JP2020089032A - Control device for vehicle power source - Google Patents

Abstract

To securely restore an amount of charge of a battery when the amount of charge of the battery becomes lower than a predetermined lower limit value.SOLUTION: A control device for a vehicle power source includes: an ISG 13 comprising a power generation function and an electrically driving function; a high-voltage battery (lithium ion battery) 14 which transfers power between the same and the ISG 13; and a controller 10 configured to set a target SOC to be applied for the SOC in order to maintain the SOC of the high-voltage battery 14 within a predetermined range, to perform SOC control on the ISG 13 so that an actual SOC of the high-voltage battery 14 becomes the target SOC. The controller 10 sets a certain target voltage to be applied for the voltage of the high-voltage battery 14, and performs a constant voltage control on the ISG 13 so that the actual voltage of the high-voltage battery 14 becomes the target voltage when the SOC of the high-voltage battery 14 is lower than the lower limit value within the predetermined range.SELECTED DRAWING: Figure 6

Description

The present invention relates to a motor generator driven by an engine and a power supply control device for a vehicle provided with a battery for exchanging electric power with the motor generator.

BACKGROUND ART Conventionally, an engine that burns an air-fuel mixture containing fuel to generate power for a vehicle, a motor generator that has a power generation function that is driven by this engine to generate power, and an electric function that generates power for driving the vehicle, A vehicle (typically a hybrid vehicle) is known that has a battery that supplies the electric power that is being charged to the motor generator so as to generate electric power from the motor generator while charging the electric power generated by the motor generator. ing.

For example, in Patent Document 1, a hybrid that performs control for maintaining the SOC (State Of Charge) (in other words, charge amount, remaining capacity, charge rate) of the battery within a predetermined range in order to prevent over-discharge of the battery. A vehicle is disclosed. In particular, in the technique disclosed in Patent Document 1, when the SOC of the battery becomes less than a predetermined value, the output of the voltage converter that converts the electric power of the battery into the electric power of low potential is limited, thereby Over-discharge of the battery is prevented by reducing the power consumption of the battery by the converter.

Japanese Patent Laid-Open No. 2005-045883

Conventionally, in order to maintain the SOC (charge amount) of the battery within a predetermined range, control of the motor generator (hereinafter referred to as “SOC control”) is performed so that the SOC of the battery becomes the target SOC. However, for example, when an abnormality occurs such as when power generation of the motor generator is restricted, the SOC of the battery may be less than the lower limit value of the predetermined range even if the SOC control is performed. In that case, the SOC of the battery may further decrease and the battery may deteriorate. Therefore, when the SOC of the battery becomes less than the lower limit value of the predetermined range, it is desirable to surely recover the SOC of the battery. It was difficult to reliably recover the SOC of the battery only by the conventional SOC control.

The present invention has been made to solve the above-described problems, and can reliably recover the charge amount of the battery when the charge amount (SOC) of the battery becomes less than a predetermined lower limit value. An object is to provide a power supply control device for a vehicle.

In order to achieve the above-mentioned object, the present invention is a power supply control device for a vehicle, the motor generator having a power generation function of being driven by an engine to generate power and an electric power function of generating power for driving the vehicle. And a battery configured to supply the charged electric power to the motor generator so as to generate electric power from the motor generator while charging the electric power generated by the motor generator, and the charge amount of the battery within a predetermined range. In order to maintain, the target charge amount to be applied to the battery charge amount is set, and the first control is executed for the motor generator so that the actual charge amount of the battery becomes the target charge amount. The controller has a fixed target voltage to be applied to the voltage of the battery when the charge amount of the battery is less than the lower limit value of the predetermined range. The second control is performed on the motor generator so that the actual voltage becomes the target voltage.

In the present invention thus configured, in order to maintain the charge amount (SOC) of the battery within a predetermined range, the controller normally controls the motor generator so that the charge amount of the battery becomes the target charge amount. 1 control is performed, but when the charge amount of the battery is less than the lower limit value of the predetermined range, the second control is performed on the motor generator so that the battery voltage becomes a constant target voltage. According to the second control, the voltage of the battery is forcibly controlled to reach the target voltage, so that the charge amount of the battery can be recovered preferentially. Therefore, according to the present invention, when the charge amount of the battery becomes less than the lower limit value, the charge amount of the battery can be promptly and reliably recovered. Therefore, it is possible to effectively prevent the charge amount from becoming extremely small and the battery from deteriorating.

In the present invention, preferably, when the battery is the first battery, the second battery having a voltage lower than that of the first battery, the power charged in the first battery and the power charged in the second battery A first electric load that is supplied with at least one of them and operates, and a first battery that is provided between the first battery and the first electric load, reduces the voltage output from the first battery, and outputs the voltage to the first electric load. And a voltage converter for performing the second control, and the controller is configured to stop the voltage converter when executing the second control.
According to the present invention thus configured, the controller stops the voltage converter when executing the second control, and transfers the voltage from the first battery to the first voltage electric load via the voltage converter. Prohibit output. Thereby, the discharge from the first battery can be suppressed and the recovery of the charge amount can be prioritized. Thereby, the charge amount of the battery can be recovered more quickly.

In the present invention, preferably, the first battery is further supplied with charged electric power, and further has a second electric load that operates at a higher voltage than the first electric load, and the controller executes the second control. In addition, the voltage converter is stopped and the second electric load is further stopped.
According to the present invention configured as described above, the controller stops both the voltage converter and the second electric load when executing the second control, so that the discharge from the first battery is reliably suppressed. However, the restoration of the charge amount can be given the highest priority. Thereby, the charged amount of the battery can be recovered more effectively and promptly.

In the present invention, preferably, the controller is configured to continuously execute the second control after the charge amount of the battery becomes equal to or more than the lower limit value due to the execution of the second control.
In the situation where the second control is executed once, there is a fact that the amount of charge of the battery becomes less than the lower limit value as a result of occurrence of some abnormality. This anomaly can reoccur, which can degrade the battery. Therefore, the controller continues to execute the second control during the current driving cycle even if the charge amount of the battery has recovered to the lower limit value or more. Thereby, the battery can be protected more reliably.

In the present invention, preferably, when the battery is the first battery, the second battery having a voltage lower than that of the first battery, the power charged in the first battery and the power charged in the second battery A first electric load that is supplied with at least one of them and operates, and a first battery that is provided between the first battery and the first electric load, reduces the voltage output from the first battery, and outputs the voltage to the first electric load. And a voltage converter for performing the second control, the controller is configured to stop the voltage converter when executing the second control, and the charge amount of the first battery is lower than the lower limit value by executing the second control. After the above, the second control is continuously executed, while the stop of the voltage converter is released and the operation of the voltage converter is restarted.
According to the present invention configured as described above, the controller continuously executes the second control after the first battery charge amount becomes equal to or more than the lower limit value due to the execution of the second control, while performing the voltage conversion. Release the stoppage of the vessel and restart its operation. By doing so, output from the first battery to the first electric load via the voltage converter is restarted, and discharge from only the second battery for operating the first electric load is suppressed. As a result, it is possible to appropriately prevent the harmful effects caused by the continuous power-out from the second battery.

In the present invention, preferably, the controller is configured to switch the control to be executed from the first control to the second control when the charge amount of the battery falls below a predetermined value smaller than the lower limit value. There is.
According to the present invention having such a configuration, it is possible to cope with the decrease in the charge amount of the battery by the first control as much as possible. That is, it is possible to appropriately prevent the harmful effects caused by the frequent execution of the second control.

According to the vehicle power supply control device of the present invention, it is possible to reliably recover the charge amount of the battery when the charge amount (SOC) of the battery becomes less than the predetermined lower limit value.

FIG. 1 is a block diagram schematically showing an overall configuration of a hybrid vehicle to which a power supply control device for a vehicle according to an embodiment of the present invention is applied. FIG. 1 is a block diagram schematically showing an electrical configuration of a vehicle power supply control device according to an embodiment of the present invention. It is a block diagram which shows roughly the structural example of the controller by embodiment of this invention. 6 is a time chart for explaining SOC control according to the embodiment of the present invention. 6 is a time chart for explaining constant voltage control according to the embodiment of the present invention. It is a flow chart which shows control processing by an embodiment of the present invention.

Hereinafter, a power supply control device for a vehicle according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

[Device configuration]
First, a device configuration relating to a vehicle power supply control device according to an embodiment of the present invention will be described.

FIG. 1 is a block diagram schematically showing an overall configuration of a hybrid vehicle to which a power supply control device for a vehicle according to an embodiment of the present invention is applied. As shown in FIG. 1, the hybrid vehicle 1 mainly includes an engine 11, a gear drive starter 12, an ISG (Integrated Starter Generator) 13, a lithium ion battery 14, a DC-DC converter 17, and a lead storage battery. 19, a high-voltage electric load 20, and a low-voltage electric load 21. In the following, since the voltage (nominal voltage) of the lithium ion battery 14 is higher than the voltage (nominal voltage) of the lead storage battery 19, the lithium ion battery 14 is appropriately referred to as a “high voltage battery 14”, and the lead storage battery 19 is appropriately referred to as “high voltage battery 14.” Called low voltage battery 19".

The engine 11 is an internal combustion engine (gasoline engine or diesel engine) that generates the driving force of the hybrid vehicle 1. The driving force of the engine 11 is transmitted to the wheels 5 via the output shaft 9, the transmission 2, the speed reducer 3 and the drive shaft 4. A gear drive starter 12 is connected to the output shaft 9 of the engine 11 via a gear. When the user turns on an ignition switch (not shown), the gear-driven starter 12 starts the engine 11 using the electric power supplied from the low-voltage battery 19. The hybrid vehicle 1 also has a brake system 7 for applying a braking force to the vehicle 1 according to the operation of the brake pedal by the driver. The brake system 7 is composed of, for example, an electric brake.

The ISG 13 is a motor generator having a power generation function that is driven by the engine 11 to generate power and an electric function that generates a driving force of the hybrid vehicle 1. The ISG 13 is connected to the output shaft 9 of the engine 11 via the belt 8. Further, the ISG 13 is electrically connected to the high voltage battery 14 via the resistor 6a and the switch elements 6b and 6c. When the ISG 13 and the high-voltage battery 14 are first connected, the switch element 6b on the side where the resistor 6a is provided is turned on to prevent damage to electronic components and the like due to inrush current. Then, after this, the switch element 6c is turned on to maintain the connection between the ISG 13 and the high voltage battery 14. Basically, when the ignition switch (not shown) is turned on, the ISG 13 and the high voltage battery 14 are connected, and when the ignition switch is turned off, the connection between the ISG 13 and the high voltage battery 14 is released. It

When the ISG 13 operates by the power generation function, the ISG 13 generates power by rotating a rotor that rotates in conjunction with the output shaft 9 of the engine 11 in a magnetic field. The ISG 13 has a built-in rectifier (not shown), and uses the rectifier to convert the generated AC power into DC power. The electric power generated by the power generation of the ISG 13 is supplied to the high-voltage battery 14 or the low-voltage battery 19 to be charged, or supplied to the high-voltage electric load 20 or the low-voltage electric load 21. On the other hand, the ISG 13 drives the output shaft 9 of the engine 11 via the belt 8 by using the electric power charged in the high-voltage battery 14 when operating by the electric function. In addition, in order to adjust the tension of the belt 8 at the time of switching between the operation by the power generation function and the operation by the electric function in the ISG 13, it is preferable to apply a pendulum type variable tension tensioner (decoupling alternator tensioner) to the belt 8. Good.

The high voltage battery 14 includes a plurality of lithium ion batteries connected in series, and the low voltage battery 19 includes a plurality of lead storage batteries connected in series. For example, the high voltage battery 14 has a nominal voltage of 24 VDC and the low voltage battery 19 has a nominal voltage of 12 VDC. The high-voltage battery 14 and the low-voltage battery 19 store electric energy by a chemical reaction and are not suitable for rapid charging/discharging, but easily store a charging capacity and thus store a relatively large amount of electric power. It has the property of being able to.

The DC-DC converter 17 is provided between the high voltage battery 14 and the low voltage battery 19. The DC-DC converter 17 changes the input voltage by on/off switching of a built-in switching element and outputs the changed voltage. Specifically, the DC-DC converter 17 steps down the voltage of the electric power supplied from the high voltage battery 14 side to the low voltage battery 19 side. For example, the DC-DC converter 17 steps down the voltage of about 24V DC supplied from the high voltage battery 14 side to about 12V DC and outputs it to the low voltage battery 19 side. The bypass switch element 18 is connected in parallel to the DC-DC converter 17. The bypass switch element 18 short-circuits between the input terminal and the output terminal of the DC-DC converter 17 when turned on, and opens the input terminal and the output terminal of the DC-DC converter 17 when turned off. To do.

The high-voltage electric load 20 is an electric load operating at a voltage of, for example, DC 24V, and the low-voltage electric load 21 is an electric load operating at a voltage lower than that of the high-voltage electric load 20, for example, a voltage of about DC 12V. The high-voltage electric load 20 is supplied with at least one of the electric power generated by the power generation of the ISG 13 and the electric power charged in the high-voltage battery 14. Further, the low-voltage electric load 21 is supplied with at least one of the electric power generated by the power generation of the ISG 13, the electric power charged in the high-voltage battery 14, and the electric power charged in the low-voltage battery 19. In one example, the high-voltage electric load 20 includes a heater (such as a seat heater), and the low-voltage electric load 21 includes an electric power steering mechanism (EAPS), an air conditioner, an audio device, and the like.

Next, FIG. 2 is a block diagram schematically showing an electrical configuration of a vehicle power supply control device according to an embodiment of the present invention.

In the present embodiment, the hybrid vehicle 1 is controlled by the controller 10 as shown in FIG. The controller 10 includes one or more processors, various programs that are interpreted and executed on the processors (including a basic control program such as an OS and an application program that is started on the OS and realizes a specific function), and programs. And a computer having an internal memory such as a ROM or RAM for storing various data.

Specifically, as shown in FIG. 2, the controller 10 mainly corresponds to parameters detected by the converter input voltage sensor 30, the battery current sensor 33, the battery voltage sensor 34, and the battery temperature sensor 35, respectively. The detection signal for The converter input voltage sensor 30 detects the input voltage of the DC-DC converter 17. The battery current sensor 33 detects the current flowing through the high voltage battery 14. The battery voltage sensor 34 detects the terminal voltage of the high voltage battery 14. The battery temperature sensor 35 detects the terminal temperature of the high voltage battery 14.

Further, the controller 10 is based on the detection signals from the sensors 30, 33, 34 and 35 described above, the ISG 13, the DC-DC converter 17, the gear drive starter 12, the switch elements 6b and 6c, the bypass switch element 18, and the high level. A control signal is output to each of the voltage electric load 20 and the low voltage electric load 21. In this way, the controller 10 performs the power generation operation and the electric operation of the ISG 13, the step-down operation by the DC-DC converter 17, the driving and stopping of the high-voltage electric load 20, the low-voltage electric load 21, and the gear drive starter 12, and the switch. It controls on/off of the elements 6b and 6c and the bypass switch element 18.

Typically, the controller 10 is configured to execute a plurality of controls defined in accordance with the driving state of the hybrid vehicle 1 for the purpose of improving fuel economy, etc., using at least the ISG 13. The plurality of controls include acceleration assist control for generating power from the ISG 13 to assist the acceleration by the engine 11 when the hybrid vehicle 1 accelerates, and regenerative power generation of the ISG 13 when the hybrid vehicle 1 decelerates. Deceleration regeneration control, and for supplying electric power to the high-voltage electric load 20 and the low-voltage electric load 21 when a predetermined condition is satisfied (for example, a situation where an increase in the load of the engine 11 due to the power generation of the ISG 13 should be suppressed). Non-power generation control for prohibiting power generation of the ISG 13 and idling for automatically stopping the engine 11 when the hybrid vehicle 1 stops and then generating power from the ISG 13 and restarting the engine 11 when the hybrid vehicle 1 starts to move thereafter. And stop control.

Further, the controller 10 performs control for operating each of the high voltage electric load 20 and the low voltage electric load 21. Specifically, when operating the high-voltage electric load 20, the controller 10 supplies at least one of the electric power generated by the power generation of the ISG 13 and the electric power charged in the high-voltage battery 14 to the high-voltage electric load 20. Control to supply to. Further, when operating the low-voltage electric load 21, the controller 10 includes at least the electric power generated by the power generation of the ISG 13, the electric power charged in the high-voltage battery 14, and the electric power charged in the low-voltage battery 19. Control is performed to supply either of them to the low-voltage electric load 21.

The "vehicle power supply control device" in the present invention mainly includes an ISG 13 as a "motor generator", a high-voltage battery 14 as a "battery (first battery)", and a low voltage as a "second battery". Voltage battery 19, high-voltage electric load 20 as "second electric load", low-voltage electric load 21 as "first electric load", DC-DC converter 17 as "voltage converter", and control And the container 10.

[Control content]
Next, the control content according to the embodiment of the present invention will be described.

Before describing the control content, a specific configuration example of the controller 10 according to the embodiment of the present invention will be described with reference to FIG. FIG. 3 is a block diagram schematically showing a configuration example of the controller 10 according to the embodiment of the present invention. As shown in FIG. 3, in the present embodiment, the controller 10 includes a PCM (Power-train Control Module) 31 that totally controls a power train including an engine 11 and a microcomputer (microcomputer) in the ISG 13. 32 and. Basically, the PCM 31 outputs a command to the microcomputer 32 in the ISG 13 in order to control the power generation operation and the electric operation of the ISG 13 according to various states in the hybrid vehicle 1, and the microcomputer 32 outputs the command from the PCM 31. In order to realize the command, the operation is controlled inside the ISG 13. Details of the control performed by the PCM 31 and the microcomputer 32 will be described later.

The controller 10 includes various controllers other than the PCM 31 and the microcomputer 32 described above. For example, the controller 10 includes a microcomputer in the DC-DC converter 17, a BECM (Battery Energy Control Module) that controls the high voltage battery 14, and the like.

Next, two controls (SOC control and constant voltage control) performed by the controller 10 on the ISG 13 in the embodiment of the present invention will be specifically described with reference to FIGS. 4 and 5. The SOC control corresponds to the "first control" in the present invention, and the constant voltage control corresponds to the "second control" in the present invention.

FIG. 4 is a time chart for explaining SOC control according to the embodiment of the present invention. In FIG. 4, the upper graph shows a time chart of the SOC of the high-voltage battery 14 (the solid line shows the actual SOC, the alternate long and short dash line shows the target SOC), and the lower graph shows the time chart of the target torque of ISG 13. Shows. In the lower graph of FIG. 4, positive torque (torque above 0) indicates the torque generated by the ISG 13 by the electric operation (in this case, the electric power charged in the high-voltage battery 14 is discharged), and the negative torque is negative. Indicates the torque generated by the power generation operation of the ISG 13 (in this case, the high-voltage battery 14 is charged with the power generated by the ISG 13). This applies to FIG. 5 as well.

The controller 10 executes SOC control in order to maintain the SOC of the high voltage battery 14 within a predetermined range defined by the upper limit value S1 (for example, 80%) and the lower limit value S2 (for example, 20%). The controller 10 executes this SOC control during normal times. Specifically, the controller 10 sets a target SOC (for example, 60%) to be applied to the SOC of the high voltage battery 14 as the SOC control, and the actual SOC of the high voltage battery 14 becomes the target SOC. The ISG 13 is controlled as described above (see the upper graph in FIG. 4). In particular, the controller 10 sets the target torque to be generated from the ISG 13 based on the difference between the set target SOC and the actual SOC (actual SOC) of the high voltage battery 14, and the ISG 13 is set so as to generate this target torque. Control (see lower graph in FIG. 4). Specifically, the controller 10 sets the target torque within a range defined by the torque T1 corresponding to the discharge limit value of the high voltage battery 14 and the torque T2 corresponding to the charge limit value of the high voltage battery 14. ..

The SOC control as described above is realized by the PCM 31 and the microcomputer 32 of the controller 10 (see FIG. 3) as follows. First, the PCM 31 sets the target torque to be generated from the ISG 13 within the range defined by the torque T1 corresponding to the discharge limit value and the torque T2 corresponding to the charge limit value, based on the difference between the target SOC and the actual SOC. The target torque is set and the target torque is output to the microcomputer 32 of the ISG 13. The microcomputer 32 of the ISG 13 controls the operation of the ISG 13 so as to realize the target torque input from the PCM 31. Then, when the microcomputer 32 controls the ISG 13 in this manner, the microcomputer 32 outputs the torque (actual torque) actually generated from the ISG 13 and the voltage (actual voltage) actually generated from the ISG 13 to the PCM 31. The PCM 31 controls the engine 11 based on the actual torque and the actual voltage thus input from the microcomputer 32. Specifically, in the PCM 31, the torque obtained by applying the actual torque generated by the ISG 13 to the torque of the engine 11 (the torque obtained by adding or subtracting the torque of the ISG 13 to the engine torque) becomes the torque requested by the driver. The engine 11 is controlled so that

Next, FIG. 5 is a time chart for explaining the constant voltage control according to the embodiment of the present invention. 5, the upper graph shows a time chart of the target voltage of the ISG 13, the center graph shows a time chart of the actual SOC of the high voltage battery 14, and the lower graph shows a time chart of the actual torque of the ISG 13. ..

When the actual SOC of the high-voltage battery 14 becomes less than the predetermined value S3 (time t1), the controller 10 promptly and reliably recovers the SOC of the high-voltage battery 14 from the viewpoint of protecting the high-voltage battery 14. Therefore, constant voltage control is executed. A value smaller than the lower limit value S2 described above (for example, 15%) is applied to the predetermined value S3. The case where the SOC of the high-voltage battery 14 becomes less than the predetermined value S3 includes the case where the power generation of the ISG 13 is limited. In one example, when the temperature of the ISG 13 is equal to or higher than a predetermined temperature (that is, when the temperature is high), the power generation of the ISG 13 is limited. In this case, in order to prevent the ISG 13 from overheating, the power generation of the ISG 13 is limited. In another example, the power generation of the ISG 13 is limited when the output of the engine 11 is limited to less than a predetermined value (typically, when the engine 11 is idling in a high altitude of extreme heat or cold). In this case, in order to prevent the engine 11 from stalling, the power generation of the ISG 13 is limited. Further, even when an electronic component (sensor, ISG 13 or the like) in the system fails, the SOC of the high voltage battery 14 may be less than the predetermined value S3.

Specifically, as a constant voltage control, the controller 10 sets a constant target voltage V1 (that is, a fixed voltage) to be applied to the voltage of the high voltage battery 14 to determine the actual voltage of the high voltage battery 14. Is controlled to the target voltage V1 (see the upper graph of FIG. 5). In one example, the target voltage V1 is a voltage (eg, 22.5V) required to set the SOC of the high-voltage battery 14 to an intermediate value (eg, 60%) between the upper limit value S1 and the lower limit value S2 described above. ) Applies. By such constant voltage control, after time t1, the ISG 13 performs a power generation operation to generate torque (negative torque) (see the lower graph in FIG. 5), and thus the power generated by the ISG 13 is generated by the high voltage battery. It is charged to 14. As a result, the actual SOC of the high-voltage battery 14 rapidly rises to the SOC value S4 corresponding to the target voltage V1, for example, the intermediate value S4 between the upper limit value S1 and the lower limit value S2 (the center of FIG. 5). See the graph). After that, the actual SOC of the high voltage battery 14 is maintained at S4.

The constant voltage control as described above is realized by the PCM 31 and the microcomputer 32 of the controller 10 (see FIG. 3) as follows. First, the PCM 31 sets a constant target voltage V1 to be applied to the voltage of the high-voltage battery 14 while considering the range defined by the discharge limit value and the charge limit value of the high-voltage battery 14, The target voltage V1 is output to the microcomputer 32 of the ISG13. The microcomputer 32 of the ISG 13 adjusts the actual voltage of the ISG 13 to the target voltage V1 based on the difference between the target voltage V1 and the actual voltage (actual voltage) of the ISG 13 in order to realize the target voltage V1 input from the PCM 31. , ISG13 voltage is feedback controlled. By performing the feedback control in the ISG 13 as described above, the voltage of the ISG 13 can be quickly adjusted. Then, when the microcomputer 32 controls the ISG 13 in this manner, the microcomputer 32 outputs the torque (actual torque) actually generated from the ISG 13 and the voltage (actual voltage) actually generated from the ISG 13 to the PCM 31. The PCM 31 controls the engine 11 based on the actual torque and the actual voltage thus input from the microcomputer 32. Specifically, the PCM 31 controls the engine 11 so that the torque obtained by applying the torque generated by the ISG 13 to the torque of the engine 11 becomes the torque requested by the driver.

Next, with reference to FIG. 6, a specific process executed by the controller 10 in the embodiment of the present invention will be described. FIG. 6 is a flowchart showing the control processing according to the embodiment of the present invention. This flow is repeatedly executed by the controller 10 in a predetermined cycle after the ignition switch is turned on.

First, in step S101, the controller 10 acquires various information of the hybrid vehicle 1. Specifically, the controller 10 acquires the parameters and the like detected by the sensors 30, 33, 34, 35 described above.

Next, in step S102, the controller 10 determines whether the SOC of the high voltage battery 14 is less than the first predetermined value. As the first predetermined value, a value smaller than a lower limit value S2 that defines a predetermined range in which the SOC of the high voltage battery 14 should be maintained in the SOC control is applied. Specifically, the first predetermined value corresponds to the predetermined value S3 shown in FIG. 5, and is, for example, 15%. The controller 10 controls the current of the high voltage battery 14 detected by the battery current sensor 33, the voltage of the high voltage battery 14 detected by the battery voltage sensor 34, and the temperature of the high voltage battery 14 detected by the battery temperature sensor 35. The SOC of the high voltage battery 14 is obtained based on the above. Specifically, the controller 10 determines the initial SOC of the high voltage battery 14 based on the voltage (corresponding to the open circuit voltage (OCV)) detected by the battery voltage sensor 34 when the ignition switch is turned on, and thereafter, , SOC of the high voltage battery 14 is obtained by accumulating the charge amount and the discharge amount corresponding to the current detected by the battery current sensor 33 based on the initial SOC. The controller 10 also determines the SOC in consideration of the temperature of the high voltage battery 14 detected by the battery temperature sensor 35. If the open circuit voltage cannot be acquired, the SOC used in the previous driving cycle may be applied as the initial SOC.

When it is determined that the SOC of the high voltage battery 14 is equal to or higher than the first predetermined value as a result of the determination in step S102 (step S102: No), the controller 10 proceeds to step S103. In this case, since the SOC of the high voltage battery 14 is secured, the controller 10 executes normal SOC control (S103). Specifically, the controller 10 is a target to be applied to the SOC of the high voltage battery 14 in order to maintain the SOC of the high voltage battery 14 within a predetermined range defined by the upper limit value S1 and the lower limit value S2. The SOC is set, and the ISG 13 is controlled so that the actual SOC of the high-voltage battery 14 becomes the target SOC. In particular, the controller 10 should generate the target from the ISG 13 within the range defined by the discharge limit value and the charge limit value of the high voltage battery 14 based on the difference between the target SOC and the actual SOC of the high voltage battery 14. The torque is set, and the ISG 13 is controlled so that this target torque is generated. After such step S103, the controller 10 exits this flow.

On the other hand, as a result of the determination in step S102, when the SOC of the high voltage battery 14 is determined to be less than the first predetermined value (step S102: Yes), the controller 10 proceeds to step S104. In this case, since the SOC of the high voltage battery 14 is extremely small, the controller 10 executes the constant voltage control in order to promptly and surely recover the SOC of the high voltage battery 14. Specifically, the controller 10 sets a constant target voltage V1 to be applied to the voltage of the high voltage battery 14, and controls the ISG 13 so that the actual voltage of the high voltage battery 14 becomes the target voltage V1. I do. The controller 10 sets a voltage required to set the SOC of the high-voltage battery 14 to a predetermined value between the upper limit value S1 and the lower limit value S2 (for example, an intermediate value between the upper limit value S1 and the lower limit value S2). It is applied as the voltage V1.

Next, in step S105, the controller 10 stops the DC-DC converter 17 in order to prohibit the output from the high-voltage battery 14 to the low-voltage electric load 21 via the DC-DC converter 17. By doing so, discharge from the high voltage battery 14 is suppressed. The bypass switch element 18 may be turned off instead of stopping the operation of the DC-DC converter 17. Also in the latter case, the DC-DC converter 17 is substantially stopped. Next, in step S106, the controller 10 further turns off the high-voltage electric load 20. By doing so, the discharge from the high voltage battery 14 is completely suppressed, and the SOC recovery of the high voltage battery 14 is given the highest priority.

Next, in step S107, the controller 10 determines whether or not the SOC of the high voltage battery 14 is equal to or higher than the second predetermined value. This second predetermined value is larger than the first predetermined value used in step S102 above. Specifically, the second predetermined value corresponds to a lower limit value S2 that defines a predetermined range in which the SOC of the high voltage battery 14 should be maintained in the SOC control, and is, for example, 20%. Also in step S107, the controller 10 obtains the SOC of the high-voltage battery 14 by the method similar to that described in step S102.

As a result of the determination in step S107, when the SOC of the high voltage battery 14 is determined to be less than the second predetermined value (step S107: No), the controller 10 returns to step S104. In this case, since the SOC of the high-voltage battery 14 is not yet sufficiently secured, the controller 10 executes the processes of steps S104 to S106 again in order to continuously recover the SOC of the high-voltage battery 14. .. That is, the controller 10 continues to execute the constant voltage control, and at the same time, continues to stop the DC-DC converter 17 and the high-voltage electric load 20.

On the other hand, if the result of determination in step S107 is that the SOC of the high-voltage battery 14 is greater than or equal to the second predetermined value (step S107: Yes), the controller 10 proceeds to step S108. In this case, it can be said that the SOC of the high-voltage battery 14 is sufficiently secured as a result of the execution of the processing of steps S104 to S106. On the other hand, in the situation where the process proceeds to step S108, there is a fact that the SOC of the high-voltage battery 14 becomes less than the first predetermined value as a result of occurrence of some abnormality. This anomaly can reoccur, which can degrade the high voltage battery 14. Therefore, although the SOC of the high voltage battery 14 has recovered to the second predetermined value or higher, the controller 10 executes the constant voltage control during the current driving cycle from the viewpoint of reliably protecting the high voltage battery 14. Is continued (step S108).

Next, in step S109, the controller 10 releases the stop of the DC-DC converter 17 and restarts the operation of the DC-DC converter 17. That is, the controller 10 continues the execution of the constant voltage control, but does not continue the stop of the DC-DC converter 17, but restores the operation of the DC-DC converter 17. By doing so, the output from the high-voltage battery 14 to the low-voltage electric load 21 via the DC-DC converter 17 is restarted, and the discharge from only the low-voltage battery 19 for operating the low-voltage electric load 21 is performed. Suppress. This prevents the SOC of the low-voltage battery 19 from becoming very small, the PCM 31 included in the low-voltage electric load 21 not operating, and the engine 11 from stalling. After such step S109, the controller 10 exits this flow.

In step S109, the controller 10 releases the stop of the DC-DC converter 17 and restarts its operation, but it is preferable to continue the stop of the high-voltage electric load 20. This is from the viewpoint of reliably protecting the high voltage battery 14.

[Action and effect]
Next, the operation and effect according to the embodiment of the present invention will be described.

According to the present embodiment, the controller 10 normally executes the SOC control for the ISG 13 so that the SOC of the high voltage battery 14 becomes the target SOC in order to maintain the SOC of the high voltage battery 14 within the predetermined range. However, when the SOC of the high voltage battery 14 is less than the lower limit value of the predetermined range, the constant voltage control for the ISG 13 is executed so that the voltage of the high voltage battery 14 becomes a constant target voltage. According to this constant voltage control, the voltage of the high voltage battery 14 is forcibly controlled to reach the target voltage, so that the SOC of the high voltage battery 14 can be recovered with priority. Therefore, according to the present embodiment, when the SOC of the high voltage battery 14 becomes less than the lower limit value, the SOC of the high voltage battery 14 can be promptly and reliably recovered. Therefore, it is possible to reliably prevent the SOC from becoming extremely small and the high-voltage battery 14 from deteriorating.

Further, according to the present embodiment, the controller 10 stops the DC-DC converter 17 and executes the low-voltage electric load from the high-voltage battery 14 via the DC-DC converter 17 when executing the constant voltage control. 21 output is prohibited. Thereby, the discharge from the high voltage battery 14 can be suppressed and the SOC recovery of the high voltage battery 14 can be prioritized.

In addition, according to the present embodiment, the controller 10 stops the DC-DC converter 17 and further stops the high-voltage electric load 20 when executing the constant voltage control, so that the high-voltage battery 14 can be operated. It is possible to reliably suppress the discharge and give the highest priority to the recovery of the SOC of the high voltage battery 14.

Further, according to the present embodiment, the controller 10 continuously executes the constant voltage control after the SOC of the high voltage battery 14 becomes equal to or higher than the lower limit value by the execution of the constant voltage control. In the situation where the constant voltage control is executed once, there is a fact that the SOC of the high voltage battery 14 becomes less than the lower limit value as a result of occurrence of some abnormality. This anomaly can reoccur, which can degrade the high voltage battery 14. Therefore, the controller 10 continues to execute the constant voltage control during the current driving cycle even if the SOC of the high voltage battery 14 has recovered to the lower limit value or more. Thereby, the high voltage battery 14 can be protected more reliably.

Further, according to the present embodiment, the controller 10 continuously executes the constant voltage control after the SOC of the high-voltage battery 14 becomes equal to or higher than the lower limit value due to the execution of the constant voltage control, while the DC-DC. The stop of the converter 17 is released and the operation of the DC-DC converter 17 is restarted. By doing so, the output from the high-voltage battery 14 to the low-voltage electric load 21 via the DC-DC converter 17 is restarted, and the discharge from only the low-voltage battery 19 for operating the low-voltage electric load 21 is performed. Suppress. As a result, it is possible to appropriately prevent the harmful effects caused by the continuous power-out from the low-voltage battery 19.

Further, according to the present embodiment, the controller 10 switches the control to be executed from the SOC control to the constant voltage control when the SOC of the high voltage battery 14 drops below the predetermined value S3 that is smaller than the lower limit value. , SOC control makes it possible to cope with a decrease in the SOC of the high-voltage battery 14 as much as possible. That is, it is possible to appropriately prevent the adverse effect caused by the constant voltage control being frequently executed.

1 Hybrid vehicle 10 Controller 11 Engine 13 ISG
14 Lithium-ion battery (high-voltage battery)
17 DC-DC converter 19 Lead acid battery (low voltage battery)
20 High-voltage electrical load 21 Low-voltage electrical load 31 PCM
32 microcomputer

Claims (6)

A power supply control device for a vehicle,
A motor generator having a power generation function of being driven by an engine to generate power, and an electric power function of generating power for driving a vehicle;
While charging the electric power generated by the motor generator, so as to generate power from the motor generator, a battery configured to be able to supply the charging electric power to the motor generator,
In order to maintain the charge amount of the battery within a predetermined range, a target charge amount to be applied to the charge amount of the battery is set so that the actual charge amount of the battery becomes the target charge amount, A controller configured to perform a first control on the motor generator;
Have
The controller sets a constant target voltage to be applied to the voltage of the battery when the charge amount of the battery is less than the lower limit value of the predetermined range, and the actual voltage of the battery is the target voltage. A power supply control device for a vehicle, which is configured to perform a second control on the motor generator so as to obtain a voltage. When the battery is a first battery, a second battery having a voltage lower than that of the first battery,
A first electric load that operates by being supplied with at least one of the electric power charged in the first battery and the electric power charged in the second battery;
A voltage converter that is provided between the first battery and the first electric load and that lowers the voltage output from the first battery and outputs the voltage to the first electric load;
Further has
The power supply control device for a vehicle according to claim 1, wherein the controller is configured to stop the voltage converter when executing the second control. The first battery is further supplied with charged electric power, and further has a second electric load that operates at a higher voltage than the first electric load,
The power supply control of the vehicle according to claim 2, wherein the controller is configured to stop the voltage converter and further stop the second electric load when executing the second control. apparatus. The controller is configured to continuously execute the second control after the charge amount of the battery becomes equal to or more than the lower limit value due to the execution of the second control. The power supply control device for a vehicle according to any one of claims. When the battery is a first battery, a second battery whose voltage is lower than that of the first battery,
A first electric load that operates by being supplied with at least one of the electric power charged in the first battery and the electric power charged in the second battery;
A voltage converter that is provided between the first battery and the first electric load and that reduces the voltage output from the first battery and outputs the voltage to the first electric load.
Further has
The controller is
Is configured to stop the voltage converter when performing the second control,
After the charge amount of the first battery becomes equal to or higher than the lower limit value due to the execution of the second control, the second control is continuously executed while the stop of the voltage converter is released to perform the voltage conversion. Configured to resume operation of the vessel,
The power supply control device for a vehicle according to claim 4. The controller is configured to switch the control to be executed from the first control to the second control when the charge amount of the battery falls below a predetermined value smaller than the lower limit value. The power supply control device for a vehicle according to any one of claims 1 to 5.

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