Effects of Disc-Shaped Piezoelectric Size Reduction on Resonant Inductorless DC-DC Converter

Abstract

This paper studies the impact of disc-shaped piezoelectric resonator dimensions on a non-isolated inductorless piezoelectric DC-DC converter. An analytical model, linking geometrical parameters to output power and efficiency is introduced. This later reveals the benefits of reducing the thickness and diameter of the piezoelectric disk. Five piezoelectric discs with different dimensions are tested and compared in experimental works, giving very high efficiency up to 98 % and output power up to 1.7 W. An exceptional power density of 366 W.cm-3 was measured at 450 kHz for a 25-30 Volt conversion with an efficiency of 81%.

A New Topology of DC–DC Converter Based on Piezoelectric Resonator

“…Indeed, the region between the resonant (L-C) and anti-resonant frequencies (L-(C//CP)), is called inductive region. The internal current i is approximated by a sinusoidal current source thanks to the high quality factor of ceramic such as the case of the Lead Zirconate Titanate (PZT) t 0 [30], [31]. In the inductive region, the operating frequency moves and depends on the transmitted power.…”

“…11 shows the prototype used to validate the operating principle. The PR is selected in order to have a high quality factor (> 1000) and a high coupling factor (> 50 %) to minimize the losses [30], [31]. For this prototype, we have firstly chosen the radial mode vibration for operating at low frequency.…”

“…The thickness should be as small as possible, but it needs to ensure the insulation (assumed 1 kV/mm C-213) and to sustain the mechanical constraints. By taking into account these parameters, the material PZT C 213 from Fuji was chosen with a diameter of 25 mm obtaining a resonant frequency around 90 kHz and a thickness of 0.75 mm, because this material offers a high quality factor and high coupling factor [30], [31]. Fig.…”

“…The highest power density is obtained for the lower area (PR1) that corresponds to a power density of 176.8 W/cm 3 . Thus, Piezo-based DC-DC converters can be suitable for high power density applications [30], [31].…”