JP2001103753A - Switching power supply unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a switching power supply unit which is capable of taking prompt actions against failure and employs a highly reliable parallel operating system. SOLUTION: Each of a plurality of converters A, B involves a switching circuit 1 and an output rectifying filtering circuit 4, and the output sides thereof are connected parallel with each other to comprise a load connecting terminal T0. An output voltage detecting circuit 5 detects the voltage of the load connecting terminal T0, and outputs an output voltage signal to a control circuit 6. A drive signal monitoring circuit 7 monitors the driving signal, and outputs a failure signal to the control circuit 6, a failure display means 8, and a load L when the driving signal is under a failure condition. The control circuit 6 controls the switching circuit 1 so that the voltage of the load connecting end T0 may be stabilized based on the output voltage signal, and stops the output of the switching power source when the failure signal is outputted. The failure display means 8 displays the failure condition if the failure signal is outputted.

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 with each other, and a plurality of converters are driven 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 the development cost, and standardization, combining the existing switching power supply devices. 2. Description of the Related Art Switching power supply devices corresponding to various specifications have been provided. In particular,
2. Description of the Related Art In the field of large computers and industrial equipment that require large power, switching power supplies of a parallel operation type have been receiving attention. The switching power supply device of the parallel operation system has a configuration in which a plurality of switching power supply devices are connected in parallel to each other, and can secure power capacity and at the same time improve reliability.

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 switching power supply device of the parallel operation type disclosed in this publication connects a plurality of resonance-type converter circuits including switching elements in parallel to form a load connection end, and also connects the resonance circuits of the respective converter circuits. The configuration is as follows.

[0005] 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. Further, in the plurality of converter circuits, the impedance of the resonance circuit viewed from the switching element side can be substantially equal to each other. Accordingly, by supplying a drive signal to the switching elements of the plurality of converter circuits from the common control circuit via the drive signal line, it becomes possible to drive the plurality of converter circuits synchronously at the same frequency. . Therefore, there is an advantage that the output voltage of the switching power supply device can be stabilized and the output current of each converter circuit can be made uniform without special control.

However, in a parallel operation type switching power supply device, when a driving signal is supplied from a common control circuit to a switching element of a plurality of converter circuits via a driving signal line, the driving signal is output from a plurality of converter circuits. However, when a converter circuit in which the connection of the drive signal line is disconnected occurs, the other converter circuits are overloaded and an overcurrent occurs. That is, the switching element of the converter circuit whose connection of the drive signal line is disconnected stops on / off. For this reason, the current that should be borne by the switching element of the converter circuit whose connection of the drive signal line is disconnected flows through the other switching elements of the converter circuit. As a result, a normal voltage is output to the load connection end, and the overcurrent state continues without detecting an abnormal state.

If the overcurrent state continues, the switching elements of the converter circuit to which the drive signal lines are normally connected generate excessive heat, and the output of the switching power supply stops due to the overheat protection operation, and further, the switching elements are damaged. This causes a failure of the switching power supply device and other troubles, thereby causing a problem that 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 an input / output terminal and a signal terminal of a converter, a switching power supply device of a parallel operation system is configured. Is done.

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. In addition, even if the wiring is correctly performed, there is not no accident such as disconnection of the wiring during operation of the power supply device. For this reason,
The above-mentioned problem of overcurrent cannot be eliminated at all, which has been a serious problem from the viewpoint of the reliability of the power supply device.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a switching power supply of a parallel operation type capable of promptly coping with an abnormality even if a drive signal line is disconnected and an overcurrent occurs in a converter. It is to be.

Another object of the present invention is to provide a highly reliable parallel operation type switching power supply that can prevent circuit damage due to the occurrence of overcurrent and other problems.

Another object of the present invention is 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 plurality of general-purpose converters.

[0013]

In order to solve the above-mentioned problems, a switching power supply according to the present invention includes a plurality of converters, an output voltage detection circuit, a control circuit, and a drive signal monitoring 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 includes at least one switching element, and switches the supplied DC voltage.

The output rectifying / smoothing circuit rectifies and smoothes a switching output 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 supplies a drive signal to the switching circuit based on the output voltage signal, and controls switching of the switching circuit so that the voltage at the load connection terminal is stabilized.

The drive signal monitoring circuit monitors the drive signal and outputs an abnormal signal when the drive signal becomes abnormal.

As described above, in the 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 includes at least one switching element, and switches the supplied DC voltage. The output rectifying / smoothing circuit rectifies and smoothes the switching output supplied from the switching circuit and outputs a DC voltage to a load connection terminal. Therefore, it is possible to realize a switching power supply device of a parallel operation system in which the power capacity is secured and at the same time, the reliability is improved.

The output voltage detection circuit detects the voltage at the load connection end and supplies an output voltage signal to the control circuit. The control circuit supplies a drive signal to the switching circuit based on the output voltage signal, and controls switching of the switching circuit so that the voltage at the load connection end is stabilized. Therefore, a switching power supply device of a parallel operation system for supplying a stable DC voltage to the load can be obtained.

The configuration of the output voltage detection circuit and the control circuit described above also means that one control circuit is added to a plurality of general-purpose converters. This is advantageous for miniaturization and cost reduction of the switching power supply, and further,
Effects such as shortening the development period of the switching power supply device and facilitating inventory management are provided.

The switching power supply of the present invention further comprises:
The drive signal monitoring circuit including the drive signal monitoring circuit monitors the drive signal and outputs an abnormal signal when the drive signal becomes abnormal.

Therefore, the switching power supply of the present invention outputs an abnormal signal from the driving signal monitoring circuit when any of the driving signals of the plurality of converters is in an abnormal state, so that the abnormality can be promptly treated. . Further, it is possible to prevent circuit damage due to generation of an overcurrent due to an abnormality in the drive signal and other problems beforehand. Therefore, the reliability of the switching power supply of the present invention is high.

The control circuit may be configured to stop driving the switching circuit when the abnormal signal is output. With this configuration, when the abnormal signal is output, the operation of the switching power supply device can be stopped.

The power supply device of the present invention can further include abnormality display means. If the abnormality display means is configured to display an abnormal state when the abnormal signal is output, the abnormal state can be quickly recognized.

In the power supply according to the present invention, the plurality of converters can be constituted by resonance type converters. By connecting the resonance circuits of the resonance type converter to each other, it becomes possible to drive a plurality of converter circuits synchronously at the same frequency. Therefore, it is possible to stabilize the output voltage of the switching power supply device without special control, and to obtain an effect that the output current of each converter circuit can be made uniform.

[0028]

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 5, a control circuit 6,
It includes a drive signal monitoring circuit 7 and an abnormality display means 8. In the figure, reference numeral 10 is a DC voltage source. DC voltage source 1
For 0, 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 10. Converter A,
In parallel connection of B, a method of connecting input / output terminals of converters A and B to an output terminal of DC voltage source 10 and an input terminal of load L using connection members such as connectors, cables, and bus bars, respectively. After connecting the terminal blocks A and B with the connection members, the DC voltage sources 10
Or 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 4. 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 controls the supplied DC voltage V
Switching in. More specifically, the switching circuit 1 includes at least one switching element 11, and switches the supplied DC voltage Vin by the switching element 11. The output rectifying / smoothing circuit 4
It 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 5 detects the voltage at the load connection terminal T0 and supplies an output voltage signal to the control circuit 6.
In the present embodiment, the voltage dividing resistor R connected to the load connection end T0
1, the voltage at the load connection end T0 is detected via R2, and the divided voltage is supplied to the control circuit 6 as an output voltage signal.

The control circuit 6 includes drive signal lines 6A, 6B
Switching circuit 1 for a plurality of converters A and B
And supplies a drive signal to the switching element 11 included in the switching circuit 1. In connecting the drive signal lines 6A and 6B, directly or
The same means as the parallel connection of the converters A and B described above can be adopted via the signal terminal. The control circuit 6 supplies a drive signal to the switching circuits 1 of the plurality of converters A and B via the drive signal lines 6A and 6B based on the output voltage signal supplied from the output voltage detection circuit 5, and the load connection terminal T
The switching operation of the switching elements 11 of the converters A and B is controlled so that the voltage of 0 is stabilized. The control circuit 6 includes, for example, an oscillation circuit, a pulse width control, a frequency control circuit or a logic circuit.

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 provides a switching power supply of a parallel operation type in which one control circuit 6 is shared by a plurality of converters A and B by adding one control circuit 6 to a plurality of general-purpose converters A and B. Indicates that you can do it. The switching power supply of the parallel operation type having such a configuration is advantageous for miniaturization and cost reduction, and further provides effects such as shortening the development period of the switching power supply and facilitating inventory management.

The drive signal monitoring circuit 7 includes a signal detector 71,
And a signal processing unit 72. The signal detection unit 71 is configured to detect a voltage, a current, and the like related to the drive signal supplied to the switching circuits 1 of the converters A and B, and supplies a detection result to the signal processing unit 72 as a detection signal. The signal processing unit 72 processes and outputs the detection signal supplied from the signal detection unit 71.

The drive signal monitoring circuit 7 monitors the drive signal supplied to the switching circuits 1 of the converters A and B, and outputs an abnormal signal when any one of the drive signals is in an abnormal state.

In this embodiment, the driving signal monitoring circuit 7
Is output to the control circuit 6, the abnormality display means 8, and a load L such as a computer connected to the load connection terminal T0.

When an abnormal signal is output from the drive signal monitoring circuit 7, the control circuit 6 switches 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 5. Control is performed such that the output of the switching power supply is reduced by stopping the drive signal supplied to the power supply or by means such as pulse width control or frequency control.

The abnormality display means 8 includes a light emitting diode 81,
And a switch element 82. When an abnormal signal is output from the drive signal monitoring circuit 7, the switch element 82 is turned on, the light emitting diode 81 is driven to emit light, and an abnormality of the drive signal is displayed. ing. The abnormality display means 8 may be a sounding / speaking means having a sound source such as a buzzer or a speaker, in addition to the light emitting means having a light source which can be viewed as described above.

In the switching power supply of the above-described embodiment, for example, when a converter whose drive signal line 6A or 6B is disconnected from the plurality of converters A and B occurs, any one of the plurality of converters A and B is used. Is in an abnormal state, and the drive signal monitoring circuit 7 outputs an abnormal signal.

The abnormality signal is sent to the control circuit 6, the abnormality display means 8
And the load L such as a computer connected to the load connection terminal T0.

When the drive signal monitoring circuit 7 outputs an abnormal signal, the control circuit 6 supplies the switching signal to 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 5. The output of the switching power supply device is controlled to be reduced by stopping the supplied drive signal or by means such as pulse width control and frequency control. For this reason, in the switching power supply, the operation stops or the output decreases.

When the drive signal monitoring circuit 6 outputs a fault signal, the fault display means 8 turns on the switch element 82, drives the light emitting diode 81 to emit light, and displays a fault in the drive signal.

The load L of the computer or the like can take measures for an abnormality such as a memory holding operation by supplying the abnormality signal.

For this reason, in the switching power supply of the present embodiment, of the plurality of converters A and B, a converter in which the connection of the drive signal line is disconnected occurs, and the switching element of the converter stops on / off. Therefore, even if the other converters are overloaded and an overcurrent occurs, it is possible to quickly take measures against the abnormality. Further, since the abnormal state is displayed, the abnormal state can be quickly recognized. Further, the operation as the switching power supply is stopped or its output is reduced, so that the overcurrent state is not continued. For this reason, circuit damage due to the occurrence of overcurrent and other problems can be prevented beforehand,
A highly reliable switching power supply device can be provided.

In the switching power supply of the present invention,
The number of the converters A and B connected in parallel is not limited to two, and the number is not limited as long as it is two or more. The types of the converters A and B are not limited to a forward type and a flyback type, and may be any of a pulse width control method and a frequency control method.

FIG. 2 is a circuit diagram showing a specific circuit configuration of converter A in another embodiment of the switching power supply device according to the present invention, and FIG. 3 is a specific diagram of converter B combined with converter A shown in FIG. FIG. 3 is a circuit diagram showing a typical circuit configuration. Although the circuit diagrams of FIGS. 2 and 3 should originally be displayed as one circuit diagram, they are divided into two diagrams for the sake of space. These figures show examples of a switching power supply device configured using a resonance type converter. In the figure, the same reference numerals as those in FIG. 1 indicate the same components. Wirings (a to j) shown in FIG. 2 and wirings (a to j) shown in FIG. 3 are connected to each other by the same reference numerals, and constitute one switching power supply device.

The illustrated switching power supply includes a resonance circuit 2, a transformer 3, terminal blocks 91 to 95, 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, a resonance circuit 2, a transformer 3, an output rectifying and smoothing circuit 4, input and output terminal blocks 91 and 92, a resonance circuit connection terminal block 93, And signal terminal blocks 94 and 95.

The switching circuit 1 switches the DC voltage Vin supplied from the DC voltage source 10. The switching circuit 1 has a first switching element 11 and a second switching element 12. The first switching element 11 and the second switching element 12 are FETs
The main circuits are connected in series with each other, and both ends thereof are input terminals 911 and 91 provided on the input terminal block 91.
2 to a DC voltage source 10. The DC voltage source 10 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 10 may be provided as a part of the switching power supply device or may be an external element.

The resonance circuit 2 includes a resonance capacitor 21 and
And a resonance inductor 22. Resonant capacitor 2
1 and the resonance inductor 22 are connected in a circuit loop including the switching circuit 1 and the primary winding 31 of the transformer 3. In the embodiment, one end of the resonance capacitor 21 is connected to a connection point m between the switching elements 11 and 12, and one end of the resonance inductor 22 is connected to the other end of the resonance capacitor 21. The other end of the resonance inductor 22 is connected to one end of the primary winding 31 of the transformer 3. Therefore, the resonance circuit 2 forms a series resonance circuit including the resonance capacitor 21 and the resonance inductor 22.

The transformer 3 includes at least a primary winding 31
And a secondary winding 32. The other end of the primary winding 31 is connected to a connection midpoint n between the source of the switching element 12 and the input terminal 912. Transformer 3 of this embodiment
Shows a secondary winding structure suitable when the output rectifying / smoothing circuit 4 is a dual-wave rectifying circuit system. The secondary winding 32 includes two windings, a first winding 321 and a second winding 322,
One end of each of the first winding 321 and the second winding 322 is connected to each other.

The output rectifying / smoothing circuit 4 is connected to the secondary winding 32 of the transformer 3 and converts an induced voltage generated in the secondary winding 32 into DC and outputs the DC. The illustrated rectifying / smoothing circuit 4
Are an output smoothing capacitor 41 and an output choke coil 42
, But may be a capacitor input type that does not include the output choke coil 42. The rectifier circuit includes a first diode 431 and a second diode 432. The anode of the first diode 431 is connected to the other end of the first winding 321, and the anode of the second diode 432 is connected to the other end of the second winding 322. The cathodes of the first diode 431 and the second diode 432 are connected to each other, and are connected to one end of the output smoothing capacitor 41 via the output choke coil 42. Both ends of the output smoothing capacitor 41 are positive and negative output terminals 921 provided on the output side terminal block 92,
922 to generate an output voltage of the converter A between the output terminals 921 and 922.

Converter B has the same circuit configuration as converter A. Therefore, the output terminal block 9 of the converter B
Similarly, the output voltage of the converter B is generated between the positive and negative output terminals 921 and 922 provided in the second circuit 2.

The input terminals of the converter A and the converter B are connected in parallel to each other on the input side, and are connected to a common DC voltage source 10. Similarly, on the output side, output terminals 921 and 922 are respectively connected in parallel to each other to form a load connection end T0.

The converters A and B are connected in parallel by connecting the input / output terminals 911, 912, 921 and 922 of the converters A and B to the output terminal of the DC voltage source 10 and the load by using connecting members such as connectors, cables and bus bars. L, input / output terminals 911, 912, 921, and 922 of the converters A and B are connected by the connection member, and then the output terminal and the load L of the DC voltage source 10 are collectively connected.
Any of the methods such as connection to the input terminal can be adopted. Alternatively, the terminals A and B may be connected by the connection member or the printed wiring pattern inside the switching power supply without using the terminal blocks 91 and 92.

Further, in the converters A and B, the resonance circuits 2 are connected to each other. In the embodiment, the resonance circuit 2 of the converter A and the resonance circuit 2 of the converter B are connected to each other at a point D via a terminal 931 provided on the resonance circuit connection terminal block 93. Have been. The other end of the resonance capacitor 21 is connected to the terminal 9.
They are connected to each other at a point p via P. 32. Further, the other end of the resonance inductor 22 is connected to the point q via the terminal 933.
Are connected to each other. The connection of the resonance circuit 2 can be performed by the same means as the parallel connection of the converters A and B described above.

There are various modes for connecting the resonance circuits 2 of the plurality of converters A and B. As examples, (a) one end of each of the resonance capacitors 21 of the plurality of converters A and B are connected to each other, and (b) one end of each of the resonance capacitors 21 of the plurality of converters A and B and the resonance capacitor 21. A form in which the other ends are connected to each other,
(C) Resonance inductor 22 of converters A and B
(D) a configuration in which the other ends of the resonance inductors 22 of the converters A and B are connected to each other, and (e) a configuration in which the resonance capacitors 21 of the converters A and B have one ends and resonance. For example, the other ends of the inductors 22 are connected to each other.

The output voltage detecting circuit 5 includes an output voltage stabilizing sense line 51 connected to the load connection terminal T0. The output voltage detecting circuit 5 includes an output voltage stabilizing sense line 51.
, 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 6.

The control circuit 6 includes drive signal lines 61A, 6A
The signal terminals 94 provided on the drive signal terminal blocks 94 of the respective converters A and B via 2A, 61B and 62B
1 and 942 to supply drive signals to the signal terminals 941 and 942. The signal terminals 941 and 942 are connected to the gates of the switching elements 11 and 12. The control circuit 6 controls the drive signal lines 61A, 62A, 61B, 6 based on the output voltage signal supplied from the output voltage detection circuit 5.
Switching element 1 of converters A and B via 2B
A drive signal is supplied to the switching elements 1 and 12, and the switching of the switching elements 11 and 12 is controlled so that the voltage at the load connection end T0 of the converters A and B is stabilized. When an abnormal signal is output from a drive signal monitoring circuit 7 to be described later, the control circuit 6 supplies the switching circuit 1 of the plurality of converters A and B irrespective of the output voltage signal supplied from the output voltage detection circuit 5. The driving signal to be supplied is stopped, or the frequency of the driving signal is controlled so that the output of the switching power supply device is reduced.

The drive signal monitoring circuit 7 (see FIG. 1 for reference numeral 7) is provided for each of the converters A and B, and includes detection units 712 and 713 and a signal processing unit 72, respectively. Detection unit 712 includes a current transformer, a resistor, and a diode. The current transformer is arranged between the source of the switching element 12 and the point n, and detects a current flowing through the switching element 12. The diode is arranged in a direction to detect a current flowing when the switching element 12 is turned on, and supplies a detection output to the signal processing unit 72.

In the present embodiment, the detection unit 713 similarly includes a current transformer, a resistor and a diode. Detection unit 71
The current transformer 3 is disposed closer to the resonance capacitor 21 than the connection point D of the resonance circuit 2 and detects a current flowing through the resonance circuit 2. The diode of the detection unit 713 is connected to the resonance circuit 2
Among the currents flowing through the switching element 12, the detection current is supplied to the signal processing unit 72.

The signal processing section 72 includes a signal level setting circuit 72
1 and a comparison circuit 722. Signal level setting circuit 72
1 includes a resistor and a capacitor. The signal level setting circuit 721 adjusts the levels of the detection output supplied from the detection unit 712 and the detection output supplied from the detection unit 713 using the resistor and the capacitor, respectively.
Voltage signals 712S and 713 that can be compared by comparison circuit 722
The signal is converted to S and supplied to different input terminals of the comparison circuit 722.

The comparison circuit 722 supplies the supplied voltage signal 71
2S is compared with the voltage signal 713S. Then, when the voltage signal 712S based on the detection output of the detection unit 712 falls below the voltage signal 713S based on the detection output of the detection unit 713, an abnormal signal is output. This abnormal signal is used as an abnormal signal output from the drive signal monitoring circuit 7 as the signal terminal block 95.
Is output to the control circuit 6 via

In the above switching power supply,
The plurality of converters A and B alternately operate the switching elements 11 and 12 connected in series to switch the input DC voltage Vin, and switch the switching output to the primary winding of the resonance circuit 2 and the transformer 3. 31
To supply.

Connection point m of switching elements 11 and 12
And a point n via a main circuit of the switching element 12, a series connection in which a resonance capacitor 21 and a resonance inductor 22 constituting the resonance circuit 2 and a primary winding 31 of the transformer 3 are connected in series. Since both ends of the circuit are connected, the resonance circuit 2 and the primary winding 31 of the transformer 3 are connected to the resonance circuit 2 by the alternate operation of the switching elements 11 and 12.
A pseudo sine wave current corresponding to the resonance frequency flows. At this time, an induced voltage is generated in the secondary winding 32 coupled to the primary winding 31. This induced voltage is applied to the secondary winding 32 of the transformer 3.
Is converted into a direct current by an output rectifying / smoothing circuit 4 connected to 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 5 detects the voltage at the load connection terminal T0 via the output voltage stabilizing sense line 51, converts the detected voltage into an output voltage signal, and outputs the output voltage signal to the control circuit 6.

The control circuit 6 controls the switching of the switching elements 11 and 12 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, it is possible to obtain a switching power supply device that employs a parallel operation method and supplies a stable output to the load L. 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 in reducing the size and cost of the switching power supply device, and further has the effects of shortening the development period of the switching power supply device and facilitating inventory management.

Next, referring to FIGS. 4 and 5, the voltages and currents of the respective parts of the switching power supply shown in FIGS. 2 and 3 will be described. FIG. 4 is a voltage and current waveform diagram of each part of the converter in the switching power supply device shown in FIGS. 2 and 3 when a parallel connection state 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 the drive signal lines 61B and 62B of the converter B are disconnected.

In the resonance type switching power supply of the parallel operation type shown in FIGS. 2 and 3, the converters A and B have resonance circuits 2 connected to each other. Therefore, the impedance of the resonance circuit 2 as viewed from the switching elements 11 and 12 becomes substantially equal in the converters A and B. For this reason, when the converters A and B are operated synchronously at the same frequency by using one control circuit 6, if the parallel connection state of the plurality of converters A and B is maintained normally, As shown in FIG. 4, the switching elements 1 are driven by the drive signals supplied to the respective converters A and B.
One gate. Source-to-source voltage Vgs1A (converter A,
4C), Vgs1B (converter B, FIG.
(G)) and the gate of the switching element 12. The source-to-source voltages Vgs2A (converter A, see FIG. 4 (d)) and Vgs2B (converter B, see FIG. 4 (g)) have substantially the same pulse voltage with a half cycle phase shift.

The current Ids1A flowing through the switching element 11 of each of the converters A and B (converter A, FIG.
(A), Ids1B (see FIG. 4 (e)), and currents Ids2A (see FIG. 4 (b)) flowing through the switching elements 12 of the converters A and B, Ids2B (converter B, see FIG. 4 (f)). ) Are almost equal.

Here, it is assumed that the connection of the drive signal lines 61B and 62B of the converter B is disconnected. Since no drive signal is supplied to the switching elements 11 and 12 of the converter B, as shown in FIG.
The gate-source voltages Vgs1B and Vgs2B of the switching elements 11 and 12 are zero voltage (FIG. 5 (g),
(H)). Therefore, switching elements 11 and 12 of converter B are cut off, and currents Ids1B and Ids flowing through switching elements 11 and 12 of converter B are set.
2B also becomes zero current (see FIGS. 5E and 5F).

On the other hand, the switching elements 11 and 12 of the converter A have a current Id almost twice as large as that when the parallel connection state is normally maintained (see FIG. 4).
s1A and Ids2A flow (see FIGS. 5A and 5B). This is because, in the switching power supply of the present embodiment, since the resonance circuits 2 of the converters A and B are connected to each other, a current flows through the connection point D of the resonance circuit 2. Therefore, when switching elements 11 and 12 of converter B are cut off, when switching element 11 of converter A conducts, switching element 1
1 and a current flows through the resonance circuit 2 of the converter B and the primary winding 31 of the transformer 3 via the connection point D of the resonance circuit 2. When the switching element 12 of the converter A is conducting,
Using the resonance circuit 2 of the converter B as a current source, the resonance circuit 2
, The switching element 12 of the converter A, the input terminals 912 of the converters A and B, and the primary winding 31 of the transformer 3 of the converter B. Thus, switching elements 11, 1 of converter A
2, a current twice as large as the normal current obtained by adding the current of the converter B to the current of the converter A flows. Therefore, switching elements 11 and 12 of converter A are in an overcurrent state.

Next, the switching power supply of the present invention includes a drive signal monitoring circuit 7. The drive signal monitoring circuit 7 of the present embodiment is provided for each of the converters A and B,
12 and 713 and the signal processing unit 72. Detector 712
Includes a current transformer, a resistor and a diode.
The current transformer is arranged between the source of the switching element 12 and the point n, and detects a current flowing through the switching element 12. The diode is a switching element 12
Are arranged in a direction for detecting a current flowing at the time of conduction, and a detection output thereof is supplied to the signal processing unit 72.

In this embodiment, the detection unit 713 also includes a current transformer, a resistor and a diode. Detection unit 71
The current transformer 3 is disposed closer to the resonance capacitor 21 than the connection point D of the resonance circuit 2 and detects a current flowing through the resonance circuit 2. The diode of the detection unit 713 is connected to the resonance circuit 2
Among the currents flowing through the switching element 12, the detection current is supplied to the signal processing unit 72.

The signal processing section 72 includes a signal level setting circuit 72
1 and a comparison circuit 722. Signal level setting circuit 72
1 includes a resistor and a capacitor. The signal level setting circuit 721 adjusts the levels of the detection output supplied from the detection unit 712 and the detection output supplied from the detection unit 713 using the resistor and the capacitor, respectively.
Voltage signals 712S and 713 that can be compared by comparison circuit 722
The signal is converted to S and supplied to different input terminals of the comparison circuit 722.

The comparison circuit 722 supplies the supplied voltage signal 71
2S and 713S are compared, and an abnormal signal is output when the voltage signal 712S based on the detection output of the detection unit 712 falls below the voltage signal 713S based on the detection output of the detection unit 713.

When the drive signal lines 61B and 62B of the converter B are disconnected, no drive signal is supplied to the switching elements 11 and 12 of the converter B, so that the switching elements 11 and 12 of the converter B are cut off. State. Therefore, the currents Ids1B and Ids2B flowing through the switching elements 11 and 12 of the converter B become zero current, and the DC voltage signal 712S based on the detection output of the detection unit 712 becomes low. On the other hand, a current flows through the resonance circuit 2 of the converter B. Therefore, the DC voltage signal 7 based on the detection output of the detection unit 713 of the converter B
13S maintains a high level. As a result, the drive signal monitoring circuit 7 outputs an abnormal signal. This abnormal signal is output to the control circuit 6.

The control circuit 6 of this embodiment provides a switching circuit for the converters A and B when the drive signal monitoring circuit 7 outputs an abnormal signal, regardless of the output voltage signal supplied from the output voltage detection circuit 5. The driving signal supplied to the switching power supply 1 is stopped or the frequency of the driving signal is controlled so that the output of the switching power supply device is reduced.
As a result, the switching power supply stops operating or
Alternatively, the output voltage can be reduced to avoid a situation where the overcurrent state of converter A continues.

As described above, according to the switching power supply of this embodiment, the driving signal line 61B or 62B
When the connection is disconnected, the output of the switching power supply stops operating or its output voltage is reduced, so that a countermeasure against abnormality can be promptly performed. Further, other problems such as circuit damage due to the occurrence of overcurrent and imbalance of power sharing between converters can be prevented. Therefore, the reliability of the switching power supply of the present embodiment is high.

The drive signal monitoring circuit 7 of this embodiment monitors a drive signal by comparing a current flowing through the switching element 12 with a current flowing through the resonance circuit 2. In this case, since both currents have the same waveform when viewed as a half wave, there is an advantage that signal processing is easy. The current may be detected by a resistor. However, by using a current transformer for the detection unit, (a) low loss, (b) flexibility in signal level setting is widened, and (c) insulation is possible. Therefore, it is possible to obtain an effect that the degree of freedom of control circuit design is widened. The arrangement position of the detection unit is not limited to the position shown in the present embodiment, and may be any position as long as it can detect the current flowing through the switching element and the current flowing through the resonance circuit.
It may be on the drain side of the switching element or between the resonance circuit and the primary winding of the transformer. Further, while detecting the current flowing through the switching element 11, the switching element 11 It is also possible to detect the current flowing when the conduction is made and compare the two.

In the drive signal monitoring circuit 7 of this embodiment, in order to detect the current flowing through one switching element in each converter, only the drive signal line for supplying a drive signal to the other switching element is disconnected. In such a case, detection becomes impossible. When the connection of the drive signal line is performed using the connector grouped for each converter, there is little possibility that the connection is cut off on only one side. When connecting, there is room for problems.

FIG. 6 is a voltage and current waveform diagram of each part of the converter when one drive signal line is disconnected in this manner, and shows a state when drive signal line 61B is disconnected. Is shown.

When the connection of drive signal line 61B of converter B is disconnected, switching element 11 of converter B
Is not supplied with a drive signal, as shown in FIG.
The gate-source voltage Vgs1B of the switching element 11 of the converter B becomes zero voltage (see FIG. 6H).
Therefore, switching element 11 of converter B is cut off, and current Ids1B flowing through switching element 11 of converter B also becomes zero (see FIG. 6 (f)).

On the other hand, the current Ids1A flows through the switching element 11 of the converter A almost twice as much as when the parallel connection state is normally maintained (see FIG. 4) (FIG. 6 (b)). )reference). On the other hand, switching element 1
2 is a drive signal line 62 for both converters A and B.
Since A and 62B are normally connected, their gates,
The source-to-source voltages Vgs2A and Vgs2B and the currents Ids2A and Ids2B flowing through the switching element 12 also show normal values (see FIGS. 6C, 6G, 6A, and 6E). Therefore, the drive signal monitoring circuit 7 of the present embodiment cannot detect an abnormal state and cannot avoid a situation where the overcurrent state continues.

FIGS. 7 and 8 are circuit diagrams showing another embodiment of the switching power supply according to the present invention which solves this problem. FIG. 7 is a circuit diagram showing a specific circuit configuration of converter A in another embodiment of the switching power supply device according to the present invention, and FIG. 8 is a specific circuit of converter B combined with converter A shown in FIG. FIG. 3 is a circuit diagram illustrating a configuration. Although the circuit diagrams of FIGS. 7 and 8 should be originally displayed as one circuit diagram, they are divided into two diagrams for the sake of space. In the drawings, the same reference numerals as those in FIGS. 2 and 3 indicate the same components. The illustrated switching power supply has the same circuit configuration as the switching power supply shown in FIGS. 2 and 3 except for the drive signal monitoring circuit 7. Hereinafter, description of the same components will be omitted, and the drive signal monitoring circuit 7 will be described.

The drive signal monitoring circuit 7 of this embodiment is provided for each of the converters A and B.
2, 714 and the signal processing unit 72. Detector 712
Includes a current transformer, a resistor and a diode.
The current transformer is arranged between the source of the switching element 11 and the point m, and detects a current flowing through the switching element 11. The diode is a switching element 11
Are arranged in a direction for detecting a current flowing at the time of conduction, and a detection output thereof is supplied to the signal processing unit 72.

The detecting section 712 has the same circuit configuration as the detecting section 712 shown in FIG. 2 and is arranged at the same position.

The detecting section 714 includes a current transformer and a full-wave rectifier diode. The detection unit 714 is disposed on the resonance capacitor 21 side from the connection point D of the resonance circuit 2, detects a current flowing in both directions in the resonance circuit 2, and supplies a detection output to the signal processing unit 72.

The signal processing section 72 includes a signal level setting circuit 72
1 and a comparison circuit 722. Signal level setting circuit 72
1 includes a resistor and a capacitor. The signal level setting circuit 721 collects the detection outputs detected by the detection units 711 and 712, adjusts the level using the resistor and the capacitor, converts the output into voltage signals 711S and 712S that can be compared by the comparison circuit 722, and The signal is supplied to one input terminal of the circuit 722. The signal level setting circuit 721 also converts the detection output in both directions detected by the detection unit 714 into a voltage signal 714S that can be adjusted by the resistor and the capacitor and compared by the comparison circuit 722,
It is supplied to the other input terminal of the comparison circuit 722.

The comparison circuit 722 compares the voltage signals 711S and 712S supplied to one input terminal with the voltage signal 714S supplied to the other input terminal, and detects a voltage based on the detection output of the detection unit 711 or 712. Signal 711
S, 712S is the detection unit 7 supplied to the other input terminal.
An abnormal signal is output when the voltage falls below a voltage signal 714S based on the 14 detection outputs.

The thus-configured drive signal monitoring circuit 7 of the present embodiment can detect any disconnection of any of the drive signal lines 61A, 62A, 61B and 62B of the converters A and B.

For example, it is assumed that the connection of the drive signal line 61B of the switching element 11 of the converter B is disconnected.
Since no drive signal is supplied to the switching element 11 of the converter B,
Is turned off. Therefore, the current Ids1B flowing through the switching element 11 of the converter B becomes zero current,
The voltage signal 711S based on the detection output of the detection unit 711 of the converter B becomes low. On the other hand, during the off period of the switching element 12 of the converter B, the converter A
When the switching element 11 is turned on, a current flows from the connection point D of the resonance circuit 2 to the resonance circuit 2 of the converter B. The detection unit 714 of the drive signal monitoring circuit 7 according to the present embodiment detects a current flowing in the resonance circuit 2 in both directions. For this reason,
DC voltage signal 714S based on the detection output of detection unit 714 of converter B maintains a high level. As a result, the drive signal monitoring circuit 7 outputs an abnormal signal.

As described above, the drive signal monitoring circuit 7 of this embodiment is
Is the drive signal line 61 of the converter A or B
Since an abnormal signal is output even if the connection between A, 62A, 61B, and 62B is disconnected, an extremely reliable switching power supply can be provided.

The present embodiment also has the advantages and effects of the embodiment shown in FIG. 1, and the change of the arrangement position of the detecting section is possible in the same manner as the embodiment shown in FIG. .

FIGS. 9 and 10 are electric circuit diagrams showing still another embodiment of the switching power supply unit according to the present invention. FIG.
FIG. 1 is a circuit diagram showing a specific circuit configuration of the converter A, and FIG.
0 is a circuit diagram showing a specific circuit configuration of converter B combined with converter A shown in FIG. FIG.
Although the circuit diagram of FIG. 10 should originally be displayed as one circuit diagram, it is divided into two diagrams for the sake of space.

The drive signal monitoring circuit 7 of the present embodiment is provided for each of the converters A and B.
And a signal processing unit 72. The detector 712 has the same circuit configuration as the detector 712 shown in FIG. 2 and is arranged at the same position. The detection unit 715 includes the resonance inductor 2
2 includes a diode connected to the other end. The diode detects a voltage applied to the resonance element when the switching element 12 is turned on, and supplies a detection output to the signal processing unit 72.
The signal processing unit 72 has the same configuration as the signal processing unit 72 shown in FIG. 2, and when the voltage signal 712S based on the detection output of the detection unit 712 falls below the voltage signal 715S based on the detection output of the detection unit 715. Outputs an abnormal signal. Therefore, when the connection between the drive signal lines 62A and 62B is disconnected, an abnormal signal is output.

The drive signal monitoring circuit 7 of the present embodiment monitors the drive signal by comparing the current flowing through the switching element 12 with the voltage applied to the resonance element of the resonance circuit 2. Therefore, the number of expensive current detection components such as a current transformer is reduced, which is effective in terms of price, power loss, and component mounting. To detect the applied voltage, the resonance capacitor 2
1, any of the resonance inductor 22 and the transformer 3 may be used. Further, the detection unit 712 is connected to the switching element 11.
Is arranged at a position where the current flowing through the
By changing the diode in the opposite direction, the drive signal line 6
An abnormal signal is output even when the connection between 1A and 61B is disconnected. Further, the number of the detection units 712 is set to two, and the detection units 712 are arranged so as to be able to detect the current flowing through each of the switching elements 11 and 12. By doing so, an abnormal signal is output even if any of the drive signal lines 61A, 62A, 61B, 62B is disconnected.

FIGS. 11 and 12 are circuit diagrams showing still another embodiment of the switching power supply according to the present invention. FIG.
FIG. 1 is a circuit diagram showing a specific circuit configuration of the converter A, and FIG.
2 is a circuit diagram showing a specific circuit configuration of converter B combined with converter A shown in FIG. Although the circuit diagrams in FIGS. 11 and 12 should originally be displayed as one circuit diagram, they are divided into two diagrams for the sake of space.

The drive signal monitoring circuit 7 of the present embodiment is provided for each of the converters A and B.
And a signal processing unit 72. The detector 712 has the same circuit configuration as the detector 712 shown in FIG. 2 and is arranged at the same position. The detection unit 716 includes a current transformer provided between one end of the second secondary winding 322 of the transformer 3 and the rectifier diode 432, and a diode that rectifies and outputs one-way output. The diode detects a current flowing through the second secondary winding 322 of the transformer 3 when the switching element 12 is turned on, and outputs a detection output to the signal processing unit 7.
Feed to 2.

The signal processing section 72 has the same configuration as the signal processing section 72 shown in FIG. 2, and a voltage signal 712S based on a detection output of the detection section 712 is converted into a voltage signal 716S based on a detection output of the detection section 716. Outputs an abnormal signal when it falls below the threshold. Therefore, when the connection between the drive signal lines 62A and 62B is disconnected, an abnormal signal is output.

The drive signal monitoring circuit 7 of this embodiment monitors a drive signal by comparing a current flowing through the switching element 12 with a current flowing on the secondary side of the transformer 3. For this reason, when the control circuit is disposed on the secondary side, there is an advantage that the insulation distance of the current transformer disposed on the secondary side can be reduced. Further, it is possible to use the current transformer for output overcurrent detection as well, which is effective in terms of cost and component mounting.

If the detection unit 712 is arranged at a position where the current flowing through the switching element 11 can be detected and the detection unit 716 is arranged at a position where the current flowing through the first secondary winding 321 of the transformer 3 can be detected, the driving signal Line 61A, 61B
An abnormal signal is output even if the connection is disconnected. Furthermore,
The number of the detection units 712 is two, and each switching element 1
Any of the drive signal lines 61A can be detected by arranging them so that the current flowing through the first and second secondary windings 321 and 322 can be detected. , 62A, 61B, and 62B are disconnected, the abnormal signal is output.

FIGS. 13 and 14 are circuit diagrams showing still another embodiment of the switching power supply according to the present invention. FIG. 13 is a circuit diagram showing a specific circuit configuration of converter A,
FIG. 14 is a circuit diagram showing a specific circuit configuration of converter B combined with converter A shown in FIG. Although the circuit diagrams in FIGS. 13 and 14 are originally to be displayed as one circuit diagram, for convenience of space,
Are shown in two figures.

The drive signal monitoring circuit 7 of this embodiment is provided for each of the converters A and B, and the detectors 713 and 717 are respectively provided.
And a signal processing unit 72. The detector 713 has the same circuit configuration as the detector 713 shown in FIG. 2 and is arranged at the same position. The detecting unit 717 includes the switching element 12
Including a diode connected to the gate of the switch. The diode detects a drive signal voltage of the switching element 12 and supplies a detection output to the signal processing unit 72. The signal processing unit 72 has the same circuit configuration as the signal processing unit 72 shown in FIG.
The voltage signal 717S based on the detection output of the detection unit 717 is
When the voltage falls below the voltage signal 713S based on the detection output of the detection unit 713, an abnormal signal is output. Therefore, when the connection between the drive signal lines 62A and 62B is disconnected, an abnormal signal is output.

The drive signal monitoring circuit 7 of the present embodiment monitors the drive signal by comparing the drive signal voltage of the switching element 12 with the current flowing through the resonance circuit 2. Therefore, the number of expensive current detection components such as a current transformer is reduced, which is effective in terms of price, power loss, and component mounting.

If the detection unit 717 is arranged at a position where the drive signal voltage of the switching element 11 can be detected, and the detection unit 713 is configured to detect the current flowing through the resonance circuit 2 when the switching element 11 is turned on, the drive signal line 61
An abnormal signal is output even when the connection between A and 61B is disconnected. Further, the number of the detectors 717 is set to two, and they are arranged so as to be able to detect the drive signal voltages of the switching elements 11 and 12. The detector 713 has the same circuit configuration as the detector 714 shown in FIG. If the configuration is such that current in both directions flowing through the circuit 2 can be detected, an abnormal signal is output even if any of the drive signal lines 61A, 62A, 61B, and 62B is disconnected.

FIGS. 15 and 16 are circuit diagrams showing still another embodiment of the switching power supply according to the present invention. FIG. 15 is a circuit diagram showing a specific circuit configuration of converter A,
FIG. 16 is a circuit diagram showing a specific circuit configuration of converter B combined with converter A shown in FIG. The circuit diagrams in FIGS. 15 and 16 should be originally displayed as one circuit diagram.
Are shown in two figures.

The drive signal monitoring circuit 7 of this embodiment is provided for each of the converters A and B, and the detectors 715 and 717 are respectively provided.
And a signal processing unit 72. The detector 715 has the same circuit configuration as the detector 715 shown in FIG. 4 and is arranged at the same position. The detection unit 717 is the detection unit 717 shown in FIG.
And has the same circuit configuration as that of FIG. Each of the detection units 715 and 717 supplies a detection output to the signal processing unit 72. The signal processing unit 72 has the same circuit configuration as the signal processing unit 72 shown in FIG.
The voltage signal 717S based on the detection output of the
When the voltage falls below the voltage signal 715S based on the 15 detection outputs, an abnormal signal is output. Therefore, the drive signal line 62
When the connection between A and 62B is disconnected, an abnormal signal is output.

The drive signal monitoring circuit 7 of the present embodiment monitors the drive signal by comparing the drive signal voltage of the switching element 12 with the voltage applied to the resonance element of the resonance circuit 2. This eliminates the need for expensive current detection components such as a current transformer, and is effective in terms of price, power loss, and component mounting. To detect the applied voltage, the resonance capacitor 2
1, any of the resonance inductor 22 and the transformer 3 may be used.

Although not shown, the detection unit 717 is
By disposing the switching element 11 at a position where the driving signal voltage can be detected and changing the diode of the detection unit 715 in the opposite direction, an abnormal signal is output even when the connection of the driving signal lines 61A and 61B is disconnected.

Further, the number of the detectors 717 is set to two, and they are arranged so as to be able to detect the drive signal voltages of the respective switching elements 11 and 12. The detector 715 also has a bidirectional voltage applied to the resonance elements of the resonance circuit 2. Can be detected,
Any of the drive signal lines 61A, 62A, 61B, 62B
An abnormal signal is output even when the connection is disconnected.

FIGS. 17 and 18 are circuit diagrams showing still another embodiment of the switching power supply according to the present invention. FIG. 17 is a circuit diagram showing a specific circuit configuration of converter A,
FIG. 18 is a circuit diagram showing a specific circuit configuration of converter B combined with converter A shown in FIG. The circuit diagrams in FIGS. 17 and 18 are originally to be displayed as one circuit diagram.
Are shown in two figures.

The drive signal monitoring circuit 7 of this embodiment is provided for each of the converters A and B, and the detectors 716 and 717 are provided respectively.
And a signal processing unit 72. The detector 716 has the same circuit configuration as the detector 716 shown in FIG. 5, and is arranged at the same position. The detector 717 has the same circuit configuration as the detector 717 shown in FIGS. 15 and 16 and is arranged at the same position. Each of the detection units 716 and 717 supplies a detection output to the signal processing unit 72. Signal processing unit 72
Has the same circuit configuration as the signal processing unit 72 shown in FIG.
S is a voltage signal 716 based on the detection output of the detection unit 716
When the value falls below S, an abnormal signal is output. Therefore, when the connection between the drive signal lines 62A and 62B is disconnected, an abnormal signal is output.

The drive signal monitoring circuit 7 of the present embodiment monitors the drive signal by comparing the drive signal voltage of the switching element 12 with the current flowing on the secondary side of the transformer 3. For this reason, when the control circuit is disposed on the secondary side, the insulation distance of the current transformer disposed on the secondary side can be reduced, and the current transformer for output overcurrent detection can also be used. . In addition, the number of expensive current detection components such as a current transformer is reduced, which is effective in terms of price, power loss, and component mounting.

If the detection unit 717 is arranged at a position where the drive signal voltage of the switching element 11 can be detected and the detection unit 716 is arranged at a position where the current flowing through the first secondary winding 321 of the transformer 3 can be detected, Signal lines 61A, 61
Even when the connection of B is disconnected, an abnormal signal is output.

Further, the number of the detectors 717 is set to two, and they are arranged so as to detect the drive signal voltages of the respective switching elements 11 and 12. The detectors 716 are also provided with the first and second secondary windings 321 and 322. If it is arranged at a position where the current flowing through can be detected, any of the drive signal lines 61A, 62A, 61B,
Even if the connection of 62B is disconnected, an abnormal signal is output.

FIGS. 19 and 20 are circuit diagrams showing still another embodiment of the switching power supply unit according to the present invention. FIG. 19 is a circuit diagram showing a specific circuit configuration of converter A,
FIG. 20 is a circuit diagram showing a specific circuit configuration of converter B combined with converter A shown in FIG. Although the circuit diagrams in FIGS. 9 and 20 should be originally displayed as one circuit diagram, the circuit diagrams are divided into two diagrams for the sake of space.

This embodiment shows an example in which each switching element is driven using a pulse transformer in the switching power supply according to the present invention shown in FIG. This indicates that the pulse transformer can be used also in the embodiments shown in FIGS. Hereinafter, the configuration of the pulse transformer will be described.

Each of the converters A and B of this embodiment includes a pulse transformer 13 for driving the switching elements 11 and 12, respectively. Pulse transformer 13 of each converter A, B
Includes a primary winding 131 and two secondary windings 133 and 134 corresponding to the number of switching elements. The primary windings 131 of the pulse transformers 13 of the converters A and B are connected to the drive signal terminals 941 and 942 so as to be parallel to each other. Each of the secondary windings 133 and 134 is connected between the gate and the source of the switching elements 11 and 12 so that the polarities thereof are opposite to each other.

The pulse transformer 13 configured as described above
Are supplied from the control circuit 6 to the drive signal lines 61A, 62A, 6A.
By supplying drive signals having different phases through 1B and 62B, the switching elements 11 and 12 are alternately driven.

Further, in this embodiment, a configuration of a drive signal monitoring circuit suitable for using a pulse transformer is shown.

The drive signal monitoring circuit 7 of the present embodiment is provided for each of the converters A and B.
9, 710 and the signal processing unit 72. Detection unit 718,
719 is a primary winding 131 of the pulse transformer 13 respectively.
When drive signals having different phases are supplied from the control circuit 6, one of the different signals is detected and supplied to the signal processing section 72. The detection unit 710 is connected to the output terminals 921 and 922 of the converters A and B via a resistor, detects the output voltages of the converters A and B, and supplies the output voltages to the signal processing unit 72.

The signal processing section 72 includes a signal level setting circuit 72
1 and a comparison circuit 722. Signal level setting circuit 72
1 is provided separately for the detection units 718 and 719 and for the detection unit 710, and includes a resistor and a capacitor, respectively. The signal level setting circuit 721 for the detection units 718 and 719 collects the detection outputs detected by the detection units 718 and 719, adjusts the level by the resistor and the capacitor, and compares the voltage signal 718S that can be compared by the comparison circuit 722. , 719S, and supplies it to one input terminal of the comparison circuit 722. The signal level setting circuit 721 for the detecting unit 710 also converts the detection output detected by the detecting unit 710 into a voltage signal 710 S that can be adjusted by the resistor and the capacitor and compared by the comparing circuit 722. It is supplied to the other input terminal of the comparison circuit 722.

The comparing circuit 722 compares the voltage signals 718S and 719S supplied to one input terminal with the voltage signal 710S supplied to the other input terminal, and detects a voltage based on the detection output of the detection unit 718 or the detection unit 719. Signal 718
S, 719S is the detection unit 7 supplied to the other input terminal.
An abnormal signal is output when the voltage falls below the voltage signal 710S based on the ten detection outputs. Accordingly, the drive signal monitoring circuit 7 of the present embodiment outputs an abnormal signal even if the connection of any of the drive signal lines 61A, 62A, 61B, 62B of the converters A and B is cut off.

The drive signal monitoring circuit 7 of this embodiment monitors the drive signal by comparing the primary voltage of the pulse transformer 13 for driving the switching elements 11 and 12 with the output voltages of the converters A and B. For this reason, since it can be electrically insulated from the primary sides of the converters A and B, there is an advantage that all signal processing can be performed on the secondary sides of the converters A and B. Further, since expensive current detection components such as a current transformer are not required, there are effects in terms of price, power loss, and component mounting.

Although the contents of the present invention have been described in detail 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.

[0127]

As described above, according to the present invention, the following effects can be obtained. (A) It is possible to provide a switching power supply device of a parallel operation system capable of promptly taking measures against an abnormality even if an abnormality occurs in the parallel connection and an overcurrent occurs in the converter. (B) It is possible to provide a highly reliable switching power supply of a parallel operation type capable of preventing other troubles such as circuit damage due to occurrence of overcurrent and imbalance of power sharing between converters. (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 circuit diagram showing a specific circuit configuration of a converter A in another embodiment of the switching power supply device according to the present invention.

FIG. 3 is a circuit 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 in the switching power supply device shown in FIGS.

FIG. 5 is a voltage and current waveform diagram of each part of the converter when the connection of the drive signal line of the converter B is disconnected.

FIG. 6 is a voltage and current waveform diagram of each part of the converter when the connection of the drive signal line is disconnected.

FIG. 7 is a circuit diagram showing a specific circuit configuration of a converter A in still another embodiment of the switching power supply device according to the present invention.

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

FIG. 9 is a circuit diagram showing a specific circuit configuration of a converter A in still another embodiment of the switching power supply device according to the present invention.

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

FIG. 11 is a circuit diagram showing a specific circuit configuration of a converter A in still another embodiment of the switching power supply device according to the present invention.

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

FIG. 13 is a circuit diagram showing a specific circuit configuration of a converter A in still another embodiment of the switching power supply device according to the present invention.

FIG. 14 is a circuit diagram showing a specific circuit configuration of converter B combined with converter A shown in FIG.

FIG. 15 is a circuit diagram showing a specific circuit configuration of a converter A in still another embodiment of the switching power supply device according to the present invention.

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

FIG. 17 is a circuit diagram showing a specific circuit configuration of converter A in still another embodiment of the switching power supply device according to the present invention.

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

FIG. 19 is a circuit diagram showing a specific circuit configuration of a converter A in still another embodiment of the switching power supply device according to the present invention.

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

[Explanation of symbols]

 A, B converter 1 switching circuit 11, 12 switching element 13 pulse transformer 2 resonance circuit 3 transformer 4 output rectification smoothing circuit 5 output voltage detection circuit 6 control circuit 7 drive signal monitoring circuit 8 abnormality display means T0 load connection end

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H730 AA15 AA20 AS01 BB26 BB57 BB62 BB82 BB88 DD04 DD22 EE03 EE08 FD01 FD21 FD51 XX04 XX11 XX25 XX35 XX42 XX50

Claims (11)

[Claims] 1. A switching power supply device including a plurality of converters, an output voltage detection circuit, a control circuit, and a drive signal monitoring circuit, wherein each of the plurality of converters includes a switching circuit, an output rectifying and smoothing circuit. The output side is connected in parallel to each other to form a load connection end, The switching circuit includes at least one switching element, switches the supplied DC voltage, The output rectification smoothing circuit, Rectifying and smoothing a switching output to output 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; Supplies a drive signal to the switching circuit based on the output voltage signal, so that the voltage at the load connection terminal is stabilized. Controls the switching of the quenching circuit, the drive signal monitoring circuit monitors the drive signals, the drive signal switching power supply unit for outputting an abnormality signal when an abnormal state. 2. The switching power supply device according to claim 1, wherein the control circuit stops driving the switching circuit when the abnormal signal is output. 3. The switching power supply according to claim 1, further comprising an abnormality display unit, wherein the abnormality display unit displays an abnormal state when the abnormality signal is output. apparatus. 4. The switching power supply according to claim 1, wherein each of the plurality of converters further includes a transformer and a resonance circuit, wherein the transformer has a primary winding. And a secondary winding. Each of the resonance circuits is connected to each other. The switching circuit includes two switching elements driven alternately, and a primary winding of the transformer via the resonance circuit. A switching power supply device for supplying a resonance current to the transformer, wherein the output rectifying / smoothing circuit rectifies and smoothes a voltage induced in a secondary winding of the transformer. 5. The switching power supply device according to claim 4, wherein the drive signal monitoring circuit monitors a drive signal by comparing a current flowing in the switching element with a resonance current flowing in the resonance circuit. Switching power supply. 6. The switching power supply device according to claim 4, wherein the drive signal monitoring circuit compares a current flowing through the switching element with a voltage applied to a resonance element of the resonance circuit. Monitoring the switching power supply. 7. The switching power supply device according to claim 4, wherein the drive signal monitoring circuit monitors a drive signal by comparing a current flowing through the switching element with a secondary current of the transformer. Switching power supply. 8. The switching power supply device according to claim 4, wherein the drive signal monitoring circuit monitors a drive signal by comparing a drive signal voltage of the switching element with a current flowing through the resonance circuit. Switching power supply. 9. The switching power supply device according to claim 4, wherein the drive signal monitoring circuit drives by comparing a drive signal voltage of the switching element with an applied voltage of a resonance element of the resonance circuit. A switching power supply that monitors signals. 10. The switching power supply device according to claim 4, wherein the drive signal monitoring circuit compares a drive signal voltage of the switching element with a secondary current of the transformer to generate a drive signal. Switching power supply to monitor. 11. The switching power supply device according to claim 1, wherein the switching element is driven by a pulse transformer, and the drive signal monitoring circuit includes: a primary side voltage of the pulse transformer; A switching power supply for monitoring a drive signal by comparing the output voltage of the converter with an output voltage of the converter.