JP2001078441A - Switching power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable parallel operation type switching power supply device which can quickly cope with an abnormality. SOLUTION: A plurality of converters A and B include switching circuits 1 and output rectifying/smoothing circuits 7 respectively, and the output sides of the plurality of converters A and B are connected in parallel with each other to constitute a load connection terminal To. An output voltage detection circuit 4 detects the voltage of the load connection terminal To and output an output voltage signal to a control circuit 10. An overvoltage detection circuit 6 detects the output voltages of the plurality of converters A and B, and if one of the output voltages of the plurality of converters A and B is an overvoltage, output an overvoltage signal to the control circuit 10. The control circuit 10 controls a switching circuit 1 according to the output voltage signal, so as to stabilize the voltage of the load connection terminal To, and if the overvoltage signal is outputted, causes the output of the switching power supply device to stop.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching power supply of a parallel operation system in which a plurality of converters are connected in parallel to each other, and a plurality of converters are controlled by a common control circuit to supply power to a load.

[0002]

2. Description of the Related Art Switching power supply devices have a small size, light weight and high efficiency, and their applications are expanding in various fields of industrial equipment and consumer equipment including computers and office automation equipment. As such applications have expanded, specifications required for switching power supply devices have also been diversified. To meet such demands, switching power supply devices of various specifications have been developed, but from the viewpoint of shortening the development period, reducing development costs, standardization, etc., various types of switching power supply devices are combined with existing switching power supply devices. 2. Description of the Related Art Switching power supply devices that meet specifications have been provided. In particular, in the field of large computers and industrial equipment that require a large amount of power, a parallel operation system that secures power capacity and improves reliability at the same time by connecting a plurality of switching power supplies in parallel with each other Is attracting attention.

In such a switching power supply of the parallel operation system, if there is a difference between the output currents (converted power) of the plurality of switching power supplies, the load is concentrated on a specific switching power supply, and the reliability is reduced. Or the size of the device is increased.

Therefore, various methods have been proposed so that the switching power supplies connected in parallel can share the output power evenly. One of them is the invention disclosed in Japanese Patent Laid-Open No. Hei 10-229676 proposed by the present inventors. The invention disclosed in this publication is a switching power supply of a parallel operation system in which a plurality of resonance-type converter circuits are connected in parallel to form a load connection end, and a resonance circuit of each converter circuit is also connected. Device. In this switching power supply, the voltage at the load connection end can be detected and used as the output voltage signal of the switching power supply. In a plurality of converter circuits,
The impedances of the resonance circuits viewed from the switching element side can be made substantially equal to each other. Therefore, a plurality of converter circuits can be operated synchronously at the same frequency with a common control circuit, and the output voltage of the switching power supply device can be stabilized without performing special control.
This has the advantage that the output current of each converter circuit can be made uniform.

[0005] However, in a parallel operation type switching power supply configured to equalize the output current of each of the converter circuits connected in parallel, the converter circuit whose connection with the load is disconnected among the plurality of converter circuits is provided. In such a case, there is a problem that the converter circuit is in an overvoltage state.

That is, the converter circuit whose connection to the load has been cut off also performs substantially the same operation by a signal from the same control circuit as the other converter circuits. Therefore,
In a converter circuit disconnected from the load, current flows through the resonance circuit to the primary side of the transformer, but no load current flows to the secondary side of the transformer because no load is connected. For this reason, the voltage of the output capacitor rises to the peak voltage on the secondary side of the transformer, and becomes an overvoltage state.

At this time, if overvoltage detection is performed only at the load connection end in order to utilize the control by the common control circuit, the overvoltage cannot be detected in the converter circuit disconnected from the load. , The overvoltage condition continues. For this reason, there has been a problem that circuit damage and other problems due to the overvoltage are caused, and the reliability of the switching power supply device is reduced.

The switching power supply of the parallel operation system is
In the manufacturing process, besides shipping as a completed power supply device in which a plurality of power supplies are connected in parallel, a power source user may connect a plurality of converters in parallel. In the latter, a connector, a cable, a bus bar, or the like is used as a connection member. Generally, by connecting these members to input / output terminals of a converter, a switching power supply device of a parallel operation system is configured.

For this reason, it is not possible for the user of the power supply to eliminate erroneous wiring connection, forgetting to connect, and the like. Further, even when the wiring is correctly performed, there is no accident such as disconnection of the wiring during operation. For this reason, the above-mentioned problem of overvoltage cannot be eliminated at all, which has been a major problem from the viewpoint of the reliability of the power supply device.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a switching power supply device of a parallel operation type capable of promptly taking measures against an abnormality even if an abnormality occurs in the parallel connection and an overvoltage occurs in the converter. It is.

Another object of the present invention is to provide a highly reliable switching power supply of a parallel operation system capable of preventing circuit damage due to the occurrence of overvoltage and other problems beforehand.

It is another object of the present invention to provide a small-sized, low-cost switching power supply of a parallel operation system which can be constituted by adding one control circuit to a general-purpose converter.

[0013]

In order to solve the above-mentioned problems, a switching power supply according to the present invention comprises a plurality of converters, an output voltage detection circuit, an overvoltage detection circuit,
And a control circuit.

Each of the plurality of converters includes a switching circuit and an output rectifying / smoothing circuit, and outputs are connected in parallel to each other to form a load connection terminal.

The switching circuit switches the supplied DC voltage.

The output rectifying / smoothing circuit rectifies and smoothes a switching output supplied from the switching circuit, and outputs a DC voltage to the load connection terminal.

The output voltage detection circuit detects a voltage at the load connection terminal, and outputs an output voltage signal to the control circuit.

The overvoltage detection circuit detects an output voltage of each of the plurality of converters, and outputs an overvoltage signal to the control circuit when at least one of the plurality of converters is in an overvoltage state. The control circuit controls the switching of the switching circuit so that the voltage of the load connection terminal is stabilized based on the output voltage signal, and when the overvoltage signal is output,
Stop the output of the switching power supply.

In the above-described switching power supply according to the present invention, the output sides of the respective converters are connected in parallel with each other to form a load connection end. Further, each converter includes a switching circuit and an output rectifying / smoothing circuit. In each converter, the switching circuit switches the supplied DC voltage.

The output rectifying and smoothing circuit rectifies and smoothes a switching output supplied from the switching circuit, and outputs a DC voltage to the load connection terminal.

The output voltage detection circuit detects a voltage at the load connection terminal and supplies an output voltage signal to the control circuit.

The control circuit controls the switching of the switching circuit so that the voltage at the load connection terminal is stabilized based on the output voltage signal. Therefore, it is possible to obtain a switching power supply device that employs a parallel operation method and supplies a stable DC voltage to a load. This configuration also shows that it can be configured by adding one control circuit to a plurality of general-purpose converters. This is advantageous for reducing the size and cost of the switching power supply device, and further has effects such as shortening the development period of the switching power supply device and facilitating inventory management.

In the switching power supply of the present invention, the overvoltage detection circuit detects an output voltage of each of the plurality of converters, and outputs an overvoltage signal to the control circuit when at least one of the plurality of converters is in an overvoltage state. Is output. The control circuit stops the output of the switching power supply when the overvoltage signal is output.

Therefore, in the switching power supply of the present invention, when an abnormality occurs in the parallel connection of a plurality of converters and an overvoltage occurs in any one of the converters, the output of the switching power supply is stopped. Can be done quickly. Also, circuit damage due to the occurrence of overvoltage,
Other problems can be prevented beforehand. Therefore, the reliability of the switching power supply of the present invention is high.

[0025]

FIG. 1 is a block diagram schematically illustrating an embodiment of a switching power supply according to the present invention. The switching power supply of this embodiment includes a plurality of converters A and B, an output voltage detection circuit 4, an overvoltage detection circuit 6, and a control circuit 10. In the figure, reference numeral 1
1 is a DC voltage source. As the DC voltage source 11, any of a battery, another DC voltage source, and a voltage obtained by converting an AC voltage into a DC through a rectifying and smoothing circuit can be used. The rectifying and smoothing circuit may be provided as a part of a converter described later, or may be an external element.

The output sides of the converters A and B are connected in parallel with each other to form a load connection end T0. In the embodiment, each of the converters A and B is supplied with the DC voltage Vin from the DC voltage source 11. Converter A,
The parallel connection of B uses a method of connecting the input / output terminals of the converters A and B to the output terminal of the DC voltage source 11 and the input terminal of the load 12 by using connection members such as connectors, cables, and bus bars, respectively. , B by connecting the terminal blocks with the connecting members, and then connecting them together to the output terminal of the DC voltage source 11 and the input terminal of the load 12, or convert each of the converters A, B inside the switching power supply.
Any method can be adopted, such as a method of connecting the spaces by the connection member or the printed wiring pattern.

Each of converters A and B includes a switching circuit 1 and an output rectifying / smoothing circuit 7. The converters A and B have the same circuit configuration in the present embodiment, and therefore, the converter A will be representatively described.

In the converter A, the switching circuit 1 switches the supplied DC voltage Vin.
More specifically, the switching circuit 1 includes at least one switching element 110, and switches the supplied DC voltage Vin by the switching element 110. The output rectifying and smoothing circuit 7 rectifies and smoothes the voltage supplied from the switching circuit 1 and outputs a DC voltage to the load connection terminal T0. Converter B has the same circuit configuration as converter A, and thus outputs a DC voltage to load connection terminal T0, similarly to converter A.

The output voltage detection circuit 4 detects the voltage at the load connection terminal T0 and outputs an output voltage signal to the control circuit 10. In this embodiment, the voltage of the load connection end T0 is detected via the voltage dividing resistors R1 and R2 connected to the load connection end T0,
The divided voltage is output to the control circuit 10 as an output voltage signal.

The overvoltage detection circuit 6 detects the output voltage of each of the plurality of converters A and B via the overvoltage sense lines 61A and 61B. Further, the overvoltage detection circuit 6
Supplies an overvoltage signal to the control circuit 10 when at least one of the plurality of converters A and B is in an overvoltage state.

The control circuit 10 includes control lines 10A, 10B
Switching circuit 1 for a plurality of converters A and B
And supplies a control signal to the switching element 110 included in the switching circuit 1. The control circuit 10 controls the switching of the switching elements 110 of the converters A and B based on the output voltage signal supplied from the output voltage detection circuit 4 so that the voltage at the load connection terminal T0 is stabilized.

According to the above-described configuration, a switching power supply device that is of a parallel operation type and supplies a stable DC voltage to a load can be obtained. This configuration also indicates that by adding one control circuit to a plurality of general-purpose converters, it is possible to configure a switching power supply device of a parallel operation system in which one control circuit is shared by a plurality of converters. The switching power supply device of the parallel operation system having such a configuration is advantageous for miniaturization and cost reduction.
This has the effect of shortening the development period and facilitating inventory management.

The control circuit 10 also includes an overvoltage detection circuit 6
When the overvoltage signal is supplied from the irrespective of the supply of the output voltage signal from the output voltage detection circuit 4, the operation of the switching element 110 included in the switching circuit 1 of the plurality of converters A and B is stopped, or Control to lower the output voltage.

In the switching power supply of this embodiment, for example, when a converter whose connection to the load 12 is disconnected occurs, the load current does not flow through the converter, so that the output voltage rises and an overvoltage state occurs. At this time, the overvoltage detection circuit 6 supplies an overvoltage signal to the control circuit 10. When the overvoltage signal is supplied from the overvoltage detection circuit 6, the control circuit 10 controls the switching elements 110 included in the switching circuits 1 of the plurality of converters A and B regardless of the output voltage signal from the output voltage detection circuit 4. Control is performed to stop the operation or reduce the output voltage.

As described above, in the switching power supply of this embodiment, an abnormality occurs in the parallel connection of the converters A and B,
When the output voltage of at least one of the plurality of converters A and B is in an overvoltage state, the output is stopped, so that the measures against the abnormality can be promptly and reliably performed.

Moreover, since the overvoltage state does not continue, circuit damage and other problems due to the occurrence of the overvoltage can be prevented beforehand, and a highly reliable switching power supply can be obtained.

In the switching power supply of the present invention,
The number of converters connected in parallel is not limited to two, and the number is not limited as long as it is two or more. The conversion type can be used regardless of the forward type or the flyback type.

FIG. 2 is a diagram showing a specific circuit configuration of the converter A in another embodiment of the switching power supply according to the present invention, and FIG. 3 is a specific diagram of a converter B combined with the converter A shown in FIG. FIG. 2 is a diagram showing a simple circuit configuration. In the figure, the same reference numerals as those in FIG. 1 indicate the same components. The wirings (ak) illustrated in FIG. 2, and
The wirings (a to k) illustrated in FIG. 3 are connected to each other by the same reference numerals, and constitute one switching power supply device. Converters A and B are configured using a resonance type converter.

The illustrated switching power supply includes an input terminal block 2, a resonance circuit 3, a transformer 5, an output terminal block 8, a resonance circuit connection terminal block 9, and the like. The number of converters A and B is two, but may be more. Converters A and B have the same circuit configuration.

First, the converter A includes a switching circuit 1, an input terminal block 2, a resonance circuit 3, and a transformer 5
, An output rectifying / smoothing circuit 7, an output terminal block 8, and a resonance circuit connecting terminal block 9.

The switching circuit 1 switches the DC voltage Vin supplied from the DC voltage source 11. The switching circuit 1 includes a first switching element 110 and a second switching element 120, and a drive circuit 130 that drives the first and second switching elements 110 and 120. The first switching element 110 and the second switching element 120 are composed of FETs or the like, the main circuits of which are connected in series with each other, and both ends of which are connected via input terminals 21 and 22 provided on the input terminal block 2. It is connected to a voltage source 11. The DC voltage source 11 is configured by a battery or other DC power supply, or a rectifying / smoothing circuit for converting an AC power supply to DC. The DC voltage source 11 may be provided as a part of the switching power supply device or may be an external element.

The transformer 5 includes at least a primary winding 51
And a secondary winding 52. The embodiment shows a secondary winding structure suitable when the output rectifying / smoothing circuit 7 is a dual-wave rectifying circuit system. The secondary winding 52 includes a first winding 521
And two windings of a second winding 522, and the first winding 521 and the second winding 522 have one ends connected to each other.

The resonance circuit 3 includes a resonance capacitor 31 and
And a resonance inductor 32. Resonant capacitor 3
1 and the resonance inductor 32 are connected in a circuit loop including the switching circuit 1 and the primary winding 51 of the transformer 5. In the embodiment, one end of the resonance capacitor 31 is connected to a connection point of the switching elements 110 and 120, and one end of the resonance inductor 32 is connected to the other end of the resonance capacitor 31. Resonance inductor 32
Is connected to one end of a primary winding 51 of the transformer 5. Therefore, the resonance circuit 3 forms a series resonance circuit including the resonance capacitor 31 and the resonance inductor 32.

The output rectifying / smoothing circuit 7 is connected to the secondary winding 52 of the transformer 5 and converts an induced voltage generated in the secondary winding 52 into DC and outputs the DC. The illustrated smoothing circuit is a choke input type including the output smoothing capacitor 71 and the output choke coil 73, but may be a capacitor input type not including the output choke coil 73.

The rectifier circuit 72 includes a first diode 721
And a second diode 722. The anode of the first diode 721 is connected to the other end of the first winding 521, and the anode of the second diode 722 is connected to the other end of the second winding 522. First diode 72
The cathodes of the first and second diodes 722 are connected to each other, and are connected to one end of an output smoothing capacitor 71 via an output choke coil 73.

Both ends of the output smoothing capacitor 71 are connected to positive and negative output terminals 81 and 82 provided on the output terminal block 8, respectively, and generate an output voltage of the converter A between the output terminals 81 and 82. The output terminal block 8 of the converter A is provided with an output voltage detection terminal 83. The output voltage detection terminal 83 is connected to the output terminal 81 of the converter A via a series circuit including the resistor R3 and the diode D1, and generates a voltage proportional to the output voltage of the converter A.

Converter B has the same circuit configuration as converter A. Therefore, the output terminal block 8 of the converter B
Similarly, the output voltage of the converter B is generated between the positive and negative output terminals 81 and 82 provided at the power supply circuit, and a voltage proportional to the output voltage of the converter B is generated at the output voltage detection terminal 83 of the converter B.

On the input side of the converter A and the converter B, input terminals 21 and 22 are connected in parallel with each other and connected to a common DC voltage source 11.
Similarly, on the output side, output terminals 81 and 82 are connected in parallel with each other to form a load connection terminal T0.

In the parallel connection of the converters A and B, the input and output terminals of the converters A and B are connected to the output terminal of the DC voltage source 11 and the input terminal of the load 12 using connecting members such as connectors, cables and bus bars. Any method, such as connecting the terminal blocks of the converters A and B with the connection members and then connecting them together to the output terminal of the DC voltage source 11 and the input terminal of the load 12 can be adopted. Also, a method may be used in which the converters A and B are connected by the connection member or the printed wiring pattern inside the switching power supply device without using the input / output terminals.

Further, converters A and B have resonant circuits 3 connected to each other. In the embodiment, in the resonance circuit 3 of the converter A and the resonance circuit 3 of the converter B, one ends of the resonance capacitors 31 are connected to each other via a terminal 91 provided on the resonance circuit connection terminal block 9. . The other ends of the resonance capacitors 31 are connected to each other via a terminal 92. Further, the resonance inductor 32
Are connected to each other via a terminal 93.
The connection of the resonance circuit 3 can be made by the same means as the connection of the converters A and B.

The output voltage detecting circuit 4 includes an output voltage stabilizing sense line 41 connected to the load connection terminal T0. The output voltage detecting circuit 4 includes an output voltage stabilizing sense line 41.
, The voltage of the load connection terminal T0 is detected, and the detected voltage is converted into an output voltage signal and supplied to the control circuit 10.

The overvoltage detection circuit 6 includes an overvoltage sense line 6
1A and 61B. Overvoltage sense lines 61A, 61
One end of B is connected to the output voltage detection terminals 83 of the converters A and B, respectively, and the other end is commonly connected to the main body 62 of the overvoltage detection circuit 6. The overvoltage detection circuit 6 detects the output voltage of each of the plurality of converters A and B via the overvoltage sense lines 61A and 61B, and furthermore, when at least one of the plurality of converters A and B enters the overvoltage state, the control circuit 10 Output an overvoltage signal to

The control circuit 10 includes control lines 10A, 10A
Via B, it is connected to control terminals 23 and 24 provided on the input side terminal blocks 2 of the converters A and B, and supplies control signals to the control terminals 23 and 24. Control terminal 23,
Reference numeral 24 denotes the switching element 11 via the drive circuit 130.
0, 120. The control circuit 10 controls the switching elements 110 and 120 included in the switching circuits 1 and 120 of the converters A and B based on the output voltage signal supplied from the output voltage detection circuit 4 so that the voltage at the load connection terminal T0 is stabilized. Control switching. When the overvoltage signal is output from the overvoltage detection circuit 6, the control circuit 10 controls the switching elements included in the switching circuits 1 of the plurality of converters A and B regardless of the output voltage signal from the output voltage detection circuit 4. Control is performed such that the operations of 110 and 120 are stopped or the output voltage is reduced.

In the switching power supply device described above,
The plurality of converters A and B alternately operate the switching elements 110 and 120 connected in series to switch the input DC voltage Vin, and switch the switching output to the primary winding of the resonance circuit 3 and the transformer 5. 51.

Between the connection point of the switching elements 110 and 120 and one end of the series circuit constituted by the switching elements 110 and 120, a resonance capacitor 31 and a resonance inductor 32 forming the resonance circuit 3, and a transformer 5 is connected to both ends of a series circuit in which the primary winding 51 and the primary winding 51 are connected in series.
Due to the alternating operation of 20, a pseudo sine wave current corresponding to the resonance frequency of the resonance circuit 3 flows through the resonance circuit 3 and the primary winding 51 of the transformer 5. At this time, an induced voltage is generated in the secondary winding 52 coupled to the primary winding 51. This induced voltage is converted to direct current by the output rectifying and smoothing circuit 7 connected to the secondary winding 52 of the transformer 5 and output.

The output sides of the converters A and B are commonly connected to each other to form a load connection end T0. The output voltage detection circuit 4 includes an output voltage stabilizing sense line 41.
, The voltage of the load connection terminal T0 is detected, the detected voltage is converted into an output voltage signal, and output to the control circuit 10.

The control circuit 10 controls the switching of the switching elements 110 and 120 included in the switching circuits 1 of the converters A and B so that the voltage at the load connection terminal T0 is stabilized based on the output voltage signal. Therefore, a switching power supply device that is of a parallel operation type and supplies a stable output to the load 12 can be obtained. This configuration also shows that it can be configured by adding one control circuit to a plurality of general-purpose converters that do not include a control circuit. This is advantageous for reducing the size and cost of the switching power supply device, and further has effects such as shortening the development period of the switching power supply device and facilitating inventory management.

Here, the voltage and current of each part of the above-mentioned switching power supply will be described with reference to FIGS. FIG. 4 shows the switching power supply device described above.
FIG. 5 is a voltage and current waveform diagram of each part of the converter when the state of the parallel connection of the plurality of converters A and B is normally maintained, and FIG. 5 is a diagram showing the voltage of each part of the converter when the normal state is not ensured; It is a current waveform diagram.

In the resonance type switching power supply of the parallel operation type as described above, the converters A and B have the resonance circuit 3 connected to each other. Therefore, the impedance of the resonance circuit 3 as viewed from the switching elements 110 and 120 is substantially equal in the converters A and B. Therefore, converters A and B are connected to one control circuit 1
0, the currents IdsA (converter A), IdsB (converter B), and the transformers IdsA (converter A) flowing through the switching elements 110 of the converters A and B, when operated synchronously at the same frequency. 5
Current IrA (converter A) flowing through the primary winding 51,
IrB (converter B) is substantially equal to each other, and the induced voltages VtA (converter A) and VtB (converter B) of the secondary winding 52 of the transformer are also substantially the same.

Here, if the load connection of converter B is disconnected, no load current flows through converter B, so that the output voltage of converter B is, as shown in FIG. It becomes a voltage obtained by peak-holding the induced voltage VtB of the winding 52, and becomes an overvoltage state. At this time, the current IrA flowing through the series resonance circuit 3 of the converter A
Is the sum of the resonance current and the load current.
Is disconnected, no load current flows through converter B. Therefore, the series resonance circuit 3 of the converter B
Is a small value of only the resonance current.

On the other hand, the current IrA flowing through the primary winding 51 of the transformer 5 of the converter A has a large current value because the load current that should be borne by the converter B is added.

An example of the output voltage of the converter at this time is as follows. For example, in the switching power supply device when the input voltage = 330 Vdc and the load current = 30 A are consumed, the converter A has an appropriate output voltage of 5.02 V. However, converter B is in an overvoltage state of 7.00V.

In the switching power supply of this embodiment, when an overvoltage state occurs, an overvoltage signal is output from the overvoltage detection circuit 6 to the control circuit 10.

When the overvoltage signal is supplied from the overvoltage detection circuit 6, the control circuit 10 is included in the switching circuits 1 of the plurality of converters A and B regardless of the output voltage signal supplied from the output voltage detection circuit 4. The operation of the switching element 110 to be stopped is controlled or the output voltage is controlled to decrease. As a result, the output of the switching power supply is stopped. Therefore, the situation where the overvoltage state of converter B continues can be avoided.

As described above, the switching power supply according to the present embodiment, when one of the plurality of converters A and B loses connection with the load 12 and an overvoltage occurs, Since the output is stopped, a measure for the abnormality can be promptly performed. In addition, circuit damage due to the occurrence of overvoltage and other problems can be prevented. Therefore, the reliability of the switching power supply of the present embodiment is high.

There are various modes for connecting the resonance circuits 3 of the plurality of converters A and B. As an example, (a) a configuration in which one ends of the resonance capacitors 31 of the plurality of converters A and B are connected to each other, and (b) a configuration in which one ends of the resonance capacitors 31 of the plurality of converters A and B and the resonance capacitor 31 are connected. A form where the other ends are connected to each other,
(C) Resonance inductor 32 of converters A and B
(D) a configuration in which the other ends of the resonance inductors 32 of the plurality of converters A and B are connected, and (e) a configuration in which the other ends of the resonance capacitors 31 of the converters A and B and the resonance. And the other end of each of the inductors 32 are connected to each other.

Although the contents of the present invention have been specifically described with reference to the embodiments of the present invention, those skilled in the art can make various modifications based on the basic technical idea and teaching of the present invention. It is obvious that you can do it.

[0068]

As described above, according to the present invention, the following effects can be obtained. (A) Even if an abnormality occurs in the parallel connection and an overvoltage occurs in the converter, it is possible to provide a switching power supply device of a parallel operation system that can promptly deal with the abnormality. (B) It is possible to provide a highly reliable parallel operation type switching power supply device capable of preventing circuit damage due to the occurrence of overvoltage and other problems beforehand. (C) It is possible to provide a small-sized, low-cost, parallel operation type switching power supply device that can be configured by adding one control circuit to a general-purpose converter.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically illustrating a switching power supply device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a specific circuit configuration of a converter A in another embodiment of the switching power supply according to the present invention.

FIG. 3 is a diagram showing a specific circuit configuration of converter B combined with converter A shown in FIG.

FIG. 4 is a voltage and current waveform diagram of each part of the converter when a state of parallel connection of a plurality of converters A and B is normally maintained.

FIG. 5 is a voltage and current waveform diagram of each part of the converter when a normal parallel connection state of a plurality of converters A and B is not ensured.

[Explanation of symbols]

 A, B converters 1 switching circuit 4 output voltage detection circuit 6 overvoltage detection circuit 7 output rectification smoothing circuit T0 load connection terminal

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H730 AA15 AA20 AS00 AS01 AS19 BB76 BB83 CC01 DD04 DD13 DD23 EE03 EE07 EE08 FD01 XX04 XX12 XX23 XX32 XX43 XX47

Claims (3)

[Claims] 1. A switching power supply including a plurality of converters, an output voltage detection circuit, an overvoltage detection circuit, and a control circuit, wherein each of the plurality of converters includes a switching circuit, an output rectification smoothing circuit, Wherein the output sides are connected in parallel to each other to form a load connection end, wherein the switching circuit switches a supplied DC voltage, and the output rectifying and smoothing circuit includes a switching output supplied from the switching circuit. Rectifying and smoothing
Outputting a DC voltage to the load connection end, the output voltage detection circuit detects a voltage at the load connection end, and supplies an output voltage signal to the control circuit; Detecting an output voltage of each of the plurality of converters and supplying an overvoltage signal to the control circuit when at least one of the plurality of converters is in an overvoltage state, wherein the control circuit adjusts a voltage of the load connection terminal based on the output voltage signal; A switching power supply device that controls switching of the switching circuit so as to be stabilized, and stops output of the switching power supply device when the overvoltage signal is supplied. 2. The switching power supply device according to claim 1, wherein each of the plurality of converters includes a resonance converter. 3. The switching power supply device according to claim 2, wherein the plurality of converters have resonance circuits connected to each other.