Temperature rise mechanism and loss model analysis in a MEMS micro traveling-wave motor

Thermal accumulation-induced performance degradation critically limits the application of micro ultrasonic motors (MUSMs) in precision systems. However, a systematic understanding of this behavior is lacking, as existing macroscopic models fail to capture the complex electro-thermo-mechanical coupling at the micro-scale. To bridge this gap, we present a coupled dynamic model tailored to a MEMS rotary traveling-wave ultrasonic motor, validated by an integrated experimental setup for synchronized drive control and sensing. Under continuous operation, the motor temperature rises by 8.6°C, causing a resonance frequency drift of 1.66kHz. Consequently, the rotational speed decreases from 392 rpm to 348 rpm (an 11.2 % reduction), while the output torque exhibits a dynamic equilibrium process. These findings provide a quantitative basis for designing thermally stable micro ultrasonic motors.