Active DC link filter for two frequency electric locomotives

By substituting passive components in electric traction vehicles for new circuit solutions based on power electronics, new possibilities to develop more effective vehicles are introduced. At single-phase line voltage the power is pulsating with twice the line frequency. This power pulsation is generally eliminated by a passive short-circuit link placed in the DC link of the traction drive. The paper presents a possibility to exchange the passive short-circuit link for an active filter. The active filter enables operation at both 16 2/3 Hz and 50 Hz supply frequency. This is especially attractive for two frequency locomotives. Principle rules of design and control as well as important parameters for the design of the active filter are described. Computer simulations verify the function