MIG WELDING MACHINE HAVING 115V INVERTER

• US 20060076331A1
• Filed: 12/09/2005
• Published: 04/13/2006
• Est. Priority Date: 09/23/2003
• Status: Active Grant

• Current Assignee: Illinois Tool Works Inc.
• Original Assignee: Illinois Tool Works Inc.
• Inventors: Vogel, Bernard J., Albrecht, Bruce, Matus, Tim A.
• Granted Patent: US 9,308,597 B2
• Time in Patent Office: Days
• US Class Current: 219/130.210
• CPC Class Codes: B23K 9/1006 Power supply
• CPC Class Codes: B23K 9/1043 characterised by the electric circuit B23K9/1012 takes precedence

Abstract

The present invention is directed to a MIG welding machine having a 115 volt inverter. Incorporation of the 115 volt inverter into the MIG welding power source reduces the weight of the power source thereby increasing its portability. The power source may include a power factor correction circuit to provide a near-unity power factor such that output power of the inverter is more efficiently provided. Additionally, the 115 volt inverter is constructed such that for short periods of time, the inverter may output power at a level that exceeds its power rating.

Claims

1. A method of regulating a power source having an 115V inverter to condition raw power into a form usable by a MIG welding process, the method comprising the step of:

determining a maximum allowable voltage error given an output condition at a weld;

determining an instantaneous command current given the maximum allowable voltage error; and

inputting a signal proportional to the instantaneous command current to a controller of the 115V inverter, the signal designed to regulate the controller to provide a control signal to regulate an output of the 115V inverter.

2. The method of claim 1 further comprising the step of inputting a signal indicative of the instantaneous command current to regulate what level of output the 115V inverter should generate.

3. The method of claim 1 further comprising the step of pulse width modulating the 115V inverter to regulate the output of the 115V inverter.

4. The method of claim 1 wherein the step of determining a maximum allowable voltage error includes the step of subtracting a voltage feedback signal from the weld from a voltage command signal.

5. The method of claim 1 further comprising the step of controlling the 115V inverter to produce either a CC or a CV output.

6. The method of claim 1 further comprising the steps of:

detecting a welding state at a weld;

limiting output current to a predetermined maximum level during an arc phase at the weld; and

limiting output current to an instantaneous maximum level based on instantaneous welding parameters during a short circuit at the weld.

7. The method of claim 6 further comprising the steps of:

monitoring duration of a short circuit at the weld;

comparing the duration to a default value;

if the duration exceeds the default value

allowing output current to increase to a clear level; and

if the short circuit persists

taking remedial action to clear the short circuit.

8. The method of claim 7 further comprising the step of either shutting off the 115V inverter or retracting wire from the weld if the short circuit persists when the output current is at the clear level.

9. The method of claim 7 further comprising the step of lowering the output current to a level lower than the clear level if the short circuit clears when the output current is at the clear level.

10. The method of claim 9 further comprising the step of allowing the 115V inverter to output power greater than a normal output power rating during a post-short circuit condition.

11. A controller to regulate a MIG welding power source having a 115 V inverter, the controller configured to execute a series of instructions that when executed cause the controller to:

determine a max allowable voltage variance given a monitored output condition at a weld that receives power thereat from the MIG welding power source;

determine an instantaneous command current based on the max allowable voltage variance; and

provide an input to the 115V inverter that is a function of the instantaneous command current to cause the power source to provide a desired output.

12. The controller of claim 11 further caused to:

detect a weld state at the weld;

regulate the power source to provide a predetermined limited output current during an arc phase at the weld; and

regulate the power source to provide an instantaneous limited output current during a short circuit at the weld, the instantaneous limited output current based on instantaneous welding parameters.

13. The controller of claim 12 further caused to:

monitor duration of a short at the weld;

compare the duration to a default, and

if the duration exceeds the default,

cause the power source to deliver an output current that will clear the short, and

if the short persists,

shut-off the power source or retract wire from the weld.

14. The controller of claim 13 further caused to cause the power source to output power at a reduced current level that is lower than that provided to clear the short if the short clears.

15. The controller of claim 32 further caused to determine the max allowable voltage variance from a difference between a commanded voltage value and a feedback voltage from the weld.

16. A MIG welding power source comprising:

a 115V inverter; and

a processor programmed to;

receive a voltage feedback signal from a weld;

determine a max permitted voltage offset from the voltage feedback signal and a commanded voltage level;

determine an instantaneous command current given the mae permitted voltage effect;

input a signal to the 115V inverter proportioned to the instantaneous command current to cause the 115 V inverter to output a desired output.

17. The power source of claim 16 wherein the processor is further programmed to receive feedback indicative of an extended short at the weld and cause the 115V to provide a reduced current output to clear the extended short.

18. The power source of claim 17 wherein the processor is further programmed to cease power delivery to the weld if the extended short does not clear with the 115V inverter providing a reduced current output.

19. The power source of claim 16 wherein the 115V inverter is connected to a power input designed to receive a 230V input.

20. The power source of claim 16 further comprising an output terminal configured to receive a cable connected to a wire feeder.