] Furthermore, the controller 28 operates as a vehicle controller, monitoring the state of the electrical device 11, and if a specific abnormality occurs, it issues a request to turn off the relays 25a and 25b.

[0023] Controller 28 controls the opening and closing of relays 25a and 25b. For example, controller 28 connects relays 25a and 25b when the system of electric vehicle 1 is started up, and disconnects relays 25a and 25b when the system of electric vehicle 1 is shut down. Controller 28 also disconnects relays 25a and 25b when a disconnection request is made based on the above-mentioned abnormality. The outputs of current sensor 26, voltage sensor 27, and current sensor 31 are sent to controller 28.

[0024] The controller 28 can further communicate with a charge controller 29 and control the charger 22 via the charge controller 29 .

[0025] <Specific examples of abnormalities> In the electric vehicle 1, if a fault such as a short circuit occurs in the electric device 11, an abnormality occurs in which a discharge current continues to flow from the battery 12 to the electric device 11. Furthermore, if a fault occurs in the inverter 11b or the control system of the inverter 11b and causes the electric motor 11a to perform unexpected regenerative operation, an abnormality occurs in which an unexpected charge current continues to flow from the inverter 11b to the battery 12.

[0026] When an abnormality such as the above occurs, the controller 28 issues a request to turn off the relays 25a and 25b based on the abnormality, in order to protect the battery 12. Then, based on the turn-off request, the controller 28 performs processing to quickly turn off the relays 25a and 25b. This processing can prevent the abnormal discharge current from the battery 12 from continuing or the abnormal charge current to the battery 12 from continuing.

[0027] The request to turn off the relays 25a and 25b based on an abnormality is not limited to being generated based on an abnormal continuation of the charging current to the battery 12 or an abnormal continuation of the discharging current from the battery 12. The request to turn off the relays 25a and 25b based on an abnormality may be generated based on another abnormality, such as detection of a collision of the electric vehicle 1. Alternatively, the request to turn off the relays 25a and 25b based on an abnormality may be generated based on discharging exceeding the dischargeable power Wout of the battery 12 and charging exceeding the chargeable power Win.

[0028] <Relay cutoff process during discharge> Next, a process will be described in the case where a request to turn off relays 25a, 25b due to an abnormality occurs while discharging from battery 12 to electric device 11 (hereinafter referred to as "during discharging"). Figures 2A to 2D are diagrams respectively showing first to fourth stages of relay turning-off process due to an abnormality during discharging.

[0029] Before a cutoff request is made, the battery 12 is discharging, so as shown in Fig. 2A, a discharge current I1 flows from the battery 12 to the electrical device 11. As shown in Fig. 2B, when a cutoff request is made based on an abnormality, the controller 28 first performs a current generation process to cause a current I2 to flow between the charger 22 and the battery 12 in a direction that reduces the current flowing through the relays 25a and 25b.

[0030] 2C, controller 28 requests charge controller 29 to perform a discharging operation, and causes power to be transmitted from battery 12 to external charging equipment 41 via charger 22 and power intake unit 21. This operation causes a discharge current I2 to flow from battery 12 to charger 22. The period during which discharge current I2 is generated may be a short period of, for example, 1 ms to 1000 ms.

[0031] The battery 12 has a limit to its instantaneous discharge capacity. Therefore, the discharge current I2 of the current generation process causes the battery 12 to discharge close to its limit of discharge capacity, and as shown in FIG. 2C, the voltage V of the battery 12 decreases. This decrease in voltage V reduces the discharge current I1 from the battery 12 to the electrical device 11, i.e., the discharge current I1 flowing through the relays 25a and 25b. The decrease in discharge current I1 may be sufficient to reduce the magnitude of the arc that occurs when the relays 25a and 25b are interrupted.

[0032] 2D, when the discharge current I1 flowing through relays 25a and 25b decreases, controller 28 shuts off relays 25a and 25b. If relays 25a and 25b were to be shut off while a large current was flowing through them, a large arc would occur, which could cause deterioration of the contacts of relays 25a and 25b. However, because the discharge current I1 flowing through relays 25a and 25b has been reduced by the current generation process, the shutdown reduces deterioration of the contacts of relays 25a and 25b.

[0033] <Relay cutoff process during charging> Next, a case where a request to shut off relays 25a and 25b due to an abnormality occurs while power is being sent from electrical device 11 to battery 12 (hereinafter referred to as "during charging") will be described. Note that "during charging" above does not include a case where battery 12 is being charged only by power sent from external charging equipment 41. Figures 3A to 3D are diagrams respectively showing first to fourth stages of relay shutoff processing due to an abnormality during charging.

[0034] Before the interruption process occurs, the battery is being charged, and as shown in Fig. 3A, a charging current I3 is being sent from the electric device 11 to the battery 12. As shown in Fig. 3B, when an interruption request is made due to an abnormality, the controller 28 first performs a current generation process to flow a current I4 between the charger 22 and the battery 12 in a direction that reduces the current flowing through the relays 25a and 25b.

[0035] 3C, controller 28 requests charging controller 29 to perform a charging operation, and causes power to be transmitted from external charging equipment 41 to battery 12 via power intake unit 21 and charger 22. This operation causes charging current I4 to flow from charger 22 to battery 12. The period during which charging current I4 is generated may be a short period of, for example, 1 ms to 1000 ms.

[0036] Battery 12 has a limit to its instantaneous charging capacity. Therefore, charging current I4 of the current generation process charges battery 12 close to its limit, and as shown in FIG. 3C, the internal resistance R of battery 12 increases, or the voltage V of battery 12 rises. As a result, charging current I3 sent from electrical device 11 to battery 12, i.e., charging current I3 flowing through relays 25a and 25b, decreases. The decrease in charging current I3 only needs to correspond to a decrease that can reduce the magnitude of the arc that occurs when relays 25a and 25b are opened.

[0037] 3D, when the current flowing through relays 25a and 25b decreases, controller 28 shuts off relays 25a and 25b. If relays 25a and 25b were to be shut off while a large current was flowing through them, a large arc would occur, which could cause deterioration of the contacts of relays 25a and 25b. However, because the charging current I3 flowing through relays 25a and 25b has been reduced by the current generation process, the shutoff reduces deterioration of the contacts of relays 25a and 25b.

[0038] <Relay shutdown process based on anomalies> Next, a more specific example of the relay shutoff process will be described. Fig. 4 is a flowchart showing an example of the relay shutoff process based on an abnormality, which is executed by the vehicle controller.

[0039] 4 is initiated by the controller 28 when a current abnormality in the battery 12 is detected and a request to stop the current to the electrical device 11 is issued, but the abnormality is not resolved (for example, the current does not decrease to a predetermined value within a predetermined time). The above-mentioned current abnormality includes the occurrence of a current that deviates from the current expected for control, the occurrence of a current that exceeds the allowable current set based on the SOC of the battery 12 (for example, a discharge current generated at a lower limit SOC or a charge current generated at an upper limit SOC), and the occurrence of a current that exceeds the allowable current set based on the operating parameters of the battery 12 (such as chargeable and dischargeable power, temperature, etc.). Current abnormalities include a first abnormality in which a discharge current continues to flow to the battery 12, and a second abnormality in which a charge current continues to flow to the battery 12.

[0040] When the relay shutoff process is started, the controller 28 first determines the direction of the current flowing through the relays 25a and 25b (step S1). Specifically, the controller 28 determines the direction of the current flowing through the relays 25a and 25b based on the current value of the battery 12 detected by the current sensor 26, or based on the current value of the battery 12 and the current value of the charger 22 detected by the current sensor 31. Note that in step S1, it is assumed that the current of the charger 22 is sufficiently small compared to the current of the battery 12, so the direction of the current through the relays 25a and 25b may be determined only from the current value of the battery 12 detected by the current sensor 26. That is, in step S1, it is determined whether the current abnormality is a first abnormality in which a discharging current continues, or a second abnormality in which a charging current continues. More specifically, when a current flows from the "+" terminal of current sensors 26 and 31 to the "-" terminal as shown in the figure, the detected values ​​of current sensors 26 and 31 may be positive, and when a current flows in the opposite direction, the detected values ​​of current sensors 26 and 31 may be negative. Here, it is assumed that the current of charger 22 is sufficiently small. Therefore, if the value obtained by subtracting the detected value of current sensor 31 from the detected value of current sensor 26 is positive, controller 28 determines that a discharging current is flowing through relays 25a and 25b. Conversely, if the value obtained by subtracting the detected value of current sensor 31 from the detected value of current sensor 26 is negative, controller 28 determines that a charging current is flowing through relays 25a and 25b. Note that if the connection positions or connection directions of current sensors 26 and 31 are different from those shown in the figure, controller 28 can make the same determination using the same calculation by inverting the positive and negative detected current values ​​as necessary.

[0041] As a result, if the current is a discharge current, controller 28 causes charger 22 to perform a discharging operation by sending a request to charge controller 29 (step S2). On the other hand, if the current is a charging current, controller 28 causes charger 22 to perform a charging operation by sending a request to charge controller 29 (step S3). Step S2 or S3 is the current generation process shown in Fig. 2C or 3C, and step S2 or S3 reduces the current flowing through relays 25a, 25b.

[0042] Next, controller 28 determines whether the current through relays 25a and 25b is equal to or less than current threshold Ith (step S4). The current values ​​through relays 25a and 25b can be calculated as the difference between the current value detected by current sensor 26 (i.e., the current value through battery 12) and the current value detected by current sensor 31 (i.e., the current value through charger 22). More specifically, if the "+" and "-" terminals of current sensors 26 and 31 are connected in the orientations described above, controller 28 subtracts the detection value of current sensor 26 from the detection value of current sensor 31, and calculates the absolute value of the subtraction as the current value through relays 25a and 25b. If the connection positions or orientations of current sensors 26 and 31 are different from those shown in the figure, controller 28 can calculate the same current values ​​by similar calculations, provided that the detected current values ​​are inverted as necessary. Alternatively, controller 28 may subtract the absolute value of the detection value of current sensor 26 from the absolute value of the detection value of current sensor 31, and calculate the absolute value of the subtraction as the current value of relays 25a, 25b. The current threshold Ith may be set to a value that can reduce the magnitude of the arc generated in relays 25a, 25b.

[0043] If the result of the determination in step S4 is YES, the controller 28 turns off the relays 25a and 25b (step S6). Then, the relay turning-off process ends. By turning off the relays 25a and 25b after reducing the current in this manner, it is possible to sufficiently reduce the deterioration of the relays 25a and 25b.

[0044] On the other hand, if the result of the determination in step S4 is NO, the controller 28 determines whether the voltage of the battery 12 is equal to or lower than the first threshold value Vth1 and equal to or higher than the second threshold value Vth2 (step S5). The first threshold value Vth1 may be set to, for example, the upper limit of an allowable voltage range (such as "rated voltage - margin value"). The second threshold value Vth2 is a value smaller than the first threshold value Vth1. The second threshold value Vth2 may be set to, for example, the lower limit of an allowable voltage range (such as "discharge end voltage + margin value"). The voltage value of the battery 12 is obtained from the output of the voltage sensor 27.

[0045] If the result of the determination in step S5 is YES, the controller 28 returns the process to step S1, repeats the current generation process in step S2 or S3, and again performs the determination process in step S4. By repeatedly continuing the current generation process, the current in the relays 25a, 25b is more likely to be reduced to or below the current threshold Ith.

[0046] On the other hand, if the result of the determination in step S5 is NO, the controller 28 does not repeat the current generation process, i.e., it interrupts the current generation process and turns off the relays 25a and 25b (step S6). The relay shutoff process then ends. The current generation process in steps S2 and S3 instantaneously discharges or charges the battery 12 to near the limit of its discharge or charge capacity, so excessive execution of the process should be avoided. Therefore, the determination and branching process in step S5 prevents the current generation process from being performed excessively, thereby protecting the battery 12.

[0047] Even if the determination result in step S5 is NO and the relays 25a and 25b are turned off, the current flowing through the relays 25a and 25b is reduced because the current generation process has been performed in the previous step S2 or S3. Therefore, even in the above case, the deterioration of the relays 25a and 25b is reduced.

[0048] The program for the relay shutoff process is stored in a non-transitory computer readable medium 28a included in the controller 28. The controller 28 may be configured to read the program stored in the portable non-transitory recording medium and execute the program. The portable non-transitory recording medium may store the program for the relay shutoff process.

[0049] As described above, according to the power transmission system 20 of the present embodiment, when a request to turn off the relays 25a and 25b is issued based on an abnormality, the controller 28 turns off the relays 25a and 25b after performing a current generation process. The current generation process is a process of causing a current to flow between the charger 22 and the battery 12 in a direction that reduces the current through the relays 25a and 25b. The current generation process quickly reduces the current through the relays 25a and 25b, and the relays 25a and 25b can be turned off in a state where the current through the controller 28 and the relays 25a and 25b has decreased. Therefore, the request to turn off the relays 25a and 25b can be quickly responded to while reducing the deterioration of the relays 25a and 25b.

[0050] In the current generation process, power is transmitted between the battery 12 and the charger 22 as current is generated. Therefore, a source or destination of the power is required to execute the current generation process. According to the power transmission system 20 of this embodiment, power is transmitted between the battery 12 and the charging facility 41 via the power intake unit 21 in the current generation process. With this configuration, it is not necessary for the electric vehicle 1 to have a configuration for storing power that generates a charging current in the power generation process, or a configuration for consuming or absorbing a discharging current in the power generation process. Therefore, the power transmission system 20 can be made more compact.

[0051] Furthermore, according to the power transmission system 20 of this embodiment, when a first abnormality occurs in which a discharging current continues from the battery 12 to the electric device 11, the current generation process is a process of flowing a current in a direction to send power from the battery 12 to the charger 22 (i.e., a discharging current). When a second abnormality occurs in which a charging current continues from the electric device 11 to the battery 12, the current generation process is a process of flowing a current in a direction to send current from the charger 22 to the battery 12 (i.e., a charging current). By such a current generation process, the current in the relays 25a, 25b can be quickly reduced as shown in FIGS. 2C and 3C.

[0052] Furthermore, according to the power transmission system 20 of this embodiment, when the voltage of the battery 12 exceeds the first threshold Vth1 during the current generation process, the controller 28 suspends the current generation process (see steps S5 and S6 in FIG. 4). Therefore, the voltage of the battery 12 is prevented from rising too much due to the current generation process, and the battery 12 can be protected.

[0053] Furthermore, according to the power transmission system 20 of this embodiment, the controller 28 suspends the current generation process when the voltage of the battery 12 becomes lower than the second threshold Vth2 during the current generation process (see steps S5 and S6 in FIG. 4). Therefore, the voltage of the battery 12 is prevented from dropping too much due to the current generation process, and the battery 12 can be protected.

[0054] Furthermore, according to the power transmission system 20 of this embodiment, the power intake unit 21 is configured to be able to transmit power contactlessly from the charging equipment 41 provided in the travel lane while the vehicle is traveling. Therefore, it is possible to deal with a case where a request to turn off the relays 25a and 25b is made based on an abnormality that occurs while the vehicle is traveling.

[0055] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments. For example, in the above embodiments, an example was shown in which the controller 28 that controls the relays 25a and 25b is a vehicle controller that controls the traveling of the electric vehicle 1. Also, an example was shown in which the charge controller 29 that controls the charger 22 is provided separately from the controller 28. However, the controller that controls the relays 25a and 25b, the controller that controls the traveling of the electric vehicle 1, and the controller that controls the charger 22 may be integrated into a single controller. Alternatively, each may be provided as a separate controller, or any two controllers may be integrated and the other controller may be provided independently. In this case, the multiple controllers communicate with each other and operate cooperatively to achieve processing similar to that of the above embodiments.

[0056] Furthermore, in the above embodiment, an example has been described in which the controller 28 turns off the relays 25a, 25b after the current generation process based on a request to turn off the relays 25a, 25b due to an abnormality both during discharging and charging of the battery 12. However, the controller 28 may perform the current generation process only during discharging of the battery 12, or may perform the current generation process only during charging of the battery 12. Even with such a configuration, it is possible to quickly respond to a request to turn off the relays 25a, 25b while reducing the progression of deterioration of the relays 25a, 25b during either charging or discharging.

[0057] Furthermore, in the above embodiment, the controller 28 interrupts the current generation process both when the voltage of the battery 12 exceeds the first threshold Vth1 and when it falls below the second threshold Vth2 during the current generation process. However, the controller 28 may interrupt the current generation process only in one of the cases. Furthermore, in the above embodiment, a configuration example was shown in which the power acquisition unit 21 can transmit power to the charging equipment 41 contactlessly while the vehicle is traveling. However, the power acquisition unit 21 may also be configured to transmit power to the charging equipment contactlessly or via a cable or the like while the vehicle is stopped. In such a configuration, if a request to turn off the relays 25a and 25b due to an abnormality occurs while the vehicle is stopped, the current generation process can be realized by exchanging power with the charging equipment.

[0058] In the above embodiment, an example has been shown in which the electrically powered vehicle 1 is an electric vehicle (EV), but the power transmission system 20 of this embodiment may be mounted on an electrically powered vehicle such as an HEV (Hybrid Electric Vehicle), a PHEV (Plug-in Hybrid Electric Vehicle), etc. Other details shown in the embodiment can be modified as appropriate without departing from the spirit of the invention. [Industrial Applicability]

[0059] The present invention can be used in a power transmission system for an electric vehicle. [Explanation of symbols]

[0060] 1 Electric vehicles 2 drive wheels 11 Electrical Equipment 11a Electric motor 11b Inverter 12 Battery 20 Power Transmission System 21 Power intake section 22 Charger 23 First Power Line 24 Second Power Line 25a, 25b relay 26 Current Sensor 27 Voltage Sensor 28 Controller 29 Charge Controller 31 Current sensor 41 Charging equipment I1, I2 discharge current I3, I4 charging current

Claims

1. A power transmission system for an electric vehicle that is mounted on an electric vehicle having a battery that stores electric power for driving and an electric device that receives electric power from the battery, a power intake unit capable of taking in power from a charging facility provided outside the electric vehicle; a charger that charges the battery using power taken in via the power taking-in unit; a first power line for transmitting power between the electrical device and the battery; a second power line for transmitting power between the battery and the charger; a relay capable of disconnecting the first power line without disconnecting the second power line; a controller for controlling the relay; Equipped with the controller, when a request to turn off the relay based on an abnormality is made, turns off the relay after a current generation process; 10. A power transmission system for an electric vehicle, wherein the current generation process is a process of flowing a current between the charger and the battery in a direction that decreases the current in the relay.

2. 2. The power transmission system for an electric vehicle according to claim 1, wherein the current generation process further comprises a process of transmitting power between the battery and the charging facility via the power intake unit.

3. The abnormality includes a first abnormality in which a discharging current continues from the battery to the electric device, and a second abnormality in which a charging current continues from the electric device to the battery, The current generation process includes: a process of flowing a current in a direction in which power is sent from the battery to the charger when the first abnormality occurs; 2. The power transmission system for an electric vehicle according to claim 1, wherein, when the second abnormality occurs, a current is caused to flow in a direction that sends power from the charger to the battery.

4. 2. The power transmission system for an electric vehicle according to claim 1, wherein the controller suspends the current generation process when the voltage of the battery exceeds a first threshold during the current generation process.

5. 2. The power transmission system for an electric vehicle according to claim 1, wherein the controller suspends the current generation process when the voltage of the battery becomes lower than a second threshold during the current generation process.

6. 2. The power transmission system for an electric vehicle according to claim 1, wherein the power intake unit is configured to be able to transmit power contactlessly to the charging facility provided in a travel lane.

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