A High-Tolerance Matching Method Against Load Fluctuation for Ultrasonic Transducers

Abstract

Fluctuation of acoustic load significantly weakens the performance of ultrasonic system. To address this problem in a simple way, we consider the main input and output variables related to the ultrasonic transducer's performance and propose a detailed mathematical model based on the simplest LC matching network containing only one capacitor and one inductor. In this model, a new resonance frequency brought by matching components was found and defined. The optimum analysis method is used to solve the model, and a high-tolerance matching method against load fluctuation is obtained. Analysis indicates that when activated at the mechanical resonance frequency, the impedance and apparent power of the PT matched by the proposed method are constant no matter how the load changes, and thereby can significantly increase the stability and robustness of ultrasonic systems. For its simple structure and high performance, the proposed matching method can be widely applied in most ultrasonic systems. The tolerance of the proposed method against other environmental factors and high-order LC matching networks were also discussed. In addition, the feasibility and advantage of the proposed matching method are also verified by experiments.

Optimized Design of a Sonar Transmitter for the High-Power Control of Multichannel Acoustic Transducers

“…The RC load was used to check the exact operation in the transmitter control test [3]. (2) The real multichannel acoustic transducer (MCAT) load was established so as to verify that the proposed control reduces the impedance variation caused by the FM. The MCAT consists of multichannel transducers; the number is N. The proposed control used a transmitting FM signal.…”

“…In recent years, the applications of acoustic transducers and transmitters have been expanded for sonar, medical, communications, and industrial purposes [1][2][3][4][5][6]. The mechanical and acoustic operations of an acoustic transducer are generally expressed as an electrical equivalent circuit model [7][8][9].…”

“…Since an acoustic transducer is a complex impedance load, a matching/filter circuit between a transmitter and an acoustic transducer is required for minimizing reactance and reducing THD (total harmonic distortion) [4,[10][11][12][13][14][15]. To utilize their load characteristics, various control methods have been studied for the transmitters driving transducers with variable impedance [2,[16][17][18].…”

“…Wang et al proposed a novel fast resonance tracking control for ultrasonic transducers [1]; they utilized the fact that the angle of a resonance point shifted by moving a center point of a G-B curve is correlated with a shifted center point of the G-B curve. Wang et al attempted to mathematically calculate a resonance frequency for finding the optimized matching point [2]. Cheng et al utilized parallel resonance frequency tracking and applied ZVS (zero-voltage switching) to the transmitter by considering both the parasitic capacitance of switches and the circuit elements of a transducer [19].…”

A Novel Fast Resonance Frequency Tracking Method Based on the Admittance Circle for Ultrasonic Transducers

“…In order to avoid above-mentioned problems, several other RFT methods have been proposed in the literature that avoid tracking and rather track other characteristic frequency or value, such as tracking the parallel resonance frequency [13], the maximum power [5,20,23], the maximum admittance [24], or keep constant amplitude [16,[25][26][27][28]. These methods have achieved relatively good results.…”