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A new approach for fast field calculation in electrostatic electron lens design and optimization

Hesam Mahmoudi Nezhad, N. (author), Ghaffarian Niasar, M. (author), Hagen, C.W. (author), Kruit, P. (author)

In electron optics, calculation of the electric field plays a major role in all computations and simulations. Accurate field calculation methods such as the finite element method (FEM), boundary element method and finite difference method, have been used for years. However, such methods are computationally very expensive and make the computer...

journal article 2024

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Series magnetic coupled reactor saturation considerations for high voltage AC and DC power systems

Heidary, Amir (author), Ghaffarian Niasar, M. (author), Popov, M. (author)

The rapid increase of integrated distributed generators results in higher fault currents in the future modern grids. A remedy for the concern is employing series reactors as fault current limiters. This paper elaborates on a ferromagnetic core series reactor, which, when saturated, adversely affects the operation of the series reactor during...

journal article 2024

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Comprehensive Investigation of Promising Techniques to Enhance the Voltage Sharing among SiC MOSFET Strings, Supported by Experimental and Simulation Validations

Zhao, W. (author), Ghafoor, S. (author), Lagerweij, Gijs Willem (author), Rietveld, Gert (author), Vaessen, P.T.M. (author), Ghaffarian Niasar, M. (author)

This paper comprehensively reviews several techniques that address the static and dynamic voltage balancing of series-connected MOSFETs. The effectiveness of these techniques was validated through simulations and experiments. Dynamic voltage-balancing techniques include gate signal delay adjustment methods, passive snubbers, passive clamping...

journal article 2024

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Magnetic core effects on the high-frequency behavior of transformers

Nasirpour, F. (author), Ghaffarian Niasar, M. (author), Popov, M. (author)

This paper investigates the high-frequency transformer losses attributed to eddy currents in both conductors and the core. A comprehensive model of a transformer winding is presented, meticulously incorporating skin and proximity effects. The winding resistance increase due to these effects is determined by applying analytical and finite element...

journal article 2024

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The principle of magnetic flux switch

Heidary, Amir (author), Ghaffarian Niasar, M. (author), Popov, M. (author)

This paper introduces an innovative Magnetic Switch (MFS) designed to control and alter magnetic flux within energy system components, offering an alternative to conventional power electronic devices. The MFS comprises a low-current control coil, a control core, and a high-density magnetic flux-carrying main core combined with a main coil energy...

journal article 2024

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Design of Integrated Hybrid Configuration of Modular Multilevel Converter and Marx Generator to Generate Complex Waveforms for Dielectric Testing of Grid Assets

Ganeshpure, D.A. (author), Soeiro, Thiago Batista (author), Ghaffarian Niasar, M. (author), Kulkarni, Nitish Milind (author), Bauer, P. (author), Vaessen, P.T.M. (author)

This article proposes a new configuration of a modular multilevel converter (MMC) and a Marx generator to generate fast-rising impulse waveforms. This new configuration improves the capabilities of the MMC-based high voltage arbitrary wave shape generator to generate fast-rising impulse since the MMC topology faces many inherent limitations....

journal article 2024

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A Data-Driven Model for Power Loss Estimation of Magnetic Materials Based on Multi-Objective Optimization and Transfer Learning

Li, Z. (author), Wang, L. (author), Liu, R. (author), Mirzadarani, R. (author), Luo, T. (author), Lyu, D. (author), Ghaffarian Niasar, M. (author), Qin, Z. (author)

Traditional methods such as Steinmetz's equation (SE) and its improved variant (iGSE) have demonstrated limited precision in estimating power loss for magnetic materials. The introduction of Neural Network technology for assessing magnetic component power loss has significantly enhanced accuracy. Yet, an efficient method to incorporate detailed...

journal article 2024

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Giant Magneto-Resistive (GMR) Sensors for Non-Contacting Partial Discharge Detection

Chen, Y. (author), Castro Heredia, L.C. (author), Smit, J.J. (author), Ghaffarian Niasar, M. (author), Ross, Robert (author)

Partial discharge (PD) detection is a standardized technique to qualify the insulation condition in power equipment. The main purpose of the article is to evaluate the performance of an extra high-sensitivity adapted giant magneto-resistive (xMR) sensor for non-contacting PD detection. First, compensation and signal conditioning circuits of...

journal article 2023

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Partial discharge detection on power equipment using a magneto-resistive sensor

Chen, Y. (author), Castro Heredia, L.C. (author), Smit, J.J. (author), Ghaffarian Niasar, M. (author), Ross, Robert (author)

Partial discharges (PD) detection is an effective diagnostic method to assess the insulation condition of electrical power equipment in the high-voltage laboratory or field tests. This paper presents a non-contacting PD detection method for power equipment. The method is based on an extra high-sensitivity adapted giant magneto-resistive (xMR)...

journal article 2023

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Design of High-frequency Fast-rise Pulse Modulators for Lifetime Testing of Dielectrics

Mathew, P. (author), Ghaffarian Niasar, M. (author), Vaessen, P.T.M. (author)

Penetration of power electronics in the grid has produced a new species of stresses, characterized by fast-rising pulsed waveforms with microsecond rise times repeating at several tens of kilohertz. Analyzing their impact on existing and future insulation systems requires pulse modulators, most often with pulse transformers (PTs), to perform...

journal article 2023

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The principles of controlled DC reactor fault current limiter for battery energy storage protection

Heidary, Amir (author), Popov, M. (author), Moghim, Ali (author), Ghaffarian Niasar, M. (author), Lekić, A. (author)

The significance of battery energy storage systems (BESSs) technology has been growing rapidly, mostly due to the need for microgrid applications and the integration of renewables. Relevant to the importance of utilization of BESS in microgrids, the protection of the BESS during microgrid faults has become a concern too. The short circuit in...

journal article 2023

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High-frequency transformer winding model with adequate protection

Nasirpour, F. (author), Heidary, Amir (author), Ghaffarian Niasar, M. (author), Lekić, A. (author), Popov, M. (author)

High local electric field intensity in transformer windings originating from transient signals is one of the reasons for transformer failures. Due to the integration of renewable energy sources into the power grids and the increased number of transients, the likelihood of transformer catastrophic failure increases accordingly. Therefore, to...

journal article 2023

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Transformer Resonance: Reasons, Modeling Approaches, Solutions

Heidary, Amir (author), Ghaffarian Niasar, M. (author), Popov, M. (author), Lekić, A. (author)

Due to the extension of the power grid with many complex and compact pieces of power equipment, transformers will be more exposed to fast transient, resulting from various resonance conditions. Transformer resonance can result in severe overvoltage on internal parts of the winding, leading to insulation failure and, consequently, transformer...

journal article 2023

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Demonstration of Scalable Series-Connected Submodule of Modular Multilevel Converter-based Arbitrary Wave shape Generator used for High Voltage Testing from Off-the-Shelf Component

Ganeshpure, D.A. (author), Soeiro, Thiago B. (author), Gagic, Mladen (author), Ghaffarian Niasar, M. (author), Bauer, P. (author), Vaessen, P.T.M. (author)

To test high-voltage (HV) equipment with increasingly complex transients obtained from various power system studies, this article demonstrates a hardware implementation of a medium-voltage (MV) submodule (SM) to be used in a modular multilevel converter (MMC)-based HV arbitrary wave shape generator (AWG). The MV SM is scalable with its own...

journal article 2023

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Fast 2.5D Loss Calculation for round Litz Wires

Luo, T. (author), Ghaffarian Niasar, M. (author), Vaessen, P.T.M. (author)

Litz wire, which is used to suppress eddy current, always have complex structure. Solving its 3-D finite element model (FEM) requires high computational resources. This article presents a 2.5-D loss calculation method for round Litz wires, which do not need mesh. One pitch of Litz wire is set as an object. The exact structure is constructed...

journal article 2023

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Improved Winding Losses Calculation based on Bessel Functions

Luo, T. (author), Ghaffarian Niasar, M. (author), Vaessen, P.T.M. (author)

In this article, an approach combining semi-empirical equations and the method of images is proposed for round conductor layer windings with un-gapped core. The new equation for proximity effect can convert the constant field strength from the magneto-motive force (MMF) across the core window into a frequency-dependent uniform background...

journal article 2023

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Two-Dimensional Frequency-Dependent Resistance and Inductance Calculation Method for Magnetic Components with Round Conductors

Luo, T. (author), Ghaffarian Niasar, M. (author), Vaessen, P.T.M. (author)

Magnetic components are essential parts in many power electronic applications. Their characteristics deeply impact the performances of the applications. This article proposed a 2-D calculation method for frequency-dependent winding losses and leakage inductance of magnetic components of round conductors. The method does not have any...

journal article 2023

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Optical Detection Method for Partial Discharge of Printed Circuit Boards in Electrified Aircraft under Various Pressures and Voltages

Zang, Yiming (author), Ghaffarian Niasar, M. (author), Qian, Yong (author), Zhou, Xiaoli (author), Sheng, Gehao (author), Jiang, Xiuchen (author), Vaessen, P.T.M. (author)

Realization of an electrical aircraft demands a low-weight electric distribution and propulsion system. The use of high voltage and power electronics operated at high switching frequencies is essential to achieve this objective. However, printed circuit boards (PCBs) in electrified aircraft are in a harsh working environment, which can make...

journal article 2022

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2D Winding losses calculation for round conductor coil

Luo, T. (author), Ghaffarian Niasar, M. (author), Vaessen, P.T.M. (author)

Winding loss calculation is essential for inductor and transformer design. In this article, a revised 1-D Ferreira's formula is proposed, which considers the interaction between conductors. Then, a 2-D loss calculation approach is proposed based on the analytical solution of round conductors under a uniform external field. An equivalent...

journal article 2022

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Optical Characteristics and Fault Diagnosis of Partial Discharge in C4F7N/CO2 Gas mixture and SF6 Based on Novel Multispectral Microarray Detection

Zang, Y. (author), Qian, Yong (author), Zhou, Xiaoli (author), Ghaffarian Niasar, M. (author), Sheng, Gehao (author), Jiang, Xiuchen (author)

Optical partial discharge (PD) detection is an efficient means of diagnosing the insulation status of power equipment. C4F7N/CO2 gas mixture is a very potential environmentally-friendly SF6 substitute gas, and its PD optical characteristics need to be studied to guide the PD diagnosis of novel C4F7N/CO2 equipment. Therefore, this article...

journal article 2022