JP2008061364A - Power storage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase a charging capacity at charging, to make an electric double-layer capacitor hardly brought into a fully charged state, to make regeneration operation hardly limited, and to facilitate control. <P>SOLUTION: The electric double-layer capacitor 2 and an accumulator 6 are connected to a power supply by using two changeover switches 3, 5, the electric double-layer capacitor 2 and the accumulator 6 are connected in series to each other at discharging, and a series circuit formed by connecting a diode 4 in series to the accumulator 6 in a charging current direction is connected to the electric double-layer capacitor 2 in parallel therewith at charging. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power storage device that uses a combination of a storage battery and an electric double layer capacitor in an electric vehicle, a railway, and the like.

As a conventional power storage device, there is Patent Document 1, which connects a capacitor and a storage battery in series at the time of discharging, disconnects the storage battery at the time of charging, charges only the capacitor, and the capacitor is fully charged (the terminal voltage is It means switching to charging the storage battery when the maximum voltage is set. That is, conventionally, when charging is performed in a state where the storage battery and the capacitor are connected in parallel, when the terminal voltage of the capacitor is lower than the storage battery terminal voltage, a charging current flows from the storage battery to the capacitor, and charging is performed up to the storage battery terminal voltage. . For this reason, the charge to the capacitor is in a high voltage range, and the amount of charge of the capacitor by the regenerative power is restricted at the time of power regeneration, and the regenerative operation is also restricted. In addition, when discharging in a state where the storage battery and the capacitor are connected in parallel, the capacitor terminal voltage is equal to the terminal voltage of the storage battery with little voltage fluctuation, so the capacitor discharge becomes a high voltage range, and the discharge amount is limited. The stored energy of the capacitor was not used effectively. Therefore, in Patent Document 1, when charging (regeneration), the storage battery is disconnected and only the capacitor is charged with regenerative power. When the capacitor is fully charged, the capacitor is disconnected and only the storage battery is connected. Then, it was charged with regenerative power.
Further, at the time of discharging, a storage battery and a capacitor are connected in series, and the use voltage range of the capacitor is widened to effectively use the stored energy.
JP 2000-354303 A

  However, in the technique of Patent Document 1 described above, the capacitor is charged in the initial stage of regeneration, and the storage battery is charged after the capacitor is fully charged. Charging and large-capacity charging could not be performed simultaneously. Further, in order to perform such switching at the time of charging, two power converters are required, which makes the control complicated and increases the cost of the apparatus.

  This invention has been made to solve the above problems, can increase the charging capacity during charging, the capacitor is less likely to be in a fully charged state, making it difficult to limit the regenerative operation, It is an object of the present invention to obtain a power storage device that does not require management of the amount of charge of a capacitor, is easy to control, and has a small and inexpensive control device.

  An electric power storage device according to claim 1 of the present invention connects an electric double layer capacitor and a storage battery to a power source using two changeover switches, and connects the electric double layer capacitor and the storage battery in series during discharge. When charging, a series circuit in which a diode is connected to the storage battery in series so as to be in the forward direction in the charging current direction and an electric double layer capacitor are connected in parallel.

  The power storage device according to claim 2 connects an electric double layer capacitor and a storage battery to a power source using three semiconductor switches, connects the electric double layer capacitor and the storage battery in parallel at the time of charging, and at the time of discharging. The electric double layer capacitor and the storage battery are connected in series, and when the terminal voltage of the electric double layer capacitor or the storage battery drops during discharging, the output voltage of the electric double layer capacitor or the storage battery is boosted by controlling the semiconductor switch. Alternatively, the storage battery is discharged.

  As described above, according to the first aspect of the present invention, the electric double layer capacitor and the storage battery are connected in parallel to the power source during charging, and the electric double layer capacitor and the storage battery can be charged simultaneously. In addition to being able to charge a large capacity, rapid charging is also possible.When the charging of the electric double layer capacitor proceeds and the terminal voltage rises and exceeds the terminal voltage of the storage battery, the electric battery is charged from the electric double layer capacitor. When the terminal voltage of the storage battery is higher than the terminal voltage of the double layer capacitor, the electric double layer capacitor is not charged by the storage battery due to the provision of the diode, and the electric double layer capacitor is unlikely to be fully charged, and regenerative operation is limited. It becomes difficult to be done. Further, by connecting the electric double layer capacitor and the storage battery in series at the time of discharging, the operating voltage range of the electric double layer capacitor can be expanded, and the stored energy can be used effectively. Furthermore, the control can be performed only by providing two changeover switches and diodes, and it is not necessary to manage the charge amount of the electric double layer capacitor, so that the control is easy and the control device can be made small and inexpensive.

  According to the second aspect, the electric double layer capacitor and the storage battery are connected in parallel to the power source during charging, and the electric double layer capacitor and the storage battery can be charged at the same time, from the electric double layer capacitor to the storage battery. Although charging is performed, charging from the storage battery to the electric double layer capacitor is not performed, and rapid charging and large-capacity charging are possible. The electric double layer capacitor is unlikely to be fully charged, and the amount of charge of the electric double layer capacitor is not controlled. This makes it difficult to limit the regenerative operation. In addition, the electric double layer capacitor and the storage battery are connected in series at the time of discharge, so that the operating voltage range can be expanded, and when the terminal voltage of the electric double layer capacitor or the storage battery drops, these boosting discharges are performed. A maximum discharge of energy is possible. Further, the control can be performed only by providing three semiconductor switches, the charge amount of the electric double layer capacitor is not required to be controlled, the control is easy, and the control device can be reduced in size and cost.

Best Embodiment 1
The best mode for carrying out the present invention will be described below with reference to the drawings. 1 (a) to 1 (c) show a circuit configuration diagram, a voltage characteristic diagram during charging, and a current characteristic diagram during charging, according to Embodiment 1 of the present invention. DC motors or feeder substations are considered, and the positive and negative terminals (hereinafter referred to as g terminal and h terminal) of the buck-boost chopper 1 are the positive side (+) terminal (hereinafter referred to as motor positive side terminal) of the DC motor. And the negative side (−) terminal (hereinafter referred to as motor negative side terminal) or the output side external line (hereinafter referred to as external line) of the feeder substation and the return line are connected. The external line is an output side of the feeder substation and is a general term for feeders, overhead lines, and trolley lines, and the external line voltage is the voltage. A reactor in which the g terminal and the h terminal of the buck-boost chopper 1 which is a converter are connected in parallel between the motor positive side and the negative terminal or between the external line and the return line, and one end is connected between the upper and lower arms of the buck-boost chopper 1. One end of an electric double layer capacitor (hereinafter abbreviated as EDLC) 2 is connected between the other end of L (hereinafter referred to as i terminal) and the negative terminal of the return line or motor. Is connected to the other end of the EDLC 2 and the common contact c of the first changeover switch 3 having a transfer contact, the first changeover switch 3 is selected as a terminal b, and the other end of the EDLC 2 is connected to the storage battery 6. A series circuit connected to the positive side (+) terminal of the circuit, a circuit selected as the terminal a and connected to the return line or the negative side terminal of the motor, and the anode of the diode 4 are connected to the i terminal of the step-up / down chopper 1. Along with the diode 4 The common contact f of the second changeover switch 5 having the cathode and the transfer contact is connected, the second changeover switch 5 is selected as the terminal e, and the cathode side of the diode 4 is made the positive side (+) terminal of the storage battery 6. A series circuit of a diode 4 and a storage battery 6 that are connected in the forward direction in the charging current direction and a circuit that is selected as the terminal d and opens the cathode side of the diode 4 are provided.

  In the above configuration, when the EDLC 2 and the storage battery 6 are discharged (when powering power is supplied to the motor or the external line), the terminals b and c of the changeover switch 3 are connected and the terminals d and f of the changeover switch 5 are connected. Then, the EDLC 2 and the storage battery 6 are connected in series between the i terminal of the step-up / down chopper 1 and the return line or the negative terminal of the motor. In this state, the EDLC 2 and the storage battery 6 are discharged to the motor or the external line via the step-up / step-down chopper 1 and power running power is supplied. At this time, in the example of the step-up / step-down chopper 1 shown in FIG. 1A, the semiconductor switch SW2 is controlled to perform boosting discharge. In addition, in the modified example of the step-up / step-down chopper 1 shown in FIG. 2A, when the voltage of the series circuit of the EDLC 2 and the storage battery 6 is higher than the external line voltage or the motor positive terminal voltage, the semiconductor switch SW3 is controlled to be stepped down. When the discharge is performed and the series circuit voltage decreases due to the continuation of the step-down discharge and the voltage of the series circuit becomes lower than the external line voltage or the motor positive terminal voltage, the semiconductor switch SW3 is controlled to be on (at the time of the boost discharge, As is, the semiconductor switch SW2 is subjected to switching control to perform boost discharge. In the case of FIG. 2A, the part other than the semiconductor switch SW3 and the diode D3 provided in the step-up / step-down chopper 1 is the same as FIG.

  Next, when charging (when regenerating from a motor or an external line), the selector switches 3 and 5 are switched in FIG. 1A or FIG. 2A to connect the terminals a and c of the selector switch 3. At the same time, the terminals e and f of the changeover switch 5 are connected so that the diode 4 of the storage battery 6 is forward in the charging current direction between the i terminal of the buck-boost chopper 1 and the return or motor negative terminal. A series circuit connected in series is connected in parallel with the EDLC 2, and the regenerative power of the motor or the external line is charged to both the EDLC 2 and the storage battery 6. The diode 4 connected in series to the storage battery 6 is connected so as to be forward in the charging current direction of the storage battery 6, and charging from the storage battery 6 to the EDLC 2 is not performed. Further, the charging current of the EDLC 2 and the storage battery 6 flows at a shunt ratio determined by the terminal voltage of the EDLC 2, the terminal voltage of the storage battery 6 and the respective internal resistances. The total charging current of both charging currents is the semiconductor switch SW1. More controlled. 2B shows a modification in which the connection between the changeover switch 3 and the EDLC 2 and the connection between the storage battery 6, the changeover switch 5 and the diode 4 are changed in FIG. 1A, and the EDLC 2 and the storage battery 6 are discharged at the time of discharging. Are connected in series, and when the EDLC 2 is connected in parallel with the series circuit of the storage battery 6 and the diode 4 that is forward in the charging current direction during charging, the same effect as in FIG.

  As shown in FIG. 1B, the terminal voltage of the EDLC 2 is lower than that of the storage battery 6 at the initial stage of charging due to discharging, and a large amount of charging is performed. When approaching, the charging current of the EDLC 2 decreases as shown in FIG. When the terminal voltage of the EDLC 2 becomes equal to or higher than the terminal voltage of the storage battery 6, the storage battery 6 is charged from the EDLC 2 and the motor or the EDLC 2 and the external line. Thereafter, the terminal voltage of the EDLC 2 and the terminal voltage of the storage battery 6 are Charging is performed in the same state.

  In the first embodiment described above, the EDLC 2 and the storage battery 6 can be connected in parallel at the time of charging (at the time of regenerative power absorption from the motor or outside line), and both the EDLC 2 and the storage battery 6 can be charged simultaneously. Compared to the single charging of the battery, the charging capacity can be increased, and the EDLC 2 is unlikely to be in a fully charged state, so that rapid charging is also possible. In addition, the amount of charge of the EDLC 2 and the storage battery 6 is determined by the terminal voltage (charging state) of the EDLC 2. Since the EDLC 2 is charged in parallel with the storage battery 6 in combination with the fact that the storage battery 6 does not charge the EDLC 2 and that large capacity charging is possible, the charging voltage of the storage battery 6 If the voltage is lower than the rated upper limit voltage of the EDLC2, the EDLC2 is unlikely to be in a fully charged state, and the regenerative operation is hardly restricted. In addition, control is possible simply by providing the two changeover switches 3 and 5 and the diode 4, and it is not necessary to manage the charge amount of the EDLC 2, no complicated control circuit is required, control is easy, and the control device is inexpensive. You can make it small.

Embodiment 2
FIG. 3A is a circuit configuration diagram of the power storage device according to the second embodiment of the present invention. As the power source, as in the first embodiment, a DC motor of an electric vehicle or a train or a feeder substation is considered. One end of the first series circuit of the first semiconductor switch SW11 and the first reactor Lb1 is connected to the outside line or the motor positive side terminal, and one end of the EDLC 7 is connected to the external line or the motor positive side terminal. A second series circuit of the second semiconductor switch SW12 and the second reactor Lb2 is connected between the other end and the other end of the EDLC 7, and the other end of the first series circuit and one end of the second series circuit. A storage battery 8 is connected between the connection point to the return line or the motor negative side terminal, and between the connection point to the other end of the second series circuit and the return line or the motor negative side terminal. 3rd reactor Lb3 and 3rd Third series circuit of a semiconductor switch SW13 is connected. The cathode side of the first free-wheeling diode FD1 is connected to the connection point between the first semiconductor switch SW11 and the first reactor Lb1, and the anode side of the free-wheeling diode FD1 is connected to the return line or the motor negative side terminal. . The cathode side of the second freewheeling diode FD2 is connected to the external line or the motor positive side terminal, and the anode side of the freewheeling diode FD2 is connected to the connection point between the third reactor Lb3 and the third semiconductor switch SW13. The cathode side of the third free-wheeling diode FD3 is connected to the connection point between the semiconductor switch SW12 and the second reactor Lb2, and the anode side of the free-wheeling diode FD3 is connected to the return line or the motor negative side terminal. Note that the terminal voltage of each of the storage battery 8 and the EDLC 7 is set to be equal to or lower than the lower limit value of the fluctuation of the power supply voltage (motor voltage or external line voltage).

  Next, the operation will be described. First, at the time of charging, as shown in FIG. 3B, the semiconductor switches SW11 and SW13 are subjected to switching control, and the semiconductor switch SW12 is controlled to be off (it remains off at the time of charging). . As a result, the charging current i1 flows from the external line or the motor positive terminal through the semiconductor switch SW11 to the reactor Lb1 and the storage battery 8 as indicated by the arrow, and the external line voltage or the motor positive terminal voltage is stepped down by switching control of the semiconductor switch SW11. Then, the storage battery 8 is charged. When the semiconductor switch SW11 is turned off by the switching control, the current i2 flows through the reactor Lb1, the storage battery 8, and the freewheeling diode FD1 by the energy stored in the reactor Lb1, and the storage battery 8 is charged. Further, the charging current i3 flows through the semiconductor switch SW13 to the EDLC 7 and the reactor Lb3, and the external line voltage or the positive terminal voltage of the motor is stepped down by the switching control of the semiconductor switch SW13 to charge the EDLC 7. When the semiconductor switch SW13 is turned off by switching control, the current i4 flows through the freewheeling diodes FD2, EDLC7, and the reactor Lb3 by the energy stored in the reactor Lb3, and the EDLC 7 is charged. At this time, the EDLC 7 is not charged from the storage battery 8 by the semiconductor switch SW11.

  Next, at the time of discharging, the control changes depending on the output voltages of the EDLC 7 and the storage battery 8. First, when the added voltage between the storage battery 8 and the EDLC 7 connected in series is equal to or higher than the external line voltage or the motor positive terminal voltage, the semiconductor switches SW11 and SW13 are turned off (step-down) as shown in FIG. Control is performed so that the target voltage is reached by switching control of the semiconductor switch SW12. When the semiconductor switch SW12 is turned on by the switching control, the storage current 8, the semiconductor switch SW12, the reactor Lb2, the discharge current i5 from the return line or the motor negative terminal by the energy stored in the EDLC 7 and the storage battery 8 as shown by the arrow, When the semiconductor switch SW12 is turned off, the discharge current i6 flows as shown in the figure via the freewheeling diode FD3 due to the energy stored in the EDLC7 and the reactor Lb2 when the semiconductor switch SW12 is turned off. Is done. If such discharge is continued, depending on the capacity ratio between the EDLC 7 and the storage battery 8, the voltage change of the EDLC 7 is large, so the voltage of the EDLC 7 decreases, and the added voltage is less than the external line voltage or the motor positive terminal voltage. Thus, the step-down discharge cannot be continued. In order to continue the discharge in this case, as shown in FIG. 4B, the semiconductor switch SW12 is turned on (it remains on at the time of step-up discharge of the EDLC 7), and the semiconductor switch SW11 is controlled to switch. Is turned on, the EDLC 7 is short-circuited, and a circulation i7 is generated in the EDLC 7 through the semiconductor switch SW11, the reactor Lb1, the semiconductor switch SW12, and the reactor Lb2. When the semiconductor switch SW11 is turned off, the output voltage of the EDLC 7 is boosted by the energy stored in the reactor Lb2, the discharge current i8 flows with the energy stored in the reactor Lb1, and the discharge current with the energy stored in the storage battery 8 i5 flows. By increasing the pressure of the EDLC 7 and continuing the discharge, the operating voltage range of the EDLC 7 is expanded and the discharge amount is increased. If such boosting discharge of the EDLC 7 is continued, the terminal voltage of the EDLC 7 further decreases, and eventually the boosting cannot be performed (or is not efficient). As described above, when the required amount of discharge cannot be ensured, as shown in FIG. 4C, the semiconductor switch SW11 is controlled to be off (it remains off when the storage battery 8 is boosted), and the semiconductor switch SW12 is turned on. ON control is performed (when the battery 8 is boosted and discharged, it remains ON). Further, the semiconductor switch SW13 is subjected to switching control. When the semiconductor switch SW13 is turned on, the storage battery 8 is short-circuited, and the recirculation current i9 is generated in the storage battery 8 through the semiconductor switch SW12, the reactors Lb2, Lb3, and the semiconductor switch SW13. When the semiconductor switch SW13 is turned off, the discharge current i10 that flows by boosting the output voltage of the storage battery 8 by the energy stored in the reactors Lb2 and Lb3 and the output voltage of the storage battery 8 are boosted only by the energy stored in the reactor Lb2. There is a discharge current i11 flowing therethrough, and the storage battery 8 is boosted to continue discharging.

  Here, a specific example applied to the feeder substation will be described. Assume that the external line is a 1500 V system, the voltage fluctuation range is 1200 to 1800 V, the EDLC 7 and the storage battery 8 are charged at 1650 V or more, and the EDLC 7 and the storage battery 8 are discharged at 1200 V or less. Further, it is assumed that the maximum terminal voltage of the EDLC 7 and the storage battery 8 is 750V, and the minimum terminal voltage of the EDLC 7 is 300V. First, when the external line voltage is 1200 V or less and the EDLC 7 and the storage battery 8 are discharged, assuming that the EDLC 7 and the storage battery 8 are fully charged, the series connection voltage is 1500 V. The step-down discharge shown is performed. If this step-down discharge is continued, the terminal voltage of EDLC7 and the storage battery 8 will fall, and a serial connection voltage will be 1200V or less. At this time, the terminal voltage of the EDLC 7 having a large voltage fluctuation decreases first. However, the terminal voltage of the EDLC 7 and the storage battery 8 is monitored, and when the series connection voltage becomes 1200 V or less due to the voltage drop of the EDLC 7, as shown in FIG. 4B, the semiconductor switch SW11 is controlled to switch to the reactor Lb2. The output voltage of the EDLC 7 is boosted with the stored energy to discharge the external line voltage to 1200V. Furthermore, if the discharge is continued, the terminal voltage of the EDLC 7 continues to decrease, and the voltage cannot be boosted or becomes inefficient. In this case, since a required voltage cannot be secured, the semiconductor switch SW11 is turned off and the SW13 is controlled to be switched as shown in FIG. By the switching control of the SW 13, the output voltage of the storage battery 8 is boosted with the energy stored in the reactors Lb 2 and Lb 3 to discharge the external line voltage to 1200V. Further, when the EDLC 7 and the storage battery 8 are charged with an external voltage of 1650 V or higher, the semiconductor switch SW12 is turned off and the storage battery 8 is stepped down by switching control of the semiconductor switch SW11 as shown in FIG. Then, step-down charging of the EDLC 7 is performed by switching control of the semiconductor switch SW13. Charging is performed until each terminal voltage reaches 750V.

  In Embodiment 2, the EDLC 7 and the storage battery 8 are connected in parallel at the time of charging, and both are charged by the external line voltage or the positive terminal voltage of the motor. When possible combination charging of the storage battery 8 is possible and the terminal voltage of the EDLC 7 is set higher than that of the storage battery 8, the EDLC 7 is unlikely to be in a fully charged state and the regenerative operation is not easily restricted. Moreover, the EDLC 7 and the storage battery 8 are connected in series at the time of discharge, and the working voltage range can be expanded. In addition, when the terminal voltage of the EDLC 7 or the storage battery 8 is lowered, these boosted discharges are performed, so that the discharge can be performed with a wider operating voltage range, and the discharge end voltage of the EDLC 7 or the storage battery 8 can be used. Furthermore, the control can be performed only by providing the three semiconductor switches SW11 to SW13, the management of the charge amount of the EDLC 7 is not required, the control is easy, and the control device is small and inexpensive.

FIG. 2 is a circuit configuration diagram, a voltage characteristic diagram during charging, and a current characteristic diagram during charging of the power storage device according to the first embodiment of the present invention. It is a figure which shows the modification of the buck-boost chopper part of the electric power storage apparatus by Embodiment 1, and the whole modification of an electric power storage apparatus. It is the circuit block diagram of the electric power storage apparatus by Embodiment 2 and operation | movement explanatory drawing at the time of the charge. It is operation | movement explanatory drawing at the time of discharge of the electric power storage apparatus by Embodiment 2. FIG.

Explanation of symbols

2,7 ... Electric double layer capacitor (EDLC)
3, 5 ... changeover switch 4 ... diode 6, 8 ... storage battery SW11-SW13 ... semiconductor switch

Claims (2)

  Connect the electric double layer capacitor and the storage battery to the power supply using two changeover switches, connect the electric double layer capacitor and the storage battery in series at the time of discharging, and forward the diode to the charging battery in the charging current direction at the time of charging. A power storage device, wherein a series circuit and an electric double layer capacitor connected in series so as to be connected in parallel are connected in parallel.   The electric double layer capacitor and the storage battery are connected to the power supply using three semiconductor switches, and the electric double layer capacitor and the storage battery are connected in parallel during charging, and the electric double layer capacitor and the storage battery are connected in series during discharging. Connecting and discharging the electric double layer capacitor or storage battery by boosting the output voltage of the electric double layer capacitor or storage battery by controlling the semiconductor switch when the terminal voltage of the electric double layer capacitor or storage battery drops during discharging Power storage device.

Images