| 摘要 |
In the field of HVDC power converters there is a need for an improved semiconductor switching circuit which obviates the difficulties associated with respective semiconductor switching elements exhibiting different performance characteristics and having inherent limitations in their performance. A semiconductor switching circuit (70; 80; 90) comprises a main current branch (74; 92) which includes at least one main semiconductor switching element (12) and through which current flows in a first direction (D1) when the or each main semiconductor switching element (12) is switched on. The semiconductor switching circuit (70; 80; 90) also includes an auxiliary current branch (76; 104) that is connected in parallel with the main current branch (74; 92). The auxiliary current branch (76; 104) includes at least one auxiliary semiconductor switching element (72) and the or each auxiliary semiconductor switching element (72) has a control unit (30) operatively connected therewith. The or each control unit (30) is configured to switch on the or each auxiliary semiconductor switching element (72) in the auxiliary current branch (76; 104) as the or each main semiconductor switching element (12) is switched on to selectively create an alternative current path (32; 108) via the auxiliary current branch (76; 104) whereby current flowing in the first direction (D1) through the main current branch (74; 92) is diverted instead to flow through the alternative current path (32; 108) to reduce the rate of change of current flowing through the or each main semiconductor switching element (12) immediately after the or each said main semiconductor switching element (12) is switched on. |
