New Transformer Oil Density Measurement Method Based on PMUTs-on-CMOS

Liquid parameter detection plays a crucial role in various fields, particularly in electrical engineering, where monitoring transformer oil density is essential for ensuring transformer reliability. In this study, a novel transformer oil density detection method based on the acoustic wave time-of-flight (ToF) principle is proposed, and temperature-dependent analysis is conducted over a wide range of densities. Additionally, an associated parameter extraction method aiming for application in transformer oil line density detection is presented. To validate the reliability of the model, a PMUTs-fluid–PMUTs (PFP) density measurement experimental platform is developed, which represents the first application of piezoelectric micromachined ultrasonic transducers (PMUTs)-based ranging system to measure the internal line density of transformer oil. To assess the accuracy and stability of the density measurement system, comparative experiments on transformer oil under various conditions are conducted. The results show that the PMUTs-on-CMOS system can detect transformer oil line density with an error margin of less than 1.68%. The proposed system overcomes traditional limitations of bulky equipment and lack of real-time capability, thereby enabling the measurement of average variations in the line path density of transformer oil while providing low power consumption, high accuracy, rapid response, and easy integration.