ENERGY STORAGE SYSTEM AND VEHICLE COMPRISING THE SAME

Abstract

Energy storage system comprising: an energy storage device (10); a relay device provided in a pair of power lines arranged between the power storage device (10) and a power conversion device (20) that exchanges power with the power storage device (10); a capacitor (55) provided between the pair of power lines between the relay device and the power conversion device (20); and an electronic control device (70) which controls the relay device, wherein: the relay device comprises a first relay (SMRB) provided in one of the pair of power lines, a second relay (SMRG) provided in the other of the pair of power lines, and a precharge circuit connected in parallel to the second relay (SMRG); the precharge circuit comprises a third relay (SMRP) and a limiting resistor (52) connected in series with the third relay (SMRP); the electronic control device (70) is configured to execute a predetermined processing for removing a foreign object (120) when it is not possible to bring one of the relays, the first relay (SMRB) or the second relay (SMRG), from a power interruption state to a conducting state; and the foreign matter removal processing (120) comprises processing for bringing the one relay other than the one of the relays that cannot be brought into the conductive state into the conductive state in a state where the first to third relays (SMRB, SMRG, SMRP) are in the power cut-off state, and then outputting a conduction command to the relay that cannot be brought into the conductive state.

Description

BACKGROUND OF THE INVENTION 1. Technical field

[0001] The present invention relates to an energy storage system or energy accumulation system and a vehicle having the same. 2. State of the art

[0002] Japanese Unexamined Patent Application Publication No. 2003-243049 (JP 2003-243049 A) ​​discloses a battery module (energy storage device) to be mounted on a vehicle. The battery module is provided with a relay capable of interrupting power (see JP 2003-243049 A).

[0003] DE 10 2006 000 144 A1 shows a circuit that includes, among other things, several relays, a capacitor, and the remaining features of the invention. However, this document only describes a method for detecting a connection fault in one of the relays, not the process for removing a foreign object.

[0004] US 2014 / 0 111 120 A1 also discloses a comparable switch design, whereby the switching sequence and welding of the relays are controlled. SUMMARY OF THE INVENTION

[0005] A high-capacity energy storage system to be mounted on a vehicle, etc., includes a relay (system main relay: SMR) arranged in a pair of power lines between an energy storage device and a load driving device (power conversion device). Generally, the SMR is provided with a precharge circuit to reduce an inrush current generated when the SMR is switched from a power-disconnected state (off state) to a conducting state (on state).

[0006] When the SMR is formed from a contact relay, a foreign matter or foreign material occasionally enters or penetrates the relay during manufacturing. The foreign matter that occasionally enters the relay moves and adheres to the surface of a contact point during use of the SMR, thus preventing the SMR from becoming conductive.

[0007] The present invention provides an energy storage system that can suppress or avoid the occurrence of a situation in which the SMR cannot be brought into the conductive state due to a foreign matter that has entered the SMR, and a vehicle having the same.

[0008] A first aspect of the present invention provides an energy storage system comprising: an energy storage device; a relay device provided in a pair of power lines arranged between the energy storage device and a power conversion device that exchanges power with the energy storage device; a capacitor provided between the pair of power lines, between the relay device and the power conversion device; and an electronic control device that controls the relay device. The relay device includes a first relay provided in one of the pair of power lines, a second relay provided in the other of the pair of power lines, and a precharge circuit connected in parallel with the second relay.The precharge circuit includes a third relay and a limiting resistor connected in series with the third relay. Both the first relay and the second relay are contact relays. The electronic control device is configured to execute predetermined processing for removing the foreign matter when it is not possible to bring one of the first and second relays from a power-off state to a conducting state. The foreign matter removal processing includes processing for bringing a relay, other than the one for which it is not possible to bring it into the conducting state, into the conducting state when the first to third relays are in the power-off state, and then issuing a conduction command to the relay for which it is not possible to bring it into the conducting state.

[0009] The energy storage system described above includes a precharge circuit. When the connection between the energy storage device and the energy conversion device is made conductive, both the first and second relays are typically made conductive after the voltage difference between the energy storage device and the capacitor is reduced by charging the capacitor, while the current is suppressed using the precharge circuit to reduce an inrush current from the energy storage device to the capacitor.

[0010] In the energy storage system, the foreign matter removal processing is performed when one of the first and second relays cannot be made conductive. In the foreign matter removal processing, a relay other than the one that cannot be made conductive is made conductive, and then a conduction command is issued to the relay that cannot be made conductive. As a result, a conduction command is issued to the relay that cannot be made conductive when the voltage difference between the energy storage device and the capacitor is large, so that it is possible to remove the foreign matter using the energy of an arc generated at a contact point of the relay.

[0011] The reason a relay cannot be switched on is not necessarily due to a foreign object. However, if such a cause is a foreign object, the foreign object can be removed. With the configuration described above, it is therefore possible to suppress or prevent a situation in which the first or second relay cannot be switched on due to a foreign object entering the relay.

[0012] According to the aspect described above, the electronic control device may be configured to execute pre-charge processing when the energy storage system is started, wherein the pre-charge processing includes processing for bringing the third relay into the conductive state after the first relay is brought into the conductive state and before the second relay is brought into the conductive state; and the electronic control device may be configured to execute the foreign object removal processing without executing the pre-charge processing when it is not possible to bring either of the first and second relays from the power cut-off state into the conductive state.

[0013] With the configuration described above, a conduction command is issued to the relay, which cannot be made conductive when the voltage difference between the energy storage device and the capacitor is large, so it may be possible to remove a foreign object using the energy of an arc generated at a contact point of the relay. With the configuration described above, it is therefore possible to suppress the occurrence of a situation in which the first or second relay cannot be made conductive due to an intruding foreign object.

[0014] In the above-described aspect, the electronic control device may be configured to perform pre-charge processing when the energy storage system is started, wherein the pre-charge processing includes processing for bringing the third relay into the conductive state after the first relay is brought into the conductive state and before the second relay is brought into the conductive state; the electronic control device may be configured to issue a conduction command to the second relay after a predetermined time has elapsed since the third relay is brought into the conductive state after the first relay is brought into the conductive state in the foreign matter removal processing when it is not possible to bring the second relay from the power cut-off state to the conductive state;and the predetermined time may be shorter than a precharge time since the third relay is brought into the conductive state until the second relay is brought into the conductive state during the precharge processing.;

[0015] With the configuration described above, the magnitude of the voltage difference between the energy storage device and the capacitor at the time a conduction command is issued to the second relay during the foreign object removal process can be adjusted by setting the predetermined time. In this way, a foreign object can be removed while simultaneously taking into account the damage that may be caused by the second relay during the foreign object removal process.

[0016] In the aspect described above, the electronic control device may be configured to execute pre-charge processing when the energy storage system is started, wherein the pre-charge processing includes processing for bringing the third relay into the conductive state after the first relay is brought into the conductive state and before the second relay is brought into the conductive state; the electronic control device may be configured to issue a conduction command to the second relay after the third relay is brought into the conductive state after the first relay is brought into the conductive state in the foreign matter removal processing when it is not possible to bring the second relay from the energy storage state to the conductive state;and a voltage difference between a voltage in the energy storage device and a voltage of the capacitor at a time when the conduction command is issued to the second relay in the foreign matter removal processing may be larger than the voltage difference at a time when the second relay is brought into the conducting state in the precharge processing;

[0017] With the configuration described above, the voltage difference between the energy storage device and the capacitor at the time the conduction command is issued to the second relay during the foreign matter removal processing is greater than the voltage difference at the time the second relay is placed in the conducting state during the precharge processing. Consequently, a foreign matter can be removed while taking into account damage that may be caused by the second relay during the foreign matter removal processing.

[0018] Furthermore, a second aspect of the present invention provides a vehicle comprising: the energy storage system; an energy conversion device that exchanges energy with the energy storage system; and an electric motor for traveling that receives energy from the energy conversion device to generate a driving force.

[0019] With the configuration described above, it is possible to suppress the occurrence of a situation in which the first or second relay cannot be made conductive due to a foreign matter entering the relay of the energy storage system. Thus, it is possible to suppress the occurrence of a situation in which the vehicle cannot be driven because the relay device cannot be made conductive and energy cannot be supplied from the energy storage device to the energy conversion device.

[0020] With the energy storage system according to the present invention, it is possible to suppress the occurrence of a situation in which the relay device cannot be made conductive due to a foreign object entering the relay of the device. Furthermore, with the vehicle according to the present invention, it is possible to suppress the occurrence of a situation in which the vehicle cannot drive. BRIEF DESCRIPTION OF THE CHARACTERS

[0021] Features, advantages and technical and industrial significance of exemplary embodiments of the invention are described below with reference to the accompanying figures, in which like reference numerals designate like elements, wherein: Fig. 1 schematically illustrates the configuration of a vehicle having an energy storage system according to a first embodiment of the present invention; Fig. Figure 2 shows an example of the configuration of a contact relay forming an SMR; Fig. 3 represents a state (conductive state) in which the relay is switched on; Fig. 4 illustrates a state in which a foreign matter adheres to the surface of a contact point of the relay; Fig. 5 shows how to remove a foreign body that has entered the relay; Fig. 6 is a flowchart showing an example of the flow of relay monitoring processing executed by an ECU; Fig. 7 is a flowchart showing an example of the flow of processing for removing the foreign matter by the relay executed in step S65 in Fig. 6 is executed; Fig. 8 is a timing chart showing the operation of relays at the time when the relays are normal; Fig. 9 is a timing chart illustrating the operation of the relays at the time the first abnormality flag is turned on; Fig. 10 is a timing chart illustrating the operation of the relays at the time a second abnormality flag is turned on; Fig. 11 is a flowchart showing an example of the flow of processing for removing the foreign matter by the relay according to a second embodiment; Fig. 12 is a timing chart illustrating the operation of relays at the time a second abnormality flag is turned on in the second embodiment; and Fig. 13 is a flowchart showing an example of the flow of processing for removing the foreign matter by the relay according to a modification. DETAILED DESCRIPTION OF EMBODIMENTS

[0022] Embodiments of the present invention will be described in detail below with reference to the figures. Like and equivalent parts are designated by like reference numerals throughout the figures, and repeated descriptions are omitted. [First embodiment]

[0023] Fig. 1 schematically illustrates the configuration of a vehicle having an energy storage system according to a first embodiment of the present invention. Hereinafter, the vehicle is an electric vehicle (EV) as a typical example. However, the energy storage system according to the present invention is not limited to being mounted on an EV, but can also be mounted on a hybrid vehicle (HV), a plug-in HV, etc., and is also applicable to uses other than vehicles.

[0024] A vehicle 1 has, as in Fig. 1, a power storage device 10, a power control unit (hereinafter referred to as "PCU") 20, a motor generator (hereinafter referred to as "MG") 30, a drive wheel 40(s), and a system main relay (SMR) 50. The vehicle 1 further includes a smoothing capacitor 55, a voltage sensor 60, a current sensor 62, an electronic control device (hereinafter referred to as "electronic control device (ECU)") 70, and a start switch (ST-SW) 80.

[0025] The energy storage device 10 is an energy storage element configured to be rechargeable. The energy storage device 10 is configured to include a secondary battery such as a lithium-ion battery or a nickel-metal hydride battery, or an energy storage element such as an electric double-layer capacitor. The lithium-ion secondary battery is a secondary battery that includes lithium as a charge carrier and may include conventional lithium-ion secondary batteries with a liquid electrolyte and so-called all-solid-state batteries with a solid electrolyte.

[0026] The energy storage device 10 stores the energy for driving the MG 30 and can supply energy to the MG 30 via the PCU 20. Furthermore, the energy storage device 10 is charged with the generated energy via the PCU 20 when the MG 30 generates power.

[0027] The PCU 20 performs bidirectional power conversion between the energy storage device 10 and the MG 30 according to a control signal from the ECU 70. The PCU 20 is configured to include an inverter that drives the MG 30 and a converter that boosts a direct current (DC) voltage supplied to the inverter to a voltage equal to or higher than the output voltage of the energy storage device 10.

[0028] The MG 30 is typically an alternating current (AC) rotating electric machine. Examples of the MG 30 include a three-phase AC synchronous motor in which permanent magnets are embedded in a rotor. The MG 30 is driven by the PCU 20 to generate a rotating drive force. The drive force generated by the MG 30 is transmitted to the drive wheel 40. On the other hand, when the vehicle 1 is decelerated or when the acceleration of the vehicle 1 is reduced on a downhill slope, the MG 30 operates as an electric generator to perform regenerative energy generation or recuperation. The energy generated by the MG 30 is supplied to the energy storage device 10 via the PCU 20.

[0029] The smoothing capacitor 55 is electrically connected between a positive pole line PL and a negative pole line NL and smoothes AC components of voltage fluctuations between the positive pole line PL and the negative pole line NL. The smoothing capacitor 55 can be present in the PCU 20.

[0030] The SMR 50 includes relays SMRB, SMRG, and SMRP, as well as a limiting resistor 52. The SMRB relay is provided in the positive pole line PL, which connects the positive pole of the energy storage device 10 to the PCU 20. The SMRG relay is arranged in the negative pole line NL, which is connected between the negative pole of the energy storage device 10 and the PCU 20. The SMRP relay and the limiting resistor 52 are connected in series and in parallel with the SMRG relay.

[0031] In the present first embodiment, each of the relays is configured as a contact relay (mechanical relay). The SMRP relay may be a contactless relay (semiconductor relay). Each of the relays is turned on and off in response to a control signal from the ECU 70.

[0032] The SMRP relay and the limiting resistor 52 form a precharge circuit that reduces the inrush current flowing when the SMR 50 is turned on. That is, when the SMR 50 is to be turned on, the SMRP relay is turned on after the SMRB relay is turned on and before the SMRG relay is turned on, and the smoothing capacitor 55 is precharged while the limiting resistor 52 limits the current. This reduces the inrush current flowing from the energy storage device 10 to the smoothing capacitor 55 when the SMR 50 is turned on.

[0033] The voltage sensor 60 detects a voltage between the terminals of the smoothing capacitor 55, that is, a voltage VH between the positive terminal line PL and the negative terminal line NL, and outputs it to the ECU 70. The current sensor 62 detects a current IB input to and output from the energy storage device 10 and outputs a detected value to the ECU 70. For example, the current sensor 62 detects a discharge current as a positive value and a charge current as a negative value.

[0034] The start switch 80 can be operated by a driver of the vehicle 1. The system of the vehicle 1 is started (Ready-ON) by the driver performing an activation operation on the start switch 80 (e.g., by pressing it in the Ready-OFF state). In contrast, the system of the vehicle 1 is stopped (Ready-OFF) by the driver performing an activation operation on the start switch 80 (e.g., by pressing it in the Ready-ON state).

[0035] The ECU 70 is configured to include a central processing unit (CPU), memories (a read-only memory (ROM) and a random access memory (RAM)), and input and output ports for inputting and outputting various signals (all of which are not shown). The CPU develops or compiles a program stored in the ROM or RAM, etc., and executes the program. The program stored in the ROM includes processing to be executed by the CPU. The ECU 70 controls various devices in the vehicle 1 by executing the processing included in the program. Part or all of the control device is not limited to processing using software and may be processed using dedicated hardware (electronic circuit).

[0036] In an example of the main processing executed by the ECU 70, when the start switch 80 is turned on, the ECU 70 executes processing (start processing) to bring the vehicle 1 into the ready-on state, thereby turning on the SMR 50. When the start switch 80 is turned off, the ECU 70 executes processing (stop processing) to bring the vehicle 1 into the ready-off state, thereby turning off the SMR 50.

[0037] Further, the ECU 70 executes relay monitoring processing for monitoring an abnormality of the SMR 50. In the first embodiment, the ECU 70 executes the relay monitoring processing when the SMR 50 is turned on. If an abnormality is detected in the relay monitoring processing that does not turn on the SMR 50, the energy storage system according to the present first embodiment executes processing for removing the foreign matter that may have entered a relay, considering the possibility that a foreign matter has entered the SMRB relay or the SMRG relay and thus the relay is not brought into the conductive state. The intrusion of a foreign matter and the method for removing the foreign matter will be described in detail below.

[0038] Fig. Figure 2 shows an example of the configuration of a contact relay constituting the SMR 50. In the present first embodiment, the relays SMRB, SMRG, and SMRP have the same configuration. Fig. 2 and in the Fig. In relays 3 to 5, which are described later, the relays are plunger contact relays. However, the relays can also be hinge contact relays. Fig. 2 represents a state in which the relay is off (power interruption state).

[0039] In Fig. 2, the relay is configured to include a housing 102, a coil 104, a plunger portion 106, a movable contact point 108, and terminals 110 and 112. The coil 104 generates an electromagnetic force to move the plunger portion 106 upward when an external current is applied.

[0040] The plunger portion 106 is configured to be movable upward by the electromagnetic force received from the coil 104 and to be pushed downward by the biasing force of a spring when the electromagnetic force is not received from the coil 104. The movable contact point 108 is made of a conductor and is configured to be movable up and down together with the plunger portion 106.

[0041] When a current flows through the coil 104, the plunger portion 106 is moved upward by the electromagnetic force, and the movable contact point 108 contacts the fixed contact points 111 and 113 of the terminals 110 and 112, respectively. When no current flows through the coil 104, the plunger portion 106 is moved downward by the biasing force of the spring, and the movable contact point 108 is brought out of contact with or away from the fixed contact points 111 and 113.

[0042] In Fig. 2, no current is supplied to the coil 104, the plunger portion 106 is pressed downward, and the movable contact point 108 is away from the fixed contact points 111 and 113 of the terminals 110 and 112 (non-conductive state).

[0043] Fig. 3 represents a state (conductive state) in which the relay is switched on. A current flows in Fig. 3 by the coil 104, and the plunger portion 106 is moved upward by the electromagnetic force received from the coil 104. This allows the movable contact point 108 to contact the fixed contact points 111 and 113, and the terminals 110 and 112 are continuous through the movable contact point 108 (on state and on state, respectively).

[0044] Fig. 4 represents a condition in which a foreign matter adheres to the surface of a contact point of the relay. A current flows in Fig. 4 by the coil 104, and the plunger portion 106 is moved upward by the electromagnetic force received from the coil 104. However, in this example, a foreign matter 120 has entered a space between the movable contact point 108 and the fixed contact point 111 of the terminal 110, and the movable contact point 108 does not contact the fixed contact points 111 and 113. Consequently, the terminals 110 and 112 are not connected through the movable contact point 108.

[0045] In this way, during manufacturing, a foreign body (e.g., resin foreign body) occasionally penetrates into a contact relay. The occasionally penetrated foreign body moves and adheres to the surface of a contact point with the use of the relay, so that, as shown in Fig. 4, it can be prevented that the relay is brought into the conductive state.

[0046] Fig. Figure 5 shows how to remove the foreign body that has penetrated the relay. Fig. 5, the energy storage system according to the first embodiment performs processing for removing the foreign matter when the relay is triggered due to the intrusion of a foreign matter as shown in Fig. 4, is not brought into the conductive state (on state). A foreign matter can be removed from the SMRB and SMRG relays by the foreign matter removal processing. A foreign matter cannot be removed from the SMRP relay by the method described below, and there is no effect on driving if the SMRP relay is not turned on as long as the SMRB and SMRG relays are turned on. Therefore, the SMRP relay is not subjected to the foreign matter removal processing according to the present first embodiment.

[0047] In the foreign matter removal processing according to the present first embodiment, a relay other than the one among the SMRB and SMRG relays that cannot be made conductive is turned on, and then a turn-on command is issued to the relay that cannot be made conductive. When it is detected that the SMRB relay cannot be made conductive, for example, the SMRG relay turns on, and then an turn-on command is issued to the SMRB relay.

[0048] When the SMRB and SMRG relays are to be turned on, both SMRB and SMRG relays are normally turned on after the voltage difference between the energy storage device 10 and the smoothing capacitor 55 is reduced by a circuit that performs precharge processing to reduce an inrush current. In contrast, in the above-described foreign matter removal processing, when the voltage difference between the energy storage device 10 and the smoothing capacitor 55 is large, an ON command is issued to the relay that cannot be turned on (the SMRB relay in the above-described example). This may make it possible to remove a foreign matter using the energy of an arc generated at a contact point of the relay.

[0049] The reason a relay cannot be switched into the conductive state is not necessarily due to a foreign object. However, if such a cause is a foreign object, the foreign object can be removed. This makes it possible to prevent a situation in which the SMRB or SMRG relay cannot be switched into the conductive state due to the ingress of a foreign object.

[0050] Fig. 6 is a flowchart illustrating an example of the flow of relay monitoring processing executed by the ECU 70. The foreign object removal processing described above is executed based on the result of the relay monitoring processing regarding the presence or absence of an abnormality in the relays. The sequence of processing or steps indicated in the flowchart is executed at the time the start switch 80 is turned on (when the vehicle system is started).

[0051] If, as in Fig. 1 and in Fig. 6, a power-on operation is performed on the start switch 80, the ECU 70 first issues a power-on command to the SMRB relay (step S10). Next, the ECU 70 issues a power-on command to the SMRP relay (step S15). Consequently, precharge processing is executed in which the smoothing capacitor 55 is charged with a current limited by the limiting resistor 52.

[0052] Next, the ECU 70 acquires a detected value of the voltage VH from the voltage sensor 60 and acquires a detected value of the current IB from the current sensor 62 (step S20). Then, after waiting a predetermined time (step S25), the ECU 70 determines whether the voltage VH is less than a threshold value Vth (step S30). This processing is performed to detect an abnormality in which the contact points of the SMRB relay (or the SMRP relay) are not continuous. The threshold value Vth is set, if necessary, to a value less than the value of the voltage VH to which the voltage VH normally rises after the predetermined time elapses since the SMRB or SMRP relay transitions to the conductive state.

[0053] Instead of determining whether the voltage VH is less than the threshold Vth, it can be determined whether the current IB is less than a threshold Ith. It is also possible to detect an abnormality in which the contact points of the SMRB relay (or the SMRP relay) are not continuous according to the magnitude of the current IB.

[0054] If it is determined in step S30 that the voltage VH is equal to or greater than the threshold value Vth (NO in step S30), it is determined that the relays SMRB and SMRP are normal, and the ECU 70 issues an on command to the relay SMRG (step S35). Subsequently, the ECU 70 issues an off command to the relay SMRP (step S40).

[0055] Then, after waiting a predetermined time (step S45), the ECU 70 again determines whether the voltage VH is less than the threshold value Vth (step S50). This processing is performed to detect an abnormality in which the contact points of the relay SMRG are not continuous. That is, when the contact points of the relay SMRG are not continuous, the circuit of the energy storage device 10 and the smoothing capacitor 55 is broken when the relay SMRP is turned off, and the voltage VH of the smoothing capacitor 55 is lowered by a discharge resistor (not shown).

[0056] Here, too, instead of determining whether the voltage VH is less than the threshold Vth, it can be determined whether the current IB is less than the threshold Ith. It is also possible to detect an abnormality in which the contact points of the SMRG relay are not continuous according to the magnitude of the current IB.

[0057] If it is determined in step S50 that the voltage VH is equal to or greater than the threshold value Vth (NO in step S50), it is determined that the relay SMRG is also normal, and the steps of the processing are ended.

[0058] On the other hand, if it is determined in step S30 that the voltage VH is below the threshold value Vth (YES in step S30), the ECU 70 turns on a first abnormality flag indicating that the relay SMRB or the relay SMRP is abnormal (the contact points of the relay are not continuous even when an ON command is issued) (step S55). Then, the ECU 70 executes processing to remove, through the relay, the foreign matter that may have entered the relay SMRB and blocked the continuity between the contact points of the relay SMRB (step S65).

[0059] It is also conceivable that the voltage VH is lower than the threshold Vth because the contact points of the SMRP relay are not continuous. However, since the intrusion of the foreign object into the SMRB relay cannot be ruled out, processing to remove the foreign object that may have entered the SMRB relay is executed when it is determined that the voltage VH is lower than the threshold Vth. The processing to remove the foreign object by the relay will be described in detail later.

[0060] On the other hand, if it is determined in step S50 that the voltage VH is less than the threshold value Vth (YES in step S50), the ECU 70 turns on a second abnormality flag indicating that the relay SMRG is abnormal (the contact points of the relay are not continuous even when an ON command is issued) (step S60). Then, the processing proceeds to step S65, and the ECU 70 executes processing to remove the foreign matter that may have entered the relay SMRG and blocked the continuity between the contact points of the relay SMRG, through the relay.

[0061] Fig. Fig. 7 is a flowchart showing an example of the flow of processing for removing the foreign matter by the relay executed in step S65 in Fig. 6 is executed. In Fig. 7, the ECU 70 determines whether the first abnormality flag is on (step S110). If it is determined that the first abnormality flag is off (NO in step S110), processing proceeds to step S130, which will be discussed later.

[0062] If it is determined in step S110 that the first abnormality flag is on (YES in step S110), the ECU 70 turns off the SMRB and SMRP relays that were on at that time (step S115). On the other hand, the ECU 70 turns on the SMRG relay located on the opposite side of the SMRB relay, into which a foreign object may have entered (step S120).

[0063] After turning on the SMRG relay, the ECU 70 then issues an ON command to the SMRB relay that may have a foreign matter intruding (step S125). That is, when turning on the SMRB and SMRG relays, pre-charge processing is normally performed, in which, as described in relation to Fig. 6, the SMRP relay (pre-charge circuit) is used. However, during the foreign matter removal processing, an ON command is issued to the SMRB relay, into which the foreign matter may have entered, after the SMRG relay is turned on without executing the pre-charge processing.

[0064] At this time, since the precharge processing is not executed before issuing an ON command to the SMRB relay, an ON command is issued to the SMRB relay when the voltage difference between the energy storage device 10 and the smoothing capacitor 55 is large. This may make it possible to remove a foreign matter using the energy of an arc generated at a contact point of the SMRB relay when a foreign matter adheres to the surface of the contact point of the SMRB relay.

[0065] On the other hand, if the determination result in step S110 is NO, the ECU 70 determines whether a second abnormality flag is on (step S130). If it is determined that the second abnormality flag is off (NO in step S130), the processing returns.

[0066] If it is determined in step S130 that the second abnormality flag is on (YES in step S130), the ECU 70 turns off the SMRB and SMRG relays that were on at that time (step S135). Next, the ECU 70 turns on the SMRB relay located on the opposite side of the SMRG relay, into which a foreign object may have entered (step S140).

[0067] After turning on the SMRB relay, the ECU 70 then issues an ON command to the SMRG relay into which a foreign matter may have entered (step S145). That is, even if the second abnormality flag is turned on, as well as the first abnormality flag, an ON command is output to the SMRG relay into which a foreign matter may have entered after the SMRB relay is turned on without executing the precharge processing. This may make it possible to remove a foreign matter using the energy of an arc generated at a contact point of the SMRG relay when a foreign matter adheres to the surface of the contact point of the SMRG relay.

[0068] The Fig. Figures 8 to 10 are each a timing diagram showing the operation of the relays SMRB, SMRP and SMRG chronologically. Fig. Figure 8 is a timing chart showing the operation of the relays at the time when the relays are normal.

[0069] In Fig. 8, when a power-on operation is performed on the start switch 80 at time t1, the SMRB relay is turned on at time t2 and the SMRP relay is turned on at time t3. Precharge processing is executed when the SMRP relay is turned on.

[0070] At time t4, when a predetermined time Δtp1 has elapsed since time t3, the voltage VH is equal to or greater than the threshold Vth (not shown), and thus the relay SMRG is turned on. After that, the relay SMRP of the precharge circuit is turned off at time t5. Consequently, the relays SMRB and SMRG are turned on along with the precharge processing when the start switch 80 is turned on.

[0071] When the start switch 80 is turned off, relay welding is checked. That is, when the start switch 80 is turned off at time t6, the SMRG relay is turned off at time t7. At this time, it is determined whether the SMRG relay is welded (connected) if the voltage VH is not lowered.

[0072] If the voltage VH drops while the SMRG relay is turned off at time t7, the SMRB relay turns off at time t8. Then, the SMRP relay turns on at time t9. If the voltage VH increases at this time, it is determined that the SMRB relay is welded (joined). After that, the SMRP relay turns off at time t10.

[0073] Fig. Figure 9 is a timing chart showing the operation of the relays at the time the first abnormality flag is turned on. That is, Fig. Figure 9 shows the operation of the relays at the time when a foreign object may have entered the SMRB relay.

[0074] If, as in Fig. 9, at time t11 a switch-on operation is performed on the start switch 80, the relay SMRB is switched on at time t12 and the relay SMRP is switched on at time t13. The operation described so far is the same as that in Fig. 8 shows operation at normal times.

[0075] Despite the fact that the SMRP relay is turned on at time t13, the voltage VH is lower than the threshold Vth (not shown) even after a predetermined time has elapsed, and consequently, the first abnormality flag is turned on at time t14. Consequently, the processing for removing the foreign object that may have entered the SMRB relay is executed.

[0076] That is, the SMRB and SMRP relays that were turned on are temporarily turned off at time t15. Then, after the SMRG relay is turned on at time t16, an on command is issued to the SMRB relay at time t17. Since the smoothing capacitor 55 is not precharged at this time, the voltage difference between the energy storage device 10 and the smoothing capacitor 55 is large, and an arc is generated on the surface of a contact point when the SMRB relay is turned on. In this example, the SMRB relay is turned on, and a foreign matter adhering to the contact point surface of the SMRB relay is removed by the arc generated on the contact point surface.

[0077] Fig. Figure 10 is a timing chart showing the operation of the relays at the time the second abnormality flag is turned on. That is, Fig. Figure 10 shows the operation of the relays at the time when a foreign object may have entered the SMRG relay.

[0078] If, how Fig. As shown in Figure 10, when a power-on operation is performed on the start switch 80 at time t21, the SMRB relay is turned on at time t22 and the SMRP relay is turned on at time t23. Precharge processing is executed when the SMRP relay is turned on.

[0079] At time t24, when a predetermined time Δtp1 has elapsed since time t23, the voltage VH is equal to or greater than the threshold value Vth (not shown), and thus the relay SMRG is turned on. After that, the relay SMRP of the precharge circuit is turned off at time t25. The operation described so far is the same as that in Fig. 8 shows operation at normal times.

[0080] In this example, after the SMRP relay is turned off at time t25, the voltage VH becomes lower than the threshold Vth (not shown), and thus the second abnormality flag is turned on at time t26. Consequently, the processing for removing the foreign matter that may have entered the SMRG relay is executed.

[0081] That is, the SMRB and SMRG relays, which were turned on, are temporarily turned off at time t27. Then, after the SMRB relay is turned on at time t28, an on command is issued to the SMRG relay at time t29. The voltage VH has become lower than the threshold Vth because the SMRP relay is turned off at time t25. Since the smoothing capacitor 55 is not precharged again at time t29, the voltage difference between the energy storage device 10 and the smoothing capacitor 55 is large, and an arc is generated on the surface of a contact point when the SMRG relay is turned on. In this example, the SMRG relay is turned on, and a foreign matter adhering to the contact surface of the SMRG relay is removed by the arc generated on the contact surface.

[0082] In the first embodiment described above, the foreign matter removal processing is executed when the SMR 50 is not brought into the conductive state. In the foreign matter removal processing, a relay other than the one among the SMRB and SMRG relays that cannot be brought into the conductive state is brought into the conductive state, and thereafter, an ON command is issued to the relay that cannot be brought into the conductive state without executing the precharge processing. As a result, a conduction command is issued to the relay that cannot be brought into the conductive state when the voltage difference between the energy storage device 10 and the smoothing capacitor 55 is large, whereby it may be possible to remove foreign matter using the energy of an arc generated at the contact point of the relay. [Second embodiment]

[0083] In the first embodiment described above, a foreign object that may have entered the SMRB relay or the SMRG relay is removed by an arc generated when the relay is turned on, by turning on the SMRB or SMRG relay when precharge processing is not being executed. In a second embodiment, when the possibility of a foreign object entering the SMRG relay to which the precharge circuit is connected in parallel is detected, precharge processing is executed for a shorter (adjustable) time than at the time of normal execution (when the relays are normal).This makes it possible to adjust the magnitude of the voltage difference between the energy storage device 10 and the smoothing capacitor 55 at the time of executing the foreign matter removal processing and to remove the foreign matter in consideration of damage that may be caused by the relay SMRG during the foreign matter removal processing.

[0084] The energy storage system according to the second embodiment is different from the energy storage system described with reference to the first embodiment in terms of the content of the processing for removing the foreign matter by the relay.

[0085] Fig. Fig. 11 is a flowchart showing an example of the flow of processing for removing the foreign matter by the relay according to the second embodiment. This flowchart corresponds to the flowchart described with reference to Fig. 7 in the first embodiment described above.

[0086] In Fig. 11, the processings in steps S210 to S240 are the same as the processings in steps S110 to S140 shown in Fig. 7. When it is determined in step S230 that the second abnormality flag is on, and the relay SMRB is turned on in step S240, the ECU 70 turns on the relay SMRP (step S245).

[0087] Next, the ECU 70 determines whether a time Δtp2 has elapsed since the SMRP relay was turned on (step S250). The time Δtp2 is shorter than the precharge time in the normal precharge processing (specified time in step S25 in Fig. 6) and is determined, if necessary, taking into account the voltage difference between the energy storage device 10 and the smoothing capacitor 55 required to remove a foreign body and damage to the SMRG relay from which a foreign body is to be removed.

[0088] When the time Δtp2 has elapsed since the SMRP relay was turned on in step S250 (YES in step S250), the ECU 70 issues an ON command to the SMRG relay for which the possibility of foreign matter intrusion is detected (step S255). Therefore, when a foreign matter adheres to the surface of a contact point of the SMRG relay, it may be possible to remove the foreign matter using the energy of an arc generated at the contact point of the SMRG relay, taking into account damage to the SMRG relay, which is turned on when the voltage difference between the energy storage device 10 and the smoothing capacitor 55 is large.

[0089] Fig. 12 is a timing chart illustrating the operation of the relays at the time of turning on the second abnormality flag in the second embodiment. Fig. 12 corresponds to Fig. 10, which was described with reference to the first embodiment.

[0090] As in Fig. 12, the operation of the relays at times t31 to t38 corresponds to that shown in Fig. 10 shows the operation of the relays at times t21 to t28.

[0091] When the SMRB relay is turned on again at time t38, the SMRP relay is turned on at time t39. Thus, precharge processing is started. Then, at time t40, when a predetermined time Δtp2 (Δtp2 < Δtp1) has elapsed since time t39, an ON command is issued to the SMRG relay. Thus, in this example, the SMRG relay is turned on, and a foreign matter adhering to the contact point surface of the SMRG relay is removed by the arc generated on the contact point surface when the SMRG relay is turned on. After that, the SMRP relay is turned off at time t41.

[0092] With the second embodiment described above, the magnitude of the voltage difference between the energy storage device 10 and the smoothing capacitor 55 at the time of issuing an ON command to the SMRG relay during the foreign matter removal processing can be adjusted by setting the predetermined time Δtp2 (Δtp2 < Δtp1) when the possibility of a foreign matter entering the SMRG relay is detected. In this way, a foreign matter can be removed while taking into account the damage that may occur to the SMRG relay during the foreign matter removal processing. [Modification]

[0093] In the second embodiment described above, when the second abnormality flag is turned on (when an abnormality of the relay SMRG is detected), the time (predetermined time Δtp2) from the time the relay SMRP is turned on until the relay SMRG is turned on is monitored to perform precharge processing for a shorter time than at normal times. However, instead of the time, the voltage difference between the energy storage device 10 and the smoothing capacitor 55 may also be monitored. That is, when the above-described voltage difference is large compared to the precharge processing at normal times (at the time when the relays are normal), the precharge processing is terminated and the relay SMRG is turned on.In this way, it is possible to directly adjust the magnitude of the voltage difference between the energy storage device 10 and the smoothing capacitor 55 at the time of performing the foreign matter removal processing, and to remove a foreign matter in consideration of the damage that may be caused to the relay SMRG during the foreign matter removal processing.

[0094] Fig. Figure 13 is a flowchart showing an example of the flow of processing for removing the foreign object by the relay according to a modification. This flowchart corresponds to the flowchart in Fig. 11 for the second embodiment described above.

[0095] The processings in steps S310 to S345 and S355, except for step S350, are as shown in Fig. 13, the same as the processings in steps S210 to S245 and S255 shown in Fig.11. When the relay SMRP is turned on in step S345, the ECU 70 determines whether the voltage difference between a voltage VB indicative of the voltage of the power storage device 10 and the voltage VH is smaller than a threshold ΔVth (step S350). The threshold ΔVth is greater than the voltage difference at the time of completion of the normal precharge processing and is appropriately determined by taking into account the voltage difference between the power storage device 10 and the smoothing capacitor 55 required to remove foreign matter and damage to the relay SMRG from which a foreign matter is to be removed, if necessary. The voltage VB is detected by a voltage sensor (not shown) that detects the voltage of the power storage device 10.

[0096] When the voltage difference between the voltage VB of the energy storage device 10 and the voltage VH is smaller than the threshold ΔVth in step S350 (YES in step S350), the processing goes to step S355, and the ECU 70 outputs an ON command to the relay SMRG for which the possibility of intrusion of a foreign matter is detected.

[0097] The modification also allows for the removal of foreign bodies, as described above, taking into account any damage that may occur to the SMRG relay during processing to remove the foreign body.

[0098] In the embodiments described above, the precharge circuit including relay SMRP and limiting resistor 52 is provided in parallel with relay SMRG. However, the precharge circuit may be provided in parallel with relay SMRB. In this case, the various processing and operation of the relays may be described by replacing relay SMRB with relay SMRG in the description of the above embodiments.

Claims

[1] Energy storage system comprising: an energy storage device (10); a relay device provided in a pair of power lines arranged between the power storage device (10) and a power conversion device (20) that exchanges power with the power storage device (10); a capacitor (55) provided between the pair of power lines between the relay device and the power conversion device (20); and an electronic control device (70) which controls the relay device, wherein: the relay device comprises a first relay (SMRB) provided in one of the pair of power lines, a second relay (SMRG) provided in the other of the pair of power lines, and a precharge circuit connected in parallel to the second relay (SMRG); the precharge circuit comprises a third relay (SMRP) and a limiting resistor (52) connected in series with the third relay (SMRP); the electronic control device (70) is configured to execute a predetermined processing for removing a foreign object (120) when it is not possible to bring one of the relays, the first relay (SMRB) or the second relay (SMRG), from a power interruption state to a conducting state; and the foreign matter removal processing (120) comprises processing for bringing the one relay other than the one of the relays that cannot be brought into the conductive state into the conductive state in a state where the first to third relays (SMRB, SMRG, SMRP) are in the power cut-off state, and then outputting a conduction command to the relay that cannot be brought into the conductive state. [2] Energy storage system according to claim 1, wherein: the electronic control device (70) is configured to perform pre-charge processing when the energy storage system is started, wherein the pre-charge processing comprises processing for bringing the third relay (SMRP) into the conductive state after the first relay (SMRB) is brought into the conductive state and before the second relay (SMRG) is brought into the conductive state; and the electronic control device (70) is configured to execute the processing for removing the foreign object (120) without executing the precharge processing when it is not possible to bring one of the relays, first relay (SMRB) and second relay (SMRG), from the power cut-off state to the conducting state. [3] Energy storage system according to claim 1, wherein: the electronic control device (70) is configured to perform pre-charge processing when the energy storage system is started, wherein the pre-charge processing comprises processing for bringing the third relay (SMRP) into the conductive state after the first relay (SMRB) is brought into the conductive state and before the second relay (SMRG) is brought into the conductive state; and the electronic control device (70) is configured to issue a conduction command to the second relay (SMRG) after a predetermined time (Δtp2) has elapsed since the third relay (SMRP) is brought into the conducting state after the first relay (SMRB) is brought into the conducting state in the processing for removing the foreign matter (120), when it is not possible to bring the second relay (SMRG) from the power cut-off state into the conducting state; and the predetermined time (Δtp2) is shorter than a precharge time (Δtp1) since the third relay (SMRP) is brought into the conductive state until the second relay (SMRG) is brought into the conductive state during the precharge processing. [4] Energy storage system according to claim 1, wherein: the electronic control device (70) is configured to execute pre-charge processing when the energy storage system is started, the pre-charge processing comprising processing for bringing the third relay (SMRP) into the conductive state after the first relay (SMRB) is brought into the conductive state and before the second relay (SMRG) is brought into the conductive state; the electronic control device (70) is configured to issue a conduction command to the second relay (SMRG) after the third relay (SMRP) has been brought into the conducting state after the first relay (SMRB) has been brought into the conducting state in the processing for removing the foreign object (120), if it is not possible to bring the second relay (SMRG) from the power interruption state into the conducting state; and a voltage difference between a voltage of the energy storage device (10) and a voltage of the capacitor (55) at a time when the conduction command is issued to the second relay (SMRG) in the foreign matter removal processing (120) is greater than the voltage difference at a time when the second relay (SMRG) is brought into the conducting state in the precharge processing. [5] Vehicle (1) which has: the energy storage system according to one of claims 1 to 4; an energy conversion device (20) that exchanges energy with the energy storage system; and an electric motor (30) for driving, which receives energy from the energy conversion device (20) to generate a driving force.

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