JP2004129455A - Series connection capacitor provided with self-supplementary charging function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a series connection capacitor provided with a self-supplementary charging function wherein when a plurality of capacitors connected in series are charged through an external charging circuit, voltage imbalance can be eliminated and maximum energy can be taken out. <P>SOLUTION: The series connection capacitor provided with a self-supplementary charging function comprises: a plurality of capacitors C101 to 106 connected in series; a common transformer T101 having a plurality of identical windings L101 to 106 connected for supplementarily charging a plurality of the capacitors; a plurality of switches SW101 to 106 which turn on and off the connections between a plurality of the windings of the common transformer and a plurality of the capacitors; and a switch control circuit B101 which generates a control signal for turning on and off a plurality of the switches at a high frequency in synchronization. If there is voltage imbalance among a plurality of the capacitors, a charging or discharging current is fed through a plurality of the windings of the common transformer connected with a plurality of the capacitors, and the voltages of the capacitors are thereby equalized. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides high-voltage large-capacity capacitors obtained by connecting a plurality of electric double-layer large-capacity electrolytic capacitors and lithium-ion batteries in series, and controls uniform voltage charging during charging even when the capacities of the capacitors are not uniform. As a result, the maximum energy can be stored up to the allowable voltage limit, and the stored energy can be effectively extracted by controlling the supplementary charge to a uniform voltage even during discharging.
[0002]
Therefore, in an electric vehicle using a lead storage battery, a lithium secondary battery, a polymer secondary battery, or an electric double-layer large-capacity electrolytic capacitor connected in series, the cruising distance of the electric vehicle can be extended to the limit.
Since the electric double layer large capacity electrolytic capacitor withstands repeated rapid charging and discharging, it can be replaced with a lead battery of an automobile by setting a withstand voltage of about 15 volts, and idling stop can be performed even in a current automobile.
[0003]
[Prior art]
The circuit for increasing the breakdown voltage of the electrolytic capacitor and absorbing the ripple current has the configuration shown in FIG.
It is divided into equal voltages by the resistors R1501 to 1503 connected in series, and is discharged through the resistors R1501 to 1503 when the voltage of the electrolytic capacitor C1501 to 1503 is high, and charged through the resistors R1501 to 1503 when the voltage of the electrolytic capacitor is low. Is performed, resulting in an equal voltage.
[0004]
FIG. 16 shows a circuit for performing equal voltage charging by a flyback type DC-DC converter. The detection voltages are equalized by making the secondary windings L1601 to 1603 of the flyback transformer T1601 the same number of turns, and as a result, each capacitor The device is charged to a uniform voltage.
[0005]
[Patent Document 1]
JP 2001-136660 A
[Problems to be solved by the invention]
In the prior art shown in FIG. 15, since the resistors R1501 to 1503 are constantly discharging, the uniform charging speed can be increased by reducing the resistance value. However, the energy discharged by the resistor increases, and the resistance value increases. However, there is a drawback that the uniform voltage operation is slowed down by increasing the discharge amount.
[0007]
Further, in the prior art shown in FIG. 16, the accumulated energy can be increased to the withstand voltage limit by the uniform voltage charging. However, if the capacities of the respective elements are unbalanced, the equal voltage discharge does not occur. There is a disadvantage that an element that is not charged or receives reverse charging before sufficient energy is taken out causes deterioration and destruction.
[0008]
Furthermore, since charging is performed only by the equalizing charging circuit, energy loss due to a forward drop voltage of the rectifying diodes CD1601 to 1603 is large, and there is a disadvantage that charging efficiency is greatly reduced.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a plurality of capacitors in which a capacitor whose terminal voltage increases in accordance with charging is connected in series, a common transformer connected to the capacitors for supplementary charging, the common transformer and the capacitor And a switch control circuit for generating a control signal for synchronously switching the switch at a high frequency, the switch control circuit being connected to the capacitor when a voltage is different between the capacitors. A charge or discharge current is passed through a plurality of windings of the common transformer, and the voltage of the capacitor is made substantially uniform.
In the present invention, the capacitors connected in series are charged by the external charging circuit. However, when an imbalance occurs in the individual capacitor voltages, the auxiliary voltage is charged from the high voltage capacitor to the low voltage capacitor. Energy can be stored.
Even in the case of discharging to an external load, a capacitor having a small capacity whose terminal voltage decreases quickly is supplemented by a capacitor having a large capacity, so that voltage imbalance can be eliminated and maximum energy can be extracted.
Since the auxiliary charging operates with respect to the unbalanced capacity, the load on the auxiliary charging circuit is small, and the switching operation improves the charging / discharging efficiency.
[0010]
In the above-described series-connected capacitor having a self-complementary charging function according to the present invention, the common transformer has a plurality of windings with a center tap (hereinafter referred to as a differential winding), and the switches are alternately switched. A differential winding and a differential switch are connected in series to one capacitor, or one differential winding is connected in series by sharing two capacitors and two differential switches.
According to the present invention, since the coupling between each capacitor and the transformer winding is a push-pull operation, the charging ON rate becomes almost 100%, and the auxiliary charging operation can be performed efficiently.
[0011]
In the above-described series-connected capacitor having a self-complementary charging function according to the present invention, the common transformer is divided into two or more, and each transformer has a secondary winding or is shared with a differential winding, and The transformer is connected in parallel with the same number of turns.
When the number of series capacitors increases, the number of windings cannot be secured with one shared transformer. However, by dividing the transformer and connecting the secondary windings in parallel, a large number of series capacitors can be connected.
[0012]
Further, in the series connection capacitor with self-supplementary charge function according to the present invention, the series connection capacitor includes a plurality of blocks each including the series connection capacitor with self-supplementary charge function, and one or more capacitors are shared between two or more blocks. It is characterized in that capacitors are connected in series.
By connecting a plurality of blocks, a large number of capacitors can be connected in series.
[0013]
Further, in the series-connected capacitor with a self-complementary charge function according to the present invention, the voltage of each capacitor is measured, and when a voltage difference occurs between the capacitors, switch control is activated, and a voltage difference occurs between the capacitors. When there is no switch control, the switch control is stopped.
[0014]
In the above-mentioned series connection capacitor with self-complementary charge function according to the present invention, charge / discharge current detection for detecting a charge current for charging the series connection capacitor with self-complementary charge function and a discharge current for discharging to a load circuit by an external charging circuit. A circuit is added, and switch control is activated at the time of charging / discharging.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an embodiment of the present invention. C101 to 106 are capacitors connected in series, TM101 is a plus terminal of the series connection capacitor, TM102 is a minus terminal of the series connection capacitor, T101 is a common transformer having windings L101 to L107, SW101 to SW106 are switches, CD101 is a rectifier diode, and B101 is a switch control circuit that generates a control signal for switching SW101 to SW106.
[0016]
FIG. 2 shows a more specific circuit, and FIG. 3 is an operation explanatory diagram.
A field effect transistor (hereinafter, referred to as an FET) is used for SW201 to SW206, and a switch control signal is distributed by a transformer T202.
Since the number of turns of the windings L201 to 206 of the transformer T201 is the same, when the FET switches SW201 to 206 are turned on and off at a high frequency in synchronization, the winding voltages at the time of ON are all the same, and the capacitors C201 to 206 Average voltage.
Therefore, when the voltage of the capacitor is different, the discharge current flows in the direction of the winding from the capacitor having the higher voltage, and the charging current flows to the capacitor having the lower voltage due to the back electromotive current due to the nature of the transformer. Will be the same.
When each switch is turned off at the same time, a counter electromotive voltage is generated by the magnetic energy stored in the common transformer T201, but energy is recovered for all the capacitors connected in series by the winding L207 and the rectifier diode CD201.
When the voltage of each capacitor becomes equal, the current flowing toward the winding of the transformer is only the current flowing to the inductance L of the transformer (windings L201 to 206).
I = e / L × t Equation (1)
I: Current value e; Capacitor voltage L; Transformer inductance t; Pulse ON time As can be seen from the equation (1), in order to suppress the current, the number of turns of the transformer winding is increased and the pulse ON time is reduced. Although it is desirable to increase the number of turns, the loss due to the winding resistance increases. Therefore, it is necessary to shorten the ON time of the pulse as much as possible, that is, to increase the ON-OFF frequency.
The pulse time integration value of the current-voltage product is the magnetic energy stored in the transformer, and the energy is recovered by the winding L207 and the rectifier diode CD201 as described above.
[0017]
FIG. 3 is an example of a winding voltage waveform when the number of windings of the winding L207 is six times that of the windings L201 to 206. For the ON time t1, the back electromotive voltage at OFF is almost the same as the forward voltage. The duration t2 is almost the same as t1.
[0018]
FIG. 4 shows another embodiment in which the push-pull operation is performed on the windings of the common transformer 20, and the number of turns is the same.
[0019]
FIG. 5 shows a more specific circuit, and FIG. 6 is an operation explanatory diagram.
Using two FETs for the differential switch, the pulse signal generated by the square wave generating circuit is distributed by the transformer T502 to each FET switch as a control signal.
In this method, the plus / minus voltage generated in the winding of the common transformer T501 is almost the average voltage of the voltages of the capacitors C501 to 506. As in the case of FIG. Flows, and a charging current flows to a capacitor having a low voltage, and the capacitor voltage becomes the same.
When the voltage of each capacitor becomes equal, the current flowing toward the winding of the transformer is only the AC current flowing to the inductance L (L501 to 506) of the transformer.
The waveform ratio of the ON-OFF and OFF-ON signals may be 50%, and the ON ratio becomes almost 100% because the coupling between each capacitor and the transformer winding is a push-pull operation, so that the auxiliary charging operation can be performed efficiently. I can do it.
Further, in this method, the magnetic energy stored in the transformer is automatically recovered in the opposite half cycle, so that the winding and the rectifier diode for recovering the energy are not required.
[0020]
FIG. 7 shows an example in which a common transformer is divided into three. If the number of series capacitors increases, the number of windings cannot be secured with one shared transformer, but as if one common transformer is connected in parallel with secondary windings, It will work like a trance.
In the example of FIG. 7, two series-connected capacitors are unitarily connected in series as one unit, but since each unit is independent, the connection order is arbitrary.
[0021]
FIGS. 8 and 9 show examples in which a plurality of self-complementary charging series-connected capacitor blocks are coupled by a shared capacitor. FIG. 8 shows two capacitors (C806 and 807) shared and capacitors connected in series.
In FIG. 8, when verifying the case where the voltage of the capacitor C801 is high and the voltage of C812 is low, C812 receives charging current from C806 to 811 via the common transformer T802, and C802 to 807 from C801 via the common transformer T801. To charge.
Accordingly, in C801 to 807, the voltage of C801 is high, and the voltage of C806 and C807 is low. In C806 to 812, the voltage of C806 and C807 is high and the voltage of C812 is low. As a result, C801 to C806 and C807 C812 is supplementarily charged.
In FIG. 9, the paths for auxiliary charging are multiplexed, and a large current can be achieved.
[0022]
When the voltages of all the capacitors become equal by the supplementary charge, the charge / discharge current decreases, and therefore the circuit loss also decreases.Thus, even if the supplementary charge operation is always performed, the loss is small. There is a method in which a supplementary charge operation is performed only when is unbalanced, or an unbalance occurs when charging / discharging by an external circuit.
[0023]
FIG. 10 shows an example of a circuit for detecting a voltage imbalance and performing a supplementary charging operation. FIGS. 11 and 12 show examples of a voltage imbalance detection circuit. FIG. 11 shows one sixth of the series voltage of six capacitors and each of them. Is obtained by amplifying the absolute value of the difference between the capacitor voltages and adding them. If all the values become equal, the output voltage becomes the midpoint voltage of the series capacitor.
[0024]
In FIG. 12, the series capacitor voltage is divided into six equal parts by six resistors R and twelve resistors r, an allowable error range is set by the resistor r, and an open collector type (or open drain type) comparator is used. The error is detected and synthesized by wired-OR. When all voltages are within the allowable range, the level becomes H level, and when even one of them exceeds the allowable range, the level becomes L level.
In response to this signal, the operation of the switch control circuit is turned on / off.
[0025]
FIG. 13 shows a configuration in which the charge / discharge current of a series-connected capacitor is detected by a current detection circuit to activate a switch control circuit. FIG. 14 shows an example of a current detection circuit.
A minute resistor R1401 is connected in series to a series-connected capacitor, and a charge / discharge current is detected by amplifying an absolute value of a voltage generated in the minute resistor.
If the charge / discharge current is zero, the output voltage will be the midpoint voltage of the series connected capacitors.
[0026]
Examples of the capacitor shown in the above embodiment include a capacitor whose terminal voltage rises as it is charged, a secondary battery, and the like, such as an electric double layer large capacity electrolytic capacitor, a lead battery, a lithium ion battery, and a polymer battery.
[0027]
【The invention's effect】
As described above, since the capacitor voltage can always be kept equal during charging / discharging of the series-connected capacitors by the supplementary charging operation, the maximum power can be stored and the maximum power can be taken out, and the imbalance in capacity can be achieved. Since the supplementary charging operation is performed by switching, the energy efficiency is increased.
7, 8, and 9, many capacitors can be connected in series, so that a capacitor of 2 to 3 volts can be a capacitor of several hundred volts, and the power efficiency of an electric vehicle or the like can be increased. Can be increased.
[Brief description of the drawings]
FIG. 1 is an embodiment of the present invention.
FIG. 2 is a specific circuit of the present invention.
FIG. 3 is a diagram illustrating the operation of the present invention.
FIG. 4 is another embodiment of the present invention.
FIG. 5 is another specific circuit of the present invention.
FIG. 6 is another operation explanatory view of the present invention.
FIG. 7 is an example in which a common transformer is divided into three parts.
FIG. 8 is an example in which a plurality of series-connected capacitor blocks with a self-complementary charging function are coupled by a shared capacitor.
FIG. 9 is an example in which a plurality of series-connected capacitor blocks with a self-complementary charging function are coupled by a shared capacitor.
FIG. 10 is an example of a circuit that performs a supplementary charging operation by detecting a voltage difference.
FIG. 11 is an example of a voltage difference detection circuit.
FIG. 12 is an example of a voltage difference detection circuit.
FIG. 13 is an example of activating a switch control circuit by detecting a charge / discharge current of a series-connected capacitor.
FIG. 14 is an example of a current detection circuit.
FIG. 15 is an example of a conventional equal voltage charging circuit using a resistor.
FIG. 16 is an example of a conventional equal voltage charging circuit using a flyback transformer.
[Explanation of symbols]
C101 to 106, 201 to 206, 401 to 406, 501 to 506, 701 to 706, 1001 to 1006, 1101 to 1106, 1201 to 1206, 1401 to 1406, 1501 to 1503, 1601 to 1606, capacitors CB801 and 802 , 901 to 903 ... series-connected capacitor blocks CD101, 201, 1601 to 1606 with self-supplementary charging function ... rectifier diodes B101, 201, 401, 501, 701 ... switch control circuits B202, 502 ... pulses Generating circuits L101 to 107, 201 to 207, 501 to 506, 1601 to 1606 ... Transformer windings SW101 to 106, 201 to 206, 401 to 406, 701 to 718 ... Switches T101, 201, 401, 501 , 70 1 to 703, 801 to 802 ... common transformer T202, 205 ... control signal distribution transformer T1601 ... flyback transformer TM101, 201, 401, 501, 701, 801, 1001, 1101, 1201, 1301, 1401 ... plus terminals TM102, 202, 402, 502, 702, 802, 1002, 1102, 1202, 1302, 1402 of series-connected capacitors-minus terminals R1401 of series-connected capacitors-minute resistors R1501 to 1503 ..Resistor for charging / discharging R: resistor r: resistor

Claims (6)

A plurality of capacitors connected in series with capacitors whose terminal voltage rises with charging;
A common transformer connected to the capacitor for auxiliary charging,
A switch for switching connection between the common transformer and the capacitor;
A switch control circuit for generating a control signal for switching the switch synchronously at a high frequency, wherein a plurality of the common transformers connected to the capacitor when the voltage between the capacitors is different by the switch control circuit. A series-connected capacitor with a self-complementary charging function, characterized in that a charging or discharging current flows through a winding to make the capacitor have an equal voltage. 2. The series-connected capacitor with a self-complementary charging function according to claim 1, wherein the common transformer has a plurality of windings with a center tap (hereinafter referred to as a differential winding), and the switches are switched alternately. Self-complementary charging, wherein a differential winding and a differential switch are connected in series to one of the capacitors, or one differential winding is connected in series by sharing two capacitors and two differential switches. Series connected capacitor with function. 3. The series-connected capacitor according to claim 1, wherein the common transformer is divided into two or more, and each transformer has a secondary winding or is shared with a differential winding. A series-connected capacitor with a self-complementary charging function, characterized in that the above-mentioned transformers are connected in parallel with the same number of turns. The series-connected capacitor with a self-complementary charging function according to any one of claims 1 to 3, comprising a plurality of blocks each including a series-connected capacitor with a self-complementary charging function. A series-connected capacitor with a self-complementary charging function, wherein the capacitor is shared and all the capacitors are connected in series. 5. The series-connected capacitor according to claim 1, wherein a voltage of each of the capacitors is measured, and when a voltage difference occurs between the capacitors, a switch control is started, and each of the capacitors is activated. A series-connected capacitor with a self-complementary charging function, wherein the switch control is stopped when no voltage difference occurs between them. 6. The series connection capacitor with a self-complementary charging function according to claim 1, wherein a charging current for charging the series connection capacitor with a self-complementary charging function and a discharge current for discharging to a load circuit are detected by an external charging circuit. A series-connected capacitor with a self-complementary charge function, characterized by adding a charge / discharge current detection circuit that activates switch control during charge / discharge.

Images