Optimal design of PZT-based piezoelectric energy harvesting module for availability

In the context of reliability and maintainability, availability is either the probability that a system performs a required function at a specified time or within a required period or the ratio of the spent time against a period. Hence, availability is roughly similar to the operation ratio. The availability of a facility is directly related to costs when designing a large-scale facility, such as a nuclear power or manufacturing plant. A renewable energy system must also consider availability to produce a large quantity of electricity sustainably. This study designed a piezoelectric energy harvesting module that is integrated with a large quantity of PZT material and circuits in consideration of availability. Each component is prone to failure because the piezoelectric effect converts vibrated mechanical energy into electrical energy, and this can seriously degrade the performance of the entire module or cause total failure. Thus, availability needs to be considered at the conceptual design stage. In this study, we analyzed each component's possible failure modes and calculated reliability based on the failure modes to evaluate the availability of the module. We examined the characteristics of availability, which could be changed by the different series and parallel combinations of the PZT material from which energy was extracted. We designed optimal combinations of series and parallel circuit configurations to secure the required availability and proposed the maintenance cycle of the piezoelectric energy harvesting module.