Inverter output rectifier circuit

Abstract

In a power source of a welding system, an inverter rectifier output circuit and method for reducing the blocking voltages across saturable reactors associated with a rectifier coupled to a transformer winding in the inverter rectifier output circuit during both turn-on and turn-off transitions of the rectifier. At least a portion of a reverse recovery current associated with the rectifier is blocked by allowing blocking voltages to build across associated saturable reactors during a transition phase of the rectifier. During a turn-off portion of the transition phase, the blocking voltages are reduced using a RC circuit, thereby suppressing a peak voltage associated with the rectifier. During a turn-on portion of the transition phase, the blocking voltages are reduced using another saturable reactor in series with a free-wheeling diode.

1 . An inverter rectifier output circuit, said circuit comprising:
 a secondary winding of a transformer, said secondary winding having a first node, a second node, and a center tap node;   a first saturable reactor connected to said first node;   a first rectifying diode connected in series with said first saturable reactor at an anode of said first rectifying diode;   a second saturable reactor connected to said second node;   a second rectifying diode connected in series with said second saturable reactor at an anode of said second rectifying diode;   a third saturable reactor connected to said center tap node;   a free-wheeling diode connected in series with said third saturable reactor at an anode of said free-wheeling diode;   a first series RC network connected between said anode of said first rectifying diode and said anode of said free-wheeling diode;   a second series RC network connected between said anode of said second rectifying diode and said anode of said free-wheeling diode;   a first output node defined by connected cathodes of said first rectifying diode, said second rectifying diode, and said free-wheeling diode; and   a second output node defined by said center tap node.   
     
     
         2 . The circuit of  claim 1  further comprising at least one primary winding of said transformer capable of coupling energy to said secondary winding. 
     
     
         3 . The circuit of  claim 1  further comprising an output filter circuit connected between said first output node and said second output node. 
     
     
         4 . The circuit of  claim 3  wherein said output filter circuit includes an inductor connected in series with a capacitor. 
     
     
         5 . The circuit of  claim 4  wherein said capacitor is capable of having a load device connected in parallel therewith, said capacitor providing energy storage and ripple reduction of an output voltage. 
     
     
         6 . An inverter rectifier output circuit, said circuit comprising:
 means for transforming an alternating energy from a primary side of said circuit to a secondary side of said circuit;   means for rectifying said alternating energy on said secondary side of said circuit;   means for reducing a reverse recovery current of said means for rectifying during a transition phase of said inverter rectifier output circuit;   means for reducing a blocking voltage across said means for reducing a reverse recovery current during a turn-off portion of said transition phase; and   means for reducing said blocking voltage across said means for reducing a reverse recovery current during a turn-on portion of said transition phase.   
     
     
         7 . The circuit of  claim 6  further comprising means for filtering an output voltage produced by said circuit. 
     
     
         8 . The circuit of  claim 7  wherein said means for filtering includes an inductor connected in series with a capacitor. 
     
     
         9 . The circuit of  claim 8  wherein said capacitor is capable of having a load device connected in parallel therewith, said capacitor providing energy storage and ripple reduction of said output voltage. 
     
     
         10 . The circuit of  claim 6  wherein said means for transforming includes a transformer having a primary winding and a secondary winding. 
     
     
         11 . The circuit of  claim 6  wherein said means for rectifying includes a plurality of rectifying diodes. 
     
     
         12 . The circuit of  claim 6  wherein said means for reducing a reverse recovery current includes at least one saturable reactor. 
     
     
         13 . The circuit of  claim 6  wherein said means for reducing a blocking voltage during a turn-off portion includes a series coupled resistor and capacitor. 
     
     
         14 . The circuit of  claim 6  wherein said means for reducing a blocking voltage during a turn-on portion includes a series coupled saturable reactor and free-wheeling diode. 
     
     
         15 . A method of reducing the blocking voltages across saturable reactors associated with a rectifier coupled to a transformer winding in an inverter rectifier output circuit during both turn-on and turn-off transitions of the rectifier, said method comprising:
 reducing at least a portion of a reverse recovery current associated with said rectifier by allowing blocking voltages to build across associated saturable reactors of said inverter rectifier output circuit during a transition phase of said rectifier;   reducing said blocking voltages across said saturable reactors during a turn-off portion of said transition phase with a RC circuit, thereby suppressing a peak voltage associated with said rectifier; and   reducing said blocking voltages across said saturable reactors during a turn-on portion of said transition phase with another saturable reactor in series with a free-wheeling diode.   
     
     
         16 . The method of  claim 15  wherein said RC circuit includes a series coupled resistor and capacitor. 
     
     
         17 . The method of  claim 15  wherein said rectifier includes a plurality of rectifying diodes. 
     
     
         18 . The method of  claim 15  further comprising filtering an output voltage produced by said inverter rectifier output circuit. 
     
     
         19 . The method of  claim 18  wherein said filtering is accomplished using an inductor connected in series with a capacitor. 
     
     
         20 . The method of  claim 19  wherein said capacitor is capable of having a load device connected in parallel therewith, said capacitor providing energy storage and ripple reduction of said output voltage. 
     
     
         21 . A welding system comprising a power source, said power source including an inverter rectifier output circuit including:
 means for transforming an alternating energy from a primary side of said circuit to a secondary side of said circuit;   means for rectifying said alternating energy on said secondary side of said circuit;   means for reducing a reverse recovery current of said means for rectifying during a transition phase of said inverter rectifier output circuit;   means for reducing a blocking voltage across said means for reducing a reverse recovery current during a turn-off portion of said transition phase; and   means for reducing said blocking voltage across said means for reducing a reverse recovery current during a turn-on portion of said transition phase.   
     
     
         22 . The welding system of  claim 21  wherein said circuit further includes means for filtering an output voltage produced by said circuit. 
     
     
         23 . The welding system of  claim 22  wherein said means for filtering includes an inductor connected in series with a capacitor. 
     
     
         24 . The welding system of  claim 23  wherein said capacitor is capable of having a load device connected in parallel therewith, said capacitor providing energy storage and ripple reduction of said output voltage. 
     
     
         25 . The welding system of  claim 21  wherein said means for transforming includes a transformer having a primary winding and a secondary winding. 
     
     
         26 . The welding system of  claim 21  wherein said means for rectifying includes a plurality of rectifying diodes. 
     
     
         27 . The welding system of  claim 21  wherein said means for reducing a reverse recovery current includes at least one saturable reactor. 
     
     
         28 . The welding system of  claim 21  wherein said means for reducing a blocking voltage during a turn-off portion includes a series coupled resistor and capacitor. 
     
     
         29 . The welding system of  claim 21  wherein said means for reducing a blocking voltage during a turn-on portion includes a series coupled saturable reactor and free-wheeling diode.