| 摘要 |
<p>The invention relates to a method for controlling a power converter for supplying direct current electric furnaces, employed especially for melting and fining/pig boiling the iron scrap, a method which provides/providing the location in the supplying circuit of an electric arc frunace (4) of at least one transformer (3) which supplied in the primary (9) with an alternating three-phase current delivers a three phase current on at least one of the secondary (10, 11) which is applied to some rectifying means (12) made up of controlled semiconductors (15, 16) supplying a voltage (Uarc) and a current (Iarc) on the load at the output which are rectified, some undirectional conductive means made up of some diodes (20) being associated to the rectifying means. According to the method, the trip/release of the controlled semiconductor is achieved by the generally variable ignition angles alpha 1 and alpha 2 allowing their change, for increasing the conduction period of the unidirectional conduction means (19) by a corresponding decrease of the conduction period of the controlled semiconductor (15, 16) and vice-versa, allowing thereby the generation on load of an practically constant active power (P) and/or reactive power (Q), in spite of load impedance variations.</p> |
