An ultra-fast transient performance tracking scheme for high power piezoelectric transducers

The vibration transient performance is critical for dynamic capability and operational stability of high power piezoelectric transducers (HPPTs). However, most of previous researches focus on the shut-down transient, there is little research on optimizing the start-up transient. This paper presents an ultra-fast transient tracking scheme for the start-up vibration response of HPPTs. The transient characteristics of the HPPT with an electrical matching are firstly derived. Then, to optimize the start-up transient without resistive loss, an equivalent virtual resistor is introduced by an inverter combined with a transformer and LC matching (ITLC) driving scheme. Furthermore, to improve the phase-frequency transient during the initial start-up transient phase, the susceptance-based frequency tracking control scheme is proposed. Experimental results demonstrate that the proposed scheme not only can break through the limitation of the transient time constant τ of the HPPT to reduce both the response time and tracking time, but also has a higher robustness under different start-up frequencies and load conditions compared to traditional phase feedback method. In an ultrasonic cutting system with τ of 100.8 ms, the proposed scheme achieves the dynamic control performance with a frequency tracking time of 5.5 ms (0.055τ) and a vibration response time of 15.0 ms (0.15τ).