LC-CLLC Compensation Method for Electric Field-Coupled Wireless Ultrasonic Motor Drive

In high magnetic field, vacuum, or sealed environments, conventional electromagnetic drive systems are hindered by magnetic material interference, complex cabling, and poor structural integrability, making it difficult to satisfy the growing demand for non-magnetic, wireless actuation in spacecraft, medical devices, and high-precision actuators. Ultrasonic motors (USM), with their compact structure, immunity to magnetic interference, and low-speed, high-torque output, show significant potential in such applications. However, efficient electric-field-coupled wireless drive solutions specifically designed for USMs remain scarce. This paper presents a capacitive power transfer (CPT)-based wireless USM drive system employing a bilateral LC compensation topology. A series–parallel LC network is implemented on both the primary and secondary sides to achieve high-frequency resonant voltage boosting, while an LLCC matching network is incorporated at the motor side to enable efficient tuning and constant-voltage output for the capacitive USM load. Theoretical modeling and experimental results demonstrate that the proposed system provides load-independent voltage gain, reduces inductance volume on both sides, and minimizes the number of required compensation components. The system delivers a stable 320V high-frequency sinusoidal voltage capable of effectively driving a rotary USM, offering a compact structure, high integrability, and strong robustness. These characteristics make it well-suited for wireless drive applications in magnetically sensitive environments, such as MRI-guided robotic systems and spaceborne micro-actuators.