Broadband piezoelectric energy harvesting for vibration isolation systems based on multi-cantilever structures and hybrid S-SSHI and SECE interface circuits

Vibration isolation systems are commonly subjected to broadband and stochastic excitations. However, conventional piezoelectric energy harvesters achieve high efficiency only near resonance, which limits continuous energy harvesting. To address this issue, a broadband piezoelectric energy harvesting system integrating a multi-cantilever structure with a hybrid S-SSHI and SECE interface circuit is proposed. Three piezoelectric cantilevers with distinct resonant frequencies cover the target range of 10–30 Hz , enabling broadband energy conversion. The hybrid interface circuit combines voltage inversion and synchronous charge extraction to improve extraction efficiency and reduce load dependence. A multi-input strategy is further developed to independently process each piezoelectric branch under different phase conditions, thereby avoiding interference among input channels. A systematic circuit model is established to evaluate the effects of key component parameters, which are optimized using a differential evolution algorithm. Simulations and experiments demonstrate that the proposed system broadens the operating bandwidth and maintains high output power over 10 – 30 Hz . The proposed method provides an effective solution for broadband piezoelectric energy harvesting in practical vibration isolation applications.