Diagnostic system for power distribution circuits

Abstract

This invention provides a diagnostic system for power distribution circuits that can diagnose the circuit network using only the existing configuration. [Solution] A system for diagnosing a power distribution circuit that distributes power supplied from a DC-DC converter and an auxiliary battery to multiple loads, comprising: a plurality of switches provided between the DC-DC converter and the auxiliary battery and the plurality of loads; a switching unit for switching the connection state of the plurality of switches; and a diagnostic unit for diagnosing the power distribution circuit based on the connection state of the plurality of switches and changes in voltage and current in the power distribution circuit.

Description

Technical Field

[0001] The present disclosure relates to a system for diagnosing a power distribution circuit that distributes power supplied from a DCDC converter and an auxiliary battery to a plurality of loads.

Background Art

[0002] Patent Document 1 discloses a method for detecting a disconnection of a battery in a system equipped with an electric circuit interconnected by a DCDC converter. In the method described in this Patent Document 1, by using a periodic control signal generated by an oscillation circuit to intentionally increase and decrease the output voltage of the DCDC converter and detect the charge and discharge current of the battery, it is determined that the circuit network is normal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the system described in the above Patent Document 1, when diagnosing a circuit network to which a DCDC converter and a battery are connected, there is a problem that a new configuration for controlling the output voltage of the DCDC converter is required in addition to the existing configuration.

[0005] The present disclosure has been made in view of the above problems, and an object thereof is to provide a diagnostic system for a power distribution circuit that can diagnose a circuit network using only the existing configuration.

Means for Solving the Problems

[0006] To solve the above problems, one aspect of the disclosed technology is a system for diagnosing a power distribution circuit that distributes power supplied from a DC-DC converter and an auxiliary battery to multiple loads, comprising: a plurality of switches provided between the DC-DC converter and the auxiliary battery and the plurality of loads; a switching unit for switching the connection state of the plurality of switches; and a diagnostic unit for diagnosing the power distribution circuit based on the connection state of the plurality of switches and changes in voltage and current in the power distribution circuit. [Effects of the Invention]

[0007] According to the power distribution circuit diagnostic system of the present disclosure described above, a power distribution circuit to which a DC-DC converter and an auxiliary battery are connected can be diagnosed using only the existing configuration. [Brief explanation of the drawing]

[0008] [Figure 1] Schematic diagram of a diagnostic system for a power distribution circuit according to one embodiment of the present disclosure. [Figure 2A] Flowchart of the circuit diagnostic control process performed by the power distribution circuit diagnostic system. [Figure 2B] Flowchart of the circuit diagnostic control process performed by the power distribution circuit diagnostic system. [Modes for carrying out the invention]

[0009] The power distribution circuit diagnostic system disclosed herein diagnoses the normal / abnormal state of the power distribution circuit without using a method that intentionally lowers the output voltage of the DC-DC converter from a control signal, as in conventional technology, by utilizing existing sensors provided for auxiliary battery control and relays in the power distribution circuit. The embodiments of this disclosure will be described in detail below with reference to the drawings.

[0010] <Embodiment> [composition] Figure 1 is a schematic diagram illustrating a diagnostic system 100 for a power distribution circuit according to one embodiment of the present disclosure. The diagnostic system 100 for a power distribution circuit illustrated in Figure 1 comprises a DC-DC converter (DDC) 110, an auxiliary battery 120, a power distribution circuit (B-DC) 130, and a plurality of loads 140-150. In Figure 1, power lines through which power is exchanged are shown as solid lines, and control signal lines through which requests and instructions are exchanged are shown as dashed lines.

[0011] The power distribution circuit diagnostic system 100 shown in Figure 1 is installed in vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs).

[0012] The DC-DC converter (DDC) 110 is a power source that supplies power to the power distribution circuit 130. More specifically, this DC-DC converter 110 is a power converter that converts the voltage of the power input from a high-voltage battery (not shown) into the voltage required for multiple loads 140-150 and outputs it to the power distribution circuit 130.

[0013] The auxiliary battery 120 is a rechargeable secondary battery, such as a lithium-ion battery. This auxiliary battery 120 is a power source that can supply the power it stores to the power distribution circuit 130. The auxiliary battery 120 includes a battery 121, a switch (SW) 122, and an MCU 123.

[0014] The battery 121 is configured, for example, as a battery pack in which lithium-ion battery cells are connected in series. The switch (SW) 122 is a switching element that can switch the electrical connection state between the battery 121 and the power distribution circuit 130. A semiconductor relay or the like is used for this switch 122. The MCU 123 is a control unit, for example, composed of a microcontroller, which can acquire the state of the battery 121 (voltage, current, etc.) via sensors (not shown) and control the connection state of the switch 122. This MCU 123 is connected to the MCU 137 of the power distribution circuit 130, which will be described later, via a network such as CAN.

[0015] The power distribution circuit (B-DC) 130 is a control unit (body domain controller) for controlling the power supply to multiple loads 140-150 using a DC-DC converter (DDC) 110 and an auxiliary battery 120 as power sources. This power distribution circuit 130 includes a first switch (first SW) 131, a second switch (second SW) 132, a third switch (third SW) 133, a fourth switch (fourth SW) 134, multiple relays (RLY) 135-136, and an MCU 137.

[0016] The first switch (first SW) 131 is a switch element for switching the power supply state from the auxiliary battery 120 to the power distribution circuit (B-DC) 130. The fourth switch (fourth SW) 134 is a switch element for switching the power supply state from the DC-DC converter (DDC) 110 to the power distribution circuit (B-DC) 130. The second switch (second SW) 132 and the third switch (third SW) 133 are switch elements inserted in series between the first switch 131 and the fourth switch 134, with the rectification direction of the parasitic diodes reversed. Multiple relays (RLY) 135-136 are switch elements for switching the power supply state to loads 140 and 150, respectively. Semiconductor relays are used for the first switch 131, second switch 132, third switch 133, fourth switch 134, and multiple relays 135-136. The MCU137 is a control unit, for example, composed of a microcontroller, that can acquire voltage and current at predetermined locations in the power distribution circuit 130 via sensors (not shown), and control the connection status of the first switch 131, second switch 132, third switch 133, and fourth switch 134. Furthermore, the MCU137 performs diagnostics of the power distribution circuit 130 based on the voltage and current at predetermined locations in the power distribution circuit 130. The MCU137 is connected to the MCU123 of the auxiliary battery 120 via a network such as CAN, enabling communication.

[0017] The multiple loads 140-150 are on-board loads that consume power by driving electronic control units (ECUs) and actuators (ACTs) installed in the vehicle. These multiple loads 140-150 operate on power supplied from the DC-DC converter 110 and / or from the auxiliary battery 120.

[0018] Note that the number of relays (RLY) 135-136 and loads 140-150 mounted on the vehicle is not limited to the number shown in Figure 1.

[0019] [control] Next, referring further to FIGS. 2A and 2B, the control performed by the diagnostic system 100 of the power distribution circuit according to the present embodiment will be described. FIGS. 2A and 2B are flowcharts for explaining the processing procedures of circuit diagnostic control executed by the MCU 137 of the power distribution circuit 130 and the MCU 123 of the accessory battery 120. The processing in FIG. 2A and the processing in FIG. 2B are respectively combined by connectors X and Y. The circuit diagnostic control illustrated in FIGS. 2A and 2B is started, for example, in a state where the safety of the vehicle is ensured, such as when parked.

[0020] (Step S201) The MCU 137 of the power distribution circuit 130 controls the first switch (first SW) 131, the second switch (second SW) 132, the third switch (third SW) 133, and the fourth switch (fourth SW) 134 to be in a conductive state (ON) respectively (switching unit). Also, the MCU 123 of the accessory battery 120 controls the switch (SW) 122 to be in a conductive state. When each switch is controlled to be in a conductive state respectively, the process proceeds to step S202.

[0021] (Step S202) The MCU 137 of the power distribution circuit 130 acquires the current A1 flowing through the first switch (first SW) 131 as information on the charge and discharge current of the accessory battery 120. Note that, as information on the charge and discharge current of the accessory battery 120, the inflow / outflow current A2 of the battery 121 in the accessory battery 120 may be used. When the charge and discharge current A1 (or A2) is acquired, the process proceeds to step S203.

[0022] (Step S203) The MCU 137 of the power distribution circuit 130 determines whether or not a charge / discharge current A1 is flowing to the auxiliary battery 120. This determination is made to confirm whether or not the auxiliary battery 120 and the power distribution circuit 130 are properly connected. The presence or absence of this charge / discharge current A1 can be determined not only by whether or not the current is zero, but also by whether or not the current exceeds a predetermined value. If it is determined that the charge / discharge current A1 is flowing (step S203, present), the process proceeds to step S211. On the other hand, if it is determined that the charge / discharge current A1 is not flowing (step S203, absent), the process proceeds to step S204.

[0023] (Step S204) The MCU 137 of the power distribution circuit 130 controls the first switch (first SW) 131 and the fourth switch (fourth SW) 134 to conduct (ON), and controls the second switch (second SW) 132 and the third switch (third SW) 133 to disconnect (OFF) (switching section). In addition, the MCU 123 of the auxiliary battery 120 controls the switch (SW) 122 to conduct. When each switch is controlled to either conduct or disconnect, the process proceeds to step S205.

[0024] (Step S205) The MCU 137 of the power distribution circuit 130 acquires the intermediate voltage V2 between the second switch (second SW) 132 and the third switch (third SW) 133. Once the intermediate voltage V2 is acquired, the process proceeds to step S206.

[0025] (Step S206) The MCU 137 of the power distribution circuit 130 determines whether or not an intermediate voltage V2 is output between the second switch (second SW) 132 and the third switch (third SW) 133. This determination is made to confirm whether the second switch 132 and / or the third switch 133 are operating normally. If it is determined that the intermediate voltage V2 is output (step S206, present), the process proceeds to step S207. On the other hand, if it is determined that the intermediate voltage V2 is not output (step S206, absent), the process proceeds to step S208.

[0026] (Step S207) The MCU 137 of the power distribution circuit 130 determines that at least one of the second switch (second SW) 132 and the third switch (third SW) 133 is abnormal (stuck in the ON position) (diagnostic unit). Which switch is abnormal can be determined based on the value of the intermediate voltage V2 (either the value from the auxiliary battery 120 or the value from the DC-DC converter 110). If at least one of the second switch 132 and the third switch 133 is determined to be abnormal, the circuit diagnostic control ends.

[0027] (Step S208) The MCU 137 of the power distribution circuit 130 acquires the voltage V1 that appears at the input terminal of the first switch (first SW) 131 as information about the output voltage of the auxiliary battery 120. Once the input voltage V1 is acquired, the process proceeds to step S209.

[0028] (Step S209) The MCU 137 of the power distribution circuit 130 acquires the current A1 flowing through the first switch (first SW) 131 as information about the discharge current of the auxiliary battery 120. Alternatively, the outflow current A2 from battery 121 in the auxiliary battery 120 may be used as information about the discharge current of the auxiliary battery 120. Once the discharge current A1 is acquired, the process proceeds to step S210.

[0029] (Step S210) The MCU 137 of the power distribution circuit 130 determines whether the input voltage V1 of the first switch (first SW) 131 is outputting and whether a discharge current A1 is flowing from the auxiliary battery 120. This determination is made to confirm whether the auxiliary battery 120 and the power distribution circuit 130 are properly connected. The presence or absence of this input voltage V1 may be determined not only by whether the voltage is zero or not, but also by whether the voltage exceeds a predetermined value. Similarly, the presence or absence of this discharge current A1 may be determined not only by whether the current is zero or not, but also by whether the current exceeds a predetermined value. If it is determined that the input voltage V1 is outputting and a discharge current A1 is flowing (step S210, yes), the process proceeds to step S211. On the other hand, if any other determination is made (step S210, no), the process proceeds to step S212.

[0030] (Step S211) The MCU 137 of the power distribution circuit 130 determines that the circuit network of the power distribution circuit 130 is normal (diagnostic unit). Specifically, it determines that the wiring system on the battery side that electrically connects the auxiliary battery 120 and the power distribution circuit 130 (wire harness, first switch (first SW) 131, etc.) is normal. Once it is determined that the circuit network of the power distribution circuit 130 is normal, this circuit diagnostic control ends.

[0031] (Step S212) The MCU 137 of the power distribution circuit 130 determines that the circuit network of the power distribution circuit 130 is abnormal (diagnostic unit). Specifically, it determines that the wiring system on the battery side that electrically connects the auxiliary battery 120 and the power distribution circuit 130 (such as the wire harness and the first switch (first SW) 131) is abnormal. Once it is determined that the circuit network of the power distribution circuit 130 is abnormal, this circuit diagnostic control ends.

[0032] <Effects and Actions> As described above, according to the power distribution circuit diagnostic system 100 of one embodiment of the present disclosure, a plurality of first switches (SW) 131 to fourth switches 134 provided between the DC-DC converter 110 and the auxiliary battery 120 and a plurality of loads 140 to 150 are appropriately switched and controlled to diagnose the normal / abnormal state of the power distribution circuit 130 based on the connection status of the plurality of first switches 131 to fourth switches 134 and changes in voltage and current in the power distribution circuit 130.

[0033] This circuit diagnostic control allows the power distribution circuit 130, to which the DC-DC converter 110 and auxiliary battery 120 are connected, to be diagnosed using only the existing configuration.

[0034] Although one embodiment of the present disclosure has been described above, the present disclosure can be understood not only as the power distribution circuit diagnostic system described above, but also as a method performed by a power distribution circuit diagnostic system equipped with a processor and memory, a program for that method, a computer-readable non-temporary recording medium storing that program, or a vehicle equipped with a power distribution circuit diagnostic system. [Industrial applicability]

[0035] The power distribution circuit diagnostic system disclosed herein can be used in vehicles equipped with a DC-DC converter and an auxiliary battery, among other applications. [Explanation of Symbols]

[0036] 100 diagnostic systems 110 DC-DC Converter (DDC) 120 Auxiliary Battery 121 Battery 122 Switches (SW) 123 MCU 130 Power distribution circuit (B-DC) 131-134 Switches (SW) 135-136 Relay (RLY) 137 MCU 140-150 load

Claims

1. A system for diagnosing a power distribution circuit that distributes power supplied from a DC-DC converter and an auxiliary battery to multiple loads, The DC-DC converter and the auxiliary battery are provided between the plurality of loads and a plurality of switches, A switching unit that switches the connection state of the plurality of switches, The system includes a diagnostic unit that diagnoses the power distribution circuit based on the connection status of the plurality of switches and changes in voltage and current in the power distribution circuit. A diagnostic system for power distribution circuits.

2. The diagnostic unit diagnoses the power distribution circuit based on the presence or absence of charge and discharge current between the auxiliary battery and the power distribution circuit when the DC-DC converter is connected to the power distribution circuit. A diagnostic system for a power distribution circuit according to claim 1.

3. The diagnostic unit diagnoses the power distribution circuit based on the presence or absence of voltage and current between the auxiliary battery and the power distribution circuit when the DC-DC converter is disconnected from the power distribution circuit. A diagnostic system for a power distribution circuit according to claim 1.

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