Converters

Energi listrik merupakan energi utama yang dibutuhkan untuk peralatan elektronik, energi listrik dapat dihasilkan dari berbagai sumber, seperti air, panas matahari, nuklir, batu bara, angin, panas bumi dan lainnya. Energi yang dihasilkan terdiri dari beberapa Joule hingga jutaan Joule. Saat ini di Indonesia belum banyak yang menggunakan sumber energi alternatif untuk peralatan elektronik yang digunakan dan lebih sedikit lagi yang menggunakan lebih dari satu energi alternatif sebagai sumber energi listrik, hal ini menjadikan sangat bergantungnya masyarakat Indonesia terhadap PLN sebagai perushaan penyedia energi listrik. Pada Proyek Akhir ini telah di rancang sebuah alat pengontrol yang digunakan untuk pembangkit listrik dengan menggunakan sumber daya alternatif yang terbarukan untuk dua sumber daya yang dapat menghasilkan listrik yaitu, air dan juga panas matahari. Pada perancangannya alat pengontrol yang menggunakan sebuah Arduino, IRF9540 dan juga MBR2045 ini dapat memonitor daya yang masuk dari kedua sumber tersebut dan juga mengecek daya baterai yang digunakan sehingga dapat diperoleh tegangan pada sistem. Dari Proyek Akhir ini didapatkan jumlah energi listrik yang sesuai dengan kebutuhan untuk membantu memberi tenaga kawasan pembakaran sampah sebesar 41.66 Watt pada kondisi maksimum sehingga kawasan tersebut dapat terbantu dengan daya selain dari PLN sehingga dapat mengurangi biaya yang dikeluarkan pengelola kawasan pembakaran sampah tersebut.

The task of the whole microgrid state-space matrix creation is usually done in a preferred textual programming language, and it presents a complicated, time-consuming, and error-prone job for a researcher without good coding practices. To ease the modeling task, contribute to the adaptation of new microgrid structures, control algorithms, and devices, and to improve the flexibility of the model, a graphical element building block method is proposed in this paper. With the proposed approach model creation of the whole microgrid is reduced to the creation of the individual element state-space model that is linked with other elements in a logical way with a graphical connection. Elements are then grouped into meaningful wholes and encapsulated with the appropriate graphical user interface that enables easy parameter modification and model complexity change. More detailed DC/DC and DC/AC models of converters than those in the literature concerning microgrid stability are presented in th...

In this paper, three solutions for the control of voltage in Low Voltage (LV) grids with high photovoltaic (PV) penetration are simulated and compared. The first solution corresponds to the use of distributed PV converters to control voltage in their connection points. In other cases, a centralized control is performed, by using a Static Var Compensator or a transformer with On Load Tap Changer installed inside the MV/LV substation. Benefits on voltage profiles and reduction of losses are shown through simulations carried out on a real grid. The consumption and PV generation profiles come from accurate measurements performed in apartment and office buildings with 1-second time step.

This paper studies the application of distributed and centralized solutions for voltage control in Low Voltage (LV) grids with high photovoltaic (PV) penetration. In traditional LV grids, the coordination of distributed PV converters and a centralized device would require massive investments in new communication and control infrastructures. The alternative of exploiting distributed PV converters for voltage control is discussed, showing that it can help to stabilize the voltage in the grid connection points also without coordination between them and/or with a centralized unit. The goal of this paper is to investigate how the setup of the voltage controllers inside PV inverters affects the operation of these controllers taking into account the limits for reactive power injection. In addition, the interaction of distributed PV converters with centralized devices (static var compensators and on load tap changers) is analyzed to assess whether additional benefits may come in these cases.

This article reveals, analyzes and proposes the method to mitigate nonlinear effects of multi-sampled multiupdate (MSMU) digital phase-shifted pulsewidth modulators (PS-DPWM) that appear in unbalanced multi-cell voltage-source converters (MC-VSCs). For balanced MC-VSCs, the harmonic cancellation of PS-DPWM allows for an increase in the sampling frequency, ensuring that the average current is acquired at the peaks, valleys, and intersections of all triangular carriers. For unbalanced operation, which is typically encountered in practice, e.g., due to cell voltage mismatch in multilevel MC-VSCs and inductance mismatch in interleaved MC-VSCs, harmonic cancellation of PS-DPWM is compromised and, thus, the increased sampling frequency brings switching ripple in the feedback signal. Since in MSMU control the modulating signal is also updated at peaks, valleys, and intersections of all carriers, this may cause vertical intersections between the modulating signal and the carriers, resulting in specific nonlinear effects. The nonlinearities are shown to introduce limit-cycle oscillations and output waveform distortion. A method to prevent such detrimental impact of MSMU-PS-PWM is also proposed. A simple analytical procedure is proposed to quantify the analyzed non-linear effects, revealing that they are more emphasized for higher levels of imbalance and control bandwidth. Moreover, the modulator nonlinearity is shown to decrease as the number of cells increases. The analyses are verified in simulations and experiments, using laboratory prototypes of three-and four-level MC-VSCs.

A power distribution scheme based on the use of on-board DC-DC converters is proposed to efficiently distribute power to the on-detector electronics of SLHC trackers. A comparative analysis of different promising converter topologies is presented, leading to the choice of a magneticbased buck converter as a first conversion stage followed by an on-chip switched capacitors converter. An overall efficiency above 80% is estimated for the practical implementation proposed. I. SLHC POWER DISTRIBUTION NEEDS In the design of upgraded trackers for SLHC, the required increase in the number of readout channels should not lead to a heavier tracker. Since cables and cooling are amongst the main contributors to the material budget, and they are both dependent on the amount of power burnt in the tracker, ondetector power management is necessary. It is important to both decreasing the power per function ratio of Front-End (FE) electronics, and to distributing the power efficiently. The first objec...

The limitation imposed on the achievable power level by the IEC 1000-3-2 standard in buck-derived power factor preregulators, is overcome by using a combined buck-flyback power stage. Two different step-down converters are proposed in this paper, which incorporate an auxiliary flyback stage. The auxiliary stage uses the same switch of the main converter, plus an additional power switch commutated at the line frequency. As compared to a simple buck rectifier, with this solution the harmonic content of the absorbed line current, at a given power level, can be reduced, thanks to the resulting increased conduction angle of the input rectifier bridge. Experimental results based on a 1 kW prototype are reported to validate the theoretical analysis of the proposed topologies.

The paper describes the design of optimized printed circuit board (PCB) air-core toroids for high-frequency dc-dc converters with strict requirements in terms of volume and noise. The effect of several design parameters on the overall inductor volume, on dc and ac winding resistance, and on the radiated noise will be investigated. PCB toroids are compared to standard air-core solenoids and other state-of-the-art air-core toroids both theoretically and experimentally: at first, using ANSOFT Maxwell and ANSOFT Q3D simulation tools, and subsequently, with laboratory measurements (irradiated noise, efficiency, and frequency response) on several prototypes. These very flexible and rather easy to manufacture inductors appear very attractive for compact highfrequency dc-dc converters where high efficiency, low volume, and low noise are of primary concern.

Today, solar energy systems based on photovoltaic (PV) panels associated with power converters are increasingly used to supply isolated sites. This structure has attracted several studies as a cost-effective, freely available, efficient source of clean and low-cost energy. However, the faults in power converters can affect the stability of the control system by supplying the isolated site with unwanted current and voltage. Therefore, this paper presents a comparative study using a fault-detection-based k-nearest neighbor (KNN) approach, between sliding mode control and exact linearization control applied to an isolated PV-system-based multicellular power converter, in order to assess the robustness and the performance of the two control strategies against the flying capacitor faults. The results obtained for both control methods in different fault cases are analyzed in terms of time series and feature spaces. These results, obtained with MATLAB software, prove the superiority of sli...

Currently, providing water in developing countries, especially in dry and hot rural areas, is a significant challenge. However, creating new electric grids is often expensive. Therefore, the use of low-cost photovoltaic (PV) panels in water pumping systems, without chemical energy storage, based on high-performance and more efficient power converters with increased time life and lower maintenance interventions is needed. In this study, a photovoltaic water pumping system with two power converters, the first is used to extract the maximum power using the maximum power point tracking (MPPT) algorithm, and the second is a three-cell multicellular power converter used to control the DC motor with a submerged pump. Meanwhile, the serial connection and redundant topology of multicellular converters render the system more vulnerable to failure. fault diagnosis-based machine learning approach and fault tolerant control (FTC) are proposed for multicellular power converters. Simulation results with MATLAB show the effectiveness and practicability of the proposed structure and control to isolate the faulty capacitor, increase the sustainability of the system, assure the supply of water under faulty conditions, minimize the mechanical vibrations in electric DC motors, and avoid PV system shutdown. INDEX TERMS Photovoltaic water pumping system, multicellular converter, fault diagnosis based machine learning, fault tolerant control (FTC).

PurposeFocuses on steady state modelling of basic unipolar non‐isolated PWM AC line matrix‐reactance choppers (MRC). Their single‐phase topologies are similar to well‐known basic DC/DC converter ones. The MRC are built up through the adaptation of DC/DC converter topologies, which are based on the substitution of self‐commutated unidirectional switches by bi‐directional ones.Design/methodology/approachPresents an approach to modelling of the MRC with averaging operator different to the one used in averaged modelling of the DC/DC converters. There is running averaging of each switching period in the proposed approach. Following this, there is a demonstration of the solutions convergence of the state space and averaged state space equations for infinitive switching frequency.FindingsThe running averaging of each switching period should be used if averaged state space method is applied to the analysis of presented choppers. A circuit averaged model build‐up procedure of the presented c...

Performance of the systems equipped with PWM inverters can be improved through increasing frequency of switching. However, frequency improvement made some troubles in the system such as electromagnetic interactions or interferences (EMI) and increased power loss. Generally in the inverters working based on PWM method, the losses of switching are so high, where the load is induction. But, in the presented method, it is possible to minimize the switching losses. In this investigation, by adding Snubber circuit in the driver circuit, switching losses significantly reduced. The results obtained from simulation showed that soft switching inverter is more efficient than hard switching inverter in terms of reduction of switching losses.

The matrix converter is devised to achieve sinusoidal input current and output voltage, and high power density. The typical matrix converter gives voltage gain less than unity using a significantly large number of switches. To reduce the number of switches an ultra sparse matrix converter (USMC) is introduced whose voltage gain is still less than unity. Researchers also introduced many modified versions of these matrix converters including quasi-Z-source, series Zsource, switched inductor, and switched capacitor USMCs. Although all of these matrix converters have their relative advantages and disadvantages in terms of the number of switches and passive elements, the voltage gain is still marginal. This paper focused on achieving higher voltage gain using minimal switches and passive elements. We proposed a doubler boost impedance network based ultra sparse matrix converter (DB-USMC). The doubler boost impedance network consists of a boost stage and doubler stage where the boost stage enhances the voltage and the doubler stage makes it double. The voltage gain of the proposed DB-USMC converter is 4.00 at a 50% duty cycle. The obtained results of the proposed DB-USMC converter show a path to get superior voltage gain using minimal switches and passive elements in a cost-effective manner.

Two charge-scaling successive approximation AID converters for on-focal-plane column-parallel data processing in CMOS active pixel image sensors (APS) are presented. The converters are designed in a thin but long fashion to fit a pitch size of 40 .tm for 2.0 jim technology and 24 pm for 1.2 im technology. Designed for multimedia and other commercial and industrial applications, each in column A/D converter achieves 8 bit resolution and accuracy with a signal swing of 1 V. Maximum conversion rate exceeding 200 kHz enables high speed digital readout beyond 200 frames/sec for large format 1K x 1K CMOS image sensors. A prototype device of 64 X 64 APS image array with 8 bit digital output was demonstrated up to 1 kHz frame rate, and with column-wise non-uniformity less than 2 LSBs.

O conversor AOD é o principal equipamento utilizado na produção de aços inoxidáveis. O processo de produção do aço inoxidável no AOD ocorre através da injeção de uma mistura de oxigênio e gás inerte no banho metálico, com o objetivo de fazer a oxidação seletiva do carbono. Com o objetivo de aumentar a produtividade e reduzir o custo de fabricação, o "Sistema Carbometria" foi implantado no conversor AOD-L da ArcelorMittal Inox Brasil. Este sistema é composto de equipamentos, que fazem a análise dos gases gerados durante a elaboração do aço, e de um modelo matemático que executa cálculos de previsão do carbono. Após sua implantação, foi possível reduzir o tempo de processo e o consumo de insumos. Palavras-chave: Conversor AOD; Aços inoxidáveis.

In this paper, we propose a new technique to regulate multi-phase interleaved switched-capacitor DC-DC converters. Traditionally, SC converters are either regulated by modulating the switching frequencies directly through a voltagecontrolled-oscillator or by using hysteretic control where separate control loops are used for each converter core. Achieving fast regulation by modulating VCO is difficult because it requires a high speed error amplifier and proper loop compensation. Conventional hysteretic controller achieves fast regulation, but it uses N comparators or one shared comparator that operates at N times the single phase switching frequency, where N is the level of interleaving. The proposed technique avoids these problems by using triple boundary hysteretic control, where one comparator is used for defining the reference voltage, and the other two comparators enable coarse/fine operation to achieve both fast recovery and tight regulation.

VCO is commonly used in time mode ADC to convert analog input voltage to time/phase information, where the time/phase information is subsequently converted to digital code using time-to-digital converter. Although high speed high resolution time-to-digital converters are currently available, the inherent nonlinear property of VCO however has become the bottle neck for time mode ADC. In this paper, a new concept named K-locked-loop is proposed to solve the nonlinearity issue of VCO within a time mode ADC. A 9-bit, 0.5MS/s time mode ADC has been modeled using SIMULINK tool in Matlab. Some of the circuits are simulated using Spectre simulator tool in Cadence using the 0.18µm CSM process, and the simulation result is back annotated to SIMULINK model to make the behavioral modeling more comprehensive and accurate.

Microgrid concept acts as a solution to integrate large amounts of micro generation without disrupting the operation of utility grid. Power generation from renewable energy sources like wind, solar, fuel cells, microturbines etc will give significant momentum in near future. Thus, hybrid AC/DC microgrid will be the best solution to reduce multiple reverse conversions (dc-ac-dc or ac-dc-ac) in an individual ac or dc grid. The proposed hybrid grid consists of both AC and DC networks connected to distribution generation through the multi-bidirectional converters. AC sources and loads are connected to AC network whereas DC sources and loads are tied to the DC network. Energy storage systems can be connected to dc or ac links. This microgrid can operate in a grid-tied or isolated mode. The coordination control schemes are proposed for smooth power transfer between AC and DC links during various supply and demand conditions. This paper presents a simulation of small hybrid microgrid and i...

Line synchronised phase-controlled thyristor power converters produce notches in synchronising signals at the instant of turning on thyristors. These synchronising signals are derived from three-phase supply to generate gate pulses for a converter. The presence of notches leads to malfunctioning of the connected power converters whose operations decisively rely on the proper zero-crossing information of the synchronising signal. Denoising these notches is difficult because of the nonstationary pattern of the synchronising signal. The small drift of supply frequency is the main cause for this non-stationary pattern. A filtering technique based on wavelet transform (WT) is proposed in this work. The application of filtering banks using multi-resolution analysis (MRA) of discrete wavelet transform (DWT) with 'Daubechies1' as mother wavelet is found effective in denoising synchronising signals from such noises. The simulation study and the experimental results are presented to justify the proposed filter structure.

This chapter is focused on Power Take-Off (PTO) systems for wave energy converters (WEC), being one of the most important elements since PTOs are responsible to transform the mechanical power captured from the waves into electricity. It presents Direct-Drive PTO (DDPTO) as one of the most reliable solutions to be adapted to some particular types of WEC, such as point absorbers. A discussion about modularity and adaptability, together with intrinsic characteristics of direct-drive PTOs, is also included. Among the different technologies of electric machines that can be used in direct-drive linear PTOs, switched reluctance machines (SRM) are described in further detail. In particular, the Azimuthal Multi-translator SRM is presented as a suitable solution in order to increase power density and reduce costs. Not only the electric machine, but also the associated power electronics are described in detail. The description includes the different configurations and topologies of power conve...

Supercapacitors, one of the most promising energy storage technologies for high power density industrial applications, exchange the energy mostly through power electronic converters, operating under high frequency components due to the commutation. The high frequency produces important effects on the performance of the supercapacitors in relation to their capacitance, inductance and internal resistance (ESR). These parameters are fundamental to evaluate the efficiency of this energy storage system. The aim of the paper is to obtain an accurate model of two supercapacitors connected in series (functional and extrapolated unit) to represent the frequency effects for a wide range of frequencies. The methodology is based on the definition of an appropriate equivalent electric circuit with voltage dependance, obtaining their parameters from experimental tests, carried out by means of electrochemical impedance spectroscopy (EIS) and the use of specific software tools such as EC-Lab® and S...

Multiphase Variable Speed Drives have found widespread applications in recent times, especially in the area of ship propulsion systems. Such drives almost invariably require converters with a suitable number of output phases. Pulse Width Modulation techniques have been the preference in recent times for the control of power electronics converters. Space Vector Pulse Width Modulation technique applied on multi-phase converters allows us an efficient implementation of such converters. This paper concentrates on the implementation of the Space Vector Modulation (SVM) in an 11-phase voltage source inverter (VSI) system. There are a total of 2 11 = 2048 space vectors for such an inverter. But out of these only 22 large vectors and 2 zero vectors are necessary for SVM implementation. The symmetrical sequence type of implementation is chosen for the SVM and its implementation method is discussed.

This is to certify that the Project entitled "MATLAB BASED MODELING OF PHOTOVOLTAIC ARRAY CHARACTERISTICS" submitted by Bibek Mishra(108EE010) and Bibhu Prasanna Kar(108EE027) in partial fulfillment of the requirements for the award of Bachelor of Technology Degree in Electrical Engineering at National Institute of Technology, Rourkela (Deemed University), is an authentic work carried out by them under my supervision and guidance. To the best of my knowledge, the matter embodied in the thesis has not been submitted to any other University/Institute for the award of any Degree or Diploma.

Multiphase ZVS BUCK DC-DC Converter with Voltage Mode Peak Current Control is proposed in the present paper. In this way, the advantages of Multiphase Converters and Zero Voltage Switching (ZVS) Converters are combined. The proposed Control System provides constant phase shifting between individual DC-DC converters when the peak value of the current varies, as a result of which the switching frequency also changes. The transient process at the start of the converter is simulated, as well as the response of the voltage regulator to a sudden change in load. Using parametric analysis, the optimal parameter values of the compensating circuit elements of the voltage regulator are determined.

A macromodel of monolithic Voltage-to-Frequency Converter (VFC) for the simulator PSpice A/D is proposed. For creating the model, simplification and build-up techniques known from modelling operational amplifiers have been adapted. This generalized model is independent from actual technical realizations and is based upon compromises regarding the representation of exact circuit structure in the model. The proposed VFC model accurately predict the circuit behaviour for nonlinear dc, ac and large-signal transient responses. The macromodel topologies comprise of four stages: analogue integrator (input stage), compa-rator, one-shot timer and output delay stage. The equivalent circuit principally contains linear controlled sources, passive elements and voltage controlled switches. The SPICE diode and transistor models are used as non-linear elements for voltage limitation and approxi-mation of characteristics. The macromodel is implemented as a hierarchical blocks and the structure of th...

Los motores que requieren los vehículos eléctricos deben poseer un comportamiento eficaz, eficiente y económico. El acelerado desarrollo de la electrónica de potencia y del control de velocidad con convertidores de frecuencia permite emplear sistemas de velocidad ajustable dentro de un amplio intervalo. En este trabajo, a partir de estudios realizados en la literatura especializada, fueron comparados distintos tipos de motores sincrónicos sin devanados en el rotor para estos vehículos. Las comparaciones se realizaron en base a momento y potencia, pérdidas y eficiencia, factor de potencia, costos y otros aspectos de los motores sincrónicos de imán permanente, sincrónicos de reluctancia y sincrónicos de reluctancia asistidos por imanes permanentes. Esto permitió valorar la mejor variante técnico económica. Se evidenció que el último tipo, utilizando imanes de ferrita, asegura menor costo, con altos valores absolutos y de densidad de momento y de potencia, elevada eficiencia y alto fac...

The effective operation of the grid side converter is crucial for the reliability of renewable energy systems. Grid side converters are responsible for converting the energy produced by renewable energy sources into a form that can be injected into the grid. A grid side converter controller manages the conversion using feedback from voltage and current sensor measurements from both the alternative current (ac) and direct current (dc) sides of the converter. However, these sensory devices may fail or diverge from their normal operation, which can affect the effective operation of the converter. This article proposes a model-based fault diagnosis scheme for sensors located in the dc and ac sides of the grid-tied converter, taking into account the effects of fault propagation due to the physical interconnection between the ac and the dc sides. First, a discrete-time, nonlinear model of the grid side converter is formulated that considers the presence of ac current and dc voltage sensor faults. Second, a nonlinear estimation scheme is designed by considering the effects of sensor noise and modeling uncertainty. The estimator design utilizes the estimator gain matrix that is obtained by solving the linear matrix inequalities problem. Finally, a sensor fault diagnosis scheme is designed based on the analytical redundancy relations considering the estimations of the nonlinear estimation scheme. The performance of the proposed fault diagnosis scheme is validated through both simulation and experimental results, demonstrating its effectiveness in timely detecting and isolating sensor faults.

The effective operation of the grid side converter is crucial for the reliability of renewable energy systems. Grid side converters are responsible for converting the energy produced by renewable energy sources into a form that can be injected into the grid. A grid side converter controller manages the conversion using feedback from voltage and current sensor measurements from both the alternative current (ac) and direct current (dc) sides of the converter. However, these sensory devices may fail or diverge from their normal operation, which can affect the effective operation of the converter. This article proposes a model-based fault diagnosis scheme for sensors located in the dc and ac sides of the grid-tied converter, taking into account the effects of fault propagation due to the physical interconnection between the ac and the dc sides. First, a discrete-time, nonlinear model of the grid side converter is formulated that considers the presence of ac current and dc voltage sensor faults. Second, a nonlinear estimation scheme is designed by considering the effects of sensor noise and modeling uncertainty. The estimator design utilizes the estimator gain matrix that is obtained by solving the linear matrix inequalities problem. Finally, a sensor fault diagnosis scheme is designed based on the analytical redundancy relations considering the estimations of the nonlinear estimation scheme. The performance of the proposed fault diagnosis scheme is validated through both simulation and experimental results, demonstrating its effectiveness in timely detecting and isolating sensor faults.

Structural design aspects and material selection choices for Wave Energy Converters (WECs) have a large impact on capital expenditure and life-cycle operating costs. The aim of this thesis is to consider the governing design issues and material selection choices in the early design stages in order to improve lifecycle cost. The work was carried out in close collaboration with Albatern and the thesis will draw on the WaveNET array as a case study. The WaveNET array is a novel multi-body floating array system, harnessing power through the relative motion of buoyant Node elements, and rigid Link elements, which are connected via an articulated Joint Module. The thesis reviews the concept design process and develops methods for assessing the trade-off between maximising power production, and minimising structural loading over the lifetime of the structure to optimise LCoE. Concept assessment methods are developed with the aid of structural load data from physical and numerical models. D...

Recent developments in intelligent control methods and power electronics have produced PV based DC to AC converters related to AC drives. Cascaded boost converter and inverter find their way in interconnecting PV and Induction Motor. This paper deals with digital simulation and implementation of closed loop controlled fivelevel inverter based Photo-Voltaic (PV) system. The objective of this work is to reduce the harmonics using Multi Level Inverter based system. The DC output from the PV panel is boosted using cascaded-boost-converters. The DC output of these cascaded boost converters is applied to the bridges of the cascaded inverter. The AC output voltage is obtained by the series cascading of the output voltage of the two inverters. The investigations are done with Induction motor load. Cascaded boost-converter is proposed in the present work to produce the required DC Voltage at the input of the bridge inverter. A simple FLC is applied to CBFLIIM system. The FLC is proposed to reduce the steady state error. The simulation results are compared with the hardware results. The results of the comparison are made to show the improvement in dynamic response in terms of settling time and steady state error. Design procedure and control strategy are presented in detail.

Recent developments in intelligent control methods and power electronics have produced PV based DC to AC converters related to AC drives. Cascaded boost converter and inverter find their way in interconnecting PV and Induction Motor. This paper deals with digital simulation and implementation of closed loop controlled five-level inverter based Photo-Voltaic (PV) system. The objective of this work is to reduce the harmonics using Multi Level Inverter based system. The DC output from the PV panel is boosted using cascaded-boost-converters. The DC output of these cascaded boost converters is applied to the bridges of the cascaded inverter. The AC output voltage is obtained by the series cascading of the output voltage of the two inverters. The investigations are done with Induction motor load. Cascaded boost-converter is proposed in the present work to produce the required DC Voltage at the input of the bridge inverter. A simple FLC is applied to CBFLIIM system. The FLC is proposed to ...

Current controller performance is key in gridconnected power converters for renewable energy applications. In this context, a challenging scenario is arising in multi-MW wind turbines, where sampling and switching frequencies tend to be lower and lower as power ratings increase. This strongly affects achievable control time constant. With this perspective, this paper presents a systematic procedure for accurate dynamics assessment and tuning of synchronous-frame PI current controllers, which is based on linear control for multiple input multiple output (MIMO) systems. The dominant eigenvalues of the system are calculated with explicit consideration of time-delay and cross-coupling terms, two factors which clearly impair the system dynamics when considering a low sampling frequency. The proposed methodology is summarized as follows. Firstly, the plant and controller matrices are modeled in state-space. Subsequently, the characteristic polynomial of the closed-loop system is obtained and a computer-aided parametric analysis is performed to calculate the MIMO root locus as a function of the control gain. By its inspection, it is possible to identify the gain which minimizes the current closed-loop time constant. This tuning is suitable for wind turbine applications, taking into consideration cascaded-control structures and grid-code requirements. The validity and accuracy of the analysis is fully supported by experimental verification.

This paper presents a study on a new full bridge series resonant converter (SRC) with wide zero voltage switching (ZVS) range, and higher output voltage. The high frequency transformer is connected in series with the LC series resonant tank. The tank inductance is therefore increased; all switches having the ability to turn on at ZVS, with lower switching frequency than the LC tank resonant frequency. Moreover, the step-up high frequency (HF) transformer design steps are introduced in order to increase the output voltage to overcome the gain limitation of the conventional SRC. Compared to the conventional SRC, the proposed converter has higher energy conversion, able to increase the ZVS range by 36%, and provide much higher output power. Finally, the a laboratory prototypes of the both converters with the same resonant tank parameters and input voltage are examined based on 1 and 2.2 kW power resprctively, for veryfing the reliability of the performance and the operation principles of both converters.

Single-ended primary-inductor converter (SEPIC) was considered a good alternative to a DC-DC converter for photovoltaic (PV) systems. The SEPIC converter can operate with an input voltage greater or less than the regulated output voltage, or as a step-up or step-down. As a step-up converter, SEPIC boosts PV voltage to specific levels. However, gain limitation and voltage stress continue to reduce the efficiency of conventional SEPIC converters. Because of this, researchers created a modified SEPIC converter to improve performance. In this paper, six modified SEPIC converters were compared and evaluated. To compare fairly, all modified SEPIC converters are non-isolated and use a single switch. Power simulator (PSIM) software was used to simulate each converter with a BISOL BMO-250 PV module and maximum power point tracking (MPPT) P&O controller. The converter with the highest static voltage gain and lowest duty cycle has been identified. It results in up to ten times voltage incremen...

Makalah ini menghadirkan strategi kendali berbagi-energi parallel untuk aplikasi kendaraan hibrida fuel cell (FCHV). Catudaya hibrida terdiri dari pembangkit fuel cell (FC) dan unit penyimpang energy (ESU) yang mengkombinasikan modul baterai dan kapasitor ultra. Bus arus DC digunakan untuk antar muka antara catudaya dan sistem pendorong kendaraan elektrik (EV). Catudaya dan sistem pendorong ini dikoneksikan ke bus DC konversi elektronika daya. Terdapat enam kalang kendali didesain pada sistem supervisi untuk mengatur tegangan bus DC, mengendalikan aliran arus listrik dan pada waktu yang sama memonitor kondisi pengisian dari masing-masing piranti penyimpan energi. Pengendali proposional integral (PI) diterapkan untuk mengatur keluaran dari tiap-tiap kalang kendali mengacu kepada sinyal referensinya. Sistem kendali energy yang diusulkan disimulasikan pada lingkungan MATLAB/Simulink. Hasil penelitian mengindikasikan bahwa sistem kendali berbagi-energi paralel yang diusulkan mampu menyediakan tanggapan kendaraan hibrida yang praktis terhadap tanggapan traksi kendaraan elektrik dan pada waktu yang sama mampu menghindarkan FC dan baterai dari beban lebih.

Cascaded multilevel converters based on medium-frequency (MF) AC-links have been proposed as alternatives to the traditional low-voltage inverter, which uses a bulky low-frequency transformer step-up voltage to medium voltage (MV) levels. In this paper, a three-phase cascaded DC-AC-AC converter with AC-link for medium-voltage applications is proposed. Three stages integrate each DC-AC-AC converter (cell): a MF square voltage generator; a MF transformer with four windings; and an AC-AC converter. Then, k DC-AC-AC converters are cascaded to generate the multilevel topology. This converter’s topological structure avoids the per-phase imbalance; this simplifies the control and reduces the problem only to solve the per-cell unbalance. Two sets of simulations were performed to verify the converter’s operation (off-grid and grid-connected modes). Finally, the papers present two reduced preliminary laboratory prototypes, one validating the cascaded configuration and the other validating the...

In order to address power imbalance in large-scale PV systems, this paper presents a multiport isolated medium-frequency (MF) link to process different power levels from PV arrays, using current-fed Z-source inverters (CZSI) modules to drive the energy from the PV array to the MF link in a single power stage. The MF link provides the galvanic isolation required by many codes and standards to integrate a system to the grid. The multiport configuration of the MF link allows the system to process different power levels on each primary port and, being all ports magnetically coupled, provide balanced power levels on secondary ports which can be used for multilevel converters applications. Additionally, the current-fed version of the Z-source topology offers natural protection against short-circuit damage enhancing reliability of the system. The analysis of CZSI cells and the study of asymmetrical power levels transference, as well as simulation and experimental results are presented.

The integration of Renewable Energy Sources (RESs) into distribution networks has increased in recent years due to numerous advantages. However, the RESs are intermittent and uncertain therefore may cause various limitations such as high lines loading and large voltage deviations, especially during high generation and low demand periods. Thus, this leads to an upper limit for the integrated capacity of RESs into the network, entitled Hosting Capacity (HC). In this paper, the complementarity of wind-PV along with the Demand Flexibility Program (DFP) are utilized for alleviating the limitations and increasing the HC in a hybrid AC/DC network. Moreover, an important feature of the AC/DC network, i.e., reactive control of Voltage Source Converters (VSCs) is investigated for increasing the HC. Additionally, a tradeoff is made between two conflicting objectives, i.e., HC and energy losses, which will be increased due to an excessive increase of the HC. Generally speaking, the paper propos...

Both Soft computing based controllers and sliding mode controllers have been utilized to regulate the output voltage of dc-dc converters in response to changes in the load and the input voltage. Although both control techniques possess desirable characteristics, they have disadvantages which prevent them from being applied extensively. Many researchers have proposed the combination of sliding mode control and Soft computing based control to combine the advantages of both control techniques. In literature survey, it is found that the combination of the methods are proposed so that sliding mode algorithm is used in the design of Soft computing based controllers and the inputs to the controller are error and change in error and the inherent stability property of sliding mode controller is not utilized. This paper presents a novel soft computing based sliding mode controller in which inputs are switching function and change in switching function which combines the advantages of soft computing based controllers, sliding mode controllers and integral controllers. Since soft computing is used in the design of sliding mode controller, the stability of the proposed controller is assured. In addition, it is well suited for digital control design and implementation. The proposed controller has been designed for a buck converter and the controller is able to obtain the desired transient response without causing chattering and error under steady-state conditions. The proposed controller is able to give robust performance in terms of rejection to input voltage variations and load variations.

This paper presents a global and optimal environment of the electro-mechanical conversion chain using the doubly-fed induction generator (DFIG) in wind turbines having an active power in the stator of the order of Megawatts (MW). The establishment of the diverse models of electric parameters and the development of the methodological tools available in the environment MATLAB/Simulink are interpreted [1]. The main components of the chain of conversion are modelled and the DFIG makes the object of a particular attention as for its sizing. Analytical and numerical methods are proposed to carry out the optimal design of the entire drive including DFIG, the multiplier mechanical speed and power converter. The implementation of the environment is illustrated by solutions

The integration of wind turbines (WTs) in variable speed drive systems belongs to the main factors causing low stability in electrical networks. Therefore, in order to avoid this issue, WTs hybridization with a storage system is a mandatory. This paper investigates WT system operating at variable speed. The system contains of a permanent magnet synchronous generator (PMSG) supported by a battery storage system (BSS). To enhance the quality of active and reactive power injected into the network, direct power control (DPC) scheme utilizing space-vector modulation (SVM) technique based on proportional-integral (PI) control is proposed. Meanwhile, to improve the rendition of this method (DPC-SVM-PI), the rooted tree optimization technique (RTO) algorithm-based controller parameter identification is used to achieve PI optimal gains. To compare the performance of RTO-based controllers, they were implemented and tested along with some other popular controllers under different working conditions. The obtained results have shown the supremacy of the suggested PI RTO algorithm compared to competing controllers regarding total harmonic distortion (THD), overshoot percentage, settling time, rise time, average active power value, overall efficiency, and active power steadystate error.

Dynamic voltage and frequency scaling (DVFS) has been studied for well over a decade. The state-of-the-art DVFS technologies and architectures are advanced enough such that they are employed in most commercial systems today. Nevertheless, existing DVFS transition overhead models suffer from significant inaccuracies, for example, by correctly accounting for the effect of DC-DC converters, frequency synthesizers, and voltage and frequency change policies on energy losses incurred during mode transitions. Incorrect and/or inaccurate DVFS transition overhead models prevent one from determining the precise break-even time and thus forfeit some of the energy saving that is ideally achievable. Through detailed analysis of modern DVFS setups and voltage and frequency change policies provided by commercial vendors, this paper introduces accurate DVFS transition overhead models for both energy consumption and delay. In particular, we identify new contributors to the DVFS transition overhead including the underclocking-related losses in a DVFS-enabled microprocessor, additional inductor IR losses, and power losses due to discontinuous-mode DC-DC conversion. We report the transition overheads for three representative processors: Intel Core2Duo E6850, ARM Cortex-A8, and TI MSP430. Finally, we present a compact, yet accurate, DVFS transition overhead macro model for use by high-level DVFS schedulers.

The paper deals with approaches for estimation of capacitors’ condition and performances in context of their lifetime prediction for electrical drives applications. The physical structure and equivalent circuit of the high-voltage capacitor is given. Experiments for evaluation of these parameters are described. Dependences of capacitors’ technical condition and the estimated parameters are given.В статті розглянуті підходи визначення технічного стану і параметрів конденсаторів в контексті прогнозування їх терміну експлуатації в складі електричних приводів. Наданий опис фізичної структури високовольтного конденсатора та пояснена його схема заміщення. Наведений опис експериментів щодо визначення параметрів схеми заміщення. Показані залежності показників технічного стану від експериментально визначених параметрів

A novel methodology for teaching the subject of dynamic response of Switch Mode (SM) systems was developed and tested in the class environment. The method applies equivalent circuit models of the power stage and the duty-cycle generation circultry to describe the low frequency behavior of SM systems and to perform numerical and symbolic analyses by general purpose computer packages (SPICE, MATLAB, MATHEMATICA). Continuous and Discontinuous Conduction Modes (CCM and DCM) of classical PWM topologies, for both voltage and current control methods are discussed.

Wide bandgap (WBG) device-based power electronics converters are more efficient and lightweight than Silicon-based converters. WBG devices are an enabling technology for many motor drive applications and new classes of compact and efficient motors. This paper reviews the potential applications and advances enabled by WBG devices in ac motor drives. Industrial motor drive products using WBG devices are reviewed and the benefits are highlighted. This paper also discusses the technical challenges, converter design considerations and design trade-offs in realizing the full potential of WBG devices in motor drives. There is a trade-off between high switching frequency and other issues such as high dv/dt and electromagnetic interference. The problems of high common mode currents and bearing and insulation damage, which are caused by high dv/dt, and the reliability of WBG devices are discussed.

A new topology has been recently proposed for grid-connected photovoltaic (PV) systems, using modular multilevel converters (MMCs) and distributing PV panels throughout the MMC cells. This topology has two main advantages: it reduces the power losses related to moving the energy into the MMC capacitors from an external source, and it removes the losses and costs related to the DC to DC converters used to track the maximum power point on string converters or central converters, because that task is delegated to MMC cells. However, traditional pulse width modulation (PWM) techniques have many problems when dealing with this application: the distortion at the output increases to unacceptable values when MMC cells target different voltages. This paper proposes a new modulation technique for MMCs with different cell voltages, taking into account the measured cell voltages to generate switching sequences with more accurate timing. It also adapts the modulator sampling period to improve the transitions from level to level, an important issue to reduce the internal circulating currents. The proposed modulation has been validated using simulations that show a consistent behavior in the output distortion throughout a wide operation range, and it also reduces the circulating currents and cuts the conduction losses by half. The behavior of this new topology and this new modulation has been compared to the mainstream topology with external PV panels and also to a fixed carrier modulation.