Prof. Dr. Joachim Holtz
Editor-in-Chief
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Prof. Dr. Joachim Holtz |
Special Section on High Power Factor Rectifiers - Part II
- Vienna Rectifier II - A Novel Single-Stage High-Frequency Isolated Three-Phase PWM Rectifier System
by Johann W. Kolar, Uwe Drofenik, Franz C. Zach
Abstract - Based on an analysis of basic realization possibilities the structure of the power circuit of a new single-stage three-phase boost-type PWM rectifier system (VIENNA Rectifier II) is developed. This system has continuous sinusoidal time behavior of the input currents and high-frequency isolation of the output voltage which is controlled in a highly dynamic manner. As compared to a conventional two-stage realization, this system has substantially lower complexity and allows to realize several isolated output circuits with minimum effort.
The basic function of the new PWM rectifier system is described based on the conducting states occurring within a pulse period. Furthermore, a straightforward space vector oriented method for the system control is proposed which guarantees a symmetric magnetization of the transformer. Also, it makes possible a sinusoidal control of the mains phase currents in phase with the associated phase voltages. By digital simulation the theoretical considerations are verified and the stresses on the power semiconductors of the new converter system are determined. Finally, results of an experimental analysis of a 2.5kW laboratory prototype of the system are given and the direct start-up and the short circuit protection of the converter are discussed. Also, the advantages and disadvantages of the new converter system are compiled in form of an overview.- Self-Oscillating Resonant AC/DC Converter Topology for Input Power Factor Correction
by Humberto Pinheiro, P. Jain, G. Joos
Abstract - This paper presents the analysis and design of a single-phase single-stage high power factor ac/dc converter employing a series-parallel resonant topology operating in self-sustained oscillating mode. A control approach is proposed to achieve low total harmonic distortion of the input current. This approach does not require sensing of the input current. In addition, the inverter output current is limited during transients, and the converter operates with zero voltage switching for all operating conditions including open and short circuit. The performance of the proposed scheme is verified experimentally on a 500 W prototype.
- An Alternative to Supply DC Voltages with High Power Factor
by Oscar Garcia, José A. Cobos, Roberto Prieto, Pedro Alou, Javier Uceda
Abstract - AC to DC is one of the most common power conversions in power electronics. DC loads should be fed with a stable and a tight regulated voltage. At the same time, the AC/DC converter should comply with low frequency harmonic regulation. The classical two-stage AC/DC converters achieve these two objectives, although the overall efficiency is low because the power is processed twice. An alternative solution is presented in this paper. It is based on the division of the input power in two parts, being one of them processed only once and keeping a unity power factor. This strategy improves the efficiency and reduces the size of the converter without any complex control scheme. This proposal can be implemented with a great variety of well-known topologies. The experimental results show that this solution is a good trade-off between efficiency and size.
- Design of a Power Factor Correction Converter based on Half Bridge Topology
by Jun-Young Lee, Gun-Woo Moon, Myung-Joong Youn
Abstract - A single stage AC/DC converter based on a half bridge topology suitable for low power level applications is proposed. The proposed converter has high power factor, low harmonic distortion,and tight output regulations. An asymmetrical control and synchronous rectification are employed to reduce the switching and rectification losses, respectively. The modelling and detailed analysis are performed to derive the design equations. Based on these design equations, a prototype converter has been designed and experimented. This prototype meets the IEC 61000-3-2 regulations with near unity power factor and high efficiency.
- Analysis and Design of a Practical Discontinuous Conduction Mode BIFRED Converter
by Michael J. Willers, M.G. Egan, J. M. D. Murphy, S. Daly
Abstract - Impending international standards on harmonic current levels drawn by single phase mains operated equipment have created a need for low-cost off-line power factor corrected switched mode power supply topologies in the power range up to a few hundred watts. The Boost Integrated / Flyback Rectifier / Energy storage / dc-dc converter (BIFRED) is one such topology which shows promise in this regard. In particular, the discontinuous conduction mode (DCM) BIFRED avoids the light load high voltage stress problem associated with the continuous conduction mode (CCM) design while still achieving the combined advantages of a low-cost single-stage topology with high displacement factor and low total harmonic distortion (THD). In this paper a practical DCM BIFRED converter with integrated low-loss snubber is investigated from both power and small-signal control perspectives. Design equations are given to ensure DCM operation under closed loop output voltage control in which switch duty cycle is varying. Experimental results on a prototype converter are also presented.
- An Alternative Approach to Synthesizing Single-Stage Converters with Power Factor Correction Feature
by Tsai-Fu Wu, Te-Hung Yu, Yuan-Chyuan Liu
Abstract - An alternative approach to synthesizing single-stage converters (SSC's) with power factor correction (PFC) feature is presented in the paper. The proposed approach is primarily based on the concept of dither effect, from which PFC cells composed of energy buffers and high frequency dither signals are introduced. Properly selecting an eligible PFC cell and inserting it in between input rectifier and dc-link capacitor can yield an SSC which can improve the input power factor significantly. In the paper, principle and configuration of PFC cells are addressed; thus, quite a few families of SSC's can be synthesized from the derived PFC cells. With this approach, not only the SSC's discussed in the literature can be developed alternatively, but novel SSC's can be synthesized. Most of the SSC's have been proved in the literature to be feasible in applications with moderate power levels.
- Integrated High Quality Rectifier-Regulators
by Mike Madigan, Robert Ericson, Esam Ismail
Abstract - A new family of ac-to-dc converters are derived which integrate the functions of low harmonic rectification, low frequency energy storage, and wide bandwidth output voltage control into a single converter containing one, two, or four active switches. These converters utilize a discontinuous conduction mode (DCM) input inductor, an internal energy storage capacitor, and transformer secondary circuits which resemble the bridge, forward, flyback, or Cuk dc-dc converters. A large signal equivalent circuit model for this family is presented which uses the "loss-free resistor" concept. Design strategies and experimental results are given. High performance regulation with satisfactory line current harmonics are demonstrated with conventional duty ratio control. Further improvements in line current are possible by simultaneous duty ratio and switching frequency control.
- Analysis and Design of an Isolated Single-Stage Converter achieving Power Factor Corrections and Fast Regulation
by Tsai-Fu Wu, Yu-Kai Chen
Abstract - This paper presents the analysis and design of an isolated single-stage converter achieving high power factor correction and fast regulation. By using the technique suggested in [1], a buck-boost converter and a flyback converter can be integrated to form the discussed converter. The buck-boost semi-stage working in the discontinuous conduction mode (DCM) functions as a power factor corrector, and the flyback semi-stage operating in the DCM is a voltage regulator which is controlled, theoretically, to be independent of load variation.
An approximated small-signal model of the converter operating in the DCM is developed. Design of a peak-current feedback loop with an optimal PI controller is also presented. A prototype is implemented to verify that the analysis and design are effective and feasible.- ZCS-PWM Full-Wave Boost Rectifier with Unity Power Factor and Low Conduction Losses
by Chien-Ming Wang, Guan-Chyun Hsieh
Abstract - A full-wave boost rectifier (FWBR) realized by zero-current-switching pulse-width-modulation (ZCS-PWM) control to achieve unity power factor is presented. Two resonant cells are configured in the presented FWBR to perform ZCS in the power switches and to pre-regulate the input current to follow up the input voltage. Only one diode and one power switch losses are included in the proposed FWBR during the rectification. Four transition states for describing the behavior of the ZCS-PWM FWBR in one switching period are described. A small-signal model is built for the system analysis, and an average-current-mode control is employed to formulate the input current waveform with low harmonics. The control strategy and design consideration are programmed to realize a 600-W ZCS-PWM FWBR, which provides high power efficiency of 95% and high power factor over 0.99.
- A Novel ZVT PWM Cúk Power Factor Corrector
by Ching-Jung Tseng, Chern-Lin Chen
Abstract - A novel zero-voltage-transition (ZVT) PWM Cuk power factor corrector (PFC) is proposed to achieve unity power factor under zero-voltage-switching (ZVS) operations. In the proposed ZVT PWM Cuk PFC, not only the power switch but also the power diode commutate under ZVS. The proposed topology has the shortest ZVT time and thus the shortest minimum duty cycle compared with other ZVT PWM topologies. The resonant inductor can be discharged regardless of the state of the main switch. Extremely short ZVT time and robust discharge of resonant inductor make the proposed topology well qualified for variable duty and high switching frequency applications. Analytical studies, design rules and experimental waveforms of the ZVT PWM Cuk PFC are presented in detail.
- Modeling of the High Power Factor Discontinuous Boost Rectifiers
by Domingos S. L. Simonetti, José Luiz F. Vieira, Gilberto C. D. Sousa
Abstract - This paper presents a modeling approach to obtain a small-signal model for a single-switch single-phase and three-phase discontinuous boost high power factor rectifiers. Such converters present nonlinear characteristics and an approximation of them is used to derive the models. The most important result obtained is that the small-signal output impedance is not equal to the load impedance. The analysis is validated by experimental results.
- Electronic Ballast with High Power Factor for Fluorescent Lamps
by Ricardo N. do Prado, Saul A. Bonaldo
Abstract - This paper describes a high power factor electronic ballast for fluorescent lamps. The converter offers a high power factor and a high frequency supply to the lamp using a single switch. In spite of its simplicity, an excellent performance concerning load and supply is achieved, ensuring a sinusoidal and in-phase supply current. High power factor is achieved by using a flyback converter operating in discontinuous-conduction mode. Operating principle, design equations, component stress, and efficiency are presented. Experimental results have been obtained for one 40W fluorescent lamp operating at 50kHz switching frequency and 220V line voltage.
- A New UPS Topology employing a PFC Boost Rectifier cascaded a High-Frequency Triport Converter
by Yu-Ming Chang, Jia-You Lee, Fang-Yu Liu
Abstract - A new UPS topology using the high-frequency tri-port UPS technique is proposed which presents the advantages of no-break power, low cost, input unity power factor, high power density and high power conversion efficiency. Through the proposed circuit configuration, charging concept and control strategy, the battery management is easily obtained by controlling the output voltage of power-factor-correction (PFC) converter and it results in non-additional power device is required for charging. The implementing circuit of the charging method is submitted to perform the two-stage charging, constant current charging and constant voltage charging. The proposed technologies can be applied to the switching power supply with build-in UPS function featuring a low cost solution for computer equipment. Finally, an experimental AC on-line UPS is built to verify the proposed concept, analysis and control strategy.
- A High Power Factor DC-Linked Resonant Inverter
by Chin-Sien Moo, Ching.R. Lee, Tsai F. Lin
Abstract - A new approach of power factor correction for the dc-linked high-frequency resonant inverters is proposed. The high power factor operation is achieved by altering the energy delivery process of the conventional used topology. The load resonant circuit of the proposed topology draws a high-frequency pulse current directly from the ac source. This approach can be accomplished merely with an additional small capacitor as the energy buffer and a diode as the energy transfer switch. The design and experimental results for an implementation example are given to verify the theoretical analyses.
- A New Single-Phase PWM Rectifier with Power Factor Correction
by Bor-Ren Lin, Hsin-Hung Lu
Abstract - A new control scheme for single-phase bridge rectifier with three-level pulse width modulation (PWM) is proposed to achieve high power factor and low current distortion. The main circuit consists of a diode bridge rectifier, a boost inductor, two ac power switches and two capacitors. According to the proposed control scheme based on a voltage comparator and hysteresis current control technique, the output capacitor voltages are balanced and the line current will follow the supply current command. The supply current command is derived from a dc link voltage regulator and an output power estimator. The major advantage of using three-level rectifier is that the blocking voltage of each ac power device is clamping to half of the dc link voltage and the generated harmonics of the three-level rectifier are less than those of the conventional two-level rectifier. There are five voltage levels (-Vdc, -Vdc/2, 0, Vdc/2, Vdc) on the ac side of the diode rectifier. The high power factor and low harmonic currents at the input of the rectifier are verified by software simulations and experimental tests.
Short Paper
- A Single-Stage High Power Factor Electronic Ballast with Duty-Ratio Controlled Series Resonant Inverter
by Chin-Sien Moo, Shun Y. Chan, Ching R. Lee
Abstract - A single-stage high power factor electronic ballast is developed by making integration of an active filter and a series resonant inverter. The function of power factor correction is performed by adjusting the duty-ratio of inverter power switches with a simple control circuit. A prototype unit designed for a 36-W compact fluorescent lamp is built and tested to verify the predicted results.
Drive Control
- A Low Cost Sensorless Technique for Load Torque Estimation in a Hybrid Stepping Motor
by J. D. Wale, C. Pollock
Abstract - This paper presents a method of torque measurement in a hybrid stepping motor without the use of speed or position sensors. It is shown that torque ripple can be minimised by appropriate shaping of the phase current pulses and that efficiency can be maximised when the level of mechanical load applied to the shaft is known. A controller is described which generates a signal related to the mechanical load by observation of the phase current profile using a novel low complexity technique. Practical results are presented showing the torque estimation relative to measured torque.
Signal Processing
- A Multiprocessor-Oriented Visual Tracking System
by Stefano Rovetta, R. Zunino
Abstract - The design and prototypal realization of a visual tracking system is presented. The approach to target identification is non-conventional in that it relies on an architecture composed of multiple standard neural networks (multilayer perceptrons), and exploits the information contained in simple features extracted from images, performing a small number of operations. Therefore, the tracking functions are learned by examples, rather than implemented directly. The system demonstrates that a quite complex task such as visual target tracking can be easily obtained by a suitable neural architecture. The fast tracking algorithm and the parallel structure allow a true real-time operation. The system exploits a two-level neural-network hierarchy with a number of parallel networks and an "arbiter." The training set consists of various geometrical shapes, pre-processed to yield the data vectors. The experimental hardware implementation is based on multiple processing units, implementing the neural architecture, and serves a prototype for the analysis of the system in practice. A small-sized realization can also be obtained.
Emerging Technologies
- Fuzzy Associative Memory Based Knowledge Construction with an Application to a Human-Machine Interface
by Hirohide Ushida, Toru Yamaguchi, Tomohiro Takagi
Abstract - A construction method of fuzzy knowledge is proposed in order to be applied it to human-machine interfaces. This paper considers human movements estimation system to be one of the interfaces. This estimation system transforms human physical movements into qualitative linguistic labels. For example, the degrees of magnitude and speed of the physical movement are represented by qualitative words. It is difficult to construct the transformation knowledge because the relation between the movements and the labels is fuzzy. This paper proposes a method of constructing the knowledge. This proposed method uses Fuzzy Associative Memory Organizing Units System (FAMOUS) and is applied to estimating human sports movements. Experimental results show that the proposed method is suitable for application to the human-machine interfaces.
Short Papers
- A New Circuit for measuring Power Factor in Non-Sinusoidal Load Current
by Kuen-Der Wu, Hurng-Liahng Jou, Jhy-Shoung Yaung
Abstract - This paper presents a new method for measuring the power factor in nonsinusoidal load current. The proposed method is based on the technique of sampling and holding the amplitude of the real part of the load current. Because no Fourier or Fast Fourier Transform calculation is used, this method can be implemented by a simple electronic circuit.
- A Reduced Hysteresis Controller for a Four-Switch Three-Phase Bidirectional Power Electronics Interface
by Yu-Kang Lo, Huang-Jen Chiu, Wen-Tsair Li
Abstract - A reduced hysteresis controller for a four-switch three-phase bidirectional power electronics interface is proposed in this letter. Polarity detection of the input voltages to determine the switching states is not required. The circuit is simple. Experimental results show unity input power factor operation and bidirectional power transfer capability.
- An Effective Software Implementation of the Space Vector Modulation
by Jang-Hyoun Youm, Bong-Hwan Kwon
Abstract - An effective software implementation of the space vector modulation (SVM) for current control on the rotating d-q frame is proposed. The conventional SVM algorithm is based on the magnitude and angle of the required voltage vector, and its implementation requires square root and arctangent. The SVM algorithm is further developed to determine directly conduction times of switches and its implementation does not require complex computations.
- A Nonlinear Control Method for Good Dynamic Performance Elastic Drive
by Rached Dhaouadi, Kenji Kubo
Abstract - This letter presents a nonlinear speed controller for two-mass-model elastic systems. The nonlinear controller is designed to provide a highly damped step response with minimum response time and minimum overshoot. The controller synthesis is carried out in the phase-plane. The simulation results indicate the effectiveness of the proposed nonlinear control system.
