Relay drive control device, control method, and control program

Abstract

To provide a relay derive controller capable of driving a relay, while suppressing an increase in cost and scale (size and weight).SOLUTION: A relay derive controller for connecting a battery installed in a vehicle with an external power supply comprises a voltage conversion part for converting an output voltage into a drive voltage to be output to a control part by inputting the output voltage from the battery, and the control part for supplying the drive voltage input from the voltage conversion part to the relay. The control part controls the voltage conversion part so as to raise the drive voltage up to a first voltage value that is relay-drivable when driving the relay, and supplies the drive voltage to the relay when the drive voltage reaches the first voltage value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a relay drive control device that controls the drive of a relay for connecting a battery mounted in a vehicle to an external power source. [Background technology]

[0002] Patent Document 1 discloses an energy storage system including an energy storage device composed of multiple single cells connected in series, a relay that switches between a connection / disconnection state between the energy storage device and a load, and a controller that controls the driving of the relay by energizing / de-energizing a coil section. In this energy storage system, the controller dynamically controls the voltage supplied to the coil section based on the state of the relay to appropriately drive the relay. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-079121 A Summary of the Invention [Problem to be solved by the invention]

[0004] The power storage system described in Patent Document 1 requires a temperature sensor for deriving a drive voltage according to the state of the relay in order to drive the relay, and a number of switches for extracting the derived drive voltage from a power storage device made up of a number of unit cells connected in series, etc. This poses a problem in that the cost and scale (size and weight) of the power storage system are large.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a relay drive control device and the like that can drive a relay while suppressing increases in cost and scale (size, weight). [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the disclosed technology is a relay drive control device that controls the drive of a relay for connecting a battery mounted in a vehicle to an external power source, and includes a voltage conversion unit that inputs an output voltage from the battery, converts the output voltage into a drive voltage, and outputs it to a control unit, and a control unit that supplies the drive voltage input from the voltage conversion unit to the relay, wherein, when driving the relay, the control unit controls the voltage conversion unit to increase the drive voltage to a first voltage value at which the relay can be driven, and supplies the drive voltage to the relay when the drive voltage reaches the first voltage value. Effect of the Invention

[0007] According to the relay drive control device and the like disclosed herein, the voltage for driving the relay is controlled using an existing device configuration, so that the relay can be driven suitably while suppressing an increase in the cost and scale (size, weight) of the device. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a functional block diagram of a relay drive control device according to an embodiment of the present disclosure and its peripheral components; [Diagram 2] Processing flowchart of DC charging control executed by the relay drive control device [Diagram 3] A process flowchart of relay drive control executed by the relay drive control device [Figure 4] A process flowchart of relay diagnosis control executed by the relay drive control device [Diagram 5] Processing flow chart for positive side DC relay stuck-close diagnosis [Figure 6] Processing flow chart for negative DC relay stuck-close diagnosis DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] When an external power source is used to charge an on-board battery, the relay drive control device of the present disclosure controls the voltage for driving a charging relay that switches the charging ON / OFF state to a voltage value that allows the relay to be driven even at high temperatures. This control allows the charging relay to be driven appropriately. Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0010] <Embodiment> [composition] Fig. 1 is a functional block diagram of a relay drive control device 10 and its peripheral parts according to an embodiment of the present disclosure. The functional blocks illustrated in Fig. 1 include the relay drive control device 10, a drive battery 20, a charge relay (CHR) 30, and a plug connection unit 40. In Fig. 1, connection lines primarily intended for power supply are indicated by thick solid lines, connection lines primarily intended for voltage supply are indicated by thin solid lines, and connection lines for control are indicated by dashed lines.

[0011] The relay drive control device 10, the driving battery 20, the charge relay 30, and the plug connection unit 40 are mounted on a vehicle (electric vehicle) such as a plug-in hybrid vehicle (PHEV) or an electric vehicle (BEV) that uses an electric motor as a power source and is capable of charging the battery using an external power source 50. A vehicle equipped with this relay drive control device 10, the driving battery 20, the charge relay 30, and the plug connection unit 40 can connect the external power source 50 to the plug connection unit 40 via a charging cable 51. The external power source 50 described in this embodiment is an external charging facility for supplying direct current (DC) power to the vehicle.

[0012] The drive battery 20 is a secondary battery, such as a lithium ion battery, configured to be chargeable and dischargeable, and is a high-voltage battery that supplies power to so-called main engines (not shown) such as a starter motor and an electric motor for driving mounted on the vehicle. The drive battery 20 can receive (be charged with) power from an external power source 50 via a charge relay 30 and a plug connection unit 40. The drive battery 20 can also supply power to the relay drive control device 10 via a system main relay (SMR) not shown.

[0013] The charge relay (CHR) 30 is a switch element provided between the drive battery 20 and the plug connection unit 40, and controls connection / disconnection of a power path (power path) for charging the drive battery 20 using an external power source 50. The charge relay 30 is composed of a DC relay 31 (hereinafter referred to as the "positive side DC relay 31") inserted in a power line on the positive (+) side of the power path, and a DC relay 32 (hereinafter referred to as the "negative side DC relay 32") inserted in a power line on the negative (-) side of the power path. The positive side DC relay 31 and the negative side DC relay 32 can independently switch between a drive state (ON operation) in which the terminals are electrically connected and an open state (OFF operation) in which the terminals are electrically disconnected, based on a drive voltage supplied from a control unit 12 of a relay drive control device 10 described later. The positive side DC relay 31 and the negative side DC relay 32 can be mechanical relays that apply a voltage to a coil portion to pass a current and thereby make a contact portion conductive. In the following description, when the positive side DC relay 31 and the negative side DC relay 32 are linked and controlled to the same operating state, this is expressed as the operating state of the charge relay 30.

[0014] The plug connection unit 40 is an electric power interface for connecting the vehicle to an external power source 50 via a charging cable 51. When the vehicle is connected to the external power source 50 via the charging cable 51, the driving battery 20 is charged with electric power supplied from the external power source 50 while the charge relay 30 is in a driven state.

[0015] The relay drive control device 10 is a device for controlling the charge relay 30 to control charging of the drive battery 20. In addition, this relay drive control device 10 can control the power balance of the drive battery 20 and an auxiliary battery (not shown) that supplies power to the auxiliary devices (not shown). The relay drive control device 10 according to this embodiment includes a voltage conversion unit 11, a control unit 12, and a voltage detection unit 13.

[0016] The voltage conversion unit 11 generates a drive voltage for driving the charge relay 30 based on the output voltage of the drive battery 20, and supplies the generated drive voltage to the control unit 12. That is, the voltage conversion unit 11 functions as a power converter that converts power having a battery-prescribed voltage stored in the drive battery 20 into power having a drive voltage. This voltage conversion unit 11 is typically configured with a DC-DC converter, and can generate a drive voltage of a voltage value instructed by the control unit 12 and output it to the control unit 12. In addition, the voltage conversion unit 11 can convert the power stored in the drive battery 20, etc., into power having a predetermined voltage and supply it to the auxiliary equipment or the auxiliary equipment battery.

[0017] The control unit 12 controls the start / end of charging of the driving battery 20 by switching the operating state of the charge relay 30 using the power of the driving voltage supplied from the voltage conversion unit 11 based on the state of the driving battery 20 and the voltage conversion unit 11 and the output end voltage of the charge relay 30 detected by the voltage detection unit 13. This control unit 12 can acquire the state of the driving battery 20 (voltage, current, temperature, etc.) from the functional unit or system that controls the driving battery 20. Furthermore, the control unit 12 can instruct the voltage conversion unit 11 to increase / maintain / decrease the voltage value of the driving voltage input from the voltage conversion unit 11. Furthermore, the control unit 12 can diagnose abnormalities such as a failure of the charge relay 30. The processing executed by this control unit 12 will be described later.

[0018] The voltage detection unit 13 is configured to detect the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32 of the charge relay 30. This voltage detection unit 13 is configured with a detection element such as a voltage sensor. The potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32 detected by the voltage detection unit 13 is output to the control unit 12. Note that this voltage detection unit 13 may be provided in a configuration other than the relay drive control device 10.

[0019] A part or all of this control unit 12 may be configured by an electronic control device (such as an HV_ECU or a charging ECU) that typically includes a processor such as a microcomputer, a memory, and an input / output interface, etc. This electronic control device can realize a part or all of the above-mentioned functions by having the processor read and execute a program stored in the memory.

[0020] [control] Next, the control executed by the relay drive control device 10 according to this embodiment will be described with further reference to Figures 2 to 6. The controls executed by the relay drive control device 10 can be exemplified by "DC charging control" which controls the charging of the drive battery 20, "relay drive control" which controls the operating state of the charge relay 30, and "relay diagnosis control" which diagnoses the presence or absence of an abnormality in the charge relay 30.

[0021] (1) DC charging control 2 is a flowchart showing the procedure of DC charging control of the drive battery 20 using the external power supply 50, which is executed by the control unit 12 of the relay drive control device 10. The DC charging control shown in FIG. 2 is started, for example, when the charging cable 51 of the external power supply 50 is connected to the plug connection unit 40.

[0022] (Step S201) When DC charging the vehicle, the control unit 12 performs relay drive control to control the operating state of the charge relay 30. Details of this relay drive control will be described later with reference to Fig. 3. When the relay drive control is performed by the control unit 12, the process proceeds to step S202.

[0023] (Step S202) The control unit 12 determines whether the charge relay 30 has been driven by the relay drive control. This determination can be made based on the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32, detected by the voltage detection unit 13.

[0024] If the control unit 12 determines that the charge relay 30 has been actuated (step S202, Yes), the process proceeds to step S203. On the other hand, if the control unit 12 determines that the charge relay 30 has not been actuated (step S202, No), the DC charging control ends without DC charging being performed.

[0025] (Step S203) The control unit 12 performs DC charging control to charge the drive battery 20 with power from the external power source 50. A well-known charging method can be used for this DC charging. When the control unit 12 performs DC charging and the DC charging is completed, the process proceeds to step S204. When this DC charging is completed, the charge relay 30 is controlled to the open state.

[0026] (Step S204) The control unit 12 performs relay diagnosis control to diagnose the presence or absence of an abnormality in the charge relay 30. Details of this relay diagnosis control will be described later with reference to Fig. 4. When the control unit 12 performs relay diagnosis control, the process proceeds to step S205.

[0027] (Step S205) The control unit 12 judges whether or not there is a problem in the diagnosis result of the charge relay 30. More specifically, the relay drive control device 10 judges whether or not the charge relay 30 is judged to be normal.

[0028] If the control unit 12 determines that the diagnosis result of the charge relay 30 is satisfactory (step S205, NO), the DC charging control ends. On the other hand, if the control unit 12 determines that the diagnosis result of the charge relay 30 is satisfactory (step S205, YES), the process proceeds to step S206.

[0029] (Step S206) The control unit 12 determines whether the charging cable 51 has been unplugged from the plug connection unit 40, the charging lid has been closed, and the vehicle ignition switch has been turned on (IG-ON). This determination can be made by the control unit 12 acquiring information such as the opening and closing of the charging lid and an ignition switch signal from a specific in-vehicle device. Only when the control unit 12 determines that the charging lid has been closed and the ignition switch has been turned on (Yes in step S206), the process proceeds to step S207.

[0030] (Step S207) The control unit 12 performs relay diagnosis control once again to diagnose again whether or not there is an abnormality in the charge relay 30. This relay diagnosis control is the same process as the relay diagnosis control in step S204 described above. When the control unit 12 performs relay diagnosis control once again, the process proceeds to step S208. Note that this re-diagnosis of the abnormality of the charge relay 30 may be performed multiple times by setting a time limit, for example.

[0031] (Step S208) The control unit 12 judges whether or not there is a problem in the diagnosis result of the charge relay 30. More specifically, the relay drive control device 10 judges whether or not the charge relay 30 is judged to be normal.

[0032] If the control unit 12 determines that the diagnosis result of the charge relay 30 is satisfactory (step S208, NO), the DC charging control ends. On the other hand, if the control unit 12 determines that the diagnosis result of the charge relay 30 is satisfactory (step S208, YES), the process proceeds to step S209.

[0033] (Step S209) The control unit 12 determines that there is an abnormal state in the charge relay 30. When the control unit 12 determines that there is an abnormal state in the charge relay 30, the DC charging control ends.

[0034] The result of the determination that the charge relay 30 is abnormal may be notified to the user of the vehicle. This notification may be, for example, by using a function (such as an LED lamp) that displays the status of the charging equipment to inform the user that the charge relay 30 is abnormal.

[0035] This DC charging control controls whether or not DC charging of the drive battery 20 using the external power source 50 is performed, and also determines whether the charge relay 30 is normal or abnormal for the next DC charging.

[0036] (2) Relay drive control Fig. 3 is a flowchart showing the procedure of the relay drive control process executed by the control unit 12 of the relay drive control device 10 in step S201 in Fig. 2. Note that the state of the charge relay 30 before starting this relay drive control is assumed to be an open state (OFF operation) in which the terminals are electrically disconnected.

[0037] (Step S301) The control unit 12 judges whether or not a "relay driving condition" that is a condition for driving the charge relay 30 to permit charging the drive battery 20 from the external power source 50 is satisfied. Examples of this relay driving condition include a case where the functions of the drive battery 20 and the voltage conversion unit 11 all show predetermined normal values, such as the drive battery 20 not being abnormally high voltage, the drive battery 20 not being abnormally high temperature, the output of the voltage conversion unit 11 not being abnormally low voltage, the output of the voltage conversion unit 11 not being abnormally high voltage, and the voltage conversion unit 11 not being abnormally high temperature. The satisfaction of such a relay driving condition may be judged based on a result provided by a system (not shown) that controls and manages the drive battery 20 or a system (not shown) that controls and manages the voltage conversion unit 11, or the control unit 12 may judge it itself based on physical quantities (such as voltage, current, and temperature) detected or acquired from the drive battery 20 and the voltage conversion unit 11.

[0038] If the control unit 12 determines that the relay drive condition of the charge relay 30 is satisfied (step S301, Yes), the process proceeds to step S302. On the other hand, if the control unit 12 determines that the relay drive condition of the charge relay 30 is not satisfied (step S301, No), the relay drive control ends.

[0039] If the relay drive condition of the charge relay 30 is not satisfied and the relay drive control ends, a notification may be sent to the user of the vehicle that an abnormality has occurred in the function of either the drive battery 20 or the voltage conversion unit 11. This notification may be sent, for example, by using a function (such as an LED lamp) that displays the status of the charging equipment to inform the user that external charging is not possible.

[0040] (Step S302) The control unit 12 performs an increase control of the drive voltage input from the voltage conversion unit 11. Specifically, the control unit 12 performs control to increase the drive voltage from the current voltage value to a predetermined first voltage value (described later). The control unit 12 increases the voltage value of the drive voltage output by the voltage conversion unit 11 by changing a command value of the output voltage for the voltage conversion unit 11. The speed at which this voltage value is increased is not limited, but the increase speed of the voltage value may be changed based on information related to the temperature of the charge relay 30, such as the duration of charging in the previously performed DC charging control, the time elapsed since the completion of the previously performed DC charging control, and the outside air temperature. For example, when the time elapsed since the completion of the previously performed DC charging control is short or the outside air temperature is high, it is estimated that the temperature of the charge relay 30 is relatively higher than normal, so the increase speed of the voltage value may be increased. This change allows the charge relay 30 to be driven at an earlier timing. When the control unit 12 performs the increase control of the drive voltage, the process proceeds to step S303.

[0041] (Step S303) The control unit 12 judges whether the drive voltage input from the voltage conversion unit 11 has reached a first voltage value. This first voltage value can be a driveable voltage value that allows the charge relay 30 to be driven at the upper limit of a predetermined temperature range in which the use of the charge relay 30 is permitted. As described above, in a mechanical relay, the touch voltage, which is the operating voltage, also rises with an increase in the temperature of the coil unit. For this reason, the driveable voltage value, which is the first voltage value in this embodiment, is set to a voltage value that allows the charge relay 30 to be driven even in the highest temperature state assumed within the usage range, taking into consideration various voltage drops in the supply path (including the wire harness, etc.).

[0042] If the control unit 12 determines that the driving voltage has reached the drivable voltage value (step S303, Yes), the process proceeds to step S305. On the other hand, if the control unit 12 determines that the driving voltage has not yet reached the drivable voltage value (step S303, No), the process proceeds to step S304.

[0043] (Step S304) The control unit 12 judges whether a predetermined time has elapsed since the start of the increase control of the drive voltage. When the temperature of the charge relay 30 is low, it is possible to drive the charge relay 30 even if the drive voltage is not a driveable voltage value. Therefore, this judgment is made for the purpose of driving the charge relay 30 before the drive voltage reaches a driveable voltage value if the drive voltage increase control seems to take a long time. Therefore, this predetermined time is set arbitrarily according to the purpose, for example, a time for which a drive delay of the charge relay 30 is allowed. In addition, this predetermined time may be changed based on information related to the temperature of the charge relay 30, such as the duration of charging in the previously performed DC charging control, the time elapsed since the completion of the previously performed DC charging control, and the outside air temperature. For example, when the time elapsed since the completion of the previously performed DC charging control is short or the outside air temperature is high, it is estimated that the temperature of the charge relay 30 is relatively higher than normal, so the predetermined time may be shortened. This change allows the charge relay 30 to be driven at an earlier timing.

[0044] If the control unit 12 determines that a predetermined time has elapsed since the start of the increase control of the drive voltage (step S304, Yes), the process proceeds to step S305. On the other hand, if the control unit 12 determines that a predetermined time has not yet elapsed since the start of the increase control of the drive voltage (step S304, No), the process proceeds to step S303.

[0045] (Step S305) The control unit 12 supplies a drive voltage (power) to the charge relay 30. When the drive voltage reaches the drivable voltage value in the above step S303, the control unit 12 supplies the drivable voltage value as the drive voltage to the charge relay 30. When a predetermined time has elapsed before the drive voltage reaches the drivable voltage value in the above step S304, the control unit 12 supplies the current voltage value output by the voltage conversion unit 11 as the drive voltage to the charge relay 30. When the drive voltage (power) is supplied to the charge relay 30 by the control unit 12, the process proceeds to step S306.

[0046] (Step S306) The control unit 12 judges whether or not the driving of the charge relay 30 has been completed. More specifically, the control unit 12 judges whether or not each of the positive side DC relay 31 and the negative side DC relay 32 has entered a driving state in which the terminals are electrically connected. This judgment can be made based on the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32, which are acquired from the voltage detection unit 13. More specifically, when the potential difference between both output end voltages becomes the voltage supplied from the external power source 50 (or the voltage of the driving battery 20), it can be judged that the driving of the charge relay 30 has been completed.

[0047] If the control unit 12 determines that the driving of the charge relay 30 is complete (step S306, Yes), the process proceeds to step S307. On the other hand, if the control unit 12 determines that the driving of the charge relay 30 is not yet complete (step S306, No), the process waits until the charge relay 30 is driven.

[0048] (Step S307) The control unit 12 performs a decrease control of the drive voltage input from the voltage conversion unit 11. Specifically, the control unit 12 performs a control to decrease the drive voltage from the current voltage value to a predetermined second voltage value. As a general characteristic of a mechanical relay, the open voltage, which is a non-operating voltage, has a lower voltage value than the operating voltage, which is a touch voltage. For this reason, the second voltage value can be set to a voltage value greater than the open voltage so that the charge relay 30 can maintain the operating state. The control unit 12 decreases the drive voltage output by the voltage conversion unit 11 by changing the command value of the output voltage for the voltage conversion unit 11. When the control unit 12 performs the decrease control of the drive voltage, this relay drive control ends.

[0049] This relay drive control makes it possible to appropriately drive the charge relay 30 and perform DC charging of the drive battery 20 using the external power source 50 while suppressing increases in cost and scale (size, weight) of the relay drive control device 10.

[0050] (3) Relay diagnostic control Fig. 4 is a flowchart showing the procedure of the relay diagnosis control executed by the control unit 12 of the relay drive control device 10 in steps S204 and S207 in Fig. 2. Note that when this relay diagnosis control is executed, it is assumed that the power supply from the external power source 50 to the plug connection unit 40 is stopped.

[0051] (Step S401) The control unit 12 performs a positive side DC relay stuck-closed diagnosis. More specifically, the control unit 12 diagnoses whether or not a contact of the positive side DC relay 31 is stuck. Details of this positive side DC relay stuck-closed diagnosis will be described later with reference to Fig. 5. When the control unit 12 performs a positive side DC relay stuck-closed diagnosis, the process proceeds to step S402.

[0052] (Step S402) The control unit 12 determines whether or not the positive side DC relay 31 is determined to be normal by the positive side DC relay stuck-closed diagnosis.

[0053] If the control unit 12 determines that the positive side DC relay 31 is normal (step S402, Yes), the process proceeds to step S403. On the other hand, if the control unit 12 determines that the positive side DC relay 31 is not normal (step S402, No), the process proceeds to step S408.

[0054] (Step S403) The control unit 12 performs a negative DC relay stuck-closed diagnosis. More specifically, the control unit 12 diagnoses whether or not a contact is stuck on the negative DC relay 32. Details of this negative DC relay stuck-closed diagnosis will be described later with reference to FIG. 6. When the control unit 12 performs a negative DC relay stuck-closed diagnosis, the process proceeds to step S404.

[0055] (Step S404) The control unit 12 determines whether or not the negative DC relay 32 is determined to be normal by the negative DC relay stuck-closed diagnosis.

[0056] If the control unit 12 determines that the negative side DC relay 32 is normal (step S404, Yes), the process proceeds to step S405. On the other hand, if the control unit 12 determines that the negative side DC relay 32 is not normal (step S404, No), the process proceeds to step S408.

[0057] (Step S405) The control unit 12 performs other diagnoses other than the DC relay stuck-closed diagnosis that are necessary to determine the state of the charge relay 30. When the control unit 12 performs other diagnoses, the process proceeds to step S406.

[0058] The order of the processes in steps S401 and S402, the processes in steps S403 and S404, and the process in step S405 may be changed. If there is no other diagnosis, the process in step S405 may be omitted.

[0059] (Step S406) The control unit 12 determines whether or not the charge relay 30 is determined to be normal, that is, whether or not both the positive side DC relay 31 and the negative side DC relay 32 are determined to be normal.

[0060] If the control unit 12 determines that the charge relay 30 is normal (step S406, Yes), the process proceeds to step S407. On the other hand, if the control unit 12 determines that the charge relay 30 is not normal (step S406, No), the process proceeds to step S408.

[0061] (Step S407) The control unit 12 confirms the determination that the charge relay 30 is normal. When the control unit 12 confirms that the charge relay 30 is normal, this relay diagnosis control ends.

[0062] (Step S408) The control unit 12 confirms the determination that there is an abnormality in the charge relay 30. When the control unit 12 confirms that there is an abnormality in the charge relay 30, this relay diagnosis control ends.

[0063] This relay diagnosis control makes it possible to determine in advance whether or not the next DC charging control of the drive battery 20 using the external power supply 50 will be able to be performed normally.

[0064] (4) Positive DC relay stuck-close diagnosis Further referring to Fig. 5, the positive side DC relay stuck-closed diagnosis performed in step S401 in Fig. 4 will be described. This positive side DC relay stuck-closed diagnosis is for diagnosing whether or not the positive side DC relay 31 is stuck-closed, that is, the contacts are welded and stuck in an electrically conductive state.

[0065] (Step S501) The control unit 12 controls the positive side DC relay 31 to an open state, and controls the negative side DC relay 32 to a driven state. During this control, the control unit 12 performs the above-mentioned relay drive control (FIG. 3) only on the negative side DC relay 32 to be driven. When the control unit 12 controls the positive side DC relay 31 to an open state, and controls the negative side DC relay 32 to a driven state, the process proceeds to step S502.

[0066] (Step S502) The control unit 12 judges whether or not a first time has elapsed since controlling the operating states of the positive side DC relay 31 and the negative side DC relay 32. This judgment is made for the purpose of forcibly terminating the diagnosis when the state of the positive side DC relay 31 is unstable and it cannot be determined whether it is normal or abnormal. Therefore, this first time may be appropriately set based on the performance of the charge relay 30, the charging specifications of the vehicle, and the like.

[0067] When the control unit 12 determines that the first time has elapsed since the control unit 12 controlled the operating states of the plus side DC relay 31 and the minus side DC relay 32 (step S502, Yes), the process proceeds to step S507. On the other hand, when the control unit 12 determines that the first time has not yet elapsed since the control unit 12 controlled the operating states of the plus side DC relay 31 and the minus side DC relay 32 (step S502, No), the process proceeds to step S503.

[0068] (Step S503) The control unit 12 monitors the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32. This potential difference between both output end voltages can be acquired from the voltage detection unit 13. When the potential difference between both output end voltages is monitored by the control unit 12, the process proceeds to step S504.

[0069] (Step S504) The control unit 12 judges whether the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32 is less than a predetermined threshold value. This judgment is made to determine whether the positive side DC relay 31 is in a driven state or an open state. Therefore, this threshold value is set to an arbitrary value between the voltage value of the driving battery 20 that appears as the potential difference between the two output end voltages when both DC relays 31 and 32 are in a driven state, and a value of approximately zero that appears as the potential difference between the two output end voltages when both DC relays 31 and 32 are in an open state.

[0070] When the control unit 12 determines that the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32 is less than the threshold value (step S504, Yes), the process proceeds to step S505. On the other hand, when the control unit 12 determines that the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32 is equal to or greater than the threshold value (step S504, No), the process proceeds to step S506.

[0071] (Step S505) The control unit 12 judges whether or not the state in which the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32 is less than the threshold continues for a second time. This judgment is made in order to judge whether or not the states of the DC relays 31 and 32 are stable. Therefore, the second time is set to any time required to judge the states of the DC relays 31 and 32.

[0072] When the control unit 12 determines that the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32 is less than the threshold value and stable for the second time continuously (step S505, Yes), the process proceeds to step S508. On the other hand, when the control unit 12 determines that the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32 is not less than the threshold value and stable for the second time continuously (step S505, No), the process proceeds to step S502.

[0073] (Step S506) The control unit 12 judges whether or not the state in which the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32 is equal to or greater than the threshold continues for a second time. This judgment is made in order to judge whether or not the states of the DC relays 31 and 32 are stable. This second time is as described in step S505 above.

[0074] When the control unit 12 determines that the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32 is stable at or above the threshold for the second time continuously (step S506, Yes), the process proceeds to step S509. On the other hand, when the control unit 12 determines that the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32 is not stable at or above the threshold for the second time continuously (step S506, No), the process proceeds to step S502.

[0075] (Step S507) The control unit 12 determines that it is in a state where it is not possible to determine whether the positive side DC relay 31 is normal or abnormal (impossible determination). When the control unit 12 determines that it is impossible to determine the positive side DC relay 31, the process proceeds to step S510.

[0076] (Step S508) The control unit 12 determines that the positive side DC relay 31 is normal (normal determination). If the control unit 12 determines that the positive side DC relay 31 is normal, the process proceeds to step S510.

[0077] (Step S509) The control unit 12 determines that an abnormality such as a stuck-closed state has occurred in the positive side DC relay 31 (abnormality determination). If the control unit 12 determines that the positive side DC relay 31 has an abnormality, the process proceeds to step S510.

[0078] (Step S510) The control unit 12 controls both the positive side DC relay 31 and the negative side DC relay 32 to an open state. When the control unit 12 controls the positive side DC relay 31 and the negative side DC relay 32 to an open state, this positive side DC relay stuck-closed diagnosis ends.

[0079] By this positive side DC relay stuck-closed diagnosis, it is possible to easily determine whether the positive side DC relay 31 alone has a contact stuck abnormality.

[0080] (5) Negative DC relay stuck-close diagnosis Further referring to Fig. 6, the negative side DC relay stuck-closed diagnosis performed in step S403 of Fig. 4 will be described. This negative side DC relay stuck-closed diagnosis is to diagnose whether or not the negative side DC relay 32 is stuck-closed, that is, the contacts are welded and stuck in an electrically conductive state.

[0081] (Step S601) The control unit 12 controls the positive side DC relay 31 to a driven state, and controls the negative side DC relay 32 to an open state. During this control, the control unit 12 performs the above-mentioned relay drive control (FIG. 3) only on the positive side DC relay 31 to be driven. When the control unit 12 controls the positive side DC relay 31 to a driven state, and controls the negative side DC relay 32 to an open state, the process proceeds to step S602.

[0082] (Step S602) The control unit 12 judges whether or not a first time has elapsed since controlling the operating states of the positive side DC relay 31 and the negative side DC relay 32. This judgment is made for the purpose of forcibly terminating the diagnosis when the state of the negative side DC relay 32 is unstable and it cannot be determined whether it is normal or abnormal. Therefore, this first time may be appropriately set based on the performance of the charge relay 30, the charging specifications of the vehicle, and the like.

[0083] When the control unit 12 determines that the first time has elapsed since the control unit 12 controlled the operating states of the plus side DC relay 31 and the minus side DC relay 32 (step S602, Yes), the process proceeds to step S607. On the other hand, when the control unit 12 determines that the first time has not yet elapsed since the control unit 12 controlled the operating states of the plus side DC relay 31 and the minus side DC relay 32 (step S602, No), the process proceeds to step S603.

[0084] (Step S603) The control unit 12 monitors the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32. This potential difference between both output end voltages can be acquired from the voltage detection unit 13. When the potential difference between both output end voltages is monitored by the control unit 12, the process proceeds to step S604.

[0085] (Step S604) The control unit 12 judges whether the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32 is less than a predetermined threshold value. This judgment is made in order to determine whether the negative side DC relay 32 is in a driven state or an open state. Therefore, this threshold value is set to an arbitrary value between the voltage value of the driving battery 20 that appears as the potential difference between the two output end voltages when both DC relays 31 and 32 are in a driven state, and a value of approximately zero that appears as the potential difference between the two output end voltages when both DC relays 31 and 32 are in an open state.

[0086] When the control unit 12 determines that the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32 is less than the threshold value (step S604, Yes), the process proceeds to step S605. On the other hand, when the control unit 12 determines that the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32 is equal to or greater than the threshold value (step S604, No), the process proceeds to step S606.

[0087] (Step S605) The control unit 12 judges whether or not the state in which the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32 is less than the threshold continues for a second time. This judgment is made in order to judge whether or not the states of the DC relays 31 and 32 are stable. Therefore, the second time is set to any time required to judge the states of the DC relays 31 and 32.

[0088] When the control unit 12 determines that the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32 is less than the threshold value and stable for the second time continuously (step S605, Yes), the process proceeds to step S608. On the other hand, when the control unit 12 determines that the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32 is not less than the threshold value and stable for the second time continuously (step S605, No), the process proceeds to step S602.

[0089] (Step S606) The control unit 12 judges whether or not the state in which the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32 is equal to or greater than the threshold continues for a second time. This judgment is made in order to judge whether or not the states of the DC relays 31 and 32 are stable. This second time is as described in step S605 above.

[0090] When the control unit 12 determines that the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32 is stable at or above the threshold for the second time continuously (step S606, Yes), the process proceeds to step S609. On the other hand, when the control unit 12 determines that the potential difference between the output end voltage of the positive side DC relay 31 and the output end voltage of the negative side DC relay 32 is not stable at or above the threshold for the second time continuously (step S606, No), the process proceeds to step S602.

[0091] (Step S607) The control unit 12 determines that it is in a state where it is not possible to determine whether the negative side DC relay 32 is normal or abnormal (impossible determination). When the control unit 12 determines that it is impossible to determine the negative side DC relay 32, the process proceeds to step S610.

[0092] (Step S608) The control unit 12 determines that the negative side DC relay 32 is normal (normal determination). If the control unit 12 determines that the negative side DC relay 32 is normal, the process proceeds to step S610.

[0093] (Step S609) The control unit 12 determines that an abnormality such as a stuck-closed state has occurred in the negative DC relay 32 (abnormality determination). If the control unit 12 determines that the negative DC relay 32 is abnormal, the process proceeds to step S610.

[0094] (Step S610) The control unit 12 controls both the positive side DC relay 31 and the negative side DC relay 32 to an open state. When the control unit 12 controls the positive side DC relay 31 and the negative side DC relay 32 to an open state, this negative side DC relay stuck-closed diagnosis ends.

[0095] This negative DC relay stuck-closed diagnosis makes it possible to easily determine whether the negative DC relay 32 alone has a contact stuck abnormality.

[0096] <Actions and Effects> As described above, according to the relay drive control device 10 according to an embodiment of the present disclosure, when the charge relay (CHR) 30 connecting the drive battery 20 and the external power source 50 is driven for DC charging, the voltage conversion unit 11 that generates the drive voltage is controlled to increase the drive voltage to a voltage value (first voltage value) capable of driving the charge relay 30. Then, the drive voltage is supplied to the charge relay 30 when the drive voltage reaches the voltage value (first voltage value) capable of driving the charge relay 30 or a predetermined time has elapsed since the drive voltage started to increase, whichever occurs first.

[0097] With this control, by setting the first voltage value to a voltage value that allows the charge relay 30 to be driven at the upper limit of a predetermined temperature range in which use of the charge relay 30 is permitted, the charge relay 30 can be driven suitably without changing the structure of the relay (such as the number of coil turns or the magnetic circuit in a mechanical relay) even in a high-temperature environment in which it is expected to be used. Also, by setting a time limit of a predetermined time, the charge relay 30 can be driven early when the temperature of the charge relay 30 is not high.

[0098] Furthermore, according to the relay drive control device 10 of this embodiment, there is no need to add a new dedicated voltage sensor or temperature sensor for relay drive control, so it is possible to reduce the cost and scale (size, weight) of the device while maintaining the drive performance of the DC relays 31 and 32, and ensure reliability and merchantability for DC charging.

[0099] The above describes one embodiment of the present disclosure, but the present disclosure can be understood as a relay drive control device, a control method executed by a control unit of the relay drive control device having a processor and a memory, a control program for executing the control method, a computer-readable non-transitory recording medium storing the control program, and a vehicle equipped with the relay drive control device. [Industrial Applicability]

[0100] The relay drive control device of the present disclosure can be used, for example, to control the drive of a relay for connecting a battery mounted in a vehicle to an external power source. [Explanation of symbols]

[0101] 10 Relay drive control device 11 Voltage conversion section 12 Control section 13 Voltage detection section 20 Drive battery 30 Charge Relay (CHR) 31 DC Relay 32 DC Relay 40 Plug connection 50 External power supply 51 Charging cable

Claims

1. A relay drive control device that controls drive of a relay for connecting a battery mounted in a vehicle to an external power source, a control unit that, when driving the relay, increases an output voltage of the battery to a voltage value at which the relay can be driven and supplies the increased voltage to the relay; a voltage conversion unit that receives the output voltage from the battery, converts the output voltage into a drive voltage, and outputs the drive voltage to the control unit, The control unit is When driving the relay, the voltage conversion unit is controlled so as to increase the drive voltage input from the voltage conversion unit to a first voltage value at which the relay can be driven, and when the drive voltage reaches the first voltage value, the drive voltage is supplied to the relay; a relay drive control device that changes a rate at which the drive voltage is increased to the first voltage value based on information related to a temperature of the relay;

2. 2. The relay drive control device according to claim 1, wherein, when driving the relay, if a predetermined time has elapsed after the control unit starts controlling the voltage conversion unit to increase the drive voltage to the first voltage value before the drive voltage reaches the first voltage value, the control unit supplies the drive voltage to the relay at a point when the predetermined time has elapsed.

3. A relay drive control device as described in Claim 2, wherein the control unit changes the specified time based on information related to the temperature of the relay.

4. 4. The relay drive control device according to claim 1, wherein the control unit controls the voltage conversion unit to reduce the drive voltage to a second voltage value after the relay is driven by supplying the drive voltage to the relay.

5. 5. The relay drive control device according to claim 1, wherein the first voltage value is a voltage value at which the relay can be driven at an upper limit value of a predetermined temperature range in which use of the relay is permitted.

6. The relay drive control device according to claim 4 , wherein the second voltage value is a voltage value at which the driven relay does not switch to an open state.

7. The relay drive control device according to claim 1 , wherein the control unit determines whether or not it is possible to drive the relay based on states of the battery and the voltage conversion unit.

8. The relay drive control device according to claim 1 , wherein the external power supply is an external charging facility that is plugged into the vehicle and is capable of supplying electric power to the vehicle.

9. A control method executed by a computer of a relay drive control device that controls drive of a relay for connecting a battery mounted in a vehicle to an external power source, comprising: determining whether to activate the relay; converting the output voltage of the battery into a driving voltage; When driving the relay, increasing the driving voltage to a first voltage value capable of driving the relay; changing a rate at which the drive voltage is increased to the first voltage value based on information related to a temperature of the relay; and supplying the drive voltage to the relay when the drive voltage reaches the first voltage value.

10. A program executed by a computer of a relay drive control device that controls driving of a relay for connecting a battery mounted in a vehicle to an external power source, determining whether to activate the relay; converting the output voltage of the battery into a driving voltage; When driving the relay, increasing the driving voltage to a first voltage value capable of driving the relay; changing a rate at which the drive voltage is increased to the first voltage value based on information related to a temperature of the relay; and supplying the drive voltage to the relay when the drive voltage reaches the first voltage value.

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