Verfahren zur Umsetzung von Gleichspannungen

摘要

Railway drives which are fed from an AC voltage network (1) or from a DC voltage network (2) at different voltages convert these feed voltages by means of two-quadrant converters (St1 - St4), which are operated as parallel-connected four-quadrant converters for an AC feed and as step-up or step-down converters for a DC feed, into an intermediate-circuit DC voltage (UD) which is as constant as possible. In order to reduce harmonics in the case of a DC feed, the two-quadrant converters (St1 - St4) can be connected via in each case one inductive impedance (L1 - L4) and switches (S8 - S11) to a positive pole (P) of a DC voltage intermediate circuit (11). The 2-quadrant converters (St1 - St4) are pulsed in a phase-shifted manner such that an 1-th two-quadrant converter is triggered or switched on (1/l) of a clock duration later than an (l - 1)th 2-quadrant converter. A ratio of the switched-duration or conducting duration to the pulse duration, that is to say a duty ratio beta of each of the l 2-quadrant converters is controlled to a value of beta = m/l, n = a number of converters >/= 2, 2