JPH09247856A - Power supply device for vehicles using electric double layer capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply including an electric double layer capacitor with sufficient current fed to a large load for a vehicle, along with a suppression of variation in voltage and a good reduction of influence of noises. SOLUTION: A power supply using an electric double layer capacitor has an electric double layer capacitor 10 charged by a generator 12 on a vehicle, and a lead storage battery 20. These capacitor 10 and the battery 20 are used to feed power to different kinds of loads. That is, the battery 20 feeds power to loads, such as a smaller load than those fed by the electric double layer capacitor 10, a load as a noise source, and a load with a possibility of generating a defect in operation when a variation is caused in voltage. On the other hand, the electric double layer capacitor 10 feeds a load 26 that is larger than the battery, and doesn't function as a noise source without a possibility of generating a defect in operation even when a variation is caused.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle power supply device using an electric double layer capacitor, and more particularly to a vehicle having both an electric double layer capacitor and a lead storage battery for supplying current from both of them to an electric load mounted on the vehicle. It relates to a power supply device.

[0002]

2. Description of the Related Art As shown in FIG. 5, an electric double layer capacitor 10 has been used as a substitute device for a battery in a power supply system in various electronic circuits. As shown in the figure, an electric double layer capacitor 10 is connected to be charged by a voltage source 12, and the output side of the electric double layer capacitor 10 is connected to various electric loads.

Such an electric double layer capacitor has excellent characteristics that it has a large capacitance and that it does not easily deteriorate even if it is repeatedly charged and discharged and has a long life. Therefore, it has been proposed to utilize such an electric double layer capacitor in a vehicle power supply device, and various circuit configurations have been adopted. However, the electric characteristics of the electric double layer capacitor include the following frequency characteristics and self-discharge characteristics, and it is necessary to utilize them after considering both characteristics.

First, the frequency characteristic will be described. The electric double layer capacitor is a storage battery that does not undergo a chemical change due to positive and negative charges accumulated on the electrode surfaces 14 and 16 as shown in the configuration explanatory view of FIG. It is stored and the ions are insulated by the separator 18. Further, since the movement of the charges is approximately limited to the vicinity of the surface, there is a frequency characteristic that it becomes a resistance against the movement of the charges having a high frequency. FIG. 7 is a graph showing this characteristic, and it can be understood that the characteristic functions as a resistance when the frequency is higher than a predetermined value.

On the other hand, the self-discharge characteristics are due to the porosity of the electrodes of the electric double layer capacitor. That is, due to the non-uniformity of the charge distribution on the electrode surface, a slight internal loss occurs even in the circuit cutoff state. Therefore, if left uncharged for a long period of time, the terminal voltage will drop due to self-discharge as shown in FIG. As shown in the figure, it is understood that the voltage drop degree of the electric double layer capacitor shown by the solid line 200 is larger than the voltage drop line 100 of the lead storage battery shown by the broken line.

Further, when a voltage higher than the rated voltage is applied to such an electric double layer capacitor, electrolysis occurs inside the electric double layer capacitor, which causes a decrease in life. Therefore, it is necessary to construct a vehicle power supply device using an electric double layer capacitor in consideration of the above various characteristics.

[0007]

When the power supply device using the electric double layer capacitor 10 shown in FIG. 5 is used for a vehicle, the voltage source 12 corresponds to an alternator that operates based on engine driving. Then, the AC voltage is converted into a DC voltage and output by the rectifier configured inside the alternator. However, as a characteristic of the generator, this DC voltage inherently contains a large amount of ripple voltage and high-frequency components forming the ripple. Further, among various electric loads mounted on a vehicle that receives a current supply, many are sources of noise.

Generally, each electronic device has a built-in filter for noise removal, but it is not perfect, and the generated noise may return to the power supply unit side. In the case of a conventional power supply device composed of a lead storage battery, such a lead storage battery has played an absolute role of a filter, and it is not necessary to take measures against it. However, in the power supply device using the electric double layer capacitor, since the electric double layer capacitor has the frequency characteristics as described above, the function of the filter cannot be achieved for a wide range of frequencies.

That is, as shown in FIG. 7, unless the frequency is higher than a predetermined value, it does not function as a resistor. Therefore, the feedback noise as described above adversely affects the electronic control unit (ECU) for engine control. And also cause radio noise.

Further, if the peak voltage of the ripple voltage exceeds the reference activation voltage during charging, the life of the electric double layer capacitor will be adversely affected. Therefore, it is necessary to set the rated voltage with some margin, which is a disadvantageous condition in the electric double layer capacitor. Further, a large number of electronic devices that are likely to cause malfunctions due to fluctuations in the applied voltage are also connected.

Since the electric double layer capacitor cannot store a large amount of energy like a lead acid battery,
When self-discharge progresses or a large-capacity electrical load is applied, the terminal voltage is likely to drop. Therefore, it may cause a malfunction in an electronic device, a computer, or the like which is weak against voltage fluctuation.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems caused by the characteristics of an electric double layer capacitor used in a vehicle-mounted power supply device. It is an object of the present invention to provide a vehicle power supply device using an electric double layer capacitor that suppresses the above-mentioned problem and excellently eliminates the influence of noise.

[0013]

To achieve the above object, according to a vehicle power supply device using an electric double layer capacitor according to claim 1, an electric double layer capacitor and a lead storage battery provided as a power supply device are provided. , Are connected so as to supply currents to different electric loads.

That is, the self-discharge is relatively small, the returned noise can be surely eliminated, and a relatively small load from the lead-acid battery side, which is highly demanded for downsizing, a load that is a source of noise, Current is supplied to a load that is easily affected by noise or a load that is liable to malfunction due to fluctuations in the supply voltage.

On the other hand, from the electric double layer capacitor side, which has a large self-discharge and lacks a filter function, a load that is relatively large and is not affected by noise, a load that does not become a source of noise, and a fluctuation in supply voltage. It is configured to supply current to a load that is not easily affected.

As a result, it is possible to suppress the adverse effect on the in-vehicle equipment due to the terminal voltage drop of the electric double layer capacitor, eliminate the noise generated by the lead storage battery, and effectively avoid the malfunction of various equipment due to the noise.

As a circuit configuration for this purpose, as described in claim 2, the lead storage battery and the vehicle-mounted generator are directly connected, and the connection line and the electric double layer capacitor are connected through a filter in series. There is.

As a result, the ripple current at the time of charging from the on-vehicle generator can be eliminated by this filter, so that the charging voltage to the electric double layer capacitor is stabilized and the life is prevented from being shortened. As this filter, for example, a resistor is installed. As a result, a more stable DC voltage can be biased to the electric double layer capacitor, and charging can be performed with a bias voltage up to the rated voltage of the electric double layer capacitor.

According to the vehicle power supply device using the electric double layer capacitor according to the third aspect, only the electric double layer capacitor is used for supplying current to the starter which requires a very large current even in the on-vehicle electric load. I'm trying to do it from A large amount of lock-up current is required for a predetermined time in the initial operation of the starter. Therefore, this lockup current is supplied by an electric double layer capacitor capable of supplying a large current. On the other hand, on the other hand, the current supply to the electric load, which is vulnerable to voltage fluctuation and noise, is stably supplied by the lead storage battery which is not directly affected by the voltage fluctuation when the starter is driven, so that the operation is stabilized.

According to the vehicle power supply device using the electric double layer capacitor of the fourth aspect, in addition to the filter, a diode is provided in the connection line between the lead storage battery and the on-vehicle generator and the connection line between the electric double layer capacitor. It is connected in the forward direction to the electric double layer capacitor. This ensures charging of the electric double layer capacitor at the maximum voltage generated by the generator. Therefore, it is ensured that the starter can be driven with a voltage equal to or higher than the electromotive voltage of the lead storage battery when the starter is operating at the engine start. Further, the discharge from the electric double layer capacitor when the starter is not operated is suppressed by the diode, and the voltage drop of the electric double layer capacitor is also prevented.

According to the vehicle power supply device using the electric double layer capacitor of the fifth aspect, the charging line from the electric double layer capacitor to the lead storage battery is formed by connecting the forward diode and the open / close switch in series. Therefore, when the voltage of the lead storage battery is indefinite, this switch operation can replenish the electric power from the electric double layer capacitor side to the lead storage battery side, and ensure stable voltage supply to the electrical load connected to the lead storage battery. Can be improved.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a schematic circuit configuration of a first embodiment of the present invention.

As shown in the figure, the lead storage battery 20 is connected to the output terminal of the alternator 12, and the electric load A is connected to the positive terminal of the lead storage battery 20. Then, a connecting line 30 between the alternator 12 and the lead storage battery 20.
The positive terminal of the electric double layer capacitor 10 is connected to 0, and the positive terminal of the electric double layer capacitor 10 is connected to the electrical load B. In addition, the connection line 300
A filter 22 is connected in series to a connection line between the positive electrode terminal of the electric double layer capacitor 10 and the electric double layer capacitor 10.

The characteristic element of the present invention is that the electric load A is
The electric load B and the electric load B are distributed according to the respective characteristics of the electric double layer capacitor 10 and the lead storage battery 20. That is, the electrical load A supplied with current by the lead storage battery 20 is a device with a relatively small load, a device that is a noise source, a device that is easily affected by noise, a device that is prone to malfunction due to supply voltage fluctuations, Are connected. On the other hand, as the electrical load B, a relatively large load, a load that is not affected by noise, a load that is not a source of noise, a load that is less likely to malfunction due to fluctuations in the supply voltage, etc. are connected.

First, from the alternator 12, an AC voltage is converted into a DC voltage by a rectifying circuit incorporated therein, and the DC voltage is output. Here, when various electric loads are close to pure resistance, ripple noise is superimposed on the DC component and supplied to the lead storage battery 20 and the electric double layer capacitor 10. The lead storage battery 20 effectively exhibits a filter function for this, and can supply a DC voltage with a low noise level to the electrical load A.

Further, in an ECU or the like having a built-in computer included in the electric load A, stability of the voltage supplied from the power source is required, while noise is generated during its operation. A situation in which the power is returned to the power supply side tends to occur. Mainly, high frequency noise generated due to ripple noise can be sufficiently smoothed by the lead storage battery 20 having good frequency characteristics. On the other hand, a large-current electric load that causes a voltage fluctuation on the power supply device side can be connected to the electric double layer capacitor 10 to be separated from other electric loads that are weak against voltage fluctuation.

The filter 22 provided between the connection line 300 and the electric double layer capacitor 10 is a lead storage battery 20.
The ripple noise once smoothed by is further smoothed by. Therefore, a more smoothed voltage is supplied to the electric double layer capacitor 10, whereby a good state of charge is obtained. That is, this allows the electric double layer capacitor 10 to be biased to the rated voltage, and more electric power is stored in the electric double layer capacitor 10.

Next, FIG. 2 shows a second embodiment, and shows an example in which a starter 26 which is a large current load is connected to the output terminal side of the electric double layer capacitor 10. That is, the starter device 26 is connected to the positive terminal of the electric double layer capacitor 10 via the starter switch 24. When the engine is started, this starter device 26
Is supplied with a large lock-up current for a predetermined time.
Therefore, although the voltage of the electric double layer capacitor 10 varies greatly, the voltage variation on the lead storage battery 20 side is suppressed to a small level because the lead storage battery 20 is connected via the resistor 28. Therefore, a stable voltage is supplied from the lead storage battery to an electronic device such as an ECU that requires a stable voltage supply in a form in which the influence of voltage fluctuation during starter driving is suppressed as much as possible. Therefore, it is possible to suppress the occurrence of a start failure due to a malfunction of an electronic device such as an ECU.

Here, when the electric double layer capacitor 10 is in a discharged state, the electric double layer capacitor 10 must be recharged as quickly as possible for the next large current consumption. For that purpose, it is desirable that the resistance value of the resistor 28 is small. However, as described above, there is a situation in which the resistance value cannot be reduced in order to reduce the influence of voltage fluctuations on the lead storage battery during high current consumption during starter driving.

Therefore, in the third embodiment shown in FIG. 3, the diode 30 is connected in series with the resistor 28.
That is, one terminal of the resistor 28 is connected to the anode side of the diode 30, and the cathode side of the diode 30 is connected to the positive terminal of the electric double layer capacitor 10.

As a result, charging of the electric double layer capacitor 10 with the maximum voltage generated by the alternator 12 is ensured, whereby the charging time by the alternator 12 can be shortened.

The output voltage of the alternator 12 is given the output voltage characteristic with respect to the ambient temperature as shown in FIG. 8 in order to keep the lead storage battery 20 in the optimum charged state. Then, when the engine stops, the lead storage battery 20
Returns to the voltage equivalent to the original electromotive voltage. However, since the diode 30 is provided at this time, the electric double layer capacitor 10 can hold the maximum voltage during charging by the alternator 12 without being influenced by the voltage of the lead storage battery 20. Therefore, when restarting, the starter 26
A high voltage is biased from the electric double layer capacitor 10 to ensure extremely good engine startability.

The resistance value of the resistor 28 connecting the electric double layer capacitor 10 and the lead storage battery 20 is set not only by considering the filter function but also by charging the electric double layer capacitor 10 from the alternator 12 sufficiently. In such a case, it is set in consideration of performing supplementary charging from the lead storage battery 20 to the electric double layer capacitor 10.

When the electric double layer capacitor 10 is left unattended without being charged for a long period of time, the voltage drops due to self-discharge. In particular, the electric double layer capacitor 10 has a higher power density than the lead storage battery 20 and is most suitable for a load that requires a power source such as the starter 26, but since the energy density is much lower than that of the lead storage battery 20, Storage battery 2
Apparent voltage drop is faster than 0. Therefore, when such a self-discharge occurs, the supplemental charging by the lead storage battery 20 is performed, so that a good voltage of the electric double layer capacitor 10 is secured.

Next, when a relatively small lead-acid battery is installed in a vehicle as a filter, it consumes a large amount of electric load and is in a state where the amount of power generated from the alternator 12 is insufficient, such as when starting or immediately after starting. , In some cases, the voltage stability of lead acid batteries is not achieved. Therefore, in the fourth embodiment shown in FIG. 4, the lead storage battery 12 is replenished and charged from the electric double layer capacitor 10 side.

That is, the diode 32 is connected in series in the forward direction from the starter 26 side to the lead storage battery 20 side in the line opened and closed by the starter switch 24 to connect the electric double layer capacitor 10 to the lead storage battery 20 via the starter switch 24. The charging line 400 is formed. That is, the cathode side of the diode 32 is connected to the positive terminal of the lead storage battery 20, and the anode side of the diode 32 is the starter switch 24.
It is connected to the.

With such a circuit configuration, at the time of start-up when the state of charge for the small capacity lead-acid battery 20 installed for exhibiting the filter function is considered low, that is, when the starter switch 24 is turned on. Electric current can be supplied to the lead storage battery 20 from the electric double layer capacitor 10. As a result, the electric double layer capacitor 10 supplies a large current such as a starter load to stabilize the state of charge of the lead storage battery 20 that has been reduced in size and weight, thereby ensuring the voltage stability of the electric load. As a result, the lead storage battery can be made smaller and the charging system can be made lighter and smaller, and the space for the power supply device can be effectively utilized.

In the embodiment shown in FIG. 1 as well, since the electrical load A for supplying current from the lead storage battery 20 side is selected to be a relatively small load, its capacity is reduced. The size of the entire power supply device can be reduced.

Further, in each of the embodiments shown in FIGS. 2 to 4, only the starter device is shown as the load of the electric double layer capacitor 10, but the present invention is not limited to such a configuration, and in FIG. It is also possible to supply current to a load that satisfies the conditions of the other electrical load B described above.

[0040]

As described above, according to the vehicle power supply device using the electric double layer capacitor according to the present invention, the electric double layer capacitor ensures a large current supply to a load requiring a large current and a lead storage battery. As a result, it is possible to ensure a stable supply of voltage to a load that is weak against voltage fluctuation. Furthermore, the noise generated in the load can be reliably removed, and the influence of noise can be eliminated as much as possible, and a well-balanced function improvement of the vehicle power supply device using the electric double layer capacitor can be achieved. As a result, it is possible to improve the fuel efficiency by reducing the weight of the entire power supply device, save resources, and effectively use the battery space by reducing the size.

[Brief description of drawings]

FIG. 1 is a schematic circuit configuration diagram showing a first embodiment.

FIG. 2 is a schematic circuit configuration diagram showing a second embodiment.

FIG. 3 is a schematic circuit configuration diagram showing a third embodiment.

FIG. 4 is a schematic circuit configuration diagram showing a fourth embodiment.

FIG. 5 is an explanatory diagram of a power supply device using a conventional electric double layer capacitor.

FIG. 6 is a graph showing a self-discharge characteristic of an electric double layer capacitor.

FIG. 7 is a graph showing frequency characteristics of the electric double layer capacitor.

FIG. 8 is a graph showing the power generation characteristics of the alternator.

FIG. 9 is an explanatory diagram showing a general configuration of an electric double layer capacitor.

[Explanation of symbols]

 10 Electric Double Layer Capacitor 20 Lead Acid Battery 22 Filter 28 Resistance 30 Diode 400 Lead Acid Battery Charging Line

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H02J 7/14 H01G 9/00 301Z

Claims (5)

[Claims] 1. A vehicle power supply device having an electric double layer capacitor charged by an on-vehicle generator and a lead storage battery for supplying current to various electric loads mounted on a vehicle, wherein: , An electric load smaller than the electric load fed from the electric double layer capacitor side, an electric load that is a noise generation source, an electric load that is easily affected by noise, or a malfunction due to fluctuations in the supplied voltage The electric current is easily supplied to the electric load, and from the electric double layer capacitor side, an electric load larger than the electric load fed from the lead storage battery side, an electric load that does not become a noise generation source, and a noise The lead storage battery and the electric double layer capacitor so as to supply a current to an electric load that is not easily affected or an electric load that is unlikely to cause a malfunction due to fluctuations in the supplied voltage. Vehicle power supply device using an electric double layer capacitor, characterized in that connection to the respective load is performed. 2. The lead storage battery is directly connected to an output terminal of the generator, and the electric double layer capacitor is connected to a connection line between the lead storage battery and the generator via a filter. A power supply device for a vehicle using the electric double layer capacitor according to claim 1. 3. The power supply device for a vehicle using an electric double layer capacitor according to claim 1, wherein the electric double layer capacitor is connected so as to supply current to the starter of the engine only. . 4. The forward diode to the electric double layer capacitor is connected to the connection line between the lead storage battery and the generator in addition to the filter. A vehicle power supply device using an electric double layer capacitor. 5. A charging line formed by connecting a forward diode and an open / close switch in series from the electric double layer capacitor to the lead storage battery is provided. Power supply device for vehicles using the electric double layer capacitor of.