Desing of a high frequency two-phase power inverter with programmable phase shift using dds based numerical oscillators

Abstract

Consulta en la Biblioteca ETSI Industriales (7677)

[EN] The goal of this work is the design of a two phase power inverter for driving ultrasonic motors. These actuators operate using the piezoelectric effect that describes the ability of some materials to generate an electric potential in response to an applied mechanical stress. The piezoelectric effect is reversible. Materials exhibiting the direct piezoelectric effect also show a converse piezoelectric effect and generate mechanical strain when an electric field is applied. The piezoelectric effect is used in sensor applications namely the generation of voltages, production and detection of sound, electronic frequency generation. Applications of ultrasonic motors include auto-focus positioning tasks in cameras or small scale miniature motors with high power density (2.5 watt/cm3) and a speed ranging up to 800 mm/s. To drive most of these motors a middle frequency power inverter roughly operating from 20 to 100 kHz is required for which the design will be presented in this thesis. The final aim was to design the inverter with two outputs that can be shifted in phase manually from a 90 degrees phase lead to a 90 degrees phase lag and can be used to drive two-phase ultrasonic motors. DDS technology is used to generate the primal driving signal. The inverter was built with two bridge drivers and can be connected to a filter circuit. to suppress the harmonic content as much as possible and obtain a sine wave. The filter was built in the course of a previous thesis and did not need to be modified.