US5615095A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for protecting an inverter power supply
Assignee: Illinois Tool Works Inc
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Filing: 1995-06-07
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Granted: 1997-03-25
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Expires: 2015-06-07
Abstract
Abstract In accordance with the present invention a power supply for providing an ac/dc output to a load is disclosed. The power supply includes a first source of dc power and an inverter that provides an ac output to the load. A second source of dc power is provided and selectably connects the first and second sources of dc power in series with the load when the output current reverses. In one embodiment the power sources are connected in series with every output current reversal. The first source of dc power is controllable and the magnitude of the dc current is responsive to a current reference signal. A control circuit provides the current reference signal, wherein the current reference signal is pulsed immediately prior to the ac output reversing polarity. The first source of dc power source preferably includes a buck converter that is switched at a variable frequency, depending upon the desired output current. In the event the user selects either an ac or dc electrode negative output a period of electrode positive dc energy is provided at start up to help establish the arc.
Inventors
- 👤 Jon O. Reynolds
- 👤 Michael D. Madsen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 12:19
CPC Classifications
B; B23; B23K; B23K9/00; B23K9/10; B23K9/1006; B23K9/1043
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
79 words
A method of protecting an invertor comprising the steps of: providing a first dc signal; inverting the first dc signal; providing a second dc signal; connecting the first and second dc signals in an additive arrangement across the input of the inverter, thereby clamping the voltage applied to the inverter to the sum of the first and second dc signals; and clamping the voltage across the invertor to a level more than twice that of the first dc signal.
Claim 2
Independent Claim
79 words
A method of protecting an invertor comprising the steps of: providing a first dc signal; inverting the first dc signal; providing a second dc signal; connecting the first and second dc signals in an additive arrangement across the input of the inverter, thereby clamping the voltage applied to the inverter to the sum of the first and second dc signals; and clamping the voltage across the invertor to a level more than twice that of the first dc signal.
Claim 3
Dependent Claim
147 words
An ac/dc GTAW power supply for providing an output to an arc comprising: a dc source of current having a dc voltage level; an inverter connected to receive the dc source of current and capable of providing an ac output to the arc and further capable of providing an electrode negative dc output to the arc and further capable of providing an electrode positive dc output to the arc; means for providing a period of electrode positive dc energy at an initiation of the welding process and prior to the provision of electrode negative output to the arc; means for providing a period of electrode positive dc energy at the initiation of the welding process and prior to the provision of ac output to the arc; and means for clamping the voltage across the inverter to a level more than twice that of the dc voltage level.
Claim 4
Dependent Claim
147 words
An ac/dc GTAW power supply for providing an output to an arc comprising: a dc source of current having a dc voltage level; an inverter connected to receive the dc source of current and capable of providing an ac output to the arc and further capable of providing an electrode negative dc output to the arc and further capable of providing an electrode positive dc output to the arc; means for providing a period of electrode positive dc energy at an initiation of the welding process and prior to the provision of electrode negative output to the arc; means for providing a period of electrode positive dc energy at the initiation of the welding process and prior to the provision of ac output to the arc; and means for clamping the voltage across the inverter to a level more than twice that of the dc voltage level.
Claim 5
Dependent Claim
142 words
The power supply of claim 2 wherein the dc source of current is adjustable and comprises; a source of dc voltage provided between first and second buses; at least one switch having a control input, wherein the switch is connected to the first bus; a current gate connected between the switch and the second bus; and at least one inductor having a first and second end, wherein the first end is connected to the node common to the switch and the current gate, wherein the output of the converter is across the second bus and the second end of the inductor; and a variable frequency saw tooth wave generator connected to the control input, wherein the switch is turned on at the frequency of the saw tooth wave, and further wherein the frequency is inversely related to the desired current output magnitude.
Claim 6
Independent Claim
77 words
A method of providing a dc output to an arc for GTAW welding comprising: providing a dc current having a first dc voltage level; inverting the dc current to providing a period of electrode positive dc energy at an initiation of the welding process and prior to the provision of electrode negative dc output to the arc; and clamping the voltage across the invertor to a level more than twice that of the first dc voltage level.
Claim 7
Independent Claim
77 words
A method of providing a dc output to an arc for GTAW welding comprising: providing a dc current having a first dc voltage level; inverting the dc current to providing a period of electrode positive dc energy at an initiation of the welding process and prior to the provision of electrode negative dc output to the arc; and clamping the voltage across the invertor to a level more than twice that of the first dc voltage level.
Claim 8
Independent Claim
71 words
A method of starting an ac GTAW arc comprising: providing a dc current having a first dc voltage level; inverting the dc current to providing an extended period of electrode positive dc energy to the arc at an initiation of the welding process; thereafter providing an ac output to the arc; and clamping the voltage across the invertor to a level more than twice that of the first dc voltage level.
Claim 9
Independent Claim
71 words
A method of starting an ac GTAW arc comprising: providing a dc current having a first dc voltage level; inverting the dc current to providing an extended period of electrode positive dc energy to the arc at an initiation of the welding process; thereafter providing an ac output to the arc; and clamping the voltage across the invertor to a level more than twice that of the first dc voltage level.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-03-24 | 2000-09-23 | 2001-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-03-24 | 2004-09-23 | 2005-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-03-24 | 2008-09-23 | 2009-03-25 | $7700.00 | Window Closed / Lapsed |