ESP-SCEI circuit for PEH: Enhanced output power and high load-impedance independence

Abstract Piezoelectric energy harvesting (PEH) interface circuit serves as the core power supply solution for self-powered sensing devices operating under harsh conditions. However, existing technologies are confronted with prominent performance bottlenecks: the conventional synchronized electric charge extraction (SECE) circuit has limited potential for improving output power, while the parallel synchronized switch harvesting on inductor (P-SSHI) circuit suffers from poor load impedance adaptability. Neither of them can simultaneously achieve the dual performance goals of high output power and strong load impedance adaptability. To address the aforementioned technical issues, this paper proposes a high-efficiency self-powered synchronized charge extraction and inversion (ESP-SCEI) interface circuit for PEH. The circuit employs an optimally designed peak detection switch to effectively reduce energy loss, and innovatively introduces a voltage inversion mechanism analogous to that of the P-SSHI topology during the energy extraction phase of the SECE circuit. Unlike the conventional SECE circuit, which fully extracts the internal charge of the piezoelectric transducer (PZT) in a single energy extraction operation, the ESP-SCEI circuit only extracts a portion of the energy stored in the PZT during each operating cycle, with the remaining charge participating in the voltage inversion process. Notably, energy extraction and charge inversion are realized synchronously in this process. This design not only elevates the peak output voltage of the PZT but also achieves effective decoupling between the PZT and the load. Experimental results demonstrate that the ESP-SCEI circuit simultaneously exhibits the high peak output power characteristic of the P-SSHI circuit and the strong load independence characteristic of the SECE circuit. Furthermore, under the conditions of an open-circuit voltage ( V oc ) of 8 V and a resonant frequency of 23.4 Hz, its output power reaches 1.96 times as much as that of the SECE circuit, placing it at the forefront of state-of-the-art rectifier technologies.