RELAY DIAGNOSTIC DEVICE FOR A VEHICLE

Abstract

Complications in diagnosing the presence or absence of malfunctions in relays are reduced. A relay diagnostic device for a vehicle comprises a first detector, a second detector, a third detector, and a control system. The first detector is designed to detect a voltage from a transducer. The second detector is designed to detect a voltage that represents a potential difference between a first electrical power line between a first relay and the transducer, and a second electrical power line between a second relay and an electrical energy storage unit. The third detector is designed to detect a voltage between the terminals of the first relay.The control system is designed to perform the following actions: adjusting the voltage of the electrical energy storage unit and the voltage of the converter to each other, diagnosing an OFF-fixing anomaly at the first relay, outputting an ON signal to the second relay, diagnosing an OFF-fixing anomaly at the second relay, diagnosing an ON-fixing anomaly at the second relay, and diagnosing an ON-fixing anomaly at the first relay.

Description

Technical field The invention relates to a relay diagnostic device for a vehicle. State of the art Diagnoses are performed to determine the presence or absence of fusion (welding) of a relay installed in a vehicle (see patent references 1 to 3). A vehicle has been proposed that does not have a pre-charging circuit designed to reduce relay fusion (see patent references 1 and 2). State of the art Patent literature Patent Literature 1: Unexamined Japanese Patent Application Publication JP 2020 - 99 129 Patent Literature 2: Unexamined Japanese Patent Application Publication JP 2007 - 295 699 Patent Literature 3: Unexamined Japanese Patent Application Publication JP 2011 - 55 631 A Brief description of the invention Problem to be solved with the invention When diagnosing the presence or absence of malfunctions in relays, a transducer must be switched on and off at least once when diagnosing a relay in a configuration as described in patent literature 1 and 2. This means that to diagnose any malfunctions in the relays, the transducer must be switched on and off multiple times. Therefore, there is a need for improvement. The object of the invention is to reduce the complexity of diagnosing the presence or absence of malfunctions in relays. Means to solve the problem A relay diagnostic device for a vehicle according to one embodiment is designed to diagnose the operation of a first relay and the operation of a second relay of the vehicle, wherein a first line for electrical energy provided with the first relay and a second line for electrical energy provided with the second relay couple an electrical energy storage unit and a converter, wherein the second line for electrical energy has a different polarity than the first line for electrical energy. The relay diagnostic device comprises a first detector, a second detector, a third detector, and a control system. The first detector is designed to detect a voltage from the converter. The second detector is designed to detect a voltage that represents a potential difference between the first electrical energy line between the first relay and the converter, and the second electrical energy line between the second relay and the electrical energy storage unit. The third detector is designed to detect a voltage between the terminals of the first relay. The control system includes a processor and memory and is designed to control the converter, the first relay, and the second relay. The control system is designed to perform the following actions: adjusting the converter voltage to a voltage from the electrical energy storage unit; outputting an ON signal to the first relay when the converter is switched on; diagnosing an OFF-fixing anomaly at the first relay when neither the voltage detected by the second detector nor the voltage detected by the third detector is detectable between the terminals; and outputting the ON signal to the second relay when both the converter and the first relay are switched on.Outputting an OFF signal to the converter and diagnosing an OFF locking anomaly at the second relay when the voltage at the first detector decreases; diagnosing an ON locking anomaly at the second relay when the voltage at the first detector does not decrease after outputting the OFF signal to the second relay, in a state where the converter is off and the first relay is on; and diagnosing an ON locking anomaly at the first relay when the voltage detected by the third detector between the terminals after outputting the OFF signal to the first relay is 0 (V), in a state where the converter is off and the second relay is off. Effects of the invention In the relay diagnostic device for the vehicle according to one embodiment, the control system performs the respective steps to cause the converter to be switched on and off once. This reduces the complexity of diagnosing the presence or absence of malfunctions in relays. Brief description of the drawings The drawings show: Fig. 1 a representation of a hybrid vehicle with a relay diagnostic device according to a first embodiment. Fig. 2 a block diagram of a schematic configuration of the hybrid vehicle with the relay diagnostic device according to the first embodiment. Fig. 3 a block diagram of an example of a functional configuration of a control system. Fig. 4 a representation of an example of a basic design of a control unit. Fig. 5 a diagram showing the times at which a system main relay in the hybrid vehicle according to the first embodiment is switched on and off, and the voltages detected at the respective times. Fig. 6 a flowchart of the first half of an execution sequence in the relay diagnostic device according to the first and second embodiments.Figure 7 shows a flowchart of the second half of the execution sequence in the relay diagnostic device according to the first and second embodiments. Figure 8 shows a flowchart of an example of the execution sequence in the relay diagnostic device according to the second embodiment. Figure 9 shows a block diagram of an internal configuration of a hybrid vehicle with a relay diagnostic device according to a modification example. Figure 10 shows a diagram illustrating the times at which a system main relay in the hybrid vehicle according to the modification example is switched on and off, and the voltages detected at the respective times. Embodiments of the invention A first embodiment, a second embodiment, and a modification example are described in detail with reference to the drawings. It should be noted that in the following description, identical or substantially identical configurations or components are designated with the same reference numerals, and redundant descriptions thereof are avoided. First embodiment Fig. 1 shows a hybrid vehicle 10 with a relay diagnostic device 40 according to the first embodiment. The hybrid vehicle 10 is an example of a vehicle. The hybrid vehicle 10 is equipped with a powertrain 16 comprising an internal combustion engine 12 and a transmission 14. The powertrain 16 has an output shaft 19. The output shaft 19 is coupled to a rear wheel 29 via a drive shaft 21 and a rear differential 23. Furthermore, the transmission 14 has a front differential 25. The front differential 25 is coupled to a front wheel 27. It should be noted that a type of hybrid vehicle 10 can be a series type, a parallel type, or a series-parallel type. The powertrain 16 is an all-wheel drive powertrain; however, the powertrain 16 is not limited to this and can also have a front-wheel drive power unit or a rear-wheel drive power unit. Fig. 2 is a block diagram of a schematic configuration of the hybrid vehicle 10. Fig. 3 is a block diagram of an example of a functional configuration of a control system 50. Fig. 4 is a representation of a basic construction of the respective control units contained in the control system 50. As shown in Fig. 2, the hybrid vehicle 10 comprises the internal combustion engine 12, the transmission 14, a drive motor 18, an inverter 24, a main battery 26, an auxiliary battery 28, a DC-DC converter 32, and a system main relay 34. DC stands for direct current. The hybrid vehicle 10 also includes a relay diagnostic device 40. The hybrid vehicle 10 can be switched between an HEV (hybrid electric vehicle) driving mode and an EV (electric vehicle) driving mode. In HEV driving mode, the hybrid vehicle 10 operates using drive energy from the combustion engine 12 and the drive energy from the traction motor 18. In EV driving mode, the hybrid vehicle 10 operates using drive energy from the traction motor 18 in a state where the combustion engine 12 is stopped. internal combustion engine The engine 12 is an internal combustion engine that generates drive energy using a fuel such as gasoline. The internal combustion engine 12 is designed to supply drive energy to power the front wheels 27 and the rear wheels 29 of the hybrid vehicle 10. A crankshaft, which is an output shaft of the internal combustion engine 12, is coupled to the transmission 14, for example via a torque converter. The transmission 14 modifies the drive energy supplied by the internal combustion engine 12 and transmits the modified drive energy to the front wheels 27 and the rear wheels 29. The internal combustion engine 12 has an integrated starter generator (ISG) 13. An output shaft of the ISG 13 is coupled to the crankshaft of the internal combustion engine 12 via a gear. The drive energy output by the ISG 13 is transmitted to the crankshaft of the internal combustion engine 12. For example, the ISG 13 is coupled to the auxiliary battery 28. The ISG 13 generates drive energy using electrical energy supplied by the auxiliary battery 28. Furthermore, the ISG 13 is designed to generate electrical energy using the drive energy output by the internal combustion engine 12. The auxiliary battery 28 can be recharged with the electrical energy generated by the ISG 13. Gearbox, etc. For example, the traction motor 18 is arranged in the gearbox 14. The traction motor 18 is an electric motor. The traction motor 18 is coupled to the main battery 26 via the inverter 24. The traction motor 18 is designed to perform both drive operation and regenerative operation. In regenerative operation, the traction motor 18 converts kinetic energy into electrical energy and charges the main battery 26 via the inverter 24. Furthermore, the traction motor 18 generates drive energy using the electrical energy supplied by the main battery 26 via the inverter 24. Main battery The main battery 26 is an example of an electrical energy storage unit that stores electrical energy to be supplied to the drive motor 18. Specifically, the main battery 26 is a battery with a higher voltage (e.g., 200 V) than the voltage of the auxiliary battery 28. A sensor 26A detects the voltage of the main battery 26. For example, a secondary battery, such as a lithium-ion battery or a nickel-metal hydride battery, is used as the main battery 26. The main battery 26 is connected to the respective components in the hybrid vehicle 10 via the DC-DC converter 32. Accordingly, the DC-DC converter 32 in the hybrid vehicle 10 is designed to step down the electrical energy stored in the main battery 26 and supply the stepped-down electrical energy to the respective components. The system main relay 34, described later, is located between the main battery 26 and the DC-DC converter 32. Auxiliary battery The auxiliary battery 28 is connected to the main battery 26 via the DC-DC converter 32, a first line 33 for electrical energy, and a second line 35 for electrical energy. The auxiliary battery 28 has a lower voltage (e.g., 12 V) than the voltage of the main battery 26. The auxiliary battery 28 is charged with electrical energy generated by the ISG 13. The electrical energy from the auxiliary battery 28 is supplied to the DC-DC converter 32. For example, a secondary battery, such as a lead-acid battery or a lithium-ion battery, is used as the auxiliary battery 28. DC-DC converter The DC-DC converter 32 is an example of a converter connected to the main battery 26 via the first line 33 for electrical power, the second line 35 for electrical power, and the system main relay 34. The DC-DC converter 32 changes the voltage of the auxiliary battery 28. Specifically, the DC-DC converter 32 steps up the voltage of the auxiliary battery 28. The DC-DC converter 32 is designed to output a voltage equal to the voltage of the main battery 26. First line for electrical energy The first electrical power line 33 has a wiring configuration 33A and a wiring configuration 33B. Wiring configuration 33A connects the DC-DC converter 32 and a terminal A of the system main relay 34, which will be described later. Wiring configuration 33B connects a terminal B of the system main relay 34, which will be described later, and the main battery 26. The first electrical power line 33 corresponds to a wiring configuration on the positive electrode side. Wiring configuration 33A is connected to one end of a wiring configuration 41. The other end of wiring configuration 41 is connected to the inverter 24. Second line for electrical energy The second electrical power line 35 has a wiring configuration 35A and a wiring configuration 35B. The second electrical power line 35 corresponds to a wiring configuration on the negative electrode side. That is, the second electrical power line 35 has a different polarity than the first electrical power line 33. Wiring configuration 35A connects the DC-DC converter 32 and a terminal C of the system main relay 34, which will be described later. Wiring configuration 35B connects a terminal D of the system main relay 34, which will be described later, and the main battery 26. Wiring configuration 35A is connected to one end of wiring configuration 43. The other end of wiring configuration 43 is connected to the inverter 24. In this way, in the hybrid vehicle 10, the first electrical power line 33 and the second electrical power line 35 connect the main battery 26 and the DC-DC converter 32. Main system relay The system main relay 34 is designed to electrically decouple and couple the main battery 26 and the DC-DC converter 32 on both the positive and negative electrode sides. The system main relay 34 enters an open state (a decoupled state) when the hybrid vehicle 10 is stopped. The system main relay 34 enters a closed state (a coupled state) when the hybrid vehicle 10 is started and while the hybrid vehicle 10 is in motion. In the following description, an operation that causes the system main relay 34 to enter the closed state is referred to as a switch-on operation, and an operation that causes the system main relay 34 to enter the open state is referred to as a switch-off operation.In particular, the system main relay 34 has a relay 36 on the positive electrode side and a relay 38 on the negative electrode side. It should be noted that in the drawings, "SMRP" is an abbreviation for relay 36 on the positive electrode side and "SMRN" is an abbreviation for relay 38 on the negative electrode side. Relay on the positive electrode side Relay 36 on the positive electrode side is an example of a first relay with terminal A and terminal B. Relay 36 on the positive electrode side is located in the first electrical power line 33 between the main battery 26 and the DC-DC converter 32. The switching on and off of relay 36 on the positive electrode side is controlled by the control system 50 described later. Relay on the negative electrode side Relay 38 on the negative electrode side is an example of a second relay with terminal C and terminal D. Relay 38 on the negative electrode side is located in the second electrical power line 35 between the main battery 26 and the DC-DC converter 32. The switching on and off of relay 38 on the negative electrode side is controlled by the control system 50 described later. Relay diagnostic device The relay diagnostic device 40 is an example of a relay diagnostic device for a vehicle. The relay diagnostic device 40 diagnoses the operation of relay 36 on the positive electrode side and the operation of relay 38 on the negative electrode side within a time period TP of a cycle described later. In particular, the relay diagnostic device 40 diagnoses the presence or absence of respective malfunctions in relay 36 on the positive electrode side and in relay 38 on the negative electrode side. In the present embodiment, "malfunctions" refers to "ON-fixing and OFF-fixing anomalies". "ON-fixing anomaly" here means that even if the control system 50, described later, outputs an OFF signal to relay 36 on the positive electrode side or to relay 38 on the negative electrode side, relay 36 on the positive electrode side or relay 38 on the negative electrode side does not switch to the OFF state. Examples of the ON-fixing anomaly include a case in which relay 36 on the positive electrode side or relay 38 on the negative electrode side is fused (welded) to a terminal. "OFF-fixing anomaly" here means that even if the control system 50 sends an ON signal to relay 36 on the positive electrode side or to relay 38 on the negative electrode side, relay 36 on the positive electrode side or relay 38 on the negative electrode side does not switch to the ON state. Examples of the OFF-fixing anomaly include a case where a fault, such as a contact fault, occurs in a circuit that actuates relay 36 on the positive electrode side or relay 38 on the negative electrode side. The relay diagnostic device 40 comprises a first voltage sensor 42, a second voltage sensor 44, a third voltage sensor 46, and the control system 50. It should be noted that the control system 50 also serves as the control system for the entire hybrid vehicle 10. First voltage sensor The first voltage sensor 42 is an example of a first detector. The first voltage sensor 42 detects a voltage of the DC-DC converter 32 on one side of the main battery 26. Specifically, the first voltage sensor 42 is coupled to wiring 33A and wiring 35A near an input / output terminal of the DC-DC converter 32. Hereinafter, the voltage detected by the first voltage sensor 42 is referred to as voltage VA. Second voltage sensor The second voltage sensor 44 is an example of a second detector. The second voltage sensor 44 is connected via wiring 33A between relay 36 on the positive electrode side and DC-DC converter 32, and via wiring 35B between relay 38 on the negative electrode side and main battery 26. This means that the second voltage sensor 44 detects a voltage that is a potential difference between the first electrical power line 33 between the relay 36 on the positive electrode side and the DC-DC converter 32, and the second electrical power line 35 between the relay 38 on the negative electrode side and the main battery 26. The voltage detected by the second voltage sensor 44 is referred to below as voltage VB. Third voltage sensor The third voltage sensor 46 is an example of a third detector. The third voltage sensor 46 detects a voltage between the terminals of the relay 36 on the positive electrode side. That is, the third voltage sensor 46 detects a voltage between terminal A and terminal B. Hereinafter, the voltage detected by the third voltage sensor 46 between the terminals is referred to as voltage VC. Control system The control system 50 has a processor 73 and a main memory 74. The main memory 74 is an example of a memory. The control system 50 controls the operation of the DC-DC converter 32, the relay 36 on the positive electrode side, and the relay 38 on the negative electrode side. The control system 50 is started by the driver pressing a switch. When the driver presses the switch while depressing the brake pedal of the hybrid vehicle 10, the control system 50 controls the hybrid vehicle 10 to enter a ready-to-drive state. In contrast, when the driver presses the switch while pressing down the brake pedal of the hybrid vehicle 10 in a state in which the hybrid vehicle 10 is controlled to be in a ready-to-drive state, the control system 50 controls the hybrid vehicle 10 to be placed in a stopped state (Ready-OFF). As shown in Figs. 2 and 5, in the present embodiment, a time period from the switching on of the DC-DC converter 32 until the end of the diagnosis by the relay diagnostic device 40 is referred to as "a cycle". In the present embodiment, the time period TP from time t1 to time t9 corresponds to a time period required for one cycle. Within one cycle, the DC-DC converter 32 performs the switch-on process once and the switch-off process once. It should be noted that in the drawings, DCDC ON and DCDC OFF denote the switching on and off of the DC-DC converter 32, respectively. The time at which the diagnosis by the relay diagnostic device 40 ends refers to the time at which the diagnosis of the presence or absence of the respective malfunction (the ON-locking anomaly and the OFF-locking anomaly) in relay 36 on the positive electrode side and in relay 38 on the negative electrode side is completed. That is, the relay diagnostic device 40 completes the diagnosis of the operation of the system main relay 34 within one cycle. Hereinafter, the presence of at least one ON-locking anomaly or one OFF-locking anomaly together may be referred to as a "malfunction". The time at which the hybrid vehicle 10 transitions to a ready-on state is specified as t4, and the time at which the hybrid vehicle 10 transitions to a ready-off state is specified as t5. Time t4 is a time after time t3, at which the ON signal is sent to relay 38 on the negative electrode side. Time t5 is a time before time t6, at which the DC-DC converter 32 is switched off, and after time t4. As shown in Fig. 3, the control system 50 includes an information acquisition unit 52, an engine control unit 54, an internal combustion engine control unit 56, a relay control unit 58, a converter control unit 62 and a diagnostic unit 64. Information recorder The information acquirer 52 acquires various types of information that are to be used for a process to be carried out by the control system 50. Furthermore, the information acquirer 52 outputs the acquired information to the motor control unit 54, the internal combustion engine control unit 56, the relay control unit 58, the converter control unit 62, and the diagnostic unit 64. Engine control unit As shown in Figs. 2 and 3, the motor control unit 54 controls the operation of the traction motor 18. For example, the motor control unit 54 controls the operation of a switching device of the inverter 24 in order to control the supply of electrical energy between the traction motor 18 and the main battery 26. In this way, the motor control unit 54 can control the generation of drive energy and the generation of electrical energy by the traction motor 18. Internal combustion engine control unit The internal combustion engine control unit 56 controls the operation of the internal combustion engine 12. For example, the internal combustion engine control unit 56 controls the operation of the respective components arranged in the internal combustion engine 12 in order to control, for example, the throttle valve angle, the ignition timing, and the fuel injection quantity. In this way, the internal combustion engine control unit 56 can control the output of the internal combustion engine 12. The internal combustion engine control unit 56 also controls the operation of the ISG 13. In particular, the internal combustion engine control unit 56 is designed to control a restart of the internal combustion engine 12 by the ISG 13 by controlling the supply of electrical energy from the auxiliary battery 28 to the ISG 13. Relay control unit The relay control unit 58 controls a switching-on (closing) and a switching-off (opening) operation of the system main relay 34. The switching-on operation of the system main relay 34 refers to an operation in which relay 36 on the positive electrode side and relay 38 on the negative electrode side are switched from OFF to ON. The switching-off operation of the system main relay 34 refers to an operation in which relay 36 on the positive electrode side and relay 38 on the negative electrode side are switched from ON to OFF. When the system main relay 34 is switched on, the relay control unit 58 sends the ON signal to the system main relay 34. When the system main relay 34 is switched off, the relay control unit 58 sends the OFF signal to the system main relay 34. Converter control unit The converter control unit 62 controls the operation of the DC-DC converter 32. In particular, the converter control unit 62 controls the operation of a switching device of the DC-DC converter 32 in order to control the supply of electrical energy between the main battery 26 and the auxiliary battery 28. Diagnostic unit The diagnostic unit 64 diagnoses the presence or absence of a malfunction in the system's main relay 34. Specifically, the diagnostic unit 64 diagnoses the presence or absence of a malfunction in relay 36 on the positive electrode side and the presence or absence of a malfunction in relay 38 on the negative electrode side. For example, the diagnostic unit 64 notifies the driver of the diagnostic result by illuminating a lamp on the instrument panel of the hybrid vehicle 10. As shown in Fig. 4, the motor control unit 54, the combustion engine control unit 56, the relay control unit 58, the converter control unit 62, and the diagnostic unit 64 each have a microcontroller 72, which includes, for example, the processor 73 and the main memory 74. The main memory 74 stores a predefined program. The processor 73 and the main memory 74 are linked and able to communicate with each other. A program is executed by instructing the processor 73 to read the predetermined program from the main memory 74 and then to develop and execute the predetermined program. It should be noted that the microcontroller 72 can also have multiple processors 73. The microcontroller 72 can also have multiple main memories 74. The motor control unit 54, the internal combustion engine control unit 56, the relay control unit 58, and the converter control unit 62 each have an input circuit 76, a driver circuit 77, a communication circuit 78, an external memory 79, and a power supply circuit 81. The diagnostic unit 64 has the input circuit 76, the communication circuit 78, the external memory 79, and the power supply circuit 81. The input circuit 76 converts signals received from various sensors into signals that can be received by the microcontroller 72. Based on the signals output by the microcontroller 72, the driver circuit 77 generates driver signals for various devices that include the internal combustion engine 12 described above. The communication circuit 78 converts the signals output by the microcontroller 72 into communication signals for other control units. The communication circuit 78 and each of the other control units are interconnected via a vehicle network 83, such as a CAN (Controller Area Network). The communication circuit 78 also converts communication signals received from the other control units into signals that can be received by the microcontroller 72. The power supply circuit 81 provides a supply voltage to, for example, the microcontroller 72, the input circuit 76, the driver circuit 77, the communication circuit 78, and the external memory 79. The external memory 79, for example, has non-volatile memory. The external memory 79 stores, for example, programs and various data. In the hybrid vehicle 10 shown in Fig. 2, the control system 50 is designed to perform steps for diagnosing the system's main relay 34. Specifically, the control system 50 outputs the ON signal to the DC-DC converter 32 in a state where relay 36 on the positive electrode side and relay 38 on the negative electrode side are switched off (open). The control system 50 is then designed to perform a step to adjust the voltage VA of the DC-DC converter 32 to the voltage of the main battery 26. The control system 50 outputs the ON signal to relay 36 on the positive electrode side in a state where the DC-DC converter 32 is switched on. The control system 50 is then designed to perform a step to diagnose an OFF-fixing anomaly at relay 36 on the positive electrode side if neither the voltage VB of the second voltage sensor 44 nor the voltage VC of the third voltage sensor 46 is detectable. It should be noted that "if no voltage is detectable" here refers to the case where a resistance value is infinite and a test device indicates an overrange. The control system 50 outputs the ON signal to relay 38 on the negative electrode side in a state where the DC-DC converter 32 and relay 36 on the positive electrode side are switched on, and then outputs the OFF signal to the DC-DC converter 32. The control system 50 is then designed to perform a step to diagnose an OFF-fixing anomaly at relay 38 on the negative electrode side when the voltage VA at the first voltage sensor 42 decreases. The control system 50 keeps the DC-DC converter 32 in the OFF state and keeps the relay 36 on the positive electrode side in the ON state. The control system 50 is designed to subsequently perform a step to diagnose an ON-fixing anomaly at the relay 38 on the negative electrode side if the voltage VA of the first voltage sensor 42 does not decrease after the OFF signal is output to the relay 38 on the negative electrode side. The control system 50 keeps the DC-DC converter 32 in the OFF state and keeps the relay 38 on the negative electrode side in the OFF state. The control system 50 is designed to subsequently perform a step to diagnose an ON-fixing anomaly at the relay 36 on the positive electrode side when the voltage VC has the value 0 (V) after the OFF signal is output to the relay 36 on the positive electrode side. Functioning of the first embodiment Relay diagnostic control: Flowchart The following describes a procedure for executing a relay (system main relay 34) diagnostic control. Figures 6 and 7 are flowcharts of an example of the process for executing the relay diagnostic control. The flowcharts shown in Figures 6 and 7 are coupled to each other using connections with reference numerals A to E. A connection with reference numeral F is used in the second embodiment described later. Each of the relay control steps shown in Figures 6 and 7 is performed by the processor 73 contained in the control system 50. It should be noted that for the respective configurations and voltages of the hybrid vehicle 10, reference is made to Figures 1, 2, 3, 4 to 5, and reference to individual figure numbers is omitted. As shown in Fig. 6, the control system 50 causes the program to proceed to step S10 and outputs the ON signal to the DC-DC converter 32 in a state where relay 36 on the positive electrode side and relay 38 on the negative electrode side are off. The program then proceeds to step S12. In step S12, the control system 50 adjusts the voltage VA of the DC-DC converter 32 based on the voltage of the main battery 26 detected by the sensor 26A, in order to match the voltage VA of the DC-DC converter 32 to the voltage of the main battery 26. The program then proceeds to step S14. In step S14, the control system 50 outputs the ON signal to relay 36 on the positive electrode side in a state where the DC-DC converter 32 is switched on. The program then proceeds to step S16. In step S16, the control system 50 determines whether neither the voltage VB nor the voltage VC is detectable. For example, if at least one of the voltages VB or VC is detectable, e.g., if VB = V2 and VC = 0 (V) (S16: YES), the program proceeds to step S18. If neither the voltage VB nor the voltage VC is detectable (S16: NO), the program proceeds to step S28. In step S18, the control system 50 outputs the ON signal to relay 38 on the negative electrode side in a state where both the DC-DC converter 32 and relay 36 on the positive electrode side are switched on. The program then proceeds to step S20. In step S20, the control system 50 outputs the OFF signal to the DC-DC converter 32 and determines whether there is a non-decrease in voltage VA compared to voltage V1. If there is a non-decrease in voltage VA compared to voltage V1 (S20: YES), the program proceeds to step S22. If there is no non-decrease in voltage VA compared to voltage V1 (S20: NO), the program proceeds to step S30. In step S22, the control system 50 sends the OFF signal to relay 38 on the negative electrode side and determines whether there is a decrease in voltage VA compared to voltage V1. If there is a decrease in voltage VA compared to voltage V1 (S22: YES), the program proceeds to step S24. If there is no decrease in voltage VA compared to voltage V1 (S22: NO), the program proceeds to step S32. As shown in Fig. 7, in step S24, the control system 50 outputs the OFF signal to relay 36 on the positive electrode side and determines whether the voltage VC is undetectable or has a value of 0 (V). If the voltage VC is undetectable (S24: YES), the program proceeds to step S26. If the voltage VC has a value of 0 (V) (S24: NO), the program proceeds to step S34. In step S26, the control system 50 displays a diagnostic result indicating that the system's main relay 34 (relay 36 on the positive electrode side and relay 38 on the negative side) is functioning correctly. For example, the control system 50 may indicate this diagnostic result by illuminating a lamp located on the dashboard to show that the relay is in good working order, or it may display a message on a touch panel confirming that the relay is functioning correctly. The program then terminates. The diagnostic result regarding the presence or absence of a malfunction in the system's main relay 34 is recorded as diagnostic information in the external memory 79. In step S28, the control system 50 displays a diagnostic result indicating that relay 36 on the positive electrode side is in an OFF-fixed anomaly state and records the diagnostic result in external memory 79. The program then terminates. A method for displaying the diagnostic result can be similar to the method in step S26. In step S30, the control system 50 displays a diagnostic result indicating that relay 38 on the negative electrode side is in an OFF-fixed anomaly state and records the diagnostic result in external memory 79. The program then terminates. A method for displaying the diagnostic result can be similar to the method in step S26. In step S32, the control system 50 displays a diagnostic result indicating that relay 38 on the negative electrode side is in an ON-fixing anomaly state and records the diagnostic result in external memory 79. The program then terminates. A method for displaying the diagnostic result can be similar to the method in step S26. In step S34, the control system 50 displays a diagnostic result indicating that relay 36 on the positive electrode side is in an ON-fixing anomaly state and records the diagnostic result in external memory 79. The program then terminates. A method for displaying the diagnostic result can be similar to the method in step S26. Fig. 5 shows the ON and OFF states of the system main relay 34 at the respective times, the detected voltage VA, the detected voltage VB, and the detected voltage VC. It should be noted that for the respective configurations of the hybrid vehicle 10, reference is made to Fig. 1, Fig. 2, Fig. 3, and Fig. 4, and reference to the individual numbering of the figures is omitted. The intervals between the respective times t1 to t9 in Fig. 5, that is, the lengths of the time periods, are examples and not limited to the time periods shown. It should be noted that there is a time delay between the sending of a control signal by the control system 50 to a control target and the start of an operating process by the control target; however, this delay is omitted in Fig. 5. A graph G1 shown in Fig. 5 indicates the times at which the ON signal and the OFF signal are sent to relay 36 on the positive electrode side. Graph G1 therefore does not indicate whether relay 36 on the positive electrode side is in the ON state or the OFF state. Graph G2 shows the times at which the ON signal and the OFF signal are sent to relay 38 on the negative electrode side. Graph G2 therefore does not indicate whether relay 38 on the negative electrode side is in the ON or OFF state. Graph G3 shows the voltage VA detected by the first voltage sensor 42. Graph G6 shows the voltage VB detected by the second voltage sensor 44. Graph G7 shows the voltage VC detected by the third voltage sensor 46. In Fig. 5, graphs G4 and G5, represented by dotted lines, indicate behavior different from that of graph G3. In Fig. 5, the diagonally hatched areas SA, SB, SC and SD each refer to an area where no voltage can be detected. As shown in Fig. 5, until just before time t1, both relay 36 on the positive electrode side and relay 38 on the negative electrode side are in the OFF state. The DC-DC converter 32 is also in the OFF state. Furthermore, the voltages VA, VB, and VC are undetectable. It can be seen that if the voltage VC is equal to 0 (V) until time t2 (in a case represented by a dotted line), relay 36 on the positive electrode side is in an ON-fixed anomaly state. In other words, it can be seen that relay 36 on the positive electrode side cannot switch off. When the DC-DC converter 32 is switched on at time t1, the voltage VA rises to the voltage V1. If the relay 36 on the positive electrode side does not exhibit an ON-fixing anomaly, the voltages VB and VC are undetectable. Upon sending the ON signal to relay 36 on the positive electrode side at time t2, if relay 36 is operating normally, it will switch to the ON state. Voltage VA is voltage V1. Voltage VB rises to voltage V2. Voltage VC is 0 (V). It can be seen that if voltages VB and VC are undetectable, relay 36 on the positive electrode side is in an OFF-locked anomaly state. In other words, relay 36 on the positive electrode side cannot switch on. Upon sending the ON signal to relay 38 on the negative electrode side at time t3, relay 38 on the negative electrode side switches to the ON state, assuming its operation is normal. Voltage VA is voltage V1. Voltage VB is voltage V2. Voltage VC is 0 (V). At time t6, the DC-DC converter 32 is switched off. It can be seen that when the voltage VA decreases, as shown in graph G4, relay 38 on the negative electrode side is in the OFF-fixed anomaly state. In other words, it can be seen that relay 38 on the negative electrode side cannot switch on. Upon sending the OFF signal to relay 38 on the negative electrode side at time t7, relay 38 on the negative electrode side, if operating normally, switches to the OFF state. At this time, the voltage VA decreases relative to the voltage V1. The voltage VB is the voltage V2. The voltage VC is 0 (V). It can be seen here that if the voltage VA is held at the voltage V1, as shown in graph G5, relay 38 on the negative electrode side is in an ON-fixed anomaly state. In other words, it can be seen that relay 38 on the negative electrode side cannot perform an OFF operation. Upon sending the OFF signal to relay 36 on the positive electrode side at time t8, relay 36 on the positive electrode side switches to the OFF state, assuming normal operation. At this time, the voltage VA remains lower than the voltage V1. The voltage VB is the same as the voltage V2. The voltage VC is undetectable. It can be seen that when the voltage VC has a value of 0 (V), relay 36 on the positive electrode side is in the ON-fixed anomaly state. Conclusion of the first embodiment As described above, the control system 50 outputs the ON signal to relay 36 on the positive electrode side in the relay diagnostic device 40. If neither voltage VB nor voltage VC is detectable thereafter, the relay diagnostic device 40 diagnoses that relay 36 on the positive electrode side is in the OFF-fixed anomaly state. If, after the ON signal is output to relay 38 on the negative electrode side, the operation of the DC-DC converter 32 stops and the voltage VA decreases, the control system 50 diagnoses that relay 38 on the negative electrode side is in the OFF-fixed anomaly state. If the voltage VA does not decrease after the OFF signal is sent to relay 38 on the negative electrode side, the control system 50 diagnoses that relay 38 on the negative electrode side is in an ON-fixed anomaly state. After the OFF signal has been sent to relay 36 on the positive electrode side and the voltage VC has a value of 0 (V), the control system 50 diagnoses that relay 36 on the positive electrode side is in an ON-fixed anomaly state. Thus, the relay diagnostic device 40 performs the necessary steps to cause the DC-DC converter 32 to be switched on and off once during a diagnostic operation. In other words, the relay diagnostic device 40 diagnoses the presence or absence of a malfunction in relay 36 on the positive electrode side and the presence or absence of a malfunction in relay 38 on the negative electrode side within a single cycle. As described above, the relay diagnostic device 40 reduces the complexity of diagnosing the presence or absence of a malfunction in relay 36 on the positive electrode side and in relay 38 on the negative electrode side compared to a configuration in which the DC-DC converter 32 is switched on and off multiple times. Second embodiment The relay diagnostic device 40 according to the second embodiment is described below. It should be noted that components identical or similar to those of the first embodiment are designated with the same reference numerals to avoid redundant descriptions. References to individual figure numbers are omitted with regard to the configurations and voltages shown in Figures 1, 2, 3, 4 to 5. As shown in the flowcharts in Fig. 6, Fig. 7 and Fig. 8, the relay diagnostic device 40 according to the second embodiment differs in that steps S2 and S4 are added before step S10. Step S10 and the subsequent steps are similar to those of the first embodiment, and a redundant description of them is omitted. In the relay diagnostic device 40 according to the second embodiment, a step to detect the voltage VC using the third voltage sensor 46 can be performed before the ON signal is output to the DC-DC converter 32 and when the OFF signal is output to the relay 36 on the positive electrode side. Furthermore, the program in the relay diagnostic device 40 is designed to diagnose the presence or absence of a malfunction (the ON-fixing anomaly) in the relay 36 on the positive electrode side by causing the program to proceed to the next step according to the value of the detected voltage VC before the ON signal is output to the DC-DC converter 32. For example, if the voltage VC detected by the third voltage sensor 46 has the value 0 (V), it is diagnosed that the relay 36 on the positive electrode side is in the ON-fixing anomaly state. Functioning of the second embodiment As shown in Fig. 8, in step S2 the control system 50 detects the voltage VC using the third voltage sensor 46 before the ON signal is output to the DC-DC converter 32 and when the OFF signal is output to the relay 36 on the positive electrode side. The program then proceeds to step S4. In step S4, the control system 50 determines whether the voltage VC is not equal to 0 (V). If the voltage VC is not equal to 0 (V) (S4: YES), the program is instructed to proceed to step S10. If the voltage VC is equal to 0 (V) (S4: NO), the program is instructed to proceed to step S34. In a phase before the DC-DC converter 32 transitions to the ON state, a state in which relay 36 on the positive electrode side is in the OFF state is considered the normal state. In this state, when the voltage VC has the value 0 (V), the control system 50 diagnoses an ON-fixing anomaly at relay 36 on the positive electrode side, since relay 36 on the positive electrode side is in the ON state. As described above, in the second embodiment, a malfunction can be diagnosed at relay 36 on the positive electrode side in a phase before a transition. It should be noted that the measures in step S10 and the subsequent steps are similar to those of the first embodiment, and a redundant description of them is omitted. Modification examples It is understood that the embodiments of the invention are not limited to the first and second embodiments and can be modified in various ways, as long as they do not deviate from the scope of the invention. As shown in Fig. 9, the hybrid vehicle 10, which has a relay diagnostic device 90, can be used as a modification example. It should be noted that configurations that are identical or similar to those of the first embodiment and the second embodiment are designated with the same reference numerals to avoid redundant descriptions. The relay diagnostic device 90 is an example of a relay diagnostic device for a vehicle. The relay diagnostic device 90 diagnoses the presence or absence of malfunctions (ON-fixing anomaly and OFF-fixing anomaly) in relay 36 on the positive electrode side and in relay 38 on the negative electrode side within a cycle. In an example, the relay diagnostic device 90 includes the first voltage sensor 42, the second voltage sensor 44, the third voltage sensor 46, and the control system 50. The relay diagnostic device 90 differs from the relay diagnostic device 40 of the first embodiment in that one configuration on the positive electrode side and one configuration on the negative electrode side are reversed. That is, relay 36 on the positive electrode side is an example of the second relay, and relay 38 on the negative electrode side is an example of the first relay. The first voltage sensor 42 is similar to that of the first embodiment. The third voltage sensor 46 detects the voltage VC, which is a voltage between the terminals of relay 38 on the negative electrode side. Specifically, the second voltage sensor 44 is connected to the wiring 33B between the relay 36 on the positive electrode side and the main battery 26, and to the wiring 35A between the relay 38 on the negative electrode side and the DC-DC converter 32. The second voltage sensor 44 detects the voltage VB, which is a potential difference between the first electrical energy line 33 between the relay 36 on the positive electrode side and the main battery 26, and the second electrical energy line 35 between the relay 38 on the negative electrode side and the DC-DC converter 32. Fig. 10 shows graphs GA, GB, GC, GD, GE, GF, and GG relating to the relay diagnostic device 90. Graph GA indicates the times at which the ON and OFF signals are sent to relay 38 on the negative electrode side. Graph GB indicates the times at which the ON and OFF signals are sent to relay 36 on the positive electrode side. Graph GC indicates the voltage VA. Graph GD indicates a state in which the voltage decreases when the DC-DC converter 32 is switched off. Graph GE indicates a state in which the voltage VA is maintained when relay 36 on the positive electrode side is switched off. Graph GF indicates the voltage VB. Graph GG indicates the voltage VC. It should be noted that graphs GA, GB, GC, GD, GE, GF, and GG exhibit tendencies similar to those of graphs G1, G2, G3, G4, G5, G6, and G7 with respect to the relay diagnostic device 40, and therefore a redundant description of them is omitted. Thus, according to the modification example, the relay diagnostic device 90 is also designed to diagnose the presence or absence of a malfunction (ON-fixing anomaly and OFF-fixing anomaly) in relay 36 on the positive electrode side and in relay 38 on the negative electrode side within a single cycle. The vehicle is not limited to the hybrid vehicle 10 and can also be an electric vehicle (EV). When diagnosing that the voltage VC is equal to 0 (V), the voltage can be considered to be 0 (V) even if the detected voltage is not equal to 0 (V), as long as the detected voltage is within a measurement error range with respect to 0 (V). Reference symbol list 10 Hybrid vehicle (example of a vehicle) 26 Main battery (example of an electrical energy storage unit) 32 DC-DC converter (example of a converter) 33 First electrical energy line 35 Second electrical energy line 36 Relay on the positive electrode side (example of a first relay) 38 Relay on the negative electrode side (example of a second relay) 40 Relay diagnostic device (example of a relay diagnostic device for vehicles) 42 First voltage sensor (example of a first detector) 44 Second voltage sensor (example of a second detector) 46 Third voltage sensor (example of a third detector) 50 Control system 73 Processor 74 Memory 90 Relay diagnostic device (example of a relay diagnostic device for vehicles) V1 Voltage V2 Voltage VA Voltage VB Voltage VC Voltage QUOTES INCLUDED IN THE DESCRIPTION This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature JP 2020 - 99 129 A

[0002] JP 2007 - 295 699 A

[0002] JP 2011 - 55 631 A

[0002]

Claims

Relay diagnostic device for a vehicle, wherein the relay diagnostic device is designed to diagnose the operation of a first relay and the operation of a second relay of the vehicle, wherein a first line for electrical energy provided with the first relay and a second line for electrical energy provided with the second relay couple an electrical energy storage unit and a converter, wherein the second line for electrical energy has a different polarity than the first line for electrical energy, wherein the relay diagnostic device comprises: - a first detector designed to detect a voltage of the converter; - a second detector designed to detect a voltage,which is a potential difference between the first electrical energy line between the first relay and the converter and the second electrical energy line between the second relay and the electrical energy storage unit; a third detector designed to detect a voltage between the terminals of the first relay; and a control system comprising a processor and memory, the control system being designed to control the converter, the first relay, and the second relay, and the control system being designed to perform the following actions: adjusting the voltage of the converter to a voltage of the electrical energy storage unit, outputting an ON signal to the first relay in a state where the converter is ON, and diagnosing an OFF-fixing anomaly at the first relay.if neither the voltage detected by the second detector nor the voltage detected by the third detector is detectable between the terminals, - outputting the ON signal to the second relay in a state where the converter and the first relay are switched on, - outputting an OFF signal to the converter and diagnosing an OFF-fixing anomaly at the second relay when the voltage at the first detector decreases, - diagnosing an ON-fixing anomaly at the second relay when the voltage at the first detector does not decrease after the OFF signal is output to the second relay, in a state where the converter is switched off and the first relay is switched on, and - diagnosing an ON-fixing anomaly at the first relay when the voltage detected by the third detector between the terminals has the value 0 (V) after the OFF signal is output to the first relay, in a state wherein which the converter is switched off and the second relay is switched off. Relay diagnostic device for the vehicle according to claim 1, wherein the control system is designed for the following measures: - detecting the voltage between the terminals by means of the third detector before the ON signal is output to the converter and when the OFF signal is output to the first relay, and - diagnosing an ON fixing anomaly at the first relay when the voltage between the terminals detected by the third detector has the value 0 (V).

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