A dynamic impedance matching method for acoustic systems based on variable inductance

In the context of ultrasonic cutting, it is observed that the impedance characteristics of the acoustic system undergo a transformation as a consequence of load variation and the elevated temperature of the transducer, consequently giving rise to impedance mismatch issues, which in turn result in a reduction in system stability and machining efficiency. To address this issue, this paper proposes a dynamic impedance matching method based on variable inductance, which is designed to complement the static impedance matching circuit. First, the principle of a dynamic impedance matching circuit using variable inductance is analyzed, and the relationship between the system impedance and the variable inductance is established. Subsequently, the variable inductance is designed and verified, with the inductance value being adjusted by controlling the winding current to alter the magnetic permeability of the variable inductance core. Ultimately, the phase difference between the system voltage and current (impedance angle) is employed as the adjustment criterion, with the winding current regulated through a Proportional-Integral (PI) algorithm to achieve dynamic adjustment of the variable inductance value. The results demonstrate that the proposed method achieves dynamic impedance matching, reducing voltage-current phase difference within ±5° and stabilizing tool tip amplitude within 20-25 μm. Forward power increased by 30%, ensuring efficient material machining. This method significantly enhances both stability and machining efficiency in ultrasonic machining systems, which provides technical support for ultrasonic machining.