Asea Brown Boveri Ag

Bbc Brown, Boveri & Company, Limited

Asea Brown Boveri Inc.

Peter Dahler

Osvin Gaupp

Gerhard O Linhofer

Jean-Francedillaois Ravot

Horst Gruning

Kadry Sadek

Herbert Stemmler

Michael Hausler

Christoph Tschudi

Peter Neidhart

A power converter circuit arrangement which comprises a first power converter and at least one further power converter is specified. The power converters are connected to the DC voltage intermediate circuit and feed a load circuit, in particular a single-phase railway grid. The or each further power converter has an output transformer on the load side. The secondary windings of the output transformers are connected in series with the primary winding of a load transformer, which feeds the load circuit, and the load-side terminals of a first power converter. This permits the turns ratios of the output transformers to be selected to be greater than or equal to one and said turns ratios between said output transformers to be selected to be gradated in a binary or ternary manner, for example. As a result, power converter stages having a gradated output voltage are available, and a finely stepped approximation to a sinusoidal output voltage can be achieved without the necessity of providing an uneconomically large number of stages.

Power breaker

An inverter having a plurality of inverter bridges which operate in parallel and whose output voltage is summed by way of a transformer. The transformer has a number of primary windings and associated secondary windings which correspond to the number of inverter bridges. Each inverter bridge is connected on the output side to a primary winding. The secondary windings are connected in series to sum the output voltages. The transformer has a center tap which is grounded by a ground connection. The suppression of in-phase or common-mode interference currents flowing by the ground connection and the interference voltages associated therewith is achieved by dividing the secondary windings into a first and second identical partial secondary winding. The partial secondary windings are connected to one another in the center tap in such a way that the common-mode currents and voltages induced in the partial secondary windings mutually cancel.

Invertor with reduced common mode voltage

An invertor (15) includes a plurality of invertor bridges (B1, . . . ,B8), which are connected in parallel and whose output voltages are summed via a transformer (19). The transformer (19) has a number of primary windings (P1, . . . ,P8) and associated secondary windings (S1, . . . ,S8) which corresponds to the number of invertor bridges (B1, . . . ,B8). Each invertor bridge (B1, . . . ,B8) is connected on the output side to one of the primary windings (P1, . . . ,P8), and the secondary windings (S1, . . . ,S8) are connected in series to sum the output voltages. The transformer (19) has a center tap (23) which is grounded via a ground connection (24). Tertiary windings (T1, . . . ,T8) are assigned to the primary windings (P1, . . . ,P8) and to the secondary windings (S1, . . . ,S8). The tertiary windings (T1, . . . ,T8) are also connected to a common-mode filter (51). The common-mode filter (51) is tuned to common mode interference voltages associated with in-phase or common-mode interference currents flowing via the ground connection (24). Thus, a circuit is formed that attenuates or suppresses the in-phase or common-mode interference currents and the associated interference voltages.

Invertor with suppression of interference currents

A power electronic circuit arrangement is specified, having a first power converter, which is connected to a first supply system, and a second power converter, which is connected to a second supply system. The first and second power converters are connected via a voltage intermediate circuit. According to the invention, a further filter is provided in addition to the so-called 33 Hz filter (supply-system filter) in the voltage intermediate circuit, which further filter serves to suppress the undesirable in-antiphase and in-phase current components flowing in the intermediate circuit. The additional filter can be realized either in split fashion, i.e. with two subfilters, in each case one for the in-antiphase current components and one for the in-phase current components, or in combined fashion with a common filter for both current components. The further filter, in combined or split fashion, fundamentally has a structure with a series circuit formed by a filter capacitor and a filter inductor, a filter resistor being connected in parallel with the filter inductor.

Power electronic circuit arrangement

A method and a device for correcting the DC offset of a converter are specified. The invention is defined in that the output voltage of the converter on the AC voltage side is fed to an essentially passive low-pass filter which reduces the output voltage to a level which can be processed electronically. Connected downstream of the low-pass filter is a controller which controls the DC offset essentially to zero by delaying the switching commands. The low-pass filter and the controller are arranged at a high-voltage potential.

Device for compensating the DC offset of a converter using a controller

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.

Common turn-off circuit for a thyristor power converter

A two-quadrant converter having a connected superconducting magnetic memory used as a chopper circuit or an actuator for stabilizing networks and for short-term bridging of power failures (e.g., uninterrupted power supply). For example, a two-quadrant converter is connected on the input side to an intermediate d.c. circuit of a converter whose intermediate circuit voltage is stabilized by an indirect capacitor. A magnetic memory is charged and discharged, respectively with energy in cyclic intervals, i.e. in conjunction with interposed free-wheeling intervals. Charging takes place via triggered thyristors, discharging via conducting diodes, with blocked thyristors. When the magnetic memory is in a charged state and is to be neither charged nor discharged over lengthy intervals, its current can be conducted in the free wheel via a closed mechanical switch connected in parallel.

Energy storage circuit with DC chopper superconducting reactor

To reduce unwanted current oscillations such as, for example, of the second harmonic of the system frequency (f.sub.o), the firing angles (.alpha.1, .alpha.2) of a link-circuit rectifier (1) and of a link-circuit inverter (2) are compensatingly acted on in push-pull mode. For this purpose, a direct-current link-circuit current signal (S5, S5'), which contains the instability or the current oscillation to be compensated, is fed by means of a current detector (5, 5') to a bandpass filter (16, 16', 16') which is tuned to the frequency (f.sub.o, f.sub.x) of the respective current oscillation. The phase of a bandpass filter output signal (S16) is shifted by 90.degree. trailing in a 90.degree. phase-shifting section (15, 15', 15'). A compensating signal (S15,S15', S15') obtained in this manner is fed to first and second function generators (13, 13', 13'; 14, 14', 14'). The first function generators allow the positive component (S13) to pass and the second function generators allow the negative component (S14) of the compensating signal to pass. The output signal of the first function generator passes via a switch (12') to a summing section (11') for forming the cosine of the firing angle (.alpha.2) of the link-circuit inverter (2). The output signal of the second function generator passes via a switch (12) to a summing section (11) for forming the cosine of the firing angle (.alpha.1) of the link-circuit rectifier (1). By these means, the firing angle (.alpha.2) of the link-circuit inverter (2) is reduced when the direct-current link-circuit current signal is dropping and the firing angle (.alpha.1) of the link-circuit rectifier (1) is increased when it is rising.

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Remigen, Switzerland

Peter Dahler