Design of a high-efficiency switching power amplifier for driving piezoelectric transducers

Abstract

Recently developed methods for wireless power transfer through metallic barriers using acoustic-electric channels require specialized amplifiers to drive their ultrasonic transducers. These channels operate at frequencies varying from 50 kHz to 1.5 MHz and present input impedance magnitudes from 50 to 1,000 Ohms. Requiring amplifiers to operate over this broad range of conditions while maintaining high levels of efficiency in high temperature environments presents a challenging set of design constraints.Two types of amplifier topologies are presented within this thesis: designs with and without galvanic isolation. Each design was researched, designed, and realized with custom printed circuit boards, and their performance was analyzed thoroughly. Design life was documented as the five individual revisions were developed and manufactured. Revisions are compared with one another and with how they fit into the specific requirements of the project application. Results include completed amplifier designs and working prototypes capable of delivering more than 50 W of power at greater than 98% efficiency, operating with up to 600 VDC supplies, driving a full range of ultrasonic transducer loads at various frequencies, and using components rated for 125 degrees C.