摘要:
An arrangement to determine a cell capacitor voltage value of a cell of a multi-cell power converter includes the cell and a control unit. The cell itself includes four power electronic valves interconnected as a full-bridge converter having a first and a second phase leg, where each phase leg includes a series-connection of two of the four power electronic valves and where the connection point between the two power electronic valves of each phase leg is externally connectable, a cell capacitor being connected in parallel to the first and the second phase legs, and four gate units, each being connected to a corresponding one of the power electronic valves as well as to the control unit.
摘要:
The invention concerns a voltage source converter (26) comprising a group of phase legs, at least three connection terminals (AC1, AC2, AC3, DC+, DC−) for connecting the phase legs to power transmission elements, a first group of cells (C1p1, C2p1, C1n1, C2n1, C1p2, C2p2, C1n2, C2n2, C1p3, C2p3, C1n3, C2n3) in each phase leg and a second group of cells (C3p1, C3n1, C3p2, C3n2 C3p3, C3n3). The cells (C1p1, C2p1, C1n1, C2n1, C1p2, C2p2, C1n2, C2n2, C1p3, C2p3, C1n3, C2n3) in the first group are only capable of providing unipolar voltage contributions to the converter and connected for only being capable of such unipolar voltage contributions, while the cells (C3p1, C3n1, C3p2, C3n2 C3p3, C3n3) in the second group are connected to the corresponding cells of the first group and arranged to have bipolar voltage contribution capability.
摘要:
A DC-DC converter (200) comprising a first (201) and a second (202) variable voltage source, a capacitor (203), an alternating current filter (204), and controlling means (205), is provided. A first DC voltage (UDC1) is provided over a series-connection of the first and the second voltage source, and a second DC voltage (UDC2), being lower in magnitude than (UDC1), is provided over the second voltage source. The conversion between (UDC1) and (UDC2) is effected by circulating an alternating current within a circuit comprising the two voltage sources and the capacitor, thereby exchanging power between the two voltage sources. The alternating current is driven by AC voltage components provided by the first and the second voltage source. The controlling means is arranged for controlling the first and the second voltage source so as to maintain a phase difference between the AC components to be close to π.
摘要:
It is presented a high voltage DC/DC converter for converting between a first DC connection and a second DC connection. The high voltage DC/DC converter comprises: a first set of DC terminals; a second set of DC terminals); a multiphase transformer device comprising a plurality of primary windings and a corresponding plurality of secondary windings; a first converter arranged to convert DC to AC, comprising a plurality of phase legs serially connected between the first set of DC terminals, wherein each phase leg is connected to an AC connection of a respective primary winding; and a second converter arranged to convert AC from the secondary windings to DC on the second set of DC terminals.
摘要:
Power exchanging arrangement, in shunt connection, with a three-phase electric power network including on one hand for each said phase a reactive impedance element and a Voltage Source Converter connected in series with said element, and on the other hand a control unit configured to control semiconductor devices of turn-off type of said converter for generating a voltage with a fundamental frequency being equal to the fundamental frequency of the voltage of the respective said phase and by that control a flow of reactive power between said arrangement and the respective phase of said electric power network. Each Voltage Source Converter includes a series connection of switching cells in the form of so-called H-bridges including two switching elements connected in parallel and each having at least two semiconductor assemblies connected in series. Each switching cell further comprises at least one energy storing capacitor connected in parallel with said switching elements.
摘要:
An apparatus for converting direct voltage into alternating voltage and conversely comprises a VSC-converter (8) having a direct voltage intermediate link (9) and at least one phase leg (12, 13). Each current valve (14-17) of the phase legs has at least one semiconductor device of turn-off type and a rectifying member connected in anti-parallel therewith. A transformer (19) has two opposite ends of a first winding (20) thereof connected to an output (21, 22) each of the VSC-converter and a second winding (23) connected to a direct converter having at least one phase leg. Each of the current valves of the direct converter being able to conduct current and block voltage in both directions and to turn on by gate control. A midpoint (27) of the phase leg of the direct converter is provided with a phase output for forming a terminal for the alternating phase voltage between this output and a further phase output (28).