Modulation and Feed-Forward Based Damping Matching Strategy for Linear Generators

This article presents an active damping matching control strategy to optimize the output power of linear generators in energy harvesting applications. The method adjusts the magnitude of the current command responsible for active power set-point. The proposed approach combines a simple model-based feed-forward term with a slow but accurate correction based on the response of output power to a low-frequency modulation in set-point current magnitude. The correction is derived from the phase of output power oscillations and used to adjust the power set-point to achieve active-load matching conditions. In order to remove the low-frequency oscillations in the power at steady state, the method automatically stops the current amplitude modulation when maximum output power is reached. In addition, the proposed control incorporates an overstroke protection, which increases the active current component thereby reducing the stroke rapidly to a safe limit. The overall control principle is validated experimentally.