Feedforward control of pantograph contact force based on phase-locked loop (Phase-locked loop for control force generation)

Abstract

This paper proposes a feedforward controller for active suppression of contact force fluctuation between a pantograph and overhead contact line of a high-speed railway vehicle, assuming the use of a pneumatic actuator with low response speed. The proposed controller, designed to exploit the periodicity of the disturbance as a priori knowledge, consists of a phase-locked-loop-based synchronized harmonic generator and adaptive compensators to extract the periodic structure of the disturbance and to generate the appropriate input for disturbance cancellation. The synchronization condition of the phase-locked loop is clarified through a theoretical study, and a design of the controller that can cancel the sinusoidal disturbance with the frequency from 1 Hz to 10 Hz is presented. Numerical studies are carried out to examine the validity of the theoretical study and the performance of the controller. Experimental studies using an actual pantograph equipment show that the proposed controller can suppress the contact force fluctuation to 10 % of that without control at the frequency from 1 Hz to 10 Hz.