Vehicle control device

Abstract

To protect a load circuit and an electric wire by cutting off a current when an overcurrent is generated while suppressing the erroneous cutoff of the current in a control device for a vehicle for controlling the energization of the current to the load circuit.SOLUTION: The vehicular control apparatus 1 includes the semi-conductor switch, the electric wires 6a and 6b connecting the load circuit 4 and the semi-conductor switch, and the control unit 3b controlling ON and OFF of the semi-conductor switch, wherein the control unit 3b prohibits energization to the load circuit 4 on condition that a duration of a state in which the estimated wire temperatures of the electric wires 6a and 6b exceed the first threshold temperature T3 exceeds a predetermined value, and a predetermined range of the estimated wire temperatures is set as the preliminary determination ranges A and B in which energization can be prohibited by the control unit 3b. The control unit 3b prohibits the energization of the load circuit 4 on condition that the duration of the state in which the wire estimated temperature is in the preliminary determination ranges A and B exceeds a specific value, and the specific value is set to a value larger than a predetermined value.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device that includes a control unit that controls the on / off of a semiconductor switch connected to a predetermined load circuit. [Background technology]

[0002] Conventionally, a semiconductor switch is provided between a load such as a motor mounted on a vehicle and a power source, and the semiconductor switch functions as a fuse. For example, a protection device described in Patent Document 1 estimates the temperature of the electric wire connecting the power source and the load by detecting the current flowing through the load. Here, the protection device determines that an overcurrent has occurred when the estimated temperature of the electric wire reaches an allowable temperature, and cuts off the current flowing through the load using the semiconductor switch. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-37940 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the protection device described in Patent Document 1 always cuts off the current flowing through the load when the estimated wire temperature exceeds the allowable temperature. Therefore, for example, even if noise enters the current flowing through the load and causes the estimated wire temperature to exceed the allowable temperature, the current is still cut off. In other words, the protection device described in Patent Document 1 may erroneously cut off the current even when the actual wire temperature has not reached the allowable temperature.

[0005] One possible measure to prevent such erroneous tripping is to cut off the current flowing through the load when the estimated temperature of the electric wire exceeds the allowable temperature for a predetermined period of time. However, if this is done, it is expected that the current cutoff will be delayed when an overcurrent occurs, which is accompanied by a sudden increase in current, and the current will not be cut off at the appropriate time.

[0006] Therefore, the present invention aims to provide a vehicle control device that controls the flow of current to a load circuit by controlling the on and off of a semiconductor switch connected to a specified load circuit, and that can prevent the accidental interruption of the current flowing through the load circuit, while interrupting the current when an overcurrent occurs to protect the load circuit and electrical wires. [Means for solving the problem]

[0007] (1) The vehicle control device of the present invention, which is provided to solve the above-mentioned problems, is a vehicle control device comprising: a semiconductor switch capable of controlling the supply of current to a predetermined load circuit; an electric wire connecting the predetermined load circuit and the semiconductor switch; and a control unit that controls the semiconductor switch on and off, wherein the control unit controls the semiconductor switch to turn off to prohibit the supply of current to the predetermined load circuit when a heat generation index indicating the amount of heat generated by the electric wire exceeds a first threshold value and an index indicating the duration of the state exceeds a predetermined value; the predetermined range of the heat generation index is set as a preliminary judgment range in which the semiconductor switch can be controlled to turn off by the control unit, and the upper limit of the preliminary judgment range is set to be equal to or less than the first threshold value; and the control unit controls the semiconductor switch to turn off to prohibit the supply of current to the predetermined load circuit when the heat generation index is in the preliminary judgment range and the index indicating the duration of the state exceeds a specific value, and the specific value is set to a value greater than the predetermined value.

[0008] The vehicle control device of the present invention may prohibit the supply of current to the load circuit in two states: a state in which the heat generation index exceeds a first threshold (first state) and a state in which the heat generation index is in a preliminary determination range whose upper limit is set to be equal to or less than the first threshold (second state). Here, the index for prohibiting the supply of current to the load circuit (an index indicating the duration of the state) is set to a higher value when the heat generation index is in the preliminary determination range than when the heat generation index exceeds the first threshold. That is, when the heat generation index is in the preliminary determination range, the vehicle control device of the present invention prohibits the supply of current to the load circuit at a later timing than when the heat generation index exceeds the first threshold. By doing so, the vehicle control device of the present invention can prevent erroneous cut-off of power to the load circuit due to noise or the like entering the current flowing through the load when the heat generation index is in the preliminary determination range. On the other hand, when the heat generation index exceeds the first threshold, which is higher than the preliminary determination range, the vehicle control device of the present invention prohibits the supply of current to the load circuit at an earlier timing than when the heat generation index is in the preliminary determination range. By doing so, the vehicle control device of the present invention can protect the load circuit and electric wires by cutting off the current, for example, even when an overcurrent accompanied by a sudden increase in current occurs.

[0009] (2) The indicator indicating the duration of the state in which the fever index exceeds the first threshold value and the indicator indicating the duration of the state in which the fever index is within the preliminary judgment range are each time, and the specific value may be set to a value longer than the predetermined value.

[0010] By doing this, the vehicle control device of the present invention can determine whether to prohibit the flow of electricity to the load circuit based on the duration of the state in which the heat generation index exceeds the first threshold value and remains within the preliminary judgment range.

[0011] (3) Preferably, a plurality of the preliminary determination ranges are set, and the specific value is set to a larger value as the preliminary determination range has a smaller heat index.

[0012] In this way, the vehicle control device of the present invention can improve the responsiveness (responsiveness to prohibition of power supply) when an overcurrent occurs as the heat generation index approaches the first threshold value in the preliminary determination range. Also, the vehicle control device of the present invention can improve the function of suppressing erroneous power supply cutoff to the load circuit due to noise as the heat generation index approaches the first threshold value in the preliminary determination range.

[0013] (4) After controlling the semiconductor switch to be off, the control unit releases the off control on the condition that the heat generation index falls below a second threshold value, and the second threshold value may be set to a value smaller than the lower limit value of the preliminary judgment range in which the heat generation index is smallest.

[0014] In this way, the vehicle control device of the present invention can prevent current supply to the load circuit from being prohibited again immediately after the prohibition on current supply has been lifted.

[0015] (5) The vehicle control device of the present invention includes an electric wire temperature estimation unit that estimates the temperature of the electric wire, The heat generation index may be an estimated electric wire temperature estimated by the electric wire temperature estimation unit.

[0016] In this way, the vehicle control device of the present invention can control the on / off of the semiconductor switch based on the estimated electric wire temperature estimated by the electric wire temperature estimating section.

[0017] (6) The vehicle control device of the present invention includes an electric wire temperature estimation unit that estimates the temperature of the electric wire, and the electric wire temperature estimation unit estimates the temperature of the electric wire at each predetermined estimation period. The index indicating the duration of the state in which the heat generation index exceeds the first threshold value and the index indicating the duration of the state in which the heat generation index is within the preliminary judgment range may each be the number of the estimation period.

[0018] In this way, the vehicle control device of the present invention can control the on / off of the semiconductor switch based on the estimated wire temperature estimated by the wire temperature estimator. Furthermore, since the vehicle control device of the present invention uses the number of estimation cycles of the estimated wire temperature as an index indicating the duration, the duration can be easily counted.

[0019] (7) At least one of the predetermined value and the specific value may be set depending on the type of the electric wire.

[0020] In this way, the vehicle control device of the present invention can prohibit the supply of electricity to the load circuit at an appropriate timing according to the type of electric wire.

[0021] (8) After controlling the semiconductor switch to be turned off, the control unit releases the off control on the condition that the heat generation index falls below a second threshold value, and the second threshold value may be set according to the degree of change in the heat generation index when the semiconductor switch is controlled to be turned off.

[0022] In this way, the vehicle control device of the present invention can be configured, for example, to set the second threshold value smaller as the degree of change in the heat generation index when current supply to the load circuit is prohibited. With this configuration, for example, in the case of an overcurrent in which the current increases rapidly, the prohibition on current supply can be lifted when the heat generation index has decreased. This allows the vehicle control device of the present invention to reduce the possibility that the heat generation index will again increase to the first threshold value after the prohibition on current supply is lifted. Furthermore, with this configuration, for example, the second threshold value is set higher as the degree of change in the heat generation index when current supply to the load circuit is prohibited. Therefore, the vehicle control device of the present invention can speed up recovery from the state in which current supply is prohibited in the case of an overcurrent in which the current increases gradually. [Effects of the Invention]

[0023] According to the present invention, a vehicle control device that controls the flow of current to a load circuit by controlling the on / off of a semiconductor switch connected to a specified load circuit can be realized, which can prevent the accidental interruption of the current flowing through the load circuit while interrupting the current when an overcurrent occurs, thereby protecting the load circuit and electrical wires. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a block diagram of a vehicle control device according to an embodiment of the present invention; [Figure 2] 10 is a diagram for explaining a determination region for determining whether or not to cut off power supply when an overcurrent occurs in a load circuit. FIG. [Figure 3] 4 is a flowchart showing the flow of a current interruption process according to the present embodiment. [Figure 4] 4 is a flowchart showing the flow of a current interruption cancellation process according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, a vehicle control device 1 according to one embodiment of the present invention will be described in detail with reference to the drawings.

[0026] A vehicle control device 1 of this embodiment controls the supply of electricity to a load circuit 4 mounted on a vehicle. As shown in Fig. 1, the vehicle control device 1 includes an IPD (Intelligent Power Device) 2 having a semiconductor switch capable of controlling the supply of electricity to the load circuit 4, a microcomputer 3 that controls the on / off of the semiconductor switch of the IPD 2, an electric wire 6a that connects the IPD 2 to the load circuit 4, and an electric wire 6b that connects the IPD 2 to a battery 5. The load circuit 4 may be, for example, various devices mounted on the vehicle, such as an air conditioner, various lamps, a de-icer, etc.

[0027] The load circuit 4 is connected to the battery 5 via electric wires 6a and 6b. Therefore, the load circuit 4 is supplied with power from the battery 5.

[0028] The IPD 2 includes a semiconductor switch capable of switching between energizing and de-energizing the connected load circuit 4, a protection circuit, and a current sensor. The semiconductor switch switches between energizing and de-energizing the connected load circuit 4 upon receiving a control signal from the control unit 4b (described later). The current sensor detects the value of the current (current value) supplied to the load circuit and outputs information related to the current value to the control unit 3b. The protection circuit is a circuit that performs self-protection when an overcurrent occurs in the IPD 2 or when external noise is superimposed on the current. In other words, when an overcurrent or other problem occurs, the protection circuit automatically stops the supply of current to the load circuit 4 without waiting for a control signal from the control unit 3b. The semiconductor switch may be, for example, a field-effect transistor (FET).

[0029] The microcomputer 3 controls the supply of current to the load circuit 4 and performs various calculations related to this control. The microcomputer 3 includes a wire temperature estimation unit 3a, a control unit 3b, and a storage unit 3c. The microcomputer 3 is connected to a battery 5 via an ignition switch 7 and receives power from the battery 5.

[0030] The wire temperature estimator 3a estimates the temperatures of the wires 6a, 6b based on the value of the current supplied to the load circuit 4 output from the IPD 2, etc. As a method for estimating the temperatures of the wires 6a, 6b by the wire temperature estimator 3a, for example, conventional techniques described in Japanese Patent Nos. 5390837, 5768176, 6322536, 6128055, and 6790350 can be used. Note that in this embodiment, the wire temperature estimator 3a estimates the temperatures of the wires 6a, 6b at a predetermined cycle (for example, every 16 ms).

[0031] The control unit 3b controls the on / off of the semiconductor switch of the IPD 2 based on the temperature of the electric wires 6a, 6b estimated by the electric wire temperature estimation unit 3a (estimated electric wire temperature). The control unit 3b controls the on / off of the semiconductor switch, thereby controlling the supply of electricity to the load circuit 4.

[0032] The above is the configuration of the vehicle control device 1 according to one embodiment of the present invention. Next, the control of the power supply to the load circuit 4 performed by the control unit 3b will be described in detail.

[0033] (Control of current flow to load circuit) As shown in FIG. 2, in this embodiment, the estimated wire temperature estimated by the wire temperature estimator 3a is divided into three judgment regions (normal judgment region, preliminary judgment region A, and preliminary judgment region B). The normal judgment region is a temperature region higher than the first threshold temperature T3. The first threshold temperature T3 is a preset temperature lower than the upper limit temperature Td set for the wires 6a and 6b. The preliminary judgment region B is a temperature region in which the upper limit is the first threshold temperature T3 and the lower limit is the second threshold temperature T2. The second threshold temperature T2 is a preset temperature lower than the first threshold temperature T3. The preliminary judgment region A is a temperature region in which the upper limit is the second threshold temperature T2 and the lower limit is the third threshold temperature T1. The third threshold temperature T1 is a preset temperature lower than the second threshold temperature T2. The upper limit temperature Td is determined in consideration of the durability of the load circuit 4 and the wires 6a and 6b.

[0034] In this embodiment, the control unit 3b changes the control mode when cutting off the current supplied to the load circuit 4 in each of the normal judgment region, the preliminary judgment region A, and the preliminary judgment region B.

[0035] For example, the control unit 3b transmits a control signal (a signal requesting current interruption) to the IPD 2 on the condition that the estimated electric wire temperature calculated by the electric wire temperature estimator 3a remains in the normal judgment region for a predetermined period of time. When the IPD 2 receives the signal, it turns off the semiconductor switch. This interrupts the current to the load circuit 4.

[0036] In this embodiment, the duration (predetermined time) that constitutes a condition for cutting off the current to the load circuit 4 is determined by the calculation period (estimation period) of the estimated wire temperature calculated by the wire temperature estimator 3a. Specifically, in this embodiment, the controller 3b transmits a control signal to the IPD 2 on the condition that the estimated wire temperature remains in the normal judgment region for one period.

[0037] The determination of whether the state in which the estimated wire temperature remains in the normal determination region has continued for one cycle can be performed, for example, as follows. For example, the control unit 3b performs a process of incrementing the count value of the first cycle counter 3c1 (FIG. 1) by 1 or clearing it to 0 for each calculation cycle of the wire temperature estimator 3a. Specifically, if the estimated wire temperature calculated by the wire temperature estimator 3a in the calculation cycle is equal to or higher than the first threshold temperature T3, the control unit 3b increments the count value of the first cycle counter 3c1 by 1. On the other hand, if the estimated wire temperature calculated by the wire temperature estimator 3a is lower than the first threshold temperature T3, the control unit 3b clears the count value of the first cycle counter 3c1 to 0.

[0038] Furthermore, when the estimated wire temperature calculated by the wire temperature estimator 3a is equal to or higher than the first threshold temperature T3, the controller 3b checks the count value of the counter 3c1. If the checked count value of the first cycle counter 3c1 is 1, the controller 3b can determine that the estimated wire temperature has remained in the normal determination region for one cycle.

[0039] Furthermore, the control unit 3b transmits a control signal (a signal requesting current interruption) to the IPD 2 on the condition that the estimated electric wire temperature estimated by the electric wire temperature estimator 3a remains in the preliminary determination region B for a first specific time. When the IPD 2 receives the signal, it turns off the semiconductor switch. This interrupts the current to the load circuit 4.

[0040] The duration (first specific time) that is the condition for cutting off the current to the load circuit 4 is also determined by the calculation period of the electric wire temperature estimation unit 3a, similar to the above-mentioned predetermined time, and in this embodiment is set to three periods.

[0041] In addition, the determination of whether the state in which the estimated wire temperature is in the preliminary judgment region B has continued for three consecutive periods can also be performed using the second period counter 3c2 (FIG. 1) in the same manner as in the case of the normal judgment region. That is, for each calculation period of the wire temperature estimator 3a, if the calculated estimated wire temperature is within the range of the preliminary judgment region B, the controller 3b increments the count value of the second period counter 3c2 by 1, and if the calculated estimated wire temperature is outside the range, the controller 3b clears the count value of the second period counter 3c2 to 0. By checking the second period counter 3c2 that has been incremented and cleared in this manner, the controller 3b can determine whether the state in which the estimated wire temperature is in the preliminary judgment region B has continued for three consecutive periods.

[0042] Furthermore, the control unit 3b transmits a control signal (a signal requesting current interruption) to the IPD 2 on the condition that the estimated electric wire temperature estimated by the electric wire temperature estimator 3a remains in the preliminary determination region A for a second specific time. When the IPD 2 receives the signal, it turns off the semiconductor switch. This interrupts the current to the load circuit 4.

[0043] The duration (second specific time) that constitutes the condition for cutting off the current to the load circuit 4 is also determined by the calculation period of the electric wire temperature estimation unit 3a, similar to the above-mentioned predetermined time, and in this embodiment is set to five periods.

[0044] In addition, the determination of whether the state in which the estimated electric wire temperature is in the preliminary determination region B has continued for five periods can be made using the third period counter 3c3 (FIG. 1) in the same manner as the determination in the normal determination region described above.

[0045] As described above, the durations that are the conditions for cutting off the current to the load circuit 4 are set to become shorter in the normal determination region (1 cycle), preliminary determination region B (3 cycles), and preliminary determination region A (5 cycles) in that order. That is, in this embodiment, the current to the load circuit 4 is more likely to be cut off in the normal determination region, preliminary determination region B, and preliminary determination region A in that order.

[0046] The first period counter 3c1, the second period counter 3c2, and the third period counter 3c3 can be set in a predetermined storage area of ​​the storage unit 3c.

[0047] After performing control to cut off the current to the load circuit 4, the control unit 3b transmits a control signal to the IPD 2 to cancel the cutoff control when a predetermined cancellation condition is met. Upon receiving the control signal, the IPD 2 cancels the OFF state of the semiconductor switch. In this embodiment, the predetermined cancellation conditions are set as follows: (i) the estimated wire temperature calculated by the wire temperature estimator 3a drops to the cutoff cancellation temperature Tc, and (ii) a switch of a device constituting the load circuit 4 is turned off.

[0048] Next, a series of steps for interrupting and releasing the current to the load circuit 4 will be described with reference to Fig. 2. Fig. 2 shows an example of the process from when an overcurrent flows in the load circuit 4, causing the control unit 3b to interrupt the current to the load circuit 4, until the interruption is released.

[0049] When the devices constituting the load circuit 4 are turned on, a rated current flows through the load circuit 4. At this time, the estimated temperatures of the electric wires 6a and 6b rise, but after a certain amount of time has passed, the rate of rise slows and the temperature stabilizes. FIG. 2 shows a case in which the estimated temperatures of the electric wires 6a and 6b are lower than the third threshold temperature T1 when the estimated temperatures of the electric wires 6a and 6b are stable. When an overcurrent occurs while the estimated temperatures of the electric wires are stable, the estimated temperatures of the electric wires 6a and 6b rise rapidly.

[0050] 2 shows a case where the estimated temperatures of the electric wires 6a and 6b rise to the normal judgment region before the duration that is the condition for cutting off the current in the preliminary judgment regions A and B has elapsed. When the duration of the estimated electric wire temperature in the normal judgment region reaches a predetermined time (one cycle), the control unit 3b transmits a control signal to the IPD 2 to cut off the current to the load circuit 4, and the current to the load circuit 4 is thereby cut off.

[0051] When the current to the load circuit 4 is interrupted, the estimated wire temperature decreases. If the above-mentioned predetermined cancellation condition is met, including the estimated wire temperature decreasing to the interruption cancellation temperature Tc as a result of the current to the load circuit 4 being continuously interrupted, the control unit 3b cancels the interruption of the current to the load circuit 4.

[0052] If the device constituting the load circuit 4 is turned on after the current interruption is released, current is supplied to the load circuit 4, and the estimated wire temperature rises accordingly. If the overcurrent that caused the current interruption has been resolved, the rated current flows through the load circuit 4, and the estimated wire temperature stabilizes at a temperature lower than the third threshold temperature T1.

[0053] (Current interruption processing) The above is the explanation of Fig. 2. Next, an example of the process (current interruption process) of interrupting the current to the load circuit 4 (electric wires 6a, 6b) executed by the control unit 3b will be explained with reference to Fig. 3. Fig. 3 is a flowchart showing an example of the current interruption process of this embodiment.

[0054] In step S1, the control unit 3b determines whether the estimated electric wire temperature calculated by the electric wire temperature estimator 3a is within the range of the preliminary determination region A (third threshold temperature T1≦estimated electric wire temperature<second threshold temperature T2). If it is determined that the estimated electric wire temperature is within the preliminary determination region A, the control unit 3b executes preliminary determination region A shutoff processing (step S2) and ends the processing.

[0055] The preliminary determination region A cutoff process includes the above-mentioned processes (I) to (III): (I) a process of incrementing third period counter 3c3 by 1, (II) a process of determining whether or not the count value of third period counter 3c3 has reached 5 (5 periods), and (III) a process of sending a control signal to IPD2 to set the semiconductor switch to OFF in order to cut off the current to load circuit 4 when the count value of third period counter 3c3 has reached 5. By these processes, the current to load circuit 4 is cut off when the state in which the estimated electric wire temperature remains in preliminary determination region A continues for a second specific time.

[0056] If it is determined in step S1 that the estimated electric wire temperature is not in the preliminary judgment region A, the control unit 3b determines whether the estimated electric wire temperature calculated by the electric wire temperature estimator 3a is within the range of the preliminary judgment region B (second threshold temperature T2≦estimated electric wire temperature<first threshold temperature T3) (step S3). If it is determined that the estimated electric wire temperature is in the preliminary judgment region B, the control unit 3b executes a preliminary judgment region B shutoff process (step S4) and ends the process.

[0057] The preliminary determination region B cutoff process includes processes equivalent to the processes (I) to (III) included in the preliminary determination region A process. By these processes, if the state in which the estimated electric wire temperature remains in the preliminary determination region B continues for a first specific time, the current to the load circuit 4 is cut off.

[0058] If it is determined in step S3 that the estimated electric wire temperature is not in the preliminary determination region B, the control unit 3b determines whether the estimated electric wire temperature calculated by the electric wire temperature estimator 3a is within the range of the normal determination region (first threshold temperature T3≦estimated electric wire temperature) (step S5).If it is determined that the estimated electric wire temperature is within the normal determination region, the control unit 3b executes normal determination region cutoff processing (step S6) and ends the processing.

[0059] The normal judgment region cutoff process includes processes equivalent to the processes (I) to (III) included in the preliminary judgment region A process. By these processes, if the estimated electric wire temperature remains in the normal judgment region for a predetermined time, the current to the load circuit 4 is cut off.

[0060] (Current cut-off release process) Next, an example of a process (current cut-off cancel process) for canceling the cut-off of the current to the load circuit 4 (electric wires 6a, 6b) executed by the control unit 3b will be described with reference to Fig. 4. Fig. 4 is a flowchart showing an example of the current cut-off cancel process of this embodiment.

[0061] In step S10, the control unit 3b determines whether or not predetermined cancellation conditions are met. As described above, the predetermined cancellation conditions include (i) the estimated wire temperature calculated by the wire temperature estimator 3a decreasing to the interruption cancellation temperature Tc, and (ii) the switch of a device constituting the load circuit 4 being turned off.

[0062] If it is determined that the predetermined cancellation condition is met (YES in step S10), the control unit 3b cancels the cut-off control of the current to the load circuit 4 (step S11) and ends the process. On the other hand, if it is determined that the predetermined cancellation condition is not met (NO in step S10), the control unit 3bf continues the cut-off control of the current and ends the process.

[0063] (Action and effect) The above is one embodiment of the vehicle control device 1 of the present invention. Next, the effects achieved by the vehicle control device 1 of this embodiment will be described below.

[0064] The above-described vehicle control device 1 has the following characteristic configuration: Therefore, the vehicle control device 1 can achieve the following unique effects that cannot be achieved by conventional techniques.

[0065] (a) A vehicle control device 1 of the present invention is a vehicle control device including a semiconductor switch capable of controlling the supply of electricity to a predetermined load circuit 4, an electric wire connecting the predetermined load circuit 4 and the semiconductor switch, and a control unit 3b that controls the on / off of the semiconductor switch, wherein the control unit 3b controls the semiconductor switch to turn off to prohibit the supply of electricity to the predetermined load circuit 4 on condition that, in a state where a heat generation index (electric wire estimated temperature) indicating the amount of heat generated in the electric wires 6a, 6b exceeds a first threshold (first threshold temperature T3), an index (number of calculation cycles) indicating the duration of the state exceeds a predetermined value (one cycle), and the predetermined range of the heat generation index (electric wire estimated temperature) is a preliminary determination range (preliminary determination area A, The preliminary judgment range (preliminary judgment range A, preliminary judgment range B) has upper limit values ​​(first threshold temperature T3, second threshold temperature T2) set to be equal to or lower than the first threshold (first threshold temperature T3), and the control unit 3 b controls the semiconductor switch to turn off to prohibit the passage of current to the predetermined load circuit 4 when the heat generation index (estimated electric wire temperature) is in the preliminary judgment range (preliminary judgment range A, preliminary judgment range B) and an index (number of calculation cycles) indicating the duration of the state exceeds a specific value (3 cycles (preliminary judgment range B), 5 cycles (preliminary judgment range A)), and the specific value (3 cycles (preliminary judgment range B), 5 cycles (preliminary judgment range A)) is set to a value greater than the predetermined value (1 cycle).

[0066] The vehicle control device 1 of the present invention configured as described above can prohibit the supply of current to the load circuit 4 in three states: a state (first state) in which the heat generation index (estimated electric wire temperature) exceeds a first threshold (first threshold temperature T3); and a state (second state) in which the heat generation index (estimated electric wire temperature) is in a preliminary judgment range (preliminary judgment region A, preliminary judgment region B) whose upper limit is set to be equal to or lower than the first threshold (first threshold temperature T3). Here, the index (number of calculation cycles) related to the prohibition of the supply of current to the load circuit 4 is set to a larger value when the heat generation index (estimated electric wire temperature) is in the preliminary judgment range (preliminary judgment region A, preliminary judgment region B) than when the heat generation index (estimated electric wire temperature) exceeds the first threshold (normal judgment region). In other words, when the heat generation index (estimated electric wire temperature) is in the preliminary judgment range (preliminary judgment region A, preliminary judgment region B), the vehicle control device 1 of the present invention prohibits the supply of current to the load circuit 4 at a later timing than when the heat generation index (estimated electric wire temperature) exceeds the first threshold (normal judgment region) (state). In this manner, the vehicle control device 1 of the present invention can suppress erroneous interruption of power supply to the load circuit 4 due to noise or the like entering the current flowing through the load circuit 4 or the like when the heat generation index (estimated electric wire temperature) is relatively low (preliminary judgment region A, preliminary judgment region B). On the other hand, when the heat generation index (estimated electric wire temperature) exceeds a first threshold value that is higher than the preliminary judgment range (preliminary judgment region A, preliminary judgment region B) (a state in the normal judgment region), the vehicle control device 1 of the present invention prohibits power supply to the load circuit 4 at an earlier timing than when the heat generation index (estimated electric wire temperature) is in the preliminary judgment range (preliminary judgment region A, preliminary judgment region B). In this manner, the vehicle control device 1 of the present invention can protect the load circuit and the electric wires by interrupting the current when, for example, an overcurrent accompanied by a sudden increase in current occurs.

[0067] In addition, in the past, to satisfy both the requirements of preventing the estimated wire temperature from rising to the upper limit of operating temperature and preventing erroneous current interruption even when noise is present in the load circuit 4 or the wires, it was necessary to ensure a wide margin between the threshold for interrupting the current (threshold of the estimated wire temperature) and the upper limit of operating temperature. This made it difficult to thin the wires 6a and 6b. However, the vehicle control device 1 of the present invention is configured to prohibit current flow to the load circuit 4 earlier when the heat generation index (estimated wire temperature) is in the normal judgment region than when it is in the preliminary judgment region A or B. This allows the vehicle control device 1 of the present invention to narrow the margin between the upper limit of operating temperature Td and the first threshold (first threshold temperature T3) compared to the conventional technology, thereby enabling the wires 6a and 6b connecting the load circuit 4 and the battery 5 to be thinned. Furthermore, by thinning the wires 6a and 6b, the vehicle control device 1 of the present invention can easily achieve weight and cost reduction.

[0068] Furthermore, the vehicle control device 1 of the present invention can improve the responsiveness of cutting off the current to the load circuit 4 in the normal judgment region, and can reliably cut off the current to the load circuit 4 before the temperature of the electric wires 6a, 6b reaches the upper usage temperature Td. As a result, the vehicle control device 1 of the present invention can reduce the replacement frequency and replacement cost of the electric wires 6a, 6b and the IPD 2.

[0069] (b) Preferably, a plurality of the preliminary judgment ranges (preliminary judgment area A, preliminary judgment area B) are set, and the specific value (number of calculation periods) is set to a larger value (preliminary judgment area A=5 periods, preliminary judgment area B=3 periods) for the preliminary judgment range (preliminary judgment area A, preliminary judgment area B) with a smaller heat generation index (estimated electric wire temperature).

[0070] In this way, the vehicle control device 1 of the present invention can improve the responsiveness (responsiveness in cutting off current) when an overcurrent occurs, as the heat generation index (estimated electric wire temperature) approaches the first threshold (first threshold temperature T3) in the preliminary determination range (preliminary determination area A, preliminary determination area B). Also, the vehicle control device 1 of the present invention can improve the function of suppressing erroneous cutting off of power to the load circuit 4 caused by noise, as the heat generation index (estimated electric wire temperature) approaches the first threshold (first threshold temperature T3) in the preliminary determination range (preliminary determination area A, preliminary determination area B).

[0071] (c) After controlling the semiconductor switch to OFF, the control unit 3b releases the OFF control on the condition that the heat generation index (estimated electric wire temperature) falls below a second threshold (unblocking temperature Tc), and the second threshold (unblocking temperature Tc) is preferably set to a value smaller than the lower limit value (third threshold temperature T1) of the preliminary judgment range (preliminary judgment area A) in which the heat generation index (estimated electric wire temperature) is smallest.

[0072] In this way, the vehicle control device 1 of the present invention can prevent the current supply to the load circuit 4 from being prohibited again immediately after the prohibition of current supply has been lifted.

[0073] (d) The vehicle control device 1 of the present invention may include an electric wire temperature estimation unit 3a that estimates the temperature of the electric wires 6a, 6b, and the heat generation index (estimated electric wire temperature) may be the estimated electric wire temperature estimated by the electric wire temperature estimation unit 3a.

[0074] In this way, the vehicle control device 1 of the present invention can control the on / off of the semiconductor switch based on the estimated electric wire temperature estimated by the electric wire temperature estimator 3a.

[0075] (e) The vehicle control device 1 of the present invention includes an electric wire temperature estimation unit 3a that estimates the temperature of the electric wires 6a, 6b. The electric wire temperature estimation unit 3a estimates the temperature of the electric wires 6a, 6b at each predetermined estimation period (calculation period). The index (number of calculation periods) indicating the duration of the state in which the heat generation index (estimated electric wire temperature) exceeds the first threshold (first threshold temperature T3) and the index (number of calculation periods) indicating the duration of the state in which the heat generation index (estimated electric wire temperature) is within the preliminary judgment range (preliminary judgment area A, preliminary judgment area) may each be the number of the estimation periods (calculation periods).

[0076] In this way, the vehicle control device 1 of the present invention can control the on / off of the semiconductor switch based on the estimated electric wire temperature estimated by the electric wire temperature estimator 3 a. Furthermore, the vehicle control device 1 of the present invention uses the number of estimation periods (calculation periods) of the estimated electric wire temperature as an index indicating the duration, so that the duration can be easily counted.

[0077] The above are the effects of the vehicle control device 1 according to the embodiment of the present invention, but the vehicle control device 1 of the present invention is not limited to the above embodiment and can be modified in various ways. That is, the above-described vehicle control device 1 merely illustrates one embodiment of the present invention, and the configuration can be appropriately changed, omitted, or added as long as it does not deviate from the spirit of the present invention. That is, the vehicle control device 1 can be one that does not include some or all of the configurations according to (a) to (e) above, one that includes other configurations, or one that realizes the configurations according to (a) to (e) above differently from those exemplified in the above embodiment, etc., as long as it does not deviate from the spirit of the present invention.

[0078] For example, in the above-described embodiment, the indicator indicating the duration of the state in which the heat generation indicator (estimated electric wire temperature) exceeds the first threshold (first threshold temperature T3) and the indicator indicating the duration of the state in which the heat generation indicator (estimated electric wire temperature) is in the preliminary judgment range (preliminary judgment region A, preliminary judgment region B) are the number of calculation cycles of the estimated electric wire temperature by the electric wire temperature estimator 3a. The indicator can be changed as appropriate as long as it is an indicator that can specify the duration. For example, the indicator may be the duration itself. In this case, the specified value (the duration corresponding to calculation cycle=5 (preliminary judgment region A) and calculation cycle=3 (preliminary judgment region B)) may be set to a value longer than the predetermined value (the duration corresponding to calculation cycle=1 (normal judgment region)).

[0079] In this way, the vehicle control device 1 of the present invention can determine whether or not to prohibit the supply of current to the load circuit 4 based on the duration of the state in which the heat generation index (estimated electric wire temperature) exceeds the first threshold (first threshold temperature T3) and is in the preliminary determination range (preliminary determination area A, preliminary determination area B). Note that if the index is the duration itself, this can be realized by setting timers (timers that count the duration) corresponding to each of the period counters 3c1 to 3c3 in the storage unit 3c instead of each of the period counters 3c1 to 3c3.

[0080] At least one of the predetermined value (calculation period = 1 period) and the specific value (calculation period = 3 periods (preliminary judgment region B), 5 periods (preliminary judgment region A)) that specifies the timing of cutting off the current to the load circuit 4 may be set according to the type of the electric wires 6a, 6b.

[0081] In this way, the vehicle control device 1 of the present invention can prohibit the supply of current to the load circuit 4 at an appropriate timing according to the type of the electric wires 6a, 6b. Here, examples of the type of the electric wires 6a, 6b include the material from which the electric wires 6a, 6b are made and the cross-sectional area of ​​the electric wires 6a, 6b in a direction intersecting with the length direction.

[0082] After controlling the semiconductor switch to OFF, the control unit 3b releases the OFF control on the condition that the heat generation index (estimated electric wire temperature) falls below a second threshold (unblocking temperature Tc), and the second threshold (unblocking temperature Tc) is preferably set according to the degree of change in the heat generation index (estimated electric wire temperature) when the semiconductor switch is controlled to OFF.

[0083] In this way, the vehicle control device 1 of the present invention can be configured to set the second threshold (shutdown release temperature Tc) lower, for example, as the degree of change in the heat generation index (estimated electric wire temperature) increases when power supply to the load circuit 4 is prohibited. With this configuration, for example, in the case of an overcurrent in which the current increases rapidly, the power supply prohibition can be released when the heat generation index (estimated electric wire temperature) has decreased. This reduces the possibility that the heat generation index (estimated electric wire temperature) will again increase to the first threshold (first threshold temperature T3) after the power supply prohibition is released. Furthermore, with this configuration, for example, the second threshold (shutdown release temperature Tc) is set higher, as the degree of change in the heat generation index (estimated electric wire temperature) decreases when power supply to the load circuit 4 is prohibited. Therefore, the vehicle control device 1 of the present invention can speed up recovery from the power supply prohibition state in the case of an overcurrent in which the current increases gradually.

[0084] In the above embodiment, the current estimated temperature is used as an example of an index for determining whether to interrupt the current to the load circuit 4. However, any index that can identify the heat generation amount of the electric wire can be used as the index. For example, the amount of power supplied to the load circuit 4 (current x voltage x time) can be used as the index. Alternatively, the value of the current supplied to the load circuit 4 can be used as the index.

[0085] Furthermore, the threshold temperatures (first to third threshold temperatures T1 to T3) that define the normal judgment region and the preliminary judgment regions A and B can be set appropriately depending on the type of the electric wires 6a and 6b and the type of the load circuit 4. Furthermore, the range of each judgment region can also be changed appropriately.

[0086] In the above embodiment, the case where there are two preliminary determination regions A and B has been described, but it is also possible to have three or more regions. In this way, the vehicle control device 1 of the present invention can perform more precise current cut-off control.

[0087] Furthermore, in the above-described embodiment, the predetermined release condition for releasing the interruption of the current to the load circuit 4 can be set as appropriate. For example, the predetermined release condition can include turning off the ignition switch 7. In this way, after the current to the load circuit 4 is interrupted, the vehicle control device 1 of the present invention can improve the protection function of the electric wires 6a, 6b and the load circuit 4 because the interruption state is not released unless the ignition switch 7 is turned off.

[0088] The threshold value (interrupt release temperature Tc) for canceling the interruption of the current to the load circuit 4 can be changed according to the type of the electric wires 6a and 6b. The interrupt release temperature Tc can also be changed as appropriate according to the location where the devices constituting the load circuit 4 are installed (for example, around the engine or inside or outside the vehicle cabin).

[0089] The above are embodiments and variations of the vehicle control device 1 according to the present invention, but the present invention is not limited to the above-described embodiments and variations, and it will be easily understood by those skilled in the art that other embodiments are possible within the scope of the claims based on the teachings and spirit of the present invention. [Industrial Applicability]

[0090] The present invention can be suitably used in all vehicle control devices that include a control unit that controls the on / off of a semiconductor switch connected to a predetermined load circuit. [Explanation of symbols]

[0091] 1: Vehicle control device 2: IPD (semiconductor switch) 3a: Wire temperature estimation section 3b: Control section 4:Load circuit 6a, 6b: Electric wire T3: First threshold temperature (first threshold) Tc: Shutdown release temperature (second threshold)

Claims

1. A vehicle control device including a semiconductor switch capable of controlling current flow to a predetermined load circuit, an electric wire connecting the predetermined load circuit and the semiconductor switch, and a control unit that controls on / off of the semiconductor switch, the control unit controls the semiconductor switch to turn off to prohibit current flow to the predetermined load circuit when, in a state where a heat generation index indicating the amount of heat generation of the electric wire exceeds a first threshold, an index indicating a duration of the state exceeds a predetermined value; a predetermined range of the heat generation index is set as a preliminary determination range in which the semiconductor switch can be controlled to be turned off by the control unit, the preliminary determination range has an upper limit set to be equal to or less than the first threshold value, the control unit controls the semiconductor switch to turn off to prohibit current flow to the predetermined load circuit when an index indicating a duration of the heat generation index in the preliminary determination range exceeds a specific value, while the heat generation index is within the preliminary determination range; The vehicle control device is characterized in that the specific value is set to a value greater than the predetermined value.

2. the indicator indicating the duration of the state in which the fever index exceeds the first threshold and the indicator indicating the duration of the state in which the fever index is in the preliminary judgment range are each time periods, The vehicle control device according to claim 1 , wherein the specific value is set to a value longer than the predetermined value.

3. A plurality of preliminary determination ranges are set, 3. The vehicle control device according to claim 1, wherein the specific value is set to a larger value as the heat generation index is smaller in the preliminary determination range.

4. the control unit, after controlling the semiconductor switch to be turned off, releases the control of turning off the semiconductor switch on condition that the heat index falls below a second threshold; The vehicle control device according to claim 3 , wherein the second threshold value is set to a value smaller than a lower limit value of the preliminary determination range, which is the smallest of the heat generation indexes.

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