Parallel driving of piezoelectric transformers

Parallel driving of piezoelectric transformers has been studied to increase output power, and output characteristics of multiple piezoelectric transfo rmers that are driven in parallel from 2 to 5 have been compared to those o f a single transformer The voltage step-up ratio increased in proportion to the parallel connection number, n, but the rate of increase decreased grad ually, so there was little increase with driving over 5 piezoelectric trans formers in parallel. The relative efficiency showed a maximum value of 1.06 with n of 2 and a minimum value of 0.75 with ra of 5. The output power inc reased continuously according to the parallel connection number, but the re lative output power per transformer gave a value of 1.015 with n of 2 and d ecreased to below 1.0 with greater n, so it of 5 gave a value of 0.75.