High Frequency Current Source Research Articles

Transient Process at Atmospheric Discharge into the Landline and the Appearance of an Electric Arc in the Switch

This document proposes a model of the process of atmospheric discharge of overhead lines followed by an electric arc. The intensity of atmospheric discharges, followed by electric arc and destruction, is determined by the difference in potential and current. Such a structure and form of discharge make it difficult to analyze the transient process and obtain adequate solutions. That is why the model of the transient process in the electric arc of the switch under the conditions of interruption of the AC circuit is specially analyzed. Simple equivalent schemes for the analysis of phenomena with given values of linear parameters are presented, which are very simple to apply. All influential parameters by which the overvoltage values in the model can be estimated were also taken into account. The evaluation of the proposed model was performed using the adapted MATLAB program psbsurlightcuurent for atmospheric electrical discharge, which contains a high frequency current source. The verified simulation method was used to verify the results as part of a method derived from artificial intelligence algorithms. The process simulation program, the obtained voltage and current diagrams confirm the application of the simulation algorithm model.

The combined effect of heat transfer and skin effect on Joule heating for silicon rod in Siemens reactor

The Maxwell’s field equations and Ohm’s Law were added to energy equation to account for the electromagnetic contributions to heat transfer phenomena within silicon rod arranged in an industrial Siemens reactor. Based on the combined effect of the heat dissipation (radiation, convection and reaction energy), a Joule heating model using alternating current (AC) has been developed. The analysis accounts for the rod radius, location, skin depth, as well as the properties of the polysilicon. The results indicate that high frequency current sources can generate an even temperature profile, and a higher deposition radius can be obtained. Alternating current, having a fixed or variable high frequency in the range of about 2.4kHz to 500kHz, is provided to concentrate at least 70% of the current in an annular region that is the outer 15% of a growing rod due to the skin effect. The voltage-current curves have been predicted based on the present model. Finally, a novel Joule heating method useful for producing the larger high-purity polycrystalline silicon rods by considering the low frequency power and the high frequency power is proposed. It is interesting that the average energy consumption (AE) can be decreased from 55kWh/kg to about 44kWh/kg as extending the maximum deposition radius from 7cm to 10cm by using a high-frequency current source.

Harmonics Reduction in a Current Source Fed Quasi-Resonant Inverter Based Induction Heater

<p>This paper investigates an approach to reduce the injection of unwanted harmonics from the input side power source. The proposed work finds an application of a suitably designed Low Pass Filter (LPF) for harmonics reduction. The Low Pass Filter is incorporated in between the input power source and high frequency current source fed single switch parallel quasi-resonant inverter of a domestic Induction Heater. The inverter has an Insulated Gate Bipolar Junction Transistor (IGBT) switch. Undesirable harmonics injection to the input power source makes voltage and current waveforms non-sinusoidal. Fast Fourier Transform (FFT) analysis has been applied to study the effect of harmonics in frequency domain. The entire system is realized in Power System Simulator (PSIM) environment. It is finally proved that the proposed filter reduces the Total Harmonic Distortion (THD) and the Distortion Factor (DF) of the input current. It is also proved that the proposed Low Pass Filter can make the input power factor closer to unity.</p>

Modified Bidirectional Converter with Current Fed Inverter

A bidirectional dc-dc converter with multiple outputs are concatenated with a high frequency current source parallel resonant push pull inverter is presented in this paper. The two outputs are added together and it is taken as the input source for the inverter. The current source parallel resonant push pull inverter implemented here with high frequency applications like induction heating, Fluorescent lighting, Digital signal processing sonar. This paper proposes a simple photovoltaic power system consists of a bidirectional converter and a current fed inverter for regulating the load variations. Solar power is used as the input source for the system. Simulation of the proposed system is carried out in PSIM software and experimentally verified the results.

자기 임피던스 센서를 이용한 맥박 측정 장치

A monitoring apparatus for pulse shapes of human heartbeats has been developed using an amorphous MI(Magnetic Impedance) sensor. The pulse shapes are successfully obtained from voltage signals due to the variations of magnetic impedance in the amorphous MI sensor, which is attached to a patient's wrist. This voltage signal was fed into a signal processing module to extract the pulse shapes of heartbeats. The signal processing module, which is proposed to detect a weak variations of impedance in MI sensor under a noisy measurement environment, consists of a high frequency current source, an amplifier stage and a synchronous detection circuit. To evaluate the characteristics of a newly developed apparatus, various experiments were performed. The experimental results show that the developed apparatus could be used as a diagnosis tool for traditional Korean medicine with further systematic clinical studies.

Magneto-impedance element

The magneto-impedance (MI) effect is a phenomenon in which the voltage induced by a high frequency current source in a ferromagnetic wire changes with the application of an external field. A giant MI effect was found in amorphous magnetic wires having a composition of (Fe/sub 0.06/Co/sub 0.94/)/sub 72.5/Si/sub 12.5/B/sub 15/ and a magnetostriction of (-10/sup -7/). The amplitude of the wire voltage decreased by 40% at 1 MHz, 60% (600 kHz) and 50% (150 kHz), for wires having diameters 30 /spl mu/m, 50 /spl mu/m and 124 /spl mu/m, respectively, under the influence of an external longitudinal field of about 10 Oe (800 A/m). A highly sensitive and quick-response field sensor was constructed using a 200 MHz resonant multivibrator bridge-circuit combining two MI-effect elements of 1 mm length with two field effect transistors (FET). Highly sensitive flux detection was carried out by using the small MI sensor head on a rotary encoder magnet having 512 poles and a diameter of 30 mm. Discussion of a mechanism for the MI effect considers the skin effect in an amorphous wire with high circumferential anisotropy. >

High-Frequency Current Source Inverter

The frequency range of the current source inverter (CSI) is limited by the slow commutation process in the inverter circuit. A method to reduce the commutation time and to limit the commutation capacitor voltage is proposed. A brief description of the conventional CSI and a detailed analysis of the commutation intervals of the proposed circuit are given. The experimental waveforms observed in the laboratory verify the validity of the analysis.

A ferroelectric amplifier

“Ferroelectric” refers to a class of nonlinear dielectrics characterized by a charge vs. voltage relationship exhibiting hysteresis and dielectric saturation. A capacitor made from barium-strontium titanate ceramic, a ferroelectric material, was used as the capacitive element in a single tuned circuit to which a high frequency current was applied. A low frequency signal to be amplified was applied to the capacitor, causing its capacitance to vary. The resulting amplitude-modulated high frequency voltage was applied to a detector circuit to recover the signal frequency. An analysis of this circuit shows what must be done to achieve maximum amplification. A circuit such as described was constructed and power gains of about 60 were obtained. When the signal was removed and the output of the amplifier fed back to the input, sustained oscillations of low frequency were obtained, with only the high frequency current source applied. The frequency of oscillation could be varied continuously over a wide range.