A Shared DC-Bus Multi-Channel Drive Architecture for Ultrasonic Motors

Conventional multi-channel ultrasonic motor (USM) drive systems commonly adopt a one-motor–one-driver architecture, in which each drive channel requires an independent isolated power supply and inverter stage. As the number of motors increases, the system volume and structural complexity grow significantly. To address this issue, this paper proposes a shared DC-bus multi-channel drive architecture for traveling-wave USM. In the proposed scheme, multiple half-bridge power stages are connected in parallel to a common high-voltage DC-bus to achieve centralized energy supply and distributed driving. A DC-side midpoint reference network is introduced to establish an AC voltage reference under a unipolar DC supply, while an independent series matching inductor is employed in each channel to shape the half-bridge output into a quasi-sinusoidal motor-terminal voltage through resonant filtering. Based on the equivalent electrical model of the USM, a unified analytical model is established to analyze the voltage formation mechanism under shared DC-bus conditions. Time-domain simulations and experimental tests are carried out on a two-channel prototype operating at a 150 V DC-bus and a 40 kHz switching frequency. The results demonstrate stable quasi-sinusoidal output voltages, preserved phase consistency, and limited inter-channel coupling during parallel operation. Compared with conventional independent-supply solutions, the proposed architecture achieves an approximately 27% reduction in overall system volume for a three-motor configuration, demonstrating good scalability for compact multi-channel USM drive systems.