JP7690342B2 - On-board power distribution device - Google Patents

Description

The present invention relates to an on-board power distribution device.

In recent years, with the advancement of autonomous driving and driving assistance technologies, the number of electrical equipment installed in vehicles, such as sensors, electric loads, and ECUs (electronic control units), is steadily increasing. In a typical vehicle, these electrical equipment are each supplied with power from a power source such as an on-board battery via a wire harness. In addition, a power supply box may be used to enable the connection of multiple systems of electrical equipment downstream of the on-board power supply.

For example, Patent Document 1 discloses a technology that allows connection target devices to be easily added to a power supply box. The in-vehicle system of Patent Document 1 includes a power supply box that is provided in a vehicle and has multiple device connectors and a control unit 2 that supplies power received from a power source to the multiple device connectors, and a switch that switches between blocking and allowing the power supply to the multiple device connectors in the power supply box. When the switch allows the power supply to the device connector, the control unit executes a connection target confirmation process that identifies the type of connection target device connected to the device connector and locates the position of the device connector to which the connection target device is connected.

JP 2020-83165 A

For example, the power supply box shown in Patent Document 1 is equipped with a connector for connecting optional equipment. Therefore, if a specified optional equipment is later attached to an empty connector on the power supply box, the optional equipment can be supplied with power from the vehicle's power supply via the power supply box.

However, with advances in autonomous driving and driving assistance technologies, there is a possibility that new electrical components and functions that were not envisaged at the time of the vehicle's initial development will be added to the in-vehicle system. Furthermore, in such cases, if the specifications for each electrical component to be added, such as power consumption, are set low in advance, this will result in significant restrictions on the functions that can be added, reducing the freedom of design.

On the other hand, at the connection point between a power source such as an in-vehicle battery and a power box, etc., components such as fuses, power supply wires, or bus bars are usually provided. In addition, the specifications of the fuse are determined so that the current can be cut off before an abnormality such as smoke occurs in the wires due to an overcurrent that exceeds the allowable current of the power supply wires.

Therefore, it is necessary to determine in advance the specifications for the upper limit of the current consumed by all electrical equipment connected downstream of the power supply box, etc., and determine the wire thickness or cross-sectional area of the wire for supplying power from the power source based on this upper limit, and further determine the interrupting characteristics of the fuse.

However, when new electrical equipment that was not anticipated when the vehicle was first developed is added and this electrical equipment is connected downstream of the power supply box, there is a possibility that the total current flowing downstream of the power supply box may exceed the upper current limit specification for the upstream wires. In such a case, there is no choice but to enlarge the wires, terminals, fuses, and other components of the wire harness upstream of the power supply box, but such modifications are not easy to make. There is also a concern that modifications will increase design costs, labor costs, and the costs of replacing parts.

On the other hand, if the power consumption specifications of electrical equipment that may be added later are designed with a large margin in mind from the beginning of vehicle development, the above-mentioned modifications will not be necessary. However, in that case, the wires, terminals, fuses, and other components of the wire harness connected upstream of the power supply box will be larger than necessary, resulting in a lot of waste unless electrical equipment that actually consumes a large current is connected downstream of the power supply box. This leads to higher costs for parts such as wire harnesses, and the space occupied by parts such as wire harnesses will be larger than necessary.

The present invention was made in consideration of the above-mentioned circumstances, and its purpose is to provide an in-vehicle power distribution device that makes it easy to add and connect new electrical components or new functions that were not anticipated at the time of design, without unnecessarily enlarging the size of components such as wire harnesses.

In order to achieve the above-mentioned object, an in-vehicle power distribution device according to the present invention has the following features (1) to (5).
(1) an on-board power supply;
A main power box that can connect multiple loads;
an upstream wire connecting an output of the vehicle power supply and an input of the main power supply box;
a plurality of semiconductor switches capable of individually controlling on/off of current flowing through each of a plurality of loads connected downstream of the main power supply box;
A control unit that controls the plurality of semiconductor switches;
Equipped with
The control unit is
acquiring, for each of the plurality of semiconductor switches, a value of a current flowing through a load connected downstream of the semiconductor switch and a length of time during which the current flows through the load, and calculating a total current value, which is a sum of currents flowing through all of the loads, based on the current value for each of the plurality of loads, and calculating a current-flow time length based on the length of time for each of the plurality of loads;
A power control characteristic is stored in advance, the power control characteristic defining a relationship between time and a current value, and having a characteristic that the current value gradually decreases as the time increases;
When the total current value approaches a current allowable value in the upstream electric wire, which is a current value obtained based on the current flow time length and the power control characteristic , the semiconductor switches are controlled to adjust power distribution to the multiple loads connected downstream of the main power supply box in accordance with the priority of each of the multiple loads so that the total current value is limited to or below the current allowable value.
On-vehicle power distribution equipment.

(2) The upstream electric wire includes an upstream fuse for limiting a current flowing through the upstream electric wire,
the current allowable value of the upstream electric wire is determined to be smaller than at least one of the smoke generation characteristic of the upstream electric wire and the interruption characteristic of the upstream fuse;
The in-vehicle power distribution device according to (1) above.

(3) The control unit includes a data storage unit that stores in advance fuse information indicating a cutoff characteristic of the upstream fuse.
The in-vehicle power distribution device according to (2) above.

(4) When the total current value approaches a current allowable value in the upstream electric wire, the control unit performs pulse width modulation control of periodically repeating on and off a specific semiconductor switch connected to a load having a relatively low priority among the plurality of semiconductor switches maintained on , and when the total current value still approaches the current allowable value in the upstream electric wire after the execution of the pulse width modulation control, switches off the specific semiconductor switch.
An in-vehicle power distribution device according to any one of (1) to (3) above.

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

According to the in-vehicle power distribution device of the above configuration (1), new electrical equipment or new functions that were not envisaged at the time of design can be easily added and connected without unnecessarily enlarging the wires, etc., upstream of the main power supply box. For example, if a new electrical equipment consuming a large amount of power is connected downstream of the main power supply box as a load, the sum of the load currents may increase to a level approaching the allowable current value of the upstream wires. If no control is performed, for example, a fuse may cut off the circuit, or the upstream wires may become abnormally hot and emit smoke. However, since the control unit automatically adjusts the power distribution to the multiple loads, it is possible to avoid an increase in the sum of the load currents. Moreover, since the power distribution is adjusted taking into account the priority of each of the multiple loads actually connected downstream of the main power supply box, it is possible to avoid limiting the function of the load with a high priority. Therefore, there is no need to modify the main power supply box to replace parts such as wires and fuses, etc., upstream of the main power supply box.

According to the on-board power distribution device configured as in (2) above, even if a new electrical device that consumes a large amount of power is connected as a load downstream of the main power supply box, the control unit adjusts the power distribution so that the total load current does not reach the smoke-generating characteristic of the upstream wire or the cut-off characteristic of the upstream fuse. Therefore, the upstream wire can be prevented from entering a smoke-generating state, and the upstream fuse can be prevented from cutting off the circuit.

According to the on-board power distribution device having the configuration (3) above, the control unit can obtain information on the interruption characteristics of the upstream fuse from the data storage unit, and can therefore suppress an increase in the total load current so that the upstream fuse does not enter a state where it interrupts the circuit.

According to the in-vehicle power distribution device having the configuration of (4) above, the control unit can suppress an increase in the total load current by switching off a specific semiconductor switch connected to the path of a low-priority load. In addition, an increase in the total load current can also be suppressed when the specific semiconductor switch switches to intermittent current control to limit the current-carrying time.

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

According to the in-vehicle power distribution device of the present invention, new electrical equipment or new functions that were not envisaged at the time of design can be easily added and connected without unnecessarily enlarging the wires, etc., upstream of the main power supply box. For example, if a new electrical equipment consuming a large amount of power is connected downstream of the main power supply box as a load, the total load current may increase to a level approaching the current allowable value of the upstream wires. If no control is performed, for example, a fuse may cut off the circuit, or the upstream wire may become abnormally hot and emit smoke. However, since the control unit automatically adjusts the power distribution to multiple loads, it is possible to avoid an increase in the total load current. Moreover, since the power distribution is adjusted taking into account the priority of each of the multiple loads actually connected downstream of the main power supply box, it is possible to avoid limiting the function of the load with a high priority. Therefore, there is no need to modify the main power supply box to replace parts such as wires and fuses, etc., upstream of the main power supply box.

The present invention has been briefly described above. The details of the present invention will become clearer by reading the following description of the embodiment of the invention (hereinafter referred to as "embodiment") with reference to the attached drawings.

FIG. 1 is a block diagram showing an example of the configuration of an in-vehicle power distribution device according to an embodiment of the present invention. 2A and 2B are graphs showing examples of power supply characteristics in a general vehicle and the vehicle of the embodiment, respectively. FIG. 3 is a flowchart showing an example of the operation of the area ECU shown in FIG. FIG. 4 is a flowchart showing a modified example of the operation of the area ECU. FIG. 5 is a flowchart showing an example of a process for the microcomputer to grasp the priority of a load.

Specific embodiments of the present invention are described below with reference to the drawings.

Figure 1 is a block diagram showing an example of the configuration of an on-board power distribution device 100 according to an embodiment of the present invention.

The on-board power distribution device 100 shown in FIG. 1 is mainly composed of an area ECU 20. This area ECU 20 has a function for managing a specific area that is predetermined on the vehicle, and a function for supplying power to loads such as various electrical equipment connected downstream. The area managed by the area ECU 20 may be assigned to a specific region in the space on the vehicle, or may be assigned to a specific functional group.

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

In the example shown in FIG. 1, multiple upstream electric wires 11 and 12 are connected to the output of the vehicle power supply 10. Each upstream electric wire 11, 12 is equipped with an upstream fuse 13, 14. The upstream fuses 13 and 14 have the function of melting and breaking the circuit when a large current exceeding the allowable value flows through each upstream electric wire 11, 12. In other words, if a large current continues to flow through each upstream electric wire 11, 12 and abnormal heat is generated, problems such as smoke generation may occur, so the upstream fuses 13, 14 have the function of preventing this from happening.

The power input terminal 20a of the area ECU 20 is connected to the downstream side of the upstream electric wire 11. Therefore, the power supply power output by the on-board power supply 10 is supplied to the area ECU 20 via the upstream fuse 13 and the upstream electric wire 11.

The area ECU 20 has a number of signal input terminals 20b. A number of signal lines 51 are connected to these signal input terminals 20b. Therefore, signals from various sensors, switches, etc. on the vehicle are input to the area ECU 20 via the signal lines 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 path of a communication network configured according to a communication standard for vehicles, such as CAN (Controller Area Network), and enables data communication between various ECUs and other electrical equipment on the vehicle.

The output side of the area ECU 20 is provided with power output terminals 25a, 25b, 25c, ..., power output terminals 26a, 26b, 26c, ..., power output terminals 27a, 27b, ..., and a communication terminal 28.

The power output terminals 25a, 25b, 25c, ... are provided to supply the necessary power to various electrical components, such as the engine control system, the driving motor control system, the steering system, and the brake system, which are necessary for the vehicle to run. Therefore, in the example of FIG. 1, a driving system load 31A is connected to the power output terminal 25a, and a driving system load 31B is connected to the power output terminal 25b.

Power output terminals 26a, 26b, 26c, ... are provided to supply the necessary power to various electrical components of the auxiliary system that are not directly related to the running of the vehicle. For example, lamps such as headlights and turn signals, wiper devices, air conditioners, door lock devices, car navigation devices, audio devices, etc. belong to the auxiliary system. Therefore, in the example of Figure 1, auxiliary load 32A is connected to power output terminal 26a, and auxiliary load 32B is connected to power output terminal 26b.

On the other hand, the power output terminals 27a, 27b, ... and the communication terminal 28 are terminals of a backup system provided in preparation for the possibility of adding functions in the future. In the example of FIG. 1, an additional load 33A is connected to the power output terminal 27a, and an 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 potentially connected at the initial design of the vehicle. Therefore, for example, the specifications of the power current consumed by each of the additional load 33A and the additional ECU 33B are determined as necessary after the vehicle is designed.

However, it is expected that the total power supply current consumed by all the loads downstream of the area ECU 20 shown in FIG. 1 will change significantly before and after the elements of the additional function 40 are connected to the area ECU 20. This change will affect the magnitude of the current flowing through the upstream electric wire 11, and there is a possibility that a large current exceeding the allowable current of the upstream electric wire 11 will flow through the upstream electric wire 11.

In the case of a typical design, if the maximum value of the current flowing through the upstream electric wire 11 increases, the upstream electric wire 11 must be changed to a thicker electric wire in order to increase the allowable current. In addition, the specifications of the upstream fuse 13 and the terminals of each part must also be changed in accordance with the change in the allowable current and thickness of the upstream electric wire 11, necessitating large-scale modifications.

On the other hand, there are also cases where the upstream electric wires 11 are designed to have a margin in the allowable current in anticipation of an increase in the power supply current consumed by the connection of future additional functions 40. In such cases, the allowable current is set to be larger than necessary compared to the total power supply current actually consumed by the loads connected downstream of the area ECU 20, so the upstream electric wires 11, etc. become thicker and the power supply becomes larger overall.

In the on-board power distribution device 100 shown in FIG. 1, there is no need to provide more than necessary leeway in the thickness, etc., of the upstream electric wires 11, and even if an additional function 40 whose specifications, such as the power supply current it consumes, are not yet determined at the time of initial design, is connected to the area ECU 20, smoke, etc., from the upstream electric wires 11 can be prevented without special modifications. The area ECU 20 is equipped with a function for this purpose.

The area ECU 20 includes a microcomputer 21 , a communication circuit 22 , a switch unit 23 , and a non-volatile memory 24 .
1, the switch unit 23 includes a first switch unit 23a, a second switch unit 23b, and a spare switch unit 23c. In the switch unit 23, the first switch unit 23a, the second switch unit 23b, and the spare switch unit 23c include IPDs (Intelligent Power Devices) in the number equal to the number of loads that can be connected.

Each IPD incorporates a semiconductor switch (MOSFET) that switches the current flowing to the load on and off, a gate driver, a current detection function, a protection circuit, and more.

In the state shown in FIG. 1, for example, when the topmost IPD in the first switch section 23a is turned on, a power supply current is supplied from the power supply input terminal 20a through the power supply line 29, the IPD in the first switch section 23a, and the power supply output terminal 25a to the running load 31A. Also, when this IPD is turned off, the power supply to the running load 31A is cut off.

Therefore, by turning on and off each IPD in the switch unit 23, the power supply to the multiple loads connected downstream of the area ECU 20 is individually turned on and off. In addition, by periodically turning on and off the IPDs at short intervals, it is also possible to implement intermittent current control such as pulse width modulation control (PWM).

The control inputs of each IPD in the switch unit 23 are connected to the output ports of the microcomputer 21. In addition, the current information detected by each IPD in the switch unit 23 is input to the input ports of the microcomputer 21. Therefore, the microcomputer 21 can individually grasp the power supply current flowing to each load connected downstream of the area ECU 20. In addition, the microcomputer 21 can individually control the on/off of the power supply to each load connected downstream of the area ECU 20.

Although not shown in FIG. 1, each of the power output terminals 25a, 25b, 25c, ..., power output terminals 26a, 26b, 26c, ..., and power output terminals 27a, 27b, ... is provided with a connector to enable physical and electrical connection and disconnection. For the electrical equipment connected to each connector, a priority for power supply is determined in advance for each connector. In this example, three types of priority are defined: "high", "medium", and "low".

In this embodiment, as shown in FIG. 1, the connectors of the driving loads 31A and 31B have a "high" priority, the connector of the auxiliary load 32A has a "high" priority, the connector of the auxiliary load 32B has a "low" priority, and the connectors of the additional load 33A and additional ECU 33B have a "medium" priority.

However, if the specifications, including the priority, of the additional load 33A and additional ECU 33B that are to be connected later as additional functions 40 are fixed at the initial design stage, it will be difficult to connect new equipment that realizes advanced functions. Therefore, the additional ECU 33B is configured to be able to change the assigned priority by communicating with the microcomputer 21 using the communication terminal 28.

The microcomputer 21 can realize various functions required for controlling the area ECU 20 by executing pre-installed programs. For example, it can identify the situation based on the state of various signals input to the signal input terminal 20b, and can perform on/off control of each load connected downstream of the area ECU 20. The microcomputer 21 can also exchange information with other ECUs via the communication circuit 22 and communication bus 52 as necessary.

The non-volatile memory 24 can store various constant data that are determined in advance. For example, data representing the specifications of the upstream fuses 13, 14 connected to the upstream electric wires 11, 12 (e.g., 30 [A], 40 [A], etc.), data on the priority assigned to each connector on the output side of the area ECU 20, etc. are stored in advance in a predetermined storage area on the non-volatile memory 24.

Figures 2(a) and 2(b) are graphs showing examples of power supply characteristics for a typical vehicle and a vehicle according to an embodiment, respectively.

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

The boundary of the conditions under which the upstream electric wire 11 starts to emit smoke can generally be expressed by a curve such as the upstream electric wire smoke emission characteristic C0 shown in Figure 2 (a). In other words, if a larger current flows, it is possible that a smoke state will be generated even with a shorter period of current flow. In addition, if a current flows continuously for a long period of time, even an overcurrent that is slightly larger than the allowable current can cause a smoke state.

On the other hand, the characteristics of the upstream fuse 13 inserted in series with the upstream electric wire 11 can be expressed by a curve such as the upstream fuse melting characteristic C1 shown in Figure 2 (a). In other words, the design is to use a component with a characteristic (C1) that causes the upstream fuse 13 to melt and interrupt the circuit before the current (Iy) actually flowing through the upstream electric wire 11 approaches the boundary of the curve of the upstream electric wire smoke generation characteristic C0.

The specifications of the area ECU 20 and each load connected downstream are determined in advance so that the total current Iy flowing through the upstream wire 11 does not reach the boundary of the upstream fuse melting characteristic C1 shown in FIG. 2(a). For example, the maximum value of the power supply current flowing through each load is limited, or a large power supply current is limited so that it does not continue to flow for a long period of time. Therefore, as shown in the characteristic curve of the total current Iy shown in FIG. 2(a), the total current Iy actually flowing through the upstream wire 11 operates so as to be below the boundary of the upstream fuse melting characteristic C1. Therefore, a situation in which the upstream fuse 13 melts does not occur.

However, for example, 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 when the additional function 40 shown in FIG. 1 is not connected, there is a possibility that the total current value Iy will reach the upstream fuse melting characteristic C1 when the additional function 40 is connected. This will cause the upstream fuse 13 to melt. Furthermore, the melting of the upstream fuse 13 will stop all supply of power from the power source downstream of the area ECU 20, and the functions of each load connected to the area ECU 20 will also stop.

Therefore, the area ECU 20 shown in FIG. 1 has a function of controlling 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 located lower than the boundary of the curve of the upstream fuse melting characteristic C1.

In reality, the area ECU 20 controls the load side current so that the total current value Iy is limited to less than or equal to the power control characteristic C2, both before and after the additional function 40 is connected. Therefore, the total current value Iy is reduced before it approaches the boundary of the curve of the upstream fuse melting characteristic C1. This makes it possible to avoid melting of the upstream fuse 13 even if an additional function 40 that was not envisaged at the time of the initial design of the area ECU 20 is connected downstream of the area ECU 20.

Figure 3 is a flowchart showing an example of the operation of the area ECU 20 shown in Figure 1. That is, the microcomputer 21 in the area ECU 20 executes the control of each step in Figure 3 according to a program. The operation of Figure 3 will be described below.

When the area ECU is powered on, the microcomputer 21 proceeds from S11 to S12, and acquires fuse specification information D1 indicating the characteristics of the upstream fuse 13 (e.g., the current specification is 30 [A]) from the information storage section M01 in the non-volatile memory 24.

In addition, the information storage unit M02 in the non-volatile memory 24 prestores a list of fusing characteristic information that shows the relationship between the current value and fusing characteristics of fuses with various characteristics.

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

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

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

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

The microcomputer 21 constantly monitors in S17 the length of time that current flows through the IPD that controls the current supply for each load connected downstream of the area ECU 20 as the current supply time length Tx.

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

The total current value Iy and the current flow time length Ty are 0 immediately after the power supply of the area ECU is switched from off to on, and change stepwise on the graph in FIG. 2(b) as the current flow to each load is turned on and off. In addition, taking into account the heat generation and heat dissipation conditions according to the power loss occurring in the upstream electric wire 11, an appropriate current flow time length Ty is calculated based on the current flow time length Tx of each load so as to reflect the actual temperature change of the upstream electric wire 11.

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

The microcomputer 21 switches off the IPD that controls the current to the loads connected downstream of the area ECU 20 and that have a low priority as determined in S15 among the current-carrying loads, thereby cutting off the current (S21).

On the other hand, if the microcomputer 21 detects through the comparison in S19 that the latest total current value Iy and current flow duration Ty have a sufficient margin (the current is small) with respect to the power control characteristic C2, the process proceeds from S22 to S23. In that case, the microcomputer 21 releases the current cutoff to the load that was cut off in S21 in S23.

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

Therefore, even if a new additional function 40 that was not envisaged at the time of the initial design of the in-vehicle power distribution device 100 is added and connected to the area ECU 20, the upstream fuse 13 can be prevented from melting. Moreover, when the total current value Iy approaches the power control characteristic C2, only the loads with low priority are deenergized, so the functions of the loads with high priority can be maintained at all times. In addition, since the design specifications for the total current value Iy flowing through the upstream electric wire 11 and the upstream fuse 13 can be determined without considering the undetermined power supply current to be passed through the additional function 40, there is no need to thicken the upstream electric wire 11, and no changes are required when the additional function 40 is added. Furthermore, when the total current value Iy is relatively small, power supply power can be supplied even to the loads with low priority.

Figure 4 is a flowchart showing a modified operation of the area ECU 20. The operation shown in Figure 4 is a modified operation of the operation shown in Figure 3, and only steps S21A and S23A have been changed. The modified parts of the operation are described below.

In the operation of FIG. 4, the microcomputer 21 proceeds to processing of S21A when the latest total current value Iy and current flow duration Ty approach the power control characteristic C2. Then, when current is passed through a load connected downstream of the area ECU 20 and in a current-passing state that has a low priority ascertained in S15, pulse width modulation control (PWM) is performed by periodically turning the IPD on and off at short intervals (S21A). In other words, the pulse width of the current passed through the load is limited, and the effective value of the current is controlled to be smaller than normal.

On the other hand, if the microcomputer 21 detects through the comparison in S19 that the latest total current value Iy and current flow time length Ty have a sufficient margin (the current is small) with respect to the power control characteristic C2, it proceeds from S22 to S23A. In that case, the current flow control for the load that was changed to PWM control in S21A is returned to normal on/off control in S23A.

When the operation of FIG. 4 is performed, if the total current value Iy and the current flow time length Ty approach the power control characteristic C2, the power supply power supplied to the low priority load is limited, so the functionality of the low priority load is temporarily reduced, but a minimum functionality can be maintained at all times.

The operations of Figures 3 and 4 may be combined. For example, if the latest total current value Iy and current flow time length Ty approach the power control characteristic C2, initially, similar to S21A, the control of the load with low priority is shifted to PWM control, and if the total current value Iy and current flow time length Ty also approach the power control characteristic C2 under this PWM control, control is performed to completely cut off current to the corresponding load, similar to S21.

Figure 5 is a flowchart showing an example of a process in which the microcomputer 21 determines the priority of a load. That is, the details of step S15 in Figure 3 are shown in Figure 5.

In step S31, the microcomputer 21 determines the relationship between the positions of the connectors corresponding to the power output terminals 25a, 25b, 25c, ..., 26a, 26b, 26c, ..., 27a, 27b downstream of the area ECU 20 and the loads connected to those positions.

Information storage unit M03 in non-volatile memory 24 stores data in advance that indicates a list of priorities for each connector. For example, in the priority situation shown in FIG. 1, the priorities assigned to the connectors of power output terminals 25a, 25b, 26a, 26b, 27a, and 27b are "high", "high", "high", "low", "medium", and "medium", respectively.

The microcomputer 21 obtains priority information D2, which indicates the priority of the position of the connector to which each load is connected, from the information storage unit M03 of the non-volatile memory 24, and grasps the priority (S32).

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

When the microcomputer 21 is able to communicate with each load, it acquires the priority information D2 sent by each load in S33. In this embodiment, the priority information D2 of each load that the microcomputer 21 knows is overwritten by the information acquired later. Therefore, the priority of a load that cannot communicate is fixed to the priority assigned in advance to the connector position, but in the case of a load that can communicate, the priority that the microcomputer 21 knows can be changed to match the load specifications.

Of the additional functions 40 shown in FIG. 1, the spare switch unit 23c, the power output terminals 27a and 27b, the communication terminal 28, and other components may be pre-installed in the area ECU 20, or may be retrofitted to the area ECU 20 when the additional load 33A, the additional ECU 33B, and the like are added.

As described above, in the on-board power distribution device 100, even if an additional function 40 with specifications not envisaged at the time of design is later connected to the area ECU 20, the total current value Iy is controlled based on the power control characteristic C2, and the upstream fuse 13 is prevented from melting. Therefore, when connecting the additional function 40, there is no need to modify the components such as the upstream electric wire 11 and the upstream fuse 13, and an easy connection like plug and play can be realized. In addition, by preventing the upstream fuse 13 from melting, the supply of power from the source is constantly maintained for high-priority loads, and the function does not stop, so reliability can be improved. Moreover, there is no need to provide more room than necessary for the size of the components such as the upstream electric wire 11 and the upstream fuse 13, so that the components such as the upstream electric wire 11 can be avoided from becoming larger.

The present invention is not limited to the above-described embodiment, 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 as long as they can achieve the present invention, and are not limited.

Here, the features of the in-vehicle power distribution device according to the embodiment of the present invention described above will be briefly summarized and listed in the following [1] to [5].
[1] An on-board power supply (10);
A main power supply box (area ECU 20) to which a plurality of loads can be connected;
an upstream wire (11) connecting between the output of the on-board power supply and the input of the main power supply box;
a plurality of semiconductor switches (each IPD in the switch unit 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) for controlling the plurality of semiconductor switches;
Equipped with
The control unit collects information on load currents flowing through loads connected downstream of the semiconductor switches for each of the semiconductor switches (S16), and controls the semiconductor switches so as to adjust power distribution to the multiple loads connected downstream of the main power supply box in accordance with the priority of each of the multiple loads (S19 to S23) when at least the sum of the load currents (total current value Iy) approaches the current allowable value (power control characteristic C2) in the upstream electric wire.
On-vehicle power distribution device.

[2] The upstream electric wire is provided with an upstream fuse (13) that limits the current flowing through the upstream electric wire,
The current allowable value (power control characteristic C2) of the upstream electric wire is determined to be smaller than at least one of the smoke generation characteristic (C0) of the upstream electric wire and the interruption characteristic (upstream fuse melting characteristic C1) of the upstream fuse (see FIG. 2B ).
The in-vehicle power distribution device according to [1] above.

[3] The control unit has a data storage unit (non-volatile memory 24, information storage unit M01) that stores in advance fuse information (fuse specification information D1) that indicates the interruption characteristics of the upstream fuse.
The in-vehicle power distribution device according to [2] above.

[4] When the sum of the load currents approaches a current allowable value in the upstream electric wire, the control unit switches off a specific semiconductor switch connected to a path of a load having a low priority among the plurality of semiconductor switches (S21), or switches to an intermittent current supply control so as to limit a current supply time of the specific semiconductor switch (S21A).
An in-vehicle power distribution device according to any one of [1] to [3] above.

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

10: on-board power supply 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 Auxiliary switch section 24 Non-volatile memory 25a, 25b, 25c Power supply output terminal 26a, 26b, 26c Power supply output terminal 27a, 27b Power supply output terminal 28 Communication terminal 29 Power supply line 31A, 31B Running system load 32A, 32B Auxiliary system load 33A Additional load 33B Additional ECU
40 Additional function 51 Signal line 52 Communication bus 100 Vehicle-mounted power distribution device C0 Upstream electric wire smoke generation characteristics C1 Upstream fuse melting characteristics C2 Power control characteristics D1 Fuse specification information D2 Priority information Ix Current flow value Iy Total current value Tx, Ty Current flow time length M01, M02, M03 Information storage unit

Claims (5)

An on-board power supply;
A main power box that can connect multiple loads;
an upstream wire connecting an output of the vehicle power supply and an input of the main power supply box;
a plurality of semiconductor switches capable of individually controlling on/off of current flowing through each of a plurality of loads connected downstream of the main power supply box;
A control unit that controls the plurality of semiconductor switches;
Equipped with
The control unit is
acquiring, for each of the plurality of semiconductor switches, a value of a current flowing through a load connected downstream of the semiconductor switch and a length of time during which the current flows through the load, and calculating a total current value, which is a sum of currents flowing through all of the loads, based on the current value for each of the plurality of loads, and calculating a current-flow time length based on the length of time for each of the plurality of loads;
A power control characteristic is stored in advance, the power control characteristic defining a relationship between time and a current value, and having a characteristic that the current value gradually decreases as the time increases;
When the total current value approaches a current allowable value in the upstream electric wire, which is a current value obtained based on the current flow time length and the power control characteristic , the semiconductor switches are controlled to adjust power distribution to the multiple loads connected downstream of the main power supply box in accordance with the priority of each of the multiple loads so that the total current value is limited to or below the current allowable value.
On-vehicle power distribution equipment. the upstream wire includes an upstream fuse for limiting a current flowing through the upstream wire;
the current allowable value of the upstream electric wire is determined to be smaller than at least one of the smoke generation characteristic of the upstream electric wire and the interruption characteristic of the upstream fuse;
The vehicle power distribution device according to claim 1 . the control unit has a data storage unit that stores in advance fuse information indicating the interruption characteristics of the upstream fuse;
The vehicle-mounted power distribution device according to claim 2 . When the total current value approaches a current allowable value in the upstream electric wire, the control unit performs pulse width modulation control of periodically repeating on and off a specific semiconductor switch connected to a load having a relatively low priority among the plurality of semiconductor switches maintained on , and when the total current value still approaches the current allowable value in the upstream electric wire even after the execution of the pulse width modulation control, switches off the specific semiconductor switch.
The in-vehicle power distribution device according to any one of claims 1 to 3. The control unit specifies priority information of each load connected downstream of the semiconductor switch based on a position of a connector to which each load is connected or based on information acquired from each load through communication.
The in-vehicle power distribution device according to any one of claims 1 to 4.