scholarly journals The Nonlinear Distortions in the Oscillatory System of Generator on CFOA

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Yuriy Konstantinovich Rybin
Keyword(s):  
Linear Model ◽  
Output Voltage ◽  
Oscillatory System ◽  
Voltage Amplitude ◽  
Current Feedback ◽  
Current Output ◽  
Oscillatory Systems ◽  
Advantages And Disadvantages ◽  
Nonlinear Distortions ◽  
Current Limiting

In recent years, many articles came out where one could find the analysis of oscillatory systems of electric sinusoid signals generators with amplifiers called CFOA—current feedback operational amplifiers. As a rule, the analysis of such systems is made by applying mathematical modeling methods on the basis of the amplifier linear model, which does not allow estimating advantages and disadvantages of the systems realized with those amplifiers in comparison with classical systems. A nonlinear model of a current feedback operational amplifier (CFOA) is introduced in the paper; nonlinearity of “current mirror” is reflected in the form of current double limiting. The analysis of two known oscillatory systems has been carried out with the use of this non-linear model. Dependence between current limiting level, output voltage amplitude, and maximum oscillation frequency has been obtained. The paper shows that output current limiting under current output connection of capacitive load reduces frequency range and output voltage amplitude considerably and increases harmonic distortions in comparison with classical oscillatory systems. The research done has found that the application of new amplifiers does not give considerable advantages to the oscillatory systems with CFOA.

MULTI–INERT OSCILLATORY MECHANISM

2020 ◽  
Vol 2 ◽  
pp. 19-25
Author(s):  
I.P. POPOV
Keyword(s):  
Kinetic Energy ◽  
Potential Energy ◽  
Oscillation Frequency ◽  
Free Oscillation ◽  
Initial Conditions ◽  
Oscillatory System ◽  
Harmonic Oscillations ◽  
Oscillatory Systems ◽  
Oscillatory Mechanism ◽  
Mutual Conversion

A mechanical oscillatory system with homogeneous elements, namely, with n massive loads (multi– inert oscillator), is considered. The possibility of the appearance of free harmonic oscillations of loads in such a system is shown. Unlike the classical spring pendulum, the oscillations of which are due to the mutual conversion of the kinetic energy of the load into the potential energy of the spring, in a multi–inert oscillator, the oscillations are due to the mutual conversion of only the kinetic energies of the goods. In this case, the acceleration of some loads occurs due to the braking of others. A feature of the multi–inert oscillator is that its free oscillation frequency is not fixed and is determined mainly by the initial conditions. This feature can be very useful for technical applications, for example, for self–neutralization of mechanical reactive (inertial) power in oscillatory systems.

scholarly journals A Review on Fault Current Limiting Devices to Enhance the Fault Ride-Through Capability of the Doubly-Fed Induction Generator Based Wind Turbine

2018 ◽  
Vol 8 (11) ◽  
pp. 2059 ◽  
Author(s):  
Seyed Naderi ◽  
Pooya Davari ◽  
Dao Zhou ◽  
Michael Negnevitsky ◽  
Frede Blaabjerg
Keyword(s):  
Power Systems ◽  
Wind Turbine ◽  
Induction Generator ◽  
Fault Current ◽  
Doubly Fed Induction Generator ◽  
Advantages And Disadvantages ◽  
Fault Ride Through ◽  
Current Limiting ◽  
Two Factors ◽  
Doubly Fed

The doubly-fed induction generator has significant features compared to the fixed speed wind turbine, which has popularised its application in power systems. Due to partial rated back-to-back converters in the doubly-fed induction generator, fault ride-through capability improvement is one of the important subjects in relation to new grid code requirements. To enhance the fault ride-through capability of the doubly-fed induction generator, many studies have been carried out. Fault current limiting devices are one of the techniques utilised to limit the current level and protect the switches, of the back-to-back converter, from over-current damage. In this paper, a review is carried out based on the fault current limiting characteristic of fault current limiting devices, utilised in the doubly-fed induction generator. Accordingly, fault current limiters and series dynamic braking resistors are mainly considered. Operation of all configurations, including their advantages and disadvantages, is explained. Impedance type and the location of the fault current limiting devices are two important factors, which significantly affect the behaviour of the doubly-fed induction generator in the fault condition. These two factors are studied by way of simulation, basically, and their effects on the key parameters of the doubly-fed induction generator are investigated. Finally, future works, in respect to the application of the fault current limiter for the improvement of the fault ride-through of the doubly-fed induction generator, have also been discussed in the conclusion section.

scholarly journals The multilevel inverter with clamped-diode

2019 ◽  
Vol 14 (3) ◽  
pp. 1189
Author(s):  
Trong-Thang Nguyen
Keyword(s):  
Numerical Simulation ◽  
Circuit Design ◽  
Output Voltage ◽  
Harmonic Distortion ◽  
Control Circuit ◽  
Multilevel Inverter ◽  
Power Circuit ◽  
Advantages And Disadvantages ◽  
Multi Level ◽  
And Control

<p>In this study, the author analyzes the advantages and disadvantages of multi-level inverter compared to the traditional two-level inverter and then chose the suitable inverter. Specifically, the author analyzes and designs the three-level inverter, including the power circuit design and control circuit design. All designs are verified through the numerical simulation on Matlab. The results show that even though the three-level inverter has a low number of switches (only 12 switches), but the quality is very good: the total harmonic distortion is small; the output voltage always follows the reference voltage.</p>

scholarly journals Inter-Stage Output Voltage Amplitude Improvement Circuit Integrated with Class-B Transmit Voltage Amplifier for Mobile Ultrasound Machines

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6244 ◽  
Author(s):  
Kiheum You ◽  
Hojong Choi
Keyword(s):  
Power Supply ◽  
Piezoelectric Transducer ◽  
Output Voltage ◽  
Piezoelectric Transducers ◽  
Voltage Amplitude ◽  
Voltage Amplifier ◽  
Class B ◽  
Voltage Signal ◽  
Limited Power ◽  
Limited Power Supply

Piezoelectric transducers are triggered by the output voltage signal of a transmit voltage amplifier (TVA). In mobile ultrasound instruments, the sensitivity of piezoelectric transducers is a critical parameter under limited power supply from portable batteries. Therefore, the enhancement of the output voltage amplitude of the amplifier under limited power supply could increase the sensitivity of the piezoelectric transducer. Several-stage TVAs are used to increase the voltage amplitude. However, inter-stage design issues between each TVA block may reduce the voltage amplitude and bandwidth because the electronic components of the amplifier are nonlinearly operated at the desired frequency ranges. To compensate for this effect, we propose a novel inter-stage output voltage amplitude improvement (OVAI) circuit integrated with a class-B TVA circuit. We performed fundamental A-mode pulse-echo tests using a 15-MHz immersion-type piezoelectric transducer to verify the design. The echo amplitude and bandwidth when using an inter-stage OVAI circuit integrated with a class-B TVA circuit (696 mVPP and 29.91%, respectively) were higher than those obtained when using only the class-B TVA circuit (576 mVPP and 24.21%, respectively). Therefore, the proposed OVAI circuit could be beneficial for increasing the output amplitude of the class-B TVA circuit for mobile ultrasound machines.

scholarly journals Design Method of Double-Boost DC/DC Converter with High Voltage Gain for Electric Vehicles

2020 ◽  
Vol 11 (4) ◽  
pp. 64 ◽  
Author(s):  
Zhengxin Liu ◽  
Jiuyu Du ◽  
Boyang Yu
Keyword(s):  
Electric Vehicles ◽  
High Voltage ◽  
Direct Current ◽  
Output Voltage ◽  
Input Voltage ◽  
Maximum Efficiency ◽  
Voltage Gain ◽  
Current Feedback ◽  
Voltage Ripple ◽  
High Voltage Gain

Direct current to direct current (DC/DC) converters are required to have higher voltage gains in some applications for electric vehicles, high-voltage level charging systems and fuel cell electric vehicles. Therefore, it is greatly important to carry out research on high voltage gain DC/DC converters. To improve the efficiency of high voltage gain DC/DC converters and solve the problems of output voltage ripple and robustness, this paper proposes a double-boost DC/DC converter. Based on the small-signal model of the proposed converter, a double closed-loop controller with voltage–current feedback and input voltage feedforward is designed. The experimental results show that the maximum efficiency of the proposed converter exceeds 95%, and the output voltage ripple factor is 0.01. Compared with the traditional boost converter and multi-phase interleaved DC/DC converter, the proposed topology has certain advantages in terms of voltage gain, device stress, number of devices, and application of control algorithms.

scholarly journals Multi-Function Active-Only High-Order Current-Driven Filter

2000 ◽  
Vol 23 (3) ◽  
pp. 157-161
Author(s):  
Muhammad Taher Abuelma'atti ◽  
Husain Abdullah Alzaher
Keyword(s):  
Output Voltage ◽  
High Order ◽  
Input Current ◽  
Operational Amplifiers ◽  
Output Current ◽  
Current Output ◽  
Circuit Topology ◽  
Operational Transconductance Amplifiers ◽  
Order Filter ◽  
Transconductance Amplifiers

A new multi-function high-order current-driven filter is proposed. The filter uses only operational amplifiers, and operational transconductance amplifiers (OTAs). Without using any external passive elements, a variety of high-order input-current/output-current and/or input-current/output-voltage responses can be realised without changing the circuit topology and without any matching or cancellation conditions. The parameters of the high-order filter responses can be electronically tuned by adjusting the bias currents of the OTAs.

scholarly journals Hierarchical Linear Model: Thinking Outside the Traditional Repeated-Measures Analysis-of-Variance Box

2015 ◽  
Vol 50 (4) ◽  
pp. 438-441 ◽  
Author(s):  
Monica Lininger ◽  
Jessaca Spybrook ◽  
Christopher C. Cheatham
Keyword(s):  
Linear Model ◽  
Athletic Training ◽  
Analysis Of Variance ◽  
Repeated Measures ◽  
Hierarchical Linear Model ◽  
Research Articles ◽  
Original Research ◽  
Short Report ◽  
Advantages And Disadvantages ◽  
Repeated Measures Analysis

Longitudinal designs are common in the field of athletic training. For example, in the Journal of Athletic Training from 2005 through 2010, authors of 52 of the 218 original research articles used longitudinal designs. In 50 of the 52 studies, a repeated-measures analysis of variance was used to analyze the data. A possible alternative to this approach is the hierarchical linear model, which has been readily accepted in other medical fields. In this short report, we demonstrate the use of the hierarchical linear model for analyzing data from a longitudinal study in athletic training. We discuss the relevant hypotheses, model assumptions, analysis procedures, and output from the HLM 7.0 software. We also examine the advantages and disadvantages of using the hierarchical linear model with repeated measures and repeated-measures analysis of variance for longitudinal data.

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