High Frequency Switching Devices Research Articles

Structural, optical, electrical and magnetic tuning based on Zn substitution at A site in yttrium doped spinel ferrites

The series of Zn2+ doped Co–Ni–Y spinel ferrites with compositional formula Co0.6Ni0.4-xZnxFe1.9Y0.1O4 where x = 0.0, 0.1, 0.2, 0.3, 0.4 were synthesized by chemical co-precipitation technique. Structural, optical, electrical and magnetic properties were explored by X-ray diffraction (XRD), Ultra violet spectroscopy (UV–Vis), Fourier transformation infrared spectroscopy (FTIR), four-point probes I–V technique and Vibrating sample magnetometer (VSM), respectively. Variations in lattice constants were detected with the insertion of Zn due to the difference in ionic radii of Zn2+ (0.82 Å) and Ni2+ (0.79 Å). FTIR outcomes exposed the existence of tetrahedral frequency absorption band in the range of 545.24–522.34 cm−1. Optical band gap energy (Eg) determined from the UV–Vis data was observed to be decreased from 3.86 to 1.84 eV. DC electrical resistivity of synthesized nanoferrites showed decreased nature in the range of 1.46 x 1010–7.78 x 107 Ω-cm for x = 0.0–0.4, respectively. Remarkable values of coercivity and microwave frequency signified that fabricated nanoferrites are highly applicable in high frequency switching devices.

Dual Notched Four-Port Multiband Reconfigurable MIMO Antenna with Novel Fork-Radiator and Ω-shaped Ground

In the proposed communication, a 2 × 2 and 4 × 4 antenna array with the capability of rejecting dual interfering bands is presented for multiband wireless applications including Ultrawideband (UWB) and X-band. Reconfiguration of notched bands is controlled using high-frequency switching devices (RF-PIN diodes). MIMO antenna configuration is formed by the combination of the Fork-shaped patch providing wideband bandwidth with Γ-T-shaped stub attached with the patch, which acts as bandstop filters for WiMAX and WLAN bands on one plane. Novel Ω-shaped ground is printed on the opposite plane, which provides good matching of impedance. The good matching of the results suggests accuracy in simulation and measurement environment with prototype in terms of frequency, time-domain, far-field and diversity MIMO performance.

Design of a Supraharmonic Monitoring System Based on an FPGA Device.

During the last few decades, the poor quality of produced electric power is a key factor that has affected the operation of critical electrical infrastructure such as high-voltage equipment. This type of equipment exhibits multiple different failures, which originate from the poor electric power quality. This phenomenon is basically due to the utilization of high-frequency switching devices that operate over modern electrical generation systems, such as PV inverters. The conduction of significant values of electric currents at high frequencies in the range of 2 to 150 kHz can be destructive for electrical and electronic equipment and should be measured. However, the measuring devices that have the ability of analyzing a signal in the frequency domain present the ability of analyzing up to 2.5 kHz–3 kHz, which are frequencies too low in comparison to the high switching frequencies that inverters, for example, work. Electric currents at 16 kHz were successfully measured on an 8 kWp roof PV generator. This paper presents a fast-developed modern measuring system, using a field programmable gate array, aiming to detect electric currents at high frequencies, with a capability for working up to 150 kHz. The system was tested in the laboratory, and the results are satisfactory.

Multiphysics Challenges and Opportunities for Integrated Voltage Regulators in Power Delivery Architectures

Integrated voltage regulator (IVR) based power delivery architectures have become a growing trend in high performance computing systems. Integrated power delivery architectures typically feature high-frequency switching devices and embedded passive components, which can be integrated either inside the die or in the package. However, dense functional integration in such architectures though necessary brings a new set of challenges to system designers. In this paper, we study the impact of heterogeneous integration on the design of power delivery architectures that addresses issues related to electrical, thermal, and electromagnetic domains through test cases. The key design problems arising out of heterogeneous integration and the solutions for each of the domains are identified. Although the electrical impedance profile seen by the load becomes flatter in the frequency domain with fewer resonances, noise coupling at the load increases due to the close proximity of noise sources. The electromagnetic interference (EMI) levels are higher and therefore more EMI and noise mitigating filters are needed for judicious placement at the package and die-level. High thermal resistance associated with embedded passives results in a threshold for power losses in embedded inductors beyond which the conventional top-level cooling is insufficient and a local cooling solution is needed.

General electromechanical transient model of grid connected photovoltaic power generation system and its comparative analysis with electromagnetic transient model

order to solve the problem of complex electromagnetic transient model and slow calculation speed of grid connected photovoltaic power generation system, a general electromechanical transient model for grid connected photovoltaic power generation system is proposed. The model contains small electrical components and high frequency switching devices. It is completed by pure mathematical calculation. The model is simple and fast. The electromechanical transient model is simulated in PSCAD/EMTDC, and the results are in good agreement with the simulation results of electromagnetic transient model, and the simulation time is greatly reduced, which verifies the correctness and effectiveness of the electromechanical transient model. The universal electromechanical transient model provides a model reference for large-scale grid connected photovoltaic power plant simulation and modeling, and has practical value.

Role of ytterbium on structural and magnetic properties of NiCr0.1Fe1.9O4 co-precipitated ferrites

Ytterbium (Yb) doped NiCr0.1YbxFe1.9−xO4 (x = 0.00, 0.002, 0.04, 0.06, 0.08) spinel ferrites with different crystallite sizes have been prepared by co-precipitation technique and their magnetic and dielectric properties were investigated. X-ray diffraction data suggested that, after doping, all the samples possess a main spinel phase along with few traces of YbFeO3 (secondary phase). The addition of Yb3+ resulted in a decrease of crystallite size and an increase in X-ray density. The magnetic measurements indicated that saturation magnetization (Ms), coercivity (Hc) and remanence (Mr) of all the samples decreased by increasing dopant (Yb) concentration. Dielectric constant, dielectric loss and tan loss were also minimized with the increase in frequency as well as increase in the concentration of Yb3+ ions in the nickel chromium based spinel ferrites. AC conductivity was directly proportional to frequency and inversely proportional to concentration of Yb3+ ions. These ytterbium doped nickel ferrites may be potential candidates for the fabrication and development of high frequency switching devices.

The influence of Ga doping on structural magnetic and dielectric properties of NiCr0.2Fe1.8O4 spinel ferrite

A series of spinel ferrites NiCr0.2GaxFe1.8−xO4 (x=0.00, 0.002, 0.04, 0.06, 0.08) was prepared by co precipitation technique. The influence of rare earth element Ga ions the structural dielectric and magnetic properties of NiCr0.2Fe1.8O4 ferrites was investigated. The X-ray diffraction confirmed the phase precipitated out was pure spinel phase with few traces of secondary phases. The crystallite size decreases and density increases with the increases of Ga contents. The magnetic moment, saturation magnetization and remanent magnetization increased with addition of Ga ions in spinel ferrite. The dielectric constant is described that it decreases more suddenly at low frequencies as compare at higher frequencies. The decrease in dielectric loss with frequency follows Deby's relaxation phenomena. Both the variation in tan loss and dielectric loss with frequency shows a similar. AC conductivity increases with the increases of frequency which inversely proportional to concentration of Ga3+ ions follows Jonscher law. These Gallium Chromium doped nickel ferrites are very helpful for high frequency switching devices.

A High-Frequency-Link Single-Phase PWM Rectifier

This paper proposes a high-performance “cycloconverter-type” high-frequency-link (HFL) single-phase rectifier with an active voltage clamper, which provides bidirectional two-stage galvanic isolation ac-dc power conversion. Modulation strategy, modeling method, and control scheme are comprehensively developed for the HFL rectifier to guarantee its superior performances: 1) two-stage power conversion and soft-switching switch devices lead to high conversion efficiency; 2) complete elimination of voltage spikes during commutation ensures safe operation of high-frequency switching devices; and 3) it can equally function as a high-performance conventional Pulsewidth Modulation (PWM) rectifier: sinusoidal input current, constant dc output voltage, bidirectional power flows between dc side and ac side, and adjustable power factor. A prototype of the proposed HFL rectifier is built for evaluation. The experiment results demonstrate the efficacy of the soft-switching HFL rectifier and its highly promising control performance. The proposed rectifier offers a high-efficiency, high-power-density, and high-performance galvanic isolation power conversion solution to extensive applications.

High-Frequency Flyback Transformer Linked PWM Power Conditioner with An Active Switched Capacitor Snubber

A single active capacitor snubber-assisted soft-switching sinewave pulse modulation utility-interactive power conditioner with a three-winding flyback high frequency transformer link and a bidirectional active power switch in its secondary side has been proposed With the aid of the switched-capacitor quasi-resonant snubber cell, the high frequency switching devices in the primary side of the proposed DC-to-AC sinewave power inverter can be turned-off with ZVS commutation. In addition to this, the proposed power conditioner in the DCM can effectively take the advantages of ZCS turn-on commutation. Its output port is connected directly to the utility AC power source grid At the end, the prototype of the proposed HF-UPC is built and tested in experiment. Its power conversion conditioning and processing circuit with a high frequency flyback transformer link is verified and the output sinewave current is qualified in accordance with the power quality guidelines of the utility AC interactive power systems.

Synchronisation based adaptive parameter identification for permanent magnet synchronous motors

High power and high performance applications of permanent magnet synchronous motors (PMSM) are increasing. PMSM models with accurate parameters are required for precise control and fault diagnostic systems. An adaptive synchronisation based parameter identification method for the PMSM with a nonlinear structure is proposed. During the identification, the PMSM's dynamic response is synchronised with another system of similar dynamic structure. The algorithm is different from the commonly known adaptive estimator. A globally converged feedback control is applied to the reference model. Lyapunov function analysis and LaSalle's invariance principle are used to assure performance. To validate the proposed identification approach, both simulation and experiments are performed for the identification of motor parameters in a PMSM servo system. During experiments, the method is further improved to counteract voltage measurement problems brought by high frequency switching devices. The results demonstrate the effectiveness of this approach.

パワーアンプを用いた組合せ型アクティブフィルタの負荷変動時の過電流補正法

Generally, conventional type active filter utilizes voltage source inverter, which requires high frequency switching devices in order to compensate high order harmonics. But due to the switching frequency characteristics of the devices, it is difficult to reduce the electro-magnetic noise. So we proposed a combined-type active filter using linear power amplifier and low-switching frequency converter. Presently, there is a problem which spike-like current occur power supply current at the time of load changes. In this paper, we propose compensation method of current at the time of load changes.

サイクル制御を利用したPFC回路とその特性

For small capacity rectifier circuits such as those for consumer electronics and appliances, capacitor input type rectifier circuits are generally used. Consequently, various harmonics generated within the power system become a serious problem. Various studies of this effect have been presented previously. However, most of these employ switching devices, such as FETs and the like. The absence of switching devices makes systems more tolerant to over-load, and brings low radio noise benefits. In a certain application, it is necessary to obtain the lower output voltage, that is very difficult to realize such condition by using the passive elements only. In order to realize such condition, we propose a power factor correction scheme using a cycle-control and phase-control without high frequency switching devices. In this method of cycle control, improved input current wave can be obtained by widening conduction period. Hence, the harmonic characteristics can be significantly improved, where the lower order harmonics, such as the fifth and seventh orders are much reduced. The results are confirmed by the theoretical and experimental implementations.

Utility AC interfaced soft-switching sinewave PWM power conditioner with two-switch flyback high-frequency transformer

High-frequency switching pulse modulation utility-interfaced power conditioners (HF-UPC) with a high-frequency transformer link have attracted special interest for renewable and sustainable energy utilisation. These conditioners are small and cost-effective for meeting the requirements of small-scale residential power applications. However, switching power losses due to high-frequency switching operations are unavoidable. Efforts to reduce the power losses by implementing additional snubber components can complicate the controlling methods of the system. To solve these problems, a flyback transformer linked HF-UPC is proposed. The high-frequency flyback transformer is introduced into the power conditioner system instead of the typical forward transformer to simplify the circuit configuration and related controlling methods. With the aid of the resonant snubber circuits, the high-frequency switching devices in the primary side of the proposed DC-to-AC power conditioner can be turned off with zero-voltage soft-switching (ZVS). In addition, the proposed power conditioner system takes advantage of operating the currents by the discontinuous conduction mode (DCM) to realise turn-on commutation of zero-current soft-switching schemes. The output ports of the HF-UPC treated here are directly connected to the utility grid single-phase AC power source. A prototype of the proposed soft-commutation HF-UPC has been built and tested in experiments. Its power conversion processing is verified and its output current is qualified in accordance with the guidelines of the power utility companies.

Power Factor Improvement of Single-Phase Diode Rectifier Circuit By Field-Weakening of Inverter Driven IPM Motor

This paper proposes a novel inverter drive system to improve the input power factor of single-phase diode rectifier. Conventional rectifiers need a high-frequency switching device and a reactor to improve the input power factor. However, the proposed power converter does not need the switching device, electrolytic capacitor, or reactor. By making many ripples across the DC-bus voltage, the input power factor can be improved. The proposed system consists of only a single-phase diode rectifier, small film capacitor, three-phase inverter, and motor. The proposed system adopts an interior permanent magnet (IPM) synchronous motor. The IPM motor is well known as a high-efficiency motor and can realize field weakening. The basic ideas of the inverter control method are based on the following operations: the inverter's controlled synchronous with the DC-bus ripple voltage by field-weakening method, and direct active power feeding from the source side to the motor without smoothing the DC-bus voltage. This paper describes that the proposed method can obtain an input power factor of 97.3% by experimental tests, and realizes the goals of small size and long life of the system. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(2): 66–73, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20047

Modeling of a power electronic converter for EMC in the conduction emission frequency band

AbstractWith the advancement of high‐frequency switching devices, electromagnetic interferences (EMI) have become problems in power electronic converter designs. It is necessary for an electromagnetic compatibility (EMC) design to prospect and consider its possible EMI levels. This paper describes how to compute effects from a power converter to an object point to reduce conduction EMI noises effectively by an appropriate design. Modeling techniques for converter elements are discussed for a model in the conduction emission frequency band by the parameter tuning method and for line constants by an analytical derivation. Then a derived model is simulated for harmonic distributions of loop currents and their magnetic fields. © 2002 Scripta Technica, Electr Eng Jpn, 139(1): 44–50, 2002: DOI 10.1002/eej.1145

An improvement technique for the efficiency of high-frequency switch-mode rectifiers

A new technique for improving the efficiency of single-phase high-frequency switch-mode boost rectifiers is proposed. This rectifier includes an additional boost converter that follows the main high-frequency switching device. The additional converter, which is controlled at lower frequencies, bypasses almost all the current in the main switch and the high frequency switching loss is greatly reduced accordingly. Both switching devices are controlled by a simple method; each controller consists of a one-shot multivibrator, a comparator and an AND gate, and the maximum switching frequency can be limited without any clock generator. The rectifier works cooperatively in high efficiency and acts as though it were a conventional high-frequency switch-mode rectifier with one switching device. The proposed method is verified by experiment. This paper describes the rectifier configuration and design, and discusses the steady-state performance concerning the switching loss reduction and efficiency improvement. Transient performance is also included.

EMCのための電力変換器の伝導エミッション周波数帯域モデリング法

With the advancement of high-frequency switching devices, electromagnetic interferences (EMI) have become problems in power electronic converter designs. It is necessary for an electromagnetic compatibility (EMC) design to prospect and consider its possible EMI levels. This paper describes how to compute effects from a power converter to an object point to reduce conduction EMI noises effectively by an appropriate design. Modeling techniques for converter elements are discussed for a model in the conduction emission frequency band by the parameter tuning method and for line constants by an analytical derivation. Then a derived model is simulated for harmonic distributions of loop currents and their magnetic fields. © 2002 Scripta Technica, Electr Eng Jpn, 139(1): 44–50, 2002: DOI 10.1002/eej.1145

高周波スイッチング素子の電力への適用

高周波スイッチング素子の電力への適用