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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