TH17973A - Improved power conversion device for supplying DC power to electric arc furnaces. - Google Patents

Abstract

A power converter for supplying direct current to an electric arc furnace consists of At least one transformer whose primary winding is fed with three-phase alternating current and at least delivered. One secondary winding, three-phase current supplied to the rated output system, load the voltage and current arranged.The rating system consists of three semiconductors that are controlled for each secondary winding and Controlled semiconductor free wheel circuit is ignited with a significantly variable current commencement angle modified to increase the conduction time in the free wheel circuit while reducing the conduction time in the semiconductor. Ignited and reversed To deliver the most constant active and reactive power even with Variation in load impedance

Claims (5)

1. Control method of power converters for direct current to electric arc furnaces (4) The device is a type consisting of at least one transformer (9,10,11) whose primary winding (9) is fed. With three-phase alternating current and supplied to at least one secondary winding, the three-phase current That feeds the output rectifier path to load the voltage (V arc) and current (l arc) arranged, such rectifier path is composed of a free wheel circuit and is A type containing a semiconductor that is controlled for each secondary winding. Such a device has the following characteristics: The controlled semiconductor is ignited at an angle of conductivity. (Alpha 1, Alpha 2) variable with a key that was modified to increase the range. Time of navigation in the freewheel circuit While reducing the time of conduction in the slated semiconductor Correspondingly and vice versa to transmit the active power (P) and / or the reactive power. Constant even with variations in the load impedance 2. Method for controlling power converters according to claim 1, where the transformer includes at least The two most characteristic secondary coils (10, 11) are Each rectifier path fed by the curl Secondary such It was incorporated into an "offset" arrangement with an alpha 1 and alpha 2 conductivity control angle, respectively, with alpha 1 not equal to alpha 2. 3. The control method of the power converter according to claim 2, which is characterized by the such initiation control angle, alpha 1 and alpha 2 are selected for the given operating points. To make Consume the lowest reactive power Where the average throughout the operating cycle is also the least 4. The control method of the power converter according to claim 2, which is characterized by the starting control angle, alpha 1 and alpha 2 are selected for The ordered current (Id) to minimize the variation in the reactive power around its mean (Q), especially in the form of blinking. 5. The control method of the power converter according to claim 2 is characterized by providing a pathway for cyclic sequencing, offset of the alpha 1 and alpha control angles. 2 of the two rectifier pathways, respectively.