title: Effects of a parallel resistor on electrical characteristics of a piezoelectric transformer in open-circuit transient state.
abstract: This paper investigates electrical transient characteristics of a Rosen-type piezoelectric transformer (PT), including maximum voltages, time constants, energy losses and average powers, and their improvements immediately after turning OFF. A parallel resistor connected to both input terminals of the PT is needed to improve the transient characteristics. An equivalent circuit for the PT is first given. Then, an open-circuit voltage, involving a direct current (DC) component and an alternating current (AC) component, and its related energy losses are derived from the equivalent circuit with initial conditions. Moreover, an AC power control system, including a DC-to-AC resonant inverter, a control switch and electronic instruments, is constructed to determine the electrical characteristics of the OFF transient state. Furthermore, the effects of the parallel resistor on the transient characteristics at different parallel resistances are measured. The advantages of adding the parallel resistor also are discussed. From the measured results, the DC time constant is greatly decreased from 9 to 0.04 ms by a 10 k(omega) parallel resistance under open output.
authors.affiliation: Department of Electrical Engineering, National United University, Miaoli 36003, Taiwan, ROC. ktchang@nuu.edu.tw
authors.forename: Kuo-Tsai
authors.initials: KT
authors.lastname: Chang
mesh_terms: D000162:Acoustics / Q000295:instrumentation*; D003198:Computer Simulation; D017076:Computer-Aided Design; D017097:Electric Impedance; D004563:Electrochemistry / Q000295:instrumentation* / Q000379:methods; D004581:Electronics; D004735:Energy Transfer; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008839:Microelectrodes; D008962:Models, Theoretical; D014159:Transducers