Design and implementation of the driving circuit for a 1 mm cylindrical piezoelectric ultrasonic motor

The performance of the driving circuit is critical for the stable and high-precision operation of micro piezoelectric ultrasonic motors. To meet the low-voltage drive and high-speed operation requirements of a 1 mm micro cylindrical piezoelectric ultrasonic motor, a transformer-inverter booster push-pull driving circuit based on the digital signal processing (DSP) 28335 chip is proposed. The DSP 28335 generates four pulse-width modulation (PWM) signals, which alternately drive four MOSFET switches. The inverter boosts and amplifies the voltage through a transformer, and an LC matching circuit filters the output to produce sinusoidal waves with equal amplitude and 90° phase difference, driving the motor. Detailed hardware and software design analyses are presented. Simulation and experiment results show that the output voltage is adjustable from 0 V to 100 V and the frequency from 15 kHz to 50 kHz. The no-load speed of the motor increases linearly with excitation voltage, reaching 480 r/min at 22 kHz and 50 V, satisfying the driving requirements of the 1mm cylindrical piezoelectric ultrasonic motor.