Diagnostic device

Abstract

A diagnostic device detects an abnormality of an ideal diode in a circuit including a DC-DC converter, a storage battery, and an ideal diode connected to an output of the DC-DC converter on an anode side and connected to the storage battery on a cathode side, the diagnostic device including: an acquisition unit configured to acquire an abnormality of the ideal diode using the output of the DC-DC converter as a power source; acquiring an output voltage of the DCDC converter in a state in which the operation is stopped; and a determination unit that determines that the ideal diode is abnormal when the output voltage is equal to or greater than a predetermined threshold value.

Description

Technical Field

[0001] The present disclosure relates to a diagnostic device for diagnosing the control of an ideal diode. Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2022-174245 discloses an in-vehicle circuit using an ideal diode that realizes ideal diode characteristics with a forward voltage of zero and current flowing only in one direction.

[0003] The ideal diode is realized, for example, by a circuit including at least a metal-oxide-semiconductor field-effect transistor (hereinafter referred to as "MOSFET") that operates by synchronous rectification and a gate control function that switches the ON state (ON operation) / OFF state (OFF operation) of the MOSFET. Generally, as an ideal diode, a structure is known in which an ideal diode IC integrating the MOSFET and the gate control function, or an ideal diode controller IC integrating only the gate control function is used to control a discrete MOSFET.

[0004] In an ideal diode, if a symptom of so-called conduction latch occurs in which an abnormality occurs in the gate control function and the MOSFET remains in the ON state, an undesired reverse current is generated. This reverse current has a significant impact on the circuit using the ideal diode, so it is necessary to appropriately detect the symptom of conduction latch of the ideal diode. Summary of the Invention

[0005] The present disclosure has been made in view of the above problems, and an object thereof is to provide a diagnostic device that can appropriately detect the conduction latch of an ideal diode.

[0006] To solve the above problems, one aspect of the technology of the present disclosure is a diagnostic device,

[0007] detecting an abnormality of an ideal diode in a circuit including a DCDC converter, a storage battery, and an ideal diode that connects the output of the DCDC converter to the anode side and the storage battery to the cathode side,

[0008] comprising: an acquisition unit that acquires the output voltage of the DCDC converter in a state where the operation is stopped, for the ideal diode that uses the output of the DCDC converter as a power source; and a determination unit that determines that the ideal diode is abnormal when the output voltage is equal to or higher than a specified threshold value.

[0009] According to the diagnostic device of the present disclosure, when the power source of the ideal diode is acquired from the output of the DCDC converter, if the ideal diode conducts latch, even if the operation of the DCDC converter stops, the voltage of the storage battery appears on the output side. Therefore, based on the output voltage of the DCDC converter, the symptom of conduction latch of the ideal diode can be appropriately detected. Description of the Drawings

[0010] Hereinafter, with reference to the drawings, the features, advantages, technology, and industrial importance of exemplary embodiments of the present invention will be described. In the drawings, the same reference numerals denote the same components, where:

[0011] Figure 1 is a schematic configuration diagram of a circuit including a diagnostic device and an ideal diode according to an embodiment of the present disclosure.

[0012] Figure 2 is a flowchart of the diagnostic control of the ideal diode executed by the diagnostic device when IG is OFF.

[0013] Figure 3 is a flowchart of the diagnostic control of the ideal diode executed by the diagnostic device when IG is ON.

[0014] Figure 4 is a diagram showing another structure of the ideal diode. Detailed Description of the Embodiment

[0015] The diagnostic device of the present disclosure uses the fact that if the ideal diode conducts and latches, the anode side and the cathode side are electrically connected, and based on whether the voltage of the battery appears at the output of the DCDC converter via the ideal diode when the operation of the DCDC converter is stopped, the conduction latch of the ideal diode is detected.

[0016] Hereinafter, a detailed description of an embodiment of the present disclosure will be given with reference to the drawings.

[0017] Embodiment

[0018] Structure

[0019] Figure 1 is a block diagram showing a schematic configuration of a circuit including a diagnostic device 40 and an ideal diode 30 according to an embodiment of the present disclosure. Figure 1 The illustrated block diagram includes a DCDC converter 10, a battery 20, an ideal diode 30, and a diagnostic device 40. The DCDC converter 10, the battery 20, the ideal diode 30, and the diagnostic device 40 can be mounted on a vehicle or the like.

[0020] The DCDC converter 10 is a power converter capable of converting the power of a first voltage input from a power source (not shown) such as a generator or a battery into the power of a specified second voltage and outputting it. The DCDC converter 10 includes a step-up / step-down circuit composed of a switching element, a coil, etc., and a drive circuit for controlling the step-up / step-down operation composed of a microcomputer, etc.

[0021] The battery 20 is a secondary battery such as a lithium ion battery that is chargeable and dischargeable. The battery 20 is connected to the DCDC converter 10 via an ideal diode 30 so as to be chargeable by the power output by the DCDC converter 10. In addition, the battery 20 can supply the stored power to a predetermined device (not shown).

[0022] The ideal diode 30 is a diode that realizes ideal diode characteristics in which the forward voltage is zero and current flows in only one direction. The ideal diode 30 can significantly reduce power loss compared to a discrete rectifying diode. Figure 1 The illustrated ideal diode 30 is configured to include a discrete MOSFET 31 and an ideal diode controller IC 32 .

[0023] The ideal diode 30 is inserted between the DCDC converter 10 and the battery 20 in a state where the output of the DCDC converter 10 is connected on the anode side and the battery 20 is connected on the cathode side. More specifically, the source of the MOSFET 31 (the anode side of the body diode) is connected to the output of the DCDC converter 10, and the drain of the MOSFET 31 (the cathode side of the body diode) is connected to the battery 20.

[0024] The ideal diode controller IC32 is a driving circuit for controlling the gate voltage (GATE) of the MOSFET31 to control the electrical conduction / disconnection between the source and drain of the MOSFET31. The ideal diode controller IC32 has a reverse flow prevention function for controlling the MOSFET31 to be in a cut-off state when a current flowing back from the battery 20 (OUT) side to the DCDC converter 10 (IN) side is detected. The power supply (Vcc) of the ideal diode controller IC32 is connected to the output side of the DCDC converter 10, and the ideal diode controller IC32 can operate if a voltage is output from the DCDC converter 10 (power is supplied). In addition, when the ideal diode controller IC32 stops (is turned off) without power supply, the MOSFET31 is controlled to be in a cut-off state (normally closed).

[0025] Alternatively, the ideal diode 30 can be used Figure 1 The structure of the discrete MOSFET 31 and the ideal diode controller IC 32 is shown. The ideal diode 30 can also be used Figure 4 An ideal diode IC33 is shown in which a MOSFET and a controller are integrated into one chip.

[0026] The diagnostic device 40 is configured to diagnose the control of the ideal diode 30. The diagnostic device 40 acquires (inputs) at least information related to the operating state (operation, stop) of the DCDC converter 10 and information on the voltage that appears on the output side of the DCDC converter 10 (hereinafter referred to as "output voltage"). When the DCDC converter 10, the storage battery 20, the ideal diode 30, and the diagnostic device 40 are mounted on a vehicle, the diagnostic device 40 also acquires (inputs) an IG signal, which is information indicating the state of the ignition switch of the vehicle (IG-ON, IG-OFF). Then, based on the multiple pieces of information thus acquired, the diagnostic device 40 performs a diagnosis related to the determination of whether there is an abnormality in the control of the ideal diode 30. The diagnostic control executed by the diagnostic device 40 will be described in detail below.

[0027] Control

[0028] Next, with further reference to Figure 2 and Figure 3 a control implemented by the diagnostic device 40 according to an embodiment of the present disclosure will be described.

[0029] Figure 2 FIG. is a flowchart showing the processing steps of the diagnostic control of the ideal diode 30 executed by the diagnostic device 40 when the ignition switch is in the OFF state (IG-OFF). The Figure 2 illustrated diagnostic control of the ideal diode 30 starts when the ignition switch of the vehicle is in the off state (IG-OFF). The state of the ignition switch of the vehicle can be determined by the IG signal.

[0030] S201

[0031] The diagnostic device 40 determines whether the DCDC converter 10 (DDC) is in a stopped state. This determination can be made based on information related to the operating state of the DCDC converter 10 or the IG signal indicating the state of the ignition switch of the vehicle. If the diagnostic device 40 determines that the DCDC converter 10 is in a stopped state (S201, YES), the process proceeds to S202.

[0032] S202

[0033] The diagnostic device 40 acquires the output voltage of the DCDC converter 10 (DDC). This output voltage can be acquired, for example, by monitoring the output terminal of the DCDC converter 10 using a voltage sensor or the like. When the diagnostic device 40 obtains the output voltage of the DC-DC converter 10 (DDC), the process proceeds to step S203.

[0034] S203

[0035] The diagnostic device 40 determines whether the output voltage of the DCDC converter 10 is equal to or higher than a predetermined threshold value. This determination is made to confirm that the anode side and the cathode side of the ideal diode 30 are conducting and that the power supply voltage required for the operation of the ideal diode 30 is supplied. Therefore, this threshold value is set to a specified value that is larger than the voltage that would appear as the voltage on the output side of the DCDC converter 10 if the ideal diode 30 were in the cut-off state (however, a value smaller than the voltage of the storage battery 20).

[0036] When the diagnostic device 40 determines that the output voltage of the DCDC converter 10 is equal to or higher than the threshold value (S203, YES), the process proceeds to S204. On the other hand, when the diagnostic device 40 determines that the output voltage of the DCDC converter 10 is lower than the threshold value (S203, NO), the process proceeds to S205.

[0037] S204

[0038] The diagnostic device 40 determines that an abnormality has occurred in the control of the ideal diode 30. Specifically, the diagnostic device 40 shows that although the DCDC converter 10 has stopped, the output voltage of the DCDC converter 10 is a voltage value equal to or higher than the threshold value (equivalent to the voltage value of the storage battery 20). Therefore, the diagnostic device 40 determines that the ideal diode 30 has symptoms of conduction latch (the ideal diode 30 is operating). If the diagnostic device 40 determines that an abnormality has occurred in the control of the ideal diode 30, the diagnostic control of the ideal diode 30 at the time of IG-OFF ends.

[0039] S205

[0040] The diagnostic device 40 determines that the control of the ideal diode 30 is normal. Specifically, in the state where the DCDC converter 10 has stopped, the output voltage of the DCDC converter 10 indicates a value lower than the threshold value. Therefore, the diagnostic device 40 determines that the ideal diode 30 does not have symptoms of conduction latch (the ideal diode 30 is not operating). When the diagnostic device 40 determines that the control of the ideal diode 30 is normal, the diagnostic control of the ideal diode 30 at the time of IG-OFF ends.

[0041] Figure 3 is a flowchart showing the processing steps of the diagnostic control of the ideal diode 30 performed by the diagnostic device 40 at the time of IG-ON. This Figure 3 illustrated diagnostic control of the ideal diode 30 starts when the ignition switch of the vehicle is in the ON state (IG-ON). The state of the ignition switch of the vehicle can be determined by the IG signal.

[0042] S301

[0043] The diagnostic device 40 determines the diagnostic control of the ideal diode 30 performed at the time of IG-OFF ( Figure 2Whether the result of ( ) is "normal". This judgment is made to prevent misdiagnosis from occurring in the case of immediately turning on the IG after turning off the IG. As a reason for misdiagnosis, it can be cited that the output voltage of the DCDC converter 10 that has stopped operating has not sufficiently decreased during diagnosis.

[0044] When the diagnostic device 40 determines that the diagnostic result of the ideal diode 30 at the time of IG-OFF is normal (S301, yes), the process proceeds to S302. On the other hand, when the diagnostic device 40 determines that the diagnostic result of the ideal diode 30 at the time of IG-OFF is abnormal (S301, no), the process proceeds to S303.

[0045] S302

[0046] The diagnostic device 40 determines whether a specified time has elapsed since the ignition switch of the vehicle became off (IG-OFF). This judgment is made to wait for the output voltage that appears on the output side of the DCDC converter 10 during operation to sufficiently decrease after stopping until diagnosis can be performed. Therefore, this specified time is appropriately set based on the time required to discharge the charge of the capacitor connected to the output side of the DCDC converter 10, etc. That is, before the specified time has elapsed, no new determination is made, and the most recent normal diagnostic result is maintained. When the specified time has elapsed since the ignition switch of the vehicle became off (IG-OFF), the process proceeds to S303.

[0047] S303

[0048] The diagnostic device 40 determines whether the DCDC converter 10 (DDC) is in a stopped state. If the DCDC converter 10 is operating due to IG-ON, correct diagnosis cannot be performed, so this determination is made based on information related to the operating state of the DCDC converter 10.

[0049] If the diagnostic device 40 determines that the DCDC converter 10 is in a stopped state (S303, yes), the process proceeds to S304. On the other hand, if it is determined by the diagnostic device 40 that the DCDC converter 10 is already in an operating state (S303, no), the diagnosis at this timing is not performed, and the diagnostic control of the ideal diode 30 ends.

[0050] S304

[0051] The diagnostic device 40 obtains the output voltage of the DCDC converter 10 (DDC). This output voltage can be obtained, for example, by monitoring the output terminal of the DCDC converter 10 using a voltage sensor or the like. When the diagnostic device 40 obtains the output voltage of the DC-DC converter 10 (DDC), the process proceeds to step S305.

[0052] S305

[0053] The diagnostic device 40 determines whether the output voltage of the DCDC converter 10 is above a predetermined threshold value. This determination is made to confirm that the anode side and the cathode side of the ideal diode 30 are conducting and that the power supply voltage required for the operation of the ideal diode 30 is supplied. The threshold value is as described above.

[0054] When the diagnostic device 40 determines that the output voltage of the DCDC converter 10 is above the threshold value (S305, Yes), the process proceeds to S306. On the other hand, when the diagnostic device 40 determines that the output voltage of the DCDC converter 10 is less than the threshold value (S305, No), the process proceeds to S307.

[0055] S306

[0056] The diagnostic device 40 determines that an abnormality has occurred in the control of the ideal diode 30. Specifically, the diagnostic device 40 shows that although the DCDC converter 10 has stopped, the output voltage of the DCDC converter 10 is a voltage value above the threshold value (equivalent to the voltage value of the storage battery 20). Therefore, the diagnostic device 40 determines that the ideal diode 30 has symptoms of conduction latch (the ideal diode 30 is operating). If the diagnostic device 40 determines that an abnormality has occurred in the control of the ideal diode 30, the diagnostic control of the ideal diode 30 during IG-ON ends.

[0057] S307

[0058] The diagnostic device 40 determines that the control of the ideal diode 30 is normal. Specifically, in the state where the DCDC converter 10 has stopped, the output voltage of the DCDC converter 10 indicates less than the threshold value. Therefore, the diagnostic device 40 determines that the ideal diode 30 does not have symptoms of conduction latch (the ideal diode 30 is not operating). When the diagnostic device 40 determines that the control of the ideal diode 30 is normal, the diagnostic control of the ideal diode 30 during IG-ON ends.

[0059] Effect

[0060] According to one embodiment of the present disclosure described above, the power supply for the ideal diode 30 inserted between the DCDC converter 10 and the storage battery 20 is supplied from the output side of the DCDC converter 10. With this configuration, the diagnostic device 40 monitors the output voltage when the DCDC converter 10 has stopped. As a result, the diagnostic device 40 can detect symptoms of conduction latch in a state where the ideal diode 30 continuously conducts the anode side and the cathode side (faults of the ideal diode controller IC32, faults of the ideal diode IC33, loss of the reverse current prevention function, etc.).

[0061] In addition, in the diagnostic device 40 of the present embodiment, when symptoms of conduction latch of the ideal diode 30 are detected, by issuing a notification of abnormality via a display device, a sound device (not shown), etc., it is possible to alert the user of the vehicle, etc.

[0062] In addition, in the above embodiment, a structure in which the power supplies (Vcc) of the ideal diode controller IC 32 and the ideal diode IC 33 are connected to the output side of the DCDC converter 10 has been described, but they may also be connected to the storage battery 20. Even in a state where the ideal diode 30 is always operated using the power of the storage battery 20, the above-described diagnostic control of the ideal diode 30 can be performed to determine an abnormality of conduction latch.

[0063] As described above, one embodiment of the disclosed technology has been described. However, the present disclosure can be understood not only as a diagnostic device but also as a method executed by the diagnostic device, a program of the method, a computer-readable non-transitory storage medium storing the program, a vehicle including the diagnostic device, etc.

[0064] The diagnostic device of the present disclosure can be used for diagnosing the control of an ideal diode, etc.

Claims

1. A diagnostic device, wherein, Detect an abnormality of the ideal diode in a circuit including a DCDC converter, a storage battery, and an ideal diode that is connected to the output of the DCDC converter on the anode side and to the storage battery on the cathode side. Comprise: An acquisition unit that acquires the output voltage of the DCDC converter in a state where the operation has stopped, for the ideal diode powered by the output of the DCDC converter; and A determination unit that determines that the ideal diode is abnormal when the output voltage is equal to or higher than a prescribed threshold value.

2. The diagnostic device according to claim 1, wherein The circuit is mounted on a vehicle, and the acquisition unit acquires the output voltage after the operation of the DCDC converter has stopped and the ignition switch of the vehicle is set to the off state.

3. The diagnostic device according to claim 1 or 2, wherein The circuit is mounted on a vehicle, and the acquisition unit acquires the output voltage after the ignition switch of the vehicle is set to the on state and before the DCDC converter starts operating.

4. The diagnostic device according to claim 2 or 3, wherein When the determination unit determines that the ideal diode is normal when the ignition switch of the vehicle is set to the off state, no new determination is made for a prescribed time after this normal determination has been made.

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