Patent EP-2234259-A1 (EP)
Inventor: WALLMEIER PETER
IPC: H02M5/22
Filed: 2010-03-05
Abstract: The circuit arrangement comprises first, second and third connectors (L1, L2, L3) for connecting with a three-phase voltage network, two outer ports (Z1, Z6) and three inner ports (Z2, Z3/Z4, Z5) for connecting silicon thin rods, two external transformers (T1, T4) and two internal transformers (T2, T3) having a primary coil and a secondary coil, two external power regulators, which are arranged for controlling the current to the external transformers through the primary coil, and two internal power regulators, which are arranged for controlling the current to the internal transformers. The circuit arrangement comprises first, second and third connectors (L1, L2, L3) for connecting with a three-phase voltage network, two outer ports (Z1, Z6) and three inner ports (Z2, Z3/Z4, Z5) for connecting silicon thin rods, two external transformers (T1, T4) and two internal transformers (T2, T3) having a primary coil and a secondary coil, two external power regulators, which are arranged for controlling the current to the external transformers through the primary coil, two internal power regulators, which are arranged for controlling the current to the internal transformers through the primary coil, units for controlling the power regulators, a first tap (T1.2.1) of the secondary coil connected to a first transformer of the both external transformers with a first port of the outer ports, a second tap (T1.2.2) of the secondary coil of the first external transformer connected with a first tap (T2.2.1) of the secondary coil of the first transformer of the both internal transformers and with a first port of the three inner ports, a second tap (T2.2.2) of the secondary coil of the first internal transformer connected with a first tap (T3.2.1) of the secondary coil of the second transformer of the both internal transformers and with a second port of the three inner ports, a second tap (T3.2.2) of the secondary coil of the second internal transformer connected with a first tap (T4.2.1) of the secondary coil of the second transformer of the both external transformers and with a third port of the three inner ports, and a second tap (T4.2.2) of the secondary coil of the second external transformer connected with a second port of the both outer ports. The primary coils of the external transformers are parallely connected and the parallel connection is connected with the first connector on one side and with the second connector on the other side for connecting with the three-phase voltage network. The primary coils of the internal transformers are parallely connected and the parallel connection is connected with the second connector on one side and with the third connector on the other side for connecting with the three-phase voltage network. The both outer ports are connected with one another by switching elements and connectable with mass. The circuit arrangement has a current detection means to detect the current through the primary coil of the transformers, and a voltage detection means to detect the voltage through the primary coil of the transformers. The current detection means and the voltage detection means are connected with the control units. The transformers are fitted and arranged for transforming a primary low voltage of 400 V into a secondary medium voltage of 6-8 kV, and have a transformation ratio of 15-20. The primary coils and the secondary coils of the transformers have same numbers of turns and are wound in the same sense. The control units are arranged for igniting the silicon thin rods connectable successively to the external power regulator to be switched with one of the outer ports and one of the inner ports. The control units are arranged for igniting the silicon thin rods connectable successively to the internal power regulator to be switched with two of the inner ports and one of the inner ports. The control units and the power regulators are arranged to regulate the current through the primary coils. The control units are arranged to the power regulators to be switched when the voltage over the primary coil reduces to half of a given amount during regulating the current through the primary coil. After switching the last power regulator, all the power regulators are simultaneously switched for implementing a reactor to adjust all the transformers to a same current with a given desired value at the primary coils. The control units are arranged to increase the desired value in a step-wise manner, to temporarily reduce all the desired values when the voltage over the primary coil of the transformers deviates around a the given amount of the voltages over the primary coils of the other transformers, and to switch all the power generators when the voltage over the primary coil of the transformers corresponds to the open-circuit operation of the transformer. Each power generator is arranged to the control unit and the arrangement has a superior control unit. The control unit is coupled with the power generators.