Width-Extensional Piezoelectric Ceramic Transformer

• Main Authors: PŮLPÁN Petr, ERHART Jiří
• Format: Article
• Language: English
• Published: Editura Universităţii din Oradea 2018-10-01
• Series: Journal of Electrical and Electronics Engineering
• Subjects: piezoelectric ceramic resonator; width-extensional vibration mode
• Online Access: http://electroinf.uoradea.ro/images/articles/CERCETARE/Reviste/JEEE/JEEE_V11_N2_OCT_2018/04paper0713PULP

Piezoelectric transformers in the shape of rectangular ceramic plate working in width-extensional mode are studied in an analytical model as well as experimentally. This vibration mode uses the higher electromechanical coupling coefficient k_31^' instead of k_31 for the length-extensional vibration mode. Higher electromechanical coupling coefficient results in the high efficiency reaching 98% at an optimum load 1-2 kΩ. However, the best efficiency close to 100% could be realized with the transformation ratio less than 1, so the application is suitable for the step-down transformers. Presented width-extensional mode transformer exhibits simple electrode structure, medium no-load transformation ratio (10-25) and high efficiency at an optimum load. Nodal plane at the minor face of transformer plate allows also for the simple mechanical clamping of transformer in the printed board electronics. Developed analytical model serves as a powerful tool for the electrode aspect ratio optimization. The optimum no-load transformation ratio was found at 0.63 input electrode aspect ratio.