In the previous chapters, four commonly used transducers for converting mechanical energy to electrical energy are described, that is, piezoelectric, electrostatic, electromagnetic, and magnetostrictive transducers. In all cases, external mechanical energy is converted to electrical energy and is available at the output of the transducer for collection, conditioning, and delivery to the load. A collection and conditioning (CC) circuit is needed to ensure that the energy demands of the load are satisfied over the entire operating range. In case of sporadic availability of input mechanical energy, an intermediate storage capability may be needed to accumulate the energy to a suitable level.
In general, the complexity of the CC circuit is dependent both on the output energy and the voltage/current characteristics of the transducer, and on the energy demands of the load. All transducers considered here produce a time-varying voltage or current, but none are ideal sources; thus, CC circuits are required for each specific system configuration. The time-varying features of the transducer output can be separated into oscillatory, or pulsed periodic, or pulsed sporadic, or even a single pulse. In the latter cases, the peak pulse amplitude as well as duration need to be considered, while for oscillatory outputs, their temporal profile as well as their periodic features must also be considered.
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