  Dynamical systems for kinetic energy harvesting have recently been designed
that use nonlinear mechanical resonators and corresponding transducers to
create electrical output. Nonlinearities are important for providing a
broadband input frequency efficiency, which is necessary to ensure that the
output voltage is at a satisfactory level in the case of a variable ambient
vibration source. In this paper, we analyze the dynamics of such a system with
the additional possibility of a switching potential barrier in the nonlinear
resonator. In order to improve the effectiveness of the energy harvester, we
numerically test the possibility of using abrupt changes in the system
parameters. We analyze the voltage output for various frequencies of both the
harmonic excitations and the potential barrier switching. In a range that
includes low and high switching frequencies of potentials, the periodic
solutions dominate in the bifurcation diagrams. With regard to the large
switching frequency, the effective values of the voltage at the piezoelectric
electrodes are significantly reduced. The highest effective values of the
voltage that are induced at the piezoelectric electrodes are observed when the
chaotic solutions appear due to their specific ability to pass the potential
barrier for relatively small excitation. The results also show that mechanical
damping with high-enough magnitudes minimize the influence of the transient
states caused by the switching potentials.
