Current path control device, and vehicle power supply system

Abstract

To provide a vehicle power supply system which reduces loss and is efficient.SOLUTION: An on-vehicle power net system 100 includes: power distribution devices 1a to 1d for distributing power to each of vehicle loads 2a to 2d; power supply trunk lines 3a to 3f for mutually connecting the power distribution devices 1a to 1d; a battery 4 and a DC / DC converter 5 capable of supplying power to each of the power distribution devices 1a to 1d through the power trunk lines 3a to 3f; and a current path control device 8 for controlling a current path when power is supplied to the power distribution devices 1a to 1d from the battery 4 and the DC / DC converter 5 in the on-vehicle power net system 100. The current path control device 8 switches the current path of the on-vehicle power net system 100, on the basis of a demand change of load currents Ia to Id flowing to the vehicle loads 2a to 2d from the power distribution devices 1a to 1d.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an apparatus for controlling a current path in a vehicle power supply system and a vehicle power supply system including the apparatus.

Background Art

[0002] In recent years, with the progress of electrification and automated driving of automobiles, the number of in-vehicle devices mounted on automobiles has been increasing. Along with this, there has been a demand for reduction of wire harnesses for power supply to each in-vehicle device and for improvement of reliability and reduction of loss in the in-vehicle power network system. However, in a conventional 12V in-vehicle power network system, a relay box and a fuse box are provided near a battery, and a method of individually connecting power cables to in-vehicle devices such as various sensors and actuators installed at various positions in the vehicle from there is often used. In such a conventional method of supplying power to in-vehicle devices, there is a problem that an enormous number of wire harnesses are required with an increase in the number of in-vehicle devices to be supplied with power and redundancy of power supply paths for reliability improvement.

[0003] Therefore, a method has been proposed in which a vehicle is divided into a plurality of zones, a power distribution device for distributing power to in-vehicle devices is arranged in each zone, and these power distribution devices are connected in a ring shape by a power main line to form a power network. By installing the power distribution device in each zone in this way, power is distributed near various sensors and actuators, so that the total extension distance of the wire harness can be shortened. In addition, by connecting the power distribution devices to each other in a ring shape, power interruption due to a failure of the power main line can be avoided.

[0004] As the background art in this technical field, the following prior art is known. Patent Document 1 describes an in-vehicle power supply system in which the output of an in-vehicle battery is branched into a plurality of power lines at a location such as a fuse unit, a path connection switch is provided that enables two power lines to be connected via a power distribution device in the previous stage, and when one power line is disconnected, the circuit of the path connection switch is closed to transmit power through a plurality of paths.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the in-vehicle power supply system described in Patent Document 1, a plurality of power lines are provided from the fuse unit to the front-stage power distribution device, and by enabling the simultaneous use of the plurality of power lines, power loss due to the power lines can be suppressed. However, in this configuration, a plurality of power lines are required for each power conversion device, and a backflow prevention diode or the like for electrically disconnecting a disconnected power line is also required. Therefore, there is room for further improvement in realizing a low-loss and efficient vehicle power supply system.

Means for Solving the Problems

[0007] The current path control device according to the present invention is provided in a vehicle power supply system including a plurality of power distribution devices that respectively distribute power to loads of a vehicle, a power main line that connects the plurality of power distribution devices to each other, and a plurality of power supply devices that can respectively supply power to the power distribution devices via the power main line, and is a device that controls a current path when supplying power from the power supply device to the power distribution device in the vehicle power supply system, and switches the current path based on a change in demand for load current flowing from the power distribution device to the load. The vehicle power supply system according to the present invention includes a current path control device, a plurality of power distribution devices that respectively distribute power to loads of a vehicle, a power main line that connects the plurality of power distribution devices to each other, and a plurality of power supply devices that can respectively supply power to the power distribution devices via the power main line.

Effects of the Invention

[0008] According to the present invention, a vehicle power supply system with low loss and high efficiency can be realized.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0011] (First Embodiment) FIG. 1 is a configuration diagram of an in-vehicle power network system according to a first embodiment of the present invention. The in-vehicle power network system 100 shown in FIG. 1 is an example of an in-vehicle power network system that forms a power grid suitable for applying the present invention, and is mounted on a vehicle such as an automobile and used. The in-vehicle power network system 100 includes power distribution devices 1a, 1b, 1c, and 1d, power supply main lines 3a, 3b, 3c, 3d, 3e, and 3f, a battery 4, a DC / DC converter 5, and a current path control device 8.

[0012] The power distribution devices 1a to 1d are respectively installed in each zone when the vehicle is divided into four zones on the front right side, front left side, rear right side, and rear left side, and power is respectively distributed to the vehicle loads 2a to 2d in each zone. The battery 4 and the DC / DC converter 5 function as power supply devices capable of supplying power to the vehicle loads 2a to 2d via the power distribution devices 1a to 1d in the in-vehicle power network system 100.

[0013] The power distribution devices 1a to 1d, the battery 4, and the DC / DC converter 5 are interconnected in a ring shape by the power supply main lines 3a to 3f. Specifically, the battery 4 and the power distribution device 1a are connected by the power supply main line 3a. The power distribution devices 1a and 1b are interconnected by the power supply main line 3b. The power distribution devices 1b and 1c are interconnected by the power supply main lines 3c and 3d. A DC / DC converter 5 is connected between the power distribution devices 1b and 1c in the power supply main lines 3c and 3d. The power distribution devices 1c and 1d are interconnected by the power supply main line 3e. The power distribution device 1d and the battery 4 are connected by the power supply main line 3f. Through these connections, a ring-shaped in-vehicle power network system 100 is formed.

[0014] The battery 4 is a rechargeable secondary battery, and supplies power to the vehicle loads 2a to 2d by discharging the charged power. As the battery 4, for example, a lead battery, a nickel-metal hydride battery, a lithium-ion battery, or the like can be used. The DC / DC converter 5 steps down the DC voltage from a high-voltage battery HV (not shown) (for example, a 400V lithium-ion battery) to a predetermined voltage, for example, 12V, and supplies the stepped-down DC power to the vehicle loads 2a to 2d respectively. The high-voltage battery HV is a battery having an output voltage higher than that of the battery 4. For example, a battery that supplies power to a driving motor of an electric vehicle or a hybrid vehicle equipped with the in-vehicle power network system 100 can be used as the high-voltage battery HV.

[0015] In FIG. 1, the battery 4 and the DC / DC converter 5 are illustrated as the power supply devices of the in-vehicle power network system 100. However, for example, an alternator that generates power by the driving force of the vehicle engine can be used instead of or in addition to the battery 4 or the DC / DC converter 5. That is, any power supply device that can generate power from different energy sources can be appropriately selected from various types of power supply devices and connected to the in-vehicle power network system 100, and can be used as a power supply device that supplies power to the vehicle loads 2a to 2d. Further, in FIG. 1, the battery 4 is connected to the power supply main lines 3a and 3f, and the DC / DC converter 5 is connected to the power supply main lines 3c and 3d. However, the power supply main lines connected to the battery 4 and the DC / DC converter 5 are not limited to this, and a configuration in which they are connected to other power supply main lines may be used.

[0016] In the in-vehicle power network system 100 shown in FIG. 1, when any one of the power main lines 3a to 3f is disconnected, the disconnected portion is disconnected, and for the vehicle loads 2a to 2d that are located ahead of the disconnected portion, power supply can be continued by detouring through another route. For example, when the power main line 3a between the battery 4 and the power distribution device 1a in FIG. 1 is disconnected, a current is made to flow from the battery 4 to the power distribution device 1a via the power main lines 3f, 3e, 3d, 3c, and 3b, and the power supplied thereby is distributed from the power distribution device 1a to the vehicle load 2a, so that the power supply to the vehicle load 2a can be continued. Also, when either the battery 4 or the DC / DC converter 5 fails, power supply to the vehicle loads 2a to 2d can be continued using the other power supply device. For example, when the battery 4 fails in FIG. 1, a current is made to flow from the DC / DC converter 5 to the power distribution device 1a via the power main lines 3c and 3b, and the power supplied thereby is distributed from the power distribution device 1a to the vehicle load 2a, so that the power supply to the vehicle load 2a can be continued. Control of the current path during power supply to the vehicle loads 2a to 2d is performed by the current path control device 8, as will be described later.

[0017] The power distribution device 1a includes a switch element 6a that electrically opens and closes the connection with the power main line 3a, and a switch element 6b that electrically opens and closes the connection with the power main line 3b. One end of the switch element 6a is connected to the power main line 3a, and the other end is connected to the switch element 6b. One end of the switch element 6b is connected to the power main line 3b, and the other end is connected to the switch element 6a. The vehicle load 2a is connected to the connection line between the switch element 6a and the switch element 6b. As the switch elements 6a and 6b, for example, semiconductor switches such as power MOSFETs and GaN transistors can be used.

[0018] In addition, the power distribution device 1a includes a current detection element 7a that detects a load current Ia flowing from the power supply main line 3a or 3b to the vehicle load 2a. The load current Ia is the sum of the currents supplied to a plurality of in-vehicle loads connected to the power distribution device 1a. This load current Ia is transmitted to the current path control device 8. The current path control device 8 detects a change in the load current Ia as a change in current demand in the power distribution device 1a. The change in current demand is information indicating a change in the load current due to the driving or stopping of the loads connected to the power distribution device. Similarly, current detection elements 7b to 7d are provided in the other power distribution devices 1b to 1d, and the load currents Ib to Id of the respective power distribution devices are transmitted to the current path control device 8. The current path control device 8 detects changes in the load currents Ib to Ic as changes in current demand in the respective power distribution devices. As the current detection element 7a, for example, a shunt resistor or a Hall element can be used. Also, in this embodiment, a configuration in which one current detection element is provided for a plurality of loads is shown, but the configuration is not limited to this. For example, a configuration in which a current detection element is provided for each load connected to the power distribution device, and the load current is obtained from the sum of the currents detected by each current detection element may also be used.

[0019] The other power distribution devices 1b to 1d also have the same configuration as the power distribution device 1a. That is, the power distribution device 1b includes a switch element 6c that electrically opens and closes the connection to the power supply main line 3b, a switch element 6d that electrically opens and closes the connection to the power supply main line 3c, and a current detection element 7b that detects a load current Ib flowing from the power supply main line 3b or 3c to the vehicle load 2b. The power distribution device 1c includes a switch element 6e that electrically opens and closes the connection to the power supply main line 3d, a switch element 6f that electrically opens and closes the connection to the power supply main line 3e, and a current detection element 7c that detects a load current Ic flowing from the power supply main line 3d or 3e to the vehicle load 2c. The power distribution device 1d includes a switch element 6g that electrically opens and closes the connection to the power supply main line 3e, a switch element 6h that electrically opens and closes the connection to the power supply main line 3f, and a current detection element 7d that detects a load current Id flowing from the power supply main line 3e or 3f to the vehicle load 2d.

[0020] The in-vehicle power network system 100 of this embodiment further includes a current path control device 8. The current path control device 8 respectively acquires information on the load currents Ia to Id from the power distribution devices 1a to 1d, and based on the acquired information on the load currents Ia to Ib, determines the opening and closing patterns of the switch elements 6a to 6h provided in the power distribution devices 1a to 1d. Information on the opening and closing patterns of each switch element determined by the current path control device 8 is transmitted to each power distribution device as switch information Sa to Sd. In the power distribution devices 1a to 1d, based on the received switch information Sa to Sd, the switch elements provided in each power distribution device are respectively opened and closed according to the opening and closing patterns determined by the current path control device 8. Note that the transmission and reception of information on the load currents Ia to Ib and the switch information Sa to Sd between the current path control device 8 and each power distribution device are performed via communication lines 9a to 9d. For the transmission and reception of this information via the communication lines 9a to 9d, communication standards such as CAN (Controller Area Network) or Ethernet (registered trademark) can be used, for example.

[0021] FIG. 2 is a diagram showing an example of a change in the current path in the in-vehicle power network system according to the first embodiment of the present invention. FIG. 2(a) shows an example of the state of the current path before the switch information Sa to Sd is transmitted from the current path control device 8 to the power distribution devices 1a to 1d. In this state, the load current Id is supplied from the battery 4 to the vehicle load 2d connected to the power distribution device 1d via the power supply main line 3f. Also, the load current Ic is supplied from the battery 4 to the vehicle load 2c connected to the power distribution device 1c via the power supply main line 3f and the power supply main line 3e. At this time, since both the load current Ic and the load current Id pass through the power supply main line 3f, the current is concentrated in this power supply main line 3f and the transmission loss has increased.

[0022] In the state of Fig. 2(a), the current path control device 8 acquires information on the load currents Ia to Id from the power distribution devices 1a to 1d respectively, and for each opening / closing pattern of the switch elements 6a to 6h, determines the magnitude of the current flowing through the main power lines 3a to 3f according to the load currents Ia to Id for each opening / closing pattern. Then, based on the obtained current values of the main power lines 3a to 3f for each opening / closing pattern and the preset conductor resistance values of the main power lines 3a to 3f, the total value of the power losses (transmission losses) occurring in the main power lines 3a to 3f is calculated for each opening / closing pattern. Based on this calculation result, the pattern with the smallest power loss among the opening / closing patterns of the switch elements 6a to 6h is selected, and the switch information Sa to Sd is transmitted to the power distribution devices 1a to 1d according to the selected opening / closing pattern. Thereby, the current path control device 8 can perform the opening / closing control of the switch elements 6a to 6h so that the current concentration occurring in the main power lines 3a to 3f is dispersed, and switch the current path.

[0023] Note that when the current path control device 8 determines the current values of the main power lines 3a to 3f for each opening / closing pattern of the switch elements 6a to 6h, it is not always necessary to determine the current values for all the opening / closing patterns. For example, for combinations of switch elements such as switch elements 6b and 6c, and switch elements 6f and 6g, where current does not flow through the corresponding main power lines 3b and 3e by turning either one of them OFF, it is not necessary to calculate the current values of the opening / closing patterns of such combinations repeatedly. Also, in the state of Fig. 2(a), since the load currents Ia and Ib respectively distributed from the power distribution devices 1a and 1b to the vehicle loads 2a and 2b are 0, there is no need to flow current through the main power lines 3a to 3c connected to the power distribution devices 1a and 1b. Thus, for the opening / closing patterns of the switch elements 6a to 6d connected to the main power lines 3a to 3c with 0 current, they may be excluded from the calculation targets of the current values. Furthermore, for opening / closing patterns where it is obvious that the power loss increases compared to the original state, such as when the current path is clearly longer compared to Fig. 2(a), the calculation of the current values may be omitted. In addition to the above, it is possible to limit the opening / closing patterns of the switch elements 6a to 6h that are the calculation targets of the current values by any method.

[0024] The current path control device 8 selects, as the pattern with the smallest power loss, an opening / closing pattern in which, for example, the switch elements 6e and 6h are turned ON and the switch elements 6f and 6g are turned OFF with respect to the load currents Ic and Id by the above-described processing. At this time, the current path control device 8 outputs switch information Sc for switching the switch element 6e to ON and the switch element 6f to OFF to the power distribution device 1c, and outputs switch information Sd for switching the switch element 6g to OFF and the switch element 6h to ON to the power distribution device 1d. These switch information Sc and Sd are respectively transmitted from the current path control device 8 to the power distribution devices 1c and 1d via the communication lines 9c and 9d (see FIG. 1).

[0025] The power distribution device 1c that has received the switch information Sc switches the switch element 6e to ON and the switch element 6f to OFF according to the opening / closing pattern indicated by the switch information Sc. Further, the power distribution device 1d that has received the switch information Sd switches the switch element 6g to OFF and the switch element 6h to ON according to the opening / closing pattern indicated by the switch information Sd. As a result, the state of the current path changes from FIG. 2(a) to FIG. 2(b). At this time, in the power distribution device 1c, the current supplied from the DC / DC converter 5 via the power supply main line 3d is distributed as the load current Ic to the vehicle load 2c. Also, in the power distribution device 1d, the current supplied from the battery 4 via the power supply main line 3f is distributed as the load current Id to the vehicle load 2d. As a result, in the state of FIG. 2(a) before switching the current path, current concentration occurred in the power supply main line 3f, but in the state of FIG. 2(b) after switching the current path, the current is dispersed between the power supply main line 3f and the power supply main line 3d, and transmission loss and temperature rise are reduced.

[0026] In the in-vehicle power network system 100 of this embodiment, the current path control device 8 performs switching control of the current path based on the conductor resistance values of the power main lines 3a to 3f and the demand changes of the load currents Ia to Id flowing from the power distribution devices 1a to 1d to the vehicle loads 2a to 2d as described above, so that the currents flowing through the power main lines 3a to 3f are dispersed. Thereby, the transmission loss in the entire in-vehicle power network system 100 can be reduced, and a local temperature rise due to current concentration can be avoided.

[0027] FIG. 3 is a diagram showing the functional configurations of the power distribution device and the current path control device according to the first embodiment of the present invention. As shown in FIG. 3, the power distribution devices 1a to 1d of this embodiment respectively detect the values of the load currents Ia to Ib distributed to the vehicle loads 2a to 2d, and transmit information indicating the detection results to the current path control device 8. Further, the current path control device 8 of this embodiment includes functional blocks of a path calculation unit 10 and an update determination unit 20. In the current path control device 8, these functional blocks are realized, for example, when a CPU executes a predetermined program.

[0028] In the current path control device 8 of this embodiment, the path calculation unit 10 has a current path selection unit 11. The current path selection unit 11 selects a current path based on the information of the load currents Ia to Id acquired from the power distribution devices 1a to 1d. The path calculation unit 10 stores network configuration information 12 indicating the connection relationship of the power distribution devices 1a to 1d, the battery 4, and the DC / DC converter 5 by the power main lines 3a to 3f in the in-vehicle power network system 100, and network parameter information 13 indicating the conductor resistance values of the power main lines 3a to 3f. The current path selection unit 11 selects a current path in which the current is dispersed in the in-vehicle power network system 100 based on the information of the load currents Ia to Id and this information stored in advance in the path calculation unit 10. Specifically, for example, as described above, for each opening / closing pattern of the switch elements 6a to 6h, the power loss due to the power main lines 3a to 3f in the entire in-vehicle power network system 100 that satisfies the load currents Ia to Id is calculated, and the opening / closing pattern with the smallest loss is selected, thereby determining the current path.

[0029] The update determination unit 20 monitors the information of the load currents Ia to Id transmitted from the power distribution devices 1a to 1d every predetermined time. When a variation equal to or greater than a predetermined value occurs in at least one of the load currents Ia to Id, it is determined that there has been a demand change in the corresponding load current, and an update instruction for the current path is sent to the path calculation unit 10. In response to this update instruction, the path calculation unit 10 performs the calculation of the current path, the subsequent current path is determined by the current path selection unit 11, and the switch information Sa to Sd is respectively transmitted from the current path control device 8 to the power distribution devices 1a to 1d.

[0030] FIG. 4 is a timing chart showing an example of the timing at which the update determination unit 20 issues an update instruction for the current path to the path calculation unit 10. In each of the timing charts of FIGS. 4(a) to 4(d), the relationship between the time change of the load currents Ia, Ib, Ic, Id and the update instruction timing of the current path is exemplified in order from the top.

[0031] When the current path control device 8 is activated in the in-vehicle power network system 100, the update determination unit 20 acquires the information of the load currents Ia to Id from the power distribution devices 1a to 1d and monitors the states of the load currents Ia to Id. As a result, as shown in FIG. 4(d), for example, a variation occurs in the load current Id at time t1, and it is assumed that the amount of variation (the change width of the current value per unit time) at this time is equal to or greater than a predetermined threshold Ith. In this case, the update determination unit 20 determines that time t1 is the update timing of the current path and outputs an update instruction to the path calculation unit 10.

[0032] On the other hand, as shown in FIG. 4(c), for example, a variation occurs in the load current Ic at time t2, and it is assumed that the amount of variation at this time is less than the threshold Ith. In this case, the update determination unit 20 determines that time t2 is not the update timing of the current path and does not output an update instruction to the path calculation unit 10.

[0033] Also, as shown in Fig. 4(a), for example, fluctuations in the load current Ia occur at times t3, t5, and t6, and it is assumed that the amounts of these fluctuations are all equal to or greater than the threshold value Ith. In this case, the update determination unit 20 determines that it is the update timing of the current path at each time, and outputs an update instruction to the path calculation unit 10. Similarly, as shown in Fig. 4(b), for example, fluctuations in the load current Ib occur at times t4 and t7, and it is assumed that the amounts of these fluctuations are all equal to or greater than the threshold value Ith. In this case, the update determination unit 20 determines that it is the update timing of the current path at each time, and outputs an update instruction to the path calculation unit 10.

[0034] When an update instruction is input from the update determination unit 20 by the update determination as described above, the path calculation unit 10 calculates the total power loss in the power main lines 3a to 3f based on the information of the load currents Ia to Id. As a result, if the power loss can be reduced by switching the current path, switch information Sa to Sd is transmitted to each power distribution device, and the current path is switched. That is, the current path control device 8 of the present embodiment includes the update determination unit 20, so that it is determined that the current path needs to be updated at the timing when the amount of change in the load currents Ia to Id flowing from the power distribution devices 1a to 1d to the vehicle loads 2a to 2d becomes equal to or greater than a predetermined value, and the path calculation unit 10 executes the calculation process of the current path. Therefore, since it is not necessary to constantly execute the calculation process of the path calculation unit 10, the processing load and power consumption of the CPU in the current path control device 8 can be reduced.

[0035] According to the first embodiment of the present invention described above, the following operational effects are achieved.

[0036] (1) The current path control device 8 is provided in the in-vehicle power network system 100 which is a vehicle power system including power distribution devices 1a to 1d that respectively distribute power to vehicle loads 2a to 2d, power supply main lines 3a to 3f that connect the power distribution devices 1a to 1d to each other, and a plurality of power supply devices (battery 4 and DC / DC converter 5) that can respectively supply power to the power distribution devices 1a to 1d via the power supply main lines 3a to 3f. The current path control device 8 controls the current path when power is supplied from the battery 4 and the DC / DC converter 5 to the power distribution devices 1a to 1d in the in-vehicle power network system 100. The current path control device 8 switches the current path of the in-vehicle power network system 100 based on the demand change of the load currents Ia to Id flowing from the power distribution devices 1a to 1d to the vehicle loads 2a to 2d. By doing so, the in-vehicle power network system 100 as a vehicle power system with low loss and high efficiency can be realized.

[0037] (2) The current path control device 8 includes an update determination unit 20 that determines whether or not to update the current path, and a path calculation unit 10 that calculates the switched current path. The path calculation unit 10 calculates the switched current path when the update determination unit 20 determines that the current path needs to be updated. By doing so, it is not necessary to always execute the processing of the path calculation unit 10, and as a result, the processing load and power consumption of the CPU in the current path control device 8 can be reduced.

[0038] (3) The update determination unit 20 determines whether or not to update the current path based on the amount of change in the load currents Ia to Id. By doing so, it is possible to surely determine the timing when the current path needs to be updated.

[0039] (Second Embodiment) Next, a second embodiment of the present invention will be described. In this embodiment, in the current path control device 8, an example will be described in which the current path is changed so as to reduce the transmission loss in the in-vehicle power network system 100 as a whole in consideration of the ambient temperature in a state where each power distribution device is mounted on the vehicle. Note that the configuration of the in-vehicle power network system 100 in this embodiment is the same as that in the first embodiment. Therefore, hereinafter, the configuration diagram of FIG. 1 described in the first embodiment will be used as the configuration diagram of the in-vehicle power network system 100 according to this embodiment to describe this embodiment.

[0040] FIG. 5 is a diagram showing the functional configurations of the power distribution devices and the current path control device according to the second embodiment of the present invention. As shown in FIG. 5, the power distribution devices 1a to 1d in this embodiment respectively detect the values of the load currents Ia to Id distributed to the vehicle loads 2a to 2d, and transmit information indicating the detection results to the current path control device 8. At the same time, the power distribution devices 1a to 1d respectively detect the temperature at the locations where they are installed as the ambient temperatures Ta to Td in the vehicle, and transmit information indicating the detection results to the current path control device 8. The current path control device 8 in this embodiment includes functional blocks of a path calculation unit 10 and an update determination unit 20. In the current path control device 8, these functional blocks are realized, for example, when a CPU executes a predetermined program.

[0041] In the current path control device 8 of this embodiment, the path calculation unit 10 further includes a wire temperature calculation unit 14 in addition to the current path selection unit 11. The wire temperature calculation unit 14 estimates and calculates the temperature of the power supply main lines 3a to 3f for each opening / closing pattern of the switch elements 6a to 6h based on the information of the load currents Ia to Id and the ambient temperatures Ta to Td acquired from the power distribution devices 1a to 1d. Specifically, for example, the wire temperature Twb of the power supply main line 3b connecting between the power distribution device 1a and the power distribution device 1b can be calculated by the following formula (1). Twb = kb·Iab 2 +Tab ···(1)

[0042] In the above formula (1), the first term on the right side represents the temperature rise due to Joule heat when the current Iab flows through the power supply main line 3b. Here, the constant kb is a constant corresponding to the conductor resistance value of the power supply main line 3b, which is determined by the thickness and material of the electric wire. Also, Tab in the second term on the right side is a value indicating the ambient temperature at the location where the power supply main line 3b is laid within the vehicle. Since the power supply main line 3b is connected between the power distribution devices 1a and 1b, the value of Tab is determined by the ambient temperatures Ta and Tb obtained from these power distribution devices. As an example, the higher of the ambient temperature Ta and the ambient temperature Tb can be selected as Tab. The above formula (1) can also be used for calculation of other power supply main lines.

[0043] Based on the temperatures of the power supply main lines 3a to 3f calculated by the wire temperature calculation unit 14, the network configuration information 12, and the network parameter information 13, the current path selection unit 11 selects a current path so as to reduce the current of the power supply main line with the highest temperature among the power supply main lines 3a to 3f. That is, based on the conductor resistances of the power supply main lines 3a to 3f indicated by the network parameter information 13, the ambient temperatures Ta to Td, and the demand changes of the load currents Ia to Id flowing from the power distribution devices 1a to 1d to the vehicle loads 2a to 2d, a current path is selected such that the current is dispersed within the in-vehicle power network system 100.

[0044] Similar to the first embodiment, the update determination unit 20 monitors the information of the load currents Ia to Id every predetermined time, and when a variation of a predetermined value or more occurs in at least any one of the load currents Ia to Id, gives an update instruction of the current path to the path calculation unit 10. In response to this update instruction, the path calculation unit 10 performs the calculation of the current path.

[0045] According to the second embodiment of the present invention described above, the current path control device 8 switches the current path of the in-vehicle power network system 100 so that the current flowing through the power supply main lines 3a to 3f is dispersed based on the conductor resistance of the power supply main lines 3a to 3f, the ambient temperatures Ta to Td in the state where the power distribution devices 1a to 1d are mounted on the vehicle, and the demand changes of the load currents Ia to Id. Specifically, the temperature of each power supply main line is calculated based on the conductor resistance of the power supply main lines 3a to 3f and the ambient temperatures Ta to Td, and the current path of the in-vehicle power network system 100 is switched so as to reduce the current of the power supply main line having the highest temperature among the power supply main lines 3a to 3f. By doing so, the current can be dispersed so that the temperatures of the power supply main lines 3a to 3f do not exceed the allowable temperature. As a result, power can be distributed from the power distribution devices 1a to 1d to the vehicle loads 2a to 2d so as to reduce the deterioration of the electric wires caused by the high temperature of the power supply main lines 3a to 3f.

[0046] Generally, inside a vehicle, the ambient temperature varies greatly from place to place due to the influence of other devices present around it. For example, the ambient temperature tends to be high under the front hood where the power train is located, and the ambient temperature tends to be low (or high) in the passenger compartment where the air conditioner is installed. Also, the ambient temperature inside the vehicle varies greatly depending on the driving state such as whether the vehicle is running or stopped. Therefore, in order to appropriately manage the temperature state of the power supply main lines 3a to 3f, it is necessary to consider the ambient temperature at the location where each power supply main line is arranged. According to the present embodiment, since the temperature of the power supply main lines 3a to 3f can be accurately estimated in consideration of the ambient temperature by the processing described above, it is possible to surely suppress the wire temperature of the power supply main lines 3a to 3f from becoming high due to current concentration.

[0047] In this embodiment, for example, temperature sensors are respectively provided in the power distribution devices 1a to 1d, and the ambient temperatures Ta to Td around the power distribution devices 1a to 1d detected by these temperature sensors are used to obtain the ambient temperature of the location where the power supply main lines 3a to 3f are arranged. In addition to this, if the ambient temperature of the location where the power supply main lines 3a to 3f are installed can be obtained, other methods can also be used. For example, it is also possible to use an outside air temperature sensor or a temperature sensor mounted on the air conditioner in the vehicle interior as a method for estimating the ambient temperature of the power supply main lines 3a to 3f.

[0048] (Third Embodiment) Next, a third embodiment of the present invention will be described. In this embodiment, an example of determining the update timing of the current path in the current path control device 8 based on the operating states of the vehicle loads 2a to 2d will be described. Note that the configuration of the in-vehicle power network system 100 in this embodiment is the same as that in the first embodiment. Therefore, hereinafter, the configuration diagram of FIG. 1 described in the first embodiment will be used as the configuration diagram of the in-vehicle power network system 100 according to this embodiment to explain this embodiment.

[0049] FIG. 6 is a diagram showing the functional configurations of the power distribution device and the current path control device according to the third embodiment of the present invention. As shown in FIG. 6, the power distribution devices 1a to 1d in this embodiment respectively detect the values of the load currents Ia to Id distributed to the vehicle loads 2a to 2d, and transmit information indicating the detection results to the current path control device 8. Further, load switches 15 are respectively provided between each load element constituting the vehicle loads 2a to 2d, and the presence or absence of power supply to each load element is switched by controlling the ON / OFF state of the load switch 15. The power distribution devices 1a to 1d in this embodiment transmit load operation information indicating the ON / OFF state of each load switch 15 to the current path control device 8. The current path control device 8 in this embodiment includes functional blocks of a path calculation unit 10 and an update determination unit 20. In the current path control device 8, these functional blocks are realized, for example, by a CPU executing a predetermined program.

[0050] In the current path control device 8 of the present embodiment, the update determination unit 20 monitors whether there is a change in the open / closed state of any of the load switches 15 based on the load operation information transmitted from the power distribution devices 1a to 1d. As a result, if there is a change in the open / closed state of any of the load switches 15, it is determined that the operations of the vehicle loads 2a to 2d have changed and a change in current demand has occurred, and an update instruction for the current path is issued to the path calculation unit 10. In response to this update instruction, the path calculation unit 10 performs the calculation of the current path, the subsequent current path is determined by the current path selection unit 11, and the switch information Sa to Sd is transmitted from the current path control device 8 to the power distribution devices 1a to 1d, respectively.

[0051] Since the load currents Ia to Id change according to the operating states of the vehicle loads 2a to 2d, even by using the load operation information indicating the ON / OFF states of the load switches 15 in the power distribution devices 1a to 1d as described above, it is possible to detect changes in the load currents Ia to Id. Therefore, in the current path control device 8 of the present embodiment, the update determination unit 20 acquires the load operation information indicating the operating states of the vehicle loads 2a to 2d connected to the power distribution devices 1a to 1d, and uses this to determine whether it is necessary to update the current path.

[0052] In the current path control device 8 of the present embodiment, when the update determination unit 20 performs the above processing, similar to the first embodiment, the path calculation is executed in the path calculation unit 10 at the timing when the current states of the power supply main lines 3a to 3f change. Therefore, it is not necessary to constantly execute the calculation process of the path calculation unit 10, and the processing load and power consumption of the CPU in the current path control device 8 can be reduced. Also, by using the load operation information, circuit elements such as sensors for acquiring the values of the load currents Ia to Id in the power distribution devices 1a to 1d become unnecessary, and the update determination of the current path can be implemented with a simpler configuration.

[0053] According to the third embodiment of the present invention described above, the update determination unit 20 determines whether it is necessary to update the current path based on the operating states of the vehicle loads 2a to 2d. By doing so, it is possible to determine the timing when the current path needs to be updated with a simpler configuration compared to the first embodiment.

[0054] (Fourth Embodiment) Next, a fourth embodiment of the present invention will be described. In this embodiment, an example of determining the update timing of the current path based on the output current of the power supply device that supplies power to the vehicle loads 2a to 2d in the current path control device 8 will be described. Note that the configuration of the in-vehicle power network system 100 in this embodiment is the same as that in the first embodiment. Therefore, hereinafter, the configuration diagram of FIG. 1 described in the first embodiment will be used as the configuration diagram of the in-vehicle power network system 100 according to this embodiment to describe this embodiment.

[0055] FIG. 7 is a diagram showing the functional configurations of the power distribution device and the current path control device according to the fourth embodiment of the present invention. As shown in FIG. 7, the current path control device 8 in this embodiment acquires current information Ibt and Idc indicating the output currents from the battery 4 (power supply device 1) and the DC / DC converter 5 (power supply device 2), which are the power supply devices of the in-vehicle power network system 100, respectively. The current information Ibt can be acquired, for example, from a current sensor provided in the battery 4. Also, the current information Idc can be acquired, for example, from a current sensor provided inside the DC / DC converter 5 or at the output section of the DC / DC converter 5. The current path control device 8 includes functional blocks of a path calculation unit 10 and an update determination unit 20. In the current path control device 8, these functional blocks are realized, for example, by a CPU executing a predetermined program.

[0056] In the current path control device 8 of the present embodiment, the update determination unit 20 monitors the fluctuations in the current values indicated by the current information Ibt and the current information Idc based on the current information Ibt and the current information Idc. As a result, when there is a change in the current information Ibt or the current information Idc, it is determined that there has been a change in the current demand at each power distribution device, and an update instruction for the current path is issued to the path calculation unit 10. In response to this update instruction, the path calculation unit 10 performs the calculation of the current path, the subsequent current path is determined by the current path selection unit 11, and the switch information Sa to Sd is respectively transmitted from the current path control device 8 to the power distribution devices 1a to 1d.

[0057] Since the output currents of the battery 4 and the DC / DC converter 5 change depending on the operating states of the vehicle loads 2a to 2d, even by using the current information Ibt and the current information Idc, the changes in the load currents Ia to Id can be detected. Therefore, in the current path control device 8 of the present embodiment, the update determination unit 20 acquires the current information Ibt and the current information Idc indicating the magnitudes of the output currents of the battery 4 and the DC / DC converter 5 respectively, and determines whether or not to update the current path using this information. Since there are a discharge state and a charge state in the battery 4, it is preferable that the discharge state and the charge state are represented by different values in the current information Ibt. In this way, the update determination unit 20 can detect the timing at which the charge / discharge state of the battery 4 switches from the discharge state to the charge state or from the charge state to the discharge state respectively, and issue an update instruction to the path calculation unit 10 according to that timing. The charge / discharge state of the battery 4 can be determined, for example, by detecting the method of current flow using a current sensor provided in the battery 4.

[0058] In the current path control device 8 of the present embodiment, when the update determination unit 20 performs the above processing, similar to the first embodiment, path calculation is executed in the path calculation unit 10 at the timing when the current states of the power supply main lines 3a to 3f change. Therefore, it is not necessary to constantly execute the calculation process of the path calculation unit 10, and the processing load and power consumption of the CPU in the current path control device 8 can be reduced. Further, by using the current information Ibt and Idc output from the battery 4 and the DC / DC converter 5 which are power supply devices, circuit elements such as sensors for obtaining the values of the load currents Ia to Id in the power distribution devices 1a to 1d become unnecessary, and the update determination of the current path can be implemented with a simpler configuration.

[0059] According to the fourth embodiment of the present invention described above, the update determination unit 20 determines whether it is necessary to update the current path based on the fluctuations in the current values of the battery 4 and the DC / DC converter 5 which are power supply devices. By doing so, it is possible to determine the timing when it is necessary to update the current path with a simpler configuration compared to the first embodiment.

[0060] (Fifth Embodiment) Next, a fifth embodiment of the present invention will be described. In this embodiment, an example of determining the update timing of the current path based on the vehicle driving plan information acquired from the outside in the current path control device 8 will be described. Note that the configuration of the in-vehicle power network system 100 in this embodiment is the same as that of the first embodiment. Therefore, hereinafter, the configuration diagram of FIG. 1 described in the first embodiment will be used as the configuration diagram of the in-vehicle power network system 100 according to this embodiment to describe this embodiment.

[0061] FIG. 8 is a diagram showing the functional configuration of the power distribution device and the current path control device according to the fifth embodiment of the present invention. As shown in FIG. 8, the current path control device 8 of the present embodiment acquires the driving plan information of the vehicle from a driving plan device 16 installed inside or outside the vehicle. The driving plan device 16 is, for example, a car navigation device or an automatic driving control device, and outputs information such as the road on which the vehicle will travel and the driving speed as the driving plan information. The current path control device 8 includes functional blocks of a path calculation unit 10 and an update determination unit 20. In the current path control device 8, these functional blocks are realized, for example, when a CPU executes a predetermined program.

[0062] In the current path control device 8 of the present embodiment, the update determination unit 20 predicts the future movement of the vehicle based on the driving plan information acquired from the driving plan device 16, and estimates the operating states of the vehicle loads 2a to 2d according to the prediction result. Thereby, the change timing of the load currents Ia to Id according to the operating states of the vehicle loads 2a to 2d is predicted, and in accordance with this change timing, an update instruction for the current path is issued to the path calculation unit 10. Specifically, for example, by predicting the timing at which steering operations, brake operations, etc. of the vehicle are performed in accordance with the curve of the road from the curvature of the road, the driving distance to the curve, the driving speed of the vehicle, etc. included in the driving plan information, the change timing of the load currents Ia to Id can be predicted, and an update instruction for the current path can be issued. In response to this update instruction, the path calculation unit 10 performs the calculation of the current path, the subsequent current path is determined by the current path selection unit 11, and the switch information Sa to Sd is transmitted from the current path control device 8 to the power distribution devices 1a to 1d, respectively.

[0063] Since the operating states of the vehicle loads 2a to 2d change according to the driving state of the vehicle, by using the driving plan information of the vehicle, it is possible to predict changes in the future load currents Ia to Id. Therefore, in the current path control device 8 of the present embodiment, the update determination unit 20 acquires the driving plan information of the vehicle from the driving plan device 16, and predicts the change timing of the load current using this information, thereby determining whether or not to update the current path. As a result, when the current states of the power supply main lines 3a to 3f change, the path calculation of the path calculation unit 10 is executed, so it is not necessary to constantly execute the calculation process of the path calculation unit 10, and the processing load and power consumption of the CPU in the current path control device 8 can be reduced. Also, since the current path can be selected and prepared before the load currents Ia to Id actually change, it is possible to reduce the power loss due to the switching delay of the current path.

[0064] According to the fifth embodiment of the present invention described above, the update determination unit 20 predicts the change timing of the load currents Ia to Id based on the driving plan information of the vehicle transmitted from the driving plan device 16, and determines whether or not to update the current path at the change timing. By doing so, it is possible to predict in advance the timing when the update of the current path is necessary.

[0065] In addition, in each of the first to fifth embodiments described above, the following modification examples may be applied.

[0066] (Modification Example 1) In each of the first to fifth embodiments, as shown in FIG. 1, an application example to an in-vehicle power network system 100 having a system configuration in which four power distribution devices 1a to 1d are interconnected in a ring shape has been described. However, when applying the present invention, the system configuration is not limited thereto. For example, as shown in FIG. 9(a), in an in-vehicle power network system 100a having a system configuration in which the power distribution device 1a is connected to the power distribution devices 1b and 1c by power supply main lines 3b and 3c, respectively, and the power distribution device 1d is connected to the power distribution devices 1b and 1c by power supply main lines 3d and 3e, respectively, the present invention can also be applied. Further, for example, as shown in FIG. 9(b), in an in-vehicle power network system 100b having a system configuration in which two power distribution devices 1a and 1b respectively connected to the battery 4 and the DC / DC converter 5 are interconnected by a power supply main line 3b, the present invention can be applied. In addition to this, the present invention can be applied to any system configuration as long as it is a vehicle power system in which a plurality of power distribution devices and a plurality of power supply devices mounted on a vehicle are interconnected by power supply main lines.

[0067] (Modification Example 2) Also, in each of the first to fifth embodiments, as shown in FIG. 1, an example of obtaining the load currents Ia to Id by the current detection elements 7a to 7d respectively installed immediately before the branch points of the power supply lines from the power distribution devices 1a to 1d to the load elements of the vehicle loads 2a to 2d has been described. However, the method of obtaining the load currents Ia to Id is not limited thereto. For example, as shown in FIG. 10, in the power distribution device 1a, a current detection element 7e for detecting the current Iin flowing through the power supply main line 3a and a current detection element 7f for detecting the current Iout flowing through the power supply main line 3b are provided, and a method of calculating the load current Ia flowing to the vehicle load 2a from the difference Iin - Iout between these currents may be adopted. In addition to this, the load currents Ia to Id can be obtained by any method.

[0068] As described above, the in-vehicle power network system to which the present invention is applied can realize a vehicle power supply system with low loss and high efficiency. Further, when damage occurs in any of the power main lines, it is possible to secure a power supply path using other power main lines and continue the maximum power supply without exceeding the allowable current of the power main line. Furthermore, even when the required current increases due to replacement with updated in-vehicle devices or addition of new in-vehicle devices, by selecting an appropriate power supply path according to the increase in the required current, it is possible to operate using the existing power supply network without replacing the power distribution device. Therefore, by standardizing the design of the power supply network in multiple vehicle models, it is also possible to reduce the man-hours required to optimize the arrangement of various vehicle loads and wiring within the vehicle for each vehicle model.

[0069] Note that the present invention is not limited to the various embodiments and modifications described above, and includes various other modifications. For example, the above-described embodiments are specifically described in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of one embodiment can be replaced with a part of the configuration of another embodiment. Also, the configuration of another embodiment can be added to the configuration of one embodiment. Also, for a part of the configuration of each embodiment, it can be deleted, a part of another configuration can be added, and a part of another configuration can be replaced.

[0070] The present invention is not limited to the above-described embodiments, and various changes can be made without departing from the spirit of the present invention.

Explanation of Reference Numerals

[0071] 1a to 1d ··· Power distribution devices, 2a to 2d ··· Vehicle loads, 3a to 3f ··· Power main lines, 4 ··· Battery, 5 ··· DC / DC converter, 6a to 6h ··· Switch elements, 7a to 7f ··· Current detection elements, 8 ··· Current path control device, 9a~9d ··· Communication lines, 10 ··· Path calculation unit, 11 ··· Current path selection unit, 12 ··· Network configuration information, 13 ··· Network parameter information, 14 ··· Wire temperature calculation unit, 15 ··· Load switch, 16 ··· Travel plan device, 20 ··· Update determination unit, 100~100b ··· In-vehicle power network system, Ia~Ib ··· Load current, Sa~Sd ··· Switch information, Ta~Td ··· Ambient temperature.

Claims

1. A vehicle power system comprising a plurality of power distribution devices that respectively distribute power to loads of a vehicle, a power supply main line that connects the plurality of power distribution devices to each other, and a plurality of power supply devices that can respectively supply power to the power distribution devices via the power supply main line, and a device that controls a current path when power is supplied from the power supply device to the power distribution device in the vehicle power system, a current path control device that switches the current path based on a change in demand for a load current flowing from the power distribution device to the load.

2. In the current path control device according to Claim 1, a current path control device that switches the current path so that the current flowing through the power supply main line is dispersed based on the conductor resistance of the power supply main line, the ambient temperature in a state where the power distribution device is mounted on the vehicle, and the change in demand for the load current.

3. In the current path control device according to Claim 2, a current path control device that calculates the temperature of each power supply main line based on the conductor resistance and the ambient temperature, and switches the current path so as to reduce the current of the power supply main line having the highest temperature among the plurality of power supply main lines.

4. In the current path control device according to Claim 1, an update determination unit that determines whether or not to update the current path, and a path calculation unit that calculates the switched current path, wherein the path calculation unit calculates the switched current path when the update determination unit determines that the current path needs to be updated.

5. In the current path control device according to Claim 4, the update determination unit is a current path control device that determines whether or not to update the current path based on the amount of change in the load current.

6. In the current path control device according to Claim 4, the update determination unit is a current path control device that determines whether or not to update the current path based on the operating state of the load.

7. In the current path control device according to Claim 4, the update determination unit is a current path control device that determines whether or not to update the current path based on a change in the current value of the power supply device.

8. In the current path control device according to Claim 4, the power supply device is a rechargeable secondary battery, and the update determination unit is a current path control device that determines whether or not to update the current path based on the timing at which the power supply device switches to a charging state or a discharging state.

9. In the current path control device according to Claim 4, The update determination unit predicts the change timing of the load current based on the driving plan information of the vehicle, and determines whether or not to update the current path at the change timing. A current path control device.

10. The current path control device according to claim 1, A plurality of power distribution devices that respectively distribute power to the loads of the vehicle, A power supply main line that connects the plurality of power distribution devices to each other, A vehicle power supply system including a plurality of power supply devices capable of supplying power to the power distribution devices via the power supply main line.

Images