Characteristics of piezoelectric ceramic transformer

A silver electrode of piezoelectric ceramics is applied to the upper and lower sides of the left half to be polarized in the thickness direction. When an alternating electric field is applied, the piezo ceramic sheet vibrates, and this portion is the driving portion. The silver electrode is applied to the end face of the right half and is polarized along the length. This part converts mechanical energy into electrical energy, which is called the power generation part. Using the piezoelectric ceramic's electrical energy→mechanical energy→secondary transformation of electrical energy, the highest boost output is obtained at the resonant frequency. They are specific working principle,When an alternating electric field of a certain frequency is applied to the driving part, mechanical deformation is caused by the inverse piezoelectric effect, thereby causing mechanical resonance and propagating along the length direction of the ceramic sheet.This kind of mechanical resonance through the positive piezoelectric effect causes a large amount of bound charge to accumulate on the end face of the power generation part of the pizoelectric ceramics cell sheet; the more is bound charge, the more space charge is attracted, so that a relatively high output is obtained at the end electrode of the power generation part.

Frequency characteristics: The output voltage of the piezoelectric ceramic transformer is related to the frequency. Whether it is half-mode or full-mode resonance, the output voltage of the transformer reaches the maximum value only near the resonant frequency; if it deviates from the resonant frequency, the voltage drop is very large. Big. Unlike a wound transformer, it does not work over a wide frequency range.

Output voltage and input voltage

  The output voltage of piezo discs piezoceramic transducer increases as the input voltage increases, but when the input voltage reaches a certain value, the output voltage tends to saturate. This may be due to the nonlinearity of the piezoelectric ceramic and the increasing in material loss due to an increase of the input voltage.

Output voltage and load impedance

The characteristic curve shows that as the transformer of load impedance decreases, the output voltage also decreases. Due to the large input impedance of the piezoelectric ceramic transformer (about ten mega ohms to several tens of mega ohms). Therefore, in a high-voltage source of using a piezoelectric ceramic transformer to boost, when the load changes, the output voltage of 200kHz peizoelectric discs changes greatly, and compensation measures must be taken.

Output power, conversion efficiency and load impedance

 The output power and conversion efficiency have a larger value area as the load impedance changes. When the piezio ceramic disc transformer performs secondary electromechanical energy conversion along with various losses, the heat of the component itself during resonance is one of them. Due to the heat, the efficiency of the transformer is significantly reduced. In addition, some studies have proved that the reasonable matching of the load impedance and the proper selection of the rectifier mode. the output part of the piezoelectric ceramic transformer can effectively control its heat generation.

Input impedance and load impedance

     The input impedance of a typical wire-wound transformer is proportional to the load impedance, while the piezoceramic transformer is the opposite as the load impedance increases, the input impedance decreases. This characteristic is extremely important when piezoelectric ceramic transformers are used as high voltage applications. This is a unique advantage of piezoelectric ceramic transformers because the transformer automatically shuts off when the load is shorted without being burned out.Temperature characteristics of PZT material piezio ceramic