Automatic measurement of the equivalent static capacitance of ultrasonic transducers for dynamic matching

The ultrasonic piezoelectric transducers have been widely applied in industrial fields, and they should be well matched to ensure its power transfer efficiency or measure accuracy. However, the electric characteristics of the transducers vary greatly with temperature, which will cause the deficiency of static matching. The existing tuning method or dynamic matching method may compensate for the variations, but they both have some limitations in applications. In this paper, a method based on the Wien bridge oscillation circuit is proposed to dynamically measure the equivalent static capacitor of ultrasonic piezoelectric transducer. It can overcome the limitations facing the conventional dynamic matching and help to realize self-adjusting of the matching inductors. This method is adaptable for a variety of ultrasonic instruments and devices, especially for the ultrasonic flow meters.