Unipoled Disk-type Piezoelectric Transformers

Abstract

Unipoled piezoelectric transformers with different input and output area ratios were fabricated. The electrical properties in terms of voltage step-up ratio, output power, efficiency, and temperature rise were measured at various load resistance. The voltage step-up ratio increased proportionally with load resistance. The relative efficiency showed a maximum value of more than 98% in the transformer, which is 23.6 mm in diameter and 1.0 mm in thickness with input/out electrode area ratio of 0.62. With the driving voltage of 35 V rms , the 8.1 W output power was obtained in the transformer with an input/output electrodes area ratio of 6.47. In such conditions, the temperature rise was only 15 C from room temperature. This transformer, which has approximately ten times higher power density than a rectangular Rosen-type piezoelectric transformer, was successfully applied to operate an 8 W compact fluorescent lamp.

Piezoelectric actuators 2006

“…NEC recently commercialized a multilayer rectangular type transformer in order to increase the voltage step-up ratio, using a third-order longitudinal mode, which is one method to release the stress concentration and to increase its lifetime of the original Rosen type [16]. Disk type transformers with an asymmetrical electrode pattern which have a much higher voltage step-up ratio than the rectangular type and disk multilayer types with a floating layer were proposed successively recently [17,18]. .…”

A lead-free piezoelectric transformer in radial vibration modes

“…[12][13][14][15] In this design, the input and output electrodes were on the same side of the piezoelectric ceramic disk and were isolated form each other by a fixed gap. The electrode pattern was a ring/dot structure, and the input and output sections were polarized along the thickness direction, such that the piezoelectric transformer used radial mode for input and output parts.…”

Applications of Lead-Free Piezoelectrics

“…By doping, PZT's piezoelectric properties have been enhanced in terms of loss and heat generation, and by design optimization piezoelectric transformers' power capability has also been increased. Power density is typically around 10~20 W/cm 3 , and the top data as high as 40 W/cm 3 has been reported by Laoratanakul et al [8].…”