Piezoelectric energy harvester impedance matching using a piezoelectric transformer

•Piezoelectric Energy Harvester impedance matching is performed.•Piezoelectric transformer also lowers high piezoelectric energy harvester voltage.•Circuit generates no electromagnetic interference.•The impedance matching control is simple.•Piezoelectric transformer and harvester can be made on same substrate.

To harvest maximum power from a piezoelectric energy harvester requires conjugate impedance matching, consisting of both resistive and inductive load. In practical circuits, dc-dc converters working in discontinuous conduction mode are used for emulated resistive impedance matching. These converters contain a large and expensive electromagnetic component to reduce the wire conduction losses. A new approach toward piezoelectric energy harvester resistive impedance matching is presented by using a step-down piezoelectric transformer with a bi-directional inductor-less half-bridge circuit working under zero voltage switching conditions. The large and expensive magnetic transformer and inductor in previous works are replaced with a ceramic component with no electromagnetic interference. The presented technique can reduce the circuit size and the ceramic transformer can be manufactured on the harvester cantilever.

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