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Author

Kevin Lee

Other affiliations: University of Wisconsin-Madison
Bio: Kevin Lee is an academic researcher from Eaton Corporation. The author has contributed to research in topics: Harmonics & Voltage source. The author has an hindex of 20, co-authored 82 publications receiving 1184 citations. Previous affiliations of Kevin Lee include University of Wisconsin-Madison.


Papers
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Journal ArticleDOI
TL;DR: The simultaneous online estimation algorithm of rotor time constant and rotor speed for a speed-sensorless induction machine is proposed and the impact of stator resistance error is severely reduced by the closed-loop structure of combined voltage and current (UI) mode flux observer.
Abstract: The simultaneous online estimation algorithm of rotor time constant and rotor speed for a speed-sensorless induction machine is proposed With a small signal injected to the flux command, the method can accurately complete the online tuning of Tr over a wide range of speed estimation, including the rated speed and the very low speed of 1 Hz or even lower speeds under both no-load and loaded operations Sensitivity of stator resistance error is studied, and the impact of stator resistance error on this method is severely reduced by the closed-loop structure of combined voltage and current (UI) mode flux observer The identification process only needs the ac component amplitude without considering ac component phase drifts; thus, the division by zero at the zero-crossing point is avoided, which greatly increases the accuracy Furthermore, any differential integral operations or even a filter is not needed; hence, the computation is rather simple and time saving Moreover, unlike other signal injection methods, there are no special requirements on the injected signal frequency The accuracy and validity of the method has been verified by Matrix Laboratory simulation model Further experimental results on a 22-kW 50-Hz 4-pole induction motor also show effectiveness of this proposed method

75 citations

Journal ArticleDOI
01 Nov 2004
TL;DR: In this article, the effects of the input voltage unbalance and sags on the DC bus electrolytic capacitors in adjustable-speed drives (ASDs) were analyzed to predict their impact on expected capacitor lifetime.
Abstract: This work analyzes the effects of the input voltage unbalance and sags on the DC bus electrolytic capacitors in adjustable-speed drives (ASDs) in order to predict their impact on expected capacitor lifetime. The key phenomenon that causes these problems is the transition of the rectifier stage from three-phase to single-phase operation. Since the ESR (equivalent series resistance) increases at low frequencies, the low-order harmonic current components (120 Hz, 240 Hz, etc.) contribute disproportionately to the capacitor power losses and temperature rise, resulting in reduced lifetime. Closed-form expressions are developed for predicting these effects including the impact of finite line impedance, finite bus capacitance, and varying load. The impact of inverter SVPWM (space vector pulse width modulation) switching on the capacitor loss is also included. Simulations and experimental tests are used to verify the accuracy and effectiveness of the closed-form analysis using a 5 hp ASD system.

70 citations

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a method to automatically obtain the total output voltage delay curve, which is a significant part of the inverter voltage error model, in order to improve the performance of sensorless field-oriented controlled motor drives at low speed.
Abstract: In order to improve the performance of sensorless field-oriented controlled motor drives at low speed, the inverter nonlinearity should be compensated for by an accurate voltage error model. This paper proposes a novel method to automatically obtain the total output voltage delay curve, which is a significant part of the inverter voltage error model. Unlike manual measurements of the output delays in earlier literature works, the proposed automatic measurement method achieves low cost in time and labor. Meanwhile, the compensation accuracy based on the automeasured output voltage delay curve is approaching to the performance of compensation by the manual measurement method, far better than the accuracy of compensation by the standard square-wave model at low speed. Moreover, in contrast to other inverter nonlinearity automeasurement methods, the measured results of the proposed method can be applied to compensate for inverter nonlinearities at different switching frequencies. The effectiveness of this method is validated in a voltage source inverter fed induction motor drive system experimentally.

67 citations

Journal ArticleDOI
TL;DR: In this paper, the authors provided an approximate closed-form analysis of the impact of line-voltage sags and unbalance on the induction-machine phase voltages, currents, and torque pulsations for a general-purpose adjustable-speed drive (ASD) consisting of a three-phase diode bridge rectifier, a dc link, and a pulsewidth modulation (PWM) inverter delivering constant volts-per-hertz excitation.
Abstract: Voltage unbalance or sag conditions generated by the line excitation can cause the input rectifier stage of an adjustable-speed drive (ASD) to enter single-phase rectifier operation. This degradation of the input power quality can have a significant negative impact on the induction-machine performance characteristics. This paper provides an approximate closed-form analysis of the impact of line-voltage sags and unbalance on the induction-machine phase voltages, currents, and torque pulsations for a general-purpose ASD consisting of a three-phase diode bridge rectifier, a dc link, and a pulsewidth modulation (PWM) inverter delivering constant volts-per-hertz excitation. Attention is focused on the impact of the dominant second harmonic of the line frequency, which appears in the dc link voltage during the sag/unbalance conditions, neglecting the impact of the other higher order harmonics. In addition to the closed-form analytical results that assume constant rotor speed, both simulation and experimental results are presented, which confirm the key analytical results, including the dominance of the second harmonic in the resulting torque pulsations. The analytical results can be used as a valuable design tool to rapidly evaluate the approximate impact of unbalance/sag conditions on ASD machine performance.

65 citations

Journal ArticleDOI
TL;DR: In this article, the theoretical power spectrum analysis as the basis for random PWM in industrial and commercial adjustable-speed drives (ASD) is presented, and five state-of-the-art PWM strategies, their voltage, current, and acoustic noise spectra characteristics are quantitatively evaluated.
Abstract: One of the problems of the pulse-width-modulation (PWM)-controlled ac machines is the acoustic noise that could become unacceptable when used in sensitive environments. Random PWM (RPWM) in industrial and commercial adjustable-speed drives (ASD) results in the partial transfer of power from the discrete spectrum (narrowband noise) of the output voltage to the continuous spectrum (wideband noise), with advantageous effects on reducing the acoustic noise in the motor drive system. In this paper, the theoretical power spectrum analysis as the basis for RPWM is presented. Five state-of-the-art RPWM strategies, their voltage, current, and acoustic noise spectra characteristics are quantitatively evaluated. The PWM schemes and theoretical analysis are validated through a 2.2-kW 380-V 50-Hz ASD induction machine experimental setup. The results provide valuable data for practicing engineering community to choose the best option in real-world applications.

65 citations


Cited by
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Journal ArticleDOI
TL;DR: Digital Control Of Dynamic Systems This well-respected, market-leading text discusses the use of digital computers in the real-time control of dynamic systems with an emphasis on the design of digital controls that achieve good dynamic response and small errors while using signals that are sampled in time and quantized in amplitude.
Abstract: Digital Control Of Dynamic Systems This well-respected, market-leading text discusses the use of digital computers in the real-time control of dynamic systems. The emphasis is on the design of digital controls that achieve good dynamic response and small errors while using signals that are sampled in time and quantized in amplitude. Digital Control of Dynamic Systems (3rd Edition): Franklin ... This well-respected, market-leading text discusses the use of digital computers in the real-time control of dynamic systems. The emphasis is on the design of digital controls that achieve good dynamic response and small errors while using signals that are sampled in time and quantized in amplitude. Digital Control of Dynamic Systems: Gene F. Franklin ... Digital Control of Dynamic Systems, 2nd Edition. Gene F. Franklin, Stanford University. J. David Powell, Stanford University Digital Control of Dynamic Systems, 2nd Edition Pearson This well-respected work discusses the use of digital computers in the real-time control of dynamic systems. The emphasis is on the design of digital controls that achieve good dynamic response and small errors while using signals that are sampled in time and quantized in amplitude. MATLAB statements and problems are thoroughly and carefully integrated throughout the book to offer readers a complete design picture. Digital Control of Dynamic Systems, 3rd Edition ... Digital control of dynamic systems | Gene F. Franklin, J. David Powell, Michael L. Workman | download | B–OK. Download books for free. Find books Digital control of dynamic systems | Gene F. Franklin, J ... Abstract This well-respected work discusses the use of digital computers in the real-time control of dynamic systems. The emphasis is on the design of digital controls that achieve good dynamic... (PDF) Digital Control of Dynamic Systems Digital Control of Dynamic Systems, Addison.pdf There is document Digital Control of Dynamic Systems, Addison.pdfavailable here for reading and downloading. Use the download button below or simple online reader. The file extension PDFand ranks to the Documentscategory. Digital Control of Dynamic Systems, Addison.pdf Download ... Automatic control is the science that develops techniques to steer, guide, control dynamic systems. These systems are built by humans and must perform a specific task. Examples of such dynamic systems are found in biology, physics, robotics, finance, etc. Digital Control means that the control laws are implemented in a digital device, such as a microcontroller or a microprocessor. Introduction to Digital Control of Dynamic Systems And ... The discussions are clear, nomenclature is not hard to follow and there are plenty of worked examples. The book covers discretization effects and design by emulation (i.e. design of continuous-time control system followed by discretization before implementation) which are not to be found on every book on digital control. Amazon.com: Customer reviews: Digital Control of Dynamic ... Find helpful customer reviews and review ratings for Digital Control of Dynamic Systems (3rd Edition) at Amazon.com. Read honest and unbiased product reviews from our users. Amazon.com: Customer reviews: Digital Control of Dynamic ... 1.1.2 Digital control Digital control systems employ a computer as a fundamental component in the controller. The computer typically receives a measurement of the controlled variable, also often receives the reference input, and produces its output using an algorithm. Introduction to Applied Digital Control From the Back Cover This well-respected, marketleading text discusses the use of digital computers in the real-time control of dynamic systems. The emphasis is on the design of digital controls that achieve good dynamic response and small errors while using signals that are sampled in time and quantized in amplitude. Digital Control of Dynamic Systems (3rd Edition) Test Bank `Among the advantages of digital logic for control are the increased flexibility `of the control programs and the decision-making or logic capability of digital `systems, which can be combined with the dynamic control function to meet `other system requirements. `The digital controls studied in this book are for closed-loop (feedback) Every day, eBookDaily adds three new free Kindle books to several different genres, such as Nonfiction, Business & Investing, Mystery & Thriller, Romance, Teens & Young Adult, Children's Books, and others.

902 citations

01 Jan 2016
TL;DR: This power electronics converters applications and design helps people to enjoy a good book with a cup of tea in the afternoon, instead they cope with some malicious virus inside their desktop computer.
Abstract: Thank you for downloading power electronics converters applications and design. Maybe you have knowledge that, people have look numerous times for their favorite readings like this power electronics converters applications and design, but end up in harmful downloads. Rather than enjoying a good book with a cup of tea in the afternoon, instead they cope with some malicious virus inside their desktop computer.

754 citations

Journal ArticleDOI
TL;DR: In this article, the effects of unbalanced voltage on doubly fed induction generators are analyzed and a novel control strategy based on direct power control (DPC+) applied to this type of generators, predominant in wind energy applications, that enables them to work under perturbed conditions and achieve optimum results.
Abstract: This paper analyzes the effects of unbalanced voltage on doubly fed induction generators. It also presents a novel control strategy based on direct power control (DPC+) applied to this type of generators, predominant in wind energy applications, that enables them to work under perturbed conditions and achieve optimum results. Although the technique can be implemented to control both rotor converters and grid converters, we will hereby exemplify the former which regulates stator active and reactive power. The results obtained with DPC+ are then compared through experimental tests to indicate that the technique is suitable and achieves good dynamic responses while controlling current distortion, power or torque oscillations. The validation of results has been performed through experimental tests on a 20-kW generator.

191 citations

Journal ArticleDOI
TL;DR: In this paper, a three-phase, five-level inverter topology with a single-dc source is presented by cascading a 3-level flying capacitor inverter with a flying H-bridge power cell in each phase.
Abstract: In this paper, a new three-phase, five-level inverter topology with a single-dc source is presented. The proposed topology is obtained by cascading a three-level flying capacitor inverter with a flying H-bridge power cell in each phase. This topology has redundant switching states for generating different pole voltages. By selecting appropriate switching states, the capacitor voltages can be balanced instantaneously (as compared to the fundamental) in any direction of the current, irrespective of the load power factor. Another important feature of this topology is that if any H-bridge fails, it can be bypassed and the configuration can still operate as a three-level inverter at its full power rating. This feature improves the reliability of the circuit. A 3-kW induction motor is run with the proposed topology for the full modulation range. The effectiveness of the capacitor balancing algorithm is tested for the full range of speed and during the sudden acceleration of the motor.

188 citations

01 Jan 2016
TL;DR: The vector control and dynamics of ac drives is universally compatible with any devices to read, and will help you to get the most less latency time to download any of the authors' books like this one.
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181 citations