Rotational Speed Measurement Based on LC Wireless Sensors

This article presents a method for detecting rotational speed by LC (inductor-capacitor) wireless sensors. The sensing system consists of two identical LC resonant tanks. One is mounted on the rotating part and the other, as a readout circuit, is placed right above the rotating part. When the inductor on the rotating part is coaxially aligned with the readout inductor during rotation, the mutual coupling between them reaches the maximum, resulting in a peak amplitude induced at the readout LC tank. The period of the readout signal corresponds to the rotation speed. ADS (Advanced Design System) software was used to simulate and optimize the sensing system. A synchronous detection circuit was designed. The rotational speed of an electric was measured to validate this method experimentally, and the results indicated that the maximum error of the rotation speed from 16 rps to 41 rps was 0.279 rps.

A Wireless Passive Vibration Sensor Based on High-Temperature Ceramic for Harsh Environment

This paper proposes a wireless passive vibration sensor based on high-temperature ceramics for vibration measurement in harsh environments such as automotive and advanced engines. The sensor can be equivalent to an acceleration-sensitive RF LC resonance tank. The structural design of the LC tank and the signal wireless sensing mechanism are introduced in detail. The high-temperature mechanical properties of the sensitive structure are analyzed using ANSYS at 25–400°C, which proves the usability of the vibration sensor in high-temperature environment. The three-dimensional integrated manufacturing of vibration sensors with a beam-mass structure based on high-temperature ceramics is completed by a bonding process. Finally, the performance of the sensor is tested on a built experimental platform, and the results show that the vibration sensitivity is approximately 1.303 mv/m·s-2, and the nonlinear error is approximately 4.3%. The vibration sensor can work normally within 250°C, and the sensitivity is 0.989 mv/m·s-2.