阅读说明：本技术 检测等离子切割机焊接电流和转移弧电流的电路 (Circuit for detecting welding current and transferred arc current of plasma cutting machine ) 是由 朱慧敏 于 2020-01-15 设计创作，主要内容包括：本发明公开了一种检测等离子切割机焊接电流和转移弧电流的电路,用于利用转移弧切割的等离子切割机,等离子切割机与电源电路相连,电源电路将交流电电源的交流信号变频并整流为等离子切割机需要的工作电压和频率,包含：负载电路,负载电路与电源电路相连；电流传感器,电流传感器设置在负载电路中。本发明通过一个霍尔电流传感器即可实现既检测等离子切割机的总输出电流,又能检测切割电流,巧妙运用了霍尔电流传感器,结构精巧,大大降低了成本；同时,控制方法也未增加任何复杂性,具有显著的经济效益。(The invention discloses a circuit for detecting welding current and transferred arc current of a plasma cutting machine, which is used for the plasma cutting machine utilizing transferred arc cutting, the plasma cutting machine is connected with a power circuit, the power circuit converts and rectifies alternating current signals of an alternating current power supply into working voltage and frequency required by the plasma cutting machine, and the circuit comprises: the load circuit is connected with the power supply circuit; and the current sensor is arranged in the load circuit. The plasma cutting machine can detect the total output current of the plasma cutting machine and the cutting current through the Hall current sensor, the Hall current sensor is skillfully used, the structure is exquisite, and the cost is greatly reduced; meanwhile, the control method does not increase any complexity, and has remarkable economic benefit.)

1. A circuit for detecting welding current and transferred arc current of a plasma cutting machine, which is used for the plasma cutting machine cutting by using the transferred arc, the plasma cutting machine is connected with a power circuit, the power circuit converts and rectifies alternating current signals of an alternating current power supply into working voltage and frequency required by the plasma cutting machine, and the circuit is characterized by comprising:

the load circuit is connected with the power supply circuit;

a current sensor disposed in the load circuit.

2. The circuit for detecting welding current and transferred arc current in a plasma cutting machine according to claim 1, wherein said power circuit comprises: the input end of the frequency conversion circuit is connected with an alternating current power supply, the primary side of the transformer is connected with the output end of the frequency conversion circuit, the input end of the rectification circuit is connected with the secondary side of the transformer, and the output end of the rectification circuit is the anode of the power supply circuit.

3. The circuit for detecting welding current and transferred arc current in a plasma cutting machine according to claim 2, wherein said frequency conversion circuit comprises, in series:

a rectifier sub-circuit connected to an alternating current power supply;

the filter capacitor is connected with the rectifier sub-circuit;

and the input end of the inverter sub-circuit is connected with the filter capacitor, and the output end of the inverter sub-circuit is connected with the primary side of the transformer.

4. The circuit for detecting welding current and transferred arc current of a plasma cutting machine according to claim 3, wherein said rectifier sub-circuit is a bridge rectifier circuit composed of four diodes, and said rectifier circuit is a single-phase full-wave rectifier circuit composed of two diodes, said single-phase full-wave rectifier circuit being connected to the secondary side of said transformer.

5. The circuit for detecting welding current and transferred arc current in a plasma cutting machine according to claim 1, wherein said load circuit comprises an electrode branch and a transferred arc branch;

the electrode branch is a branch formed by connecting an electrode of the plasma cutting machine and the negative electrode of the power circuit;

the switching arc branch is a branch of which the nozzle of the plasma cutting machine is connected with the anode of the power circuit.

6. The circuit for detecting welding current and transferred arc current of a plasma cutting machine according to claim 5, wherein said current sensor is a Hall current sensor, and the wire of said transferred arc branch is led out from the positive pole of said power circuit, passes through said Hall current sensor, and then is wound back to pass through said Hall current sensor again and then is connected to the workpiece.

7. The circuit for detecting welding current and transferred arc current of a plasma cutting machine as set forth in claim 6, wherein the direction in which the wire of said transferred arc branch passes twice through said hall current sensor is the same.

8. The circuit for detecting welding current and transferred arc current of a plasma cutting machine according to claim 7, wherein the transferred arc branch further comprises an insulated gate bipolar transistor, a collector of the insulated gate bipolar transistor is connected with an anode of the power circuit, an emitter of the insulated gate bipolar transistor is connected with a nozzle of the plasma cutting machine, and a lead wire output by the anode of the power circuit is connected with the collector of the insulated gate bipolar transistor, then winds back to pass through the Hall current sensor again, and then is connected with a workpiece.

9. The circuit for detecting welding current and transferred arc current of a plasma cutting machine according to claim 5, wherein said current sensor is a hall current sensor, a first output line output by a positive pole of said power supply circuit passes through said hall current sensor so that said hall current sensor is disposed in said transferred arc branch, a second output line output by a positive pole of said power supply circuit passes through said hall current sensor and then is connected to a workpiece, and the directions of said first output line and said second output line passing through said hall current sensor twice are the same.

10. The circuit for detecting plasma cutter welding current and transferred arc current of claim 5, wherein said electrode branch further comprises a filter inductance connected in series between a negative pole of said power circuit and an electrode of said plasma cutter.

Technical Field

The invention relates to a control circuit of a plasma cutting machine, in particular to a circuit for detecting welding current and transferred arc current of the plasma cutting machine.

Background

Disclosure of Invention

According to an embodiment of the present invention, there is provided a circuit for detecting a welding current and a transferred arc current of a plasma cutting machine, the plasma cutting machine being configured to cut by using the transferred arc, the plasma cutting machine being connected to a power supply circuit, the power supply circuit converting and rectifying an ac signal of an ac power supply into a working voltage and a frequency required by the plasma cutting machine, the circuit including:

the load circuit is connected with the power supply circuit;

and the current sensor is arranged in the load circuit.

Further, the power supply circuit includes: the input end of the frequency conversion circuit is connected with an alternating current power supply, the primary side of the transformer is connected with the output end of the frequency conversion circuit, the input end of the rectification circuit is connected with the secondary side of the transformer, and the output end of the rectification circuit is the anode of the power supply circuit.

Further, the frequency conversion circuit comprises:

the rectifier sub-circuit is connected with the alternating current power supply;

the filter capacitor is connected with the rectifier sub-circuit;

and the input end of the inverter sub-circuit is connected with the filter capacitor, and the output end of the inverter sub-circuit is connected with the primary side of the transformer.

Further, the rectifier sub-circuit is a bridge rectifier circuit composed of four diodes, the rectifier circuit is a single-phase full-wave rectifier circuit composed of two diodes, and the single-phase full-wave rectifier circuit is connected with the secondary side of the transformer.

Further, the load circuit comprises an electrode branch and a switching arc branch;

the electrode branch is a branch formed by connecting an electrode of the plasma cutting machine with the negative electrode of the power circuit;

the conversion arc branch is a branch of which the nozzle of the plasma cutting machine is connected with the anode of the power circuit.

Furthermore, the current sensor is a Hall current sensor, and a lead of the conversion arc branch is output from the anode of the power circuit, passes through the Hall current sensor, is wound back, passes through the Hall current sensor again and is connected with the workpiece.

Further, the direction of the lead of the switching arc branch passing through the Hall current sensor twice is the same.

And furthermore, the conversion arc branch also comprises an insulated gate bipolar transistor, a collector of the insulated gate bipolar transistor is connected with the anode of the power circuit, an emitter of the insulated gate bipolar transistor is connected with a nozzle of the plasma cutting machine, and a lead output by the anode of the power circuit is connected with the collector of the insulated gate bipolar transistor, then is wound back, passes through the Hall current sensor again and is connected with the workpiece.

Furthermore, the current sensor is a Hall current sensor, a first output line output by the anode of the power supply circuit penetrates through the Hall current sensor to enable the Hall current sensor to be arranged in the conversion arc branch, a second output line output by the anode of the power supply circuit penetrates through the Hall current sensor and then is connected with a workpiece, and the directions of the first output line and the second output line penetrating through the Hall current sensor twice are the same.

Further, the electrode branch also comprises: and the filter inductor is connected between the negative electrode of the power supply circuit and the electrode of the plasma cutting machine in series.

According to the circuit for detecting the welding current and the transferred arc current of the plasma cutting machine, the total output current of the plasma cutting machine can be detected and the cutting current can be detected through the Hall current sensor, the Hall current sensor is ingeniously used, the structure is exquisite, and the cost is greatly reduced; meanwhile, the control method does not increase any complexity, and has remarkable economic benefit.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and are intended to provide further explanation of the claimed technology.

Drawings

Fig. 1 is a schematic diagram of a circuit for detecting welding current and transferred arc current of a plasma cutting machine according to an embodiment of the present invention.

Detailed Description

The present invention will be further explained by describing preferred embodiments of the present invention in detail with reference to the accompanying drawings.

First, a circuit for detecting a welding current and a transferred arc current of a plasma cutting machine according to an embodiment of the present invention will be described with reference to fig. 1, which is applied to a plasma cutting machine in a wide range of applications.

As shown in fig. 1, the circuit for detecting welding current and transferred arc current of a plasma cutting machine according to an embodiment of the present invention is used for a plasma cutting machine that cuts using transferred arc, and the plasma cutting machine is connected to a power supply circuit that frequency-converts and rectifies an alternating current signal AC _ L, AC _ N of an alternating current power supply to an operating voltage and frequency required for the plasma cutting machine, and has a load circuit and a current sensor a. The load circuit is connected to the power circuit, and the current sensor a is disposed in the load circuit.

Specifically, as shown in fig. 1, the power supply circuit includes: the input end of the frequency conversion circuit is connected with an alternating current power supply, the primary side of the transformer T1 is connected with the output end of the frequency conversion circuit, the input end of the rectification circuit is connected with the secondary side of the transformer T1, and the output end of the rectification circuit is the anode of the power supply circuit. In the present embodiment, the rectifying circuit is a single-phase full-wave rectifying circuit composed of two diodes D1 and D2, and the single-phase full-wave rectifying circuit is connected to the secondary side of the transformer T1.

Further, as shown in fig. 1, the frequency conversion circuit includes: a rectifier sub-circuit BR1, a filter capacitor C5 and an inverter sub-circuit TR. The rectifier sub-circuit BR1 is a bridge rectifier circuit composed of four diodes, is connected with an alternating current power supply and rectifies alternating current into direct current; the filter capacitor C5 is connected to the rectifier sub-circuit BR1, in this embodiment, the filter capacitor C5 is a large capacitor, and filters the rectified dc to make the waveform straight; the inverter sub-circuit TR has an input terminal connected to the filter capacitor C5 and an output terminal connected to the primary side of the transformer T1.

In particular, the load circuit comprises an electrode branch and a switching arc branch. The electrode branch is a branch formed by connecting an electrode of the plasma cutting machine and the negative electrode of the power circuit; the conversion arc branch is a branch of which the nozzle of the plasma cutting machine is connected with the anode of the power circuit.

Further, as shown in fig. 1, the lead of the switching arc branch is connected to the workpiece 3 after passing through the current sensor a, i.e., the hall current sensor, after being output from the positive electrode of the power supply circuit, i.e., from the negative electrodes of the diodes D1, D2 of the rectifier circuit, and being wound back in the same direction to pass through the hall current sensor again.

Further, as shown in fig. 1, the switching arc branch further includes an Insulated Gate Bipolar Transistor (IGBT) T2, an emitter of the switching arc branch is connected to the nozzle 1 of the plasma cutting machine, and a collector of the switching arc branch is connected to an anode of the power circuit, that is, to a lead passing through the hall current sensor, in this embodiment, the lead is connected to a collector of the insulated gate bipolar transistor T2, and then, the lead is wound back to pass through the hall current sensor again and then is connected to the workpiece 3, so that the detected current can be both the current for cutting the workpiece 3 and the current for transferring the arc branch, and the switching arc branch has a delicate structure and greatly reduces the cost.

Furthermore, the electrical connection mode that the current passes through the hall current sensor after being connected with the collector of the insulated gate bipolar transistor T2 through one lead wire and then is wound back can also be realized through two lead wires, namely, a first output wire output by the anode of the power supply circuit passes through the hall current sensor to enable the hall current sensor to be arranged in a switching arc branch, a second output wire output by the anode of the power supply circuit passes through the hall current sensor and then is connected with a workpiece, the directions of the first output wire and the second output wire passing through the hall current sensor twice are the same, and the current detected by a single hall current sensor can be ensured to be the current on the cutting workpiece 3 and the current of the switching arc branch.

Furthermore, the electrode branch is also provided with a filter inductor L1 which is connected in series between the negative electrode of the power circuit, namely the middle tap of the secondary side of the transformer T1 and the electrode 2 of the plasma cutting machine.

When operating, assume that the holding current for the transferred arc state is 20A and the current for the normal cutting state is 100A. After a switch of the plasma cutting machine is turned on, the plasma cutting machine enters a transferred arc maintaining state, and the current value detected by the Hall current sensor is 20A because only the transferred arc branch has current.

When the workpiece 3 is cut, leakage current is generated on the workpiece 3 and passes through the hall current sensor, at the moment, the hall current sensor detects the leakage current and is superposed with the maintaining current 20A of the previous transferred arc, so that the detected current value of the hall current sensor is larger than 20A, the current signal is judged to be in a normal cutting state through the controller, the insulated gate bipolar transistor T2 is controlled to be switched off, the plasma cutting machine enters the normal cutting state, the cutting current in the normal cutting state is switched to be 100A, and the current passes through the hall current sensor twice, so that the detected current signal is 200A.

When the arc is broken, the cutting current can immediately drop, the detection current of the Hall current sensor can immediately be smaller than 200A, the controller receives the current signal drop of the Hall current sensor at the moment, the insulated gate bipolar transistor T2 is turned on, and then the state of arc maintenance of the transferred arc is entered.

In the above, with reference to fig. 1, the circuit for detecting the welding current and the transferred arc current of the plasma cutting machine according to the embodiment of the present invention is described, the total output current of the plasma cutting machine can be detected through one hall current sensor, the cutting current can also be detected, the hall current sensor is skillfully used, the structure is exquisite, and the cost is greatly reduced; meanwhile, the control method does not increase any complexity, and has remarkable economic benefit.

It should be noted that, in the present specification, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising circuitry for detecting plasma cutter welding current and transferred arc current" does not exclude the presence of additional like elements in a process, method, article, or apparatus that comprises the element.

While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention. Various modifications and alterations to this invention will become apparent to those skilled in the art upon reading the foregoing description. Accordingly, the scope of the invention should be determined from the following claims.