US 7,586,766 B2
Plasma arc power supply and control method for same
Tetsuro Ikeda, Osaka (Japan); Masahiro Ohashi, Osaka (Japan); and Takayuki Nishisako, Osaka (Japan)
Assigned to Sansha Electric Manufacturing Co., Ltd., Osaka (Japan)
Filed on Dec. 12, 2007, as Appl. No. 11/955,151.
Claims priority of application No. 2006-338421 (JP), filed on Dec. 15, 2006.
Prior Publication US 2008/0143261 A1, Jun. 19, 2008
Int. Cl. H02M 7/00 (2006.01)
U.S. Cl. 363—65  [363/71; 363/74; 363/98; 363/142] 19 Claims
OG exemplary drawing
 
1. A plasma arc power supply comprising:
output setting means for specifying an output of a variable load current;
N (N≧2) direct-current power supply units that are feedback-controlled by a detection signal of a corresponding output current;
a relay circuit for outputting a relay signal for delaying a drive timing of (N−1) direct-current power supply units among said N direct-current power supply units; and
a signal distributor for distributing said load current and determining a current value generated by said N direct-current power supply units;
wherein
one direct-current power supply unit among said N direct-current power supply units outputs a pilot arc current;
only said one direct-current power supply unit continuously supplies a load current in a small-current region;
said relay circuit drives only said one direct-current power supply unit and increases the load current to a prescribed current value when a load current that exceeds the small-current region is specified by said output setting means; and
said relay circuit outputs a relay signal so that said (N−1) direct-current power supply units are driven, and said N direct-current power supply units generate a current on the basis of the current value determined by said signal distributor when the current value of said one direct-current power supply unit reaches said prescribed current value, resulting in a composite output of said N direct-current power supply units coinciding with said load current.