Merged Switched-Capacitor Piezoelectric-Resonator Based DC-DC Converter with High Voltage Conversion Ratio

Piezoelectric devices have recently emerged as a promising candidate to replace magnetic components. Past research has explored different topologies and control strategies for dc-dc converters which only use a single piezoelectric resonator as the main energy-storage component. However, such converters exhibit relatively low efficiency when the voltage conversion ratio deviates from its nominal value. In this paper, a new merged switched-capacitor piezoelectric-resonator based dc-dc converter which can achieve high and flat efficiency across a wide voltage conversion ratio is proposed. The switched capacitor and the piezoelectric resonator are combined in the proposed converter to form a multi-level structure and controlled in a manner to achieve high efficiency across a wide voltage conversion ratio. The proposed topology and control strategy enable the switched capacitor to be soft-charged by the current from the piezoelectric resonator and achieve zero-voltage-switching (ZVS) for all its switches. The steady-state operation of the proposed converter is analyzed in detail. Simulation and experimental results are presented to verify the advantages of the proposed converter. Finally, a family of merged switched-capacitor piezoelectric-resonator based dc-dc converters, based on the proposed principle, is also presented.