| 摘要 |
An active filter ( 4 ) for compensation of variations in an apparatus' ( 3 ) current consumption from a power grid ( 1 ) as a cause of variations in the apparatus electrical load, through active frequency filtering and dynamic compensation of reactive energy/current. For each of the power grid's phases (a, b, c) the active filter includes a transistor bridge (Ta, Tb, Tc) connected between each phase and a DC-link ( 7 ). The active filter includes a filter circuit of LCL-type, arranged to reduce disturbances on the power grid caused by the active filter itself. The active filter further includes a control device ( 9 ) for calculating, with a given working frequency (f), points in time at which the transistor bridges are set to reverse the current direction through the DC-link, and the filter circuit is preferably adjusted to that working frequency.
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