• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.6
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• pp.1315-1320
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• 2012

In this study, piezoelectric AC-DC converter using ring-dot type multilayer piezoelectric transformer with no anisotropic of polarization was developed. Considering the characteristics of piezoelectric transformer which is very narrow operating frequency range, piezoelectric converter was designed with mixed structure of PFM driving method for feedback control of oscillation frequency and PWM driving method for output control. Maximum power and allowed current of the developed piezoelectric converter showing stable driving with minimum heat was 25W and 900mA, respectively. The output voltage of the piezoelectric converter was controlled by the driving oscillation frequency and showed stable and efficient operating characteristics at the maximum power.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.407-410
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• 2009

A piezoelectric device which converts mechanical vibration energy into electrical energy is able to harvest energy and the usable energy is mW ${\sim}$ W, hence a converter is necessary to acquire the energy efficiently. Various limited conditions should be considered for the design of AC/DC converter for energy harvesting of a piezoelectric device supplying small amount of energy. In addition to simple structure, compact size, light weight and high efficiency, the energy harvesting AC!DC converter should adopt the technique of self operating, in which only the harvested energy from the piezoelectric device is available. This paper proposes new AC/DC resonant boost converter to harvest efficiently electrical energy from mechanical vibration energy, analyzes the operating characteristics of the converter and proves its feasibility for energy harvester with PSPICE simulation and experiment.

• Journal of Power Electronics
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• v.5 no.4
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• pp.247-256
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• 2005

In order to harvest power in an efficient manner from a micro piezoelectric (PZT) device for charging the battery of a remote system, a new AC/DC resonant pulse power converter is proposed. The proposed power converter has two stages in the power conversion process. The first stage includes N-type MOSFET full bridge rectifier. The second stage includes a boost converter having an N-type MOSFET and a P-type MOSFET. MOSFETs work in the $1^{st}$ or $3^{rd}$ quadrant region. A small inductor for the boost converter is assigned in order to make the size of the power converter as small as possible, which makes the on-interval of the MOSFET switch of the boost converter ultimately short. Due to this short on-interval, the parasitic junction capacitances of MOSFETs affect the performance of the power converter system. In this paper, the performance of the new converter is analytically and experimentally evaluated with consideration of the parasitic capacitance of switching devices.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.6 s.183
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• pp.64-71
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• 2006

A target of this paper is to study on the usefulness of the adaptive piezoelectric energy harvesting device as a wireless electrical power supply when it is driven by mechanical vibrations of low frequency. For this purpose, an adaptive control technique and a step-down converter are used. A THUNDER series a piezoelectric material (TH7-R), which has been developed by a NASA engineer is selected for this study. In order to provide a mechanical energy to the piezoelectric material, a mechanical motion vibrator is designed. The adaptive controller is implemented using a dSPACE DS1104 controller board. The do-dc converter with an adaptive control technique harvests energy at over five times the rate of direct charging without a converter.

• Journal of Power Electronics
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• v.14 no.1
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• pp.183-193
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• 2014

Due to the requirements for high reliability and accuracy, safety issues for airbag ignition systems need to be studied. In this paper, a high-voltage piezoelectric converter is designed to improve these requirements in airbag ignition systems. The proposed converter includes an inverter drive circuit, a Rosen piezoelectric transformer (PZT), an output circuit and a feedback control circuit. The key components of the high-voltage piezoelectric transformer are analyzed in detail. In addition, the proposed converter system is simulated and implemented for testing. The experimental results show that when the power supply is turned on, the charging time is less than 800ms. Furthermore, the output voltage of this converter can be kept between 2.9kV and 3.1kV, under high-efficiency constant current charging mode and zero-voltage switching conditions.

• 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.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.6
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• pp.488-495
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• 2009

This paper proposes a new AC/DC RPPB(Resonant Piezo-Powered Boost) converter for energy harvesting using a piezoelectric device which converts mechanical vibration energy to electrical energy. The AC/DC RPPB converter can operate with only the harvested energy without an additional power conversion circuit for switching circuit and transfer energy to a load of which the voltage is higher than piezoelectric voltage. With the review of published topologies of the converter for energy harvesting, the operation principle of the AC/DC RPPB converter, and the results of PSPICE simulation and experiment are presented to prove the feasibility of the new converter for the energy harvesting.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.5
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• pp.343-354
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• 2009

In this paper, a magnetic-less dc-dc switching converter realizing an integrable power conversion system is described. Instead of magnetic devices, the inductive impedance range of piezoelectric transducers is utilized to store and resonate the energy for soft-switching. Piezoelectric devices have no windings and deliver the power by the electrodes, which lead to mass product through semiconductor-manufacturing process. This paper presents a resonant-type step-up dc-dc power converter employing a disk-type piezoelectric transducer, analyzing the operation principles and the frequency control characteristics. Also, a topology extension of the single stage converter into cascaded multi-stage is presented and analyzed with the operation principles and control characteristics. For verification of the analysis, a 10W output dc-dc power converter hardware was implemented. The hardware experiments shows a good frequency control and power efficiency greater than 96% in the single stage. A hardware prototype of the extended multi-stage one was also realized and tested. The results shows that the converter has the same frequency control performance and high efficiency such as 93%.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.2
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• pp.171-177
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• 2004

Piezoelectric transformer(PZT) can be used advantageously in high output voltage power supply. Recently, it also can be used in AC/DC Converter for miniaturizing size nd lightening weight. The modeling of PZT was performed by the calculation method through the physical and electrical constants of the material. The attributes of PZT were derived by an approximate analysis for output voltage gain, and resonant frequency. The proposed method is verified by computer simulation and experiment.

• The Journal of the Acoustical Society of Korea
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• v.21 no.7
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• pp.600-605
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• 2002

In this paper, a Negative Impedance Converter (NIC) circuit was employed for the electro-mechanical characteristic control of a thickness mode piezoelectric vibrator. Two circular plane piezoelectric vibrators were bonded together and the NIC circuit was connected to one of the vibrators. The theoretical and experimental analysis of the characteristics shown that the quality factor and the electro-acoustic efficiency of the vibrator with the NIC circuit could be improved by 20 times and 2.5 times, respectively.