Wire protection devices and vehicle-mounted systems

Abstract

To provide an electric wire protection device and an on-vehicle system, capable of appropriately protecting an electric wire from overheating.SOLUTION: An electric wire protection device 10 comprises a first current detection unit 12, a voltage detection unit 13, and a power supply controller 18. The first current detection unit 12 detects a current value of an electric wire connecting a power supply device 4 to a load 6, as a first detection current value AU. The voltage detection unit 13 detects a voltage value at a first voltage detection point 8U provided between the power supply device 4 and the electric wire 8 as a first detection voltage value VU and detects a voltage value at a second voltage detection point 8D provided between the electric wire and the load 6 as a second detection voltage value VD. The power supply controller 18 calculates power of the electric wire 8 as a first calculated power value W1 on the basis of the first detection current value AU, the first detection voltage value VU, and the second detection voltage value VD and, on the basis of the first calculated power value W1, restricts power supply to be performed via the electric wire 8.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The technology disclosed in the present application relates to a wire protection device and an in-vehicle system. [Background technology]

[0002] Patent Document 1 describes an overcurrent detection circuit. The overcurrent detection circuit described in Patent Document 1 calculates a load current flowing through a load based on the drain-source voltage and temperature of a field effect transistor (FET). The overcurrent detection circuit compares the load current with a determination value to determine whether the load current is an overcurrent or not. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-326400 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the conductor of an electric wire is generally composed of multiple strands, and even if some of the strands are broken, the current is almost the same as in normal conditions. Therefore, in the overcurrent detection circuit described in Patent Document 1, even if some of the strands are broken, the drain-source voltage of the FET is almost the same as in normal conditions. In other words, it is not possible to accurately determine an overcurrent based on the calculated load current, and there is a possibility that the electric wire cannot be adequately protected.

[0005] An object of the technique disclosed in the present application is to provide a wire protection device and an in-vehicle system that can adequately protect wires. [Means for solving the problem]

[0006] According to a first feature, the wire protection device includes a first current detection unit, a voltage detection unit, and a power supply controller. The first current detection unit detects a current value of a wire connecting a power supply device to a load as a first detected current value. The voltage detection unit detects a voltage value at a first voltage detection point provided between the power supply device and the wire as a first detected voltage value, and detects a voltage value at a second voltage detection point provided between the wire and the load as a second detected voltage value. The power supply controller calculates the power of the wire as a first calculated power value based on the first detected current value, the first detected voltage value, and the second detected voltage value, and limits the power supply through the wire based on the first calculated power value.

[0007] In the wire protection device according to the first feature, the state of the wire can be grasped relatively accurately based on the first calculated power value, and the wire can be appropriately protected from overheating.

[0008] According to a second feature, in the wire protection device according to the first feature, the power supply controller cuts off the power supply through the wire when the first calculated power value exceeds a power threshold value.

[0009] In the wire protection device according to the second aspect, the wire can be more appropriately protected from overheating while still supplying power through the wire.

[0010] According to a third feature, in the wire protection device according to the first or second feature, the power supply controller allows power supply through the wire when the first calculated power value is equal to or less than a power threshold value.

[0011] In the wire protection device according to the third aspect, the wire can be more appropriately protected from overheating while still supplying power through the wire.

[0012] According to a fourth feature, in the wire protection device according to any one of the first to third features, the power supply controller calculates the first calculated power value based on a power value calculation formula indicating the relationship between the first detected current value, the first detected voltage value, the second detected voltage value, and the first calculated power value.

[0013] In the wire protection device according to the fourth aspect, the calculated power value of the wire can be calculated more accurately by using the power value calculation formula, and the wire can be more appropriately protected from overheating.

[0014] According to a fifth feature, in the wire protection device related to the fourth feature, the power supply controller corrects an error in the power value calculation formula based on the first detected voltage value and the second detected voltage value output from the voltage detection unit when the power supply via the wire is interrupted.

[0015] In the wire protection device according to the fifth feature, by using the first detected voltage value and the second detected voltage value when the power supply through the wire is cut off, the error in the power value calculation formula can be appropriately corrected, and the wire can be more appropriately protected from overheating.

[0016] According to a sixth feature, in the wire protection device according to the fourth or fifth feature, the power supply controller corrects an error in the power value calculation formula based on the multiple different first detected current values ​​output from the first current detection unit at the multiple different detection timings, the multiple different first detected voltage values ​​output from the voltage detection unit at the multiple different detection timings, and the multiple different second detected voltage values ​​output from the voltage detection unit at the multiple different detection timings.

[0017] In the wire protection device according to the sixth aspect, the error in the power value calculation formula can be appropriately corrected, and the wire can be more appropriately protected from overheating.

[0018] According to a seventh feature, in the wire protection device related to the sixth feature, the power supply controller corrects an error in the power value calculation formula based on a plurality of different first detected current values ​​output from the first current detection unit at a plurality of different detection timings in a first determination period in which the first detected current value is equal to or less than the reference current value, a plurality of different first detected voltage values ​​output from the voltage detection unit at a plurality of different detection timings in the first determination period, and a plurality of different second detected voltage values ​​output from the voltage detection unit at a plurality of different detection timings in the first determination period.

[0019] In the wire protection device according to the seventh feature, when the first detected current value is equal to or less than the reference current value, the temperature of the wire is relatively low, and therefore the accuracy of the power value calculation formula tends to be relatively less affected by the wire temperature. Therefore, by correcting the error in the power value calculation formula based on the multiple different first detected current values, multiple different first detected voltage values, and multiple different second detected voltage values ​​in the first determination period, the error in the power value calculation formula can be more appropriately corrected.

[0020] According to an eighth feature, in the wire protection device related to the seventh feature, the power supply controller corrects an error in the power value calculation formula based on a plurality of different first detected current values ​​output from the first current detection unit at a plurality of different detection timings during a first judgment period in which the first detected current value is equal to or less than the reference current value and during a second judgment period from start-up of the vehicle until a predetermined time has elapsed, a plurality of different first detected voltage values ​​output from the voltage detection unit at a plurality of different detection timings during the first judgment period and the second judgment period, and a plurality of different second detected voltage values ​​output from the voltage detection unit at a plurality of different detection timings during the first judgment period and the second judgment period.

[0021] In the wire protection device according to the eighth feature, the temperature of the wire is relatively low until a predetermined time has elapsed since the start of the vehicle, so that the accuracy of the power value calculation formula is less susceptible to the effect of the wire temperature. Therefore, by correcting the error in the power value calculation formula based on the multiple different first detected current values, the multiple different first detected voltage values, and the multiple different second detected voltage values ​​in the first determination period and the second determination period, the error in the power value calculation formula can be corrected more appropriately.

[0022] According to a ninth feature, in the wire protection device according to the eighth feature, the second determination period includes an inrush current period in which the first current detection unit detects an inrush current value, and a steady current period in which the first current detection unit detects a steady current value after the inrush current period. The plurality of different first detected current values ​​includes an inrush current value and a steady current value. The plurality of different first detected voltage values ​​includes a first inrush voltage value and a first steady voltage value corresponding to the inrush current value and the steady current value, respectively. The plurality of different second detected voltage values ​​includes a second inrush voltage value and a second steady voltage value corresponding to the inrush current value and the steady current value, respectively. The power supply controller corrects an error in the power value calculation formula based on the inrush current value, the steady current value, the first inrush voltage value, the first steady voltage value, the second inrush voltage value, and the second steady voltage value.

[0023] In the wire protection device according to the ninth feature, since the difference between the inrush current value and the steady-state current value is relatively large, the error in the power value calculation formula can be corrected based on a wide range of data.

[0024] According to a tenth feature, in a wire protection device relating to any one of the first to ninth features, the voltage detection unit includes a first voltage detection unit that detects a voltage value at a first voltage detection point as a first detected voltage value, and a second voltage detection unit that detects a voltage value at a second voltage detection point as a second detected voltage value.

[0025] In the wire protection device according to the tenth feature, even if the first voltage detection point and the second voltage detection point are separated from each other, the first voltage detection unit and the second voltage detection unit can detect the voltage values ​​at the first voltage detection point and the second voltage detection point.

[0026] According to an eleventh feature, in the wire protection device according to the tenth feature, the first voltage detection unit is connected to a first voltage detection point arranged on a voltage line provided between the power supply device and the load and a first reference point arranged on a ground line provided between the power supply device and the load and serving as a reference for a first detected voltage value, and the second voltage detection unit is connected to a second voltage detection point arranged on the voltage line and a second reference point arranged on the ground line and serving as a reference for a second detected voltage value.

[0027] In the wire protection device according to the eleventh feature, the first voltage detection unit and the second voltage detection unit can detect the voltage values ​​at the first voltage detection point and the second voltage detection point.

[0028] According to a twelfth feature, in the wire protection device according to the eleventh feature, the second reference point is provided at a position on the ground line different from a position of the first reference point.

[0029] In the wire protection device according to the twelfth feature, the degree of freedom in arranging the first voltage detection unit and the second voltage detection unit can be increased.

[0030] According to a thirteenth feature, in the wire protection device related to the twelfth feature, the second voltage detection unit is connected to a line connecting the first voltage detection unit and the first reference point, and corrects the second detected voltage value based on the potential difference between the first reference point and the second reference point.

[0031] In the wire protection device according to the thirteenth feature, the degree of freedom in the arrangement of the first voltage detection unit and the second voltage detection unit can be increased, while the detection accuracy of the second voltage detection unit can be improved.

[0032] According to a fourteenth feature, in the wire protection device according to the eleventh feature, the second reference point is provided on a line connecting the first voltage detection unit and the first reference point.

[0033] In the wire protection device according to the fourteenth feature, the detection accuracy of the second voltage detection section can be improved.

[0034] According to a fifteenth feature, in the wire protection device according to the fourteenth feature, the second reference point is provided at the same position as the first reference point.

[0035] In the wire protection device according to the fifteenth feature, the detection accuracy of the second voltage detection section can be further improved.

[0036] According to a sixteenth feature, in the wire protection device according to any one of the tenth to fifteenth features, the first voltage detection section and the second voltage detection section are configured as an integrated unit.

[0037] In the wire protection device according to the sixteenth aspect, the structure can be simplified and the wires can be more appropriately protected from overheating.

[0038] According to a seventeenth feature, the wire protection device according to any one of the tenth to fifteenth features further includes a first unit and a second unit disposed at a position spaced apart from the first unit. The first unit includes a first voltage detection unit. The second unit includes a second voltage detection unit.

[0039] In the wire protection device according to the seventeenth feature, the first voltage detection unit and the second voltage detection unit are provided as separate units, so that the wire protection device can be applied to various arrangements of power sources and loads.

[0040] According to an 18th feature, the wire protection device relating to any one of the 1st to 17th features further includes a second current detection unit provided between the wire and the load and detecting a current value of the wire as a second detected current value.

[0041] In the wire protection device according to the eighteenth feature, the value of the current after flowing through the wire can be detected by the second current detection unit as the second detected current value. Therefore, the difference between the current value on the upstream side and the current value on the downstream side of the wire can be calculated using the first detected current value and the second detected current value, and the state of the wire can be grasped more accurately. Therefore, the first detected current value and the second detected current value can be used to more appropriately protect the wire from overheating.

[0042] According to a 19th feature, in the wire protection device related to the 18th feature, the power supply controller calculates the power of the wire as a second calculated power value based on the second detected current value, the first detected voltage value, and the second detected voltage value, and limits the power supply through the wire based on the first calculated power value and the second calculated power value.

[0043] In the wire protection device of the 19th feature, the condition of the wire can be grasped more accurately based on the first calculated power value on the upstream side of the wire and the second calculated power value on the downstream side of the wire, and the wire can be more appropriately protected from overheating.

[0044] According to a twentieth feature, in the wire protection device according to any one of the first to nineteenth features, the wire protection device further includes a third current detection unit configured to detect a current value of the wire as a third detected current value. The first current detection unit is disposed on the voltage line. The third current detection unit is disposed on the ground line.

[0045] In the wire protection device according to the twentieth feature, the current value of the current returning from the load to the power supply device can be detected as the third detected current value by the third current detection unit, and the state of the ground line can be grasped using the third detected current value.

[0046] According to a 21st feature, in the wire protection device related to the 20th feature, the power supply controller calculates the power of the wire as a third calculated power value based on the third detected current value, the first detected voltage value, and the second detected voltage value, and limits the power supply through the wire based on the first calculated power value and the third calculated power value.

[0047] In the wire protection device of the 21st feature, the condition of the wire can be grasped more accurately based on the first calculated power value of the voltage line of the wire and the third calculated power value of the ground line, and the wire can be more appropriately protected from overheating.

[0048] According to a twenty-second feature, an in-vehicle system includes a power supply device, a load, an electric wire, and a wire protection device according to any one of the first to twenty-first features. The wire protection device is electrically connected to the power supply device. The wire protection device is electrically connected to the load. No other device is electrically connected between the power supply device and the wire protection device. No other device is electrically connected between the wire protection device and the load.

[0049] In the in-vehicle system according to the twenty-second feature, no other devices are electrically connected between the power supply device and the wire protection device, and no other devices are electrically connected between the wire protection device and the load. That is, the wire protection device is disposed on a dedicated line between the power supply device and the load. Therefore, at least one of the detected current value, the first detected voltage value, and the second detected voltage value is less susceptible to the influence of the current supplied to the other load, and the detection accuracy of at least one of the detected current value, the first detected voltage value, and the second detected voltage value can be improved. For example, by applying the wire protection device to a dedicated line, the fluctuation of the ground potential is included in the detection signal rather than in the error. Therefore, the detection signal becomes larger, and the detection accuracy is improved. Effect of the Invention

[0050] According to the technology disclosed in the present application, it is possible to provide a wire protection device and an in-vehicle system that can appropriately protect wires from overheating. [Brief description of the drawings]

[0051] [Figure 1] FIG. 1 is a schematic block diagram of a vehicle including a wire protection device according to an embodiment. [Diagram 2] FIG. 2 is a schematic block diagram of a vehicle including a wire protection device according to a first modified example. [Diagram 3] FIG. 3 is a schematic block diagram of a vehicle including a wire protection device according to the second modification. [Figure 4] FIG. 4 is a schematic block diagram of a vehicle including a wire protection device according to the third modified example. [Diagram 5] FIG. 5 shows an example of a timing chart of the wire protection device shown in FIG. [Figure 6] FIG. 6 shows an example of a graph showing the relationship between the current value and the potential difference used in the wire protection device shown in FIG. [Figure 7] FIG. 7 shows an example of a timing chart of the wire protection device shown in FIG. [Figure 8] FIG. 8 shows an example of a timing chart of the wire protection device shown in FIG. [Figure 9] FIG. 9 shows an example of a timing chart of the wire protection device shown in FIG. [Figure 10] FIG. 10 shows an example of a flowchart of the operation of the wire protection device shown in FIG. [Figure 11] FIG. 11 shows an example of a flowchart of the operation of the wire protection device shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0052] Hereinafter, an embodiment will be described with reference to the drawings. In the drawings, the same reference numerals indicate corresponding or identical components.

[0053] As shown in Fig. 1, the vehicle 2 includes an on-board system 3. The on-board system 3 includes a power supply device 4, a load 6, an electric wire 8, and an electric wire protection device 10. Examples of the vehicle 2 include automobiles. Examples of the automobiles include automobiles equipped with an engine (internal combustion engine) as a power source, hybrid vehicles equipped with an engine and a vehicle drive motor as power sources, and electric vehicles or fuel cell vehicles equipped with a vehicle drive motor as a power source. However, the vehicle 2 is not limited to the above vehicles.

[0054] The load 6 is electrically connected to the power supply device 4 via an electric wire 8 and an electric wire protection device 10. The power supply device 4 supplies power (electricity) to the load 6 via the electric wire 8 and the electric wire protection device 10. To protect the electric wire 8, the electric wire protection device 10 limits the power supply between the power supply device 4 and the load 6 depending on the condition of the electric wire 8.

[0055] The loads 6 are operated by electricity supplied from the power supply device 4. Examples of the loads 6 include an electronic control unit (ECU), a light, a heater, an audio device, a sensor, and a camera. The power supply device 4 may be connected to a plurality of loads 6. The loads 6 may also be referred to as in-vehicle devices 6.

[0056] The power supply device 4 includes a battery and a power supply circuit. The power supply circuit converts a voltage (e.g., 12 V) supplied from the battery into a predetermined control voltage (e.g., 3 V or 5 V). The power supply device 4 is electrically connected to the load 6 via an electric wire 8 and an electric wire protection device 10. The power supply device 4 supplies the control voltage to the load 6 via the electric wire 8 and the electric wire protection device 10. The power supply device 4 is electrically connected to a start operation unit 2A of the vehicle 2. The start operation unit 2A is configured to receive a start operation by a user to start the vehicle 2. The start operation unit 2A is configured to receive a stop operation by a user to stop the system of the vehicle 2.

[0057] The start operation unit 2A includes, for example, at least one of an engine start key and a start button. Examples of the user's start operation include an operation in which the user turns the engine start key of the start operation unit 2A to the start side, and an operation in which the user presses the start button of the start operation unit 2A. Examples of the user's stop operation include an operation in which the user turns the engine start key of the start operation unit 2A to the stop side, and an operation in which the user presses the start button of the start operation unit 2A again. When the start operation unit 2A receives the user's start operation, it outputs a start signal. When the start operation unit 2A receives the user's stop operation, it outputs a stop signal. When the power supply device 4 receives the start signal from the start operation unit 2A, it starts supplying power to the wire protection device 10. When the power supply device 4 receives the stop signal from the start operation unit 2A, it stops supplying power to the wire protection device 10.

[0058] The wire protection device 10 is electrically connected to the power supply device 4. The wire protection device 10 is electrically connected to the load 6. In this embodiment, no other device is electrically connected between the power supply device 4 and the wire protection device 10. No other device is electrically connected between the wire protection device 10 and the load 6. That is, the wire protection device 10 is disposed on a dedicated line between the power supply device 4 and the load 6. However, other device may be electrically connected between the wire protection device 10 and the power supply device 4. Other device may be electrically connected between the wire protection device 10 and the load 6.

[0059] The wire protection device 10 includes a first current detection unit 12 and a voltage detection unit 13. The first current detection unit 12 detects a current value (first current value) of the wire 8 connecting the power supply device 4 to the load 6 as a first detected current value AU. The voltage detection unit 13 detects a voltage value (first voltage value) at a first voltage detection point 8U provided between the power supply device 4 and the wire 8 as a first detected voltage value VU. The voltage detection unit 13 detects a voltage value (second voltage value) at a second voltage detection point 8D provided between the wire 8 and the load 6 as a second detected voltage value VD.

[0060] In this embodiment, the voltage detection unit 13 includes a first voltage detection unit 14 and a second voltage detection unit 16. The first voltage detection unit 14 detects a voltage value (first voltage value) at a first voltage detection point 8U as a first detected voltage value VU. The second voltage detection unit 16 detects a voltage value (second voltage value) at a second voltage detection point 8D as a second detected voltage value VD. The first voltage detection point 8U is disposed between the first current detection unit 12 and the electric wire 8 on the voltage line. However, the first current detection unit 12 may be disposed between the first voltage detection point 8U and the electric wire 8 on the voltage line. The first voltage detection point 8U may also be referred to as an upstream voltage detection point 8U. The second voltage detection point 8D may also be referred to as a downstream voltage detection point 8D. The first voltage detection unit 14 may also be referred to as an upstream voltage detection unit 14. The second voltage detection unit 16 may also be referred to as a downstream voltage detection unit 16. The first detected voltage value VU may also be referred to as a detected upstream voltage value VU, and the second detected voltage value VD may also be referred to as a detected downstream voltage value VD.

[0061] The wire protection device 10 includes a power supply controller 18. The power supply controller 18 limits the power supply through the wire 8 based on the first detected current value AU, the first detected voltage value VU, and the second detected voltage value VD. The power supply controller 18 calculates the power of the wire 8 as a first calculated power value W1 based on the first detected current value AU, the first detected voltage value VU, and the second detected voltage value VD, and limits the power supply through the wire 8 based on the first calculated power value W1.

[0062] The wire protection device 10 further includes a second current detection unit 19. The second current detection unit 19 is provided between the wire 8 and the load 6, and detects the current value (second current value) of the wire 8 as a second detected current value AD. The first current detection unit 12 is arranged on the voltage line. The second current detection unit 19 is arranged on the voltage line. The second current detection unit 19 is arranged between the wire 8 and a second voltage detection point 8D on the voltage line. However, the second voltage detection point 8D may be arranged between the wire 8 and the second current detection unit 19 on the voltage line. The second current detection unit 19 may be omitted from the wire protection device 10.

[0063] The wire protection device 10 further includes a third current detection unit 20. The third current detection unit 20 detects a current value (third current value) of the wire 8 as a third detected current value AX. The third current detection unit 20 is disposed on the ground line. The third current detection unit 20 may be omitted from the wire protection device 10.

[0064] The wire protection device 10 includes a first unit 21 and a second unit 22. The second unit 22 is disposed at a position away from the first unit 21. The first unit 21 is disposed upstream of the second unit 22. The first unit 21 includes a first current detection unit 12, a third current detection unit 20, a first voltage detection unit 14, and a power supply controller 18. The second unit 22 includes a second current detection unit 19 and a second voltage detection unit 16. The first unit 21 may also be referred to as an upstream unit 21. The second unit 22 may also be referred to as a downstream unit 22. The power supply controller 18 may be provided in the second unit 20.

[0065] In this application, in the direction of current flow from positive (higher voltage side) to negative (lower voltage side), the positive side is referred to as "upstream" or "upstream side", and the negative side is referred to as "downstream" or "downstream side".

[0066] The power supply controller 18 includes a switch circuit 24, a processor 18P, a circuit board 18C, and a bus 18B. The switch circuit 24 is provided between the power supply device 4 and the load 6, and allows and blocks the power supply from the power supply device 4 to the load 6. The switch circuit 24 includes, for example, a field effect transistor (FET) 24F and a gate driver 24G.

[0067] The FET 24F is, for example, a metal oxide semiconductor (MOS) FET. More specifically, the FET 24F is an N-channel MOSFET. However, the FET 24F is not limited to an N-channel MOSFET. The FET 24F includes a drain electrode D, a source electrode S, and a gate electrode G. The drain electrode D is electrically connected to the power supply 4 via an electric wire 8. The source electrode S is electrically connected to the load 6 via an electric wire 8. The gate electrode G is electrically connected to the gate driver 24G.

[0068] When a gate voltage higher than the threshold is applied to the gate electrode G, the FET 24F allows a current to flow from the source electrode S to the drain electrode D. When a gate voltage higher than the threshold is not applied to the gate electrode G, the FET 24F blocks a current from flowing from the source electrode S to the drain electrode D.

[0069] The gate driver 24G is electrically connected to the processor 18P via the circuit board 18C and the bus 18B. The gate driver 24G supplies a gate voltage higher than a threshold to the gate electrode G of the FET 24F based on a command from the processor 18P.

[0070] The processor 18P includes, for example, a central processing unit (CPU) and / or a micro processing unit (MPU). The memory 18M includes, for example, a volatile and / or non-volatile memory. An example of the volatile memory includes a random access memory (RAM). An example of the non-volatile memory includes a read only memory (ROM) and an electrically erasable programmable ROM (EEPROM).

[0071] The memory 18M of the power supply controller 18 stores information such as a control program and firmware for implementing the control algorithm of the power supply controller 18. The processor 18P implements the control algorithm of the power supply controller 18 by reading and executing the control program stored in the memory 18M. The configuration of the power supply controller 18 is not limited to the processor 18P and the memory 18M. The configuration of the power supply controller 18 can be implemented by hardware only, software only, or a combination of hardware and software.

[0072] The switch circuit 24, the processor 18P, and the memory 18M are electrically mounted on a circuit board 18C. The switch circuit 24, the processor 18P, and the memory 18M are electrically connected to each other via the circuit board 18C and the bus 18B.

[0073] The first current detection unit 12 and the first voltage detection unit 14 are electrically connected to the power supply controller 18. The first current detection unit 12 and the first voltage detection unit 14 are electrically mounted on a circuit board 18C. The first current detection unit 12 and the first voltage detection unit 14 are electrically connected to the processor 18P and the memory 18M via the circuit board 18C and the bus 18B. The first detection current value AU output from the first current detection unit 12 is input to the power supply controller 18 via the circuit board 18C and the bus 18B. The third detection current value AX output from the third current detection unit 20 is input to the power supply controller 18 via the circuit board 18C and the bus 18B. The first detection voltage value VU output from the first voltage detection unit 14 is input to the power supply controller 18 via the circuit board 18C and the bus 18B.

[0074] The second unit 22 includes a circuit board 22C. The second current detection unit 19 and the second voltage detection unit 16 are electrically mounted on the circuit board 22C. The wire protection device 10 includes an electric cable 28. The second unit 22 is electrically connected to the first unit 21 via the electric cable 28. The second current detection unit 19 and the second voltage detection unit 16 are electrically connected to the processor 18P and the memory 18M via the circuit board 22C, the electric cable 28, the bus 18B, and the circuit board 18C. The second detected current value AD output from the second current detection unit 19 is input to the power supply controller 18 via the circuit board 22C and the electric cable 28. The second detected voltage value VD output from the second voltage detection unit 16 is input to the power supply controller 18 via the circuit board 22C and the electric cable 28.

[0075] The vehicle 2 further includes electric wires 81, 82, 84, and 85. The power supply device 4 is electrically connected to the first unit 21 via the electric wire 81. The electric wire 82 is provided in the first unit 21. The first unit 21 is electrically connected to the second unit 22 via the electric wire 8. The electric wire 84 is provided in the second unit 22. The second unit 22 is electrically connected to the load 6 via the electric wire 85.

[0076] The electric wire 81 includes electric connectors 81A and 81B, a voltage line VL1, and a ground line GL1. The electric connector 81A is removably connected to the power supply device 4. The electric connector 81B is removably connected to the first unit 21 of the electric wire protection device 10. The electric connector 81A is connected to the electric connector 81B via the voltage line VL1 and the ground line GL1.

[0077] The electric wire 82 is provided in the first unit 21. The first voltage detection point 8U is provided in the first unit 21. The electric wire 82 includes electric connectors 82A and 82B, a voltage line VL2, and a ground line GL2. The electric connectors 82A and 82B are electrically connected to the circuit board 18C. The voltage line VL2 and the ground line GL2 are provided on the circuit board 18C. The electric connector 82A is connected to the electric connector 82B via the voltage line VL2 and the ground line GL2. The electric connector 81B of the electric wire 81 is detachably connected to the electric connector 82A of the electric wire 82. The voltage line VL2 is electrically connected to the voltage line VL1 via the electric connectors 81B and 82A. The ground line GL2 is electrically connected to the ground line GL1 via the electric connectors 81B and 82A. The voltage line VL2 and the ground line GL2 are electrically connected to the circuit board 18C so that power is supplied from the power supply device 4 to the power supply controller 18 regardless of the power supply from the power supply device 4 to the load 6. Therefore, while power is being supplied from the power supply device 4 to the wire protection device 10, the power supply controller 18 operates using the power supply from the power supply device 4.

[0078] The wire 8 includes electrical connectors 83A and 83B, a voltage line VL3, and a ground line GL3. The electrical connector 83A is connected to the electrical connector 83B via the voltage line VL3 and the ground line GL3. The electrical connector 83A is removably connected to the first unit 21 of the wire protection device 10. The electrical connector 83A of the wire 8 is removably connected to the electrical connector 82B of the wire 82. The voltage line VL3 is electrically connected to the voltage line VL2 via the electrical connectors 82B and 83A. The ground line GL3 is electrically connected to the ground line GL2 via the electrical connectors 82B and 83A. The electrical connector 83B is removably connected to the second unit 22 of the wire protection device 10.

[0079] The electric wire 84 is provided on the second unit 22. The second voltage detection point 8D is provided on the electric wire 84. The electric wire 84 includes electrical connectors 84A and 84B, a voltage line VL4, and a ground line GL4. The electrical connectors 84A and 84B are electrically connected to the circuit board 18C. The voltage line VL4 and the ground line GL4 are provided on the circuit board 18C. The electrical connector 84A is connected to the electrical connector 84B via the voltage line VL4 and the ground line GL4. The electrical connector 83B of the electric wire 8 is detachably connected to the electrical connector 84A of the electric wire 84. The voltage line VL4 is electrically connected to the voltage line VL3 via the electrical connectors 83B and 84A. The ground line GL4 is electrically connected to the ground line GL3 via the electrical connectors 83B and 84A.

[0080] The electric wire 85 includes electrical connectors 85A and 85B, a voltage line VL5, and a ground line GL5. The electrical connector 85A is connected to the electrical connector 85B via the voltage line VL5 and the ground line GL5. The electrical connector 85A is removably connected to the first unit 21 of the electric wire protection device 10. The electrical connector 85A of the electric wire 85 is removably connected to the electrical connector 84B of the electric wire 84. The voltage line VL5 is electrically connected to the voltage line VL4 via the electrical connectors 84B and 85A. The ground line GL5 is electrically connected to the ground line GL4 via the electrical connectors 84B and 85A. The electrical connector 85B is removably connected to the load 6.

[0081] The FET 24F of the switch circuit 24 is disposed on the voltage line VL2. The first current detection unit 12 detects the current value of the current flowing through the voltage line VL2 as a first detected current value AU. The second current detection unit 19 detects the current value of the current flowing through the voltage line VL4 as a second detected current value AD. The third current detection unit 20 detects the current value of the current flowing through the ground line GL2 as a third detected current value AX. The first voltage detection unit 14 detects the voltage value applied between the voltage line VL2 and the ground line GL2 as a first detected voltage value VU. The second voltage detection unit 16 detects the voltage value applied between the voltage line VL4 and the ground line GL4 as a second detected voltage value VD.

[0082] The first voltage detection unit 14 is connected to a first voltage detection point 8U arranged on a voltage line provided between the power supply device 4 and the load 6, and a first reference point RP1 arranged on a ground line provided between the power supply device 4 and the load 6 and serving as a reference for the first detected voltage value VU. The second voltage detection unit 16 is connected to a second voltage detection point 8D arranged on the voltage line, and a second reference point RP2 arranged on the ground line and serving as a reference for the second detected voltage value VD. In this embodiment, the second reference point RP2 is provided at a position on the ground line different from the position of the first reference point RP1. The position of the first reference point RP1 is away from the position of the second reference point RP2. However, as shown in FIG. 2, the second reference point RP2 may be provided on a line connecting the first voltage detection unit 14 and the first reference point RP1. In the modified example shown in FIG. 2, the second reference point RP2 is provided at the same position as the position of the first reference point RP1. However, the second reference point RP2 may be provided at a position different from the position of the first reference point RP1 on the line connecting the first voltage detection unit 14 and the first reference point RP1. Also, as shown in FIG. 3, when the second reference point RP2 is provided at a position different from the position of the first reference point RP1 on the ground line, the second voltage detection unit 16 may be connected to the line connecting the first voltage detection unit 14 and the first reference point RP1. In this case, the second voltage detection unit 16 corrects the second detection voltage value VD based on the potential difference between the first reference point RP1 and the second reference point RP2. Furthermore, in this embodiment, the first voltage detection unit 14 and the second voltage detection unit 16 are provided in the first unit 21 and the second unit 22, respectively, but as shown in FIG. 4, the first voltage detection unit 14 and the second voltage detection unit 16 may be configured as an integrated unit.

[0083] 1, the power supply controller 18 calculates the first calculated power value W1 based on a power value calculation formula D1 that indicates the relationship between the first detected current value AU, the first detected voltage value VU, the second detected voltage value VD, and the first calculated power value W1. The memory 18M of the power supply controller 18 stores the power value calculation formula D1.

[0084] For example, a power value calculation formula D1 indicating the relationship between the first detected current value AU, the first detected voltage value VU, the second detected voltage value VD, and the first calculated power value W1 is expressed by the following formula (1).

[0085] W1 = (VU-VD) × AU = ΔV × AU (1) The first current detection unit 12 outputs the first detected current value AU constantly or at a predetermined cycle. The first voltage detection unit 14 outputs the first detected voltage value VU constantly or at a predetermined cycle. The second voltage detection unit 16 outputs the second detected voltage value VD constantly or at a predetermined cycle. The power supply controller 18 stores the latest first detected current value AU, the latest first detected voltage value VU, and the latest second detected voltage value VD in the memory 18M. The power supply controller 18 calculates the first calculated power value W1 at a predetermined cycle based on the latest first detected current value AU, the latest first detected voltage value VU, the latest second detected voltage value VD, and the power value calculation formula D1. The memory 18M stores the latest first calculated power value W1.

[0086] 5, when the first calculated power value W1 is equal to or less than the power threshold W0, the power supply controller 18 allows power supply through the electric wire 8. Specifically, when the first calculated power value W1 is equal to or less than the power threshold W0, the processor 18P of the power supply controller 18 transmits a current command to the gate driver 24G of the switch circuit 24. The gate driver 24G supplies a gate voltage to the FET 24F of the switch circuit 24 based on the current command. The supply of the gate voltage causes the FET 24F to allow power supply from the power supply device 4 to the load 6. As a result, power is supplied from the power supply device 4 to the load 6.

[0087] On the other hand, when the first calculated power value W1 exceeds the power threshold W0, the power supply controller 18 cuts off the power supply through the electric wire 8. When the first calculated power value W1 exceeds the power threshold W0, the processor 18P of the power supply controller 18 sends a power supply stop command to the gate driver 24G of the switch circuit 24. The gate driver 24G stops the supply of gate voltage to the FET 24F of the switch circuit 24 based on the power supply stop command. By stopping the supply of gate voltage, the FET 24F of the switch circuit 24 cuts off the power supply from the power supply device 4 to the load 6.

[0088] As shown in FIG. 6, the relationship between the first detected current value AU, the first detected voltage value VU, the second detected voltage value VD, and the resistance value R is expressed by the following formula (2).

[0089] ΔV = VU - VD = AU × R (2) However, as shown in the following formula (3), a voltage error ΔVE1 may occur when the first detected current value AU is zero.

[0090] ΔV=AU×R+ΔVE1 (3) Therefore, the power supply controller 18 corrects the error in the power value calculation formula D1 based on the first detected voltage value VU and the second detected voltage value VD output from the voltage detection unit 13 when the first detected current value AU is zero. The power supply controller 18 corrects the error in the difference ΔV between the first detected voltage value VU and the second detected voltage value VD based on the first detected voltage value VU and the second detected voltage value VD output from the voltage detection unit 13 when the first detected current value AU is zero.

[0091] The state in which the first detected current value AU is zero includes, for example, a state in which the power supply controller 18 cuts off the power supply via the electric wire 8. The voltage error ΔVE1 (=VU0-VD0) can be calculated using the first detected voltage value VU and the second detected voltage value VD in the state in which the first detected current value AU is zero. This makes it possible to correct the voltage error ΔVE1 of the difference ΔV used in the power value calculation formula D1. That is, a zero point correction can be performed for the voltage detection unit 13 (in this embodiment, the first voltage detection unit 14 and the second voltage detection unit 16).

[0092] If the potential difference ΔV is corrected by the voltage error ΔVE1, the multiple first detected current values ​​AU, the multiple first detected voltage values ​​VU, and the multiple second detected voltage values ​​VD should be plotted on a straight line passing through the origin in the graph shown in FIG. 6.

[0093] 6, even if the power value calculation formula D1 is corrected with the voltage error ΔVE1, the multiple first detected current values ​​AU, the multiple first detected voltage values ​​VU, and the multiple second detected voltage values ​​VD cannot be plotted on a straight line passing through the origin, and the straight line passing through the multiple points defined by the multiple first detected current values ​​AU (e.g., AU1 and AU2) and the multiple potential differences ΔV (e.g., ΔV1 and ΔV2) may deviate from the origin by the voltage error ΔVE2. This is expressed by the following formula (4).

[0094] ΔV=AU×R+ΔVE2 (4) Therefore, the power supply controller 18 corrects the error in the power value calculation formula D1 based on a plurality of different first detected current values ​​AU output from the first current detection unit 12 at a plurality of different detection timings, a plurality of different first detected voltage values ​​VU output from the voltage detection unit 13 (in this embodiment, the first voltage detection unit 14) at a plurality of different detection timings, and a plurality of different second detected voltage values ​​VD output from the voltage detection unit 13 (in this embodiment, the second voltage detection unit 16) at a plurality of different detection timings.

[0095] For example, the power supply controller 18 corrects the error in the difference ΔV between the first detected voltage value VU and the second detected voltage value VD based on a plurality of different first detected current values ​​AU1 and AU2, a plurality of different first detected voltage values ​​VU1 and VU2, and a plurality of different second detected voltage values ​​VD1 and VD2.

[0096] If the difference between the first detected voltage value VU1 and the second detected voltage value VD1 is a potential difference ΔV1, the relationship between the potential difference ΔV1, the first detected current value AU1, and the resistance value R is expressed by the following formula (5).

[0097] ΔV1=AU1×R+ΔVE2 (5) If the difference between the first detected voltage value VU2 and the second detected voltage value VD2 is a potential difference ΔV2, the relationship between the potential difference ΔV2, the first detected current value AU2, and the resistance value R is expressed by the following equation (6).

[0098] ΔV2=AU2×R+ΔVE2 (6) From equations (5) and (6), the voltage error ΔVE2 of equation (4) is expressed by the following equation (7).

[0099] ΔVE2=(ΔV2×AU1-ΔV1×AU2) / (AU1-AU2) (7) By using the voltage error ΔVE2 expressed by formula (7), the error in the potential difference ΔV expressed by formula (4) can be corrected. That is, the power supply controller 18 can correct the error in the power value calculation formula D1 caused by the voltage error ΔVE2, based on the multiple different first detected current values ​​AU1 and A2, the multiple different first detected voltage values ​​VU1 and VU2, and the multiple different second detected voltage values ​​VD1 and VD2.

[0100] However, the above error correction is based on the premise that the resistance value R is constant. However, there may be cases where the resistance value R in the power value calculation formula D1 of the electric wire 8 changes in response to a change in the temperature of the electric wire 8.

[0101] Therefore, the power supply controller 18 corrects the voltage error ΔVE2 of the potential difference ΔV during a period when the temperature of the electric wire 8 is assumed to be relatively low. The period when the temperature of the electric wire 8 is assumed to be relatively low may be, for example, a period when the first detected current value AU is relatively low.

[0102] For example, as shown in Figures 5 and 7, the power supply controller 18 corrects an error in the power value calculation formula D1 based on a plurality of different first detected current values ​​AU output from the first current detection unit 12 at a plurality of different detection timings in the first judgment period P1 in which the first detected current value AU is equal to or less than the reference current value A0, a plurality of different first detected voltage values ​​VU output from the voltage detection unit 13 (in this embodiment, the first voltage detection unit 14) at a plurality of different detection timings in the first judgment period P1, and a plurality of different second detected voltage values ​​VD output from the voltage detection unit 13 (in this embodiment, the second voltage detection unit 16) at a plurality of different detection timings in the first judgment period P1.

[0103] Specifically, the power supply controller 18 corrects the error in the difference ΔV between the first detection voltage value VU and the second detection voltage value VD using equation (7) based on a plurality of different first detection current values ​​AU (e.g., AU1 and AU2) in the first judgment period P1, a plurality of different first detection voltage values ​​VU (e.g., VU1 and VU2) in the first judgment period P1, and a plurality of different second detection voltage values ​​VD (e.g., VD1 and VD2) in the first judgment period P1.

[0104] Furthermore, a period during which the temperature of the electric wire 8 is assumed to be relatively low may be, for example, immediately after the start-up of the vehicle 2 (for example, a period from the start-up of the vehicle 2 until a predetermined time has elapsed). Here, the start-up of the vehicle 2 includes, for example, the start-up of the drive system of the vehicle 2 in response to a user's operation on the start-up operation unit 2A (for example, see FIG. 1). An example of the start-up of the drive system of the vehicle 2 includes the system of the vehicle 2 switching from an off state to a state in which the vehicle 2 is capable of running. More specifically, an example of the start-up of the drive system of the vehicle 2 includes the start-up of the engine of the vehicle 2, and the system of the vehicle 2 switching from an off state to a state in which power supply to the vehicle drive motor can begin.

[0105] As shown in FIG. 7, the power supply controller 18 corrects an error in the power value calculation formula D1 based on a plurality of different first detected current values ​​AU output from the first current detection unit 12 at a plurality of different detection timings during a first judgment period P1 in which the first detected current value AU is equal to or less than the reference current value A0 and during a second judgment period P2 from the start of the vehicle until a predetermined time has elapsed, a plurality of different first detected voltage values ​​VU output from the voltage detection unit 13 (in this embodiment, the first voltage detection unit 14) at a plurality of different detection timings during the first judgment period P1 and the second judgment period P2, and a plurality of different second detected voltage values ​​VD output from the voltage detection unit 13 (in this embodiment, the second voltage detection unit 16) at a plurality of different detection timings during the first judgment period P1 and the second judgment period P2.

[0106] Specifically, the power supply controller 18 corrects the error in the difference ΔV between the first detection voltage value VU and the second detection voltage value VD based on a plurality of different first detection current values ​​AU (e.g., AU1 and AU2) in the first judgment period P1 and the second judgment period P2, a plurality of different first detection voltage values ​​VU (e.g., VU1 and VU2) in the first judgment period P1 and the second judgment period P2, and a plurality of different second detection voltage values ​​VD (e.g., VD1 and VD2) in the first judgment period P1 and the second judgment period P2.

[0107] Here, the second judgment period P2 includes an inrush current period P21 during which the first current detection unit 12 detects the inrush current value, and a steady current period P22 during which the first current detection unit 12 detects the steady current value after the inrush current period P21. The inrush current value is different from the steady current value. For example, the inrush current value has a peak, and the maximum value of the inrush current value is higher than the maximum value of the steady current value. Since the difference between the inrush current value and the steady current value is relatively large, the difference between the inrush voltage value corresponding to the inrush current value and the steady voltage value corresponding to the steady current value is also relatively large. It can be expected that the accuracy of correction of the voltage error ΔVE2 will increase as the difference between the inrush current value and the steady current value increases.

[0108] Therefore, the power supply controller 18 corrects the error in the power value calculation formula D1 caused by the voltage error ΔVE2 using the first detected current value AU, the first detected voltage value VU, and the second detected voltage value VD in the inrush current period P21 and the steady current period P22, respectively.

[0109] Specifically, the multiple different first detected current values ​​AU include an inrush current value (e.g., A1) and a steady-state current value (e.g., A2). The multiple different first detected voltage values ​​VU include a first inrush voltage value (e.g., VU1) and a first steady-state voltage value (e.g., VD1) corresponding to the inrush current value and the steady-state current value, respectively. The multiple different second detected voltage values ​​VD include a second inrush voltage value (e.g., VU2) and a second steady-state voltage value (e.g., VD2) corresponding to the inrush current value and the steady-state current value, respectively. The power supply controller 18 corrects an error in the power value calculation formula D1 based on the inrush current value A1, the steady-state current value A2, the first inrush voltage value VU1, the first steady-state voltage value VD1, the second inrush voltage value VU2, and the second steady-state voltage value VD2. The power supply controller 18 corrects the error in the difference ΔV between the first detected voltage value VU and the second detected voltage value VD based on the inrush current value A1, the steady-state current value A2, the first inrush voltage value VU1, the first steady-state voltage value VD1, the second inrush voltage value VU2, and the second steady-state voltage value VD2.

[0110] For example, the power supply controller 18 monitors the first detected current value AU, the first detected voltage value VU, and the second detected voltage value VD from the start of the vehicle 2 until the second determination period P2 has elapsed. The power supply controller 18 stores in the memory 18M the maximum value A1 of the first detected current value AU, the first detected voltage value VU1 corresponding to the maximum value A1 of the first detected current value AU, and the second detected voltage value VD1 corresponding to the maximum value A1 of the first detected current value AU. The maximum value A1 of the first detected current value AU is usually detected during an inrush current period P21. The power supply controller 18 monitors the period from when the power supply is received from the power supply device 4 until a predetermined time has elapsed as the inrush current period P21.

[0111] After detecting the maximum value of the first detected current value AU, the power supply controller 18 stores in the memory 18M the minimum value A2 of the first detected current value AU, the first detected voltage value VU2 corresponding to the minimum value A2 of the first detected current value AU, and the second detected voltage value VD2 corresponding to the minimum value A2 of the first detected current value AU. The minimum value A2 of the first detected current value AU is usually detected in the steady current period P22. The power supply controller 18 monitors the period from the end of the inrush current period P21 until the end of a predetermined time as the steady current period P22.

[0112] After the second determination period P2 has elapsed, the power supply controller 18 corrects the error in the power value calculation formula D1 caused by the voltage error ΔVE2 using formula (7). In this way, the power supply controller 18 corrects the error in the power value calculation formula D1 caused by the voltage error ΔVE2 immediately after the start of the vehicle 2.

[0113] 1, the power supply controller 18 calculates the power of the electric wire 8 as a second calculated power value W2 based on the second detected current value AD, the first detected voltage value VU, and the second detected voltage value VD. The power supply controller 18 calculates the second calculated power value W2 based on a power value calculation formula D2 that indicates the relationship between the second detected current value AD, the first detected voltage value VU, the second detected voltage value VD, and the second calculated power value W2. The memory 18M of the power supply controller 18 stores the power value calculation formula D2.

[0114] For example, a power value calculation formula D2 indicating the relationship between the second detected current value AD, the first detected voltage value VU, the second detected voltage value VD, and the second calculated power value W2 is expressed by the following formula (8).

[0115] W2 = (VU-VD) × AD = ΔV × AD (8) The second current detection unit 19 outputs the second detected current value AD constantly or at a predetermined cycle. The first voltage detection unit 14 outputs the first detected voltage value VU constantly or at a predetermined cycle. The second voltage detection unit 16 outputs the second detected voltage value VD constantly or at a predetermined cycle. The power supply controller 18 stores the latest second detected current value AD, the latest first detected voltage value VU, and the latest second detected voltage value VD in the memory 18M. The power supply controller 18 calculates the second calculated power value W2 at a predetermined cycle based on the latest second detected current value AD, the latest first detected voltage value VU, the latest second detected voltage value VD, and the power value calculation formula D2. The memory 18M stores the latest second calculated power value W2. When the power supply controller 18 calculates the second calculated power value W2 using the formula (8), it uses the potential difference ΔV corrected by the voltage errors ΔVE1 and ΔVE2.

[0116] The power supply controller 18 calculates the power of the electric wire 8 as a third calculated power value W3 based on the third detected current value AX, the first detected voltage value VU, and the second detected voltage value VD. The power supply controller 18 calculates the third calculated power value W3 based on a power value calculation formula D3 that indicates the relationship between the third detected current value AX, the first detected voltage value VU, the second detected voltage value VD, and the third calculated power value W3. The memory 18M of the power supply controller 18 stores the power value calculation formula D3.

[0117] For example, a power value calculation formula D3 indicating the relationship between the third detected current value AX, the first detected voltage value VU, the second detected voltage value VD, and the third calculated power value W3 is expressed by the following formula (9).

[0118] W3 = (VU-VD) × AX = ΔV × AX (9) The second current detection unit 19 outputs the third detected current value AX constantly or at a predetermined cycle. The first voltage detection unit 14 outputs the first detected voltage value VU constantly or at a predetermined cycle. The second voltage detection unit 16 outputs the second detected voltage value VD constantly or at a predetermined cycle. The power supply controller 18 stores the latest third detected current value AX, the latest first detected voltage value VU, and the latest second detected voltage value VD in the memory 18M. The power supply controller 18 calculates the third calculated power value W3 at a predetermined cycle based on the latest third detected current value AX, the latest first detected voltage value VU, the latest second detected voltage value VD, and the power value calculation formula D3. The memory 18M stores the latest third calculated power value W3. When the power supply controller 18 calculates the third calculated power value W3 using the formula (9), it uses the potential difference ΔV corrected by the voltage errors ΔVE1 and ΔVE2.

[0119] 8, the power supply controller 18 limits the power supply through the electric wire 8 based on the first calculated power value W1 and the second calculated power value W2. The power supply controller 18 calculates the difference between the first calculated power value W1 and the second calculated power value W2 as the first power difference ΔW12. Since the first detected current value AU and the second detected current value AD are usually approximately the same, the first calculated power value W1 and the second calculated power value W2 are also approximately the same, and the first power difference ΔW12 is approximately zero.

[0120] However, if some of the multiple strands of the electric wire 8 break and break through the insulating coating, coming into contact with another component such as the housing, or if the insulating coating deteriorates, the second detected current value AD may become lower than the first detected current value AU. When the second detected current value AD becomes lower than the first detected current value AU, the second calculated power value W2 becomes smaller than the first calculated power value W1, and the first power difference ΔW12 increases.

[0121] Therefore, when the first power difference ΔW12 exceeds the threshold value W20, the power supply controller 18 cuts off the power supply through the electric wire 8. When the first power difference ΔW12 is equal to or smaller than the threshold value W20, the power supply controller 18 allows the power supply through the electric wire 8.

[0122] 9, the power supply controller 18 limits the power supply through the electric wire 8 based on the first calculated power value W1 and the third calculated power value W3. The power supply controller 18 calculates the difference between the first calculated power value W1 and the third calculated power value W3 as the second power difference ΔW13. Since the first detected current value AU and the third detected current value AX are usually approximately the same, the first calculated power value W1 and the third calculated power value W3 are also approximately the same, and the second power difference ΔW13 is approximately zero.

[0123] However, if there is some defect in the electric wire 8 or other current-carrying parts, the third detected current value AX may become lower than the first detected current value AU. If the third detected current value AX becomes lower than the first detected current value AU, the third calculated power value W3 becomes smaller than the first calculated power value W1, and the second power difference ΔW13 increases.

[0124] Therefore, when the second power difference ΔW13 exceeds the threshold value W30, the power supply controller 18 cuts off the power supply through the electric wire 8. When the second power difference ΔW13 is equal to or smaller than the threshold value W30, the power supply controller 18 allows the power supply through the electric wire 8.

[0125] The operation of the wire protection device 10 will be described with reference to FIGS.

[0126] 10, after the vehicle 2 is started, power supply to the wire protection device 10 is started (steps S1 and S2). At this time, power supply to the load 6 is cut off by the wire protection device 10. In the wire protection device 10, the first current value AU, the second current value AD, the third current value AX, the first voltage value VU, and the second voltage value VD are started to be obtained by the first current detection unit 12, the second current detection unit 19, the third current detection unit 20, and the voltage detection unit 13 (in this embodiment, the first voltage detection unit 14 and the second voltage detection unit 16) (step S3).

[0127] The first detected current value AU, the second detected current value AD, the third detected current value AX, the first detected voltage value VU, and the second detected voltage value VD outputted from the first current detection unit 12, the second current detection unit 19, the third current detection unit 20, the first voltage detection unit 14, and the second voltage detection unit 16, respectively, are inputted to the power supply controller 18 at a predetermined period.

[0128] The first detected current value AU, the second detected current value AD, the third detected current value AX, the first detected voltage value VU, and the second detected voltage value VD input to the power supply controller 18 at the same timing are associated with each other and stored in memory 18M of the power supply controller 18. The latest first detected current value AU, the latest second detected current value AD, the latest third detected current value AX, the latest first detected voltage value VU, and the latest second detected voltage value VD are associated with each other and stored in memory 18M of the power supply controller 18.

[0129] Before power supply to the load 6 is started, the errors in the power value calculation formulas D1, D2, and D3 caused by the voltage error ΔVE1 are corrected by the power supply controller 18 based on the first detected voltage value VU and the second detected voltage value VD (step S4).

[0130] After the error correction of the power value calculation formula D1, the voltage line VL4 is connected by the switch circuit 24 of the power supply controller 18, and power supply to the load 6 is started (step S5). After the power supply to the load 6 is started, the maximum value of the inrush current value is determined by the power supply controller 18 during the inrush current period P21 (step S6). The first detection voltage value VU input to the power supply controller 18 at the same timing as the maximum value of the inrush current value is selected by the power supply controller 18 as the first detection voltage value VU corresponding to the maximum value of the inrush current value (step S7). Similarly, the second detection voltage value VD input to the power supply controller 18 at the same timing as the maximum value of the inrush current value is selected by the power supply controller 18 as the second detection voltage value VD corresponding to the maximum value of the inrush current value (step S8). The maximum value of the inrush current value, the first detection voltage value VU corresponding to the maximum value of the inrush current value, and the second detection voltage value VD corresponding to the maximum value of the inrush current value are stored in the memory 18M of the power supply controller 18.

[0131] After the inrush current period P21 has elapsed, the minimum value of the steady-state current value is determined by the power supply controller 18 during the steady-state current period P22 (step S9). The first detected voltage value VU input to the power supply controller 18 at the same timing as the minimum value of the steady-state current value is selected by the power supply controller 18 as the first detected voltage value VU corresponding to the minimum value of the steady-state current value (step S10). Similarly, the second detected voltage value VD input to the power supply controller 18 at the same timing as the minimum value of the steady-state current value is selected by the power supply controller 18 as the second detected voltage value VD corresponding to the minimum value of the steady-state current value (step S11). The minimum value of the steady-state current value, the first detected voltage value VU corresponding to the minimum value of the steady-state current value, and the second detected voltage value VD corresponding to the minimum value of the steady-state current value are stored in the memory 18M of the power supply controller 18.

[0132] 11, the power supply controller 18 determines whether the first detected current value AU is equal to or less than the reference current value A0 (step S12). If the first detected current value AU is equal to or less than the reference current value A0, the power supply controller 18 corrects the errors in the power value calculation formulas D1, D2, and D3 caused by the voltage error ΔVE2 based on the first detected current value AU, the first detected voltage value VU, and the second detected voltage value VD (steps S12 and S13). On the other hand, if the first detected current value AU exceeds the reference current value A0, the error in the power value calculation formula D1 caused by the voltage error ΔVE2 is not corrected by the power supply controller 18 (step S12).

[0133] The power supply controller 18 calculates a first calculated power value W1 based on the first detected current value AU, the first detected voltage value VU, the second detected voltage value VD, and the power value calculation formula D1 (step S14). The power supply controller 18 calculates a second calculated power value W2 based on the second detected current value AD, the first detected voltage value VU, the second detected voltage value VD, and the power value calculation formula D2 (step S15). The power supply controller 18 calculates a third calculated power value W3 based on the third detected current value AX, the first detected voltage value VU, the second detected voltage value VD, and the power value calculation formula D3 (step S16).

[0134] The power supply controller 18 calculates a first power difference ΔW12 based on the first calculated power value W1 and the second calculated power value W2 (step S17). The power supply controller 18 calculates a second power difference ΔW13 based on the first calculated power value W1 and the third calculated power value W3 (step S18).

[0135] The power supply controller 18 determines whether there is an abnormality in the electric wire 8 based on the first calculated power value W1. Specifically, when the first calculated power value W1 exceeds the power threshold value W0, the power supply controller 18 cuts off the power supply to the load 6 (steps S19 and S22). When the first calculated power value W1 is equal to or less than the power threshold value W0, the power supply controller 18 determines whether there is an abnormality in the electric wire 8 based on the first power difference ΔW12 (steps S19 and S20). Specifically, when the first power difference ΔW12 exceeds the threshold value W20, the power supply controller 18 cuts off the power supply to the load 6 (steps S20 and S22). When the first power difference ΔW12 is equal to or less than the threshold value W20, the power supply controller 18 determines whether there is an abnormality in the electric wire 8 based on the second power difference ΔW13 (steps S20 and S21). Specifically, when the second power difference ΔW13 exceeds the threshold value W30, the power supply controller 18 cuts off the power supply to the load 6 (steps S21 and S22). When the second power difference ΔW13 is equal to or smaller than the threshold value W30, the process returns to step S12 (step S21). Steps S12 to S21 are repeated until an abnormality in the electric wire 8 is detected or the vehicle 2 is turned OFF.

[0136] As described above, in the wire protection device 10, the power supply controller 18 calculates the power consumption of the wire 8 as the first calculated power value W1 based on the first detected current value AU, the first detected voltage value VU, and the second detected voltage value VD, and limits the power supply through the wire 8 based on the first calculated power value W1. This makes it possible to more accurately grasp the state of the wire 8 and appropriately protect the wire 8 from overheating.

[0137] In the above embodiment, the power threshold W0 corresponds to a steady current, but the power supply controller 18 may be configured to change the power threshold depending on whether the current is an inrush current or a steady current.

[0138] Moreover, the process of correcting the error in the potential difference ΔV can be at least partially omitted.

[0139] In this application, the term "comprise" and its derivatives are non-restrictive terms that describe the presence of elements and do not exclude the presence of other elements not described. This also applies to the terms "have", "include" and their derivatives.

[0140] In this application, ordinal numbers such as "first" and "second" are merely terms for identifying components and do not have any other meaning (e.g., a particular order, etc.). For example, the presence of a "first element" does not imply the presence of a "second element," and the presence of a "second element" does not imply the presence of a "first element."

[0141] Words expressing degrees such as "substantially," "about," and "approximately" can refer to reasonable deviations that do not significantly change the end result. All numerical values ​​described in this application can be interpreted to include words such as "substantially," "about," and "approximately."

[0142] In addition, the expression "at least one of A and B" in this disclosure includes, for example, any of (1) A only, (2) B only, and (3) both A and B. The expression "at least one of A, B, and C" includes, for example, any of (1) A only, (2) B only, (3) C only, (4) A and B, (5) B and C, (6) A and C, and (7) all of A, B, and C. In this disclosure, the expression "at least one of A and B" is not to be interpreted as "at least one of A and at least one of B."

[0143] It is apparent that various changes and modifications of the present invention are possible in light of the above disclosure, and therefore, the present invention may be practiced otherwise than as specifically disclosed herein without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0144] 2: Vehicle 4:Power supply 6: Load 8:Electric wire 8U: First voltage detection point 8D: Second voltage detection point 10: Wire protection device 12: First current detection section 13: Voltage detection section 14: First voltage detection unit 16: Second voltage detection section 18: Power supply controller 19: Second current detection section 20: Third current detection section A0: Reference current value AU: First detected current value AD: Second detection current value AU1: First detected current value AU2: First detected current value AX: Third detection current value P1: First judgment period P2: 2nd judgment period P21: Inrush current period P22: Steady current period RP1: 1st reference point RP2: 2nd reference point VU: First detection voltage value VD: Second detection voltage value W0: Power threshold W1: First calculated power value W2: Second calculated power value W3: Third calculated power value

Claims

1. a first current detection unit that detects a current value of an electric wire connecting the power supply device to a load as a first detected current value; a voltage detection unit that detects a voltage value at a first voltage detection point provided between the power supply device and the electric wire as a first detected voltage value, and detects a voltage value at a second voltage detection point provided between the electric wire and the load as a second detected voltage value; a power supply controller that calculates a first calculated power value of the electric wire based on the first detected current value, the first detected voltage value, and the second detected voltage value, and limits power supply through the electric wire based on the first calculated power value; the power supply controller calculates the first calculated power value based on a power value calculation formula indicating a relationship between the first detected current value, the first detected voltage value, the second detected voltage value, and the first calculated power value; the power supply controller corrects an error in the power value calculation formula based on the first detected voltage value and the second detected voltage value output from the voltage detection unit in a state in which the power supply via the electric wire is interrupted. Wire protection device.

2. The power supply controller cuts off the power supply through the electric wire when the first calculated power value exceeds a power threshold. The wire protection device of claim 1 .

3. The power supply controller allows the power supply through the electric wire when the first calculated power value is equal to or less than the power threshold. The wire protection device according to claim 2 .

4. the power supply controller corrects an error in the power value calculation formula based on a plurality of different first detected current values ​​output from the first current detection unit at a plurality of different detection timings, a plurality of different first detected voltage values ​​output from the voltage detection unit at the plurality of different detection timings, and a plurality of different second detected voltage values ​​output from the voltage detection unit at the plurality of different detection timings. The wire protection device according to any one of claims 1 to 3.

5. the power supply controller corrects an error in the power value calculation formula based on the plurality of different first detected current values ​​output from the first current detection unit at the plurality of different detection timings in a first determination period in which the first detected current value is equal to or less than a reference current value, the plurality of different first detected voltage values ​​output from the voltage detection unit at the plurality of different detection timings in the first determination period, and the plurality of different second detected voltage values ​​output from the voltage detection unit at the plurality of different detection timings in the first determination period. The wire protection device according to claim 4.

6. the power supply controller corrects an error in the power value calculation formula based on the multiple different first detected current values ​​output from the first current detection unit at the multiple different detection timings during the first determination period in which the first detected current value is equal to or less than a reference current value and during a second determination period until a predetermined time has elapsed since startup of the vehicle, the multiple different first detected voltage values ​​output from the voltage detection unit at the multiple different detection timings during the first determination period and the second determination period, and the multiple different second detected voltage values ​​output from the voltage detection unit at the multiple different detection timings during the first determination period and the second determination period. The wire protection device according to claim 5.

7. the second determination period includes an inrush current period in which the first current detection unit detects an inrush current value, and a steady current period in which the first current detection unit detects a steady current value after the inrush current period, the plurality of different first detected current values ​​include the inrush current value and the steady-state current value; the plurality of different first detected voltage values ​​include a first inrush voltage value and a first steady-state voltage value corresponding to the inrush current value and the steady-state current value, respectively; the plurality of different second detected voltage values ​​include a second inrush voltage value and a second steady-state voltage value corresponding to the inrush current value and the steady-state current value, respectively; the power supply controller corrects an error in the power value calculation formula based on the inrush current value, the steady-state current value, the first inrush voltage value, the first steady-state voltage value, the second inrush voltage value, and the second steady-state voltage value. The wire protection device according to claim 6.

8. the voltage detection unit includes a first voltage detection unit that detects a voltage value at the first voltage detection point as the first detected voltage value, and a second voltage detection unit that detects a voltage value at the second voltage detection point as the second detected voltage value. The wire protection device according to any one of claims 1 to 7.

9. the first voltage detection unit is connected to the first voltage detection point that is disposed on a voltage line provided between the power supply device and the load, and to a first reference point that is disposed on a ground line provided between the power supply device and the load and serves as a reference for the first detected voltage value; the second voltage detection unit is connected to the second voltage detection point disposed on the voltage line and to a second reference point disposed on the ground line and serving as a reference for the second detected voltage value; 9. The wire protection device of claim 8.

10. the second reference point is provided at a position on the ground line different from a position of the first reference point; 10. The wire protection device of claim 9.

11. the second voltage detection unit is connected to a line connecting the first voltage detection unit and the first reference point, and corrects the second detected voltage value based on a potential difference between the first reference point and the second reference point. The wire protection device of claim 10.

12. The second reference point is provided on a line connecting the first voltage detection unit and the first reference point.

10. The wire protection device of claim 9.

13. The second reference point is provided at the same position as the first reference point.

13. The wire protection device of claim 12.

14. The first voltage detection unit and the second voltage detection unit are configured as an integral unit. The wire protection device according to any one of claims 8 to 13.

15. A first unit; A second unit disposed at a position distant from the first unit, the first unit includes the first voltage detection unit, The second unit includes the second voltage detection unit. The wire protection device according to any one of claims 8 to 13.

16. a second current detection unit provided between the electric wire and the load and configured to detect a current value of the electric wire as a second detected current value; The wire protection device according to any one of claims 1 to 15.

17. the power supply controller calculates the power of the electric wire as a second calculated power value based on the second detected current value, the first detected voltage value, and the second detected voltage value, and limits the power supply through the electric wire based on the first calculated power value and the second calculated power value.

17. The wire protection device of claim 16.

18. A third current detection unit detects a current value of the electric wire as a third detected current value, the first current detection unit is disposed on a voltage line; the third current detection unit is disposed on a ground line; 18. A wire protection device according to any one of claims 1 to 17.

19. the power supply controller calculates the power of the electric wire as a third calculated power value based on the third detected current value, the first detected voltage value, and the second detected voltage value, and limits the power supply through the electric wire based on the first calculated power value and the third calculated power value.

20. The wire protection device of claim 18.

20. The power supply device; The load; The electric wire; The wire protection device according to any one of claims 1 to 19, The wire protection device is electrically connected to the power supply device, The wire protection device is electrically connected to the load, No other device is electrically connected between the power supply device and the wire protection device, No other equipment is electrically connected between the wire protection device and the load. In-vehicle systems.

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