JP7627626B2 - Power Control Unit - Google Patents

Description

The disclosed embodiment relates to a power supply control device.

Conventionally, there is a redundant power supply system that has a first power supply and a second power supply so that the vehicle can be evacuated to a safe place and stopped even if a power failure such as a ground fault occurs while the vehicle is traveling in autonomous driving mode, and if a ground fault occurs in one of the power supply systems, the other power supply system supplies power to the on-board equipment (load) for autonomous driving (see, for example, Patent Document 1).

The redundant power supply system includes a first system connected to a first load for automatic operation, a second system connected to a second load having the same functions as the first load, and an inter-system switch capable of connecting and disconnecting the first and second systems.

Under normal circumstances, the redundant power supply system connects the inter-system switch to supply power from the first power supply to the first load and the second load. If a ground fault occurs in the first system, the redundant power supply system shuts off the inter-system switch to supply power from the second power supply to the second load, and if a ground fault occurs in the second system, the redundant power supply system shuts off the inter-system switch to supply power from the first power supply to the first load.

In such a redundant power supply system, a ground fault may occur in the second system, and the ground fault in the second system may be eliminated after the inter-system switch is shut off. In such a case, the superimposed power supply system restores electrical continuity to the inter-system switch, and returns to the normal state in which power is supplied from the first power supply to the first load and the second load.

JP 2018-182864 A

However, the superimposed power supply system has the problem that it takes time to supply sufficient power to the second load after the ground fault in the second system is resolved.

One aspect of the embodiment has been made in consideration of the above, and aims to provide a power supply control device that can shorten the time it takes to supply sufficient power to the second load after a ground fault in the second system is resolved.

The power supply control device according to one aspect of the embodiment includes a first system, a second system, an inter-system switch, a supply circuit, and a control unit. The first system supplies power from a first power source to a first load. The second system supplies power from a second power source to a second load. The inter-system switch is provided in a connection path connecting the first system and the second system, and is capable of connecting and disconnecting the first system and the second system. The supply circuit supplies a weak current from the second power source to the second load. When the control unit detects a ground fault in the first system or the second system, it shuts off the inter-system switch, and when the ground fault in the second system continues, it supplies a weak current to the second load via the supply circuit.

The power supply control device according to one aspect of the embodiment can reduce the time it takes to supply sufficient power to the second load after a ground fault in the second system is resolved.

FIG. 1 is an explanatory diagram illustrating an example of the configuration of a power supply control device according to an embodiment. FIG. 2 is an explanatory diagram illustrating an example of the operation of the power supply control device according to the embodiment. FIG. 3 is an explanatory diagram illustrating an example of the operation of the power supply control device according to the embodiment. FIG. 4 is an explanatory diagram illustrating an example of the operation of the power supply control device according to the embodiment. FIG. 5 is an explanatory diagram illustrating an example of the operation of the power supply control device according to the embodiment. FIG. 6 is an explanatory diagram illustrating an example of the operation of the power supply control device according to the embodiment. FIG. 7 is a flowchart illustrating an example of a process executed by the control unit of the power supply control device according to the embodiment.

Embodiments of the power supply control device will be described in detail below with reference to the attached drawings. Note that the present invention is not limited to the embodiments described below. The following describes an example of a power supply control device that is installed in a vehicle with an autonomous driving function and supplies power to a load, but the power supply control device according to the embodiment may also be installed in a vehicle that does not have an autonomous driving function.

In the following, we will explain the case where the vehicle in which the power supply control device is installed is an electric vehicle or a hybrid vehicle, but the vehicle in which the power supply control device is installed may also be an engine vehicle that runs on an internal combustion engine.

The power supply control device according to the embodiment may be installed in any device that includes a first power supply and a second power supply, and that backs up the first or second power supply using the other power supply system in the event of a power failure in either the first or second power supply system.

[1. Configuration of power supply control device]
Fig. 1 is an explanatory diagram showing a configuration example of a power supply control device according to an embodiment. As shown in Fig. 1, the power supply control device 1 according to the embodiment is connected to a first power supply 10, a first load 101, a general load 102, a second load 103, and an automatic operation control device 100. The power supply control device 1 includes a first system 110 that supplies power from the first power supply 10 to the first load 101 and the general load 102, and a second system 120 that supplies power from a second power supply 20 (described later) to the second load 103.

The first load 101 includes a load for autonomous driving. For example, the first load 101 includes a steering motor, an electric brake device, an in-vehicle camera, a radar, and the like that operate during autonomous driving. The general load 102 includes, for example, a display, an air conditioner, an audio device, a video device, various lights, and the like.

The second load 103 has the same functions as the first load 101. The second load 103 includes devices that operate during autonomous driving, such as a steering motor, an electric brake device, an in-vehicle camera, and a radar. The first load 101, the general load 102, and the second load 103 operate using power supplied from the power supply control device 1. The autonomous driving control device 100 is a device that controls the autonomous driving of a vehicle by operating the first load 101 or the second load 103.

The first power source 10 includes a DC/DC converter (hereinafter referred to as "DC/DC11") and a lead battery (hereinafter referred to as "PbB12"). Note that the battery of the first power source 10 may be any secondary battery other than PbB12.

The DC/DC 11 is connected to a generator and a high-voltage battery with a higher voltage than the PbB 12, and steps down the voltage of the generator and the high-voltage battery and outputs it to the first system 110. The generator is, for example, an alternator that converts the kinetic energy of a traveling vehicle into electricity to generate electricity. The high-voltage battery is, for example, a battery for driving the vehicle that is installed in an electric vehicle or a hybrid vehicle.

When the first power source 10 is installed in an engine vehicle, an alternator (generator) is provided instead of the DC/DC 11. The DC/DC 11 charges the PbB 12, supplies power to the first load 101 and the general load 102, supplies power to the second load 103, and charges the second power source 20 described below.

The power supply control device 1 includes a second power supply 20, an inter-system switch 41, a battery switch 42, a backup switch 43, a control unit 3, a first voltage sensor 51, a second voltage sensor 52, and a supply circuit 53. The second power supply 20 is a backup power supply in case the first power supply 10 is unable to supply power. The second power supply 20 includes a lithium ion battery (hereinafter referred to as "LiB21"). Note that the battery of the second power supply 20 may be any secondary battery other than LiB21.

The inter-system switch 41 is provided in the connection path 130 that connects the first system 110 and the second system 120, and is a switch that can connect and disconnect the first system 110 and the second system 120. The battery switch 42 is a switch that can connect and disconnect the LiB21 and the second system 120. Specifically, the battery switch 42 is a switch that can connect and disconnect the LiB21 and the backup switch 43 and the supply circuit 53.

The backup switch 43 is a switch that can connect and disconnect the battery switch 42 and the second system 120. The supply circuit 53 is connected in parallel with the backup switch 43, and adjusts the current and voltage output from the LiB21 and the current and voltage input to the LiB21.

The supply circuit 53 is, for example, a step-down circuit such as a DC/DC, and reduces the amount of current output from the LiB 21 and supplies it to the second system 120. This allows the supply circuit 53 to supply an appropriately adjusted weak current from the second power source 20 to the second system 120. The operation of the supply circuit 53 is controlled by the control unit 3.

The supply circuit 53 is not limited to DC/DC and may be a resistor. This allows the supply circuit 53 to supply an appropriately adjusted weak current from the second power source 20 to the second system 120 with an inexpensive and simple configuration.

The first voltage sensor 51 is provided in the first system 110, detects the voltage of the first system 110, and outputs the detection result to the control unit 3. The second voltage sensor 52 is provided in the second system 120, detects the voltage of the second system 120, and outputs the detection result to the control unit 3.

The control unit 3 includes a microcomputer having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., and various circuits. The control unit 3 may also be configured with hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

The control unit 3 controls the operation of the power supply control device 1 by having the CPU execute a program stored in the ROM using the RAM as a working area. The control unit 3 detects a ground fault in the first system 110 or the second system 120 based on the detection results input from the first voltage sensor 51 and the second voltage sensor 52. A specific example of a method for detecting a ground fault by the control unit 3 will be described later.

When the control unit 3 detects a ground fault in the first system 110 or the second system 120, it notifies the automatic driving control device 100 of that fact. When the control unit 3 detects a ground fault in the first system 110 or the second system 120, it may notify the automatic driving control device 100 that automatic driving is not possible. When the control unit 3 does not detect a ground fault in the first system 110 or the second system 120, it may notify the automatic driving control device 100 that automatic driving is possible.

When a power failure such as a ground fault occurs in the first system 110, the control unit 3 shuts off the system switch 41, turns on the battery switch 42 and the backup switch 43, and supplies power from the second power source 20 to the second load 103. When a power failure such as a ground fault occurs in the second system 120, the control unit 3 shuts off the system switch 41, and supplies power from the first power source 10 to the first load 101 and the general load 102 with the battery switch 42 shut off.

As a result, even if a ground fault occurs in one of the systems during autonomous driving, the power supply control device 1 can use the other system and have the autonomous driving control device 100 evacuate the vehicle to a safe location and stop the vehicle. Next, the operation of the power supply control device 1 will be described with reference to Figures 2 to 6.

[2. Normal operation of the power supply control device]
During normal operation when no ground fault has occurred in the first system 110 and the second system 120, the control unit 3 turns off the battery switch 42 as shown in FIG. 2 , turns on the inter-system switch 41 while keeping the backup switch 43 conductive, and supplies power from the first power source 10 to the first load 101, the general load 102, and the second load 103.

[3. Operation of the power supply control device when a ground fault occurs]
Next, the operation of the power supply control device 1 when a ground fault occurs will be described with reference to Figures 3 to 6. As shown in Figure 3, in the power supply control device 1, for example, when a ground fault 200 occurs in the first system 110 or when a ground fault 201 occurs in the second system 120, an overcurrent flows toward the ground fault point, and the voltages detected by the first voltage sensor 51 and the second voltage sensor 52 become equal to or lower than the ground fault threshold value.

Therefore, when the voltage detected by the second voltage sensor 52 becomes equal to or lower than the ground fault threshold, the control unit 3 provisionally determines that a ground fault 200, 201 has occurred in the first system 110 or the second system 120. Then, when the control unit 3 provisionally determines that a ground fault 200, 201 has occurred, it shuts off the inter-system switch 41 and the backup switch 43, and turns on the battery switch 42.

As a result, the connection between the first system 110 and the second system 120 is cut off, power is supplied from the first power source 10 to the first system 110, and power is supplied from the second power source 20 to the second system 120 via the supply circuit 53. At this time, the control unit 3 controls the supply circuit 53 to supply less current to the second system 120 than when actually performing backup. This allows the power supply control device 1 to suppress the amount of discharge from the LiB 21.

When a ground fault 200, 201 occurs in the first system 110 or the second system 120, the voltage detected by the first voltage sensor 51 also becomes equal to or lower than the ground fault threshold. Therefore, the control unit 3 can provisionally determine that a ground fault has occurred in the first system 110 or the second system 120 when the voltage detected by at least one of the first voltage sensor 51 or the second voltage sensor 52 becomes equal to or lower than the ground fault threshold.

Then, if the voltage detected by the first voltage sensor 51 is below the ground fault threshold for a predetermined time or more, and the voltage detected by the second voltage sensor 52 returns to above the ground fault threshold within the predetermined time, the control unit 3 determines that a ground fault 200 has occurred in the first system 110.

In this case, as shown in FIG. 4, the control unit 3 turns on the backup switch 43, supplies power from the second power source 20 to the second load 103 without going through the supply circuit 53, and notifies the automatic driving control device 100 of this fact. As a result, the automatic driving control device 100 can operate the second load 103 using the power supplied from the second power source 20, and can evacuate the vehicle to a safe place and stop it.

In addition, after the control unit 3 provisionally determines that a ground fault has occurred in the first system 110 or the second system 120, if the voltage detected by the second voltage sensor 52 is equal to or lower than the ground fault threshold and the voltage detected by the first voltage sensor 51 returns to exceed the ground fault threshold within a predetermined time, the control unit 3 makes a definite determination that a ground fault 201 has occurred in the second system 120.

In this case, as shown in FIG. 5, the control unit 3 supplies power from the first power source 10 to the first load 101 and notifies the automatic driving control device 100 of this fact. As a result, the automatic driving control device 100 can operate the first load 101 using the power supplied from the first power source 10, and can evacuate the vehicle to a safe place and stop the vehicle.

Here, when a typical power supply control device determines that a ground fault 201 has occurred in the second system 120, it shuts off the battery switch 42 to prevent the LiB 21 from discharging. However, when the ground fault 201 in the second system 120 is subsequently eliminated and normal operation as shown in FIG. 2 is resumed, a problem occurs in that it takes time for the typical power supply control device to supply sufficient power to the second load 103.

Specifically, a typical power supply control device does not supply any power to the second load 103 from the time the battery switch 42 is cut off until the ground fault 201 in the second system 120 is resolved and the inter-system switch 41 is turned on to start normal operation. For this reason, a typical power supply control device takes time from the start of normal operation until the power supplied to the second load 103 gradually increases to the necessary and sufficient power.

The control unit 3 of the power supply control device 1 therefore shuts off the inter-system switch 41 when it detects a ground fault 200, 201 in the first system 110 or the second system 120, and if the ground fault 201 in the second system 120 continues, supplies a weak current to the second load 103 via the supply circuit 53.

Specifically, as shown in FIG. 5, after the control unit 3 has determined that a ground fault 201 has occurred in the second system 120, it controls the supply circuit 53 to supply a weak current from the second power source 20 to the second system 120 via the supply circuit 53, the weak current being smaller than the current supplied when determining whether the system has a ground fault (see FIG. 3).

Then, the control unit 3 obtains the voltage detection result from the second voltage sensor 52 and monitors whether the ground fault 201 of the second system 120 is resolved. At this time, the power supply control device 1 supplies the minimum weak current required for monitoring the ground fault 201 from the second power supply 20 to the second system 120, so that the discharge amount of the LiB 21 can be minimized.

At this time, the control unit 3 can also control the supply circuit 53 to intermittently (e.g., once every few seconds) supply a weak current to the second system 120. This allows the control unit 3 to further reduce the discharge amount of the LiB21.

As shown in FIG. 6, when the ground fault in the second system 120 is eliminated, the voltage detected by the second voltage sensor 52 recovers. When the voltage detected by the second voltage sensor 52 exceeds the ground fault threshold, the control unit 3 determines that the ground fault 201 in the second system 120 has been eliminated.

When the ground fault 201 in the second system 120 is resolved, the control unit 3 turns on the system switch 41 and the backup switch 43, turns off the battery switch 42, and returns to the normal operation state shown in Figure 2.

At this time, the power supply control device 1 supplies a weak current to the second load 103 before turning on the system switch 41, so that the time it takes to supply sufficient power to the second load 103 after returning to the normal operating state can be shortened.

In this way, if the control unit 3 determines that the ground fault 201 in the second system 120 continues after cutting off the system-to-system switch 41, it turns on the battery switch 42, cuts off the backup switch 43, and supplies a weak current to the second load 103 via the supply circuit 53.

As a result, when a ground fault 201 occurs in the second system 120 and then is resolved, the power supply control device 1 can reduce the time it takes to supply sufficient power to the second load 103.

In addition, in the power supply control device 1, if the first load 101 or the general load 102 is temporarily overloaded, rather than if there is a ground fault 200, 201, the voltage detected by the first voltage sensor 51 may temporarily fall below the ground fault threshold. In addition, in the power supply control device 1, if the second load 103 is temporarily overloaded, the voltage detected by the second voltage sensor 52 may temporarily fall below the ground fault threshold.

In this case, in the power supply control device 1, power is continuously supplied from the first power source 10 to the first load 101 and the general load 102, and power is supplied from the second power source 20 to the second load 103 via the supply circuit 53. Therefore, after the control unit 3 provisionally determines that a ground fault 200, 201 has occurred in the first system 110 or the second system 120, if the voltages detected by the first voltage sensor 51 and the second voltage sensor 52 both return to exceeding the ground fault threshold before a predetermined time has elapsed, the control unit 3 determines that this is a temporary voltage drop and that there is no abnormality in the power supply. After that, in order to return to normal operation as shown in FIG. 2, the control unit 3 shuts off the battery switch 42 and re-connects the system switch 41 and the backup switch 43.

[4. Processing Executed by the Control Unit]
Next, a process executed by the control unit 3 of the power supply control device 1 according to the embodiment will be described with reference to Fig. 7. Fig. 7 is a flowchart showing an example of a process executed by the control unit of the power supply control device according to the embodiment.

The control unit 3 repeatedly executes the process shown in FIG. 7 during normal operation. Specifically, as shown in FIG. 7, the control unit 3 first determines whether or not a ground fault has occurred (step S101). If the control unit 3 determines that a ground fault has not occurred (step S101, No), it ends the process and starts the process again from step S101.

When the control unit 3 determines that a ground fault has occurred (step S101, Yes), it shuts off the system switch 41 (step S102), turns on the battery switch 42 (step S103), and shuts off the backup switch 43 (step S104). Then, the control unit 3 controls the supply circuit 53 to supply current from the second power source 20 to the second load 103 via the supply circuit 53 (step S105).

Then, the control unit 3 determines whether the power supply system has returned to normal (step S106). If the control unit 3 determines that the power supply system has returned to normal (step S106, Yes), the process proceeds to step S110. If the control unit 3 determines that the power supply system has not returned to normal (step S106, No), the control unit 3 determines whether a ground fault has occurred in the second system 120 (step S107).

If the control unit 3 determines that the fault is not a ground fault in the second system, i.e., that the fault is a ground fault in the first system 110 (step S107, No), it turns on the backup switch 43 (step S113) and supplies current from the second power source 20 directly to the second load 103 without passing through the supply circuit 53, and ends the process.

If the control unit 3 determines that there is a ground fault in the second system 120 (step S107, Yes), it controls the supply circuit 53 to supply a weak current from the second power source 20 to the second load 103 via the supply circuit 53 (step S108).

Then, the control unit 3 determines whether the ground fault in the second system 120 has been resolved (step S109). If the control unit 3 determines that the ground fault in the second system 120 has not been resolved (step S109, No), the control unit 3 proceeds to step S108.

If the control unit 3 determines that the ground fault in the second system 120 has been resolved (step S109, Yes), it turns on the system switch 41 (step S110), turns off the battery switch 42 (step S111), and turns on the backup switch 43 (step S112). This causes the power supply control device 1 to return to normal operation. The control unit 3 then ends the process and starts the process again from step S101.

Further advantages and modifications may readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and equivalents thereof.

1 Power supply control device 10 First power supply 11 DC/DC
12 PbB
20 Second power supply 21 LiB
3 Control unit 41 Inter-system switch 42 Battery switch 43 Backup switch 51 First voltage sensor 52 Second voltage sensor 53 Supply circuit 100 Automatic operation control device 101 First load 102 General load 103 Second load 110 First system 120 Second system

Claims (4)

a first system that supplies power from a first power source to a first load;
a second system that supplies power from a second power source to a second load;
an inter-system switch provided in a connection path connecting the first system and the second system, the inter-system switch being capable of connecting and disconnecting the first system and the second system;
a supply circuit for supplying a weak current from the second power source to the second load;
a control unit that, when a ground fault is detected in the first system or the second system, shuts off the inter-system switch, and, when the ground fault in the second system continues, supplies a weak current to the second load via the supply circuit. a battery switch capable of connecting and disconnecting the second power source to the second system;
a backup switch connected in parallel to the supply circuit provided between the battery switch and the second system,
The control unit is
2. The power supply control device according to claim 1, wherein, if it is determined that the ground fault in the second system continues after the inter-system switch is cut off, the battery switch is made conductive, the backup switch is cut off, and a weak current is supplied to the second load via the supply circuit. 3. The power supply control device according to claim 1, wherein the supply circuit is a step-down circuit. 3. The power supply control device according to claim 1, wherein the supply circuit is a resistor.

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