JPH11346436A - Power supply unit with connection bank number control - Google Patents

Abstract

(57) [Problem] To control connection of a capacitor with a small number of switches to reduce the cost of the device and improve the reliability. SOLUTION: In a power supply device for storing electric energy in a capacitor bank and supplying power to a load, an output capacitor bank C1 charged and discharged within a rated voltage range of the load.
To C3, adjustment capacitor banks C4 and C5 charged and discharged within the allowable range of the load voltage fluctuation, and adjustment capacitor banks C to output capacitor banks C1 to C3.
4, switching means S1 to S3 for connecting or disconnecting C5 in series, and control means A1 for controlling the switching means by detecting the charging / discharging state of the output capacitor banks C1 to C3. By connecting or disconnecting the adjusting capacitor bank in series to or from the adjusting capacitor bank, a power source with little fluctuation in which the output voltage is adjusted to the allowable range of the load voltage fluctuation is obtained.

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 for storing electric energy by a capacitor bank and supplying power to a load.

[0002]

2. Description of the Related Art An electric double-layer capacitor can be rapidly charged by physical charging like other capacitors, compared with a chemical battery which takes a long time to charge such as a lead battery or a nickel-cadmium battery. . In addition, the electric double layer capacitor battery has a great advantage over a chemical battery in that it can store a large amount of energy. However, if an attempt is made to effectively use it by increasing the amount of stored power, Q
= Has the characteristic that the terminal voltage varies greatly based on the relation of CV ^2/2. Power storage devices based on ECS (Energy Capacitor System) that use electric double-layer capacitors can increase the amount of power stored in electric double-layer capacitors and use them effectively. It is drawing attention as a power storage device.

[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. Therefore, as a capacitor bank that can be used to the full withstand voltage,
The parallel monitor plays an extremely important role and is an indispensable device for effective use of energy density. By connecting the parallel monitor, even when the characteristics of the capacitors vary and the amount of residual charge is large, equalization of the maximum voltage, prevention of backflow, detection and control of the charge termination voltage, and the like can be performed. Therefore, all the capacitors in the capacitor bank are charged evenly to the set voltage, and the storage capacity of the capacitors can be exerted almost 100%.

However, in a power supply device using a battery having a large voltage fluctuation, such as an electric double layer capacitor, whose voltage greatly decreases as energy is extracted from a fully charged state, in order to make effective use of the storage capacity, the power supply side voltage is reduced. It is essential to achieve a constant voltage. To this end, a power supply device has been proposed (see Japanese Patent Application Laid-Open No. 8-168182) in which the series-parallel switching of batteries is performed to reduce the fluctuation range of the voltage. FIG. 7 is a diagram showing an example of the configuration of a power supply device that performs series-parallel switching of a capacitor battery, in which the capacitor battery is switched from parallel connection to series connection as the voltage decreases. In such a power supply device, for example, a series / parallel switching circuit of the capacitor batteries C1 and C2 shown in FIG. 7A is cascaded in more stages as shown in FIG. By performing the switching control, the fluctuation range of the voltage can be reduced in accordance with the number of stages.

[0005]

However, in order to reduce the fluctuation range of the voltage as described above, the number of stages for switching from parallel connection to series connection increases, and as the number of stages increases, the number of changeover switches Sp1 increases. , Sp
2, Ss1 to Sp31, Sp32, and Ss31 are required. That is, as is apparent from FIG.
Since three changeover switches Sp1, Sp2, and Ss1 are used, three times the number of changeover switches is required.

In addition, since these changeover switches are used for a power supply, power semiconductors such as a large electromagnetic contactor, a giant transistor, an IGBT, a GTO, and a thyristor are used. Therefore, the number of components including the drive circuit of the changeover switch and the heat sink is increased, and it is necessary to secure a large space for mounting. As a result, the cost of the device is increased, and there is a problem in reliability.

Further, when switching from the parallel connection to the series connection, if the voltages of the capacitor batteries C1 and C2 are not uniform, a large cross current flows between the capacitor batteries C1 and C2. Protection circuit A for preventing such cross current as shown in C).
1, A2, and switching elements Q1 to Q corresponding thereto
3 is required.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and aims at controlling the connection of a capacitor with a small number of switches to reduce the cost of the device and improve the reliability. .

Therefore, the present invention provides a power supply device for storing electric energy by a capacitor bank and supplying power to a load, wherein a plurality of capacitor banks are connected in series,
The number of the capacitor banks connected in series is controlled according to the charging / discharging state, so that the output voltage is adjusted to be within the allowable range of the load voltage.

Further, an output capacitor bank charged / discharged within a range of a rated voltage of a load, an adjustment capacitor bank charged / discharged within a permissible variation range of a load voltage, and the output capacitor bank include: Adjustment capacitor
Switching means for connecting or disconnecting the banks in series, and control means for controlling the switching means by detecting a charge / discharge state of the output capacitor bank, wherein the output capacitor bank includes By connecting or disconnecting the adjusting capacitor banks in series, the output voltage is adjusted to be within the allowable range of the variation of the load voltage.

Further, the output capacitor bank includes:
A series connection of multiple capacitor banks,
The adjusting capacitor bank includes a plurality of capacitor banks.
A plurality of capacitor banks, wherein the control unit performs stepwise connection or disconnection of the plurality of capacitor banks in accordance with the state of charge, and the control unit controls a voltage between terminals of the output capacitor bank. The charge / discharge state is measured to measure the voltage between the terminals of the output capacitor bank, the remaining energy is calculated, and the remaining amount is displayed.

[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 connection bank number control type power supply device according to the present invention.
C5 is a capacitor bank, S1 to S3 are switches, A
Reference numeral 1 denotes a control circuit, 1 denotes a charger, 2 denotes an output control circuit, and 3 denotes a load.

In FIG. 1, capacitor banks C1 to C1
C5 is used for storing electric energy, for example, by using a plurality of capacitors (single cells) such as an electric double layer capacitor and connecting them in series or further in parallel. Is connected to a parallel monitor. Among these, the capacitor banks C1 to C3 are output capacitor banks that are charged and discharged in the range of the rated voltage of the load, and the capacitor banks C4 and C5 are charged and discharged in the allowable range of the load voltage. Adjustment capacitor bank. The switches S1 to S3 are used in addition to the output capacitor banks C1 to C3 connected in series to connect the adjustment capacitor banks C4 and C5 in series in a stepwise manner or to disconnect the connection. .

The control circuit A1 controls the charge / discharge state (voltage) of the output capacitor banks C1 to C3 connected in series.
And switches S1 to S3 according to the charging / discharging state.
To perform connection or disconnection of the adjustment capacitor banks C4 and C5. Therefore, by turning on only one of the switches S1 to S3 at all times by the control circuit A1, the series connection of the capacitor banks C1 to C3 to the capacitor bank C4 and further to the series connection including the capacitor C5 is added. Until the state
The number of banks connected in series is switched stepwise. Therefore, the control circuit A1 switches between the three connection states, so that two detection levels E ₁ and E ₂ (for example, E ₁ <
E ₂ ).

The charger 1 charges the capacitor banks C1 to C5 connected in series from a power supply at a constant current, and disconnects the capacitor banks C4 and C5 in a stepwise manner. The series circuit of C1 to C3 is charged up to the rated voltage and charging is completed. The output control circuit 2 controls and regulates a current supplied from the capacitor banks C1 to C5 to the load 3 as in a known current pump, or a capacitor as a current source (charger) from the load 3 in reverse. Charging the banks C1 to C5,
That is, switching is performed in the case of regenerative braking in which the load 3 is a generator. Therefore, as the output control circuit 2, an electronic switch, a step-down chopper, a step-up chopper, or another DC / DC converter is used.
By controlling the connection switching of the capacitor banks C1 to C5, it is possible to omit the case where the voltage is stabilized in a range that does not need to be adjusted when viewed from the load 3, and it is a component that is particularly indispensable for the present invention. Not something. Of course,
If the voltage change range is reduced by controlling the connection switching of the capacitor banks C1 to C5, the converter can be designed with high efficiency by combining this with the converter, and a power supply with high voltage stability can be realized.

Next, a charge / discharge operation for controlling the switches S1 to S3 in accordance with the voltages of the capacitor banks C1 to C3 and switching the number of capacitor banks C1 to C5 connected in series will be described. FIG. 2 is a diagram for explaining an example of a connection control processing routine, and FIG. 3 is a diagram showing a configuration example of a control circuit.

The control circuit A1 reads the voltage V at the upper end of the capacitor bank C3, for example, as shown in FIG. 2 (step S11), and sets the preset levels E ₁ and E as the control criterion. Compare with Step ₂ (Steps S12 and S14). Then, the voltage V when the first lower than the set level E _1, turn on only the switch S3 is connected in series of the total capacitor bank C1 to C5 (step S16). Also, if the voltage V second set level E ₂ a first setting level E ₁ or below, turn on only the switch S2 is connected in series to the capacitor bank C1~C4 except capacitor bank C5 (Step S15). Then, the voltage V becomes the second set level E
If it is ₂ or more, only the switch S1 is turned on and the capacitor bank C1 is removed except for the capacitor banks C4 and C5.
To C3 in series (step S13). This will be described below in terms of the charge / discharge operation.

The charging operation will be described. The charging from the full discharge is performed by turning on only the switch S3 as shown in FIG.
Are connected in series. That is, the control circuit A1 determines that the voltage V at the upper end of the capacitor bank C3 is the first voltage.
When the not reach the set level E ₁ to turn on only the switch S3. When charging is started and the control circuit A1 detects that the charging voltage V has risen to the _first set level E1, the switch S3 is turned off and only the switch S2 is turned on as shown in FIG. 1B. As a result, the capacitor bank C5 is disconnected to connect the capacitor banks C1 to C4 in series. Further charging voltage V rises and the second setting level E ₂ reached (exceeded) the control circuit A1 that is detected, only the switch S1 turns off the switch S2 as shown in FIG. 1 (C) By turning on, the capacitor bank C4 is disconnected and the capacitor bank C4 is disconnected.
1 to C3 are connected in series. When the battery is charged up to the rated voltage, this state becomes a full charge as a system.

The discharge operation will be described. Discharging from the full charge is performed in the reverse of the charging operation by turning on only the switch S1 as shown in FIG. 1 (C) so that the three capacitor banks C1 to C3 are connected in series. Start. Discharge voltage V decreases by, when the control circuit A1 that falls below the second set level E ₂ is detected,
By turning off switch S1 and turning on only switch S2 as shown in FIG. 1B, a capacitor bank C4 is added in series. Furthermore discharge proceeds, the control that the voltage V falls below the first set level E ₁ circuit A1
Is detected, the switch S2 is turned off and only the switch S1 is turned on, as shown in FIG.
A capacitor bank C5 is also added in series. By sequentially adding the capacitor banks C4 and C5 in series in this manner, a decrease in output voltage is compensated for.

In the fully charged state of the system, FIG.
Only the switch S1 is turned on as shown in FIG.
Since the rated voltage is obtained by connecting the banks C1 to C3 in series, the voltage of the capacitor bank C4 + C5 is stacked on the rated voltage, and the maximum voltage generated inside the circuit increases accordingly. In contrast to the circuit configuration shown in FIGS. 1A to 1C, the circuit configuration shown in FIG.
Since the connection is made with the polarity subtracted from the voltage of the series circuit of 1 to C3, the maximum voltage generated inside the circuit can be suppressed low.

As described above, in the control circuit A1, the output capacitor bank C charged and discharged in the range of the rated voltage of the load.
The charge / discharge state can be detected based on the measurement of the voltage V between the terminals 1 to C3, and the remaining energy can also be obtained from the voltage V. FIG. 3 shows a configuration example of a control circuit having a circuit for displaying the remaining amount. In FIG. 3, a voltage detection circuit 11 measures a voltage V between terminals of the output capacitor banks C1 to C3. The voltage determination circuit 12 determines a voltage based on the voltage V (determines a charge / discharge state). The switch control circuit 12 determines whether the switches S1 to S3 are on or off based on the determination of the voltage determination circuit 12. The control is performed. The remaining amount calculation circuit 14 calculates the remaining amount of energy based on the voltage V.
Numeral 5 indicates the remaining energy amount calculated by the remaining amount calculation circuit 14.

An operation example from charging to discharging will be further described. FIG. 4 is a diagram showing an example of a voltage transition of each unit from a fully discharged state to a constant current charge and a constant power discharge completion. The same 1000F, 10V rated capacitor bank C1
FIG. 4 shows an example of conducting a charge / discharge test using C5 to C5.
It is. Here, the set level of the control circuit A1 is E ₁ =
18V and E ₂ = 22.5V, the charger is 30A
The voltage limit value was set to 30.5 V, and the discharge was performed at a constant power load of 500 W.

First, transition of the output voltage and the voltage of each capacitor bank from the basic full discharge state, that is, from the state where the initial voltage of each capacitor bank is zero to full charge, and from full charge to full discharge. As shown in FIG. 4, the output voltage is 1 (◇), the voltage at the upper end of the capacitor bank C3 is 2 (□), the average voltage of the capacitor banks C1 to C3 is 3 (▽), the capacitor bank C4, C5 voltage is 4
(△), 5 (○). As described above, the output voltage 1 has a minimum voltage of 22.5 V during the entire period from the point where the charging voltage of the capacitor banks C1 to C5 in the series state reaches the rated voltage to the point where the rated voltage is divided even when connected in series. , The range of fluctuation could be kept within 7.5 / 30 = 25%.

As is apparent from the voltage trace 2 at the upper end of the capacitor bank C3, the terminal voltages of the capacitor banks C1 to C3 have a fixed relationship with the remaining amount of stored energy in the system. Therefore, from the energy U is the terminal voltage V accumulated in the capacitor of the capacitance C, utilizing the principle expressed by U = CV ^2/2, capacitor bank C1~C3
By measuring the terminal voltage, the terminal voltage V can be converted to the remaining amount of stored energy, that is, the amount of stored power, using the above calculation or the square-root / square root line approximation circuit. And accurate display can be performed.

FIG. 5 and FIG. 6 are diagrams for explaining another embodiment of the power supply device of the series number control type according to the present invention. In the above embodiment, for simplicity, all capacitor banks have the same capacitance and withstand voltage. However, as is clear from traces 3, 4, and 5 shown in FIG. Fixed capacitor banks C1 to C3
, The switched capacitor banks C4, C4
5 are charged only up to 75% and 60% voltage, respectively, and therefore have low withstand voltage capacitors
Banks or capacitor banks with a small number of series connections can be used. When a bank with a small number of series connections is manufactured from a single cell having the same capacitance, the capacitance necessarily increases in proportion to the small number of series connections.

The switched capacitor bank C4,
Capacitance larger than the capacitor banks C1 to C3 fixed to C5 (C4 = 1 kF / 0.6, C5 = 1 kF / 0.
FIG. 5 shows an example of the voltage transition of each part when using (75).
FIG. 6 shows an example of the voltage transition of each part when the capacitance (C4, C5 = 1 kF × 0.8) smaller than the fixed capacitor banks C1 to C3 is used for C4 and C5. These are: □ is the voltage at the top of the capacitor bank C3;
Indicates the output voltage, ○ indicates the average voltage of the capacitor banks C1 to C3, △ indicates the voltage of the capacitor bank C4, and ▽ indicates the voltage of the capacitor bank C5.

As the capacitance of the switched capacitor banks C4 and C5 is increased or decreased, the amount of power available at a certain voltage or more, that is, the utilization factor is increased or decreased, and the fluctuation range of the voltage is changed. Therefore, the present invention is to select a design according to the purpose, such as whether the manufacturing is facilitated by using all the same capacitors, or whether the capacitance is adjusted depending on the part where the capacitance is used and the amount of stored power is effectively used. Is possible.

The present invention is not limited to the above embodiment, but can be variously modified. For example, in the above-described embodiment, three capacitor banks are connected in series, and two capacitor banks are added or disconnected stepwise in accordance with the charge / discharge state. However, the number of these is optional. It is needless to say that the combination can be adopted. For example, two capacitor banks may be connected in series and one capacitor bank may be added or disconnected in series. Generally, to reduce the variation, the unswitched capacitor banks C1-C
It is sufficient to increase the number of portions 3, that is, to increase the voltage.
This allows the voltage step to be a small percentage of the total output voltage when a switched capacitor bank is added.

[0029]

As is clear from the above description, according to the present invention, the number of capacitor banks connected in series is increased or decreased. The number can be reduced from 12 to 3 to 4 as compared with the conventional case of switching between parallel connection and series connection. Therefore, loss of the switch, mounting space, cooling of heat generation, switch driving circuit, and cost can be significantly reduced, and reliability can be significantly improved.
In addition, when switching between the conventional parallel connection and series connection, means for preventing cross current from flowing due to voltage imbalance at the time of switching to parallel connection is necessary. Since the number of connected capacitor banks is increased or decreased, such means is not required.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of a connection bank number control type power supply device according to the present invention.

FIG. 2 is a diagram for explaining an example of a connection control processing routine;

FIG. 3 is a diagram illustrating a configuration example of a control circuit.

FIG. 4 is a diagram illustrating an example of a voltage transition of each unit from a fully discharged state to a constant current charge and a constant power discharge completion.

FIG. 5 is a diagram for explaining another embodiment of the number-of-series-control power supply device according to the present invention.

FIG. 6 is a diagram for explaining another embodiment of the series number control type power supply device according to the present invention.

FIG. 7 is a diagram illustrating a configuration example of a power supply device that performs series-parallel switching of a capacitor battery.

[Explanation of symbols]

C1 to C5: capacitor bank, S1 to S3: switch, A1: control circuit, 1: charger, 2: output control circuit,
3 ... Load

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Dio Okamura 2-19-6 Minamiota-cho, Minami-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Masaaki Yamagishi 1-1-1 Fukuura, Kanazawa-ku, Yokohama-shi, Kanagawa Power System Co., Ltd.

Claims (6)

[Claims] In a power supply device for storing electric energy by a capacitor bank and supplying power to a load, a plurality of capacitor banks are connected in series, and the number of capacitor banks connected in series is determined according to a charge / discharge state. A power supply unit for controlling the number of connected banks, wherein the output voltage is adjusted to be within a permissible range of variation of the load voltage by controlling. 2. An output capacitor bank charged / discharged within a rated voltage range of a load, an adjustment capacitor bank charged / discharged within a variation range of load voltage, and an output capacitor bank. Switching means for connecting or disconnecting the adjusting capacitor bank in series, and control means for controlling the switching means by detecting a charge / discharge state of the output capacitor bank; 2. The device according to claim 1, wherein the output voltage is adjusted to a permissible range of a load voltage by connecting or disconnecting the adjusting capacitor bank in series with the bank. Power supply unit with connection bank number control. 3. The connection-bank-number-controlled power supply device according to claim 2, wherein said output capacitor bank is obtained by connecting a plurality of capacitor banks in series. 4. The adjusting capacitor bank includes a plurality of capacitor banks, and the control unit performs connection or disconnection of the plurality of capacitor banks stepwise according to the state of charge. 3. The power supply device according to claim 2, wherein the number of connection banks is controlled. 5. The power supply device according to claim 2, wherein the control means detects the charge / discharge state by measuring a voltage between terminals of the output capacitor bank. 6. The connection bank number control according to claim 5, wherein said control means measures a voltage between terminals of said output capacitor bank, calculates an energy remaining amount, and displays a remaining amount. Type power supply.