Area Of Power Electronics Research Articles

Model Predictive Control: A Review of Its Applications in Power Electronics

Model-based predictive control (MPC) for power converters and drives is a control technique that has gained attention in the research community. The main reason for this is that ?although MPC presents high computational burden, it can easily handle multivariable case and system constraints and nonlinearities in a very intuitive way. Taking advantage of that, MPC has been successfully used for different applications such as an active front end (AFE), power converters connected to resistor?inductor RL loads, uninterruptible power supplies, and high-performance drives for induction machines, among others. This article provides a review of the application of MPC in the power electronics area.

Laser Micro Welding for Ribbon Bonding

Abstract Laser ribbon bonding is a new field of application for laser micro welding in the electronics industry especially in the area of power electronics. Traditional ribbon bonding is conducted by using ultrasonic welding to create the bond between the aluminum or copper ribbon and a conductive surface. By adapting an ultrasonic ribbon bonder and equipping it with a fiber laser, a galvanometric scanner and a beam focusing and delivery system, a new technology for ribbon bonding is created. The presented work includes test results of the welding of copper ribbons with a thickness of 300 μm to DCB-substrates and the system design of the “laser bonder”. For the laser welding of the ribbons spatial power modulation is being used and the effect of this approach on the welded ribbons is presented. The work concludes with advantages and limits of the technology especially concerning the applications compared to ultrasonic bonding.

Educational Applications of Interactive Tools to Analyze, Design, and Simulate D.C.-D.C. Power Converters

Currently, interactivity is playing a fundamental role in engineering education because of the development of communications and systems. An important challenge is the effective use of computer tools that allow associating teaching methods with the new ways students learn. In the area of power electronics, recognizing different concepts of switching converters is simplified, given simulation and experimentation tools. Nevertheless, general-purpose tools applied in the analysis and simulation of power electronics systems do not make use of the full interactivity that computer applications can offer. Consequently, it is necessary to develop modern tools with specific capacities to complement teaching and research experiences in power electronics. This article describes the Power Electronics Interactive Laboratory implemented in LabVIEW as a tool to introduce interactivity in power electronics education and presents results of its application in research and teaching activities.

ANALYSIS OF CURRENT HARMONICS IN A DECOUPLED SVPWM CONTROLLED DUAL TWO LEVEL INVERTER FED OPEN END WINDING INDUCTION MOTOR DRIVE

Pulse width modulation has been one of the most intensively investigated areas of power electronics for many years now, and the number of combinations seems to be endless. However, according to a hierarchal consensus, Space Vector Modulation techniques are ranked higher in order of merit, based on harmonic performance. In this paper, Space Vector PWM Switching scheme is employed for a dual two level inverter feeding an Induction motor from both ends (open end winding). The decoupled SVPWM is employed for the dual-inverter scheme in order to realize the reference voltage vector. The Gating pulses are correspondingly generated for the dual inverters in order to realize the reference voltage, and the respective voltages are fed to 1kW open end windings of an induction motor drive. The harmonic content of the three phase currents in the motor are analyzed with an appropriate variation in its modulation index. Thus the performance in terms of harmonic analysis is carried out using Matlab/SIMULINK for an open end winding induction motor drive.

Advantages and Challenges of a Type-3 PLL

A phase-locked loop (PLL) is a closed-loop feedback control system, which synchronizes its output signal in frequency as well as in phase with an input signal. The phase detector, the loop filter, and the voltage controlled oscillator are the key parts of almost all PLLs. Within the areas of power electronics and power systems, which are focused on in this paper, the PLLs typically employ a proportional-integral controller as the loop filter, resulting in a type-2 control system (a control system of type-N has N poles at the origin in its open-loop transfer function). Recently, some attempts have been made to design type-3 PLLs, either by employing a specific second-order controller as the loop filter, or by implementing two parallel tracking paths for the PLL. For this type of PLLs, however, the advantages and limitations are not clear at all, as the results reported in different literature are contradictory, and there is no detailed knowledge about their stability and dynamic characteristics. In this paper, different approaches to realize a type-3 PLL are examined first. Then, a detailed study of dynamics and analysis of stability, followed by comprehensive parameters design guidelines for a typical type-3 PLL are presented. Finally, to get insight into the advantages/limitations of this type of PLLs, the performance of a well-tuned type-3 PLL is compared with a conventional synchronous reference frame PLL (which is a type-2 PLL) through extensive experimental results and some theoretical discussions.

Analysis of Motor Driving Circuit in EV/HEV with Battery Circuit Model Employed

In the EV/HEV motor driving system, one of the most important elements that should be taken into account would be a battery that drives the whole system, because the rest of the circuit elements except battery have been relatively well established in the power electronics area. Because of the high frequency power harmonic noises inherent in the circuit, exact voltage fluctuation analysis of the driving circuit at the design stage has been emphasized quite a lot so far. This paper describes the analysis of motor driving circuit with novel battery model employed: as a result, the fluctuated battery voltage for a given DOD (Depth of Discharge) could be calculated. A filter design procedure that takes into consideration of the battery characteristics is also described for a fixed DOD. The effectiveness of the designed filter was confirmed by simulation, which was performed by using MATLAB, Ansys' Simplorer, and Agilent Technology's ADS (Advanced Design System). EV (Electric Vehicle) or HEV (Hybrid-Electric Vehicle) basically employs power electronic circuit to charge battery as well as to drive a motor, and the high voltage in the circuit, typically in the range of hundreds volts, needs to be chopped to control the driving circuits, and as a result it is inevitable to produce high frequency harmonic voltage/ current components inside. Therefore one of the most important things the HEV motor circuit designer needs to consider is the prediction of the electromagnetic compatibility of the driving circuit at the design stage. This is crucial to avoid unnecessary trial and errors after fabrication of the whole driving circuit only to find that the circuit needs to be revised to satisfy EMC standards such as IEC/CISPR and ISO. Therefore, precise analysis of the motor driving circuit is mandatory in the EV/HEV development process at the design stage. The main elements of power electronic circuit in the HEV are such as a high voltage battery, IGBT (Insulated Gate Bipolar Transistor) inverter to control motor through PWM (Pulse Width Modulation) algorithm, BLDC (Brushless DC) motor, and so on. Since the other elements except the battery have been common in the classical driving circuit simulation, an emphasis is put on the battery circuit modeling, which enables to simulate the driving circuit at various DOD levels. For this purpose, battery circuit model includes not only a simple DC model in time domain, but also complex R-C elements in frequency domain, coming from charge transfer resistance and double layer capacitors in the battery. Since the R and C in the battery model depend on the DOD level of the battery, one needs to take into consideration the frequency-dependent battery impedance as well as the load condition to design the filters in the motor driving circuit. (1)(2) This paper is organized as follows. In the next chapter, battery model which is used in the analysis of motor driving system is introduced. In chapter 3 all the circuit elements, such as battery, inverter, and filters, are integrated to form the whole circuit, and brief filter design procedure is described. Chapter 4 demonstrates the simulated results of the voltage fluctuations and the conducted noise, and the effectiveness of the filter is also shown. Finally, this paper ends with a conclusion and further works in the last section.

Design of Fractional Order PID controller using Soft computing methods for a Buck-Boost converter

Fractional order controller is widely used in most areas of science and engineering, being recognized its ability to yield a superior control in many dynamical systems. This work proposes the applications of a Fractional Order PID (FOPID) controller in the area of Power Electronics for a DC-DC power converter to evaluate the use of Fractional Order PID controller with soft computing techniques. To design Fractional Order PID controller is to determine the two important parameters λ (integrator order) and μ (derivative order). In this article that the response and performance of Fractional Order PID controller is compared with closed loop conventional PID controller. In all the cases the Fractional Order PID controller much better than conventional PID controller for the given system.

Hybrid predictive control of a DC–DC boost converter in both continuous and discontinuous current modes of operation

AbstractDeveloping efficient and appropriate modeling and control techniques for DC–DC converters is of major importance in power electronics area and has attracted much attention from automatic control theory. Since DC–DC converters have a complex hybrid nature, recently several techniques based on hybrid modeling and control have been introduced. These techniques have shown better results as compared with conventional averaging‐based schemes with limited modeling and control abilities. But the current works in this field have not considered all possible dynamics of the converters in both continuous and discontinuous current modes (CCM, DCM) of operations. These dynamics are results of controlled and uncontrolled switching phenomena in DC–DC converters. This paper proposes a new switching scheme for modeling and controlling a DC–DC boost converter. The converter is represented as a hybrid automaton by considering the all three possible modes. The hybrid automaton is translated into the mixed logical dynamical (MLD) mathematical framework. The switching among these modes is generated by hybrid predictive control method which is calculated by Mixed Integer Quadratic Programming (MIQP). Using the exact model of the converter, the proposed switching algorithm can globally control the converter in all operation regimes, including CCM and DCM operations, considering all constraints in the physical plant, such as maximum inductor current and capacitor voltage limits. The switching algorithm is applied to a real converter circuit, modeled with various parasitic components. Simulation results are provided to show the advantages of the proposed control scheme. Copyright © 2010 John Wiley & Sons, Ltd.

Numerical Algebraic Geometry for Optimal Control Applications

A new technique for solving polynomial nonlinear constrained optimal control problems is presented. The problem is reformulated into a parametric optimization problem, which in turn is solved in a two-step procedure. First, in a precomputation step, the equation part of the corresponding first order optimality conditions is solved for a generic value of the parameter. Relying on the underlying algebraic geometry, this first solution makes it possible to solve efficiently and in real time the corresponding optimal control problem at the measured parameter value for each subsequent time step. This approach has a probability one guarantee of finding the global optimal solution at each step. Controller synthesis for two applications from the area of power electronics featuring a dc-ac converter and a dc-dc converter are discussed to motivate the proposed approach.

Performance Investigation of Neural-Network-Based Unified Power-Quality Conditioner

The application of artificial intelligence is growing fast in the area of power electronics and drives. The artificial neural network (ANN) is considered as a new tool to design control circuitry for power-quality (PQ) devices. In this paper, the ANN-based controller is designed for the current control of the shunt active power filter and trained offline using data from the conventional proportional-integral controller. A digital-signal-processor-based microcontroller is used for the real-time simulation and implementation of the control algorithm. An exhaustive simulation study is carried out to investigate the performance of the ANN controller and compare its performance with the conventional PI controller results. The system performance is also verified experimentally on a prototype model developed in the laboratory.

A Modular, Open-Architecture D.C.-D.C. Power Conversion Laboratory

Today's graduates are expected to have a mix of skills and be competent as technology specialists and system designers. Many undergraduate courses are reflecting these requirements by introducing an element of systems design into their programmes and individual modules. This paper presents a power conversion laboratory based around a d.c.-d.c. power supply conversion unit that helps students understand both the system elements behind the unit's design, as well as the technology areas of power electronics required within the design. The laboratory is modular, allowing considerable flexibility in the type of experiment run and its main learning outcomes, for example whether the focus is on the power switches, the electronics, the magnetics or the control.

Validating the power loss model of a transformer by measurement - Validation is key

Attempts to verify power losses deduced from simulation by direct measurement are highly respectable. It is the only means to become confident in models that limit simulation accuracy. Unfortunately, in the power electronics area, power measurements are often very difficult. Despite the fact that it is difficult to built, costly, and time consuming, calorimetric apparatus remains the only way to accurately measure the losses of low-loss components such as some capacitors. This paper presents the validation of the power loss model of high-frequency copper losses in transformers using calorimetric measurements.

Temperature and dynamics problems of ultracapacitors in stationary and mobile applications

Ultracapacitors as a powerful energy storage systems are used in various areas of power electronics. Depending on the application, temperature and dynamics properties of these components have to be considered. These properties strongly depend on the characteristics of basic materials of the capacitors. The frequency and temperature dependence of the capacitance as well as of the internal resistance, ESR, is manly affected by the electrodes of activated carbon and the electrolyte. Under operating conditions differences of 15% and more of the capacitance due to a different structure of the electrodes are observed. Due to the reduced solubility of the conducting salt and the increased viscosity of the solvents for temperatures below freezing point the conductivity of the electrolyte drops drastically with decreasing temperatures. Thus, increases of the ESR between 200 and 700% between room temperature and −30 °C depending on the electrolyte are registered. Due to the slightly different selfdischarge of the single capacitors equivalent to a voltage drop of 4–12% within 3 days, the individual cell inside a module has to be protected by a cell voltage balancing unit. By an active cell voltage balancing unit connected in parallel to the capacitors a voltage drop will be leveled out after 1 h. In addition to the electrical characteristics of the ultracaps also the thermal properties of the single cell as well as of the modules have to be considered for the design in of these storage devices. By cooling elements integrated in the surface of the module casing and forced cooling the effective current load can be nearly doubled. Based on this know how ultracap modules were designed, which fulfill all the requirements of the applications in automotive and industrial electronics.

Hypermedia Design Methodology in World Wide Web Applications

One approach to instruction based on a "learner-centered" view of learning is to provide rich environments in which learners can actually build their own knowledge. Therefore only educational software, carefully designed, can improve the efficiency of courseware. Within this framework, the World Wide Web provides a unique support for course material. Using a generalized hypermedia instructional design methodology, we integrated a hypermedia instructional module with simulation additional tools into an academic information system. This academic information system is a computer-supported environment in which collaborative discourse is the primary medium for knowledge advancement in the area of power electronics. It can be explored by learners in that they have both contextual access to knowledge displayed in a hypertext format and access to real experiences by means of simulation. In this article, we present an object-orientated approach that integrates the complete graphic user interface development.

Plasma-Induced Effects on The Thermal Conductivity of Hydride Vapor Phase Epitaxy Grownn-GaN/Sapphire (0001)

ABSTRACTWe have measured high spatial/depth resolution (2-3 [.proportional]m) thermal conductivity (κk) at 300K before and after plasma-induced effects on a series ofn-GaN/sapphire (0001) samples fabricated by hydride vapor phase epitaxy (HVPE) using a ThermoMicroscope'as scanning thermal microscope (SThM). The sample thicknesses were 50 ± 5 [.proportional]m and the carrier concentrations ~ 8 × 1016cm-3, as determined by Hall effect measurements. The thermal conductivity before treatment was found to be in the 1.70 – 1.75 W/cm-K range, similar to that previously reported for HVPE material with this carrier concentration and thickness [D. I. Florescuet al., J. Appl. Phys. 88, 3295 (2000)]. The samples were processed under constant Ar gas flow and pressure fora fixed period of time (5 min). The only variable processing parameter was the DC bias voltage (125 – 500 V). After the initial 125 V procedure κ exhibited a decrease linear in the DC voltage in the investigated range. At 125 V the thermal conductivity was only slightly less (κ ~ 1.65 W/cm-K) than the untreated case. κ had dropped to ~ 0.3 W/cm-K for the 500 V situation. The implications of these results for device applications in the area of high power opto-electronics and high power electronics will be discussed.

An industry-university collaboration in power electronics and drives

In 1997 Danfoss Drives A/S and the Institute of Energy Technology at Aalborg University in Denmark started an initial four-year collaboration called Danfoss Professor Program. The main goal of the program is to attract more students to the multidisciplinary area of power electronics and drives by offering a world-class curriculum taught by world-class teachers. During the four years of the program distinguished professors will visit the university, giving advanced courses in their specialty areas and interacting with postgraduate students. A new curriculum in power electronics and drives is also now being implemented at the university, based on courses developed together with professors from the program. Another goal is to strengthen the research team at the university in the area by fostering new contacts and research areas. Finally, training and education of engineers in industry is a major aim of the program. After 2 1/2 yr, the Danfoss Professor Program has resulted in a significant increase in the number of students and research output of Aalborg University in the power electronics and drives area. It is beginning to be recognized world wide as a model of successful Industry/University collaboration. This paper describes the major goals, implementation and an evaluation of the program.

The significance of zero space vector placement for carrier-based PWM schemes

Pulsewidth modulation has been one of the most intensively investigated areas of power electronics for many years, and the number and combination of permutations seem to be endless. However, a general hierarchical consensus appears to have emerged from this work which ranks space vector modulation techniques, regular sampled modulation, and sine-triangle modulation strategies in decreasing order of merit based on harmonic performance. However, what has not been clearly identified is why space vector modulation should lead to a reduced harmonic current ripple compared to regular sampled modulation, especially since it is straightforward to show that they produce identical low-frequency fundamental components. This paper addresses this issue by showing how it is the placement of the zero space vector component within the carrier interval that determines the harmonic performance of the modulation strategy, rather than any intrinsic differences between the various methods of calculating the switching instances.

Silicon wafer bonding via designed monolayers**

Silicon wafer bonding is a technology which allows two silicon wafers to stick together without any glue (e.g. see Fig.). The technique is used in the areas of microelectronics, micromechanics, and power electronics. Hydrolyzed tetramethoxysilane is used in he new bonding process presented here, providing a low‐temperature method of wafer bonding compatible with the presence of microelectronics aluminum metallization magnified image.

Expert system, fuzzy logic, and neural network applications in power electronics and motion control

Artificial intelligence (AI) tools, such as expert systems, fuzzy logic, and neural networks are expected to usher a new era in power electronics and motion control in the coming decades. Although these technologies have advanced significantly and have found wide applications, they have hardly touched the power electronics and machine drives area. The paper describes these AI tools and their application in the area of power electronics and motion control. The body of the paper is subdivided into three sections which describe, respectively, the principles and applications of expert systems, fuzzy logic, and neural networks. The theoretical portion of each topic is of direct relevance to the application of power electronics. The example applications in the paper are taken from the published literature. >

Trends in Power Electronics

Power electronics seemed for a long period an obsolete area with very few innovations. This period of stagnation is replaced now due to rapid developments in semiconductor technology. This development boosts development in all areas of power electronics, too: the power semiconductors, the topologies of the converters and inverters, the control strategies and furthermore modern computer-aided-design and optimization-tools. This paper will discuss the different aspects.