METHOD OF CONTROLLING AMPLITUDE OF MECHANICAL EXCITATION OF A PIEZOELECTRIC POWERED ULTRASONIC STACK INCLUDING UNDER LOAD

摘要

An ultrasonic system has a piezoelectric powered ultrasonic stack having a piezoelectric ultrasonic converter excited by an ultrasonic power supply. A control loop feedback controller determines in real time a true amplitude of mechanical excitation at the end of the piezoelectric powered ultrasonic stack including when the piezoelectric powered ultrasonic stack is under load by multiplying one of an amplitude of motional voltage exciting the piezoelectric ultrasonic converter and an amplitude of motional current exciting the piezoelectric ultrasonic converter by a cosine of a phase difference angle between the motional voltage and the motional current and controls the ultrasonic power supply to control an output amplitude of at least one of output voltage and output current of the ultrasonic power supply so that the determined true amplitude of mechanical excitation at the end of the piezoelectric powered ultrasonic stack