On-board power supply network

Abstract

The present application relates to a vehicle-mounted power supply network that supplies power to loads mounted on a vehicle via a plurality of nodes in the vehicle, the plurality of nodes including a first node that supplies power and a second node that receives power supplied from the first node, between the first node and the second node, a power line that supplies power and a signal line that transmits information about the power and is terminated at a terminal potential via a resistor are connected, the first node and the second node each have a current measurement unit that measures a current value flowing into and out of the own node via the power line, a current input / output unit that inputs and outputs a current proportional to the current value between the signal line and the own node, and a potential measurement unit that measures a potential of the signal line, the current input / output unit has a current limiting unit that limits the input / output current input to or output from the own node, and in a case where the potential of the signal line is different from the terminal potential, it is diagnosed that an abnormality occurs somewhere in the vehicle-mounted power supply network.

Description

Technical Field

[0001] This invention relates to power supply networks, and more particularly to on-board power supply networks suitable for electric vehicles. Background Technology

[0002] Since the beginning of this century, the electrification of automotive auxiliary systems such as electric power steering and electric brakes has made continuous progress. Furthermore, in recent years, the electrification of the main engine, exemplified by hybrid and electric vehicles, has also been developing. In addition, autonomous driving is constantly evolving, and in the future, even in the event of a vehicle malfunction, it will be required that the vehicle operate autonomously and automatically without human intervention. Against this backdrop, there is an increasing demand for high-performance and reliable (continuous operation during malfunctions) onboard power supply networks that support the electrification and automation of automobiles.

[0003] To ensure the continuity of operation in the event of a fault in the onboard power supply network, which has a daisy-chain / ring topology and is located in the vehicle body through electronic control units (regional ECUs), it is necessary to detect which segment (which regional ECU) the fault occurs in and to disconnect or bypass that segment. Furthermore, in this manual, "fault" refers to a "power supply short circuit" where wiring is shorted to the power source, and a "ground short circuit" where wiring is shorted to ground potential (GND).

[0004] To determine the faulty region, for example, the differential current method disclosed in Patent Document 1 detects whether the output current and input current are consistent on the power supply side and the power receiving side of that region. According to this technique, the output current and input current are consistent when no fault occurs in that region, but they are no longer consistent once a fault occurs, thus enabling the detection of the fault.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2021-90257 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] However, in Patent Document 1, since the current is detected by a current transformer and the abnormality is determined by a relay, its applicability is limited to the AC current that is the mainstream in commercial power supplies, and it cannot be applied to the DC current that is the mainstream in current vehicle power supply networks.

[0010] The present invention was made in view of the above-mentioned problems, and its object is to provide an on-board power supply network that utilizes direct current and can quickly detect faults.

[0011] Methods for solving problems

[0012] To achieve the above objectives, the vehicle power supply network of the present invention supplies power to loads mounted on the vehicle via multiple nodes within the vehicle. The multiple nodes include a first node that sends power and a second node that receives power sent from the first node. The first and second nodes are connected by a power line supplying power and a signal line that transmits information about the power and is terminated at a terminal potential via a resistor. Each of the first and second nodes has: a current measuring unit that measures the current flowing into and out of its own node via the power line; a current input / output unit that inputs and outputs a current proportional to the current value between the signal line and its own node; and a potential measuring unit that measures the potential of the signal line. The current input / output unit has a current limiting unit that limits the input and output currents input to or output from itself. When the potential of the signal line differs from the terminal potential, an anomaly is diagnosed at some point within the vehicle power supply network.

[0013] Invention Effects

[0014] According to the present invention, in a vehicle power supply network that utilizes direct current, the occurrence of faults can be detected quickly.

[0015] Further features related to this invention will become clear from the description and drawings in this specification. Furthermore, issues, configurations, and effects other than those described above will become clear through the following description of embodiments. Attached Figure Description

[0016] Figure 1 This is a diagram illustrating the basic structure of the vehicle power supply network according to Reference Example 1 of the present invention.

[0017] Figure 2 This is a diagram illustrating an example of the time elapsed for diagnostics performed from the occurrence of a fault in the vehicle's power supply network until the location of the fault is determined.

[0018] Figure 3 It is a graph showing the relationship between the types of faults that occur and the potential of the sensing line.

[0019] Figure 4 This is a diagram illustrating the configuration of the on-board power supply network described in Reference Example 2, where the terminal is set as a Thevenin terminal.

[0020] Figure 5 This diagram illustrates the configuration of embedding the Thevenin terminal into the ECU200-1.

[0021] Figure 6 This is a diagram showing the configuration of embedding the Thevenin terminal into the ECU200-2.

[0022] Figure 7 This is a diagram illustrating the configuration of the vehicle power supply network described in Reference Example 3, in which network communications within the vehicle power supply network are multiplexed.

[0023] Figure 8 This is a graph showing the change in potential when the potential is transmitted using the recessive voltage of CAN.

[0024] Figure 9 This diagram illustrates an example of the configuration used in the case of transmitting potential with the recessive voltage of CAN.

[0025] Figure 10 This is a diagram illustrating the configuration of the vehicle power supply network described in Reference Example 4, in which an ECU200-3 is added by branching the power lines.

[0026] Figure 11 This is a diagram showing the detailed configuration of the current measurement unit and the current input / output unit, and the configuration of the vehicle power supply network involved in Example 5.

[0027] Figure 12 It is shown in Figure 11 The diagram shows the configuration of an additional current amplifier circuit.

[0028] Figure 13 This is a diagram illustrating the configuration of the on-board power supply network described in Reference Example 6, where the power supply is configured as redundant.

[0029] Figure 14 This is a diagram illustrating a modified example of the vehicle power supply network involved in Reference Example 6.

[0030] Figure 15 The figure shows other variations of the vehicle power supply network involved in Reference Example 6.

[0031] Figure 16 This is a diagram illustrating the configuration of the vehicle power supply network used in the four ECUs mounted in a car, as described in Reference Example 7.

[0032] Figure 17 It is shown in Figure 16 A diagram showing the relationship between the location of the fault and the opening / closing status of the switch in the configuration.

[0033] Figure 18 This is a variation of the vehicle power supply network mentioned in Example 7.

[0034] Figure 19 This is a diagram illustrating the configuration of the vehicle power supply network used in the four ECUs mounted in a car, as described in Reference Example 8.

[0035] Figure 20 It is shown in Figure 19A diagram showing the relationship between the location of the fault and the opening / closing status of the switch in the configuration.

[0036] Figure 21 This is a diagram illustrating a modified example of the vehicle power supply network involved in Reference Example 8.

[0037] Figure 22 This is a diagram showing the types of semiconductor-based switches.

[0038] Figure 23 This is a diagram illustrating the basic structure of the vehicle power supply network according to Embodiment 1 of the present invention.

[0039] Figure 24 This is a graph showing the relationship between the types of faults that occurred in Example 1 and the potential of the sensing line.

[0040] Figure 25 This is a diagram showing the basic configuration of the vehicle power supply network according to Embodiment 2 of the present invention, in which a clamping diode is added in parallel with Rsout and Rsin as a current limiting part.

[0041] Figure 26 This is a diagram showing the relationship between Iout, Iin and Is1, Is2 obtained according to Example 2.

[0042] Figure 27 This diagram illustrates the basic configuration of the vehicle power supply network described in Embodiment 3, in which a current limiting resistor r is connected in series at the output of the current input / output section as a current limiting unit.

[0043] Figure 28 This is a diagram showing the relationship between Vs1, Vs2 and Is1, Is2 obtained according to Example 3.

[0044] Figure 29 This is a diagram showing the basic configuration of the vehicle power supply network according to Embodiment 4, in which a diode is added in series with the power supply ground of the current input / output section as a current limiting section.

[0045] Figure 30 This is a diagram showing the relationship between Vs1, Vs2 and Is1, Is2 obtained according to Example 4.

[0046] Figure 31 This is a diagram illustrating the basic configuration of the vehicle power supply network according to Embodiment 5, which uses the charging and discharging currents of the smoothing capacitor to test the abnormality detection function of the power line 20 provided by the present invention.

[0047] Figure 32 This is a graph showing the time variations of Iout and Iin obtained according to Example 5.

[0048] Figure 33 This is a graph showing the relationship between the types of faults that occurred and the potential of the sensing line, as applied in Example 5.

[0049] Figure 34 This is a diagram illustrating the basic configuration of the vehicle power supply network according to Embodiment 6, where the ground potential used as a reference when measuring the potentials Vs1 and Vs2 of the sensing lines is set as the ground potential of the Thevenin terminal.

[0050] Figure 35 This diagram illustrates the configuration of embedding the Thevenin terminal into the ECU200-1.

[0051] Figure 36 This is a diagram showing the configuration of embedding the Thevenin terminal into the ECU200-2.

[0052] Figure 37 This is a diagram illustrating the basic configuration of the vehicle power supply network according to Embodiment 7, in which the wire connected to the ground potential of the sensing line and the Thevenin terminal is a twisted pair.

[0053] Figure 38 This diagram illustrates the configuration of embedding the Thevenin terminal into the ECU200-1.

[0054] Figure 39 This is a diagram showing the configuration of embedding the Thevenin terminal into the ECU200-2.

[0055] Figure 40 This is a diagram illustrating the basic configuration of the vehicle power supply network according to Embodiment 8, in which the line connecting the sensing line and the ground potential of the Thevenin terminal is a shielded line or a coaxial cable.

[0056] Figure 41 This diagram illustrates the configuration of embedding the Thevenin terminal into the ECU200-1.

[0057] Figure 42 This is a diagram showing the configuration of embedding the Thevenin terminal into the ECU200-2. Detailed Implementation

[0058] The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0059] [Reference Example 1]

[0060] First, in order to facilitate understanding of the embodiments of the present invention, the following methods are used. Figures 1-22 Useful reference examples are explained. Figure 1 This is a diagram illustrating the basic structure of the vehicle power supply network according to Reference Example 1 of the present invention.

[0061] The vehicle power supply network 1 described in Example 1 supplies power (not shown) to loads (not shown) mounted on the vehicle via multiple ECUs through a power source (not shown). The vehicle power supply network 1 includes an ECU 200-1 that sends power and an ECU 200-2 that receives power from the ECU 200-1. The ECU 200-1 and ECU 200-2 are connected by a power line 20 that supplies power and a sensing line 21 that transmits information about the power.

[0062] ECU200-1 includes a current measuring unit 201-1 that measures the current Iout delivered via power line 20, and a current input / output unit 202-1 that directs a current Is1 = K × Iout proportional to the measured current Iout to the sensing line 21. Here, K is a predetermined proportionality constant. ECU200-2 similarly includes a current measuring unit 203-2 that measures the current Iin received via power line 20, and a current input unit 204-2 that receives a current Is2 = K × Iin proportional to the current Iin from the sensing line 21. Furthermore, in Figure 1 The current is configured to flow from ECU200-1 to ECU200-2, but conversely, it can also be configured to flow from ECU200-2 to ECU200-1. In this case, the current flowing through the sensing line 21 is output from the current input section 204-2 of ECU200-2 and input to the current input / output section 202-1 of ECU200-1. Therefore, these will not be distinguished hereafter, and will be collectively referred to as current input / output sections.

[0063] The sensing line 21 is then connected to the potential VAG via a resistor R and terminated in ground. In addition, the power supply network 1 is connected to a potential meter capable of measuring the potential at any location, and a CPU (Central Processing Unit) for controlling the operation of the voltage source, ECU, and potential meter (none of which are shown).

[0064] Here, if the potential of sensing line 21 is set to Vs, and the current flowing through resistor R is set to i, then

[0065] i=(VAG-Vs) / R...(1)

[0066] From equation (1)

[0067] Vs=VAG-R×i...(2)

[0068] According to Kirchhoff's law for the current at point A,

[0069] i + K × Iout - K × Iin = 0...(3)

[0070] From equation (3)

[0071] i = K × Iin - K × Iout...(4)

[0072] Substituting equation (4) into equation (2), then

[0073] Vs=VAG-R×K(Iin-Iout)...(5) holds true.

[0074] As can be seen from equation (5), the potential Vs of the sensing line 21 contains the information of the difference between the input current and the output current (Iin-Iout). When the two are equal, i.e., Iin=Iout, Vs=VAG.

[0075] Furthermore, here, the value of K is set such that, for the actual objects Iin and Iout, the values ​​of Is1 and Is2 are within a range suitable for information sharing. For example, if K is set to 10... -3 Then, for the number A, the values ​​of Iin, Iout, Is1, and Is2 are within the range of the number mA. If we set K=10... -4 For Iin and Iout in the tens of A, the values ​​of Is1 and Is2 are in the range of several mA. If we set K=10 -5 For Iin and Iout values ​​in the hundreds of A range, the values ​​of Is1 and Is2 are in the range of several mA, which is within the range where noise based on Is1 and Is2 will not occur. The values ​​of VAG and R are set such that the value of Vs is within a range that is easy to measure. For example, when measuring in a circuit where the positive power supply voltage Vcc of the entire circuit is set to 5V, it is preferable to set VAG to approximately Vcc / 2 = 2.5 [V].

[0076] at this time,

[0077] VAG = Vcc / 2...(6)

[0078] Substituting equation (6) into equation (5), then

[0079] Vs=(Vcc / 2)-R×K(Iin-Iout)...(5)' is true.

[0080] If we set R=10 at this point... 3 Then, the current difference (Iin-Iout) relative to several A is within the voltage range of Vs=(Vcc / 2)± several V.

[0081] Furthermore, as mentioned above, in relation to Figure 1 The configuration is reversed. When the current flows from ECU200-2 to ECU200-1, only the directions (symbols) of Iout and Iin are reversed, and the above operation is valid.

[0082] Figure 2This diagram illustrates an example of the time elapsed for diagnosis performed from the occurrence of a fault in the vehicle's power supply network until the fault location is determined. Specifically, it shows the flow of fault occurrence → fault detection → disconnection switching → network communication → fault location determination. First, in stage 1, the fault occurrence is detected as an abnormality in the potentials Vs1 and Vs2 of the sensing lines 21 connected to ECU 200-1 and ECU 200-2. Then, the power line 20 is disconnected to protect the power line 20 and the circuitry within ECU 200-1 and ECU 200-2 from overheating, damage, or fire caused by overcurrent. Next, in stage 2, ECU 200-1 and ECU 200-2 exchange the measured potentials Vs1 and Vs2 of their respective sensing lines 21 via network communication. By sharing the potentials Vs1 and Vs2 of the sensing lines 21 detected by both, the fault location can be determined in stage 3, as described below.

[0083] Figure 3 This is a graph showing the relationship between the types of faults that occur and the potentials of the sensing lines used in the diagnostic process for determining fault location in Stage 3. The vertical axis represents the potential Vs1 of the sensing line 21 measured using ECU200-1, and the horizontal axis represents the potential Vs2 of the sensing line 21 measured using ECU200-2. When no fault occurs in the vehicle power supply network 1 and everything is normal, both Vs1 and Vs2 are approximately equal to VAG (=Vcc / 2).

[0084] When the power line is short-circuited to ground, the current flowing into sensing line 21 increases due to the decrease in the impedance of the entire system. Therefore, Vs1 and Vs2 both take values ​​larger than Vcc / 2 in region (1). When the power line is short-circuited to the power source, conversely, the current flowing into sensing line 21 decreases due to the increase in the impedance of the entire system. Therefore, Vs1 and Vs2 both take values ​​smaller than Vcc / 2 in region (2).

[0085] In the event of a fault in the Vs1 detection circuit of ECU200-1, the value of Vs2 in region (3) is approximately equal to Vcc / 2, and the value of Vs1 is different from Vcc / 2. In the event of a fault in the Vs2 detection circuit of ECU200-2, the value of Vs1 in region (4) is approximately equal to Vcc / 2, and the value of Vs2 is different from Vcc / 2.

[0086] When the sensing line breaks at the location where the potential VAG is connected to the sensing line 21 on the ECU200-1 side, for example at... Figure 1When the wire breaks at point B, since Vs1 is not terminated through resistor R, Vs1 oscillates to Vcc due to Is1. Since Vs2 is terminated through resistor R, when the current input / output section 204-2 is driven by a single-sided power supply (Vcc~0V), Vs2 becomes 0V. When driven by a dual power supply (Vcc~-Vcc), Vs2 is -Is2×R (region (5)), which is proportional to Is2. When the sensing line breaks at the ECU200-2 side where the potential VAG is connected to the sensing line 21, for example at Figure 1 When the wire is disconnected at point C, Vs1 is connected through resistor R and is a value of Is1×R that is proportional to Is1. Since Vs2 is not connected through resistor R, Vs2 is 0V when the current input / output section 204-2 is driven by a single power supply (Vcc~0V) and is -Vcc (region (6)) when driven by a dual power supply (Vcc~-Vcc).

[0087] Based on the principles explained above, by simply measuring the potential of the sensing line 21 connected between ECU200-1 and ECU200-2, the location of a fault in the on-board power supply network 1 that uses DC current can be quickly determined, and the entire system can be protected by cutting off the fault location.

[0088] [Reference Example 2]

[0089] Figure 4 This diagram illustrates the configuration of the vehicle power supply network 1 according to Reference Example 2. The vehicle power supply network 1 according to this Reference Example differs from the vehicle power supply network 1 according to Reference Example 1 in that the terminal of the sensing line 21 is a Thevenin terminal. In this Reference Example, the sensing line 21 is connected to the ground potential GND and the positive power supply voltage Vcc respectively via resistor 2R. According to Thevenin's theorem, this becomes an equivalent circuit to one where resistor R is connected to potential Vcc / 2. According to this Reference Example, unlike Reference Example 1, it is not necessary to separately configure a power supply (voltage source) for the terminal potential VAG=Vcc / 2 from the positive power supply voltage Vcc, thus simplifying the circuit configuration.

[0090] In addition, Figure 4 In the middle, the Thevenin resistor is set on the sensing line 21 between ECU200-1 and ECU200-2, but as Figure 5 , Figure 6 As shown, the terminal unit can also be built into either ECU200-1 or ECU200-2. Figure 5 This is a reference example where the terminal unit is built into the ECU200-1. Figure 6 This is a reference example of embedding the terminal unit into the ECU200-2.

[0091] [Reference Example 3]

[0092] Figure 7 This diagram illustrates the configuration of the vehicle power supply network 1 according to Reference Example 3, which multiplexes internal network communications. In the vehicle power supply network 1 according to this reference example, network transceivers 206-1 and 206-2 are built into ECU 200-1 and ECU 200-2, respectively. These network transceivers 206-1 and 206-2 can serve as... Figure 2 The shared communication lines Vs1 and Vs2 between ECU200-1 and ECU200-2 in Phase 2 are described in the document.

[0093] In addition, the following methods are listed as methods for bidirectional communication shared between Vs1 and Vs2.

[0094] ■Baseband transmission:

[0095] ・TDMA (Time Division Multiple Access)

[0096] ■Modulated wave transmission:

[0097] ・TDMA (Time Division Multiple Access)

[0098] ・FDMA (Frequency Division Multiple Access)

[0099] ・CDMA (Code Division Multiple Access)

[0100] Figure 8 , Figure 9 The diagrams show the potential changes and their configurations when using network transceivers 206-1 and 206-2, and employing CAN (Control Area Network) in network communication via sensing line 21, with the potential Vs transmitted as a recessive voltage. The recessive voltage of CAN is typically around 2.5V, but by setting the recessive voltage to Vs, it can be shared as Vs1 and Vs2 via ECUs 200-1 and ECU 200-2 connected to sensing line 21.

[0101] exist Figure 9In the dominant state, the transistor connected to Vcc is turned on for the CANH terminal of CAN transceivers 206-1 and 206-2, and the transistor connected to GND is turned on for the CANL terminal. In the recessive state, the transistor connected to Vcc is turned off for the CANH terminal of CAN transceivers 206-1 and 206-2, and the transistor connected to GND is turned off for the CANL terminal, with the voltage typically around 2.5V. However, based on the current Is1 from the current input / output section 202-1, the current Is2 from the current input / output section 204-2, and the terminating resistor, the potential becomes Vs according to equation (5)'.

[0102] In this case, such as Figure 8 As shown, the differential voltage is less than 0.5V in recessive mode and exceeds 0.9V in dominant mode, thus enabling the transmission of Vs without affecting the CAN communication itself.

[0103] According to this reference example, it is possible to perform calculations based on the implicit voltage Vs of ECU200-1 and ECU200-2 respectively. Figure 2 Phase 1 involves detection → disconnection switching, and CAN is used for network communication in Phase 2, which is then used for fault location determination in Phase 3.

[0104] [Reference Example 4]

[0105] Figure 10 This is a diagram illustrating the configuration of the vehicle power supply network involved in Reference Example 4, which branches the power line 20 and adds ECU 200-3. For currents flowing into and out of ECUs 200-1, ECU 200-2, and ECU 200-3 via sensing lines 21 having the same topology as the power line 20, Kirchhoff's laws apply as they do for currents flowing into and out of ECUs 200-1, ECU 200-2, and ECU 200-3 via the power line 20. Therefore, even in the case of branching as in this reference example, the operation shown in Reference Example 1 also applies. Furthermore, this reference example shows the case where the power line 20 is branched into two paths, but regardless of the number of branches, for currents flowing into and out of multiple ECUs via sensing lines 21 having the same topology as the power line 20, Kirchhoff's laws apply as they do for currents flowing into and out of multiple ECUs via the power line 20. Therefore, the operation shown in Reference Example 1 also applies.

[0106] [Reference Example 5]

[0107] Figure 11 This is a diagram illustrating the configuration of the vehicle power supply network involved in Reference Example 5, which shows the detailed configuration of the current measurement units 201-1 and 203-2 and the current input / output units 202-1 and 204-2.

[0108] In the current measurement unit 201-1 and the current input / output unit 202-1, the current Iout output from the ECU 200-1 is measured via a shunt resistor Rsout. At this time, the voltage difference across the shunt resistor Rsout is Iout × Rsout. The voltages across the shunt resistor Rsout are connected to the + and - input terminals of the operational amplifier OA via the input resistor Ri, respectively. The output of the operational amplifier OA is output to the sensing line 21 via another shunt resistor Rso. Here, the shunt resistor Rso is set up to measure the output current from the operational amplifier OA, and the voltage difference across the shunt resistor Rso is Is1 × Rso. The voltages across the shunt resistor Rso are connected to the + and - input terminals of the operational amplifier OA via the feedback resistor Rf, respectively. Here, if the potential difference [(Vin+) - (Vin-)] between the + and - input terminals of the operational amplifier OA is considered, then...

[0109] (Vin+)-(Vin-)=(Rf×Iout×Rsout-Ri×Is1×Rso) / (Rf+Ri)...(7)

[0110] Established.

[0111] Here, the gain of operational amplifier OA is ideally infinite, thus the output voltage from the output terminal operates in the manner of (Vin+)-(Vin-)→0. Therefore, if we assume the left side of equation (7) = 0, then

[0112] Is1=Rf×Iout×Rsout / Ri×Rso...(8)

[0113] K=Is1 / Iout=Rf×Rsout / (Ri×Rso)...(9)

[0114] Established.

[0115] The same applies to the current measurement unit 203-2 and the current input / output unit 204-2 on the ECU200-2 side.

[0116] K=Is2 / Iin=Rf×Rsin / (Ri×Rso)...(10)

[0117] Established.

[0118] Figure 12 Is Figure 11The above configuration is a reference example with a current amplification circuit added to the end of the operational amplifier OA. The output current of the operational amplifier OA is usually around 25mA, but by adding a current amplification circuit, a current exceeding this value can be output to the sensing line 21. Even in this case, the output currents Is1 and Is2 are measured through the shunt resistor Rso and fed back to the operational amplifier OA, thus performing the operation shown in equations (7) to (10).

[0119] [Reference Example 6]

[0120] Figure 13 This is a reference example of ECUs 200-1 and 200-2 used to implement the present invention. ECU 200-1 is connected to other ECUs 200-2 via power lines 20 through switches SW1 and SW2, and further connected to load 40-1 via switch SW11. Additionally, it is connected to the control function 210-2 of other ECUs 200-2 via switch SW12. Control function 210-1 controls switches SW1, SW2, SW11, and SW12 based on the potentials Vs1 and Vs2 of the sensing lines. Control function 210-1 is powered from the connection point of switches SW1 and SW2 and an external power source via diode OR (DOR). With the above power supply configuration, even if switches SW1 and SW2 are disconnected in case of a fault, power is still supplied from an external power source, thus enabling the control of switches SW1, SW2, SW11, and SW12 to continue.

[0121] ECU200-2 is also connected to other ECUs via power line 20 through switches SW3 and SW4, and further connected to loads 40-3 and 40-4 via switches SW21 and SW22. Control function 210-2 controls switches SW3, SW4, SW21, and SW22 based on the potentials Vs1 and Vs2 of the sensing lines. Control function 210-2 is powered from the connection point of switches SW3 and SW4 and from the external power supply (ECU200-1) via diode OR (DOR). With this power supply configuration, even if switches SW3 and SW4 are disconnected in case of a fault, power is still supplied from the external power supply (ECU200-1), thus allowing control of switches SW3, SW4, SW21, and SW22 to continue.

[0122] Figure 14 This is a reference example where the control function 210-2 within ECU200-2 is powered via diode OR (DOR) from power line 20-12 connected to ECU200-1 and power line 20-23 connected to other power sources. With the power supply configuration described above, even if switches SW3 and SW4 are disconnected in case of a fault, power is still supplied from power line 20-12 or power line 20-23, thus enabling the control of switches SW3, SW4, SW21, and SW22 to continue.

[0123] Figure 15 This is a reference example of the control function 210-2 within ECU200-2 being powered via diode OR (DOR) from the connection point of switches SW3 and SW4 and from an external power supply (ECU200-3). With the power supply configuration described above, even if switches SW3 and SW4 are disconnected in case of a fault, power is supplied from an external power supply (ECU200-3) that is different from the power supply to ECU200-1 via SW3, thus enabling the control of switches SW3, SW4, SW21, and SW22 to continue.

[0124] [Reference Example 7]

[0125] exist Figures 16-22 The diagram shows a reference example of a vehicle in which the power supply network described above is integrated.

[0126] Figure 16 This is a reference example where power is supplied from power source 100-1 to ECU 200-1, and from power source 100-2 to ECU 200-3. ECU 200-1 and ECU 200-3 are connected via power line 20-13. Power is further supplied from ECU 200-1 to ECU 200-2 via power line 20-12, and from ECU 200-3 to ECU 200-4 via power line 20-34. Furthermore, for the sake of simplicity, only the symbols indicating components that require special explanation will be described.

[0127] ECU200-1 receives power from power source 100-1 via switch SW1, receives power from ECU200-2 via switch SW2 and power line 20-12, and is connected to ECU200-3 via SW9 and power line 20-13. ECU200-2 receives power from ECU200-1 via switch SW3.

[0128] ECU200-3 receives power from power source 100-2 via switch SW5, and supplies power to ECU200-4 via SW5 and power line 20-34. It is connected to ECU200-1 via switch SW10 and power line 20-13. ECU200-4 receives power from ECU200-3 via switch SW7.

[0129] Furthermore, sensing lines (not shown) serving as signal lines for sharing current information are provided on power lines 20-12, 20-13, and 20-34 respectively, and faults in power lines 20-12, 20-13, and 20-34 are detected by the method provided by the present invention.

[0130] Power supply 100-1 is a DC / DC converter connected to the main drive battery (not shown) and the main unit (motor / generator). In the case of a hybrid vehicle, the main unit is mechanically connected to the engine; in the case of an electric vehicle, the main drive battery is connected to a charger or the charger's connection terminal. Normally, regenerative power from the main drive battery or the main unit (motor / generator) is converted to auxiliary drive voltage by the DC / DC converter of power supply 100-1 and supplied to ECU 200-1.

[0131] Power supply 100-2 is an auxiliary drive battery, which is usually float charged through the output of power supply 100-1 via ECU200-1 and ECU200-3.

[0132] Figure 17 The operation of each switch in this reference example is shown. Condition 0 is the normal condition with no fault location, where all switches are turned on to supply power to all loads. In addition, the steering ECU 200-5 and the automatic driving ECU 200-6 are powered via diode OR, and the electric braking ECUs (BK ECUs) 200-7 to 200-10 are also powered via their respective switches.

[0133] Furthermore, the "normal" state without a fault location here includes not only the case where the power line 20 is functioning normally without a fault, but also the case where the elements constituting the function of detecting abnormalities in the power line 20, namely the sensing line 21, the node (electronic control unit: ECU) 200, the current measurement units 201, 203, and the current input / output units 202, 204, are also functioning normally. This is because if an abnormality in the power line 20 cannot be detected due to an abnormality in one of the elements constituting the function of detecting abnormalities in the power line 20, each switch will be activated based on incorrect information, and the overall operation may not be expected to function normally.

[0134] Therefore, in this reference example, by comparing the potential of the sensing line 21 detected by the ECUs at both ends, it is possible to detect faults such as open circuit, short circuit to power supply, and short circuit to ground in the sensing line 21, and to detect faults in the elements constituting the function of detecting abnormalities in the power line 20.

[0135] Condition 1 is a fault that occurred on power line 20-12. By using... Figures 1-3 The principle of this invention, as explained, detects a fault by disconnecting switches SW2 and SW3, thereby cutting off power line 20-12. Furthermore, the power supply to ECU 200-2 and the power supply to load 40-21 are also cut off at this time.

[0136] Operating condition 2 is a case where a fault occurs in power line 20-13. The fault is detected using the principle of this invention, and switches SW9 and SW10 are opened, thus disconnecting power line 20-13. Furthermore, the battery serving as power source 100-2 is disconnected from power source 100-1 at this time and is no longer float-charged.

[0137] Operating condition 3 is a case where a fault occurs in power line 20-34. The fault is detected using the principle of this invention, and switches SW6 and SW7 are opened, thus disconnecting power line 20-34. Furthermore, the power supply to ECU 200-4 is cut off at this time, as are the power supplies to load 40-41 and the rear wheel electric brake ECUs (BK ECUs) 200-8 and 200-10. At this time, as... Figure 18 As shown, by connecting the battery, which serves as the power source 100-2, to the ECU 200-4, even in the event of a failure in the power line 20-34, the power supply to the ECU 200-4, the load 40-41, and the rear wheel electric brake ECUs (BK ECUs) 200-8 and 200-10 continues. Furthermore, since important loads are typically concentrated at the front of the vehicle, therefore... Figure 16 The battery shown is preferably connected to the ECU 200-3 as the power source 100-2.

[0138] Operating condition 4 is in the event of a fault in power supply 100-1. By monitoring the output of power supply 100-1 or detecting the fault through the self-diagnostic function of power supply 100-1, switch SW1 is opened, thus cutting off power supply 100-1. Meanwhile, power is supplied to the entire vehicle power supply network through the output of power supply 100-2, which is constantly being float-charged.

[0139] Condition 5 is a scenario where power supply 100-2 fails. By monitoring the output of power supply 100-2 or detecting the fault through its self-diagnostic function, switch SW5 is opened, thus cutting off power supply 100-2. Simultaneously, power is supplied to the entire vehicle power supply network through the output of power supply 100-1.

[0140] [Refer to Example 8]

[0141] Figure 19 It is relative to Figure 16 The configuration is further illustrated in the reference example where ECU200-2 and ECU200-4 are connected via power lines 20-24 through switches SW4 and SW8. Figure 20 The operation of switch SW in this reference example is illustrated. Furthermore, Figure 20 Is Figure 17 The diagram above the action example shows the control of switches SW4 and SW8 located at both ends of power lines 20-24.

[0142] In the absence of a fault location (normal condition), it is not necessary to disconnect all switches; power is supplied to all loads. However, even in this case, there are two options: Operating Condition 0A and 0B. As shown in Operating Condition 0A, when switches SW9 and SW10 are turned on to connect ECU200-1 and ECU200-3 via power line 20-13, SW4 and SW8, which connect power line 20-24 connecting ECU200-2 and ECU200-4, can be either on or off. Similarly, as shown in Operating Condition 0B, when switches SW4 and SW8 are turned on to connect ECU200-2 and ECU200-4 via power line 20-24, SW9 and SW10, which connect power line 20-13 connecting ECU200-1 and ECU200-3, can be either on or off. Furthermore, in the table, "*" indicates any, meaning either on or off is acceptable.

[0143] Regarding operating conditions 1-3, and Figure 17 The same applies to the various operating conditions shown in the figure, and the descriptions are omitted.

[0144] In the event of a failure in power supply 100-1, there are two options: 4A and 4B. In 4A, when switches SW9 and SW10 are turned on to connect ECU200-1 and ECU200-3 via power line 20-13, switches SW4 and SW8 on power line 20-24 connecting ECU200-2 and ECU200-4 can be either on or off. In 4B, when switches SW4 and SW8 are turned on to connect ECU200-2 and ECU200-4 via power line 20-24, switches SW9 and SW10 on power line 20-13 connecting ECU200-1 and ECU200-3 can be either on or off. Furthermore, in this case, power is supplied to the entire vehicle power supply network through the output of power supply 100-2.

[0145] Similarly, in the event of a failure in power supply 100-2, there are two options: 5A and 5B. In 5A, when switches SW9 and SW10 are turned on to connect ECU200-1 and ECU200-3 via power line 20-13, switches SW4 and SW8 on power line 20-24 connecting ECU200-2 and ECU200-4 can be either on or off. In 5B, when switches SW4 and SW8 are turned on to connect ECU200-2 and ECU200-4 via power line 20-24, switches SW9 and SW10 on power line 20-13 connecting ECU200-1 and ECU200-3 can be either on or off. Furthermore, in this case, power is supplied to the entire vehicle power supply network through the output of power supply 100-1.

[0146] Condition 6 is a case where a fault occurs in power line 20-24. The fault is detected using the principle of this invention, and switches SW4 and SW8 are disconnected, thus cutting off power line 20-24. ECUs 200-2 and ECU 200-4 are then supplied with power via power lines 20-12 and 20-34, respectively.

[0147] As described above, by connecting ECU200-2 and ECU200-4 via power lines 20-24 through switches SW4 and SW8, even if any one of power lines 20-12, 20-13, or 20-34 fails, power supply to the load can continue. Therefore, Figure 21 As shown, the diode OR used to supply power from power supply 100-2 to steering ECU 200-5 and automatic driving ECU 200-6 can also be omitted.

[0148] Furthermore, in [Reference Example 7], current flows bidirectionally only in the wiring to power supply 100-2 and power lines 20-13. Therefore, in the case of implementing switches SW5, SW9, and SW10 by semiconductor switches, in order to control the bidirectional current, it is necessary to... Figure 22 (b) shows the connection of components with opposite polarities. In the other electric field lines 20-12 and 20-34, the current flows in a single direction; therefore, the other SW lines can be connected as follows: Figure 22 (a) shows a single-polarity element. Furthermore, in [Reference Example 8], current flows bidirectionally in the wiring to power supply 100-2 and in all power lines 20-12, 20-13, 20-34, and 20-24. Therefore, when SW2 to SW10 are implemented using semiconductor switches, in order to control the bidirectional current, it is necessary to... Figure 22 (b) shows the connection of elements with opposite polarities.

[0149] Based on the above examples, faults such as short circuits to ground and to the power supply in power line 20, malfunctions in the ECU's potential detection circuit, and open circuits in sensing line 21 can be quickly detected. However, faults involving short circuits to ground and to the power supply in sensing line 21 are difficult to detect correctly. This is because when a short circuit to ground occurs in sensing line 21, the current flowing through sensing line 21 is significantly reduced as it flows towards ground. In the case of a short circuit to the power supply in sensing line 21, it indicates that sensing line 21 is in contact with the power source, and a significantly large current will flow. On the other hand, if using... Figure 3 As explained, in the event of a short circuit to ground / short circuit to the power supply in power line 20, the current flowing through sensing line 21 also increases / decreases. Therefore, as by Figure 3As shown in (1) and (2), when the current flowing through the sensing line 21 increases or decreases due to the increase or decrease in the potential of both ECU 200-1 and 200-2, it is sometimes difficult to determine whether it is a short circuit to ground / to the power supply of the power line 20 or a short circuit to ground / to the power supply of the sensing line 21.

[0150] In addition to the reference examples described above, the inventors have further discovered the aforementioned problems and, in order to solve these problems, have obtained the configurations involved in the embodiments described below.

[0151] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, the same reference numerals will be used to denote configurations identical to those described above, and descriptions may sometimes be omitted.

[0152] [Example 1]

[0153] Figure 23 Is Figure 1 The diagram shown illustrates the basic configuration of the vehicle power supply network according to Embodiment 1, in which current limiting units 220-1 and 220-2 are added to the current input / output units 202-1 and 204-2. In this embodiment, by providing current limiting units 220-1 and 220-2 in the current input / output units 202-1 and 204-2, the input and output currents of the current input / output units 202-1 and 204-2 are limited to be less than the current value flowing when the sensing line 21 experiences a short circuit to the power supply or a short circuit to ground. Therefore, it is possible to clearly distinguish the current when the power line experiences a short circuit to ground / short circuit to the power supply and the current when the sensing line 21 experiences a short circuit to ground / short circuit to the power supply.

[0154] Figure 24 This is a graph showing the relationship between the types of faults that occur and the potential of the sensing line, as used in this embodiment. Figure 3 Similarly, the vertical axis represents the potential Vs1 of the sensing line 21 measured using ECU200-1, and the horizontal axis represents the potential Vs2 of the sensing line 21 measured using ECU200-2. Under normal conditions and without any faults in the vehicle power supply network 1, both Vs1 and Vs2 are approximately equal to VAG (=Vcc / 2).

[0155] exist Figure 24 In the graph showing the relationship between the types of faults and the potential of the sensing line, according to this embodiment, the output current range of the current input / output units 202-1 and 204-2 is limited, such as... Figure 24As shown in regions (7) and (8), these are regions that can be set to represent the potential of the sensing line 21 when it is short-circuited to ground or short-circuited to the power supply, which cannot be achieved under the limited output current of the current input / output units 202-1 and 204-2 and only occur when the sensing line 21 is short-circuited to ground or short-circuited to the power supply without current limitation. Specifically, region (7) only occurs when the sensing line 21 is short-circuited to ground, and region (8) only occurs when the sensing line 21 is short-circuited to the power supply. Therefore, when the potential of the sensing line is in region (7), it indicates a fault where the sensing line is short-circuited to ground, and when it is in region (8), it indicates a fault where the sensing line 21 is short-circuited to the power supply.

[0156] [Example 2]

[0157] Figure 25 Is Figure 11 The diagram shows the configuration of the vehicle power supply network according to Embodiment 2, in which clamping diodes are added in parallel to Rsout and Rsin as current limiting parts 220-1 and 220-2. According to this configuration, the clamping diodes function as current limiters, such as... Figure 26 As shown, the current output ranges of Is1 and Is2 can be set so that the voltages across Rsout and Rsin are each less than Vf. Figure 24 As shown in regions (7) and (8), regions that cannot be generated using the output current of current input / output units 202-1 and 204-2 are possible. Specifically, when a current with a smaller current output range than Is1 and Is2 flows, it is equivalent to Figure 24 In region (7), it can be determined that the sensing line has a short circuit to ground. On the other hand, when a current with a larger current output range than Is1 and Is2 flows, it is equivalent to Figure 24 The region (8) can be identified as a short circuit to the power supply caused by the sensing line.

[0158] [Example 3]

[0159] Figure 27 Is Figure 11 The diagram shows the configuration of the vehicle power supply network according to Embodiment 3, in which a current limiting resistor r is added in series at the output of the current input / output sections 202-1 and 204-2 as the current limiting sections 220-1 and 220-2. According to this embodiment, in... Figure 28In the diagram showing Vs1 and Vs2 relative to Is1 and Is2, the current output in the upper right region (where Vs1, Vs2, and Is1 and Is2 are all relatively large, i.e., Is1 < (Vcc - Vs1) / r) and the lower left region (where Vs1, Vs2, and Is1 and Is2 are all relatively small, i.e., Is1 > -Vs1 / r) can be limited. If a current flows through the region corresponding to the upper right region, it can be determined that the sensing line is short-circuited to the power supply; if a current flows through the region corresponding to the lower left region, it can be determined that the sensing line is short-circuited to ground. Similarly, in this embodiment, as... Figure 24 As shown in regions (7) and (8), regions that cannot be generated by using the output current of current input / output units 202-1 and 204-2 are generated.

[0160] [Example 4]

[0161] Figure 29 Is Figure 11 The diagram shows the configuration of the vehicle power supply network according to Embodiment 4, in which diodes 220-1a, 220-1b, 220-2a, and 220-2b are added in series with the power supply ground of the current input / output sections 202-1 and 204-2 as current limiting parts 220-1 and 220-2. According to this embodiment, in Figure 30 In the diagram showing Vs1 and Vs2 relative to Is1 and Is2, the current output in the right-hand (Vs1, Vs2 > Vcc - Vf) and left-hand (Vs1, Vs2 < Vf) regions can be limited. Therefore, if current flows through the region corresponding to the right-hand side, it can be determined that the sensing line is short-circuited to the power supply; if current flows through the region corresponding to the left-hand side, it can be determined that the sensing line is short-circuited to ground. Similarly, in this embodiment... Figure 24 As shown in regions (7) and (8), regions that cannot be generated by using the output current of current input / output units 202-1 and 204-2 are generated.

[0162] [Example 5]

[0163] Figure 31 This is a diagram illustrating the configuration of the vehicle power supply network according to Embodiment 5, in which a smoothing capacitor C is inserted into the power line 20 (at any position between Rsout and Rsin), and the charging current and discharging current to the smoothing capacitor C are used for testing the abnormality detection function of the power line 20 provided by this invention. According to the configuration of this embodiment, at the instant the region ECU1 is turned on, as... Figure 32As shown, a portion of Iout output from ECU200-1 becomes the charging current (A) to the smoothing capacitor C, therefore Iout is correspondingly greater than Iin. Then, at the instant region ECU1 is disconnected, the discharge current (B) from the smoothing capacitor C is added to Iin, therefore Iin is correspondingly greater than Iout. As described above, through... Figure 32 The series of on / off actions of ECU1 in the shown area temporarily cause the values ​​of Iout and Iin to become inconsistent. Therefore, in Figure 33 In the graphs showing the relationship between the types of faults and the potential of the sensing line, as shown in (A) and (B), the change in the potential graph of sensing line 21 confirms that the abnormality detection function of the power line 20 provided by this invention is normal, i.e., the power line 20 is not broken, and the detection functions of Vs1 and Vs2 are normal. Specifically, it can be confirmed that there is no abnormality such as only reading the value of Vcc / 2 due to a fault in the potential (Vs1, Vs2) detection circuit caused by a break in the power line 20. Furthermore, in Figure 31 In this configuration, the smoothing capacitor C is located within region ECU2, but the location of the smoothing capacitor C can be any position between Rsout and Rsin, either inside region ECU1 or outside the two ECUs.

[0164] [Example 6]

[0165] Figure 34 Is Figure 4 The diagram illustrates the configuration of the vehicle power supply network according to Embodiment 6, where the ground potential used as a reference when measuring the potentials Vs1 and Vs2 of the sensing lines is set to the ground potential of the Thevenin terminal. Therefore, in this embodiment, a signal line connected to the ground potential of the Thevenin terminal is connected to the position where the potentials Vs1 and Vs2 of the sensing lines are measured, and the potentials Vs1 and Vs2 of the sensing line 21 are used as a differential input between the ground potential of the Thevenin terminal and the potential of the signal line closer to its own node side than the position where it is terminated at the Thevenin terminal. Furthermore, in Figure 34 In subsequent diagrams, illustrations of the current limiting parts 220-1 and 220-2 are omitted.

[0166] According to this embodiment, even when there is a difference in ground potential between area ECU1 (200-1) and area ECU2 (200-2), the potentials Vs1 and Vs2 of the sensing line can be measured without being affected by the ground potential difference, thereby enabling more accurate fault determination.

[0167] In addition, Figure 34 The text describes the case where there is a Thevenin terminal between region ECU1 (200-1) and region ECU2 (200-2), but as... Figure 34Variations can also be such as Figure 35 The Thevenin terminal is shown to be built into region ECU1 (200-1). In this case, as... Figure 35 As shown, the potential Vs1 of the sensing line on the ECU1 (200-1) side can be measured as a normal single-ended input. The potential Vs2 of the sensing line on the ECU2 (200-2) side can be measured as a differential input between the ground potential of the Thevenin terminal and the potential of the signal line on the node side closer to its own node than the position where it is terminated at the Thevenin terminal.

[0168] In addition, with Figure 35 Similarly, it can also be like Figure 36 The Thevenin terminal is shown to be built into region ECU2 (200-2). In this case, as... Figure 36 As shown, the potential Vs2 of the sensing line on the ECU2 (200-2) side can be measured as a normal single-ended input. The potential Vs1 of the sensing line on the ECU1 (200-1) side can be measured as a differential input between the ground potential of the Thevenin terminal and the potential of the signal line on the node side closer to its own node than the position where it is terminated at the Thevenin terminal.

[0169] [Example 7]

[0170] Figure 37 This diagram illustrates the configuration of the vehicle power supply network according to Embodiment 7, where the sensing line 21 and the signal line connected to the ground potential of the Thevenin terminal are twisted together. Here, a twisted pair refers to a cable formed by twisting two wires together. In a twisted pair, the magnetic flux generated in adjacent twisted pairs is in opposite directions, therefore the current generated due to this magnetic flux is also in opposite directions, making it less susceptible to external influences, thus reducing electromagnetic induction noise. For example, using... Figure 34 As explained, in the event of a short circuit to ground in sensing line 21, only a very weak current flows, thus posing a risk of significant impact from noise caused by electromagnetic induction. However, by utilizing this embodiment to reduce noise caused by electromagnetic induction, the weak current generated in the event of a short circuit to ground in sensing line 21 can be reliably detected. Furthermore... Figure 38 and Figure 39 and Figure 35 and Figure 36 Similarly, the diagrams show the configuration of embedding the Thevenin terminal in region ECU1 (200-1) and region ECU2 (200-2), respectively.

[0171] [Example 8]

[0172] Figure 40This diagram illustrates the configuration of the vehicle power supply network according to Embodiment 8, where the sensing line 21 connected to the ground potential of the Thevenin terminal is surrounded by a shielding layer 22. The shielding layer 22 functions as an electromagnetic induction barrier, and in this embodiment, it can reduce electromagnetic induction noise in the same way as in Embodiment 7. Furthermore... Figure 41 and Figure 42 and Figure 35 and Figure 36 Similarly, the diagrams show the configuration of embedding the Thevenin terminal in region ECU1 (200-1) and region ECU2 (200-2), respectively.

[0173] Based on the embodiments of the present invention described above, the following remarkable effects are achieved.

[0174] (1) The vehicle power supply network of the present invention is a vehicle power supply network that supplies power to a load mounted on the vehicle through multiple nodes in the vehicle. The multiple nodes include a first node that sends out power and a second node that receives power sent from the first node. The first node and the second node are connected by a power line that supplies power and a signal line that transmits information about the power and is terminated at a terminal potential via a resistor. The first node and the second node each have: a current measuring unit that measures the current value flowing into and out of its own node through the power line; a current input / output unit that inputs and outputs a current proportional to the current value between the signal line and its own node; and a potential measuring unit that measures the potential of the signal line. The current input / output unit has a current limiting unit that limits the input and output current input to or output from itself. When the potential of the signal line is different from the terminal potential, an anomaly is diagnosed at some point in the vehicle power supply network.

[0175] By adopting the above configuration, faults can be detected quickly in vehicle power supply networks that utilize direct current.

[0176] (2) The current measurement section and the current input / output section are composed of operational amplifiers. Therefore, even if the current output from the ECU is weak, it can be reliably detected by amplification.

[0177] (3) The current limiting unit sets a limit on the measurement range of the current measuring unit. Therefore, if a current flows through the area corresponding to the limited area, it can be determined that the sensing line has a short circuit to ground / short circuit to the power supply.

[0178] (4) The current limiting section includes: a voltage clamping circuit connected in parallel with the shunt resistor in the current measuring section; a resistor inserted in series at the output terminal of the current input / output section; or a clamping circuit connected in series with the power supply and ground of the current input / output section. The current limiting section is specifically constructed by these components.

[0179] (5) The terminal potential and resistance are formed by Thevenin terminals. Therefore, it is not necessary to set up a power supply separately from the positive power supply voltage for the terminal potential, which is expected to achieve miniaturization and cost control of the entire system.

[0180] (6) The potential measurement units of the first and second nodes measure the potential of the signal line at a point closer to their own node than the point where it is terminated to the terminal potential. Thus, each node can determine where the fault occurs on the signal line.

[0181] (7) The first node and the second node exchange the measured potentials of the signal lines via the network. Thus, each node can determine the cause of the fault by comparing its measured potential with the received potential.

[0182] (8) If the potentials of the signal lines of the first and second nodes after the exchange are different, the abnormality is diagnosed as any one of the signal lines, the current measurement section, and the current input / output section. This diagnosis can be specifically performed by adopting the configuration described in (5) above.

[0183] (9) The first and second nodes encode the measured potential of the signal line, superimpose it onto the signal line, and transmit it. This efficient information transmission can be achieved by using multiplexed network communication as shown in Example 3.

[0184] (10) The first and second node potential measurement units use the ground potential of the terminal potential as a reference, and measure the potential of the signal line at a position closer to its own node than the position where it is terminated to the terminal potential as a differential input. Therefore, even if there is a difference in ground potential between the first and second nodes, the potential of the sensing line can be measured without being affected by the ground potential difference, thereby enabling more accurate fault diagnosis.

[0185] (11) The grounding potential of the terminal potential and the signal line are connected by twisted pair or coaxial cable. This reduces electromagnetic noise generated in the signal line.

[0186] (12) A capacitor is connected to the power line, and a fault in the potential measurement unit is detected based on the potential change of the signal line caused by the following currents: the charging current to the capacitor when power is supplied from one of the first node and the second node to the other, and the discharging current from the capacitor when power supply ends from one of the first node and the second node to the other. By utilizing the change in current related to the discharge / charge of the capacitor, it is possible to confirm that the fault detection function of the signal line involved in this invention is normal.

[0187] (13) The node is an electronic control unit, which has: a current measuring unit; a current input / output unit; a first switch that turns on and off the current flowing to the power line connected to the electronic control unit; a second switch that turns on and off the current flowing to the load connected to the electronic control unit; and a control circuit that controls the first and second switches. Thus, the power supply path of the power line or load diagnosed as having a fault can be immediately cut off, and the power supply network can be quickly protected.

[0188] Furthermore, the present invention is not limited to the above embodiments and various modifications are possible. For example, the above embodiments are described in detail for ease of understanding and illustration of the present invention, and the present invention is not necessarily limited to having all the described configurations. Additionally, a portion of the configuration of one embodiment can be replaced with the configuration of another embodiment. Furthermore, the configuration of another embodiment can be incorporated into the configuration of one embodiment. Moreover, for a portion of the configuration of each embodiment, other configurations can be deleted, added, or substituted.

[0189] Symbol Explanation

[0190] 20… power line, 21… sensing line, 22… shielding layer, 40… load, 100… power supply, 200… node (electronic control unit: ECU), 201, 203… current measurement unit, 202, 204… current input and output unit, 210… control function (control circuit), 220… current limiting unit.

Claims

1. An on-board power supply network that supplies power to loads mounted on the vehicle via multiple nodes within the vehicle, characterized in that, The plurality of nodes includes a first node that sends out power and a second node that receives power sent from the first node. Between the first node and the second node, there is a power line supplying power and a signal line transmitting information about the power and terminated at a terminal potential via a resistor. The first node and the second node each have: a current measuring unit that measures the current flowing into and out of its own node via the power line; a current input / output unit that inputs and outputs a current proportional to the current value between the signal line and its own node; and a potential measuring unit that measures the potential of the signal line. The current input / output section includes a current limiting section that limits the input / output current to or from itself. If the potential of the signal line is different from the terminal potential, an anomaly is diagnosed at some point in the vehicle power supply network.

2. The vehicle-mounted power supply network according to claim 1, characterized in that, The current measurement unit and the current input / output unit are composed of operational amplifiers.

3. The vehicle-mounted power supply network according to claim 1, characterized in that, The current limiting unit sets a limit on the measurement range of the current measuring unit.

4. The vehicle-mounted power supply network according to claim 3, characterized in that, The current limiting section includes a voltage clamping circuit connected in parallel with the shunt resistor in the current measuring section.

5. The vehicle-mounted power supply network according to claim 1, characterized in that, The current limiting section includes a resistor inserted in series at the output terminal of the current input / output section.

6. The vehicle-mounted power supply network according to claim 1, characterized in that, The current limiting unit includes a power supply and a clamping circuit connected in series with the current input / output unit and grounded.

7. The vehicle-mounted power supply network according to claim 1, characterized in that, The terminal potential and the resistor are formed by Thevenin terminals.

8. The vehicle-mounted power supply network according to claim 1, characterized in that, The potential measurement units of the first node and the second node respectively measure the potential of the signal line at a position closer to its own node than the position where it is terminated to the terminal potential.

9. The vehicle-mounted power supply network according to claim 8, characterized in that, The first node and the second node exchange the measured potentials of the signal lines via the network.

10. The vehicle-mounted power supply network according to claim 9, characterized in that, If the potentials of the signal lines of the exchanged first and second nodes are different, an abnormality is diagnosed in any one of the signal lines, the current measurement unit, and the current input / output unit.

11. The vehicle-mounted power supply network according to claim 8, characterized in that, The first node and the second node encode the measured potential of the signal line, superimpose it on the signal line, and transmit it.

12. The vehicle-mounted power supply network according to claim 8, characterized in that, The potential measurement units of the first node and the second node use the ground potential of the terminal potential as a reference, and measure the potential of the signal line at a position closer to its own node than the position where it is terminated to the terminal potential as a differential input.

13. The vehicle-mounted power supply network according to claim 12, characterized in that, The ground potential of the terminal potential and the signal line are connected by twisted pair or coaxial cable.

14. The vehicle-mounted power supply network according to claim 1, characterized in that, A capacitor is connected to the power line. The fault of the potential measurement unit is detected based on the potential change of the signal line caused by the following currents: the charging current flowing to the capacitor when power is sent from one of the first node and the second node to the other, and the discharging current from the capacitor when power is sent from one of the first node and the second node to the other.

15. The vehicle-mounted power supply network according to claim 1, characterized in that, The node is an electronic control unit. The electronic control unit includes: the current measuring unit; the current input / output unit; a first switch that turns on and off the current flowing to the power line connected to the electronic control unit; and a second switch that turns on and off the current flowing to the load connected to the electronic control unit. and control circuits, The control circuit controls the first switch and the second switch.

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