Abstract: A DC-to-DC converter converts a DC input voltage to a DC output voltage by generating a primary AC voltage and transforming the primary AC voltage into a secondary AC voltage with a transformation ratio. The DC-to-DC converter has series resonance circuit for each AC voltage phase. When the ratio of the DC output voltage to the DC input direct voltage is greater than the transformation ratio, a phase shift between the primary alternating voltage and a series resonance circuit current corresponding to the primary alternating voltage is controlled to zero by changing a clocking frequency clocking the AC voltages. Conversely, when the ratio of the DC output voltage to the DC input voltage is less than the transformation ratio, the phase shift between the secondary AC voltage and a series resonance circuit current corresponding to the secondary AC voltage is controlled to zero by changing a clocking frequency.

Abstract: A resonant DC-DC converter includes an inverter circuit, a rectifier circuit and a transformer unit. The inverter circuit is connected to a first terminal of the transformer unit, and the rectifier circuit is connected to a second terminal of the transformer unit. The first and second terminals are galvanically isolated from one another by a first transformer. The transformer unit is configured to adapt a transformation ratio of the transformer unit. The transformer unit has an energy transmission path which includes an inverter and a second transformer, with an input of the energy transmission path being arranged parallel to a primary side of the first transformer and an output of the energy transmission path being arranged in series with the secondary side of the first transformer.

Abstract: A DC-to-DC converter converts a DC input voltage to a DC output voltage by generating a primary AC voltage and transforming the primary AC voltage into a secondary AC voltage with a transformation ratio. The DC-to-DC converter has series resonance circuit for each AC voltage phase. When the ratio of the DC output voltage to the DC input direct voltage is greater than the transformation ratio, a phase shift between the primary alternating voltage and a series resonance circuit current corresponding to the primary alternating voltage is controlled to zero by changing a clocking frequency clocking the AC voltages. Conversely, when the ratio of the DC output voltage to the DC input voltage is less than the transformation ratio, the phase shift between the secondary AC voltage and a series resonance circuit current corresponding to the secondary AC voltage is controlled to zero by changing a clocking frequency.

Abstract: An electric arc furnace (1) operated with alternating current has a converter (2) which converts mains voltage (U), into primary voltage (U?) having a furnace frequency (f?). A furnace transformer (4) transforms the primary voltage (U?) into a secondary voltage (U?), supplied to electrodes (6) in a furnace vessel (8) (1). They apply electric arcs (10) to a melt material (9) in the vessel (8). The secondary voltage (U?) is also supplied to a capacitor assembly (7) on the output side of the furnace transformer (4) and the furnace transformer (4) is connected on the output side. A control device (5) controls the converter (2) such that a primary voltage (U?) output from the converter (2) to the furnace transformer (4) has a furnace frequency (f) of least ten times the mains frequency (f) and/or greater than 1 kHz.

Abstract: A resonant DC-DC converter includes an inverter circuit, a rectifier circuit and a transformer unit. The inverter circuit is connected to a first terminal of the transformer unit, and the rectifier circuit is connected to a second terminal of the transformer unit. The first and second terminals are galvanically isolated from one another by a first transformer. The transformer unit is configured to adapt a transformation ratio of the transformer unit. The transformer unit has an energy transmission path which includes an inverter and a second transformer, with an input of the energy transmission path being arranged parallel to a primary side of the first transformer and an output of the energy transmission path being arranged in series with the secondary side of the first transformer.

Abstract: An apparatus for regulating an electric arc furnace connected to a power supply system with at least one system phase that applies an AC voltage to a furnace electrode and an arc current for melting. A control loop device includes an electrical converter designed for negative feedback of an amplitude and/or frequency of the AC voltage to produce an amplitude and/or frequency of the arc current. The converter includes an input port having a system power supply connected thereto, and an output port having a melting furnace power supply and a primary circuit of a first transformer connected thereto, wherein a secondary circuit of the first transformer is connected to the arc furnace electrode. A primary coil of a second transformer is connected in parallel with the converter input port, and a secondary coil of the first transformer is connected in series with a secondary coil of the second transformer.

Abstract: An electrical arrangement for an electric arc furnace (1) operated with alternating current has a converter (2) which converts mains voltage (U), having a mains frequency (f), of a supply grid (3) into primary voltage (U?) having a furnace frequency (f?). A furnace transformer (4) of the electrical arrangement transforms the primary voltage (U?) into a secondary voltage (U?). The secondary voltage (U?) is supplied to a number of electrodes (6) of the electric arc furnace (1). The electrodes (6) are arranged in a furnace vessel (8) of the electric arc furnace (1). They apply electric arcs (10) to a melt material (9) in the furnace vessel (8). The secondary voltage (U?) is also supplied to a capacitor assembly (7) which is on the output side of the furnace transformer (4) and to which the furnace transformer (4) is connected on the output side.

Abstract: A transformer including a coaxial transmission line and a series circuit of discrete stages of voltage sources arranged along a main axis of wave propagation. Electromagnetic waves are propagated along the coaxial transmission line in each stage and are coupled in the coaxial transmission line by pulse currents. Each stage has a coupling-in inductance formed by discrete inductances that generate the pulse currents. The discrete inductances are magnetically coupled to each other such that magnetic fluxes of the discrete inductances are superimposed on one another and added to one another along a circular line that is rotationally symmetrical to the main axis of wave propagation.

Abstract: An electric arc furnace has a safety device (3) connected to an earthed peripheral device. An earth cable (4) is provided to the peripheral device of the arc furnace (2). An ammeter (6) measures the current across the earth cable (4). A circuit breaker (8) in the earth cable (4) has a tripping time of less than 100 ms.

Abstract: The invention refers to a multilevel topology power converter (I) for electrical adaption of a low voltage alternating current (LVAC) of an electrical wind power generator (1) and a medium voltage (MV) transmission level for a transmission link to each other, the power converter (I) comprising for each phase: a switching unit (9) for adapting the low voltage (LV) and the medium voltage (MV) to each other, the switching unit (9) being controlled by a controller (15), whereby the controlled switching unit (9) separately switches n+1 terminal potentials along terminals of an electrical series of n>1 capacitors C1 . . . Cn (7); a current converter (5) for providing or using a direct current (DC) through the plurality of n>1 capacitors C1 . . . Cn (7) connected in series.

Abstract: An apparatus for regulating an electric arc furnace connected to a power supply system with at least one system phase that applies an AC voltage to a furnace electrode and an arc current for melting. A control loop device includes an electrical converter designed for negative feedback of an amplitude and/or frequency of the AC voltage to produce an amplitude and/or frequency of the arc current. The converter includes an input port having a system power supply connected thereto, and an output port having a melting furnace power supply and a primary circuit of a first transformer connected thereto, wherein a secondary circuit of the first transformer is connected to the arc furnace electrode. A primary coil of a second transformer is connected in parallel with the converter input port, and a secondary coil of the first transformer is connected in series with a secondary coil of the second transformer.

Abstract: A method for operating an electric arc furnace (10) which has at least one electrode (18) having a through-opening (32). An electric arc (20) is generated between the at least one electrode (18) and a material to be melted (16). A first additive is introduced into the through-opening (32) of the electrode (18) for causing an endothermic chemical reaction which is controlled such that the chemical reaction is caused in a predetermined region (34) of the at least one electrode (18), wherein the region faces the material to be melted (16).

Abstract: A transformer including a coaxial transmission line and a series circuit of discrete stages of voltage sources arranged along a main axis of wave propagation. Electromagnetic waves are propagated along the coaxial transmission line in each stage and are coupled in the coaxial transmission line by pulse currents. Each stage has a coupling-in inductance formed by discrete inductances that generate the pulse currents. The discrete inductances are magnetically coupled to each other such that magnetic fluxes of the discrete inductances are superimposed on one another and added to one another along a circular line that is rotationally symmetrical to the main axis of wave propagation.

Abstract: The present invention relates to an apparatus for generating high-voltage pulses, in particular by means of an inductive coltage adder (IVA), wherein an inner conductor (1) of a coaxial transmission line (21) is in the form of a body which is rotationally symmetrical to a main axis (HA) of wave propogation and passes through all stages, the outer radius of said body being formed so as to decrease in size continuously from the first to the last stage with a constant pitch.

Abstract: The invention refers to a multilevel topology power converter (I) for electrical adaption of a low voltage alternating current (LVAC) of an electrical wind power generator (1) and a medium voltage (MV) transmission level for a transmission link to each other, the power converter (I) comprising for each phase: a switching unit (9) for adapting the low voltage (LV) and the medium voltage (MV) to each other, the switching unit (9) being controlled by a controller (15), whereby the controlled switching unit (9) separately switches n+1 terminal potentials along terminals of an electrical series of n>1 capacitors C1 . . . Cn (7); a current converter (5) for providing or using a direct current (DC) through the plurality of n>1 capacitors C1 . . . Cn (7) connected in series.

Abstract: The invention relates to a Terminal (I) for electrical connection of an amount of electrical generators (1) to a high-voltage transmission network (3), the terminal (I) comprising connected in series in this order for each generator (1) assembly level (Li): a start AC/DC converter (5) for rectification of the generator voltage(s); a series resonant converter (7) for galvanic isolation between the generator (1) and the high-voltage; a converter unit (9) for providing the high-voltage.

Abstract: An apparatus and a method for generating high-voltage pulses using an inductive voltage adder, in which a first stage contains an electromagnetically coupling funnel-shaped intermediate piece positioned between a radial transmission line and a coaxial transmission line for transmitting electromagnetic waves from the radial transmission line into the coaxial transmission line.

Abstract: In a mixer circuit with a balanced frequency mixer with varactor diodes, a first input signal that exhibits a first input frequency can be fed to the frequency mixer via a first input. Furthermore, a second input signal that exhibits a second input frequency can be fed to the frequency mixer via a second input. The frequency mixer has at least two amplifier elements fashioned as varactor diodes. These amplifier elements mix the input signals with one another into a mix signal with a first signal component and a second signal component. The first signal component exhibits a first component frequency, the second signal component a second component frequency. The first component frequency is equal to the sum of the first and second input frequencies, the second component frequency is equal to the difference of the first and second input frequencies. An output signal that contains at least one of the signal components can be tapped via the output.

Abstract: A radio-frequency coil arrangement has a number of conductor traces forming basic coils and with capacitors interconnected in the conductor traces. Conductor traces of various basic coils intersect at node points. At least one switching arrangement for selective, reversible connection of the conductor traces to form different coil geometries is provided at least some of the node points.

Abstract: A magnetic resonance system that has a magnet system that generates magnetic fields in an excitation region, allowing nuclei in an examination subject in the excitation region to be excited to emit a magnetic resonance signal. A reception antenna device with multiple local coils for reception of the magnetic resonance signals is arranged in proximity to the examination subject, and has a base part and an attachment part. The attachment part can be placed on the base part such that the examination subject is located between the base part and the attachment part (6). The multiple local coils are respectively connected with an evaluation device for evaluation of magnetic resonance signals.