Systems and methods for detecting non-operating thyristors in welding systems

Patent metadata

Field	Value
Publication number	US-2016167152-A1
Application number	US-201414565994-A
Country	US
Kind code	A1
Filing date	Dec 10, 2014
Priority date	Dec 10, 2014
Publication date	Jun 16, 2016
Grant date	—

Abstract

A welding system includes a power supply coupled to a power source and configured to receive a power signal. The power supply includes power conversion circuitry having one or more silicon-controlled rectifiers (SCRs) and configured to rectify the power signal to generate a DC signal for use in providing welding power. The welding system also includes an SCR detection system configured to receive a signal indicative of an inductor current of the DC signal and a signal indicative of a voltage of the DC signal. The SCR detection system is further configured detect a non-firing, open, or shorted SCR in the one or more SCRs based on the inductor current and the welding voltage of the DC signal.

First claim

1 . A welding system, comprising:
a power supply coupled to a power source and configured to receive a power signal, the power supply comprising power conversion circuitry having one or more silicon-controlled rectifiers (SCRs) and configured to rectify the power signal to generate a DC signal for use in providing welding power; and an SCR detection system configured to receive a signal indicative of an inductor current of the DC signal and a signal indicative of a voltage of the DC signal, and detect a non-firing, open, or shorted SCR in the one or more SCRs based on the inductor current or the welding voltage of the DC signal, or both.

2 . The welding system of claim 1 , wherein the SCR detection system is configured to determine a ripple component of the inductor current and the welding voltage, and detect the non-firing, open, or shorted SCR if the ripple component is significant at a frequency of the power signal for a pre-set number of cycles.

3 . The welding system of claim 2 , wherein the SCR detection system is configured to detect the frequency of the power signal.

4 . The welding system of claim 1 , wherein the SCR detection system comprises memory and a digital signal processor.

5 . The welding system of claim 1 , wherein the SCR detection system is part of a retrofit kit for the welding system.

6 . The welding system of claim 4 , wherein the SCR detection system is configured to determine the ripple component using only shift and add operations.

7 . The welding system of claim 1 , wherein the SCR detection system is configured to shut down the welding system upon detection of a non-firing, open, or shorted SCR.

8 . The welding system of claim 1 , wherein the SCR detection system is configured to generate an operator alert upon detection of a non-firing, open, or shorted SCR.

9 . The welding system of claim 1 , wherein the power supply is configured to rectify single-phase power from a single-phase power source.

10 . The welding system of claim 1 , wherein the power supply is configured to rectify three-phase power from the power source.

11 . The welding system of claim 1 , wherein the power signal is a balanced power signal.

12 . The welding system of claim 1 , wherein the power signal is an unbalanced power signal.

13 . A method, comprising, in a welding system comprising a power supply coupled to a power source and configured to receive a power signal, the power supply comprising power conversion circuitry having one or more silicon-controlled rectifiers (SCRs) and configured to rectify the power signal to generate a DC signal for use in providing welding power:
receiving a signal indicative of a frequency of an AC signal provided by the power source; receiving a signal indicative of an inductor current of a DC signal generated by rectifying the AC signal via the power conversion circuitry; receiving a signal indicative of a voltage of the DC signal; determining a ripple component of the inductor current or the welding voltage, or both; detecting a non-firing, open, or shorted SCR if the line frequency ripple component is significant for a pre-set number of cycles of the AC signal.

14 . The method of claim 13 , comprising using a Fourier transform to determine the ripple component.

15 . The method of claim 13 , comprising generating a warning signal if the ripple component is equivalent to the frequency of the AC signal for a pre-set number of cycles less than the number of cycles that indicates a non-firing, open, or shorted SCR.

16 . The method of claim 13 , comprising generating and transmitting a control signal to a control system of a welding system comprising the power conversion circuitry upon detecting a non-firing, open, or shorted SCR.

17 . A retrofit kit for a welding system, comprising:
electronic memory storing executable code; and a digital signal processor operatively coupled to the memory and configured to execute the stored code to receive a signal indicative of an AC power signal for the welding system, a signal indicative of an inductor current of a DC signal generated by rectifying the AC power signal, and a signal indicative of a welding voltage of the DC signal, determine a ripple component of the inductor current or the welding voltage, or both, and detect a non-firing, open, or shorted SCR if the line frequency ripple component is significant.

18 . The retrofit kit of claim 17 , wherein the digital signal processor is configured to generate a warning signal if the line frequency ripple component is significant for a pre-set number of cycles less than the number of cycles that indicates a non-firing, open, or shorted SCR.

19 . The retrofit kit of claim 18 , wherein the digital signal processor is configured to detect the frequency of the AC power signal.

20 . The retrofit kit of claim 17 , wherein the digital signal processor is configured to transmit a control signal to a control system for the welding system upon detection of a non-firing, open, or shorted SCR.

Assignees

• Illinois Tool Works

Inventors

• Ulrich James F

Classifications

• G01R31/50

  Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections (testing of sparking plugs H01T13/58) · CPC title

• B23K9/1062

  with computing means · CPC title

• H02H7/1255

  responsive to internal faults, e.g. by monitoring ripple in output voltage · CPC title

• B23K9/0956

  using sensing means, e.g. optical · CPC title

• B23K9/1043 Primary

  characterised by the electric circuit (B23K9/1012 takes precedence) · CPC title