Patent ID: 6013969
Filing Date: 2000-01-11
Classification: H02M,H05B

Abstract:
A piezoelectric transformer inverter comprising:a piezoelectric transformer for converting an alternating voltage applied across its primary electrodes to an alternating current which is supplied to a load connected to its secondary electrode;a boosting drive circuit made up of a first series combination of a first coil and a first switching element for applying a voltage to one of said primary electrodes of said piezoelectric transformer, a second series combination of a second coil with a second switching element for applying a voltage to another of said primary electrodes of said piezoelectric transformer, and a two-phase drive circuit for alternately driving said first and second switching elements;a driving voltage control circuit connected between an input terminal of said series combinations and an input power supply and adapted to control an average voltage applied to said input terminal of said series combinations whereby current on a secondary electrode side of said piezoelectric transformer is maintained at a constant level; anda driving frequency control circuit which controls a driving frequency at which said first and second switching elements are driven in such a manner that the phase difference between said alternating voltage applied to said primary electrodes of said piezoelectric transformer and said alternating current flowing supplied to said load is maintained at a predetermined value.