Design of a Power Piezoelectric Transformer for a PFC Electronic Ballast

A power piezoelectric transformer (PT) was used to replace the conventional inductor-capacitor resonant tank to save valuable space and cost for ballast applications. In the past, the design of the PT or Transoner for the ballast circuit has been difficult due to the complex interaction between the physical and electrical equivalent circuit characteristics. Previous ballast design using the PT requires selecting available PT models that do not normally match the specific application, therefore resulting in poor efficiency. In this paper, a design procedure was established for a PT tailored to a 120-V 32-W power-factor-correction electronic ballast. A prototype Transoner based on this design was fabricated by Face Electronics Inc., Norfolk, VA, and was experimentally tested. The experimental results showed that the ballast using the designed PT can achieve unity power factor, zero-voltage switching, and 83% overall efficiency.