Sensorless Displacement-Information-Recovery-Based Control for Piezoelectric Energy Harvesting With Adjustable Interfaces

The existing studies on adjustable-parameter interfaces (APIs) have demonstrated their effectiveness in enhancing the output power and bandwidth of piezoelectric energy harvesters (PEHs). However, current self-sensing approaches remain constrained by information-poor signals or reliance on external sensors, restricting multi-parameter interface applicability. Moreover, under sensorless conditions, the mutual modulation between the piezoelectric response and adjustment behavior fundamentally impedes the realization of automation. To overcome the challenge, we propose a sensorless control scheme that interprets the electrical signal characteristics of piezoelectric elements in real time to provide instantaneous feedback for dynamic adjustment of interfaces. Specifically, a displacement information recovery module is designed to recover the displacement-related information required for control from the energy-harvesting signal, while a periodic phase correction (PPC) technique is developed to resolve the mutual modulation between sensing and adjustment. On this basis, a large-step MPPT strategy is developed for the dual-parameter interface (energy extraction phase φ and voltage inversion ratio β), achieving rapid autonomous convergence. A prototype implementing the proposed method was fabricated and experimentally validated on two PEHs (PEH-1 and PEH-2). Experimental results show that both configurations successfully achieve sensorless fast auto-tuning, with 5.6-fold and 2.1-fold bandwidth improvements over traditional rectifiers for PEH-1 and PEH-2, respectively.