• Journal of Electrical Engineering and Technology
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• v.6 no.5
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• pp.671-676
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• 2011

A multilayer square-type piezoelectric transformer with a hole at the center was investigated in this paper. Temperature distribution at the center was improved by using this construction, therefore increasing input voltage and output power. This model was simulated and investigated successfully by applying a finite element method (FEM) in ATILA software. An optimized structure was then fabricated, examined, and compared to the simulation results. Electrical characteristics, including output voltage and output power, were measured at different load resistances. The temperature distribution was also monitored using an infrared camera. The piezoelectric transformer operated at first radial vibration mode and a frequency area of 70 kHz. The 16 W output power was achieved in a three-layer transformer with 96% efficiency and $20^{\circ}C$ temperature rise from room temperature under 115 V driving voltage, 100 ${\Omega}$ matching load, $28{\times}28{\times}1.8mm$ size, and 2 mm hole diameter. With these square-type multilayer piezoelectric transformers, the temperature was concentrated around the hole and lower than in piezoelectric transformers without a hole.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.7
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• pp.644-649
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• 2006

This paper presents a new disk-type piezoelectric transformer. The input side of the transformer has a crescent-shaped electrode and the output side has a focused poling direction. The piezoelectric transformers operated in each transformer's resonance vibration mode. The electrodes and poling directions on commercially available piezoelectric ceramic disks were designed so that the planar or shear mode coupling factor $(k_p\;k_{15})$ becomes effective rather than the transverse mode coupling factor $(k_{31})$. ANSYS finite element code was used to analyze transformer behavior and to optimize electrode and poling configurations. The voltage step-up ratio of the proposed transformer has been markedly improved in comparison with that of the equivalent rectangular(Rosen) type. A single layer prototype transformer, $20\sim30mm$ in diameter and $1.0\sim3.5mm$ thick, was fabricated, such as step-up ratio, power transformation efficiency, and temperature were measured. While the transformer was driving a Cold Cathode Fluorescent Lamp(CCFL), the temperature field of the transformer was also observed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.143-146
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• 2002

The characteristics of a multilayer piezoelectric transformer were investigated using 0.05Pb(A $l_{0.5}$N $b_{0.5}$) $O_3$-0.95Pb(Z $r_{0.52}$ $Ti_{0.48}$) $O_3$+0.9wt%N $b_2$ $O_{5}$+0.5wt%Mn $O_2$+0.04wt% $V_2$ $O_{5}$ ceramics. The multilayer piezoelectric trans formers were developed for voltage step-up. The multilayer ceramic technology was applied in piezoelectric transformer. The electrical characteristics of the piezoelectric transformer (33x8.5x1mm) has the efficiency of above 85%, step-up ratio of 70 under the 130 kΩ load, and driving frequency of 93.5kHz, respectively.ctively.y.y.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.630-633
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• 1999

This paper presents a new sort of multilayer piezoelectric ceramice transformer for switching regulatied power supplies. And this paper presents the study and development of a DC-DC converter with a transformer made from piezoelectric materials. This piezoelectric transformer operate, in the second thickness extensional vibration mode. Its resonant frequency is higher than 1MHz, This piezoelectric transformer was used the PbTiO$_3$ family ceramics because it was a material large anisotropy between electromechanical coupling factors k$_{t}$ and k$_{p}$. The input and output layer consists of two piezoelectric ceramic layer for eleivater of outpur power.wer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.855-860
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• 1998

This paper presents a new structure for a piezoelectric transformer, operating in thickness extensional vibration mode. Modified $PbTiO_3$ family ceramics were used for the piezoelectric transformer, because it was a material with large anisotropy between elecromechanical coupling factors $K_t$ and $K_p$ . The size of piezoelectric transformer was 20mn long, 20mm wide and 3.1mm thick. The second harmonic resonant frequency of thickness extensional vibration mode was 0.72MHz at loading resistance 100[$\omega$], And Voltage gin of piezoelectric ceramics showed 0.53 at resonant frequency of sencond thickness extensional vibration mode.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.11
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• pp.885-891
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• 2001

Ring/dot-type step-down piezoelectric transformer was manufactured by using Pb[(Mn$\sub$1/3/Sb$\sub$2/3)$\sub$0.05/Zr$\sub$0.475/Ti$\sub$0.475/]O$_3$ ceramics, which have excellent high-power piezoelectric properties. The characteristics of step-down piezoelectric transformer as a function of load resistance at output terminal was examined. Voltage gain was greatly dependent on drive frequency and load resistance, and showed maximum voltage gain at the resonance frequency. The output voltage was linearly increased as the input voltage increased. Voltage gain of the step-down piezoelectric transformer with respect to input voltage was very stable when the load resistance was in the range of 50-500 $\Omega$ .

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.389-392
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• 2001

In this paper, we have explained electrical characteristics of a step-down Rosen type piezoelectric transformer for AC-adapter. When the electric voltage is applied to the driving piezoelectric vibrator polarized in the longitudinal direction, then output voltage is generated at the generating piezoelectric vibrator polarized in the thickness direction due to the piezoelectric effects. Output voltage and current from a 11-layered and a 13-layered piezoelectric transformer were measured under the various conditions of loads and frequencies. We measured resonant frequency from impedance curve. It was shown from experiments that output voltage has increased and resonant frequency has changed according to various resistor loads. Output current has changed inversely proportional to resistances.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.367-370
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• 2004

This paper present a new disk-type piezoelectric transformer. The input side of the transformer has a crescent-shaped electrode and the output side has a focused poling direction. The piezoelectric transformers operated in each transformer's resonance vibration mode. The electrodes and poling directions on commercially available piezoelectric ceramic disks were designed so that the planar or shear mode coupling factor $(k_p,\;k_{15})$ becomes effective rather than the transverse meed coupling factor $(k_{31})$. A single layer prototype transformer, 26[m] in diameter and 2.0[mm] thickness, was fabricated, such as step-up ratio, power transformation efficiency and temperature were measured.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.621-625
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• 1999

Rosen type piezoelectric transformer for LCD backlight operated at high voltage and low current, may not be sucessfully used for illuminating general fluorescent lamps because low voltage and high current are required. In this study, the piezoelectric transformer with width vibration mode operated at low voyage and high current was designed for the application of fluorescent lasso ballast. The step-up ratio and efficiency as a function of the load resistance in the piezoelectric transformer indicated that the transformer can be effectively used for the electronic ballast for low profile fluorescent lamp.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.301-303
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• 2006

In this study, multilayer piezoelectric transformer were manufactured using the PZN-PMN-PZT ceramic and then the electrical characteristics were investigated. The voltage step-up ratio of multilayer piezoelectric transformer showed the maximum value in the vicinity of 78.16kHz and increased according to the increase of load resistance. When the output impedance coincided with the load resistance, piezoelectric transformer showed the temperature increase of about $20^{\circ}C$ at the output power of 12W. The results, the multilayer transformer manufactured using the low temperature sintered PZN-PMN-PZT ceramics can be stably driven for step-up transformers.