JPH11252923A - Switching converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a switching converter, provided with an inexpensive space- saving rush current suppressing circuit which allows more rushes. SOLUTION: One side of the DC bus of a rectifier circuit 2 composed of a rectifier element bridge is connected to the DC bus of a switching bridge 22, and the other side of the DC bus of the circuit 2 is connected to the DC bus of the bridge 22 through a semiconductor switch circuit 5 constituted by connecting a serial body 4 of a resistor and a capacitor, in parallel with a switching element 3. When power supply is made, a smoothing capacitor 23 is charged via the switch circuit 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching converter comprising a switching element and obtaining a DC power supply from an AC power supply.

[0002]

2. Description of the Related Art FIG. 27 is a diagram showing a circuit configuration of a switching converter as a conventional converter device.
In the figure, 21 is a commercial AC power supply, 22 is a switching bridge which is constituted by a switching element, receives an AC power supply, converts it into a DC voltage, and outputs it, 23 is a smoothing capacitor connected to the switching bridge 22 for smoothing the DC voltage, Reference numeral 24 denotes a load connected to the output side of the switching bridge 22. 25 is a switching bridge 22
And a smoothing capacitor 23. The switching converter includes a main circuit 25 and an inrush current suppressing circuit 29 described later. Reference numeral 26 denotes a noise reduction capacitor provided between the main circuit 25 and ground to prevent noise generated by switching of the switching bridge 22 from entering other devices connected to the switching converter. 27 is an inrush resistor for limiting the inrush current, 28 is an inrush relay, 29 is an inrush resistor 2
7 and a relay 28. Reference numeral 30 denotes a contactor that is turned off when the power is turned on and turned on during normal operation.

When the power is turned on, the relay 28 is turned on as an inrush operation before the normal operation starts, and the smoothing capacitor 23 is charged by connecting the commercial AC power supply 21 to the input of the switching bridge 22 via the inrush resistor 27. . During normal operation, when the contactor 30 is turned on, the commercial AC power supply 21 and the switching bridge 22 are connected, and power required for a load is supplied to the main circuit 25 via the contactor 30.

A contact relay such as an electromagnetic contactor is generally used as the relay 28. A triac or thyristor (hereinafter, referred to as S) is used for the contact relay.
Solid State Relay (Solid Stat) which is a contactless relay using a semiconductor element such as CR
e Relay (hereinafter referred to as SSR), which has the characteristics of (1) long life, high reliability, (2) high-speed opening / closing response, and (3) direct drive with minute output such as IC, etc. It has been used for on / off control of solenoid valves, lamps, heaters, motors, electromagnetic switches, and the like connected to a power supply.

[0005]

In the conventional switching converter as described above, the relay 28 is connected to the inrush circuit 29.
, There is a problem that the number of allowable rushes is limited by the ON / OFF life of the relay 28. Further, when the relay 28 is simply replaced with an SSR which is a non-contact relay using a semiconductor element, a snubber circuit is required for the SSR. There was a problem of being charged.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to realize a switching converter having an inrush current suppressing circuit which is reduced in cost and space, while increasing the allowable number of inrushes. Aim.

[0007]

In a switching converter according to the present invention, a rectifying circuit comprising a rectifying element bridge, a rush resistor for limiting a current connected between the rectifying circuit and an AC power supply, A semiconductor switch circuit composed of a series connection of a capacitor and a parallel connection of a switching element;
One of the DC buses of the rectifier circuit is connected to the DC bus of the switching bridge, and the other of the DC bus of the rectifier circuit is connected to the DC bus of the switching bridge via a semiconductor switch circuit. In this case, the smoothing capacitor is charged.

Further, in the switching converter according to the present invention, a rectifying circuit comprising a rectifying element bridge, a rush resistor for limiting a current connected between the rectifying circuit and the AC power supply, and a series connection of the resistor and the capacitor. A rush current suppression circuit consisting of a parallel connection of a body and a switching element; and a rectifier circuit, wherein both the positive and negative sides of the DC bus of the rectifier circuit are connected to the DC of the switching bridge via the semiconductor switch circuit. It is connected to a bus and charges the smoothing capacitor via a semiconductor switch circuit when power is turned on.

Furthermore, a resistor is connected in parallel to the rectifier circuit.

Furthermore, a voltage limiting element is connected in parallel with the rectifier circuit.

Also, a capacitor is connected in parallel to the rectifier circuit.

Further, in the switching converter according to the present invention, a semiconductor switch circuit bridge comprising a semiconductor switch circuit composed of a series connection of a resistor and a capacitor and a parallel connection of a switching element, and the semiconductor switch A rush current suppressing circuit comprising a rush resistor for limiting current connected between a circuit bridge and an AC power supply, wherein a dc bus of a semiconductor switch circuit bridge and a dc bus of a switching bridge are connected. It is.

Furthermore, a voltage limiting element is connected in parallel to a semiconductor switch circuit constituting a semiconductor switch circuit bridge.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a diagram showing a circuit configuration of a switching converter according to an embodiment of the present invention. In the figure, 21 to 27 and 30 are the same as those in FIG. 27 of the conventional example, and the description thereof is omitted.
1 is a diode as a rectifying element, 2 is a rectifying circuit configured by a bridge of a diode 1, 3 is an SCR as a switching element, 4 is a snubber circuit configured as a series body of a resistor and a capacitor, 5 is an SCR 3 and a snubber circuit 4 Is a semiconductor switch circuit configured by parallel connection with 6
Reference symbol a denotes an inrush current suppression circuit including the inrush resistor 27, the rectifier circuit 2, and the semiconductor switch circuit 5. Inrush current suppressing circuit 6a of the switching converter according to this embodiment
Connects one of the DC buses of the rectifier circuit 2 to the DC bus of the switching bridge 22, and connects the other of the DC buses of the rectifier circuit 2 to the DC bus of the switching bridge 22 via the semiconductor switch circuit 5, and turns on the power. Sometimes, the smoothing capacitor is charged via the semiconductor switch circuit.

FIGS. 2 and 3 are diagrams showing the flow of current in the switching converter according to one embodiment of the present invention. FIG. 4 is a diagram showing voltage waveforms at various parts in the switching converter according to the embodiment of the present invention. In the figure, E is the amplitude of the power supply voltage 21, V1
Is the voltage of the AC power supply 21, and V2 is the noise reduction capacitor 2.
6, V3 is the voltage across SCR3, V4 is the voltage across diode 1 of rectifier circuit 2, i1, i2,
i3 and i4 are currents.

Next, the operation of the switching converter according to the first embodiment will be described with reference to FIGS. SCR
When 3 is off, the smoothing capacitor 23 is not charged,
No output voltage of the main circuit 25 is generated. When the SCR 3 is turned on, a current flows from the AC power supply 21 to the smoothing capacitor 23 through the rush resistor 27 and the rectifier circuit 2. Since the rush resistor 27 limits the current, the smoothing capacitor 23 is gradually charged, and the rush operation is completed.

When the SCR 3 is off, the AC power supply 2
Depending on the polarity of the voltage of 1, the current flowing through the circuit takes a path as shown in FIG. 2 or FIG. When the polarity of the AC power supply 21 is as shown in FIG. 2, the currents i1 and i2 flow through the illustrated path, and are charged to almost E at both ends of the noise reduction capacitor 26, and to almost E at both ends of the snubber circuit 4. . When the polarity of the AC power supply 21 is reversed and the state shown in FIG. 3 is reached, the currents i3 and i4 flow through the illustrated path, and the electric charge discharged from the noise reduction capacitor 26 flows into the snubber circuit 4 and both ends of the snubber circuit 4 Rises to almost twice E. When the polarity of the AC power supply 21 is reversed again, the voltage V3 between the terminals of the snubber circuit 4 has risen to 2E, so that the snubber circuit 4 is not charged, and only the voltage V2 across the noise reduction capacitor 26 is provided. It is almost charged to the voltage E.

In the state shown in FIG. 3, the snubber circuit 4 is charged to approximately 2E, and the voltage between the terminals of the smoothing capacitor 23 is approximately 0 due to the large capacitance of the capacitor. Is conducted, the voltage V4 between the terminals of the diode 1 of the rectifier circuit 2
Is equal to the inter-terminal voltage V3 of the snubber circuit 4. Therefore,
The withstand voltage of the SCR 3 and the diode 1 requires 2E.

FIG. 5 is a diagram showing a circuit configuration of a switching converter according to an embodiment of the present invention. In the figure, 1 to 5, 21 to 27 and 30 are the same as in FIG.
The description is omitted. 6b is an inrush current suppression circuit.
In FIG. 1 described above, the semiconductor switch circuit 5 is provided on the positive electrode side of the inrush current suppression circuit DC section, but FIG. 5 is provided with the semiconductor switch circuit 5 installed on the negative electrode side of the inrush current suppression circuit DC section. It is.

Embodiment 2 FIG. 6 is a diagram showing a circuit configuration of a switching converter according to one embodiment of the present invention. In the figure, 1 to 5, 21 to 27, and 30 are the same as those in FIG. 1, and the description thereof is omitted. 6c is an inrush current suppression circuit, and 7 is a resistor connected between the positive electrode and the negative electrode of the inrush current suppression circuit DC section. The switching converter shown in this embodiment has a configuration in which a resistor 7 for discharging a capacitor in the snubber circuit 4 is added between the positive electrode and the negative electrode of the rush current suppression circuit DC section in FIG.

FIG. 7 is a diagram showing a discharge path of the capacitor of the snubber circuit in the switching converter according to one embodiment of the present invention. FIG. 8 is a diagram showing voltage waveforms at various parts of the switching converter according to one embodiment of the present invention. In the figure, E is the amplitude of the power supply voltage 21,
V3 is the voltage across SCR3, V4 is the voltage across diode 1, and i5 is the current.

In this embodiment, since the resistor 7 is added between the positive electrode and the negative electrode of the inrush current suppression circuit DC section, a path for discharging the capacitor in the snubber circuit is formed as shown by the current i5 in FIG. , The voltage V3 between both ends becomes approximately E at the maximum, and the voltage V4 across the diode 1 also becomes approximately E at the maximum.

Embodiment 3 FIG. FIG. 9 is a diagram showing a circuit configuration of a switching converter according to one embodiment of the present invention. In the figure, 1 to 5, 21 to 27, and 30 are the same as those in FIG. 1, and the description thereof is omitted. 6c is an inrush current suppression circuit, 7 is a resistor, and 8 is a voltage limiting element connected in parallel with the resistor 7. FIG. 10 is a diagram showing waveforms of voltages of respective parts of the switching converter according to one embodiment of the present invention. In the figure, E is the amplitude of the power supply voltage 21, V3 is the voltage across SCR3, and V4 is the voltage across diode 1.

In this embodiment, a voltage limiting element 8 is connected in parallel to a resistor 7 connected between the positive electrode and the negative electrode of the inrush current suppression circuit DC section in the second embodiment. In this embodiment, the voltage V4 across the diode 1 is lower than the voltage limited by the voltage limiting element 8. SCR3
Of the power supply voltage is suppressed to be substantially equal to or less than the amplitude E of the power supply voltage, and the withstand voltage of the SCR 3 may be substantially E. Furthermore, the value of the resistor connected between the buses of the rectifier circuit can be made larger than in the second embodiment, and heat generated by the resistor can be suppressed.

Embodiment 4 FIG. 11 is a diagram showing a circuit configuration of a switching converter according to one embodiment of the present invention. In the figure, 1 to 5, 21 to 27 and 30 are:
It is the same as FIG. 1 and the description is omitted. 6e is an inrush current suppression circuit. In this embodiment, the semiconductor switch circuit 5 is provided on both the positive electrode side and the negative electrode side of the rush current suppression circuit DC section, and has a configuration obtained by combining FIGS. 1 and 5 in the first embodiment. is there.

FIGS. 12 and 13 are diagrams showing a current flow in the switching converter according to one embodiment of the present invention. FIG. 14 is a diagram showing voltage waveforms at various parts in the switching converter according to one embodiment of the present invention. In the figure, E is the amplitude of the power supply voltage 21, V1
Is the voltage of the AC power supply 21, and V2 is the noise reduction capacitor 2.
6, V3 is a voltage across the SCR3, V4 is a voltage across the diode 1 of the rectifier circuit 2, and i6, i7 are currents.

Next, a fourth embodiment will be described with reference to FIGS.
The operation of the switching converter of FIG. The AC power supply 21 is connected to the rectifier circuit 2 through the inrush resistor 27 and becomes a DC, and the current is turned on / off by the semiconductor switching circuit 5. When both the SCR3 of the semiconductor switch circuit 5 installed on the positive side of the inrush current suppression circuit DC section and the SCR3 of the semiconductor switch circuit 5 installed on the negative side of the inrush current suppression circuit DC section are off Depending on the polarity of the voltage of the AC power supply 21, a current flows as shown in FIGS.

Voltage V across diode 1 of rectifier circuit 2
4 is at most twice the amplitude E of the power supply voltage, so the withstand voltage of the diode 1 needs to be twice as large as E. However, since the voltage V2 across the noise reduction capacitor 26 is a voltage divided by the circuit constant, it can be kept low, and the voltage V3 across the SCR3 becomes almost E. Therefore, the withstand voltage of the SCR 3 only needs to be substantially E.

Embodiment 5 FIG. 15 is a diagram showing a circuit configuration of a switching converter according to one embodiment of the present invention. In the figure, 1 to 5, 21 to 27 and 30 are:
It is the same as FIG. 1 and the description is omitted. 6f is an inrush current suppression circuit. This embodiment is different from the above-described fourth embodiment in which the semiconductor switch circuit 5 is installed on both the positive electrode side and the negative electrode side of the inrush current suppression circuit DC section, between the positive electrode and the negative electrode of the inrush current suppression circuit DC section. A resistor 7 for discharging a capacitor in the snubber circuit is added.

FIG. 16 is a diagram showing a discharge path of the capacitor of the snubber circuit in the switching converter according to one embodiment of the present invention. FIG. 17 shows an SCR3 in a switching converter according to an embodiment of the present invention.
And the voltage V4 across the diode 1
FIG. 5 is a diagram showing voltage waveforms of FIG. In the figure, E is the amplitude of the power supply voltage 21, V3 is the voltage across SCR3, V4 is the voltage across diode 1, and i8 is the current.

The inrush current suppressing circuit A discharge path is formed as shown by the current i8 in FIG. 16 by the resistor 7 for discharging the capacitor in the snubber circuit added between the positive electrode and the negative electrode of the DC section.
Since the voltage at both ends of the SCR 3 is prevented from increasing, the withstand voltage of both the SCR 3 and the diode 1 may be approximately E.

Embodiment 6 FIG. FIG. 18 is a diagram showing a circuit configuration of a switching converter according to one embodiment of the present invention. In the figure, 1 to 5, 21 to 27 and 30 are:
It is the same as FIG. 1 and the description is omitted. 6g is a rush current suppressing circuit, 8 is a voltage limiting element connected in parallel with the resistor 7, and V5 is a voltage of the rectifier circuit 2. FIG. 19 is a diagram showing a voltage waveform of the rectifier circuit 2 of the switching converter according to one embodiment of the present invention.

In this embodiment, a voltage limiting element 8 is connected in parallel to a resistor 7 for discharging a capacitor in a snubber circuit installed between a positive electrode and a negative electrode of a rush current suppressing circuit in the fifth embodiment. And the fifth embodiment described above.
Therefore, the value of the resistor 7 can be made larger than that of the resistor 7, and heat generation by the resistor can be suppressed. Further, the ripple of the DC part of the inrush current suppression circuit can be limited to the limited voltage or less by the voltage limiting element 8.

Embodiment 7 FIG. 20 is a diagram showing a circuit configuration of a switching converter according to one embodiment of the present invention. In the figure, 1 to 5, 21 to 27 and 30 are:
It is the same as FIG. 1 and the description is omitted. 6h is an inrush current suppression circuit, 9 is a capacitor, and V5 is a voltage of the rectifier circuit 2. FIG. 21 is a diagram showing a voltage waveform of the rectifier circuit 2 of the switching converter according to one embodiment of the present invention. In the figure, (a) is a voltage waveform in the case of the above-described fifth embodiment, and (b) is a resistor 7 for discharging a capacitor in a snubber circuit installed between a positive electrode and a negative electrode of a rush current suppression circuit DC section.
3 shows a voltage waveform in the case of this embodiment in which a capacitor 9 is connected in parallel.

In this embodiment, a capacitor 9 is connected in parallel to a resistor 7 for discharging a capacitor in a snubber circuit provided between a positive electrode and a negative electrode of a rush current suppressing circuit DC part in the above-described fifth embodiment. . The capacitor 9 smoothes the ripple in the DC portion of the inrush current suppression circuit,
The voltage applied to the diode can be suppressed.

Embodiment 8 FIG. FIG. 22 is a diagram showing a circuit configuration of a switching converter according to an embodiment of the present invention. In the figure, 21 to 27 and 30 are the same as those in FIG. 27 of the conventional example, and the description thereof is omitted. Reference numeral 3 denotes an SCR as a switching element, 4 denotes a snubber circuit configured as a series body of a resistor and a capacitor, and 5 denotes a semiconductor switch circuit including the SCR 3 and a snubber circuit 4. 10a is a thyristor bridge as a semiconductor switch circuit bridge composed of four semiconductor switch circuits 5, and 11a is an inrush resistor 27 and a thyristor bridge 10a.
And a rush current suppressing circuit composed of

FIGS. 23 and 24 show current flows in the switching converter according to one embodiment of the present invention. FIG. 25 is a diagram showing voltage waveforms at various parts of the switching converter according to one embodiment of the present invention. In the figure, E is the amplitude of the power supply voltage 21, V1 is the waveform of the AC power supply voltage 21, and V6 and V7 are the waveforms of the voltage across the SCR.

Next, the operation of the switching converter of this embodiment will be described with reference to FIGS.
The AC power supply 21 is connected to the thyristor bridge 10a through the inrush resistor 27, and is rectified by the thyristor bridge 10a to be a direct current when the four semiconductor switch circuits 5 are on, so that a current flows. Also, when the four semiconductor switch circuits 10a are off, current flows through the circuits as shown in FIGS. 23 and 24 depending on the polarity of the voltage of the AC power supply. The arrow in the figure is the direction of the current.

Since the voltage at both ends of the SCR is a voltage divided by the circuit constant, the voltage can be suppressed lower than the amplitude E of the power supply voltage. Therefore, the withstand voltage of the SCR only needs to be E. Further, since the voltage applied to the semiconductor element can be suppressed to E or less without providing a discharge resistor, power loss at the discharge resistor can be suppressed. Furthermore, in order to prevent the switching converter from being damaged even if another power supply system is grounded, it is necessary to design a voltage circuit that does not exceed the withstand voltage of the semiconductor element. Generally, components for high withstand voltage are used. In this embodiment, by selecting a constant, the voltage applied to the semiconductor element can be suppressed to about E even when another 400 V power supply is grounded.

Embodiment 9 FIG. 26 is a diagram showing a circuit configuration of a switching converter according to one embodiment of the present invention. In the figure, reference numerals 3 to 5, 21 to 27, and 30 are the same as those in FIG. 22 of the eighth embodiment, and a description thereof will be omitted. Reference numeral 12 denotes a voltage limiting element connected in parallel to the semiconductor switch circuit 5, 10b denotes a thyristor bridge composed of four semiconductor switch circuits 5 and four voltage limiting elements 12 connected in parallel to the semiconductor switch circuit 5, 11
“b” denotes an inrush current suppression circuit including the inrush resistor 27 and the thyristor bridge 10b.

In this embodiment, the voltage limiting element 12 is connected in parallel to the semiconductor switch circuit 5 constituting the thyristor bridge 10a shown in FIG. SCR3 can be prevented from being damaged even when a ground fault occurs.

[0042]

Since the present invention is configured as described above, it has the following effects.

In the switching converter according to the present invention, a rectifying circuit comprising a rectifying element bridge, a rush resistor for limiting a current connected between the rectifying circuit and the AC power supply, and a series body of a resistor and a capacitor are provided. A rush current suppressing circuit comprising a semiconductor switch circuit configured in parallel with a switching element, and connecting one of the DC buses of the rectifier circuit to the DC bus of the switching bridge and the other of the DC bus of the rectifier circuit. Is connected to the DC bus of the switching bridge via the semiconductor switch circuit, and the smoothing capacitor is charged via the semiconductor switch circuit when the power is turned on. A switching converter provided with a suppression circuit can be realized.

Further, in the switching converter according to the present invention, a rectifying circuit comprising a rectifying element bridge, a rush resistor for limiting a current connected between the rectifying circuit and the AC power supply, and a series connection of the resistor and the capacitor. A rush current suppression circuit consisting of a parallel connection of a body and a switching element; and a rectifier circuit, wherein both the positive and negative sides of the DC bus of the rectifier circuit are connected to the DC of the switching bridge via the semiconductor switch circuit. Since the power supply is connected to the bus and the smoothing capacitor is charged via the semiconductor switch circuit when the power is turned on, the voltage at both ends of the semiconductor switch circuit can be suppressed to the maximum voltage of the AC power supply or less.

Further, since the resistor is connected in parallel to the rectifier circuit, the voltage at both ends of the semiconductor switch circuit and the voltage at both ends of the rectifier element of the rectifier circuit can be suppressed below the maximum voltage of the AC power supply.

Furthermore, since the voltage limiting element is connected in parallel to the rectifier circuit, the peak of the voltage between the buses of the rectifier circuit can be suppressed below the limit voltage. Further, the value of the resistor connected between the buses of the rectifier circuit can be increased, and the heat generated by the resistor can be suppressed.

Further, since a capacitor is connected in parallel to the rectifier circuit, the peak of the bus voltage of the rectifier circuit can be suppressed. Further, the value of the resistor connected between the buses of the rectifier circuit can be increased, and the heat generated by the resistor can be suppressed.

Further, in the switching converter according to the present invention, a semiconductor switch circuit bridge comprising a semiconductor switch circuit composed of a series connection of a resistor and a capacitor and a parallel connection of a switching element, and this semiconductor switch A rush current suppression circuit consisting of a rush resistor for current limiting connected between the circuit bridge and the AC power supply is provided, and the DC bus of the semiconductor switch circuit bridge and the DC bus of the switching bridge are connected. Further, the voltage at both ends of the semiconductor switch circuit can be suppressed to the maximum voltage of the AC power supply or less. In addition, since it is not necessary to add a discharge resistor, power loss can be reduced, and the number of components can be reduced, so that a rush current suppressing circuit can be realized at low cost and space.

Further, since the voltage limiting element is connected in parallel to the semiconductor switch circuit constituting the semiconductor switch circuit bridge, it is possible to prevent the thyristor from being damaged even when a power supply system other than the 400 V system is grounded.

[Brief description of the drawings]

FIG. 1 is a diagram showing a circuit configuration of a switching converter according to an embodiment of the present invention.

FIG. 2 is a diagram showing a current flow in a switching converter according to an embodiment of the present invention.

FIG. 3 is a diagram showing a current flow in a switching converter according to an embodiment of the present invention.

FIG. 4 is a diagram showing waveforms of voltages at respective parts in the switching converter according to the embodiment of the present invention;

FIG. 5 is a diagram showing a circuit configuration of a switching converter according to one embodiment of the present invention.

FIG. 6 is a diagram showing a circuit configuration of a switching converter according to one embodiment of the present invention.

FIG. 7 is a diagram showing a discharge path of a capacitor of a snubber circuit in the switching converter according to one embodiment of the present invention.

FIG. 8 is a diagram showing waveforms of voltages of respective parts of the switching converter according to the embodiment of the present invention.

FIG. 9 is a diagram showing a circuit configuration of a switching converter according to one embodiment of the present invention.

FIG. 10 is a diagram showing waveforms of voltages of respective parts of the switching converter according to one embodiment of the present invention.

FIG. 11 is a diagram showing a circuit configuration of a switching converter according to an embodiment of the present invention.

FIG. 12 is a diagram showing a current flow in the switching converter according to one embodiment of the present invention.

FIG. 13 is a diagram showing a current flow in the switching converter according to one embodiment of the present invention.

FIG. 14 is a diagram showing waveforms of voltages at respective parts in the switching converter according to one embodiment of the present invention;

FIG. 15 is a diagram showing a circuit configuration of a switching converter according to an embodiment of the present invention.

FIG. 16 is a diagram showing a discharge path of a capacitor of a snubber circuit in the switching converter according to one embodiment of the present invention.

FIG. 17 is a diagram showing voltage waveforms of voltage V3 across SCR3 and voltage V4 across diode 1 in the switching converter according to one embodiment of the present invention;

FIG. 18 is a diagram showing a circuit configuration of a switching converter according to one embodiment of the present invention.

FIG. 19 is a diagram showing a voltage waveform of the rectifier circuit 2 of the switching converter according to one embodiment of the present invention.

FIG. 20 is a diagram showing a circuit configuration of a switching converter according to an embodiment of the present invention.

FIG. 21 is a diagram showing a voltage waveform of the rectifier circuit 2 of the switching converter according to one embodiment of the present invention.

FIG. 22 is a diagram showing a circuit configuration of a switching converter according to an embodiment of the present invention.

FIG. 23 is a diagram showing a current flow in the switching converter according to one embodiment of the present invention.

FIG. 24 is a diagram showing a current flow in the switching converter according to one embodiment of the present invention.

FIG. 25 is a diagram showing waveforms of voltages of respective parts of the switching converter according to one embodiment of the present invention.

FIG. 26 is a diagram showing a circuit configuration of a switching converter according to an embodiment of the present invention.

FIG. 27 is a diagram showing a circuit configuration of a switching converter as a conventional converter device.

[Explanation of symbols]

1 diode, 2 rectifier circuit, 3 SCR, 4
Snubber circuit, 5 semiconductor switch circuit, 6a, 6
b, 6c, 6e, 6f, 6g, 6h Inrush current suppression circuit, 7 resistor, 8 voltage limiting element, 9 capacitor, 10a, 10b thyristor bridge, 11
a, 11b Inrush current suppression circuit, 12 voltage limiting element, 21 commercial AC power supply, 22 switching bridge, 23 smoothing capacitor, 24 load, 25
Main circuit, 26 noise reduction capacitor, 27 inrush resistor, 28 relay, 29 inrush current suppression circuit,
30 contactors, E amplitude of power supply voltage 21, V1
Voltage of AC power supply 21, V2 noise reduction capacitor 26
Voltage across V3, V3 voltage across SCR3, V4
The voltage across diode 1; V5 the voltage across rectifier circuit 2; the waveform of the voltage across V6, V7 SCR;
2, i3, i4, i5, i6, i7, i8 current.

Claims (7)

[Claims] A switching bridge for inputting an AC power supply, converting the DC power into a DC voltage, and outputting the DC voltage; a smoothing capacitor for smoothing the DC voltage output from the switching bridge;
A switching converter comprising: a noise reduction capacitor connected to an output side of the switching bridge; and an inrush current suppression circuit connected to an input side of the switching bridge to limit an inrush current. Is composed of a rectifier circuit composed of a rectifier element bridge, a rush resistor for current limitation connected between the rectifier circuit and the AC power supply, and a parallel connection of a series body of the resistor and the capacitor and the switching element. A semiconductor switch circuit, and connecting one of the DC buses of the rectifier circuit to the DC bus of the switching bridge;
The other of the DC bus of the rectifier circuit is connected to the DC bus of the switching bridge via the semiconductor switch circuit, and the smoothing capacitor is charged via the semiconductor switch circuit when power is turned on. Switching converter. 2. A switching bridge for receiving an AC power supply, converting the DC voltage into a DC voltage, and outputting the DC voltage; a smoothing capacitor for smoothing the DC voltage output from the switching bridge;
A switching converter comprising: a noise reduction capacitor connected to an output side of the switching bridge; and an inrush current suppression circuit connected to an input side of the switching bridge to limit an inrush current. Is composed of a rectifier circuit composed of a rectifier element bridge, a rush resistor for current limitation connected between the rectifier circuit and the AC power supply, and a parallel connection of a series body of the resistor and the capacitor and the switching element. And a semiconductor switch circuit, wherein both the positive and negative sides of the DC bus of the rectifier circuit are connected to the DC bus of the switching bridge via the semiconductor switch circuit, and when the power is turned on, via the semiconductor switch circuit. A switching converter, wherein the smoothing capacitor is charged. 3. The switching converter according to claim 1, wherein a resistor is connected in parallel to the rectifier circuit. 4. The switching converter according to claim 3, wherein a voltage limiting element is connected to the rectifier circuit in parallel. 5. The switching converter according to claim 3, wherein a capacitor is connected in parallel to the rectifier circuit. 6. A switching bridge for inputting an AC power supply, converting it to a DC voltage and outputting the DC voltage, a smoothing capacitor for smoothing the DC voltage output from the switching bridge,
A switching converter comprising: a noise reduction capacitor connected to an output side of the switching bridge; and an inrush current suppression circuit connected to an input side of the switching bridge to limit an inrush current. Is connected between a semiconductor switch circuit bridge formed by bridging a semiconductor switch circuit composed of a series connection of a resistor and a capacitor and a parallel connection of a switching element, and the semiconductor switch circuit bridge and an AC power supply. And a rush resistor for limiting current, wherein a DC bus of the semiconductor switch circuit bridge and a DC bus of the switching bridge are connected. 7. The switching converter according to claim 6, wherein a voltage limiting element is connected in parallel to the semiconductor switch circuit forming the semiconductor switch circuit bridge.