SSHI and Analog MPPT Integration-Based Self-Powered Interfacing Circuit for Piezoelectric Vibration Energy Harvester

This paper explores the utilization of vibration energy to power self-sustaining systems, addressing the limitations of traditional energy sources. We propose an enhanced interfacing circuit for a piezoelectric energy harvester by integrating Synchronous Switch Harvesting on Inductor (SSHI) and an adaptive Analog Maximum Power Point Tracker (MPPT) based self-powered system. Although the individual SSHI technique significantly enhances the maximum output power at the optimal load resistance, this enhancement can diminish for practical loads with low resistances. To overcome such limitations, we integrate the existing adaptive analog MPPT with the SSHI scheme followed by a voltage supervisor unit. This proposed integration approach enables the development of self-powered embedded systems with practical loads that offer low resistance. The proposed circuit is first simulated in LTSpice and then implemented in hardware. A PZT-based PPA-1014 piezoelectric element is interfaced with the proposed circuit, and the integrated system is characterized using an electrodynamic vibration shaker. For a typical sensor load of ADXL335 (10 k<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $</tex-math> </inline-formula>), the proposed integrated system demonstrates 2.19 times power enhancement and 49.6% enhancement in load duty cycle compared to the standard full bridge-based energy harvester while operating the accelerometer in self-powered mode. This energy harvester setup is then used to drive an ADXL335 accelerometer along with an MSP430 micro-controller in fully self-powered mode to measure and transmit structural vibrations. The system is further tested with real-time vibrations generated by a vehicle, successfully transmitting accelerometer data every 1.15 minutes via UART communication.