JP7406472B2 - vehicle power system - Google Patents

Description

The present invention relates to a vehicle power supply system.

Patent Document 1 discloses a vehicle power supply system that can supply power to a starter motor from both a low voltage battery and a DC/DC converter. In this power supply system, when driving the starter motor, the output voltage of the DC/DC converter changes if the internal loss (friction) of the engine is large.

JP2011-046248A

When restarting an engine with a large internal loss, the load on the restart motor increases, so the electric power required to drive the restart motor increases. In order to make it possible to restart even an engine with large internal losses, it is sufficient to increase the capacity of the equipment battery that supplies power.

On the other hand, modern vehicles are sometimes equipped with multiple power sources, such as multiple device batteries and DC/DC converters. In this case, even an engine with a large internal loss can be restarted sufficiently by accommodating power from another power source and supplying it to the restart battery without increasing the capacity of one equipment battery.

However, when accommodating power from another power source, if no measures are taken, the power source to which the power is being accommodated may be affected by voltage drop, etc., and the normal operation of other devices may be hindered. The equipment includes equipment such as control equipment that cannot be stopped even temporarily.

The present invention makes it possible to restart the engine by accommodating power from another power source even when the internal loss of the engine is large, and also to suppress adverse effects on control system equipment due to the accommodating power. The purpose is to provide power supply systems.

The invention according to claim 1 is
A restart motor that restarts the engine, a travel battery that supplies power to the travel motor, and a first device battery and second device that supply power to a plurality of devices including both the restart motor and control system devices. A vehicle power supply system mounted on a vehicle including a battery and a DC/DC converter that generates a power supply voltage that can be supplied to the plurality of devices from the electric power of the driving battery,
a first power line through which power is sent from the first device battery to the control system device;
a second power line carrying power from the second equipment battery to the restart motor;
a first switch connected between the DC/DC converter and the first power line, the first switch having a diode oriented to allow current to flow toward the first power line;
a relay line capable of transmitting power from between the DC/DC converter and the first switch to the second power line;
a second switch that opens and closes the electrical circuit of the relay line;
a control unit that controls the restart motor, the first switch, and the second switch;
Equipped with
Based on the engine restart request, the control unit opens the second switch to drive the restart motor, and if the engine does not restart, closes the second switch and closes the first switch. It is characterized in that it is opened to drive the restart motor.

The invention according to claim 2 is the vehicle power supply system according to claim 1, comprising:
The DC/DC converter is switchable in output capacity,
The control unit further increases the output capacity of the DC/DC converter when the engine does not restart.

The invention according to claim 3 is the vehicle power supply system according to claim 1 or claim 2,
The control unit is characterized in that, when the engine does not restart, the control unit further changes the output voltage of the DC/DC converter in accordance with the internal loss of the engine.

The invention according to claim 4 is the power supply system for a vehicle according to any one of claims 1 to 3,
The control unit may further stop at least one device connected to the first power line when the engine does not restart.

The invention according to claim 5 is the vehicle power supply system according to any one of claims 1 to 4,
The control unit is characterized in that when the second switch is closed and the first switch is opened due to the engine not being restarted, the control unit opens the first switch and then closes the second switch.

According to the present invention, when the internal loss of the engine is low, the control section opens the second switch and drives the restart motor, so that the engine can be restarted using the electric power of the second equipment battery. On the other hand, if the internal loss of the engine is high and the engine cannot be restarted using only the electric power from the second equipment battery, the control unit closes the second switch and opens the first switch to connect the DC/DC converter and the second equipment battery. By driving the restart motor with both electrical powers, it is often possible to restart the engine.

Furthermore, when the power from the DC/DC converter is supplied to the restart motor, the first switch is open, thereby suppressing current being drawn from the first power line to the second power line. In addition, the diode included in the first switch allows power to be sent from the DC/DC converter to the first power line when a device connected to the first power line consumes a lot of power. Therefore, even if the power of the DC/DC converter is used as driving power for the restart motor, voltage drop and other effects are unlikely to affect the first power line. It is possible to suppress the negative impact on

1 is a configuration diagram showing a vehicle equipped with a power supply system according to an embodiment of the present invention. This is the first part of a flowchart showing restart processing executed by the system control unit. This is the second part of the flowchart showing the restart processing. 7 is a time chart illustrating an example of the operation of restart processing. It is a part of a flowchart which shows the modification of the process at the time of a restart performed by a system control part.

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a configuration diagram showing a vehicle equipped with a power supply system according to an embodiment of the present invention. A vehicle 1 according to an embodiment of the present invention is a HEV (Hybrid Electric Vehicle), and includes drive wheels 2, an engine 4 that outputs power to the drive wheels 2, an auxiliary machine 5 for driving the engine 4, and an engine. an ISG (Integrated Starter Generator) 6 that starts or restarts the drive wheels 2; a travel motor 11 that outputs power to the drive wheels 2; an inverter 12 that drives the travel motor 11; and a travel motor that supplies power for travel to the inverter 12. a driving operation unit 20 that receives driving operations from the driver, a driving control unit 21 that controls the driving of the vehicle 1, a system control unit 22 that controls the system of the vehicle 1, and a heater for heating. In-vehicle equipment 7 is provided. ISG6 corresponds to an example of a restart motor according to the present invention. The system control unit 22 corresponds to an example of a control unit according to the present invention.

The running battery 13 is a lithium ion secondary battery, a nickel hydride secondary battery, or the like, and outputs a voltage higher than the power supply voltage (12V system) for equipment.

The ISG 6 has a function as a generator that absorbs a portion of the motive power of the vehicle 1 to generate electricity, and a function as an electric motor that outputs motive power for starting or restarting the engine 4. The ISG 6 temporarily consumes a large amount of power when starting or restarting the engine 4.

The driving operation section 20 includes an accelerator operation section, a brake operation section, a steering operation section, a starting operation section, and the like. The travel control unit 21 receives signals from the driving operation unit 20 indicating the operation amounts of the accelerator operation unit and the brake operation unit, and drives the auxiliary equipment 5 or the inverter 12 in accordance with these signals, and controls the engine 4 and the travel battery 13. make it work. These operations allow the vehicle 1 to travel in accordance with the driving operation.

Furthermore, the vehicle 1 includes a vehicle speed sensor 31 , a rotation sensor 32 that detects the rotational speed of the engine 4 , and a liquid temperature sensor 33 that measures the temperature of the coolant of the engine 4 . Vehicle speed sensor 31 , rotation sensor 32 , and liquid temperature sensor 33 output detection signals to system control section 22 .

The vehicle 1 further includes a first equipment battery 41 that supplies power to control system equipment (the travel control unit 21 and the system control unit 22), a second equipment battery 42 that supplies power to the ISG 6, and a travel battery 13. A DC/DC converter 43 that converts the high voltage of the device into a power supply voltage (12V system) for the equipment, a first power line L1, a second power line L2, and a relay line L3 to which the power supply voltage for the equipment is supplied, and the power supply It includes a relay (corresponding to a second switch) 25 and a semiconductor switch 26 (corresponding to a first switch) for switching the supply route. The first power line L1, the second power line L2, the relay line L3, the relay 25, the semiconductor switch 26, and the system control unit 22 correspond to the power supply system E1 of this embodiment.

The first device battery 41 and the second device battery 42 are, for example, lead batteries, and output a power supply voltage (12V system) for the device.

A first equipment battery 41, an auxiliary machine 5, control system equipment, a driving operation unit 20, and an on-vehicle equipment 7 are connected to the first power line L1, and the first equipment battery 41 is connected to the auxiliary equipment via the first power line L1. 5. Electric power is transmitted to the control system equipment, the driving operation section 20, and the on-vehicle equipment 7. The second device battery 42 and ISG6 are connected to the second power line L2, and power is transmitted from the second device battery 42 to the ISG6 via the second power line L2.

Semiconductor switch 26 is connected between the output terminal of DC/DC converter 43 and first power line L1. The semiconductor switch 26 includes a diode 26a oriented to allow current to flow toward the first power line L1. The diode 26a is connected in parallel with the switching section of the semiconductor switch 26. Diode 26a may be a parasitic diode. The relay line L3 connects the second power line L2 and the connection point N1, and can transmit power between them. Connection point N1 is located in the electrical path between DC/DC converter 43 and semiconductor switch 26. Relay 25 is located in the electrical path of relay line L3, and opens and closes the electrical path. The system control unit 22 switches and controls the relay 25 and the semiconductor switch 26.

The DC/DC converter 43 has a function of switching the output voltage to a plurality of voltages such as 12V, 13V, and 14V. Both voltages that can be switched are voltages that can be used as power supply voltages for equipment. Furthermore, the DC/DC converter 43 has a boost function that makes the output capacity higher than the normal output capacity for a predetermined period of time. When the output capacity is normal, the maximum output current is limited to the first current value (for example, the rated current), but when switched to a higher output capacity, the maximum output current is increased to a second current value that is larger than the first current value. It will be done. However, in the boost function, the time to maintain high output capacity and the time interval from the previous switch to increase the output capacity until the next switch is possible are limited to a predetermined duration and a predetermined time interval, respectively. . Switching of the output voltage of the DC/DC converter 43 and activation of the boost function are performed by the system control unit 22.

In the power supply system E1, the second device battery 42 is charged by power generation from the ISG 6. Further, the first device battery 41 is charged by supplying the electric power of the driving battery 13 or the regenerated electric power of the driving motor 11 after being stepped down by the DC/DC converter 43 . During normal times other than when the engine 4 is started or restarted, the relay 25 is opened and the semiconductor switch 26 is closed. By closing the semiconductor switch 26, the power of the DC/DC converter 43 can be guided to the first power line L1 with low loss.

<Idling stop function>
The vehicle 1 has an idling stop function that stops the idling operation of the engine 4 according to conditions when the vehicle 1 temporarily stops running or when regenerative charging is stopped during HEV running. In the idling stop function, the system control unit 22 stops the idling operation of the engine 4 when the idling stop condition is satisfied, and restarts the engine 4 when the restart condition is satisfied.

<Processing when restarting the engine>
2 and 3 are flowcharts showing restart processing executed by the system control unit. FIG. 4 is a time chart showing an example of the operation of restart processing. The restart process is started when a condition for restarting the engine 4 is satisfied after the idling operation of the engine 4 is stopped. When restart processing is started, the system control unit 22 first opens the relay 25 (step S1). If the relay 25 is originally open, the system control unit 22 maintains that state. Next, the system control unit 22 starts driving the ISG 6 to restart the engine 4 (step S2), and waits for a predetermined time (for example, 2 seconds) required for restarting (step S3).

Subsequently, the system control unit 22 receives a signal of the rotational speed of the engine 4 (step S4), stops driving the ISG 6 (step S5), and determines that the rotational speed of the engine 4 obtained in step S4 exceeds the complete explosion threshold. (Step S6). The complete explosion threshold is set to the rotational speed at which the engine 4 restarts.

Period T1 in FIG. 4 shows an example of the operations in steps S2 to S6. The period T1 is a driving period of the ISG6. When the ISG 6 is driven, the rotational speed of the engine 4 gradually increases over a period T1, as shown by a curve C1. Internal loss (friction) of the engine 4 changes depending on temperature factors and factors other than temperature, such as total mileage, aging, and maintenance status. A change in the internal loss of the engine 4 corresponds to a change in the load on the ISG 6. Therefore, when the ISG 6 is driven by the same power source, when the internal loss of the engine 4 changes, the amount of increase in the curve C1 (the amount of increase in the rotational speed of the engine 4) changes. The end timing t1 of the period T1 is the timing at which the rotational speed of the engine 4 is approximately at its maximum, and the rotational speed signal in step S4 is taken in at this timing t1. If the rotational speed Rmax1 at the end timing t1 reaches the complete explosion threshold, it is determined in step S6 that the restart of the engine 4 has been successful, and if it does not reach the complete explosion threshold, it is determined that the restart of the engine 4 has failed in step S6. . In the example of FIG. 4, the maximum rotational speed Rmax1 of the engine 4 during the period T1 does not reach the complete explosion threshold, and the restart fails.

In the restart processing, if the determination result in step S6 is YES, that is, if the engine 4 has been restarted, the system control unit 22 ends the restart processing. On the other hand, if the determination result in step S6 is NO, that is, if restarting the engine 4 has failed, the system control unit 22 branches the process to steps S7 to S15 in which a second restart is attempted.

When the process proceeds to branch processing for attempting a second restart, the system control unit 22 first opens the semiconductor switch 26 (step S7), and then closes the relay 25 (step S8). By this switching, when the ISG 6 is driven, power is supplied from the second device battery 42 and the DC/DC converter 43 to the ISG 6. Furthermore, even if a voltage drop occurs in both the second power line L2 and the relay line L3 due to the driving of the ISG6, the semiconductor switch 26 is open, so that current is not drawn from the first power line L1 to the second power line L2. Can't be pulled out. Furthermore, the diode 26a of the semiconductor switch 26 allows power to be transferred from the DC/DC converter 43 to the first power line L1 when there is sufficient output from the DC/DC converter 43 and the power consumption of the first power line L1 is large. Supplied. At this time, some loss occurs in the diode 26a, but this period does not continue for a long time. By switching the power path as described above, the power of the DC/DC converter 43 can be changed to the ISG 6, and even if the power is changed, the voltage of the first power line L1 will not become unstable. .

Further, by switching in steps S7 and S8, the semiconductor switch 26 is opened first, so that the first power line L1 and the second power line L2 are directly connected during the switching period of the relay 25 and the semiconductor switch 26. does not occur. Therefore, even if the voltage of the second device battery 42 is low and the voltage of the first device battery 41 is high, current is prevented from being drawn from the first device battery 41 to the second device battery 42. Note that the system control unit 22 may control the output voltage of the DC/DC converter 43 to be higher than the voltage of the first power line L1 during the switching period of the relay 25 and the semiconductor switch 26, and by this control, step S6 and Even if the order of step S7 is reversed, the above-mentioned current draw can be prevented.

After performing the switching in steps S7 and S8, the system control unit 22 increases the output voltage of the DC/DC converter 43 according to the rotational speed of the engine 4 acquired in step S4 (step S9). Here, the purpose of increasing the output voltage will be explained. As shown in period T1 in FIG. 4, when restarting the engine 4 fails, the maximum rotational speed Rmax1 of the engine 4 correlates with the internal loss of the engine 4. That is, if the internal loss of the engine 4 is low, the maximum rotational speed Rmax1 will be high, and if the internal loss of the engine 4 is high, the maximum rotational speed Rmax1 will be low. If the internal loss is high and the rotational speed of the engine 4 cannot be increased, the rotational speed of the engine 4 can be increased by increasing the power supply voltage supplied to the ISG 6. Furthermore, in order to increase the rotation speed in the same way when the internal loss is high and when it is higher, the higher the internal loss (that is, the lower the maximum rotation speed Rmax1), the lower the power supply voltage supplied to ISG6. All you have to do is make it higher. In step S9, the system control unit 22 increases the output voltage of the DC/DC converter 43 in order to increase the rotational speed of the engine 4 by subsequently driving the ISG 6. The system control unit 22 switches the output voltage according to the rotational speed Rmax1 such that the lower the rotational speed Rmax1 of the engine 4 acquired in step S4, the higher the output voltage of the DC/DC converter 43.

Subsequently, the system control unit 22 waits until a cooling period (for example, 1 second) has elapsed since the ISG 6 was stopped (step S10), and then starts driving the ISG 6 (step S11), and starts driving the ISG 6 for a predetermined amount of time required for restarting. Wait for a period of time (for example, 2 seconds) (step S12). After that, the system control unit 22 receives a signal of the rotational speed of the engine 4 (step S13), and stops driving the ISG 6 (step S14). Then, the system control unit 22 determines whether the rotational speed of the engine 4 obtained in step S13 exceeds the complete explosion threshold (step S15), and if it exceeds the complete explosion threshold, that is, the engine 4 has not been restarted. If so, the restart processing ends.

On the other hand, if the determination result in step S15 is NO and the restart of the engine 4 has failed, the system control unit 22 branches the process to steps S16 to S21 in which a third restart is attempted. Period T2 in FIG. 4 shows an example in which the rotational speed of the engine 4 does not reach the complete explosion threshold in the second restart process, and the restart is determined to have failed at timing t2.

Proceeding to the process of attempting a third restart, first, the system control unit 22 increases the output capacity by using the boost function of the DC/DC converter 43 (step S16). Due to the increase in output capability, the output voltage of the DC/DC converter 43 is set not to decrease until the output current of the DC/DC converter 43 reaches a second rated current that is larger than the first rated current. With normal output capability, when the output current reaches the first rated current, the output voltage decreases. In step S16, the system control unit 22 may also perform control to raise the output voltage of the DC/DC converter 43 to the maximum value.

Next, the system control unit 22 waits until a cooling period (for example, 1 second) has elapsed since the ISG 6 was stopped (step S17), starts driving the ISG 6 (step S18), and waits for a predetermined time (for example, 1 second) required for restarting the ISG 6 (step S17). 2 seconds) (step S19). After that, the system control unit 22 receives a signal of the rotational speed of the engine 4 (step S20), and stops driving the ISG 6 (step S21). Then, the system control unit 22 determines whether the rotational speed of the engine 4 obtained in step S20 exceeds the complete explosion threshold (step S22), and if it exceeds the complete explosion threshold, that is, the engine 4 has not been restarted. If so, the restart processing ends.

On the other hand, if it is determined in step S22 that the rotational speed is below the complete explosion threshold and the third restart has failed, the system control unit 22 executes error processing to deal with the restart failure (step S23) and restarts the engine. Ends startup processing. Period T3 in FIG. 4 shows an example in which the rotational speed of the engine 4 exceeds the complete explosion threshold in the third restart process, and the restart is determined to be successful at timing t3.

With the restart processing described above, even when the internal loss of the engine 4 is high, such as at low temperatures, the restart processing is performed multiple times while changing the amount of power supplied, making it possible to restart the engine 4 in many cases. Startup is successful.

As described above, according to the vehicle 1 and the power supply system E1 of the present embodiment, the semiconductor switch 26 with the diode 26a is provided between the first power line L1 to which the control system equipment is connected and the DC/DC converter 43. provided. Furthermore, a relay line L3 and a relay 25 that opens and closes the electrical circuit are provided between the second power line L2 and the first power line L1 to which the ISG 6 is connected. Then, based on the request to restart the engine 4, the system control unit 22 first opens the relay 25 to drive the ISG 6, and when the rotational speed of the engine 4 does not reach the complete explosion threshold indicating restart, the system control unit 22 opens the relay 25 and drives the ISG 6. is closed and the semiconductor switch 26 is opened to drive the ISG 6. Therefore, when the internal loss of the engine 4 is low, the engine 4 is restarted with the power of the second equipment battery 42. On the other hand, if the internal loss of the engine 4 is high and the engine 4 cannot be restarted with the power of the second equipment battery 42, the system control unit 22 supplies the combined power of the DC/DC converter 43 to the ISG 6. to drive. Therefore, even when the internal loss of the engine 4 is high, the engine 4 can be restarted in many cases by accommodating the power of the DC/DC converter 43. Further, at this time, the semiconductor switch 26 with the diode 26a suppresses the current from being drawn from the first power line L1 to the second power line L2, while the current from the DC/DC converter 43 to the first power line L1 is suppressed. is enabled. Therefore, even if the ISG 6 temporarily consumes a large amount of power and a voltage drop occurs on the second power line L2 and the relay line L3, the first device battery 41 and the first power line L1 will not be affected by the voltage drop. is suppressed. Therefore, it is possible to suppress the occurrence of inconveniences such as the control system equipment connected to the first power line L1 being reset.

Furthermore, according to the vehicle 1 and the power supply system E1 of the present embodiment, the DC/DC converter 43 has a boost function that temporarily increases the output capability. Then, the system control unit 22 increases the output capacity of the DC/DC converter 43 when restarting the engine 4 fails and executes restart processing again. Therefore, due to the above-mentioned increase in output capability, a larger amount of electric power is supplied to the ISG 6, increasing the probability that the engine 4 will be restarted successfully thereafter. Furthermore, even if part of the power from the DC/DC converter 43 is sent to the first power line L1, the power consumption of the ISG 6 will temporarily decrease as the maximum value of the output power of the DC/DC converter 43 increases. Even if the voltage increases, the amount of drop in the power sent from the DC/DC converter 43 to the first power line L1 can be suppressed, and the effects of voltage drop and the like on the first power line L1 can be suppressed.

Furthermore, according to the vehicle 1 and the power supply system E1 of the present embodiment, when restarting the engine 4 fails and executing the restart process again, the system control unit 22 controls the rotation of the engine 4 at the time of the failure. The output voltage of the DC/DC converter 43 is switched depending on the speed. Specifically, when the rotational speed of the engine 4 is high when the restart fails, the output voltage is set to a value higher than the standard value, and when the rotational speed is low, the output voltage is set to a higher value. Through this process, the torque of the ISG 6 increases in accordance with the internal loss of the engine 4, and the rotational speed of the engine 4 can be increased. Therefore, the probability that the engine 4 will be restarted successfully increases. Furthermore, even if the power consumption of the ISG 6 temporarily increases due to the increase in the output voltage of the DC/DC converter 43, it is possible to suppress the drop in power sent from the DC/DC converter 43 to the first power line L1. It is possible to suppress the effects of voltage drop and the like on the first power line L1.

Furthermore, according to the vehicle 1 and the power supply system E1 of the present embodiment, when restarting the engine 4 fails and switching between the relay 25 and the semiconductor switch 26, the system control unit 22 first opens the semiconductor switch 26. Then, the relay 25 is closed. Therefore, there is no period during which the first power line L1 and the second power line L2 are directly connected, and even if the voltage of the second device battery 42 is low and the voltage of the first device battery 41 is high, Current can be prevented from being drawn from the first device battery 41 to the second device battery 42. Therefore, during the switching period of the relay 25 and the semiconductor switch 26, the voltage of the first power line L1 is prevented from becoming unstable.

(Modified example)
FIG. 5 is a part of a flowchart showing a modified example of restart processing executed by the system control unit. The restart processing of the modified example is a partial modification of the restart processing shown in FIGS. 2 and 3, and the modified parts will be described in detail below.

In the restart process of the modified example, when the judgment in step S15 is NO (restart failure) and the process moves to a branch process in which the third restart is attempted, the system control unit 22 first controls the DC/ It is determined whether the output of the DC converter 43 has a margin (step S31). The presence or absence of a margin may be determined, for example, by comparing the measured value of the output power or output current of the DC/DC converter 43 with a threshold value (for example, 75% of the rating) that identifies the presence or absence of a margin. Alternatively, whether there is a margin or not may be determined from the driving state of the on-vehicle equipment 7 connected to the first power line L1. The in-vehicle equipment 7 includes equipment that is driven depending on the situation, such as a heating equipment (heater, etc.), a rear defroster, and a blower fan for air conditioning. The output and presence or absence of margin are determined.

As a result of the determination in step S31, if it is determined that there is a surplus in the output of the DC/DC converter 43 (NO in step S31), the system control unit 22 directly advances the process to step S16 in order to restart the engine 4.

As a result of the determination in step S31, if it is determined that there is no margin for the output of the DC/DC converter 43 (YES in step S31), the system control unit 22 controls the on-vehicle equipment 7 connected to the first power line L1. Among them, the driving of predetermined devices is stopped (step S32). Then, the system control unit 22 sets the stop flag to "1" (step S33). Here, as the equipment to be driven and stopped, equipment that does not easily cause trouble in driving the vehicle 1 even if temporarily stopped is applied. The above-mentioned devices may be devices that are driven depending on the situation, such as heating devices (heaters, etc.), rear defrosters, blower fans, etc., or devices that are normally driven constantly, such as auxiliary indicators on the meter panel. It may be. By stopping the above equipment, the power output from the DC/DC converter 43 via the first power line L1 is reduced, and the output margin of the DC/DC converter 43 (output amount obtained by subtracting the current output from the rated output) is reduced. ) is large.

Subsequently, the system control unit 22 advances the process to step S16 in order to restart the engine 4. By combining the stopping of the equipment in step S32 and the increase in the output capacity of the DC/DC converter 43 in step S16, it is possible to further increase the probability that the engine 4 can be restarted in the subsequent restart process.

The processing in steps S16 to S21 is similar to the processing in FIG. 3. After stopping the driving of the ISG 6 in step S21, the system control unit 22 determines whether the stop flag is "1" (step S34), and if it is "1", drives the device stopped in step S32 again. (Step S35), and updates the stop flag to "0" (Step S36). Thereafter, the process advances to step S22.

As described above, according to the vehicle 1 and the power supply system E1 of the modified example, when restarting the engine 4 fails and the system control unit 22 executes restart processing again, the power supply system E1 is connected to the first power line L1. Among the devices that are in operation, the operation of devices other than control system devices is stopped. Therefore, when the ISG 6 is subsequently driven, the power that can be supplied from the DC/DC converter 43 to the ISG 6 increases, increasing the probability that the next restart of the engine 4 will be successful. Furthermore, even if the power consumption of ISG6 temporarily increases due to the stoppage of the above equipment, the power consumption via the first power line L1 is reduced, so that the power consumption of the first power line L1 is reduced. It is possible to suppress the effects of voltage drop and other effects. Therefore, inconveniences such as control system equipment being reset are suppressed.

In Modified Example 1, the system control unit 22 checks whether there is a margin in the output of the DC/DC converter 43, and if there is little margin, drives a predetermined device among the on-vehicle devices 7. It was configured to stop. However, the system control unit 22 may stop driving the device without checking whether there is enough output. In addition, in the first modification, an example was shown in which the drive stoppage of the device is controlled before the third restart process, but the system control unit 22 stops the drive of the device before the second restart process. may also be controlled. In addition, if the control flow is to perform restart processing four or more times when restart failure continues, the system control unit 22 controls the drive stop of the device before the fourth or subsequent restart processing. You may do so.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. For example, in the above embodiment, in the restart processing, when the restart fails, the restart is attempted up to three times, but the restart is attempted up to two times, It may be done four times or more. Furthermore, when the number of times is four or more, control may be performed to increase the output capability or output voltage of the DC/DC converter 43 in stages as the number of times increases. Further, in the above embodiment, an example has been shown in which when the restart of the engine 4 fails, the ISG 6 is once stopped and then the next restart process is started. However, while the ISG 6 is continuously driven, the process of determining whether the restart is successful or unsuccessful, and the switching of the relay 25 and the semiconductor switch 26 or the switching of the DC/DC converter 43 when it is determined that the restart has failed are performed. A switch may also be made.

Further, in the embodiment described above, an example was shown in which the system control unit 22 determines whether restarting of the engine 4 was successful or failed based on whether the rotational speed of the engine 4 reached the complete explosion threshold. However, the system control unit 22 may determine whether the restart of the engine 4 has been successful or failed based on other physical quantities. For example, the physical quantity used in various complete explosion determination methods, such as the amount of decrease in the rotational torque of the ISG 6, may be applied as the above-mentioned physical quantity.

In addition, the details shown in the embodiments, such as the specific configurations corresponding to the first switch and the second switch, can be changed as appropriate without departing from the spirit of the invention.

1 Vehicle 2 Drive wheel 4 Engine 5 Auxiliary equipment 6 ISG
11 Travel motor 12 Inverter 13 Travel battery 21 Travel control section 22 System control section (control section)
31 Vehicle speed sensor 32 Rotation sensor 33 Liquid temperature sensor 41 First equipment battery 42 Second equipment battery 43 DC/DC converter L1 First power line L2 Second power line L3 Relay line 25 Relay (second switch)
26 Semiconductor switch (first switch)
26a diode E1 power system

Claims (5)

A restart motor that restarts the engine, a travel battery that supplies power to the travel motor, and a first device battery and second device that supply power to a plurality of devices including both the restart motor and control system devices. A vehicle power supply system mounted on a vehicle including a battery and a DC/DC converter that generates a power supply voltage that can be supplied to the plurality of devices from the electric power of the driving battery,
a first power line through which power is sent from the first device battery to the control system device;
a second power line carrying power from the second equipment battery to the restart motor;
a first switch connected between the DC/DC converter and the first power line, the first switch having a diode oriented to allow current to flow toward the first power line;
a relay line capable of transmitting power from between the DC/DC converter and the first switch to the second power line;
a second switch that opens and closes the electrical circuit of the relay line;
a control unit that controls the restart motor, the first switch, and the second switch;
Equipped with
Based on the request to restart the engine, the control unit opens the second switch to drive the restart motor, and closes the second switch and turns the first switch if the engine does not restart. A power supply system for a vehicle, characterized in that the power supply system for a vehicle is opened to drive the restart motor. The DC/DC converter is switchable in output capacity,
2. The vehicle power supply system according to claim 1, wherein the control unit further increases the output capacity of the DC/DC converter when the engine is not restarted. 3. The control unit further changes the output voltage of the DC/DC converter according to internal loss of the engine when the engine does not restart. Vehicle power system. Any one of claims 1 to 3, wherein the control unit further stops at least one device connected to the first power line when the engine does not restart. The vehicle power system described in. 2. The control unit, when closing the second switch and opening the first switch due to the engine not restarting, opens the first switch and then closes the second switch. The vehicle power supply system according to any one of claims 1 to 4.

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