A control strategy for a low resonance frequency LCL (inductance-capacitance-inductance) filter used in the input stage of dc-dc bidirectional boost converters is proposed. When compared with the classical L filter, an LCL filter allows to obtain a cheaper topology. However, with an LCL topology, damping is needed for guaranteeing the system stability. In this paper an active damping strategy is designed. The needed damping is achieved via a dynamic controller. The controller consists of a simple PI (proportional-integral) controller plus a linear filter added in series with the PI integrator term. The modified PI controller achieves the active damping of the LCL filter and allows to arbitrarily place the system closed-loop poles. The proposed strategy only requires measurement of the variable to be controlled, the source current. Simulation and experimental results validate the proposed controller and show its effectiveness. (C) 2015 Elsevier Ltd. All rights reserved.