The ZVS Class E/F3 Inverter Using Piezoelectric Transformers for Energy Extraction

Enhanced class E inverters (EFn or E/F-n) reduce the high peak switch voltage that is prevalent in class E inverters. Additionally, their stability and load regulation capabilities are improved as compared to class E inverters. This paper proposes an enhanced class E inverter (E/F-3) with a piezoelectric transformer (PT) replacing the auxiliary resonant networks. This class E/F-3 inverter is designed by adding a tuned auxiliary LC network at the third harmonic of the switching frequency to the class E inverter. Both the primary and auxiliary resonant networks are realized using a piezoelectric transformer (PT). The converter is simulated in LTspice and an experimental prototype is built and tested. It is found that the experimental results concur with the simulation results, with a measured efficiency of 90%. Thus, the theoretical design is verified and the concept of energy extraction is achieved.