Abb Schweiz Ag

Hitachi Energy Ltd

Abb Power Grids Switzerland Ag

Dawei Yao

XiaoBo Yang

ChunMing Yuan

Guoxing Fan

Chao Yang

Sheng Zong

Francisco Canales

Bernt Bergdahl

Kuenfaat Yuen

Mats Andersson

Neil-QiNan Li

A voltage source converter (VSC) system of a high-voltage direct current (HVDC) system is disclosed. The system includes a number of line-commutated converter (LCC) transformers. Each LCC transformer is operable to transform alternate current (AC) voltage. A number of VSC converter units are connected in series and coupled to the plurality of LCC transformers. Each VSC converter unit is operable to convert between the AC voltage and direct current (DC) voltage. A bypass breaker is connected in parallel with at least one of the VSC converter units and operable to be closed to bypass the at least one VSC converter unit.

UHVDC converter transformer re-usage for LCC to VSC upgrade

An objective of the invention is to provide a bidirectional power valve for current occurring in a high voltage DC conductor, control method therefor, hybrid multi-terminal HVDC System using the same. The bidirectional power valve includes a first power diode arrangement of a first conducting direction, a second power diode arrangement of a second conducting direction; a mechanical disconnector, being connected with the second power diode arrangement in series; wherein: the first power diode arrangement and the series-connected second power diode arrangement and the mechanical disconnector are connected in parallel; and the first conducting direction of the first power diode arrangement and the second conducting direction of the second power diode arrangement are opposite to each other. The current commutation and re-commutation can be achieved with less requirement of the timing accuracy of switching event which makes the usage of a mechanical disconnector and power diode feasible. This will then result in a significant reduction of cost and power transfer losses.

Bidirectional power valve and control method therefor and hybrid multi-terminal HVDC system using the same

A DC to DC converter with intermediate conversion into AC power, including: a transformer having a primary winding and a secondary winding; a first DC to AC conversion circuit having its AC terminals coupled with the primary winding of the transformer; a first AC to DC conversion circuit having its AC terminals coupled across a first tap and a second tap of the secondary winding of the transformer; a second AC to DC conversion circuit having its AC terminals coupled across a third tap and a fourth tap of the secondary winding of the transformer, wherein the first tap and the second tap are arranged between the third tap and the fourth tap along the secondary winding of the transformer; and at least one first power switch, being arranged between one of DC terminals of the first AC to DC conversion circuit and one of DC terminals of the second AC to DC conversion circuit. By having the solution as above, the DC output voltage may be changed between two levels by operating only one power switch. Because a power switch is more expensive than a multiple of power diodes, by reducing the number of power switches responsible for changing the level of DC output voltage, it is helpful for decreasing the cost and complexity of control. Besides, the power loss can be decreased due to switching of less power switch.

DC to DC converter

The application relates to a DC to DC converter and control method thereof. The DC to DC converter includes a first converter circuit, a second converter circuit, a transformer having a primary winding and a secondary winding, a first resonant tank having a first capacitive element and a first inductive element, and a second resonant tank having a second capacitive element and a second inductive element. The first capacitive element and the first inductive element are coupled between the first converter circuit and the primary winding of the transformer; the second capacitive element and the second inductive element are coupled between the second converter circuit and the secondary winding of the transformer. During power transfer from the second converter circuit to the first converter circuit, a first plurality of first power-semiconductor-devices of the first converter circuit are operable to charge the first capacitive element during a first half cycle of a switching period; and a second plurality of the first power-semiconductor-devices of the first converter circuit are operable to provide an output voltage comprising an voltage across the primary winding of the transformer and the voltage of the first capacitive element superimposed thereon. This provides step-up gain for the backward direction, the first converter circuit operating in double voltage rectification manner and the second converter circuit working in the conventional full-bridge modulation with switching frequency fixed substantially at the resonant frequency.

DC-DC converter and control method

The invention relates to a bidirectional DC-DC converter with intermediate conversion into AC power, including: a DC-AC conversion circuit using a plurality of MOSFETs; an AC-DC conversion circuit using a plurality of power diodes; a transformer; a pair of switches, one of which being inserted in series between a DC terminal of the DC-AC conversion circuit and the AC-DC conversion circuit and the other of which being inserted in series between another DC terminal of the DC-AC conversion circuit and the AC-DC conversion circuit; and a controller being adapted for turning on the pair of switches such that the plurality of power diodes of the AC-DC conversion circuit are reverse-biased where the AC power is transferred in the forward direction and turning off the pair of switches where the AC power is transferred in the backward direction.

Bidirectional DC-DC converter and control method therefor

The application relates to a system for charging a battery of an electrical vehicle. The electrical vehicle charging system of the present application is helpful for decreasing the converter capacity while maintaining the charging capacity and electrical vehicles with various nominal voltages can be charged simultaneously. In one aspect the system for charging an electrical vehicle includes: a plurality of central converters, at least one switch electrically connected to the central converters, at least one transformer electrically connected to an external AC power supply, at least one distributed converter for supplying at least one distributed DC voltage with a level below that of the central converter, and a controller connected to the at least one switch.

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Beijing, China

Dawei Yao