Continuous high-performance drive of rotary traveling-wave ultrasonic motor with water cooling

It is known that rotary traveling-wave ultrasonic motors (RTUSMs) have several inherent advantages over conventional electromagnetic motors. However, the practical applications of RTUSMs are limited in the field of transitory servo drive. The underlying reason is that the temperature rise caused by internal losses has a significant influence on the motor characteristics, which gives rise to substantial performance degradation and poor operational reliability. To explore the feasibility of RTUSMs in the applications of continuous motion drive, we propose to maintain the output performance by directly suppressing the working temperature rise. Based on convective heat transfer, a water-cooling motor base was designed to remove heat from the stator. The motor base was fabricated by embedding a simple pipeline structure and connected to a commercial PC water-cooling radiator. The experimental results show that the RTUSM60 motor maintains an output power of 3.3 W and a temperature rise of 22 °C during 48-h continuous operation with water cooling. Due to the effective suppression of temperature rise, the motor can work with a stable output power of 2.35 W even under the load torque of 0.9 N m.