JP2000175363A - Power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply capable of preventing a transversal current when a state of serial connection of a plurality of capacitor battery is changed to a state of parallel connection. SOLUTION: In a power supply, a battery with a large variation in voltage, in which the voltage is gradually lowered when energy is taken from a full charged state, is used, and a switching circuit 10 for changing a state of connection from serial to parallel or from parallel to serial of a plurality of batteries with large variation in voltage is provided. The switching circuit 10 includes rectifying means 13, 14, 16, and 17, and switches 11a, 11b, 11e, and 11d to prevent a transverse current flowing according to a remaining voltage difference of each battery when the serial connection is changed to parallel connection in the battery with the large variation in voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device using a battery having a large voltage fluctuation, in which a voltage gradually decreases when energy is extracted from a fully charged state.

[0002]

2. Description of the Related Art Recently, attempts have been made to use an electric double layer capacitor as a battery for electric power.
This type of battery has a great difference in the output characteristics as compared with conventionally known lead batteries and nickel-cadmium batteries. In other words, the terminal voltage of a lead battery or nickel-cadmium battery shows almost constant constant voltage characteristics regardless of the amount of energy stored in the battery even when power is supplied to a load, whereas the electric double layer capacitor battery Has a characteristic that the terminal voltage of the battery changes greatly depending on the amount of stored energy. More specifically, in an electric double layer capacitor battery, the stored energy is 100%
If the battery voltage at the time of (1) is 100% and the stored energy is 25%, the battery voltage will drop to about 50% at the time of full charge.

Therefore, as a countermeasure against this, a power supply device as shown in FIG. 2 has been proposed (Japanese Patent Application Laid-Open No. 8-16818).
No. 2). In FIG. 2, a capacitor battery C1,
C2 is an electric double-layer capacitor battery having substantially the same characteristics. Switches S1 to S3 operate in conjunction with switches S2 and S3, and switches S1 and S3 operate in a complementary manner, according to the voltages of capacitor batteries C1 and C2. On / off control is performed. In this power supply device, when the capacitor batteries C1 and C2 are fully charged, the switch S1 is turned off, the switches S2 and S3 are turned on, and the two are connected in parallel.
And the switches S2 and S3 are turned off to connect them in series. The load RL is, for example, a power motor for an electric vehicle, or a heater for a heater. The output conversion / adjustment circuit A includes switching means that is intermittently controlled by a pulse signal.
For example, a circuit for stabilizing an output voltage with a boost converter or a step-down converter is shown.

[0004] Explaining the operation of the power supply device as described above, those having a full charge voltage of 24 V are selected as the capacitor batteries C1 and C2. And capacitor battery C
When the switches S1 and S3 are turned off and the switches S2 and S3 are turned on, the capacitor batteries C1 and C2 are fully charged.
Are 24V, so that the output conversion
In the adjustment circuit A, the voltage is reduced by half with respect to the input of 24 V, and the power is supplied to the load RL at the rated voltage of 12 V. When energy is consumed by the load RL and the voltage between the terminals of the capacitor batteries C1 and C2 decreases, the output conversion / adjustment circuit A reduces the step-down ratio from 1/2 until the voltage between the terminals of the capacitor batteries C1 and C2 decreases to 12V. Power is supplied to the load RL at a stable rated voltage of 12 V by changing it to 1/1. When approximately 75% of the energy is extracted from the capacitor batteries C1 and C2, the voltage between the terminals of the capacitor batteries C1 and C2 drops to 12 V. At this time, the switches S2 and S3 are turned off and then the switch S1 is turned on. By doing so, the capacitor batteries C1 and C2 are connected in series. Then,
Since 24 V is input again to the output conversion / adjustment circuit A, the voltage is reduced by half to 12 V in the same manner as at the time of full charge.
Power is supplied to the load RL at the rated voltage of, and approximately 20% of energy is taken out.
Until the voltage drops to 2V, power can be supplied to the load RL at a stable rated voltage of 12V.

If the voltage at which 94% of the energy is extracted is the rated voltage of the load, the capacitor batteries C 1,
When C2 is connected in series, the input voltage of the output conversion / adjustment circuit A becomes four times at the time of full charge. Therefore, the output conversion / adjustment circuit A does not change the step-down ratio from 1/4 to 1/1. However, when the capacitor batteries C1 and C2 are switched from the parallel connection at the time of full charge to the series connection when the voltage between the terminals is reduced to half as in the apparatus shown in FIG. The circuit A may change the step-down ratio from 1/2 to 1/1. Therefore,
The output conversion / adjustment circuit A can perform high-efficiency conversion by reducing the width of the step-down ratio, and can reduce the voltage to half, so that the degree of freedom in selecting the semiconductor to be used can be increased.

[0006]

However, in practice, each of the capacitor batteries C1 and C2 has a difference in characteristics, and in the above-described power supply device, the series charging and discharging of the capacitor batteries C1 and C2 is performed. At times, the difference between the characteristics of these two capacitor batteries C1 and C2 causes a change in the voltage balance between the two batteries, resulting in a state where the voltages of the two batteries are greatly different. If the capacitor batteries C1 and C2 are connected in parallel in order to switch the voltage in a state where the voltages of both batteries are greatly different, a situation occurs in which a large cross current flows according to the residual voltage difference between both batteries. When such a cross current flows, when a voltage switching switch, particularly a semiconductor switch, is used, the switching element may be damaged depending on the magnitude of the current. Therefore, the present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a power supply device capable of preventing a cross current generated when switching the connection of both batteries from a series connection to a parallel connection. To provide.

[0007]

That is, according to the present invention, a battery having a large voltage fluctuation whose voltage gradually decreases in extracting energy from a fully charged state is used, and a plurality of batteries having a large voltage fluctuation are connected in parallel. And a switching circuit for switching from series connection to series connection to parallel connection, wherein the switching circuit includes a rectifier and a switch, and switches the battery with large voltage fluctuation from series connection to parallel connection. In this case, there is provided a power supply device characterized by preventing a cross current flowing according to a residual voltage difference of each battery.

Further, in the power supply device of the present invention, the switching circuit has first to fifth switching switches, and includes a first rectifying unit including a combination of a first diode and a first switching switch; First switching means in which a second diode, which is opposite to the first diode, and a second rectifying means, which is a combination of a second changeover switch, are connected in parallel; a third diode and a third changeover switch Second rectifying means connected in parallel with a third rectifying means composed of a combination of the third diode and a fourth rectifying means composed of a combination of a fourth diode and a fourth changeover switch, which are opposite to the third diode. And a series circuit of the battery and the first switching means and a series circuit of the battery and the second switching means are connected in parallel, and a fifth circuit is connected between the series connection points between the respective series circuits. A changeover switch is connected, and the first changeover means and the second changeover switch are connected to the fifth changeover switch.
It is preferable that the switching means be operated complementarily. In the present invention, an electric double layer capacitor can be cited as a battery having a large voltage fluctuation. An example of a battery having a large voltage fluctuation is an electric double layer capacitor bank in which a plurality of electric double layer capacitors having substantially the same characteristics are connected in series.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a power supply device according to the present invention will be described based on embodiments shown in the drawings. FIG. 1 is a circuit diagram showing one embodiment of a switching circuit in a power supply device according to the present invention. As shown in FIG. 1, the switching circuit 10 includes first to fifth changeover switches 11a, 11b, 11c, 1
1d, 11e, a first rectifier 13 composed of a combination of a first diode 12a and a first changeover switch 11a, and a second rectifier 13 which is opposite to the first diode 12a.
The first switching means 15 is formed by connecting the diode 12b and the second rectifying means 14 composed of the combination of the second changeover switch 11b in parallel, and the combination of the third diode 12c and the third changeover switch 11c. The third rectifier 16 and a fourth rectifier 16 which is opposite to the third diode 12c.
And a second switching unit 18 in which a fourth rectifying unit 17 composed of a combination of the diode 12d and the fourth changeover switch 11d is connected in parallel.

In this switching circuit 10, a series circuit of a capacitor battery 20 a and a first switching means 15, a capacitor battery 20 b and a second switching means 18
Are connected in parallel with each other, and a fifth changeover switch 11e is connected between series connection points between the respective series circuits. The switching circuit 10 is configured as described above, and the output conversion / adjustment circuit, which is another element constituting the power supply device, is the same as that in FIG.

Next, the operation of the switching circuit 10 will be described.
First, the capacitor batteries 20a and 20b are fully charged, and the second changeover switch 11b and the fourth changeover switch 11d
Is turned off, the fifth changeover switch 11e is turned off, and the first
When the changeover switch 11a and the third changeover switch 11c are turned on, the voltage between the terminals of the capacitor batteries 20a and 20b, for example, the input of 24V, is reduced to half by an output conversion / adjustment circuit or the like (not shown). Power the load. This is discharge.

Next, when energy is consumed by the load and the voltage between the terminals of the capacitor batteries 20a and 20b decreases, the voltage between the terminals of the capacitor batteries 20a and 20b is reduced to 12V in the output conversion / adjustment circuit, as in FIG. The step-down ratio is changed from 1/2 to 1/1 until the voltage drops, and power is supplied to the load at a stable rated voltage of 12V. Capacitor battery 2
When a predetermined amount (for example, about 75%) of energy is extracted from the battery cells 20a and 20b, the capacitor batteries 20a and 20b
Since the terminal-to-terminal voltage drops to 12 V, the first
By turning off the changeover switch 11a and the third changeover switch 11c and then turning on the fifth changeover switch 11e, the capacitor batteries 20a and 20b are connected in series. Then, the output conversion / adjustment circuit again has 2
Since 4V is input, 1 /
2, the power is supplied to the load at a rated voltage of 12 V, a predetermined amount (for example, about 20%) of energy is extracted, and the voltage between the terminals of the capacitor batteries 20a and 20b is reduced to 6%.
Until the input voltage of the V / output conversion / adjustment circuit drops to 12V, power is supplied to the load at a stable rated voltage of 12V.

As described above, the capacitor battery 20
When the discharge operation in which a predetermined amount of energy is taken out from the battery cells 20a and 20b is completed, the capacitor battery 2
A charging operation that satisfies energy at 0a and 20b is performed.
At the time of this charging, first, the first to fourth changeover switches 1
After turning off 1a, 11b, 11c and 11d, the fifth
By turning on the changeover switch 11e, the capacitor batteries 20a and 20b are connected in series, and a voltage (in a direction opposite to that at the time of discharging) is applied to this series circuit to be charged. After the capacitor batteries 20a and 20b are charged with a predetermined amount of energy (that is, after the terminal voltages of the capacitor batteries 20a and 20b reach approximately 12 V, respectively), the fifth
By turning off the changeover switch 11e, the second changeover switch 11b and the fourth changeover switch 11d are turned on, thereby connecting the capacitor batteries 20a and 20b in parallel, and applying a voltage to this parallel circuit for charging. . In this way, the voltage between the terminals of each of the capacitor batteries 20a and 20b is fully charged to a predetermined value, for example, 24V.

In the power supply device of FIG. 1, as described above, the fifth changeover switch 11e is turned off, and the second changeover switch 11b and the fourth changeover switch 11d are turned on, whereby the capacitor batteries 20a, When switching the series connection 20b from the series connection to the parallel connection, the second rectifier 14 is composed of a combination of the second diode 12b and the second switch 11b.
Is the fourth diode 12d and the fourth changeover switch 11d
, The current does not flow backward, and no cross current occurs unlike the conventional circuit shown in FIG.

The embodiment of the power supply device using the electric double layer capacitor battery as the battery having a large voltage fluctuation has been described above. However, the present invention is not limited to this. Accordingly, the present invention can also be applied to a battery whose terminal voltage greatly fluctuates, a capacitor using a charge storage function such as a conductive polymer, or the like.

[0016]

As described above, according to the power supply device of the present invention, when the connection of a plurality of capacitor batteries is switched from series connection to parallel connection, cross current flowing according to the residual voltage difference of each battery is prevented. Thus, it is possible to prevent the switching element of the voltage switching switch such as a semiconductor switch from being damaged.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of a switching circuit in a power supply device according to the present invention.

FIG. 2 is a circuit diagram illustrating an example of a conventional power supply device.

[Explanation of symbols]

10 switching circuit, 11a first switching switch, 11b
... 2nd changeover switch, 11c ... 3rd changeover switch,
11d: fourth changeover switch, 11e: fifth changeover switch, 12a: first diode, 12b: second diode, 11c: third diode, 12d: fourth diode, 13: first rectifier , 14 ... second rectification means,
15: first switching means, 16: third rectifying means, 1
7: fourth rectifying means, 18: second switching means, 20
a, 20b: Capacitor battery.

Claims (4)

[Claims] 1. A method of using a battery having a large voltage fluctuation whose voltage gradually decreases in extracting energy from a fully charged state, and switching a plurality of batteries having a large voltage fluctuation from parallel connection to series connection or from series connection to parallel connection. A power supply device provided with a circuit, wherein the switching circuit includes a rectifier and a switch, and according to a residual voltage difference of each battery when the battery having a large voltage fluctuation is switched from series connection to parallel connection. A power supply device characterized by preventing a flowing cross current. 2. The switching circuit has first to fifth changeover switches, a first rectifier comprising a combination of a first diode and a first changeover switch, and an opposite direction to the first diode. A first switching means connected in parallel with a second rectifying means comprising a combination of a second diode and a second changeover switch, and a third switching means comprising a combination of a third diode and a third changeover switch. A battery comprising: rectifying means; and second switching means, which is connected in parallel with a fourth diode and a fourth rectifying means, which is a combination of a fourth diode and a fourth changeover switch, which are opposite to the third diode. And a series circuit of the first switching means and a series circuit of the battery and the second switching means are connected in parallel, and a fifth changeover switch is connected between the series connection points between the respective series circuits. 5 The power supply device according to claim 1, wherein the first switching means and the second switching means are operated complementarily to the changeover switch. 3. The power supply device according to claim 1, wherein the battery having a large voltage fluctuation is an electric double layer capacitor. 4. The power supply device according to claim 1, wherein said battery having a large voltage fluctuation is an electric double layer capacitor bank in which a plurality of electric double layer capacitors having substantially the same characteristics are connected in series.