JP6102804B2 - Vehicle power supply - Google Patents

Description

  The present invention belongs to a technical field of a power supply device for a vehicle, particularly a power supply device for a vehicle having an idle stop system.

  Currently, as a system for improving the fuel efficiency of the engine, when the vehicle is stopped, the engine is automatically stopped when a predetermined stop condition such as brake ON and vehicle speed is zero, and a predetermined restart condition such as brake OFF is satisfied while the engine is stopped. Has been put into practical use.

  For example, as disclosed in Patent Document 1, a power supply device for a vehicle equipped with an idle stop system supplies power to an engine starter 502 such as a generator 501 or a starter driven by an engine as shown in FIG. Between the first battery 503 to be supplied, the second battery 504 that stores the electric power generated by the generator 501, and various electric devices (hereinafter referred to as “electric load”) 505 mounted on the vehicle and the second battery 504 And a DC / DC converter 506 that controls power supply to the electric load 505.

  Here, for example, a lead battery is used for the first battery 503, and a lithium ion battery or a capacitive capacitor (capacitor) is used for the second battery 504, for example. The electric load 505 includes, for example, a lamp, electric power steering, audio, power window, defogger, seat heater, dynamic stability control, and the like.

  On the other hand, the output current of a DC / DC converter is usually limited to a predetermined current value based on its heat dissipation characteristics in consideration of durability and the like.

  As for this, Patent Document 2 discloses that a DC / DC converter supplies power using two batteries in combination when an electric load is in a high load state and exceeds a maximum current supply capability of the DC / DC converter. Is disclosed.

JP 2011-208599 A JP 2007-64209 A

  However, in a vehicle power supply device equipped with an idle stop system, when the engine is restarted, the lead battery needs to supply output power exclusively to cranking by the engine starting means. Therefore, at the time of restart, the electric load must cover the operation of the electric load only by the electric power from the DC / DC converter. In that case, for example, when an electric load (for example, a lamp, a power window, a high-power audio system, etc.) that consumes a large amount of power is activated when the engine is restarted, such as when the foot is released while opening the power window, Within the current limit, there is a risk that the power supplied to the operating electric load will be insufficient. In particular, when the steering operation by the driver is a restart condition of the engine during idling stop, the power consumption by the power steering unit due to this operation is large, so that the power supplied to other electric loads tends to be insufficient.

  Accordingly, the present invention has been made to solve the above-described problems, and provides a vehicle power supply device capable of operating an electric load having a large power consumption only by power from the DC / DC converter when the engine is restarted. It is to provide.

  In order to solve the above problems, the present invention is configured as follows.

First, the invention according to claim 1 of the present application is
A power supply device for a vehicle including an engine idle stop control device that automatically stops an engine when a predetermined stop condition is satisfied and automatically restarts the engine when a predetermined restart condition is satisfied,
A generator driven by the engine;
A first power storage device that stores electric power generated by the generator and supplies the stored electric power to an engine starting means when the engine is automatically restarted;
A second power storage device that is connected to the generator via switch means, and stores the electric power generated by the generator when the switch means is closed;
A converter for stepping down power stored in the second power storage device and supplying power to an on-vehicle electric load;
The converter includes current limiting means for limiting the output current to a predetermined current upper limit value, and releases the restriction to the predetermined current upper limit value by the current limiting means when the engine restart condition is satisfied. Bei to give a current restriction release means that,
The current limiting means starts limiting the output current of the converter when the restart of the engine is completed .

The invention according to claim 2 is the invention according to claim 1,
The current limit release means releases the restriction to the predetermined current upper limit value by the current limit means, and limits the output current to a maximum supplyable current value higher than the predetermined current upper limit value. .

  According to the invention according to the above claims, the following effects can be obtained.

  First, according to the first aspect of the present invention, in the vehicle provided with the idle stop control device, the converter that supplies electric power to the on-vehicle electric load includes a current limiting unit that limits the output current to a predetermined current upper limit value. And a current limit releasing means for releasing the restriction by the current limiting means of the converter when the engine restart condition is satisfied, so that the converter has a predetermined current upper limit value only when the engine is restarted. Large current exceeding can be passed. At this time, if the electrical load transiently increases during engine restart, a large current flows through the converter. However, since the engine restart time is short (usually within 1 second), the converter There is no risk of damage. Therefore, according to the present invention, when the engine is restarted, an electric load having a large power consumption can be operated only by the power from the converter.

  According to the second aspect of the present invention, when the current limit releasing means releases the restriction to the current upper limit value by the current limiting means, a current larger than the current upper limit value flows when the engine is restarted. However, since the current is limited to the maximum current value that can be supplied, the converter can be protected from a large transient current and the reliability can be further improved.

It is a figure which shows the system configuration | structure of the vehicle power supply device which concerns on the 1st Embodiment of this invention. It is a flowchart which shows the control method of the power supply device for vehicles of FIG. It is a figure which shows the system configuration | structure of the vehicle power supply device which concerns on the 2nd Embodiment of this invention. It is a figure which shows the system configuration | structure of the vehicle power supply device which concerns on the 3rd Embodiment of this invention. It is a figure which shows the system configuration | structure of the conventional vehicle power supply device.

  Hereinafter, a vehicle power supply device according to a first embodiment of the present invention will be described with reference to FIG.

  FIG. 1 shows a system configuration of a power supply apparatus 100 for a vehicle 1 that automatically stops an engine when a predetermined stop condition is satisfied and automatically restarts the engine when a predetermined restart condition is satisfied.

  As shown in FIG. 1, a vehicular power supply apparatus 100 includes a regenerative alternator 1 capable of decelerating regenerative power generation performed when the vehicle decelerates and normal power generation driven by an engine (not shown), and a starter that starts the engine. 2 and a battery 3 that stores the electric power generated by the regenerative alternator 1 and supplies the stored electric power to the starter 2 when the engine is automatically restarted, and is connected to the regenerative alternator 1 via a normally open first relay 6 The main fuse box 7 is connected to the capacitor 4 that stores the power generated by the regenerative alternator 1 when the first relay 6 is closed, and the various electric loads 5 that are mounted on the vehicle by stepping down the power stored in the capacitor 4. And a DC / DC converter unit 10 that supplies electric power via the DC / DC converter unit 10.

  The regenerative alternator 1 is a variable voltage type (for example, 12 to 25 V) alternator that is belt-driven by an engine and efficiently regenerates kinetic energy during deceleration or the like. High voltage up to 25V is possible.

  The battery 3 is a general lead battery.

  The capacitor 4 is a large-capacity low-resistance electric double layer capacitor (EDLC) that can instantaneously store a large amount of regenerated electric energy and efficiently extract and use it. For example, the capacitor 4 can generate a voltage of up to 25V. The capacitor 4 is capable of rapid power storage (for example, several seconds when traveling at 50 to 60 km / h) as compared with a lithium ion battery or a general lead battery used in an electric vehicle or the like, and has an unlimited discharge depth. There is an advantage such as having a semi-permanent lifetime.

  The electric load 5 includes, for example, a lamp, electric power steering, audio, power window, defogger, seat heater, dynamic stability control, navigation system, and the like.

  The first relay 6 cuts off the current stored in the capacitor 4 from the vehicle power supply device 100 during a vehicle collision accident or maintenance in order to prevent electric shock.

  The DC / DC converter unit 10 includes a DC / DC converter main body 11 that supplies the electric power stored in the capacitor 4 to the electric load 5, and a capacitor 16 that stores the electric power stored in the capacitor 4. The DC / DC converter main body 11 includes a current limiter 12 that limits the output current, and the current limiter 12 limits the output current from a maximum current value that can be supplied (for example, 130 A) to a predetermined current upper limit value (for example, 95 A). can do. Moreover, the DC / DC converter main body 11 can step down and output a maximum DC25V to DC14V, for example.

  Further, the DC / DC converter unit 10 is provided with a normally open type second relay 13 and a third relay 14 that can cut off the power supplied from the regenerative alternator 1 to the battery 3 in series.

  Further, the DC / DC converter unit 10 is provided with a first bypass circuit unit 17 for supplying the electric power stored in the battery 3 to the electric load 5 without the DC / DC converter body 11 being interposed. The first bypass circuit unit 17 has one end connected to a circuit unit between the second relay 13 and the third relay 14 and the other end connected to the output side of the DC / DC converter main body 11. .

  Further, the DC / DC converter unit 10 is configured to bypass the third relay 14 so that the electric power 5 can be supplied from the battery 3 when the third relay 14 remains open due to a failure. Two diodes 15 are provided in parallel.

  The above-described DC / DC converter unit 10 is controlled by the DC / DC converter ECU 20. The DC / DC converter ECU 20 performs signal processing based on various signals such as an output signal from the engine ECU 30 that performs engine idle stop control and the like, and controls the DC / DC converter unit 10 based on the processing result. Is output. In particular, when the DC / DC converter ECU 20 receives an output signal indicating that the engine restart condition is satisfied from the engine ECU 30, the DC / DC converter ECU 20 limits the current limiter 12 of the DC / DC converter body 11 to a predetermined current upper limit value. It is configured to release.

  The “converter” in claim 1 corresponds to a combination of the DC / DC converter unit 10 and the DC / DC converter ECU 20 of the present embodiment.

  Next, a specific power control method of the vehicle power supply device 100 will be described with reference to FIG.

  First, it is determined whether or not the engine is started based on an output signal from the engine ECU 30 (step S1).

  When it is determined that the engine is started, it is determined whether or not a predetermined idle stop condition such as brake ON, vehicle speed zero, or the like is satisfied (step S2). On the other hand, if it is determined that the engine has not been started, the process returns to step S1.

  If it is determined in step S2 that the idle stop condition is satisfied, the engine ECU 30 automatically stops the engine (step S3). On the other hand, if it is determined that the idle stop condition is not satisfied, the process returns to step S2.

  Next, it is determined whether or not a predetermined engine restart condition such as brake OFF is satisfied while the engine is stopped (step S4).

  If it is determined in step S4 that the restart condition is satisfied, the DC / DC converter ECU 20 releases the current limitation by the current limiter 12 of the DC / DC converter main body 11 (step S5). On the other hand, when it is determined that the restart condition is not satisfied, the process returns to step S3.

  Next, the contact of the second relay 13 is opened (off state) (step S6).

  Next, the engine ECU 30 restarts the engine (step S7).

  Next, it is determined whether or not the engine has been restarted (step S8).

  If it is determined in step S8 that the engine has restarted, the output current of the DC / DC converter main body 11 is limited by the current limiter 12 (step S9). On the other hand, if it determines with the engine not having restarted in step S8, it will return to step S7.

  Finally, the contact of the second relay 13 is closed (ON state) (step S10).

  As described above, according to the present embodiment, the DC / DC converter main body 11 can flow a large current (for example, 130 A) exceeding a predetermined current upper limit value (for example, 95 A) only when the engine is restarted. At this time, if the electrical load 5 increases transiently during the automatic restart of the engine, a large current flows through the DC / DC converter body 11, but the engine restart time is short (usually within 1 second). There is no possibility that the DC / DC converter main body 11 is damaged by Joule heat. Therefore, the electric load 5 having a large power consumption can be operated only by the power from the DC / DC converter main body 11 when the engine is restarted.

  Further, according to the present embodiment, when the DC / DC converter ECU 20 releases the restriction on the current upper limit value (for example, 95 A) by the current limiter 12, a current larger than the current upper limit value flows when the engine is restarted. However, since the current is limited to the maximum supplyable current value (for example, 130 A), the DC / DC converter main body 11 can be protected from a transient large current and the reliability can be further improved.

(Second Embodiment)
Next, a vehicle power supply device 200 according to a second embodiment of the present invention will be described with reference to FIG. Note that a detailed description of a configuration having the same function as that of the first embodiment described above is omitted.

  In the above-described first embodiment, when the contact of the relay 6 is changed from the open state to the closed state (on state), if the potential difference between both ends of the relay 6 is large (for example, DC5V, capacitor on the DC / DC converter unit 10 side) 4), the contact of the relay 6 may be melted due to an instantaneously large current (several hundreds A) flowing through the relay 6.

  Therefore, in the second embodiment, the second bypass circuit unit 201 for reducing the potential at both ends of the relay 6 is provided immediately before the contact of the relay 6 is changed from the open state to the closed state. The second bypass circuit unit 201 is provided so as to bypass the relay 6, and the FET relay 202 and the diode 203 are provided in series in the second bypass circuit unit 201.

  Here, in general, the FET relay is a non-contact relay configured by a semiconductor element without a mechanical movable part like a normal contact relay. In the FET relay, the semiconductor element generates heat when energized, but it is possible to energize a larger current than a normal contact relay for a short time. In addition, since there is no contact in the FET relay, there is no risk of the relay contact being melted.

  The vehicle power supply device 200 described above first closes the FET relay 202 of the second bypass circuit unit 201 before switching the relay 6 from the open state to the closed state, Then, the capacitor 16 in the DC / DC converter unit 10 is charged (see the arrow in FIG. 3), and the potential difference between both ends of the relay 6 is reduced within a predetermined range (for example, the voltage of the capacitor 16 is about DC16V, That is, the relay 6 is controlled to be in a closed state after the contact voltage of the relay 6 on the DC / DC converter unit 10 side is set to around DC 16 V).

  Therefore, according to this embodiment, the transient current flowing through the relay 6 can be suppressed, and the contact of the relay 6 can be protected.

(Third embodiment)
Next, a vehicle power supply device 300 according to a third embodiment of the present invention will be described with reference to FIG. Note that a detailed description of a configuration having the same function as that of the first embodiment described above is omitted.

  In the first embodiment described above, when the relay 14 is in the closed state and the contact of the relay 13 is changed from the open state to the closed state (on state), if the potential difference between both ends of the relay 13 is large (for example, on the battery 3 side). When DC14V and DC5V on the capacitor 4 side), an excessively large current (several hundreds A) instantaneously flows through the relay 13, and the contact of the relay 13 may be melted.

  Therefore, in the third embodiment, a third bypass circuit unit 311 for reducing the potential at both ends of the relay 13 is provided immediately before the contact of the relay 13 is changed from the open state to the closed state. The third bypass circuit unit 311 is provided so as to bypass the relay 13, and the FET relay 312 and the diode 313 are provided in series in the third bypass circuit unit 311.

  The above-described power supply apparatus 300 first closes the FET relay 312 of the third bypass circuit unit 311 before switching the relay 13 from the open state to the closed state, and passes the capacitor through the third bypass circuit unit 311. 16 is charged (see the arrow in FIG. 4), and the potential difference between both ends of the relay 13 is reduced within a predetermined range (for example, the voltage of the capacitor 16 is in the vicinity of DC14V, that is, the contact on the capacitor 16 side of the relay 13). The relay 13 is controlled to be in a closed state after the voltage is set to around DC14V.

  Therefore, according to the present embodiment, similarly to the second embodiment described above, the transient current flowing through the relay 13 can be suppressed, and the contact of the relay 13 can be protected.

  It should be noted that the present invention is not limited to the illustrated embodiment, and it goes without saying that various improvements and design changes can be made without departing from the gist of the present invention.

  For example, the first to third embodiments described above can be implemented by appropriately combining a part or all of them.

  As described above, according to the present invention, in the vehicle power supply device, an electric load having a large power consumption can be operated only with power from the DC / DC converter when the engine is restarted. There is a possibility of being suitably used in the field of manufacturing technology.

First-generation alternator (generator)
2 Starter (engine starting means)
3 battery (first power storage device)
4 Capacitor (second power storage device)
5 Electric load 6 Second relay (switch means)
10 DC / DC converter unit 12 Current limiter (current limiting means)
20 DC / DC converter ECU (current limit release means)
30 Engine ECU (idle stop control device)
100, 200, 300 Power supply device for vehicle

Claims (2)

A power supply device for a vehicle including an engine idle stop control device that automatically stops an engine when a predetermined stop condition is satisfied and automatically restarts the engine when a predetermined restart condition is satisfied,
A generator driven by the engine;
A first power storage device that stores electric power generated by the generator and supplies the stored electric power to an engine starting means when the engine is automatically restarted;
A second power storage device that is connected to the generator via switch means, and stores the electric power generated by the generator when the switch means is closed;
A converter for stepping down power stored in the second power storage device and supplying power to an on-vehicle electric load;
The converter includes current limiting means for limiting the output current to a predetermined current upper limit value, and releases the restriction to the predetermined current upper limit value by the current limiting means when the engine restart condition is satisfied. Bei to give a current restriction release means that,
The power supply device for a vehicle according to claim 1, wherein the current limiting means starts limiting the output current of the converter when the restart of the engine is completed . The current limit release means releases the restriction to the predetermined current upper limit value by the current limit means, and limits the output current to a maximum supplyable current value higher than the predetermined current upper limit value. The power supply device for vehicles according to claim 1.

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