Self-Powered Engine Temperature Measurement by Piezoelectric Stack Generators With Linear Compensation for Magnetic Stiffness

The strategy of linear compensation for nonlinear stiffness to flexibly adjust the degree of stiffness is widely applied in the field of vibration reduction but remains relatively uncommon in the domain of energy harvesting. This article explores the utilization of a piezoelectric stack energy harvester that compensates for nonlinear stiffness through linear stiffness [compensated-nonlinearity piezoelectric energy harvester (CPEH)], thereby effecting a broad-spectrum shift in the energy-harvesting frequency band. A two-degree-of-freedom theoretical model is formulated to anticipate the bandwidth shift phenomenon, subsequently validated using specific experimental data. The investigation delves into the influence of system parameters on the output performance of the CPEH, substantiating the impact of linear compensation on bandwidth translation. For instance, employing a linear stiffness of 0.33 N/mm to compensate for the 256-mT magnetic spring in the 4.8–9-Hz operating bandwidth shifts to 13.7–18.9 Hz. Through automotive application experiments, the feasibility of energy harvesting in practical scenarios has been validated, achieving a theoretical voltage of 4.87 V under idle low gear conditions. Additionally, temperature testing experiments have confirmed the potential for real-time power supply. A design guideline is presented for optimizing energy-harvesting performance through parameter analysis.