JP2001136659A - Current supply circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply a current to an automotive load with a small current capacity efficiently by a simple circuit configuration. SOLUTION: An air-zinc battery 24 is connected to a memory unit 23 via a power supply line 22. The cathode of a diode 21 is connected to the power supply line 22 of a connection point between the memory unit 23 and the battery 24. The anode of the diode 21 is connected to the current supply side of a DC-DC converter 4 via a power supply line 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current supply circuit for supplying a current to a vehicle-mounted load by lowering an output voltage of a vehicle-mounted power supply to a predetermined low voltage by a stabilized power supply circuit. And a current supply circuit for efficiently supplying a current to the current supply circuit.

[0002]

2. Description of the Related Art Conventionally, the rated voltage of an on-vehicle load such as electric components mounted on an automobile is often a 5 V system or a 12 V system. Has been adopted.
However, in recent years, in order to reduce the size of the on-vehicle load and rationalize the electric wiring, it has been studied to increase the voltage to be higher than the 12 V system. When the output voltage of the vehicle-mounted power supply is increased to, for example, a 36V system, the output voltage of the vehicle-mounted power supply is reduced by a stabilized power supply circuit such as a switching regulator or a DC-DC converter for a vehicle load of a 5V system or a 12V system. It will drop to voltage and supply current.

[0003]

It is necessary to constantly supply a dark current of about several mA to the ECU and the RAM of the navigation system for the refresh operation even in the on-vehicle load of 5V system. However, constantly driving a stabilized power supply circuit such as a switching regulator or a DC-DC converter to supply such a low-level dark current is very inefficient and leads to a large energy loss.

An object of the present invention is to solve the above-mentioned problem and to provide a current supply circuit capable of efficiently supplying a current to a vehicle-mounted load having a small current capacity with a simple circuit configuration. .

[0005]

According to the present invention, there is provided a current supply circuit for lowering an output voltage of a vehicle-mounted power supply to a predetermined low voltage by a stabilized power supply circuit and supplying a current to the vehicle-mounted load. A battery connected to a predetermined load having a small current capacity; and backflow prevention means for preventing current from flowing out from a connection point between the predetermined load and the battery to a current supply terminal of the stabilized power supply circuit. It is a thing.

According to this configuration, when the stabilized power supply circuit stops operating, current is supplied from the battery to a predetermined load having a small current capacity among the on-vehicle loads.
In this case, since the backflow prevention means is connected, no current flows from the battery toward the current supply end of the stabilized power supply circuit, and the current flows only from the battery to the predetermined load. Become. As a result, current can be efficiently supplied to a predetermined load having a small current capacity without using a stabilized power supply circuit.

The predetermined load having a small current capacity among the on-vehicle loads can be applied to a RAM such as an ECU or a navigation system.

Further, since the battery is made of a zinc-air battery, it becomes possible to supply current to the above-mentioned predetermined load from a zinc-air battery having a high energy density for a long period of time.

Further, the present invention provides a current supply circuit for lowering the output voltage of a vehicle-mounted power supply to a predetermined low voltage by a stabilized power supply circuit and supplying a current to a vehicle-mounted load;
Switch means interposed between the predetermined load having a small current capacity and the secondary battery among the on-vehicle loads,
The switching means is turned on when the stabilized power supply circuit stops operating.

According to this configuration, the output voltage of the vehicle-mounted power supply is dropped to a predetermined low voltage by the stabilized power supply circuit and the current is supplied to the vehicle-mounted load, but when the operation of the stabilized power supply circuit is stopped. Then, when the switch means interposed between the predetermined load having a small current capacity among the on-vehicle loads and the secondary battery is turned on, current is supplied from the secondary battery to the predetermined load. As a result, current can be efficiently supplied to a predetermined load having a small current capacity without using a stabilized power supply circuit.

The operation of the stabilized power supply circuit may be stopped when, for example, the vehicle-mounted engine is stopped.

[0012] Further, a remaining capacity detecting means for detecting the remaining capacity of the secondary battery, and when the detected remaining capacity is equal to or lower than a predetermined level, turning on the switch means and operating the stabilized power supply circuit. And charge control means for turning on.

According to this configuration, when the remaining capacity of the secondary battery is equal to or less than the predetermined level, the switching means is turned on to turn on the operation of the stabilized power supply circuit, thereby allowing the stabilized power supply circuit to operate at a lower level. Since the current is supplied to the secondary battery and the secondary battery is charged by this, the current supply to the predetermined load is further reduced for a long time while the operation time of the stabilized power supply circuit is minimized. Can be performed.

The on-vehicle power supply comprises an alternator and an on-vehicle battery. While the operation of the alternator is stopped, the operation of the stabilized power supply circuit is stopped, and the operation of the stabilized power supply circuit is stopped. Power supply control means for operating the stabilized power supply circuit for a predetermined time every predetermined cycle; and receiving the current from the stabilized power supply circuit for the predetermined time and turning off the secondary A remaining capacity detecting means for detecting a remaining capacity of the battery; and a charging control means for turning on the switch means and continuously operating the stabilized power supply circuit when the detected remaining capacity is equal to or lower than a predetermined level. May be provided.

According to this configuration, while the operation of the alternator is stopped, the operation of the stabilized power supply circuit is stopped. However, the stabilized power supply circuit is operated intermittently for a predetermined period of time at a predetermined period. During each operation, the current supply from the stabilized power supply circuit is received, and the remaining capacity of the secondary battery is accurately detected in a state where the switch is turned off. And
When the remaining capacity of the secondary battery is below a predetermined level, the switch means is turned on and the stabilized power supply circuit continues to operate,
Current is supplied from the stabilized power supply circuit to the secondary battery. Thus, since the secondary battery is charged, it is possible to supply the current to the predetermined load for a longer period of time while minimizing the operation time of the stabilized power supply circuit.

The interval at which the stabilized power supply circuit is operated intermittently, that is, the predetermined period is determined in advance by examining the degree of reduction in the capacity of the secondary battery due to current supply to the predetermined load. What is necessary is just to determine according to it. Further, the operation time when the stabilized power supply circuit is operated intermittently, that is, the above-mentioned predetermined time may be any time that can detect the remaining capacity of the secondary battery and determine its level.

[0017]

FIG. 1 is a circuit diagram showing a first embodiment of a current supply circuit according to the present invention, and FIG. 2 is a block diagram showing an example of the configuration of a DC-DC converter. This current supply circuit includes an alternator 1, a vehicle battery 2, and a D
C-DC converters 3 and 4 are provided.

The alternator 1 has a three-phase synchronous generator with a built-in full-wave rectifier circuit, and is driven by a vehicle engine (not shown). Make up for the shortfall,
When the amount of power generation exceeds the load on the vehicle, the vehicle-mounted battery 2 is charged. The in-vehicle battery 2 has a rated voltage V2 (for example, V2 = 36V in this embodiment) higher than a conventional general 12V. The alternator 1 and the vehicle battery 2 constitute a vehicle power supply.

The DC-DC converter 3 drops the rated voltage V2 of the on-vehicle battery 2 to DC12V.
The -DC converter (stabilized power supply circuit) 4 drops the rated voltage V2 of the vehicle-mounted battery 2 to DC5V.

As shown in FIG. 2, each of the DC-DC converters 3 and 4 has a high-frequency transformer 11 and a MOS-
It includes an FET 12, a drive circuit 13, a diode 14, a smoothing circuit 15, and a control circuit 16. MOS-F
ET12 is a converter input terminal and high-frequency transformer 11
And the primary winding. In addition, MOS-F
Instead of ET, a bipolar transistor such as IGBT may be used. The drive circuit 13 turns on and off the MOS-FET 12 according to a control signal from the control circuit 16.

When a pulse voltage generated by turning on / off the MOS-FET 12 is applied to the primary winding of the high-frequency transformer 11, the turn ratio of the secondary winding to the primary winding and the turning on / off of the MOS-FET 12 are performed. Is induced in the secondary winding of the high-frequency transformer 11. The AC induced voltage is rectified by the diode 14 to be a DC voltage, smoothed by the smoothing circuit 15, and output from the converter output terminal. It should be noted that the winding ratio is higher than that of the DC-DC converter 4 by DC-DC.
Converter 3 is set to a larger value.

When an operation command signal indicating that the alternator 1 is operating is input from the alternator 1, the control circuit 16 operates the drive circuit 13 to cause the MOS-FE to operate.
T12 is turned on and off, and the on / off duty ratio of the MOS-FET 12 is controlled in accordance with the output voltage from the smoothing circuit 15, whereby the DC12V (DC
-A stable output of the rated voltage of DC converter 3) or 5V DC (DC-DC converter 4).

Returning to FIG. 1, directly from the vehicle battery 2
A current is supplied to the 36V load 6 via the power supply line 5,
12 from the DC-DC converter 3 via the power line 7
The configuration is such that current is supplied to the V-system load 8. A power supply line 9 is connected to the current supply end 4 a of the DC-DC converter 4, and a current is supplied to the 5 V load 10 via the power supply line 9.

The 36 V system load 6 comprises, for example, a power steering, an electric brake or a discharge type headlamp, and the 12 V system load 8 comprises, for example, other lamps, a cooling fan, an audio system, or the like.
Is, for example, a door ECU, an air conditioner ECU, an engine EC
U etc.

A zinc zinc air battery 24 is connected to the memory unit 23 via a power supply line 22. The power supply line 22, which is a connection point between the memory unit 23 and the zinc air battery 24,
The cathode of the diode 21 is connected, and the anode of the diode 21 is connected to the DC-DC
It is connected to the current supply terminal 4a of the converter 4.

The memory unit 23 is composed of a RAM such as an ECU or a navigation system, and constitutes a predetermined load having a small current capacity. It is necessary to always supply a dark current to the memory unit 23 for the refresh operation regardless of the presence or absence of the engine operation. The zinc-air battery 24 is a primary battery with high energy density, about 2 m
When supplying dark current for memory backup of A, 1
Despite having a relatively small volume of 0cm x 10cm x 2cm, about 1
The current can be supplied over a long period of time.

In such a configuration, while the DC-DC converter 4 is stopped, a current is supplied from the zinc-air battery 24 to the memory unit 23 via the power supply line 22. Also,
If the output voltage of the zinc-air battery 24 is set to a voltage slightly lower than a value obtained by subtracting the forward voltage of the diode 21 from the output voltage of the DC-DC converter 4, DC-DC
During the operation of the converter 4, a current is supplied from the DC-DC converter 4 to the memory unit 23 instead of the zinc-air battery 24.

Here, the diode 21 is connected to the memory 23
Functioning as a backflow prevention means for preventing a current from flowing out from the power supply line 22 which is a connection point between the air-zinc battery 24 and the current supply terminal 4a of the DC-DC converter 4.

As described above, according to the first embodiment, DC
Since the positive electrode of the zinc-air battery 24 is connected to the cathode of the diode 21 having the anode connected to the power supply line 9 connected to the DC converter 4, and the memory unit 23 is connected to the positive electrode of the zinc-air battery 24. , Memory unit 23
, It is not necessary to operate the DC-DC converter 4 only for supplying dark current to the DC-DC converter 4. As a result, DC-DC
By operating the converter 4 and supplying a low-level current to a small-capacity load such as the memory unit 23, energy loss can be prevented beforehand.

FIG. 3 is a circuit diagram showing a second embodiment of the current supply circuit according to the present invention. The same members as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the second embodiment, as shown in FIG. 3, the DC-DC converter 4 is a low power consumption timer circuit 17 having a backup power supply such as an electric double layer capacitor.
have. Then, the control circuit 16 has a function of driving the drive circuit 13 (FIG. 2) for a predetermined time at a predetermined cycle while the alternator 1 is stopped by the operation of the timer circuit 17. The control circuit 16 and the timer circuit 17 constitute power supply control means.

As shown in FIG. 3, in the current supply circuit of the second embodiment, a charge control circuit 31 is connected to the power supply line 9 and the small capacity load 3 is connected to the charge control circuit 31.
The secondary and secondary batteries 33 are connected.

The charge control circuit 31 includes a diode 41, a relay (switch means) 42, and a control unit 43. One contact 51a of the contact portion 51 of the relay 42 is connected to the small-capacity load 32 via a power supply line 44. The power supply line 44 is connected to a cathode of a diode 41, and the anode of the diode 41 is connected to a power supply. Connected to line 9. The other contact 51 b of the contact portion 51 of the relay 42 is connected to the positive electrode of the secondary battery 33.
The exciting coil 52 of the relay 42 has one end connected to the control unit 43 and the other end grounded.

The contact part 51 of the relay 42 is a normally closed contact, and when an exciting current is supplied to the exciting coil 52, the contacts 51a, 51
When the exciting current is not supplied to the exciting coil 52, the contact between the contacts 51a and 51b is conducted.

The small-capacity load 32 is a RAM such as an ECU or a navigation system, or a radio or the like.
The required current capacity is relatively small and DC-DC
Regardless of whether the converter 4 is operating or not, the load is composed of a 5 V system load that always requires current supply.

As the secondary battery 33, a lithium ion battery, a lithium polymer battery, a nickel metal hydride battery, a nickel cadmium battery or the like is used, and a battery having a high volume energy density and a high mass energy density is preferable. The secondary battery 33
May be used as an electric double layer capacitor.

The control unit 43 of the charge control circuit 31 is connected to the power supply line 9 and the DC-D
It is supplied with power for operation from the C converter 4 and has the following functions. Excitation coil 5 of relay 42
A function as a switch control unit that switches on and off the relay 42 by controlling the supply of the exciting current to the relay 2. With the relay 42 turned off, the secondary battery 33
Function as remaining capacity detecting means for detecting the remaining battery capacity of the secondary battery 33 by detecting the battery voltage of the secondary battery 33. Secondary battery 33 detected
When the remaining capacity of the DC-DC converter 4 is lower than a predetermined level, the relay 42 is turned on and the control circuit 1 of the DC-DC converter 4 is turned on.
6. Function as charge control means for sending an operation command signal to 6.

Next, the operation of the current supply circuit according to the second embodiment will be described. First, the case where the alternator 1 is generating power while the engine is operating will be described.
Upon receiving an operation command signal from the alternator 1, the DC-D
The C converters 3 and 4 operate. Then, current is supplied from the DC-DC converter 3 to the 12 V system load 8 via the power supply line 7, and current is supplied from the DC-DC converter 4 to the 5 V system load 10 via the power supply line 9. . Further, a current is supplied from the DC-DC converter 4 to the small-capacity load 32 via the power supply line 9, the diode 41, and the power supply line 44.

At this time, the control unit 43 of the charge control circuit 31
Is operated by receiving a current supply from the DC-DC converter 4 via the power supply line 9, and supplies an exciting current to the exciting coil 52 of the relay 42 to turn off the contact portion 51 for a predetermined time, for example. The remaining capacity of the secondary battery 33 is detected every time. When the secondary battery 33 is not fully charged, the supply of the exciting current to the relay 42 is stopped and the contact 5
1 is turned on, and the secondary battery 33 is charged by the current supply from the DC-DC converter 4 via the power line 9, the diode 41, the power line 44, and the relay 42. When the secondary battery 33 is fully charged, an exciting current is supplied to the relay 42 to turn off the contact portion 51 and stop charging.

Next, a case where the engine is stopped and the alternator 1 is not generating power will be described.
The C converter 4 has stopped operating, and the control unit 43 has also stopped operating without receiving current supply. Therefore, the exciting current is not supplied to the relay 42, the contact portion 51 is in a conductive state, and the current is supplied from the secondary battery 33 to the small capacity load 32. At this time, the current from the secondary battery 33 does not flow out to the power supply line 9 due to the rectifying action of the diode 41.

Then, in response to the operation of the timer circuit 17 of the DC-DC converter 4, the drive circuit 13 (FIG. 2) is driven by the control circuit 16 for a predetermined period at predetermined intervals, and the DC-DC converter 4 operates.

During the operation of the DC-DC converter 4,
An exciting current is supplied to the relay 42 to turn off the contact portion 51, and the control portion 43 detects the remaining capacity of the secondary battery 33. At the time of this detection, if the remaining capacity is equal to or lower than the predetermined level, an operation command signal is sent from the control unit 43 to the DC-DC converter 4 so that the operation of the DC-DC converter 4 is continued. Is stopped and the contact portion 51 is turned on, whereby the D
The secondary battery 3 is supplied by the current supplied from the C-DC converter 4.
3 is charged. At this time, the current supply to the small capacity load 32 is performed by the DC-DC converter 4.
Then, when the secondary battery 33 is fully charged, the transmission of the operation command signal from the control unit 43 to the DC-DC converter 4 is stopped, and the DC-DC converter 4 stops operating.

Here, in the remaining capacity of the secondary battery 33,
Below the predetermined level for determining whether to start charging is 2
This is a level at which the secondary battery 33 is determined to be completely discharged.

For example, when a lithium ion battery is used as the secondary battery 33, if the single cell voltage becomes 2.5 V or less due to the electrode material, the battery characteristics may be deteriorated. If they are used in series, the voltage may be 5.6 V).

When a nickel-metal hydride battery is used as the secondary battery 33, the single cell voltage fluctuates in a range of 1.0 V to 1.3 V. V.

As described above, according to the second embodiment, since the secondary battery 33 is connected via the charge control circuit 31, the DC-DC converter 4 is not used while the alternator 1 is stopped. A current can be supplied from the secondary battery 33 to the small-capacity load 32, and without a large energy power loss as in the first embodiment.
Current can be suitably supplied to the small-capacity load 32.

In the second embodiment, the secondary battery 3
3 is determined based on the battery voltage level, but is not limited to this. The discharge time from the full charge of the secondary battery 33 (the time during which current is supplied from the secondary battery 33 to the small capacity load 32) ) Is integrated, and the amount of discharge is calculated using the known current level supplied to the small-capacity load 32 and the above-described integrated value. The determination may be made.

In the second embodiment, the DC-DC
The converter 4 has a timer circuit 17 provided with a backup power supply such as an electric double layer capacitor. The timer circuit 17 receives a current supply from the secondary battery 33 as included in the small capacity load 32. You may do so. According to this embodiment, there is no need to separately provide a backup power supply, and the configuration can be simplified.

Further, the timer circuit 17 may be configured to receive current supply directly from the vehicle-mounted battery 2 instead of the backup power supply. However, in this case, if the current consumption of the timer circuit 17 is large, it causes an increase in dark current, which is contrary to the intention of the present invention. As the timer circuit 17,
It is preferable to select one that has a sufficiently low current consumption and does not cause the vehicle-mounted battery 2 to be completely discharged (so-called dead battery) when used continuously for one month or more.

[0050]

As described above, according to the present invention,
A battery connected to a predetermined load having a small current capacity among in-vehicle loads, and a backflow prevention for preventing a current from flowing out from a connection point between the predetermined load and the battery to a current supply terminal of the stabilized power supply circuit. Means, when the stabilized power supply circuit stops operating, current does not flow out from the battery toward the current supply end of the stabilized power supply circuit, and the current capacity of the vehicle-mounted load is reduced. The current is supplied from the battery only to a small predetermined load, and the current can be efficiently supplied to the predetermined load having a small current capacity from the battery without using a stabilized power supply circuit.

Further, since the battery is a zinc-air battery, current can be supplied from the zinc-air battery having a high energy density to the predetermined load for a long period of time.

Further, according to the present invention, the secondary battery, the predetermined load having a small current capacity among the on-vehicle loads, and the second
Switch means interposed between the secondary battery and the secondary battery. The switch means is turned on when the stabilized power supply circuit stops operating. Current can be supplied to the predetermined load having a small current capacity among the in-vehicle loads, and the current can be efficiently supplied from the battery without using the stabilized power supply circuit.

Further, the remaining capacity detecting means for detecting the remaining capacity of the secondary battery, and, when the detected remaining capacity is equal to or lower than a predetermined level, turning on the switch means and operating the stabilized power supply circuit. When the remaining capacity of the secondary battery is equal to or lower than a predetermined level, the switch means is turned on and the operation of the stabilized power supply circuit is turned on. A current is supplied from the stabilized power supply circuit to the secondary battery, whereby the secondary battery is charged and the current supply to the predetermined load is performed while minimizing the operation time of the stabilized power supply circuit. It can be performed over a longer period.

While the operation of the alternator is stopped, the operation of the stabilized power supply circuit is stopped. Even when the operation of the stabilized power supply circuit is stopped, the stabilized power supply circuit is operated for a predetermined time every predetermined period. Power supply control means for causing the battery to receive current from the stabilized power supply circuit at predetermined time intervals, and remaining capacity detection means for detecting the remaining capacity of the secondary battery with the switch means turned off; When the remaining capacity is equal to or lower than a predetermined level, a charge control means for turning on the switch means and continuously operating the stabilized power supply circuit is provided. The remaining capacity of the secondary battery can be accurately detected. When the detected remaining capacity of the secondary battery is equal to or lower than a predetermined level, the switch means is turned on and the stabilized power supply is turned on. By but continue to operate,
A current is supplied from the stabilized power supply circuit to the secondary battery to charge the secondary battery, thereby minimizing the operation time of the stabilized power supply circuit and supplying current to the predetermined load. For a longer period of time.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a current supply circuit according to the present invention.

FIG. 2 is a block diagram illustrating an example of a configuration of a DC-DC converter.

FIG. 3 is a circuit diagram showing a second embodiment of the current supply circuit according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Alternator 2 On-board battery 3, 4 DC-DC converter 16 Control circuit 21 Diode 22 Power supply line 23 Memory part 24 Zinc battery 31 Charge control circuit 32 Small capacity load 33 Secondary battery 41 Diode 42 Relay 43 Control part

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Fumiaki Mizuno 1-7-10 Kikuzumi, Minami-ku, Nagoya-shi, Aichi F-term in Harness Research Institute, Inc. (reference) 5G003 AA04 AA07 BA02 CA11 CC01 CC02 DA06 DA12 DA17 FA08 GB03 GC05 5G065 AA00 AA01 DA01 DA07 EA02 FA02 GA09 HA02 HA04 JA01 JA04 KA02 KA05 MA09 MA10 NA06

Claims (5)

[Claims] 1. A current supply circuit for supplying an electric current to an on-vehicle load by lowering an output voltage of an on-vehicle power supply to a predetermined low voltage by a stabilized power supply circuit. A current supply, comprising: a connected battery; and a backflow preventing means for preventing a current from flowing out from a connection point between the predetermined load and the battery to a current supply end of the stabilized power supply circuit. circuit. 2. The current supply circuit according to claim 1, wherein
The current supply circuit, wherein the battery is a zinc-air battery. 3. A current supply circuit for lowering an output voltage of an on-vehicle power supply to a predetermined low voltage by a stabilized power supply circuit and supplying current to an on-vehicle load, comprising: a secondary battery; Switch means interposed between the small predetermined load and the secondary battery, wherein the switch means is turned on when the stabilized power supply circuit stops operating. Current supply circuit. 4. The current supply circuit according to claim 3, wherein said remaining capacity detecting means for detecting the remaining capacity of said secondary battery, and said switch means being turned on when said detected remaining capacity is below a predetermined level. And a charge control means for turning on the operation of the stabilized power supply circuit. 5. The current supply circuit according to claim 3, wherein
The on-vehicle power supply includes an alternator and an on-vehicle battery. While the operation of the alternator is stopped, the operation of the stabilized power supply circuit is stopped. Power supply control means for operating the stabilized power supply circuit for a predetermined time; and receiving current supply from the stabilized power supply circuit for the predetermined time and changing the remaining capacity of the secondary battery in a state where the switch means is turned off. And a charge control means for turning on the switch means and continuously operating the stabilized power supply circuit when the detected remaining capacity is equal to or lower than a predetermined level. Characteristic current supply circuit.