TH43384A - High current welding power source - Google Patents

Abstract

DC60 (14/03/43) A welding power supply with a welding current in the form of a continuous pulse of current followed by a maximum current level and a closed state. The current pulse passes through a series circuit consisting of an inductor and an electrode in contact with the workpiece. The power supply consists of (a) an inverter section with inputs connected to the power supply, terminal one at the polarity condition when the inverter is turned on, terminal two at the polarity condition when the inverter is turned on, and a control for generating a signal to turn off the inverter and eliminate the current generated by the terminal to shift the current pulse to the closed state; and (b) a power switching section consisting of transistor switches with conditions for current flow from terminal one when the first logic signal is generated and a condition for not blocking the current flow when the second logic signal is generated. Improvements include a sensor for instantaneous measurement of the welding current, a comparator for generating a low current signal when the instantaneous current is below the selected value and the maximum current level, and a circuit or program for generating the second logic signal. While a low current signal is produced after the generation of the off signal, a transistor switch switches from a conducting condition to a non-conducting condition when the welding current is at the selected value. The welding power supply, with the welding current in a continuous pulse with a maximum current level and a subsequent off state, the current pulse passing through the series circuit consisting of an inductor and electrode in contact with the workpiece, has a power supply consisting of (a) an inverter section with inputs connected to the power supply, the first terminal in the step condition when the inverter is turned on, the second terminal in the polarity condition when the inverter is turned on, and a control signal is generated to turn off the inverter and eliminate the current generated by the steps to shift the current pulse to the off state; and (b) a power switching section consisting of transistor switches with a conducting condition allowing current flow from the first terminal when the first logic signal is generated, and a non-conducting condition allowing current flow when the second logic signal is generated. Improvements include a sensor for instantaneous measurement of the welding current. A comparator is used to generate a low-current signal when the instantaneous current is at a selected value below the maximum current level. A circuit or program is used to generate a second logic signal while the low-current signal is being produced after the off signal is generated. A transistor switch switches from a conducting condition to a non-conducting condition when the connecting current is at the selected value.

Claims (72)

1. In a welding power supply where the welding current is in the form of a continuous pulse of current with a maximum current level and a subsequent off state, the current pulse passes through a series circuit consisting of an inductor and electrodes in contact with the workpiece. The power supply has an inverter section with input connected to the power supply. The first terminal is at the first electrode state when the inverter is turned on. The second terminal is at the second electrode state when the inverter is turned on. The control generates a signal to turn off the inverter and eliminates current from the terminals, shifting the current pulse to the off state. A power switching section consists of transistor switches with conditions for current conduction from the first terminal during the generation of the first logic signal and a condition for blocking current conduction during the generation of the second logic signal. Improvements include a sensor for instantaneous measurement of the welding current, a comparator for generating a low current signal when the instantaneous current is below the selected value, and a circuit or program for generating the second logic signal during the low current signal generation after the off signal is generated. The transistor switches from... A condition that leads to a non-conducting condition when the connection current is at the selected value. 2. As per the improvements outlined in Claim 1, the power source will be a three-phase power source. 3. As an improvement as specified in claim 2, the inverter shall consist of a switching network controlled by a pulse width modulator operating at a frequency exceeding 18 kHz. 4. As per the improvements outlined in Claim 3, the current pulses will have a frequency of less than 400 Hz. 5. As an improvement to claim 1, the inverter shall consist of a switching network controlled by a pulse width modulator operating at a frequency exceeding 18 kHz. 6. In accordance with the improvements specified in Claim 5, the current pulses will have a frequency of less than 400 Hz. 7. In accordance with the improvements specified in Claim 1, the current pulses will have a frequency of less than 400 Hz. 8. The improvements specified in Claim 1 involve the inverting section, together with an output transformer, having a primary winding that receives high-frequency current pulses and a secondary winding that delivers current pulses to the terminals. 9. In accordance with the improvements specified in Claim 1, all current pulses shall have the specified polarity. 10. As per claim 1, the pulse continuity shall consist of alternating pulses between positive and negative current pulses. 11. As per the improvements outlined in Claim 10, the power source will be a three-phase power source. 12. As an improvement as specified in claim 10, the inverter shall consist of a switching network controlled by a pulse width modulator operating at a frequency exceeding 18 kHz. 13. In accordance with the improvements specified in Claim 12, the current pulses will have a frequency of less than 400 Hz. 14. In accordance with the improvements specified in Claim 10, the current pulses will have a frequency of less than 400 Hz. 15. The improvements as specified in Claim 10 will include methods for generating positive and negative pulses and methods for adjusting the pulse frequency. 16. In accordance with the improvements specified in Claim 15, the current pulses will have a frequency of less than 400 Hz. 17. The improvements as specified in Claim 10 will include a method for adjusting the relative timing between positive and negative current pulses. 18. The improvements as specified in claim 17 will include methods for generating positive and negative pulses and methods for adjusting the pulse frequency. 19. In accordance with the improvements specified in Claim 18, the current pulses will have a frequency of less than 400 Hz. 20. In accordance with the improvements specified in Claim 17, the current pulses will have a frequency of less than 400 Hz. 21. The improvements specified in Claim 10 will include methods for adjusting the amplitude of the positive and negative current pulses. 22. The improvements as specified in claim 21 will include a method for adjusting the relative timing between positive and negative current pulses. 23. In accordance with the improvements specified in Claim 22, the current pulses will have a frequency of less than 400 Hz. 24. As per the improvements specified in Claim 21, the current pulses will have a frequency of less than 400 Hz. 25. As per the improvements specified in Claim 1, the selected current will be less than 200 amperes. 26. As per the improvements specified in Claim 25, the selected current will be in the range of 100-150 Amperes. 27. As per the improvements specified in Claim 25, the power source will be a three-phase power source. 28. As an improvement as specified in claim 25, the inverter shall consist of a switching network controlled by a pulse width modulator operating at a frequency exceeding 18 kHz. 29. In accordance with the improvements specified in Claim 25, the current pulses will have a frequency of less than 400 Hz. 30. As per claim 25, the pulse continuity shall consist of alternating pulses between positive and negative current pulses. 31. In a welding power supply that generates a succession of positive and negative current pulses, an inverter is used. A positive current pulse passes through the rod segment of the first inductor and the electrode is in series with the workpiece, switching off the first transistor while the first command signal is received. A negative current pulse passes through the rod segment of the second inductor and the electrode, switching off the second transistor while the second command signal is received. Improvements would include a control device with a reversal method for use with the switching between the first and second command signals to reverse the polarity of the current pulses, and a reduction method for closing the inverter before the command signal is reversed. 32. The improvements specified in Claim 31 include a delay method that determines when the current pulse will drop to a selected current value and a method that triggers a reverse cycle when the current drops to the selected value. 33. As an improvement to claim 32, the inverter shall consist of a switching network controlled by a pulse width modulator operating at a frequency exceeding 18 kHz. 34. In accordance with the improvements specified in Claim 32, the current pulses will have a frequency of less than 400 Hz. 35. In accordance with the improvements specified in Claim 32, the selected current will be less than 200 amperes. 36. As per the improvements specified in Claim 35, the selected current will be in the range of 100-150 Amperes. 37. As an improvement as specified in claim 31, the inverter shall consist of an input connected to a multiphase power source. 38. As an improvement as specified in claim 31, the inductor segment shall be a single component of the inductor. 39. As an improvement to claim 31, the inverter shall consist of a switching network controlled by a pulse width modulator operating at a frequency exceeding 18 kHz. 40. In accordance with the improvements specified in Claim 39, the current pulses will have a frequency of less than 400 Hz. 41. As per the improvements specified in Claim 31, the current pulses will have a frequency of less than 400 Hz. 42. As per the improvements specified in Claim 31, the selected current will be less than 200 amperes. 43. As per the improvements specified in Claim 42, the selected current will be in the range of 100-150 Amperes. 44. As per claim 31, the reversal method would be a flip-flop circuit with logic Q as the first signal and logic Q as the second instruction signal. 45. The improvement specified in claim 44 involves a delay mechanism consisting of a logic network whose output is combined with one of the logic signals to disable the inverse from initiating the logic signal transmission. 46. The improvement specified in claim 31 involves a delay mechanism consisting of a logic network with the oscillator's output combined with one of the instruction signals, thereby preventing the inverse from initiating the transmission of such instruction signal. 47. As per claim 31, the delay method shall consist of instantaneous welding current detection and a reverse trigger method when the instantaneous current reaches a value of the chosen value. 48. A method for generating a welding current in the form of a series of current pulses with a maximum current level and a subsequent off state. The current pulses pass through a series circuit including an inductor and electrodes connected to the workpiece. A power supply with an inverter section with inputs connected to the power supply, terminal one at the first electrode state when the inverter is activated, terminal two at the second electrode state when the inverter is activated, and control of the inverter's off signal generation and current elimination from the terminals to shift the current pulses to the off state. A power switching section consisting of transistor switches with conditions of current conduction from terminal one when the first logic signal is generated and a condition of non-conducting current blocking when the second logic signal is generated. This method consists of (a) instantaneous measurement of the welding current, (b) generation of a low current signal when the instantaneous current is below the selected value and (c) generation of the second logic signal while the low current signal is generated after the off signal generation. The transistor switches from the conducting condition to the non-conducting condition. This method consists of (a) instantaneous measurement of the welding current, (b) generation of a low current signal when the instantaneous current is below the maximum current, and (c) generation of the second logic signal while the low current signal is generated after the off signal generation. The transistor switches from the conducting condition to the non-conducting condition. The connection is established when the welding current reaches the selected value. 49. In accordance with the method specified in claim 48, the power source shall be a three-phase power source. 50. As per claim 48, the inverter shall consist of a switching network controlled by a pulse width modulator operating at a frequency exceeding 18 kHz. 51. Under the method described in Claim 48, the current pulses shall have a frequency of less than 400 Hz. 52. In the method described in claim 48, the pulse continuity shall consist of the alternation of pulses between positive and negative current pulses. 53. The methods specified in Claim 48 shall consist of: 54. Under the method specified in Claim 48, the chosen current will be less than 200 amperes. 55. In the method specified in claim 54, the selected current will be in the range of 100-150 amperes. 56. Method for generating a succession of positive and negative current pulses. An inverter is used, with a positive current pulse passing through the rod segment of the first inductor and an electrode in series with the workpiece, switched off at the first transistor while the first command signal is received, and a negative current pulse passing through the rod segment of the second inductor and an electrode, switched off at the second transistor while the second command signal is received. This method consists of (a) switching between the first and second command signals to reverse the polarity of the current pulses, and (b) closing the inverter before switching the command signals. 57. The procedure described in claim 56 also includes (c) determining when the current pulse will drop to a pre-selected current value and (d) triggering a reverse action when the current drops to the pre-selected value. 58. High-current AC arc welding power supply located at the electrode and workpiece grounded. This power supply consists of an inductor used to convert the AC voltage to a DC current source with a maximum current of at least 200 amperes, with positive, negative, and ground terminals, and an output switching network including transistor switches in series with the positive terminal of the first inductor segment, electrode and workpiece grounded; a second transistor switch in series with the negative terminal of the second inductor segment, electrode and workpiece grounded; and a control method for switching the first switch on and the second switch off at the first switch reversal point, and switching the second switch on and the first switch off at the second switch reversal point. This generates a high AC welding current with positive and negative current pulses for the arc welding. The inductor has low inductance, and the method for closing the inductor while receiving the inductor shutdown signal, and the method for controlling the generation of the inductor shutdown signal before the reversal point, are all part of the power supply design. 59. The welding power supply as specified in claim 58 shall include a backsetting method when the selected current is below 200 amperes. 60. The welding power source as specified in Claim 59 shall have positive and negative current pulses with a frequency of less than 400 Hz. 61. The welding power supply as specified in claim 58 shall consist of a pulse width modulation switching network operating at a frequency exceeding 18 kHz. 62. The welding power source as specified in Claim 61 shall have positive and negative current pulses with a frequency less than 400 Hz. 63. The welding power supply as specified in claim 62 shall have a maximum inverse current exceeding 1000 amperes. 64. The welding power source as specified in Claim 61 shall have positive and negative current pulses with a frequency less than 400 Hz. 65. The welding power source as specified in Claim 58 shall have positive and negative current pulses with a frequency less than 400 Hz. 66. The welding power supply as specified in claim 65 shall have a maximum inverse current of more than 1000 amperes. 67. The welding power supply as specified in Claim 65 shall include a method for adjusting the pulse frequency. 68. The welding power supply as specified in claim 58 shall consist of a pulse frequency adjustment method. 69. The improvements as specified in claim 58 shall include methods for adjusting the relative timing between positive and negative current pulses. 70. The improvements as specified in claim 58 shall include methods for adjusting the relative timing between positive and negative current pulses. 71. As per claim 58, the inverter shall consist of inputs, which must be connected to a multiphase power source. 72. As an improvement to claim 58, the inductor segment shall be a single inductor segment.