Title :
A double-closed loop DC/DC converter based on a piezoelectric transformer
Author :
Díaz, J. ; Martín-Ramos, J.A. ; Prieto, M.J. ; Nuño, F.
Author_Institution :
Oviedo Univ., Spain
Abstract :
Nowadays, piezoelectric transformers (PT) are a good alternative to substitute magnetic materials in AC/DC and DC/DC converters. They have high isolation voltage and operate at high frequencies, with lower losses. However, their optimum operating frequency exhibits a strong dependence on different parameters, such as temperature, load or voltage level applied. This usually causes an inconvenience, because this drift affects PT gain and efficiency, which can vary enormously within a few hundred of hertzs. On the other hand, it is not only necessary to ensure the PT is driven at the proper frequency -in terms of gain and efficiency, including zero voltage switching (ZVS) in the power stage- but also to regulate the output voltage. In this paper, two simple feedback loops are implemented in a PT based DC/DC converter: One of them adjusts the switching frequency to obtain the best gain and efficiency. The other performs the output voltage regulation.
Keywords :
AC-DC power convertors; DC-DC power convertors; piezoelectric devices; resonant power convertors; switching convertors; transformers; voltage control; AC-DC converters; DC-DC converter; PT; ZVS; feedback loop; magnetic material; optimum operating frequency; piezoelectric transformer; resonant converters; switching frequency; voltage regulation; zero voltage switching; Circuit topology; DC-DC power converters; Equivalent circuits; Feedback loop; Frequency; Impedance; Inductors; Resonance; Voltage control; Zero voltage switching;
Conference_Titel :
Applied Power Electronics Conference and Exposition, 2004. APEC '04. Nineteenth Annual IEEE
Print_ISBN :
0-7803-8269-2
DOI :
10.1109/APEC.2004.1296051