JP2001293564A - Arc welding machine or plasma cutter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving circuit by which a reverse bias can be applied with a simple constitution to a power semiconductor by a pulse transformer with no intermediate terminal in a secondary winding. SOLUTION: This is a power semiconductor driving circuit equipped with the pulse transformer with no intermediate terminal in the secondary winding, a capacitor for the reverse bias and a Zener diode connected to the capacitor in parallel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arc welding machine and a plasma cutting machine equipped with a power semiconductor for performing output control and a drive circuit.

[0002]

2. Description of the Related Art Generally, an arc welding machine or a plasma cutting machine is provided with a power semiconductor for controlling output. In particular, in recent years, in order to reduce the size of equipment, an IGBT or a conventional bipolar transistor has been used instead of a conventional bipolar transistor. MOS FET
Inverter control methods using power semiconductors for high-speed switching such as those described above have become mainstream.

[0003] In a welding machine or a cutting machine using these IGBTs or MOS FETs for output control, IGBTs or MOS FETs are used.
Since the FET is a voltage-driven switching element, the average power of the gate drive can be small. Therefore, a drive circuit using a pulse transformer is often provided.

While a drive circuit for a bipolar transistor requires an independent power supply circuit for each drive circuit, a pulse transformer drive circuit uses a pulse transformer for signal transmission and power transmission for gate drive. Since they also serve, an independent power supply is not required, and the circuit can be simplified.

[0005] A drive circuit of a pulse transformer type has been widely put into practical use, and a drive circuit having a reverse bias voltage circuit at the time of a drive OFF signal has been proposed.

A conventional welding machine equipped with a pulse transformer type driving circuit will be described below with reference to FIG.

[0007] The welding machine and the cutting machine are usually several kHz to 10 kHz.
IGBT and MOS at inverter frequency of about 0kHz
By controlling the conduction width of a power semiconductor such as an FET, constant current characteristics and constant voltage characteristics are obtained. FIG. 2 shows a configuration in which the drive circuit portion of the power semiconductor is extracted.

In FIG. 2, reference numeral 1 denotes a drive signal generation circuit;
Is a switching element for driving a pulse transformer, 3 is a pulse transformer having an intermediate terminal for reverse bias on the secondary side,
Is a rectifying element for applying a forward bias voltage for gate drive to the power semiconductor, 5 is a gate resistor, 6 is a switching element for applying a reverse bias voltage to the power semiconductor, 7 is a capacitor serving as a reverse bias voltage source, and 8 is a reverse A rectifying element for charging a bias voltage, 9 is a limiting resistor for charging a reverse bias voltage, and 10 and 11 are switching elements 6
Constitutes a pulse transformer back electromotive force regenerative circuit for conducting the drive signal during the drive signal OFF period, 10 is a rectifying element, 11 is a resistor, and 12 is a power semiconductor for controlling the output of a welding machine or a plasma cutting machine. It is.

The operation of the power semiconductor drive circuit configured as described above will be described below.

The pulse transformer driving switching element 2 applies a drive voltage to the primary winding of the pulse transformer 3 according to the ON signal output from the drive signal generation circuit 1. During the drive signal ON period, a forward bias voltage supplied to the power semiconductor is induced in the secondary winding of the pulse transformer 3, and this forward bias voltage is applied to the gate resistor 5 and the rectifier 4.
The voltage is applied to the gate of the power semiconductor 12 through the capacitor 7 and the power semiconductor 12 is turned on. At this time, the capacitor 7 is charged with a reverse bias voltage from the reverse bias charging intermediate terminal of the pulse transformer secondary winding through the limiting resistor 9 and the rectifying element 8.

When an OFF signal is output from the drive signal generating circuit 1, the switching element 2 is turned off, the voltage applied to the primary winding of the pulse transformer is released, and a counter electromotive voltage is induced in the secondary winding of the pulse transformer. . This back electromotive voltage is the resistance 1
1. Regeneration is performed through the rectifier element 10. At this time, the switching element 6 conducts and supplies the voltage charged in the capacitor 7 to the gate of the power semiconductor 12 as a reverse bias voltage. As a result, the power semiconductor 12 can discharge the charge stored in the gate more rapidly, and can increase the OFF speed.

[0012]

However, in the above-mentioned conventional drive circuit, it is necessary to use a pulse transformer having a secondary intermediate terminal for reverse bias, and the pulse transformer must be a specially designed product. And the circuit configuration becomes complicated.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems. A drive circuit having a reverse bias circuit is constituted by using a general pulse transformer having no intermediate terminal on a secondary winding. Provided is a driver circuit which can realize simplification of a circuit.

[0014]

According to the present invention, there is provided an arc welding machine, comprising: a switching element connected to a primary winding of a pulse transformer for driving the pulse transformer; A rectifying element for applying a forward bias voltage to the gate of the power semiconductor from the secondary side of the transformer; a capacitor connected in series to the pulse transformer secondary side circuit and charged with a reverse bias voltage during a forward bias period; Power semiconductor drive circuit provided with a Zener diode connected in parallel with a capacitor to limit the charging voltage of the power semiconductor, and a reverse bias switching element for applying the charging voltage of the capacitor to the power semiconductor as a reverse bias voltage during a gate OFF period It is characterized by having.

According to a second aspect of the present invention, there is provided a plasma cutting machine comprising the power semiconductor drive circuit according to the first aspect.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the first and second aspects of the present invention, a power semiconductor drive circuit having the same configuration is mounted on an arc welding machine in the first aspect. In this example, the present invention is mounted on a plasma cutting machine, and has the same function. Therefore, the embodiment of the present invention will be described with reference to an arc welding machine.

Hereinafter, an arc welding machine according to an embodiment of the present invention will be specifically described with reference to the drawings.

FIG. 1 is a circuit diagram showing a power semiconductor drive circuit configuration of an arc welding machine according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a drive signal generation circuit;
Is a switching element for driving a pulse transformer, 13 is a pulse transformer having no intermediate terminal in the secondary winding, 4 is a rectifying element for applying a forward bias voltage for gate driving to the power semiconductor, 5 is a gate resistor, and 6 is reverse to the power semiconductor. A switching element for applying a bias voltage, 7 is a capacitor serving as a reverse bias voltage source, 14 is a Zener diode for determining a reverse bias voltage value charged in the capacitor 7, and 10 and 11 are switches for switching the switching element 6 during the drive signal OFF period. A pulse transformer back electromotive force regenerative circuit for conducting is constituted, 10 is a rectifying element, 11 is a resistor, and 12 is a power semiconductor for controlling the output of a welding machine or a plasma cutting machine.

The operation of the power semiconductor drive circuit configured as described above will be described below.

The pulse transformer driving switching element 2 applies a drive voltage to the primary winding of the pulse transformer 3 according to the ON signal output from the drive signal generation circuit 1. During the drive signal ON period, a forward bias voltage supplied to the power semiconductor is induced in the secondary winding of the pulse transformer 3, and this forward bias voltage is applied to the gate resistor 5 and the rectifier 4.
The voltage is applied to the gate of the power semiconductor 12 through the capacitor 7 and the power semiconductor 12 is turned on. Also, at this time, the capacitor 7
Is charged with a reverse bias voltage, and the charged voltage is clamped to a voltage level determined by the Zener diode 14.

When an OFF signal is output from the drive signal generating circuit 1, the switching element 2 is turned off, the voltage applied to the primary winding of the pulse transformer is released, and a counter electromotive voltage is induced in the secondary winding of the pulse transformer. . This back electromotive voltage is the resistance 1
1. Regeneration is performed through the rectifier element 10. At this time, the switching element 6 conducts and supplies the voltage charged in the capacitor 7 to the gate of the power semiconductor 12 as a reverse bias voltage. As a result, the power semiconductor 12 can discharge the charge stored in the gate more rapidly, and can increase the OFF speed.

That is, if this configuration is used, a power semiconductor drive circuit having a reverse bias circuit is constructed using a general pulse transformer having no intermediate terminal in the secondary winding in a welding machine or a cutting machine. At the same time, the circuit can be simplified.

By using the power semiconductor drive circuit having the above-described reverse bias circuit, the same operation and effect can be obtained in the plasma cutting machine.

[0025]

As described above, according to the present invention, in an arc welding machine, a power semiconductor drive circuit having a reverse bias circuit using a general pulse transformer having no intermediate terminal in the secondary winding is used. The configuration and simplification of the circuit can be realized.

In the plasma cutting machine, a power semiconductor drive circuit having a reverse bias circuit is formed by using a general pulse transformer having no intermediate terminal on the secondary winding, and the circuit is simplified. can do.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a power semiconductor drive circuit for an arc welding machine according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration of a conventional power semiconductor drive circuit for a welding machine.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 drive signal generating circuit 2 pulse transformer driving switching element 3 pulse transformer having intermediate terminal for reverse bias on secondary side 4 rectifier 5 gate resistor 6 reverse bias switching element 7 capacitor serving as reverse bias voltage source 8 rectification Element 9 Limiting resistance 10 Rectifier element 11 Resistance 12 Power semiconductor 13 Pulse transformer without secondary winding intermediate terminal 14 Zener diode for determining reverse bias voltage value

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor ▲ Hama ▼ Koji Moto 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 4E001 AA01 BA04 DE04 4E082 DA01 EA20 EE08 EF02 EF07 5H740 BA11 BC01 BC02 HH07 JA01 JB02 KK03 5H790 BA03 EA01 EA02 EA15

Claims (2)

[Claims] A switching element connected to a primary winding of a pulse transformer for driving the pulse transformer; a rectifying element for applying a forward bias voltage to a gate of a power semiconductor from a secondary side of the pulse transformer; A capacitor connected in series to the secondary circuit and charged with a reverse bias voltage during a forward bias period; a zener diode connected in parallel with the capacitor to limit the charging voltage of the capacitor; An arc welding machine having a power semiconductor drive circuit provided with a reverse bias switching element for applying a reverse bias voltage to a semiconductor during a gate OFF period. A switching element connected to a primary winding of the pulse transformer for driving the pulse transformer; a rectifying element for applying a forward bias voltage from a secondary side of the pulse transformer to a gate of a power semiconductor; A capacitor connected in series to the secondary circuit and charged with a reverse bias voltage during a forward bias period; a zener diode connected in parallel with the capacitor to limit the charging voltage of the capacitor; A plasma cutting machine having a power semiconductor drive circuit provided with a reverse bias switching element for applying a reverse bias voltage to a semiconductor during a gate OFF period.