DISTORTION FREE ARC WELDING VOLTAGE MEASUREMENT

• US 20190321910A1
• Filed: 04/19/2018
• Published: 10/24/2019
• Est. Priority Date: 04/19/2018
• Status: Active Grant

• Current Assignee: Esab AB (Enovis Corp.)
• Original Assignee: Esab AB (Enovis Corp.)
• Inventors: Moreels, Karel
• Granted Patent: US 11,161,192 B2
• Time in Patent Office: Days
• CPC Class Codes: B23K 9/0953 using computing means
• CPC Class Codes: B23K 9/0956 using sensing means, e.g. optical
• CPC Class Codes: B23K 9/1043 characterised by the electric circuit B23K9/1012 takes precedence
• CPC Class Codes: B23K 9/32 Accessories earthing connections H01R

Abstract

Methods and systems to reduce distortions induced in a voltage measurement wire. In an embodiment, a measurement wire is coupled to a head of an arc welding apparatus and to a feedback circuit to provide a head voltage and noise induced on the measurement wire to the feedback circuit. A reference wire is coupled to a reference node and to the feedback circuit to provide noise induced on the reference wire to the feedback circuit. The reference node may be proximate to and electrically isolated from the head, and the measurement wire and the reference wire may be arranged adjacent to one another (e.g., as a twisted pair), so that the similar distortions are induced in the measurement wire and the reference wire. The feedback circuit determines the head voltage as a difference between noise of the reference wire and the head voltage and noise of the first measurement wire.

Claims

1. An apparatus, comprising:

a first feedback circuit configured to provide a head voltage of an arc welding apparatus to a power supply of the arc welding apparatus;

a first measurement wire coupled to a head of the arc welding apparatus and to a first input of the feedback circuit to provide the head voltage and noise induced on the first measurement wire to the feedback circuit; and

a first reference wire coupled to a first reference node of the arc welding apparatus and to a second input of the first feedback circuit to provide noise induced on the first reference wire to the feedback circuit, wherein the first reference node is proximate to and electrically isolated from the head of the arc welding apparatus;

wherein the first feedback circuit is configured to determine the head voltage as a difference between the noise of the first reference wire and the head voltage and noise of the first measurement wire.

2. The apparatus of claim 1, wherein the first feedback circuit is configured to:

invert the noise of the first reference wire; and

sum the inverted noise of the first reference wire with the head voltage and noise of the first measurement wire.

3. The apparatus of claim 2, wherein the first feedback circuit includes:

a potentiometer to control an amplitude of the inverted noise of the first reference wire that is summed with the head voltage and noise of the first measurement wire.

4. The apparatus of claim 1, wherein the first feedback circuit includes a transformer, and wherein:

a secondary winding of the transformer is biased with the head voltage and noise of the first measurement wire; and

the noise of the first reference wire is applied to a primary winding of the transformer to induce an inverted version of the noise of the first reference wire in the secondary winding to cancel the noise of the first measurement wire.

5. The apparatus of claim 4, wherein the first feedback circuit further includes:

a potentiometer to control amplification of the inverted version of the noise of the first reference wire that is summed with the head voltage and noise of the first measurement wire.

6. The apparatus of claim 1, wherein the first and second wires are arranged adjacent to one another such that the noise induced on the first measurement wire is equal to the noise induced on the first reference wire.

7. The apparatus of claim 1, wherein the first measurement wire and the first reference wire are configured as a twisted pair of wires.

8. The apparatus of claim 1, further including:

a second feedback circuit configured to provide a workpiece voltage to the power supply;

a second measurement wire coupled to the workpiece and to a first input of the second feedback circuit to provide the workpiece voltage and noise induced on the second measurement wire to the second feedback circuit; and

a second reference wire coupled to a second reference node of the arc welding apparatus and to a second input of the second feedback circuit to provide noise induced on the second reference wire to the feedback circuit, wherein the second reference node is proximate to and electrically isolated from the workpiece.

9. An arc welding apparatus, comprising:

an arc welding head;

a boom to support the head;

a column to support the boom;

a power supply to provide a voltage between the head and a workpiece;

a first feedback circuit configured to provide a head voltage to the power supply;

a first measurement wire coupled to the head and to a first input of the feedback circuit to provide the head voltage and noise induced on the first measurement wire to the feedback circuit; and

a first reference wire coupled to a first reference node of the arc welding apparatus and to a second input of the first feedback circuit to provide noise induced on the first reference wire to the feedback circuit, wherein the first reference node is proximate to and electrically isolated from the head;

wherein the first feedback circuit is configured to determine the head voltage as a difference between the noise of the first reference wire and the head voltage and noise of the first measurement wire.

10. The arc welding apparatus of claim 9, wherein the first feedback circuit is configured to:

invert the noise of the first reference wire; and

sum the inverted noise of the first reference wire with the head voltage and noise of the first measurement wire.

11. The arc welding apparatus of claim 10, wherein the first feedback circuit includes:

a potentiometer to control an amplitude of the inverted noise of the first reference wire that is summed with the head voltage and noise of the first measurement wire.

12. The arc welding apparatus of claim 9, wherein the first feedback circuit includes a transformer, and wherein:

a secondary winding of the transformer is biased with the head voltage and noise of the first measurement wire; and

the noise of the first reference wire is applied to a primary winding of the transformer to induce an inverted version of the noise of the first reference wire in the secondary winding to cancel the noise of the first measurement wire.

13. The arc welding apparatus of claim 12, wherein the first feedback circuit further includes:

a potentiometer to control amplification of the inverted version of the noise of the first reference wire that is summed with the head voltage and noise of the first measurement wire.

14. The arc welding apparatus of claim 9, wherein the first and second wires are arranged adjacent to one another such that the noise induced on the first measurement wire is equal to the noise induced on the first reference wire.

15. The arc welding apparatus of claim 9, wherein the first measurement wire and the first reference wire are configured as a twisted pair of wires.

16. The arc welding apparatus of claim 9, further including:

a second feedback circuit configured to provide a workpiece voltage to the power supply;

a second measurement wire coupled to the workpiece and to a first input of the second feedback circuit to provide the workpiece voltage and noise induced on the second measurement wire to the second feedback circuit; and

a second reference wire coupled to a second reference node of the arc welding apparatus and to a second input of the second feedback circuit to provide noise induced on the second reference wire to the feedback circuit, wherein the second reference node is proximate to and electrically isolated from the workpiece.

17. A method, comprising:

inverting noise induced in a reference wire, wherein the reference wire is coupled to a node proximate to and electrically isolated from a head of an arc welding apparatus, and wherein a path of the reference wire is adjacent to a path of a head voltage measurement wire of the arc welding apparatus;

summing the inverted noise with a head voltage received over a measurement wire, and with noise induced on the measurement wire, to provide a noiseless head voltage; and

controlling a power supply of the arc welding apparatus based on the noiseless head voltage.

18. The method of claim 17, further including:

controlling an amplitude of the inverted noise of the reference wire that is summed with the head voltage and noise of the measurement wire.

19. The method of claim 17, wherein:

the inverting includes applying the noise of the reference wire to a primary winding of a transformer to induce an inverted version of the noise at a node of a secondary winding of the transformer;

the summing includes applying the head voltage and noise of the measurement wire to the node of the secondary winding.

20. The method of claim 17, further including:

arranging the first and second wires adjacent to one another such that the noise induced on the measurement wire is equal to the noise induced on the reference wire.