LLCC resonant inverter for piezoelectric ultrasonic motor drive

An LLCC resonant circuit is implemented in this study to build a high-frequ ency two-phase voltage source inverter for the piezoelectric ultrasonic mot or (USM). A single-phase equivalent model of the USM is described. The oper ating principle and detailed analysis of the proposed driving circuit, in w hich the inherent parasitic capacitances formed by the polarised piezoelect ric ceramic of the USM are parts of the two LLCC resonant circuits, are int roduced. Since the dynamic characteristic of the USM is greatly influenced by the variation in the Q of the RLC resonant tanks, the drive will be oper ated about a geometric frequency where the amplitude and phase of the two-p hase output voltages of the resonant inverter would not be influenced by th e variation in Q. Detailed experimental results art: provided to demonstrat e the effectiveness of the proposed driving circuit.