JP2007209056A - Capacitor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capacitor device which can suppress the voltage fluctuation of a DC part within a certain range even if an original power source fluctuates. <P>SOLUTION: A capacitor 120 ( preferably, an electric double layer capacitor C) is connected via a reversible converter 111 to the DC part 12 of a feeder system including a load M and the original power source 11 of AC power or DC power, and a control circuit 112 monitors the voltage of the DC part 12, and controls the charge/discharge of the capacitor 120 by switching the reversible converter 111, according to the voltage of the DC part 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a power storage device applied to, for example, an uninterruptible power supply (UPS) of a large power supply system or a power supply system of a general-purpose inverter device, and more specifically, charge / discharge connected to a DC unit in the power supply system. The present invention relates to a technology that suppresses voltage fluctuations in the direct current section.

  In an uninterruptible power supply, the accumulator is connected to a direct current section that rectifies the ac power supply as the main power source and generates a direct current voltage, and stores in the accumulator in preparation for a voltage drop or a power failure. The electric power is converted into alternating current by an inverter and used.

  In general-purpose inverter devices, AC power is temporarily converted to DC, and the DC power is converted to AC by an inverter to drive a load such as an AC motor. In order to cope with the absorption of regenerative power and the like, a capacitor is connected to a direct current unit serving as a direct current power source.

  In the above power feeding system, a secondary battery capable of charging / discharging is usually used for the capacitor, and a model case thereof is shown in FIG. In FIG. 12, a secondary battery E2 as a storage battery is connected between the DC power supply E1 and the load M, but the DC power supply E1 is an AC power supply (original power supply) in the uninterruptible power supply apparatus or the general-purpose inverter apparatus. The load M corresponds to, for example, an AC electric motor driven by an AC voltage obtained by inversely converting the DC voltage by an inverter.

  The internal resistance of the DC power supply E1 is R1, the internal resistance of the secondary battery E2 is R2, the switch interposed between the DC power supply E1 and the secondary battery E2 is between SW1, the secondary battery E2 and the load M. SW2 is a switch interposed in the switch, and the switch SW1 is turned on and the switch SW2 is turned off during charging.

  As a result, the voltage of the secondary battery E2 is charged to the secondary battery E2 through the internal resistance R1 and the internal resistance R2 of the secondary battery E2, so the voltage V of the secondary battery E2 is shown in FIG. As shown, the voltage increases from V1 to V0 by the amount of current flowing through the internal resistor R2 as compared to the voltage V1 before charging.

  On the other hand, the switch SW2 is turned on at the time of discharging, and a load current flows toward the load M. Therefore, due to this load current, the internal resistance R1 of the secondary battery E2 and the internal resistance R2 of the secondary battery E2 As shown in FIG. 13, the voltage V of the secondary battery E2 drops to V2 (V2 <V1).

  That is, when the DC power supply voltage E1 rises, the secondary battery E2 also increases the charging current and the voltage, and the load voltage rises accordingly. Conversely, when the DC power supply voltage E1 decreases, the charging current of the secondary battery E2 decreases and the voltage drop due to the internal resistance R2 also decreases, but the load voltage also decreases.

  As described above, the charging current and the load current of the secondary battery also fluctuate due to the voltage fluctuation of the original power supply (in this case, the DC power supply voltage E1). Patent Document 1 discloses an invention in which the internal state of a secondary battery is modeled by an equivalent circuit, and characteristics such as the state of charge of the battery are quantitatively grasped from the input / output history of the battery.

JP 2003-243017 A

  In an uninterruptible power supply, charging / discharging is always performed at a shallow depth of discharge, but the DC unit to which the secondary battery is connected is connected to the AC power source, which is the original power source, via a rectifier circuit. The voltage of is affected by the original power source.

  Therefore, when the voltage of the original power source is high, the voltage of the direct current section also becomes high, so that the charging current of the secondary battery increases and the voltage of the secondary battery rises and may be overcharged. On the other hand, when the voltage of the main power source is low, the voltage of the DC part also becomes low, so the charging current of the secondary battery decreases, the secondary battery voltage is stable in a low state, the charging becomes insufficient, and the amount of charge is kept constant. It becomes difficult.

  Further, if this is prolonged at the time of a power failure, since the power is supplied to the load from the secondary battery, the discharge depth of the battery becomes deep, which causes the battery life to be advanced. In general-purpose inverter devices, a smoothing capacitor is usually used for the DC part, but since this type of smoothing capacitor has a small capacitance, it serves as an auxiliary power source when the voltage generated by the main power supply drops or during a power failure. Cannot be used.

  Also, in the regenerative braking mode of the motor, it is necessary to use a special conversion inverter for regenerating power to the AC power source side of the original power source and a harmonic removal filter for EMC (electromagnetic environment compatibility) measures There is.

  In addition to the secondary battery, there is an electric double layer capacitor as a chargeable / dischargeable battery. An electric double layer capacitor has a large capacitance, can be charged in a short time, can instantly release a large amount of power, and has a much longer charge / discharge cycle life than a secondary battery.

  However, since the voltage of the electric double layer capacitor changes with charge / discharge, it is difficult to apply it to a general-purpose inverter device. That is, an inverter circuit mounted on a general-purpose inverter device is usually designed with the voltage fluctuation within, for example, 10%, so that the design standard may not be cleared with an electric double layer capacitor.

  Accordingly, an object of the present invention is to provide a power storage device connected to a direct current unit in a power supply system such as an uninterruptible power supply device or a general-purpose inverter device. An object is to provide a power storage device that can be suppressed. Another object of the present invention is to make it possible to use an electric double layer capacitor as the capacitor.

In order to solve the above-mentioned problems, the present invention is used in a power supply system that applies a DC voltage obtained by rectifying an AC power supply by a rectifying means or a DC voltage obtained from a DC power supply to a load without conversion or predetermined conversion. In a power storage device, a power storage device comprising a chargeable / dischargeable electric double layer capacitor connected to a direct current unit of the power supply system via a reversible converter, and a control for controlling the reversible converter by monitoring the voltage V of the direct current unit And the control means exists between the first threshold voltage VH on the high voltage side and the second threshold voltage VL on the low voltage side, and between the first threshold voltage VH and the second threshold voltage VL. the third is set three predetermined threshold voltage in the threshold voltage VC, the control means, the reversible converter when the voltage V of the DC portion is higher than the first threshold voltage VH of Starts the charging of the said capacitor from switching the DC section in the charging direction, a charging step to continue the charging to the voltage V of the DC unit is lowered to the third threshold voltage VC, the voltage of the DC portion V When the voltage becomes lower than the second threshold voltage VL, the reversible converter is switched to the discharge direction to start discharging the capacitor with respect to the DC unit, and the voltage V of the DC unit is discharged to the third DC voltage . A discharge step that continues until the threshold voltage VC rises, and the DC voltage V is between the third threshold voltage VC and the second threshold voltage VL or the third threshold voltage VC and the first threshold voltage VH. A charge / discharge stop step of turning off the reversible converter and stopping charge / discharge of the battery .

In the present invention, in order to make the power storage device self-contained, it is preferable to obtain an operating power source for the control means from the DC section .

  According to the present invention, the accumulator is connected via the reversible converter to the AC power source as the main power source or the DC power source of the power supply system from the DC power source to the load, and the voltage of the DC unit is monitored by the control means. By switching the reversible converter according to the voltage to control the charging / discharging of the battery, a stable DC voltage can be obtained from the DC unit without being affected by the voltage fluctuation of the original power supply.

  Thereby, for example, the inverter control in the uninterruptible power supply apparatus and the general-purpose inverter apparatus is stabilized, the DC-AC conversion efficiency is improved, and the configuration of the filter circuit for EMC countermeasure can be simplified. Moreover, the electric power generated by the regenerative braking of the electric motor can be efficiently stored in the electric storage device. Furthermore, characteristics and life deterioration due to overcharge and overdischarge of the capacitor can be prevented. In addition, since the voltage of the direct current section is stably maintained by the control of the reversible converter, an electric double layer capacitor whose voltage fluctuates with charge / discharge can be used as the secondary battery, similarly to the secondary battery.

  First, an embodiment in which a power storage device 100 according to the present invention is applied to an inverter device will be described with reference to FIG. The inverter device converts the AC power source E, which is the original power source, into a direct current by a rectifier circuit Bt made of a diode group of the rectifier 11 and smoothes it by an LC filter circuit made up of a coil Lf and a capacitor Cf. 12 DC power is reversely converted into AC by the inverter circuit 13 to drive the load (motor) M.

  The power storage device 100 according to the present invention includes a control device 110 and a power storage device 120, and is connected to the DC unit 12 on the output side of the rectifying device 11 of the inverter device. In this example, an electric double layer capacitor C is used for the capacitor 120, and the electric double layer capacitor C is connected to the DC unit 12 via the control device 110.

  As shown in FIG. 2, as a basic configuration, the control device 110 includes a reversible converter 111 connected to the direct current unit 12, a control circuit 112 that monitors the voltage of the direct current unit 12 and controls the reversible converter 111, And a power supply circuit 113 for supplying operation power to the control circuit 112.

  In order to make the control device 110 self-contained, that is, to be able to self-activate in the inverter device, the power supply circuit 113 uses the voltage of the DC unit 12 as a power source, and enters the operating state when the voltage of the DC unit 12 reaches a specified value or more. enter. In this example, the control circuit 112 obtains the voltage value of the DC unit 12 from the power supply circuit 113.

  FIG. 3 shows a configuration example of the reversible converter 111. In FIG. 3, the rectifier circuit Bt in the rectifier 11 is indicated by a battery symbol for convenience of drawing. The reversible converter 111 used here may be a general one including a pair of transistors Tr1 and Tr2. Each base of the transistors Tr1 and Tr2 is connected to a control terminal (not shown) of the control circuit 112.

  The emitter of one transistor Tr1 and the collector of the other transistor Tr2 are connected. In this case, the collector of one transistor Tr1 is connected to the Hi side of the DC section 12, and the emitter of the other transistor Tr2 is connected to the DC section 12. Is connected to the Lo (ground) side.

  In addition, diodes D1 and D2 having a forward direction from the emitter to the collector side are respectively connected in parallel between the collectors and emitters of the transistors Tr1 and Tr2. One pole of the electric double layer capacitor 120 is connected to the connection point of the transistors Tr1 and Tr2 via the reactor L, and the other pole of the electric double layer capacitor 120 is connected to the Lo side of the DC unit 12 together with the emitter of the transistor Tr2. Connected.

  The charging / discharging of the electric double layer capacitor C is controlled by the reversible converter 111. FIG. 4 shows a timing chart during the charging operation, and FIG. 5 shows a timing chart during the discharging operation.

  At the time of charging, one transistor Tr1 is turned on and off by the control circuit 112, and the other transistor Tr2 is turned off. Referring to FIG. 4, a power supply voltage (voltage of DC unit 12) is applied to reactor L and electric double layer capacitor C during times T <b> 1 to T <b> 2 when transistor Tr <b> 1 is on.

  Then, when the current increases to reach the upper limit value, the transistor Tr1 turns off. As a result, the energy stored in the reactor L is released, and the electric double layer capacitor C is further charged by the circuit including the reactor L, the electric double layer capacitor C, and the diode D2 during time T2 to T3, and the voltage rises. To do.

  During discharging, the control circuit 112 turns off one transistor Tr1 and turns on and off the other transistor Tr2. Referring to FIG. 5, the energy stored in electric double layer capacitor C during the time T2 to T3 when transistor Tr2 is on flows to the circuit including electric double layer capacitor C, transistor Tr2 and reactor L. Current rises.

  When the current reaches the upper limit value, the transistor Tr2 is turned off, and the energy stored in the reactor L is released to the DC unit 12 through a circuit including the electric double layer capacitor C, the reactor L, and the diode D1. .

  Since this discharge voltage is a pulse voltage as shown as Tr2 voltage in FIG. 5, it is not shown, but it is necessary to interpose a smoothing circuit between the reversible converter 111 and the DC unit 12. . In that case, since the switching frequency for turning on and off the transistors Tr1 and Tr2 can be made higher than the power supply frequency of the AC power supply E, the smoothing circuit can be made compact.

12 and 13, it has been described that in the case of the conventional device, the charging current and load current of the battery (secondary battery) also change due to the voltage fluctuation of the original power supply. Therefore, by the switching control of the reversible converter 111 by the control circuit 112, the voltage fluctuation of the original power supply can be compensated and the voltage of the DC unit 12 can be kept substantially constant. First, the basic operation of this control will be described with reference to FIGS.

  6 shows a rectifier 11 for converting the original power supply (AC power supply E) of FIG. 1 into a direct current as a direct current power supply E1 for convenience of explanation, and the inverter circuit 13 of FIG. Yes.

  6 corresponds to the rectifying device 11, the voltage varies depending on the original power supply (AC power supply E). The power storage device 100 of the present invention is connected to the DC section 12 on the output side of the DC power supply E1. The switch SW1 is a charge switch for the power storage device 100, and the switch SW2 is a discharge switch for the load M.

  In addition, the control circuit 112 included in the control device 110 has a function of monitoring the voltage of the DC unit 12, but the control circuit 112 suppresses the voltage of the DC unit 12 within a certain range. As shown in FIG. 7, an upper threshold voltage VH and a lower threshold voltage VL are set.

Control circuit 112 switches the reversible converter 111 according to the voltage V of the DC unit 12 executes a charging step for the electric double layer capacitor C, and a discharge step to the load M.

  First, the charging step will be described. Assuming that the switch SW1 is on and the switch SW2 is off, the reversible converter 111 is switched in the charging direction when the voltage V of the DC unit 12 becomes higher than the upper threshold voltage VH, and the electric double layer capacitor C is switched from the DC unit 12 to the charging direction. The charging is continued until the voltage V of the DC unit 12 drops to the lower threshold voltage VL.

  With this charging, the voltage drop at the internal resistance R1 due to the charging current flowing through the DC power supply E1 increases, and the voltage of the DC power supply E1 (the voltage V of the DC unit 12) decreases. Therefore, in order to prevent hunting of the control system, the lower limit threshold voltage VL needs to be set in consideration of the increased value of the voltage drop at the internal resistance R1.

  Next, the discharge step will be described. When the switch SW2 is on and a load current flows due to the activation of the load M, the voltage V of the DC unit 12 decreases. When the voltage V becomes lower than the lower threshold voltage VL, the reversible converter 111 is switched to the discharge direction, and the electric double layer capacitor C starts discharging to the DC unit 12, but the voltage V increases. This discharge is continued until the voltage V of the DC unit 12 rises to the upper threshold voltage VH.

  Even during this discharge, in order to prevent hunting of the control system, the upper limit threshold voltage VH needs to be set in consideration of the voltage increase during the discharge.

In this way, the control of the reversible converter 111, even when the voltage of the DC power supply E1 fluctuates, it is possible to keep the voltage V of the DC portion 12 between the upper limit threshold voltage VH and the lower limit threshold voltage VL.

  Next, FIG. 8 shows a timing chart of waveforms simulating the power feeding system of FIG. 6 from the DC power source E1 to the load M, and this will be described. 8A shows the voltage waveform of the load M, FIG. 8B shows the voltage waveform of the DC power supply E1 and the voltage waveform of the electric double layer capacitor C, and FIG. 8C shows the current waveform of the DC power supply E1 and the electric double layer. It is a current waveform of the capacitor C. Among these, the waveform of the load M is indicated by a solid line, the waveform of the DC power supply E1 is indicated by a one-dot chain line, and the waveform of the electric double layer capacitor C is indicated by a two-dot chain line.

  In this simulation, the rated output DC100V of the DC power supply E1 is varied between DC105V and DC95V, and the upper limit threshold voltage is DC101V and the lower limit threshold voltage is DC99V.

  The voltage of the DC power supply E1 starts to increase from DC 100V to DC 105V at 0.5 seconds, but when the upper threshold voltage DC 101V is reached, charging of the electric double layer capacitor C is started. Since the voltage of the power source E1 is continued until the lower limit threshold voltage is DC99V, the voltage of the load M is kept at DC99V.

  That is, while the constant current DC10A continues to flow through the load M during this period, the charging current of DC20A flows from the DC power supply E1 to the electric double layer capacitor C, and the voltage drop at the DC power supply E1 caused thereby causes the voltage drop at the DC power supply E1 as described above. The voltage of the load M is maintained at DC99V.

  Then, at the time of 2.5 seconds, the voltage of the DC power supply E1 starts to decrease toward DC95V, but when the voltage reaches the lower limit threshold voltage of DC99V, the electric double layer capacitor C starts to be discharged. Since the discharge is continued until the voltage of the DC power supply E1 reaches the upper limit threshold voltage of DC 101V, the voltage of the load M is kept at DC 101V.

  During this time, the current from the DC power source E1 is attenuated (0 A on the chart), and DC 10A is supplied from the electric double layer capacitor C to the load M. This state continues until 4.75 seconds when the voltage of the DC power supply E1 rises again toward DC105V.

  Next, an example of a logic circuit that switches and controls the reversible converter 111 by comparing the voltage V of the DC unit 12, the upper threshold voltage VH, and the lower threshold voltage VL will be described with reference to FIG.

  This logic circuit is incorporated in the control circuit 112, and for charge control, a charge memory 2a comprising a flip-flop circuit having terminals of set S and reset R, an OR circuit 2b, a charge memory 2a and an OR And an AND circuit 2c that takes the AND of each output of the circuit 2b.

  Similarly, for discharge control, a discharge memory 3a composed of a flip-flop circuit having terminals of set S and reset R, an OR circuit 3b, and an AND circuit that takes AND of outputs of the discharge memory 3a and the OR circuit 3b 3c.

  The logic circuit includes first to third determination steps ST4a to ST4c for determining whether V ≧ VH, VH> V ≧ VL, and VL> V. The YES output (for example, logic level) of each determination step is included. The output of “1” is applied to each circuit element described above. The charging memory 2a and the discharging memory 3a output “1” at the logic level when set, and the output becomes “0” when reset.

  That is, the YES output of the first determination step ST4a is applied to the set terminal S of the charging memory 2a, one input terminal of the OR circuit 2b, and the reset terminal R of the discharging memory 3a. The YES output of the second determination step ST4b is applied to the other input terminal of the OR circuit 2b and one input terminal of the OR circuit 3b. The YES output of the third determination step ST4c is applied to the set terminal S of the discharge memory 3a, the other input terminal of the OR circuit 3b, and the reset terminal R of the charge memory 2a.

  When V ≧ VH, the charging memory 2a is set by the YES output of the first determination step ST4a, and the discharging memory 3a is reset. As a result, the respective outputs of the charging memory 2a and the OR circuit 2b become “1”, so that a charging control signal is output from the AND circuit 2c to the reversible converter 111 to enter the charging mode.

  When VH> V ≧ VL, the charging memory 2a is set in the first determination step ST4a, and the YES output of the second determination step ST4b is applied to the OR circuit 2b, so that the charging mode is maintained. Is done.

  When VL> V, the discharge memory 3a is set by the YES output of the third determination step ST4c, and the charge memory 2a is reset. As a result, the respective outputs of the discharge memory 3a and the OR circuit 3b become “1”, so that a discharge control signal is output from the AND circuit 3c to the reversible converter 111 and the discharge mode is set.

  In this discharge mode, when the voltage V of the DC unit 12 rises and V ≧ VH again, a YES output is output in the first determination step ST4a and the mode is switched to the charge mode.

According to the above control reporting, to become a repeating, as shown in FIG. 7, the charging by the actuation of the main power fluctuations and load discharge and, if this is frequently performed, by switching in a reversible converter 111 Loss may increase.

Therefore, in this onset bright, the control circuit 112, as shown in FIG. 10, upper threshold voltage VH, as a third threshold voltage, in addition to the lower limit threshold voltage VL, sets the intermediate threshold voltage VC. The intermediate threshold voltage VC is preferably a voltage that is ½ of the upper threshold voltage VH and the lower threshold voltage VL (for example, DC100V if VH is DC101V and VL is DC99V), but may be another voltage.

According to the present invention, when the voltage V of the DC unit 12 becomes higher than the upper threshold voltage VH, the reversible converter 111 is switched to the charging direction, and charging of the electric double layer capacitor C from the DC unit 12 is started. At the same time, this state of charge is continued until the voltage V of the DC unit 12 drops to the intermediate threshold voltage VC.

  When the voltage V of the DC unit 12 exists between the intermediate threshold voltage VC and the lower threshold voltage VL, the reversible converter 111 is controlled to be turned off, and charging / discharging of the electric double layer capacitor C is stopped.

  When the voltage V of the DC unit 12 becomes lower than the lower limit threshold voltage VL, the reversible converter is switched to the discharge direction, and the electric double layer capacitor C starts to be discharged to the DC unit 12. Is continued until the voltage V of the DC unit 12 rises to the intermediate threshold voltage VC.

  When the voltage V of the DC unit 12 exists between the intermediate threshold voltage VC and the upper threshold voltage VH, the reversible converter 111 is controlled to be turned off, and charging / discharging of the electric double layer capacitor C is stopped.

That is, in the present invention , by setting the above-described charging / discharging stop period, charging / discharging is not performed when the voltage V of the DC unit 12 is between the upper threshold voltage VH and the lower threshold voltage VL. Therefore, the number of times of switching in the reversible converter 111 can be reduced.

11 shows an example of a logic circuit for controlling the switching of the reversible converter 111. The circuit elements shown in FIG. 9 may be used for both charge control and discharge control, but in this embodiment, the determination steps are V ≧ VH, VH> V ≧ VC, VC> V ≧ VL, VL> V Since the first to fourth determination steps ST5a to ST5d are performed, the input / output relationship of each circuit element is changed as follows.

  That is, in the charge control system, the YES output of the first determination step ST5a is applied to the set terminal S of the charging memory 2a and one input terminal of the OR circuit 2b, and the other input terminal of the OR circuit 2b The YES output of the second determination step ST5b is applied. The output of the OR circuit 2b is applied to the AND circuit 2c and the reset terminal R of the discharge memory 3a.

  In the discharge control system, the YES output of the third determination step ST5c is applied to one input terminal of the OR circuit 3b, and the output of the OR circuit 3b is given to the reset terminal R of the charging memory 2a and the AND circuit 3c. Further, the YES output of the third determination step ST5d is given to the other input terminal of the OR circuit 3b and the set terminal S of the discharge memory 3a.

  According to this, when V ≧ VH, the YES output of the first determination step ST5a is applied to the set terminal S and the OR circuit 2b of the charging memory 2a, whereby the charging memory 2a is set. On the other hand, since the discharging memory 3a is reset, a charging control signal is output from the AND circuit 2c to the reversible converter 111, and the charging mode is set.

  When VH> V ≧ VC, the YES output of the second determination step ST5b is applied to the OR circuit 2b, and the charging memory 2a is set in the first determination step ST5a, so that the charging mode is maintained. The

  When VC> V ≧ VL, since the YES output of the third determination step ST5c is applied to the OR circuit 2b, the charging memory 2a is reset and the discharging memory 3a is also in the reset state, so that charging / discharging is stopped. It becomes a state.

  In the case of VL> V, the YES output of the fourth determination step ST5d is applied to the set terminal S and the OR circuit 3b of the discharge memory 3a, whereby the discharge memory 3a is set and charged for this. Since the memory 2a is reset, a discharge control signal is output from the AND circuit 3c to the reversible converter 111, and the discharge mode is set.

  In this discharge mode, when the voltage V of the DC unit 12 rises and V ≧ VC, a YES output is output from the second determination step ST5b, whereby the discharge memory 3a is reset and the charge memory Since 2a is also in the reset state, the charge / discharge stop state is entered.

As mentioned above, although this invention was demonstrated based on the example of illustration, this invention is not limited to this. In the above embodiment, an electric double layer capacitor in the electric storage pack can also be used a hybrid capacitor that combines electric double layer capacitor and a secondary battery. Moreover, in the said embodiment, although the original power supply was demonstrated as an alternating current power supply, the original power supply may be a direct current power supply.

The typical circuit block diagram which shows embodiment which applied the electrical storage apparatus of this invention to the inverter apparatus. The circuit block diagram which shows the said electrical storage apparatus. The circuit block diagram which showed concretely the composition of the reversible converter with which the above-mentioned electrical storage device is provided. The timing chart for demonstrating the charging operation of the said reversible converter. The timing chart for demonstrating the discharge operation of the said reversible converter. The schematic diagram for demonstrating the basic operation | movement of the said electrical storage apparatus in the electric power feeding system containing a power supply and load. The schematic diagram which shows the basic charging / discharging cycle of control by this invention. Timing chart by charge / discharge simulation. The block diagram which shows the logic circuit for the charging / discharging control applied to the charging / discharging cycle of FIG. Schematic diagram showing the charge-discharge cycle of control to the present invention. The block diagram which shows the logic circuit for charge / discharge control applied to this invention . The schematic diagram which shows the electric power feeding system which has the conventional electrical storage. The graph which shows the voltage fluctuation state in the said electric power feeding system of the said conventional electrical storage.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Rectifier 12 DC part 13 Inverter circuit 100 Power storage device 110 Control device 111 Reversible converter 112 Control circuit 113 Power supply circuit 120 Power storage E AC power supply E1 DC power supply R1 Internal resistance C Electric double layer capacitor VH Upper threshold voltage (first threshold voltage)
VL Lower threshold voltage (second threshold voltage)
VC intermediate threshold voltage (third threshold voltage)

Claims (5)

In a power storage device used for a power supply system that provides a DC voltage obtained by rectifying an AC power supply by a rectifying means or a DC voltage obtained from a DC power supply to a load without conversion or predetermined conversion,
A chargeable / dischargeable battery connected to the DC section of the power supply system via a reversible converter; and a control means for controlling the reversible converter by monitoring the voltage V of the DC section. Two predetermined threshold voltages, the first threshold voltage VH on the high voltage side and the second threshold voltage VL on the low voltage side, are set,
The control means switches the reversible converter to the charging direction when the voltage V of the DC unit becomes higher than the first threshold voltage VH, and starts charging from the DC unit to the battery, and performs the charging. A charging step that continues until the voltage V of the DC section drops to the second threshold voltage VL;
When the voltage V of the DC unit becomes lower than the second threshold voltage VL, the reversible converter is switched to the discharge direction, and the capacitor starts discharging to the DC unit, and the discharge is transferred to the DC unit. And a discharging step that continues until the voltage V rises to the first threshold voltage VH. The control means is further set with a third threshold voltage VC existing between the first threshold voltage VH and the second threshold voltage VL,
The control means switches the reversible converter to the charging direction when the voltage V of the DC unit becomes higher than the first threshold voltage VH, and starts charging from the DC unit to the battery, and performs the charging. A charging step that continues until the voltage V of the DC section drops to the third threshold voltage VC;
When the voltage V of the DC unit becomes lower than the second threshold voltage VL, the reversible converter is switched to the discharge direction, and the capacitor starts discharging to the DC unit, and the discharge is transferred to the DC unit. In addition to the discharging step that continues until the voltage V rises to the third threshold voltage VC,
When the voltage V of the DC section is between the third threshold voltage VC and the second threshold voltage VL or between the third threshold voltage VC and the first threshold voltage VH, the reversible converter is turned off. The power storage device according to claim 1, further comprising a charge / discharge stop step for stopping charge / discharge of the battery.   The power storage device according to claim 1 or 2, wherein an operating power source of the control means is obtained from the DC section.   The power storage device according to any one of claims 1 to 3, wherein the battery is an electric double layer capacitor. The power storage device according to any one of claims 1 to 3, wherein the battery is a secondary battery.

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