JP3509531B2 - Switching converter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching converter which includes a switching element and obtains 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 composed of switching elements and which inputs the AC power supply and converts it into a DC voltage and outputs it, 23 is a smoothing capacitor which is connected to the switching bridge 22 and smoothes the DC voltage, Reference numeral 24 is a load connected to the output side of the switching bridge 22. 25 is a switching bridge 22
And a smoothing capacitor 23, and the switching converter includes a main circuit 25 and an inrush current suppressing circuit 29 described later. Further, 26 is a noise reduction capacitor installed between the main circuit 25 and the ground so as to prevent noise generated by switching of the switching bridge 22 from invading other devices connected to the switching converter. 27 is an inrush resistance for limiting the current at the time of inrush, 28 is a relay for inrush, 29 is an inrush resistance 2
7 is a rush current suppressing circuit composed of 7 and a relay 28. Reference numeral 30 is a contactor that is turned off when the power is turned on and is turned on during normal operation.

When the power is turned on and before the normal operation is started, the relay 28 is turned on as a rush operation, and the commercial AC power source 21 is connected to the input of the switching bridge 22 via the rush resistance 27 to charge the smoothing capacitor 23. . During normal operation, the contactor 30 is turned on to connect the commercial AC power supply 21 and the switching bridge 22, and the electric power required for the 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. In contrast to this contact relay, a triac or a thyristor (hereinafter, S
Solid state relay (Solid Stat), which is a contactless relay that uses semiconductor elements such as CR.
e Relay, hereinafter referred to as SSR), and is characterized by (1) long life, high reliability, (2) high-speed switching response, and (3) direct drive with minute output such as IC, etc. It has come to be used for on / off control of solenoid valves, lamps, heaters, motors, electromagnetic switches, etc. connected to a power supply.

[0005]

In the conventional switching converter as described above, the rush circuit 29 is provided with the relay 28.
However, there is a problem that the allowable number of times of inrush is limited by the on / off life of the relay 28. Further, when the relay 28 is simply replaced with the SSR which is a contactless relay using a semiconductor element, a snubber circuit is required for the SSR. Therefore, the smoothing capacitor 23 does not turn on the SSR due to the leakage current of the snubber circuit. There was a problem of being charged.

The present invention has been made in order to solve the above problems, and it is an object of the present invention to realize a switching converter equipped with an inrush current suppressing circuit that is low in cost and space, while increasing the allowable number of inrush times. To aim.

[0007]

In a switching converter according to the present invention, a rectifying circuit composed of a rectifying element bridge, a rush resistance for limiting a current connected between the rectifying circuit and an AC power supply, and a resistor are provided. A semiconductor switch circuit configured by parallel connection of a series body with a capacitor and a switching element, and an inrush current suppression circuit including
One of the DC bus of the rectifier circuit while connected to one of the DC bus of said switching bridge, the other of the DC bus of the rectifier circuit via the semiconductor switching circuit connected to the other of the DC bus of the switching bridge, the semiconductor at the time of power-on The smoothing capacitor is charged through the switch circuit.

Further, in the switching converter according to the present invention, a rectifying circuit composed of a rectifying element bridge, a rush resistance for limiting current which is connected between the rectifying circuit and an AC power supply, and a resistor and a capacitor in series. A semiconductor switch circuit composed of a parallel connection of the body and a switching element, and an inrush current suppression circuit consisting of both the positive side and the negative side of the DC bus of the rectifier circuit. The smoothing capacitor is charged through a semiconductor switch circuit when it is connected to a bus bar and the power is turned on.

Further, a resistor is connected in parallel with the rectifier circuit.

Furthermore, a voltage limiting element is connected in parallel to the rectifying circuit.

Further, 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 constituted by a bridge structure of a semiconductor switch circuit composed of a series body of a resistor and a capacitor and a switching element connected in parallel, and the semiconductor switch circuit bridge. A rush current suppressing circuit consisting of a rush resistance for limiting current connected between the circuit bridge and an AC power supply, and connecting the DC busbar of the semiconductor switch circuit bridge and the DC busbar of the switching bridge Is.

Further, the voltage limiting element is connected in parallel to the semiconductor switch circuit which constitutes the semiconductor switch circuit bridge.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION 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 of the conventional example shown in FIG.
Reference numeral 1 is a diode as a rectifying element, 2 is a rectifying circuit configured by a bridge with the 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 It is a semiconductor switch circuit configured by parallel connection with. 6
Reference numeral a is an inrush current suppressing circuit composed of the inrush resistor 27, the rectifying circuit 2 and the semiconductor switch circuit 5. Inrush current suppressing circuit 6a of switching converter of this embodiment
Connects one of the DC busbars of the rectifier circuit 2 to the DC busbar of the switching bridge 22 and connects the other DC busbar of the rectifier circuit 2 to the DC busbar of the switching bridge 22 via the semiconductor switch circuit 5 to turn on the power. The smoothing capacitor is sometimes charged via the semiconductor switch circuit.

2 and 3 are diagrams showing the current flow in the switching converter according to the embodiment of the present invention. FIG. 4 is a diagram showing waveforms of voltages 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, V2 is the noise reduction capacitor 2
6, V3 is a voltage across SCR3, V4 is a voltage across diode 1 of rectifier circuit 2, i1, i2,
i3 and i4 are currents.

Next, the operation of the switching converter of the first embodiment will be described with reference to FIGS. SCR
When 3 is off, the smoothing capacitor 23 is not charged,
The main circuit 25 output voltage is not 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 resistance 27 and the rectifier circuit 2. Since the rush resistance 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 source 2
Depending on the polarity of the voltage of 1, the current flowing through the circuit has a path as shown in FIG. 2 or 3. In the case where the polarity of the AC power supply 21 is as shown in FIG. 2, the currents i1 and i2 flow in the illustrated path, and the ends of the noise reduction capacitor 26 are charged to almost E, and the ends of the snubber circuit 4 are also charged to almost E. . 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 in the illustrated paths, the electric charges discharged by the noise reduction capacitor 26 flow into the snubber circuit 4, and both ends of the snubber circuit 4 are discharged. Voltage 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 charging to the snubber circuit 4 does not occur and only the voltage V2 across the noise reduction capacitor 26 is generated. It is charged to almost the voltage E.

In the state shown in FIG. 3, the snubber circuit 4 is charged to approximately 2E, and the voltage across the smoothing capacitor 23 is approximately 0 because the capacitance of the capacitor is large. Is conducted, the voltage V4 across the terminals of the diode 1 of the rectifier circuit 2 is
Corresponds to the voltage V3 between the terminals of the snubber circuit 4. Therefore,
The withstand voltage of SCR3 and diode 1 needs to be 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, 1-5, 21-27 and 30 are the same as in FIG.
The description is omitted. 6b is an inrush current suppressing circuit.
In FIG. 1 described above, the semiconductor switch circuit 5 is shown installed on the positive electrode side of the DC portion of the inrush current suppressing circuit, but FIG. 5 shows that the semiconductor switch circuit 5 is installed on the negative electrode side of the DC portion of the inrush current suppressing circuit. Is.

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

FIG. 7 is a diagram showing a discharge path of the capacitor of the snubber circuit in the switching converter according to the embodiment of the present invention. FIG. 8 is a diagram showing waveforms of voltages at respective parts of the switching converter according to the 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, by adding the resistor 7 between the positive electrode and the negative electrode of the DC part of the inrush current suppressing circuit, a path for discharging the capacitor in the snubber circuit is formed as shown by the current i5 in FIG. The voltage V3 across both ends of the diode is about E at maximum, and the voltage V4 across the diode 1 is about E at maximum.

Embodiment 3. FIG. 9 is a diagram showing a circuit configuration of a switching converter according to an embodiment of the present invention. In the figure, 1-5, 21-27, and 30 are the same as in FIG. 1, and the description thereof is omitted. 6c is an inrush current suppressing 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 at respective parts of the switching converter according to the 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, the voltage limiting element 8 is connected in parallel to the resistor 7 connected between the positive electrode and the negative electrode of the DC portion of the inrush current suppressing circuit in the second embodiment. In this embodiment, the voltage V4 across the diode 1 is equal to or lower than the voltage limited by the voltage limiting element 8. SCR3
The voltage V3 at both ends of the SCR3 is suppressed to the amplitude E of the power supply voltage or less, and the withstand voltage of the SCR3 may be substantially E. Furthermore, the value of the resistance connected between the busbars of the rectifier circuit can be made larger than that in the second embodiment, and heat generation by the resistance can be suppressed.

Fourth Embodiment FIG. 11 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
It is similar to FIG. 1 and its explanation is omitted. 6e is an inrush current suppressing circuit. In this embodiment, the semiconductor switch circuit 5 is installed on both sides of the positive electrode side and the negative electrode side of the DC portion of the inrush current suppressing circuit, and has a configuration in which FIG. 1 and FIG. 5 in the above-described first embodiment are combined. is there.

12 and 13 are diagrams showing current flows in the switching converter according to the embodiment of the present invention. FIG. 14 is a diagram showing waveforms of voltages at respective 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, V2 is the noise reduction capacitor 2
6, V3 is a voltage across SCR3, V4 is a voltage across diode 1 of rectifier circuit 2, and i6 and i7 are currents.

Next, a fourth embodiment will be described with reference to FIGS.
The operation of the switching converter will be described. The AC power supply 21 is connected to the rectifier circuit 2 through the rush resistance 27 to become DC, and the semiconductor switching circuit 5 turns on / off the current. When both the SCR3 of the semiconductor switch circuit 5 installed on the positive side of the DC part of the inrush current suppression circuit and the SCR3 of the semiconductor switch circuit 5 installed on the negative side of the DC part of the inrush current suppression circuit are off A current flows as shown in FIGS. 12 and 13 depending on the polarity of the voltage of the AC power supply 21.

Voltage V across diode 1 of rectifier circuit 2
Since the maximum value of 4 is twice the amplitude E of the power supply voltage, the withstand voltage of the diode 1 is required to be twice E. However, since the voltage V2 across the noise reduction capacitor 26 is divided by the circuit constant, it can be suppressed to a low level, and the voltage V3 across the SCR3 becomes almost E. Therefore, the withstand voltage of the SCR 3 may be about E.

Embodiment 5. FIG. 15 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
It is similar to FIG. 1 and its explanation is omitted. 6f is an inrush current suppressing circuit. In this embodiment, the semiconductor switch circuit 5 is installed on both sides of the positive electrode side and the negative electrode side of the inrush current suppressing circuit DC part, and in the fourth embodiment, between the positive electrode and the negative electrode of the inrush current suppressing circuit DC part, A resistor 7 for discharging the capacitor in the snubber circuit is added.

FIG. 16 is a diagram showing the discharge path of the capacitor of the snubber circuit in the switching converter according to the embodiment of the present invention. FIG. 17 shows an SCR3 in the switching converter according to the embodiment of the present invention.
Voltage V3 across diode 1 and voltage V4 across diode 1
It is a figure which shows the voltage waveform of. 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 has a resistor 7 for discharging the capacitor in the snubber circuit, which is added between the positive electrode and the negative electrode of the DC portion, to form a discharge path like the current i8 in FIG.
Since the voltage across both ends of the SCR 3 is prevented from increasing, the withstand voltage of the SCR 3 and the diode 1 may be about E.

Sixth Embodiment FIG. 18 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
It is similar to FIG. 1 and its explanation is omitted. 6g is an inrush current suppressing circuit, 8 is a voltage limiting element connected in parallel with the resistor 7, and V5 is a voltage of the rectifying circuit 2. FIG. 19 is a diagram showing voltage waveforms of the rectifier circuit 2 of the switching converter according to the embodiment of the present invention.

In this embodiment, the voltage limiting element 8 is connected in parallel to the resistor 7 for discharging the capacitor in the snubber circuit, which is installed between the positive electrode and the negative electrode of the DC portion of the inrush current suppressing circuit in the fifth embodiment. And the above-described fifth embodiment.
It is possible to increase the value of the resistor 7 and suppress heat generation in the resistor. Further, the voltage limiting element 8 can limit the ripple in the DC portion of the inrush current suppressing circuit to be equal to or lower than the limiting voltage.

Embodiment 7. FIG. 20 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
It is similar to FIG. 1 and its explanation is omitted. 6h is an inrush current suppressing circuit, 9 is a capacitor, and V5 is a voltage of the rectifying circuit 2. FIG. 21 is a diagram showing voltage waveforms of the rectifier circuit 2 of the switching converter according to the embodiment of the present invention. In the figure, (a) is the voltage waveform in the case of the above-mentioned fifth embodiment, and (b) is the resistor 7 for discharging the capacitor in the snubber circuit installed between the positive electrode and the negative electrode of the DC portion of the inrush current suppressing circuit.
2 is a voltage waveform in the case of this embodiment in which a capacitor 9 is connected in parallel to the.

In this embodiment, the capacitor 9 is connected in parallel with the resistor 7 for discharging the capacitor in the snubber circuit, which is installed between the positive electrode and the negative electrode of the DC portion of the inrush current suppressing circuit in the 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. 22 is a diagram showing a circuit configuration of a switching converter according to one embodiment of the present invention. In the figure, 21 to 27 and 30 are the same as those of the conventional example shown in FIG. Reference numeral 3 is an SCR as a switching element, 4 is a snubber circuit configured as a series body of a resistor and a capacitor, and 5 is a semiconductor switch circuit including an 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 resistance 27 and a thyristor bridge 10a.
It is an inrush current suppression circuit configured by.

23 and 24 are diagrams showing current flows in the switching converter according to the embodiment of the present invention. FIG. 25 is a diagram showing voltage waveforms at various parts of 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 waveform of the AC power supply voltage 21, and V6 and V7 are the waveforms of the voltages across the SCR.

Next, the operation of the switching converter of this embodiment will be described with reference to FIGS.
The AC power source 21 is connected to the thyristor bridge 10a through the inrush resistance 27, and when the four semiconductor switch circuits 5 are turned on, the thyristor bridge 10a rectifies the current to generate a direct current, and a current flows. Further, 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 indicates the direction of current flow.

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

Ninth Embodiment FIG. 26 is a diagram showing a circuit configuration of a switching converter according to an embodiment of the present invention. In the figure, 3 to 5, 21 to 27, and 30 are the same as those in the above-described eighth embodiment shown in FIG. 22, and the description thereof will be omitted. Reference numeral 12 is a voltage limiting element connected in parallel to the semiconductor switch circuit 5, 10b is a thyristor bridge composed of four semiconductor switching circuits 5 and four voltage limiting elements 12 connected in parallel to the semiconductor switching circuit 5, 11
Reference numeral b is an inrush current suppressing circuit composed of 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. It is possible to prevent the SCR 3 from being damaged even when the ground fault occurs.

[0042]

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

In the switching converter according to the present invention, a rectifying circuit composed of a rectifying element bridge, a rush resistance for limiting current that is connected between the rectifying circuit and an AC power supply, and a series body of a resistor and a capacitor. A semiconductor switch circuit configured by parallel connection with a switching element, and an inrush current suppressing circuit consisting of, one of the DC bus of the rectifier circuit is connected to one DC bus of the switching bridge, and the DC bus of the rectifier circuit The other of the above is connected to the other 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. Switch of semiconductor switch circuit
The smoothing capacitor is charged when the teaching element is off.
It is possible to realize a switching converter which is provided with a rush current suppressing circuit which is low in cost and space saving.

Further, in the switching converter according to the present invention, a rectifying circuit composed of a rectifying element bridge, a rush resistance for current limitation connected between the rectifying circuit and an AC power source, and a series connection of a resistor and a capacitor are provided. A semiconductor switch circuit composed of a parallel connection of the body and a switching element, and an inrush current suppression circuit consisting of both the positive side and the negative side of the DC bus of the rectifier circuit. The smoothing capacitor is charged via the semiconductor switch circuit when the power is turned on by connecting to the bus bar, increasing the allowable number of rushes.
And the switching element of the semiconductor switch circuit is turned on.
Do not charge the smoothing capacitor when
Equipped with a low-cost, space-saving inrush current suppression circuit
If we can realize such a switching converter,
Not only that, but the voltage across the semiconductor switch circuit can be suppressed below the maximum voltage of the AC power supply.

Further, since the resistors are connected in parallel to the rectifier circuit, the voltage across the semiconductor switch circuit and the voltage across the rectifying element of the rectifier circuit can be suppressed to the maximum voltage of the AC power source or less.

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

Further, since the capacitor is connected in parallel to the rectifier circuit, it is possible to suppress the peak of the voltage between the busbars of the rectifier circuit. Further, the value of the resistor connected between the busbars of the rectifier circuit can be increased, and heat generation in the resistor can be suppressed.

Further, in the switching converter according to the present invention, a semiconductor switch circuit bridge constituted by a bridge structure of a semiconductor switch circuit configured by connecting a series body of a resistor and a capacitor and a switching element in parallel, and the semiconductor switch circuit bridge. Since a rush current suppressing circuit consisting of a rush resistance for limiting the current connected between the circuit bridge and the AC power source is provided, the DC bus of the semiconductor switch circuit bridge and the DC bus of the switching bridge are connected. , Switching element of semiconductor switch circuit
The smoothing capacitor is charged when the child is off
Without, it is possible to suppress the voltage across the semiconductor switching circuit below the maximum voltage of the AC power source. Further, since it is not necessary to attach a discharging resistor, it is possible to reduce power loss and to reduce the number of parts, so that it is possible to realize a rush current suppressing circuit at low cost and space.

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

[Brief description of 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 the switching converter according to the embodiment of the present invention.

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

FIG. 4 is a diagram showing waveforms of voltages at various 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 an embodiment of the present invention.

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

FIG. 8 is a diagram showing voltage waveforms at various 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 an embodiment of the present invention.

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

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

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

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

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

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

FIG. 25 is a diagram showing voltage waveforms at various parts of the switching converter according to the 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 circuits, 6a, 6
b, 6c, 6e, 6f, 6g, 6h Inrush current suppressing circuit, 7 resistance, 8 voltage limiting element, 9 capacitor, 10a, 10b thyristor bridge, 11
a, 11b Inrush current suppressing 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 resistance, 28 relay, 29 inrush current suppression circuit,
30 contactors, E amplitude of power supply voltage 21, V1
AC power supply 21 voltage, V2 noise reduction capacitor 26
Voltage across V3, V3 voltage across SCR3, V4
Voltage across diode 1, voltage across V5 rectifier circuit 2, waveforms across voltage across V6, V7SCR, i1, i
2, i3, i4, i5, i6, i7, i8 Current.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02M 7/155 H02M 7/219

Claims (7)

(57) [Claims] 1. A switching bridge which inputs an AC power source, converts it into a DC voltage and outputs it, and a smoothing capacitor which smoothes the DC voltage output by this switching bridge,
One end is connected to the output side of the switching bridge
Together with a noise reduction capacitor whose other end is grounded, and a rush current suppressing circuit that is connected to the input side of the switching bridge and limits the current during rush, in a switching converter, the rush current suppressing circuit, Semiconductor switch composed of a rectifier circuit consisting of a rectifier bridge, an inrush resistor for current limiting connected between this rectifier circuit and an AC power supply, and a parallel body of a series body of a resistor and a capacitor and a switching element. A circuit, wherein one of the DC busbars of the rectifier circuit is connected to one of the DC busbars of the switching bridge, and the other of the DC busbars of the rectifier circuit is connected to the other of the switching bridges via the semiconductor switch circuit . Connect to a DC bus and charge the smoothing capacitor through the semiconductor switch circuit when power is turned on. Switching converter characterized in that so as to. 2. A switching bridge which inputs an AC power source, converts it into a DC voltage and outputs the DC voltage, and a smoothing capacitor which smoothes the DC voltage output by the switching bridge.
One end is connected to the output side of the switching bridge
Together with a noise reduction capacitor whose other end is grounded, and a rush current suppressing circuit that is connected to the input side of the switching bridge and limits the current during rush, in a switching converter, the rush current suppressing circuit, Semiconductor switch composed of a rectifier circuit consisting of a rectifier bridge, an inrush resistor for current limiting connected between this rectifier circuit and an AC power supply, and a parallel body of a series body of a resistor and a capacitor and a switching element. A rectifier circuit, 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 the smoothing is performed via the semiconductor switch circuit when power is turned on. A switching converter characterized in that a 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 in parallel to the rectifier circuit. 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 into a DC voltage and outputting it, and a smoothing capacitor for smoothing the DC voltage output by this switching bridge,
One end is connected to the output side of the switching bridge
Together with a noise reduction capacitor whose other end is grounded, and a rush current suppressing circuit that is connected to the input side of the switching bridge and limits the current during rush, in a switching converter, the rush current suppressing circuit, A semiconductor switch circuit bridge configured by a bridge structure of a semiconductor switch circuit configured by connecting a series body of a resistor and a capacitor and a switching element in parallel, and a current limit connected between the semiconductor switch circuit bridge and an AC power supply. And a rush resistance for use in the switching circuit, wherein the DC bus of the semiconductor switch circuit bridge and the DC bus of the switching bridge are connected to each other. 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.