JP2022018698A - Power supply device - Google Patents

Abstract

To provide a power supply device capable of suppressing deterioration in a change-over switch and occurrence of a failure.SOLUTION: A power supply device applies to a system comprising a lead acid battery 10, a starter 12, a rotary electric machine 11, an engine 14, and an ECU 21. The power supply device comprises a connection path L1 for connecting the lead acid battery 10 and the rotary electric machine 11, and a change-over switch SW provided in the connection path L1. The power supply device further includes a BMU 20 which controls the change-over switch SW, a first communication unit 22 which communicably connects the ECU 21 and the BMU 20 and transfers an ON signal from the ECU 21, and a second communication unit 23 which communicably connects the ECU 21 and the BMU 20 and transfers a signal indicating that start of the engine 14 has been completed. When communication by the first communication unit 22 is determined to be impossible, the BMU 20 inhibits the change-over switch SW from being switched to ON until it receives an engine start completion signal from the ECU 21 transferred by the second communication unit 23.SELECTED DRAWING: Figure 1

Description

The present invention relates to a power supply device.

As a power supply device, Patent Document 1 discloses a system including a first power storage unit, a power supply target connected to the first power storage unit, and a second power storage unit. The power supply device is provided in a connection path connecting the first storage unit and the second storage unit, and is provided in the connection path, and when it is turned on, the connection between the first storage unit and the second storage unit is made conductive and turned off. It is provided with a changeover switch that shuts off between the first power storage unit and the second power storage unit.

Japanese Unexamined Patent Publication No. 2017-21288

The system has a command unit and the power supply unit has a switch control unit. The command unit outputs an on command for the changeover switch. When the switch control unit receives an on command from the command unit, the switch control unit turns on the changeover switch.

The power supply unit includes a communication unit that enables communication between the command unit and the switch control unit. Here, for example, a delay in communication by the communication unit may cause communication to be interrupted by the communication unit. In this case, since the signal from the command unit is not transmitted to the switch control unit, the changeover switch is turned on while the power supply target is being driven, and a large current flows through the changeover switch, which may cause deterioration or failure of the changeover switch. There is.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a power supply device capable of suppressing deterioration and failure of a changeover switch.

In the present invention, the first power storage unit and
The power supply target connected to the first power storage unit and
The second power storage unit and
In a power supply applied to a system with a command unit
A connection path connecting the first power storage unit and the second power storage unit,
It is provided in the connection path, and when it is turned on, the connection between the first storage unit and the second storage unit is made conductive, and when it is turned off, it is between the first storage unit and the second storage unit. With a changeover switch that shuts off
A switch control unit that controls the changeover switch and
A first communication unit that is communicably connected between the command unit and the switch control unit and transmits an on command of the changeover switch from the command unit to the switch control unit.
A second communication unit that is communicably connected between the command unit and the switch control unit and transmits a signal indicating a drive state of the power supply target from the command unit to the switch control unit is provided.
When the switch control unit determines that communication by the first communication unit is possible, the switch control unit switches the changeover switch on when the on command is received from the command unit via the first communication unit. When it is determined that communication by the first communication unit is impossible, the changeover switch is turned on based on the signal indicating the drive state of the power supply target received from the command unit via the second communication unit. Prohibit switching.

According to the present invention, when the switch control unit determines that communication by the first communication unit is impossible, the switch control unit is a changeover switch based on a signal indicating a drive state of a power supply target received via the second communication unit. Prohibits switching on. As a result, even if communication by the first communication unit is disabled, the switch control unit can prohibit switching of the changeover switch to ON until it receives a signal indicating the drive state of the power supply target. As a result, it is possible to prevent the changeover switch from being turned on while the power supply target is being driven, and it is possible to suppress deterioration and failure of the changeover switch. Further, since the information regarding the switching of the changeover switch to the on can be promptly acquired via the second communication unit instead of the first communication unit, it is possible to prevent the changeover switch from being switched on from being delayed. ..

The block diagram of the power supply system which concerns on 1st Embodiment. A time chart showing an example of control of a comparative example. A flowchart of the process performed by BMU. A time chart showing an example of power system control. The block diagram of the power supply system which concerns on 2nd Embodiment.

<First Embodiment>
Hereinafter, embodiments embodying the present invention will be described with reference to the drawings. The power supply system of this embodiment is mounted on a vehicle. A vehicle travels by using an engine (internal combustion engine) as a traveling power source.

As shown in FIG. 1, the power supply system includes a lead storage battery 10, a rotary electric machine 11, and a starter 12. A lead storage battery 10 is connected in parallel to the rotary electric machine 11 and the starter 12. The lead storage battery 10 can supply power to the rotary electric machine 11 and the starter 12. The rated voltage of the lead storage battery 10 is, for example, 12V. In the present embodiment, the lead storage battery 10 corresponds to the "first power storage unit".

The rotary shaft of the rotary electric machine 11 can transmit power to the crank shaft of the engine 14 of the vehicle by a belt or the like, and the rotation of the crank shaft rotates the rotary shaft of the rotary electric machine 11 to generate power. That is, the rotary electric machine 11 functions as a generator. The generated power of the rotary electric machine 11 is charged into the lead storage battery 10 while being smoothed by the smoothing capacitor of the rotary electric machine 11. Further, the rotary electric machine 11 has a power output function of applying a rotational force to the crank shaft as an electric machine. In this case, the rotary electric machine 11 constitutes an ISG (Integrated Starter Generator). In the present embodiment, the rotary electric machine 11 corresponds to the "second power storage unit".

The starter 12 is a starting device for starting the engine 14. The starter 12 is driven by turning on the ignition switch of a vehicle (not shown) and being supplied with electric power from the lead storage battery 10, and starts the engine 14 by applying initial rotation to the output shaft of the engine 14. In the present embodiment, the starter 12 corresponds to the "power supply target".

The power supply system includes a connection path L1 for connecting the lead storage battery 10 and the rotary electric machine 11. A starter 12 is connected to a connection point N, which is an intermediate point of the connection path L1. The connection path L1 is a current path assuming that an input / output current is passed through the rotary electric machine 11.

The power supply system includes a changeover switch SW, a bypass path L2, and a resistor 13. The changeover switch SW is provided on the rotary electric machine 11 side of the connection path L1 with respect to the connection point N. When the changeover switch SW is turned on, the lead storage battery 10 and the rotary electric machine 11 are brought into a conductive state. On the other hand, when the changeover switch SW is turned off, the lead storage battery 10 and the rotary electric machine 11 are cut off.

The bypass path L2 electrically connects the connection point N side of the connection path L1 with respect to the changeover switch SW and the rotary electric machine 11 side of the connection path L1 with respect to the changeover switch SW so as to bypass the changeover switch SW. do. A resistor 13 is provided in the bypass path L2. The lead-acid battery 10 and the rotary electric machine 11 are always connected via the resistor 13 of the bypass path L2. As a result, even when the changeover switch SW is turned off, the lead storage battery 10 and the rotary electric machine 11 can be electrically connected to each other through the bypass path L2. By constantly connecting the lead-acid battery 10 and the rotary electric machine 11 via the resistor 13, the current flowing through the bypass path L2 is limited, and the lead-acid battery 10 can always energize the rotary electric machine 11. .. Therefore, the capacitor of the rotary electric machine 11 is held in a charged state. As a result, the inrush current flowing to the rotary electric machine 11 when the changeover switch SW is turned on is suppressed.

The power supply system includes a battery management unit (hereinafter referred to as BMU20) and an ECU 21 which is a higher control device than the BMU20. The BMU 20 is a microcomputer including a CPU, ROM, RAM, an input / output interface, and the like. The BMU 20 turns on or off the changeover switch SW based on the signal output from the ECU 21. In this embodiment, the BMU 20 corresponds to the "switch control unit".

The ECU 21 is an electronic control device including a well-known microcomputer including a CPU, ROM, RAM, flash memory, and the like. The signal output by the ECU 21 to the BMU 20 includes a changeover command Sg1 that turns on the changeover switch SW that is turned off before the start of the engine 14 after the start of the engine 14. The switching command Sg1 is a signal for securing a charging path from the rotary electric machine 11 to the lead storage battery 10 at an early stage after the engine 14 is started. The switching command Sg1 is output from the ECU 21 to the BMU 20 after the ignition switch is pressed by the user, for example. In the present embodiment, the changeover command Sg1 indicates an off command of the changeover switch SW by the logic L, and indicates an on command of the changeover switch SW by the logic H. The reason why the changeover switch SW is turned off before the engine 14 is started is, for example, to suppress the dark current flowing in the connection path L1. Further, in the present embodiment, the ECU 21 corresponds to the "command unit".

The ECU 21 can grasp the driving state of the starter 12. The ECU 21 outputs a binary signal indicating the driving state of the starter 12 to the BMU 20. In the present embodiment, the binary signal indicating the driving state of the starter 12 is the start completion signal Sg2 indicating whether or not the start of the engine 14 is completed. For example, when the ECU 21 determines that the initial explosion of the engine 14 is generated by the fuel injection control and the rotation speed of the crank shaft becomes equal to or higher than the predetermined rotation speed after the drive of the starter 12 is started, the ECU 21 outputs the start completion signal Sg2. Output. In the present embodiment, the start completion signal Sg2 of the engine 14 indicates that the start of the engine 14 has not been completed by the logic L, and indicates that the start of the engine 14 has been completed by the logic H.

The power supply system includes a first communication unit 22 that connects the BMU 20 and the ECU 21. In this embodiment, a CAN capable of multiplex communication is used as the first communication unit 22. In the present embodiment, the first communication unit 22 includes a CAN microcomputer and a transceiver IC having a built-in CAN communication controller. As a result, the BMU 20, the ECU 21, and other control devices (for example, the control device of the engine 14) are communicably connected to each other. The output signal of the ECU 21 including the switching command Sg1 and the start completion signal Sg2 of the engine 14 is transmitted to the BMU 20 via the first communication unit 22.

When the BMU 20 receives the changeover command Sg1 and the start completion signal Sg2 of the engine 14, the BMU 20 performs a normal time changeover control for switching on the changeover switch SW. The BMU 20 knows the period during which the changeover switch SW can be safely turned on by receiving the start completion signal Sg2 of the engine 14.

By the way, before starting the engine 14, the voltage at both ends of the changeover switch SW is the same (for example, 12V). On the other hand, during the start of the engine 14, a large current flows from the lead storage battery 10 to the starter 12, so that the terminal voltage of the lead storage battery 10 drops. Therefore, during the start of the engine 14, a voltage difference is generated at both ends of the changeover switch SW. In this state, when the changeover switch SW is turned on, a large current flows from the rotary electric machine 11 side to the changeover switch SW, and the changeover switch SW may deteriorate or break down.

Here, the first communication unit 22 may not be able to communicate, and the start completion signal Sg2 of the engine 14 may not be transmitted from the ECU 21 to the BMU 20. In this case, the BMU 20 cannot grasp the period during which the changeover switch SW can be safely turned on. The situations in which the BMU 20 and the ECU 21 cannot communicate include, for example, a situation in which communication is temporarily disabled due to a delay in communication timing or an increase in the load on the first communication unit 22. 1 There is a situation in which communication is always impossible due to a failure of the communication unit 22. Further, in a situation where the BMU 20 and the ECU 21 cannot communicate with each other, some of the signals transmitted from the ECU 21 to the BMU 20 (for example, the start completion signal Sg2 of the engine 14) are missing and communication is impossible. Situations are included.

FIG. 2 shows a comparative example in which a large current flows through the changeover switch SW when the communication by the first communication unit 22 is interrupted. In FIG. 2, (a) shows the state of whether or not the first communication unit 22 can communicate, (b) shows the transition of the current Is flowing through the starter 12, and (c) shows the terminal voltage VPb of the lead storage battery 10. (D) shows the transition of the output voltage Vm of the rotary electric machine 11, (e) shows the transition of the voltage difference Vd at both ends of the changeover switch SW, and (f) shows the changeover command input to the BMU 20. The transition of Sg1 is shown, (g) shows the transition of the start completion signal Sg2 input to the BMU20, (h) shows the state of the changeover switch SW, and (i) shows the transition of the current Iw flowing through the changeover switch SW. show.

At time t1, communication between the BMU 20 and the ECU 21 by the first communication unit 22 is disabled. In the present embodiment, the BMU 20 determines whether or not communication is possible by the first communication unit 22. The BMU 20 determines, for example, that communication by the first communication unit 22 is impossible when there is no communication from the ECU 21 via the first communication unit 22 for a predetermined time.

At time t2 after time t1, the engine 14 starts to start. As a result, the current Is flowing through the starter 12 increases. Along with this, the terminal voltage VPb of the lead storage battery 10 decreases. On the other hand, the output voltage Vm of the rotary electric machine 11 is substantially constant before and after the start of the engine 14. Therefore, the voltage difference Vd at both ends of the changeover switch SW increases. Here, the voltage difference Vd is positive when the voltage on the rotary electric machine 11 side is higher than that on the starter 12 side among both ends of the changeover switch SW.

Since communication by the first communication unit 22 is impossible, the logic of the start completion signal Sg2 of the engine 14 remains L. Therefore, the completion of the start of the engine 14 is not transmitted to the BMU 20, and the BMU 20 cannot grasp the period during which the changeover switch SW can be safely turned on. In the present embodiment, since there is a request to secure a charging path from the rotary electric machine 11 to the lead storage battery 10 at an early stage after the engine 14 is started, the start completion signal Sg2 is a condition for switching the logic of the switching command Sg1 to H. The condition regarding the logic of is not included. That is, the ECU 21 may set the logic of the switching command Sg1 to H even when the start of the engine 14 is not completed. FIG. 2 shows an example in which the logic of the switching command Sg1 is changed from L to H at the time t3 when the engine 14 is starting. In this case, the changeover switch SW is switched from off to on.

In the period from the time t3 when the changeover switch SW is turned on to the time t4 when the start of the engine 14 is completed, the current Iw flowing through the changeover switch SW increases. As a result, the changeover switch SW may deteriorate or break down. Here, the sign of the current Iw flowing through the changeover switch SW is positive in the direction from the rotary electric machine 11 to the lead storage battery 10.

In order to prevent deterioration of the changeover switch SW, for example, it is conceivable to wait until communication by the first communication unit 22 becomes possible. However, in this case, it becomes impossible to quickly secure the charging path. Therefore, as shown in FIG. 1, the power supply system includes a second communication unit 23 that connects the BMU 20 and the ECU 21. The second communication unit 23 is provided with a signal line that electrically connects the BMU 20 and the ECU 21 and enables communication of a single binary signal. In the present embodiment, the single binary signal transmitted from the ECU 21 to the BMU 20 by the second communication unit 23 is the start completion signal Sg2 of the engine 14. In the present embodiment, the BMU 20, the first communication unit 22, the second communication unit 23, the changeover switch SW, the connection path L1, the bypass path L2, and the resistor 13 correspond to the “power supply device”.

FIG. 3 shows the processing performed by the BMU 20. This process is repeated every predetermined cycle.

In step S10, it is determined whether or not communication by the first communication unit 22 is possible. If an affirmative determination is made in step S10, the process proceeds to step S11. In step S11, normal time switching control is performed. Specifically, on the condition that the logic of the start completion signal Sg2 of the engine 14 is H, when it is determined that the logic of the switching command Sg1 is H, the changeover switch SW is switched on. On the other hand, if it is determined in step S10 that communication by the first communication unit 22 is impossible, the process proceeds to step S12.

In step S12, it is determined whether or not the logic of the start completion signal Sg2 of the engine 14 transmitted via the second communication unit 23 is H. If an affirmative determination is made in step S12, the process proceeds to step S13, and switching of the changeover switch SW is permitted. In this case, if it is determined that the logic of the switching command Sg1 has been switched to H after the timing at which the switching is permitted, the switching switch SW is switched on. On the other hand, if a negative determination is made in step S12, the process proceeds to step S14, and switching of the changeover switch SW is prohibited. In this case, even if the logic of the changeover command Sg1 is switched to H, the changeover switch SW is not switched on.

FIG. 4 shows an example of control in the present embodiment when communication by the first communication unit 22 is interrupted. FIGS. 4 (a) to 4 (i) correspond to FIGS. 2 (a) to 2 (i) above.

Since the time t1 to the time t2 are the same as those in FIG. 2, the description thereof will be omitted. At the time t3 when the engine 14 is starting, the logic of the changeover command Sg1 is changed from L to H, but the changeover switch SW cannot be switched from off to on. If it is determined that communication by the first communication unit 22 is impossible, a negative determination is made in step S12 until the logic of the start completion signal Sg2 of the engine 14 is switched to H, and switching is made in step S14. This is because switching of the switch SW is prohibited.

At time t4, the start of the engine 14 is completed, and the current Is flowing through the starter 12 is reduced. Along with this, the terminal voltage VPb of the lead storage battery 10 rises. Therefore, the voltage difference Vd at both ends of the changeover switch SW decreases. At time t5 after time t4, the logic of the engine 14 start completion signal Sg2 transmitted from the ECU 21 to the BMU 20 via the second communication unit 23 is switched to H. As a result, an affirmative determination is made in step S12, and switching of the changeover switch SW is permitted in step S13. Therefore, the changeover switch SW is switched from off to on. As described above, it is possible to prevent the changeover switch SW from being switched and the current Iw flowing through the changeover switch SW from increasing during the period in which the voltage difference Vd at both ends of the changeover switch SW is increased.

According to the present embodiment described in detail above, the following effects can be obtained.

When it is determined that communication by the first communication unit 22 is impossible, the start completion signal Sg2 of the engine 14 is transmitted by the second communication unit 23. As a result, switching of the changeover switch SW to ON is prohibited until the BMU 20 receives the start completion signal Sg2 of the engine 14. Therefore, it is prevented that the changeover switch SW is turned on during the period when the voltage difference Vd at both ends of the changeover switch SW is increasing. As a result, it is possible to prevent the occurrence of a situation in which a large current flows through the changeover switch SW, and it is possible to suppress the occurrence of deterioration and failure of the changeover switch SW.

Further, since the BMU 20 can quickly acquire the start completion signal Sg2 via the second communication unit 23 instead of the first communication unit 22, it is possible to prevent the changeover switch SW from being switched on from being delayed. ..

In a communication network that enables multiplex communication, communication delay may occur, for example, due to an increase in the amount of communication. Therefore, in the present embodiment, it is assumed that the second communication unit 23 is composed of a signal line that enables communication of a single binary signal. Since the second communication unit 23 connects the two control devices of the BMU 20 and the ECU 21, the communication is delayed even when it is determined that the communication by the first communication unit 22 is impossible. Difficult or no communication delay occurs. Therefore, it is possible to prevent the occurrence of a situation in which the transmission of the start completion signal Sg2 is delayed. As a result, it is possible to prevent the occurrence of a situation in which a large current flows through the changeover switch SW, and it is possible to suppress the occurrence of deterioration and failure of the changeover switch SW.

It is assumed that the second communication unit 23 is composed of a signal line that enables communication of a single binary signal. As a result, the communication means of the start completion signal Sg2 between the BMU 20 and the ECU 21 is duplicated with the minimum necessary configuration. Therefore, the power supply system can be simplified as compared with the configuration in which the communication network such as CAN that enables multiple communication is duplicated. As a result, the cost of the power supply system can be reduced.

<Second Embodiment>
Hereinafter, the second embodiment will be described with reference to FIG. 5, focusing on the differences from the first embodiment. In FIG. 5, the same reference numerals are given to the configurations shown in FIG. 1 above for convenience.

In the first embodiment, the power supply system is a single power supply system having a lead storage battery 10 as a "first power storage unit". In the present embodiment, the power supply system is a dual power supply system having a lithium ion storage battery 30 as a "first power storage unit" and a lead storage battery 10 as a "second power storage unit". The lithium ion storage battery 30 is a high-density storage battery having a smaller power loss during charging and discharging, and a higher output density and energy density than the lead storage battery 10. The rated voltage of the lead storage battery 10 and the lithium ion storage battery 30 are the same, for example, 12V.

The power supply system includes an electric load 31, a first changeover switch SW1, and a connection path L1. The electric load 31 is, for example, a rotary electric machine that restarts the engine 14 in idling stop control and assists torque when the vehicle starts or accelerates. The connection path L1 connects the lead storage battery 10 and the electric load 31. The connection path L1 is provided with a first changeover switch SW1. When the first changeover switch SW1 is turned on, the lead storage battery 10 is charged and discharged via the connection path L1.

The power supply system includes a second changeover switch SW2. Of the connection path L1, the second changeover switch SW2 is connected to the connection point P on the electric load 31 side of the first changeover switch SW1. A lithium ion storage battery 30 is connected to the side of both ends of the second changeover switch SW2 opposite to the connection point P. When the second changeover switch SW2 is turned on, the lithium ion storage battery 30 is charged and discharged via the connection path L1. Specifically, by supplying electric power to the electric load 31 as a rotary electric machine, it is possible to restart the engine 14 and to perform torque assist at the time of starting or accelerating the vehicle. In the present embodiment, the electric load 31 corresponds to the “power supply target”. Further, the BMU 20, the first communication unit 22, the second communication unit 23, the first and second changeover switches SW1 and SW2, and the connection path L1 correspond to the "power supply device".

The BMU 20 turns on / off the first and second changeover switches SW1 and SW2 based on the command from the ECU 21.

The ECU 21 outputs a binary signal indicating the driving state of the electric load 31 to the BMU 20. In the present embodiment, the signal indicating the driving state of the electric load 31 is a signal indicating whether or not the restart of the engine 14 is completed, or whether or not the torque assist at the time of starting or accelerating the vehicle is completed. It is a signal to show.

When the BMU 20 receives, for example, the restart completion signal of the engine 14 and the switching command Sg1, the BMU 20 performs normal switching control. The BMU 20 grasps the timing at which the first changeover switch SW1 can be safely turned on by receiving the restart completion signal of the engine 14.

Specifically, before restarting the engine 14, the voltage at both ends of the first changeover switch SW1 is the same (for example, 12V). On the other hand, during the restart of the engine 14, a large current flows from the lithium ion storage battery 30 to the electric load 31, so that the terminal voltage of the lithium ion storage battery 30 drops. Therefore, during the restart of the engine 14, a voltage difference is generated at both ends of the first changeover switch SW1. In this state, when the first changeover switch SW1 is turned on, a large current flows from the lead storage battery 10 side to the first changeover switch SW1, and the first changeover switch SW1 may be deteriorated or malfunction. .. Therefore, in order to prevent the first changeover switch SW1 from being turned on while the engine 14 is restarting, the BMU 20 may receive the restart completion signal of the engine 14 and safely turn on the first changeover switch SW1. Understand the possible period.

When the first communication unit 22 cannot communicate, the restart completion signal of the engine 14 may not be transmitted from the ECU 21 to the BMU 20. In this case, the BMU 20 cannot grasp the period during which the changeover switch SW can be safely turned on. As a result, the first changeover switch SW1 may be turned on when there is a voltage difference between both ends of the first changeover switch SW1.

Therefore, in the present embodiment, when the first communication unit 22 cannot communicate, the restart completion signal of the engine 14 is transmitted from the ECU 21 to the BMU 20 via the second communication unit 23 provided in the power supply system. Until this is done, switching of the first changeover switch SW1 to ON is prohibited. In the present embodiment, the restart completion signal of the engine 14 indicates that the restart of the engine 14 has not been completed by the logic L, and indicates that the restart of the engine 14 has been completed by the logic H. In this case, in step S12 in FIG. 3, it is determined whether or not the logic of the restart completion signal of the engine 14 is H.

Also in this embodiment, the same effect as that of the first embodiment can be obtained.

<Other embodiments>
Each of the above embodiments may be modified as follows.

The first communication unit 22 may be any one capable of multiplex communication, and may be, for example, a LIN (Local Interconnect Network).

-The second communication unit 23 is not limited to the one capable of communicating a single binary signal. As the second communication unit 23, for example, a CAN or the like capable of multiple communication may be used as in the case of the first communication unit 22.

The first and second communication units 22 and 23 are not limited to those connecting the BMU 20 and the ECU 21 by wire, but may be connected wirelessly.

-In the second embodiment, the electric load 31 is not limited to the rotary electric machine. For example, it may be a seat heater which is a general electric load, a heater for a defroster of a rear window, a headlight, a wiper of a front window, an air conditioning fan of an air conditioner, or the like.

-In the first embodiment, when it is determined that communication by the first communication unit 22 is impossible, it is determined that the logic of the start completion signal Sg2 of the engine 14 has become H, and then the logic of the switching command Sg1 has become H. It is said that the changeover switch SW can be switched on by determining that the switch has been turned on, but the present invention is not limited to this. When it is determined that communication by the first communication unit 22 is impossible, the switching command Sg1 is not determined, and the logic of the engine 14 start completion signal Sg2 is determined to be H, so that the changeover switch SW is turned on. It may be switched to. As a result, the period until the logic of the changeover command Sg1 becomes H can be omitted, and it is possible to prevent the changeover switch SW from being switched on from being delayed.

-In the second embodiment, the binary signal indicating the driving state of the electric load 31 is not limited to the restart completion signal of the engine 14. For example, it may be a torque assist completion signal or a power supply completion signal indicating whether or not the power supply to the electric load 31 is completed. When the BMU 20 receives the torque assist completion signal and the switching command Sg1, or the power supply completion signal and the switching command Sg1, the first changeover switch SW1 may be switched on.

In the second embodiment, when the first communication unit 22 is unable to communicate, the signal transmitted via the second communication unit 23 is not limited to the restart completion signal of the engine 14, for example, torque assist completion. It may be a signal. In this case, for example, the BMU 20 may prohibit switching of the first changeover switch SW1 to ON until the torque assist completion signal is transmitted from the ECU 21 via the second communication unit 23. Here, the torque assist completion signal indicates that the torque assist is not completed by the logic L, and indicates that the torque assist is completed by the logic H. In this case, in step S12 in FIG. 3, it may be determined whether or not the logic of the torque assist completion signal is H.

Further, in each of the above embodiments, when the first communication unit 22 is unable to communicate, the signal transmitted via the second communication unit 23 indicates whether or not the starter 12 and the electric load 31 are energized. It may be a signal indicating. For example, information indicating the magnitude of the energizing current flowing through the starter 12 and the electric load 31 is input to the ECU 21. When the energization current flowing through the starter 12 and the electric load 31 is equal to or greater than a predetermined value, the ECU 21 determines that the starter 12 and the electric load 31 are energized, and outputs a signal to the effect that the starter 12 and the electric load 31 are energized. The BMU 20 prohibits switching of the changeover switch SW or the first changeover switch SW1 while the starter 12 and the electric load 31 are energized. Here, the signal indicating that the power is on indicates that the starter 12 and the electric load 31 are energized by the logic L, and that the starter 12 and the electric load 31 are not energized by the logic H. In this case, in step S12 in FIG. 3, it may be determined whether or not the logic of the signal indicating that the power is being supplied is H.

In each of the above embodiments, when the first communication unit 22 is unable to communicate, the signal transmitted by the second communication unit 23 is not limited to the signal in the direction from the ECU 21 to the BMU 20, but is from the BMU 20. It may be a signal in the direction toward the ECU 21. This signal is, for example, a prohibition signal for prohibiting the driving of the starter 12 and the electric load 31. Specifically, the BMU 20 outputs a prohibition signal to the ECU 21 prior to switching on the changeover switch SW or the first changeover switch SW1. When the ECU 21 receives the prohibition signal, the ECU 21 prohibits the driving of the starter 12 or the electric load 31. This prevents the starter 12 or the electric load 31 from being driven while the changeover switch SW or the first changeover switch SW1 is on. Therefore, it is possible to prevent the occurrence of a situation in which a large current flows through the changeover switch SW and the first changeover switch SW1, and it is possible to suppress the occurrence of deterioration and failure of the changeover switch SW and the first changeover switch SW1.

-In the second embodiment, the power supply system may be configured to include the third and fourth changeover switches SW3 and SW4 in addition to the first and second changeover switches SW1 and SW2. The third and fourth changeover switches SW3 and SW4 in this configuration correspond to, for example, the third and fourth switches 23 and 24 described in FIG. 1 of JP-A-2017-052446.

-The BMU 20 is not limited to the power supply system mounted on the vehicle, and may be applied to a power supply system other than the vehicle-mounted power system.

10 ... lead-acid battery, 11 ... rotary electric machine, 12 ... starter, 20 ... BMU, 21 ... ECU, 22 ... first communication unit, 23 ... second communication unit, 30 ... lithium ion storage battery, SW ... changeover switch, SW1 ... first 1 changeover switch.

Claims (4)

The first power storage unit (10, 30) and
The power supply target (12, 31) connected to the first power storage unit and
The second power storage unit (10, 11) and
In a power supply applied to a system comprising a command unit (21).
A connection path (L1) connecting the first power storage unit and the second power storage unit,
It is provided in the connection path, and when it is turned on, the connection between the first storage unit and the second storage unit is made conductive, and when it is turned off, it is between the first storage unit and the second storage unit. Switch (SW, SW1) that shuts off
The switch control unit (20) that controls the changeover switch and
A first communication unit (22) that is communicably connected between the command unit and the switch control unit and transmits an on command of the changeover switch from the command unit to the switch control unit.
A second communication unit (23) is provided which is communicably connected between the command unit and the switch control unit and transmits a signal indicating a drive state of the power supply target from the command unit to the switch control unit.
When the switch control unit determines that communication by the first communication unit is possible, the switch control unit switches the changeover switch on when the on command is received from the command unit via the first communication unit. When it is determined that communication by the first communication unit is impossible, the changeover switch is turned on based on the signal indicating the drive state of the power supply target received from the command unit via the second communication unit. A power supply that prohibits switching between. The power supply target is a starting device that starts or restarts the engine by applying an initial rotation to the output shaft of the engine (14).
The signal indicating the drive state of the power supply target is a signal indicating that the start or restart of the engine by the starter has been completed.
A claim that the switch control unit prohibits switching on of the changeover switch until it receives a signal indicating a drive state of the power supply target when it determines that communication by the first communication unit is impossible. The power supply device according to 1. The signal indicating the drive state of the power supply target is a signal indicating that the energization current of the power supply target is a predetermined value or more.
When the switch control unit determines that communication by the first communication unit is impossible, the switch control unit prohibits switching on of the changeover switch during the period of receiving a signal indicating the drive state of the power supply target. The power supply device according to claim 1. The first communication unit enables multiple communication and enables multiple communication.
The power supply device according to any one of claims 1 to 3, wherein the second communication unit is capable of communicating a single binary signal.

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