The Environmental Stability Of The Step-down Multilayer Piezoelectric Transformer

Nowadays, the multilayer piezoelectric ceramic such as the filter,loudspeaker, transformer, transducer and ultrasonic motor, have been widelyused in the loudspeaker, transformer, transducer and ultrasonic motor. Energytransform can be realized by multilayer piezoelectric transformers (MPT).Two steps will be carried out during the energy transform. The first step isthat put a low voltage on the input terminal of the device. Based on theinverse piezoelectric effect, the voltage will be changed into the vibration.And then, according to the piezoelectric effect, there is a higher voltage on theoutput terminal. The voltage gain, output power and efficiency are threeimportant parameters to characterize the piezoelectric transformer. Accordingto the voltage gain, the piezoelectric transformer can be divided intopressurization type and step-down type. Transformer has several outstandingadvantages, such as light, small size, no electromagnetic interference and highefficiency. They can be applied in the fields of computer display, portableDVD, TV, automobile etc.At present, the study of step-down piezoelectric transformer is behind thestep-up piezoelectric transformer and there are no theories about the principleof step-down PT. In this paper, a piezoelectric transformer provided byWeiHua Corp was employed for evaluation of their basic electrical propertiesand the influence of the environment temperature in the basic electricalproperties. Specific including:(1) Based on non-contact method, thepiezoelectric constant, butterfly curve, and temperature characters are tested.Experiments show that non-contact method is more accurate for d33testing.(2) The electrical characteristics of MPT were also investigated. The inputvoltage was supplied by XD22A Low Frequency Single Generator, andmagnified by power amplifier. Two digital oscillographs were set up tomeasure the input and output voltage, current and their phase difference.(3) The Impedance Analyzer HP4194A with thermostat was applied to measuresome static electrics parameters of MPT at various temperatures, such asresonance frequency, anti-resonance frequency, admittance etc.(4) Thestep-down piezoelectric transformer was employed for evaluation of theinfluence of the environment temperature in the basic electrical properties.The results show that the environmental stability of the step-downmultilayer piezoelectric transformer is good, but dramatically changers ofenvironment in a long time will have impact on the performance, and highenvironment temperature also affects the use of performance seriously.