Electric wire temperature estimation device

Abstract

To provide an electric wire temperature estimation device in which an electric wire temperature during startup of a vehicle power source is calculated, whereby the accuracy of estimating an electric wire temperature after the startup can be improved.SOLUTION: An electric wire temperature estimation device includes a control unit that estimates an electric wire temperature on the basis of a current value of a vehicle power source, for example. The control unit acquires an electric wire temperature during stop of the vehicle power source and a lapse time from the stop to startup of the vehicle power source, calculates an electric wire temperature during startup of the vehicle power source on the basis of the electric wire temperature during stop of the vehicle power source and a heat dissipation amount of the electric wire calculated using the lapse time, sets the calculated temperature as an initial temperature, and estimates an electric wire temperature after startup of the vehicle power source on the basis of the initial temperature.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an electric wire temperature estimation device. [Background technology]

[0002] It has been disclosed in the past that whether or not the current flowing through an electric wire is an overcurrent is estimated based on the current flowing through the electric wire and the estimated temperature of a semiconductor fuse, and if it is determined to be an overcurrent, the current is controlled or cut off by the semiconductor fuse. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-103897 Summary of the Invention [Problem to be solved by the invention]

[0004] However, since the determination is based on the current flowing through the wire and the estimated temperature of the semiconductor fuse, the wire temperature at startup is not taken into consideration. As a result, a difference may occur between the actual wire temperature and the estimated temperature depending on the startup timing, which could result in a discrepancy between the actual wire temperature and the estimated temperature at the time of temperature determination.

[0005] An object of the present invention is to provide an electric wire temperature estimation device that can improve the accuracy of estimating the temperature of an electric wire after a vehicle power supply is started by calculating the temperature of the electric wire when the vehicle power supply is started. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the electric wire temperature estimation device of the present invention includes a control unit that estimates the electric wire temperature based on the current value of the vehicle power supply, and the control unit acquires the electric wire temperature when the vehicle power supply is stopped and the elapsed time from when the vehicle power supply is stopped to when it is started, calculates the electric wire temperature when the vehicle power supply is started based on the electric wire temperature when the vehicle power supply is stopped and the amount of heat dissipation of the electric wire calculated using the elapsed time, sets the calculated temperature as an initial temperature, and estimates the electric wire temperature after the vehicle power supply is started based on the initial temperature. [Effects of the Invention]

[0007] According to the present invention, when estimating the temperature of the electric wire, the initial temperature at the time of starting up the vehicle power supply can be calculated, thereby improving the accuracy of temperature estimation after the start-up of the vehicle power supply. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of a vehicle to which an electric wire temperature estimation device according to an embodiment of the present invention is applied. [Figure 2] FIG. 2 is a timing chart for explaining an example of control processing in the electric wire temperature estimation device according to one embodiment of the present invention. [Figure 3] FIG. 3 is a flowchart illustrating an example of a control process in the electric wire temperature estimation device according to one embodiment of the present invention. [Figure 4] FIG. 4 is a block diagram showing an example of the configuration of a vehicle to which an electric wire temperature estimation device according to the second embodiment of the present invention is applied. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0010] Fig. 1 is a block diagram showing an example of the configuration of a vehicle to which an electric wire temperature estimation device 10 according to one embodiment of the present invention is applied. As shown in Fig. 1, the electric wire temperature estimation device 10 includes a control unit 1, a second control unit 2, an IPD (Intelligent Power Device) 3, a power source 4, an auxiliary machine (load) 5, a SW (switch) input unit 6, an IG (ignition) switch 7, an electric wire 9, etc.

[0011] The control unit 1 is equipped with, for example, an ECU (Electronic Control Unit). The ECU has a microcontroller unit (microcomputer), which incorporates, for example, a CPU, a nonvolatile memory such as a flash (registered trademark) memory, and a volatile memory such as a DRAM (Dynamic Random Access Memory). The ECU is connected to enable bidirectional communication using the CAN (Controller Area Network) communication protocol. Various sensors required for control are connected to the ECU, and detection signals from the connected sensors are input to the ECU.

[0012] The control unit 1 is activated when a current flows through the control unit 1 when the power supply 4 is activated, for example, by the user (passenger) operating the IG switch 7. The control unit 1 receives an input signal from the SW input unit 6 and performs drive control to pass current through the auxiliary equipment 5. At this time, the control unit 1 detects the duration of current flow and the current value, and estimates the temperature of the electric wire 9 based on the results.

[0013] For example, if the electric wire 9 between the IPD 3 and the auxiliary device 5 is shorted due to deterioration or the like, the control unit 1 estimates that the temperature of the electric wire 9 is high and performs cut-off control on the IPD 3. This allows the IPD 3 to cut off the current to the auxiliary device 5. The control unit 1 may store data on the amount of heat dissipation per elapsed time for each electric wire.

[0014] Next, as an example, the IPD3 has the function of a semiconductor fuse. Conventional melt-type fuses are formed of metal such as a plate or wire, and the metal forming the fuse melts and cuts off the current in the electric wire when a current above a predetermined value flows. On the other hand, the IPD3 shown in this embodiment does not melt like a fuse, and therefore has the function of a semiconductor fuse that can repeatedly cut off and restore. This eliminates the need for fuse replacement. The IPD3 may also be an IPS (Intelligent Power Switch).

[0015] The IPD 3 is provided in a path between the control unit 1 and the auxiliary device 5, and prevents an overcurrent from flowing to the auxiliary device 5. The control unit 1, the IPD 3, and the auxiliary device 5 are connected by electric wires. When the IPD 3 receives cut-off control from the control unit 1, it cuts off the current flowing to the auxiliary device 5.

[0016] The IG switch 7 is operable, for example, from the driver's seat, and when the switch is turned ON by a user's switching operation, the vehicle's power supply 4 is activated. When the switch is turned OFF, the power supply 4 is deactivated. When the power supply 4 is activated, the control unit 1 is activated.

[0017] The SW input unit 6 is, for example, a switch provided inside the vehicle cabin. When the switch is operated, it is turned on and an input signal is sent to the control unit 1. When the switch is operated again, it is turned off. When the SW input unit 6 is switched on, the control unit 1 causes current to flow to the auxiliary device 5. The control unit 1 starts acquiring the elapsed time since the switch was turned on and the current value. It is also possible to acquire the elapsed time since the IG switch 7 was turned on and the current value.

[0018] The auxiliary device (load) 5 is, for example, a heater, and is driven by the drive control of the control unit 1. When the electric wire 9 or the like is short-circuited, the current to the auxiliary device 5 is cut off by the IPD 3.

[0019] The second control unit 2 is active even when the IG switch 7 is switched off, and is capable of measuring the elapsed time from when the IG switch 7 is switched off to when it is switched on. When the control unit 1 is activated, it can send the elapsed time from when the switch is switched off to when it is switched on. Furthermore, the second control unit 2 may constantly acquire the temperature of the electric wire 9 estimated by the control unit 1, or may acquire it at regular intervals. This allows it to acquire the temperature of the electric wire estimated by the control unit 1 when the switch is off, and when the switch is on, it can send to the control unit 1 the estimated temperature of the electric wire when the switch is off and the elapsed time from when the switch is off to when it is on. Note that the elapsed time from when the switch is switched off to when it is on by the SW input unit 6 may also be sent.

[0020] The power supply 4 is, for example, a battery pack made up of a combination of multiple secondary batteries. The secondary batteries are, for example, lithium ion batteries. The power supply 4 outputs DC power of, for example, about 200 to 350 V (volts). The power supply 4 may be provided above the floor panel inside the vehicle.

[0021] The vehicle of this embodiment is equipped with, as an example, a series hybrid system, which includes an engine, a generator motor (MG1), a drive motor (MG2), and a PCU (Power Control Unit).

[0022] The engine is, for example, a gasoline engine. The engine is equipped with a throttle body, a fuel injector that injects fuel into the intake air, etc. The throttle body is a component that takes in fuel and air and sends them to the engine's combustion chamber. It is equipped with an electronic throttle valve that adjusts the amount of intake air to the engine's combustion chamber, a throttle position sensor that detects the opening of the electronic throttle valve, and a control valve that adjusts the amount of intake air when the vehicle is idling, such as when stopped.

[0023] The generator motor is, for example, a permanent magnet synchronous motor. The rotating shaft of the generator motor is mechanically connected to the engine crankshaft via a gear. For example, an engine output gear is supported on the engine crankshaft so as not to rotate relative to the crankshaft, and a motor gear is supported on the generator motor rotating shaft so as not to rotate relative to the crankshaft, and the engine output gear and the motor gear are meshed.

[0024] The drive motor is, for example, a permanent magnet synchronous motor that is larger than the generator motor. The rotating shaft of the drive motor is connected to the vehicle's drivetrain. The drivetrain includes a differential gear, and the power of the drive motor is transmitted to the differential gear, and then distributed and transmitted from the differential gear to the drive wheels, which consist of the left and right front wheels or rear wheels. This causes the left and right drive wheels to rotate, causing the vehicle to move forward or backward.

[0025] The PCU is a unit for controlling the driving of the generator motor and the drive motor, and is equipped with an inverter and a converter.

[0026] When starting an engine, the DC power output from the power source is boosted by a converter, the boosted DC power is converted to AC power by an inverter, and the AC power is supplied to a generator motor. This causes the generator motor to operate in powered mode, and the engine is motored (cranked) by the generator motor. When the rotation speed of the engine crankshaft has increased to the rotation speed required for starting due to motoring, the engine starts when the engine's spark plug is fired.

[0027] Although a hybrid vehicle is used as an example, it may be, for example, an electric vehicle that does not have an engine 11. Also, it may be a gasoline vehicle, and the vehicle is not limited thereto.

[0028] Fig. 2 is a timing chart for explaining an example of control processing in the electric wire temperature estimation device 10 according to one embodiment of the present invention. As shown in Fig. 2, the vertical axis of Fig. 2 represents the electric wire temperature of the electric wire 9. The horizontal axis of Fig. 2 represents time t. The lower part of Fig. 2 shows the switching of the switch input unit 6 and the IG switch 7 between ON and OFF over time in accordance with the change in temperature of the electric wire 9 over time t.

[0029] 2 also shows graph G1, graph G2, temperatures A0, A1, A2, A3, A4, time 0, t1, and times t2 to t9. Time t=0 indicates time t when the IG switch 7 is turned on and the vehicle power supply is started. Time t1 indicates time t when the switch of the SW input unit 6 is turned on.

[0030] Temperature A0 is an example of a base temperature that indicates the ambient temperature before current is applied. Temperature A1 is an example of the initial temperature when the SW input unit 6 is switched from switch OFF to switch ON again. Temperature A2 is an example of a reference temperature that indicates the temperature at which the current sent to the auxiliary device 5 should be maintained appropriately. Temperature A3 is an example of a cutoff temperature at which the current is cut off. Temperature A4 is an example of a smoke temperature at which the electric wire 9 may emit smoke.

[0031] The IG switch 7 is switched off at time t3, stopping the power supply to the vehicle, and then switched on again at time t4 after a predetermined time has elapsed, starting up the power supply to the vehicle.

[0032] The SW input unit 6 can send an input signal to the control unit 1 when the IG switch 7 is switched on. t1 indicates a case where the SW input unit 6 is switched on by the user. This causes the control unit 1 to receive the signal and perform control to send current to the auxiliary equipment 5. t2 indicates a case where the SW input unit 6 is switched off. t5 indicates a case where the switch is switched on again. t8 indicates that the switch is on from t5 to t8, is switched off at t8, and is switched on again at t9.

[0033] Graph G1 shows the temperature change per predetermined time of the actual temperature of the electric wire 9. Graph G2 shows the temperature change per predetermined time of the temperature of the electric wire 9 estimated by the control unit 1.

[0034] The control unit 1 controls the current value to the auxiliary device 5 so that the electric wire temperature is maintained at an appropriate reference temperature A2. For example, if the electric wire 9 shorts out due to deterioration or the like, the cutoff temperature A3 exceeds the reference temperature A2. In this case, the control unit 1 controls the IPD 3 to stop the current to the auxiliary device 5. This makes it possible to cut off the current to the electric wire 9 even if the electric wire 9 shorts out due to deterioration or the like.

[0035] Next, the processing of the control unit 1 will be explained for each time from time t1 to time t9.

[0036] At time t1, the control unit 1 receives an input signal to turn the switch ON from the SW input unit 6 and controls the flow of current to the auxiliary device 5, thereby increasing the temperature of the electric wire 9. At this time, the control unit 1 estimates the temperature of the electric wire 9 by measuring the value of the current flowing to the auxiliary device 5 and the time for which the current is flowing.

[0037] At time t2, the control unit 1 receives an input signal to turn the switch OFF from the SW input unit 6 and performs control to stop the current to the auxiliary device 5.

[0038] The control unit 1 stops when the IG switch 7 is switched off at t3. The control unit 1 initializes the wire temperature and elapsed time. The control unit 1 sends the wire temperature to the second control unit 2. The timing for sending the wire temperature to the second control unit 2 may be constant or at a fixed interval.

[0039] The control unit 1 is started when the IG switch 7 is turned on at t4.

[0040] At time t5, the control unit 1 receives an input signal to turn on the switch of the SW input unit 6. As a result, the control unit 1 controls the flow of current to the auxiliary device 5.

[0041] At this time, it is assumed that the interval from t2 to t5 is short, that is, the interval from switching OFF to switching ON of the SW input unit 6 is short. For example, even if the wire temperature hardly drops below the reference temperature A2, the temperature estimated by the control unit 1 shown in G2 is returned to and set as the base temperature.

[0042] Therefore, when the switch input unit 6 is turned ON again at time t5, the estimated temperature G2 is lower than the actual temperature G1. As a result, a difference occurs between the actual temperature and the estimated temperature. For example, if the electric wire 9 shorts out after time has passed from time t5, the actual temperature may reach the cutoff temperature A3 before the estimated temperature.

[0043] On the other hand, in this embodiment, at t5, the control unit 1 acquires the wire temperature at t2 and the elapsed time from t2 to t5 from the second control unit 2. This allows the control unit 1 to calculate the amount of heat dissipation per elapsed time for each wire, and estimate the wire temperature at t5 from the wire temperature at t2 and the amount of heat dissipation per elapsed time.

[0044] Assume that at time t6, a short circuit occurs due to, for example, deterioration of the electric wire 9. Then, at time t7, the estimated temperature of the electric wire 9 reaches the cutoff temperature A3 before the actual temperature, and the IPD 3 can cut off the current to the auxiliary device 5.

[0045] When the control unit 1 performs the cutoff control at t7, the control unit 1 keeps the current below a predetermined value or stops the current for a predetermined time from t7 to t8, thereby lowering the temperature of the electric wire to the base temperature.

[0046] At time t9, the IPD 3 is restored, and the control unit 1 can again receive the input signal of the switch ON of the SW input unit 6 and pass current to the auxiliary device 5, similar to time t1.

[0047] Next, Fig. 3 is a flowchart for explaining an example of control processing in the electric wire temperature estimation device 10 according to one embodiment of the present invention. As shown in Fig. 3, after the IG switch 7 is turned on and the vehicle power supply is started, the control unit 1 receives an input signal that is turned on by the user operating the SW input unit 6 (step S1).

[0048] Next, the control unit 1 acquires from the second control unit 2 the temperature of the electric wire 9 when the SW input unit 6 was turned OFF before being turned ON, and the elapsed time from OFF to ON (step S2).

[0049] The control unit 1 calculates the amount of heat radiation per unit time elapsed from the acquired OFF to ON state of the electric wire 9. The control unit 1 holds the amount of heat radiation per unit time elapsed according to the electric wire 9 (step S3).

[0050] The control unit 1 calculates the temperature of the electric wire 9 when the SW input unit 6 is ON from the temperature of the electric wire 9 when the SW input unit 6 is OFF and the amount of heat radiation per unit time elapsed from OFF to ON (step S4).

[0051] The control unit 1 determines whether the calculated temperature is less than a predetermined temperature (step S5). If it determines that the calculated temperature is less than the predetermined temperature (step S5: Yes), the process proceeds to step S6. On the other hand, if it determines that the calculated temperature is equal to or greater than the predetermined temperature (step S5: No), the process proceeds to step S7.

[0052] Here, the predetermined temperature is, for example, an intermediate temperature between the base temperature A0 and the reference temperature A2 shown in Fig. 2. For example, it is set to an initial temperature A1.

[0053] In step S5, if the control unit 1 determines that the calculated temperature is lower than the predetermined temperature, it sets the predetermined temperature as the initial temperature (step S6).

[0054] On the other hand, if the control unit 1 determines in step S5 that the calculated temperature is equal to or higher than the predetermined temperature, it determines whether the calculated temperature is lower than a second predetermined temperature (step S7). If it determines that the calculated temperature is lower than the second predetermined temperature (step S7: Yes), the process proceeds to step S8. On the other hand, if it determines that the calculated temperature is equal to or higher than the second predetermined temperature (step S7: No), the process proceeds to step S9.

[0055] If the control unit 1 determines in step S7 that the calculated temperature is lower than the second predetermined temperature, it sets the calculated temperature as the initial temperature (step S8).

[0056] On the other hand, if the control unit 1 determines in step S7 that the calculated temperature is equal to or higher than the second predetermined temperature, it keeps the current below a predetermined value or stops the current for a certain period of time (step S9).

[0057] Here, the second predetermined temperature is, for example, an intermediate temperature between the reference temperature A2 and the shut-off temperature A3 shown in FIG.

[0058] That is, in step S8, if the calculated temperature is higher than the base temperature A0 and close to the reference temperature A2, the accuracy of the subsequent estimated temperature can be improved by setting the calculated temperature as the initial temperature of the electric wire 9. Also, in step S9, if the temperature is close to the interruption temperature A3, the current is kept below a predetermined value or stopped until the temperature of the electric wire 9 drops.

[0059] By the processing up to this point, it has been possible to set the initial temperature of the electric wire 9 when the switch is turned on, or to lower the temperature of the electric wire 9 to the base temperature A0.

[0060] Next, the control unit 1 sends a current to the auxiliary device 5. At this time, the control unit 1 detects the value of the current flowing to the auxiliary device 5 and measures the time for which the current flows, thereby estimating the temperature of the electric wire 9 (step S10).

[0061] The control unit 1 determines whether the estimated temperature is equal to or higher than a third predetermined temperature (step S11). If it determines that the estimated temperature is equal to or higher than the third predetermined temperature (step S11: Yes), the process proceeds to step S12. On the other hand, if it determines that the estimated temperature is lower than the third predetermined temperature (step S11: No), the process returns to step S10 and the estimation of the temperature of the electric wire 9 is repeated.

[0062] In step S11, when the controller 1 determines that the estimated temperature is equal to or higher than the third predetermined temperature, the controller 1 causes the IPD 3 to cut off the current to the auxiliary device 5 (step S12).

[0063] Here, the third predetermined temperature is, for example, the cutoff temperature A3 shown in Fig. 2. This allows the IPD3 to suppress overcurrent.

[0064] Although the explanation has been given in steps 1 to 12 by taking the example of starting and stopping by turning the switch on and off of the SW input unit 6, the starting and stopping of the vehicle power supply may be achieved by turning the IG switch 7 on and off.

[0065] Fig. 4 is a block diagram showing an example of the configuration of a vehicle to which an electric wire temperature estimation device according to a second embodiment of the present invention is applied. As shown in Fig. 4, the electric wire temperature estimation device 10 may further include a temperature detection unit 8. The temperature detection unit 8 is provided, for example, in a position where it can detect the temperature inside the hood of the vehicle. It detects the temperature inside the hood and outputs the detected temperature to the control unit 1. The temperature detection unit 8 is, for example, a transistor or a thermistor. The other configuration is the same as that of the embodiment shown in Fig. 1, so a description thereof will be omitted.

[0066] Furthermore, if the electric wire temperature estimation device 10 includes a temperature detection unit 8 that detects the temperature inside the vehicle, the control unit 1 may set the detected temperature as the initial temperature if the calculated temperature is lower than a predetermined temperature. This allows the initial temperature of the electric wire to be set to the ambient temperature detected by the temperature detection unit, thereby improving the accuracy of the temperature estimation of the electric wire after startup.

[0067] <Effects of this embodiment> As described above, the electric wire temperature estimation device according to this embodiment includes, for example, a control unit that estimates the electric wire temperature based on the current value after the vehicle power supply is started. The control unit acquires the electric wire temperature when the vehicle power supply is stopped and the elapsed time from when the vehicle power supply is stopped to when it is started, calculates the electric wire temperature when the vehicle power supply is started based on the electric wire temperature when the vehicle power supply is stopped and the amount of heat dissipation from the electric wire calculated using the elapsed time, sets the calculated temperature to an initial temperature, and estimates the electric wire temperature after the vehicle power supply is started based on the initial temperature.

[0068] Therefore, by calculating the temperature of the electric wire at startup based on the temperature of the electric wire when the power supply is shut off and the elapsed time from shutdown to startup, the accuracy of estimating the temperature of the electric wire after startup can be improved. In addition, since temperature estimation can be performed without using a temperature sensor or the like, the accuracy of temperature estimation can be improved without increasing costs. As a result, for example, the interruption temperature can be estimated with high accuracy.

[0069] In addition, the electric wire temperature estimation device according to this embodiment further includes, for example, a temperature detection unit that detects the temperature inside the vehicle, and the control unit sets the detected temperature as the initial temperature when the calculated temperature is lower than a predetermined temperature.

[0070] Therefore, since the initial temperature of the electric wire can be set to the ambient temperature detected by the temperature detection unit, the accuracy of estimating the temperature of the electric wire after startup can be improved.

[0071] In addition, in the electric wire temperature estimation device according to the present embodiment, for example, when the calculated temperature is lower than the predetermined temperature, the control unit sets the predetermined temperature as the initial temperature.

[0072] Therefore, even if the calculated temperature is lower than the predetermined temperature, the overcurrent can be suppressed by setting the initial temperature to the predetermined temperature.

[0073] The heat dissipation amount of the electric wire in the electric wire temperature estimation device according to the present embodiment is set, for example, according to the characteristics of the electric wire.

[0074] Therefore, it is possible to calculate an appropriate amount of heat radiation per elapsed time depending on the electric wire, thereby improving the accuracy of estimating the temperature of the electric wire after startup.

[0075] Furthermore, for example, when the calculated temperature is equal to or higher than a second predetermined temperature, the control unit of the electric wire temperature estimation device according to this embodiment keeps the current flowing through the electric wire at or below a predetermined value until a predetermined time has elapsed or stops the current.

[0076] Therefore, when the temperature of the electric wire is equal to or higher than the second predetermined temperature, the temperature of the electric wire can be lowered by reducing the current to a predetermined value or lower or stopping the current for a predetermined time. As a result, for example, the IPD can cut off the current or reduce the current to a predetermined value or lower, thereby preventing the temperature of the electric wire from rising.

[0077] Although the present embodiment has been described as a control device applied to a series hybrid system, the present invention is not limited to this. For example, the present invention can be applied to a series-parallel hybrid system in which a vehicle is provided with a power split mechanism and both the engine and the motor are used as power sources, a mild hybrid system in which the motor is used as an auxiliary motor for the engine (for example, an ISG (Integrated Starter Generator)), and a parallel hybrid system.

[0078] Although the embodiments of the present invention have been described above, the above-described embodiments are presented as examples. This novel embodiment is not intended to limit the scope of the present invention. The present invention can be embodied in various other forms without departing from the spirit of the invention. Various omissions, substitutions, and modifications can be made within the scope of the present invention. The scope of the invention and its equivalents as defined in the claims are included in the scope and spirit of the invention. Included in. [Explanation of symbols]

[0079] 1: Control section 2: Second control section 3:IPD 4: Power supply 5: Auxiliary 6: SW input section 7:IG switch 8: Temperature detection unit 9:Electric wire 10:Wire temperature estimation device

Claims

1. a control unit that estimates a temperature of the electric wire based on a current value of a vehicle power supply; The control unit The temperature of the electric wire when the vehicle power supply is stopped and the elapsed time from the stop of the vehicle power supply to the start of the vehicle power supply are acquired; calculating a temperature of the electric wire when the vehicle power supply is started based on the temperature of the electric wire when the vehicle power supply is stopped and an amount of heat radiation of the electric wire calculated using the elapsed time; The calculated temperature is set as the initial temperature. estimating a temperature of the electric wire after activation of the vehicle power supply based on the initial temperature; Wire temperature estimation device.

2. When the calculated temperature is lower than a predetermined temperature, the control unit sets the predetermined temperature as the initial temperature. The electric wire temperature estimation device according to claim 1 .

3. The heat dissipation amount is set according to the characteristics of the electric wire. The electric wire temperature estimation device according to claim 1 .

4. When the calculated temperature is equal to or higher than a second predetermined temperature, the control unit keeps the current flowing through the electric wire at or below a predetermined value until a predetermined time has elapsed or stops the current. The electric wire temperature estimation device according to claim 1 .

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