Open-circuit Method Research Articles

Electromagnetic radiation suppressor based on Co-Ti doped strontium lanthanum hexaferrite for Ku-Band applications

In this proposed work, we report Co-Ti doped Strontium-lanthanum M−type hexaferrites with general chemical formula, Sr0.85La0.15(CoTi)0.5Fe11O19 and Sr0.85La0.15(CoTi)0.75Fe10.5O19 prepared by citrate auto-combustion method. Complex permittivity, complex permeability and microwave absorptive properties of fabricated ferrite compositions were analysed in 12.4 to 18 GHz frequency range (Ku-Band). The XRD (X-ray diffraction) pattern of Co-Ti substituted compositions show single-phase M−type hexagonal ferrite indicating this co-substitution maintained the crystal phase structure. The grain diameter (average) decreased from 587 nm to 290 nm and 415 nm to 318 nm for ferrite samples with composition x = 0.50 and x = 0.75 respectively after 20 hours of ball-milling. The reflection loss (RL) exhibited the absorption bandwidth of more than 90 % (−10 dB) of value 2.41 GHz and 1.2 GHz for fabricated ferrites with chemical composition Sr0.85La0.15(CoTi)0.5Fe11O19 and Sr0.85La0.15(CoTi)0.75Fe10.5O19 respectively.. Both dielectric loss tangent and magnetic loss tangent contributed to enhance total loss tangent which represents microwave absorbing properties of the prepared ferrite samples. Reflection coefficient (S11) values for open circuit method also shows absorption bandwidth (−10 dB) of more than 90 % for these ferrites. Double layer electromagnetic absorber was simulated and observed improved reflection loss and absorption bandwidth. Therefore, these suggested ferrite samples have potential to be used as electromagnetic wave absorbing material of both single and double layer at higher frequency range.

Innovative measurement and noise reduction of voltage coupling in shielded cables for enhanced signal integrity

The reliable transmission of electrical signals through shielded cables in the presence of electromagnetic interference (EMI) remains a critical challenge for signal integrity. This paper presents a novel and comprehensive approach for measuring and reducing voltage coupling in shielded cables connected to a shielded room from a waveguide. Additionally, we introduce an innovative active EMI filter to effectively mitigate common-mode (CM) and differential-mode (DM) noises, thereby enhancing the overall signal quality. To address the issue of voltage coupling, an open circuit method with a transmission line is considered for the measurement of output voltage at the end of the shielded cable. In order to assess the impact of EMI on transmitted signals, we utilize a state-of-the-art noise separator that enables precise differentiation and characterization of CM and DM noise components. This analysis provides valuable insights into the overall noise profile, guiding the subsequent steps toward noise reduction. An active EMI filter was designed to effectively attenuate the unwanted noise. The filter intelligently targets and mitigates both CM and DM noises, resulting in improved signal integrity. The experimental setup encompasses a shielded room, shielded cables, a waveguide, and the equipment. The obtained output voltage from the shielded cable is 495 V. It is given as an input to the equipment (Cuk converter). The noises are generated when the input voltage is given; the noises are separated by using a noise separator. CM noise obtained at the output of an active noise separator is 118.8 dBµV. DM noise obtained at the output of a differential mode noise separator is 115.8 dBµV. With the active EMI filter, we achieve remarkable reductions in CM and DM noise levels. After adding a filter to the circuit, the noises are reduced below the limit line according to the International Special Committee on Radio Interference standard; the CM noise is 44.8 dBµV and the DM noise is 47.8 dBµV.

Analisis Aliran Daya Reconductoring Saluran Transmisi Paiton Kraksaan-Probolinggo 150 kV Terhadap Saluran Yang Terimbas

Provision of quality and sufficient electrical energy is something that must be done by PT. PLN (Persero). Based on data from PT. PLN (Persero), carried out work on replacing conductors on the Paiton – Kraksaan – Probolinggo transmission line from the TACSR 330 mm2 conductor with KHA 1190 A to 2xACCC/TW Copenhagen with KHA 2016 A. Reconductoring work is one of the efforts to uprating the transmission line by considering increasing load requirements. This reconductoring is carried out using the open circuit method or a total blackout in a circuit where the conductor is being replaced by taking into account the stages determined by PT. PLN (Persero). So that the power flow in the system must be considered when these conditions take place for the sake of service reliability or system reliability using a power flow simulator application, namely ETAP software. The simulation voltage tolerance with actual conditions is 5%. Next, analyze the power flow on the affected transmission line which is directly connected to the Kraksaan – Paiton – Probolinggo 150 kV transmission line based on voltage drop, transmission line losses and loading from each stage. As well as calculating the power transfer capability after and before reconductoring. The results of the simulation show that the most significant anomaly (deviation that should not be) is that there is a critical point loading of up to 89.220% on the Probolinggo - Gondangwetan channel when reconductoring has been carried out except for the Paiton - Kraksaan1 transmission line. Meanwhile, the value of power transfer capability increased after reconductoring, where the Paiton-Kraksaan1 and Paiton-Kraksaan2 channels increased by 63.91 MW, the Kraksaan - Probolinggo1 channel increased by 67.95 MW, and the Kraksaan - Probolinggo2 channel increased by 63.461 MW from previously

Analisis Aliran Daya Reconductoring Saluran Transmisi Paiton Kraksaan-Probolinggo 150 kV Terhadap Saluran Yang Terimbas

Provision of quality and sufficient electrical energy is something that must be done by PT. PLN (Persero). Based on data from PT. PLN (Persero), carried out work on replacing conductors on the Paiton – Kraksaan – Probolinggo transmission line from the TACSR 330 mm2 conductor with KHA 1190 A to 2xACCC/TW Copenhagen with KHA 2016 A. Reconductoring work is one of the efforts to uprating the transmission line by considering increasing load requirements. This reconductoring is carried out using the open circuit method or a total blackout in a circuit where the conductor is being replaced by taking into account the stages determined by PT. PLN (Persero). So that the power flow in the system must be considered when these conditions take place for the sake of service reliability or system reliability using a power flow simulator application, namely ETAP software. The simulation voltage tolerance with actual conditions is 5%. Next, analyze the power flow on the affected transmission line which is directly connected to the Kraksaan – Paiton – Probolinggo 150 kV transmission line based on voltage drop, transmission line losses and loading from each stage. As well as calculating the power transfer capability after and before reconductoring. The results of the simulation show that the most significant anomaly (deviation that should not be) is that there is a critical point loading of up to 89.220% on the Probolinggo - Gondangwetan channel when reconductoring has been carried out except for the Paiton - Kraksaan1 transmission line. Meanwhile, the value of power transfer capability increased after reconductoring, where the Paiton-Kraksaan1 and Paiton-Kraksaan2 channels increased by 63.91 MW, the Kraksaan - Probolinggo1 channel increased by 67.95 MW, and the Kraksaan - Probolinggo2 channel increased by 63.461 MW from previously.

Analysis and fault-tolerant control of inter-turn short-circuit fault for five-phase permanent-magnet synchronous machine

For the demand of high reliability in the aerospace field, multi-phase electric machines have become a research hotspot for the fault-tolerant ability. Inter-turn short-circuit fault is one of the main fault forms in the electric machine. The fault mechanism, diagnosis method and fault-tolerant control strategy of inter-turn short-circuit fault of the open-winding five-phase permanent-magnet synchronous machine that is used as the starter/generator system are studied in this paper. Firstly, the fault mechanism of the inter-turn short-circuit fault (ITSCF) is analyzed. The characteristics of phase voltage, inter-turn short-circuit current and torque ripple are compared using the phase winding open-circuit method and the phase winding short-circuit method. Secondly, a fault diagnosis method based on the information fusion is proposed, which determines the fault phase firstly and then identifies the inter-turn short-circuit ratio. According to the fault mechanism, a fault-tolerant control method is proposed, in which the accurate inter-turn short-circuit ratio and inter-turn short-circuit current are not required. The proposed fault-tolerant control method has similar torque ripple compared with the control method using accurate inter-turn short-circuit ratio and inter-turn short-circuit current. Finally, the effectiveness of the proposed fault-tolerant control method has been verified by experimental results.

Measurement and Safety Criteria of Step Voltage of High Voltage Direct Current Grounding Electrode

Grounding electrode is an indispensable part in HVDC transmission projects. During its design and safety evaluation, step voltage is a crucial aspect. By reviewing and sorting out the present standards involving step voltage measurement and its safety limit, this paper illustrates the contradiction between the measurement methods and the safety evaluation. Reasons for the contradiction are explained by analyzing the principal of step voltage measurement and safety evaluation. The Open-circuit step voltage measurement method and the measurement method with a human body equivalent resistance paralleled are compared to find out their advantages and disadvantages. Suitable circumstances and corresponding safety criteria of these two methods are put forward. Method proposed in this paper can be applied to step voltage measurement and safety evaluation of HVDC grounding electrode, providing reference when revising the related standards.

Application Error Analysis of SOC Estimation of Pure Electric Vehicles Based on Kalman Signal Big Data Algorithm

The state of charge estimation of a pure electric vehicle power battery pack is one of the important contents of the battery management system. Improving the estimation accuracy of the battery pack’s SOC is conducive to giving full play to its performance and preventing overcharge and discharge of a single battery. At present, the open-circuit voltage ampere-hour integral method is traditionally used to estimate the SOC value of the battery pack; however, this estimation method is not accurate enough to correct the initial value of SOC and cannot solve the problem of current time integration error between this correction and the next correction. As for the battery performance and characteristics of electric vehicles, it is pointed out that the size of the model value will affect the estimation accuracy of the Kalman signal value. Based on the analysis of the factors to be referred to in the calculation and estimation of SOC by Kalman for pure electric vehicles, the scheme is improved considering the change of battery model value, and the Kalman scheme is proposed. The feasibility and accuracy of the scheme are proved by several battery simulation experiments.

A novel IGBT open-circuit protection method for three-phase PWM rectifier

A novel IGBT open-circuit protection method for three-phase PWM rectifier

A novel IGBT open-circuit protection method for three-phase PWM rectifier

In order to avoid the damage or the secondary fault caused by serious over-current, a new solution for protection of IGBT open-circuit faults in three-phase PWM rectifier is presented in this paper. Firstly, the open-circuit faults features of three-phase PWM rectifier have been analysed, and it was found that the most obvious features of open-circuit faults in three-phase PWM rectifier are the rise of some phase currents and the drop of DC voltage. Secondly, compared with the maximum and minimum absolute values of phase currents under normal state, one of them always can be 1.3 times larger than that of normal state when open-circuit faults occur in IGBTs except all IGBTs. Finally, by observing the DC voltage and the currents' behaviour, the maximum-minimum values-based method can detect the open-circuit faults of the system. The experiment results have verified that the method can effectively detect the open-circuit faults in IGBTs and protect the system.

Development and experimental validation of fault detection and diagnosis method in SPWM modulated symmetric cascaded H-bridge multilevel inverter

This paper discusses gate open-circuit fault detection and diagnosis method in SPWM modulated symmetric cascaded H-bridge multilevel inverter. First, an output voltage modelling under fault condition in cascaded H-bridge multilevel inverter is presented. Further, simulations of fault conditions have been carried out for the development of the fault detection and diagnosis method. Based on fault modelling and simulations, a fault detection and diagnosis method have been proposed based on the mean values of the bridge voltages as the diagnostic feature. Further, the proposed method has been validated experimentally on a 5-level symmetric sine pulse width modulated cascaded H-bridge multilevel inverter.

Spirometryin Smokers and Non-smokers: A Comparative Study

Introduction : Spirometry is the process of recording volume of air that moves into and out of the lungs. It is a physiological test that measures how an individual breathes air volumes as a function of time. It provides an objective and quantitative measure of lung function. Smoking produces increase in epithelial damage, cellular inflammatory infiltrates, muscles and fibrosis in respiratory airways and is responsible for acute respiratory illnesses including pneumonia, impaired lung growth, early onset decline in lung function, poor asthma control, chronic obstructive pulmonary disease (COPD). Early identification of reduction in lung function of smokers by spirometry can be very important in order to encourage them to stop smoking.
 Methods: This study included a total of 106 individuals, 51 were smokers and55 were non-smokers. The participants performed spirometry in the sitting position by open circuit method. Parameters of spirometry FVC, FEV1, FEV1/FVC and PEFR were recorded collected in the form of percentage of predicted.
 Results: The mean FVC in smokers and non-smokers were 99.98±9.88% and 102.97±8.03% respectively (p=0.092). The mean FEV1 in smokers and non-smokers were 99.65±9.61% and 104.58±10.03% respectively (p=0.011). The mean FEV1/FVC ratio in smokers and non-smokers were 103.25±4.60% and 105.57±5.10% respectively (p=0.016). The mean PEFR in smokers and non-smokers were 102.11±8.40% and 106.01±10.62% respectively (p=0.038).
 Conclusion: The spirometry parameters of pulmonary function were better in non-smoker group. Spirometry can be useful in detecting reduction in pulmonary function before appearance of any symptoms or before pulmonary functions become significantly abnormal.

A Comparison of Methods to Measure the Coupling Coefficient of Electromagnetic Vibration Energy Harvesters

Vibration energy harvesters transform environmental vibration energy into usable electrical energy. The transformation is only possible because of a coupling between the mechanical part of the energy harvester and the electric circuit. This paper compares several measurement methods to determine the electromagnetic coupling coefficient. These methods are applied to various implementations of an energy harvester and the results are compared with one another and with simulation data by analyzing the magnetic flux. The average deviation between the measurement methods and the simulation data in our study was 5%. This good agreement validates the methods. Based on this, we recommend determination of the coupling coefficient and the optimum load resistance for maximum power harvesting on the basis of simulations and the open circuit method, because this procedure leads to the shortest measurement times.

An Open-Circuit Method to Control the Hysteresis Parameters of Rare-Earth Permanent Magnets

Abstract—The peculiarities of application of the open-circuit method and prospects for development of technological equipment for monitoring the hysteresis parameters of permanent magnets from highly coercive hard magnetic material have been considered using complex-shaped samples in the pulse magnetic field. The advantages of the open magnetic circuit method and problems that occur during the development of technological equipment have been shown. Based on an analysis of foreign and domestic publications, it has been concluded that the direction is promising. The information on design features, characteristics of the developed equipment for processing control over permanent magnets from hard magnetic materials have been presented.

Temperature Effects on Calendar Aging of Lithium-Ion and Nickel Metal Hydride Batteries

The effect of temperature on the calendar aging of commercially available 3.25 Ah Lithium-Ion (Li-Ion) and 2.30 Ah Nickel Metal Hydride (Ni-MH) batteries were investigated. Calendar life tests were carried out using open circuit method at -20°C, 20°C and 55°C temperatures and initial state of charge (100% SOC). It is found that the aging of the batteries increases with increasing temperature and storage time.

Current residual‐based method for open‐circuit fault diagnosis in single‐phase PWM converter

This study presents an open-circuit fault diagnosis method based on residual changing rate instead of the specific switching signals injection for single insulated gate bipolar transistor in the single-phase pulse-width modulation (PWM) converter. Firstly, the mixed logical dynamic model of the single-phase PWM converter is established to obtain the residual of grid-side current. Then, the characteristics of residual changing rate are obtained through the combination of theoretical analysis and simulation results. Furthermore, the diagnostic variables based on the residual changing rate are defined by the isolation of switching signals. Also compared with the threshold, fault detection and location can be accomplished. The proposed diagnosis method does not need extra sensors and injection of special switching signals, which can reduce the diagnosis complexity and does not affect operating state of the system. Furthermore, the diagnostic method has fast diagnosis speed and robustness against false alarms under different operation conditions. Experimental results have illustrated the validity and feasibility of the proposed diagnostic method.

State of charge estimation of power Li-ion batteries using a hybrid estimation algorithm based on UKF

Based on the analysis of the existing State of charge (SOC) Estimation Algorithms of batteries, this paper proposes a hybrid estimation algorithm according to the UKF method, the Ah method and the open circuit method in SOC estimation of battery pack which consists of 320 batteries. The “buckets effect” exists between series batteries and the differences between each cell were also been taken into consideration during estimating the SOC of power batteries. Finally, the hybrid estimation algorithm was applied to estimate SOC of battery pack under ECE driving cycles. The result shows that the error of the hybrid estimation algorithm is less than 5%.

Complex Microwave Permittivity of Secondary High Explosives

AbstractWe aim to understand how microwaves interact with high explosives by studying the complex permittivity from 1–18 GHz of HMX, RDX, TNT, TATB, PETN, Octol, Comp B, 95 % RDX/5 % Viton A (PBX‐RDX), PBX 9404, PBXN‐5, PBXN‐7, PBXW‐14, PBX 9501, and PBX 9502. The combination of a resonant cavity perturbation technique for determining the room‐temperature complex dielectric constant at discrete frequencies and a wide band open circuit method (1–18 GHz) provides an accurate, broadband measurement that describes the dielectric properties in the frequency range of interest. While the values of the real and imaginary permittivity components did not vary significantly as a function of frequency, we found the real part of the permittivity to be highly dependent on relatively small changes in the material density. We used dielectric mixing theory, specifically the linear‐law approximation, to compare the predicted values based on the dielectric properties of individual components with those of the resulting formulation measured experimentally for a select number of samples; the prediction agrees well within the observed variability of the experimentally measured values.

Open-Circuit Fault Diagnosis and Fault-Tolerant Control of IPMSM System

The integrated mathematical model of an interior permanent magnet synchronous machine (IPMSM) system is set up suitable for healthy state, open-circuit fault state and fault-tolerant state in this paper. An on-line open-circuit fault diagnosis method is proposed, the fault-tolerant structure is set to connect the fault phase to the middle of DC link, considering that DC link voltage is not balanced, therefore, an optimized adaptive space vector pulse width SVPWM of four-switch three-phase inverters (FSTPI) under DC-link voltage ripple condition is presented to achieve the maximum torque per ampere (MTPA) control and flux weakening control of the IPMSM system under the fault-tolerant state. Based on the abovementioned research, system simulations are implemented and simulation results are given.

Direct Measurement of Carrier Mobility in Intrinsic Channel Tri-Gate Single Silicon Nanowire Metal–Oxide–Semiconductor Field-Effect Transistors

In this paper, we report the direct measurement of intrinsic carrier mobility in “single”-silicon-nanowire metal–oxide–semiconductor field-effect transistors (MOSFETs) for the first time. To obtain intrinsic carrier mobility with high accuracy by the split capacitance–voltage (C–V) method, ultralong single-silicon-nanowires, instead of multiple parallel nanowires, were designed and fabricated. The open-circuit method was utilized to remove the parasitic effect in measured capacitance. It is found that, although mobility degradations in narrower nanowires are seen in both electrons and holes, the hole mobility is higher than the universal mobility on the (100) surface even in a “single”-nanowire thanks to the high hole mobility on the (110)-oriented side surface of the [110]-directed nanowire. The extracted mobility indicates that surface orientation plays a key role in nanowire mobility.

Corrosion Behavior of Ultra Fine Grain Pure Magnesium for Automotive Applications

The contemporary challenge in automotive industry is weight reduction. Compared to conventional automotive materials, commercially pure magnesium is having enhanced strength-to-mass ratio and low density, which confers to optimal requirement for automotive applications. Amongst various other reasons such as low hardness, low corrosion resistance also prevents it from entering mass production .severe plastic deformation by equal channel angular extrusion (ECAE) is regarded as one of the prominent method to increase the mechanical properties of magnesium. However, the investigation in corrosion resistance of extruded magnesium in automotive environment is not discussed in depth. This paper discusses the microstructure and corrosion characteristics of commercially pure magnesium which has been extruded by ECAE at 473k through the routes a and bc up to eight passes and their three surfaces (extrusion direction, normal direction & transverse direction) in detail. The corrosion experiment has been performed using conventional electrochemical techniques such as open-circuit potential measurements and potentiodynamic polarization method in 3.5 wt% Nacl solution environment. The surface morphology of the magnesium billet was examined in detail using scanning electron microscopy (SEM) and the hardness was measured using micro Vickers hardness tester.