DRIVING WITH INVERTERS WITH LOW SWITCHING LOSSES

摘要

The invention relates to converters (inverters, pulse or frequency converters) and to the driving of “magnetically active” operating means. An effective switching frequency of the converter is not to be reduced, but nevertheless a reduction in cooling requirements is to be achieved A noise level produced in the operating means is to be kept low as well. The invention proposes, for this purpose, a circuit arrangement for feeding the operating means (electrically operated machine (M)) having at least one winding (L1, L2, L3), which circuit arrangement, in at least one first winding phase (S1), comprises a first branch (Z1) of a frequency converter (WR1) adapted for and operable at a switching frequency of not higher than 5 kHz for outputting a main alternating current generated at said switching frequency and having a substantially lower operating frequency (f₁) to a winding (L1). A second branch (z1) of another frequency converter (WR2) is adapted for and operable at a second switching frequency of more than 5 kHz for outputting a supplementary alternating current generated at said switching frequency to the same winding (L1). In the at least one winding (L1), the two alternating currents (i_A(t); i_B(t)) of the two branches (Z1, z1) are superimposed to form a sum current, namely during parallel operation of the first and second branches (Z1, z1) of the two non-identical inverters.