US2008296276A1PendingUtilityA1
Welding-Type Power Source with Integrated Open-Circuit Voltage Controller
Est. expiryMay 31, 2027(~0.8 yrs left)· nominal 20-yr term from priority
B23K 9/1031
56
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Claims
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.
Claims
exact text as granted — not AI-modified1 . A welding-type system comprising:
a switched power delivery circuit connected to deliver power to output terminals; an open-circuit voltage (OCV) control circuit configured to adjust an operational state of the switched power delivery circuit; and a controller 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.
2 . The welding-type system of claim 1 further comprising a filter circuit connected to regulate an average voltage of the power delivered to the output terminals by the switched power delivery circuit.
3 . The welding-type system of claim 2 wherein the switched power delivery circuit includes a transformer having a primary voltage and a secondary voltage and an inverter having a minimum pulse width on time to operate at a switching frequency and, wherein the filter circuit has a capacitance of at least:
C
≥
(
π
·
f
S
)
(
Tp
min
)
2
(
V
S
-
10
)
2
11
,
250
;
where f s is the switching frequency of the inverter, Tp min is the minimum achievable pulse width on time, and V s is a non-reduced voltage of the transformer secondary.
4 . The welding-type system of claim 2 wherein the filter circuit decreases an impedance at the output terminal to substantially reduce a ripple current in an external welding circuit connected to the output terminal during a welding-type process.
5 . The welding-type system of claim 1 further comprising a voltage feedback circuit configured to monitor the output terminals and provide voltage feedback to the controller to identify an open circuit condition.
6 . The welding type system of claim 5 wherein the controller is further configured to compare the voltage feedback to a predetermined voltage window and engage a failsafe lockout if the voltage feedback is outside the predetermined voltage window for a predetermined time interval.
7 . The welding-type system of claim 6 further comprising a display configured to display an error message upon engaging the failsafe lockout.
8 . The welding-type system of claim 5 wherein the controller is further configured to compare a peak of the voltage feedback to a threshold value and, if the peak is above the threshold value, engage a failsafe lockout.
9 . The welding-type system of claim 1 wherein the OCV control circuit is configured to adjust the operational state of the switched power delivery circuit to reduce the voltage of the output power delivered to the output terminals during the open circuit condition to not greater than 35 volts.
10 . The welding-type system of claim 9 further comprising a voltage sensing wire feeder connected to at least one of the output terminals.
11 . The welding-type system of claim 10 wherein the voltage of the output power delivered to the output terminals during the open circuit condition is maintained below 35 volts during idle operation of the voltage sensing wire feeder and during jog operation of the voltage sensing wire feeder.
12 . The welding-type system of claim 1 further comprising a switch configured to engage the OCV control circuit and wherein the controller is configured to only close the switch to engage the OCV control circuit upon user selection of a low open-circuit voltage mode.
13 . The welding-type system of claim 12 wherein the controller is further configured to delay closing the switch upon detecting the open circuit condition to determining if the open-circuit condition is momentary.
14 . The welding-type system of claim 12 further comprising a voltage sensing wire feeder connected to receive operational power from the output terminals and wherein the controller is configured to immediately close the switch upon determining an open circuit condition and, after a predetermined delay, open the switch to determine connection of the voltage sensing wire feeder connected to the output terminals.
15 . A welding-type power supply comprising:
a pair of output terminals configured to deliver welding-type power to drive a welding-type process; an inverter configured to switch at a switching frequency to generate alternating current (AC) power; a pulse-width modulation (PWM) controller configured to generate a plurality of pulses having a minimum pulse width on time to cause the inverter to switch at the switching frequency to generate the AC power; a rectifier configured to receive the AC power and convert the AC power to the welding-type power delivered to the output terminals; a transformer having a primary winding configured to receive the AC power from the inverter and a secondary winding configured to provide the AC power to the rectifier at a secondary winding voltage; a voltage reducing circuit configured to adjust the switching frequency of the inverter to reduce a voltage of the welding-type power delivered to the output terminals; and a filter connected to at least one of output terminals and having a capacitance of at least:
C
≥
(
π
·
f
S
)
(
Tp
min
)
2
(
V
S
-
10
)
2
11
,
250
;
where f s is the switching frequency of the inverter, Tp min is the minimum achievable pulse width on time, and V s is a non-reduced voltage of the transformer secondary.
16 . The welding-type power supply of claim 15 further comprising:
a sensor configured to monitor the output terminals and provide feedback regarding a power condition at the output terminals; and a controller configured to receive the feedback from the sensor and, upon determining an open circuit condition at the output terminals from the feedback, engage the voltage reducing circuit to cause the PWM controller to reduce the minimum pulse width on time to cause the inverter to switch at a reduced switching frequency and, thereby, reduce the voltage of the welding-type power provided to the output terminals.
17 . The welding-type power supply of claim 15 wherein the filter is an RC filter.
18 . A welding-type power source comprising:
a housing; a pair of output terminals extending from the housing; an inverter arranged in the housing and configured to deliver welding-type power to the output terminals; a voltage reducing circuit arranged in the housing and configured to reduce a voltage of the welding-type power delivered to the output terminals; and a controller arranged in the housing and configured to determine an open-circuit condition at the output terminals and selectively engage the voltage reducing circuit to reduce the voltage of the welding-type power delivered to the output terminals during the open-circuit condition.
19 . The welding-type power source of claim 18 wherein the controller is further configured to determine connection of a voltage sensing wire feeder connected to the output terminals and reduce the voltage of the welding-type power delivered to the output terminals during the open-circuit condition while maintaining a sufficient voltage at the output terminals to operate the voltage sensing wire feeder during idle and jog conditions.
20 . The welding-type power source of claim 18 wherein the reduced voltage is less than 40 volts and greater than 15 volts.
21 . A method of operating a welding-type power source comprising the steps of:
controlling an inverter according to a first technique 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 a beginning of an open-circuit condition; and upon determining connection of the voltage sensing wire feeder connected to the output terminals and the open-circuit condition at the output terminals, controlling the inverter according to a second technique to deliver a reduced open-circuit voltage to the output terminals.
22 . The method of claim 21 further comprising the step of:
monitoring conditions of the welding-type power at the output terminals to determine an end of the open-circuit condition; and upon determining the end of the open-circuit condition at the output terminals, controlling the inverter according to the first technique to deliver the welding-type power to the output terminals.
23 . The method of claim 21 wherein the step of determining connection of a voltage sensing wire feeder further includes periodically switching between controlling the inverter according to the first technique and the second technique and identifying a voltage at the output terminals associated with a voltage sensing wire feeder.
24 . The method of claim 23 further comprising the step of delaying the step of periodically switching to allow a voltage stored in a capacitance of the voltage sensing wire feeder to fall below a voltage provided to the output terminals.
25 . The method of claim 24 wherein the step of delaying has a duration of approximately 0.5 seconds.
26 . The method of claim 21 further comprising the step of filtering to regulate an average output voltage and reduce voltage ripples at the output terminals.
27 . The method of claim 26 wherein the step of filtering including applying an RC filter between the output terminals having a capacitance of at least:
C
≥
(
π
·
f
S
)
(
Tp
min
)
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.
28 . The method of claim 21 wherein the step of monitoring conditions further includes comparing a voltage at the output terminals to a predetermined voltage window and engaging a failsafe lockout if the voltage is outside the predetermined voltage window for a predetermined time interval.
29 . The method of claim 21 wherein the step of controlling the inverter according to a second technique includes adjusting a duty cycle of the inverter to deliver a decreased open-circuit voltage.
30 . The method of claim 21 wherein the step of controlling the inverter according to a second technique includes maintaining a sufficient voltage at the output terminals to operate the voltage sensing wire feeder during idle and jog conditions.Join the waitlist — get patent alerts
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