Inductive Voltage Research Articles

Synchronous rectification of LLC resonant converters based on resonant inductor voltage

Synchronous rectification (SR) technology has been a critical technology for LLC converters to achieve high efficiency and power density. However, conventional SR driving methods face challenges in terms of light-load condition, module size, switching accuracy, and circuit complexity. This paper proposes an SR driving strategy based on resonant inductor voltage (RLV) to address those issues. This RLV-SR driving strategy does not require current sensors and is insensitive to rectifier parasitic parameters. In addition, the RLV-SR driving strategy can be applied in a relatively wide operating frequency range and load conditions. Experimental results based on a 100-W/24-V LLC converter are presented to verify the effectiveness of the proposed RLV-SR driving strategy. Furthermore, the error of turn-on time caused by stray inductance is significantly reduced compared with the conventional VDS-ON sensing method, which improves the power converter’s efficiency.

Analisa Karakteristik Generator Sinkron Terhadap Perubahan Beban Daya Aktif

Generators are electric machines that are used as generators of electrical energy, namely converting mechanical energy into electrical energy. Mechanical energy is obtained from the primover which can be a diesel engine, or something else. In large generators, conversion tools are often used, namely synchronous generators. so that the performance of the generator to be optimal it must be maintained stability. The purpose of this study is to examine and see the performance of synchronous generators against changes in active power load. From the analysis results, it is found that the lowest excitation current is 2.6 A, the reactive power is 1 MVAr, the highest excitation current is 6.08 A, the reactive power is 1.7 MVAr. When the excitation current is 6.08 A, the induced voltage is 16.12 kV. The Armature Current is 494.45 A, the Induction Voltage is 15.21 kV and the highest Armature Current value is 1,372.90 A with an Induction Voltage of 16.12 kV, the Induction voltage, the calculation results are 12.53 kV with an Active Power of 26 MW, the value of the Armature Current is 1,306 .62 A and the highest Induction Voltage is 16.54 kV, Active Power is 10 MW, Armature Current is 503.02 A

A Comprehensive Small-Signal Model Formulation and Analysis for the Quasi-Y Impedance-Source Inverter

This paper presents a detailed derivation of the small-signal model and components design considerations for the Quasi-Y-Source inverter. The design methodology is based on the converter steady-state operation, considering the impedance network inductor and capacitor voltage and charge balances, respectively. Moreover, the additional design criteria for component selection, considering control constraints and performance compromise, are given by parametric variation analysis based on converter dynamic response. The small-signal model and transfer functions are obtained using a state-space averaged model, including converter non-ideal characteristics given by equivalent-series resistances (ESR), which makes possible the proposition of different control strategies, using both single or multi-loop schemes. To demonstrate the usefulness of the proposed small-signal model, a DSP-based single-loop type-II PI control strategy is used in which the peak DC-link voltage is indirectly controlled through the measurement of the impedance network capacitor voltage. The controller and converter performances are verified with simulation and experimental results and successfully confirm the validity of the proposed dynamic model. Finally, the obtained results are validated with a built small-scale three-phase/three-wire inverter prototype.

A numerical method to calculate screening current-dependent self and mutual inductances of REBCO coils

The screening current and its relaxation cause the variation of the self- and mutual inductances of REBCO coils—REBCO is one of the high-temperature superconductors. However, most studies of coil voltage analysis on a REBCO magnet, a stack of coils, have reported simulation results assuming invariant self- and mutual inductances so far. Although the conventional assumption of invariant inductances is still acceptable for fundamental coil voltage analyses, it can cause misleading conclusions due to inductive voltage errors when a precise coil voltage analysis is demanded. Hence, here we report a numerical method to calculate screening-current-dependent self- and mutual inductances of REBCO coils for advanced studies based on a lumped-circuit analysis model. In this work, we aim to investigate the inductance variation due to the screening current with a case study and discuss its effects on the coil voltage. We assume that there is a stack of 12 REBCO single-pancake coils. No transverse current in each coil is considered for simplicity. A numerical simulation of the current density in the magnet is performed, and then the inductances are calculated by considering the spatially non-uniform current density due to the screening current. From this case study, we confirm that the self- and mutual inductances are changed by up to 110% and 30% each. It is also confirmed that the discrepancy is notable at the beginning of the charge while marginal at the end. Finally, we discuss the effect of inductance variation on the quench voltage analysis.

Underground Displacement Measurement Method Based on Double Mutual Inductance Voltage Contour Model of Optimized Dual Kriging

Landslide is a common geological hazard. Existing displacement monitoring sensors for landslides are classified into surface displacement and underground displacement. However, current underground displacement sensors cannot effectively monitor the vertical displacement caused by soil accumulation of landslides, which cannot meet the needs of landslide monitoring. Therefore, this study has designed a three-dimensional underground displacement measurement sensor based on the double mutual inductance voltage contour method. Since the double mutual inductance voltage measurement model has low measurement accuracy due to low interpolation accuracy and complex location calculation method when solving the spatial position, the improved Dual-Kriging interpolation method based on quantum pigeon inspired algorithm is adopted to improve the original interpolation accuracy. The experimental results show that this method avoids the complex problem of Kriging interpolation calculation and improves the calculation speed. At the same time, the overall accuracy is significantly improved, reducing its fitting error and actual value to a maximum of three ADC12 resolutions. The landslide experiment on the landslide simulation experiment platform shows that the sensor can effectively reflect the displacement of underground soil, and has important application value for slope displacement monitoring.

An SC-Parallel-Inductor Hybrid Buck Converter With Reduced Inductor Voltage and Current

This article presents a switched-capacitor (SC)-parallel-inductor buck (CPL-Buck) converter with reduced inductor voltage and current. The proposed CPL-Buck converter reduces the voltage stress on the power inductor with a series-connected flying capacitor in one phase, alleviating the current stress with a parallel-connected SC path in both phases. Therefore, it effectively lowers the average inductor current as well as its ripple, allowing the utilization of a small-volume inductor to deliver a large output current. In addition, to cover a wide voltage conversion ratio (VCR) range, the proposed CPL-Buck is able to operate in either a sub-1/3X mode or a sub-1/2X mode. This work, fabricated in 65-nm CMOS, occupies an area of 2.72 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}$</tex-math> </inline-formula> . Measurement results show that the proposed CPL-Buck obtains a peak efficiency of 92.9% and a peak current density of 0.3 A/mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}$</tex-math> </inline-formula> with a power inductor as small as 1.6 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 0.8 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 0.8 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{3}$</tex-math> </inline-formula> , with an input range of 3–4.2 V, an output range of 0.6–1 V, and 1.2-A maximum output current.

Universal Synchronous Rectification Scheme for LLC Resonant Converter Using Primary-Side Inductor Voltage

In recent years, many advanced modulation strategies have been applied in LLC resonant converters, resulting in the increased demand for the synchronous rectification (SR) schemes without modulation strategy limitation. However, the conventional universal SR schemes are mainly on the basis of primary/secondary side current or drain-source voltage of synchronous rectifiers, which are limited by high cost of current transformer (CT) and loss of duty cycle caused by parasitic inductance, respectively. To deal with these problems, this paper proposes a novel SR scheme for LLC resonant converter. Firstly, a SR analysis method on the basis of the idea of power transmission is proposed. It can decouple SR from modulation strategy. Based on this method, this paper proposes a universal SR scheme using primary-side inductor voltage. The scheme is no longer restricted by the modulation strategy of converter. Meanwhile, no CT is required, thereby reducing the cost and conduction loss. Thanks to the large signal sensing-based, this scheme has good noise immunity. Moreover, it eliminates the negative effect of parasitic inductance by integral operation. With these effects, it has high accuracy of SR. Furthermore, an easily-debugged analog implementation is designed, which only needs to adjust one component parameter. Finally, experimental results show that the proposed scheme is compatible with different modulation strategies, and it has higher efficiency than the commercial SR scheme in a wide range of operating conditions.

An Equivalent Differential Method for Active Damping of LCL Type Grid-Connected Inverters With Grid-Side Inductor Voltage Feedback

The differential feedback of grid-side inductor voltage can effectively increase the damping of grid-connected inverters. Compared with proportional feedback of filter capacitor current, it can increase the output impedance of the grid-connected inverters, which is more conducive to reducing the impact of grid background harmonics on the grid-in current. However, there is a differential link in its damping branch, and existing differential implementation methods were pursuing to be ideal differential in wide frequency band, as a consequence, high frequency components of the grid-side inductor voltage are amplified, which affects the quality of grid-in current. For this reason, this paper proposes a band-pass filter in series with a lead compensation unit to replace the ideal differential. The major advantage different from the conventional methods is that the proposed strategy is only equivalent to the ideal differential around the resonance frequency band. Specifically, it features lower gain at low and high frequency bands. Finally, theoretical analysis and experiment results show that the proposed strategy can reduce the influence of the added damping path on the fundamental component of grid-in current and features better suppression effect on the harmonics.

Study on Characteristics of Electromagnetic Interference Caused by Metro Train Movement

With the rapid development of the urban power grid and metro system, their mutual influence has become more and more serious. The dc magnetic bias of the transformer caused by the metro becomes the main research direction. In this paper, the characteristics of dynamic electromagnetic coupling between metro trains and transmission lines are studied. First, the motion equation of the metro is written out according to the running law of the train, and three coupling relations are given according to the position of the train. The calculation method of dynamic induced voltage is deduced. Then the influence of parallel length and distance between the metro and transmission line on induced voltage is studied. The dynamic induction voltage increases first and then decreases with the increase of the parallel length of the metro and transmission line and decreases with the increase of the distance between them. It is proposed that the electromagnetic coupling of a single train has limited influence on the dc magnetic bias of transmission lines, but the influence of dynamic electromagnetic coupling cannot be ignored when multiple trains are running simultaneously.

AC Motor Monitoring and Controlling Using IoT

The design of IOT technology is shown to monitor and diagnose the performance of a three-phase induction motor and record crucial operational characteristics. Today's technology is rapidly tied to the Internet of Things (IOT), keeping things connected efficiently. For the purpose of gathering and processing induction motor parameters, the solutions given include an IOT-based platform. The parameters are made up of sensors, including humidity, temperature, voltage, and current sensors. With the help of the pocket IOT application, this data may be shown on a smartphone, accessed via web sites, and stored in a cloud platform. It will be promptly informed if performance limits are exceeded. To prevent motor downtime, an induction motor can be checked and immediate action taken can save money and time. Utilising IOT to monitor induction motors has several benefits, including notification of problem alerts and historical data for preventative maintenance. Recent technological advancements have greatly improved the quality, speed, and ease of our lives. This article explains how to manage and control induction motors (IOT) using the Internet of Things. The IOT is more effective and convenient for controlling systems because it can be used from anywhere via Wi-Fi. This intelligent system's main objective is to prevent induction motor failure by taking preventive measures. Because of its many benefits, including their self-starting nature, low cost, high power factor, and robust construction, induction motors are utilised in a wide range of applications, including those for electric vehicles, businesses, and agricultural areas. In order to maximise motor efficiency and assure safe and reliable operation, it is crucial to identify defects in motors as soon as possible using the best smart protection approach currently available. Remote monitoring is possible for the induction motor's speed, voltage, current, temperature, humidity, and other electrical, mechanical, and environmental parameters because errors in these areas seriously damage the motors and have an impact on the induction motor's ability to function in other applications. In this system for monitoring and controlling Induction using IOT, a number of sensors are employed to acquire the motor data in real-time and a relay is used to control the motor. The proposed system will collect and analyse induction motor parameters in real-time using an IOT-based platform.

Simulation and Optimization Design of Inductive Wear Particle Sensor.

In order to monitor the diagnosis of mechanical equipment by monitoring the metal wear particles carried in large aperture lubricating oil tubes, the simulation optimization structure design was carried out based on the traditional three-coil inductance wear particle sensor. The numerical model of electromotive force induced by the wear particle sensor was established, and the coil distance and coil turns were simulated by finite element analysis software. When permalloy is covered on the surface of the excitation coil and induction coil, the background magnetic field at the air gap increases, and the induced electromotive force amplitude generated by wear particles is increased. The effect of alloy thickness on the induced voltage and magnetic field was analyzed to determine the optimum thickness, and increase the induction voltage of the alloy chamfer detection at the air gap. The optimal parameter structure was determined to improve the detection ability of the sensor. Ultimately, by comparing the extreme values of the induced voltage of various types of sensors, the simulation determined that the minimum allowable detection of the optimal sensor was 27.5 µm ferromagnetic particles.

The Phasor Diagram of a Superconducting Synchronous Electrical Machine

This paper describes a universal method proposed by the author for the evaluative analytical calculation of the main parameters of synchronous electrical machines, including superconducting ones. Traditional methods for analytical calculation of parameters to build a phasor diagram of electrical machines require a calculation of all dimensions of the active zone, tooth-slot zone and frontal parts of armature windings. All sizes and local states of magnetic circuit saturation are necessary for the calculation of magnetic conductivities. Traditional analytical methods use, among other things, empirical formulas and non-physical coefficients and allow one to calculate only standard machines with classic tooth-slot zones and armature winding types. As a result of drawing a phasor diagram using traditional methods, the angle between the electromotive force and voltage is calculated, which is the machine’s internal parameter and has no major significance for users. The application of modern computer programs for simulation requires a preliminary analytical calculation in order to obtain all dimensions of the three-dimensional model. FEM simulation programs are expensive, require expensive high-performance computers and highly paid skilled personnel. Fast analytical techniques are also required to assess the correctness of the obtained automatic computer simulation results. The proposed analytical method makes it possible to quickly obtain all the main parameters of a newly designed machine (including superconducting ones and those of non-traditional design) without a detailed calculation of the dimensions of the tooth-slot zone and armature end-windings. The characteristic values of load angles are set according to the results of simple calculations, and the desired values, obtained via plotting, represent the inductive resistances of armature winding and inductive voltage drop across it. Results of practical significance, calculated from the voltage diagram, are as follows: the inductor’s magnetomotive force necessary to maintain the nominal load voltage value, regardless of the magnitude (including double overload) and type of the connected load, or the main dimensions of the active zone.

Assessment of Multi-Phase Conversion and Modified PWM Strategy for Power Converters of Medium-Voltage Induction Motors Drive

Multi pulse and multilevel converters show great potential for use in medium voltage induction motor drive systems due to cascaded design and high-quality output. However, variable-speed medium voltage drives have demanding requirements in enhancement number of pulses with less number of DC sources and converter topologies with reduced component counts. This paper utilizes the phase displacement technique as well as the three-phase to five-phase conversion technique so that the drive system extracts 30-pulse current from the grid supply, which helps to enhance the power quality at the grid end. In this paper, a 30-pulse AC-DC converter based on a 10-pulse converter is designed and implemented to feed a power 4-level cascaded inverter through three DC sources. Apart from this, a modified carrier-based LSPWM technique is used to enhance the performance of the MLI at a low switching frequency. An indirect field-oriented control (IFOC) method is utilized to address the issues of the drive system during dynamic operations. Performance analysis through theoretical and simulation by using the full-scale model is evaluated in terms of voltage and current quality, speed and torque response, losses, and efficiency. Experimental verification is also carried out on a 7.5kW, 415V laboratory prototype using a digital signal controller for implementation of the control scheme.

Reconstructing Primary Voltage Across Inductive VTs—Part II: Validation, Application, and Analysis

This two-part paper presents an inverse method to reconstruct the primary voltage of a VT from the available distorted secondary signals. In this second part, the performance of the proposed inverse method is validated by simulation using a 10 kV inductive voltage transformer (VT). Additionally, four laboratory experiments are performed to show the potential applications of the proposed method. These experiments closely represent realistic field conditions. The simulation and experimental results verify the accuracy and reliability of the method. The robustness and parameter accessibility are discussed. The novel inverse method provides an effective solution for the accurate reproduction of high-frequency transients and low-frequency over-voltages measurements. Furthermore, the reconstructed primary voltage waveforms provide usable data for the study of voltages in power systems.

Reconstructing Primary Voltages Across Inductive VTs — Part I: Methodology

Inductive voltage transformers (VTs) are the most widely used instrument transformers in power grids operating at 35 kV and below. Frequently, however, during disturbances, the secondary signals are not replicas of the primary voltages because of eddy current effects, capacitive effects, and nonlinearities. In this two-part paper, a new inverse method considering the frequency-dependent characteristics and nonlinearities is proposed to reconstruct the primary voltage from a distorted secondary signal. In Part I, the framework of the method is presented and then realized with two inverse models. An inverse black-box model is used to compensate the eddy currents and capacitive effects, and an inverse duality-derived model is used to consider the nonlinearities. Methods for model parameter determination are described. Experimental validation and analysis of the proposed method are afforded in Part II. The inverse method effectively improves the primary voltage measurement of VTs without any auxiliary high-voltage equipment. The proposed method provides accurate primary voltage waveforms of VTs during disturbances.

Методы расчета и оценки термоэмиссионного плазменно-капельного генератора с магнитной сепарацией заряда

The development of design solutions and preliminary calculation substantiation of the characteristics of a high-voltage plasma-drop generator with magnetic charge separation have been completed. The aim of the study was to confirm the possibility of creating a current source with an operating voltage of about 107 V. The proposed energy conversion method is based on the separation of charged drops from dusty plasma in a gradient magnetic field. Droplets are charged due to thermal emission from their surface. A schematic description of the generator is presented and an elementary calculation model is proposed. This model is divided into 4 blocks that describe the various processes taking place in the device. The assumptions and simplifications necessary for the evaluation are discussed. Preliminary calculation data on the efficiency of a plasma-drop generator with magnetic charge separation have been obtained under conditions close to those actually achievable by manufacturing technologies. The main parameters for evaluation were power, efficiency, voltage and magnetic field induction. As a result of the calculations performed, the fundamental possibility of creating a workable plasma-drop generator based on the proposed solutions is shown. The results obtained are not accurate and require further improvement of the model and study of the processes taking place in the generator.

Design and implementation of a novel zero‐current switching method for low‐power DC–DC converters

AbstractThis paper introduces a unique zero‐current switching (ZCS) technique for low‐power dc–dc converters. In this paper, a single‐inductor dual‐input triple‐output converter is considered to apply this new technique, which can be generalized for converters with more inputs and outputs and high‐power and energy‐harvesting applications. The first input of this converter can be connected to any source that can produce energy, such as photovoltaic (PV) cells or thermoelectric generator (TEG), and the second input can be considered a battery. The proposed converter is implemented discretely, and a low‐power microcontroller whose power consumption is reduced by the software is employed to control the whole system. In the proposed ZCS method, the current sensor is not used, and only a simple voltage level detector is employed to detect the inductor voltage level in order to determine the optimal value of the inductor discharge duty cycle. This converter works in discontinuous conduction mode (DCM) and uses pulse width modulation (PWM) and the time‐multiplexing strategy (TMS). The main focus of this paper is on designing and implementing a digital control algorithm based on this new ZCS technique in order to increase efficiency.

Calculation of inlet capacitance for long-duration induction voltage test of single-phase three-winding converter transformers

The converter transformer is one of the core equipment in the high-voltage DC (HVDC) transmission project. The capacity of the converter transformer is much larger than that of an ordinary AC transformer, and its main function is to convert the AC system voltage to the phase change voltage required by the converter. The long-duration induction voltage test is an important technical means to assess the insulation strength of electrical equipment, and the calculation of the inlet capacitance of the converter transformer in the test design is extremely critical. This paper conducts circuit and mathematical modeling based on the structure of a single-phase three-winding converter transformer, calculates the equivalent capacitance between each winding of the converter transformer and each winding to ground by the model, and uses each equivalent capacitance to calculate the voltage added inlet capacitance, then obtains the appropriate compensation inductance. Moreover, the calculated inlet capacitance is verified by using the field test data, and the verification results show the reasonableness of the model. Finally, the calculation results are analyzed for errors and possible sources of errors are pointed out. This inlet capacitance calculation method has some universality and is expected to be promoted and applied in this field.

Analysis of Flexible Silver-printed NFC Tag Antenna on Miniaturization and Bending Effect

Size and flexibility are the two main elements that must be considered in designing a near-field communication (NFC) tag antenna because they will determine the performance of the whole system. The previously designed NFC tag antenna, which is made of a rigid substrate such as FR-4, limited the application of the tag to only on a flat surface. The size of the tag antenna also needs to be optimised based on the application requirements since different sizes of the antenna will contribute to different electrical properties, including inductance and resistance. Therefore, this paper presents an analysis of a flexible printed tag antenna with different miniaturisation sizes and bending effects for NFC systems. The operating frequency of the proposed NFC tag antenna is 13.56 MHz, which is the same frequency as the NFC reader, allowing them to be coupled and to communicate with each other. Three sizes of silver printed tag antenna are presented, and the performance of the tag during bending is analyzed. Other tag antenna parameters and characteristics, including reflection coefficient, inductance, resistance, read range and output voltage, are also observed through simulation and accordingly measured. The results show that the Design 1 antenna has demonstrated the highest measured tag reading range of 3 cm, while the Design 2 antenna has shown good flexibility, withstanding bending at various angles and exhibiting a minimum reading range of 0.5 cm. Overall, the correlation between antenna size, flexibility and antenna performance has been determined and systematically validated.

Efficient Nonlinear Multi-Parameter Decoupled Estimation of PMSM Drives Based on Multi-State Voltage and Torque Measurements

Accurate and fast parameter estimation is essential for efficient operation and control of permanent magnet synchronous machine (PMSM). In this paper, a novel multi-parameter decoupling estimation method based on multi-state measurement is proposed to analyze and estimate the important parameters including winding resistance, permanent magnetic flux linkage, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$d-q$</tex-math></inline-formula> axis inductances. An improved PMSM model containing inverter distorted voltage and nonlinear inductance considering magnetic saturation is established at first, then the model is decoupled to reduce the cross influences among the parameters and improve the computation efficiency through model dimension reduction according to the proposed decoupling method, and finally each parameter is estimated from multi-state voltage and torque measurement with improved efficiency and accuracy. This decoupling method separates the resistance and the inductance based on electromagnetic torque and reluctance torque, which is the crucial part of the estimation method proposed in this paper. Experiment on a PMSM driving system and comparison with existing methods are conducted to show that the proposed estimation method can improve the accuracy of estimation and calculation efficiency.