Welding-type power source with integrated open-circuit voltage controller

Patent metadata

Field	Value
Publication number	US-10758993-B2
Application number	US-201715701078-A
Country	US
Kind code	B2
Filing date	Sep 11, 2017
Priority date	May 31, 2007
Publication date	Sep 1, 2020
Grant date	Sep 1, 2020

Abstract

A welding-type system and method for operating a welding-type system is disclosed. The system includes a switched power delivery circuit connected to deliver power to output terminals and an open-circuit voltage (OCV) control circuit configured to adjust an operational state of the switched power delivery circuit. A controller is included that is configured to monitor the output terminals to identify an open circuit condition and selectively engage the OCV control circuit to adjust the operational state of the switched power delivery circuit to reduce a voltage of the output power delivered to the output terminals during the open circuit condition.

First claim

We claim:

1. A welding-type power source comprising:
an inverter configured to deliver welding-type power to output terminals of the welding-type power source;
a controller configured to:
determine a connection of a voltage sensing wire feeder connected to the output terminals;
monitor conditions of the welding-type power at the output terminals to determine an open-circuit condition; and
control the inverter to deliver a reduced open-circuit voltage to the output terminals in response to determining that the voltage sensing wire feeder is connected to the output terminals and determining the open-circuit condition, wherein the controller is configured to adjust a duty cycle of the inverter to deliver the reduced open-circuit voltage.

2. The welding-type power source of claim 1 , wherein the controller is configured to control the inverter to deliver the welding-type power to the output terminals in response to determining that the open-circuit condition has ended.

3. The welding-type power source of claim 1 , wherein the controller is configured to:
control the inverter to switch between delivering the welding-type power and delivering the reduced open-circuit voltage;
monitor a voltage output in response to the switching; and
identify a voltage at the output terminals associated with the voltage sensing wire feeder when the monitored voltage output is below a low open-circuit voltage threshold level.

4. The welding-type power source of claim 3 , wherein the controller is configured to delay the switching to allow a voltage stored in a capacitor of the voltage sensing wire feeder to fall below a voltage provided to the output terminals.

5. The welding-type power source of claim 4 , wherein the delay has a duration of approximately 0.5 seconds.

6. The welding-type power source of claim 1 , further comprising a filter configured to regulate an average output voltage and reduce voltage ripples at the output terminals.

7. The welding-type power supply of claim 6 , wherein the filter is a resistor-capacitor (RC) filter.

8. The welding-type power source of claim 7 , wherein the RC filter between the output terminals has a capacitance of at least:

C
≥

(

π
·

f
S

)

⁢

(

Tp

m
⁢

⁢
i
⁢

⁢
n

)

2

⁢

(

V
S

-
10

)

2

11
⁢

,

⁢
250

;

where f s is a switching frequency of the inverter, Tp min is a minimum achievable pulse width on time, and V s is a non-reduced voltage of a transformer secondary of a transformer connected to the inverter.

9. The welding-type power source of claim 1 , wherein the inverter is configured to deliver the reduced open-circuit voltage at a voltage at the output terminals to operate the voltage sensing wire feeder during idle and jog conditions.

10. A method of operating a welding-type power source, comprising:
controlling an inverter to deliver a welding-type power to output terminals of the welding-type power source;
determining connection of a voltage sensing wire feeder connected to the output terminals;
monitoring conditions of the welding-type power at the output terminals to determine an open-circuit condition;
comparing a voltage at the output terminals to a predetermined voltage window;
engaging a failsafe lockout if the voltage is outside the predetermined voltage window for a predetermined time interval; and
controlling the inverter to deliver a reduced open-circuit voltage to the output terminals in response to determining that the voltage sensing wire feeder is connected to the output terminals and determining the open-circuit condition.

11. The method of claim 10 , further comprising controlling the inverter to deliver the welding-type power to the output terminals in response to determining that the open-circuit condition has ended.

12. The method of claim 10 , wherein the determining of the connection of the voltage sensing wire feeder further includes:
switching between controlling the inverter to deliver the welding-type power and controlling the inverter to deliver the reduced open-circuit voltage;
monitor a voltage output in response to the switching; and
identifying a voltage at the output terminals associated with the voltage sensing wire feeder when the monitored voltage output is below a low open-circuit voltage threshold level.

13. The method of claim 12 , further comprising delaying the switching to allow a voltage stored in a capacitor of the voltage sensing wire feeder to fall below a voltage provided to the output terminals.

14. The method of claim 13 , wherein the step of delaying has a duration of approximately 0.5 seconds.

15. The method of claim 10 , further comprising filtering to regulate an average output voltage and reduce voltage ripples at the output terminals.

16. The method of claim 15 , wherein the filtering includes applying an RC filter between the output terminals, having a capacitance of at least:

C
≥

(

π
·

f
S

)

⁢

(

Tp

m
⁢

⁢
i
⁢

Assignees

• Illinois Tool Works

Inventors

• Schartner Quinn W
• Bunker Thomas A

Classifications

• B23K9/1031 Primary

  Reduction of the arc voltage beneath the arc striking value, e.g. to zero voltage, during non-welding periods · CPC title