JP7188542B2 - Power supply system, method and program - Google Patents

Description

The present disclosure relates to a power supply system and the like that redundantly includes a plurality of batteries.

Japanese Unexamined Patent Application Publication No. 2002-200000 discloses a power supply system for a vehicle in which a main battery and a sub-battery are used to form a power supply in a redundant configuration. In this power supply system, the main battery is directly connected to the load mounted on the vehicle, and the sub-battery is connected to the load mounted on the vehicle via a DCDC converter or relay switch to ensure power redundancy. there is

JP-A-2004-328988

When using a sub-battery as a backup power supply for a load that is important in automatic driving, it is necessary to maintain the sub-battery in a predetermined state required for the backup power supply. However, the power supply system described in Patent Document 1 has a configuration in which the sub-battery is always connected to the load via either a DCDC converter or a relay switch. It's not easy to keep up.

The present disclosure has been made in view of the above problems, and aims to provide a power supply system or the like that can easily diagnose the state of a predetermined single battery and maintain it in a predetermined state. and

In order to solve the above problems, one aspect of the disclosed technology is a power supply system, comprising: a first battery connected to a first load; a second battery; A connection switching unit including a DCDC converter that connects a battery, a first switch that connects a first battery and a second load, and a second switch that connects a second battery and a second load. and the connection switching unit includes a first mode for closing the first switch and opening the second switch, and a first mode for opening the first switch and opening the second switch is selectively switched between a second mode for closing the

In the power supply system of one aspect of the present disclosure, when the first switch is closed to directly supply power from the first battery to the second load, the second switch is opened to power the second battery. Disconnect from second load (first mode). Accordingly, the state of the second battery can be easily diagnosed and the predetermined state can be easily maintained by the charge/discharge control using the DCDC converter. In addition, in this first mode, the DCDC converter does not need to supply power to the second load, and only needs to diagnose and maintain the state of the second battery, so power consumption can be suppressed. On the other hand, when the first switch is opened to disconnect the first battery from the second load, the second switch is closed to connect the second battery to the second load (second load). mode). As a result, power can be supplied from the second battery to the second load even if the first battery fails.

In this aspect, the connection switching unit may switch the states of the first switch and the second switch after controlling the voltage difference between the primary side and the secondary side of the DCDC converter to be equal to or less than a predetermined value. good.

By this control, the voltage difference between the primary side and the secondary side of the DCDC converter can be reduced, so that voltage fluctuation can be suppressed when the mode is switched. In addition, it is possible to quickly switch between modes.

When the power supply system of this aspect is installed in a vehicle, the first mode can be the manual operation mode, and the second mode can be the automatic operation mode.

According to the power supply system and the like of the present disclosure, the state of the battery alone can be easily diagnosed and maintained in a predetermined state.

A diagram showing a schematic configuration of a power supply system according to an embodiment of the present disclosure Diagram showing a configuration example of a DCDC converter Flowchart for explaining mode switching control performed by the connection switching unit The figure which shows the state of the 1st and 2nd switch in manual operation mode. The figure which shows the state of the 1st and 2nd switch in automatic operation mode.

[Overview]
The power supply system redundantly provided with a plurality of batteries of the present disclosure keeps the sub-battery disconnected from the load in a normal state in which power is supplied to the load from the main battery. As a result, the state of the sub-battery alone can be easily diagnosed, and the predetermined state can be easily maintained.

[Configuration of power supply system]
FIG. 1 is a diagram showing a schematic configuration of a power supply system 1 according to an embodiment of the present disclosure. The power supply system 1 illustrated in FIG. 1 includes a first battery 11, a second battery 12, a first load 21, a second load 22, a connection switching unit 30, and a generator 40. I have.

The first battery 11 , the first load 21 , the connection switching section 30 and the generator 40 are interconnected by a first wiring 51 . The second battery 12 and the connection switching unit 30 are connected by a second wiring 52 . The second load 22 and the connection switching unit 30 are connected by a third wiring 53 .

The power supply system 1 according to this embodiment can be installed in equipment that requires a redundant power supply configuration. In the following embodiments, an example will be described in which the power supply system 1 is installed in a vehicle capable of switching between a manual operation mode and an automatic operation mode.

The generator 40 is a device capable of outputting a predetermined amount of power, such as an alternator or a DCDC converter. The power output by the generator 40 is supplied to the first battery 11, the first load 21, and the like.

The first battery 11 is a chargeable/dischargeable power storage element such as a lead-acid battery or a lithium-ion battery. The first battery 11 stores power output by the generator 40 and releases power stored by itself to the first load 21 and the connection switching unit 30 . The first battery 11 is provided as a main battery exclusively used for running the vehicle. Note that a capacitor may be used instead of the battery.

The second battery 12 is a chargeable/dischargeable power storage element such as a lead-acid battery or a lithium-ion battery. The second battery 12 stores the power output by the generator 40 and the power of the first battery 11 via the connection switching unit 30, and stores the power stored by itself via the connection switching unit 30 to the second battery. It is discharged (supplied) to the load 22 or the like. This second battery 12 is redundantly provided as a sub-battery for backing up the first battery 11 .

The first load 21 is an in-vehicle device that consumes power. The first load 21 is configured to operate with power output by the generator 40 and/or power stored in the first battery 11 .

The second load 22 is an on-vehicle device that consumes electric power, and can be a device particularly related to safe driving of the vehicle. More specifically, the second load 22 is an important load that requires power supply from the second battery 12 for a predetermined period and with a predetermined current even if the power source of the first battery 11 fails. , for example, in automatic driving, it can be a load that performs an important function for safely evacuating the vehicle in an emergency. As will be described later, the second load 22 operates on power output from the generator 40 and/or power stored in the first battery 11 during manual operation, and stores power in the first battery 11 during automatic operation. It is configured to operate on stored power and/or power stored in the second battery 12 .

The connection switching unit 30 includes a first switch 31, a second switch 32, and a DCDC converter 33 in its configuration. These configurations are controlled by a controller such as a microcomputer (not shown).

The first switch 31 is arranged between the first wiring 51 and the third wiring 53 and is configured to be openable and closable based on the driving mode of the vehicle. The first switch 31 is closed to connect the first wiring 51 and the third wiring 53 when the vehicle is in the manual operation mode, and is opened when the vehicle is in the automatic operation mode. The first wiring 51 and the third wiring 53 are separated by pressing. For the first switch 31, for example, a normally-on semiconductor relay, an excitation mechanical relay, or the like can be used.

The second switch 32 is arranged between the second wiring 52 and the third wiring 53 and is configured to be openable and closable based on the driving mode of the vehicle. The second switch 32 is closed to connect the second wiring 52 and the third wiring 53 when the vehicle is in the automatic driving mode, and is opened when the vehicle is in the automatic driving mode. to separate the second wiring 52 and the third wiring 53 . For the second switch 32, for example, a normally-off semiconductor relay, an excitation mechanical relay, or the like can be used.

The DCDC converter 33 is a voltage converter that converts an input voltage into a predetermined voltage and outputs the voltage. The DCDC converter 33 has a primary side connected to a first wiring 51 and a secondary side connected to a second wiring 52 . The DCDC converter 33 has, for example, a step-down function of stepping down the voltage on the primary side and outputting it to the secondary side, and a step-up function of stepping up the voltage on the secondary side and outputting it to the primary side. A step-up/step-down type DCDC converter can be used.

An example of a bidirectional buck-boost DCDC converter is shown in FIG. In the DCDC converter illustrated in FIG. 2, a switching element M1, an inductor L, and a switching element M3 connected in series are inserted between a primary side terminal and a secondary side terminal. A switching element M2 is grounded between the switching element M1 and the inductor L, and a switching element M4 is grounded between the inductor L and the switching element M3. Smoothing capacitors C1 and C2 are grounded to the primary side terminal and the secondary side terminal, respectively. For example, a field effect transistor (MOSFET: Metal Oxide Semiconductor Field Effect Transistor) can be used for the switching elements M1 to M4. The switching elements M1 to M4 have their gate voltages controlled by a control unit (not shown) to perform on/off operations.

[Control executed by the power system]
Next, control executed by the power supply system 1 according to the present embodiment will be described with further reference to FIGS. 3 to 5. FIG. FIG. 3 is a flowchart for explaining the procedure of mode switching control performed by the connection switching unit 30 of the power supply system 1 . FIG. 4 is a diagram showing states of the first switch 31 and the second switch 32 in the manual operation mode. FIG. 5 is a diagram showing states of the first switch 31 and the second switch 32 in the automatic operation mode.

The control illustrated in FIG. 3 is started when the power of the vehicle is turned on, and is repeatedly executed until the power is turned off. It should be noted that the initial state of the vehicle immediately after the power is turned on is described assuming that the manual operation mode is set.

Step S301: The connection switching unit 30 closes the first switch 31 and opens the second switch 32 to set the power supply system 1 to the "manual operation mode (FIG. 4)". When the manual operation mode is set, the process proceeds to step S302.

In this manual operation mode, power can be supplied from the first battery 11 to the second load 22 without going through the DCDC converter 33 (solid line arrow in FIG. 4), so power consumption in the DCDC converter 33 can be suppressed. Further, since the second battery 12 is disconnected from the second load 22 and current does not flow from the second battery 12 to the second load 22, discharging of the second battery 12 can be suppressed. In addition, since the second battery 12 is connected to the first battery 11 and the generator 40 via the DCDC converter 33, it can be charged with the power of the first battery 11 and the power generated by the generator 40. It becomes possible. Furthermore, since the DCDC converter 33 is bi-directional, it is possible to discharge from the second battery 12 (second wiring 52 side) toward the first battery 11 and the like (first wiring 51 side).

Step S<b>302 : The connection switching unit 30 diagnoses the state of the second battery 12 . This diagnosis is performed, for example, by determining whether the second battery 12 is in a predetermined state at predetermined time intervals. This predetermined state refers to a state in which the second battery 12 stores electric power capable of continuously outputting a specified current value for a specified time. SOC), internal resistance value, and the like. This diagnosis can be performed, for example, based on changes in the voltage value and current value when discharging from the second battery 12 to the first wiring 51 via the DCDC converter 33 (broken line in FIG. 4). arrow). If the second battery 12 is in the predetermined state (S302, OK), the process proceeds to step S304, and if the second battery 12 is not in the predetermined state (S302, NG), step The process proceeds to S303.

Step S303: The connection switching unit 30 performs predetermined recovery processing so that the second battery 12 is in a predetermined state. As an example of the recovery process, when the amount of electricity stored in the second battery 12 is less than the specified amount of electricity stored, the process of charging the second battery 12 with the power of the first battery 11 via the DCDC converter 33. , and when the amount of electricity stored in the second battery 12 is greater than the specified amount of electricity stored, there is a process of discharging the power of the second battery 12 to the first wiring 51 via the DCDC converter 33 (Fig. 4 dashed arrow). After the recovery process is executed, the process proceeds to step S304.

Step S304: The connection switching unit 30 determines whether or not the vehicle has transitioned from manual driving to automatic driving. If the operation is not shifted to automatic operation and remains manual operation (S304, No), the process returns to step S302, and if the manual operation is shifted to automatic operation (S304, Yes), the process proceeds to step S305. move on.

The determination in step S304 may be performed in parallel with the processing in steps S302 and S303, but step S305 may be performed after recovery of the second battery 12 in step S303.

Step S305: The connection switching unit 30 opens the first switch 31, closes the second switch 32, and sets the power supply system 1 to the "automatic operation mode (FIG. 5)". When the automatic driving mode is set, the process proceeds to step S306.

In this automatic operation mode, power is supplied from the first battery 11 to the second load 22 via the DCDC converter 33, and power is also supplied from the second battery 12 (solid line in FIG. 5). arrow). As a result, even in an emergency such as when the first battery 11 fails, the second battery 12 is hardly affected by the failure due to the action of the intervening DCDC converter 33. can back up the power supply from to the second load 22 .

Here, the reason why the second battery 12 is hardly affected even if the first battery 11 fails will be described with reference to FIG. When the voltage on the primary side of the DCDC converter 33 to which the first battery 11 is connected becomes lower than the voltage on the secondary side to which the second battery 12 is connected, the primary side is A boosting operation is performed to flow a current toward the secondary side (energy charge to the inductor L by turning on the switching elements M1 and M4, and discharge from the inductor L by turning off the switching element M4 and turning on the switching element M3). Therefore, current discharge from the second battery 12 through the DCDC converter 33 does not occur. Further, when the voltage drop on the primary side of the DCDC converter 33 progresses, a control unit (not shown) stops the operation of the DCDC converter 33 (all the switching elements M1 to M4 are turned off). No current discharge occurs through the In this way, the power of the second battery 12 is maintained.

Step S306: The connection switching unit 30 determines whether or not the vehicle has transitioned from automatic driving to manual driving. If the automatic operation remains without shifting to manual operation (S306, No), the determination of step S306 is continued, and if the automatic operation shifts to manual operation (S306, Yes), the process proceeds to step S301. Processing returns.

In addition, when switching the operation mode, in order to suppress the influence of voltage fluctuation, one battery is charged and discharged to reduce the voltage difference between the primary side and the secondary side of the DCDC converter 33 to a predetermined value or less as much as possible. It is desirable to keep However, when the current is discharged from the secondary side of the DCDC converter 33 to the primary side, the power supply voltage of the first wiring 51 rises further from the output voltage of the generator 40 and becomes higher. The rated voltage may be exceeded. In order to avoid such a situation, it is useful to lower the output voltage of the generator 40 in advance when discharging the current from the secondary side of the DCDC converter 33 to the primary side.

[Functions and effects of the present embodiment]
According to the power supply system 1 according to the embodiment of the present disclosure described above, in the manual operation mode (first mode), the connection switching unit 30 closes the first switch 31 to switch from the first battery 11 to Power is directly supplied to the second load 22 and the second switch 32 is opened to disconnect the second battery 12 from the second load 22 .

As a result, in the manual operation mode, the charge/discharge control using the DCDC converter 33 makes it possible to easily diagnose the state of the second battery 12 alone, which is for backup during automatic operation. A state in which power can be supplied with a predetermined current can be easily maintained. In addition, in this manual operation mode, the DCDC converter 33 does not need to supply power to the second load 22, and only needs to diagnose and maintain the state of the second battery 12, so power consumption can be suppressed.

Further, according to the power supply system 1 according to the present embodiment, in the automatic operation mode (second mode), the connection switching unit 30 opens the first switch 31 to switch the first battery 11 to the second load. 22 , the second switch 32 is closed to connect the second battery 12 to the second load 22 .

Thereby, in the automatic operation mode, power can be supplied from the second battery 12 to the second load 22 even if the first battery 11 fails.

Furthermore, according to the power supply system 1 according to the present embodiment, the connection switching unit 30 controls the voltage difference between the primary side and the secondary side of the DCDC converter 33 to a predetermined value or less, and then switches the first switch 31 and The state of the second switch 32 is switched. As a result, the voltage difference between the primary side and the secondary side of the DCDC converter 33 can be reduced, thereby suppressing voltage fluctuation when switching the operation mode. In addition, it is possible to quickly switch the operation mode.

Note that when the vehicle is powered off, the first switch 31 shown in FIG. It is desirable to set the switch 32 to the manual operation mode with the switch 32 open.

Further, although the above embodiment has been described using a bidirectional buck-boost DCDC converter, the scope to which the present disclosure is applied does not have to be "bidirectional".

The power supply system and the like of the present disclosure can be used in vehicles and the like that are redundantly equipped with a plurality of batteries.

1 power supply system 11 first battery 12 second battery 21 first load 22 second load 30 connection switching unit 31 first switch 32 second switch 33 DCDC converter 40 generators 51 to 53 wiring

Claims (5)

a first battery connected to a first load;
a second battery;
A voltage converter connecting the first battery and the second battery, a first switch connecting the first battery and the second load, and the second battery and the second load A connection switching unit including a second switch that connects the
The connection switching unit closes the first switch and opens the second switch after controlling the voltage difference between the primary side and the secondary side of the voltage converter to be equal to or less than a predetermined value. Selectively switching between a first mode to open the first switch and a second mode to close the second switch,
power system. In the first mode, when the amount of charge of the second battery is less than a specified amount of charge, the connection switching unit increases the amount of charge of the second battery by charging via the voltage converter. characterized by switching from the first mode to the second mode after recovering to a specified amount of stored electricity,
The power system of claim 1. The power supply system is mounted on a vehicle,
The first mode is a manual operation mode, and the second mode is an automatic operation mode,
The power supply system according to claim 1 or 2. A first battery connected to a first load, a second battery, a voltage converter connecting the first battery and the second battery, the first battery and the second load and a connection switching unit including a first switch that connects the second battery and the second load that connects the second battery and the second load.
a first mode in which the first switch is closed and the second switch is opened after the voltage difference between the primary side and the secondary side of the voltage converter is controlled to a predetermined value or less; , selectively switching between a second mode in which the first switch is opened and the second switch is closed,
Method. A first battery connected to a first load, a second battery, a voltage converter connecting the first battery and the second battery, the first battery and the second load A program to be executed by a computer of a power supply system, comprising a connection switching unit including a first switch that connects and a second switch that connects the second battery and the second load, ,
a first mode in which the first switch is closed and the second switch is opened after controlling the voltage difference between the primary side and the secondary side of the voltage converter to a predetermined value or less; , selectively switching between a second mode in which the first switch is open and the second switch is closed,
program.

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