A better filtering effect for disturbing harmonic currents in a high-tension direct current transmission installation is described. A balancing winding is provided between a primary winding as an outer winding and a secondary winding in a 3-winding transformer with a transformer core. The distances between the balancing winding and the primary winding and the secondary winding, respectively, are selected such that the equivalent reactance of this balancing winding is equal to or less than zero. A second balancing winding can be provided as the inner winding in a series with the first balancing winding. In the case of a 4-winding transformer, two winding arrangements are provided with two parallel-connected primary windings as the outer windings, with a separate secondary winding for each and a balancing winding for each between the primary and secondary windings, the two balancing windings being connected in series.
A common turn-off circuit for a thyristor power converter is specified. The common turn-off circuit is particularly suitable for AC converters such as, for example, railway grid couplings. The turn-off thyristors are directly connected to the secondary transformer windings. Additionally provided is a special freewheeling path via which the energy stored, in particular, in the transformer inductors or other relevant inductors can be drawn away. What is advantageous is the fact that all of the thyristors of the power converter can be turned off reliably and without any special precautions, since the common turn-off circuit is automatically ready for turning off. Overvoltages are avoided, moreover, by the special freewheeling path.
An integrated magnetic filter inductor having series and common mode windings includes a magnetic core (44) having a first leg (46), a second leg (48), and a third leg (50). The first leg (46) is connected to the second leg (48) with bridging structures (52) and (54). In a similar manner, the third leg (50) is connected to the second leg (48) with bridging structures (56) and (58). A common mode winding (64) is wound about the bridging structure (52) with a given dot orientation. A common mode winding (66) is wound about the other bridging structure (54) with the same dot polarity. Current flowing into the dot terminal of the common mode winding (64) and out of the dot terminal of the common mode winding (66) result in a net zero magnetic flux induced in the magnetic structure (44). A common mode winding (68) is wound about the bridging structure (56) with a predetermined dot polarity. A common mode winding (70) is wound about the other bridging structure (58) with the same dot polarity. Therefore, when current flows into the dot end of one of the windings (68) and (70) and out of the dot end of the other winding, the net flux induced in the magnetic structure (44) is zero. A primary winding (62) is wound about the second leg and induces a flux into the magnetic structure (44).
A transformer with interference suppression includes a primary winding (1) with a first primary coil (27), one end of which is connected to a primary reference point (19), and also includes a second primary coil (39). The transformer has a secondary winding (3) with a secondary coil (33), one end of which is conductively connected to a secondary reference point (21). All of said coils (27, 39, 33) are solenoid coils which are concentrically arranged on a coil former (5) with intermediate electrical insulating means (29, 31; 29, 37) so that the first primary coil (27), across which the voltage drop amounts to U.sub.1p, is capacitively coupled to the secondary coil (33) across which the voltage drop amounts to U.sub.1s. The capacitance between these two coils has the value C.sub.1. The second primary coil (39), across which the voltage drop amounts to U.sub.2p, is capacitively coupled to a secondary coil (33) across which the voltage drop amounts to U.sub.2s. The capacitance between these two coils has the value C.sub.2. In order to prevent a disturbing voltage from occurring between the primary reference point (19) and the secondary reference point (21), the following condition is satisfied:
5666047 - Dielectric transformer - Owned by The United States of America as represented by the Secretary of the Navy (Washington, DC)
A dielectric power transformer comprises a tuning inductor having a nonmatic core connected in parallel with a capacitive voltage divider. The dielectric power transformer transforms the voltage of an alternating current power source connected across the inductor into a voltage across a load connected to the capacitive voltage divider. The dielectric power transformer has a resonant frequency substantially equal to the frequency of the power source.
A voltage sourced inverter system includes an inverter for coupling to a DC power source and an interphase transformer bank coupled to the inverter. The inverter includes a number of poles for providing discretely displaced voltage waveforms to the interphase transformer bank. A main transformer operably coupled to the interphase transformer bank transforms power therefrom into an AC power output. The interphase transformer bank may be a singular stage or a hierarchial arrangement of plural interphase transformers which combine the discretely displaced voltage waveforms to reduce selected harmonic components therefrom. The inverter may provide notched waveforms to remove additional selected harmonics from the discretely displaced voltage waveforms. A method of inverting DC power into AC power with reduced selected harmonic components is also disclosed.
