JP2023014748A - On-vehicle power distribution device - Google Patents

Abstract

To provide an on-vehicle power distribution device which easily performs additional connection of even new electrical components and new functions that are not assumed at design time thereof without making parts such as a wiring harness or the like larger than necessary.SOLUTION: Priority of each load, which is connected to a downstream side of an ECU having power source power distribution function has been previously grasped. Each power source current Ix flowing to each load is detected, and a total current value Iy flowing an electric wire on an upstream side of the ECU is calculated. A relation of "upstream electric wire smoke generation characteristic C0>upstream fuse fusion cutting characteristic C1>power control characteristic C2" is established, and when the total current value Iy approaches the power control characteristic C2, electric conduction of a load with lower priority is blocked or switched to PWM control to reduce the total current value Iy.SELECTED DRAWING: Figure 1

Description

The present invention relates to an in-vehicle power distribution device.

2. Description of the Related Art In recent years, along with advances in automatic driving of vehicles and driving assistance technology, the number of devices such as sensors, electric loads, and ECUs (electronic control units) mounted on vehicles, that is, electrical components, has been steadily increasing. In a typical vehicle, these electrical components are supplied with power from a power source such as an on-vehicle battery through wire harnesses. In some cases, a power supply box is used to enable connection of a plurality of systems of electrical equipment to the downstream side of the on-vehicle power supply.

For example, Patent Literature 1 discloses a technique for easily adding a device to be connected to a power supply box. The in-vehicle system of Patent Document 1 includes a power supply box provided in a vehicle and having a plurality of device connectors and a control unit 2 that supplies power received from a power supply to the plurality of device connectors; a switch for switching between blocking and permitting power supply to the device connector. Further, when the switch permits power supply to the device connector, the control unit identifies the type of the device to be connected connected to the device connector and determines the position of the device connector to which the connection target device is connected. Execute connection target confirmation processing for specifying the

Japanese Patent Application Laid-Open No. 2020-83165

For example, the power supply box disclosed in Patent Document 1 is pre-equipped with connectors for connecting optional devices. Therefore, if a predetermined optional device is retrofitted to the unused connector of the power supply box, it is possible to supply power from the vehicle side to the optional device via the power supply box.

By the way, with the progress of automatic driving technology and driving support technology for vehicles, new electrical components and functions that were not envisioned at the beginning of vehicle development may be added to in-vehicle systems as retrofits. Also, in that case, if the power consumption and other specifications for each retrofitted electrical component are set low in advance, the functions that can be retrofitted will be greatly restricted, and the degree of freedom in design will be reduced. .

On the other hand, parts such as fuses, electric wires for power supply, bus bars, etc. are usually provided at the connecting portion between the power source such as the on-vehicle battery and the power box or the like. In addition, the specifications of the fuse are determined so as to cut off the current before an abnormality such as smoke occurs in the electric wire due to the influence of an overcurrent exceeding the allowable current of the electric wire for power supply.

Therefore, the specification of the upper limit of the current consumed by all electrical equipment connected to the downstream side such as the power supply box is determined in advance, and based on this upper limit, the core wire thickness or cross-sectional area of the electric wire for power supply , and also the breaking characteristics of the fuse.

However, when adding new electrical components that were not envisioned at the beginning of vehicle development and connecting these electrical components to the downstream side of the power supply box, the total current flowing downstream of the power supply box may exceed the maximum current specification in the side wire. In that case, parts such as wires, terminals, and fuses of the wiring harness must be enlarged on the upstream side of the power supply box, but such modification is not easy. In addition, there is a concern that the design cost, work cost, cost of parts to be replaced, etc., associated with the remodeling will increase.

On the other hand, if the power consumption specifications of electrical components that may be added later are designed from the beginning of the development of the vehicle with a large margin in advance, such modifications as described above will not be necessary. However, in that case, the wires, terminals, fuses, and other parts of the wire harness connected to the upstream side of the power supply box become larger than necessary, so electrical components that actually consume large currents are placed downstream of the power supply box. It will be wasteful unless you connect it. As a result, the cost of parts such as wire harnesses increases, and the space occupied by parts such as wire harnesses increases more than necessary.

The present invention has been made in view of the circumstances described above, and its purpose is to prevent the size of parts such as wire harnesses from becoming unnecessarily large, and to use new electrical components and new functions that were not assumed at the time of design. To provide an in-vehicle power distribution device which facilitates additional connection even if there is one.

In order to achieve the above object, an on-vehicle power distribution device according to the present invention is characterized by the following (1) to (5).
(1) an in-vehicle power supply;
A main power supply box that can connect multiple loads,
an upstream wire connecting between the output of the vehicle power supply and the input of the main power supply box;
a plurality of semiconductor switches capable of individually controlling power supply to each of a plurality of loads connected downstream of the main power supply box;
a control unit that controls the plurality of semiconductor switches;
with
The control unit collects, for each of the plurality of semiconductor switches, information about load currents flowing in loads connected downstream of the semiconductor switches, and at least the sum of the load currents is within the allowable current value of the upstream wire. When approaching, the plurality of semiconductor switches are controlled so as to adjust the power distribution to the plurality of loads according to the priority of each of the plurality of loads connected downstream of the main power supply box,
In-vehicle power distribution equipment.

(2) the upstream wire includes an upstream fuse that limits current flowing through the upstream wire;
The allowable current value of the upstream wire is determined to be smaller than at least one of the smoking characteristics of the upstream wire and the breaking characteristics of the upstream fuse.
The in-vehicle power distribution device according to (1) above.

(3) The control unit has a data holding unit that holds in advance fuse information representing cutoff characteristics of the upstream fuse.
The in-vehicle power distribution device according to (2) above.

(4) When the sum of the load currents approaches the allowable current value of the upstream line, the control unit selects a specific load path among the plurality of semiconductor switches connected to a low-priority load path. switching off a semiconductor switch or switching to intermittent energization control such that the particular semiconductor switch limits the energization time;
An in-vehicle power distribution device according to any one of (1) to (3) above.

(5) The control unit obtains priority information of each load connected to the downstream side of the semiconductor switch based on the position of the connector to which each load is connected, or based on information acquired from each load through communication. Identify,
An in-vehicle power distribution device according to any one of (1) to (4) above.

According to the in-vehicle power distribution device with the above configuration (1), new electrical components and new functions that were not assumed at the time of design can be easily implemented without increasing the size of the wires upstream of the main power supply box more than necessary. can be additionally connected to For example, if a new electrical component that consumes a large amount of power source power is connected as a load to the downstream side of the main power supply box, the total load current may increase to the extent that it approaches the allowable current value of the upstream wire. If nothing is controlled, for example, a fuse may break the circuit, or the upstream wire may overheat and smoke. However, since the control unit automatically adjusts power distribution to multiple loads, it is possible to avoid an increase in the sum of load currents. Moreover, since the power distribution is adjusted considering the priority of each of the multiple loads actually connected downstream of the main power supply box, it is possible to avoid restricting the functions of loads with high priority. can. Therefore, modification for replacing parts such as electric wires and fuses on the upstream side of the main power supply box becomes unnecessary.

According to the in-vehicle power distribution device having the above configuration (2), even if a new electrical component that consumes a large amount of power is connected to the downstream side of the main power supply box as a load, the power distribution adjustment of the control unit , the sum of the load currents is controlled so as not to reach the smoking characteristics of the upstream wire or the breaking characteristics of the upstream fuse. Therefore, it is possible to prevent the upstream wire from becoming smoke-emitting, and to prevent the upstream fuse from breaking the circuit.

According to the in-vehicle power distribution device having the above configuration (3), the control unit can acquire the information on the breaking characteristics of the upstream fuse from the data holding unit. can suppress an increase in the sum of

According to the in-vehicle power distribution device having the configuration of (4) above, the increase in the total load current can be suppressed by turning off the specific semiconductor switch connected to the low-priority load path by the control unit. . Moreover, even when a specific semiconductor switch switches to intermittent energization control so as to limit the energization time, an increase in the total load current can be suppressed.

According to the in-vehicle power distribution device having the configuration of (5) above, even when an unknown electrical component is connected as a new load downstream of the semiconductor switch, the control unit can easily obtain information on the priority of the load. can be grasped.

According to the in-vehicle power distribution device of the present invention, it is possible to easily add and connect new electrical components and new functions that have not been assumed at the time of design, without increasing the size of the wires upstream of the main power supply box more than necessary. . For example, if a new electrical component that consumes a large amount of power source power is connected as a load to the downstream side of the main power supply box, the total load current may increase to the extent that it approaches the allowable current value of the upstream wire. If nothing is controlled, for example, a fuse may break the circuit, or the upstream wire may overheat and smoke. However, since the control unit automatically adjusts power distribution to multiple loads, it is possible to avoid an increase in the sum of load currents. Moreover, since the power distribution is adjusted considering the priority of each of the multiple loads actually connected downstream of the main power supply box, it is possible to avoid restricting the functions of loads with high priority. can. Therefore, modification for replacing parts such as electric wires and fuses on the upstream side of the main power supply box becomes unnecessary.

The present invention has been briefly described above. Furthermore, the details of the present invention will be further clarified by reading the following detailed description of the invention (hereinafter referred to as "embodiment") with reference to the accompanying drawings. .

FIG. 1 is a block diagram showing a configuration example of an in-vehicle power distribution device according to an embodiment of the present invention. FIGS. 2(a) and 2(b) are graphs showing examples of power supply characteristics in a general vehicle and a vehicle according to the embodiment, respectively. FIG. 3 is a flow chart showing an operation example of the area ECU shown in FIG. FIG. 4 is a flow chart showing a modification of the operation of the area ECU. FIG. 5 is a flow chart showing an example of processing for the microcomputer to grasp the load priority.

Specific embodiments relating to the present invention will be described below with reference to each drawing.

FIG. 1 is a block diagram showing a configuration example of an in-vehicle power distribution device 100 according to an embodiment of the present invention.

The vehicle-mounted power distribution device 100 shown in FIG. 1 is mainly composed of an area ECU 20 . The area ECU 20 has a function of managing a predetermined specific area on the vehicle, and has a function of supplying power from the power source to loads such as various electrical components connected downstream thereof. ing. The area managed by the area ECU 20 may be assigned to a specific area in the space above the vehicle, or may be assigned to a specific function group.

An in-vehicle power supply 10 shown in FIG. 1 corresponds to, for example, a main battery, an alternator, a DC/DC converter, etc. mounted in a vehicle, and serves as a source of power supply required by various electrical components mounted in the vehicle. Function. The output voltage of the in-vehicle power source 10 is, for example, 12 [V], but it may output a voltage of 48 [V] or the like.

In the example shown in FIG. 1 , a plurality of upstream electric wires 11 and 12 are connected to the output of an onboard power source 10 . Each upstream electric wire 11, 12 is provided with an upstream fuse 13, 14, respectively. The upstream fuses 13 and 14 have the function of blowing out to break the circuit when a large current exceeding the allowable value flows through the upstream wires 11 and 12, respectively. That is, if a large current continues to flow through each of the upstream wires 11 and 12 and abnormally heats up, problems such as smoke generation may occur. ing.

A power input terminal 20 a of the area ECU 20 is connected to the downstream side of the upstream electric wire 11 . Therefore, the power supply power output from the vehicle-mounted power supply 10 is supplied to the area ECU 20 via the upstream fuse 13 and the upstream wire 11 .

The area ECU 20 has a plurality of signal input terminals 20b. A plurality of signal lines 51 are connected to these signal input terminals 20b. Therefore, signals from various sensors and switches on the vehicle are input to the area ECU 20 via the signal line 51 .

The area ECU 20 also has a communication terminal 20c. This communication terminal 20c is connected to a communication bus 52 on the vehicle side. The communication bus 52 is a transmission line of a communication network configured according to vehicle communication standards such as CAN (Controller Area Network), and performs data communication between various ECUs and other electrical components on the vehicle. to enable.

, power supply output terminals 26a, 26b, 26c, . . . , power supply output terminals 27a, 27b, . A terminal 28 is provided.

The power supply output terminals 25a, 25b, 25c, . It is provided to supply the necessary power supply power respectively. Therefore, in the example of FIG. 1, the traveling system load 31A is connected to the power output terminal 25a, and the traveling system load 31B is connected to the power output terminal 25b.

The power supply output terminals 26a, 26b, 26c, . For example, lamps such as headlights and winkers, wipers, air conditioners, door lock devices, car navigation devices, and audio devices belong to the accessory system. Therefore, in the example of FIG. 1, the accessory load 32A is connected to the power output terminal 26a, and the accessory load 32B is connected to the power output terminal 26b.

On the other hand, the power supply output terminals 27a, 27b, . In the example of FIG. 1, the additional load 33A is connected to the power output terminal 27a, and the additional ECU 33B is connected to the power output terminal 27b. However, the additional load 33A and the additional ECU 33B are electrical components that are only assumed to be objects that may be connected at the beginning of the design of this vehicle. Therefore, for example, the specification of the power supply current consumed by each of the additional load 33A and the additional ECU 33B is determined as necessary after designing the vehicle.

However, it is assumed that the total power supply current consumed by all the loads downstream of the area ECU 20 will change significantly between before and after the element of the additional function 40 is connected to the area ECU 20 shown in FIG. be. This change affects the magnitude of the current flowing through the upstream wire 11 , and a large current exceeding the allowable current of the upstream wire 11 may flow through the upstream wire 11 .

In general design, if the maximum value of the current flowing through the upstream wire 11 increases, the upstream wire 11 must be changed to a thicker wire to increase the allowable current. In addition, the specifications of parts such as the upstream fuse 13 and the terminals of each part must be changed in accordance with changes in the allowable current and thickness of the upstream electric wire 11, which necessitates a large-scale modification.

On the other hand, in some cases, the allowable current of the upstream wire 11 is designed to have a margin in anticipation of an increase in the power supply current that will be newly consumed due to the connection of the additional function 40 in the future. In that case, the power supply current actually consumed by the loads connected to the downstream side of the area ECU 20 will have a larger margin than necessary. becomes larger.

In the in-vehicle power distribution device 100 shown in FIG. 1, there is no need to give extra margin to the thickness of the upstream wire 11, and moreover, the additional function 40 whose specifications such as the power supply current to be consumed are undecided at the time of initial design. Even when it is connected to the area ECU 20, it is possible to prevent the upstream electric wire 11 from emitting smoke or the like without any special modification. A function for that purpose is installed in the area ECU 20 .

The area ECU 20 has a microcomputer 21 , a communication circuit 22 , a switch section 23 and a nonvolatile memory 24 .
In addition, in the example of FIG. 1, the switch section 23 includes a first switch section 23a, a second switch section 23b, and a spare switch section 23c. Also, in the switch section 23, the first switch section 23a, the second switch section 23b, and the backup switch section 23c are provided with IPDs (Intelligent Power Devices) corresponding to the number of loads connectable thereto.

Each IPD incorporates a semiconductor switch (MOSFET) that switches ON/OFF of the current flowing through the load, a gate driver, a current detection function, a protection circuit, and the like.

In the state shown in FIG. 1, for example, when the uppermost IPD in the first switch section 23a is turned on, the power supply line 29, the IPD in the first switch section 23a, and the power output terminal 25a are connected from the power supply input terminal 20a. The power supply current passing through is supplied to the traveling system load 31A. Further, when the IPD is turned off, power supply to the travel system load 31A is cut off.

Therefore, by turning on/off each IPD in the switch unit 23, power supply to a plurality of loads connected to the downstream side of the area ECU 20 is individually turned on/off. In addition, it is possible to perform intermittent energization control such as pulse width modulation control (PWM) by periodically repeating ON/OFF in a short cycle.

A control input of each IPD in the switch section 23 is connected to an output port of the microcomputer 21 respectively. Information on the current detected by each IPD in the switch section 23 is input to the input port of the microcomputer 21 . Therefore, the microcomputer 21 can individually grasp the power supply current flowing through each load connected to the downstream side of the area ECU 20 . Further, the microcomputer 21 can individually control on/off of power supply to each load connected to the downstream side of the area ECU 20 .

, power output terminals 26a, 26b, 26c, . . , power output terminals 27a, 27b, . , a connector is provided to allow attachment and detachment of physical and electrical connection. For the electrical components connected to each connector, the priority for power supply is determined in advance for each connector. Also, in this example, three types of "high", "middle", and "low" are defined as the priority.

In this embodiment, as shown in FIG. 1, the priority of the connectors of the traveling system loads 31A and 31B is "high", the priority of the connector of the auxiliary system load 32A is "high", and the priority of the connector of the auxiliary system load 32B is "high". The priority is set to "low", and the priority of the connectors of the additional load 33A and the additional ECU 33B is set to "middle".

However, with regard to the additional load 33A and the additional ECU 33B, which will be connected later as the additional function 40, if the specifications including the priority are fixed at the initial stage of design, it becomes difficult to connect new equipment that realizes advanced functions. Therefore, the additional ECU 33B communicates with the microcomputer 21 using the communication terminal 28 so that the assigned priority can be changed.

The microcomputer 21 can realize various functions necessary for controlling the area ECU 20 by executing a preinstalled program. For example, the status can be identified based on the state of various signals input to the signal input terminal 20b, and on/off control of each load connected to the downstream side of the area ECU 20 can be performed. Further, the microcomputer 21 can exchange information with other ECUs via the communication circuit 22 and the communication bus 52 as necessary.

The nonvolatile memory 24 can hold various predetermined constant data. For example, data representing the specifications of the upstream fuses 13 and 14 connected to the upstream electric wires 11 and 12 (for example, 30 [A], 40 [A], etc.), data for each connector on the output side of the area ECU 20, Data such as the assigned priority is stored in a predetermined storage area on the nonvolatile memory 24 in advance.

FIGS. 2(a) and 2(b) are graphs showing examples of power supply characteristics in a general vehicle and a vehicle according to the embodiment, respectively.

In the in-vehicle power distribution device 100 shown in FIG. 1, the upstream electric wire 11 on the upstream side of the area ECU 20 is heated by Joule heat according to the power loss determined by the internal resistance of this electric wire and the current (Iy) passing through this electric wire. Fever. In addition, if the thickness (cross-sectional area) of the core wire of the electric wire is small, the internal resistance per unit length increases, so the amount of heat generated increases. Therefore, if a large current exceeding the allowable current of the upstream wire 11 continues to flow, the temperature may continue to rise and the upstream wire 11 may smoke. To prevent this, the upstream fuse 13 cuts off the circuit when a large current flows.

The boundary of the conditions under which the upstream wire 11 begins to emit smoke can generally be represented by a curve such as the upstream wire smoke emission characteristic C0 shown in FIG. 2(a). In other words, when a larger current flows, there is a possibility that a smoking state may occur with only a short period of energization. Further, when current flows continuously for a long period of time, even an overcurrent slightly larger than the allowable current may lead to a smoking state.

On the other hand, the characteristics of the upstream fuse 13 inserted in series with the upstream wire 11 can be represented by a curve like the upstream fuse fusing characteristic C1 shown in FIG. 2(a). That is, it is designed so that the upstream fuse 13 melts and cuts off the circuit before the current (Iy) actually flowing through the upstream wire 11 approaches the boundary of the curve of the upstream wire smoke generation characteristic C0. be done.

Also, the specifications of the area ECU 20 and the specifications of each load connected downstream thereof are set so that the total current value Iy flowing through the upstream wire 11 does not reach the boundary of the upstream fuse fusing characteristics C1 shown in FIG. Determined in advance. For example, the maximum value of power supply current flowing through each load is limited, or a large power supply current does not continue to flow for a long period of time. Therefore, like the characteristic curve of the total current value Iy shown in FIG. 2A, the total current value Iy actually flowing through the upstream wire 11 operates below the boundary of the upstream fuse fusing characteristic C1. . Therefore, a situation in which the upstream fuse 13 is blown does not occur.

However, if the thickness of the upstream wire 11 and the specifications of the upstream fuse 13 are designed based on the total current value Iy in the state where the additional function 40 is not connected as shown in FIG. In this case, the total current value Iy may reach the upstream fuse blowing characteristic C1. As a result, the upstream fuse 13 is melted. Since the supply of power to the downstream side of the area ECU 20 stops due to the blowing of the upstream fuse 13, the functions of the loads connected to the area ECU 20 also stop.

Therefore, the area ECU 20 shown in FIG. 1 has a function of performing control based on the power control characteristic C2 shown in FIG. 2(b). As shown in FIG. 2(b), the curve of the power control characteristic C2 is positioned lower than the boundary of the curve of the upstream fuse blowing characteristic C1.

In practice, the area ECU 20 controls the current on the load side so that the total current value Iy is limited to the power control characteristic C2 or less both before and after the additional function 40 is connected. Therefore, the total current value Iy is reduced before the total current value Iy approaches the boundary of the curve of the upstream fuse blowing characteristic C1. As a result, even if the additional function 40 not assumed at the beginning of the design of the area ECU 20 is connected to the downstream side of the area ECU 20, the upstream fuse 13 can be prevented from blowing.

FIG. 3 is a flow chart showing an operation example of the area ECU 20 shown in FIG. That is, the microcomputer 21 in the area ECU 20 executes control of each step in FIG. 3 according to the program. The operation of FIG. 3 will be described below.

When the power supply of the area ECU is turned on, the microcomputer 21 advances from S11 to S12, and extracts the fuse representing the characteristics of the upstream fuse 13 (for example, the current specification is 30 [A]) from the information storage unit M01 in the nonvolatile memory 24. Acquire the specification information D1.

The information storage unit M02 in the nonvolatile memory 24 holds in advance a list of fusing characteristics information representing the relationship between current values and fusing characteristics of fuses having various characteristics.

Based on the fuse specification information D1 acquired in S12, the microcomputer 21 acquires data of the upstream fuse blowing characteristic C1 (see FIG. 2B) corresponding to the upstream fuse 13 from the information storage unit M02 in S13.

The microcomputer 21 determines data of the power control characteristic C2 in S14 based on the upstream fuse blowing characteristic C1 obtained in S13. The curve of this power control characteristic C2 is determined such that the current and time are smaller than those of the upstream fuse blowing characteristic C1 by a constant value, for example, as shown in FIG. 2(b).

In S15, the microcomputer 21 acquires priority information D2 representing the priority of each load connected to the downstream side of the area ECU 20 . For each priority, an initial value is assigned in advance to the position of the connector that connects each load, but the priority can be changed.

In step S16, the microcomputer 21 obtains, from each IPD, an energization current value Ix flowing through the IPD in the switch unit 23 that controls energization of each load connected to the downstream side of the area ECU 20 .

The microcomputer 21 always monitors in S17 the length of time during which the current flows through the IPD that controls the energization of each load connected to the downstream side of the area ECU 20 as the energization time length Tx.

The microcomputer 21 calculates the total current value Iy, which is the sum of the currents flowing through all the loads connected to the downstream side of the area ECU 20, and calculates the energization time length Ty (S18). Here, the total current value Iy corresponds to the current value flowing through the upstream wire 11 and the upstream fuse 13 .

The total current value Iy and the energization time length Ty are 0 immediately after the power supply of the area ECU is switched from off to on, and sequentially change stepwise on the graph of FIG. Change. In addition, in consideration of the heat generation and heat dissipation according to the power loss occurring in the upstream wire 11, an appropriate energization time is determined based on the energization time length Tx of each load so as to reflect the actual temperature change of the upstream wire 11. A length Ty is calculated.

The microcomputer 21 compares the latest total current value Iy and the energization time length Ty calculated in S18 with the threshold value representing the boundary of the power control characteristic C2 determined in S14 (S19). Then, when the latest total current value Iy and the energization time length Ty approach the power control characteristic C2, the process proceeds to S21.

The microcomputer 21 is connected to the downstream side of the area ECU 20 and switches off the IPD that controls the energization of the load with the low priority determined in S15 among the energized loads to cut off the energization. (S21).

On the other hand, if the microcomputer 21 detects from the comparison in S19 that the latest total current value Iy and energization time length Ty have a sufficient margin (current is small) with respect to the power control characteristic C2, Proceed to S23. In that case, the microcomputer 21 cancels in S23 the current interruption to the load that was interrupted in S21.

By executing the operation shown in FIG. 3, the total current value Iy flowing through the upstream wire 11 and the upstream fuse 13 is automatically controlled to be limited to the boundary of the power control characteristic C2 in FIG. 2(b). be.

Therefore, even if a new additional function 40 that was not assumed at the beginning of the design of the vehicle-mounted power distribution device 100 is added and connected to the area ECU 20, the upstream fuse 13 can be prevented from blowing. Moreover, when the total current value Iy approaches the power control characteristic C2, only the low-priority loads are de-energized, so the high-priority loads can be maintained at all times. In addition, since the design specification of the total current value Iy flowing through the upstream wire 11 and the upstream fuse 13 can be determined without considering the undetermined power supply current flowing through the additional function 40, the upstream wire 11 need not be thickened, and the additional function The change when adding 40 is also unnecessary. Furthermore, when the total current value Iy is relatively small, power can be supplied even to loads with low priority.

FIG. 4 is a flow chart showing a modification of the operation of the area ECU 20. As shown in FIG. The operation shown in FIG. 4 is a modification of the operation shown in FIG. 3, and only steps S21A and S23A are changed. The operation of the modified portion is described below.

In the operation of FIG. 4, the microcomputer 21 advances to the processing of S21A when the latest total current value Iy and current supply time length Ty approach the power control characteristic C2. Then, when energizing a load with a low priority ascertained in S15 among the loads that are connected downstream of the area ECU 20 and are in an energized state, the IPD is periodically turned on and off in a short cycle, and the pulse width is Modulation control (PWM) is implemented (S21A). In other words, the pulse width of the current flowing through the load is limited, and the effective value of the current is controlled to be smaller than usual.

On the other hand, if the microcomputer 21 detects from the comparison in S19 that the latest total current value Iy and energization time length Ty have a sufficient margin (current is small) with respect to the power control characteristic C2, Proceed to S23A. In that case, the energization control for the load changed to PWM control in S21A is returned to normal ON/OFF control in S23A.

When the operation of FIG. 4 is performed, when the total current value Iy and the energization time length Ty approach the power control characteristic C2, the power source power supplied to the low priority load is limited. Functionality is temporarily degraded under load, but minimum functionality can be maintained at all times.

Note that the operations of FIGS. 3 and 4 may be combined. For example, when the latest total current value Iy and the energization time length Ty approach the power control characteristic C2, the control of the low priority load is first shifted to PWM control as in S21A, and even in that PWM control, the total current value When the value Iy and the energization time length Ty approach the power control characteristic C2, control is performed so as to completely cut off the energization of the corresponding load in the same manner as in S21.

FIG. 5 is a flow chart showing an example of processing for the microcomputer 21 to grasp the load priority. That is, the details of step S15 in FIG. 3 are shown in FIG.

, 26a, 26b, 26c, . . . , 27a, 27b on the downstream side of the area ECU 20. In S31, the correspondence relationship with the load connected to is grasped.

The information storage unit M03 in the non-volatile memory 24 holds in advance data representing a list of priorities for each connector. For example, in the situation of priority shown in FIG. High, Low, Medium, and Medium.

The microcomputer 21 acquires the priority information D2 representing the priority of the position of the connector connected to each load from the information storage unit M03 of the nonvolatile memory 24 and grasps the priority (S32).

Further, when each load is an ECU having a communication function, communication can be performed between the load-side ECU and the area ECU 20 . For example, since the additional ECU 33B shown in FIG. 1 is connected to the communication terminal 28, it can communicate with the microcomputer 21 via the communication circuit 22.

When the microcomputer 21 can communicate with each load, the microcomputer 21 acquires the priority information D2 transmitted by each load in S33. In this embodiment, the priority information D2 of each load grasped by the microcomputer 21 is overwritten with information obtained later. Therefore, the priority of the load that cannot communicate is fixed to the priority assigned in advance to the connector position, but in the case of the load that can communicate, the priority grasped by the microcomputer 21 is changed according to the specifications of the load. It is possible to

Of the additional functions 40 shown in FIG. 1, parts such as the spare switch section 23c, the power supply output terminals 27a and 27b, and the communication terminal 28 may be incorporated in the area ECU 20 in advance, or may be added to the additional load. 33A, the additional ECU 33B, etc., may be incorporated into the area ECU 20 as a retrofit.

As described above, in the in-vehicle power distribution device 100, even if the additional function 40 having specifications not assumed at the beginning of the design is additionally connected to the area ECU 20 later, the total current value Iy does not exceed the power control characteristic C2. to prevent the upstream fuse 13 from blowing. Therefore, when connecting the additional function 40, there is no need to modify parts such as the upstream wire 11 and the upstream fuse 13, and easy connection like plug-and-play can be realized. In addition, by preventing the blowing of the upstream fuse 13, the supply of power from the power supply is always maintained for loads with high priority, and the functions do not stop, so reliability can be improved. Moreover, since there is no need to give extra margin to the size of parts such as the upstream wire 11 and the upstream fuse 13, it is possible to avoid an increase in the size of the parts such as the upstream wire 11 and the like.

It should be noted that the present invention is not limited to the above-described embodiments, and can be modified, improved, etc. as appropriate. In addition, the material, shape, size, number, location, etc. of each component in the above-described embodiment are arbitrary and not limited as long as the present invention can be achieved.

Here, the features of the vehicle-mounted power distribution device according to the embodiment of the present invention described above are summarized and listed briefly in [1] to [5] below.
[1] an in-vehicle power supply (10);
a main power supply box (area ECU 20) to which multiple loads can be connected;
an upstream wire (11) connecting between the output of the vehicle-mounted power supply and the input of the main power supply box;
a plurality of semiconductor switches (each IPD in the switch section 23) capable of individually controlling power supply to each of a plurality of loads connected downstream of the main power supply box;
a control unit (microcomputer 21) that controls the plurality of semiconductor switches;
with
For each of the plurality of semiconductor switches, the control unit collects information on load currents flowing in loads connected downstream of the semiconductor switches (S16), and at least sums the load currents (total current value Iy). approaches the allowable current value (power control characteristic C2) in the upstream line, power distribution to the plurality of loads according to the priority of each of the plurality of loads connected to the downstream side of the main power supply box controlling the plurality of semiconductor switches so as to adjust (S19 to S23)
In-vehicle power distribution equipment.

[2] The upstream wire comprises an upstream fuse (13) for limiting the current flowing through the upstream wire,
The allowable current value (power control characteristic C2) of the upstream wire is determined to be smaller than at least one of the smoking characteristics (C0) of the upstream wire and the breaking characteristics (upstream fuse fusing characteristics C1) of the upstream fuse ( See FIG. 2(b)),
The in-vehicle power distribution device according to [1] above.

[3] The control unit has a data holding unit (nonvolatile memory 24, information storage unit M01) that holds in advance fuse information (fuse specification information D1) representing cutoff characteristics of the upstream fuse.
The in-vehicle power distribution device according to [2] above.

[4] When the sum of the load currents approaches the allowable current value of the upstream line, the control unit selects a specific load path among the plurality of semiconductor switches connected to a low-priority load path. Switch off the semiconductor switch (S21) or switch to intermittent energization control so that the specific semiconductor switch limits the energization time (S21A);
An in-vehicle power distribution device according to any one of [1] to [3] above.

[5] The control unit acquires priority information of each load connected downstream of the semiconductor switch based on the position of the connector to which each load is connected (S32) or from each load through communication. specified by the information obtained (S33),
An in-vehicle power distribution device according to any one of [1] to [4] above.

REFERENCE SIGNS LIST 10 in-vehicle power source 11, 12 upstream electric wire 13, 14 upstream fuse 20 area ECU
20a power supply input terminal 20b signal input terminal 20c communication terminal 21 microcomputer 22 communication circuit 23 switch section 23a first switch section 23b second switch section 23c spare switch section 24 nonvolatile memory 25a, 25b, 25c power supply output terminals 26a, 26b , 26c power supply output terminals 27a, 27b power supply output terminals 28 communication terminals 29 power supply lines 31A, 31B traveling system loads 32A, 32B auxiliary machine system loads 33A additional load 33B additional ECU
40 Additional function 51 Signal line 52 Communication bus 100 On-board power distribution device C0 Upstream wire smoke emission characteristics C1 Upstream fuse fusing characteristics C2 Power control characteristics D1 Fuse specification information D2 Priority information Ix Energizing current value Iy Total current value Tx, Ty Energizing time length M01, M02, M03 information storage unit

Claims (5)

in-vehicle power supply;
A main power supply box that can connect multiple loads,
an upstream wire connecting between the output of the vehicle power supply and the input of the main power supply box;
a plurality of semiconductor switches capable of individually controlling power supply to each of a plurality of loads connected downstream of the main power supply box;
a control unit that controls the plurality of semiconductor switches;
with
The control unit collects, for each of the plurality of semiconductor switches, information on load currents flowing in loads connected downstream of the semiconductor switches, and at least the sum of the load currents is equal to the allowable current value in the upstream wire. When approaching, controlling the plurality of semiconductor switches so as to adjust the power distribution to the plurality of loads according to the priority of each of the plurality of loads connected downstream of the main power supply box,
In-vehicle power distribution equipment. the upstream wire comprises an upstream fuse that limits the current flowing through the upstream wire;
The allowable current value of the upstream wire is determined to be smaller than at least one of the smoking characteristics of the upstream wire and the breaking characteristics of the upstream fuse.
The vehicle-mounted power distribution device according to claim 1 . The control unit has a data holding unit that holds in advance fuse information representing cutoff characteristics of the upstream fuse.
The in-vehicle power distribution device according to claim 2. When the sum of the load currents approaches the allowable current value of the upstream line, the control unit selects a specific semiconductor switch among the plurality of semiconductor switches connected to a load path with a low priority. switching off or switching to intermittent energization control such that the particular semiconductor switch limits the energization time;
An in-vehicle power distribution device according to any one of claims 1 to 3. The control unit identifies priority information of each load connected to the downstream side of the semiconductor switch based on the position of the connector to which each load is connected, or by information acquired from each load through communication.
An in-vehicle power distribution device according to any one of claims 1 to 4.

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