Online ISSN
1755-4543
Print ISSN
1755-4535
IET Power Electronics
Volume 4, Issue 7, August 2011
Volumes & issues:
Volume 4, Issue 7
August 2011
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- Author(s): D. Sha ; D. Wu ; X. Liao
- Source: IET Power Electronics, Volume 4, Issue 7, p. 743 –751
- DOI: 10.1049/iet-pel.2010.0231
- Type: Article
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The power quality of three-phase grid-connected inverters has drawn attention with the increasing numbers of distributed generation systems. In order to effectively eliminate the harmonics in output currents, a hybrid system based on proportional–integral (PI) control and repetitive control (RC) implemented in the synchronous reference frame (SRF) is presented. Based on the reference frame transformation, the use of a repetitive controller is not for achieving fundamental reference current tracking but attaining the harmonics compensation, which is different from the RC designed in a static reference frame. In addition, analyses of the SRF-based hybrid controlled converter system, including stability constraints, harmonics rejection principles and the relationship between the PI controller and repetitive controller, are further developed in frequency domain and time domain. Finally, experimental results are demonstrated to validate the steady-state and dynamic performance of the proposed hybrid controlled system. - Author(s): A.I. Maswood ; E. Al-Ammar ; F. Liu
- Source: IET Power Electronics, Volume 4, Issue 7, p. 752 –758
- DOI: 10.1049/iet-pel.2010.0189
- Type: Article
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752
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Three-phase three-level rectifier (TPTL) is popular in present days for high-power application owing to its low blocking-voltage stress on the power switches (half of dc-link voltage). Such a rectifier can also operate as unity power factor (PF) converter as presented in this work. The rectifier input current controller can be operated with either fixed frequency or random frequency both with their advantages and shortcomings. In this study, the current controller is implemented with: (a) conventional hysteresis current control (random frequency) and (b) average current control (fixed frequency). The design issues and the performance of the two current modulation strategies are investigated and compared. Rectifier performance parameter, that is, THD and PF are evaluated and confirmed through hardware prototype results. - Author(s): Suroso and T. Noguchi
- Source: IET Power Electronics, Volume 4, Issue 7, p. 759 –766
- DOI: 10.1049/iet-pel.2010.0008
- Type: Article
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759
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The study proposes a new circuit configuration of multilevel current-source inverter (CSI). In this new multilevel CSI topology, all power switching devices of the inverter are connected at a common-emitter point or at a common-potential line. Hence, all the power switches need only a single gate drive power supply without using isolated power supplies or conventional bootstrap techniques. This feature is still valid even if the number of the power switches increases owing to the higher-level number of the output current waveform. As a result, complexity of the gate drive circuit can be remarkably moderated. In addition, the multilevel CSI circuit is more capable to operate at high switching frequency if required, because all the power switches are connected at a common potential level. A five-level pulse width modulation inverter configuration, including chopper circuits as DC current-power source circuits using small smoothing inductors, is verified through computer simulations and experimental tests. The results show feasibility of the proposed multilevel inverter topology with reducing the complexity of the gate drive circuits, the inductor size, total harmonic distortion (TMD) of output current and increasing the efficiency of the multilevel CSI. - Author(s): R. Horvat and K. Jezernik
- Source: IET Power Electronics, Volume 4, Issue 7, p. 767 –775
- DOI: 10.1049/iet-pel.2010.0275
- Type: Article
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767
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This study presents the implementation of a hybrid control strategy that is applied to a brushless AC (BLAC) motor drive. Hybrid control is a general approach for control of switching-based hybrid systems (HS). This class of HS includes a continuous process, controlled by a discrete controller with a finite number of states. The overall stability of the system is shown with the use of Lyapunov technique. The Lyapunov functions contain a term that penalises incremental energy of control error, torque and stator current, which enhances the stability. The closed-loop system, with the proposed control law, provides good transient response and good regulation of the BLAC motor control. A new logical field programmable gate array current (torque) controller is developed, based on the Lyapunov theory. The reference tracking performance of speed and torque (current) is demonstrated in terms of transient characteristics through simulation and experimental results. - Author(s): D. Hamza ; M. Sawan ; P.K. Jain
- Source: IET Power Electronics, Volume 4, Issue 7, p. 776 –784
- DOI: 10.1049/iet-pel.2010.0200
- Type: Article
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776
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This study introduces a technique that combines passive and active electromagnetic interference (EMI) filtering methods to attenuate the common mode conducted noise in the input bus of the DC/DC converter and to minimise the size and the cost of the existing passive EMI filters. The technique presented can be implemented in all DC/DC converters topologies to provide a level of compliance with the electromagnetic directives. The circuit analysis and the attenuation curves showing the performance and the viability of this technique is provided. The filter input/output impedance criterion is verified to ensure the stability of the converter, by measuring the gain and the phase margins of the open-loop frequency response of the converter. The proposed technique provides a valuable design solution for compliance engineers where the Printed Circuit Board real-estate is an issue. Experimental results reveal more than 30 dB attenuation across the electromagnetic compatibility spectrum. This method contributes to the reduction of the size and weight of the input passive EMI filter. The proportion of the passive filter as compared to the DC/DC converter device can vary from 5 to 3%, depending on the converter specifications. Experimental results to demonstrate the performance and the effectiveness of the input active EMI filter in DC/DC converters are presented. - Author(s): E. Jayashree and G. Uma
- Source: IET Power Electronics, Volume 4, Issue 7, p. 785 –792
- DOI: 10.1049/iet-pel.2010.0265
- Type: Article
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This study presents the analysis, design and voltage regulation of a zero-voltage switching quasi-resonant DC–DC converter with low switching losses for applications requiring constant power supply. In order to increase the power packing density, a simple control method using an analogue resonant controller UC3861 is used to regulate the output voltage against load variations and supply disturbances. The performance of the controller is verified by developing a prototype model of the converter and experimental results are presented. Also it is observed that the converter provides maximum efficiency of 93.5% at full load. - Author(s): N.Z. Yahaya ; K.M. Begam ; M. Awan
- Source: IET Power Electronics, Volume 4, Issue 7, p. 793 –798
- DOI: 10.1049/iet-pel.2010.0218
- Type: Article
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p.
793
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High-efficiency converters with excellent low ripple regulated output load must feature the outstanding switching loss reduction mechanism. The rapid advancement of low-loss converter design has posed stringent challenges to designers for efficient power delivery and tight voltage regulation. In this work, the new synchronous rectifier buck converter (SRBC) circuit is proposed. It has been found that the SRBC can operate effectively at 1 MHz switching frequency with low switching and gate drive losses operating in zero-voltage switching condition. - Author(s): M. Niroomand and H.R. Karshenas
- Source: IET Power Electronics, Volume 4, Issue 7, p. 799 –807
- DOI: 10.1049/iet-pel.2010.0097
- Type: Article
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This study is concerned with the control of three-phase uninterruptible power supply (UPS) systems based on a hybrid controller. A UPS must be able to maintain regulated output voltage in the face of all line/load disturbances. In order to achieve this, the control system of a UPS must have a fast transient response and a low steady-state error. Fast controllers cannot always maintain the required steady-state accuracy. Therefore in this study, a hybrid control solution is proposed. In the proposed method, a fast, yet simple, controller based on deadbeat (DB) control law is used to achieve the fast transient response required for UPS output voltage control. Noting that non-linear loads that tend to distort UPS output voltage in steady-state have periodic waveforms in nature, a type of learning controller known as a repetitive controller is added to the DB controller to improve steady-state performance of the UPS system. This results in distortion-free output voltage along with a fast error convergence. The system modelling and controller design for the proposed structure are presented in this study. A brief stability analysis is given. Both simulations and experimental results are shown for verification of the theoretical analysis. - Author(s): C. Liu ; A.P. Hu ; N.-K.C. Nair
- Source: IET Power Electronics, Volume 4, Issue 7, p. 808 –815
- DOI: 10.1049/iet-pel.2010.0243
- Type: Article
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Capacitively coupled contactless power transfer (CCPT) technology has been proposed as a new contactless/wireless power transfer method recently. By employing electric field as the energy transfer medium, CCPT has advantages of being able to transfer power across metal barriers and reduced electromagnetic interference. However, there is very limited understanding and experience in the CCPT system modelling and analysis. This study models a typical CCPT system and analyses its performance under steady-state operations. An accurate non-linear circuit model is established and the stroboscopic theory is extended to determine the zero-voltage switching (ZVS)-operating frequency of the system. The tuning inductance for achieving exact ZVS operation is derived, and the effects of the coupling and load variations on the system performance are analysed. A prototype CCPT circuit is built, and practical measurements show that the steady-state time domain waveforms and efforts of coupling and load variations calculated from the theoretical model are in good agreements with experimental results. The power efficiency predicted is slightly higher than the practical results, particularly at heavy loads, because ideal power semiconductor switches and wires are used in the theoretical model. - Author(s): S. Sharma and B. Singh
- Source: IET Power Electronics, Volume 4, Issue 7, p. 816 –826
- DOI: 10.1049/iet-pel.2011.0007
- Type: Article
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p.
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A synchronous detection-based control algorithm for voltage and frequency control (VFC) of an isolated asynchronous generator (IAG) is proposed for a stand-alone wind energy conversion system (SWECS). A three-legged voltage source converter (VSC) with an isolated star/polygon transformer is used as an integrated VSC. The integrated VSC with a battery energy storage system is used to control the active and reactive powers of the SWECS. The SWECS is modelled and simulated in the MATLAB using the Simulink and the sim power system toolboxes. Test results on the developed prototype of SWECS are also presented to validate the control algorithm. The proposed VFC functions as a voltage and frequency regulator, a load leveller, a load balancer and a harmonics filter in the SWECS. - Author(s): H. Bodur ; S. Cetin ; G. Yanik
- Source: IET Power Electronics, Volume 4, Issue 7, p. 827 –834
- DOI: 10.1049/iet-pel.2010.0280
- Type: Article
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In this study, a new active snubber cell is proposed for pulse width modulated (PWM) converters. This snubber cell provides zero-voltage transition (ZVT) turn on and zero-voltage switching (ZVS) turn off for the main switch. In the converter with the new snubber cell, auxiliary switch is turned on with zero current switching and turned off with ZVS. Also, the main diode and all of auxiliary diodes are operating with soft switching (SS). At the same time, in this converter, all SS energy stored in the snubber inductance is transferred effectively to the output by a transformer, and so the current stress of the auxiliary switch is reduced significantly. Also, this transformer provides possibility of using the capacitors required for ZVS turning off of the main and auxiliary switches. In this converter, no semiconductor device has any additional voltage and current stresses and SS-operating conditions are maintained at very wide line and load ranges. In this study, detailed steady state analysis of the new ZVT-PWM boost converter is presented, and this theoretical analysis is verified experimentally by a 1 kW and 100 kHz prototype. - Author(s): S.S. Saha ; B. Majumdar ; S.K. Biswas
- Source: IET Power Electronics, Volume 4, Issue 7, p. 835 –841
- DOI: 10.1049/iet-pel.2010.0079
- Type: Article
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p.
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An improved fully soft-switched boost converter for active power factor correction is presented here. The converter uses an auxiliary circuit consisting of a switch, one inductor, a resonating capacitor and a diode. Unlike several earlier solutions, all switches used in this converter turn on and turn off under fully soft-switched condition. The boost diode also commutates softly and the auxiliary diode operates under soft-switched condition. The main switch of the converter does not suffer from additional current stress. Moreover, the main and auxiliary switches share a common emitter connection, facilitating direct drive to them. Various operating modes of the converter are presented and analysed in detail. The performance of the converter has been verified by means of computer simulation and experimental results. - Author(s): H.-L. Do
- Source: IET Power Electronics, Volume 4, Issue 7, p. 842 –849
- DOI: 10.1049/iet-pel.2010.0256
- Type: Article
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p.
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The interleaved multi-channel converter is very popular these days because of its ability to reduce current ripples. In this study, an interleaved boost converter with a single magnetic component is proposed. Interleaving operation and a loosely coupled inductor significantly reduce the ripple component of the input current. Moreover, zero-voltage-switching characteristic of the proposed converter reduces the switching losses and raises the overall efficiency. Experimental results based on an 80 W (170 V/0.47 A) prototype are provided to verify the effectiveness and feasibility of the proposed converter.
Analysis of a hybrid controlled three-phase grid-connected inverter with harmonics compensation in synchronous reference frame
Average and hysteresis current-controlled three-phase three-level unity power factor rectifier operation and performance
Common-emitter topology of multilevel current-source pulse width modulation inverter with chopper-based DC current sources
Implementation of discrete event control for brushless AC motor
Suppression of common-mode input electromagnetic interference noise in DC–DC converters using the active filtering method
Analysis, design and implementation of a quasi-resonant DC–DC converter
Experimental analysis of a new zero-voltage switching synchronous rectifier buck converter
Hybrid learning control strategy for three-phase uninterruptible power supply
Modelling and analysis of a capacitively coupled contactless power transfer system
Voltage and frequency control of asynchronous generator for stand-alone wind power generation
A new zero-voltage transition pulse width modulated boost converter
Improved active power factor correction circuit using a fully soft-switched boost converter
Interleaved boost converter with a single magnetic component
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