A Precise Real-Time Monitoring System for the Amplitude of an Ultrasonic Transducer Based on Passive Piezoelectric Sensors

In power ultrasonics, the amplitude of ultrasonic transducers (UT) can be unstable due to changes in external loads, system impedance and temperature, resulting in UT’s low work efficiency and accuracy. To control the amplitude rapidly and precisely, a precise real-time monitoring system for the UT’s amplitude based on passive PZT sensors is proposed. Firstly, the UT integrated with passive PZT sensors is designed and fabricated, which can feedback real-time amplitude based on the piezoelectric effect of the sensors. Then a load application system is established for the frequency response test and time response test under various loads of the integrated sensors. The frequency response results indicate that the sensor perform well in the right side of the resonance frequency, which lower demands on frequency tracking results. The sensing performance of integrated PZT sensors is characterized in the time response test with high correlation (R
²
> 0.97}), low delay (∆t < 6 ms), small hysteresis, and high repeatability (σ < 0.05). The good sensing performance of the proposed sensor points to potential applications in amplitude control.