JPH11215695A - Series-parallel switching type power supply unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the variation width of the voltage of a power supply unit which uses a battery with a large voltage variation, whose voltage changes gradually in taking out energy as seen in a capacitor. SOLUTION: This power supply unit uses a battery with a large voltage variation whose energy is charged and stored and whose voltage decreases gradually as the stored energy is taken out, whereas battery units 1 to (n) are constituted of a pair of batteries C11 to Cn2 with a large voltage variation as seen in an electric double layer capacitor bank with a plurality of capacitors as power storage connected in series and parallel and switching means S11 to Sn3 which conduct switching between parallel connection and series connection of a pair of the batteries C11 to Cn2. A pair of the batteries C11 to Cn2 are switched from the parallel connection to the series connection by serially- connecting the battery units 1 to (n) to a plurality of stages, and controlling the switching means S11 to Sn3 stepwise for a plurality of stages of the battery units 1 to (n) with an decrease 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 energy is charged and stored, and the voltage is gradually changed in accordance with the amount of charge and discharge as the stored energy is taken out.

[0002]

2. Description of the Related Art ECS using an electric double layer capacitor
(Energy Capacitor System) has attracted attention as a power supply device for electric vehicles and a large-scale power storage device. Electric double layer capacitors can be rapidly charged by physical charging, like other capacitors, compared to chemical batteries that take a long time to charge, such as lead batteries and nickel-cadmium batteries. In addition, a chemical battery is a constant voltage device, and its terminal voltage shows almost constant constant voltage characteristics regardless of the amount of energy stored in the battery even when power is supplied to a load in a normal operating range. hand,
Electric double-layer capacitor batteries have a great advantage over chemical batteries that they can store large amounts of energy. However, the electric double-layer capacitor battery requires a large amount of stored power and attempts to use it effectively.
= For CV ^2/2 of the terminal voltage based on the relationship has a characteristic that varies greatly, the terminal voltage by the stored amount of energy due to discharge is largely changed from the full-charge voltage to zero, stable rated load ECS to supply voltage
Therefore, a large adjustment of the output voltage is required.

[0003] ECS is a power energy storage system comprising a capacitor, a parallel monitor and a current pump.
3, Denki Kagaku B, Vol. 115, No. 5, 1995, p.
10 etc.). Here, the parallel monitor is
In this device, a plurality of capacitors are connected between terminals of each capacitor of a capacitor bank connected in series and parallel, and a charging current is bypassed when a charging voltage of the capacitor bank exceeds a set value of a parallel monitor.

[0004] The capacitor bank having the parallel monitor bypasses the charging current so as to prevent the charging voltage of the capacitor bank from rising above a set value when charging, so that all capacitors in the capacitor bank are kept constant. The capacitor is charged evenly to the set voltage, and the storage capacity of the capacitor can be exerted almost 100%. Therefore, even if there are variations in the characteristics of the capacitors and the magnitude of the residual charge, the parallel monitor performs equalization of the maximum voltage, prevention of backflow, detection and control of the charge termination voltage, etc. As a thing,
It has an extremely important role and is an indispensable device for effective use of energy density.

FIG. 13 is a diagram showing an example of a standard configuration of an ECS, and FIG. 14 is a diagram showing a step-up / step-down operation region of an ECS current pump. In the power storage device using ECS, FIG.
From the electric double-layer capacitor that stores power as shown in
Electric power is taken out by a switching type DC / DC converter called a current pump, and a constant voltage is supplied to a load. The current pump used at this time may be a step-down chopper, a step-up chopper, or another DC / DC converter, but a type using a transformer is not advantageous because high efficiency is an essential condition.

Now, in an ECS-based 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 V _O is selected to be equal to the voltage V _O ^* 4 at the time of full charge, and as shown in up of FIG. 14, the voltage is boosted by the converter and the output always becomes V _O ^* 4. Control may be performed as follows.
At this time, the operation range of the boost converter is boosted from 1 to 4 times. In a step-down converter, the output voltage V
_O is selected to be equal to 1/4 of the voltage V _O ^* 1 at the time of full charge, and as shown in down of FIG. 14, the voltage is reduced to 1/4 at the start of discharge by the converter, and the step-down ratio is reduced in accordance with the discharge and output. Is controlled to always be V _O ^* 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 1 /
The pressure drops from 4 to 1.

In the case of a power supply such as a capacitor battery whose voltage fluctuates greatly (decreases) as energy is extracted as described above, in the case of a circuit for stabilizing the output voltage with a step-down converter, the number of rated output voltages is reduced. In order to use 94% of energy, for example, the rated output voltage is 1
In the case of 2V, a battery voltage of about 48V, which is four times that of the battery voltage, is required, and a rated output voltage of 12V must be stably taken out by a step-down converter using such a battery voltage as input. The operation for this is as follows. When the battery voltage in the first fully charged state is 48 V, the voltage is reduced to 1/4 and taken out to 12 V, but as the battery voltage gradually decreases, the battery voltage becomes 24 V When it decreases to 1/2,
At 12V, the step-down ratio is changed to 1/1, and the output voltage is stabilized at 12V by such a change in the step-down ratio.

[0008] Therefore, in the case of a circuit for stabilizing the output voltage by a step-down converter, a battery voltage three to four times the rated output voltage, which far exceeds the voltage value actually used, is required. There was a problem and it was not so good. For example, 80 for an electric vehicle operating at 200V
A 0V battery is required, but at this voltage, the degree of freedom of the semiconductor used is reduced, and it is necessary not only to provide sufficient insulation creepage to prevent electric shock, but also to use special insulating materials. become. Therefore, it is desired to lower the voltage of the battery not only from the viewpoint of safety but also from the viewpoint of economy.

When 94% energy is used by a circuit for stabilizing an output voltage in a boost converter, the output voltage is used from 12 V to about 1/4 of about 3 V. The operation is the same. In the first fully charged state, when the battery voltage is 12 V, the boost ratio is 1 and the output is performed as it is. However, as the battery voltage decreases, the boost ratio is changed, and when the battery voltage becomes 6 V, the boost ratio becomes 2 When the battery voltage finally becomes 3V, the boosting ratio must be increased to 4 so that 12V is supplied stably.

Therefore, in the case of a circuit for stabilizing the output voltage by a boost converter, not only the conversion efficiency is generally inferior to that of a step-down converter, but also if the energy use efficiency of the battery is 94%, the boost ratio becomes 3 to 3. The efficiency is further reduced by four times. Even for a boost converter, it is not preferable to design a power having such a large boost ratio, and a boost ratio of about twice is desired as the most efficient use method.

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 to avoid an electric shock accident. However, if the voltage is lowered where a certain amount of power is required,
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 that uses the above voltage range, it is necessary to mount a capacitor that fully charges 1200V, which is four times that of the above, and a 1/4 step-down converter. And may increase safety costs. On the other hand, when fully charging 300 V, it is necessary to use a quadruple boost converter or conversely use a step-down converter to lower the output voltage to 75 V.

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 switching semiconductor elements. Even with the boost type, boosting 4 times not only reduces the efficiency,
Production of the boost choke coil also becomes difficult.

[0014]

Therefore, as a power supply device using a large voltage fluctuation, for example, an electric double layer capacitor, in which the voltage gradually decreases as energy is extracted from a fully charged state, the power supply side voltage is made constant. To achieve this, a configuration in which the series / parallel switching of the battery is performed has already been proposed (see Japanese Patent Application Laid-Open No. 8-168182). This is because a plurality of batteries having large voltage fluctuations, switching means for switching the batteries from parallel connection to series, and a voltage or current supplied to the load by the switching means using the batteries connected in parallel and series switching by the switching means as a power source. And a switching means for switching the battery from a parallel connection to a series connection as the voltage drops. The switching means has, for example, first to third changeover switches using a semiconductor element, and connects a series circuit of a battery and a second changeover switch and a series circuit of the third changeover switch and the battery in parallel. The first switch is connected between the series connection points of the respective series circuits, and the second and third switches are operated complementarily to the first switch.

According to the conventional apparatus proposed above, the step-down ratio and the step-up ratio can be reduced by using a step-down converter or a step-up converter as the control means. Efficiency can be improved, and moreover, the degree of freedom in selecting a semiconductor to be used and the degree of freedom in design can be increased, so that the economical efficiency of the device can be improved. However, even in the conventional device proposed above, the output voltage is doubled at the moment of switching from parallel connection to series connection, so that the voltage is 1/2 of the full charge voltage, that is, 50% of the full charge voltage. There is a problem that the fluctuation width cannot be further reduced.

[0016]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. The present invention solves the above-mentioned problem by charging and storing energy like a capacitor, and taking out the stored energy. An object of the present invention is to suppress a fluctuation range of a voltage of a power supply device using a battery having a large voltage fluctuation which gradually changes.

For this purpose, the present invention relates to a power supply device using a battery having a large voltage fluctuation in which energy is charged and stored, and the voltage gradually changes in accordance with the charge / discharge amount as the stored energy is taken out. The big one
A battery unit is configured by a pair of batteries and a switching unit that switches the pair of batteries between parallel connection and series connection, and the battery units are connected in series in a plurality of stages,
The switching unit is controlled in a stepwise manner with respect to the plurality of battery units in accordance with a decrease in voltage, so that the pair of batteries is switched from parallel connection to series connection, Further, the battery having a large voltage fluctuation is an electric double layer capacitor bank in which a plurality of capacitors are connected in series and parallel for power storage, and the switching means has a current limiting circuit, and is used when the battery unit is charged. The switching is performed reversibly with the discharging.

[0018]

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 switching type power supply device according to the present invention, and FIG. 2 is a diagram for explaining an operation range. In the figure, 1 to n indicate series-parallel switching type capacitor units, C11 to Cn2 indicate capacitor banks, S11 to Sn3 indicate changeover switches, and V _O indicates an output voltage.

In FIG. 1, each of the series-parallel switching capacitor units 1 to n includes a pair of capacitor banks and a switch for switching between parallel connection and series connection.
These are cascaded over a plurality of stages to form a capacitor power storage device. For example, the series-parallel switching capacitor unit 1 includes a pair of capacitor banks C11 and C12.
Respectively, a first changeover switch S11 and a second changeover switch S12 are connected in series on opposite polarities, respectively, and the series connection circuits are connected in parallel, and a third switch is connected between the connection points of the series connection circuits. The switch S13 is connected. When the first switch S11 and the second switch S12 are turned on by operating the third switch S13 complementarily to the first switch S11 and the second switch S12. When the third switch S13 is turned off to connect a pair of capacitor banks C11 and C12 in parallel, and the third switch S13 is turned on, the first switch S11 and the second switch S12 are turned on. Is turned off, and a pair of capacitor banks C11 and C12 are connected in series. The series-parallel switching type capacitor units 2 to n also have the same configuration as the series-parallel switching type capacitor unit 1, and the series-parallel switching type capacitor units 1, 2,..., N are connected in series, and an output voltage V _O is obtained. . The capacitor banks C11 to Cn2 are formed by connecting a plurality of electric double layer capacitors having, for example, a parallel monitor in series / parallel.

The parallel monitor has, for example, a semiconductor control element for bypassing the charging current as already known from the above-mentioned literatures and applications, and when the charging voltage exceeds the set value by the control thereof, the set value is set. This is a device that turns on and short-circuits the electric double-layer capacitor when the electric double-layer capacitor connected in parallel fails and becomes abnormally charged. A semiconductor rectifier connected in parallel to the electric double layer capacitor in reverse polarity, a semiconductor control element connected in parallel to the electric double layer capacitor to bypass the charging current, and a monitor control circuit controlling the semiconductor control element. Become.

In the series-parallel switching type power supply according to the present invention configured as described above, first, when each of the capacitor banks C11 to Cn2 having the same rated voltage and capacity is fully charged, FIG. As shown, each of the series / parallel switching type capacitor units 1 to n includes first switching switches S11 and S11.
21,..., Sn1, a second changeover switch S12,
, Sn2 are on, and the third changeover switches S13, S23, ..., Sn3 are off. That is, all the series-parallel switching type capacitor units 1 to n
Are connected in parallel.

Next, each capacitor bank C1 is discharged by discharging.
When the charging voltage of the first to the parallel-connected capacitor unit 1 decreases as the output voltage V _O decreases at least to the voltage of one of the capacitor banks C11 to Cn2, as shown in FIG. Only the first switch S11 and the second switch S12 are turned off, and the third switch S13 is turned on. As a result, only the first series-parallel switching capacitor unit 1 becomes a series connection circuit of the capacitor banks C11 and C12, and the charged voltage of the capacitor bank C11 increases as a whole.

Further, each capacitor bank C is discharged by discharging.
11 to Cn2, the output voltage V _O decreases at least in parallel with the capacitor banks C21 to C21.
When the voltage of one Cn2 is reached, as shown in FIG. 1C, the second series-parallel switching capacitor unit 2 switches the first switching switch S21 and the second switching switch S22.
Is turned off, and the third switch S23 is turned on.
As a result, the second series-parallel switching capacitor unit 2 is connected to the first series-parallel switching capacitor unit 2.
Is a series connection circuit of the capacitor banks C21 and C22, and the charged voltage of the capacitor bank C21 increases as a whole.

Similarly, each time the discharging lowers the charging voltage of each of the capacitor banks C11 to Cn2 and the output voltage V _O decreases by at least one voltage of the capacitor banks connected in parallel, the capacitor banks are connected in parallel. The number of series-parallel switching capacitor units that switch from connection to series connection is gradually increased. FIG. 2 shows a state of voltage fluctuation due to such multi-stage switching. Thus, the output voltage V _O will vary within the range of V _U ~V _L as shown in FIG.

Here, the upper limit value V _U of the fluctuating voltage is determined from the full charge voltage V _CF of the capacitor banks C 11 to Cn 2 and the number n of stages of the series-parallel switching type capacitor units 1 to n as V _U = It can be obtained by V _CF × n. Also, the lower limit value _VL of the fluctuating voltage is such that only the first series / parallel switching type capacitor unit 1
The output voltage when it becomes 11 and the series connection circuit of the C12 is V _U from _{V L, V L = V U} -V U / (n +
It can be obtained in 1). That is, the fluctuation width (V _U -V _L ) of the output voltage V _O can be suppressed to 1 / (n + 1). For example, if the number of stages n is 4, the fluctuation width is 20%.

FIG. 3 is a diagram showing a configuration example of a four-stage switching circuit of a series-parallel switching type power supply according to the present invention, and FIG. 4 is a diagram for explaining an operation comparison example between a conventional capacitor power supply and the present invention. FIG. For example, as shown in FIG. 3, assuming that the number n of stages of the series-parallel switching type capacitor unit is 4 and the full charge voltage V _CF of each capacitor bank is 30 V as shown in FIG. next the voltage variation of the upper limit V _U of 120V, the lower limit value V _L of the voltage fluctuation becomes lower 96V by a voltage corresponding to the 1/5. Therefore, in the conventional device, 120 V and its 1
However, in the present invention, the range of fluctuation between 120 V and 96 V, that is, 20%, can be suppressed. Actually, in the series-parallel switching of the first series-parallel switching capacitor unit 1, there is a fluctuation of 24 V, but in the second series-parallel switching capacitor unit 2 and thereafter, each capacitor bank is further discharged. Therefore, the fluctuation width gradually decreases as shown in FIG. In FIG. 4, 0 is a device without serial-parallel switching, 1 is a device that performs conventional serial-parallel switching, and 4 is a comparison of voltage fluctuations of a device that performs four-stage switching of the series-parallel switching capacitor unit according to the present invention. An example is shown.

As shown in FIG. 3, each of the series-parallel switching type capacitor units has comparators A1 to A31.
Is connected to detect the switching voltage, the setting of the switching voltage of each of the comparators A1 to A31 is, for example, 24.2 V for the first stage, 21.3 V for the second stage, and 1 for the third stage.
9.5V, and the fourth stage becomes 13.2V. In this way, even if each capacitor bank is fully charged evenly, the state of charge of each stage of the capacitor bank becomes uneven with the discharge. Serial-parallel switching may be performed. In other words, each stage may be operated reversibly by charging and discharging. When performing reversible charging, when switching from series to parallel,
If there is a voltage difference between the capacitor banks, a large short-circuit current flows based on the voltage difference. In order to avoid such a transient large current flow,
A current limiting circuit used in a constant voltage power supply is connected to all switches using ET. This is a simple circuit using a current detection unit and a transistor.

Next, an example of the configuration of a series-parallel switching circuit for controlling the changeover switch of the series-parallel switching type power supply according to the present invention will be described. FIG. 5 is a diagram illustrating a configuration example of a series-parallel switching circuit, FIG. 6 is a diagram illustrating another configuration example of a series-parallel switching circuit, 11, 22 and 27 are comparators, and 12-1 to 12-12.
-N is an AND gate, 13-1 to 13-n are switching controllers, 21 and 26 are subtraction circuits, V _REF is a reference voltage, V _O is an output voltage, and V _Cn is a capacitor bank voltage.

In the above embodiment, the switching voltage is detected by the comparator for each capacitor unit as the voltage drops due to the discharge, and the connection of the capacitor banks is switched from parallel to series, but the output voltage V _O is detected. Then, the switching voltage can be determined. FIG. 5 shows an example of this case. In this case, the comparator 11 compares the output voltage V _O with the reference voltage V _REF, and sequentially switches the capacitor banks from parallel to series. That is, in the circuit shown in FIG. 5, first, the reference voltage V _REF is set to the lower limit value _VL of the fluctuating voltage shown in FIG. 2, and in the comparator 11, the output voltage V _O becomes the reference voltage V _REF , that is, When the voltage becomes lower than the lower limit value V _L , a switching signal (for example, logic “1”)
Is output. The AND gate 12-1 and the switching controller 13-1 constitute a circuit for controlling switching of the first stage capacitor unit 1, and the AND gate 12-2 and the switching controller 13-2 constitute a second stage. A circuit for controlling the switching of the capacitor unit 2 of the AND gate 12-3
And the switching controller 13-3 are circuits for controlling switching of the third-stage capacitor unit 3..., And the AND gate 12-n and the switching controller 13-n are , Respectively. And gates 12-1 to 12-n
Is a switching control signal of the previous-stage capacitor unit and a switching signal of the comparator 11 as input signals, provided that the previous-stage capacitor unit is switched to a series connection and that the output voltage is smaller than the reference voltage. The output signal becomes logic "1", and operates the switching controller of the capacitor unit. The switching controllers 13-1 to 13-n operate according to output signals when the logical conditions of the AND gates 12-1 to 12-n are satisfied, and switch the connection of the capacitor banks of the capacitor units from parallel to series.

[0030] The above example using the lower limit value V _L of the voltage that varies as a switching voltage to the example shown in FIG. 6 (A),
It is an upper limit value V _U of the voltage varying switching voltages. In this case, in FIG.
Subtracts the output voltage V _O from the reference voltage V _REF , and the comparator 22 compares the subtracted value with the capacitor bank voltage V _Cn of the last-stage capacitor unit. Here, the reference voltage V _REF is set to the upper limit value V _U , and the output voltage V _O is the capacitor bank voltage V of the last stage capacitor unit.
_The switching signal is output from the comparator 22 when the voltage falls below _Cn . That is, the capacitor bank voltage V _Cn of the last stage capacitor unit is used as a representative value of the capacitor bank voltage of the capacitor units connected in parallel among the capacitor units.

In the example shown in FIG. 6B, the switching voltage is controlled so that the average value of the fluctuating voltage becomes constant. Therefore, in FIG. 6 (B), the subtraction circuit 26 subtracts the output voltage V _O from the reference voltage V _REF , and the comparator 27 calculates the difference between the subtracted value and the capacitor bank voltage V _Cn of the last stage capacitor unit. / 2 value. Then, the reference voltage V _REF is a value between the upper limit V _U and the lower limit value V _L, the average value of the voltage that is variation V _M =
(V _U + V _L ) / 2. By doing so, when the output voltage V _O falls below the average value V _M by V _Cn / 2 or more, the connection of the capacitor unit is switched from parallel to series, so that the output voltage V _O immediately after that is conversely V _Cn / 2
growing.

By increasing the number of stages of the capacitor unit as described above, the fluctuation range of the output voltage is reduced, so that a power supply device having a voltage stability of ± 10% or less, comparable to a battery, can be realized. And with high efficiency,
It can be realized without requiring a large choke coil or high-voltage, large-current, high-speed switch. Of course, the output voltage may be further stabilized by using a step-down chopper circuit or a step-up chopper circuit as in the conventional device. Next, stabilization of the output voltage will be specifically described with reference to a configuration example of one capacitor unit.

FIG. 7 is a diagram showing a configuration example of an output voltage stabilizing circuit, and FIG. 8 is a diagram for explaining an operation range.
Is a step-down chopper circuit, 32 is a step-up chopper circuit, 34 is a comparator, 35 is a step-down chopper control circuit, 36 is a step-up chopper control circuit, 37 is an inverter, 38 is an error amplifier,
D _D and D _U are unidirectional rectifiers, CH _D and CH _U are chopper switching elements, L is a choke coil, and V _rO is a reference voltage.

In FIG. 7, the choke coil L is shared by the step-down chopper circuit 31 and the step-up chopper circuit 32. The step-down chopper circuit 31 and the step-up chopper circuit 32 operate the chopper in the middle of the fluctuation range of the power supply voltage. Are switched from the step-down chopper circuit 31 to the step-up chopper circuit 32. During operation of the step-down chopper circuit 31, chopper switching element CH _U of the step-up chopper circuit 32 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. When the boost chopper circuit 32 operates, the chopper switching element CH _D
There while still turned on, chopper switching element CH _U is boosted by ON / OFF, adjust the output voltage to the rated voltage of the load.

The reference voltage V _rO corresponds to the rated voltage supplied to the load of the power storage device, and is used as a reference voltage for detecting an error in the chopper control, and at the same time, for switching between the step-down chopper control and the step-up chopper control. And an intermediate value in the fluctuation range of the power supply voltage is set. For example, the variation range of the power supply voltage is 120 V to 96
V and the rated voltage of the load is 108 V, the upper limit of 12
The region from 0 V to 108 V is controlled by the step-down chopper circuit, and the region from 108 V to the lower limit of 96 V is controlled by the step-up chopper circuit to supply the rated voltage of 108 V.

The comparator 34 compares the terminal voltage and the reference voltage V _{and rO} power storage unit, when the terminal voltage of the power storage unit is greater than the reference voltage V _{and rO} is the output signal active (logic "1 )), _And becomes smaller than the reference voltage V _rO ,
The output signal is made non-active (logic "0"), and the inverter 37 inverts the output signal of the comparator 34. The error amplifier 38 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 35 and the step-up chopper control circuit 36. Is done.

The step-down chopper control circuit 35 includes a comparator 34
Operates on the condition that the output signal of
The chopper switching element CH _D based on the error amplification signal of the error amplifier 38 turns on / off control, to stop the operation and the output signal of the comparator 34 becomes non-active, turns on the chopper switching element CH _D, unidirectional a rectifying element D _D is to the oFF state.

The step-up chopper control circuit 36 stops the operation on condition that the output signal of the comparator 34 is active by inputting the output signal of the comparator 34 through the inverter 37, and the chopper switching element C
H _U is turned off, and the operation is performed when the output signal of the comparator 34 becomes non-active, and on / off control of the chopper switching element CH _U is performed based on the error amplification signal of the error amplifier 38.

Next, the overall operation will be described. Now, when the capacitor bank of each capacitor unit is in a fully charged state, that is, when the amount of discharged power in FIG. 8 (shown in the example of one capacitor unit) is 0%, the output signal of the comparator 34 becomes active. Therefore, the step-down chopper control circuit 35 operates and the step-up chopper control circuit 36 stops operating. Therefore, the voltage of the power storage unit is _reduced to _VrO by the step-down chopper circuit 31, and is supplied to the load. As shown in FIG. 8, as the amount of discharged power increases, the voltage of the power storage unit decreases, and when the voltage becomes equal to the rated voltage of the load, the output signal of the comparator 34 becomes inactive. The operation is stopped, and the boost chopper control circuit 36 starts operating. Further, when the amount of discharged power increases and the voltage of the power storage unit decreases to the lower limit, the switch of the capacitor unit is operated to switch the capacitor bank from parallel connection to series connection as described above, so that the power storage unit Voltage rises to almost the initial voltage. Therefore, the output signal of comparator 34 becomes active again, so that boost chopper control circuit 3
6 stops operating, and the step-down chopper control circuit 35 starts operating. In this way, it is possible to switch the capacitor bank of the last-stage capacitor unit of the power storage unit from parallel connection to series connection, and to supply power to the load at the rated voltage until the voltage drops below a predetermined voltage.

It is to be noted that the fluctuation range of the power supply voltage is 120 V to 9
In the case of 6 V, the rated voltage of the load is set to the intermediate value of 108 V. However, the rated voltage of the load may be set to 100 V or 105 V, and it is needless to say that the rated voltage of the load can be arbitrarily set within a fluctuation range. . In this case, if the voltage at full charge and the rated voltage of the load are the same, only the boost chopper circuit is used.If the lower limit of the fluctuation range and the rated voltage of the load are the same, It consists only of a chopper circuit. FIG. 9 is a diagram showing respective control regions when configured with either a step-up chopper circuit or a step-down chopper circuit. Also, whether the end point of the discharge and the lower limit value V _L, or 50% of the voltage of the upper limit value V _U, is either free appropriately set to any level, the boost chopper circuit accordingly, the step-down chopper circuit The operation range is set.

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,
It may be combined with an AC / DC conversion circuit such as a three-phase or six-phase polyphase bridge inverter or the like, and a reversible power storage device may be realized using the combination.

FIG. 10 is a diagram showing a configuration example of a single-phase bridge inverter, FIG. 11 is a diagram showing a configuration example of a reversible power storage device, and FIG. 12 is a diagram showing a modified example of a converted waveform in the case of pulse width modulation. is there. Using the single-phase bridge inverter shown in FIG. 10A, a PWM as shown in FIG.
When converting from DC to sine wave AC by (pulse width modulation), a considerably deep pulse width modulation is required in the process to obtain a sine wave with few harmonics. Most large inverters for power use have input fluctuation specifications within ± 20%. If the DC input voltage fluctuates significantly, 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 state where the operation is performed, and the design becomes difficult. However, if the power storage device is configured to switch the capacitor bank in series / parallel as described above, the voltage fluctuation width can be suppressed, and further,
By combining the above choppers, the input fluctuation width can be suppressed to a small value. Therefore, a reversible power storage device can be realized by replacing a unidirectional rectifier with a bidirectional switching element and connecting a PWM inverter as shown in FIG. Moreover, PWM
The parts can be made much easier, with a stable and efficient design. In this case, by controlling the inverter in the reverse direction, the capacitor can be treated as a constant current charger, and the same device can be used also as the charger.
Further, 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 square wave shown in FIG. Such a modified rectangular wave can also be adopted.

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, a configuration using units having the same rated voltage and capacity and an electric double layer capacitor bank has been described.
Units having different rated voltages and capacities may be combined. For example, a unit having a higher rated voltage or a smaller capacity may be used for a unit at a subsequent stage than a unit at a stage before performing serial-parallel switching. Further, not only one unit for performing the serial / parallel switching, but also a plurality of units may be grouped with a decrease in voltage, and the number thereof may be changed stepwise, or these may be combined. Further, as described above, the voltage fluctuation width changes according to the control stage of the unit that switches from parallel to series, and gradually decreases, so that the reference voltage V shown in FIGS.
_REF may be changed. The series-parallel switching power supply device using the electric double layer capacitor bank as the series-parallel switching capacitor unit has been described. However, as the energy is charged and stored, and the stored energy is taken out, the voltage is gradually increased according to the charge / discharge amount. The present invention can be similarly applied to power storage means such as another capacitor and a secondary battery as long as the battery has a large voltage change that changes.

[0044]

As is apparent from the above description, according to the present invention, a plurality of capacitor units for switching and connecting a pair of capacitor banks in series from parallel to series are connected in series to reduce the voltage accompanying discharge. Therefore, since the capacitor units are switched from parallel to series in a stepwise manner, the fluctuation range of the voltage can be suppressed according to the number of stages of the capacitor units. Therefore, the size of the converter can be reduced even when a chopper-type switching converter is used to suppress the voltage fluctuation width in large-scale electric energy storage, electric buses, trucks, and the like.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating an operation range.

FIG. 3 is a diagram illustrating a configuration example of a four-stage switching circuit of the series-parallel switching power supply device according to the present invention.

FIG. 4 is a diagram for explaining an operation comparison example between a conventional capacitor power supply device and the present invention.

FIG. 5 is a diagram illustrating a configuration example of a series-parallel switching circuit.

FIG. 6 is a diagram illustrating another configuration example of the series-parallel switching circuit.

FIG. 7 is a diagram illustrating a configuration example of an output voltage stabilizing circuit;

FIG. 8 is a diagram illustrating an operation range.

FIG. 9 is a diagram showing respective control regions when configured with a step-up chopper circuit or a step-down chopper circuit.

FIG. 10 is a diagram illustrating a configuration example of a single-phase bridge inverter.

FIG. 11 is a diagram illustrating a configuration example of a reversible power storage device.

FIG. 12 is a diagram showing a modified example of a converted waveform in the case of pulse width modulation.

FIG. 13 is a diagram illustrating a standard configuration example of an ECS.

FIG. 14 is a diagram showing a step-up / step-down operation region of the ECS current pump.

[Explanation of symbols]

1 to n: series-parallel switching capacitor unit, C11 to C
n2: capacitor bank, S11 to Sn3: switch, V _O : output voltage

Claims (3)

[Claims] 1. A power supply device using a battery having a large voltage fluctuation in which a voltage gradually changes in accordance with a charge / discharge amount as energy is charged and stored, and the stored energy is taken out. And a switching means for switching the pair of batteries between a parallel connection and a series connection to form a battery unit, wherein the battery units are connected in series in a plurality of stages, and the plurality of batteries are connected in accordance with a decrease in voltage. A series-parallel switching type power supply device, wherein the switching means is controlled stepwise with respect to a unit to switch the pair of batteries from parallel connection to series connection. 2. The battery according to claim 1, wherein the battery having a large voltage fluctuation is an electric double layer capacitor bank in which a plurality of capacitors are connected in series and parallel for power storage.
A series-parallel switching type power supply device as described in the above. 3. The series-parallel switching type according to claim 1, wherein said switching means has a current limiting circuit, and is configured so that switching at the time of charging the battery unit is reversibly performed at the time of discharging. Power supply.