Effects of introducing nonlinear components for a random excited hybrid energy harvester

Abstract

This work is mainly devoted to discussing the effects of introducing nonlinear components for a hybrid energy harvester under random excitation. For two different types of nonlinear hybrid energy harvesters subjected to random excitation, the analytical solutions of the mean output power, voltage and current are derived from Fokker–Planck (FP) equations. Monte Carlo simulation exhibits qualitative agreement with FP theory, showing that load values and excitation’s spectral density have an effect on the total mean output power, piezoelectric (PE) power and electromagnetic power. Nonlinear components affect output characteristics only when the PE capacitance of the hybrid energy harvester is non-negligible. Besides, it is also demonstrated that for this type of nonlinear hybrid energy harvesters under random excitation, introducing nonlinear components can improve output performances effectively.

Nonlinear Hybrid Piezoelectric and Electromagnetic Energy Harvesting Driven by Colored Excitation

“…Nevertheless, the effects of introducing nonlinear stiffness into a randomly excited hybrid PE and EM energy harvester on output characteristics could be quite different. Li et al [38] and Zhou et al [39] showed that a nonlinear hybrid energy harvester excited by white Gaussian noise could theoretically outperform its linear counterpart, which was validated by numerical and experimental methods, respectively. However, to the best of the authors' knowledge, there are no related studies for the response of a nonlinear hybrid piezoelectric-electromagnetic energy harvester when subjected to colored excitation, which represents a more realistic simulation of a practical vibration environment.…”

“…In order to generate a nonlinear hybrid PE and EM energy harvester, two permanent magnets are used, located symmetrically on the mass magnet (see Figure 1). Introducing magnets as nonlinear component into hybrid piezoelectric and electromagnetic energy harvester will produce a linear factor 1 k and nonlinear factor 3 k based on references [38][39][40][41][42], hence it becomes a nonlinear hybrid piezoelectric and electromagnetic energy harvester, and its governing equation can be obtained as follows:…”

“…Based on previous studies on both linear and nonlinear energy harvesters under random excitation [26,34,36,38,39], the inductance of coils is usually ignored in order to simplify the theoretical analysis. Hence Equation (2) can be expressed as:…”

“…Combining the basic assumption from our previous work [39] and extending the approximate analytical Fokker-Planck (FP) theory from Daqaq et al [32], which was concentrated on energy harvester with a single harvesting mechanism, the main contribution of this paper is to obtain the effects of introducing stiffness-type nonlinearity into a hybrid PE and EM energy harvester under colored excitation. Along with Monte Carlo (MC) simulation, the theoretical output characteristics of a nonlinear hybrid PE and EM energy harvester subjected to colored excitation are presented and compared.…”

“…Verification with numerical solutions, theoretical output performances for nonlinear and linear hybrid energy harvesters with the variation of load resistances, spectral density (SD), bandwidth and center frequency under colored excitation are presented in Section 4. In particular, for a case with colored excitation approaching white Gaussian excitation, theoretical results are discussed and compared with that from our previous Fokker-Planck expressions for a hybrid energy harvester under white noise excitation [39]. Concluding comments are then provided in Section 5.…”