Enhancing the performance of electromagnetic damper cum energy harvester using microcontroller: Concept and experiment validation

An electromagnetic damper cum energy harvester (EMDEH), which consists of an electromagnetic damper (EMD) connected to an energy harvesting circuit (EHC), aims to suppress structural vibrations by harvesting the vibration energy of structures. Maintaining a steady equivalent resistance of an EHC is often desirable for achieving the target performance of vibration control and energy harvesting functions; however, it remains an unresolved challenge in the EHC design. This study proposes an improved version of EMDEH with a specially designed EHC, a buck–boost converter with a low-power microcontroller unit (MCU). Compared with the existing EMDEH using an EHC with a fixed duty cycle, the improved version employs the MCU to adjust the duty cycle based on the feed-forward signal so as to continuously maintain a nearly constant resistance characteristic of the EHC. The effectiveness of the proposed EHC was validated through numerical simulations and experimental tests. A prototype of the improved EMDEH was installed in a 135 m-long bridge stay cable and tested under harmonic excitations of different levels. An output power of 200 mW and a nearly constant resistance of the proposed EHC were observed in this full-scale experiment. The results of this study show how the use of a MCU in a feed-forward controlled EHC benefits the performance of a dual-function EMDEH with respect to its simultaneous vibration control and energy harvesting performance.