A New Non -Isolated Low-Power Inductorless Piezoelectric DC-DC Converter

We present a new non-isolated low-power inductorless piezoelectric resonant converter. The piezoelectric material is used as an energy storage element like an inductance in a classical buck-boost power electronic converter. As opposed to most existing piezoelectric converters, the proposed topology enables to dynamically adjust the output power and ratio keeping a high efficiency for a large range of output powers and for a large range of conversion ratios taking advantage of piezoelectric high-quality factor and achieving zero-voltage switching. A theoretical analysis of the step-up converter using an energetic approach is introduced and enables a fast and reliable predesign of the piezoelectric component. This analysis is in perfect agreement with the simulation model performed on MATLAB/Simulink. For a given piezoelectric resonator both analytical and simulation models provide very high efficiencies for different output powers. The converter is tested experimentally with a 10 V input voltage using the piezoelectric radial resonance mode. An efficiency higher than 98% for a 160 mW power conversion is achieved, decreasing slowly to 78% at 1.4 W. For a large range of voltage gains, the efficiency remains higher than 90% up to an output power of 750 mW. The experimental results are in perfect agreement with the theoretical analysis until 500 mW.