Three stage power source for electric ARC welding

• US 8,581,147 B2
• Filed: 03/24/2005
• Issued: 11/12/2013
• Est. Priority Date: 03/24/2005
• Status: Active Grant

• Current Assignee: Lincoln Global Incorporated (Lincoln Electric Holdings Incorporated)
• Original Assignee: Lincoln Global Incorporated (Lincoln Electric Holdings Incorporated)
• Inventors: Kooken, Todd E., Luo, Lifeng
• Primary Examiner(s): Yuen, Henry
• Assistant Examiner(s): MAYE, AYUB A
• Application Number:
  US11/087,179
• Publication Number:
  US 20060213890A1
• Time in Patent Office: 3,155 Days
• Field of Search: 219/130.1, 219/130.5, 219/137.7, 219/137.PS
• US Class Current: 219/137.7
• CPC Class Codes: B23K 9/095 Monitoring or automatic control of welding parameters
• CPC Class Codes: B23K 9/1043 characterised by the electric circuit B23K9/1012 takes precedence
• CPC Class Codes: H02M 1/0006 Arrangements for supplying an adequate voltage to the control circuit of converters
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/0085 Partially controlled bridges
• 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: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02M 7/487 Neutral point clamped inverters
• 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
• CPC Class Codes: Y02P 80/10 Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier

Abstract

A three stage power source for an electric arc welding process comprising an input stage having an AC input and a first DC output signal; a second stage in the form of an unregulated DC to DC converter having an input connected to the first DC output signal, a network of switches switched at a high frequency with a given duty cycle to convert the input into a first internal AC signal, an isolation transformer with a primary winding driven by the first internal high frequency AC signal and a secondary winding for creating a second internal high frequency AC signal and a rectifier to convert the second internal AC signal into a second DC output signal of the second stage, with a magnitude related to the duty cycle of the switches; and, a third stage to convert the second DC output signal to a welding output for welding wherein the input stage has a regulated DC to DC converter with a boost power switch having an active soft switching circuit.

Claims

1. A three stage power source for an electric arc welding process, said power source comprising an input stage having an AC input and a first fixed DC output signal;

a second stage in the form of an unregulated DC to DC converter having an input connected to said first fixed DC output signal, a network of switches switched at a high frequency with a given duty cycle to convert said input into a first internal AC signal, an isolation transformer with a primary winding driven by said first internal high frequency AC signal and a secondary winding for creating a second internal high frequency AC signal and a rectifier to convert said second internal AC signal into a second fixed DC output signal of said second stage;

with a magnitude related to said duty cycle of said switches; and

a third stage to convert said second fixed DC output signal to a welding output for welding wherein said input stage has a regulated DC to DC converter including a boost converter having a main inductance, a main rectifier, and a power switch having an active soft switching circuit, said active soft switching circuit of said input stage comprising;

an auxiliary switching device and a tank circuit closed by said auxiliary switching device, said tank circuit comprising a resonant inductance coupled in series with said auxiliary switching device, and a resonant capacitance coupled in parallel with said power switch, said resonant capacitance having a first resonant capacitor portion coupled in parallel with said resonant inductance and a second resonant capacitor portion coupled in parallel with said auxiliary switching device.

2. A three stage power source as defined in claim 1 wherein said regulated DC to DC converter is a power factor correcting converter.

3. A three stage power source as defined in claim 1 wherein said regulated DC to DC converter is said boost converter.

4. A three stage power source as defined in claim 1 wherein said tank circuit is activated by said auxiliary switch.

5. A three stage power source as defined in claim 1 wherein said auxiliary switch is operated in unison with said power switch.

6. A three stage power source as defined in claim 1 wherein said third stage is a chopper with a power switch having a passive soft switching circuit.

7. A three stage power source as defined in claim 1 wherein said given duty cycle is greater than 80% to hold conduction losses of said second stage at a low level.

8. A three stage power source as defined in claim 1, wherein said given duty cycle is adjustable.

9. A three stage power source as defined in claim 2 wherein said regulated DC to DC power factor correcting converter includes said boost converter.

10. A three stage power source as defined in claim 2 wherein said tank circuit is activated by said auxiliary switch.

11. A three stage power source as defined in claim 2 wherein said auxiliary switch is operated in unison with said power switch.

12. A three stage power source as defined in claim 2 wherein said third stage is a chopper with a power switch having a passive soft switching circuit.

13. A three stage power source as defined in claim 2 wherein said given duty cycle is greater than 80% to hold conduction losses of said second stage at a low level.

14. A three stage power source as defined in claim 3 wherein said auxiliary switch operated in u nison with said power switch.

15. A three stage power source as defined in claim 3 wherein said tank circuit is activated by said auxiliary switch.

16. A three stage power source as defined in claim 3 wherein said third stage is a chopper with a power switch having a passive soft switching circuit.

17. A three stage power source as defined in claim 3 wherein said given duty cycle is greater than 80% to hold conduction losses of said second stage at a low level.

18. A three stage power source as defined in claim 5 wherein said main rectifier is a boost diode soft switched by said soft switching circuit.

19. A three stage power source as defined in claim 5 wherein said regulated DC to DC converter has a positive and a negative output lead with said resonant capacitance joining said leads and a diode clamping the positive end of said auxiliary switch to said positive output lead.

20. A three stage power source as defined in claim 5 wherein said third stage is a chopper with a power switch having a passive soft switching circuit.

21. A three stage power source as defined in claim 5 wherein said given duty cycle is greater than 80% to hold conduction losses of said second stage at a low level.

22. A three stage power source as defined in claim 9 wherein said tank circuit is activated by said auxiliary switch.

23. A three stage power source as defined in claim 9 wherein said auxiliary switch is operated in unison with said power switch.

24. A three stage power source as defined in claim 9 wherein said third stage is a chopper with a power switch having a passive soft switching circuit.

25. A three stage power source as defined in claim 9 wherein said given duty cycle is greater than 80% to hold conduction losses of said second stage at a low level.

26. A three stage power source as defined in claim 11 wherein said main rectifier is a boost diode soft switched by said soft switching circuit.

27. A three stage power source as defined in claim 11 wherein said regulated DC to DC converter has a positive and a negative output lead with said resonant capacitance joining said leads and a diode clamping the positive end of said auxiliary switch to said positive output lead.

28. A three stage power source as defined in claim 11 wherein said third stage is a chopper with a power switch having a passive soft switching circuit.

29. A three stage power source as defined in claim 11 wherein said given duty cycle is greater than 80% to hold conduction losses of said second stage at a low level.

30. A three stage power source as defined in claim 14 wherein said main rectifier is a boost diode soft switched by said soft switching circuit.

31. A three stage power source as defined in claim 14 wherein said tank circuit closed is activated by said auxiliary switch.

32. A three stage power source as defined in claim 14 wherein said regulated DC to DC converter has a positive and a negative output lead with said resonant capacitance joining said leads and a diode clamping the positive end of said auxiliary switch to said positive output lead.

33. A three stage power source as defined in claim 14 wherein said third stage is a chopper with a power switch having a passive soft switching circuit.

34. A three stage power source as defined in claim 14 wherein said given duty cycle is greater than 80% to hold conduction losses of said second stage at a low level.

35. A three stage power source as defined in claim 18 wherein said regulated DC to DC converter has a positive and a negative output lead with said resonant capacitance joining said leads and a diode clamping the positive end of said auxiliary switch to said positive output lead.

36. A three stage power source as defined in claim 18 wherein said third stage is a chopper with a power switch having a passive soft switching circuit.

37. A three stage power source as defined in claim 18 wherein said given duty cycle is greater than 80% to hold conduction losses of said second stage at a low level.

38. A three stage power source as defined in claim 23 wherein said main rectifier is a boost diode soft switched by said soft switching circuit.

39. A three stage power source as defined in claim 23 wherein said regulated DC to DC converter has a positive and a negative output lead with said resonant capacitance joining said leads and a diode clamping the positive end of said auxiliary switch to said positive output lead.

40. A three stage power source as defined in claim 23 wherein said third stage is a chopper with a power switch having a passive soft switching circuit.

41. A three stage power source as defined in claim 23 wherein said given duty cycle is greater than 80% to hold conduction losses of said second stage at a low level.

42. A three stage power source as defined in claim 26 wherein said regulated DC to DC converter has a positive and a negative output lead with said resonant capacitance joining said leads and a diode clamping the positive end of said auxiliary switch to said positive output lead.

43. A three stage power source as defined in claim 26 wherein said third stage is a chopper with a power switch having a passive soft switching circuit.

44. A three stage power source as defined in claim 26 wherein said given duty cycle is greater than 80% to hold conduction losses of said second stage at a low level.

45. A three stage power source as defined in claim 30 wherein said tank circuit is activated by said auxiliary switch.

46. A three stage power source as defined in claim 30 wherein said regulated DC to DC converter has a positive and a negative output lead with said resonant capacitance joining said leads and a diode clamping the positive end of said auxiliary switch to said positive output lead.

47. A three stage power source as defined in claim 31 wherein said regulated DC to DC converter has a positive and a negative output lead with said resonant capacitance joining said leads and a diode clamping the positive end of said auxiliary switch to said positive output lead.

48. A three stage power source as defined in claim 32 wherein said third stage is a chopper with a power switch having a passive soft switching circuit.

49. A three stage power source as defined in claim 32 wherein said given duty cycle is greater than 80% to hold conduction losses of said second stage at a low level.

50. A three stage power source as defined in claim 38 wherein said regulated DC to DC converter has a positive and a negative output lead with said resonant capacitance joining said leads and a diode clamping the positive end of said auxiliary switch to said positive output lead.

51. A three stage power source as defined in claim 38 wherein said third stage is a chopper with a power switch having a passive soft switching circuit.

52. A three stage power source as defined in claim 38 wherein said given duty cycle is greater than 80% to hold conduction losses of said second stage at a low level.

79. An active soft switching circuit as defined in any one of claims 1, 53 and 73, wherein the series combination of said resonant inductance and said auxiliary switching device form a first leg of said tank circuit with a first intermediate node between said resonant inductance and said auxiliary switch, wherein said first and second resonant capacitor portions form a second leg of said tank circuit with a second intermediate node between said first and second resonant capacitor portions, and wherein said tank circuit further comprises a first diode coupled between said first and second intermediate nodes and a second diode coupled between said second intermediate node and said cathode of said main rectifier.

87. An active soft switching circuit as defined in claim 79, wherein said first resonant capacitor portion is larger than said second resonant capacitor portion.

88. The active soft switching circuit as defined in claim 79, wherein said second resonant capacitor portion controls a rate of increase of a voltage across said auxiliary switching device when said auxiliary switching device is turned off.

89. The active soft switching circuit as defined in claim 79, wherein said second resonant capacitor portion controls a rate of increase of a voltage across said auxiliary switching device when said auxiliary switching device is turned off.

96. The active soft switching circuit as defined in claim 87, wherein said second resonant capacitor portion controls a rate of increase of a voltage across said auxiliary switching device when said auxiliary switching device is turned off.

53. A three stage power source comprising an input first stage having an AC input and a first fixed DC output signal, a second stage in the form of an unregulated DC to DC converter having an input connected to said first fixed DC output signal, a network of switches switched at a high frequency with a given duty cycle to convert said input into a first internal AC signal, an isolation transformer with a primary winding driven by said first internal high frequency AC signal and a secondary winding for creating a second internal AC signal and a rectifier to convert said second internal AC signal into a second fixed DC output signal of said second stage, with the magnitude related to said duty cycle of said switches, wherein said input first stage includes a boost converter having a main inductance, a main rectifier, and a power switch having an active soft switching circuit and a third stage to convert said second fixed DC output signal of said second stage into a current suitable for welding, said active soft switching circuit of said input first stage including:

an auxiliary switching device and a tank circuit closed by said auxiliary switching device, said tank circuit comprising a resonant inductance coupled in series with said auxiliary switching device, and a resonant capacitance coupled in parallel with said power switch, said resonant capacitance having a first resonant capacitor portion coupled in parallel with said resonant inductance and a second resonant capacitor portion coupled in parallel with said auxiliary switching device.

54. A power source as defined in claim 53 wherein said input first stage includes a rectifier and a power factor correcting converter.

55. A power source as defined in claim 53 wherein said power switch is in said boost converter.

56. A power source as defined in claim 53 wherein said auxiliary switch is operated in unison with said power switch.

57. A power source as defined in claim 53 wherein said given duty cycle is greater than 80% to hold conduction losses of said second stage at a low level.

58. A power source as defined in claim 54 wherein said power factor correcting converter includes said boost converter operated by said power switch.

59. A power source as defined in claim 54 wherein said auxiliary switch is operated in unison with said power switch.

60. A power source as defined in claim 54 wherein said given duty cycle is greater than 80% to hold conduction losses of said second stage at a low level.

61. A power source as defined in claim 55 wherein said auxiliary switch is operated in unison with said power switch.

62. A power source as defined in claim 55 wherein said given duty cycle is greater than 80% to hold conduction losses of said second stage at a low level.

63. A power source as defined in claim 56 wherein said given duty cycle is greater than 80% to hold conduction losses of said second stage at a low level.

64. A power source, as defined in claim 56 wherein said power switch comprises a main boost switch.

65. A power source as defined in claim 58 wherein said auxiliary switch is operated in unison with said power switch.

66. A power source as defined in claim 58 wherein said given duty cycle is greater than 80% to hold conduction losses of said second stage at a low level.

67. A power source as defined in claim 59 wherein said given duty cycle is greater than 80% to hold conduction losses of said second stage at a low level.

68. A power source as defined in claim 61 wherein said given duty cycle is greater than 80% to hold conduction losses of said second stage at a low level.

69. A power source as defined in claim 64 wherein said second resonant capacitor portion is coupled in parallel with said auxiliary switch by a forward poled diode.

70. A power source as defined in claim 64 wherein said second resonant capacitor portion is substantially less than ½

the capacitance of said first resonant capacitor portion.

71. A power source as defined in claim 65 wherein said given duty cycle is greater than 80% to hold conduction losses of said second stage at a low level.

72. A power source as defined in claim 69 wherein said second resonant capacitor portion is substantially less than ½

the capacitance of said first resonant capacitance capacitor portion.

73. A three stage power source comprising an input first stage having an AC input and a first fixed DC output signal with a DC to DC converter including a boost converter having a main inductance, a main rectifier, and a power switch with an active soft switching circuit, a second stage in the form of an unregulated DC to DC inverter having a plurality of power switches, said plurality of switches operated by a pulse-width-modulated control set at a given duty cycle, and a third stage to convert a second fixed DC output of said unregulated inverter into a current suitable for welding, said active soft switching circuit of said input first stage including an auxiliary switching device and a tank circuit closed by said auxiliary switching device, said tank circuit comprising a resonant inductance coupled in series with said auxiliary switching device, and a resonant capacitance coupled in parallel with said power switch, said resonant capacitance having a first resonant capacitor portion coupled in parallel with said resonant inductance and a second resonant capacitor portion coupled in parallel with said auxiliary switching device.

74. A power source as defined in claim 73 wherein said DC to DC converter is said boost converter.

75. A power source as defined in claim 73 wherein said DC to DC converter is driven by a power factor correcting control.

76. A power source as defined in claim 73 wherein said given duty cycle of said pulse-width-modulated control is greater than 80%.

77. A power source, as defined in claim 73 wherein said power switch comprises a main boost switch.

78. A three stage power source as defined in claim 73, wherein said pulse-width-modulated control is a phase shift pulse-width-modulated control.

80. A power source as defined in claim 74 wherein said DC to DC converter is driven by a power factor correcting control.

81. A power source as defined in claim 74 wherein said given duty cycle of said pulse-width-modulated control is greater than 80%.

82. A power source as defined in claim 75 wherein said given duty cycle of said pulse-width-modulated control is greater than 80%.

83. A three stage power source, as defined in claim 75 wherein said power switch comprises a main boost switch.

84. A power source as defined in claim 76 wherein said duty cycle is greater than 90%.

85. A power source as defined in claim 77 wherein said second resonant capacitor is coupled in parallel with said auxiliary switch by a forward poled diode.

86. A power source as defined in claim 77 wherein said second resonant capacitor portion is substantially less than ½

the capacitance of said first resonant capacitor portion.

90. A power source as defined in claim 80 wherein said given duty cycle of said pulse-width-modulated control is greater than 80%.

91. A power source as defined in claim 81 wherein said duty cycle is greater than 90%.

92. A power source as defined in claim 82 wherein said duty cycle is greater than 90%.

93. A power source as defined in claim 83 wherein said second resonant capacitor portion is coupled in parallel with said auxiliary switch by a forward poled diode.

94. A power source as defined in claim 83 wherein said second resonant capacitor portion is substantially less than ½

the capacitance of said first resonant capacitor portion.

95. A power source as defined in claim 85 wherein said second resonant capacitance is substantially less than ½

the capacitance of said first resonant capacitance.

97. A power source as defined in claim 90 wherein said duty cycle is greater than 90%.

98. A power source as defined in claim 93 wherein said second resonant capacitor portion is substantially less than ½

the capacitance of said first resonant capacitor portion.