JP4006920B2 - Arc welding machine or plasma cutting machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an arc welding machine and a plasma cutting machine equipped with a power semiconductor for controlling output and a drive circuit.
[0002]
[Prior art]
In general, arc welding machines and plasma cutting machines are equipped with power semiconductors for output control. Particularly in recent years, in order to reduce the size of equipment, high-speed devices such as IGBTs and MOS FETs are substituted for conventional bipolar transistors. Inverter control systems using power semiconductors for switching have become mainstream.
[0003]
In these welding machines and cutting machines that use IGBTs or MOS FETs for output control, since the IGBTs or MOS FETs are voltage-driven switching elements, the average power for gate drive may be small, so a drive circuit using a pulse transformer is required. Often provided.
[0004]
The drive circuit for the bipolar transistor requires an independent power supply circuit for each drive circuit, whereas in the pulse transformer type drive circuit, the pulse transformer doubles as the signal transmission and power transmission for the gate drive. Therefore, an independent power source is unnecessary and the circuit can be simplified.
[0005]
A pulse transformer type drive circuit has been widely put into practical use, and a drive circuit including a reverse bias voltage circuit at the time of a drive OFF signal has been proposed.
[0006]
Hereinafter, a welding machine equipped with a conventional pulse transformer system drive circuit will be described with reference to FIG.
[0007]
A welding machine and a cutting machine usually obtain constant current characteristics and constant voltage characteristics by controlling the conduction width of power semiconductors such as IGBTs and MOS FETs at an inverter frequency of about several kHz to 100 kHz. FIG. 2 shows a configuration obtained by extracting the drive circuit portion of the power semiconductor.
[0008]
In FIG. 2, 1 is a drive signal generation circuit, 2 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, and 4 is a forward bias voltage for driving a gate to a power semiconductor. Rectifier element 5 is a gate resistor, 6 is a switching element for applying a reverse bias voltage to the power semiconductor, 7 is a capacitor as a reverse bias voltage source, 8 is a rectifier element for charging the capacitor 7 with a reverse bias voltage, and 9 is Reverse bias voltage charging limiting resistors 10 and 11 constitute a pulse transformer back electromotive voltage regeneration circuit for conducting the switching element 6 during the drive signal OFF period. 10 is a rectifier element, 11 is a resistor, and 12 is a resistor. It is a power semiconductor for controlling the output of welding machines and plasma cutting machines.
[0009]
The operation of the power semiconductor drive circuit configured as described above will be described below.
[0010]
In response to the ON signal output from the drive signal generation circuit 1, the pulse transformer driving switching element 2 applies a drive voltage to the primary winding of the pulse transformer 3. 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 passes through the gate resistor 5, the rectifier element 4 and the capacitor 7, and the power semiconductor. The power semiconductor 12 is conducted by being applied to the gate 12. At this time, the reverse bias voltage is charged to the capacitor 7 through the limiting resistor 9 and the rectifying element 8 from the reverse bias charging intermediate terminal of the pulse transformer secondary winding.
[0011]
When an OFF signal is output from the drive signal generation circuit 1, the switching element 2 is turned OFF, the voltage to the pulse transformer primary winding is released, and a counter electromotive voltage is induced in the pulse transformer secondary winding. This back electromotive voltage is regenerated through the resistor 11 and the rectifying element 10. At this time, the switching element 6 is turned on, and the voltage charged in the capacitor 7 is supplied to the gate of the power semiconductor 12 as a reverse bias voltage. Thereby, the power semiconductor 12 can discharge the electric charge accumulated in the gate more rapidly and increase the OFF speed.
[0012]
[Problems to be solved by the invention]
However, in the conventional drive circuit as described above, it is necessary to use a pulse transformer having a secondary intermediate terminal for reverse bias, and the pulse transformer must be a dedicated design product, and the circuit configuration is complicated. Had the problem of becoming.
[0013]
The present invention solves the above-described conventional problems, and a drive circuit having a reverse bias circuit is configured by using a general pulse transformer that does not have an intermediate terminal on the secondary winding, and the circuit is simplified. Provided is a drive circuit that can be realized.
[0014]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention according to claim 1 is an arc welding machine in which a switching element that is connected to a primary winding of a pulse transformer and drives the pulse transformer, and a forward bias voltage from the secondary side of the pulse transformer. A rectifying element for applying a voltage to the gate of the power semiconductor, a capacitor connected in series to the secondary circuit of the pulse transformer and charged with a reverse bias voltage during a forward bias period, and a capacitor for limiting the charging voltage of the capacitor And a power semiconductor drive circuit provided with a reverse bias switching element that applies a charging voltage of the capacitor to the power semiconductor as a reverse bias voltage during the gate OFF period.
[0015]
According to a second aspect of the present invention, in the plasma cutting machine, the power semiconductor drive circuit according to the first aspect is provided.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 of the present invention and the invention according to claim 2 are configured such that a power semiconductor drive circuit having the same configuration is mounted on an arc welder in claim 1, and mounted on a plasma cutting machine in claim 2. Since the configuration and the same operation are both achieved, the description of the embodiment of the present invention will be made with respect to an arc welder.
[0017]
Hereinafter, the arc welding machine which shows embodiment of this invention is demonstrated concretely, referring drawings.
[0018]
FIG. 1 is a circuit diagram showing a power semiconductor drive circuit configuration of an arc welder in an embodiment of the present invention.
[0019]
In FIG. 1, 1 is a drive signal generating circuit, 2 is a switching element for driving a pulse transformer, 13 is a pulse transformer having no intermediate terminal in the secondary winding, and 4 is a rectifying element for applying a forward bias voltage for driving the gate 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, 14 is a Zener diode for determining a reverse bias voltage value charged in the capacitor 7, 10 and 11 is a pulse transformer back electromotive voltage regeneration circuit for conducting the switching element 6 during the drive signal OFF period, 10 is a rectifier, 11 is a resistor, and 12 is an output control of a welding machine or a plasma cutting machine. Power semiconductor.
[0020]
The operation of the power semiconductor drive circuit configured as described above will be described below.
[0021]
In response to the ON signal output from the drive signal generation circuit 1, the pulse transformer driving switching element 2 applies a drive voltage to the primary winding of the pulse transformer 3. 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 passes through the gate resistor 5, the rectifier element 4 and the capacitor 7, and the power semiconductor. The power semiconductor 12 is conducted by being applied to the gate 12. At this time, the reverse bias voltage is charged to the capacitor 7 by the bias current due to the forward bias, and the charged voltage is clamped to a voltage level determined by the Zener diode 14.
[0022]
When an OFF signal is output from the drive signal generation circuit 1, the switching element 2 is turned OFF, the voltage to the pulse transformer primary winding is released, and a counter electromotive voltage is induced in the pulse transformer secondary winding. This back electromotive voltage is regenerated through the resistor 11 and the rectifying element 10. At this time, the switching element 6 is turned on, and the voltage charged in the capacitor 7 is supplied to the gate of the power semiconductor 12 as a reverse bias voltage. Thereby, the power semiconductor 12 can discharge the electric charge accumulated in the gate more rapidly and increase the OFF speed.
[0023]
That is, if this configuration is used, in a welding machine or a cutting machine, a power semiconductor drive circuit having a reverse bias circuit is configured using a general pulse transformer that does not have an intermediate terminal in the secondary winding, and the circuit Simplification can also be realized.
[0024]
By using the power semiconductor drive circuit having the reverse bias circuit described above, the same operation and effect can be obtained in the plasma cutting machine.
[0025]
【The invention's effect】
As described above, according to the present invention, in the arc welder, a power semiconductor drive circuit having a reverse bias circuit is configured using a general pulse transformer that does not include an intermediate terminal in the secondary winding, and the circuit Simplification can also be realized.
[0026]
Moreover, in a plasma cutting machine, a power semiconductor drive circuit having a reverse bias circuit can be configured by using a general pulse transformer that does not have an intermediate terminal on the secondary winding, and the circuit can be simplified. it can.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a configuration of a power semiconductor drive circuit for an arc welder in an embodiment of the present invention. FIG. 2 is a circuit diagram showing a configuration of a conventional power semiconductor drive circuit for a welder.
DESCRIPTION OF SYMBOLS 1 Drive signal generation circuit 2 Pulse transformer drive switching element 3 Pulse transformer having an intermediate terminal for reverse bias on the secondary side 4 Rectifier 5 Gate resistance 6 Reverse bias switching element 7 Capacitor 8 serving as a reverse bias voltage source Rectification Element 9 Limiting resistor 10 Rectifying element 11 Resistor 12 Power semiconductor 13 Pulse transformer having no intermediate terminal in the secondary winding 14 Zener diode for determining a reverse bias voltage value

Claims (2)

A switching element that is connected to the primary winding of the pulse transformer and drives the pulse transformer, a rectifier element that applies a forward bias voltage to the gate of the power semiconductor from the secondary side of the pulse transformer, and a series circuit in the pulse transformer secondary side circuit A capacitor connected and charged with a reverse bias voltage during a forward bias period; a Zener diode connected in parallel to the capacitor to limit the charging voltage of the capacitor; and a reverse bias voltage applied to the power semiconductor for charging the capacitor. An arc welding machine having a power semiconductor drive circuit provided with a reverse bias switching element applied during the gate OFF period. A switching element that is connected to the primary winding of the pulse transformer and drives the pulse transformer, a rectifier element that applies a forward bias voltage to the gate of the power semiconductor from the secondary side of the pulse transformer, and a series circuit in the pulse transformer secondary side circuit A capacitor connected and charged with a reverse bias voltage during a forward bias period; a Zener diode connected in parallel to the capacitor to limit the charging voltage of the capacitor; and a reverse bias voltage applied to the power semiconductor for charging the capacitor. A plasma cutting machine having a power semiconductor drive circuit provided with a reverse bias switching element applied during the gate OFF period.

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