JP2001320885A - Voltage step-up circuit and pulse generating circuit using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pulse generating circuit which can obtain an energy transmission efficiency higher than a conventional one. SOLUTION: A voltage step-up circuit which is composed of (n) pulse transformers whose winding ratios are low, whose primary windings are connected in parallel to each other, and whose secondary windings are connected in series to each other, is provided. On the primary side of the voltage step-up circuit, an SI thyristor for turning on/off is connected to a charging power supply 1, and series connection circuits composed of the primary windings of the respective pulse transformers and charging capacitors 2 are connected in parallel to the SI thyristor. A magnetic pulse contraction unit B which contracts a pulse obtained from the secondary windings of the respective pulse transformers which are connected in series to each other is connected to the secondary side of the voltage step-up circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a voltage boosting circuit and a pulse generating circuit using the same.

[0002]

2. Description of the Related Art A conventional pulse discharge circuit using a power semiconductor switch element will be described with reference to FIG. The conventional pulse discharge circuit includes a pulse generation unit D, a magnetic pulse compression unit E, and an electrode unit F. The circuit including the pulse generator D and the magnetic pulse compressor E is called a pulse generator.

The pulse generator D has one end connected to a connection point between the resistor 14 and the power semiconductor switch element 13 connected in series to the charging power source 10 and a connection point between the resistor 14 and the anode of the power semiconductor switch element 13. Magnetic assist 11
A charging capacitor 12 connected to the other end of the magnetic assist 11, and a pulse transformer PT having primary windings connected to both ends of the power semiconductor switch element 13 via the magnetic assist 11 and the charging capacitor 12. Have been.

The magnetic pulse compression unit E includes a pulse transformer P
This is for compressing the pulse obtained from the secondary winding of T more steeply. The magnetic pulse compression unit E includes n-stage capacitors 15-1 to 15-n connected in parallel with each other.
And n magnetic switches 16-1 connected between each stage
.About.16-n and n for resetting each magnetic switch.
And reset circuits 17-1 to 17-n. The electrode portion F includes a peaking capacitor 18 and an electrode (including preionization) 19.

The operation of this pulse discharge circuit is as follows. Charging power supply 10 to charging capacitor 12
A pulse is generated by applying a trigger signal to the power semiconductor switch element 13 to turn on the energy stored in the power semiconductor switch element 13. The generated pulse is transferred to a pulse transformer P
The pressure is raised according to the turns ratio of T (normally about 1:10), and the process proceeds to the magnetic pulse compression unit E. In the magnetic pulse compression unit E, the boosted pulse is supplied to the n-stage capacitors 15-1 to 15-1.
The compression is performed to a predetermined pulse width by the 5-n and n magnetic switches 16-1 to 16-n. The compressed pulse is transferred to the peaking capacitor 18 and discharged at the electrode 19.

Here, the magnetic assist will be described.
The magnetic assist is manufactured by winding a winding around a core. The manufacturing method and operation are the same as those of the magnetic switch, but the insertion purpose and the design method are different.

In the case of magnetic assist, the purpose of insertion is to reduce the loss of the semiconductor switching element. That is, as shown in FIG. 4, when the semiconductor switch element is turned on, the current is caused to flow after the voltage is sufficiently reduced, thereby performing an operation of reducing V × I (loss). In FIG. 4, when there is no magnetic assist, the current flows as indicated by the broken line, and the loss (V × I) at this time is the area of the portion where the voltage and the current overlap. When switching high power, the values of voltage and current are on the order of kV and kA. Therefore, even if the switching time is short, the value of the loss (V × I) cannot be ignored. The time ΔT is designed by the following equation.

ΔT = (ΔB · N · S) / V where ΔB is the amount of change in magnetic flux density, N is the number of turns of the winding, S is the cross-sectional area of the core, and V is the voltage applied to the magnetic assist.
At the time of designing, the time ΔT is designed to be a value larger than the switching time of the semiconductor switching element. In any case, when the magnetic assist is inserted, the current flowing due to the hysteresis characteristic of the magnetic body can be delayed, and the flowing current is reduced as shown in FIG.
At the point indicated by the solid line. As a result, the loss (V ×
I) can be made sufficiently small.

Next, the magnetic switch and its reset circuit will be described. The reset circuit is a circuit for flowing a current in the direction opposite to the direction in which the saturation current flows in order to increase the amount of change in the magnetic flux density of the magnetic material in the magnetic switch as much as possible.

FIG. 5 shows the hysteresis characteristic of the magnetic material. The time .DELTA.t until the magnetic switch is turned on is represented by the following equation: .DELTA.t = (. DELTA.B.N.S) / V. In this case, the time Δt is proportional to the variation ΔB of the magnetic flux density of the core of the magnetic switch. On the other hand, the magnetic field H is represented by the following equation.

H = (NI) / L where I is the current and L is the average magnetic path length of the magnetic material. From this equation, the magnetic field H is proportional to the current I.

In view of the above, it is necessary to increase ΔB in order to obtain a sufficient switch waiting time with a smaller magnetic switch. For this purpose, a reset circuit (constant current source) is connected to reset the core in advance.

[0013]

In the above-described pulse discharge circuit, the pulse width generated by the pulse generator D is determined by the current increase rate di / dt of the power semiconductor switch element 13 and the pulse width of the magnetic assist 11. Saturation inductance, charging capacitor 12, pulse transformer PT
Is determined by the resonance frequency due to the primary side leakage inductance. For this reason, when high output energy is required, the amount of charge charged to the charging capacitor 12 increases, and the pulse width generated from the pulse generator D increases. This is the magnetic pulse compression unit E
However, there is a drawback that the energy loss is increased due to the increase in the compression ratio and the magnetic pulse compression unit E (including the reset circuit) is complicated (multi-stage).

If the voltage is increased at a high turns ratio (about 1:10) in the pulse transformer PT, the coupling between the primary side and the secondary side of the pulse transformer PT becomes less dense,
There is a disadvantage that energy transmission efficiency is reduced due to an increase in leakage inductance.

An object of the present invention is to provide a pulse generation circuit that can obtain higher energy transmission efficiency than in the prior art.

Another object of the present invention is to provide a voltage boosting circuit suitable for the above-mentioned pulse generating circuit.

[0017]

According to the present invention, a plurality of pulse transformers having a low turn ratio are used, the primary windings of each pulse transformer are connected in parallel with each other, and the secondary windings are connected in series. There is provided a voltage boosting circuit characterized by being connected.

According to the present invention, a plurality of pulse transformers having a low turn ratio are used, and the primary windings of the pulse transformers are connected in parallel with each other, and the secondary windings are connected in series. On the primary side of the voltage boosting circuit, a switching power semiconductor switch element is connected to a charging power source, and the power semiconductor switch element is connected to a primary winding of each pulse transformer by charging. A series connection circuit with a capacitor is connected in parallel, and on the secondary side of the voltage booster circuit, a magnetic pulse compression unit for compressing a pulse obtained from a secondary winding of each pulse transformer connected in series is provided. A pulse generating circuit characterized by being connected is obtained.

It is preferable that an SI thyristor is used for the power semiconductor switch element.

In each of the pulse transformers, it is preferable that the primary winding and the secondary winding are wrapped.

In each of the pulse transformers, the primary winding and the secondary winding may be formed by a stranded wire.

The turn ratio of each pulse transformer is 1:
It is preferable to set it to 1-1: 3.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a pulse generation circuit according to the present invention is applied to a pulse discharge circuit will be described with reference to FIG. The configuration of the present pulse discharge circuit is obtained by adding an electrode section F to a pulse generation circuit including a pulse generation section A and a magnetic pulse compression section B. Pulse generator A
Connects a series circuit of a resistor 5 and an SI thyristor 4 to a charging power supply 1, and has n primary windings of n pulse transformers PT1 to PTn and a magnetic assist 3 at both ends of the SI thyristor 4.
-1 to 3-n and charging capacitors 2-1 to 2-
n in series. That is,
The primary windings of each of the n pulse transformers acting as voltage boosting circuits are connected in parallel to each other, and the secondary windings are connected in series.

The magnetic pulse compression unit B here comprises a one-stage capacitor 6, a magnetic switch 7, and a reset circuit 8 for resetting the magnetic switch 7.
The functions of the capacitor 6, the magnetic switch 7, and the reset circuit 8 are the same as those of the conventional one shown in FIG. 3, and the number of stages of the magnetic pulse compression unit B is appropriately set according to the pulse width compression ratio. The electrode portion F includes a peaking capacitor 18 and an electrode (including preliminary ionization) 19.

The operation of this circuit is similar to that of the conventional example described with reference to FIG. 3, and a pulse is generated by the pulse generator A. The generated pulse is formed by connecting the secondary windings of n pulse transformers in series. It is boosted. The boosted pulse is compressed to a predetermined pulse width by the magnetic pulse compression unit B, and energy is transmitted to the electrode unit C. This circuit has the following features.

1) An SI thyristor 4 having a large current and a large current increase rate is used as a power semiconductor switch element.

2) By dividing the pulse generator A into n parts and connecting their primaries in parallel, the resonance frequency due to the saturation inductance of the magnetic assist 3, the charging capacitor 2, and the primary leakage inductance of the pulse transformer PT is increased. , The generated pulse width is shortened.

3) As a boosting method using the pulse transformer PT, as shown in FIG. 1, a low turns ratio of 1: 1 to 1: 3
The boosting is performed by connecting the secondary sides of the n pulse transformers PT1 to PTn in series.

4) The pulse transformer PT is manufactured as shown in FIG.
(A) As shown in FIG.
0 or insulated wires are wound on top of each other, or
As shown in (b), the insulated wire is wound in a more linear shape around the high magnetic permeability core 20 to further improve the coupling coefficient.

The present invention is suitable for a pulse discharge circuit for a laser device, and is particularly applicable to a circuit requiring a high-voltage pulse, high output energy, and high repetition operation, and can be applied to all gas lasers.

[0031]

The advantages of the above-described features over the conventional pulse generation circuit are as follows.

The pulse width generated in the pulse generator A can be made shorter than that of the conventional type. That is, the input pulse width to the magnetic pulse compression unit B is short, and the compression ratio can be reduced. Thereby, the energy transmission efficiency in the magnetic pulse compression unit B is increased, and the magnetic pulse compression unit B
Structure can be simplified.

The SI thyristor 4 can flow a large current and has a current increase rate of one digit or more as compared with a power semiconductor switch element such as a GTO, so that one element can switch a large energy. . Therefore,
There is no need to synchronize the trigger circuit required when the switching elements are connected in series, and the trigger circuit can be simplified.

The turn ratio of the pulse transformer PT is 1: 1 to 1
By making the ratio as low as 1: 3, the leakage inductance can be reduced. Also, by connecting the primary side of the pulse transformer PT in parallel and connecting the secondary side in series,
It is possible to obtain a boosting ratio similar to or higher than the conventional one.

Since the number of turns wound around the core can be reduced by reducing the turns ratio, a winding method as shown in FIGS. 2A and 2B can be employed. Therefore, the coupling coefficient can be further increased, and the energy transmission efficiency at the pulse transformer can be increased.

[Brief description of the drawings]

FIG. 1 is a circuit diagram in which the present invention is applied to a pulse discharge circuit.

FIG. 2 is a diagram for explaining an example of a winding method applied to the pulse transformer of FIG.

FIG. 3 is a diagram showing a conventional pulse discharge circuit.

FIG. 4 is a diagram for explaining a function of magnetic assist.

FIG. 5 is a diagram for explaining functions of a magnetic switch and a reset circuit thereof.

[Explanation of symbols]

2-1 2-2, 2-n, 11 Charging capacitor 3-1, 3-2, 3-n, 12 Magnetic assist 4 SI thyristor PT, PT1, PT2, PTn Pulse transformer 7, 16-1, 16 -N magnetic switch 19 electrodes

Claims (9)

[Claims] 1. A voltage booster circuit comprising a plurality of pulse transformers having a low turn ratio, wherein primary windings of each pulse transformer are connected in parallel with each other, and secondary windings are connected in series. . 2. The voltage boosting circuit according to claim 1, wherein
A voltage boosting circuit, wherein a primary winding and a secondary winding of each pulse transformer are superposed. 3. The voltage boosting circuit according to claim 1, wherein
A voltage boosting circuit, wherein a primary winding and a secondary winding of each pulse transformer are stranded. 4. The voltage boosting circuit according to claim 2, wherein the turns ratio of each pulse transformer is 1: 1 to 1: 3.
A voltage boosting circuit characterized by: 5. A voltage booster circuit comprising a plurality of pulse transformers having a low turn ratio, wherein primary windings of the respective pulse transformers are connected in parallel with each other, and secondary windings are connected in series, On the primary side of the voltage boosting circuit, a power semiconductor switching element for switching is connected to a charging power source, and a primary winding of each pulse transformer and a charging capacitor are connected in series to the power semiconductor switching element. Circuits are connected in parallel, and a magnetic pulse compression unit for compressing a pulse obtained from a secondary winding of each pulse transformer connected in series is connected to a secondary side of the voltage booster circuit. Pulse generating circuit. 6. The pulse generation circuit according to claim 5, wherein an SI thyristor is used as said power semiconductor switch element. 7. The pulse generating circuit according to claim 5, wherein each of the pulse transformers has a primary winding and a secondary winding which are overlapped. 8. The pulse generation circuit according to claim 5, wherein each of the pulse transformers has a primary winding and a secondary winding which are wound with a single wire. 9. The pulse generating circuit according to claim 7, wherein the turns ratio of each pulse transformer is 1: 1 to 1:
3. A pulse generating circuit, wherein