Power Electronic Engineers Research Articles

Measurement of Parasitic Inductances in the Bus-Bar Assembly of a High Power Voltage Source Converter

Insulated gate bipolar transistor (IGBT) based voltage source converters use copper plates with insulating sheets in between them (sandwich bus-bar arrangement) for connecting the different device terminals in the power circuit. In such converters, the parasitic inductances in the power circuit are crucial as they cause overvoltage spikes across the device. Also, the parasitics affect the current sharing between IGBTs when they are connected in parallel in high power converters. The conduction path through plates and fasteners in the bus-bar assembly is three-dimensional and quite complex, making analytical evaluation of the stray inductance quite challenging. The first objective here is to present a simple experimental setup and experimental procedure, which are convenient for power electronic engineers, to measure the bus-bar inductance. The next objective is to carry out experimental studies on the inductances offered by different components and sub-assemblies in a bus-bar assembly. This includes evaluation of inductances of the different conduction paths in typical bus-bar plates. The third objective is to experimentally evaluate the parasitic inductances in the bus-bar assembly of a commercial 250 kVA high power converter. Each leg of this converter consists of two 300 A/1200 V IGBTs connected in parallel. The effective inductance seen by the individual device modules are determined experimentally.

Control of Bifurcation Behaviour of the Buck Converter via a Resonant Parametric Perturbation Circuit

Nonlinear circuits and systems research has been growing very quickl y over the past two decades. Activel y pursued in almost every branch of science and engineering, nonlinear systems theory luis found wide applications in a variety of practical engineering problems. Engineers, scientists and mathematicians have similarly advanced from the passive role of simpl y anal yzing, or identifying chaos to their present, active involvement in controlling chaos — control directed not onl y at suppression, but also at exploiting its enormous potential. We now stand at the threshold ofmajor advances in the control and synchronization of cluios for new applications across the range of engineering disciplines. All feedback controlled power converters exhibit certain non-linear phenomena over a specific breadth of parameter values. Despite being commonly encountered hy power electronics engineers, these non-linear phenomena are by and large not thoroughl y understood by engineers. Such phenomena remaining somewhat mysterious and hardl y ever been examined in a formal way. As the discipline of power electronics becomes more matured, demand for better functionality, dependability and performance of power electronics circuits will inevitably force researchers to engage themselves in more detailed stud y and analysis of non-linear phenomena and complex behaviour of power electronics converters. The bifurcation behaviour of the back converter occurs when the input voltage is varied. In this study, the computer simulation scheme, PSPICE is employed to model the behaviour of the ideal back converter. For certain values of the input voltage Vin instability occurs. The resonant parametric perturbation method is then applied to control the bifurcation behaviour of the voltage-mode controlled back converter. Analysis and simulations are presented to provide theoretical and practical evidence for the proposed control method. As the back converter has wide industrial application, it would be deemed necessary for designers to know about its bifurcation behaviour and how to control such behaviour.

APEC Guides Engineers to Latest Advances in Power Devices, Components, and Packaging: High-voltage gallium nitride transistors and the new generation of digital controllers

Continuing its long-standing tradition of addressing issues of immediate and long-term interest to practicing power electronics engineers, the IEEE Applied Power Electronics Conference and Exposition (APEC) celebrated its 30th anniversary this year in Charlotte, North Carolina, 15-19 March. While many advances and innovations in areas ranging from power semiconductor devices to circuit components and packaging were presented, two key trends took center stage: the availability of high-voltage gallium nitride (GaN) transistors with improved reliability, among other widebandgap devices, and the new generation of digital controllers for smooth transition from analog to digital power management in dc-dc and ac-dc power converters. In addition, the Power Sources Manufacturers Association (PSMA) presented its technology report on threedimensional (3-D) power packaging with a focus on embedded substrate technologies.

Bifurcation Behaviour of the Buck Converter

The bifurcation and chaos phenomena appeared in power system have become a focus subject at present. It has become apparent about a decade ago that power converters exhibit various types of non-linear behaviour which includes all kinds of bifurcations and chaos. Even basic DC/DC converters exhibit bifurcation and chaos phenomena as well as parallel-connected DC/DC converters and PFC system. The main source of such non-linearity is the switching mechanism of the converters. Non-linear components of the converter circuit and control scheme such as the use of naturally-sampled, constant-frequency PWM further contribute to the non-linear behaviour of converters such as a DC-to-DC buck converter. Thus, all feedback controlled power converters exhibit certain non-linear phenomena over a specific breadth of parameter values. Despite being commonly encountered by power electronics engineers, these non-linear phenomena are by and large not thoroughly understood by engineers. This paper examines the bifurcation behaviour of the buck converter in an ideal case when the input voltage is varied. The computer simulation scheme, PSPICE is employed to model the behaviour of the ideal buck converter. For certain values of the input voltage, Vin instability occurs. The analysis and conclusion presented in this paper will provide an overview of the bifurcation behaviour of the DC-to-DC buck converter, aspiring to draw attention of the power electronics and the circuits and systems communities to a field that is not often researched and examined.

A New Must-Read Magazine for Power Electronics Engineers [From the Editor

Presents the editorial for this issue of the publication.

MODELING AND SIMULATION OF SOLAR PHOTOVOLTAIC MODULE USING MATLAB/SIMULINK

This paper presents the circuit model of photovoltaic (PV) module. Simulation and modeling is done using MATLAB/ Simulink software package. The proposed model is user friendly and can be used as a common platform for both applied physics scientist and power electronics engineers. A detailed modeling procedure is presented. The designed model is verified by using STP255-20/Wd PV module. The IV and PV characteristics are simulated at different temperature and irradiance conditions and the results are verified. The proposed model is very simple fast and accurate. The designed model can be used for analysis of PV characteristics and for simulation of maximum power point tracking algorithms. I. INTRODUCTION Energy is required for large number of purposes. Traditional energy is used from coal, natural gas, oil and nuclear energy. But they are exhaustible and polluting. So we need to find an alternate source which is renewable energy source. This can be more extensively used in many applications. Solar energy is a good option and the electricity produced is clean, long lasting, no moving parts, less maintenance and silent. It has experienced a remarkable growth for the past two decades in its widespread use from standalone and utility interactive PV systems (1, 2). The increase in a number of photovoltaic system installed all over the world brought the need for proper supervision and control algorithms as well as modelling and simulation tool for researcher and practitioners involved in its application is very mandatory. The modelling and simulation of PV have made a great transition and play a vital role in power generation. Simple circuit models have been proposed in literature (3, 4). Even though they are interesting, they are very tedious complicated and impractical. Thus because of numerical challenges, an accurate and comprehensive design of PV system in MATLAB Simulink model is proposed. In this paper modelling is limited to simulation of PV module characteristics. In section II, a simple circuit with detailed circuit modelling of PV module is presented for the design of PV system. In section III, physical equations governing the PV module are presented. A Simulink model is developed for each equation of PV module. In section IV, the numerical result for different temperature and irradiance conditions is presented. Section V presents the discussion and conclusion of the modelling process. II. BASIC CIRCUIT AND MATHEMATICAL MODEL A PV module consists of number of solar cells connected in series and parallel as per the requirement. When solar light falls on PV cell, light energy is converted to electrical energy without any moving parts. The transmitted light is absorbed within the semiconductor, by using this light energy to excite the free electrons from the low energy status to an unoccupied higher energy level. These excess electron hole pairs contribute to the flow of current. A general mathematical description of I-V output characteristics for a PV cell has been researched and analysed for the past four decades. Such an equivalent based circuit based model is mainly used for the Maximum power point tracking techniques (MPPT) (5, 6). Authors (7, 8, 9) discussed about solar power extraction. The equivalent circuit of the general model which consists of a photon current, a diode, a parallel resistor expressing a leakage current, and a series resistor describing an internal resistance to the flow of current is shown in Fig. 1. The current (Ipv) - voltage (Vpv) equation of a solar cell is given by:

A new approach to time domain analysis of perturbed PWM push-pull DC-DC converter

In this paper, an analytical technique is presented for time domain analysis (transient and steady-state response) of perturbed PWM push-pull DC-DC converter using interesting corollary on Kharitonov’s theorem. The main advantage of the proposed analysis is that even though the transfer function model of a PWM push-pull DC-DC converter is perturbed, the complete analysis has been done on a linear transfer function model of a PWM push-pull DC-DC converter. The proposed analysis is verified using MATLAB simulation. This analysis will be very much useful to power electronics engineers, since the technique is very simple and computationally efficient and easily applicable in precise applications such as aerospace applications.

An analysis of approaches to developing converters for power engineering based on vacuum switching-type electronic devices

The technical feasibility of using electron-beam valves of the EBV 2/200, EBV 4/40, and EBV 50/100 types in power electronic engineering, including static reactive-power compensators or integrated power-flow controllers, was considered at line voltages of 20–35 kV without using high-voltage transformers. A physical analog of bridge and half-bridge inverters on the basis of the EBV 4/40 valve with pulse-width modulation with a sampling rate of 1–2 kHz was built.

Practical Experiences with Li-Ion Traction Accumulator in an Electric Bike

An electric bike (1kW) with a Li-Ion accumulator 28V/42A was constructed and tested in the Department of power electrical and electronic engineering. Panasonic cells CGR18650C (ca 2Ah) are used in the accumulator. The battery is completed with 7 serial-connected blocks. Each block is a set of 21 parallel-connected cells. The accumulator was tested in the vehicle since 2005 till now. During the tests a distance of approx. 12000km was driven. Some theoretical know-how about the used charging and discharging strategy and about the battery management system is proposed in this contribution. Practical results regarding the lifetime, capacity decreasing, charging problems, temperature dependencies and cell voltage balancing are visible from the long-time experiment described in this contribution too.

Recent Patents on Conducted Electromagnetic Interference Reduction Techniques in Power Electronic Systems

This paper surveys recent patents on conducted electromagnetic interference (EMI) reduction techniques for power electronic applications, i.e. switched-mode power supplies and electric drives. Most essential patents currently available are classified into three categories: switching control techniques, modifying topology techniques, and filtering techniques. Significant patented techniques are not only summarized and reported in details, but the usefulness and limitation of benchmarked techniques are also discussed. With this classification and summarization, it would be helpful for power electronic design engineers to be able to appropriately choose EMI reduction techniques with minimum hassle.

A GUI-Based Education Toolbox for Power Electronics Converters Using MATLAB/Simulink and SimPowerSystems

A power electronics course is essential for electrical engineers and is typically included in the undergraduate-level syllabus. Power electronics converters (PECs) are widely used to provide power processing for applications ranging from communications and medical electronics to motor drives, power conversion and high-power transmission, making them one of the most important topics for power electronics engineering. This paper presents an educational graphical user interface (GUI) for simulation of various topologies of PECs which students can use to explore the behaviour of PECs. The GUI is developed by using Matlab/Simulink, SimPowerSystems and the GUIDE tool of MATLAB, which acts as a front-end interface that can be used for teaching as well as learning. The positive response from students indicates that the comprehensive GUI package is extremely useful for power electronics courses. The package can be considered as a virtual laboratory or as a useful learning tool for the power community.

A Dynamic Voltage Restorer Equipped With a High-Frequency Isolated DC–DC Converter

This paper presents a dynamic voltage restorer (DVR) that is characterized by the use of a high-frequency unidirectional isolated dc-dc converter. A traditional DVR has a large and bulky series transformer even for three-phase low-voltage up to 480-V applications because the transformer operates at the line frequency (50 or 60 Hz). The emergence of state-of-the-art semiconductor devices and magnetic cores has driven power electronic engineers to develop compact high-frequency isolated dc-dc converters. This paper discusses the control and performance of a low-voltage DVR using a high-frequency isolated dc-dc converter. The high-frequency (20-kHz) transformer in the dc-dc converter is much smaller, for example, one-hundredth, in volume than the line-frequency transformer. Moreover, connecting the shunt converter to the load side brings a significant reduction in energy-storage capacity to the DVR. Experimental results obtained from a three-phase three-wire 200-V 5-kW laboratory system confirm the viability and effectiveness of the system configuration.

Performance Comparison of Three-Phase Shunt Active Power Filter Algorithms

The usage of parallel converters is ever increasing. However, the voltage and current harmonics, zero-sequence and negative- sequence components of voltage and current and reactive power present in parallel converters give an alarming signal to power system and power electronic engineers. This research discusses performance of three-phase shunt active power filter (APF) system using three different control techniques namely synchronous detection algorithm (SDM), instantaneous active and reactive (p-q) theory and instantaneous direct and quadrature (d-q) current method for the control of zero and negative sequence components, reactive power and harmonics. The novelty of this research lies in the successful application of SDM based APF and (d-q) current method APF for the control of reactive power, harmonics and negative and zero sequence currents resulted by the use of parallel three-phase converters. MATLAB 6.1 toolbox is used to model the systems.

High frequency model of an electric motor based on measurement results

In a motor drive system, a voltage source converter with hard switches generates high dv/dt, which causes leakage currents due to stray capacitances in an electric motor. A high frequency model of an electric motor is an important issue for power electronic engineers, which helps them analyse leakage and bearing currents, and design EMI filters. At low frequency ranges, an equivalent circuit of an electric motor consists of inductances and resistances without considering stray capacitances and skin effects. These issues become more important at high frequencies, particularly in fast switching applications due to high dv/dt. An impedance of a 5.5 kW motor has been measured in terms of frequency using an impedance analyser and the results have been used to extract high frequency parameters. It is recommended to estimate the behaviour of the motor in a frequency range when the motor acts as a capacitive or an inductive load according to the phase values of the impedance. Then, the parameters can be calculated directly from the magnitude and the phase values of the impedance. A simple model of an electric motor at high frequency used for high speed switching applications is discussed in this research work.

Control and Power Research Group, Electrical & Electronic Engineering Department, Imperial College London(Our Research Group)

Control and Power Research Group, Electrical & Electronic Engineering Department, Imperial College London(Our Research Group)

Interactions Between Fuel Cells and Power Converters: Influence of Current Harmonics on a Fuel Cell Stack

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> As fuel cells are likely to be used in many future applications, dedicated power converters must be developed and optimized. A thorough knowledge of the fuel cell operation is thus required for power electronics engineers. This paper proposes a theoretical and experimental study of the behavior of a fuel cell stack subject to current harmonics. The fundamental role of the internal double layer capacitor is demonstrated. </para>

可変周波数形無損失共振器を用いた単相電圧形PWMインバータによる任意波形出力制御

Power supplies used on the electric power environment test process for electronic products and audio-amplifiers are required to generate arbitrary ac voltage waveforms in the wide frequency range. Traditionally, analogue amplifier technologies have been used for those application even though those have the disadvantages of low-efficiency, bulky in volume, and heavy in weight. Recently, however, research on the arbitrary waveform power generator becomes to be attractive among power electronics engineers, because the audio amplifiers utilizes the D-Mode switching technologies have been move into the market. This paper presents an arbitrary ac power generator utilizes a novel instantaneous waveform control method for a single-phase voltage source PWM inverter. A remarkable feature of this control method is that an adaptive frequency band-pass filter based on a rotation frame transformation and a command generator on the rotation frame is used. The proposed method can suppress the resonance caused by the LC filter at the output line, and hence it enables to generate a rectangular voltage waveform without overshoot. The command generator generates both an instantaneous frame angle and accurate voltage commands on the rotating frame from one an analogue signal. The effectiveness of this method is verified through 500W experimental set-up.

A MECHANICAL DARLINGTON MODEL FOR MEMS APPLICATIONS

This paper presents the design and Micro-Electro-Mechanical-System (MEMS) realization of a Darlington-pair circuit used in power electronics engineering. MEMS are integrated micro devices or systems combining electrical and mechanical components fabricated using integrated circuits processing techniques. The size range of the components is from micrometers up to a couple of millimeters. Current MEMS applications include almost all engineering fields. Since MEMS is a newly developed technology, very few studies have been carried out directly on knowledge transferring from different engineering disciplines. The objective of this paper is to demonstrate a mechanical model developing of a power electronic circuit, to characterize and to analyze its performance and its suitability to MEMS application.

Problem-Based and Project-Oriented Learning. An Efficient Way to Implement Research Based Teaching in Power Electronic

Power electronics is an emerging technology. New applications are added every year as well as the power handling capabilities is steadily increasing. One example is renewable energy, which is efficiently enabled by power electronics. The demands to the education of engineers in this field are also increasing. Generally, the content of the curriculum should be more expanded without extra study time. This paper presents a teaching approach, which very fast makes it possible for the students to obtain in-depth skills into new research areas, and this method is the problem-oriented and project-based learning. The necessary skills for power electronic engineers are outlined that is followed up by a description on how the problem-oriented and project-based learning are implemented. A complete curriculum in power electronics and drives at Aalborg University is presented where different power electronics related projects at different study levels are finally presented.

How Power Electronics Engineers Should Write and Present Technical Papers in English

This paper describes techniques that Japanese power electronics engineers can use to improve the quality of their technical papers written in English and the accompanying technical presentations. These techniques are based on the experience that the author has gained by participating in international conferences. Such techniques are important to discuss because the significant differences exist in writing and presentation styles between Japanese and American engineers. The author believes that such style differences are caused by differences between the Japanese and American cultures. The objective of this paper is to help Japanese engineers understand these cultural differences and improve their technical communication skills in English. The paper also includes some practical tips on writing and presentation techniques for improving the quality of their technical communications in English.