JP2019184577A - Diagnostic device and method for diagnosis - Google Patents

Abstract

To provide a diagnostic device and a method for diagnosis which can make an overall diagnosis to find defects which is required for a configuration that employs a flying capacitor system.SOLUTION: A diagnostic device 100 includes: a capacitor 10, which can be connected to a first battery 200 in parallel; a plurality of first switches 1 for changing the connection state between a plurality of first batteries 200 and the capacitor 10; a detection circuit 20 having an AD converter 22, the detection circuit detecting the difference in the potential between terminals of the capacitor 10; a second switch 2 for changing the connection state between the capacitor 10 and the detection circuit 20; a third switch 3 for connecting terminals of the first switches 1 which are not connected to the first batteries 200 to one of the detection circuit 20 and another AD converter by bypassing the second switch 2; and a controller 60. The controller 60 diagnoses the first switches 1 and thereafter switches the capacitor 10 and the second switch 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a diagnostic apparatus and a diagnostic method.

  Conventionally, after charging the battery voltage to the capacitor, the battery is disconnected from the capacitor, and in that state, the voltage of the capacitor is detected by a voltage detection circuit, thereby indirectly measuring the battery voltage of the flying capacitor method. The device is known.

  In the above-described flying capacitor type battery monitoring device, it is known to perform failure diagnosis of a switch that switches connection between a capacitor and a voltage detection circuit. For example, in Patent Document 1, if the voltage detection circuit detects a voltage even though the switch for switching the connection between the capacitor and the voltage detection circuit is instructed to turn off, it is determined that the switch has a short circuit failure. .

JP 2014-182089 A

  In the flying capacitor type battery monitoring device, it is desirable not only to diagnose the failure of the switch that switches the connection between the capacitor and the voltage detection circuit, but also to perform the failure diagnosis of the switch that switches the connection between the battery and the capacitor. However, Patent Document 1 does not discuss a switch for switching the connection between a battery and a capacitor, and failure diagnosis of the capacitor.

  An object of the present invention made in view of such a viewpoint is to provide a diagnostic apparatus and a diagnostic method capable of comprehensively performing a failure diagnosis required in a configuration employing a flying capacitor system.

In order to solve the above problem, a diagnostic apparatus according to a first aspect is
A capacitor connectable in parallel to each first battery of a plurality of first batteries connected in series;
A plurality of first switches for switching a connection state between the plurality of first batteries and the capacitor;
A detection circuit having an AD converter and detecting a potential difference between both terminals of the capacitor;
A second switch for switching a connection state between the capacitor and the detection circuit;
A third switch connectable to a terminal of the first switch not connected to the first battery and one of the detection circuit or another AD converter, bypassing the second switch;
A control unit for controlling the first switch, the second switch, and the third switch,
The controller is
Based on the detection result of one of the detection circuit or the other AD converter when the first switch is turned on or off with the second switch turned off and the third switch turned on, Diagnosing the first switch;
After the diagnosis of the first switch, the third switch is turned off, the second switch is turned on from off, and the capacitor and the second switch are diagnosed.

In order to solve the above problem, a diagnostic method according to a second aspect is:
A capacitor that can be connected in parallel to each first battery of a plurality of first batteries connected in series, a plurality of first switches that switch a connection state between the plurality of first batteries and the capacitor, and an AD converter A detection circuit for detecting a potential difference between both terminals of the capacitor, a second switch for switching a connection state between the capacitor and the detection circuit, and a terminal of the first switch not connected to the first battery And a third switch capable of connecting the detection circuit or one of the other AD converters by bypassing the second switch,
Based on the detection result of one of the detection circuit or the other AD converter when the first switch is turned on or off with the second switch turned off and the third switch turned on, Diagnosing the first switch;
After the diagnosis of the first switch, turning off the third switch, turning the second switch from off to on, and diagnosing the capacitor and the second switch.

In order to solve the above problem, a diagnostic device according to a third aspect is:
A capacitor connectable in parallel to each first battery of a plurality of first batteries connected in series;
A plurality of first switches for switching a connection state between the plurality of first batteries and the capacitor;
A first detection circuit for detecting a potential difference between both terminals of the capacitor;
A second switch for switching a connection state between the capacitor and the first detection circuit;
A second detection circuit capable of detecting the voltage of a terminal of the first switch not connected to the first battery by bypassing the second switch;
A third switch for switching a connection state between the first switch and the second detection circuit;
A control unit for controlling the first switch, the second switch, and the third switch,
The controller is
The first switch is diagnosed based on the detection result of the second detection circuit when the first switch is turned on or off with the second switch turned off and the third switch turned on. And
After the diagnosis of the first switch, the third switch is turned off, the second switch is turned on from off, and the capacitor and the second switch are diagnosed based on the detection result of the first detection circuit.

  According to the diagnosis apparatus according to the first aspect, it is possible to comprehensively perform failure diagnosis required in the configuration employing the flying capacitor method.

  According to the diagnosis method according to the second aspect, it is possible to comprehensively perform failure diagnosis required in the configuration employing the flying capacitor method.

  According to the diagnosis apparatus according to the third aspect, it is possible to comprehensively perform failure diagnosis required in the configuration employing the flying capacitor method.

It is a block diagram which shows the structural example of the diagnostic apparatus which concerns on one Embodiment. FIG. 2 is a block diagram illustrating an example of a configuration of a constant voltage circuit of FIG. It is a flowchart which shows an example of the procedure of the diagnostic method by the diagnostic apparatus which concerns on one Embodiment. It is a block diagram for demonstrating the diagnosis 1-1. It is a block diagram for demonstrating diagnosis 1-2. It is a figure which shows the timing chart of the diagnosis 1-2. It is a block diagram for demonstrating the diagnosis 2. FIG. It is a figure which shows the timing chart of the diagnosis 2. FIG. It is a block diagram for demonstrating diagnosis 3-1. It is a figure which shows the timing chart of the diagnosis 3-1. It is a block diagram for demonstrating diagnosis 3-2. It is a figure which shows the timing chart of the diagnosis 3-2. It is a block diagram for demonstrating diagnosis 3-3. It is a figure which shows the timing chart of the diagnosis 3-3. It is a block diagram for demonstrating diagnosis 3-4. It is a figure which shows the timing chart of the diagnosis 3-4. It is a block diagram for demonstrating diagnosis 3-5. It is a figure which shows the timing chart of the diagnosis 3-5. It is a block diagram for demonstrating diagnosis 3-6. It is a figure which shows the timing chart of the diagnosis 3-6. It is a block diagram for demonstrating diagnosis 3-7. It is a figure which shows the timing chart of the diagnosis 3-7. It is a block diagram for demonstrating the diagnosis 4. FIG. It is a figure which shows the timing chart of the diagnosis 4. FIG. It is a flowchart which shows an example of the detailed procedure of step S3 and step S4 of FIG. It is a flowchart which shows an example of the detailed procedure of step S3 and step S4 of FIG. It is a flowchart which shows an example of the detailed procedure of step S3 and step S4 of FIG. It is a block diagram which shows the structural example of the diagnostic apparatus which concerns on a modification.

  Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

  As illustrated in FIG. 1, a diagnostic device 100 according to an embodiment is connected to first batteries 200A to 200E. The diagnostic device 100 and the first batteries 200A to 200E may be mounted on a vehicle such as a vehicle equipped with an internal combustion engine such as a gasoline engine or a diesel engine, or a hybrid vehicle capable of running with the power of both the internal combustion engine and the electric motor. .

  The first batteries 200A to 200E may be included in the battery pack. The battery pack may include the diagnostic device 100. The battery pack may include a BMS (Battery Management System). The diagnostic device 100 may function as a BMS or may be included in the BMS.

  In the example shown in FIG. 1, a first battery 200A, a first battery 200B, a first battery 200C, a first battery 200D, and a first battery 200E are connected in series. Hereinafter, the first batteries 200 </ b> A to 200 </ b> E may be collectively referred to as the first battery 200 when it is not necessary to distinguish them.

  In the example shown in FIG. 1, the five first batteries 200 are connected in series, but the number of the first batteries 200 is not limited to this. Any number of the first battery 200 may be connected in series.

  The first battery 200 may be a secondary battery having a wide SOC (State Of Charge) bandwidth. The SOC bandwidth of the first battery 200 may be, for example, 10 to 90%. The first battery 200 is, for example, a lithium ion battery or a nickel hydride battery, but is not limited thereto, and may be another secondary battery.

  Diagnostic device 100 includes first switches 1A to 1K, second switches 2A and 2B, fourth switch 4, capacitor 10, resistor 11, detection circuit 20, constant voltage circuit 30, and capacitor voltage detection circuit. 40, a sub detection circuit 50, a control unit 60, and a storage unit 70.

  The capacitor 10 can be connected in parallel to the first batteries 200A to 200E via the first switches 1A to 1K. The capacitor 10 can be charged with electric power supplied from the first battery 200. The detection circuit 20 can detect a potential difference between both terminals of the capacitor 10 charged by the first battery 200. That is, the capacitor 10 functions as a flying capacitor in voltage measurement of the flying capacitor method.

  First switches 1 </ b> A to 1 </ b> K switch the connection state between first battery 200 and capacitor 10 in accordance with a command from control unit 60. When the first switches 1A to 1K are controlled to be turned on, both ends thereof are conducted. When the first switches 1A to 1K are controlled to be turned off, both ends thereof are insulated. In FIG. 1, the control lines from the control unit 60 to the first switches 1 </ b> A to 1 </ b> K are omitted in order to improve readability.

  The first switch 1A, the first switch 1C, the first switch 1E, the first switch 1G, and the first switch 1J are respectively a first battery 200A, a first battery 200B, a first battery 200C, a first battery 200D, and a first switch. The connection state between the positive electrode of the battery 200E and the first node 10A is switched. The first node 10 </ b> A is a node connected to one end of the capacitor 10.

  The first switch 1B, the first switch 1D, the first switch 1F, the first switch 1H, and the first switch 1K are respectively a first battery 200A, a first battery 200B, a first battery 200C, a first battery 200D, and a first switch. The connection state between the negative electrode of the battery 200E and the second node 10B is switched. The second node 10 </ b> B is a node connected to the other end of the capacitor 10.

  Hereinafter, the first switches 1 </ b> A to 1 </ b> K may be collectively referred to as the first switch 1 when it is not necessary to distinguish between them. The first switch 1 may be a mechanical switch having a movable part. The first switch 1 may have a contact, and may be configured to switch between a conduction state and an insulation state by opening and closing the contact. The first switch 1 may be, for example, an electromagnetic relay.

  The second switches 2 </ b> A and 2 </ b> B switch the connection state between the capacitor 10, the detection circuit 20, and the sub detection circuit 50 in accordance with a command from the control unit 60. When the second switches 2A and 2B are controlled to be turned on, both ends thereof are conducted. When the second switches 2A and 2B are controlled to be turned off, both ends thereof are insulated. In FIG. 1, the control lines from the control unit 60 to the second switches 2A and 2B are not shown in order to improve readability.

  The second switch 2A switches the connection state between the first node 10A, the detection circuit 20, and the sub detection circuit 50. The second switch 2B switches the connection state between the second node 10B and the ground. The second switch 2A is also referred to as an upper second switch. The second switch 2B is also referred to as a lower second switch.

  Hereinafter, the second switches 2A and 2B may be collectively referred to as the second switch 2 when it is not necessary to distinguish between them. The second switch 2 may be a mechanical switch having a movable part. The 2nd switch 2 has a contact, and may be comprised so that a conduction | electrical_connection state and an insulation state may be switched by opening and closing a contact. The second switch 2 may be, for example, an electromagnetic relay.

  The fourth switch 4 switches the connection state between the first node 10 </ b> A and the resistor 11 in accordance with a command from the control unit 60. When the fourth switch 4 is controlled to be turned on, both ends thereof are conducted. When the fourth switch 4 is controlled to be turned off, both ends thereof are insulated. The fourth switch 4 may be a mechanical switch having a movable part. The fourth switch 4 may have a contact, and may be configured to switch between a conduction state and an insulation state by opening and closing the contact. The fourth switch 4 may be, for example, an electromagnetic relay. In FIG. 1, the control line from the control unit 60 to the fourth switch 4 is omitted in order to improve readability.

  The resistor 11 is connected to the fourth switch 4 at one end and grounded at the other end. The fourth switch 4 is controlled so as to be off in normal times. When the fourth switch 4 is turned on, the capacitor 10 is discharged via the resistor 11. That is, the fourth switch 4 and the resistor 11 constitute a discharge circuit for discharging the charge charged in the capacitor 10.

  The detection circuit 20 can detect a potential difference between both terminals of the capacitor 10 in a state where the second switch 2 is on. The detection circuit 20 includes an operational amplifier 21 and an AD converter 22. The detection circuit 20 can detect a potential difference between both terminals of the capacitor 10 based on an input to the operational amplifier 21.

  The operational amplifier 21 is connected to a negative input terminal and an output terminal to constitute a voltage follower. The voltage follower including the operational amplifier 21 functions as a buffer and outputs the voltage input to the detection circuit 20 to the AD converter 22.

  Note that the voltage follower configured by the operational amplifier 21 is disposed in front of the AD converter 22 is an example, and the configuration of the detection circuit 20 is not limited thereto. Instead of the voltage follower, an amplifier having an amplification factor different from 1 may be arranged in front of the AD converter 22. That is, an amplifier circuit having an arbitrary amplification factor, such as a voltage follower with an amplification factor of 1 or an amplifier having an amplification factor different from that of the amplification factor 1, may be disposed in front of the AD converter 22.

  The AD converter 22 has an AD input terminal 22A. The AD converter 22 converts an analog voltage input from the voltage follower configured by the operational amplifier 21 to the AD input terminal 22 </ b> A into a digital signal corresponding to the analog voltage and outputs the digital signal to the control unit 60.

  The AD converter 22 further has AD input terminals 22B and 22C. The AD input terminal 22B is connected to the first node 10A via the third switch 3A and the resistor 41. The AD input terminal 22B is grounded via a resistor 42. The AD input terminal 22C is connected to the second node 10B via the third switch 3B and the resistor 43. The AD input terminal 22C is grounded via a resistor 44.

  The AD converter 22 converts the analog voltage input to the AD input terminal 22 </ b> B into a digital signal corresponding to the analog voltage and outputs the digital signal to the control unit 60. The AD converter 22 converts the analog voltage input to the AD input terminal 22 </ b> C into a digital signal corresponding to the analog voltage and outputs the digital signal to the control unit 60.

  The constant voltage circuit 30 has a control terminal 30A and an output terminal 30B. The constant voltage circuit 30 outputs a constant voltage from the output terminal 30B in response to a control signal input from the control unit 60 to the control terminal 30A. The constant voltage circuit 30 can output a constant voltage to the capacitor 10. In the present embodiment, the constant voltage circuit 30 outputs a constant voltage when a high signal is input from the control unit 60 to the control terminal 30A, and stops outputting the constant voltage when a low signal is input. To do.

  FIG. 2 shows an example of the configuration of the constant voltage circuit 30. The constant voltage circuit 30 includes a power supply terminal 30C not shown in FIG. 1 in addition to the control terminal 30A and the output terminal 30B.

  The constant voltage circuit 30 is supplied with a power supply voltage from the power supply terminal 30C. As shown in FIG. 2, the constant voltage circuit 30 is supplied with the power supply voltage from the second battery 300 to the power supply terminal 30 </ b> C via the voltage conversion circuit 400, for example.

  The second battery 300 is a battery different from the first battery 200. The second battery 300 may be a secondary battery having a narrower SOC bandwidth than the first battery 200. The second battery 300 is, for example, a lead storage battery, but is not limited thereto, and may be another secondary battery. Although not particularly illustrated, the second battery 300 is connected in parallel to the first battery 200 and supplies power to the auxiliary equipment of the vehicle.

  The voltage conversion circuit 400 converts the voltage supplied from the second battery 300 and supplies the converted voltage to the power supply terminal 30 </ b> C of the constant voltage circuit 30. For example, the voltage conversion circuit 400 steps down the voltage of 12V supplied from the second battery 300 to 5V and supplies the voltage to the power supply terminal 30C of the constant voltage circuit 30.

  As shown in FIG. 2, the constant voltage circuit 30 includes an NPN transistor 31, a PNP transistor 32, a capacitor 33, resistors 34 to 38, and a diode 39.

  When a high signal is received from the control unit 60 at the control terminal 30A of the constant voltage circuit 30, the base voltage of the NPN transistor 31 rises and the NPN transistor 31 is turned on. When the NPN transistor 31 is turned on, the base voltage of the PNP transistor 32 is lowered and the PNP transistor 32 is turned on. When the PNP transistor 32 is turned on, a current can be supplied from the output terminal 30B to the first node 10A. For example, when the second switch 2B shown in FIG. 1 is on, the capacitor 10 can be charged by the current supplied from the output terminal 30B of the constant voltage circuit 30. At this time, a constant voltage that is reduced by a voltage drop caused by the resistor 34 and the PNP transistor 32 from the power supply voltage input to the power supply terminal 30C is supplied to the output terminal 30B of the constant voltage circuit 30. Thus, the PNP transistor 32 can function as a changeover switch that switches the connection state between the second battery 300 and the capacitor 10 in accordance with a command from the control unit 60. When the PNP transistor 32 is turned on, the voltage from the second battery 300 can be applied to the capacitor 10. The diode 39 has a cathode connected to the first battery 200 side so as to prevent a current from flowing backward from the first battery 200.

  The constant voltage circuit 30 thus generates a constant voltage based on the power supply voltage supplied from the secondary battery having a narrow SOC bandwidth, for example, the second battery 300 that is a lead storage battery. Thereby, the constant voltage circuit 30 can generate | occur | produce the constant voltage more than predetermined magnitude | size stably.

  The constant voltage output from the constant voltage circuit 30 is the maximum voltage that can be supplied by the first batteries 200A to 200E connected in series, that is, the positive terminal of the first battery 200A and the negative terminal of the first battery 200E. The voltage may be smaller than the voltage between. For example, when the maximum voltage that can be supplied by each first battery 200 is 2.4V, the maximum voltage that can be supplied by the first batteries 200A to 200E connected in series is 12V. In this case, the constant voltage output from the constant voltage circuit 30 can be smaller than 12V. Thereby, when the constant voltage which the constant voltage circuit 30 outputs is input into the operational amplifier 21 of the detection circuit 20, the possibility that the operational amplifier 21 will fail can be reduced.

  The constant voltage output from the constant voltage circuit 30 may be larger than the maximum voltage that can be supplied by each first battery 200. For example, when the maximum voltage that can be supplied to each first battery 200 is 2.4V, the constant voltage output from the constant voltage circuit 30 can be greater than 2.4V. Thereby, the control part 60 can confirm that the said voltage is not the voltage supplied from the 1st battery 200, when detecting the voltage charged in the capacitor 10 from the constant voltage circuit 30 in the diagnostic process.

  The diagnostic device 100 can perform a failure diagnosis using the constant voltage output from the constant voltage circuit 30. If the voltage of the first battery 200 that is the detection target is used as the reference voltage when the diagnosis apparatus 100 performs the failure diagnosis, when the battery capacity of the first battery 200 is reduced, the capacitor 10, Failures such as the first switch 1 and the second switch 2 may not be correctly detected. However, since the diagnostic apparatus 100 according to the present embodiment performs failure diagnosis using the constant voltage output from the constant voltage circuit 30, the capacitor 10, the first switch 1, and the first switch are not dependent on the first battery 200. 2 The state of the switch 2 or the like can be diagnosed.

  A description will be given with reference to FIG. 1 again.

  The capacitor voltage detection circuit 40 is a circuit for detecting the voltage at both terminals of the capacitor 10, that is, the voltage at the first node 10 </ b> A and the second node 10 </ b> B without using the operational amplifier 21 of the detection circuit 20.

  The capacitor voltage detection circuit 40 includes third switches 3A and 3B, a resistor 41, a resistor 42, a resistor 43, and a resistor 44.

  The third switch 3 </ b> A switches the connection state between the first node 10 </ b> A and the resistor 41 in accordance with a command from the control unit 60. The third switch 3 </ b> B switches the connection state between the second node 10 </ b> B and the resistor 43 in accordance with a command from the control unit 60. When the third switches 3A and 3B are controlled to be turned on, both ends thereof are conducted. When the third switches 3A and 3B are controlled to be turned off, both ends thereof are insulated. In FIG. 1, the control lines from the control unit 60 to the third switches 3 </ b> A and 3 </ b> B are not shown in order to improve readability.

  The third switch 3 </ b> A can be connected to the first node 10 </ b> A and the AD input terminal 22 </ b> B by bypassing the operational amplifier 21 by being controlled to be turned on. The third switch 3 </ b> B can be connected to the second node 10 </ b> B and the AD input terminal 22 </ b> C by bypassing the operational amplifier 21 by being turned on. The first node 10A is connected to terminals of the first switch 1A, the first switch 1C, the first switch 1E, the first switch 1G, and the first switch 1J that are not connected to the first battery 200. The second node 10B is connected to terminals of the first switch 1B, the first switch 1D, the first switch 1F, the first switch 1H, and the first switch 1K that are not connected to the first battery 200.

  Hereinafter, the third switches 3 </ b> A and 3 </ b> B may be collectively referred to as the third switch 3 when it is not necessary to distinguish between them. The third switch 3 may be a mechanical switch having a movable part. The third switch 3 may have a contact, and may be configured to switch between a conduction state and an insulation state by opening and closing the contact. The third switch 3 may be, for example, an electromagnetic relay.

  The resistor 41 is connected to the first node 10A via the third switch 3A at one end. The resistor 41 is connected to the AD input terminal 22B of the AD converter 22 and the resistor 42 at the other end.

  The resistor 42 is connected to the AD input terminal 22B and the resistor 41 of the AD converter 22 at one end. The resistor 42 is grounded at the other end.

  The resistor 43 is connected at one end to the second node 10B via the third switch 3B. The resistor 43 is connected to the AD input terminal 22C of the AD converter 22 and the resistor 44 at the other end.

  The resistor 44 is connected to the AD input terminal 22C and the resistor 43 of the AD converter 22 at one end. The resistor 44 is grounded at the other end.

  When the constant voltage circuit 30 is off and the third switch 3A is on, any of the first switch 1A, the first switch 1C, the first switch 1E, the first switch 1G, and the first switch 1J is on. The voltage on the positive side of the first battery 200 connected to the first switch 1 that is turned on is divided by the resistor 41 and the resistor 42 and supplied to the AD input terminal 22 </ b> B of the AD converter 22.

  When the constant voltage circuit 30 is off and the third switch 3A is on, the first switch 1A, the first switch 1C, the first switch 1E, the first switch 1G, and the first switch 1J are all off. Then, 0V is supplied to the AD input terminal 22B of the AD converter 22 through the resistor 42 that is grounded.

  When the constant voltage circuit 30 is off and the third switch 3B is on, if any of the first switch 1B, the first switch 1D, the first switch 1F, and the first switch 1H is on, it is on. The voltage on the negative side of the first battery 200 connected to the first switch 1 is divided by the resistors 43 and 44 and supplied to the AD input terminal 22 </ b> C of the AD converter 22.

  When the constant voltage circuit 30 is off and the third switch 3B is on, if the first switch 1B, the first switch 1D, the first switch 1F, and the first switch 1H are all off, they are grounded. 0V is supplied to the AD input terminal 22 </ b> C of the AD converter 22 through the resistor 44.

  When the third switch 3 </ b> A is off, 0 V is supplied to the AD input terminal 22 </ b> B of the AD converter 22 through the grounded resistor 42. When the third switch 3B is off, 0V is supplied to the AD input terminal 22C of the AD converter 22 via the grounded resistor 44.

  The sub detection circuit 50 can detect a potential difference between both terminals of the capacitor 10 in a state where the second switch 2 is turned on. The sub detection circuit 50 is a circuit for diagnosing whether or not the operational amplifier 21 of the detection circuit 20 is operating normally. The sub detection circuit 50 operates together when the detection circuit 20 operates.

  The sub detection circuit 50 includes an operational amplifier 51 and an AD converter 52.

  The operational amplifier 51 is connected to a negative input terminal and an output terminal to constitute a voltage follower. The voltage follower including the operational amplifier 51 functions as a buffer and outputs the voltage input to the sub detection circuit 50 to the AD converter 52.

  The AD converter 52 converts an analog voltage input from the voltage follower configured by the operational amplifier 51 into a digital signal corresponding to the analog voltage and outputs the digital signal to the control unit 60.

  FIG. 1 shows a configuration in which the AD converter 52 is an AD converter different from the AD converter 22.

  The control unit 60 is communicably connected to each component of the diagnostic device 100 by wired or wireless communication. The control unit 60 may output a control instruction to each component unit or obtain information from each component unit.

  The controller 60 controls on / off of the first switch 1, the second switch 2, the third switch 3, and the fourth switch 4. The control unit 60 controls on / off of the constant voltage circuit 30. When the control unit 60 turns on the constant voltage circuit 30, the constant voltage circuit 30 can supply a constant voltage to the first node 10A.

  The control unit 60 can acquire a digital signal corresponding to the analog voltage input to the AD input terminals 22A, 22B, and 22C from the AD converter 22 of the detection circuit 20. The control unit 60 can acquire a digital signal corresponding to the analog voltage input to the sub detection circuit 50 from the AD converter 52 of the sub detection circuit 50.

  The control unit 60 may be configured by a processor such as a CPU (Central Processing Unit) that executes a program that defines a control procedure. When the diagnostic device 100 is mounted on a vehicle, the control unit 60 may be configured as an ECU (Electric Control Unit or Engine Control Unit) of the vehicle.

  The storage unit 70 is connected to the control unit 60 and stores information acquired from the control unit 60. The storage unit 70 may function as a working memory for the control unit 60. The storage unit 70 may store a program executed by the control unit 60. The storage unit 70 is configured by, for example, a semiconductor memory, but is not limited thereto, and may be configured by a magnetic storage medium or may be configured by another storage medium. The storage unit 70 may be included as part of the control unit 60.

  In the present embodiment, the first switch 1, the capacitor 10, and the second switch 2 </ b> A can function as a detection connection circuit that enables the first battery 200 to be connected to the detection circuit 20. The constant voltage circuit 30 can function as a diagnostic connection circuit for enabling the second battery 300 to be connected to the detection connection circuit.

  The control unit 60 of the diagnostic apparatus 100 can diagnose the components in the diagnostic apparatus 100 according to the procedure shown in the flowchart of FIG. The control unit 60 can diagnose whether or not a failure has occurred in the first switch 1, the second switch 2, the capacitor 10, and the operational amplifier 21.

  First, the control unit 60 performs a diagnosis mainly using the capacitor voltage detection circuit 40 (step S1). In step S1, the control unit 60 diagnoses the first switch 1 other than the first switch 1K that is the first switch 1 at the lowest stage connected to the ground, that is, the first switches 1A to 1J. Hereinafter, the diagnosis in step S1 of the control unit 60 is referred to as “diagnosis 1”.

  Subsequently, the control unit 60 performs a diagnosis mainly using the detection circuit 20 (step S2). In step S2, the control unit 60 diagnoses the first switch 1K at the lowest stage. Hereinafter, the diagnosis in step S2 of the control unit 60 is referred to as “diagnosis 2”.

  Subsequently, the control unit 60 performs diagnosis mainly using the constant voltage circuit 30 (step S3). In step S3, the control unit 60 diagnoses the capacitor 10, the second switch 2, the operational amplifier 21, and the first switch 1K at the lowest stage. Hereinafter, the diagnosis in step S3 of the control unit 60 is referred to as “diagnosis 3”.

  Subsequently, the control unit 60 performs diagnosis mainly using the sub detection circuit 50 (step S4). In step S4, the control unit 60 diagnoses the operational amplifier 21. Hereinafter, the diagnosis in step S4 of the control unit 60 is referred to as “diagnosis 4”.

  When it is determined that a failure has occurred in any of the components of the diagnostic device 100 at any stage of diagnosis 1 to diagnosis 4, the control unit 60 sets a failure flag and stops subsequent diagnosis processing. You can do it.

  In the present embodiment, the control unit 60 controls the on / off of the first switch 1, the second switch 2, the third switch 3, the fourth switch 4, and the constant voltage circuit 30, and the first switch 1, Although the description will be made assuming that both the two switches 2, the capacitor 10, and the operational amplifier 21 are diagnosed, the present invention is not limited to this configuration. For example, the processor may include a control unit 60 and a diagnosis unit. In this case, the control unit 60 executes on / off control of the first switch 1, the second switch 2, the third switch 3, the fourth switch 4, and the constant voltage circuit 30, and the diagnosis unit performs the first switch. Diagnosis of the first switch 2, the second switch 2, the capacitor 10, and the operational amplifier 21 may be performed.

  Hereinafter, details of diagnosis 1 to diagnosis 4 will be described.

[Diagnosis 1]
Diagnosis 1 includes the following two diagnoses.
Diagnosis 1-1: Short fault diagnosis of the first switches 1A to 1J Diagnosis 1-2: Open fault diagnosis of the first switches 1A to 1J

(Diagnosis 1-1)
Diagnosis 1-1 is a short fault diagnosis of the first switches 1A to 1J other than the first switch 1K at the lowest stage. The diagnosis 1-1 will be described with reference to the block diagram shown in FIG. In FIG. 4, some of the components of the diagnostic apparatus 100 shown in FIG.

  In diagnosis 1-1, the control unit 60 controls the first switch 1 to be off, the second switch 2 to be off, and the third switch 3 to be on. Further, the control unit 60 controls the constant voltage circuit 30 shown in FIG. 1 to be turned off.

  At this time, if any of the first switches 1A to 1J has a short circuit failure, the AD converter 22 is connected to the first switch 1 having a short circuit failure at either the AD input terminal 22B or 22C. The voltage of the first battery 200 is detected.

  FIG. 4 shows a state in which the first switch 1A is short-circuited as an assumed failure site. In this case, even if the first switch 1A is controlled to be turned off, the first switch 1A remains short-circuited, so the AD input terminal 22B of the AD converter 22 detects the voltage on the positive side of the first battery 200A.

  When none of the first switches 1A to 1J has a short circuit failure, the AD converter 22 detects 0 V at both the AD input terminals 22B and 22C.

  That is, when the controller 60 detects a voltage other than 0V in a state where the first switch 1 is turned off, the second switch 2 is turned off, the third switch 3 is turned on, and the constant voltage circuit 30 is turned off, It can be determined that any of the switches 1A to 1J may have a short circuit failure. The control unit 60 may determine that a voltage other than 0 V has been detected when a voltage equal to or higher than a predetermined threshold is detected.

  In the present embodiment, the diagnostic device 100 executes the diagnosis 1-1 as the first diagnosis, and checks whether there is a short circuit failure in the first switches 1A to 1J. This is because if any one of the first switches 1A to 1J is short-circuited, a relatively high voltage is applied to the operational amplifier 21 when the second switch 2 is turned on, and the operational amplifier 21 may fail. is there.

  The controller 60 executes the diagnosis 1-1 before executing the process of turning on the second switch 2, and if it is determined that any of the first switches 1A to 1J has a short fault, the second switch 2 Is maintained off, and the subsequent diagnostic processing is stopped. Thereby, the diagnostic apparatus 100 can reduce the risk of failure of the operational amplifier 21 due to the application of a relatively high voltage.

(Diagnosis 1-2)
The diagnosis 1-2 is an open failure diagnosis of the first switches 1A to 1J other than the first switch 1K in the lowermost stage. The diagnosis 1-2 will be described with reference to the block diagram shown in FIG. 5 and the timing chart shown in FIG. In FIG. 5, some of the components of the diagnostic apparatus 100 shown in FIG.

  In the diagnosis 1-2, the control unit 60 controls the second switch 2 to be off and the third switch 3 to be on. Further, the control unit 60 controls the constant voltage circuit 30 shown in FIG. 1 to be turned off.

  The controller 60 sequentially turns on / off the first switch 1 connected to both terminals of the first battery 200 from the low potential side of the first battery 200 toward the high side. That is, the controller 60 first turns on / off the first switches 1J and 1K in a state where all the first switches 1 are off. Subsequently, the control unit 60 turns on / off the first switches 1G and 1H. The control unit 60 continues this process until the first switches 1A and 1B are turned on / off.

  The controller 60 sequentially turns the first switch 1 connected to both terminals of the first battery 200 from the high potential side to the low side rather than from the low potential side to the high side. It may be turned on / off.

  FIG. 6 shows a timing chart when the control unit 60 turns on / off the first switches 1A and 1B. When the first switches 1A and 1B are turned on, the control unit 60 measures the voltages input to the AD input terminals 22B and 22C at predetermined measurement timings t1 and t2. Thereafter, the controller 60 turns off the first switches 1A and 1B. The control unit 60 may calculate an average value of the voltages measured at t1 and t2 to obtain a detected voltage value.

  In the example shown in FIG. 6, the control unit 60 measures the voltage at two timings t1 and t2, but the measurement timing is not limited to this. The control unit 60 may measure the voltage at one timing or may measure the voltage at three or more timings. When the voltage is measured at a plurality of timings, the control unit 60 may calculate an average value and use it as a detected voltage value. Regarding the calculation of the number of measurement timings and the average value, the same concept applies to the diagnosis 2 and later, and therefore, the description about the calculation of the number of measurement timings and the average value is omitted in the description after the diagnosis 2.

  At this time, if any one of the first switches 1A to 1J has an open failure, the AD converter 22 is connected to the first switch 1 when the first switch 1 having the open failure is turned on. 0 V is detected at the AD input terminal 22B or 22C.

  FIG. 5 shows a state in which the first switches 1A and 1B are turned on when the first switch 1A has an open failure as an assumed failure site. In this case, since the first switch 1A remains open even if it is controlled to be on, the AD input terminal 22B of the AD converter 22 detects 0V. Since the first switch 1B is normally turned on, the AD input terminal 22C of the AD converter 22 detects the voltage on the negative side of the first battery 200A divided by the resistors 43 and 44.

  The timing chart of FIG. 6 shows two states, the case where the first switch 1A is normal and the case where an open failure occurs. As shown in FIG. 6, when the first switch 1 </ b> A is normal, the AD input terminal 22 </ b> B of the AD converter 22 detects the voltage on the positive side of the first battery 200 </ b> A divided by the resistor 41 and the resistor 42. When the first switch 1A has an open failure, the AD input terminal 22B of the AD converter 22 detects 0V.

  That is, when the controller 60 sequentially turns on / off the first switch 1 with the second switch 2 turned off, the third switch 3 turned on, and the constant voltage circuit 30 turned off, If 0V is detected in a state where any one of the first switches 1A to 1J is turned on, it may be determined that there is a possibility that the first switch 1 has an open failure. The control unit 60 may determine that 0 V has been detected when a voltage equal to or lower than a predetermined threshold is detected.

[Diagnosis 2]
Diagnosis 2 is an open failure diagnosis of the first switch 1K which is the lowest switch of the first switch 1. The diagnosis 2 will be described with reference to the block diagram shown in FIG. 7 and the timing chart shown in FIG. In FIG. 7, some of the components of the diagnostic device 100 shown in FIG.

  In the diagnosis 2, the control unit 60 controls the third switch 3 and the constant voltage circuit 30 shown in FIG. In addition, before the start of diagnosis 2, the control unit 60 turns off all of the first switch 1 and the second switch 2.

  FIG. 8 shows a timing chart in diagnosis 2. The controller 60 turns on / off the first switches 1J and 1K connected to both terminals of the first battery 200E, which is the battery having the lowest potential among the first batteries 200. Thereafter, when the second switch 2 is turned on, the control unit 60 measures the voltage input to the AD input terminal 22A of the AD converter 22 at predetermined measurement timings t1 to t4. Thereafter, the controller 60 turns off the second switch 2. The control unit 60 may calculate an average value of the voltages measured at t1 to t4 to obtain a detected voltage value.

  When the control unit 60 turns on the first switches 1J and 1K, when the first switches 1J and 1K are normal, the potential difference between both terminals of the capacitor 10 reaches the voltage of the first battery 200E as shown in FIG. To rise. Thereafter, even if the control unit 60 turns off the first switches 1J and 1K, the potential difference is maintained between both terminals of the capacitor 10. In this case, the control unit 60 detects a voltage corresponding to the voltage of the first battery 200E at predetermined measurement timings t1 to t4 after turning on the second switch.

  FIG. 7 shows a state where the first switch 1K has an open failure as an assumed failure site. In this case, since the first switch 1K remains open even when the first switches 1J and 1K are controlled to be on, the capacitor 10 is not charged, and the potential difference between both terminals of the capacitor 10 is shown in FIG. Thus, it remains at 0V. In this case, the control unit 60 detects 0 V at predetermined measurement timings t1 to t4 after turning on the second switch.

  Note that the capacitor 10 is not charged even if the first switch 1J, rather than the first switch 1K, has an open failure. However, when the first switch 1J has an open failure, an open failure is detected in the diagnosis 1-2, and the diagnosis process is stopped at that time. Therefore, when diagnosis 2 is executed and 0 V is detected at predetermined measurement timings t1 to t4, the control unit 60 may determine that there is a possibility that the first switch 1K has an open failure.

  Further, the sequence based on the timing chart shown in FIG. 8 is the same sequence as the sequence when the control unit 60 detects the voltage of the first battery 200 in the normal process. Therefore, the control unit 60 can execute the diagnosis 2 in the same sequence as the normal voltage detection sequence of the first battery 200.

[Diagnosis 3]
Diagnosis 3 includes the following seven diagnoses.
Diagnosis 3-1: Capacitor 10 leak or short fault diagnosis Diagnosis 3-2: Open fault diagnosis of the second switch 2 Diagnosis 3-3: Diagnosis of the output voltage of the operational amplifier 21 (0 V)
Diagnosis 3-4: Short failure diagnosis of the second switch 2A Diagnosis 3-5: Short failure diagnosis of the second switch 2B Diagnosis 3-6: Short failure diagnosis of the first switch 1K Diagnosis 3-7: Operational amplifier 21 Output voltage sticking diagnosis (5V)

(Diagnosis 3-1)
The diagnosis 3-1 diagnoses a leak failure or a short-circuit failure of the capacitor 10. The diagnosis 3-1 will be described with reference to the block diagram shown in FIG. 9 and the timing chart shown in FIG. As shown in FIG. 9, the failure diagnosis target of diagnosis 3-1 is a capacitor 10. In FIG. 9, some of the components of the diagnostic apparatus 100 shown in FIG.

  In the diagnosis 3-1, the control unit 60 controls the first switch 1 to be turned off. Further, the control unit 60 controls the third switch 3 shown in FIG. 1 to be turned off. Further, before the start of the diagnosis 3-1, the control unit 60 turns off the constant voltage circuit 30 and the second switch 2.

  FIG. 10 shows a timing chart in diagnosis 3-1. The control unit 60 outputs a high signal to the control terminal 30A, turns on the constant voltage circuit 30, and turns on the second switch 2. When the constant voltage circuit 30 and the second switch 2 are turned on, the control unit 60 measures the voltage input to the AD input terminal 22A of the AD converter 22 at predetermined measurement timings t1 to t4. Hereinafter, the measurement at the predetermined measurement timings t1 to t4 is also referred to as “measurement 1”.

  Thereafter, the control unit 60 outputs a low signal to the control terminal 30A to turn off the constant voltage circuit 30. When the constant voltage circuit 30 is turned off, the control unit 60 measures the voltage input to the AD input terminal 22A of the AD converter 22 at predetermined measurement timings t5 to t8. Hereinafter, the measurement at predetermined measurement timings t5 to t8 is also referred to as “measurement 2”.

  The controller 60 may match the conditions of the predetermined measurement timings t1 to t4 and t5 to t8 as much as possible with the conditions of the measurement timing when detecting the voltage of the first battery 200 in the normal process. For example, when the number of measurements in the normal process is four times and the four measurement values are averaged, the control unit 60 measures four times at the timings t1 to t4 in the measurement 1, and the four measurement values are obtained. May average. Moreover, the control part 60 may measure 4 times at the timing of t5-t8 also in the measurement 2, and may average 4 times of measured values. Further, the control unit 60, for example, a delay time from turning on the second switch 2 to starting measurement 2 is defined as a delay time from turning on the second switch 2 in normal processing to starting measurement. It may be the same time. As described above, the control unit 60 adjusts the conditions of the measurement timings t1 to t4 and t5 to t8 in the diagnosis 3-1 as much as possible to the measurement timing conditions when detecting the voltage of the first battery 200 in the normal process. Measurement 1 and measurement 2 can be performed with a small error. For measurements 1 to 6 shown in FIGS. 12, 14, 16, 18, 20, 22, and 24, the measurement timing conditions are measured when the voltage of the first battery 200 is detected in normal processing. It may be matched to the timing conditions as much as possible.

  When the control unit 60 turns on the constant voltage circuit 30 and the second switch 2, the capacitor 10 is charged by the constant voltage supplied from the constant voltage circuit 30 when the capacitor 10 is normal. In this case, in the measurement 1, the control unit 60 detects a voltage corresponding to the constant voltage supplied by the constant voltage circuit 30. Even when there is a leak failure in the capacitor 10, the capacitor 10 can be charged by the constant voltage supplied from the constant voltage circuit 30. In this case, in the measurement 1, the control unit 60 can detect a voltage corresponding to the constant voltage supplied by the constant voltage circuit 30. When the capacitor 10 has a short circuit failure, the capacitor 10 is not charged even if a constant voltage is supplied from the constant voltage circuit 30. In this case, in the measurement 1, the control unit 60 detects 0V.

  Subsequently, when the control unit 60 turns off the constant voltage circuit 30, when the capacitor 10 is normal, the capacitor 10 maintains a charged state. In this case, in the measurement 2, the control unit 60 detects a voltage corresponding to the constant voltage supplied by the constant voltage circuit 30. When there is a leak failure in the capacitor 10, the charge charged in the capacitor 10 decreases due to the leak. In this case, in the measurement 2, the control unit 60 detects a voltage smaller than the voltage detected in the measurement 1. Further, when there is a short circuit failure in the capacitor 10, in the measurement 2, the control unit 60 continues to detect 0V.

  When the voltage detected in measurement 1 is 0 V, the control unit 60 can determine that there is a possibility of a short circuit failure in the capacitor 10. The control unit 60 may determine that 0 V has been detected when a voltage equal to or lower than a predetermined threshold is detected.

  When the difference obtained by subtracting the voltage detected in measurement 2 from the voltage detected in measurement 1 is larger than a predetermined threshold, the control unit 60 can determine that the capacitor 10 may be leaking. The predetermined threshold value may be set to an appropriate value in consideration of voltage reading error, noise, and the like.

  In this way, the control unit 60 can determine that there is a possibility that a leak failure has occurred in the capacitor 10. As a result, the control unit 60 can reduce the possibility that the voltage of the first battery 200 is misread in the normal process due to a leakage failure of the capacitor 10 and the first battery 200 is overcharged.

(Diagnosis 3-2)
Diagnosis 3-2 is an open fault diagnosis of the second switch 2. The diagnosis 3-2 will be described with reference to the block diagram shown in FIG. 11 and the timing chart shown in FIG. As illustrated in FIG. 11, the failure diagnosis targets of the diagnosis 3-2 are the second switches 2A and 2B. In FIG. 11, some of the components of the diagnostic apparatus 100 shown in FIG.

  In the diagnosis 3-2, the control unit 60 controls the first switch 1 to be turned off. Further, the control unit 60 controls the third switch 3 shown in FIG. 1 to be turned off. Further, before the start of the diagnosis 3-2, the control unit 60 turns off the constant voltage circuit 30 and the second switch 2.

  FIG. 12 shows a timing chart in the diagnosis 3-2. The control unit 60 controls on / off of the constant voltage circuit 30 and on / off of the second switch 2 at the same timing as the timing chart shown in FIG. Moreover, the control part 60 performs the measurement 1 in the measurement timing t1-t4 similar to the timing chart shown in FIG. Further, the control unit 60 performs the measurement 2 at the measurement timings t5 to t8 similar to the timing chart shown in FIG.

  When the control unit 60 turns on the constant voltage circuit 30 and the second switch 2, the capacitor 10 is charged by the constant voltage supplied from the constant voltage circuit 30 when the second switch 2 </ b> B is normal. In this state, when the second switch 2 </ b> A is normal, in the measurement 1, the control unit 60 can detect a voltage corresponding to the constant voltage supplied by the constant voltage circuit 30. Further, since the capacitor 10 remains charged even when the constant voltage circuit 30 is turned off, the control unit 60 can detect a voltage corresponding to the constant voltage supplied by the constant voltage circuit 30 also in the measurement 2. .

  When the control unit 60 turns on the constant voltage circuit 30 and the second switch 2, the capacitor 10 is not charged by the constant voltage circuit 30 if the second switch 2 </ b> B has an open failure. In this case, the control unit 60 detects 0 V in measurement 1 and measurement 2.

  When the control unit 60 turns on the constant voltage circuit 30 and the second switch 2, if the second switch 2A has an open failure, the voltage of the first node 10A is not applied to the AD input terminal 22A of the AD converter 22. . In this case, since the input terminal on the positive side of the operational amplifier 21 is grounded via a resistance component of about several kilohms due to a wraparound of a peripheral circuit, the control unit 60 performs 0V in measurement 1 and measurement 2. Is detected.

  When the voltage detected in measurement 1 and measurement 2 is 0 V, the control unit 60 can determine that the second switch 2 may have an open failure. The control unit 60 may determine that 0 V has been detected when a voltage equal to or lower than a predetermined threshold is detected.

(Diagnosis 3-3)
The diagnosis 3-3 diagnoses whether the output voltage of the operational amplifier 21 is stuck to 0V. The diagnosis 3-3 will be described with reference to the block diagram shown in FIG. 13 and the timing chart shown in FIG. As illustrated in FIG. 13, the failure diagnosis target of the diagnosis 3-3 is an operational amplifier 21. In FIG. 13, some of the components of the diagnostic apparatus 100 shown in FIG.

  In the diagnosis 3-3, the control unit 60 controls the first switch 1 to be turned off. Further, the control unit 60 controls the third switch 3 shown in FIG. 1 to be turned off. Further, before the start of the diagnosis 3-3, the control unit 60 turns off the constant voltage circuit 30 and the second switch 2.

  FIG. 14 shows a timing chart in the diagnosis 3-3. The control unit 60 controls on / off of the constant voltage circuit 30 and on / off of the second switch 2 at the same timing as the timing chart shown in FIG. Moreover, the control part 60 performs the measurement 1 in the measurement timing t1-t4 similar to the timing chart shown in FIG. Further, the control unit 60 performs the measurement 2 at the measurement timings t5 to t8 similar to the timing chart shown in FIG.

  When the control unit 60 turns on the constant voltage circuit 30 and the second switch 2, the capacitor 10 is charged by the constant voltage supplied from the constant voltage circuit 30. In this state, when the operational amplifier 21 is normal, the operational amplifier 21 outputs a voltage corresponding to the constant voltage supplied by the constant voltage circuit 30 to the AD input terminal 22 </ b> A of the AD converter 22. Therefore, the control unit 60 can detect a voltage corresponding to the constant voltage supplied by the constant voltage circuit 30 in the measurement 1. Further, since the capacitor 10 remains charged even when the constant voltage circuit 30 is turned off, the control unit 60 can detect a voltage corresponding to the constant voltage supplied by the constant voltage circuit 30 also in the measurement 2. .

  When the output of the operational amplifier 21 is stuck at 0V, the operational amplifier 21 outputs 0V even when a voltage corresponding to the constant voltage supplied by the constant voltage circuit 30 is input. Therefore, when the output of the operational amplifier 21 is stuck at 0V, the control unit 60 detects 0V in measurement 1 and measurement 2. When the output of the operational amplifier 21 sticks to 0V, the output of the detection circuit 20 also sticks to 0V.

  When the voltage detected in measurement 1 and measurement 2 is 0V, the control unit 60 can determine that the output of the operational amplifier 21 may be stuck at 0V. The control unit 60 may determine that 0 V has been detected when a voltage equal to or lower than a predetermined threshold is detected.

(Diagnosis 3-4)
The diagnosis 3-4 is a short failure diagnosis of the second switch 2A. The diagnosis 3-4 will be described with reference to the block diagram shown in FIG. 15 and the timing chart shown in FIG. As shown in FIG. 15, the failure diagnosis target of diagnosis 3-4 is the second switch 2A. In FIG. 15, some of the components of the diagnostic apparatus 100 shown in FIG.

  In the diagnosis 3-4, the control unit 60 controls the first switch 1 to be turned off. Further, the control unit 60 controls the third switch 3 shown in FIG. 1 to be turned off. Further, before the start of the diagnosis 3-4, the control unit 60 turns off the constant voltage circuit 30 and the second switch 2.

  FIG. 16 shows a timing chart in diagnosis 3-4. The control unit 60 controls on / off of the constant voltage circuit 30 and on / off of the second switch 2 at the same timing as the timing chart shown in FIG. Moreover, the control part 60 performs the measurement 1 in the measurement timing t1-t4 similar to the timing chart shown in FIG. Further, the control unit 60 performs the measurement 2 at the measurement timings t5 to t8 similar to the timing chart shown in FIG.

  When the second switch 2 is turned off, the control unit 60 measures the voltage input to the AD input terminal 22A of the AD converter 22 at predetermined measurement timings t9 to t12. Hereinafter, the measurement at the predetermined measurement timings t9 to t12 is also referred to as “measurement 3”.

  The input terminal on the positive side of the operational amplifier 21 is grounded to the ground through a resistance component of about several kilohms due to wraparound of peripheral circuits. For this reason, when the control unit 60 turns off the second switch, when the second switch 2A is normal, the input voltage of the operational amplifier 21 gradually decreases due to current leakage through the resistance component. In this case, the control unit 60 detects a voltage smaller than the voltage detected in the measurement 2 in the measurement 3.

  If the second switch 2A is short-circuited, the second switch 2A remains short-circuited even if the control unit 60 performs control to turn off the second switch 2. In this case, the input voltage of the operational amplifier 21 does not change even when the control unit 60 performs control to turn off the second switch 2. Therefore, the control unit 60 detects a voltage equivalent to the voltage detected in the measurement 2 in the measurement 3.

  When the difference obtained by subtracting the voltage detected in measurement 3 from the voltage detected in measurement 1 or measurement 2 is zero, the control unit 60 can determine that there is a possibility of a short failure in the second switch 2A. The control unit 60 may determine that the difference is zero when the difference obtained by subtracting the voltage detected in measurement 3 from the voltage detected in measurement 1 or measurement 2 is equal to or less than a predetermined threshold.

(Diagnosis 3-5)
Diagnosis 3-5 is a short failure diagnosis of the second switch 2B. The diagnosis 3-5 will be described with reference to the block diagram shown in FIG. 17 and the timing chart shown in FIG. As shown in FIG. 17, the failure diagnosis target of diagnosis 3-5 is the second switch 2B. In FIG. 17, some of the components of the diagnostic apparatus 100 shown in FIG.

  In the diagnosis 3-5, the control unit 60 controls the first switch 1 to be turned off. Further, the control unit 60 controls the third switch 3 shown in FIG. 1 to be turned off. Further, before the start of the diagnosis 3-5, the control unit 60 turns off the constant voltage circuit 30 and the second switch 2.

  FIG. 18 shows a timing chart in diagnosis 3-5. The control unit 60 outputs a high signal to the control terminal 30A to turn on the constant voltage circuit 30, and outputs a low signal to the control terminal 30A to turn off the constant voltage circuit 30 when a predetermined time elapses. The controller 60 turns off the constant voltage circuit 30, turns on the second switch 2, and then turns off the second switch 2. When the second switch 2 is turned on, the control unit 60 measures the voltage input to the AD input terminal 22A of the AD converter 22 at predetermined measurement timings t13 to t16. Hereinafter, the measurement at predetermined measurement timings t13 to t16 is also referred to as “measurement 4”.

  When the control unit 60 turns on the constant voltage circuit 30 with the second switch 2 turned off, the capacitor 10 is not charged. This is because the second node 10B is not grounded when the second switch 2B is normal. Therefore, after that, after the control unit 60 turns off the constant voltage circuit 30, when the second switch 2 is turned on, the control unit 60 detects 0V.

  When the second switch 2B is short-circuited, the capacitor 10 is charged when the control unit 60 turns on the constant voltage circuit 30 with the second switch 2 turned off. This is because when the second switch 2B is short-circuited, the second node 10B is grounded. Therefore, when the control unit 60 turns off the constant voltage circuit 30 and then turns on the second switch 2, the control unit 60 detects a voltage corresponding to the constant voltage supplied by the constant voltage circuit 30.

  When the voltage detected in the measurement 4 is not 0 V, the control unit 60 can determine that there is a possibility of a short circuit failure in the second switch 2B. The control unit 60 may determine that a voltage other than 0 V is detected when a voltage equal to or higher than a predetermined threshold is detected.

(Diagnosis 3-6)
Diagnosis 3-6 is a short fault diagnosis of the first switch 1K which is the lowest switch of the first switch 1. The diagnosis 3-6 will be described with reference to the block diagram shown in FIG. 19 and the timing chart shown in FIG. As illustrated in FIG. 19, the failure diagnosis target of the diagnosis 3-6 is the first switch 1K. In FIG. 19, some of the components of the diagnostic apparatus 100 shown in FIG.

  In diagnosis 3-6, the control unit 60 controls the first switch 1 to be turned off. Further, the control unit 60 controls the third switch 3 shown in FIG. 1 to be turned off. In addition, the controller 60 turns off the constant voltage circuit 30 and the second switch 2 before starting diagnosis 3-6.

  FIG. 20 shows a timing chart in diagnosis 3-6. The control unit 60 controls on / off of the constant voltage circuit 30 and on / off of the second switch 2 at the same timing as the timing chart shown in FIG. Further, the control unit 60 performs the measurement 4 at the measurement timings t13 to t16 similar to the timing chart illustrated in FIG.

  When the control unit 60 turns on the constant voltage circuit 30 with the second switch 2 turned off, the capacitor 10 is not charged. This is because the second node 10B is not grounded when the first switch 1K is normal. Therefore, after that, after the control unit 60 turns off the constant voltage circuit 30, when the second switch 2 is turned on, the control unit 60 detects 0V.

  When the first switch 1K has a short circuit failure, the control unit 60 turns on the constant voltage circuit 30 with the second switch 2 turned off, so that the capacitor 10 is charged. This is because the second node 10B is grounded when the first switch 1K is short-circuited. Therefore, when the control unit 60 turns off the constant voltage circuit 30 and then turns on the second switch 2, the control unit 60 detects a voltage corresponding to the constant voltage supplied by the constant voltage circuit 30.

  When the voltage detected in measurement 4 is not 0 V, the control unit 60 can determine that there is a possibility of a short circuit failure in the first switch 1K. The control unit 60 may determine that a voltage other than 0 V is detected when a voltage equal to or higher than a predetermined threshold is detected.

(Diagnosis 3-7)
The diagnosis 3-7 diagnoses whether the output voltage of the operational amplifier 21 is stuck to the power supply voltage (for example, 5V). The diagnosis 3-7 will be described with reference to the block diagram shown in FIG. 21 and the timing chart shown in FIG. As illustrated in FIG. 21, the failure diagnosis target of diagnosis 3-7 is an operational amplifier 21. In FIG. 21, some of the components of the diagnostic apparatus 100 shown in FIG.

  In the diagnosis 3-7, the control unit 60 controls the first switch 1 to be turned off. Further, the control unit 60 controls the third switch 3 shown in FIG. 1 to be turned off.

  FIG. 22 shows a timing chart in diagnosis 3-7. The controller 60 measures the voltage input to the AD input terminal 22A of the AD converter 22 at predetermined measurement timings t17 to t20 before turning on the constant voltage circuit 30 and the second switch 2. Hereinafter, the measurement at the predetermined measurement timings t17 to t20 is also referred to as “measurement 5”.

  Before the control unit 60 turns on the constant voltage circuit 30 and the second switch 2, the capacitor 10 is not charged. In this state, when the operational amplifier 21 is normal, the operational amplifier 21 outputs 0 V to the AD input terminal 22 </ b> A of the AD converter 22. Therefore, the control unit 60 can detect 0 V in the measurement 5.

  When the output of the operational amplifier 21 is stuck to a power supply voltage (for example, 5V), the operational amplifier 21 outputs 5V even if 0V is input to the operational amplifier 21. Therefore, when the output of the operational amplifier 21 is stuck to 5V, the control unit 60 detects 5V in the measurement 5. When the output of the operational amplifier 21 sticks to 5V, the output of the detection circuit 20 also sticks to 5V.

  When the voltage detected in the measurement 5 is the power supply voltage (for example, 5V) of the operational amplifier 21, the control unit 60 can determine that the output of the operational amplifier 21 may be stuck to 5V. The control unit 60 may determine that 5V has been detected when a voltage with a difference from 5V being equal to or less than a predetermined threshold is detected.

[Diagnosis 4]
Diagnosis 4 is a failure diagnosis of the operational amplifier 21. The diagnosis 4 will be described with reference to the block diagram shown in FIG. 23 and the timing chart shown in FIG. In FIG. 23, some components of the diagnostic apparatus 100 shown in FIG.

  In the diagnosis 4, the control unit 60 controls the third switch 3 and the constant voltage circuit 30 shown in FIG. Further, before the diagnosis 4 is started, the control unit 60 turns off all of the first switch 1 and the second switch 2.

  FIG. 24 shows a timing chart in diagnosis 4. The control unit 60 outputs a high signal to the control terminal 30A, turns on the constant voltage circuit 30, and turns on the second switch 2. When the constant voltage circuit 30 and the second switch 2 are turned on, the control unit 60 measures the voltage input to the AD input terminal 22A of the AD converter 22 at predetermined measurement timings t21 to t24. In diagnosis 4, when the control unit 60 turns on the constant voltage circuit 30 and the second switch 2, the voltage input to the AD input terminal of the AD converter 52 of the sub detection circuit 50 at the measurement timings t21 to t24. Also measure. Hereinafter, the measurement at predetermined measurement timings t21 to t24 is also referred to as “measurement 6”.

  When the control unit 60 turns on the constant voltage circuit 30 and the second switch 2, the capacitor 10 is charged by the constant voltage supplied from the constant voltage circuit 30. In this case, in the measurement 6, when the operational amplifier 21 is normal, the control unit 60 detects a voltage corresponding to the constant voltage supplied by the constant voltage circuit 30 from both the detection circuit 20 and the sub detection circuit 50. When there is an abnormality in the operational amplifier 21, the control unit 60 detects different voltages from the detection circuit 20 and the sub detection circuit 50 in the measurement 6.

  When the difference between the voltage acquired from the detection circuit 20 and the voltage acquired from the sub-detection circuit 50 is greater than a predetermined threshold in the measurement 6, the control unit 60 may indicate that the operational amplifier 21 may have failed. Can be judged.

[Procedures of diagnosis 3 and diagnosis 4]
An example of a detailed procedure of step S3 (diagnosis 3) and step S4 (diagnosis 4) shown in FIG. 3 will be described with reference to flowcharts shown in FIGS.

  The control unit 60 of the diagnostic apparatus 100 starts the flow shown in FIGS. 25 to 27 from the state in which the first switch 1, the second switch 2, the third switch 3, and the constant voltage circuit 30 are controlled to be turned off. .

  The controller 60 turns on the second switch 2 (step S101) and turns on the constant voltage circuit 30 (step S102), for example, as in the timing chart shown in FIG. The control unit 60 may execute step S101 and step S102 simultaneously. The controller 60 may execute step S102 before step S101.

  The controller 60 performs measurement 1 (step S103). The controller 60 turns off the constant voltage circuit 30 (step S104). The control unit 60 performs measurement 2 (step S105).

  Based on the results of measurement 1 and measurement 2, the control unit 60 determines whether a failure of diagnosis 3-1, diagnosis 3-2 or diagnosis 3-3 has been detected (step S106).

When the voltage detected in the measurement 1 is 0 V, the control unit 60 can determine that there is a possibility of any of the following failures. The control unit 60 may determine that 0 V is detected when a voltage equal to or lower than a predetermined threshold is detected.
・ Short circuit failure of capacitor 10 (diagnosis 3-1)
・ Open switch 2 failure (Diagnosis 3-2)
・ Standing the output of operational amplifier 21 to 0V (diagnosis 3-3)

  When the difference obtained by subtracting the voltage detected in measurement 2 from the voltage detected in measurement 1 is greater than a predetermined threshold, the control unit 60 may determine that the capacitor 10 may be leaking (Diagnosis 3− 1).

  When the failure of the diagnosis 3-1, the diagnosis 3-2, or the diagnosis 3-3 is detected (Yes in step S106), the control unit 60 sets a failure flag (step S107) and ends the diagnosis process.

  When the failure of the diagnosis 3-1, the diagnosis 3-2, or the diagnosis 3-3 is not detected (No in step S106), the control unit 60 proceeds to step S108.

  The controller 60 turns off the second switch 2 (step S108) and executes the measurement 3 (step S109), for example, as in the timing chart shown in FIG.

  The control unit 60 determines whether a failure of the diagnosis 3-4 has been detected based on the results of the measurement 1 to the measurement 3 (step S110).

  When the difference obtained by subtracting the voltage detected in measurement 3 from the voltage detected in measurement 1 or measurement 2 is zero, the control unit 60 can determine that the second switch 2A may have a short fault (diagnosis 3). -4). The control unit 60 may determine that the difference is zero when the difference obtained by subtracting the voltage detected in measurement 3 from the voltage detected in measurement 1 or measurement 2 is equal to or less than a predetermined threshold.

  When the failure of diagnosis 3-4 is detected (Yes in step S110), the control unit 60 sets a failure flag (step S111) and ends the diagnosis process.

  When the failure of the diagnosis 3-4 is not detected (No in Step S110), the control unit 60 proceeds to Step S112.

  The controller 60 turns on the fourth switch 4 and discharges the capacitor 10 (step S112).

  The controller 60 turns on the constant voltage circuit 30 after turning it on (step S113) and turns on the second switch 2 (step S114), for example, as in the timing chart shown in FIG. The control unit 60 performs measurement 4 (step S115).

  Based on the result of measurement 4, the control unit 60 determines whether a failure of the diagnosis 3-5 or the diagnosis 3-6 has been detected (step S116).

When the voltage detected in the measurement 4 is not 0 V, the control unit 60 can determine that there is a possibility of any of the following failures. The control unit 60 may determine that a voltage other than 0 V is detected when a voltage equal to or higher than a predetermined threshold is detected.
・ Short circuit failure of 2nd switch 2B (diagnosis 3-5)
・ Short circuit failure of the first switch 1K (diagnosis 3-6)

  When the failure of diagnosis 3-5 or diagnosis 3-6 is detected (Yes in step S116), the control unit 60 sets a failure flag (step S117) and ends the diagnosis process.

  When the failure of diagnosis 3-5 or diagnosis 3-6 is not detected (No in step S116), the control unit 60 proceeds to step S118.

  The control unit 60 turns off the second switch 2 (step S118).

  The controller 60 turns on the fourth switch 4 to discharge the capacitor 10 (step S119). When the diagnosis 3-5 or the diagnosis 3-6 has not failed, the capacitor 10 is not charged, so step S119 can be omitted.

  For example, as shown in the timing chart of FIG. 22, the control unit 60 performs the measurement 5 in a state where the constant voltage circuit 30 and the second switch 2 are off (step S120).

  The controller 60 turns on the constant voltage circuit 30 (step S121) and turns on the second switch 2 (step S122), for example, as in the timing chart shown in FIG. The control unit 60 may execute step S121 and step S122 at the same time. The control unit 60 may execute step S122 before step S121.

  The control unit 60 performs measurement 6 (step S123).

  The control unit 60 determines whether a failure of the diagnosis 3-7 or the diagnosis 4 is detected based on the results of the measurement 5 and the measurement 6 (step S124).

  When the voltage detected in the measurement 5 is the power supply voltage (for example, 5V) of the operational amplifier 21, the control unit 60 can determine that the output of the operational amplifier 21 may be stuck to 5V (diagnosis 3-7). . The control unit 60 may determine that 5V has been detected when a voltage with a difference from 5V being equal to or less than a predetermined threshold is detected.

  When the difference between the voltage acquired from the detection circuit 20 and the voltage acquired from the sub-detection circuit 50 is greater than a predetermined threshold in the measurement 6, the control unit 60 may indicate that the operational amplifier 21 may have failed. Can be determined (diagnosis 4).

  When the failure of diagnosis 3-7 or diagnosis 4 is detected (Yes in step S124), the control unit 60 sets a failure flag (step S125) and ends the diagnosis process.

  When the failure of the diagnosis 3-7 or the diagnosis 4 is not detected (No in step S124), the control unit 60 ends the diagnosis process.

  The controller 60 may perform control so as to stop the subsequent use of the first battery 200 when the failure flag is set and the diagnosis process is terminated in step S107, step S111, step S117, or step S125.

  The timing of failure determination in step S106, step S110, step S116, and step S124 is an example, and is not limited to this.

For example, the following failure determination in step S106 may be performed when measurement 1 is performed in step S103.
・ Short circuit failure of capacitor 10 (diagnosis 3-1)
・ Open switch 2 failure (Diagnosis 3-2)
・ Standing the output of operational amplifier 21 to 0V (diagnosis 3-3)

  For example, the failure determination in step S106 may be performed together with the failure determination in step S110 after performing measurement 3 in step S109.

  For example, the failure determination of diagnosis 3-7 in step S124 may be performed at the stage where measurement 5 is performed in step S120.

  In the present embodiment, the detection circuit 20 has been described as detecting a potential difference between both terminals of the capacitor 10. However, the detection circuit 20 may detect a discharge current from the capacitor 10.

  According to the diagnostic apparatus 100 according to the present embodiment, the diagnostic apparatus 100 includes a capacitor 10 that functions as a flying capacitor, a first switch 1 that switches a connection state between the first battery 200 and the capacitor 10, a capacitor 10, and a detection circuit. The second switch 2 that switches the connection state with the second switch 2 is diagnosed. Thereby, the diagnostic apparatus 100 according to the present embodiment can comprehensively perform failure diagnosis required in the configuration employing the flying capacitor method.

  Further, according to the diagnostic device 100 according to the present embodiment, when the diagnostic device 100 detects a short failure of the first switch 1, the diagnostic device 100 maintains the state in which the second switch 2 is turned off, and the capacitor 10 and the second The diagnosis of the switch 2 can be stopped. As a result, it is possible to reduce the risk that the operational amplifier 21 will fail due to a high voltage applied to the operational amplifier 21 of the detection circuit 20 due to a short circuit failure of the first switch 1.

  Further, according to the diagnostic device 100 according to the present embodiment, the diagnostic device 100 can apply a voltage to the capacitor 10 from the second battery 300 different from the first battery 200. The detection circuit 20 detects a potential difference or a discharge current after the control unit 60 turns on the PNP transistor 32 and applies a voltage from the second battery 300 to the capacitor 10. Then, the control unit 60 diagnoses at least one of the capacitor 10, the first switch 1K, and the second switch 2. Thereby, the diagnostic apparatus 100 according to the present embodiment can diagnose the states of the capacitor 10, the first switch 1K, and the second switch 2 without depending on the first battery 200 that is a voltage detection target.

  In addition, according to the diagnostic device 100 according to the present embodiment, a constant voltage can be supplied from the constant voltage circuit 30 to the capacitor 10 during failure diagnosis, so that a threshold value for determining whether or not there is a failure can be easily set. Yes.

(Modified example of configuration of diagnostic device)
FIG. 28 shows the configuration of a diagnostic apparatus 110 according to a modification. The diagnostic apparatus 110 according to the modification is different from the diagnostic apparatus 100 illustrated in FIG. 1 in that a detection circuit 23 is provided in addition to the detection circuit 20. Regarding the diagnostic apparatus 110 according to the modification, differences from the diagnostic apparatus 100 illustrated in FIG. 1 will be mainly described.

  The detection circuit 23 includes an AD converter 24. The AD converter 24 has AD input terminals 24A and 24B. The AD converter 24 converts the analog voltage input to the AD input terminal 24 </ b> A into a digital signal corresponding to the analog voltage and outputs the digital signal to the control unit 60. The AD converter 24 converts the analog voltage input to the AD input terminal 24B into a digital signal corresponding to the analog voltage and outputs the digital signal to the control unit 60.

  In the diagnostic device 110 according to the modification, the detection circuit 20 and the detection circuit 23 may function as a first detection circuit and a second detection circuit, respectively. The AD converter 22 and the AD converter 24 may function as a first AD converter and a second AD converter, respectively.

  In the diagnostic device 110 according to the modification, the third switch 3A is connected to the AD input terminal 24A of the AD converter 24 via the resistor 41. The third switch 3B is connected to the AD input terminal 24B of the AD converter 24 via the resistor 43.

  Even the configuration of the diagnostic apparatus 110 according to the modification may have the same effects as the diagnostic apparatus 100 illustrated in FIG.

  Although one embodiment according to the present disclosure has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various changes or modifications based on the present disclosure. Accordingly, it should be noted that these variations or modifications are included in the scope of the present disclosure. For example, the functions included in each means can be rearranged so as not to be logically contradictory, and a plurality of means can be combined into one or divided.

DESCRIPTION OF SYMBOLS 100,110 Diagnostic apparatus 1, 1A-1K 1st switch 2, 2A, 2B 2nd switch 3, 3A, 3B 3rd switch 4 4th switch 10 Capacitor (flying capacitor)
DESCRIPTION OF SYMBOLS 10A 1st node 10B 2nd node 11 Resistance 20 Detection circuit 21 Operational amplifier 22 AD converter 22A-22C AD input terminal 23 Detection circuit 24 AD converter 24A-24B AD input terminal 30 Constant voltage circuit 30A Control terminal 30B Output terminal 30C Power supply terminal 31 NPN transistor 32 PNP transistor 33 Capacitor 34, 35, 36, 37, 38 Resistance 39 Diode 40 Capacitor voltage detection circuit 41, 42, 43, 44 Resistance 50 Sub detection circuit 51 Operational amplifier 52 AD converter 60 Control unit 70 Storage unit 200, 200A -200E 1st battery 300 2nd battery 400 Voltage conversion circuit

Claims (11)

A capacitor connectable in parallel to each first battery of a plurality of first batteries connected in series;
A plurality of first switches for switching a connection state between the plurality of first batteries and the capacitor;
A detection circuit having an AD converter and detecting a potential difference between both terminals of the capacitor;
A second switch for switching a connection state between the capacitor and the detection circuit;
A third switch connectable to a terminal of the first switch not connected to the first battery and one of the detection circuit or another AD converter, bypassing the second switch;
A control unit for controlling the first switch, the second switch, and the third switch,
The controller is
Based on the detection result of one of the detection circuit or the other AD converter when the first switch is turned on or off with the second switch turned off and the third switch turned on, Diagnosing the first switch;
A diagnostic device that turns off the third switch, turns off the second switch from off to on after the diagnosis of the first switch, and diagnoses the capacitor and the second switch. The diagnostic device according to claim 1,
When the control unit detects a short-circuit failure of the first switch, the control unit maintains a state where the second switch is turned off, and stops diagnosis of the capacitor and the second switch. The diagnostic apparatus according to claim 1 or 2,
The detection circuit includes an amplification circuit that outputs to the AD converter, detects a potential difference between both terminals of the capacitor based on an input to the amplification circuit,
The third switch can be connected to a terminal of the first switch that is not connected to the first battery and the AD converter or the other AD converter, bypassing the amplifier circuit,
The controller detects one of the AD converter or the other AD converter when the first switch is turned on or off with the second switch turned off and the third switch turned on. A diagnostic device that diagnoses the first switch based on a result. In the diagnostic device according to any one of claims 1 to 3,
A switching switch for switching a connection state between the second battery different from the first battery and the capacitor;
The controller turns off the third switch after the diagnosis of the first switch, turns the second switch on from off, turns on the changeover switch, and applies a voltage from the second battery to the capacitor. A diagnostic device that diagnoses the capacitor and the second switch later based on a detection result of the detection circuit. The diagnostic apparatus according to claim 4, wherein
A diagnostic device further comprising a constant voltage circuit capable of generating a constant voltage from the second battery and outputting the constant voltage to the capacitor via the changeover switch. The diagnostic apparatus according to claim 5, wherein
The diagnostic device, wherein the constant voltage is smaller than a maximum voltage that can be supplied by the plurality of first batteries connected in series. The diagnostic device according to claim 5 or 6,
The diagnostic device, wherein the constant voltage is greater than a maximum voltage that the first battery can supply. In the diagnostic device according to any one of claims 1 to 7,
The first battery is a diagnostic device, which is a lithium ion battery or a nickel metal hydride battery. In the diagnostic device according to any one of claims 1 to 8,
The second battery is a diagnostic device, which is a lead storage battery, a lithium ion battery, or a nickel metal hydride battery. A capacitor that can be connected in parallel to each first battery of a plurality of first batteries connected in series, a plurality of first switches that switch a connection state between the plurality of first batteries and the capacitor, and an AD converter A detection circuit for detecting a potential difference between both terminals of the capacitor, a second switch for switching a connection state between the capacitor and the detection circuit, and a terminal of the first switch not connected to the first battery And a third switch that can be connected to the detection circuit or one of the other AD converters by bypassing the second switch,
Based on the detection result of one of the detection circuit or the other AD converter when the first switch is turned on or off with the second switch turned off and the third switch turned on, Diagnosing the first switch;
And a step of diagnosing the capacitor and the second switch after turning off the third switch and turning off the second switch after turning off the first switch. A capacitor connectable in parallel to each first battery of a plurality of first batteries connected in series;
A plurality of first switches for switching a connection state between the plurality of first batteries and the capacitor;
A first detection circuit for detecting a potential difference between both terminals of the capacitor;
A second switch for switching a connection state between the capacitor and the first detection circuit;
A second detection circuit capable of detecting the voltage of a terminal of the first switch not connected to the first battery by bypassing the second switch;
A third switch for switching a connection state between the first switch and the second detection circuit;
A control unit for controlling the first switch, the second switch, and the third switch,
The controller is
The first switch is diagnosed based on the detection result of the second detection circuit when the first switch is turned on or off with the second switch turned off and the third switch turned on. And
Diagnosing the capacitor and the second switch based on a detection result of the first detection circuit by turning off the third switch, turning off the second switch from off to on after the diagnosis of the first switch. apparatus.

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