Patent ID: 12257924

DETAILED DESCRIPTION OF EMBODIMENTS

An in-vehicle system according to the present disclosure has a configuration in which a main battery connected to a main functional unit and a sub-battery connected to a redundant sub-functional unit are connected in parallel by a relay. In the in-vehicle system having the configuration, when an abnormality is detected in either one of the two batteries, the relay is turned off to electrically separate the main battery and the sub-battery. Then, in the in-vehicle system, when the abnormality is no longer detected in the two batteries, the voltage difference between the main battery and the sub-battery is reduced, and then the relay is turned on again. The above-mentioned control can suppress excessive current flow between the two batteries.

Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings.

Configuration

FIG.1is a diagram showing a schematic configuration of a system10including an in-vehicle system200according to an embodiment of the present disclosure. The system10illustrated inFIG.1includes a direct current-direct current (DCDC) converter (DDC)100, an in-vehicle system200, a first power supply system including first loads111,112,121,122,131,132,141,142, and a second power supply system including second loads221,231. The system10may be mounted, for example, in an electrified vehicle, such as hybrid electric vehicles (HEV) using an electric motor as a power source, plug-in hybrid electric vehicles (PHEV), and battery electric vehicle (BEV).

The DCDC converter100is an electric power converter that may convert high-voltage electric power supplied from a high-voltage battery (not shown), such as a lithium-ion battery into predetermined electric power of a low-voltage and output the converted electric power. The DCDC converter100may output (supply) electric power to the first loads111,112,121,122,131,132,141,142and the second loads221,231. In addition, the DCDC converter100may output (supply) electric power to charge a first battery261and a second battery262of the in-vehicle system200, which will be described later.

(1) First Power Supply System

A first power supply system is a power supply system for supplying electric power to a load (in-vehicle equipment) that operates at a low voltage, which is called an auxiliary machine. The first power supply system includes first loads111,112,121,122,131,132,141,142. The configuration of the first power supply system shown inFIG.1is an example, and the present disclosure is not limited to the configuration.

The first loads111,112are connected to the DCDC converter100and the in-vehicle system200through a relay110(hereinafter referred to as “IGP relay110”) which is turned into a conducting state when an ignition switch of the vehicle is turned on (IGSW-ON). The first loads111,112may be loads for implementing functions of a vehicle that does not need a redundant configuration.

The first loads121,122are connected to the DCDC converter100and the in-vehicle system200through a relay120(hereinafter referred to as “IGR relay120”) which is turned into the conducting state when an ignition switch of the vehicle is turned on (IGSW-ON). The first loads121,122may be loads for implementing functions of a vehicle that needs a redundant configuration.

The first loads131,132are directly connected to the DCDC converter100and the in-vehicle system200without relays. The first loads131,132may be loads for implementing functions of a vehicle that needs a redundant configuration.

The first loads141,142are connected to the DCDC converter100and the in-vehicle system200through a relay140(hereinafter referred to as “+BA relay140”) which is turned into the conducting state when an ignition switch of the vehicle is turned on (IGSW-ON). The first loads141,142may be loads for implementing functions of a vehicle that does not need a redundant configuration.

The turn-on and turn-off of the IGP relay110, IGR relay120, and +BA relay140may be controlled by control means (not shown), or may be controlled by the in-vehicle system200. An excitation type mechanical relay or a semiconductor relay may be used for the relays.

(2) Second Power Supply System

The second power supply system is a power supply system for supplying electric power to a load (in-vehicle equipment) redundantly arranged with respect to the load (in-vehicle equipment) connected to the first power supply system. The second power supply system includes second loads221,231. The configuration of the second power supply system shown inFIG.1is an example, and the present disclosure is not limited to the configuration.

The second load221is connected to the in-vehicle system200and is also connected to the DCDC converter100through relays220,230which will be described later. The second load221is redundantly provided with respect to the first load121.

The second load231is connected to the in-vehicle system200and is also connected to the DCDC converter100through a disconnection relay230. The second load231is redundantly provided with respect to the first load131.

(3) In-Vehicle System

The in-vehicle system200has a configuration for controlling the state of electric power supply to the first loads111,112,121,122,131,132,141,142of the first power supply system and the second loads221,231of the second power supply system.

The in-vehicle system200includes the relay220(hereinafter referred to as “IG2 relay220”), the relay230(hereinafter referred to as “disconnection relay230”), a relay251(hereinafter referred to as “BAT1 relay251”), a relay252(hereinafter referred to as “BAT2 relay252”), the first battery261, the second battery262, a detector310, a determiner320, a relay controller330, and a discharge controller340.

The IG2 relay220, the disconnection relay230, the BAT1 relay251, and the BAT2 relay252switch between the turn-on state and the turn-off state according to control by the relay controller330. An excitation type mechanical relay or a semiconductor relay may be used for the relays.

The first battery261is a power supply capable of supplying electric power to the first loads111,112,121,122,131,132,141,142and the second loads221,231. The first battery261is a stack (assembled battery) configured by connecting a plurality of single battery cells, which are secondary batteries, such as lithium-ion batteries configured to be rechargeable and dischargeable, in series. The first battery261is connected to the first loads111,112,121,122,131,132,141,142of the first power supply system through the BAT1 relay251, and is connected to the second loads221,231of the second power supply system through the BAT1 relay251, the disconnection relay230, and the IG2 relay220.

The second battery262is a power supply capable of supplying electric power to the first loads111,112,121,122,131,132,141,142and the second loads221,231. The second battery262is a stack (assembled battery) configured by connecting a plurality of single battery cells, which are secondary batteries such as lithium-ion batteries configured to be rechargeable and dischargeable, in series. The second battery262is connected to the first loads111,112,121,122,131,132,141,142of the first power supply system through the BAT2 relay252and the disconnection relay230, and is connected to the second loads221,231of the second power supply system through the BAT2 relay252and the IG2 relay220.

Batteries having the same specified voltage are used for the first battery261and the second battery262. Furthermore, one or both of the first battery261and the second battery262may be constituted by a plurality of stacks.

The detector310is a functional unit that detects an abnormality in the first battery261and the second battery262. Examples of battery abnormalities detected by the detector310include a decrease in output voltage and an increase in output current (outflow current) due to a short circuit in a single battery cell, a ground fault in a connection system, or the like. The detection may be performed, for example, based on values detected by voltage sensors, current sensors provided in the first battery261and the second battery262.

The determiner320is a functional unit that acquires a physical quantity indicating the state of the first battery261and a physical quantity indicating the state of the second battery262, and determines the difference between the two acquired physical quantities. Examples of physical quantities that indicate the state of the battery include a voltage value, a current value, a state of charge (SOC), and temperature. The physical quantity may be acquired and calculated, for example, based on values detected by various sensors (voltage, current, temperature, and the like) provided in the first battery261and the second battery262. The difference between the physical quantities is, for example, the difference between the voltage value of the first battery261and the voltage value of the second battery262or the difference between the state of charge of the first battery261and the state of charge of the second battery262.

The relay controller330is a functional unit that controls the turn-on and turn-off states of the IG2 relay220, the disconnection relay230, the BAT1 relay251, and the BAT2 relay252based on a detection result of the battery abnormality in the detector310and a determination result of the difference between physical quantities of the batteries in the determiner320. By the state control of each relay, the relay controller330controls the state of the electric power supply to the first loads111,112,121,122,131,132,141,142and the second loads221,231from the first battery261and the second battery262. The control of the state of each relay will be described later.

The discharge controller340is a functional unit that performs a discharging process for reducing the physical quantity difference (output voltage difference, state-of-charge difference, or the like) of the first battery261or the second battery262, based on the detection result of the battery abnormality in the detector310and the determination result of the difference between physical quantities of the batteries in the determiner320. The discharging process will be described later.

Some or all of the detector310, the determiner320, the relay controller330, and the discharge controller340of the in-vehicle system200described above may be typically an electronic control unit (ECU) including a processor, a memory, an input and output interface, and the like. The electronic control unit implements the functions of each component by reading and executing a program stored in the memory by the processor.

Control

The control performed by the in-vehicle system200according to the present embodiment will be described with further reference toFIGS.2to9.FIG.2is a flowchart illustrating a procedure of a process for electric power supply relay control executed by each component of the in-vehicle system200.

In the following description, as illustrated inFIG.3, in a state of both ignition switches of the vehicle being on (IGSW-ON), all of the IGP relay110, the IGR relay120, +BA relay140, the IG2 relay220, the disconnection relay230, the BAT1 relay251, and the BAT2 relay252are set to be in a connected state. That is, the first loads111,112,121,122,131,132,141,142and the second loads221,231are all in an operable state. In addition, inFIG.3, a thick line indicates that electric power is being supplied.

As illustrated inFIG.4, in a state of the ignition switches of the vehicle being off (IGSW-OFF), with the IGP relay110, the IGR relay120, the +BA relay140, and the IG2 relay220being turned off, and with the disconnection relay230, the BAT1 relay251, and the BAT2 relay252being turned on, a control is executed, such that electric power is supplied just to some loads (the first load131, the first load132, and the second load231) that needs minimal operation. In addition, inFIG.4, a thick line indicates that electric power is being supplied.

When the detector310detects an abnormality in the first battery261or the second battery262while the ignition switch of the vehicle is on (IGSW-ON), an electric power supply relay control shown inFIG.2is started.

Step S21

The relay controller330turns off the disconnection relay230. Thereby, the first battery261and the second battery262are electrically separated. At this time, the relay controller330may turn off the BAT1 relay251or the BAT2 relay252inserted on the side of the battery in which the abnormality is detected, at the same time as the turn-off of the disconnection relay230. By turning off the relays, it is possible to prevent current from continuing to flow out of the battery, for example, in the event of a ground fault in the power supply system.

FIG.5shows an example of relay control when an abnormality is detected in the first battery261. In the example ofFIG.5, the IGP relay110, the IGR relay120, the +BA relay140, the disconnection relay230, and the BAT1 relay251are turned off, and the IG2 relay220and the BAT2 relay252are turned on. With such relay control, even when an abnormality is detected in the first battery261, electric power can be continuously supplied from the normal second battery262to the second loads221,231of the redundant configuration, and the operations of the loads can be maintained. In addition, inFIG.5, a thick line indicates that electric power is being supplied.

Further,FIG.6shows an example of relay control when an abnormality is detected in the second battery262. In the example ofFIG.6, the disconnection relay230and BAT2 relay252are turned off, and the IGP relay110, the IGR relay120, the +BA relay140, the IG2 relay220, and the BAT1 relay251are turned on. With such relay control, even when an abnormality is detected in the second battery262, electric power can be continuously supplied from the normal first battery261to the first loads111,112,121,122,131,132,141,142, and the operations of the loads can be maintained. In addition, inFIG.6, a thick line indicates that electric power is being supplied.

When at least the disconnection relay230is turned off by the relay controller330, the process proceeds to step S22.

Step S22

The detector310determines whether the abnormality in the first battery261and the second battery262is no longer detected after the relay controller330turns off the disconnection relay230. The determination is made to determine an event in which there is no problem with the system10itself, such as a case in which a momentary erroneous determination is made that a battery is abnormal due to disturbance noise or the like and then return to normal is made.

When the detector310determines that the abnormality in the first battery261and the second battery262is no longer detected (Yes in step S22), the process proceeds to step S23. On the other hand, while the abnormality in the first battery261or the second battery262is detected (No in step S22), the disconnection relay230remains off.

Step S23

The determiner320acquires a physical quantity (voltage, state of charge, or the like) indicating the state of the first battery261and a physical quantity (voltage, state of charge, or the like) indicating the state of the second battery262, and calculates the difference between the acquired two acquired physical quantities (voltage difference, state-of-charge difference, or the like). When the in-vehicle system200has three or more batteries (or stacks), the difference between the maximum value and the minimum value of a plurality of physical quantities may be calculated.

When the determiner320calculates the difference between the physical quantities of the first battery261and the second battery262, the process proceeds to step S24.

Step S24

The determiner320determines whether the calculated difference between the physical quantities of the first battery261and the second battery262satisfies a predetermined condition. The determination is made to determine whether or not there is a risk that a large amount of current will flow between the batteries when the first battery261and the second battery262are connected. Examples of a large amount of current include current that may cause deterioration of single battery cells, current that may lead to failures in circuit components, and current that may cause discomfort to occupants of the vehicle. Therefore, the predetermined condition is set to restrain such a large amount of current from flowing between the batteries.

For example, when the physical quantity is voltage, it is possible to set the voltage difference corresponding to the upper limit current value (withstand current value) that the battery can withstand as the first threshold value, and to determine that the predetermined condition is satisfied when the absolute value difference (voltage difference) between the voltage of the first battery261and the voltage of the second battery262is less than or equal to the first threshold value. Alternatively, when the physical quantity is the state of charge, it is possible to set the state-of-charge difference corresponding to the withstand current value as the second threshold value, and to determine that the predetermined condition is satisfied when the absolute value difference (state-of-charge difference) between the state of charge of the first battery261and the state of charge of the second battery262is less than or equal to the second threshold value.

The first battery261and the second battery262are affected by temperature, and accordingly, the determination as to whether the difference between physical quantities of the first battery261and the second battery262satisfies a predetermined condition may be made based on the temperature of the batteries in addition to the first threshold value and the second threshold value.FIG.9shows an example of a condition matching determination map using the difference between absolute values (difference in state of charge) of the state of charge of the first battery261and the state of charge of the second battery262and the battery temperature as parameters. In the example ofFIG.9, a battery state of “1” on the map is determined to satisfy the predetermined condition, and a battery state of “0” on the map is determined not to satisfy the predetermined condition.

When the determiner320determines that the difference between the physical quantities of the first battery261and the second battery262satisfies the predetermined condition (Yes in step S24), the process proceeds to step S26. When the determiner320determines that the difference between the physical quantities of the first battery261and the second battery262does not satisfy the predetermined condition (No in step S24), the process proceeds to step S25.

Step S25

The discharge controller340executes the discharging process for decreasing the physical quantity (voltage, state of charge, or the like) of the first battery261or the second battery262. In general, it is estimated that the physical quantity of the battery in which the abnormality is detected by the detector310, which triggers the start of the electric power supply relay control, remains high without being consumed. Therefore, the discharge controller340executes a predetermined discharging process on the battery in which the abnormality is detected. Specifically, the discharging process is performed by consuming electric power by a load that is connected without going through the disconnection relay230.

FIG.7shows an example of the discharging process when an abnormality is detected in the first battery261and the electric power supply relay control is started. In the example ofFIG.7, by turning on the IGP relay110, the IGR relay120, the +BA relay140, and the BAT1 relay251in a state in which the disconnection relay230is turned off, the electric power of the first battery261is consumed by the first loads111,112,121,122,131,132,141,142(discharging operation), while the operation of the second loads221,231are stopped. In addition, inFIG.7, a thick line indicates that electric power is being supplied. Thereby, the physical quantity (voltage, state of charge, or the like) of the first battery261gradually decreases and approaches the physical quantity (voltage, state of charge, or the like) of the second battery262.

FIG.8shows an example of the discharging process when an abnormality is detected in the second battery262and the electric power supply relay control is started. In the example ofFIG.8, by turning on the IG2 relay220and the BAT2 relay252in the state in which the disconnection relay230is turned off, the electric power of the second battery262is consumed by the second loads221,231(discharging operation), while the operation of the first loads111,112,121,122,131,132,141,142are stopped. In addition, inFIG.8, a thick line indicates that electric power is being supplied. Thereby, the physical quantity (voltage, state of charge, or the like) of the second battery262gradually decreases and approaches the physical quantity (voltage, state of charge, or the like) of the first battery261.

When the discharge controller340executes the discharging process for decreasing the physical quantity (voltage, state of charge, or the like) of the first battery261or the second battery262, the process proceeds to step S24.

Step S26

The relay controller330turns on the disconnection relay230. At this time, the relay controller330also turns on the IGP relay110, the IGR relay120, the +BA relay140, the IG2 relay220, the BAT1 relay251, and the BAT2 relay252. Thereby, the first battery261and the second battery262are electrically connected, and the system10returns to the power supply state shown inFIG.3.

When the disconnection relay230and the like are turned on by the relay controller330, the electric power supply relay control ends.

Action and Effect

As described above, the in-vehicle system200according to an embodiment of the present disclosure has the configuration in which the first battery261connected to the main functional unit (first load) to be able to supply electric power and the second battery262connected to a sub-functional unit (second load) of the redundant configuration to be able to supply electric power are connected in parallel with the disconnection relay230, in which when an abnormality is detected in either one of the first battery261and the second battery262, the disconnection relay230is turned off to electrically separate the first battery261and the second battery262.

With the control, even when an abnormality occurs in one battery among the batteries, the in-vehicle system200can continue to supply electric power to a load that demands the electric power from the other battery at a normal state, whereby it is possible to continue to perform operations of functions needed in the system10(for example, evacuation behavior in autonomous driving).

Further, in the in-vehicle system200according to an embodiment of the present disclosure, when the abnormality in the first battery261and the second battery262is no longer detected after the disconnection relay230is turned off, the difference between physical quantities of (voltage, state of charge, or the like) of the first battery261and the second battery262is reduced to satisfy the condition for preventing a large amount of current from flowing, and then the disconnection relay230is turned on back to reassume the system10.

With the control, the in-vehicle system200can restrain excessive current flowing between the first battery261and the second battery262.

An embodiment of the disclosed technology has been described above, but the present disclosure can be understood not only as an in-vehicle system, but also as a method executed by an in-vehicle system equipped with a processor or memory, a control program for the method, a computer-readable non-transitory recording medium storing the control program, a vehicle equipped with the in-vehicle system, or the like.

The in-vehicle system and the like of the present disclosure can be used, for example, when electric power supply of a vehicle is controlled.