Power distribution device

Abstract

To establish wire protection from an upstream side to a downstream side without requiring re-design of a wire protection function when adding or changing an on-vehicle device.SOLUTION: A first power supply distribution device 11 comprises a cutoff section 111 and a control section 113 which controls the cutoff section 111 on the basis of first cutoff characteristics. Second and third power supply distribution devices 12 and 13 comprise cutoff sections 121 and 131 and control sections 123 and 133 which control the cutoff sections 121 and 131 on the basis of second cutoff characteristics. The first cutoff characteristics and the second cutoff characteristics are initially set in such a manner that a cutoff time of the cutoff section 111 becomes longer than cutoff times of the cutoff sections 121 and 131. In a case where cutoff characteristics of the cutoff sections 121 and 131 are changed by changing or adding on-vehicle loads 2B and 2C and the cutoff time of the cutoff section 111 becomes shorter than the cutoff times of the cutoff sections 121 and 131, the control section 113 changes the first cutoff characteristics in such a manner that the cutoff time of the cutoff section 111 becomes longer than the cutoff times of the cutoff sections 121 and 131.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power distribution device. [Background technology]

[0002] There are known in-vehicle power distribution devices that have the function of distributing power from a power source to multiple in-vehicle devices and that address the issue of supporting the addition of new in-vehicle devices (see, for example, Patent Documents 1 and 2). The power distribution device described in Patent Document 1 sets conditions for the smoke-emission characteristics of upstream electric wires, the melting characteristics of upstream fuses, and the power control characteristics of downstream switches, and adjusts the power distribution to the in-vehicle devices according to priority when the total current flowing through the multiple in-vehicle devices approaches the power control characteristics of the downstream switches. Furthermore, the power distribution device described in Patent Document 2 provides an extension section including a fuse in a relay device to which a main power line is connected, and further relay devices are connected via this extension section. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-14748 [Patent Document 2] Japanese Patent Publication No. 2022-363 Summary of the Invention [Problem to be solved by the invention]

[0004] In the power distribution device described in Patent Document 1, the operation of an onboard device with a lower priority is simulated. Furthermore, in the power distribution device described in Patent Document 2, the expansion section in the relay device must be changed every time an onboard device is added or changed, which increases the burden on the design of the power protection function. Furthermore, in the power distribution device described in Patent Document 2, when multiple relay devices are connected in series and parallel, if an onboard device is added or changed downstream, the wire protection conditions will not be met not only in the downstream relay device but also in the upstream relay device. In this case, problems such as simultaneous tripping or erroneous tripping of an upstream switch or fuse and a downstream switch or fuse may occur.

[0005] In view of the above circumstances, an object of the present invention is to provide a power distribution device that can protect electric wires from the upstream side to the downstream side without requiring redesign of the electric wire protection function when changing or adding an on-board device. [Means for solving the problem]

[0006] A power distribution device of the present invention includes a first power distribution device that distributes power supplied from a power supply device, and a second power distribution device that distributes the power distributed by the first power distribution device to an in-vehicle device, wherein the first power distribution device includes a first cutoff unit that connects or cuts off a first electric wire that supplies power from the power supply device to the second power distribution device, and a first control unit that controls the first cutoff unit based on a first cutoff characteristic that indicates a relationship between a heat quantity of the first electric wire and a first cutoff time that is a time from when current starts to flow through the first electric wire until the first cutoff unit cuts off the first electric wire, and the second power distribution device connects or cuts off a second electric wire that supplies power from the first power distribution device to the in-vehicle device. and a second control unit that controls the second breaking unit based on a second breaking characteristic that indicates the relationship between the heat quantity of the second electric wire and a second breaking time, which is the time from when current starts to flow through the second electric wire until the second breaking unit breaks the current. The first breaking characteristic and the second breaking characteristic are initially set so that the first breaking time is longer than the second breaking time. When the on-board device is changed or added, the second breaking characteristic is changed and the first breaking time becomes shorter than the second breaking time, and the first control unit executes a first breaking characteristic change process that changes the first breaking characteristic so that the first breaking time becomes longer than the second breaking time. [Effects of the Invention]

[0007] According to the present invention, when an on-board device is changed or added, it is possible to achieve wire protection from the upstream side to the downstream side without requiring redesign of the wire protection function. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing a power distribution device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a graph showing the relationship between the time during which the electric current flows through the electric wire and the change in the amount of heat. [Figure 3] FIG. 3 is a logarithmic graph showing the relationship between the current flowing through the wire and the interruption time of the interrupter. [Figure 4]FIG. 4 is a flowchart for explaining a process for changing the interrupting characteristics of the upstream interrupter after a downstream in-vehicle load is changed or added. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described below in accordance with preferred embodiments. Note that the present invention is not limited to the embodiments described below, and the embodiments described below can be modified as appropriate without departing from the spirit of the present invention. In addition, in the embodiments described below, some components are omitted from illustration and description, but for the details of the omitted technologies, publicly known or well-known technologies are applied as appropriate within the scope of not causing any contradictions with the content described below.

[0010] 1 is a block diagram showing a power distribution device 10 according to one embodiment of the present invention. As shown in this figure, the power distribution device 10 includes a first power distribution device 11, a second power distribution device 12, and a third power distribution device 13. The power distribution device 10 distributes power supplied from an on-board power supply device 1 to a plurality of on-board devices (on-board loads 2A, 2B, 2B', 2C, sensors 3A, 3C, an ECU (Electronic Control Unit) 4, etc.).

[0011] The power supply device 1 is a storage battery such as a lithium-ion battery, a power converter such as a DC / DC converter, a generator such as an alternator, etc. The vehicle loads 2A, 2B, 2B', 2C are a motor, an air conditioner, a lighting device, etc. The sensors 3A and 3C are various vehicle sensors such as a camera, a LiDAR (Light detection and ranging), a millimeter-wave radar, an ultrasonic sensor, a GPS (Global Positioning System) sensor, an acceleration / gyro sensor, a wheel speed sensor, an air pressure sensor, etc. The ECU 4 is an electronic control device equipped with a microcomputer, a CAN (Control Area Network) transceiver, an AD converter, etc.

[0012] The first power distribution device 11 is connected to the power supply device 1 by an electric wire 14. Furthermore, the second power distribution device 12 is connected to the first power distribution device 11 by an electric wire 15. Furthermore, the third power distribution device 13 is connected to the first power distribution device 11 by an electric wire 16. In other words, the second power distribution device 12 and the third power distribution device 13 are connected to the power supply device 1 via the first power distribution device 11.

[0013] An on-vehicle load 2A is connected to the first power distribution device 11 by an electric wire 17A. A sensor 3A is also connected to the first power distribution device 11. An on-vehicle load 2B is also connected to the second power distribution device 12 by an electric wire 17B. An ECU 4 is also connected to the second power distribution device 12. An on-vehicle load 2C is also connected to the third power distribution device 13 by an electric wire 17C. A sensor 3C is also connected to the third power distribution device 13.

[0014] Here, after the vehicle is shipped, there may be cases where the on-board devices connected to the first to third power distribution devices 11 to 13 are changed or added, such as when the on-board load 2B connected to the second power distribution device 12 is changed to an on-board load 2B'. In this case, the characteristics of the wire protection functions provided in the first to third power distribution devices 11 to 13 are automatically changed. This point will be described in detail later.

[0015] The first power distribution device 11 includes a cutoff unit 111, a detection unit 112, and a control unit 113. The second power distribution device 12 includes a cutoff unit 121, a detection unit 122, and a control unit 123. The third power distribution device 13 includes a cutoff unit 131, a detection unit 132, and a control unit 133.

[0016] The interrupting units 111, 121, and 131 are relays such as semiconductor relays and mechanical relays. The interrupting unit 111 connects or disconnects the electric wire 14 and the electric wire 15, and also connects or disconnects the electric wire 14 and the electric wire 16. The interrupting unit 121 connects or disconnects the electric wire 15 and the electric wire 17B. The interrupting unit 131 connects or disconnects the electric wire 16 and the electric wire 17C.

[0017] Sensor 3A is connected to a contact point upstream of circuit breaker 111. Therefore, when circuit breaker 111 is in a circuit breaker state, power is supplied to sensor 3A from power supply device 1. Furthermore, ECU 4 is connected to a contact point upstream of circuit breaker 121. Therefore, when circuit breaker 121 is in a circuit breaker state and circuit breaker 111 is in a connected state, power is supplied to ECU 4 from power supply device 1. Furthermore, sensor 3C is connected to a contact point upstream of circuit breaker 131. Therefore, when circuit breaker 131 is in a circuit breaker state and circuit breaker 111 is in a connected state, power is supplied to sensor 3C from power supply device 1.

[0018] On the other hand, in-vehicle load 2A is connected to a contact downstream of circuit breaker 111 by electric wire 17A. Therefore, when circuit breaker 111 is in the interrupted state, power is not supplied from power supply device 1 to in-vehicle load 2A. In addition, in-vehicle load 2B is connected to a contact downstream of circuit breaker 121 by electric wire 17B. Therefore, when circuit breaker 121 is in the interrupted state, power is not supplied from power supply device 1 to in-vehicle load 2B, regardless of the state of circuit breaker 111. In addition, in-vehicle load 2C is connected to a contact downstream of circuit breaker 131 by electric wire 17C. Therefore, when circuit breaker 131 is in the interrupted state, power is not supplied from power supply device 1 to in-vehicle load 2C, regardless of the state of circuit breaker 111.

[0019] The detection unit 112 detects the voltage and current of the interrupter 111 and transmits the detected values ​​to the control unit 113. The detection unit 122 detects the voltage and current of the interrupter 121 and transmits the detected values ​​to the control unit 123. The detection unit 132 detects the voltage and current of the interrupter 131 and transmits the detected values ​​to the control unit 133.

[0020] The control unit 113 incorporates a timer that measures the time that the electric wires 15, 16 are energized, and a memory that stores information such as the interruption characteristics of the circuit breaker 111. The control unit 113 determines whether to connect or disconnect the circuit breaker 111 based on the time that the electric wires 15, 16 are energized as measured by the timer, the detection value of the detection unit 112, and the interruption characteristics of the circuit breaker 111 stored in the memory, and transmits a control signal to the circuit breaker 111. The control unit 113 can calculate the temperature (heat quantity) of the connected electric wires 15, 16 based on the information obtained by the detection unit 112.

[0021] The control unit 123 incorporates a timer that measures the time that electric current is applied to the electric wire 17B, and a memory that stores information such as the interruption characteristics of the circuit breaker 121. The control unit 123 determines whether to connect or disconnect the circuit breaker 121 based on the time that electric current is applied measured by the timer, the detection value of the detection unit 122, and the interruption characteristics of the circuit breaker 121 stored in the memory, and transmits a control signal to the circuit breaker 121. The control unit 123 can calculate the temperature (amount of heat) of the connected electric wire 17B based on the information obtained by the detection unit 122.

[0022] The control unit 133 incorporates a timer that measures the time that electric current is applied to the electric wire 17C, and a memory that stores information such as the interruption characteristics of the circuit breaker 131. The control unit 133 determines whether to connect or disconnect the circuit breaker 131 based on the time that electric current is applied measured by the timer, the detection value of the detection unit 132, and the interruption characteristics of the circuit breaker 131 stored in the memory, and transmits a control signal to the circuit breaker 131. The control unit 133 can calculate the temperature (amount of heat) of the connected electric wire 17C based on the information obtained by the detection unit 132.

[0023] Fig. 2 is a graph showing the relationship between the current flow time of the electric wire 15 etc. and the change in heat quantity. Fig. 3 is a logarithmic graph showing the relationship between the current flowing through the electric wires 15, 17B and the interruption time (the time from the start of current flow to the interruption) of the interrupting units 111, 121. The vertical axis of this graph is a logarithmic scale.

[0024] As shown by the dashed-dotted line and the two-dotted line in the graph of Fig. 2, the interruption characteristics of interrupter 111 are defined by a curve showing the relationship between the amount of heat of electric wire 15 and the interruption time of interrupter 111. Furthermore, as shown by the solid line and the dashed line in the graph of Fig. 2, the interruption characteristics of interrupter 121 are defined by a curve showing the relationship between the amount of heat of electric wires 17B, 17B' and the interruption time of interrupter 121. Furthermore, although not shown in the graph of Fig. 2, the interruption characteristics of interrupter 131 are defined by a curve showing the relationship between the amount of heat of electric wire 17C and the interruption time of interrupter 131.

[0025] The control unit 113 of the first power distribution device 11 reads out the interruption time (threshold) corresponding to the temperature (amount of heat) of the electric wires 15 and 16 calculated from the detection value of the current flowing by the detection unit 112 from the interruption characteristics of the interrupter 111, and when the current flow time measured by the timer exceeds the threshold, determines to interrupt the interrupter 111 and transmits a disconnection signal to the interrupter 111. Furthermore, the control unit 123 of the second power distribution device 12 reads out the interruption time (threshold) corresponding to the temperature (amount of heat) of the electric wire 17B calculated from the detection value of the current flowing by the detection unit 122 from the interruption characteristics of the interrupter 121, and when the current flow time measured by the timer exceeds the threshold, determines to interrupt the interrupter 121 and transmits a disconnection signal to the interrupter 121. Furthermore, the control unit 133 of the third power distribution device 13 reads out the interruption time (threshold value) corresponding to the temperature (heat quantity) of the electric wire 17C calculated from the detection value of the current flowing by the detection unit 132 from the interruption characteristics of the interruption unit 131, and when the current flow time measured by the timer exceeds the threshold value, determines that the interruption unit 131 should be interrupted and sends a disconnection signal to the interruption unit 131.

[0026] 1 , the control unit 113 of the first power distribution device 11, the control unit 123 of the second power distribution device 12, and the control unit 133 of the third power distribution device 13 are connected to be able to communicate with each other. The control unit 123 of the second power distribution device 12 transmits the detection value of the open-circuit voltage of the circuit breaker 121 by the detection unit 122 to the control unit 113 of the first power distribution device 11. In addition, the control unit 133 of the third power distribution device 13 transmits the detection value of the open-circuit voltage of the circuit breaker 131 by the detection unit 132 to the control unit 113 of the first power distribution device 11.

[0027] The control unit 113 of the first power distribution device 11 compares the detected value of the open-circuit voltage of the breaker 121 received from the control unit 123 of the second power distribution device 12 with the detected value of the open-circuit voltage of the breaker 111 received from the detection unit 112. Then, the control unit 113 of the first power distribution device 11 determines that the open-circuit voltage of the breaker 111 is located upstream of the breaker 121 based on the fact that the open-circuit voltage of the breaker 111 is higher than the open-circuit voltage of the breaker 121.

[0028] Furthermore, control unit 113 of first power distribution device 11 compares the detected value of the open-circuit voltage of breaker unit 131 received from control unit 133 of third power distribution device 13 with the detected value of the open-circuit voltage of breaker unit 111 received from detection unit 112. Control unit 113 of first power distribution device 11 then determines that breaker unit 111 is located upstream of breaker unit 131 when the open-circuit voltage of breaker unit 111 is higher than the open-circuit voltage of breaker unit 131. Note that the method of determining the upstream-downstream relationship between breaker unit 111 and breaker units 121 and 131 is not limited to the method of determination based on the open-circuit voltage, and may be replaced with another method, such as storing information indicating the upstream-downstream relationship in advance.

[0029] The control units 113, 123, and 133 are communicatively connected to the in-vehicle communication device 18 shown in FIG. 1 , and the communication device 18 is communicatively connected to a data center DC via a wireless communication network such as a mobile phone network. The control units 113, 123, and 133 can transmit to the communication device 18 an acquisition request for information related to changes in the in-vehicle loads 2A, 2B, and 2C (hereinafter, referred to as load change information). The communication device 18 can also transmit to the data center DC an acquisition request for the load change information received from the control units 113, 123, and 133. The data center DC also stores load change information related to the interruption characteristics of the interruption units 111, 121, and 131, and can transmit the load change information to the communication device 18 in response to the received acquisition request. The communication device 18 can also transmit the load change information received from the data center DC to the control units 113, 123, and 133.

[0030] The control units 113, 123, and 133 can be connected to the service terminal ST via wired or wireless communication. The control units 113, 123, and 133 can transmit a request to acquire load change information to the service terminal ST. Furthermore, the service terminal ST stores load change information related to the cutoff characteristics of the cutoff units 111, 121, and 131, and can transmit the load change information to the control units 113, 123, and 133 in response to the received acquisition request.

[0031] Here, a case will be described in which the vehicle load 2B connected to the circuit breaker 121 of the second power distribution device 12 is changed to the vehicle load 2B'. An example is assumed in which the state in which the vehicle load 2B, which is a small lighting device that lights up with a relatively small current, is connected to the circuit breaker 121 by the electric wire 17B rated for the small current is changed to the state in which the vehicle load 2B', which is a large lighting device that lights up with a relatively large current, is connected to the circuit breaker 121 by the electric wire 17B' rated for the large current.

[0032] In this assumed example, as shown by the solid line in the graph of Fig. 3, the relationship between the conduction current and the interruption time of the interrupter 121 corresponding to the in-vehicle load 2B before the change is initially set to match the conduction current, which is a relatively small current (I2). Also, as shown by the dashed line in the graph of Fig. 3, the relationship between the conduction current and the interruption time of the interrupter 121 corresponding to the in-vehicle load 2B' after the change is set to match the conduction current, which is a relatively large current (I2').

[0033] 2 is initially set to the smoke generation characteristics of wire 15 (the relationship between the amount of heat and the time from the start of current flow until smoke generation (hereinafter referred to as smoke generation time)). The curve showing the relationship between the current flowing through breaker unit 111 and the interruption time before the change, shown by the dashed line in the graph of FIG. 3, is initially set to lie between the curve showing the relationship between the current flowing through breaker unit 121 and the interruption time before the change and the curve showing the relationship between the current flowing through wire 15 and the time until smoke generation. Although not shown in the graph of FIG. 3, the curve showing the relationship between the current flowing through breaker unit 111 and the interruption time before the change is initially set to lie between the curve showing the relationship between the current flowing through breaker unit 131 and the interruption time and the curve showing the relationship between the current flowing through wire 15 and the time until smoke generation. That is, the relationship between the current flow and the interruption time of the interruption units 111, 121, and 131 is initially set so that the interruption time of the interruption unit 111 is shorter than the smoking time of the electric wire 15 and longer than the interruption times of the interruption units 121 and 131.

[0034] 3, the curve showing the relationship between the conduction current and the interruption time of the circuit breaker 111 before the change, shown by the dashed line, intersects with the curve showing the relationship between the conduction current and the interruption time of the circuit breaker 121 after the change when the conduction current is I3 (>I2'>I2), and does not fall within the range between the curve showing the relationship between the conduction current and the interruption time of the circuit breaker 121 after the change and the curve showing the relationship between the conduction current of the electric wire 15 and the time until smoke is generated. In other words, when the conduction current is I3 or more, the interruption time of the circuit breaker 111 becomes shorter than the interruption time of the circuit breaker 121. Therefore, when the conduction current is I3, the circuit breaker 111 and the circuit breaker 121 are interrupted at the same time, and when an abnormality occurs in the in-vehicle load 2B', not only the in-vehicle load 2B' but also the ECU 4 cannot be operated simultaneously.

[0035] Therefore, in the power distribution device 10 of this embodiment, when the downstream in-vehicle loads 2B, 2C are changed, not only are the interruption characteristics of the interrupting units 121, 131 corresponding to the changed in-vehicle loads 2B, 2C changed, but the interruption characteristics of the upstream interrupting unit 111 are also changed. Specifically, first, each control unit 113, 123, 133 acquires the detected values ​​of the voltage and current of each interrupting unit 111, 121, 131 from the detection units 112, 122, 132 each time the power supply device 1 is reset. Each control unit 113, 123, 133 determines whether or not change processing of the interruption characteristics of each interrupting unit 111, 121, 131 is necessary depending on the amount of change in the detected values ​​of the voltage and current of each interrupting unit 111, 121, 131. In the above assumed example, when the vehicle load 2B connected to the interrupter 121 is changed to the vehicle load 2B', the detected voltage and current values ​​of the interrupter 121 change, and the control unit 123 determines that processing to change the interruption characteristics of the interrupter 121 is necessary.

[0036] When each control unit 113, 123, 133 determines that it is necessary to change the cutoff characteristics of each cutoff unit 111, 121, 131, it transmits a request to acquire load change information to the data center DC or the service terminal ST and receives the load change information from the data center DC or the service terminal ST. Each control unit 113, 123, 133 changes the cutoff characteristics of each cutoff unit 111, 121, 131 in accordance with the received load change information.

[0037] Next, the control unit 113 of the first power distribution device 11 changes the interrupting characteristics of the interrupting unit 111 so that the curve showing the relationship between the current flowing through the interrupting unit 111 and the interrupting time falls between the curve showing the relationship between the current flowing through the interrupting units 121, 131 and the interrupting time after the change and the curve showing the relationship between the current flowing through the electric wire 15 and the time until smoking occurs. Hereinafter, a process of changing the interrupting characteristics of the upstream interrupting unit 111 after changing or adding the downstream in-vehicle loads 2B, 3B will be described.

[0038] 4 is a flowchart for explaining the process of changing the interruption characteristics of the upstream interrupter 111 after changing or adding the downstream in-vehicle loads 2B, 3B. The process shown in this flowchart starts when the power supply device 1 is reset.

[0039] First, each control unit 113, 123, 133 acquires the detected values ​​of the voltage and current of each interrupter 111, 121, 131 from each detection unit 112, 122, 132, and determines whether the amount of change in the detected value since the last reset of the power supply device 1 exceeds a threshold (step S1). If the determination in step S1 is affirmative, the process proceeds to step S2, and if the determination in step S1 is negative, the process proceeds to normal processing.

[0040] Next, each control unit 113, 123, 133 transmits a request to acquire load change information to the data center DC or the service terminal ST, and acquires load change information such as cutoff characteristics for the changed in-vehicle load (step S2). Next, each control unit 113, 123, 133 changes the cutoff characteristics of the corresponding cutoff unit 111, 121, 131 based on the acquired load change information (step S3).

[0041] Next, the control unit 113 acquires the open circuit voltage detection values ​​of the respective interrupting units 111, 121, 131 detected by the detection units 112, 122, 132, and determines the upstream-downstream relationship of the interrupting units 111, 121, 131 based on the acquired detection values ​​(step S4).

[0042] Next, the control unit 123 transmits the interruption characteristics of the interruption unit 121 to the control unit 113, and the control unit 133 transmits the interruption characteristics of the interruption unit 131 to the control unit 113 (step S5). Next, the control unit 113 calculates the heat quantity of each of the electric wires 15, 17B, 17B', 17C (hereinafter referred to as electric wire 15, etc.) when a virtual steady-state current flows through each of the electric wires 15, 17B, 17B', 17C, using the following equations (1) to (6) (step S6).

[0043] When the electric current starts to flow through the electric wires 15 and the like, the control unit 113 calculates the heat generation amount X1 per unit length of the electric wires 15 and the like using the following formula (1).

number

[0044] Furthermore, the control unit 113 calculates the amount of heat radiation Y1 from the electric wires 15 and the like using the following equation (2).

number

[0045] Then, the control unit 113 calculates the wire temperature T n Calculate.

number

[0046] That is, every time the sampling time Δt elapses, the control unit 113 calculates the temperature T p The heat generation amount X1 is added or the heat radiation amount Y1 is subtracted from the heat generation amount X1, and the wire temperature T of the wire 15 etc. at the time of measurement is calculated. n Calculate.

[0047] Hereafter, pseudo heat capacity C th * As shown by the curve indicated by the dashed line in the graph of Figure 2, when a given current is continuously passed through the electric wire 15, the amount of heat of the electric wire 15 rises. It is known that the temperature T2 of the electric wire 15 at this time is expressed by the following equation (4).

number

[0048] The control unit 113 determines the continuous current I of a fuse of a standard normally used for the electric wire 15, etc. max Based on this, the temperature threshold ΔT max Calculate the continuous current I of this fuse. max can be obtained by actually passing a current through the fuse and measuring the current and time until the fuse melts.

number

[0049] In the above formula (4), if T2-T1=ΔT, it is expressed by the following formula (4').

number

[0050] The current I in the above formula (4') is appropriately changed, and the elapsed time t is increased for each current I, so that the temperature rise ΔT is equal to or exceeds the temperature threshold ΔT max By plotting the time when the temperature threshold ΔT is reached, a curve showing the relationship between the current flow and the interruption time can be obtained as shown in the graph of Figure 3. max By multiplying this by the mass and specific heat of the electric wire 15 etc., the threshold values ​​of the heat quantity (shutoff threshold A, shutoff threshold A', shutoff threshold B, shutoff threshold B') shown in the graph of FIG. 2 are obtained.

[0051] The temperature threshold ΔT calculated using equation (5) above maxSubstitute the value of ΔT in the above equation (4'), and the left side is the heat capacity C th Transform the equation so that the heat capacity C th is the pseudo heat capacity C th * When this is substituted, the following equation (6) is obtained.

number

[0052] As shown in the flowchart of FIG. 4, the control unit 113 calculates the interruption time of each of the interruption units 111, 121, 131 when the virtual steady-state current flows through the electric wire 15, etc., based on the heat quantity and interruption threshold of each of the interruption units 111, 121, 131 (step S7).

[0053] Next, control unit 113 determines whether the interruption times of interruption units 121 and 131 are longer than the interruption time of interruption unit 111 (step S8). As shown in the graph of Fig. 2, in the initial setting, interruption time T1 of interruption unit 111 is longer than interruption time T2 of interruption unit 121, but after the in-vehicle load 2B is changed, it is expected that interruption time T1 of interruption unit 111 will be shorter than interruption time T2' of interruption unit 121. As shown in the flowchart of Fig. 4, if a positive determination is made in step S8, the process proceeds to step S9, and if a negative determination is made in step S8, the process proceeds to normal processing.

[0054] The control unit 113 changes the time constant τ shown in the following equation (7) to change the interruption characteristics of the interruption unit 111 so that the interruption characteristics of the interruption unit 111 are between the changed interruption characteristics of the interruption units 121 and 131 and the smoke generation characteristics of the electric wire 15 (step S9). As a result, as shown in the graph of FIG. 2, the interruption time T1' of the interruption unit 111 becomes longer than the interruption time T2' of the interruption unit 121.

number

[0055] The above equation (7) is obtained by converting the above equation (6) with ΔT max as the left side into the following equation (8), and after converting the following equation (8) into an equation with the time constant τ as the left side, ΔT max is converted so that it becomes a value between the temperature threshold of the changed cutoff part 121 and the temperature threshold of the smoke generation characteristic of the electric wire 15 for the in - vehicle load 2B’.

Equation

[0056] As shown in the flowchart of FIG. 4, the control unit 113 determines whether the cutoff time of the cutoff part 111 is longer than the cutoff times of the cutoff parts 121 and 131 (step S10). If an affirmative determination is made in step S10, the process proceeds to normal processing. If a negative determination is made in step S10, alarm processing is executed (step S11), and then the process proceeds to normal processing. <0000​​As described above, in the power distribution device 10 of this embodiment, when the vehicle loads 2B, 2C connected to the downstream second power distribution device 12 or the third power distribution device 13 are changed or added, the interrupting characteristics of the circuit breakers 121, 131 of the second power distribution device 12 or the third power distribution device 13 are changed. In this situation, if the interrupting time of the circuit breaker 111 of the upstream first power distribution device 11 becomes shorter than the interrupting times of the circuit breakers 121, 131, the control unit 113 of the upstream first power distribution device 11 changes the interrupting characteristics of the circuit breaker 111 so that the interrupting time of the circuit breaker 111 becomes longer than the interrupting times of the circuit breakers 121, 131. As a result, when the vehicle loads 2B, 2C connected to the downstream second power distribution device 12 or the third power distribution device 13 are added or changed, the electric wires 15 and the like can be protected from the upstream side to the downstream side without the need to redesign the circuit breakers 111, 121, 131. Furthermore, simultaneous interruption of the upstream interrupter 111 and the downstream interrupters 121 and 131 can be prevented.

[0058] In the power distribution device 10 according to this embodiment, the interruption characteristics of the upstream interrupter 111 and the downstream interrupters 121 and 131 are initially set so that the interruption time between the interrupter 111 and the interrupter 121 and 131 is shorter than the smoke generation time, which is the time from the start of current flow through the electric wire 15 to the generation of smoke. In addition, the interruption characteristics of the interrupter 111 and the interrupter 121 and 131 are initially set so that the interruption time of the interrupter 111 is longer than the interruption times of the interrupter 121 and 131. On the other hand, in a situation where the on-vehicle loads 2B, 2C connected to the downstream second power distribution device 12 or the third power distribution device 13 are changed or added and the interrupting characteristics of the interrupting units 121, 131 are changed, if the interrupting time of the interrupting unit 111 becomes shorter than the interrupting times of the interrupting units 121, 131, the control unit 113 changes the interrupting characteristics of the interrupting unit 111 so that the interrupting time of the interrupting unit 111 becomes longer than the interrupting times of the interrupting units 121, 131 and shorter than the smoking time of the electric wire 15. This makes it possible to prevent the upstream side interrupting unit 111 and the downstream side interrupting units 121, 131 from being cut off simultaneously, and to reliably prevent the electric wire 15 from smoking.

[0059] Moreover, in the power distribution device 10 according to this embodiment, the upstream control unit 113 and the downstream control units 123 and 133 are connected to each other so as to be able to communicate with each other. The upstream control unit 113 receives the interruption characteristics of the downstream circuit breakers 121 and 131 from the downstream control units 123 and 133. Based on the received interruption characteristics of the circuit breakers 121 and 131, the upstream control unit 113 calculates the interruption times of the circuit breakers 121 and 131 when a predetermined current flows through the electric wires 17B, 17B', and 17C. Based on the interruption characteristics of the circuit breaker 111, the upstream control unit 113 also calculates the interruption times of the circuit breaker 111 when a predetermined current flows through the electric wires 15 and 16. Then, when the calculated interruption time of the interruption unit 111 is shorter than the calculated interruption times of the interruption units 121 and 131, the upstream control unit 113 changes the interruption characteristics of the interruption unit 111 so that the interruption time of the interruption unit 111 becomes longer than the interruption times of the interruption units 121 and 131. This makes it possible to compare the interruption times of the interruption units 111, 121 and 131 after changing or adding the in-vehicle loads 2B and 2C, and change the interruption characteristics of the interruption unit 111 based on the comparison result.

[0060] Furthermore, in the power distribution device 10 according to this embodiment, the first power distribution device 11 on the upstream side includes a detection unit 112 that detects the voltage and current of the breaker unit 111, and the second power distribution device 12 and the third power distribution device 13 on the downstream side include detection units 122 and 132 that detect the voltage and current of the breaker units 121 and 131. The control unit 113 of the first power distribution device 11 receives the detection values ​​of the voltage and current of the breaker units 121 and 131 detected by the detection units 122 and 132 from the control units 123 and 133 of the second power distribution device 12 and the third power distribution device 13. This allows the control unit 113 of the first power distribution device 11 to determine the upstream-downstream relationship of the breaker units 111, 121, and 131 by comparing the voltage of the breaker unit 111 on the upstream side with the voltage of the breaker units 121 and 131 on the downstream side. Furthermore, the control unit 113 of the first power distribution device 11 can calculate the amount of heat of the electric wires 15 and the like based on the currents of the breakers 111, 121, and 131.

[0061] The present invention has been described above based on the above embodiment, but the present invention is not limited to the above embodiment, and modifications may be made to the above embodiment within the scope of the spirit of the present invention, or publicly known or well-known technologies may be combined as appropriate. [Explanation of symbols]

[0062] 1: Power supply 2B: Vehicle load (vehicle device) 2B': Vehicle load (vehicle device) 2C: Vehicle load (vehicle device) 10:Power distribution device 11:1st power distribution device 12:Second power distribution device 13:Third power distribution device (second power distribution device) 15: Electric wire (first electric wire) 16: Electric wire (first electric wire) 17B: Electric wire (second electric wire) 17B': Electric wire (second electric wire) 17C: Electric wire (second electric wire) 111: Breaking section (first breaking section) 112: Detection unit (first detection unit) 113: Control unit (first control unit) 121: Breaking section (second breaking section) 122: Detection unit (second detection unit) 123: Control unit (second control unit) 131: Breaking section (second breaking section) 132: Detection unit (second detection unit) 133: Control unit (second control unit) T1: Breaking time (first breaking time) T1': Breaking time (first breaking time) T2: Breaking time (second breaking time) T2': Breaking time (second breaking time)

Claims

1. a first power distribution device that distributes power supplied from a power supply device; a second power distribution device that distributes the power distributed by the first power distribution device to an in-vehicle device, The first power distribution device a first interrupter that connects or interrupts a first electric wire that supplies power from the power supply device to the second power distribution device; a first control unit that controls the first interrupting unit based on a first interrupting characteristic that indicates a relationship between a heat quantity of the first electric wire and a first interrupting time that is a time from when current starts to flow through the first electric wire until the first interrupting unit interrupts the current; Equipped with The second power distribution device a second disconnecting unit that connects or disconnects a second electric wire that supplies power from the first power distribution device to the in-vehicle device; a second control unit that controls the second cutoff unit based on a second cutoff characteristic that indicates a relationship between a heat quantity of the second electric wire and a second cutoff time that is a time from when current starts to flow through the second electric wire until the second cutoff unit cuts off the current; and Equipped with the first cut-off characteristic and the second cut-off characteristic are initially set so that the first cut-off time is longer than the second cut-off time, The first control unit executes a first cut-off characteristic change process to change the first cut-off characteristic so that the first cut-off time becomes longer than the second cut-off time when the in-vehicle device is changed or added, changing the second cut-off characteristic and making the first cut-off time shorter than the second cut-off time.

2. the first interruption characteristic and the second interruption characteristic are initially set so that the first interruption time and the second interruption time are shorter than a smoking time, which is a time from when current starts to flow through the first electric wire until smoking occurs; 2. The power distribution device according to claim 1, wherein the first control unit changes the first cut-off characteristic in the first cut-off characteristic change process so that the first cut-off time is longer than the second cut-off time and shorter than the smoking time.

3. the first control unit and the second control unit are connected to each other so as to be able to communicate with each other; The first control unit receiving the second interruption characteristic from the second control unit; calculating the first breaking time when a predetermined current flows through the first electric wire based on the first breaking characteristic; calculating the second breaking time when the predetermined current flows through the second electric wire based on the second breaking characteristic; The power distribution device according to claim 1 or 2, wherein the first cut-off characteristic change process is executed when the calculated first cut-off time is shorter than the calculated second cut-off time.

4. the first power distribution device includes a first detection unit that detects a voltage and a current of the first cutoff unit, the second power distribution device includes a second detection unit that detects a voltage and a current of the second cutoff unit, The power distribution device according to claim 3 , wherein the first control unit receives, from the second control unit, the detected values ​​of the voltage and current of the second cutoff unit detected by the second detection unit.

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