This paper describes the design of a traveling-wave ultrasonic motor (TWUSM) drive circuit, intended to simultaneously employ both driving frequency and phase modulation control. The operating principles and a detailed analysis of the proposed driving circuit, consisting of voltage-controlled oscillator (VCO), voltage-controlled phase-shifter circuit and non-resonant power amplifier converter, are introduced. To drive the USM effectively, a two-phase power amplifier converter using non-resonant

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... output was designed to provide a balanced two-phase voltage source. Two-phase output driving voltages could be maintained at the same peak voltage value as the driving frequency under varying phase-modulation processes. Detailed experimental results are provided to demonstrate the effectiveness of the proposed driving circuit.