Current Measurement Methods Research Articles

On-Line Measurement of Chip Temperature Based on Blocking Leakage Current of the Insulated-Gate Bipolar Transistor Module in the High-Temperature Reverse-Bias Test

In high-temperature reverse-bias test of an insulated-gate bipolar transistor module, the problem of self-heating in chip resulting from power loss arises with high frequency. To address this problem, the law of the variation in leakage current with temperature for the reverse-bias state of a device is derived and utilized to establish a temperature calibration curve, with which the online measurement of the insulate-gate bipolar transistor module chip temperature can be implemented directly by real-time monitoring of device leakage current in high-temperature reverse-bias test. The method we proposed solves the problem of large measurement error in chip temperature obtained by traditional thermal resistance calculation method. In addition, real-time chip temperature can be monitored without introducing additional test circuit or HTRB interruption experiment. To demonstrate the effectiveness of the proposed method, the switching small-current temperature measurement method is used to make comparison, and the experiment result indicates that the temperature of the chip in the blocking test can be obtained with high precision by using the leakage current measurement method presented in this work.

Automatic 3-D Imaging and Measurement of Human Spines With a Robotic Ultrasound System

Comparing with X-ray, ultrasound imaging has the advantages of no radiation and easy operation, etc., which is expected to be an effective alternative in clinical assessment for the human spine. At present, freehand scanning is mainly used in ultrasound imaging field, and recently robot-assisted scanning has emerged as a promising way to gradually reduce human intervention. However, the automatic recognition and scanning, as well as the control strategy of robots that guarantee the tight coupling between a probe and human skin, are still challenges. Moreover, the current measurement method of the spine is usually conducted based on plain radiographs, which lacks spatial structure information of spine. In this article, a new radiation-free robotic ultrasound system for 3-D imaging and a measurement method of the spine based on 3-D imaging are presented. A fully convolutional network (FCN) named fuse-Unet based on RGB and depth images captured by an RGB-depth (RGB-D) sensor Kinect, is proposed to realize the automatic recognition of human spine area and scanning path pre-planning. Then a six-degree-of-freedom robotic arm plays the role of a doctor to complete the automatic scanning along the pre-planning path, during which a normal-vector-based method and two force sensors are used to ensure that the probe well fits the spine area. Finally, 3-D ultrasound reconstruction and visualization of the spine are realized, based on which cobb angles are calculated for assessing the morphological structure of the spine. Phantom and in vivo experiments are conducted for evaluating the performance of the proposed system. Experimental results validate the practicability and accuracy of the system, indicating its potential for clinical application.

Development of PIV measurement technique in turbulent flow laden with binary-size particle groups

Abstract Particle image velocimetry (PIV) is an instantaneous whole-field measuring diagnostic that makes it feasible to measure the microscale spatial information of the interphase dynamics for good understanding of two-phase flow. However, application of PIV to the two-phase flow measurement is still a state of the art so far. A double-discriminating process in terms of gray level and size of image patterns together with the median mask technique is developed. The test flow is a turbulent air wake laden with a binary group of particles with the mean size of 2.7 μm (representing the carrier phase) and 55 μm (representing the dispersed phase). It is demonstrated that the velocity measurements of both phases can be successfully performed through the combined PIV/PTV (particle tracking velocimetry) scheme associated with the developed phase discrimination method. It is noted that the discriminating capability of the size ratio between the large- and small-particle groups in the study is around 20 together with the mean size of O(100 μm) for small particles, which is the commonly required size for the seedings used in the PIV measurements of airflows, as compared to the size of O(101 μm) adopted in the current two-phase PIV measurement methods.

Determination of corrosion rate in places of insulation damage of underground pipelines

The electromagnetic method of non-contact current measurements makes it possible to quickly monitor the state of passive (insulating coatings) and active (cathodic polarization) corrosion protection of underground pipelines (UP); detect places of unsatisfactory insulation, determine the transient resistance and its components (resistances of soil, insulating layer, polarization) in different sections, the area of insulation damage, the current distribution of cathodic protection of UP. In combination with contact measurements of direct and alternating voltages, ohmic and polarization potentials, it is possible to determine the polarization resistance and estimate the corrosion rate.

A High-Efficiency IGBT Health Status Assessment Method Based on Data Driven

As a critical device of power electronics, the health status and residual life of the insulated gate bipolar transistor (IGBT), as well as its high-efficiency assessment should be concerned. High-efficiency assessment methods can provide dangerous warning for transportation equipment to avoid catastrophic accidents. This article focuses on the IGBT solder layer failure. We use the finite element simulation combined with the small current junction temperature measurement method to obtain the relationship between the internal structure degradation of the solder layer and the sensitive parameters of the external port under different load conditions. According to the characteristics of port parameters, a data processing method called multiple weight function (WF) network (MWFN) is developed, and the parameter monitoring platform is built. Finally, an IGBT health assessment method based on MWFN is formed. The main advantage of this method is that the best WF is introduced into the neural network to solve the time-consuming problem of updating the high-dimensional weight matrix. In the case study, the active power cycling test was carried out. We obtained the solder layer delamination images by using the 3-D tomography system and the corresponding port parameters by monitoring platform. From the perspective of evaluation results, the proposed method not only performs as well as other mainstream data-driven methods in terms of evaluation accuracy but also has significant advantages in terms of running time.

Feasibility of using thermal response methods for nonintrusive compressed air flow measurement

Robust, low-cost nonintrusive flow meters are of interest in many industries. In particular, a reliable nonintrusive flow measurement for the diagnosis of air leaks in compressed air systems is desirable. Measurement of the air flow due to leaks in the system ensures an accurate estimation of potential cost and energy savings. This study evaluates a novel method of using thermal responses to nonintrusively measure leakage rates in compressed air lines. The method uses heat and the resulting thermal response to calculate the flow rate inside the compressed air line. Compared to the current methods for flow measurement, this method can simplify flow measurement while decreasing the sensitivity to errors when measuring flow rates. In this study, the methodology of the proposed method is explained along with the potential advantages to the design. Two approaches are evaluated: a dynamic step response and sinusoidal frequency response. Simulated tests evaluate the feasibility of the proposed methods, followed by experiments that validate the simulation results. A clear correlation between the thermal step response and the flow rate indicate viability of the proposed method in simulation. Experimental results yielded similar results, confirming the validity of the proposed method. The results of a field test in an industrial environment demonstrate the capability of the approach to other flow rate measurement techniques.

An Accurate Datasheet-Based Full-Characteristics Analytical Model of GaN HEMTs for Deadtime Optimization

The gallium nitride high electron mobility transistors (GaN HEMTs) are a superior candidate for the new-generation power electronics systems with higher efficiency and power density. However, due to the unique reverse characteristics, the reverse voltage drop of GaN HEMTs is much higher than that of diode. The deadtime loss in GaN-based bridge converters will be comparable to switching losses if the deadtime is not optimized. To optimize the deadtime for higher efficiency, this article proposes an accurate analytical model of GaN HEMTs, including circuit's parasitic inductances, the nonlinear capacitances, the unique reverse characteristics, etc. Taking a GaN-based synchronous buck converter as the example, the proposed model is realized, which fully uses the datasheet to avoid additional experiments. In order to accurately measure the switching current for validation, a novel parasitics-based current measurement method is proposed. The proposed model is verified by simulation in LTspice and experiment, and good agreement is shown. Based on the accurate analytical model, the deadtime is optimized for different load currents to improve the efficiency within the full load range. Compared with the fixed deadtime of 15 ns, the increase of efficiency can be up to 8%. This work will promote the high-frequency application of GaN HEMTs.

A measurement method for tooth surface errors of straight bevel gears based on 3D model

Due to the inconsistency between a theoretically designed tooth surface and the actual measured reference surface, the tooth surface error data obtained by the traditional measurement method is unreliable, and incorrectly reflects the machining accuracy of straight bevel gears. This has become a key problem in the current measurement process, and needs to be resolved. In this paper, a new measurement method is proposed to achieve accurate measurement and evaluation of the machining error of straight bevel gears. The 3-dimensional (3D) model surface designed by the manufacturer is directly extracted as a theoretical reference to complete the measurement, which ensures the correctness of the error results. A measurement strategy of normal rotation of the measured point is adopted to make up for the disadvantages of the one-dimensional (1D) probe and improve the measurement accuracy. The problem of the sensitive direction of the probe deviating from the normal direction is compensated for by increasing the dimension of the 1D probe and reducing the dimension of the 3D normal. According to the constructed error calculation model, the minimum tooth surface error is obtained through reconstruction and optimal matching techniques. Finally, the accuracy and effectiveness of the measurement method are verified through measurement comparison experiments. This method solves the technical problem of the inconsistency of the measured reference surface, and uses a low-cost 1D probe to achieve precise measurement of the 3D surface. It not only improves the disadvantages of current measurement methods, but also provides effective technical support for other gear measurements.

Spin-Zero Polarimetry for Linearly Polarised Photons at MAMI

Background: The tagged Coherent Bremsstrahlung technique is used to provide beams of linearly polarised photons at several of the world’s leading photonuclear facilities, including MAMI in Mainz, ELSA at Bonn, and GlueX at Jefferson Laboratory. The degree of linear polarisation in real photon experiments has direct impact on measurements of polarisation observables. Measurement of the linear polarisation is often the biggest source of systematic error in these experiments. Continuous, in-beam measurement will also allow the beam position to be adjusted to optimise the polarisation. Purpose: To determine whether it is possible to make an improved measurement of the degree of linear polarisation using a polarimeter based on a 12C target. Methods: Coherent π0 meson production from a spin-zero nucleus has a photon asymmetry of 1 and hence provides a direct method of measuring the beam polarisation. Results: Current methods of measurement are being employed as a comparison. Simulated statistics of π0 mesons produced off the polarimeter suggest the measurement is viable. Early results from production data support the viability of live, event-by-event measurements of the polarisation using this method. Conclusions: A spin-zero nucleus such as carbon will be developed as a polarimeter for measuring the degree of linear polarisation in hadron physics experiments with tagged photons of up to 1557 MeV.

Development of Computer Vision Algorithms for Measurement and Inspection of Spur Gears (Dept.M)

Gears are one of the most common mechanisms for transmitting power and motion. Error in gears causes two main problems, increased acoustic noise in operation and increased wear, both of which are sufficiently troublesome to cause concern. Therefore, precision measurement of gears plays a vital role in gear measurement and inspection. The current methods of gear measurement are either time consuming or expensive. In addition, no single measurement method is available and capable of accurately measuring all gear parameters while significantly reducing the measurement time. The aim of this paper is to utilize the computer vision technology to develop a non-contact and rapid measurement system capable of measuring and inspecting most of spur gear parameters with an appropriate accuracy. The vision system has been established in the metrology lab and it is used to capture images for gears to be measured or inspected. A software (named GearVision) has been especially developed in-house using Microsoft Visual C++ to analyze the captured images and to perform the measurement and inspection processes. The introduced vision system has been calibrated for both metric and pixel units. After calibration, the system was verified by measuring two sample gears and comparing the calculated parameters with the actual values of gear parameters. The maximum variations between the calculated parameters and the actual values were +0.101 mm for a spur gear with 156 mm outside diameter. This variation can be decreased by measuring small gears.

Sustained Breast Development and Breast Anthropometric Changes in 3 Years of Gender-Affirming Hormone Treatment.

Breast development is important for most trans women. An important limitation of current breast development measurement methods is that these do not allow for 3D volume analyses. To examine breast development and change in anthropometry during the first 3 years of gender-affirming hormone treatment using 3D imaging. Associations with clinical or laboratory parameters and satisfaction with the gained breast development were also studied. Prospective cohort study. Specialized tertiary gender identity clinic in Amsterdam, the Netherlands. Participants were 69 adult trans women with a median age of 26 years (interquartile range, 21-38). Gender-affirming hormone treatment. Volumetric and anthropometric breast development and satisfaction. Breast volume increased by 72 cc (95% confidence interval [CI], 48-97) to 100 cc (standard deviation 48). This resulted in a cup-size <A-cup in 71% of the participants. Although the change in breast-chest difference plateaued after approximately 9 months, sustained increase in breast volume was observed during the 3-year observation period. Sternal notch to nipple distance increased by 1.3 cm (95% CI, 0.9-1.7) and internipple distance increased by 1.0 cm (95% CI, 0.4-1.5). At least 58% of trans women were satisfied with the gained breast size. Sustained breast growth and development during hormone treatment was observed during the full 3-year observation period. The breasts of trans women are positioned more laterally and caudally on the chest compared with cis women. Although modest breast volumes were observed, breast development was satisfactory to most trans women.

In situ method for stress measurements in film-substrate electrodes during electrochemical processes: key role of softening and stiffening

Electrode stress is one of the main driving forces of electrochemical degradation, which is directly related to battery cycle life, thus attracting great interest. Herein, we propose an in situ method to measure bilayer stresses in film-substrate electrodes during electrochemical processes. This method consists of two parts: stress models featuring Li-dependent material modulus and in situ deformation measurements, through which electrode bilayer stresses evolution accompanied by Li-dependent material modulus can be quantitatively characterized. As application of the method, typical silicon-composite and carbon-composite film-substrate electrodes are selected for in situ mechanical measurements and experimental analysis is performed. Results show that silicon material and carbon material exhibit significant, continuous softening and stiffening, respectively. In two film-substrate electrodes, electrode material films experience compressive stress and current collector substrates undergo a tensile-to-compressive conversion across the thickness. Besides, moduli and stresses in both electrodes vary nonlinearly with capacity, presenting non-overlapping paths between lithiation and delithiation. Based on experimental data, we further demonstrate the key role of Li-dependent modulus on electrode stresses, finding that silicon material softening decreases and carbon material stiffening increases electrode stresses. The deficiencies of current stress measurement method based on Stoney equation and the applicability of our method are discussed.

Development of Measurement Methodology for Sub 23 nm Particle Number (PN) Measurements

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;A proposal for sub-23 nm Solid Particle Number (SPN) measurement method was developed by the Particle Measurement Programme (PMP) group, based on the current SPN measurement method. In the proposal, a Particle Number Counter (PNC) having (65 ± 15)% counting efficiency at 10 nm and &amp;gt;90% at 15 nm (PNC10) replaces the current regulation PNC efficiency of 50±12% at 23 nm and &amp;gt;90% at 41 nm. Additionally, a catalytically active evaporation tube (CS) is required for sub-23 nm measurement method instead of the non-reactive evaporation tube (ET) of the current regulation. Here experimental work carried out at the JRC to address the issues of sub-23 nm SPN-measurement method is presented. The PNC10 was shown to be less dependent on the particle material than the PNC23, thus soot-like particles are still allowed for PNC-calibration. The high charging probability of soot-like particles was shown to have a low effect on PNC calibration uncertainties. The new proposed linearity test which requires that the PNC readings need to be within ±5% of the slope was here shown to be applicable. The proposal requires that Particle Concentration Reduction Factor (PCRF) at 15 nm shall be at most 100% higher than the 100 nm PCRF for the Volatile Particle Remover (VPR). The allowed variability in VPR-losses and PNC10-efficiencies of the new proposal could cause differences up to 36% when a distribution with Geometric Mean Diameter at 15 nm was simulated. Yet, for the commercial CS and ET systems with experimentally determined PCRF 15 nm to 100 nm ratios of 80% and 50% respectively, the maximum difference was 19% using PNC10. The average PCRF in the proposal is calculated as in the current regulation, with an average of PCRFs at 30 nm, 50 nm and 100 nm in order to keep the comparability with the 23 nm regulation and because the addition of the PCRF at 15 nm did not improve the accuracy.&lt;/div&gt;&lt;/div&gt;

Validation and Evaluation of a Ship Echo-Based Array Phase Manifold Calibration Method for HF Surface Wave Radar DOA Estimation and Current Measurement

Shore-based phased-array HF radars have been widely used for remotely sensing ocean surface current, wave, and wind around the world. However, phase uncertainties, especially phase distortions, in receiving elements significantly degrade the performance of beam forming and direction-of-arrival (DOA) estimation for phased-array HF radar. To address this problem, the conventional array signal model is modified by adding a direction-based phase error matrix. Subsequently, an array phase manifold calibration method using antenna responses of incoming ship echoes is proposed. Later, an assessment on the proposed array calibration method is made based on the DOA estimations and current measurements that are obtained from the datasets that were collected with a multi-frequency HF (MHF) radar. MHF radar-estimated DOAs using three calibration strategies are compared with the ship directions that are provided by an Automatic Identification System (AIS). Additionally, comparisons between the MHF radar-derived currents while using three calibration strategies and Acoustic Doppler Current Profilers (ADCP)-measured currents are made. The results indicate that the proposed array calibration method is effective in DOA estimation and current measurement for phased-array HF radars, especially in the phase distortion situation.

Ultrasensitive Detection of Enzymatic Activity Using Single Molecule Arrays

Enzyme assays are important for many applications including clinical diagnostics, functional proteomics, and drug discovery. Current methods for enzymatic activity measurement often suffer from low analytical sensitivity. We developed an ultrasensitive method for the detection of enzymatic activity using Single Molecule Arrays (eSimoa). The eSimoa assay is accomplished by conjugating substrates to paramagnetic beads and measuring the conversion of substrates to products using single molecule analysis. We demonstrated the eSimoa method for the detection of protein kinases, telomerase, histone H3 methyltransferase SET7/9, and polypeptide N-acetylgalactosaminyltransferase with unprecedented sensitivity. In addition, we tested enzyme inhibition and performed theoretical calculations for the binding of inhibitor to its target enzyme and show the need for an ultrasensitive enzymatic assay to evaluate the potency of tight binding inhibitors. The eSimoa assay was successfully used to determine inhibition constants of both bosutinib and dasatinib. Due to the ultrasensitivity of this method, we also were able to measure the kinase activities at the single cell level. We show that the eSimoa assay is a simple, fast, and highly sensitive approach, which can be easily extended to detect a variety of other enzymes, providing a promising platform for enzyme-related fundamental research and inhibitor screening.

Research on a Composite Voltage and Current Measurement Device for HVDC Networks

With the global trend to develop digital substation automation systems, measurement devices are required to be reliable, of small size and light weight and of acceptable accuracy in a wide frequency band. This article presents a combined high voltage direct current measurement method which comprises the above-mentioned features that makes it suitable for smart grids protection and control applications. The proposed measurement method utilizes Hall sensor array for dc current measurement. DC voltage is measured using a voltage divider circuit while the harmonic currents are measured using a square Rogowski coil made of four straight bars along with a high precision digital integration algorithm. A four-spectral line interpolation fast Fourier transform algorithm based on trapezoidal convolution window is proposed to improve the extraction accuracy of the dc and harmonic components from the measured signal. Experimental results show that the error variation of the proposed method is less than 0.098% for voltage measurement while it is less than 0.104% for current measurement. The harmonic measurement ratio error is less than 0.2% and the angle error is less than 8'.

Large Dynamic Current Monitoring for UAV Steering Motor Using Twin Nonlinear Shunt

Steering motor is of vital importance in UAV’s health-monitoring system, to which its supply current is the most critical characteristic representing health statue of UAV. In order to conduct continuous measuring on the steering motor’s current of large dynamic range, in this paper, a current measurement method is therefore proposed on the basis of twin nonlinear shunt. The proposed method adopts the twin diode as the current sampling device, which not only realizes measurement range and relative constant resolution, but also ensures continuity of the measurement due to the eliminated operation of range switching. The associated diode is used to compensate the temperature of core temperature of the shunt diode, and to make the nonlinear-shunt more adaptive for the case of junction being heated under larger current. The working principle, real-time compensation method and circuit implementation of our method are discussed in detail. Experimental test results suggest that the measurement error of the proposed method is less than 4.5% when the measurement current varies between 10 mA to 10 A, maintaining the relative resolution at an almost constant level, while preventing the conventional method of frequent range switching from generating glitches. In addition to the ensured continuity, information-rich details of the current are sustained, contributing to the UAV’s health-monitoring system. The proposal can also be applied to other applications concerning large dynamic current detection, including, but not limited to, industrial control, motor control, etc.

New Method for Determining and Predicting Test Interconnect Pin Current Carrying Capacity

With new advances in the semiconductor technology, current carrying requirements for electronic packages and interconnects (sockets) are on the rise. Although there are a lot of documented methods for determining current carrying capacity (CCC) of electrical wires, there is no specific industry standard for determining current carrying capacity of socket pins and their contact interface with package balls and pads. This paper presents a new current carrying capacity measurement method, developed specifically to address the challenges of test socket pins and their contact interface with solder balls and pads. In addition, a method for predicting CCC in future test socket pins is presented and correlated to measured data.

P‐230: Late‐News‐Poster: Evaluations of Lithium‐Fluoride Behavior in OLEDs by Means of Cyclic‐Displacement Current‐Measurement Method

We propose a cyclic displacement current measurement method to investigate the behavior of lithium fluoride (LiF) in OLEDs by applying a cyclic voltage and measuring a repeatable current. We found that a LiF layer reduces electron injection barrier, increases a hole injection barrier, and improves the discharge process. This method allows us to clarify the charge injection process of OLEDs in detail.

Current measurement and control method of HVAC integration systems through DC link single current sensor

The HVAC (Heating, Ventilation & Air Conditioning) system of an electric vehicle consists of an electric compressor including PMSM (Permanent Magnet Synchronous Machine) and a PTC (Positive Temperature Coefficient) heater. Each of these systems is configured independently. This paper proposes an HVAC system that integrates the compressor control system and the heater control system. The system shares an input noise filter, DC link capacitors, and a controller that includes an MCU. In addition, several of the current sensors in each system are replaced with a single current sensor in the DC link. In a typical cooling sequence that uses only a compressor, the integration system can use conventional single shunt control to restore the three-phase current and to control the speed of the compressor. However, the system cannot be controlled by the conventional method of only measuring current in the effective vector in operation, where the compressor and the heater are used together to increase heating performance. The proposed method measures the DC link current in the zero vector as well as the effective vector, and separates the compressor current and the heater current. Therefore, the compressor and the heater can be simultaneously controlled by one current sensor even in operation using the compressor and the heater. The effectiveness of the proposed system and control method are verified through experiments.