Piezoelectric Ceramic Transformer for Power Supply Operating in Thickness Extensional Vibration Mode

概要

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This paper presents a new sort of multilayer piezoelectric ceramic transformer for switching regulated power supplies. This piezoelectric transformer operates in the second thickness extensional vibration mode. Its resonant frequency is higher than 1 MHz. First, numerical simulation was implemented using a distributed constant electromechanical equivalent circuit method. It was calculated that this piezoelectric transformer, which has higher than 200 mechanical quality factor Q_m, could work with higher than 90% efficiency and in more than 20-W/cm^3 high power density. Second, a trially fabricated transformer, which is 15 mm long, 15 mm wide and 2.2 mm thick, was examined. Modified PbTiO_3 family ceramics were used for the piezoelectric transformer material, because of the large anisotropy between electromechanical coupling factors k_t and k_p. Obtained results indicate that the piezoelectric transformer has good resonant characteristics, with little spurious vibration, and exhibits 16-W/cm^3 power density with high efficiency at 2 MHz. Moreover, a switching regulated power supply, applying the piezoelectric ceramic transformer, was built and examined.
社団法人電子情報通信学会の論文
1994-12-25