JPH11299112A - Series-parallel switching power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid a cross current which is produced by a potential difference between a pair of batteries, when the charging method of the pair of batteries are switched from the parallel connection charging to the series connection charging. SOLUTION: A power supply device has a pair of batteries C1 and C2 whose voltages are much changed in accordance with charge/discharge values and three switching means which are connected in series to the pair of batteries respectively. The connection of the pair of batteries are switched between the series connection and the parallel connection at a predetermined voltage. Unilateral control rectification devices Q1 and Q2 are connected in series at least to the pair of batteries C1 and C2 respectively as the switching means. The unilateral control rectification devices Q1 and Q2 are connected in the flowing directions of the charging currents of the batteries to limit excessive charging currents or to avoid a cross current which flows from the battery with a higher voltage to the battery with a lower voltage at the time of charging.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pair of batteries whose voltage varies greatly according to the amount of charge and discharge, and a pair of batteries connected in series and connected between the series connection points.
The present invention relates to a series-parallel switching power supply device that is provided with two switching units and configured to switch the pair of batteries to a parallel connection or a series connection at a predetermined voltage by the three switching units.

[0002]

2. Description of the Related Art ECS using an electric double layer capacitor
(Energy Capacitor System) has attracted attention as a power supply device for electric vehicles and a large-scale power storage device. Electric double layer capacitors can be rapidly charged by physical charging, like other capacitors, compared to chemical batteries that take a long time to charge, such as lead batteries and nickel-cadmium batteries. Moreover, the electric double-layer capacitor battery has a great advantage over a chemical battery in that a large amount of energy can be stored. However, a chemical battery is a constant voltage device.In a normal operating range, even if power is supplied to a load, its terminal voltage shows almost constant constant voltage characteristics regardless of the amount of energy stored in the battery. Therefore, the electric double-layer capacitor battery requires a large amount of stored power to use it effectively.
= Has the characteristic that the terminal voltage varies greatly based on the relation of CV ^2/2. Therefore, as the stored energy is discharged, the terminal voltage greatly changes from the full charge voltage to zero, and a large output voltage adjustment is required by the ECS to supply a stable rated voltage to the load.

[0003] ECS is a power energy storage system comprising a capacitor, a parallel monitor and a current pump.
3, Denki Kagaku B, Vol. 115, No. 5, 1995, p.
10 etc.). Here, the parallel monitor is
In this device, a plurality of capacitors are connected between terminals of each capacitor of a capacitor bank connected in series and parallel, and a charging current is bypassed when a charging voltage of the capacitor bank exceeds a set value of a parallel monitor.

[0004] The capacitor bank having the parallel monitor bypasses the charging current so as to prevent the charging voltage of the capacitor bank from rising above a set value when charging, so that all capacitors in the capacitor bank are kept constant. The capacitor is charged evenly to the set voltage, and the storage capacity of the capacitor can be exerted almost 100%. Therefore, even if there are variations in the characteristics of the capacitors and the magnitude of the residual charge, the parallel monitor performs equalization of the maximum voltage, prevention of backflow, detection and control of the charge termination voltage, etc. As a thing,
It has an extremely important role and is an indispensable device for effective use of energy density.

FIG. 4 is a diagram showing a standard configuration example of the ECS.
FIG. 5 is a diagram showing a step-up / step-down operation region of the ECS current pump. In the power storage device based on ECS, as shown in FIG. 4, power is taken out from an electric double layer capacitor storing power by a switching type DC / DC converter called a current pump, and supplied to a load at a constant voltage. The current pump used at this time is a step-down chopper,
A boost chopper or another DC / DC converter may be used, but a type using a transformer is not advantageous because high efficiency is an essential condition.

Now, in an ECS-based power storage device, if it is attempted to use the capacitor voltage up to 1/4 of the voltage when fully charged, the power is 15/16 = 93.75%.
Will be used. When implementing it in the boost converter, the output voltage V _O to select fully equal to the charge voltage V _O ^* 4 at the converter output boosts is always V _O ^* 4 in as shown in up to 5 Control may be performed as follows. At this time, the operation range of the boost converter is boosted from 1 to 4 times. In a step-down converter, the output voltage V _O
5 is selected to be equal to 1/4 of the voltage V _O ^* 1 when fully charged.
As shown in the down of FIG.
If the voltage is reduced to 4 and the step-down ratio is reduced along with the discharge to control the output to always be V _O ^* 1, the rated voltage can be supplied until the voltage of the capacitor becomes the first quarter. The operation range of the step-down converter at this time is step-down from 1/4 to 1.

As described above, in the ECS, the voltage range of the capacitor to be used is widened to increase the amount of electric power that can be stored, so that a significant change in the terminal voltage of the capacitor is an essential phenomenon. However, depending on the application, it may be inconvenient for the ECS to significantly change the voltage as compared with the conventional secondary battery.

Therefore, as a battery having a large voltage fluctuation in which the voltage gradually decreases as energy is taken out from the fully charged state, for example, a power supply device using an electric double-layer capacitor, the batteries are connected in series and parallel in order to make the power supply side voltage constant. A configuration in which switching is performed has already been proposed (Japanese Unexamined Patent Application Publication No.
No. 8182). FIG. 6 is a diagram showing a configuration example of a series-parallel switching power supply device, which includes a plurality of capacitor batteries C1 and C2 having large voltage fluctuations and a changeover switch Sp1 for switching these from parallel connection to series.
Sp2, Ss1 and control means (ECS) for switching and controlling the voltage or current supplied from the capacitor batteries C1, C2 to the load.
2. By Ss1, the capacitor batteries C1 and C2 are switched from parallel connection to series connection as the voltage decreases. Therefore, the changeover switches Sp1, Sp
2, the changeover switch Ss1 is operated complementarily.

According to the conventional apparatus proposed above, the step-down ratio and the step-up ratio can be reduced by using a step-down converter or a step-up converter as the control means. Efficiency can be improved. Further, the degree of freedom in selecting a semiconductor to be used and the degree of freedom in designing can be increased, so that the economical efficiency of the device can be improved.

[0010]

However, in the conventional series-parallel switching power supply, the changeover switches Sp1, Sp2,
Although a relay or a power MOSFET is used as Ss1, the following problem occurs when the capacity is increased. One is that if the capacity is too large to be handled by a relay or a power MOSFET, the element used as a switch becomes a problem, and the other is that the capacitor batteries C1, C2
When charging 2 by switching from series connection to parallel connection,
If the voltages of the two capacitor batteries C1 and C2 are not the same, a cross current flows at the moment of parallel connection. Such a cross current is not negligible especially in a large-capacity device.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a cross current flows due to a voltage difference between batteries when a pair of batteries is switched from parallel connection charging to series connection charging. It is to prevent that.

For this purpose, the present invention comprises a pair of batteries whose voltage varies greatly according to the charge / discharge amount, and three switching means connected in series to the pair of batteries and connected between the series connection points, respectively. In the series-parallel switching power supply device configured to switch the pair of batteries to a parallel connection or a series connection at a predetermined voltage by the three switching units, a unidirectional control is performed on at least the switching units respectively connected in series to the pair of batteries. A rectifying element is constituted by a parallel circuit in which a rectifying element in the opposite direction is connected in parallel to the rectifying element, and the one-way control rectifying element is connected in a direction in which a discharging current flows from the battery and in a direction in which a charging current flows in the battery. To limit the flow of an excessive charging current.

[0013] Further, at least the switching means connected in series to the pair of batteries, respectively, is constituted by a parallel circuit comprising a pair of unidirectional control rectifiers connected in the reverse direction, and a unidirectional control of the pair of the parallel circuits. Among the rectifiers, the unidirectional control rectifier in the direction in which the discharge current flows from the battery is non-uniform while the voltage of the pair of batteries is not uniform when the pair of batteries is switched from series connection to parallel connection and charged. It is characterized in that the conductive state is controlled.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a series-parallel switching power supply device according to the present invention, wherein C1 and C2 are batteries, D1 to D3 are rectifying elements, Q1 to Q3, Q11, and Q2.
Reference numeral 2 denotes a unidirectional control rectifier, and L1 and L2 denote current limiting circuits.

In FIG. 1A, batteries C1 and C2 are:
For example, each is composed of an electric double layer capacitor or a capacitor bank in which a plurality of electric double layer capacitors are connected in series and parallel, and a parallel circuit of rectifying elements D1 and D2 and unidirectional control rectifying elements Q1 and Q2 is connected in series to each of them. Further, a parallel circuit of a rectifying element D3 and a unidirectional control rectifier element Q3 is connected between these series connection points, and the on / off control of Q1 to Q3 of these unidirectional control rectifier elements controls the battery. C1 and C2 are switched between series connection and parallel connection. Therefore, when a parallel circuit of the rectifying element D1 and the unidirectional control rectifying element Q1 is connected to the positive electrode side of the battery C1, the parallel circuit of the rectifying element D2 and the unidirectional control rectifying element Q2 becomes opposite to the negative electrode side of the battery C2. Connect to The rectifiers D1 and D2 are connected to polarities in the direction in which a discharge current flows from the batteries C1 and C2, respectively. Conversely, the unidirectional control rectifiers Q1 and Q2 are connected to the batteries C1 and C2, respectively.
C2 is connected to the polarity in the direction in which the charging current flows. In the parallel circuit connected between the series connection points, the unidirectional control rectifier Q3 is connected in series from the batteries C1 and C2, and the polarity is set so that the discharge current flows, and the rectifier D3 is connected to the batteries C1 and C2.
To the polarity of the direction in which the charging current flows in series. The current limiting circuits L1 and L2 are circuits that limit the flow of excessive charging current to the batteries C1 and C2.

The series-parallel switching power supply according to the present invention, as described above, replaces the configuration using a conventional switch as the switching means for switching the batteries C1 and C2 to parallel connection or series connection in accordance with the voltage fluctuation. A parallel circuit configuration of rectifying elements D1 to D3 and unidirectional control rectifying elements Q1 to Q3 is adopted, and the battery C is controlled by the unidirectional control rectifying elements Q1 and Q2.
1, to control the charging current when C2 is connected in parallel. In other words, the unidirectional control rectifiers Q1, Q2 have the polarities in the direction in which the charging current flows to the batteries C1, C2, respectively.
When the batteries C1 and C2 are switched from series connection to parallel connection because the unidirectional control rectifiers Q1 and Q2 are controlled by the current limiting circuits L1 and L2 to limit the flow of excessive charging current. Can be prevented from flowing an excessively large charging current, and as a result, a large cross current can be prevented from flowing due to the voltage difference between the batteries C1 and C2.

Next, the connection switching control and the charging current control by the unidirectional control rectifiers Q1 to Q3 according to the process of discharging the batteries C1 and C2 from a fully charged state and then charging them again will be described. When the batteries C1 and C2 both start discharging from a fully charged state, if the unidirectional control rectifier Q3 is off, the battery C1 is connected to the rectifier D1 and the battery C2 is connected to the rectifier D2. Are connected in parallel to the outputs via the respective outputs, and power can be supplied to the outputs from both of them.
1, Q2 may be on or off.

First, when the discharge proceeds in parallel from the batteries C1 and C2 and the output voltage drops to half the voltage at the time of full charge,
The unidirectional control rectifier Q3 is turned on, the unidirectional control rectifiers Q1 and Q2 are turned off, and the batteries C1 and C2 are connected in series. When the discharge proceeds from this state until the output voltage further decreases to half the voltage at the time of full charge, batteries C1 and
This means that 15% of the initial total charged amount was used as electric power until C2 reached 1/4 of the total total voltage at the time of full charge.

In the process of reverse charging from full discharge, the unidirectional control rectifier Q3 is turned on and the unidirectional control rectifier Q3 is turned on.
1, Q2 is turned off and batteries C1, C2 are connected in series. Charging starts from this state, and the battery C1,
When the total voltage of C2 connected in series becomes equal to the voltage of each of the batteries C1 and C2 when fully charged, the unidirectional control rectifier Q3 is turned off, the unidirectional control rectifiers Q1 and Q2 are turned on, and the batteries C1 and C2 are turned on. Are connected in parallel.

At this time, similarly to the conventional switch, a switch composed of a parallel circuit of a rectifier D1 and a unidirectional control rectifier Q1 and a rectifier D2 and a unidirectional control rectifier Q
When the switches composed of the parallel circuits of the two are turned on at the same time, that is, when the unidirectional control rectifiers Q1 and Q2 are turned on at the same time, the voltages of the batteries C1 and C2 at this time are not actually the same. A cross current flows due to the difference between the voltages. There is no problem in ignoring such a cross current in a small-sized device, or in a measure of limiting current. However, in a large-sized device, there is usually no large margin for the stress of components and circuits.

The series-parallel switching power supply according to the present invention controls the unidirectional control rectifiers Q1 and Q2 by the current limiting circuits L1 and L2 when the batteries C1 and C2 are switched from series connection to parallel connection in the charging process. To limit the flow of excessive charging current, and temporarily interrupt the charging current. As a result, a cross current flows based on the difference between the charging voltages of the batteries C1 and C2. This is to prevent this. Therefore, for example, when thyristors or GTOs are used as the unidirectional control rectifiers Q1 and Q2, they are turned on / off by a switching method to control the effective current to be equal to or less than the limit value, and when IGBTs are used, they are analog-like. Can also be controlled,
It can also be controlled so as to have a constant current. The current limiting circuits L1, L2 are, for example, unidirectional control rectifiers Q1, Q
2. A means for detecting the current flowing through the power supply 2 may be used, and the current may be limited so that the detected current is equal to or less than the maximum charging current. In place of the means for detecting the current, a means for detecting heat generation is provided. May be adopted. The detection of these excessive currents is determined not by the unidirectional control rectifiers Q1 and Q2 but by the batteries C1,
It goes without saying that the same is true even if the operation is performed in C2.

Further, as shown in FIG. 1A, the unidirectional control rectifiers Q1, Q2 are controlled by the current limiting circuits L1, L2.
(Or one of the unidirectional control rectifiers Q1 and Q2 so as to limit the current by detecting an excessive current flowing through the batteries C1 and C2).
, A circuit in which a cross current flows directly may be cut off. FIG. 1 shows an example of the configuration.
1B, a unidirectional control rectifier Q11, Q21 is connected in place of the rectifiers D1, D2 shown in FIG. 1A to prevent a cross current from flowing. Therefore, the unidirectional control rectifiers Q11 and Q21 are turned off at least for a certain period of time after the batteries C1 and C2 are switched to the parallel connection during charging, that is, until the non-uniform state of the voltages of the batteries C1 and C2 is eliminated. . Therefore, the batteries C1, C
Control may be performed so that the unidirectional control rectifiers Q11 and Q21 are turned off during the charging mode, including a time period during which the voltage non-uniformity is eliminated from the time point when the second charging is switched from the series charging to the parallel charging. , The charging voltage is detected according to the charging pattern until the charging voltage reaches a predetermined charging voltage, or the batteries C1 and C
The unidirectional control rectifiers Q11 and Q21 may be controlled so as to be turned off while the voltage of No. 2 is detected and the voltage is not uniform. By doing so, the unidirectional control rectifiers Q1 and Q2 can be turned on according to the switching timing from the series connection to the parallel connection without any consideration of the degree of non-uniformity of the voltage of the batteries C1 and C2. Good.

Next, as the series-parallel switching power supply according to the present invention, there is provided a power supply configured so as to reduce the voltage fluctuation width by connecting the battery units composed of a pair of batteries shown in FIG. explain. This is to switch the serial / parallel switching power supply from parallel connection to series connection step by step when the voltage is reduced by discharge. FIG. 2 is a diagram showing a configuration example of a series-parallel switching power supply device in which the series-parallel switching power supply device according to the present invention is connected in series in four stages, and FIG. 3 is a diagram for explaining an operation comparison example with a conventional capacitor power supply device. It is. In FIG. 2, the series-parallel switching power supply has a stage number n of 4
And four series-parallel switching capacitor units (battery units) 1, 11, 21, 31 connected in series.
1 in the fully charged state are connected in parallel, and the voltage is 1 /
Each time the value decreases by (n + 1), the serial connection is switched from the parallel connection to the serial connection one by one, such as the series-parallel switching capacitor unit 1 and then the series-parallel switching capacitor unit 11. Therefore, assuming that the full charge voltage V _CF of each capacitor bank of the series-parallel switching capacitor unit is 30 V, the upper limit value V _U of the fluctuating voltage is 120 V in 30 V × 4 stages, and the lower limit value V _L of the fluctuating voltage is 1 /
(N + 1), that is, 96 lower by a voltage corresponding to 1/5
V. Therefore, in the conventional device that switches from parallel connection to series connection when the voltage of the capacitor bank decreases to half of the full charge voltage, 120
In the range between V and 1/2 V of 60 V, that is, 50%, in the above-described multi-stage switching, 120 V is applied.
And 96V, that is, 20%.

Actually, in the series-parallel switching of the first series-parallel switching capacitor unit 1, there is a fluctuation of 24 V. However, after the second series-parallel switching capacitor unit 11, each capacitor bank is further discharged. Therefore, the fluctuation width gradually decreases as shown in FIG. In FIG. 3, 0 is a device without serial / parallel switching, 1
Shows a comparative example of voltage fluctuations of a conventional device for performing serial-parallel switching and a device 4 for performing four-stage switching of the serial-parallel switching capacitor unit according to the present invention.

As shown in FIG. 2, when the comparators A1 to A31 are connected to the respective series-parallel switching capacitor units to detect the switching voltage, the setting of the switching voltage of each of the comparators A1 to A31 is performed, for example, in the first stage. The eye is 24.2V, the second stage is 21.3V, and the third stage is 1
9.5V, and the fourth stage becomes 13.2V. In this way, even if each capacitor bank is fully charged evenly, the state of charge of each stage of the capacitor bank becomes uneven with the discharge. Serial-parallel switching may be performed. In other words, each stage may be operated reversibly by charging and discharging. When performing reversible charging, when switching from series to parallel,
If there is a voltage difference between the capacitor banks, a large cross current flows based on the voltage difference, and the present invention prevents such a transient large current from flowing as described above. Is what you do.

In the power supply device in which the n-stage series-parallel switching capacitor units are connected in series as described above, the upper limit value V _U of the fluctuating voltage is determined by the full charge voltage V _CF of the capacitor banks C11 to Cn2 and the series-parallel switching capacitor unit. 1 to n
From the number n of stages, V _U = V _CF × n
Can be obtained by Also, the lower limit value V of the fluctuating voltage
_L is such that the output voltage when only the first series-parallel switching capacitor unit 1 becomes a series connection circuit of the capacitor banks C11 and C12 is changed from V _L to V _U , so that V _L = V
_U− V _U / (n + 1). That is,
The variation width (V _U -V _L ) of the output voltage V _O is 1 / (n +
1). Therefore, if the number of stages n is 4 as described above, the fluctuation width is 20%.

It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible. For example, in the above embodiment, the conventional series-parallel changeover switch is configured by a parallel circuit of a unidirectional control rectifier and a rectifier, but such a parallel circuit is used only for a series-parallel changeover switch connected in series to a battery. You may do so. The reason is that when the battery unit is switched from series connection to parallel connection and charging is continued, a cross current flows based on a difference in battery voltage by preventing a transient excessive charging current from flowing in each battery. This is because we try to prevent Therefore, the series-parallel changeover switch connected between the series connection point of the battery and the series-parallel changeover switch may use a relay or a bidirectional control rectifier.

[0028]

As is apparent from the above description, according to the present invention, as a switching means connected in series to a pair of batteries whose voltage greatly changes according to the charge / discharge amount, the switching means is connected to the unidirectional control rectifying element. The rectifiers are connected in parallel by connecting rectifiers in the same direction.The rectifiers are connected in the direction in which the discharge current flows from the battery, and the unidirectional control rectifiers are connected in the direction in which the charge current flows in the battery. To prevent
When charging by switching from series connection to parallel connection, it is possible to prevent a cross current from flowing based on a voltage difference. Further, as a switching means connected in series to the pair of batteries, a parallel circuit composed of a pair of unidirectional control rectifiers connected in the opposite direction is configured, and the unidirectional control rectifier in the direction of flowing the discharge current connects the batteries of the pair. When switching from series connection to parallel connection and charging, the battery is controlled to be in a non-conductive state while the voltage of the pair of batteries is not uniform, so that a cross current can be prevented from flowing.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a series-parallel switching power supply device according to the present invention.

FIG. 2 is a diagram showing a configuration example of a series-parallel switching power supply device in which series-parallel switching power supply devices according to the present invention are connected in series in four stages.

FIG. 3 is a diagram for explaining an operation comparison example with a conventional capacitor power supply device.

FIG. 4 is a diagram showing an example of a standard configuration of an ECS.

FIG. 5 is a diagram showing a step-up / step-down operation region of the ECS current pump.

FIG. 6 is a diagram illustrating a configuration example of a series-parallel switching power supply device.

[Explanation of symbols]

C1, C2: battery, D1 to D3: rectifier, Q1 to Q
3, Q11, Q22 ... unidirectional control rectifier, L1, L2
… Current limiting circuit

 ──────────────────────────────────────────────────続 き Continuing from the front page (71) Applicant 000004271 3-1-2-2 Musashino, Akishima-shi, Tokyo (72) Inventor Dio Okamura 2--19-6 Minami-ota, Minami-ku, Yokohama-shi, Kanagawa ( 72) Inventor Masaaki Oshima 4-1 Egasaki-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside the Electric Power Research Laboratory, Tokyo Electric Power Company (72) Inventor Masaaki Yamagishi 1-1-1, Fukuura, Kanazawa-ku, Yokohama-shi, Kanagawa Power System Co., Ltd. (72) Inventor Akinori Mogami 3-1-2, Musashino, Akishima-shi, Tokyo Japan Electronics Co., Ltd.

Claims (4)

[Claims] 1. A battery comprising a pair of batteries whose voltage greatly changes in accordance with the amount of charge and discharge, and three switching means connected in series to the pair of batteries and connected between the series connection points, respectively. Means for switching the pair of batteries to a parallel connection or a series connection at a predetermined voltage, wherein at least the switching means connected in series to the pair of batteries is reversed to a unidirectional control rectifier. A rectifying element in parallel with a parallel circuit, and connecting the rectifying element in a direction in which a discharging current flows from the battery and connecting the unidirectional control rectifying element in a direction in which a charging current flows in the battery. A series-parallel switching power supply device configured to limit the flow of an excessive charging current. 2. The series-parallel switching power supply according to claim 1, wherein the battery is an electric double layer capacitor. 3. A battery comprising a pair of batteries whose voltage greatly changes in accordance with the amount of charge and discharge, and three switching means connected in series to the pair of batteries and connected between the series connection points, respectively. A series-parallel switching power supply device configured to switch the pair of batteries to a parallel connection or a series connection at a predetermined voltage by means of at least a pair of switching units connected in series to at least the pair of batteries in the reverse direction. A parallel circuit composed of a unidirectional control rectifier element, and a unidirectional control rectifier element in a direction in which a discharge current flows from the battery among the unidirectional control rectifier elements of the pair of the parallel circuit connects the batteries of the pair in series. A series-parallel switching power supply device, characterized in that when switching from connection to parallel connection and charging, the series-parallel switching power supply is controlled to be in a non-conducting state while the voltage of the pair of batteries is uneven. 4. The series-parallel switching power supply according to claim 3, wherein the battery is an electric double layer capacitor.