JP2012035756A - Power supply device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply device for a vehicle which can suppress a voltage drop during a driving operation of a large load by sufficiently utilizing the abilities of capacitors of the small number of capacitors.SOLUTION: The power supply device for a vehicle includes the capacitor 3 charged by a generator 1 mounted on the vehicle or a battery 4 to feed a power to a group of loads 2 mounted on the vehicle by the generator 1 mounted on the vehicle, the battery 4 or the capacitor 3. The power supply device for the vehicle includes voltage drop charging means Q, T, D1, D2, L and C3 for dropping an output voltage of the battery 4 to charge the capacitor 3 and connecting means 5 and D6 for connecting the battery 4 in series to the capacitor 3. When a detected voltage value of a battery voltage detector 8 is V1 or higher and a detected voltage value of a capacitor voltage detector 7 is V2(<V1) or lower, the voltage drop charging means Q to C3 charge the capacitor 3. When the detected voltage of the battery voltage detector 8 is V3 (V2<V3<V1) or lower, the connecting means 5 and D6 connect the battery 4 in series to the capacitor 3 to feed a power to the group of loads 2 mounted on the vehicle from the capacitor 3.

Description

  The present invention relates to a vehicle power supply device that includes a vehicle-mounted generator or a battery that is charged by a battery that is linked to an engine, and that supplies power to a vehicle-mounted load group by the vehicle-mounted generator, battery, or battery.

  In recent years, the number of electrical components mounted on a vehicle is increasing, and among them, the electric power steering apparatus is frequently operated and consumes a large current. Further, in consideration of the environment, the number of vehicles that perform idle stop for stopping idling when the vehicle is stopped is increasing. In such a vehicle, since the engine is started more frequently than in the conventional vehicle, the power source of the starter for starting the engine is important.

Since the starter consumes a large current when starting the engine and the motor consumes a large current when the electric power steering apparatus is operated, the voltage of the vehicle power supply device temporarily decreases. If the voltage drops temporarily, the lamps may temporarily darken, the power supply voltage of the electrical load such as the navigation device and ECU (Electronic Control Unit) may drop, and the operation may become unstable. It was.
For this reason, a backup battery or an electric double layer capacitor is connected in parallel to the battery (main power source) as an auxiliary power source, and a voltage drop at the time of driving a large load such as a starter and an electric power steering device is suppressed by discharging from the auxiliary power source. It is considered.

  Patent Document 1 includes a series circuit of a battery and a power storage unit, a DC / DC converter connected to charge and discharge the power storage unit, a switch connected to the series circuit and the battery, and a switch for switching to either one of them. A power supply device is disclosed that includes a motor connected to the output of a switch via a power converter, and a DC / DC converter, a switch, and a control circuit connected to the power converter. The control circuit connects the switch to the battery side when the motor is performing regenerative operation, and connects the switch to the series circuit side when performing power running operation. The power storage unit is charged by the DC / DC converter.

JP 2009-268343 A

  As described above and as shown in FIG. 3A, when the electric double layer capacitor C is connected in parallel to the battery B, the electric charge that can be output from the electric double layer capacitor C is limited to the voltage difference from the battery B. There is a problem. Further, when N cells of the electric double layer capacitor are connected in series according to the battery voltage, the capacity is reduced to 1 / N and the ESR (equivalent series resistance) is N times that of a single cell. Thus, there is a problem that the voltage drop becomes large.

  The present invention has been made in view of the above-described circumstances, and sufficiently uses the capacity of a capacitor with a small number of capacitors to suppress a voltage drop when driving a large load such as a starter and an electric power steering device. An object of the present invention is to provide a vehicular power supply device.

  In the vehicular power supply apparatus according to the present invention, when a large load is activated and the power supply voltage starts to decrease, a path in which one battery is connected in series to the battery B is connected from the battery B to the load group as shown in FIG. Add to the route to Needless to say, even if a plurality of capacitors connected in parallel are connected in series to the battery B, the same effect can be obtained.

  According to a first aspect of the present invention, there is provided a vehicular power supply device comprising: an on-vehicle generator linked to an engine or a battery that is charged by a battery; a battery voltage detector that detects an output voltage of the battery; and a battery that detects an output voltage of the battery. In a vehicle power supply device comprising a voltage detector and configured to supply power to an in-vehicle load group by the on-vehicle generator, battery, or capacitor, step-down charging that steps down the output voltage of the battery and charges the capacitor And a connection means for connecting the battery and the battery in series, the voltage value detected by the battery voltage detector is V1 or more, and the voltage value detected by the battery voltage detector is V2 (<V1) or less When the step-down charging means charges the battery, the voltage value detected by the battery voltage detector is V3 (V2 <V3 <V1) or less. To come, the connecting means, the battery and capacitor are connected in series, characterized in that the capacitor is arranged to supply power to the vehicle load group.

  In this vehicle power supply device, the battery is charged by an on-vehicle generator or battery that is linked to the engine, and the battery voltage detector detects the output voltage of the battery. The capacitor voltage detector detects the output voltage of the capacitor and supplies power to the vehicle load group by the vehicle generator, battery or capacitor. The step-down charging means steps down the output voltage of the battery and charges the battery, and the connection means connects the battery and the battery in series. When the voltage value detected by the battery voltage detector is V1 or higher and the voltage value detected by the battery voltage detector is V2 (<V1) or lower, the step-down charging means charges the battery. When the voltage value detected by the battery voltage detector is V3 (V2 <V3 <V1) or less, the connecting means connects the battery and the battery in series and feeds power from the battery to the in-vehicle load group.

  In the vehicular power supply device according to a second aspect of the present invention, the connection means includes a first diode connected in a forward direction between the positive electrode of the battery and the negative electrode of the battery, and the positive electrode of the battery and the vehicle load group. A second diode connected in a forward direction between the on-vehicle generator and each positive electrode of the battery, and between the positive electrode of the battery and the on-board load group side terminal of the switch. And a third diode connected in the forward direction.

  In this vehicle power supply device, the connection means includes a first diode connected in the forward direction between the positive electrode of the battery and the negative electrode of the battery, and a switch connected between the positive electrode of the battery and the in-vehicle load group. The second diode is forward-connected between the positive electrodes of the in-vehicle generator and the battery, and the third diode is forward-connected between the positive electrode of the battery and the in-vehicle load group side terminal of the switch.

  According to a third aspect of the present invention, the step-down charging means includes: a primary coil to which the output voltage of the battery is applied; an insulation transformer in which a secondary coil to which a rectifier circuit is connected is insulated; and the primary coil. And a chopper for turning on / off a given output voltage.

  In this vehicular power supply device, the step-down charging means includes an insulating transformer, a primary coil to which the output voltage of the battery is applied, and a secondary coil to which the rectifier circuit is connected is insulated, and a chopper is provided to the primary coil of the insulating transformer. The output voltage to be turned on / off.

  According to the vehicle power supply device of the present invention, the vehicle power supply device that can sufficiently suppress the voltage drop at the time of driving a large load, such as a starter and an electric power steering device, by sufficiently utilizing the capacity of the capacitor with a small number of capacitors. Can be realized.

It is a block diagram which shows schematic structure of embodiment of the vehicle power supply device which concerns on this invention. It is a block diagram for demonstrating operation | movement of the vehicle power supply device shown in FIG. It is a circuit diagram for demonstrating the principle of the power supply device for vehicles which concerns on this invention.

Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof.
FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a vehicle power supply device according to the present invention.
In this vehicle power supply device, an alternator (on-vehicle generator, AC generator) 1 generates power in conjunction with the engine 9. The generated electric power is converted into direct current in the alternator 1 and supplied to the battery (lead storage battery) 4 through a backflow prevention diode (second diode) D4. The power generated by the alternator 1 and the power output by the battery 4 are given to a load group (vehicle load group) 2 mounted on the vehicle via a backflow prevention diode (third diode) D5. .

The positive electrode of the battery 4 is connected to the negative electrode of the electric double layer capacitor (capacitor) 3 via a backflow prevention diode (first diode, connection means) D6. The positive electrode of the electric double layer capacitor 3 is A switch (connection means) 5 is connected to the cathode of the diode D5 and the load group 2.
One terminal of the primary coil of the insulation transformer T is connected to the positive electrode of the battery 4, and the drain of the N-channel MOS FET Q and the anode of the diode D3 are connected to the other terminal of the primary coil. The source of the FETQ is connected to the negative electrode of the battery 4.

A parallel circuit of a resistor R2 and a capacitor C2 is connected between one terminal of the primary coil of the insulating transformer T and the cathode of the diode D3.
A series circuit of a capacitor C4 and a resistor R1 is connected between the drain and source of the FET Q, and the gate of the FET Q is ON / OFF controlled by the control unit 6.
A capacitor C <b> 1 is connected between the positive electrode and the negative electrode of the battery 4.

The anode of the diode D2 is connected to one terminal of the secondary coil of the isolation transformer T, the anode of the diode D1 is connected to the other terminal of the secondary coil, and the cathodes of the diodes D1 and D2 are connected to the smoothing coil. It is commonly connected to one terminal of L. The other terminal of the smoothing coil L is connected to the positive electrode of the smoothing capacitor C3, and the negative electrode of the smoothing capacitor C3 is connected to the other terminal of the secondary coil.
The electric double layer capacitor 3 is connected in parallel to the smoothing capacitor C3.

A voltage value Vc between both electrodes of the electric double layer capacitor 3 is detected by a voltage detector (capacitor voltage detector) 7 built in the control unit 6, and an output voltage value Vb of the battery 4 is built in the control unit 6. It is detected by a voltage detector (battery voltage detector) 8.
Based on the voltage value Vc detected by the voltage detector 7 and the output voltage value Vb detected by the voltage detector 8, the control unit 6 controls on / off of the switch 5 and on / off control of the gate of the FETQ ( Chopping).

Below, operation | movement of the power supply device for vehicles which concerns on this invention of such a structure is demonstrated.
The electric power generated by the alternator 1 in conjunction with the engine 9 is charged to the battery 4 via the diode D4 and given to the load group 2 via the diode D5. When the power supplied from the alternator 1 to the load group 2 is insufficient and when the alternator 1 is stopped, the power from the battery 4 is supplied to the load group 2 via the diode D5.

When the output voltage value Vb of the battery 4 detected by the voltage detector 8 is higher than 10 V (V3), for example, the controller 6 turns off the switch 5 as shown in FIG.
In the control unit 6, the output voltage value Vb detected by the voltage detector 8 is, for example, 12V (V1) or more, and the voltage value Vc between both electrodes of the electric double layer capacitor 3 detected by the voltage detector 7 is 1.9V. (V2) When it is equal to or lower, the gate of the FETQ is on / off controlled (chopped).

When the control unit 6 chops the gate of the FETQ, the insulating transformer T steps down the output voltage (for example, about 13V) of the battery 4 to about 2V. The stepped down voltage is rectified and smoothed by the diodes D1 and D2, the smoothing coil L, and the smoothing capacitor C3, and charged in the electric double layer capacitor 3 as shown in FIG.
When the charging voltage of the electric double layer capacitor 3 is 2V, the voltage of the positive electrode of the electric double layer capacitor 3 is about 15V by adding the output voltage (for example, about 13V) of the battery 4 through the diode D6. .

  When the voltage value Vc detected by the voltage detector 7 becomes 2.1 V, for example, the control unit 6 stops chopping the gate of the FET Q, and the voltage value Vc is 1.9 V (due to natural discharge of the electric double layer capacitor 3). When V2) or less, chopping of the gate of FETQ is started. Further, the control unit 6 stops the chopping of the gate of the FETQ when the output voltage value Vb detected by the voltage detector 8 is lower than 12 V (V1), for example.

  When the engine is started or a large load such as an electric power steering device is operated and the output voltage value Vb of the battery 4 detected by the voltage detector 8 becomes, for example, 10 V (V3) or less, the control unit 6 As shown, switch 5 is turned on. At this time, since the output voltage value Vb detected by the voltage detector 8 is lower than 12V, the controller 6 stops chopping the gate of the FETQ.

When the control unit 6 turns on the switch 5, a current flows through the switch 5 from the positive electrode of the electric double layer capacitor 3 that is about 2 V higher than the output voltage value Vb of the battery 4, and accordingly, the current output from the battery 4 is The voltage drop due to the internal resistance of the battery 4 is suppressed, and the output voltage value Vb increases. As a result, the voltage applied to the load group 2 increases or does not decrease from about 10V.
If the switch 5 is on, most of the stored charge can be output from the electric double layer capacitor 3.

Here, assuming that the capacitance of the electric double layer capacitor 3 is C, the voltage change during discharge is ΔV, the current value during discharge is I, and the discharge time is t (seconds), the charge that can be supplied (discharge) = C · Δ V = I · t.
For example, it is assumed that a charge of 100 A × 5 s = 500 As is required when the electric power steering apparatus is operated. When the capacitance C of the electric double layer capacitor 3 is 72 F, about 72 × 2 = 144 (As) can be supplied from the electric double layer capacitor 3. Therefore, the load of the battery 4 can be reduced to 500−144 = 356As.

The controller 6 turns off the switch 5 when the output voltage value Vb detected by the voltage detector 8 becomes 10.5 V or more, or when the voltage value Vc detected by the voltage detector 7 becomes 0.1 V or less, for example. To do.
Thereafter, when the output voltage value Vb detected by the voltage detector 8 recovers to, for example, 12 V (V1) or more, the control unit 6 chops the gate of the FET Q and starts charging the electric double layer capacitor 3.

1 Alternator (on-vehicle generator)
2 Load group (vehicle load group)
3 Electric double layer capacitor (capacitor)
4 Battery 5 Switch (connecting means)
6 Control unit 7 Voltage detector (capacitor voltage detector)
8 Voltage detector (battery voltage detector)
9 Engine C1, C2, C4 Capacitor C3 Smoothing capacitor (step-down charging means)
D1-D3 diode D4 diode (second diode)
D5 diode (third diode)
D6 diode (first diode, connection means)
L Smoothing coil (Step-down charging means)
Q (N-channel MOS type) FET (step-down charging means)
R1, R2 Resistance T Insulation transformer (Step-down charging means)

Claims (3)

An on-vehicle generator linked to an engine or an accumulator charged by a battery, a battery voltage detector for detecting an output voltage of the battery, and an accumulator voltage detector for detecting an output voltage of the accumulator; In the vehicle power supply device configured to supply power to the in-vehicle load group by a battery or a capacitor,
Step-down charging means for stepping down the output voltage of the battery and charging the battery, and connection means for connecting the battery and the battery in series, and the voltage value detected by the battery voltage detector is V1 or more, When the voltage value detected by the battery voltage detector is V2 (<V1) or less, the step-down charging means charges the battery, and the voltage value detected by the battery voltage detector is V3 (V2 <V3 <V1). When the following is true, the connection means is configured to connect a battery and a capacitor in series and supply power from the capacitor to the in-vehicle load group.   The connection means includes a first diode connected in a forward direction between the positive electrode of the battery and the negative electrode of the battery, and a switch connected between the positive electrode of the battery and the vehicle load group, A second diode connected in a forward direction between each positive electrode of the on-vehicle generator and the battery, and a third diode connected in a forward direction between the positive electrode of the battery and the on-vehicle load group side terminal of the switch. The power supply device for vehicles according to claim 1 provided.   The step-down charging means includes a primary coil to which an output voltage of the battery is applied, an insulation transformer in which a secondary coil connected to a rectifier circuit is insulated, and a chopper for turning on / off the output voltage applied to the primary coil; The vehicle power supply device according to claim 2, comprising:

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