• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2010년도 하계학술대회 논문집
• /
• pp.16-16
• /
• 2010

The multilayer piezoelectric transformer was manufactured using $Pb(Zn_{1/2}W_{1/2})O_3-Pb(Mn_{1/3}Nb_{2/3})O_3-Pb(Zr_{0.48}Ti_{0.52})O_3$ (abbreviated as PZW-PMN-PZT) ceramics and their electrical properties were investigated. The $k_{eff}$ of the input and the output calculated from the resonant and anti-resonant frequencies were 0.403 and 0.233, respectively. The voltage step-up ratio showed the maximum value in the vicinity of 81kHz. The multilayer piezoelectric transformer showed the temperature rise of about $36^{\circ}C$ at the output power of 12w.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2010년도 춘계학술회의 초록집
• /
• pp.1-1
• /
• 2010

In this study, electrical properties of multilayer piezoelectric transformer sintered at $900^{\circ}C$ using pure Ag internel electrode was investigated. This multilayer piezoelectric transformer was fabricated as a ring-dot type. The multilayer piezoelectric transformer should have hight electromechanical coupling factor ($k_p$) and electromechanical qualiy factor ($Q_m$) in order to increase the efficiency of energy conversion between electrical and mechanical energy. The maximum values of $k_p$ and $Q_m$ showed 0.552 and 1320, respectively.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2010년도 하계학술대회 논문집
• /
• pp.334-334
• /
• 2010

In order to fabricate the multilayer piezoelectric transformer by tape casting method, we investigated the effect of $TiO_2$ and PZT powder additions on the Ag/Pd electrode. Meanwhile, effects of $TiO_2$ and PZT powder additives on the microstructure and electrical properties of Ag/Pd electrode were investigated in detail. In addition, the multilayer piezoelectric transformers were fabricated and the characteristics with various load resistance were measured at resonance frequency. The voltage step-up ratio was continuously change with increasing input voltage and load resistance, and then output voltage and powers were increased with increasing input voltage at matching impedance. The temperature rise of multilayer piezoelectric transformers were increased with increasing input voltage and load resistance. Meanwhile, multilayer piezoelectric transformers sintered at $1100^{\circ}C$ show the favorable characteristics with a power of 15 W at $100\;{\Omega}$.

• 한국산학기술학회논문지
• /
• 제11권4호
• /
• pp.1229-1232
• /
• 2010

본 논문은 고효율 강압형 적층 압전변압기를 개발하기 위하여 저온소결 세라믹스 개발 및 적층 변압기를 제작하였다. 그리고 회로 요소로써 사용하는 PT는 인버터 설계의 일반적인 접근법을 보여주기 위한 것이다. 또한 압전기 영향의 기술(記述)은 다수의 연구에서 복잡한 방정식과 공식도 쉽게 찾을 수 있다. 특히 압전기 세라믹 EMT가 변화하지 않으며 PT기초 전기소자의 여러 가지 예는 더욱 효과적인 적층변압기의 적용이 가능할 것으로 판단된다.

• 한국전자통신학회논문지
• /
• 제7권6호
• /
• pp.1315-1320
• /
• 2012

본 연구에서는 분극의 이방성이 없는 ring-dot형 적층형 압전 변압기를 이용한 압전 AC-DC 컨버터를 개발하였다. 동작주파수 범위가 매우 좁은 압전 변압기의 특성을 고려하여 압전 컨버터는 발진주파수의 피드백 제어를 위한 PFM 구동방식과 출력제어를 위한 PWM 구동방식을 이용한 혼합형 구조로 설계되었다. 개발된 압전 컨버터의 최소 발열을 동반하는 안정적 구동을 보이는 최대전력 값은 25W였으며 허용전류 값은 약 900mA이었다. 압전 컨버터의 출력전압의 크기는 구동 발진주파수의 크기에 따라 제어가 가능하였으며, 최대전력에서 효율적이고 안정적인 동작특성을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 영호남학술대회 논문집
• /
• pp.70-73
• /
• 2000

This paper present a new sort of multilayer piezoelectric ceramic transformer for AC-adapter. This piezoelectric transformer operates in the second longitudinal vibration mode. The output voltage of the multilayer piezoelectric transformer was simulated using ANSYS, that is one of the FEM analysis program. As results, the minimum displacement was occurred at the two paints where one is the middle of input and the other is middle of output side in second thickness extensional vibration mode. And output voltage was inversely decreased by increasing number of output layers. 缀Ѐ㘰〻ሀ䝥湥牡氠瑥捨湯汯杹

• Journal of Power Electronics
• /
• 제3권2호
• /
• pp.139-144
• /
• 2003

In this paper, 11 and 13 layered step-down piezoelectric transformers were fabricated and their electrical characteristics have been analyzed for AC-adapter. When the voltage is applied to the driving piezoelectric vibrator polarized in the longitudinal direction, the output voltage is generated at the generating piezoelectric vibrator polarized in the thickness direction due to the piezoelectric effects. From the piezoelectric direct and converse effects, symbolic expressions between the electric inputs and outputs of the step-down piezoelectric transformer are derived with an equivalent circuit model. With those expressions, load and frequency characteristics are discussed through the simulations. Output voltage and current from a 11-layered and a 13-layered piezoelectric transformers were measured under the different load and frequency conditions. First we measured resonant frequency from impedance curve and got equivalent impedance value of the piezoelectric transformer from admittance plot. It was shown from experiments that output voltage increase s and resonant frequency changes according to the various resistor loads. Output current decreases inversely proportional to the change of loads. Moreover, the measured output voltage and current are well matched with the simulated results obtained from the proposed equivalent circuit model. Furthermore, a new step-down piezoelectric transformer has been suggested to Increase the output power based on a simulation result having a driving piezoelectric vibrator polarized thickness direction.

• E2M - 전기 전자와 첨단 소재
• /
• 제9권2호
• /
• pp.138-145
• /
• 1996

A multilayer piezoelectric transformer (MPT) which generates a high voltage dc power with low driving voltage and high voltage setup ratio was made by the tape casting method. The measured electrical characteristics of the MPT agreed with the results simulated from the equivalent circuit of the MPT. With increasing the number of layer in the MPT, the resonance curve of the input cur-rent revealed an asymmetry due to the increasing input capacitance, while that of output dc voltages revealed symmetry. The MPT which has very thin layer was excellently characterized as low driving voltage and high voltage setup ratio. The output dc voltage is nonlinearly influenced by the number of layer in the MPT.

• 한국전기전자재료학회논문지
• /
• 제14권11호
• /
• pp.898-903
• /
• 2001

In this study, we investigated amounts, distributions and sizes of pores of multilayer piezoelectric transformer, and predicted heat emission property and electrical characteristics according to designs of internal electrode. Forming densities of device having MLC, fingered and full filled internal electrode structure were 4.73 g/㎤, 4.80 g/㎤, 4.82 g/㎤ and forming porosities were 17.3737%, 13.1475%, 12.6121%, respectively. And sintered densities of MLC structured, fingered and full filled devices were 7.76 g/㎤, 7.75 g/㎤, 7.84 g/㎤ and sintered porosities were 4.0967%, 2.7132%, 2.5317%, respectively. Therefore, we concluded that fingered and full fi1led internal electrode devices, expecially, fingered internal electrode devices had cost-effective effect and maximum poling effect due to higher sintered density and lower porosity than MLC structured device. Also we can predict that they have an effect on good heat emission and high output properties of multilayer piezoelectric transformer.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
• /
• pp.821-825
• /
• 2004

In this paper, in order to develop the low temperature sintering ceramics for multilayer piezoelectric transformer, PMN-PZT ceramcis using $Li_2CO_3$ and $Bi_2O_3$ as sintering aids were manufactured, and their microstructural, dielectric and piezoelectric properties were investigated. The sintering aids were proved to lower the sintering temperature of piezoelectric ceramics due to the effect of $LiBiO_2$ liquid phase. At 0.1wt% $Li_2CO_3$ added specimen sintered at $970[^{\circ}C]$, electromechanical coupling factor(Kp), mechanical quality factor(Qm) and dielectric constant showed the optimum values of 0.50, 2,413 and 1,245, respectively, for multilayer piezoelectric transformer application.