Power convertor with low loss switching

• US 6,625,046 B2
• Filed: 06/20/2002
• Issued: 09/23/2003
• Est. Priority Date: 07/09/1998
• Status: Expired due to Term

• Current Assignee: Illinois Tool Works Inc.
• Original Assignee: Illinois Tool Works Inc.
• Inventors: Geissler, Steven
• Primary Examiner(s): NGUYEN, MATTHEW VAN
• Application Number:
  US10/176,712
• Publication Number:
  US 20020191425A1
• Time in Patent Office: 460 Days
• Field of Search: 363/16, 363/17, 363/34-37, 363/50, 363/52, 363/53, 363/55, 363/56.01, 363/56.02, 363/56.03, 363/56.05, 363/89, 363/97, 363/98, 363/125, 363/127, 363/131, 363/132, 323/222, 323/223
• US Class Current: 363/89
• CPC Class Codes: B23K 9/1043 characterised by the electric circuit B23K9/1012 takes precedence
• CPC Class Codes: B23K 9/1056 by using digital means B23K9/1068 takes precedence
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 1/342 Active non-dissipative snubbers
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y02P 70/10 Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working

Abstract

A welding power supply includes an input rectifier that receives sinusoidal or alternating line voltage and provides a rectified voltage. A pre-regulator provides a dc bus and a convertor, such as a boost convertor, provides a welding output. The pre-regulator is an SVT (slow voltage transition) and an SCT (slow current transition) switched convertor. It may include a snubber circuit having a diode that is SVT switched. Also, the boost convertor may be SVT and SCT switched. The pre-regulator preferably includes a power factor correction circuit. The power source includes, in one embodiment, an inverter having a snubber circuit having a first switch in anti-parallel with a first diode, and a second switch in anti-parallel with a second diode. The first switch and first diode are connected in series with the second switch and the second diode, and the first and second switches are connected in opposing directions, to form a switched snubber.

Claims

1. A method of providing power from a power supply including a first power switch, a second power switch, a first snubber switch, a second snubber switch, a first dc bus, a second dc bus, a first power capacitor, a second power capacitor, a first snubber diode, a second snubber diode, a first snubber capacitor, a second snubber capacitor, a first anti-parallel power diode, a second anti-parallel power diode, and a transformer, comprising:

turning on the first power switch and the first snubber switch, and allowing current to flow through the first power switch, the first dc bus, the first power capacitor, and in a first direction through the transformer;

turning the first power switch off and allowing current to flow through the first snubber switch, the second snubber diode, the first snubber capacitor, and through the transformer in the first direction, while the first power switch is turning off, to provide a slow voltage transition off;

allowing current to flow through the second anti-parallel power diode, the second DC bus, the second power capacitor, and through the transformer in the first direction, while the first power switch is continuing to turn off, to continue providing a slow voltage transition off;

turning off the first snubber switch;

turning on the second power switch and the second snubber switch after the first power switch is off, and allowing current to flow through the second power switch, the transformer in a second direction, the second power capacitor, and the second dc bus;

turning the second power switch off and allowing current to flow through the second snubber switch, the first snubber diode, the transformer in the second direction, and the second snubber capacitor, while the second power switch is turning off, to provide a slow voltage transition off;

allowing current to flow through the first anti-parallel power diode, the transformer in the second direction, and the first power capacitor, while the second power switch is turning off, to provide a slow voltage transition off;

turning off the second snubber switch;

and repeating these steps.

2. The method of claim 1, wherein turning on the first and second power switches includes soft switching on the first and second power switches.

3. A method of providing power from a power supply including a first power switch, a second power switch, a first snubber switch, a second snubber switch, a dc bus, a power capacitor, a first snubber diode, a second snubber diode, a snubber capacitor, a first anti-parallel power diode, a second anti-parallel power diode, and a transformer, comprising:

turning on the first power switch and the first snubber switch, and allowing current to flow through the first power switch, the dc bus, the power capacitor, and in a first direction through the transformer;

turning the first power switch off and allowing current to flow through the first snubber switch, the second snubber diode, the snubber capacitor, and through the transformer in the first direction, while the first power switch is turning off, to provide a slow voltage transition off;

allowing current to flow through the second anti-parallel power diode, the DC bus, the power capacitor, and through the transformer in the first direction, while the first power switch is continuing to turn off, to continue providing a slow voltage transition off;

turning off the first snubber switch;

turning on the second power switch and the second snubber switch after the first power switch is off, and allowing current to flow through the second power switch, the transformer in a second direction, the second power capacitor, and the dc bus;

turning the second power switch off and allowing current to flow through the second snubber switch, the first snubber diode, the transformer in the second direction, and the snubber capacitor, while the second power switch is turning off, to provide a slow voltage transition off;

allowing current to flow through the first anti-parallel power diode, the transformer in the second direction, and the power capacitor, while the second power switch is turning off, to provide a slow voltage transition off;

turning off the second snubber switch;

and repeating these steps.

4. The method of claim 3, wherein turning on the first and second power switches includes soft switching on the first and second power switches.

5. The method of claim 4, wherein the power capacitor is comprised of first and second capacitors, and the dc bus is a split bus.

6. The method of claim 4, wherein the snubber capacitor is comprised of first and second capacitors, and the dc bus is a split bus.