Modeling and Test Structures for Accurate Current Sensing in Vertical Power FETs

Current measurement is a key part of the monitoring system for power transmission lines. Compared with the conventional current sensor, the distributed, self-powered and contactless current sensor has great advantages of safety and reliability. By integrating the current sensing function and the energy harvesting function of current transformer (CT), a time-multiplexed self-powered wireless sensor that can measure the power transmission line current is presented in this paper. Two operating modes of CT, including current sensing mode and energy harvesting mode, are analyzed in detail. Through the design of mode-switching circuit, harvesting circuit and measurement circuit are isolated using only one CT secondary coil, which eliminates the interference between energy harvesting and current measurement. Thus, the accurate measurement in the current sensing mode and the maximum energy collection in the energy harvesting mode are both realized, all of which simplify the online power transmission line monitoring. The designed time-multiplexed working mode allows the sensor to work at a lower transmission line current, at the expense of a lower working frequency. Finally, the proposed sensor is verified by experiments.

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On-site monitoring of bearing failure in composite bolted joints using built-in eddy current sensing film

Journal of Composite Materials ◽

10.1177/0021998320979737 ◽

2020 ◽

pp. 002199832097973

Author(s):

Qijian Liu ◽

Hu Sun ◽

Yuan Chai ◽

Jianjian Zhu ◽

Tao Wang ◽

...

Keyword(s):

Numerical Simulations ◽

Eddy Current ◽

Failure Modes ◽

Bolted Joints ◽

Bearing Failure ◽

Monitoring Method ◽

Current Sensing ◽

Site Monitoring ◽

Array Sensing ◽

Bearing Damage

Bearing damage is one of the common failure modes in composite bolted joints. This paper describes the development of an on-site monitoring method based on eddy current (EC) sensing film to monitor the bearing damage in carbon fiber reinforced plastic (CFRP) single-lap bolted joints under tensile testing. Configuration design and operating principles of EC array sensing film are demonstrated. A series of numerical simulations are conducted to analyze the variation of EC when the bearing failure occurs around the bolt hole. The results of damage detection in the horizontal direction and through the thickness direction in the bolt hole with different exciting current directions are presented by the finite element method (FEM). Experiments are performed to prove the feasibility of the proposed EC array sensing film when the bearing failure occurs in CFRP single-lap bolted joints. The results of numerical simulations and experiments indicate that bearing failure can be detected according to the variation of EC in the test specimen.

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Simultaneous Voltage and Current Measurement Instrumentation Amplifier for ECG and PPG Monitoring

Electronics ◽

10.3390/electronics10060679 ◽

2021 ◽

Vol 10 (6) ◽

pp. 679

Author(s):

Jongpal Kim

Keyword(s):

Integrated Circuit ◽

Cardiovascular Health ◽

Current Noise ◽

Instrumentation Amplifier ◽

Current Sensing ◽

Application Specific Integrated Circuit ◽

Time Division ◽

Electrocardiogram Ecg ◽

First Time ◽

Application Specific

An instrumentation amplifier (IA) capable of sensing both voltage and current at the same time has been introduced and applied to electrocardiogram (ECG) and photoplethysmogram (PPG) measurements for cardiovascular health monitoring applications. The proposed IA can switch between the voltage and current sensing configurations in a time–division manner faster than the ECG and PPG bandwidths. The application-specific integrated circuit (ASIC) of the proposed circuit design was implemented using 180 nm CMOS fabrication technology. Input-referred voltage noise and current noise were measured as 3.9 µVrms and 172 pArms, respectively, and power consumption was measured as 34.9 µA. In the current sensing configuration, a current noise reduction technique is applied, which was confirmed to be a 25 times improvement over the previous version. Using a single IA, ECG and PPG can be monitored in the form of separated ECG and PPG signals. In addition, for the first time, a merged ECG/PPG signal is acquired, which has features of both ECG and PPG peaks.

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