JP2008072880A - Power supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply system capable of stably supplying electric power, even if fluctuations in the power source voltage of a voltage system is generated. <P>SOLUTION: This power supply system which comprises a DC/DC converter 30 that converts the voltage of a low-voltage system 10 and the voltage of a high-voltage system 12, supplies electric power of the high-voltage system 12 to the low-voltage system 10 via the DC-DC converter 30 through voltage conversion. The low-voltage system 10 is provided with a first feed system that includes a low-voltage system battery 14 and a generator 16, which feeds electric power to a redundant system electric load 22 of the low-voltage system 10; a changeover switch 44 capable of interrupting the electrical continuity between the first feed system and the DC/DC converter 30, and a second feed system 6 that enables supplying of electric power from the DC/DC converter 30 to the redundant system electrical load 22 of the low-voltage system 10, when conduction is interrupted by the changeover switch 44. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power supply system mounted on a vehicle or the like, and more particularly to a power supply system that converts the voltage of one voltage system into a voltage and supplies it to the other voltage system.

  Conventionally, a power supply system in which a DC-DC voltage converter (DC-DC converter) is provided between a high voltage system and a low voltage system is known (see, for example, Patent Document 1). The DC-DC converter has an inductance interposed between the high voltage system and the low voltage system, and a capacitor provided between the inductance and the ground terminal. The DC-DC converter converts the power of one system into a voltage using an inductance and a capacitor and supplies it to the other system. Therefore, according to the above power supply system, it is possible to supply power from the low voltage system to the high voltage system or from the high voltage system to the low voltage system or both.

Further, in the above power supply system, it is detected whether or not the low voltage battery is in a good state based on the voltage and temperature between terminals of the low voltage battery provided in the low voltage system. If the low-voltage battery is not in good condition, power corresponding to the power consumption of the load provided in the low voltage system is supplied from the high voltage system side to the low voltage system side, and the operation of the load is permitted. Is done. For this reason, it is possible to prevent the low-voltage battery from being overdischarged or overcharged, and it is possible to secure as many opportunities as possible to operate the low-voltage load.
JP 2004-320877 A

  Incidentally, the power supply voltage in each voltage system generally tends to fluctuate. However, since the DC-DC converter that converts the power supply voltage between the voltage systems converts the voltage of one voltage system and supplies it to the other voltage system, the above-described conventional technique has a mode of fluctuation of the power supply voltage. Depending on the case, the fluctuation may affect the power supply control of the DC-DC converter.

  In view of the above, an object of the present invention is to provide a power supply system capable of performing stable power supply even when fluctuations occur in the power supply voltage of the voltage system.

In order to achieve the above object, the power supply system of the present invention provides:
Voltage conversion means for converting the voltage of the first voltage system and the voltage of the second voltage system;
A power supply system that converts the voltage of one voltage system through the voltage conversion means and supplies the power to the other voltage system,
Either voltage system is
A first power supply system for supplying power to the electric load of the voltage system;
A blocking means capable of blocking conduction between the first power feeding system and the voltage converting means;
And a second power supply system that enables power supply from the power conversion means to the electric load of the voltage system when the interruption means interrupts the conduction.

  As a result, no matter how the power supply voltage of one voltage system fluctuates, the conduction between the first power supply means for supplying the power of the power supply voltage and the voltage conversion means is interrupted by the interruption means. The voltage conversion means can perform stable power supply from the other voltage system to the electric load of the voltage system that is not affected by the power supply voltage that fluctuates.

Here, the power supply system of the present invention is
A power supply state detecting unit for detecting the power supply state of the voltage system; and an abnormality determining unit for determining an abnormality in the voltage system based on a detection result of the power supply state detecting unit. It is preferable that the conduction is cut off when the voltage system is determined to be abnormal by the determination means. Thereby, since the power feeding system determined to be abnormal can be disconnected from the voltage converting means, the voltage converting means is not affected by the abnormality, and the voltage converting means passes through the second power feeding system. Stable power supply can be performed to the electric load of the abnormal power supply system.

  At this time, the second power supply system enables power supply from the power conversion means to the electric load of the voltage system not only when the interruption means interrupts the conduction but also when there is the conduction. In the power supply system, the power supply state detection means detects a current passing through the second power supply system, and the abnormality determination means has a current value passed through the second power supply system determined by the power supply state detection means. When the threshold value is detected, the voltage system may be determined to be abnormal as an abnormality of the first power feeding system. In the state where there is continuity, the power supply from the power conversion means can be fed to the electric load of the voltage system in both the first power feeding system and the second power feeding system, so that the current value through the second power feeding system This is because it can be considered that an abnormality such as disconnection has occurred in the first power feeding system. If it is determined that the voltage system is abnormal as an abnormality of the first power supply system, the conduction is interrupted by the interruption means, so that the voltage conversion means passes through the second power supply system. Stable power supply can be performed to the electric load of the abnormal power supply system.

  At this time, the second power supply system can supply power from the power conversion means to the electric load of the voltage system not only when the interruption means interrupts the conduction but also when there is the conduction. The power supply state detecting means detects a current passing through the second power supply system, and the abnormality determining means is configured to detect a current passing through the second power supply path by the power supply state detecting means. If it is not detected, it is determined that the second power supply system is abnormal, and the interruption means stops the conduction interruption when the abnormality determination means determines that the second power supply system is abnormal. Is preferred. In the state where there is continuity, the power supply from the power conversion means can be fed to the electric load of the voltage system in both the first power feeding system and the second power feeding system, so that the current through the second power feeding system is If not detected, it can be considered that an abnormality such as disconnection has occurred in the second power feeding system. In this case, when the voltage system is determined to be abnormal as an abnormality of the second power supply system and the continuity is interrupted by the interrupting means, power supply to the electric load of the voltage system becomes impossible. There is a fear. Therefore, it is preferable that the interruption of the conduction is stopped when the abnormality determination means determines that the second power feeding system is abnormal.

By the way, in the power supply system of the present invention,
The second power supply system is a power supply system that enables power supply from the power conversion means to the electric load of the voltage system not only when the interruption means interrupts the conduction but also when there is the conduction. The power supply state detecting means for detecting the current through the second power supply system during the interruption period by the power supply means, and the current value through the second power supply system is detected by the power supply state detecting means above a predetermined threshold value. An abnormality determining unit that determines that the first power feeding system is abnormal when the abnormality determining unit determines that the abnormality of the first power feeding system is determined by the abnormality determining unit. May be continued. In the state where there is continuity, the power supply means can supply power to the electric load of the voltage system in both the first power supply system and the second power supply system. This is because it can be considered that an abnormality such as disconnection has occurred in the first power supply system if the current value through the power supply system increases. If the voltage system is determined to be abnormal as an abnormality of the first power supply system, the conduction is interrupted by the interruption means. That is, the occurrence of an abnormality can be detected as quickly as possible by performing the interruption according to the interruption period at the normal time.

  At this time, the second power supply system can supply power from the power conversion means to the electric load of the voltage system not only when the interruption means interrupts the conduction but also when there is the conduction. A power supply state detecting means for detecting a current through the second power supply system during a cutoff period by the power supply means, and a current through the second power supply system is detected by the power supply state detecting means. An abnormality determining unit that determines that the second power feeding system is abnormal when the abnormality is not detected, and the blocking unit interrupts the conduction when the abnormality determining unit determines that the second power feeding system is abnormal. Is preferably discontinued. In the state where there is continuity, the power supply means can supply power to the electric load of the voltage system in both the first power supply system and the second power supply system. If no current is detected through the power feeding system, it can be considered that an abnormality such as disconnection has occurred in the second power feeding system. In this case, when the voltage system is determined to be abnormal as an abnormality of the second power supply system and the continuity is interrupted by the interrupting means, power supply to the electric load of the voltage system becomes impossible. There is a fear. Therefore, it is preferable that the interruption of the conduction is stopped when the abnormality determination means determines that the second power feeding system is abnormal. That is, as described above, the occurrence of an abnormality can be detected as quickly as possible by performing the interruption according to the interruption period at the normal time.

By the way, in the power supply system of the present invention,
The power supply state detection unit detects a power supply voltage of the first power supply system, and the abnormality determination unit detects the power supply voltage value of the first power supply system below a predetermined threshold by the power supply state detection unit. In addition, the voltage system may be determined to be abnormal as an abnormality of the first power feeding system. If the power supply voltage of the first power supply system is reduced, the power supply capability from the first power supply system to the electric load of the large voltage system is reduced, and it can be regarded as an abnormality of the first power supply system. If it is determined that the voltage system is abnormal as an abnormality of the first power supply system, the conduction is interrupted by the interruption means, so that the voltage conversion means passes through the second power supply system. Stable power supply can be performed to the electric load of the abnormal power supply system.

  At this time, in the power supply system of the present invention, the first power supply system includes a generator, the power supply state detection unit detects a power generation state of the generator, and the abnormality determination unit includes the power supply state. When the power generation state of the generator is detected as a power generation failure state by the detection means, the voltage system may be determined to be abnormal as an abnormality of the generator. If the voltage system is determined to be abnormal as an abnormality of the generator, the continuity is interrupted by the interrupting means, so that an abnormal power supply system is connected from the voltage converting means via the second power supply system. It is possible to stably supply power to the electrical load.

  At this time, the first power supply system includes a power storage device, and when the abnormality determination unit determines that the abnormality of the voltage system is an abnormality of the generator, the interruption unit interrupts the conduction. It is preferable that power is supplied from the power storage device to the electric load of the voltage system. Even if the continuity is interrupted by the shut-off means due to an abnormality in the generator, stable power feeding can be performed to the electric load of the abnormal power feeding system from the two power feeding means of the power storage device and the voltage converting means.

  In the power supply system of the present invention, a starter motor for starting the engine is connected to the first power feeding system, and the shut-off means shuts off the conduction when the engine is started by the starter motor. You may do it. It is possible to prevent the fluctuation of the power supply voltage due to the drive of the starter motor from being transmitted to the electric load and the voltage conversion means.

  At this time, it is preferable that the interruption means interrupts the conduction before the starter motor is driven and releases the interruption after the generator is driven by starting the engine. It is possible to prevent voltage fluctuation at the start of driving of the starter motor and voltage fluctuation at the start of driving of the generator from being transmitted to the electric load and the voltage converting means.

  Further, it is preferable that the disconnection of the conduction is performed after the output voltage of the generator and the output voltage on the voltage system side of the voltage conversion means are set to be the same. Due to the difference between the two output setting voltages at the time when the interruption of the conduction is released (when the conduction is turned off from the non-conduction), the power supply voltage of the voltage system fluctuates and the voltage to be supplied to the electric load is It can prevent becoming stable.

  In the power supply system of the present invention, if the electric load of the voltage system is a vehicle behavior control device that stabilizes the behavior of the vehicle, there is an abnormality in one power supply system with respect to the vehicle behavior control device that is important during traveling. Even if it occurs, stable power supply can be performed from the other voltage system via the other power supply system, and a functional deterioration due to insufficient power supply of such a vehicle behavior control device can be prevented.

  Further, if the electric load of the voltage system is an electric load in which a visual change is caused by a voltage change (for example, a lamp or a meter that easily blinks due to the voltage change), how the power supply voltage of one voltage system fluctuates. Even if the continuity between the first power supply means for supplying the power of the power supply voltage and the voltage conversion means is interrupted by the interrupting means, such blinking of the electric load caused by the fluctuation of the power supply voltage, etc. Can prevent visual changes.

  According to the present invention, stable power feeding can be performed even if fluctuations occur in the power supply voltage of the voltage system.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

[First embodiment]
FIG. 1 shows a configuration diagram of a power supply system according to a first embodiment of the present invention. The system of the present embodiment is a system that controls a step-up / step-down DC-DC converter that is mounted on, for example, a vehicle or the like and boosts and lowers a power supply voltage.

  As shown in FIG. 1, the system of the present embodiment includes two systems, a low voltage system 10 and a high voltage system 12. The low voltage system 10 includes a secondary battery 14 and a generator 16. The secondary battery 14 is a power storage device such as a lead battery having an output voltage of about 12V. The generator 16 is a generator that generates electric power by the rotation of a vehicle engine, which is one of vehicle regenerative brakes and vehicle power. Further, the high voltage system 12 has a secondary battery 18. The secondary battery 18 is a power storage device such as a nickel metal hydride battery or a lithium ion battery having an output voltage of about 36V. Note that the secondary battery 14 and the secondary battery 18 may be a lead battery, a lithium ion battery, a nickel metal hydride battery, an electric double layer capacitor, or the like, or a combination of them. Hereinafter, the secondary battery 14 is referred to as a low-voltage battery 14, and the secondary battery 18 is referred to as a high-voltage battery 18.

  The low voltage system 10 also has electric loads 20 and 22 such as an air conditioner such as a blower motor, a compressor, and an electric heater, and an emergency notification device (Mayday). The low-voltage battery 14 and the generator 16 mainly discharge and supply stored electric power or generated electric power to the electric loads 20 and 22. The electric loads 20 and 22 become operable when supplied with electric power stored in the low-voltage battery 14 or electric power generated by the generator 16.

  The high voltage system 12 also has an electrical load 24 such as an electric power steering (EPS), an electric stabilizer, and a drive motor that is one of vehicle power. The high-voltage battery 18 mainly discharges and supplies the stored electric power to the electric load 24. The electric load 24 becomes operable when the electric power stored in the high-voltage battery 18 is supplied.

  In addition, the system of this embodiment includes a direct current-direct current voltage converter (hereinafter referred to as a DC-DC converter) 30. The DC-DC converter 30 is interposed between the low voltage system 10 and the high voltage system 12. The DC-DC converter 30 converts the input voltage bidirectionally between the low voltage system 10 and the high voltage system 12 and supplies and outputs power.

  The DC-DC converter 30 has a step-up / step-down circuit including an inductance 32, a low-voltage capacitor 34, and a high-voltage capacitor 36. The inductance 32 is connected in series on a line connecting the low voltage system 10 and the high voltage system 12. The low-voltage capacitor 34 is connected between the terminal on the low-voltage system 10 side of the inductance 32 and the ground terminal. The high-voltage capacitor 36 is connected between a terminal on the high-voltage system 12 side of the inductance 32 and a ground terminal. The low-voltage capacitor 34 and the high-voltage capacitor 36 can store and discharge power supplied from the low-voltage battery 14 and the generator 16 or power supplied from the high-voltage battery 18. The low-voltage capacitor 34 and the high-voltage capacitor 36 are components necessary for smoothing the discharge power when the DC-DC converter 30 is operated. When the DC-DC converter 30 is normally operated, A ripple current flows in a predetermined range.

  The DC-DC converter 30 includes a control unit 38 that is an electronic control unit, and a pair of switching elements 40 and 42. Each of the switching elements 40 and 42 is, for example, a MOSFET configured of a semiconductor. The switching element 40 has one end connected to the terminal on the high voltage system 12 side of the inductance 32 and the other end grounded. The switching element 42 has one end connected to the terminal on the high voltage system 12 side of the inductance 32 and the other end connected to the high voltage system 12.

  The above-described control unit 38 is connected to the gates of the switching elements 40 and 42, and drives the switching elements 40 and 42, respectively. The control unit 38 inverts the switching element 40 and the switching element 42 to realize step-up conversion from the low pressure system 10 to the high pressure system 12 or step-down conversion from the high pressure system 12 to the low pressure system 10. Each of the switching elements 40 and 42 performs a switching operation in accordance with a drive command from the control unit 38.

  A changeover switch 44 is interposed between the low voltage system 10 and the inductance 32 of the DC-DC converter 30. That is, the power supply system such as the low voltage system battery 14 and the generator 16 of the low voltage system 10 is connected to the inductance 32 side of the DC-DC converter 30 via the changeover switch 44. The changeover switch 44 is, for example, a MOSFET made of a semiconductor as shown in FIG. The changeover switch 44 is disposed in the DC-DC converter 30, and its gate is connected to the control unit 38 described above. As will be described later in detail, the control unit 38 drives the changeover switch 44 as appropriate. The changeover switch 44 performs a switching operation in accordance with a drive command from the control unit 38, and connects / disconnects between the power supply system such as the low voltage system battery 14 and the generator 16 of the low voltage system 10 and the inductance 32.

  Of the electric loads 20 and 22 of the low voltage system 10, the electric load 20 is a load (for example, various lights and blower motors) that does not need to operate when an abnormality such as a failure of the low voltage system 10 occurs. The electric load 20 is connected in parallel to the low-voltage battery 14 and the generator 16, and is connected to the inductance 32 side of the DC-DC converter 30 via the changeover switch 44.

  On the other hand, the electric load 22 is a load (for example, an emergency call device, a brake device, etc.) that needs to operate even when an abnormality such as a failure of the low voltage system 10 occurs. The electric load 22 is connected in parallel to the low-voltage battery 14 and the generator 16, and is connected to the inductance 32 side of the DC-DC converter 30 via the changeover switch 44, and further via the changeover switch 44. Of course, it is connected to the inductance 32 side of the DC-DC converter 30. That is, the electric load 22 is supplied with power from the DC-DC converter 30 not via the changeover switch 44 together with the power supply line 46 from the low voltage system 10 so that power can be supplied even when an abnormality such as a failure of the low voltage system 10 occurs. A supply line 48 is connected. The diode 8 is configured so that the current supplied through the power supply line 46 does not flow into the power supply line 48 side, and the current supplied through the power supply line 48 does not flow into the power supply line 46 side. A diode 7 is configured.

  In addition, a current detector 50 is connected to the control unit 38. The current detector 50 is disposed on the power supply line 48. The current detector 50 outputs a signal corresponding to the current flowing through the electric load 22 via the power supply line 48 using a current probe or a shunt resistor. The output of the current detector 50 is supplied to the control unit 38. Based on the output of the current detector 50, the control unit 38 detects a current I 6 that flows through the electric load 22 via the power supply line 48. As for the direction of the current I6, the direction flowing into the electric load 22 via the power supply line 48 is positive (+). Further, a system between cd including the power supply line 48, the diode 8 and the current detector 50 is referred to as a redundant power supply system 6. If a redundant power supply system 6 requires a fuse, if a current detection function FET is used as the current detector 50, the current detection function and the fuse function can be used together, and the number of parts can be reduced. It can be reduced.

  Next, the operation of the power supply system of this embodiment will be described.

  In the system of this embodiment, when the operation of the electric loads 20 and 22 of the low voltage system 10 is required, power is supplied from the low voltage system battery 14 or the generator 16 to the electric loads 20 and 22. In this case, the electric loads 20 and 22 can be operated. Further, when an operation of the electric load 24 of the high voltage system 12 is requested, power is supplied from the high voltage system battery 18 to the electric load 24. In this case, the electric load 24 can be operated.

  The control unit 38 of the DC-DC converter 30 controls the power supply state of the low voltage system 10 (for example, the voltage value of the low voltage system 10 (low voltage system battery 14), the remaining capacity of the low voltage system battery 14) and the high voltage system 12. Boost conversion from the low voltage system 10 to the high voltage system 12 is required based on the relationship with the power supply state (for example, the voltage value of the high voltage system 12 (high voltage battery 18), the remaining capacity of the high voltage battery 18). Whether or not the DC-DC converter 30 should be started by determining whether or not step-down conversion from the high voltage system 12 to the low voltage system 10 is necessary. Is determined. When the DC-DC converter 30 is to be started, the changeover switch 44 is turned on to make the low voltage system 10 and the DC-DC converter 30 conductive, and according to the state of both voltage systems 10 and 12. The duty ratio of the pair of switching elements 40 and 42 is set.

  When the DC-DC converter 30 is to perform step-up conversion, the control unit 38 first turns on the switching element 40 and turns off the switching element 42 according to the set duty ratio. When the switching element 40 is turned on and the switching element 42 is turned off, a current flows from the low voltage system 10 to the high voltage system 12 through the inductance 32, so that electric power is stored in the inductance 32. Next, the control unit 38 turns off the switching element 40 and turns on the switching element 42 according to the set duty ratio in a state where power is stored in the inductance 32. When the switching element 40 is turned off and the switching element 42 is turned on, the electric power stored in the inductance 32 is discharged to the high voltage system 12 side in a smoothed state and is higher than the voltage on the low voltage system 10 side. The voltage is output to the high voltage system 12.

  When the DC-DC converter 30 should perform step-down conversion, the control unit 38 first turns off the switching element 40 and turns on the switching element 42 according to the set duty ratio. When the switching element 40 is turned off and the switching element 42 is turned on, a current flows from the high voltage system 12 to the low voltage system 10 through the inductance 32, so that electric power is accumulated in the inductance 32 and the low voltage system. Electric charges are accumulated in the capacitor 34, and power is supplied to the low voltage system 10. Next, the control unit 38 turns on the switching element 40 and turns off the switching element 42 in accordance with the set duty ratio in a state where power is stored in the inductance 32. When the switching element 40 is turned on and the switching element 42 is turned off, the power stored in the inductance 32 and the low voltage system capacitor 34 is discharged to the low voltage system 12 side in a smoothed state, and the high voltage system 10 A voltage lower than the side voltage is output to the low voltage system 10.

  Therefore, according to the system of the present embodiment, the DC-DC converter 30 is operated by repeating the on / off drive at a predetermined duty ratio while the pair of switching elements 40 and 42 are operated in an inverted manner, thereby reducing the low voltage. The voltage conversion between the system 10 and the high voltage system 12 can be performed by synchronous rectification, and the voltage of the low voltage system 10 is boosted as desired by the switching control of the DC-DC converter 30 or the voltage of the high voltage system 12 is increased. The power of the low voltage system 10 or the high voltage system 12 can be supplied to the high voltage system 12 or the low voltage system 10 while stepping down as desired.

  By the way, in the low voltage system 10, there may be a failure such as a power generation failure of the generator 16, a failure such as an open or short circuit of the low voltage battery 14, or a failure such as an open or short circuit of the power supply line 46 or 48. As a method for detecting these failures, it is conceivable that a voltage sensor and a current sensor are provided in the generator 16 and the low-voltage battery 14 and the failure is individually determined. However, with such a technique, it is necessary to provide a large number of sensors in order to detect an abnormality in the low voltage system 10, and the power supply system may be complicated.

  Further, as described above, the electric load 22 provided in the low voltage system 10 is a load that needs to operate even when the low voltage system 10 such as a Mayday device or an electric brake device is abnormal. Even when an abnormality occurs, it is necessary to enable power supply.

  On the other hand, the system of the present embodiment detects an abnormality of the low voltage system 10 connected to the DC-DC converter 30 with a simple configuration as described in detail below. When an abnormality occurs, power is supplied to the redundant electrical load 22 while disconnecting the abnormal part of the low voltage system 10 from the DC-DC converter 30.

  FIG. 3 is a first diagram showing the relationship between the current I6 flowing through the electric load 22 via the power supply line 48 and the on / off of the changeover switch 44 in the DC-DC converter 30 of the present embodiment.

  In the first embodiment, as described above, the electric load 22 is supplied with the power supply line 46 from the low voltage system 10 via the changeover switch 44 so that power can be supplied even in the event of an abnormality such as a failure of the low voltage system 10. A power supply line 48 (redundant power supply system 6) from the non-DC-DC converter 30 is connected. The control unit 38 monitors the current I6 flowing through the redundant power supply system 6 based on the output of the current detector 50.

  On the other hand, in the low voltage system 10, when an abnormality occurs in the power supply system of the low voltage system 10, such as the low voltage system battery 14, the generator 16, and the power supply line 46 (for example, the terminals of the low voltage system battery 14 and the cell An open failure, a failure accompanied by a decrease in the power supplied to the generator 16, a power supply line 46 (in this case, power supply lines in the low-voltage system 10 excluding the power supply line 48 (ie, between a and b in FIG. When an abnormality such as disconnection of the power line between c)) occurs, it becomes difficult to supply power from the low voltage battery 14 or the generator 16 to the electric load 22 of the low voltage system 10. At this time, since the power supply voltage of the low voltage system 10 decreases, a large amount of power is taken out from the DC-DC converter 30 that controls to suppress the decrease of the power supply voltage of the low voltage system 10, and the range of current that can be normally supplied is reduced. Excessive supply current exceeding flows out from the DC-DC converter 30 to the electric load 22 via the redundant power supply system 6. Therefore, if the current I6 flowing through the redundant power supply system 6 (power supply line 48) is monitored, various abnormalities in the low voltage system 10 can be detected.

  In the present embodiment, the changeover switch 44 is interposed between the low voltage system 10 and the inductance 32 of the DC-DC converter 30 as described above. Of the electric loads 20 and 22 of the low voltage system 10, the electric load 20 is connected to the inductance 32 side of the DC-DC converter 30 via the changeover switch 44, but the electric load 22 is further connected in addition to the connection. The DC-DC converter 30 is connected to the inductance 32 side without going through the changeover switch 44. Therefore, even when the low voltage system 10 is abnormal, the low voltage system 10 is disconnected from the DC-DC converter 30, but the redundant system is directly connected from the high voltage system 12 via the DC-DC converter 30. It is possible to supply electric power to the electrical load 22 of the current.

  Therefore, the threshold value Ith for determining the abnormality of the low-voltage system 10 shown in FIG. 3 is larger than the current flowing through the redundant power supply system 6 during the normal operation of the DC-DC converter 30 and an abnormality occurs in the low-voltage system 10. It may be set to a current value at which it can be determined. Further, when the current I 50 is not detected by the current detector 50 even though the electric load 22 is operating, it can be regarded as an abnormality such as disconnection of the redundant power supply system 6. When an abnormality of the low voltage system 10 is detected, for example, a warning for notifying the driver of the abnormality may be output.

  Each of FIGS. 4 to 6 shows a flowchart of an example of a control routine executed by the control unit 38 in the DC-DC converter 30 of the first embodiment. In the power supply system of the present embodiment, the current detector 50 is provided on the redundant power supply system 6 as described above, and the control unit 38 of the DC-DC converter 30 is based on the output of the current detector 50. The current I6 flowing through the line is monitored (step 10 in FIG. 4, step 20 in FIG. 5, step 30 in FIG. 6). The control unit 38 determines whether or not the current I6 flowing through the redundant power supply system 6 is zero (Step 11, FIG. 5, Step 21, and FIG. 6 Step 31). If the current I6 is zero, the redundant power supply is performed. Considering that the system 6 is abnormal, the driver is warned that there is an abnormality (step 12, FIG. 5, step 22, FIG. 6, step 32 in FIG. 6). As an abnormality of the redundant power supply system 6 in this case, an open failure of the power supply line 48 and the diode 8, a failure of the current detector 50 itself, and the like can be mentioned.

  On the other hand, when the current I6 flowing through the redundant power supply system 6 is greater than or equal to the threshold value Ith (step 13, FIG. 5, step 23, FIG. 6, step 33), the control unit 38 detects an abnormality in the power supply system of the low voltage system 10. (For example, a failure of a terminal or a cell of the low-voltage battery 14 or an open failure of the low-voltage battery 14, a failure accompanied by a decrease in the power supplied to the generator 16, or a disconnection of the power supply line 46). 30 control switching is performed. In this case, the control of the DC-DC converter 30 may be switched from step-up control to step-down control after the change-over switch 44 is turned off (steps 14 and 15 in FIG. 4). Switching from step-up control to step-down control may be performed simultaneously (step 24 in FIG. 5), or the switch 44 may be turned off after switching from step-up control to step-down control of the DC-DC converter 30 (FIG. 6). Steps 34, 35). If the control of the DC-DC converter 30 is switched from step-up control to step-down control after the changeover switch 44 is turned off as in steps 14 and 15 of FIG. The DC-DC converter 30 can be disconnected from the location. That is, it is possible to quickly prevent the influence of the abnormality of the power supply system of the low voltage system 10 from reaching the DC-DC converter 30 and the electric load 22 and to perform stable power supply from the DC-DC converter 30 to the electric load 22. it can. If the changeover switch 44 is turned off after switching from step-up control to step-down control of the DC-DC converter 30 as in steps 34 and 35 in FIG. 10 can be quickly recovered by the power supply from the DC-DC converter 30. In addition, since power can be supplied from the DC-DC converter 30 quickly, the capacity of the low-voltage capacitor 34 can be reduced and the volume thereof can also be reduced.

  According to such a configuration, I6 flowing through the redundant power supply system 6 is monitored, and it is determined that an abnormality has occurred in the low voltage system 10 when a supply current exceeding a threshold Ith larger than the normal supply current flows. Can do. In this case, it is not necessary to provide a current detector or the like for each of the low voltage battery 14 and the generator 16 in order to detect an abnormality in the low voltage system 10, and a detection element is provided only in the DC-DC converter 30. It is sufficient to provide it. In addition, it is not necessary to individually detect the current values flowing through the low-voltage battery 14 and the generator 16, and it is sufficient to monitor the current I6 flowing through the redundant power supply system 6.

  Therefore, according to the power supply system of the present embodiment, the abnormality detection of the low voltage system 10 can be performed only by the elements provided in the DC-DC converter 30, and therefore the abnormality of the low voltage system 10 can be achieved with a simple configuration. Can be detected. For this reason, it is possible to construct an abnormality detection system for the low-voltage system 10 at a low cost and with a small number of assembly steps.

  According to the above configuration, the changeover switch 44 that is turned on during normal operation can be turned off when it is detected that an abnormality has occurred in the low-voltage system 10. When the changeover switch 44 is turned off, the low voltage system 10 (specifically, the low voltage battery 14, the generator 16, and the electrical load 20) is disconnected from the DC-DC converter 30, while the low voltage system The ten electrical loads 22 continue to connect to the DC-DC converter 30 through the power supply line 48. In this case, power cannot be supplied from the high voltage system 12 to the electrical load 20 from the low voltage system battery 14 or the generator 16 of the low voltage system 10 via the DC-DC converter 30. 22 can be supplied with power from the high voltage system 12 via the DC-DC converter 30.

  Therefore, according to the power supply system of the present embodiment, the low voltage system 10 in which an abnormality has occurred is disconnected from the DC-DC converter 30 by opening the changeover switch 44, and the high voltage system is connected to the electric load 22 of the low voltage system 10. Power can be supplied from 12 through the DC-DC converter 30. In this respect, in the power supply system of the present embodiment, it is possible to prevent wasteful power supply from the high voltage system 12 via the DC-DC converter 30 to the low voltage system 10 in which an abnormality has occurred. ing. Further, even if an abnormality occurs in the low voltage system 10 due to, for example, disconnection of the power supply line 46 and the power supply from the low voltage system battery 14 or the generator 16 becomes impossible, the redundant system load 22 is not affected. Can be supplied with power, and the operation of the electric load 22 can be secured. Further, since the power source of the low voltage system 10 can be disconnected from the DC-DC converter 30, the influence of the abnormality of the power source of the low voltage system 10 is prevented from reaching the DC-DC converter 30 and the electric load 22, and the DC-DC Stable power supply from the converter 30 can be performed on the electric load 22.

[Second Embodiment]
The configuration of the power supply system of the second embodiment of the present invention is the same as that of the first embodiment shown in FIG. In the first embodiment, the changeover switch 44 that is turned on during normal operation is controlled to turn off when it is detected that an abnormality has occurred in the low-voltage system 10, but the second embodiment In the example, the changeover switch 44 is controlled to be turned off even when it is not detected that an abnormality has occurred in the low voltage system 10. That is, a function check is performed during normal operation.

  FIG. 7 is a second diagram showing the relationship between the current I6 flowing through the electric load 22 via the power supply line 48 and the on / off of the changeover switch 44 in the DC-DC converter 30 of the present embodiment.

  In the second embodiment, as described above, the electric load 22 can be supplied with power even in the event of an abnormality such as a failure of the low voltage system 10 through the changeover switch 44 together with the power supply line 46 from the low voltage system 10. The power supply line 48 (redundant power supply system 6) from the non-DC-DC converter 30 is connected. The control unit 38 monitors the current I6 flowing through the redundant power supply system 6 based on the output of the current detector 50.

  On the other hand, the control unit 38 sets the changeover switch 44 for a short time (for example, low voltage) within a predetermined cycle (for example, within a time during which the electric load 22 can operate with the capacity of the low voltage system capacitor 34 built in the DC-DC converter 30). The system 10 is turned off only for a time during which the abnormality of the system 10 can be determined. A voltage (for example, a voltage at a connection point d between the inductance 32 and the low-voltage capacitor 34) on the low voltage system 10 side of the DC-DC converter 30 is slightly higher than an output voltage (voltage at the point b) of the generator 16 (for example, 1V), if the current I50 is not detected by the current detector 50 within the period when the changeover switch 44 is off, it can be regarded as an abnormality such as disconnection of the redundant power supply system 6. This is because if a diode OR circuit composed of the diode 7 and the diode 8 is a normal circuit, a current flows from a diode having a large anode side voltage among the two diodes. When an abnormality such as disconnection of the redundant power supply system 6 is detected, a warning for notifying the driver of the abnormality may be output, for example.

  Further, in the low voltage system 10, a failure of a terminal or cell of the low voltage battery 14, a failure accompanied by a decrease in the power supplied to the generator 16, a power supply line 46 (in this case, the low voltage system 10 excluding the power supply line 48) When an abnormality occurs in the power supply system of the low voltage system 10 such as disconnection of the power supply line (that is, the power supply line between ab and bc in FIG. 1), the low voltage system battery 14 and the power generation It becomes difficult to supply power from the machine 16 to the electric load 22 of the low voltage system 10. At this time, since the power supply voltage of the low voltage system 10 decreases, a large amount of power is taken out from the DC-DC converter 30 that controls to suppress the decrease of the power supply voltage of the low voltage system 10, and the range of current that can be normally supplied is reduced. Excessive supply current exceeding flows out from the DC-DC converter 30 to the electric load 22 via the redundant power supply system 6. Therefore, when an excessive supply current exceeding the range of current that can be normally supplied within the period in which the changeover switch 44 is off flows from the DC-DC converter 30 to the electric load 22 via the redundant power supply system 6, It can be considered that power supply from the low voltage battery 14 or the generator 16 to the electric loads 20 and 22 is not sufficiently performed due to an abnormality in the power supply system of the low voltage system 10. That is, when the current detector 50 detects the current I6 at a predetermined threshold value Ith or more during the period when the changeover switch 44 is OFF, the control unit 38 detects that the terminal of the low-voltage battery 14 or the cell has failed, the generator 16, a failure accompanied by a decrease in the supply power, the power supply line 46 (in this case, the power supply lines in the low-voltage system 10 excluding the power supply line 48 (that is, the power supply lines between ab and bc in FIG. 1) It is determined that there is an abnormality in the power supply system of the low-voltage system 10 such as disconnection)).

  Even when the switch 44 is kept off and the low voltage system 10 is disconnected from the DC-DC converter 30, the redundant electrical system is directly connected from the high voltage system 12 via the DC-DC converter 30. It is possible to supply power to the load 22.

  FIG. 8 shows a flowchart of an example of a control routine executed by the control unit 38 in the DC-DC converter 30 of the second embodiment. The control unit 38 turns on the changeover switch 44 (step 40). In the power supply system of the present embodiment, the current detector 50 is provided on the redundant power supply system 6 as described above, and the control unit 38 of the DC-DC converter 30 is based on the output of the current detector 50. The current I6 flowing through the line is monitored (step 41). The control unit 38 turns off the changeover switch 44 after a predetermined time after the changeover switch 44 is turned on (step 42), and determines whether or not the current I6 flowing through the redundant power supply system 6 is zero while the changeover switch 44 is turned off. However, if the current I6 is zero, it is considered that the redundant power supply system 6 is abnormal, and the driver is warned that there is an abnormality (step 44). As an abnormality of the redundant power supply system 6 in this case, an open failure of the power supply line 48 and the diode 8, a failure of the current detector 50 itself, and the like can be mentioned.

  On the other hand, when the current I6 flowing through the redundant power supply system 6 is greater than or equal to the threshold value Ith (step 45), the control unit 38 detects that the power supply of the low voltage system 10 is abnormal (for example, the terminal of the low voltage system battery 14 or the cell is open). The control of the DC-DC converter 30 is switched from step-up control to step-down control, assuming that it is a failure, a failure accompanied by a decrease in the power supplied to the generator 16, or a disconnection of the power supply line 46 (step 46).

  Even in such a configuration, it is possible to monitor I6 flowing through the redundant power supply system 6 and determine that an abnormality has occurred in the low voltage system 10 when a supply current exceeding a threshold Ith larger than the normal supply current flows. it can. Even in this case, it is not necessary to provide a current detector or the like for each of the low voltage system battery 14 and the generator 16 in order to detect an abnormality in the low voltage system 10, and a detection element is provided only in the DC-DC converter 30. It is sufficient to provide it. In addition, it is not necessary to individually detect the current values flowing through the low-voltage battery 14 and the generator 16, and it is sufficient to monitor the current I6 flowing through the redundant power supply system 6.

  Therefore, according to the power supply system of the present embodiment, the abnormality detection of the low voltage system 10 can be performed only by the elements provided in the DC-DC converter 30, and therefore the abnormality of the low voltage system 10 can be achieved with a simple configuration. Can be detected.

  Also in the above configuration, when the changeover switch 44 is turned off, the low voltage system 10 (specifically, the low voltage system battery 14, the generator 16, and the electric load 20) is disconnected from the DC-DC converter 30. On the other hand, the electrical load 22 of the low voltage system 10 still continues to be connected to the DC-DC converter 30 through the power supply line 48. In this case, power cannot be supplied from the high voltage system 12 to the low voltage system battery 14, the generator 16, and the electrical load 20 of the low voltage system 10 via the DC-DC converter 30. 22 can be supplied with power from the high voltage system 12 via the DC-DC converter 30.

  Therefore, according to the power supply system of the present embodiment, the low voltage system 10 in which an abnormality has occurred is disconnected from the DC-DC converter 30 by opening the changeover switch 44, and the high voltage system is connected to the electric load 22 of the low voltage system 10. Power can be supplied from 12 through the DC-DC converter 30. Further, even if an abnormality occurs in the low voltage system 10 due to, for example, disconnection of the power supply line 46 and the power supply from the low voltage system battery 14 or the generator 16 becomes impossible, the redundant system load 22 is not affected. Can be supplied with power, and the operation of the electric load 22 can be secured. Further, since the power source of the low voltage system 10 can be disconnected from the DC-DC converter 30, the influence of the abnormality of the power source of the low voltage system 10 is prevented from reaching the DC-DC converter 30 and the electric load 22, and the DC-DC Stable power supply from the converter 30 can be performed on the electric load 22.

[Third embodiment]
FIG. 9 shows a configuration diagram of a power supply system according to the third embodiment of the present invention. In the third embodiment, the electric load 22 is an example of an electric load that performs an intermittent operation that repeatedly starts and stops. In the power supply system of the third embodiment shown in FIG. 9, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  In FIG. 9, the control unit 38 includes a signal line 9 in order to detect the operating state of the electric load 22. The control unit 38 acquires an operation signal BL3 indicating the operation state of the electric load 22 via the signal line 9. For example, the operation signal BL3 = 0 indicates that the electrical load 22 is stopped, and the operation signal BL3 = 1 indicates that the electrical load 22 is in operation.

  Alternatively, the control unit 38 may include the signal line 9 in order to force the electric load 22 to operate. The control unit 38 outputs an operation command signal BL3 that commands the operation of the electric load 22 via the signal line 9. When it is desired to start the operation of the electric load 22, the control unit 38 outputs an operation command signal of BL3 = 1 indicating that the operation of the electric load 22 is started, and stops the operation of the electric load 22. In this case, an operation command signal of BL3 = 0 indicating that the operation of the electric load 22 is stopped is output. The electric load 22 operates according to these operation command signals.

  In the first embodiment, the changeover switch 44 that is turned on during normal operation is controlled to turn off when it is detected that an abnormality has occurred in the low voltage system 10, but the third embodiment In the example, the changeover switch 44 is controlled to be turned off even when it is not detected that an abnormality has occurred in the low voltage system 10. That is, a function check is performed during normal operation.

  In the DC-DC converter 30 of the present embodiment, the relationship between the current I6 flowing through the electric load 22 via the power supply line 48 and the on / off of the changeover switch 44 is the same as in FIG. 7 in the second embodiment. is there.

  In the third embodiment, as in the second embodiment, the control unit 38 determines that the electrical load 22 can operate with a predetermined period (for example, the capacity of the low-voltage capacitor 34 built in the DC-DC converter 30). The changeover switch 44 is turned off for a short time (for example, a time during which the low pressure system 10 can be determined to be abnormal). Then, the control unit 38 sets the output voltage of the DC-DC converter 30 (the voltage at the connection point d between the inductance 32 and the low-voltage capacitor 34) to a voltage (a voltage slightly higher than the output voltage of the generator 16 (the voltage at the point b)). For example, when the current I 50 is not detected by the current detector 50 during the period when the changeover switch 44 is OFF, it is determined that the redundant power supply system 6 is abnormal such as disconnection.

  Similarly to the second embodiment, the control unit 38 controls the low voltage battery 14 when the current detector 50 detects a current I6 that is equal to or greater than a predetermined threshold value Ith within a period in which the changeover switch 44 is off. Terminal or cell open failure, failure accompanied by a decrease in power supplied to the generator 16, power supply line 46 (in this case, power supply lines in the low-voltage system 10 excluding the power supply line 48 (ie, ab in FIG. 1) And the power supply line between b and c) is determined to be abnormal in the power supply of the low voltage system 10 such as disconnection.

  However, the current detector 50 detects the current I6 when the consumption current is not generated because the electric load 22 is not operating or is not stopped due to intermittent operation. Therefore, even if an abnormality such as disconnection of the redundant power supply system 6 or an abnormality of the power supply of the low voltage system 10 is determined, there is a risk of erroneous determination. Therefore, the third embodiment operates as shown in FIG. 10 in order to avoid the erroneous determination.

  FIG. 10 shows a flowchart of an example of a control routine executed by the control unit 38 in the DC-DC converter 30 of the third embodiment. The control unit 38 turns on the changeover switch 44 (step 50). In the power supply system of the present embodiment, the current detector 50 is provided on the redundant power supply system 6 as described above, and the control unit 38 of the DC-DC converter 30 is based on the output of the current detector 50. The current I6 flowing through the line is monitored (step 51). The control unit 38 determines whether or not the current I6 flowing through the redundant power supply system 6 is zero when BL3 = 1 (the electric load 22 is operating) (step 52) and the changeover switch 44 is off (step 53). If the current I6 is zero, it is considered that the redundant power supply system 6 is abnormal, and the driver is warned that there is an abnormality (step 55). As an abnormality of the redundant power supply system 6 in this case, an open failure of the power supply line 48 and the diode 8, a failure of the current detector 50 itself, and the like can be mentioned.

  On the other hand, when BL3 = 1 (the electric load 22 is operating) (step 52) and the changeover switch 44 is off (step 53), the control unit 38 sets the current I6 flowing through the redundant power supply system 6 to the threshold value Ith. In the above case (step 56), an abnormality in the power supply system of the low voltage system 10 (for example, an open failure of a terminal or a cell of the low voltage system battery 14, a failure accompanied by a decrease in the power supplied to the generator 16, a power supply line 46 The control of the DC-DC converter 30 is switched from step-up control to step-down control (step 57).

  Note that the controller 36 may detect an abnormality by monitoring the current I6 flowing through the line based on the output of the current detector 50 when BL3 = 1 without turning off the changeover switch 44. . That is, the control unit 38 determines whether or not the current I6 flowing through the redundant power supply system 6 is zero when BL3 = 1. If the current I6 is zero, the controller 38 considers that the redundant power supply system 6 is abnormal. Warning the driver. On the other hand, when the current I6 flowing through the redundant power supply system 6 is equal to or greater than the threshold value Ith when BL3 = 1, the control unit 38 switches the control of the DC-DC converter 30 from step-up control to step-down control.

  Even in such a configuration, it is possible to monitor I6 flowing through the redundant power supply system 6 and determine that an abnormality has occurred in the low voltage system 10 when a supply current exceeding a threshold Ith larger than the normal supply current flows. it can. Even in this case, it is not necessary to provide a current detector or the like for each of the low voltage system battery 14 and the generator 16 in order to detect an abnormality in the low voltage system 10, and a detection element is provided only in the DC-DC converter 30. It is sufficient to provide it. In addition, it is not necessary to individually detect the current values flowing through the low-voltage battery 14 and the generator 16, and it is sufficient to monitor the current I6 flowing through the redundant power supply system 6.

  Therefore, according to the power supply system of the third embodiment, it is possible to detect the abnormality of the low voltage system 10 only with the elements provided in the DC-DC converter 30, so that the low voltage system 10 has a simple configuration. It is possible to detect abnormalities.

  Also in the above configuration, when the changeover switch 44 is turned off, the low voltage system 10 (specifically, the low voltage system battery 14, the generator 16, and the electric load 20) is disconnected from the DC-DC converter 30. On the other hand, the electrical load 22 of the low voltage system 10 still continues to be connected to the DC-DC converter 30 through the power supply line 48. In this case, power cannot be supplied from the high voltage system 12 to the low voltage system battery 14, the generator 16, and the electrical load 20 of the low voltage system 10 via the DC-DC converter 30. 22 can be supplied with power from the high voltage system 12 via the DC-DC converter 30.

  Therefore, according to the power supply system of the present embodiment, the low voltage system 10 in which an abnormality has occurred is disconnected from the DC-DC converter 30 by opening the changeover switch 44, and the high voltage system is connected to the electric load 22 of the low voltage system 10. Power can be supplied from 12 through the DC-DC converter 30. Further, even if an abnormality occurs in the low voltage system 10 due to, for example, disconnection of the power supply line 46 and the power supply from the low voltage system battery 14 or the generator 16 becomes impossible, the redundant system load 22 is not affected. Can be supplied with power, and the operation of the electric load 22 can be secured. Further, since the power source of the low voltage system 10 can be disconnected from the DC-DC converter 30, the influence of the abnormality of the power source of the low voltage system 10 is prevented from reaching the DC-DC converter 30 and the electric load 22, and the DC-DC Stable power supply from the converter 30 can be performed on the electric load 22. Moreover, since the abnormality determination of the low voltage system 10 is performed during the operation of the electric load 22, an erroneous determination due to the abnormality determination during the non-operation of the electric load 22 can be prevented.

[Fourth embodiment]
FIG. 11 shows a configuration diagram of a power supply system according to the fourth embodiment of the present invention. The fourth embodiment is an example of a case where an abnormality has occurred in the generator (alternator) 16. When an abnormality occurs in the generator 16, the power generation capacity is reduced or the power generation itself is stopped. Therefore, it is necessary to prevent the function of the electrical load 22 such as the emergency call device or the electric brake device from being impaired because the voltage of the low-voltage battery 14 decreases due to the abnormality of the generator 16. In the power supply system of the fourth embodiment shown in FIG. 11, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  In FIG. 11, the abnormality detector 5 for detecting an abnormality of the generator 16 is connected to the control unit 38. The abnormality detector 5 outputs the power generation information of the generator 16 to the control unit 38. The abnormality detector 5 outputs, for example, a power generation state indicating whether or not the power generator 16 is generating power (for example, outputs a Hi signal when power is being generated, and outputs a Lo signal when power is not being generated. The so-called L terminal can be used). The control unit 38 recognizes that the generator 16 is not in the power generation state based on the power generation state of the abnormality detector 5 in spite of the condition that the generator 16 originally generates power, such as when the ignition is ON. In this case, it is determined that the generator 16 is abnormal. The abnormality detector 5 can detect the power generation state of the generator 16 by directly monitoring the output current and output voltage of the generator 16, for example. Moreover, the control part 38 may determine the abnormality of the generator 16 as being a power generation failure, when the power generation amount of the generator 16 detected is below a predetermined value.

  FIG. 12 is a diagram illustrating a relationship among abnormality detection of the generator 16, ON / OFF of the changeover switch 44, and switching control of the DC-DC converter 30 in the present embodiment. The DC-DC converter 30 performs step-up control in the direction from the low voltage system 10 to the high voltage system 12 during normal operation. However, when an abnormality of the generator 16 is detected by the abnormality detector 5, It is considered that the power supply capability has decreased, and the changeover switch 44 is turned off and the step-up control is switched to the step-down control.

  In the present embodiment, the changeover switch 44 is interposed between the low voltage system 10 and the inductance 32 of the DC-DC converter 30 as described above. Of the electric loads 20 and 22 of the low voltage system 10, the electric load 20 is connected to the inductance 32 side of the DC-DC converter 30 via the changeover switch 44, but the electric load 22 is further connected in addition to the connection. The DC-DC converter 30 is connected to the inductance 32 side without going through the changeover switch 44. Therefore, when the abnormality of the generator 16 occurs, even if the generator 16 is disconnected from the DC-DC converter 30, the high-voltage system 12 from the low-voltage battery 14 and via the DC-DC converter 30. Therefore, it is possible to supply power to the redundant electrical load 22.

  FIG. 13 is a flowchart of an example of a control routine executed by the control unit 38 of the fourth embodiment. The controller 38 monitors the abnormality of the generator 16 based on the output of the abnormality detector 5 (step 60). When the abnormality of the generator 16 is detected (step 62), the control unit 38 transmits an operation switching signal from step-up control to step-down control to the DC-DC converter 30 to control the DC-DC converter 30. Is switched from step-up control to step-down control, and the changeover switch 44 is turned off (step 64).

  According to this configuration, the changeover switch 44 that is turned on during normal operation can be turned off when it is detected that an abnormality has occurred in the generator 16. When the changeover switch 44 is turned off, the low voltage system 10 (specifically, the low voltage battery 14, the generator 16, and the electrical load 20) is disconnected from the DC-DC converter 30, while the low voltage system The ten electric loads 22 continue to be connected to the low-voltage battery 14 and to the DC-DC converter 30 through the power supply line 48. In this case, power cannot be supplied from the high voltage system 12 to the low voltage system battery 14, the generator 16, and the electrical load 20 of the low voltage system 10 via the DC-DC converter 30. The electric power from the low-voltage system battery 14 and the electric power from the high-voltage system 12 via the DC-DC converter 30 can be supplied to 22.

  Therefore, according to the power supply system of the present embodiment, the low voltage system 10 in which an abnormality has occurred is disconnected from the DC-DC converter 30 by opening the changeover switch 44, and the electric load 22 of the low voltage system 10 has a high voltage. Power can be supplied from the system 12 via the DC-DC converter 30 and can be supplied from the low-voltage battery 14. In this respect, in the power supply system of this embodiment, when the changeover switch 44 is turned off, power is supplied from the high voltage system 12 through the DC-DC converter 30 to the low voltage system 10 in which an abnormality has occurred. It is possible to prevent. Further, by supplying power to the redundant electrical load 22 by both the low voltage battery 14 and the high voltage battery 18 via the DC-DC converter 30, the redundant load 22 can be supplied with the highest priority. In addition, it is possible to extend the time during which power can be supplied to the redundant load 22. In the case of a Mayday device that transmits an emergency signal in the event of an accident or an electric brake device that can assist the driver's brake operation and stabilize the behavior of the vehicle, the extension of the operation time leads to an improvement in the merchantability. In this case, by stopping or limiting the operations of the electric load 20 and the electric load 24, the power supply possible time to the redundant load 22 can be further extended. Further, by detecting the failure of the generator 16, it is possible to promptly shift to a predetermined protection control before a decrease in the power supplied to the redundant load 22 occurs.

[Fifth embodiment]
FIG. 14 shows a configuration diagram of a power supply system according to the fifth embodiment of the present invention. In the fifth embodiment, on / off of the changeover switch 44 is controlled based on the detection result of the voltage of the power supply line 46 that is the power supply path from the low-voltage battery 14 to the redundant load 22. When the voltage supplied to the redundant load 22 is reduced, the redundant load 22 and the DC-DC converter 30 are separated from the location where the failure has occurred, and the redundant load 22 and the DC-DC converter 30 are connected to each other. 22 functions are protected. In the power supply system of the fifth embodiment shown in FIG. 14, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  In FIG. 14, the voltage detector 4 for detecting the voltage of the power supply line 46 is connected to the control unit 38. The voltage detector 4 outputs the voltage information of the power supply line 46 to the control unit 38. The voltage detector 4 has a threshold value for determining a decrease in the supply voltage (that is, the voltage of the power supply line 46) from the low-voltage battery 14 to the redundant load 22, and the supply voltage is equal to or less than the threshold value. In the case, the voltage drop signal is output to the control unit 38. The control unit 38 that has received the voltage drop signal considers that the voltage of the power supply line 46 has dropped due to some abnormality such as a reduction in the remaining charge capacity of the low-voltage battery 14, turns off the changeover switch 44, and DC-DC An operation switching signal for switching the voltage conversion direction from the step-up direction to the step-down direction is output to the converter 30. The DC-DC converter 30 performs step-up control in the direction from the low voltage system 10 to the high voltage system 12 during normal operation, but when the operation switching signal is received due to a voltage drop in the power supply line 46, the switch 44 is turned off. At the same time, step-up control is switched to step-down control. By turning off the changeover switch 44, it is possible to prevent the power to be supplied from the DC-DC converter 30 to the redundant load 22 from being supplied to the low-voltage battery 14 in the event of an abnormality. When the voltage of the power supply line 46 becomes higher than the threshold value, the control unit 38 turns on the changeover switch 44 and switches from step-down control to step-up control to return to normal operation.

  Further, the control unit 38 determines that the voltage detector 4 causes the voltage of the power supply line 46 to be equal to or lower than a predetermined threshold voltage and the voltage on the low voltage system 10 side of the DC-DC converter 30 is equal to or higher than the predetermined threshold voltage. The cause of the voltage drop of the power supply line 46 can be specified as the disconnection of the power supply line 46.

  FIG. 15 is a diagram illustrating a relationship among voltage detection of the voltage detector 4, on / off of the changeover switch 44, and switching control of the DC-DC converter 30 in the present embodiment. Vm represents the supply voltage from the low voltage system battery 14 to the redundant load 22 (that is, the voltage of the power supply line 46), Vd represents the voltage on the low voltage system 10 side of the DC-DC converter 30, and Vt represents the power supply line. The threshold value for determining the voltage drop of 46 is represented. The DC-DC converter 30 performs step-up control in the direction from the low voltage system 10 to the high voltage system 12 during normal operation. However, when Vm and Vd are equal to or lower than the threshold value Vt, the low voltage system 10 is considered to be abnormal. The step-up control is switched to the step-down control when the selector switch 44 is turned off by the unit 38. Note that when only Vm becomes equal to or less than the threshold value Vt, the changeover switch 44 may be turned on and remain in step-up control to warn the driver that there is an abnormality.

  In the present embodiment, the changeover switch 44 is interposed between the low voltage system 10 and the inductance 32 of the DC-DC converter 30 as described above. Of the electric loads 20 and 22 of the low voltage system 10, the electric load 20 is connected to the inductance 32 side of the DC-DC converter 30 via the changeover switch 44, but the electric load 22 is further connected in addition to the connection. The DC-DC converter 30 is connected to the inductance 32 side without going through the changeover switch 44. Therefore, even if the generator 16 is disconnected from the DC-DC converter 30 when a voltage drop occurs in the power supply line 46, the redundant system is directly connected from the high voltage system 12 via the DC-DC converter 30. It is possible to supply electric power to the electrical load 22 of the current. If the power supply line 46 is not disconnected, it is possible to supply power to the electric load 22 from the low-voltage battery 14.

  FIG. 16 is a flowchart of an example of a control routine executed by the control unit 38 of the fifth embodiment. The control unit 38 monitors the voltage of the power supply line 46 based on the output of the voltage detector 4 (step 70). When the voltage Vm of the power supply line 46 is equal to or lower than the threshold value Vt and the voltage Vd on the low voltage system 10 side of the DC-DC converter 30 is equal to or lower than the threshold value Vt (Steps 72 and 74). The control of the DC-DC converter 30 is switched from step-up control to step-down control, and the changeover switch 44 is turned off to warn the driver (step 76). On the other hand, when the voltage Vm of the power supply line 46 is equal to or lower than the threshold value Vt and the voltage Vd on the low voltage system 10 side of the DC-DC converter 30 is not equal to or lower than the threshold value Vt (steps 72 and 74). The power supply line 46 is regarded as a disconnection, and only a warning is given to the driver without switching the changeover switch 44 or the voltage conversion direction (step 78). This is because if the disconnection of the power supply line 46 can be specified, the power supply from the low-voltage battery 14 to the redundant load 22 can be continued through the power supply line 47 and the on-state changeover switch 44.

  According to such a configuration, it has been detected that the changeover switch 44 that is turned on during normal operation has caused a drop in the voltage Vd on the low voltage system 10 side of the DC-DC converter 30 and the voltage Vm of the power supply line 46. In case it can be turned off. When the changeover switch 44 is turned off, the low voltage system 10 (specifically, the low voltage battery 14 and the generator 16) is disconnected from the DC-DC converter 30, while the electric load 22 of the low voltage system 10 is disconnected. Still continues to connect to the DC-DC converter 30 through the power supply line 48. In this case, power cannot be supplied from the high voltage system 12 to the low voltage system battery 14 or the generator 16 of the low voltage system 10 via the DC-DC converter 30, but the electrical load 22 is not high. Electric power from the voltage system 12 via the DC-DC converter 30 can be supplied.

  Therefore, according to the power supply system of the present embodiment, the low voltage system 10 in which an abnormality has occurred is disconnected from the DC-DC converter 30 by opening the changeover switch 44, and the high voltage system is connected to the electric load 22 of the low voltage system 10. Power can be supplied from 12 through the DC-DC converter 30. In this respect, in the power supply system of the present embodiment, it is possible to prevent wasteful power supply from the high voltage system 12 via the DC-DC converter 30 to the low voltage system 10 in which an abnormality has occurred. ing. If the power supply line 46 is not disconnected, it is possible to supply power to the electric load 22 from the low-voltage battery 14. At this time, by supplying power to the redundant electrical load 22 by both the low voltage battery 14 and the high voltage battery 18 via the DC-DC converter 30, the redundant load 22 can be supplied with the highest priority. It is also possible to extend the time during which power can be supplied to the redundant load 22. In the case of a Mayday device that transmits an emergency signal in the event of an accident, extending the operating time leads to an improvement in merchantability. In this case, by stopping or limiting the operations of the electric load 20 and the electric load 24, the power supply possible time to the redundant load 22 can be further extended.

[Sixth embodiment]
FIG. 17 shows a configuration diagram of a power supply system according to the sixth embodiment of the present invention. In the sixth embodiment, on / off of the changeover switch 44 is controlled based on the detection result of the voltage of the power supply line 46 that is the power supply path from the low-voltage battery 14 to the redundant load 22. When the voltage supplied to the redundant load 22 is reduced, the redundant load 22 and the DC-DC converter 30 are separated from the location where the failure has occurred, and the redundant load 22 and the DC-DC converter 30 are connected to each other. 22 functions are protected. The power supply system of the sixth embodiment is obtained by changing the diode OR circuit including the diodes 7 and 8 in the fifth embodiment to the changeover switch 3. In the power supply system of the sixth embodiment shown in FIG. 17, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted or simplified.

  When the voltage of the power supply line 46 and the voltage on the low voltage system 10 side of the DC-DC converter 30 are equal to or lower than a predetermined threshold voltage, the control unit 38 turns off the changeover switch 44 to turn off the low voltage system battery 14 and the DC-DC. The converter 30 is separated. Further, the control unit 38 controls the changeover switch 3 to separate the electric load 22 and the power supply line 46 and connect the electric load 22 and the power supply line 48. In addition, the control unit 38 transmits an operation switching signal that instructs the DC-DC converter 30 to switch the voltage conversion direction from the step-up direction to the step-down direction.

  When the DC-DC converter 30 receives the operation switching signal from the control unit 38, the DC-DC converter 30 switches from step-up control to step-down control. When the power supply line 46 is disconnected, a voltage drop is detected by the voltage detector 4, but power can be supplied from the low-voltage battery 14 via the power supply lines 47 and 48, so that only a warning is issued and normal operation is performed. . Here, even if a voltage drop is detected by the voltage detector 4, if the voltage supplied from the low voltage battery 14 to the DC-DC converter 30 is higher than a predetermined threshold value, it is regarded as a disconnection of the power supply line 46.

  Note that the output voltage (voltage at point d) on the low voltage system 10 side of the DC-DC converter 30 is slightly higher than the output voltage (voltage at point b) of the generator 16 (low voltage system battery 14) (for example, 1V). When the changeover switch 44 is off, if no current flows through the power supply line 48 during the off-period, the power supply line 48 can be regarded as a disconnection. In this case, the driver may be warned. When the operation of the electric load 24 connected to the high voltage battery 18 is restricted during the step-down control of the DC-DC converter 30, the power supply possible time to the electric load 22 can be extended along with the restriction. Then, when the voltage supplied from the low voltage system battery 14 to the electric load 22 becomes higher than a predetermined threshold value, the normal operation is restored. In this way, even if a failure such as a terminal disconnection of the low-voltage battery 14 or a disconnection of the power supply line 46 occurs, it is possible to prevent the electrical load 22 from being immediately stopped.

  Here, the changeover switch 3 is, for example, a MOSFET made of a semiconductor as shown in FIG. The gate of the changeover switch 3 is connected to the control unit 38. The changeover switch 3 performs a switching operation according to a drive command from the control unit 38 and switches the power supply path of the electric load 22 to the power supply line 46 or 48.

  FIG. 19 is a diagram illustrating a relationship among voltage detection of the voltage detector 4, ON / OFF of the changeover switch 44, ON / OFF of the changeover switch 3, and switching control of the DC-DC converter 30 in the present embodiment. Vm, Vd, and Vt are the same as those in FIG.

  The DC-DC converter 30 performs step-up control in the direction from the low voltage system 10 to the high voltage system 12 during normal operation. The step-up control is switched to the step-down control as the change-over switch 44 is turned off by the unit 38 and the change-over switch 3 is switched from the power supply line 46 side to the power supply line 48 side. Note that when only Vm becomes equal to or less than the threshold value Vt, the changeover switch 44 may be turned on and remain in step-up control to warn the driver that there is an abnormality.

  In the present embodiment, the changeover switch 44 is interposed between the low voltage system 10 and the inductance 32 of the DC-DC converter 30 as described above. Of the electric loads 20 and 22 of the low voltage system 10, the electric load 20 is connected to the inductance 32 side of the DC-DC converter 30 via the changeover switch 44, but the electric load 22 is further connected in addition to the connection. The DC-DC converter 30 is connected to the inductance 32 side without going through the changeover switch 44. Therefore, even if the generator 16 is disconnected from the DC-DC converter 30 when a voltage drop occurs in the power supply line 46, the redundant system is directly connected from the high voltage system 12 via the DC-DC converter 30. It is possible to supply power to the electrical load 22.

  FIG. 20 is a flowchart of an example of a control routine executed by the control unit 38 of the sixth embodiment. The control unit 38 monitors the voltage of the power supply line 46 based on the output of the voltage detector 4 (step 80). When the voltage Vm of the power supply line 46 is equal to or lower than the threshold value Vt and the voltage Vd on the low voltage system 10 side of the DC-DC converter 30 is equal to or lower than the threshold value Vt (steps 82 and 84). The switch 3 switches the connection destination of the electrical load 22 from the power supply line 36 to the power supply line 38, switches the control of the DC-DC converter 30 from step-up control to step-down control, turns off the switch 44, and Is warned (step 86). On the other hand, when the voltage Vm of the power supply line 46 is less than or equal to the threshold value Vt and the voltage Vd of the power supply line 47 is not less than or equal to the threshold value Vt (steps 82 and 84), the control unit 38 Considering a disconnection, only a warning is given to the driver without switching the selector switch 44 or the voltage conversion direction (step 88). This is because if the disconnection of the power supply line 46 can be specified, the power supply from the low-voltage battery 14 to the redundant load 22 can be continued through the power supply line 47 and the on-state changeover switch 44.

  According to such a configuration, it has been detected that the changeover switch 44 that is turned on during normal operation has caused a drop in the voltage Vd on the low voltage system 10 side of the DC-DC converter 30 and the voltage Vm of the power supply line 46. In case it can be turned off. When the changeover switch 44 is turned off, the low voltage system 10 (specifically, the low voltage battery 14 and the generator 16) is disconnected from the DC-DC converter 30, while the electric load 22 of the low voltage system 10 is disconnected. Still continues to connect to the DC-DC converter 30 through the power supply line 48. In this case, power cannot be supplied from the high voltage system 12 to the low voltage system battery 14 or the generator 16 of the low voltage system 10 via the DC-DC converter 30, but the electrical load 22 is not high. Electric power from the voltage system 12 via the DC-DC converter 30 can be supplied.

  Therefore, according to the power supply system of the present embodiment, the low voltage system 10 in which an abnormality has occurred is disconnected from the DC-DC converter 30 by opening the changeover switch 44, and the high voltage system is connected to the electric load 22 of the low voltage system 10. Power can be supplied from 12 through the DC-DC converter 30. In this respect, in the power supply system of the present embodiment, it is possible to prevent wasteful power supply from the high voltage system 12 via the DC-DC converter 30 to the low voltage system 10 in which an abnormality has occurred. ing. If the power supply line 46 is not disconnected, it is possible to supply power to the electric load 22 from the low-voltage battery 14. At this time, by supplying power to the redundant electrical load 22 by both the low voltage battery 14 and the high voltage battery 18 via the DC-DC converter 30, the redundant load 22 can be supplied with the highest priority. It is also possible to extend the time during which power can be supplied to the redundant load 22. In the case of a Mayday device that transmits an emergency signal in the event of an accident, the extension of the operation time leads to an improvement in merchandise. In this case, by stopping or limiting the operations of the electric load 20 and the electric load 24, the power supply possible time to the redundant load 22 can be further extended.

[Seventh embodiment]
FIG. 21 shows a configuration diagram of a power supply system according to the seventh embodiment of the present invention. In the seventh power supply system shown in FIG. 21, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted or simplified. The system of the seventh embodiment is a system that is mounted on, for example, a vehicle and controls a step-up / step-down DC-DC converter that boosts and lowers a power supply voltage, for reducing exhaust gas and improving fuel efficiency. This is an idling stop system that automatically stops the engine while the vehicle is stopped. In the seventh embodiment, the DC-DC converter 30 is switched from step-up control to step-down control before the engine is stopped by the idling stop system, so that electric power is supplied to the electric loads 20 and 22 or can be supplied. . Then, when the engine is restarted, the low voltage system 10 constituting the starter 2 is disconnected from the DC-DC converter 30 before the starter 2 for starting the engine is driven. By supplying power to the electric load 22 from the DC-DC converter 30 separated from the low voltage system 10, the influence of voltage fluctuation due to the drive of the starter 2 does not reach the electric load 22, and stable electric power supply to the electric load 22 is achieved. It becomes possible.

  FIG. 22 is a time chart showing the operation of the power supply system of the seventh embodiment. The operation of the power supply system according to the present embodiment will be described with reference to FIGS.

  In the system of this embodiment, when the operation of the electric loads 20 and 22 of the low voltage system 10 is required, power is supplied from the low voltage system battery 14 or the generator 16 to the electric loads 20 and 22. In this case, the electric loads 20 and 22 can be operated. Further, when an operation of the electric load 24 of the high voltage system 12 is requested, power is supplied from the high voltage system battery 18 to the electric load 24. In this case, the electric load 24 can be operated.

  As in the above-described embodiment, the control unit 38 of the DC-DC converter 30 supplies power to the low voltage system 10 (for example, the voltage value of the low voltage system 10 (low voltage battery 14) and the remaining capacity of the low voltage battery 14). Etc.) and the power supply state of the high voltage system 12 (for example, the voltage value of the high voltage system 12 (high voltage battery 18) and the remaining capacity of the high voltage battery 18). By determining whether or not step-up conversion to the system 12 is necessary, and conversely determining whether or not step-down conversion from the high voltage system 12 to the low voltage system 10 is necessary, DC-DC It is determined whether or not the converter 30 should be activated. When the DC-DC converter 30 is to be started, the changeover switch 44 is turned on to make the low voltage system 10 and the DC-DC converter 30 conductive, and according to the state of both voltage systems 10 and 12. The duty ratio of the pair of switching elements 40 and 42 is set.

  In a normal state in which the engine is operating, the electric power generated by the generator 16 is supplied to the low-voltage battery 14 and the electric loads 20 and 22. Further, the power of the low voltage system 10 is supplied to the high voltage battery 18 of the high voltage system 12 and the electric load 24 by the boost control of the DC-DC converter 30. In this normal state, the control unit 38 turns on the changeover switch 44 to make it conductive.

  The control unit 38 that has received the engine stop request signal from the idling stop system switches the control of the DC-DC converter 30 from step-up control to step-down control, and transmits an engine stop permission signal to the idling stop system after switching. The idling stop system that has received the engine stop permission signal stops the engine. Power generation by the generator 16 is stopped by stopping the engine.

  The engine is restarted by driving a starter 2 with a built-in electric motor. When the control unit 38 receives a pre-drive signal that informs in advance of the drive of the starter 2, the control unit 38 turns off the changeover switch 44 to make it non-conductive. When the changeover switch 44 is turned off, the output on the low voltage system 10 side of the DC-DC converter 30 is separated from the starter 2, the low voltage battery 14, and the electric load 20. After the separation, the control unit 38 transmits a permission signal for permitting the drive of the starter 2 to a control system that controls the drive of the starter 2, and the starter 2 is driven. When the starter 2 is driven, the engine restarts and the generator 16 starts generating power. The control unit 38 that has detected the power generation state of the generator 16 turns on the changeover switch 44 and switches the control of the DC-DC converter 30 from step-down control to step-up control.

  In this way, by controlling the on / off of the changeover switch 44 and the voltage conversion direction of the DC-DC converter 30, stable electric power can be supplied to the electric loads 20 and 22. That is, even when the engine at which the power generation of the generator 16 is stopped is stopped, the DC-DC converter 30 is switched to step-down control so that power can be supplied from the high-voltage battery 18, and the low-voltage battery 14 and the electric load 20 can be supplied. , 22 can be stably fed. Further, even when the engine restarts when the power supply voltage of the low voltage system 10 fluctuates due to driving of the starter 2, the influence of the voltage fluctuation due to the changeover of the changeover switch 44 is low in the electric load 22 and the DC-DC converter 30. Since it does not reach the output on the voltage system 10 side, stable power feeding to the electric load 22 is possible. Although the power supply voltage of the low voltage system 10 on the anode side of the diode 7 is reduced by driving the starter 2, the output voltage on the low voltage system 10 side (the anode side of the diode 8) of the DC-DC converter 30 is the anode of the diode 7. Since the voltage is higher than the power supply voltage of the low-voltage system 10 on the side, the electric load 22 is stably fed from the DC-DC converter 30.

  In the case where the electrical load 22 is an electrical load that blinks due to voltage fluctuation such as a lamp or meter, the following control may be performed. The control unit 38 that has received the engine stop request signal from the idling stop system sets the output voltage on the low voltage system 10 side of the DC-DC converter 30 to the same power generation voltage as that of the generator 16, and then the DC-DC converter 30. The control is switched from step-up control to step-down control, and an engine stop permission signal is transmitted to the idling stop system after switching. The idling stop system that has received the engine stop permission signal stops the engine. Power generation by the generator 16 is stopped by stopping the engine.

  When the engine is restarted, as described above, the control unit 38 turns off the changeover switch 44 and puts it into a non-conducting state when it receives a pre-drive signal notifying the drive of the starter 2 in advance. Then, after setting the output voltage of the generator 16 to the output voltage on the low voltage system 10 side of the DC-DC converter 30, the control unit 38 controls the drive of the starter 2 with a permission signal permitting the drive of the starter 2. The data is transmitted to the control system, and the starter 2 is driven. When the starter 2 is driven, the engine restarts and the generator 16 starts generating power. The control unit 38 that has detected the power generation state of the generator 16 based on the generated voltage or the like turns on the changeover switch 44 and switches the control of the DC-DC converter 30 from step-down control to step-up control.

  In this way, by controlling the on / off of the changeover switch 44, the voltage conversion direction of the DC-DC converter 30, the output voltage thereof, and the output voltage of the generator 16, the electric load 22 is caused by voltage fluctuations such as lamps and meters. Even an electric load that blinks can prevent blinking. That is, when the engine is stopped or restarted, the output voltage of the generator 16 and the output voltage on the low-voltage system 10 side of the DC-DC converter 30 are set to be the same, so that the voltage fluctuation to the lamp or meter is changed. Since the power supply system can be switched while being suppressed, blinking due to voltage fluctuation can be prevented, and the merchantability of the vehicle is improved.

  Incidentally, the following control may be executed when the engine is stopped by the idling stop system. When the engine is stopped by the idling stop system, the control unit 38 monitors the remaining capacity of the low voltage system battery 14 and the high voltage system battery 18 by the voltage of each battery or SOC (State of Charge), and the remaining capacity thereof. When the battery voltage becomes equal to or lower than a predetermined threshold value, control is performed to charge a battery that is equal to or lower than the threshold value.

  Here, the predetermined threshold is a minimum remaining capacity at which all loads can operate normally when the engine is restarted. The predetermined threshold for the low voltage battery 14 is a remaining capacity capable of driving the starter 2, and the predetermined threshold for the high voltage battery 18 is a remaining capacity required by the electric load 22 during driving of the starter 2, and the engine. This is the remaining capacity at which the high-voltage system load 18 can be driven at least until the DC-DC converter 30 starts the boost control after startup.

  For example, when the remaining capacity of the low-voltage system battery 14 is equal to or lower than a predetermined threshold value while the engine is stopped, the control unit 38 turns off the changeover switch 44 to make it non-conductive. When the changeover switch 44 is turned off, the output on the low voltage system 10 side of the DC-DC converter 30 is separated from the starter 2, the low voltage battery 14, and the electric load 20. After the separation, the control unit 38 transmits a permission signal for permitting the drive of the starter 2 to a control system that controls the drive of the starter 2, and the starter 2 is driven. When the starter 2 is driven, the engine restarts and the generator 16 starts generating power. The control unit 38 that has detected the power generation state of the generator 16 turns on the changeover switch 44 and switches the control of the DC-DC converter 30 from step-down control to step-up control. As described above, the low-voltage battery 14 can be charged by forcibly generating power when the remaining capacity of the low-voltage battery 14 becomes a predetermined threshold value or less while the engine is stopped. Note that the control unit 38 drives the starter 2 when the remaining capacity of the high-voltage battery 18 is sufficient even when the remaining capacity of the low-voltage battery 14 falls below a predetermined threshold value while the engine is stopped. Without the changeover switch 44 being turned on, the low voltage system battery 14 is fed by supplying power to the low voltage system 10 side until the remaining capacity of the high voltage system battery 18 is lowered to a predetermined threshold by the step-down control of the DC-DC converter 30. May be charged.

  Further, for example, when the remaining capacity of the high-voltage battery 18 becomes equal to or less than a predetermined threshold value while the engine is stopped, the control unit 38 turns off the changeover switch 44 to make it non-conductive. When the changeover switch 44 is turned off, the output on the low voltage system 10 side of the DC-DC converter 30 is separated from the starter 2, the low voltage battery 14, and the electric load 20. After the separation, the control unit 38 transmits a permission signal for permitting the drive of the starter 2 to a control system that controls the drive of the starter 2, and the starter 2 is driven. When the starter 2 is driven, the engine restarts and the generator 16 starts generating power. The control unit 38 that has detected the power generation state of the generator 16 turns on the changeover switch 44 and switches the control of the DC-DC converter 30 from step-down control to step-up control. As described above, when the remaining capacity of the high-voltage battery 18 becomes equal to or lower than the predetermined threshold value while the engine is stopped, the high-voltage battery 18 can be charged by forcibly boosting the voltage. Note that the control unit 38 drives the starter 2 when the remaining capacity of the low-voltage battery 14 is sufficient even when the remaining capacity of the high-voltage battery 18 falls below a predetermined threshold value while the engine is stopped. Without switching, the high voltage system battery 18 is fed by supplying power to the high voltage system 12 until the remaining capacity of the low voltage system battery 18 is lowered to a predetermined threshold value by the boost control of the DC-DC converter 30 with the changeover switch 44 turned on. May be charged.

  In this way, when the remaining capacity of each battery becomes equal to or less than a predetermined threshold value, the electric load 20 of the low voltage system 10 is controlled when the engine is restarted by performing control for charging the battery that is equal to or less than the threshold value. Therefore, it is possible to prevent the power supply to the electric load 24 of the high voltage system 12 and the high voltage system 12 from being insufficient, and to stop the engine by the idling stop system at an appropriate time.

  By the way, in order to suppress the power loss of the DC-DC converter 30 while the engine is stopped, the following control may be executed when the engine is stopped by the idling stop system. FIG. 23 is a second time chart showing the operation of the power supply system of the seventh embodiment. Receiving the engine stop request signal from the idling stop system, the control unit 38 stops the boost control of the DC-DC converter 30, and transmits the engine stop permission signal to the idling stop system. The idling stop system that has received the engine stop permission signal stops the engine. Power generation by the generator 16 is stopped by stopping the engine. Therefore, when the engine is stopped, the electric loads 20 and 22 are supplied with electric power from the low voltage system battery 14, and the high voltage system load 24 is supplied with electric power from the high voltage system battery 18.

  When the engine is restarted, as described above, the control unit 38 turns off the changeover switch 44 and puts it into a non-conducting state when it receives a pre-drive signal notifying the drive of the starter 2 in advance. Then, after switching the control of the DC-DC converter 30 from the stopped state to the step-down control, the control unit 38 transmits a permission signal for permitting the drive of the starter 2 to the control system for controlling the drive of the starter 2. Is driven. When the starter 2 is driven, the engine restarts and the generator 16 starts generating power. The control unit 38 that has detected the power generation state of the generator 16 based on the generated voltage or the like turns on the changeover switch 44 and switches the control of the DC-DC converter 30 from step-down control to step-up control.

  In addition, the voltage fluctuation of the low-voltage loads 20 and 22 can be prevented by gradually changing the output voltage of the generator 16 to the open voltage of the low-voltage battery 14 before stopping the engine and then stopping the engine. Further, when the engine is stopped, the remaining capacities of the low-voltage battery 14 and the high-voltage battery 18 are monitored, and when those remaining capacities are below a predetermined threshold, the batteries that are below the threshold are charged. Control may be implemented.

  In this way, by stopping the DC-DC converter 30 while the engine is stopped, power loss due to the DC-DC converter 30 can be suppressed.

[Eighth embodiment]
FIG. 24 shows a configuration diagram of a power supply system according to the eighth embodiment of the present invention. In the eighth power supply system shown in FIG. 24, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted or simplified. The system of the eighth embodiment is an idling stop system similar to the system of the seventh embodiment. Unlike the seventh embodiment, in the eighth embodiment, the electric load 22 is divided into electric loads 22a and 22b. The electrical load 22a is a load (for example, an emergency notification device, a brake device, etc.) that needs to operate even when an abnormality such as a failure of the low voltage system 10 occurs. The electrical load 22b is an electrical load that blinks due to voltage fluctuations such as lamps and meters.

  Changeover switches 44 a and 44 b are interposed between the low voltage system 10 and the inductance 32 of the DC-DC converter 30. That is, the low voltage system battery 14 and the generator 16 of the low voltage system 10 are connected to the inductance 32 side of the DC-DC converter 30 via the changeover switch 44a. The changeover switches 44a and 44b are MOSFETs made of a semiconductor as shown in FIG. 2, for example. The changeover switches 44a and 44b are disposed in the DC-DC converter 30, and their gates are connected to the control unit 38 described above. As will be described later in detail, the control unit 38 performs switching driving of the changeover switches 44a and 44b as appropriate. The change-over switches 44a and 44b perform a switching operation in accordance with a drive command from the control unit 38, and conduct / cut off between the low voltage system 10 and the inductance 32.

  The electrical load 22a of the low voltage system 10 is connected in parallel to the low voltage system battery 14 and the generator 16, and is connected to the inductance 32 side of the DC-DC converter 30 via the changeover switch 44a. It is connected to the inductance 32 side of the DC-DC converter 30 without going through the changeover switch 44a. That is, the electric load 22a is connected to the power supply line 46a from the low-voltage system 10 and the power supply line 48a from the DC-DC converter 30 not via the changeover switch 44a.

  The electric load 22b of the low voltage system 10 is connected in parallel to the low voltage system battery 14 and the generator 16, and is connected to the inductance 32 side of the DC-DC converter 30 via the changeover switch 44a. Furthermore, it is connected to the inductance 32 side of the DC-DC converter 30 via the changeover switch 44b without passing through the changeover switch 44a. That is, the power supply line 48b from the DC-DC converter 30 through the changeover switch 44b is connected to the electrical load 22b together with the power supply line 46b from the low voltage system 10.

  Next, the operation of the power supply system according to the eighth embodiment will be described. In a normal state in which the engine is operating, the electric power generated by the generator 16 is supplied to the low voltage battery 14 and the electric loads 20, 22a, 22b. Further, the power of the low voltage system 10 is supplied to the high voltage battery 18 of the high voltage system 12 and the electric load 24 by the boost control of the DC-DC converter 30. In this normal state, the control unit 38 turns on the changeover switches 44a and 44b to bring them into a conductive state.

  The control unit 38 that has received the engine stop request signal from the idling stop system sets the output voltage on the low voltage system 10 side of the DC-DC converter 30 to the same power generation voltage as that of the generator 16, and then the DC-DC converter 30. The control is switched from step-up control to step-down control, and an engine stop permission signal is transmitted to the idling stop system after switching. The idling stop system that has received the engine stop permission signal stops the engine. Power generation by the generator 16 is stopped by stopping the engine.

  The engine is restarted by driving the starter 2. When the control unit 38 receives a pre-drive signal that notifies the starter 2 of driving in advance, the control unit 38 turns off the changeover switch 44a to make it non-conductive. The output on the low voltage system 10 side of the DC-DC converter 30 is separated from the starter 2, the low voltage battery 14, and the electric load 20 by turning off the changeover switch 44 a. After the separation, the control unit 38 sets the output voltage of the generator 16 to the output voltage on the low voltage system 10 side of the DC-DC converter 30 and then controls the drive of the starter 2 with a permission signal permitting the drive of the starter 2. And the starter 2 is driven. When the starter 2 is driven, the engine restarts and the generator 16 starts generating power. The control unit 38 that has detected the power generation state of the generator 16 turns on the changeover switch 44a and switches the control of the DC-DC converter 30 from step-down control to step-up control.

  Similarly to the above-described embodiment, when an abnormality in the power supply of the low voltage system 10 is detected, the control unit 38 switches from the switching switches 44a and 44b off and the step-up control of the DC-DC converter 30 to the step-down control. Switch over.

  Thus, by controlling the on / off of the changeover switch 44a and the voltage conversion direction of the DC-DC converter 30, stable power can be supplied to the electric loads 20, 22a, and 22b. Further, by controlling the on / off of the changeover switch 44a, the voltage conversion direction of the DC-DC converter 30, the output voltage thereof, and the output voltage of the generator 16, the electric load 22b flickers due to voltage fluctuations such as a lamp or meter. Flickering can be prevented even with an electrical load. In addition, when an abnormality occurs in the power supply of the low voltage system 10, DC is preferentially applied only to the electrical load 22a that is a load that needs to operate even when the low voltage system 10 is abnormal by turning off the changeover switches 44a and 44b. -Since power can be supplied from the DC converter 30, it is possible to extend the time during which power can be supplied to the electrical load 22.

  By the way, in the power supply systems of the first to eighth embodiments, the DC-DC converter converts the input voltage bi-directionally between the low voltage system 10 and the high voltage system 12 to supply and output power. However, the present invention is not limited to this, and is applied to a step-up DC-DC converter that steps up power input from the low voltage system 10 and outputs the boosted power to the high voltage system 12. Alternatively, it may be applied to a step-down DC-DC converter that steps down the power input from the high voltage system 12 and outputs it to the low voltage system 10.

  Also, it is possible to implement control combining any one of the power supply systems of the first to eighth embodiments.

The block diagram of the power supply system which is 1st Example of this invention is shown. It is a block diagram of the selector switch with which the power supply system of a present Example is provided. FIG. 3 is a first diagram illustrating a relationship between a current I6 flowing through an electric load 22 via a power supply line 48 and on / off of a changeover switch 44 in the DC-DC converter 30 of the present embodiment. The flowchart of the example of a control routine which the control part 38 performs in the DC-DC converter 30 of 1st Example is shown. The flowchart of the example of a control routine which the control part 38 performs in the DC-DC converter 30 of 1st Example is shown. The flowchart of the example of a control routine which the control part 38 performs in the DC-DC converter 30 of 1st Example is shown. FIG. 6 is a second diagram illustrating the relationship between the current I6 flowing through the electric load 22 via the power supply line 48 and the on / off state of the changeover switch 44 in the DC-DC converter 30 of the present embodiment. The flowchart of the example of a control routine which the control part 38 performs in the DC-DC converter 30 of 2nd Example is shown. The flowchart of the example of a control routine which the control part 38 performs in the DC-DC converter 30 of 2nd Example is shown. The flowchart of the example of control routine which the control part 38 performs in the DC-DC converter 30 of 3rd Example is shown. The block diagram of the power supply system which is 4th Example of this invention is shown. It is a figure showing the relationship between abnormality detection of the generator 16, ON / OFF of the changeover switch 44, and switching control of the DC-DC converter 30 in a present Example. It is a flowchart of the example of a control routine which the control part 38 of 4th Example performs. The block diagram of the power supply system which is 5th Example of this invention is shown. It is a figure which shows the relationship between the voltage detection of the voltage detector 4, the ON / OFF of the changeover switch 44, and the switching control of the DC-DC converter 30 in a present Example. It is a flowchart of the example of a control routine which the control part 38 of 5th Example performs. The block diagram of the power supply system which is 6th Example of this invention is shown. It is a block diagram of the selector switch with which the power supply system of a present Example is provided. It is a figure which shows the relationship between the voltage detection of the voltage detector 4, ON / OFF of the changeover switch 44, ON / OFF of the changeover switch 3, and the switching control of the DC-DC converter 30 in a present Example. It is a flowchart of the example of a control routine which the control part 38 of 6th Example performs. The block diagram of the power supply system which is 7th Example of this invention is shown. It is a time chart which shows operation | movement of the power supply system of 7th Example. It is a 2nd time chart which shows operation | movement of the power supply system of 7th Example. The block diagram of the power supply system which is 8th Example of this invention is shown.

Explanation of symbols

2 Starter 4 Voltage detector 5 Abnormality detector 6 Redundant power supply system 7, 8 Diode 9 Signal line 10 Low voltage system 12 High voltage system 14 Low voltage system battery 16 Generator 18 High voltage system battery 20 Low voltage system electrical load 22 Low voltage system electrical load Load (redundant load)
30 DC-DC converter 32 Inductor 34 Low voltage system capacitor 38 Control unit 3,44 Changeover switch

Claims (14)

Voltage conversion means for converting the voltage of the first voltage system and the voltage of the second voltage system;
A power supply system that converts the voltage of one voltage system to the other voltage system through the voltage conversion means,
Either voltage system is
A first power supply system for supplying power to the electric load of the voltage system;
A blocking means capable of blocking conduction between the first power feeding system and the voltage converting means;
A power supply system comprising: a second power supply system that enables power supply from the power supply conversion means to the electric load of the voltage system when the interruption means interrupts the conduction. Power supply state detecting means for detecting the power supply state of the voltage system;
An abnormality determining means for determining an abnormality of the voltage system based on a detection result of the power supply state detecting means,
2. The power supply system according to claim 1, wherein when the abnormality determination unit determines that the voltage system is abnormal, the interruption unit interrupts the conduction. The second power supply system is a power supply system that enables power supply from the power conversion means to the electric load of the voltage system not only when the interruption means interrupts the conduction but also when there is the conduction. There,
The power supply state detection means detects a current through the second power supply system,
The abnormality determining unit determines that the voltage system is abnormal as an abnormality of the first power feeding system when the current value through the second power feeding system is detected by the power feeding state detecting unit to be equal to or greater than a predetermined threshold value. The power supply system according to claim 2. The second power supply system is a power supply system that enables power supply from the power conversion means to the electric load of the voltage system not only when the interruption means interrupts the conduction but also when there is the conduction. There,
The power supply state detection means detects a current through the second power supply system,
The abnormality determining means determines that the second power feeding system is abnormal when the current flowing through the second power feeding path is not detected by the power feeding state detecting means;
3. The power supply system according to claim 2, wherein when the abnormality determination unit determines that the second power feeding system is abnormal, the interruption unit stops interruption of the conduction. The second power supply system is a power supply system that enables power supply from the power conversion means to the electric load of the voltage system not only when the interruption means interrupts the conduction but also when there is the conduction. There,
A power supply state detection means for detecting a current through the second power supply system during a cutoff period by the cutoff means;
An abnormality determining unit that determines that the first power feeding system is abnormal when a current value through the second power feeding system is detected by the power feeding state detecting unit to be equal to or greater than a predetermined threshold;
2. The power supply system according to claim 1, wherein when the abnormality determining unit determines that the first power feeding system is abnormal, the blocking unit continues to block the conduction. The second power supply system is a power supply system that enables power supply from the power conversion means to the electric load of the voltage system not only when the interruption means interrupts the conduction but also when there is the conduction. There,
A power supply state detection means for detecting a current through the second power supply system during a cutoff period by the cutoff means;
An abnormality determining means for determining an abnormality of the second power feeding system when the current through the second power feeding system is not detected by the power feeding state detecting means;
2. The power supply system according to claim 1, wherein when the abnormality determination unit determines that the second power feeding system is abnormal, the interruption unit stops interruption of the conduction. The power supply state detecting means detects a power supply voltage of the first power supply system,
The abnormality determination unit determines that the voltage system is abnormal as an abnormality of the first power supply system when the power supply voltage detection value of the first power supply system is detected below a predetermined threshold by the power supply state detection unit. The power supply system according to claim 2. The first power supply system includes a generator,
The power supply state detection means detects the power generation state of the generator,
The abnormality determination unit determines that the voltage system is abnormal as an abnormality of the generator when the power generation state of the generator is detected as a power generation failure state by the power supply state detection unit. The described power supply system. The first power supply system includes a power storage device,
When the interruption means is interrupting the continuity due to the abnormality determination means determining the abnormality of the voltage system as an abnormality of the generator, the electric storage device with respect to the electric load of the voltage system The power supply system according to claim 8, wherein power is supplied. A starter motor for starting the engine is connected to the first power feeding system,
10. The power supply system according to claim 1, wherein when the engine is started by the starter motor, the blocking unit blocks the conduction.   The power supply system according to claim 10, wherein the shut-off means shuts off the continuity before the starter motor is driven, and releases the shut-off of the continuity after the generator is driven by starting the engine.   12. The power supply system according to claim 11, wherein the release of the interruption of conduction is performed after the output voltage of the generator and the output voltage on the voltage system side of the voltage conversion unit are set to be the same.   The power supply system according to any one of claims 1 to 12, wherein the electric load of the voltage system includes a vehicle behavior control device that stabilizes the behavior of the vehicle.   The power supply system according to any one of claims 1 to 12, wherein the electric load of the voltage system includes an electric load in which a visual change is caused by a voltage fluctuation.

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