JP2008154333A - Power supply for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce unnecessary power consumption from a power accumulator to a control section, when the voltage of a main power supply drops. <P>SOLUTION: Since a passage for supplying power from a power accumulator 13 to a control section 17, when the voltage of a main power supply 1 drops is constituted through a third diode 19, having a cathode connected with the power supply terminal 18 of the control section 17 and an anode, connected with the junction point of a transfer switch 15 and a first diode 25, power can be supplied from the power accumulator 13 to the control section 17, if the transfer switch 15 is switched on, and only when power is supplied from the power accumulator 13 to a load 7, and thereby unnecessary power consumption can be reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle power supply apparatus that continuously supplies power to a load when a voltage of a main power supply drops.

  In recent years, idling stop vehicles have been rapidly developed from the viewpoint of global environmental protection. However, in a battery used as the main power supply, if a large current is suddenly supplied at the time of engine start after idling stop or the like, a voltage drop occurs, and there is a possibility that a stable voltage supply to the load cannot be performed. Therefore, for example, Patent Document 1 proposes a vehicle power supply device that can compensate for a voltage even during a sudden load change by mounting a power storage element such as a large-capacity capacitor as an auxiliary power supply in addition to a battery. .

  The configuration of the vehicle power supply device will be described below with reference to FIG.

  A battery 101 as a main power source is connected to a power storage device 105 via an ignition switch (hereinafter referred to as IG switch 103). The output of the power storage device 105 is connected to an electronic control unit 107 that is a load.

  The power storage device 105 has the following configuration.

  The output of the battery 101 is connected to the electronic control unit 107 via the voltage detection means 109 that monitors the voltage, and is also connected to the capacitor unit 113 via the charging circuit 111. Further, the output of the battery 101 is connected to the microcomputer 115 via the IG switch 103. As a result, power is supplied from the battery 101 to the microcomputer 115. The capacitor unit 113 is connected to the electronic control unit 107 via an FET switch 117 that switches the supply of the electric power to the electronic control unit 107. Note that a discharge circuit 119 for forcibly discharging charges stored in the capacitor unit 113 when the IG switch 103 is turned off is connected to the capacitor unit 113.

  Next, the operation at the time of starting such a vehicle power supply device will be described.

  First, when the IG switch 103 is turned on, the power of the battery 101 is supplied to the entire vehicle. As a result, the microcomputer 115 operates. Although omitted in FIG. 3, the IG switch 103 has an accessory state in which the power of the battery 101 is supplied only to the electronic control unit 107 such as an audio, and a start state in which the engine is started, in addition to the on state. In the accessory state, the electric power of the battery 101 is supplied to the electronic control unit 107 via the voltage detection means 109.

  Thus, the microcomputer 115 controls the charging circuit 111 to supply the electric power of the battery 101 to the capacitor unit 113 and performs a charging operation until a certain voltage is reached.

  Next, an operation when power is supplied from the capacitor unit 113 to the electronic control unit 107 when the voltage of the battery 101 drops will be described.

  The microcomputer 115 monitors the voltage Vb of the battery 101 by the voltage detection means 109, and this voltage Vb is set to a predetermined reference voltage (an operation lower limit voltage of the microcomputer 115 which is a control unit, a circuit variation or an operation lower limit voltage of the load). When the voltage is equal to or less than the voltage obtained by adding a margin such as the FET switch 117, the FET switch 117 is turned on.

As a result, since the electric power of the capacitor unit 113 is supplied to the electronic control unit 107, stable electric power can be supplied to the electronic control unit 107 even when the voltage of the battery 101 drops.
JP 2005-28908 A

  In the conventional vehicle power supply device, it is possible to continue to supply power from the capacitor unit 113 to the electronic control unit 107 even when the voltage of the battery 101 drops. However, in the conventional vehicle power supply device shown in FIG. 3, since the power supply source to the microcomputer 115 is only the battery 101 via the IG switch 103, power is supplied to the microcomputer 115 when the voltage of the battery 101 decreases. There was a possibility of becoming impossible.

  In order to avoid this, for example, as shown in FIG. 4, a wiring for supplying power also from the capacitor unit 113 to the microcomputer 115 may be added, and two diodes 121 may be provided to prevent backflow. . As a result, the higher voltage of the battery 101 or the capacitor unit 113 becomes the power supply source of the microcomputer 115, so that the microcomputer 115 can continue to operate with the power of the capacitor unit 113 even when the voltage of the battery 101 drops.

  However, even if the voltage drop of the battery 101 occurs, if the voltage Vb of the battery 101 is higher than the reference voltage and the voltage Vc of the capacitor unit 113 is higher than the voltage Vb of the battery 101, the power from the capacitor unit 113 instead of the battery 101 Thus, the microcomputer 115 operates. As a result, although the microcomputer 115 can be operated by the battery 101, the electric charge stored in the capacitor unit 113 is taken out unnecessarily, and wasteful power consumption is performed.

  Details of this operation will be described in detail with reference to FIG. In FIG. 5, the horizontal axis indicates time, and the vertical axis indicates voltage.

  It is assumed that the vehicle is in normal use until time t0 is reached. At this time, since the engine is operating, the alternator (not shown) is also activated, and the voltage Vb of the battery 101 is higher than the voltage of the battery 101 when the alternator is not activated. And is supplied to the power storage device 105. The voltage Vb in this state is larger than the voltage Vc of the capacitor unit 113. Therefore, the power of the battery 101 is supplied to the microcomputer 115 during the engine operation.

  Next, it is assumed that idling stop is started at time t0. As a result, when the engine stops, the alternator also stops, so that the voltage Vb of the battery 101 gradually decreases to the voltage of the battery 101 depending on the state of the peripheral load (not shown).

  Therefore, when the time t1 is reached, the voltage Vb of the battery 101 falls below the voltage Vc of the capacitor unit 113. As a result, as described above, the higher voltage of the battery 101 or the capacitor unit 113 becomes the power supply source of the microcomputer 115, so that the power of the capacitor unit 113 is supplied to the microcomputer 115 after the time t1. Along with this, the voltage Vc of the capacitor unit 113 gradually decreases.

  Thereafter, at time t2, when the idling stop is completed and the engine is started, the voltage Vb of the battery 101 starts to drop rapidly. During this time, since the vertical relationship of the voltages Vb and Vc does not change, the power to the capacitor unit 113 is continuously supplied to the microcomputer 115.

  When the voltage Vb of the battery 101 further drops and becomes equal to or lower than the reference voltage at time t3, the microcomputer 115 turns on the FET switch 117. As a result, power is also supplied to the electronic control unit 107.

  Next, when the engine start is completed, the alternator is also started to increase the voltage Vb of the battery 101. When the voltage becomes equal to or higher than the reference voltage at time t4, the microcomputer 115 turns off the FET switch 117. As a result, the power supply source to the electronic control unit 107 is switched to the battery 101. However, since the voltage Vc of the capacitor unit 113 is higher than the voltage Vb of the battery 101 at this time, power supply to the microcomputer 115 is performed from the capacitor unit 113 by the diode 121.

  When the voltage Vb of the battery 101 further rises and exceeds the voltage Vc of the capacitor unit 113 at time t5, the power supply source to the microcomputer 115 is switched to the battery 101.

  In such an operation, the voltage Vb of the battery 101 is larger than the reference voltage at times t1 to t3 and t4 to t5, and power is supplied from the capacitor unit 113 even though the microcomputer 115 can be operated by the battery 101. There is a problem that unnecessary charges (the area indicated by vertical stripes in FIG. 5) are consumed.

  An object of this invention is to provide the vehicle power supply device which reduces unnecessary power consumption.

  To achieve the above object, the present invention provides a main power source, an ignition switch connected to the main power source, a power storage device connected to the ignition switch and storing power of the main power source, and connected to the power storage device. The power storage device includes a charging circuit connected to the main power supply, a power storage unit connected to the charging circuit, a changeover switch having one end connected to the power storage unit, and the other switch. A first diode having an anode connected to the end; a voltage detection circuit connected to the main power supply for detecting a voltage (Vb) of the main power supply; an anode at the voltage detection circuit; a cathode at the load; A second diode connected to the cathode of the first diode, a control unit to which the charging circuit, the changeover switch, and the voltage detection circuit are connected; and a power supply terminal of the control unit A third diode having an anode connected to a connection point of the changeover switch and the first diode, a fourth diode having a cathode connected to a power supply terminal of the control unit, and an anode connected to the ignition switch, and the control unit The capacitor is connected to the power supply terminal.

  According to the vehicle power supply device of the present invention, since electric power is supplied from the power storage unit to the control unit only when the changeover switch is on, it is possible to reduce the unnecessary power consumption from the power storage unit.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment)
FIG. 1 is a block circuit diagram of a vehicle power supply device according to an embodiment of the present invention.

  FIG. 2 is a time-dependent change diagram of the main power supply voltage and the power storage unit voltage of the vehicle power supply device according to the embodiment of the present invention. In FIG. 1, a thick line indicates a power path, and a thin line indicates a signal path. In the present embodiment, an example in which the vehicle power supply device is used for an idling stop vehicle will be described.

  In FIG. 1, an IG switch 3 is connected to a main power source 1 made of a battery. The IG switch 3 has an accessory state, an on state, and a start state as in the prior art, and is connected as in the conventional FIG. Thereby, the starter 4 is driven by the driver setting the IG switch 3 to the start state, and the engine can be started. The main power source 1 and the IG switch 3 are connected to a power storage device 5 that stores the power of the main power source 1. A load 7 made of, for example, audio or navigation is connected to the output of the power storage device 5 via a second diode described later.

  Next, a detailed configuration of the power storage device 5 will be described.

  The main power source 1 is connected to the load 7 via the voltage detection circuit 9 that detects the voltage Vb of the main power source 1 and also connected to the power storage unit 13 via the charging circuit 11. The charging circuit 11 has a function of detecting and outputting the voltage Vc of the power storage unit 13. The power storage unit 13 is composed of an electric double layer capacitor, and is configured by connecting a plurality thereof.

  One end of a changeover switch 15 is connected to the power storage unit 13. The changeover switch 15 switches whether to supply the power of the power storage unit 13 to the load 7. A load 7 is connected to the other end of the changeover switch 15 via a first diode described later.

  A controller 17 composed of a microcomputer is connected to the voltage detection circuit 9, the charging circuit 11, and the changeover switch 15. Further, the control unit 17 has a function of exchanging data with a vehicle side control circuit (not shown).

  The power storage terminal 13 of the control unit 17 is connected to the power storage unit 13 via the changeover switch 15 and the third diode 19, and the output of the IG switch 3 is connected to the power supply source via the fourth diode 21. Yes. As a result, power is supplied from the main power supply 1 to the control unit 17. Note that the anode of the third diode 19 is connected to the changeover switch 15 and the cathode is connected to the power supply terminal 18 so that the power of the main power supply 1 and the power of the power storage unit 13 do not flow backward, and the anode of the fourth diode 21 is connected to the IG. The cathode is connected to the output of the switch 3 and the power supply terminal 18 respectively.

  Here, when the control unit 17 controls the changeover switch 15 to switch the power supply source from the main power supply 1 to the power storage unit 13, the power supply to the control unit 17 is momentarily interrupted depending on the response speed of the changeover switch 15. there is a possibility. In order to avoid the stop of the control unit 17 due to this, the capacitor 23 is connected to the power supply terminal 18.

  Further, when the voltage of the load 7 is higher than that of the power storage device 5, current may flow backward from the load 7 to the power storage device 5. In order to prevent this, a first diode 25 and a second diode 27 are provided between the changeover switch 15 and the load 7 and between the voltage detection circuit 9 and the load 7, respectively, with the load 7 side connected to the cathode. .

  The operation of the vehicle power supply device configured as described above will be described below.

  First, when the driver turns on the IG switch 3, the power of the main power supply 1 is supplied to the control unit 17 via the IG switch 3 and the fourth diode 21. As a result, the control unit 17 starts operating. Thereafter, the control unit 17 transmits a control signal cont for starting charging to the charging circuit 11. In response to this, the charging circuit 11 supplies the power of the main power source 1 to the power storage unit 13 and performs a charging operation until a certain voltage is reached.

  Next, the operation when power is supplied from the power storage unit 13 to the load 7 via the changeover switch 15 when the voltage of the main power supply 1 drops will be described with reference to FIG. In FIG. 2, the horizontal axis represents time, and the vertical axis represents voltage.

  Since the vehicle is in a normal state until time t0, the engine is operating. Accordingly, since the voltage Vb of the main power supply 1 is larger than the voltage Vc of the power storage unit 13, the power of the main power supply 1 is supplied to the control unit 17. These voltages are monitored by being taken into the control unit 17 by the voltage detection circuit 9 and the charging circuit 11 as appropriate.

  Next, when the idling stop is started at time t0, the alternator (not shown) is also stopped, so that the voltage Vb decreases with time. At this time, since the power storage unit 13 is not supplying power, the voltage Vc maintains the full charge voltage.

  Next, it is assumed that voltage Vb of main power supply 1 falls below voltage Vc of power storage unit 13 at time t1. At this time, the voltage Vb of the main power supply 1 is sufficiently larger than the reference voltage, so that the power of the main power supply 1 can be continuously supplied to the load 7. Therefore, the changeover switch 15 remains off. Thereby, since the electric power to the control part 17 is also supplied from the main power supply 1 via the 4th diode 21, the electric power of the electrical storage part 13 is not consumed.

  Thereafter, at time t2, when the starter 4 is started to start the engine after completion of the idling stop, the voltage Vb of the main power supply 1 starts to drop.

  Further, when the voltage Vb of the main power supply 1 drops and falls below the reference voltage at time t3, the control unit 17 transmits an on / off signal VOF1 for turning on the changeover switch 15. In response to this, the changeover switch 15 is turned on, and power is supplied from the power storage unit 13 to the load 7. As a result, the drive voltage Vcc is also supplied to the control unit 17 via the third diode 19. At this time, even if a power interruption to the control unit 17 described above occurs, the power is supplied from the capacitor 23, so the control unit 17 does not stop. Thereby, since electric power is supplied from the power storage unit 13 to the control unit 17 for the first time at time t3, unnecessary power consumption as in the prior art can be reduced at times t1 to t3.

  Next, when the voltage Vb of the main power source 1 rises due to completion of engine start or the like and becomes equal to or higher than the reference voltage at time t4, the control unit 17 transmits an on / off signal VOF1 so as to turn off the changeover switch 15. As a result, the power supply source to the load 7 is switched to the main power source 1. As a result, the power supply source to the control unit 17 is also switched to the main power source 1.

  Further, at time t5 when the voltage rises, the voltage Vb of the main power supply 1 becomes larger than the voltage Vc of the power storage unit 13, so charging of the power storage unit 13 is started. At this time, the changeover switch 15 remains off, Subsequently, power is supplied from the main power supply 1 to the control unit 17. As a result, unnecessary power consumption as in the prior art can also be reduced at times t4 to t5.

  From these operations, the power storage unit 13 only consumes the charge corresponding to the area indicated by the diagonal lines in FIG. 2 at time t3 to t4, and the charge corresponding to the area indicated by the vertical stripes in FIG. Recognize.

  With the above configuration and operation, power can be supplied from the power storage unit 13 to the control unit 17 only during the period when the changeover switch 15 is on, so that a vehicle power supply device that reduces unnecessary power consumption can be realized. .

  In addition, although this Embodiment demonstrated using the idling stop vehicle, it can be used also for vehicle systems, such as an electric power steering and an electric brake.

  Moreover, although the structure which connected several electric double layer capacitors as the electrical storage part 13 was shown, you may use other large capacity capacitors, such as an electrochemical capacitor.

  Since the vehicle power supply device according to the present invention reduces unnecessary power consumption from the power storage unit to the control unit, the vehicle power supply device as an auxiliary power supply that supplies power from the power storage unit when the main power supply voltage drops Useful.

1 is a block circuit diagram of a vehicle power supply device according to an embodiment of the present invention. The time-dependent change figure of the main power supply voltage and electrical storage part voltage of the power supply device for vehicles in embodiment of this invention Schematic block circuit diagram of a conventional vehicle power supply device Schematic block circuit diagram of another configuration of a conventional vehicle power supply device Changes over time in battery voltage and capacitor unit voltage of a conventional vehicle power supply device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main power supply 3 IG switch 4 Starter 5 Power storage device 7 Load 9 Voltage detection circuit 11 Charging circuit 13 Power storage unit 15 Changeover switch 17 Control unit 18 Power supply terminal 19 3rd diode 21 4th diode 23 Capacitor 25 1st diode 27 2nd diode

Claims (1)

A main power supply,
An ignition switch connected to the main power source;
A power storage device connected to the ignition switch and storing the power of the main power supply;
A load connected to the power storage device;
The power storage device includes a charging circuit connected to the main power source,
A power storage unit connected to the charging circuit;
A changeover switch having one end connected to the power storage unit;
A first diode having an anode connected to the other end of the changeover switch;
A voltage detection circuit connected to the main power supply for detecting a voltage (Vb) of the main power supply;
A second diode having an anode connected to the voltage detection circuit, a cathode connected to the load, and a cathode of the first diode;
A control unit to which the charging circuit, the changeover switch, and the voltage detection circuit are connected;
A third diode having a cathode connected to a power supply terminal of the control unit and an anode connected to a connection point between the changeover switch and the first diode;
A fourth diode having a cathode connected to the power supply terminal of the control unit and an anode connected to the ignition switch;
A vehicle power supply device comprising a capacitor connected to a power supply terminal of the control unit.

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