Search results for "Converter"
showing 10 items of 275 documents
Investigation and reduction of losses on inverter-fed induction motors
2017
An electric motor is more effective and flexible when supplied by a frequency converter. The frequency converter not only produces the fundamental voltage but also a set of higher harmonics which cause additional losses in the motor. Losses in the frequency converter are normally neglected in the drive dimensioning due to insufficient data available from manufacturers. Motor's losses can be reduced by increasing the switching frequency of frequency converters. An increase of the switching frequency may result in higher losses in the frequency converter. This work investigates analytically and experimentally the dependence of the losses of modern motor and frequency converter on a switching …
Sensorless control of induction motors using an extended Kalman filter and linear quadratic tracking
2017
Induction motors are the most commonly used prime-movers in industrial applications. Many induction motors supplied by frequency converters are coupled with a physical angular rotor position/velocity sensor which makes the drive complex and require maintenance. This paper presents a sensorless control structure to avoid using a physical angular rotor position/velocity sensor. The proposed method estimates and control the angular rotor velocity using optimal control theory. The optimal controller used in this paper is based on linear quadratic tracking and the states of the machine are estimated using an extended Kalman filter. Both the controller and the estimator utilize the same internal …
Partial discharges at different voltage waveshapes: Comparison between two different acquisition systems
2018
In modern HV apparatuses the wide use of electronic converters, increase the stress on the involved insulation systems and thus affect the reliability of the whole power grid. Additionally, such non-sinusoidal voltage shapes contain high gradient flanks that create problems in the detection of partial discharge (PD) activity. The aim of this paper is to discuss the methodology on how to suitably approach PD detection in insulation systems exposed to various voltage waveshapes in general by comparing two different measuring systems. The first one, equipped with a resonant PD decoupler, designed specifically for detection at typical power electronic waveshapes and the other one, based on an a…
Multi-pulse characterization of trapping/detrapping mechanisms in AlGaN/GaN high electromobility transistors
2019
GaN high-electro mobility transistors (HEMTs) are among the most promising candidates for use in high-power, high-frequency, and high-temperature electronics owing to their high electrical breakdown threshold and their high saturation electron velocity. The applications of these AlGaN/GaN HEMTs in power converters are limited by the surface trapping effects of drain-current collapse. Charge-trapping mechanisms affect the dynamic performance of all GaN HEMTs used in power switching applications. This study analyzes the dynamic resistance of GaN HEMTs and finds that the effects of dynamic resistance can be suppressed by controlling switching conditions and on-off cycles.
Experimental Investigation of Efficiency Map for an Inverter-Fed Surface-Mount Permanent Magnet Synchronous Motor
2019
Losses in inverter-fed permanent magnet motors are underestimated by using analytical or numerical approach since additional losses due to extra harmonics of the frequency converter are normally skipped. Further, losses in switches and passive components of the converter and the effect of switching frequencies cannot be numerically taken into consideration. Loss-minimizing control and proper efficiency analysis of inverter-fed permanent magnet motors cannot be achieved if an efficiency map is built based on a numerical investigation of the motors alone. This works first reviews losses in a surface-mount permanent magnet synchronous motor (SPMSM) and frequency converters. The efficiency map …
A Planar Generator for a Wave Energy Converter
2019
This article presents a permanent magnet planar translational generator which is able to exploit multiple modes of sea wave energy extraction. Linear electrical generators have recently been studied for the exploitation of sea wave energy, but, to the best of our knowledge, no synchronous planar translational generator has been proposed. In this article, to maximize the energy extraction, we have considered all the potential modes of motion due to wave excitation and included them within the mathematical model of the proposed system. The principle of operation of the generator can be summarized as follows: the moving part (translator) of the generator is driven from the sea waves and induce…
Silicon dosimeters based on Floating Gate Sensor: design, implementation and characterization
2020
A rad-hard monolithic dosimeter has been implemented and characterized in a standard 180 nm CMOS technology. The radiation sensor (C-sensor) is based on a Floating Gate (FG) MOS discharge principle. The output current is processed by a current-to-voltage (I/V) interface and then converted by a 5-bit flash ADC. The dosimeter is re-usable (FG can be recharged) and can detect a dose up to 1krad (Si) with a resolution of 30rad (Si) typical over temperature 0 to 85°C range. The ADC allows easy further signal processing for calibration and averaging, etc. The power consumption of C-sensor plus I/V interface is < 2mW from a 5 V power supply. The overall layout area is less than 0.25mm2. The Rad…
Low complexity digital background calibration algorithm for the correction of timing mismatch in time-interleaved ADCs
2019
Abstract A low-complexity post-processing algorithm to estimate and compensate for timing skew error in a four-channel time-interleaved analog to digital converter (TIADC) is presented in this paper, together with its hardware implementation. The Lagrange interpolator is used as the reconstruction filter which alleviates online interpolator redesign by using a simplified representation of coefficients. Simulation results show that the proposed algorithm can suppress error tones for input signal frequency from 0 to 0.4 f s . The proposed structure has, at least, 41% reduction in the number of required multipliers. Implementation of the algorithm, for a four-channel 10-bit TIADC, show that, f…
The Effect of the Harmonic Content Generated by AC/DC Modular Multilevel Converters on HVDC Cable Systems
2019
With the increasing penetration of renewable and decentralized energy sources into the power grid, an extended use of DC voltages is expected on both distribution and transmission levels. Generation of DC voltages by means of voltage source converters is associated with a wide spectrum of harmonic distortions at converter terminals, both on the ac and on the dc sides. This can lead to partial discharges in power cables, which deteriorate insulation material thus weakening its performance and reducing cable life-time. In the previously published paper, the effect of harmonic distortion on appearance of partial discharges in cable insulation was evaluated. Here, the study related to the PD be…
A unified observer for robust sensorless control of DC–DC converters
2017
Abstract Due to the large variety of converters' configurations, many different sensorless controllers are available in the literature, each one suited for a particular converter. The need for different configurations, especially on the same power supply, make it clear the advantage of having a shared control algorithm. This paper presents a unified nonlinear robust current observer for buck, boost and buck–boost converters in synchronous and asynchronous configurations. The unified observer speeds up the design, tuning and the implementation, and requires a memory cheaper code, easier to certify. Simulation and experimental results are presented to validate the approach in different scenar…