JPH10215160A - Semiconductor switching circuit with protection function, welding machine and cutting machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the damage of a power element without being affected by external noise by incorporating one or plural circuits among an overcurrent detection circuit, overheat detection circuit and a control power voltage drop detection circuit in a semiconductor element and arranging an oscillation circuit outside the semiconductor element. SOLUTION: One or plural circuits among the overcurrent detection circuit 1b, the overheat detection circuit 1c and the control power voltage drop detection circuit 1d, a stop circuit 1f and the power element 1a having a switching function are incorporated in the semiconductor element 1. One or plural circuits in the detection circuits 1b-1d are connected to the stop circuit 1f. The oscillation circuit 2 outside the semiconductor element 1 is connected to the power element 1a and the stop circuit 1f in series. When the overcurrent of not less than a rating flows in the power element 1a, for example, a signal is sent from the detection circuit 1b to the stop circuit 1f and the stop circuit 1f interrupts the signal from the oscillation circuit 2 to the power element 1a. Thus, the power element 1a stops a switching operation before it is damaged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor switching circuit having a protection function, and a welding machine and a cutting machine used in a work place having a relatively large amount of external noise and dust such as welding and cutting.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional arc welding machine having an inverter circuit using a semiconductor switching circuit with a protection function.
It is explained along.

[0003] DC power supply E (including rectified AC)
Power element 1 having a switching function
The signal is converted into a high-frequency AC output by an inverter circuit using a and input to the transformer T. The AC output of the transformer T is used as the DC output of the arc welding machine rectified by the rectifier diode D. Further, in order to prevent the power element 1a having the switching function of the inverter circuit from being damaged, an overcurrent detection circuit 1b, an overheat detection circuit 1c, a control power supply voltage drop detection circuit 1d, and a stop circuit 1f are provided outside. However, since the time required for the stop circuit 1f to stop the switching operation of the power element 1a is long, the power element 1a may be damaged. Although a DC output arc welding machine is shown as a conventional example, the configuration is the same for a plasma cutting machine and a resistance welding machine. When the output is an AC arc welding machine or the like, the rectifier diode D shown in FIG. 3 is not required.

Next, in a general electric device other than a welding machine, in order to prevent the power element 1a constituting the inverter circuit from being damaged, as shown in FIG.
A semiconductor element 11 having a built-in overheat detection circuit 1c, a control power supply voltage drop detection circuit 1d, and a stop circuit 1f is used. The semiconductor element 11 includes the overcurrent detection circuit 1b, the overheat detection circuit 1c, the control power supply voltage drop detection circuit 1d, and the stop circuit 1f.
In addition, an oscillation circuit 1e (generally called a driver circuit or a drive circuit) for causing the power element 1a to perform a switching operation is incorporated. And the instruction circuit 1
2, the command signal 12a is sent to the oscillation circuit 1e of the semiconductor element 11 through the input terminal 1e-1.

However, in addition to the input terminal 1e-1, the overcurrent detection circuit 1b, the overheat detection circuit 1c, and the control power supply voltage drop detection circuit 1d of the semiconductor element 11 having a protection function used for general electric equipment perform a protection operation. Signal output terminal 1b of the overcurrent detection circuit 1b in order to output a signal to the outside when
-1, a signal output terminal 1c-1 of the overheat detection circuit 1c, and a signal output terminal 1d-1 of the control power supply voltage drop detection circuit 1d. Such a semiconductor element 11 with a protection function cannot be used for a welding machine, a cutting machine or the like.

[0006]

That is, in a conventional welding machine, cutting machine or the like, the time required for the stop circuit 1f for preventing the breakage of the power element 1a to stop the switching operation of the power element 1a is long. , Power element 1
a was sometimes damaged.

The above-mentioned semiconductor device 11 with a protection function for general electric equipment includes a signal output terminal 1b-1 of an overcurrent detection circuit 1b to the outside and a signal output terminal 1c of an overheat detection circuit 1c.
-1, signal output terminal 1 of control power supply voltage drop detection circuit 1d
Since the input terminal 1e-1 for transmitting the command signal 12a to d-1 and the oscillation circuit 1e was provided, the distance L between the input terminals 1e-1 could not be large. Therefore, in a work place having a lot of conductive dust such as welding and cutting, the distance L between terminals is not sufficient as an insulation distance.

When the terminal distance L is short-circuited by conductive dust such as welding or cutting, the signal output terminal 1d-1 of the overcurrent detection circuit 1b and the signal output terminal 1c-1 of the overheat detection circuit 1c are provided. In addition, the signal at the signal output terminal 1d-1 of the control power supply voltage drop detection circuit 1d and the signal at the input terminal 1e-1 for transmitting the command signal 12a to the oscillation circuit 1e are not correctly transmitted, which may cause damage to the power element 1a. A command signal 12a for the oscillation circuit 1e for causing the power element 1a to perform a switching operation is sent from the command circuit 12 as a weak current signal of tens of mA. Further, in a general semiconductor device with a protection function 11 of an electric device, an oscillation circuit 1e is built in, and since an instruction circuit 12 is outside the semiconductor device 11 with a protection function,
The command signal 12a with a weak current of about 10 mA needs to transmit a long path. For this reason, it is necessary to place the work circuit such as welding or cutting in a work place where a relatively large amount of external noise is present.
The command signal 12a to e is susceptible to noise,
The command signal 12a is not transmitted correctly, which causes damage to the power element. As described above, in an arc welding machine or the like used in a work place where there is a lot of external noise or dust such as welding and cutting, the semiconductor element with a protection function of general electric equipment does not function effectively, so the power element 1a is damaged. There was a fear of doing.

An object of the present invention is to solve the above-mentioned conventional problems.

[0010]

To achieve this object, the present invention provides a thyristor, a transistor, an IGBT,
(Insulated Gate Bipolar T
a power element having a switching function, an overcurrent detection circuit for detecting an overcurrent flowing through the power element, an overheat detection circuit for detecting overheating of the power element, and a control power supply voltage drop for detecting a control power supply voltage drop. A protection circuit having a built-in detection circuit singly or plurally, and a built-in stop circuit for stopping the power element by one or a plurality of signals from the overcurrent detection circuit, the overheat detection circuit, and the control power supply low voltage detection circuit. A semiconductor switching circuit with a function, wherein one or more of the overcurrent detection circuit, the overheat detection circuit, and the control power supply voltage drop detection circuit are built in a semiconductor element, and the stop circuit is provided with the power element. The overcurrent detection circuit,
One or more of the overheat detection circuit and the control power supply voltage drop detection circuit is connected to the stop circuit, and the built-in overcurrent detection circuit, the overheat detection circuit, and the control power supply voltage drop detection circuit are connected to the semiconductor. It does not have an output terminal to the outside of the element.

Further, the welding machine of the present invention has an inverter circuit using the semiconductor switching circuit with the protection function.

Further, the cutting machine of the present invention has an inverter circuit using the semiconductor switching circuit with the protection function.

[0013]

With the above arrangement, the semiconductor switching circuit with a protection function of the present invention has a signal output terminal of an overcurrent detection circuit for outputting a signal to the outside of a semiconductor element, a signal output terminal of an overheat detection circuit, and a control power supply. The signal output terminal of the voltage drop detection circuit has been eliminated to secure the distance between the input terminal of the oscillation circuit and the input terminal to the stop circuit.
By arranging the oscillation circuit outside the semiconductor element to transmit the weak current command signal through a short path, the oscillation circuit is not affected by external noise and has an effect of preventing the power element from being damaged. Further, the welding machine and the cutting machine of the present invention have the above-mentioned semiconductor switching circuit with a protection function, and have a function of performing a stable operation even in a work place which is easily affected by external noise.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
It will be described with reference to FIG. FIG. 1 shows a semiconductor switching circuit with a protection function according to an embodiment of the present invention. That is, one of the overcurrent detection circuit 1b, the overheat detection circuit 1c, and the control power supply voltage drop detection circuit 1d is provided inside the semiconductor element 1.
One or more, a stop circuit 1f, and a power element 1a having a switching function.
b, overheat detection circuit 1c, control power supply voltage drop detection circuit 1d
Of these, one or a plurality of them are connected to the stop circuit 1f, and an oscillation circuit 2 outside the semiconductor element 1 is connected in series to the power element 1a and the stop circuit 1f.

When an overcurrent exceeding the rating flows through the power element 1a, a signal is sent from the overcurrent detection circuit 1b to the stop circuit 1f, and the stop circuit 1f is turned on by the oscillation circuit 2f.
By interrupting the signal from the power element 1a to the power element 1a, the power element 1a stops the switching operation before being damaged.

When the temperature of the power element 1a becomes higher than its rated value, a signal is sent from the overheat detection circuit 1c to the stop circuit 1f, and the stop circuit 1f sends a signal from the oscillation circuit 2 to the power element 1a. , The switching operation of the power element 1a is stopped before the power element 1a is damaged.

Further, when the power element 1a receives a voltage lower than the rated voltage, a signal is sent from the control power supply voltage drop detection circuit 1d to the stop circuit 1f, and the stop circuit 1f sends the signal from the oscillation circuit 2 to the power element 1a. , The switching operation of the power element 1a is stopped before the power element 1a is damaged.

The above is an explanation of the embodiment in the case where the operating points of the overcurrent detection circuit 1b, the overheat detection circuit 1c, and the control power supply voltage drop detection circuit 1d are set out of the rating. 1b, the overheat detection circuit 1c, and the control power supply voltage drop detection circuit 1d can be set to any operating point.

Since the overcurrent detection circuit 1b, the overheat detection circuit 1c, and the control power supply voltage drop detection circuit 1d have no output terminal to the outside, the external connection terminal of the semiconductor element 1 is only the input terminal 1f-1. In addition, there is an advantage that a sufficient insulation distance L can be ensured even in a work place having a large amount of conductive dust such as welding and cutting.

Further, since the signal to the semiconductor element 1 is a signal output from the oscillation circuit 2 which is hardly affected by noise, a stable operation can be performed even in a work place having a lot of external noise such as welding and cutting. is there.

FIG. 2 shows an embodiment of a welding machine or cutting machine having an inverter circuit using the semiconductor switching circuit with a protection function of FIG. 3, the DC voltage of the DC power supply E is converted into a high-frequency AC by an inverter circuit and input to the transformer T. The AC output of the transformer T is rectified by the rectifier diode D to be a DC output of a welding machine or a cutting machine.

[0022]

According to the semiconductor switching circuit with a protection function of the present invention, one or more of an overcurrent detection circuit, an overheat detection circuit and a control power supply voltage drop detection circuit are connected to a stop circuit inside a semiconductor element. An oscillation circuit external to the semiconductor element is connected in series with the stop circuit and the power element, and a built-in overcurrent detection circuit, overheat detection circuit, and control power supply voltage drop detection circuit connect an output terminal to the outside of the semiconductor element. Since they do not have respective components, the external connection terminal of the semiconductor element is only an input terminal from the oscillation circuit, and a sufficient insulation distance between the terminals can be ensured, and the power element is not affected by external noise and is not damaged. It has the effect that it has.

Further, the welding machine and the cutting machine of the present invention have an inverter circuit using a semiconductor switching circuit with a protection function, so that the power element can be prevented from being damaged when used in a work place with a lot of external noise and dust. It has excellent effects.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of a semiconductor switching circuit with a protection function according to an embodiment of the present invention.

FIG. 2 is a block circuit diagram of an inverter circuit using the semiconductor switching circuit with the protection function.

FIG. 3 is a block circuit diagram of a conventional inverter circuit.

FIG. 4 is a block circuit diagram of a semiconductor device with a protection function used in general electric equipment.

[Explanation of symbols]

 Reference Signs List 1 semiconductor element 1a power element 1b overcurrent detection circuit 1c control power supply voltage drop detection circuit 1f stop circuit 2 oscillation circuit

Continuation of the front page (72) Inventor Yoshiyuki Tabata 1006 Kazuma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] A power device having a switching function such as a thyristor, a transistor, or an IGBT; an oscillation circuit for causing the power device to perform a switching operation; and an overcurrent detection circuit for detecting an overcurrent flowing through the power device. ,
An overheat detection circuit that detects overheating of the power element, a control power supply voltage drop detection circuit that detects a control power supply voltage drop of the power element, the overcurrent detection circuit, the overheat detection circuit, and the control power supply voltage drop detection circuit. A protection switching semiconductor circuit including a stop circuit for interrupting a signal from the oscillation circuit to the power element by one or more signals, wherein the overcurrent detection circuit and the overheat detection circuit are provided inside a semiconductor element. Circuit, one or more of the control power supply voltage drop detection circuits, and the stop circuit and the power element.
One or more of the overheat detection circuit and the control power supply voltage drop detection circuit are connected to the stop circuit, the oscillation circuit outside the semiconductor element is connected in series to the power element and the stop circuit, and A semiconductor switching circuit with a protection function, wherein the overcurrent detection circuit, the overheat detection circuit, or the control power supply voltage drop detection circuit does not have an output terminal to the outside of the semiconductor element. 2. A welding machine having an inverter circuit using the semiconductor switching circuit with a protection function according to claim 1. 3. A cutting machine having an inverter circuit using the semiconductor switching circuit with a protection function according to claim 1.