JP4079403B2 - Series-parallel switching capacitor power storage device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention controls switching of a plurality of capacitor banks with a changeover switch, and starts charging by connecting in series when charging from a fully discharged state, and connecting in parallel when the output terminal voltage reaches the full charge voltage. The present invention relates to a series-parallel switching capacitor power storage device that charges each capacitor bank until it reaches a full charge voltage.
[0002]
[Prior art]
In a power storage device that uses a capacitor bank in which a large number of large-capacity capacitors are connected in series and in parallel, charging starts with the capacitor bank connected in series, and the capacitor bank is connected in parallel as the charging voltage rises When there is a voltage difference between the banks, a large current called a cross current flows between the banks, causing failure or loss.
[0003]
FIG. 4 is a diagram showing a configuration example of a series-parallel switching circuit for capacitor banks, C1 and C2 are capacitor banks, and S1, S2a and S2b are changeover switches. In the series-parallel switching circuit for capacitor banks shown in FIG. 4 (see, for example, US Pat. No. 5,734,205, Japanese Patent Laid-Open No. 8-168182), the switch S1 is turned off, the switch S2a, By turning on S2b, discharge is started with the capacitor banks C1 and C2 connected in parallel. Then, when the voltage between the output terminals decreases with the discharge and becomes half of the time when the discharge is started, the changeover switch S1 is turned on and the changeover switches S2a and S2b are turned off. Since the capacitor banks C1 and C2 are connected in series by this switching operation, the voltage between the output terminals rises again to the voltage at the start of discharge. Therefore, the discharge can be continued until the voltage between the output terminals is reduced to ½ of that at the start of discharge. As a result, in the voltage range of 100% to 50% of the initial voltage, it is possible to use 1/4 of the total amount of electricity stored in each capacitor bank and 15/16 = 94% of the amount of electricity stored.
[0004]
[Problems to be solved by the invention]
In the capacitor bank series / parallel switching circuit, when charging is performed from the fully discharged state, only the changeover switch S1 is turned on to start charging, and the total voltage of the capacitor banks C1 and C2 reaches a predetermined full charge voltage. At the same time, the changeover switch S1 is turned off, and at the same time, the changeover switches S2a and S2b are turned on to continue charging. However, at this time, if the charging voltages of the capacitor banks C1 and C2 are not equal, there arises a problem that the charging current (cross current) flows from the higher voltage to the lower voltage. The capacitor power storage device is manufactured by removing unnecessary resistance components as much as possible in order to obtain high efficiency. Therefore, if the voltage difference between the capacitor banks C1 and C2 is large, the cross current value may damage the device.
[0005]
In order to prevent such breakage, it is necessary to incorporate a function for limiting the current into one of the changeover switches S2a and S2b or an intermediate wiring. As one of them, a power switch that can perform an analog operation, such as a MOSFET or an IGBT, is used for the changeover switches S2a and S2b. In this case, the switch can be provided with a current limiting function, and control can be performed so that the cross current does not flow because the resistance becomes high at a current larger than a set value. If the current is transient for a short time, a cross yoke can be prevented by inserting a Chiyoke coil.
[0006]
However, due to recent technological advances, the capacitance of the capacitor has become enormous and the amount of electricity stored has increased, so if you try to limit the current to the switch, the energy loss at that time can not be ignored, Trying to block the current is like installing a massive iron and copper mass.
[0007]
[Means for Solving the Problems]
The present invention solves the above-described problem, and prevents a cross current from flowing with a simple configuration, reduces loss, and maintains a safe operation.
[0008]
For this purpose, the present invention relates to a series-parallel switching capacitor power storage device configured to switch and control the series-parallel connection of a plurality of capacitor banks, and is connected in series between one capacitor bank and the other capacitor bank. A series connection switch for turning on / off current, a first parallel connection switch connected in parallel with a series circuit of the other capacitor bank and the series connection switch, and turning on / off a charge / discharge current of one capacitor bank, the one A plurality of capacitor banks that are connected in parallel with a series circuit of the capacitor bank and the series connection switch and that turn on / off the charge / discharge current of the other capacitor bank . A switch, voltage detecting means for detecting a voltage of the capacitor bank, and the voltage detecting means. And control means for determining a voltage detected by means for controlling the plurality of switches, wherein, when the charging is switched to the parallel connection of the capacitor bank connected in series to turn off the series connection switch The voltage of each capacitor bank to be switched to the parallel connection is detected and compared by the voltage detection means, and when there is a voltage difference of a predetermined value or more, only the parallel connection switch of the capacitor bank having the lower voltage is turned on. The other parallel connection switch is turned on on condition that the voltage difference becomes smaller than a predetermined value .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a series-parallel switching type capacitor power storage device according to the present invention. 1 is a voltage detection circuit, 2 is a control circuit, 4 is a PWM inverter, C1 and C2 are capacitor banks, Ss and S1p. , S2p indicates a changeover switch.
[0010]
In FIG. 1, capacitor banks C1 and C2 are banks in which one or a plurality of cells of, for example, electric double layer capacitors are connected as power storage means for charging from a charging power source and discharging to a load, and changeover switches Ss and S1p. , S2p switches the connection of the capacitor banks C1, C2 in series and parallel. The voltage detection circuit 1 detects a voltage between output terminals in which the capacitor banks C1 and C2 are connected in series and parallel, and also detects a charging voltage of each capacitor bank C1 and C2. For example, (1) and (2) The voltage applied to the changeover switch S1p (switch open voltage) Vs1p, the voltage between the capacitor bank C2 (charge level) Vc2 between (1) and (3), and the capacitor between (2) and (4) Between the voltage Vc1 of the bank C1, (3) and (4), the voltage Vs2p applied to the changeover switch S2p, and the output terminal voltage Vo is detected between (1) and (4). The control circuit 2 compares the output terminal voltage Vo detected by the voltage detection circuit 1 with the full charge voltage, compares and determines the charge voltages Vc1 and Vc2 of the capacitor banks C1 and C2, and switches the changeover switches Ss, S1p, and S2p. ON / OFF control is performed, and no cross current flows due to uneven charging levels Vc1 and Vc2 between the capacitor banks C1 and C2 based on the determination result of the charge / discharge mode and the voltage comparison determination circuit 2 at that time. Thus, the on / off timing is controlled.
[0011]
Next, serial / parallel switching control performed by the serial / parallel switching capacitor power storage device will be described in detail. When charging from the fully discharged state, as shown in FIG. 1B, the control circuit 2 first turns on only the changeover switch Ss and starts charging with the capacitor banks C1 and C2 connected in series. The voltage between the output terminals Vo is detected by the voltage detection circuit 1, the output terminal voltage Vo is compared with the full charge voltage Vf which is the reference value, and the output terminal voltage Vo reaches the predetermined full charge voltage Vf. By the way, in order to switch the connection of the capacitor banks C1 and C2 from the series to the parallel by the control circuit 2, only the changeover switch Ss is turned off. At this time, in the control circuit 2, the voltage comparison determination circuit 2 performs comparison determination of the charging voltages Vc1 and Vc2 of the capacitor banks C1 and C2, and if these voltage differences are close to zero, as shown in FIG. The switches S1p and S2p are turned on, and charging is continued in a state where the capacitor banks C1 and C2 are connected in parallel.
[0012]
However, when the capacitor banks C1 and C2 are switched from the serial connection state shown in FIG. 1B to the parallel connection state shown in FIG. 1D, the charging voltages Vc1 and Vc2 of the capacitor banks C1 and C2 are changed. If there is a voltage difference equal to or greater than a predetermined value in the comparison determination (not near zero), as shown in FIG. Continue charging with only S2p) on.
[0013]
In this state, only the capacitor bank C1 with the lower charge level is charged, so that the voltage difference between the capacitor banks C1 and C2 decreases, and if the charging is continued as it is, the voltage difference becomes zero and then reverses. . When the voltage difference is detected to be close to zero, the other changeover switch S2p (or S1p) is turned on, and the capacitor banks C1 and C2 are connected in parallel as shown in FIG. Continue charging in the state.
[0014]
FIG. 2 is a diagram for explaining another embodiment of the present invention using a multi-stage connection switching control capacitor power supply device. CA1 to CA3 and CB1 to CB3 are capacitors, SS, SA1 to SA3, and SB1 to SB3 are switches. Show. In the above embodiment, the series-parallel switching of one bank is simply described. However, the present invention can be similarly applied to a case where a plurality of banks are sequentially connected in series-parallel switching. The embodiment is shown in FIG.
[0015]
In FIG. 2, capacitors CA1 to CA3 and CB1 to CB3 are capacitors (single cells) such as electric double layer capacitors for storing electrical energy, and two sets of capacitor groups A connected in series, respectively. B is constituted. Each of the capacitors CA1 to CA3 and CB1 to CB3 may be a bank in which a plurality of capacitors are connected in series or in parallel. The switch SS is a series connection switch that connects two sets of capacitor groups A and B in series, and the switches SA1 to SA3 have a series connection point (1) between one capacitor group A and the switch SS as the other capacitor group. One switch group, switches SB1 to SB3, connected to the other end of the series connection (3) of B and the series connection point of the capacitors CB1 to CB3, are connected to the series connection point (2) of the other capacitor group B and the switch SS. Is the other switch group connecting the other end of the series connection of the capacitor group A (4) and the series connection point of the respective capacitors. Then, by turning on only the switch SS as shown in FIG. 2A, capacitors CA1 to CA3 and CB1 to CB3 are connected in series as shown in FIG. 2D, and FIG. As shown in FIG. 2E, the switch SS is turned off and the switch SA3 of one switch group and the switch SB3 of the other switch group corresponding to the switch SS are turned on. The center side connection capacitor CA3 and the center side connection capacitor CB3 of the other capacitor group B are connected in parallel. Similarly, as shown in FIG. 2C, the switch SA2 of one switch group and the switch SB2 of the other switch group corresponding to the switch SA2 are turned on, and all the other switches are turned off, so that FIG. As shown in FIG. 2, the series circuit of the center side connection capacitors CA3 and CA2 of one capacitor group A and the series circuit of the center side connection capacitors CB3 and CB2 of the other capacitor group B are connected in parallel. Further, by turning on the switch SA1 of one switch group and the switch SB1 of the other switch group corresponding to the switch SA1 and turning off all the other switches, one capacitor group A as shown in FIG. Are connected in parallel to the series circuit of the capacitors CA1 to CA3 and the series circuit of the capacitors CB1 to CB3 of the other capacitor group B.
[0016]
As described above, any one of the switches SA1 to SA3 of one switch group and the switches SB1 to SB3 or the switch SS of the other switch group on the opposite side are selectively connected, and FIG. ) To (G), the switching of the connection of the plurality of capacitors CA1 to CA3 and CB1 to CB3 is controlled, so that the voltage can be adjusted to suppress voltage fluctuations associated with charging and discharging. For example, as shown in FIG. 2D, the capacitors CA1 to CA3 and CB1 to CB3 are all connected in series to start charging, but when the terminal voltage on the charging side rises to a predetermined value, the charging is shown in FIG. By switching to the connection, the voltage of the capacitors CA3 and CB3 is reduced. When the charging-side terminal voltage rises again to a predetermined value due to charging, the charging-side terminal voltage can be suppressed so as not to rise above the predetermined value by sequentially switching to the connections shown in FIGS. 2 (F) and 2 (G). it can. In the case of switching control from these series connection to parallel connection, in the present invention, among capacitors connected in parallel, the capacitor with the lower voltage (charge level) is connected first, and charging is performed so that the charge level is higher. Waiting for equality, connect the other remaining capacitor in parallel.
[0017]
In addition, when discharging is started to supply power to the load from the connection state shown in FIG. 2G, when the output voltage drops to a predetermined value, switching to the connection shown in FIG. When the decrease is compensated and the output voltage further decreases to a predetermined value, the output voltage can be suppressed so as not to decrease below the predetermined value by switching to the connection shown in FIGS. Moreover, it is only the switch SS that connects all the capacitors CA1 to CA3 and CB1 to CB3 in series, and the other switches SA1 to SA3 and SB1 to SB3 are responsible for the total current during charging and discharging. A current capacity of 1/2 is sufficient. Furthermore, since only one switch is connected in series with the capacitor at any stage, the loss due to the on-voltage of the switch, which is a problem when a semiconductor is used as the switch, can be minimized.
[0018]
FIG. 3 is a diagram showing still another embodiment of a multi-stage connection switching control capacitor power supply device. CM, CA1 to CAn, CB1 to CBn are capacitors, SA and SB are switches, SS1, SS2, SSA1 to SSA3, and SSB1. ˜SSB3 is a control rectifier, SD1, SD2, SDA1 to SDA3, SDB1 to SDB3 are rectifiers, A1 is a control circuit, 1 is a charging circuit, 2 is an output control circuit, and 3 is a load.
[0019]
In FIG. 3A, a capacitor CM is an output main capacitor bank that is charged and discharged within the rated voltage range of the load, and the capacitors CA1 to CAn and CB1 to CBn are within the allowable fluctuation range of the load voltage. An adjustment capacitor that is charged and discharged for voltage adjustment is connected in series to the capacitor CM, and the voltage is adjusted by switching the series-parallel connection. The switches SA and SB are for switching the series-parallel connection by dividing the capacitors CA1 to CAn and CB1 to CBn connected in series to the capacitor CM into two sets of capacitor groups. When there is a voltage difference, the same control as described above is performed.
[0020]
The control circuit A1 detects the charge / discharge state (terminal voltage) in the capacitor CM and controls the switches SA and SB in accordance with the charge / discharge state to switch the series-parallel connection of the capacitors CA1 to CAn and CB1 to CBn. It is a control means. The switches SA and SB are connected to the series circuit of the capacitors CA1 to CAn of one capacitor group A and the capacitors of the other capacitor group B from the solid line position where the capacitors CA1 to CAn and CB1 to CBn are all connected in series by the control circuit A1. Switching is controlled step by step up to the dotted line position where the series circuit of CB1 to CBn is connected in parallel.
[0021]
The charging circuit 11 charges the capacitors CM, CA1 to CAn, and CB1 to CBn with a constant current from a power source, and switching of the series-parallel connection of the capacitors CA1 to CAn and CB1 to CBn connected in series to the capacitor CM is a stage. And the series circuit of the capacitors CA1 to CAn of one capacitor group A and the series circuit of the capacitors CB1 to CBn of the other capacitor group B are connected in parallel and charged to the rated voltage to complete the charging. To do. The output control circuit 12 controls and adjusts the current supplied from the capacitors CM, CA1 to CAn, and CB1 to CBn to the load 13 as in a known current pump, for example. ) To charge capacitors CM, CA1 to CAn, and CB1 to CBn, that is, to perform switching in the case of regenerative braking in which load 13 serves as a generator. Therefore, an electronic switch, a step-down chopper, a step-up chopper, and other DC / DC converters are used as the output control circuit 12, but as viewed from the load 13 by controlling connection switching of the capacitors CA1 to CAn and CB1 to CBn. If the voltage is stabilized in a range that does not require adjustment, it can be omitted and is not a particularly essential component. Of course, if the voltage fluctuation range becomes smaller by controlling the connection switching of the capacitors CA1 to CAn and CB1 to CBn, the converter can be designed with high efficiency by combining this with the converter, thereby realizing a power supply with high voltage stability. You can also.
[0022]
Further, as shown in FIG. 3B, the switches SA and SB constituting the switching circuit are unidirectional control rectifier elements SS1, SS2, SSA1 to SSA3, SSB1 to SSB3 and a rectifier element made of a diode as shown in FIG. 3B. An antiparallel circuit with SD1, SD2, SDA1 to SDA3, and SDB1 to SDB3 can be used. Among these, a circuit that connects between one end of the series connection of at least one capacitor group A and the other end of the series connection of the other capacitor group B includes the control rectifier SSA1, the rectifier SDA1, and the other capacitor group B. A circuit that connects between one end of the series connection and the other end of the series connection of one capacitor group A is configured by the control rectifying element SSB1 and the rectifying element SDB1, and the reverse direction (charge direction) ) Control rectifying elements SSA1 and SSB1 are connected in parallel. In other circuits, the control rectifier elements SS2, SSA3, SSB3 in the charging direction and the control rectifier elements SS1, SSA2, SSB2 in the reverse direction are connected in series, and the reverse rectifier elements SD2, SDA3, SDB3, Rectifier elements SD1, SDA2, and SDB2 are connected in parallel. Of course, these circuits may be circuits in which thyristors (control rectifier elements) are connected in antiparallel or circuits in which triacs (bidirectional control rectifier elements) are connected. In this case, when there is a voltage difference, the same control as described above may be performed. However, by selectively turning on / off a unidirectional control rectifier, cross current can be prevented, so that parallel connection can be performed simultaneously. Switching control may be used.
[0023]
By configuring the switching circuit by combining thyristors, triacs, and diodes as described above, it is strong against inrush current, and it is possible to reduce on-loss and gate loss for a long time. In addition, since the capacitor voltage is applied to the main pole as a reverse bias at the time of switching the connection, the turn-off control is not required and the gate control circuit can be simplified. For example, in the circuit of FIG. 3B, at the time of charging, it starts from a state in which only the control rectifier element SS2 is turned on and all others are turned off. As the charging proceeds, the control rectifier elements SSA3 and SSB3 are first turned on, so that the control rectifier element SS2 is turned off with a reverse bias. Next, by turning on the control rectifier elements SSA1 and SSB1, the control rectifier elements SSA3 and SSB3 are turned off with a reverse bias. At the time of discharging, from the state where all the control rectifier elements are turned off, the rectifier elements SDA1 and SDB1 are conducted to start discharging, the control rectifier elements SSA2 and SSB2 are turned on, and then the control rectifier element SS1 is turned on, Switching control can be performed until the capacitors CA1 to CAn and CB1 to CBn are all connected in series.
[0024]
In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible. For example, in the above embodiment, when switching the capacitor bank from serial connection to parallel connection while charging, the charging voltage of each capacitor bank is compared and if there is a voltage difference, the lower voltage changeover switch is turned on, Charging was continued until the voltage difference was close to zero. At that time, the voltage applied to the remaining changeover switch without turning it on (Vs1p in (1)-(2) in FIG. 1, (3)- (4) Vs2p) may be detected, and control may be performed so that the changeover switch is turned on when the voltage approaches zero. In this way, after the switch of the capacitor bank having the lower charge voltage is turned on, the voltage applied to the switch that remains off is not compared without comparing the charge voltage between the capacitor banks. It is only necessary to monitor and turn on when the voltage is near zero. At this time, the voltage applied to the changeover switch of the capacitor bank with the higher charge voltage that remains in the off state decreases as the capacitor bank with the lower charge voltage is charged. Passes and reverses the polarity of the voltage. Therefore, it suffices to detect and turn on the voltage near zero.
[0025]
The changeover switch is not limited to an element capable of analog operation such as an IGBT, FET, or transistor, but an element capable of only on / off control such as a thyristor, triac, GTO, or mechanical relay can be used. Needless to say. Therefore, in principle, the present invention detects the moment when the voltage applied to the switch becomes zero and turns on the switch. However, when the switch element requires an on-current, such as a thyristor, it is zero. Alternatively, the switch element may be turned on by detecting a state in which a certain minute voltage remains.
[0026]
【The invention's effect】
As is apparent from the above description, according to the present invention, in a series-parallel switching capacitor power storage device configured to switch and control the series-parallel connection of a plurality of capacitor banks, one capacitor bank, the other capacitor bank, A series connection switch that is connected in series to turn on / off the charge / discharge current, and is connected in parallel with the series circuit of the other capacitor bank and the series connection switch to turn on / off the charge / discharge current of one capacitor bank. One parallel connection switch, and a second parallel connection switch connected in parallel with the series circuit of one capacitor bank and the series connection switch to turn on / off the charge / discharge current of the other capacitor bank. a plurality of switches for switching the parallel connection, the voltage detecting means for detecting the voltage of the capacitor bank , And control means for controlling the plurality of switches to determine the voltage detected by the voltage detecting means, the control means, when charging is switched to the parallel connection of the capacitor bank connected in series to turn off the series switch The voltage of each capacitor bank to be switched to the parallel connection is detected and compared by the voltage detection means, and when there is a voltage difference of a predetermined value or more, only the parallel connection switch of the capacitor bank having the lower voltage is turned on, and the voltage difference Since the other parallel connection switch is turned on under the condition that is smaller than a predetermined value, when switching a plurality of capacitor banks connected in series with a simple configuration, the connection between the capacitor banks is reduced. Even if there is a difference in charge level, cross current can be prevented from flowing. Therefore, the loss of the series-parallel switching capacitor power storage device can be reduced, and safe operation can be maintained.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a series-parallel switching capacitor power storage device according to the present invention.
FIG. 2 is a diagram for explaining another embodiment of the present invention using a multistage connection switching control capacitor power supply device;
FIG. 3 is a diagram showing still another embodiment of a multistage connection switching control capacitor power supply device;
FIG. 4 is a diagram illustrating a configuration example of a series-parallel switching circuit of a capacitor bank.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Voltage detection circuit, 2 ... Voltage comparison judgment circuit, 3 ... Switch control circuit, 4 ... PWM inverter, C1, C2 ... Capacitor bank, Ss, S1p, S2p ... Changeover switch

Claims (1)

In the series-parallel switching type capacitor power storage device configured to switch and control the series-parallel connection of a plurality of capacitor banks,
A series connection switch connected in series between one capacitor bank and the other capacitor bank to turn on / off charging / discharging current, and one capacitor connected in parallel with a series circuit of the other capacitor bank and the series connection switch A first parallel connection switch for turning on / off the charge / discharge current of the bank; a second switch for turning on / off the charge / discharge current of the other capacitor bank connected in parallel with the series circuit of the one capacitor bank and the series connection switch; A plurality of switches that switch the series-parallel connection of the plurality of capacitor banks,
Voltage detecting means for detecting the voltage of the capacitor bank;
Control means for determining the voltages detected by the voltage detection means and controlling the plurality of switches, the control means turning off the series connection switch and switching the capacitor bank from series connection to parallel connection to charge. The voltage of each capacitor bank to be switched to the parallel connection is detected and compared by the voltage detection means, and when there is a voltage difference of a predetermined value or more, only the parallel connection switch of the capacitor bank having the lower voltage is used. And the other parallel connection switch is turned on on the condition that the voltage difference is smaller than a predetermined value .

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