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This paper presents a highly effective load adaptive drive system to control the speed of a travelling-wave ultrasonic motor. The motor driver was built based on the two-phase high-frequency inverter using the mechanical resonant frequency of the ultrasonic motor. To digitally control the drive system, a TMS320F243 digital signal processor was adapted to the driver. The developed system includes two feedback loops; speed control loop and feedback voltage-resonant frequency tracking loop. The driving frequency was used as a control input to control the motor. Direct pulse-width modulation (PWM) control was used to obtain the required driving frequency. The developed drive system was experimentally tested under several operating conditions. The obtained results demonstrated the effectiveness of the drive system for high performance drive applications.