JP3306326B2 - Capacitor power storage device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitor power storage device for storing power in a capacitor, converting a voltage that decreases with discharge into a constant rated voltage, and supplying the same.

[0002]

2. Description of the Related Art FIG. 7 is a diagram showing a standard configuration example of an ECS, and FIG. 8 is a diagram showing a step-up / step-down operation region of an ECS current pump. A chemical battery that has been used for power storage is a constant voltage device, and can supply a substantially constant voltage in a normal operating range regardless of the amount of charge. On the other hand, since the terminal voltage of the capacitor greatly changes from the value at the time of full charge to zero with discharge, if the range of the change is suppressed and used, the amount of power that can be stored is reduced.

[0003] As an electric vehicle power supply device or a large-scale power storage device, ECS (E
Attention has been focused on power storage devices based on the Nergy Capacitor System). Electric double-layer capacitors have the major advantage of being able to store a large amount of energy, as well as being able to rapidly charge by physical charging, like other capacitors, compared to chemical batteries that take a long time to charge. .
However, the supply when by increasing the storage amount of the power as described above attempts to effectively utilize it, since the terminal voltage varies greatly based on the relationship Q = CV ^2/2, a stable rated voltage to a load To this end, a large adjustment of the output voltage is required in the ECS.

In an electric power storage device based on ECS, as shown in FIG. 7, electric power is taken out of an electric double layer capacitor storing electric power by a switching type DC / DC converter called a current pump, and supplied to a load at a constant voltage. ing. The current pump used at this time may be a step-down chopper, a step-up chopper, or another DC / DC converter. However, since high efficiency is an essential condition, a type using a transformer is not advantageous.

[0005] Now, in an ECS power storage device, if it is attempted to use the capacitor voltage up to 1/4 of the voltage when fully charged, the power is 15/16 = 93,75%.
Will be used. In order to realize this, in the boost converter, the output voltage Vo is selected to be equal to the voltage Vo ^* 4 at the time of full charge, and the converter is boosted by the converter as shown in up of FIG. 8 so that the output always becomes Vo ^* 4. Just fine. At this time, the operation range of the boost converter is boosted from 1 to 4 times. In the step-down converter, the output voltage Vo
8 is selected to be equal to 1/4 of the voltage Vo ^* 1 when fully charged.
As shown in the down of FIG.
If the voltage is reduced to 4 and the step-down ratio is reduced along with the discharge to control the output to always be Vo ^* 1, the rated voltage can be supplied until the voltage of the capacitor becomes the first quarter. Therefore, the operation range of the step-down converter at this time is step-down from 1/4 to 1.

As described above, in the ECS, the voltage range of a capacitor to be used is widened to increase the amount of electric power that can be stored. Therefore, it is an essential phenomenon that the terminal voltage of the capacitor greatly changes. However, depending on the application, it may be inconvenient for the ECS to significantly change the voltage as compared with the conventional secondary battery.

As an example, in an electric vehicle, there is a demand to use as low a voltage as possible in order to avoid an electric shock accident.
The current increases and the wires and equipment become prohibitively large.
For example, if you try to change an electric vehicle with a rated voltage of 300V from a secondary battery to a capacitor power supply used in the above voltage range, load a capacitor that fully charges 1200V, four times that of the above, and a quarter step-down chopper. And may increase safety costs. On the other hand, when fully charging 300 V, it is necessary to use a quadruple step-up chopper or conversely use a step-down chopper to lower the output voltage to 75 V.

[0008] As another example, consider power storage.
When power is stored at 4000 V, the maximum voltage of the capacitor in the step-down type is quadrupled to 16000 V, and the components and insulation are not included, but it is difficult to prepare a device that can handle the switching semiconductor element. Even if it is a boost type, not only efficiency will decrease to boost 4 times, but also
It becomes difficult to manufacture a boost choke coil.

[0009]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and realizes the power storage of a capacitor bank and its utilization with high efficiency.

For this purpose, the present invention provides a capacitor power storage device for storing power in a capacitor and converting the voltage that decreases with discharge to a constant rated voltage and supplying the same to a constant rated voltage, comprising a plurality of capacitor banks for storing power. A power storage unit; a voltage when the power storage unit is fully charged;
/ 2 is set to a rated voltage, and a step-down circuit that steps down to the rated voltage when the output voltage of the power storage unit is higher than the rated voltage, and a rated voltage when the output voltage of the power storage unit is lower than the rated voltage. And a voltage adjusting unit configured to adjust the output voltage of the power storage unit, the voltage adjusting unit including a booster circuit that boosts the voltage up to
According to another feature of the present invention, the voltage regulator switches between step-down / step-up and adjusts to a rated voltage in response to a change in output voltage accompanying the discharge from the power storage unit.

[0011] The voltage adjusting section may include a first chopper switching element, a choke coil, and a first unidirectional rectifying element inserted and connected in series to a power supply line. A step-down chopper circuit is formed by connecting a second unidirectional rectifier to a series connection point with a choke coil, and a second chopper switching element is connected to a series connection point between the choke coil and the first unidirectional rectifier. To form a step-up chopper circuit, or a step-down circuit and a step-up circuit are constituted by an AC / DC conversion circuit, wherein the power storage unit includes two capacitor banks in which a plurality of capacitors are connected in series and parallel. And the two capacitor banks are connected in parallel on condition that the voltage is more than half of the full charge, and is reduced to less than half of the full charge. It is characterized in that it has a switching means for switching connection to the serial connection to the condition.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a series-parallel connection switching capacitor power storage device according to the present invention,
FIG. 2 is a diagram for explaining an operation range. In the figure, 1 is a step-down chopper circuit, 2 is a step-up chopper circuit, 3 is a series-parallel switching circuit, 4 is a comparator, 5 is a step-down chopper control circuit, 6
Is a boost chopper control circuit, 7 is an inverter, 8 is an error amplifier, C ₁ and C ₂ are capacitor banks, D ₁ , D ₂ and D
_D and D _U are unidirectional rectifying elements, CH _D and CH _U are chopper switching elements, L is a choke coil, S ₁ is a changeover switch, and V _rI and V _rO are reference voltages.

In FIG. 1A, a capacitor bank C
₁ and C ₂ are connected in series in parallel with a plurality of electric double layer capacitors having, for example, a parallel monitor for power storage, and are connected in series to unidirectional rectifiers D ₁ and D ₁ .
_2, constitutes a power storage unit by the changeover switch S ₁ to perform connection switching of these series-parallel. The series-parallel switching circuit 3 compares the terminal voltage of the power storage unit with the reference voltage V _rI to control the on / off of the switching switch S ₁ , so that the parallel connection and the series connection of the capacitor banks C ₁ and C ₂ can be performed. The reference voltage V _rI is set to _に of the voltage when the capacitor banks C ₁ and C ₂ are fully charged. Changeover switch S ₁ is turned off from the capacitor bank C _1, C ₂ is fully charged until discharging the half voltage, the capacitor bank C _1, C ₂
Is turned on when the voltage of the battery becomes 1/2 or less of the full charge,
To connect the capacitor banks C ₁ and C ₂ in series,
It is controlled by the series / parallel switching circuit 3. Therefore, the series-parallel switching circuit 3 may be configured to compare the terminal voltage of _one of the capacitor banks C ₁ and C ₂ with the reference voltage V _rI . When the voltage of the capacitor banks C ₁ and C ₂ becomes less than half of the full charge, the changeover switch S ₁
Is turned on to form a series connection, so that the voltage of the power storage unit is doubled, and by extracting the voltage from the time of full charge to half of the voltage to be discharged, a 94% discharge is obtained. Electricity can be used. Changeover switches S ₁ and chopper switching element, C
H _D, CH _U is composed of semiconductor elements other switching elements such as MOSFET or a bipolar transistor.

The choke coil L is a step-down chopper circuit 1
The step-down chopper circuit 1 and the step-up chopper circuit 2 control the operation of the chopper from the step-down chopper circuit 1 to the step-up chopper in the middle of the voltage at the time of full charge and half the voltage. Switching to the circuit 2 is performed. During operation of the step-down chopper circuit 1, chopper switching element CH _U of the step-up chopper circuit 2 is in a state in which off, chopper switching element CH _D steps down to turn on / off, the output voltage load Adjust to the rated voltage. Further, during the operation of the boost chopper circuit 2 is in a state where chopper switching element CH _D is turned on, and the booster chopper switching element CH _U on / off to the output voltage to the rated voltage of the load adjust. FIG. 1B shows a specific configuration example of the switching control circuit.

In FIG. 1B, the reference voltage V _rO corresponds to the rated voltage supplied to the load of the power storage device,
Is intended to be used for reference voltage for the switching of the step-up chopper control at the same time as the step-down chopper control when used in reference voltage for the error detection of the chopper control, full charge when the voltage of the capacitor bank C _1, C ₂ and its An intermediate value from the voltage of 1/2 is set. For example, if the rated voltage of the load is 75
In the case of V, assuming that the full charge voltage of the capacitor banks C ₁ and C ₂ is 100 V, the region from 100 V to 75 V is controlled by the step-down chopper circuit, and from 75 V to 50 V which is １ ／ of the full charge voltage. Is controlled by a step-up chopper circuit to supply a rated voltage of 75V.

[0016] The comparator 4 compares the terminal voltage and the reference voltage V _{and rO} power storage unit, the output signal activated when the terminal voltage of the power storage unit is greater than the reference voltage V _{and rO,} the reference voltage V _{and rO} When it becomes smaller, the output signal becomes non-active, and the inverter 7 inverts the output signal of the comparator 4. The error amplifier 8 detects and amplifies an error between the output voltage supplied to the load and the reference voltage _VrO, and _uses this error amplification signal as a control signal for the step-down chopper control circuit 5 and the step-up chopper control circuit 6. Is done.

The step-down chopper control circuit 5 operates on condition that the output signal of the comparator 4 is active, and on / off control of the chopper switching element CH _D based on the error amplification signal of the error amplifier 8, When the output signal of the comparator 4 becomes non-active, the operation is stopped, and the chopper switching element CH _D is turned on and the unidirectional rectifier element D _D is turned off.

The boost chopper control circuit 6 includes an inverter 7
By inputting the output signal of the comparator 4 through
And stops the operation on condition that the output signal of the comparator 4 is active, the chopper switching element CH _U to the OFF state, operates the output signal of the comparator 4 becomes non-active, the error amplifier 8 of the chopper switching element CH _U based on the error amplification signal is for on / off control.

Next, the overall operation will be described. Now, when the capacitor banks C ₁ and C ₂ are fully charged, that is, when the discharge power amount shown in FIG. 2 is 0%, the changeover switch S ₁ is controlled to be turned off, and the output signal of the comparator 4 becomes active. Therefore, the step-down chopper control circuit 5 operates and the step-up chopper control circuit 6 stops operating. Therefore, the voltage of the power storage unit is reduced by 25 by the step-down chopper circuit 1.
% To be supplied to the load. As the amount of discharged power increases, the voltage of the power storage unit decreases as shown in FIG.
When the voltage becomes equal to the rated voltage of the load, the output signal of the comparator 4 becomes non-active, so that the step-down chopper control circuit 5 stops operating and the step-up chopper control circuit 6 starts operating. Further voltage of the discharge power amount is a power storage unit becomes 75% is 1/2 of the time of full charge decreases, so to turn on the switch S ₁ operates the serial-parallel switching circuit 3,
The capacitor banks C ₁ and C ₂ are connected in series, and the voltage of the power storage unit rises to the same voltage as at the time of double full charge. Therefore, the output signal of comparator 4 becomes active again, so that boost chopper control circuit 6 stops operating and step-down chopper control circuit 5 starts operating. In this way, it is possible to supply power to the load at the rated voltage until the discharge power amount of the power storage unit finally becomes 94% and the voltage becomes half of the voltage at the time of full charge.

It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible. For example, in the above-described embodiment, the rated voltage of the load is set to be 75 when the voltage of the capacitor banks C ₁ and C ₂ at the time of full charge is set to 100.
Needless to say, the rated voltage of the load can be set arbitrarily up to the voltage of. In this case, when the voltage at the time of full charge is equal to the rated voltage of the load, only the boost chopper circuit is used, and the voltage of half of the voltage at the time of full charge is equal to the rated voltage of the load. In this case, only the step-down chopper circuit may be used. FIG. 3 is a diagram showing the respective control regions when configured with a boost chopper circuit or a step-down chopper circuit. Further, although the step-down chopper circuit and the step-up chopper circuit are connected in series by sharing the choke coil, the step-down chopper circuit and the step-up chopper circuit may be connected in parallel. In addition, single-phase bridge inverters, single-phase push-pull, single-phase half-bridges,
Furthermore, it may be combined with an AC / DC conversion circuit such as a three-phase or six-phase polyphase bridge inverter, or the combination may be used to realize a reversible power storage device.

FIG. 4 is a diagram showing a configuration example of a single-phase bridge inverter, FIG. 5 is a diagram showing a configuration example of a reversible power storage device,
FIG. 6 is a diagram showing a modified example of the converted waveform in the case of pulse width modulation. When a single-phase bridge inverter shown in FIG. 4A is used to convert DC to sine-wave AC by PWM (pulse width modulation) as shown in FIG. 4B, a sine wave with few harmonics is obtained. Requires a rather deep pulse width modulation in the process. Most large inverters for power use have input fluctuation specifications within ± 20%. If the DC input voltage fluctuates greatly, for example, as much as four times, the depth and controllability of pulse width modulation (feedback control A problem is liable to occur in a condition in which stable automatic control is performed without causing oscillation or hunting in a running state), and design becomes difficult. However, if the power storage device is configured to switch the capacitor banks in series / parallel as described above, the DC input can be suppressed to four to two times. Further, by combining the above-mentioned choppers, the input fluctuation width can be reduced. Therefore, a reversible power storage device can also be realized by replacing the unidirectional rectifying element with a bidirectional switching element and connecting a PWM inverter as shown in FIG. Moreover, the PWM part can be designed much more easily, stably and efficiently. In this case, by controlling the inverter in the reverse direction, the capacitor can be treated as a constant current type charger, and the same device can be used also as the charger. In pulse width modulation, various waveforms from a rectangular wave to a pseudo sine wave are used in practical use. However, since the original purpose is to obtain a sine wave, the waveform shown in FIG. Such a modified rectangular wave can also be adopted.

[0022]

As is apparent from the above description, according to the present invention, a power storage unit composed of a plurality of capacitor banks for storing power, a voltage when the power storage unit is fully charged, and a voltage of the voltage. Set the voltage in the middle of 1/2 to the rated voltage,
It consists of a step-down circuit that steps down to the rated voltage when the output voltage of the power storage unit is higher than the rated voltage and a booster circuit that boosts the output voltage to the rated voltage when the output voltage of the power storage unit is lower than the rated voltage. A voltage adjustment unit,
According to the fluctuation of the output voltage accompanying the discharge from the power storage unit,
Since the voltage regulator switches between step-down / step-up and adjusts to the rated voltage, the switching regulator can be used in an efficient area, and power storage and use of the capacitor bank can be realized with high efficiency. In addition, since the power storage unit can be configured with a voltage substantially equal to the rated voltage of the load, the voltage rating of the control element and the like can be suppressed low, and a control element that is economical and has low internal resistance can be used. In addition, the inductance of the choke coil is minimized, and the size and weight can be reduced. In addition, most of the time during which the chopper operates is under operating conditions in which the transformation ratio is small and high efficiency can be easily obtained, so that power loss can be minimized.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a series-parallel connection switching capacitor power storage device according to the present invention.

FIG. 2 is a diagram illustrating an operation range.

FIG. 3 is a diagram illustrating respective control regions when configured with a step-up chopper circuit or a step-down chopper circuit.

FIG. 4 is a diagram illustrating a configuration example of a single-phase bridge inverter.

FIG. 5 is a diagram illustrating a configuration example of a reversible power storage device.

FIG. 6 is a diagram showing a modified example of a converted waveform in the case of pulse width modulation.

FIG. 7 is a diagram showing a standard configuration example of an ECS.

FIG. 8 is a diagram showing a step-up / step-down operation region of the ECS current pump.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Step-down chopper circuit, 2 ... Step-up chopper circuit, 3 ... Series-parallel switching circuit, 4 ... Comparator, 5 ... Step-down chopper control circuit, 6 ... Step-up chopper control circuit, 7 ... Inverter, 8 ...
Error amplifier, C ₁ , C ₂ ... capacitor bank, D ₁ , D
_{2, D D, D U} ... unidirectional rectifying element, CH _D, CH _U ... chopper switching element, L ... choke coil, S ₁
... change-over switch, V _rI, V _rO ... reference voltage

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02J 1/00-1/16 H02J ⁷ /00-7/36

Claims (4)

(57) [Claims] 1. A capacitor power storage device for storing power in a capacitor and converting the voltage that decreases with discharge to a constant rated voltage and supplying the same to a constant rated voltage, comprising: a power storage unit including a plurality of capacitor banks for storing power; A step-down circuit that sets an intermediate voltage between the voltage of the power storage unit at the time of full charge and half of the voltage to a rated voltage, and reduces the voltage to the rated voltage when the output voltage of the power storage unit is higher than the rated voltage. And a voltage adjustment unit that adjusts the output voltage of the power storage unit, the output unit including a booster circuit that boosts the output voltage of the power storage unit to the rated voltage when the output voltage is lower than the rated voltage. A capacitor power storage device characterized in that the voltage regulator switches between step-down / step-up and adjusts to a rated voltage in accordance with a change in voltage. 2. The voltage adjusting section according to claim 1, wherein the first chopper switching element, the choke coil, and the first unidirectional rectifier are inserted and connected in series to a power supply line, and the first chopper switching element is connected to the first chopper switching element. A step-down chopper circuit is formed by connecting a second unidirectional rectifier to a series connection point with a choke coil, and a second chopper switching element is connected to a series connection point between the choke coil and the first unidirectional rectifier. 2. The capacitor power storage device according to claim 1, wherein a step-up chopper circuit is configured by connecting the step-up chopper circuit. 3. The voltage adjustment unit according to claim 1, wherein the step-down circuit and the step-up circuit are configured by an AC / DC conversion circuit.
A capacitor power storage device as described. 4. The power storage unit includes two capacitor banks in which a plurality of capacitors are connected in series / parallel, and a condition that a voltage of the two capacitor banks is more than half of a full charge. 2. A capacitor power storage device according to claim 1, further comprising: switching means for connecting in parallel with each other and switching to serial connection on condition that the voltage is reduced to １ ／ or less of a full charge.