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EPE 2015 - DS1b: Standard and Advanced Control Techniques for Power Converters
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2015 ECCE Europe - Conference > EPE 2015 - Topic 03: Measurement and Control > EPE 2015 - DS1b: Standard and Advanced Control Techniques for Power Converters
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	9 kW SiC Mosfet based DC/DC Converter   By Lech M. GRZESIAK	[View]   [Download]
Abstract: In this paper a 9 kW DC/DC converter based on SiC MOSFET devices is presented. Precise control of the output voltage is realized with the help of a state feedback controller with an additional integral action. Simulation and experimental test results as well as an efficiency of DC/DC converter are presented. The behavior of the converter was investigated during no-load and variable load operation. Device efficiency was also investigated and it was found that the efficiency exceed 98\% in a wide operating range.
	A Converter Control Field Bus Protocol for Power Electronic Systems with a Synchronization Accuracy of +/- 5 ns   By Christoph CARSTENSEN	[View]   [Download]
Abstract: This paper is presenting a field bus protocol for modular converter systems. It is optimized for minimal cycle times and synchronisation of the converter modules to +/- 5 ns. The principle of operation is shown in detail, implemented on an FPGA based prototype system and validated by multiple measurements.
	A Generalized Predictive Current Control Method based on Two Vectors for Three-Phase Voltage Source Inverters   By Sangshin KWAK	[View]   [Download]
Abstract: In this paper, a generalized predictive current control method based on two vector utilization in one sampling period are proposed for regulating load currents of three-phase voltage source inverters (VSIs) with small current errors and current ripples. In the proposed method, selecting two future voltage vectors and partitioning them in a future sampling period are determined by an optimization process, by considering all 49 possible combinations producible by two voltage vectors of the three-phase VSI.
	A hybrid discontinuous modulation technique to influence the switching losses of three phase inverters   By Julian WOELFLE	[View]   [Download]
Abstract: This paper presents a modulation technique, which combines the known space-vector-pulse-widthmodulation (SVPWM) and the discontinuous-pulse-width-modulation (DPWM). This enables thepossibility to set the switching losses freely within a certain border band. A possible area ofapplication is the reliability of IGBT-inverters modules, where junction temperature swings can bereduced by influencing the power losses. The functionality is underlined by the analytical derivation ofthe switching and conduction mean power loss equations which are verified by measurements incertain operation points.
	A New Non-Characteristic Harmonic Compensation Method in Three-phase Active Power Filters Equipped with a Small DC Capacitor   By Tomoyuki MANNEN	[View]   [Download]
Abstract: This paper proposes a new control method suitable for active power filters equipped with a small dc capacitor. The proposed method can achieve not only suppressing the dc capacitor voltage fluctuation in transient states but also compensating all harmonic components in steady states. The proposed method employs a harmonic detection method based on the 7-step compensator and a repetitive controller with a comprehensive harmonic detection method. The experimental results using the active power filter with a small dc capacitor of 300-uF have confirmed that the proposed method has the capability to compensate non-characteristic harmonics produced by a 15-kW diode rectifier in steady states without any voltage fluctuations in transient states.
	A New Understanding and Improvements of Finite Set Model Predictive Control in Inverter Applications   By Galina MIRZAEVA	[View]   [Download]
Abstract: This paper proposes a new interpretation of Finite Set Model Predictive Control (FS-MPC) for inverters. This interpretation gives insights into the existing limitations of FS-MPC and suggests mitigation strategies. Consequently, significant improvements of FS-MPC performance are achieved, including elimination of steady state error, improved harmonic spectrum, reduced control delays, etc.The proposed new MPC interpretation also establishes relationships between various control schemes, including FS-MPC and PWM-MPC, FS-MPC and MPC with integral action, etc. Additionally, the paper proposes further embellishments to FS-MPC based on its more efficient and accurate implementation. The findings of the paper are supported by simulations and experimental results.
	A Novel Capacitor Voltage Balancing Method for Distributed Switching Frequency in a Modular Multilevel Converter Application   By Si-Hwan KIM	[View]   [Download]
Abstract: This paper proposes a novel capacitor voltage balancing method for a modular multilevel converter in order to make a switching frequency of sub-module converter evenly distributed, while maintaining the voltage balance within a desired range. Similar to the conventional, the proposed method is based on the sorting algorithm which is widely used due to its simple and effective implementation, but introduces double target bands, voltage deviation band and switching commutation band, to avoid unevenly increased switching commutation. Several simulation results are provided to verify the effectiveness of the proposed method.
	Adaptive Digital Current Mode Controller for DC-DC Converters   By Fazel TAEED	[View]   [Download]
Abstract: An adaptive control technique for a digital current mode control of dc-dc converters is proposed in this paper. The adaptive digital controller is designed to maintain the optimum gain-phase of the outer control loop regardless of the changes in the load value. In the control algorithm, the load resistance is calculated using the average current and output voltage values inside the digital processor. Next the calculated value of the load resistance is used to tune the Proportional-Integral (PI) controller such that the requirements for crossover frequency and phase margin values are fulfilled. In order to avoid the calculation burden to slow down the program execution speed, the parameter values of PI controller for each value of the load resistance are inserted into a look-up table inside the digital processor. To verify the proposed technique, the controller is implemented in an FPGA to control a buck converter. The experimental results show the excellent performance of the controller in presence of a load change.
	Adaptive Saturation for a Multifunctional Three-Phase Photovoltaic Inverter   By HEVERTON PEREIRA	[View]   [Download]
Abstract: This paper presents an inverter control scheme, based on proportional-resonant controllers, where the inverter works in multifunctional operation. In this case, the reactive power and harmonic compensation of the load are ancillary services. A resonant control is implemented in stationary reference frame (aß), where is not necessary the use of a phase-locked loop (PLL). The instantaneous power theory (IPT) is used to detect the harmonic current and reactive power of the load. These components are used as references in the inverter control strategy. Most important fact and less related in literature is the inverter current limitation strategy. Thus, this work introduces a dynamic saturation scheme for a multifunctional three-phase inverter. This strategy possibilities partial or total reactive power and harmonic current compensation without injection of low order harmonics, ensuring that the inverter current does not exceeds the rated current.
	Adaptive Switching-Loss-Optimized Space-Vector Modulation for Three-Level Neutral-Point-Clamped Converters   By Hafiz Abu Bakar SIDDIQUE	[View]   [Download]
Abstract: With ever-increasing integration of intermittent renewable energy resources in the current ac grid, the grid stability is decreasing. A potential solution to this problem is integration of large battery energy storage systems that would act as buffers for short-term grid dynamics. Since the batteries store energy in dc, a power electronic interface in the form of an inverter is inevitable for coupling with the existing ac grid. A promising converter for medium-to-high power levels at low voltage is the so-called T-type Neutral-Point-Clamped (TNPC) converter. Such a converter is operated with Pulse Width Modulation (PWM) in order to comply with the Total Harmonic Distortion (THD) requirements in the grid codes. A generalized implementation of a variant of the well-known space-vector modulation featuring lower losses is proposed in this work. The highlight of this work is a set of relations to select a switching sequence that optimizes the switching loss and the output THD. The derived relations are based on the binary logic and symmetry of the possible states of the converter. The algorithm enables the dynamic adjustment of the clamping width and the position and hence, the switching sequences to accommodate the capacitive as well as inductive behavior of the converter.
	Analysis of DC-Link Current Harmonics for Unconventional PWM strategies - Application of the double Fourier integral Method   By NAJIB ROUHANA	[View]   [Download]
Abstract: This paper presents a numerical approach for determining the theoretical harmonic components ofunconventional pulse width modulation (PWM) strategies such as the Unified-Double Carrier PWM (Uni-DCPWM). The method uses a double Fourier integral formulation to analyze the inverter DC-link current harmoniccomponents, by establishing inner and outer integral limits of this formulation. The provided results of theinvestigated modulation strategy are demonstrated by comparing with those obtained by Fast Fourier Transform(FFT) analysis of simulated switched waveforms for selected conditions. 3D graphics and generalcartographies for global variation of the DC bus RMS current are also presented, together with acomparison of the harmonic performance of a classic PWM strategy and the Uni-DC PWM.
	Cancellation of the Output Ripples of a Three-Phase Converter using Parallel-Connected Inverters and Phase-Shift-Self-Oscillating Controllers   By Jean-Claude LE CLAIRE	[View]   [Download]
Abstract: This paper deals with controls of a converter, where two paralleled-inverters are used. One inverter acts as a master unit and the other one acts as a slave unit. Thanks to these controls, an accurate tracking of the references is got and the output voltage ripples are lowered. As the goal is not to expand the system capacity, the slave unit delivers the currents to the load and becomes the power source meanwhile the master unit is in charge of the output voltage regulations. Thus the master unit compensates the ripples of the slave module output currents. In order to understand the proposed strategy, it is necessary to start with the operation of the Phase-Shift Self-Oscillating controllers. Then the operation of the paralleled-inverters is explained and a model of the power circuit is investigated. Simulations and experiments confirm the high performances in terms of ripples rejections.
	Comparison between grid side and inverter side current control for parallel interleaved grid connected converters   By Lorand BEDE	[View]   [Download]
Abstract: To meet the ever stringent grid codes, the high power converter systems have multiple converters connected in parallel and require high order filters due to their limited switching capability. Controlling the grid current and, at the same time, ensuring equal current sharing is a challenge that these converters have to face. There are two main methods on how to control the output current of the converter system: either by directly controlling the total grid current and applying the same gate signals for all parallel converters, or by controlling the individual converters' currents. Using simulation and experimental results, this paper presents the advantages and disadvantages of both control methods when applied on a converter system consisting of two parallel interleaved converters connected to the electricity grid through a high order filter. For a better comparison, a controller design for both methods is also included.
	Control of a Modular DC-DC Converter Dedicated to Energy Storage   By Alfred RUFER	[View]   [Download]
Abstract: A DC-DC converter system is presented based on an Input-Series/Output-Parallel Dual Active Bridgestructure, in a full modular design. The association of 4 elementary modules leads to a one stage DAB.The proposed converter is dedicated to interface a DC-voltage network with a battery based energystorage device. The paper aims to define and test a suited control strategy able to equalize the powerflow in the two channels. The control is established using the Energetic Macroscopic Representationand the associated Inversion Based Control. The modelling method for elaborating the control ispresented, together with experimental results.
	Control of SiC Based Front-End Rectifier under Unbalanced Supply Voltage   By Ramkrishan MAHESHWARI	[View]   [Download]
Abstract: A voltage source converter is used as a front end converter typically. In this paper, a converter which is realized using SiC MOSFET is considered. Due to SiC MOSFET, a switching frequency more than 50 kHz can be achieved. This can help increasing the current control loop bandwidth, which is not possible with the Si based converter switching with 10 - 20 kHz. Due to increased current controller bandwidth, it is possible to control the negative sequence current without a separate negative sequence current controller. This paper presents a new feedforward controller for the negative-sequence current together with a positive-sequence current controller for the front-end rectifier. A gain in the feedforward term can be changed to control the negative-sequence current. Simulation results are presented to verify the theory.
	Design of the LC+Trap Filter for a Current Source Rectifier   By MIN HUANG	[View]   [Download]
Abstract: This paper investigates an LC + trap filter for current source converters to improve the switching harmonic attenuation. The resonant frequency characteristics of the filter of current source rectifier are analyzed. A filter design procedure is proposed based on the input power factor, filter capacitor voltage and the line current THD for space vector modulation. The resonance of the input filter can be excited by the Pulse Width Modulation (PWM) and a simple passive damping can damp the resonances. The analysis and design of the input filter have been verified by simulations in MATLAB/Simulink.
	Direct Control Method for Matrix Converter with Stabilisation of the Input Current   By Nico REMUS	[View]   [Download]
Abstract: This paper presents a new control method for direct matrix converters (DMC) which combines direct torque control (DTC)of induction machines with directvoltage control (DVC) of thecapacitors in the LC filter. It stabilizes the LC filter while advantages of DTC are retained. Passive damping is not necessary which improves the filter characteristics. The functionality is proven by simulation and experimental results.
	Direct Model Predictive Control of Quasi-Z-Source Inverter Compared with The Traditional PI-based PWM Control   By Ayman AYAD	[View]   [Download]
Abstract: This paper presents a direct model predictive current control of quasi-Z-source inverter (qZSI) compared with the traditional PI control based on PWM technique. The comparison is done in terms of the tracking ability throughout the transient and the steady-state operation, the required switching frequency, and the Total Harmonic Distortion (THD\%) values. Experiment results are presented verifying the effectiveness of the model predictive control as an attractive algorithm for the qZSI.
	Dynamic Modeling and Integral Sliding Mode Controller Design for the Cuk Inverter   By ByeongCheol HAN	[View]   [Download]
Abstract: This paper proposes a PWM based integral sliding mode controller (ISMC) for the single-stage Cuk inverter. The fourth-order model of the Cuk inverter is derived first and it is simplified to use ISMC. Based on the simplified system model, the ISMC that consists of the equivalent control part plus the switching control part is designed and applied to the single-stage Cuk inverter. Comparing to conventional controller, the ISMC can accurately control the output current of the single-stage Cuk inverter. Simulation and experimental tests using the prototype of the single-state Cuk inverter were performed to validate the proposed control approach.
	Efficiency Improvement at light load in Bidirectional DC-DC converter by utilizing Discontinuous Current Mode   By Nam LE	[View]   [Download]
Abstract: This paper proposes a feedback current control for bidirectional DC-DC converter which is operated in Discontinuous Current Mode (DCM) at light load and Continuous Current Mode (CCM) at heavy load in order to improve light load efficiency. In the proposed method, the nonlinearity compensation for DCM operation is constructed by using the duty ratio at previous calculation period. Moreover, the introduction of DCM current feedback control into bidirectional power conversion is accomplished by detecting the operation mode at the output of the control system. This make the control becomes parameter-independent. The validity of the proposed control is confirmed by a 1-kW prototype. In the ramp response, the slope of the DCM current almost agrees to the design value with the error of 0.8\%. Moreover, the smooth transition among 4 current modes: CCM-powering, DCM-powering, DCM-generation, CCM-generation, is also confirmed. On the other hand, in order to further improve the efficiency at light load, the synchronous switching for DCM is proposed. As a result, at load of 0.1 p.u. the efficiency of the DCM synchronous switching is improved by 1.5\% from 97.2\% to 98.7\% compared with the CCM synchronous switching. Besides, it is confirmed that, the efficiency of the CCM/DCM synchronous switching is higher by 0.2\% than that of the CCM/DCM asynchronous switching at all range of load. Furthermore, the efficiency at rated load is 98.8\%, whereas the maximum efficiency is 99.0\% at load of 0.45-0.65 p.u..
	Flyback Converter Using an Observer-Based Digital Controller   By Ya ZHANG	[View]   [Download]
Abstract: A scheme is presented to integrate a primary-side-sensing technique into a model-predictive-controller for a Flyback converter. The control circuit consists of a signal processor, an observer, and a model-predictive controller. Besides inheriting the advantages of model-predictive-control, e.g. optimal trade-off between overshoot, fast stabilization and constraints handling, the proposed controller saves on hardware by applying primary-side-sensing.
	Harmonic Comparison of Two Existing Modulation Strategies Applicable to a Multi-Level Cascaded H-Bridge Converter   By Roberto ALVES BARACIARTE	[View]   [Download]
Abstract: This paper outlines a comparison between two traditional modulation strategies according to some indicators and figures of merit. The paper highlights the harmonic performance benefits of Average Value Modulation (AVM), which is a scheme that produces the same output voltage waveforms as level shifted modulation. The comparison was carried out using a well-established model and an ABB/FACTS simulation Tool. Experimental verifications will be the subject of a later paper. The comparative analysis shows that 'AVM' improves the harmonic content in the range of low frequencies by a small increase of the harmonic content in the high frequency range. The high-frequency electromagnetic interference can be reduced by filtering high frequencies at a lower cost.
	Implementation of Iterative Learning Control based Deadtime Compensation for PWM inverters   By Lazhar BEN-BRAHIM	[View]   [Download]
Abstract: Deadtime effects in PWM inverters are nonlinear and depend on the switching frequency of the inverters and the types of power devices, snubber circuits, and loads. Several deadtime compensation methods were proposed in the literature where some are based on the polarity of reference current. In these cases, the actual current ripples around the zero crossing cause inverter output voltage distortions. This paper discusses and implements a deadtime and current zero crossing effects compensation method based on Iterative Learning Control (ILC) technique. Preliminary off-line experimental results confirmed the feasibility of the proposed method. Note that, beside the compensation for the above effects, the proposed technique may be also used to compensate for the effects caused by snubber circuits and switching devices imperfections such as voltage drop and on/off delay.
	Influence of Modulation Method on Using LC-Traps with Single-Phase Voltage Source Inverters   By Xiongfei WANG	[View]   [Download]
Abstract: The switching-frequency LC-trap filter has recently been employed with high-order passive filters for Voltage Source Inverters (VSIs). This paper investigates the influence of modulation method on using the LC-traps with single-phase VSIs. Two-level (bipolar) and three-level (unipolar) modulations that include phase distortion and alternative phase opposition distortion methods are analyzed. Harmonic filtering performances of four LC-trap-based filters with different locations of LC-traps are compared. It is shown that the use of parallel-LC-traps in series with filter inductors, either grid or converter side, has a worse harmonic filtering performance than using series-LC-trap in the shunt branch. Simulations and experimental results are presented for verifications.
	Minimum Power Losses Operation for Switched Capacitor Converters   By Rodrigo SANTOS	[View]   [Download]
Abstract: In this paper, a new operation strategy for switched capacitor converters is presented. This operation mode increases the converter efficiency throughout all the load range, including heavy and light load conditions. The efficiency is increased by adjusting the switching frequency, based on the analysis of the power loss model. In order to support this concept, theoretical analysis and experimental results are applied.
	Model Predictive Control for an Asymmetric Multilevel Converter with Two Floating Cells per Phase   By Marcelo VÁSQUEZ	[View]   [Download]
Abstract: This paper proposes a control scheme based on predictive control for an Asymmetric Multilevel Converter,composed of a two-level inverter and two floating cells per phase. Main cell is handled by usinga simple modulation that selects the sector of the reference vector and floating capacitor voltages arecontrolled to maintain an optimal asymmetry to maximize the number of load voltage levels with a smallnumber of calculation, selecting only near sub-sectors and vectors of previous solution. This approachpermits an improvement in the current quality and a reduction in the number of calculation. Results arepresented in simulations.
	Modified PWM algorithm for low duty in SRC   By Petr SPANEL	[View]   [Download]
Abstract: This paper shows modified PWM algorithm for control of the series resonant converter working withthe low duty cycle in comparison with standard PWM. Proposed algorithm is used in combinationwith standard PWM to achieve lowest switching losses in whole output voltage range. The standardalgorithm uses basic pulse-width modulation with pulses centered to the waveforms of current. That isdisadvantageous, when the low output voltage is needed (low duty cycle). The proposed PWMalgorithm uses two pulses, instead of one, in one half of period. The first pulse starts in instant, whenthe current crosses zero and the second pulse ends in time, when the current also crosses zero asshown in the paper.
	Modulated Model Predictive Current Control for Direct Matrix Converter with Fixed Switching Frequency   By Manjusha VIJAYAGOPAL	[View]   [Download]
Abstract: Matrix converters have become popular due to their capability for direct ac-ac conversion without adc-link capacitor. Several modulation methods have been proposed for matrix converters includingSpace Vector Modulation (SVM), which has been widely used in conjunction with numerous differentcontrol approaches as it can ensure sinusoidal input and output currents with unity power factor andfixed switching frequency. Model Predictive Control (MPC) is a control strategy introduced recentlyfor power converters with several benefits like fast transient response and possibility to controlmultiple variables without cascaded loops; however it produces a variable switching frequency. Thispaper introduces a new control technique for direct matrix converters that combines the features of theclassical MPC and SVM technique into a Modulated Model Predictive Control (M2PC) with fixedswitching frequency. Simulation results showing the effectiveness of the method in controlling a directmatrix converter feeding a passive RL load are presented in this paper
	Modulator for Five-Leg Voltage-Source Inverters   By Tomas KOMRSKA	[View]   [Download]
Abstract: This paper is concerned with design of a new general PWM method dedicated for multiphase converters. The proposed approach is based on the minimum infinity-norm solution which enables optimization of control signals for arbitrary number of phases with maximum dc-link utilization. The verification is performed for three and five phase converters by both simulations as well as experiments on laboratory prototypes.
	Multilevel direct current control for grid-connected inverters   By Markus SCHAEFER	[View]   [Download]
Abstract: One of the most important requirements for grid-connected inverters is an accurate control of the line currents. Applying the 'switched diamond hysteresis control (SDHC)' to multilevel inverters combines the advantages of both techniques and is an enabling step towards a better inverter performance than using state of the art controllers. The hypotheses are further investigated in a real hardware test setup. Experimental results proof the excellent dynamic of the SDHC control algorithm.
	New Strategy to Balance Neutral-point Voltage in Three-level VSI Based on SVM Regarding Output Current   By Abbas DEHGHANIKIADEHI	[View]   [Download]
Abstract: This paper proposes new modulation strategy in order to balance neutral-point voltage in the three-level Voltage Source Inverter (VSI). In the proposed method, not only initial neutral-point voltages and wanted voltage vector but also resulted current is used to detect and apply appropriate space vectors. In this method, all space vectors can be categorized into two dynamic groups which are P-Type and N-Type vectors. For each dynamic category, containing vectors are selected based on resulted current vector. This method slightly injects high order harmonics which lead to enhance voltage THD, due to using small and medium space vectors. Respecting dynamic categorizing, the proposed method has strong capability to rapidly balance neutral-point voltage, with regardless ripple for all modulation index ranges and balanced/unbalanced loads. Simulation results verify the validity and capability of the modulation strategy, also the proposed method is easy to implement without adding any extra hardware and expenses.
	Novel MMC control for active balancing and minimum ripple current in series-connected battery strings   By Damien FROST	[View]   [Download]
Abstract: The performance of a string of series-connected batteries is typically restricted by the worst battery cell in the string and a single failure point will render the entire string unusable. To address these issues, we present a decentralised battery management system based on a modular multilevel converter (MMC) with a distributed inductor. This novel MMC design enables each MMC cell to operate autonomously, without central control, by sensing the local inductor voltage. Batteries are loaded with a current proportional to their capacity, and the MMC cells also work together to minimize the output ripple voltage of the full series stack. We show experimentally that the novel decentralized controller implemented in each MMC cell can reduce the output voltage ripple by 69\%. We also give an extensive theoretical analysis of the waveforms produced by the MMC using Fourier decomposition. This analysis has applications in all modular multilevel converters.
	Performance Characteristic of Digital Peak Current Mode Control Switching Power Supply   By Yudai FURUKAWA	[View]   [Download]
Abstract: Please note that all co-authors should be listed for every synopsis.If this is the only synopsis that you will submit, please enter every co-author once and do it manually.If you are submitting more than one synopsis and some co-authors, which you entered during your first submission, have to be linked to your second, third, fourth… synopsis, please find and select them by using the search option.
	PFC-Control for Improved Inductor Utilization   By Lukas KEUCK	[View]   [Download]
Abstract: Inductors are one of the major cost and volume driving components in PFC recti_ers. Inductors aredesigned for a particular inductance, RMS-current and peak current. This paper presents a method tominimize the peak current up to 20\%. This is done by adding a suitable harmonic content to the inductorcurrent which barely modi_es its RMS-value. Using the proposed method, a smaller, more ef_cient ora cheaper inductor can be designed. Further, the presented method fully satis_es the harmonic standardEN-61000-3-2.
	Predictive Digital Peak Current Mode Controller with Inductor Inductance Estimation for DC-DC Converter   By Karsten HOLM ANDERSEN	[View]   [Download]
Abstract: This paper presents a Digital Predictive Peak Current Mode controller which uses inductor inductanceestimation to estimate the inductor current slopes and to predict the inductor current in bothdiscontinuous and continuous conduction mode. The estimated current slopes are used for controllingthe current loop. The proposed controller is implemented in a Field Programmable Gate Array (FPGA)to control a 450 W buck converter and the experimental results verify excellent inductor inductanceestimation and demonstrate the achievement of a very fast digital controller.
	Repetitive neurocontroller with disturbance dual feedforward -- choosing the right dynamic optimization algorithm   By Bartlomiej UFNALSKI	[View]   [Download]
Abstract: The paper presents a recently developed repetitive neurocontroller (RNC) that does not require additional filtering and/or forgetting to robustify it, i.e. to circumvent the long horizon stability issue present in the classic iterative learning control (ILC) scheme. Initially, the Levenberg--Marquardt (L--M) error backpropagation (BP) algorithm was used as a DOP(dynamic optimization problem)-capable search mechanism. At that time the choice of the training algorithm was made based on the frequently reported effectiveness of the L--M method in static optimization problems. However, there is an abundance of neural network training methods characterized, e.g., by different convergence rates, computational burden, noise sensitivity, etc. The performance of a particular optimization method is always problem specific. The case study of a constant-amplitude constant-frequency (CACF) voltage-source inverter (VSI) with an LC output filter is analysed here and some recommendations regarding the trade-off between convergence rate and computational complexity are made. The robustness to a measurement noise is also tested. The comparison is based on the results of numerical experiments. A couple of algorithms is then suggested for real-time implementation.
	Research on Typical Harmonic Elimination Algorithms in Phase Synchronization Control   By Liansong XIONG	[View]   [Download]
Abstract: Phase synchronization results in distorted grid contain a certain amount of oscillations, failing to meet the requirement of high-performance grid-connected power converters. Moving Average Filter (MAF) and Delayed Signal Cancellation (DSC), as well as their derivations, i.e. Cascaded MAF (CMAF) and Cascaded DSC (CDSC), are main solutions to this problem. In this paper, the mathematical models of these methods are analyzed, and their improved versions, namely Periodical MAF (PMAF) and Periodical DSC (PDSC) are proposed, tackling the problems of conventional CMAF and CDSC in dealing with multiple harmonic components. Further comparisons are made between these methods, based on the dynamic performance, required data storage size, harmonics elimination and high-frequency noise suppression ability. A selection criterion for practical applications is established. Experiments results under different operating conditions are coherent with the analysis of these methods, and also con_rmed the superiority of the proposed derivations.
	Robust Controller Design for Phase-Shifted Full-Bridge Series Resonant Converter under the Nonlinear Load   By Sungho SON	[View]   [Download]
Abstract: In this paper, a third-order sliding mode control (3-SMC) scheme is proposed for the phase-shifted full-bridge series resonant converter (PSFB-SRC) which has a nonlinear characteristic and experiences the nonlinear load variation when it is used in DC/DC power supply application. 3-SMC is effective in compensating the nonlinear load variation in nonlinear system. The system modeling of resonant tank and output filter are derived, and the 3-SMC which is comprised of an equivalent controller and a switching controller is developed. Numerical simulations are performed to validate the proposed control approach.
	Sequential Cycle Stealing - A novel control method dedicated for resonant converters   By Rafal WIDOREK	[View]   [Download]
Abstract: The most popular control method for resonant converters, the frequency modulation control, has low efficiency at loads lower than 40\%. The proposed new method called Sequential Cycle Stealing (SCS), based on patented solution (PCT/EP2012/064379), improves efficiency by introducing selective stealing of converter switching cycles, while ensuring ZVS switching. The paper presents a preliminary implementation of the SCS controller with a brief description of its operation. The SCS controller operation is then verified in a LCLC resonant converter. Performance measurements, such as switching conditions, load step response, efficiency and conducted EMI are included in the paper. Finally, some improvements for the SCS controller are suggested in order to remedy some disadvantages of current implementation.
	SiC heat pump converters with support for voltage unbalance in distribution grids   By Ionut TRINTIS	[View]   [Download]
Abstract: This paper studies the impact of involving the demand side of the LV grid into the grid conditioningprocess. Heat pumps are distribution loads with a substation capacity increase in the last years, withexpectancy of growth in the coming years. Controlling the loads is the first step in the transition to smartgrids, and heat pumps are to be the first promising smart loads. They can be used for load shedding butalso for unbalance compensation purposes. When they are equipped with a back to back compressor driveand a proper control strategy, grid support can be provided to reduce the negative sequence component inthe voltage at the installation point. Two control strategies are proposed and investigated experimentallyon a SiC heat pump converter prototype.
	Single phase PFC control with Lyapunov method   By Jari HONKANEN	[View]   [Download]
Abstract: In this paper a current control method based on Lyapunov function for single phase active power factor correction (PFC) is presented. Lyapunov functions can be used for defining control law for either linear or nonlinear systems. The control is designed with cascade structure, where a voltage controller feeds the current amplitude reference to the current controller. The operation and performance are demonstrated with measurements from 3 kW power supply which uses power factor correction. The designed controller is shown to track the mains voltage with close to unity power factor.
	Single-phase multifunctional inverter with dynamic saturation scheme for partial compensation of reactive power and harmonics   By Heverton PEREIRA	[View]   [Download]
Abstract: Single and three-phase photovoltaic inverters are essential components of the photovoltaic (PV) systems to extracting the PV power and injecting it into the grid. Thus, in order to extract the maximum power of the solar array for various solar irradiation tracks, it is used a maximum power point tracker (MPPT) algorithm. Due to variations in solar irradiance, inverters have a current margin, which is not explored during the day. Thereby, many works have proposed the multifunctional operation. This concept consists in aggregate to the inverter control strategy other functions, such as harmonics and reactive power compensation. However, most important fact and less related in literature is the necessity of techniques to compensate partially reactive power and harmonics of the load, ensuring that the inverter works below the rated current. Hence, the present work proposes a current dynamic saturation scheme in order to compensate partially reactive power and harmonics of the load during the multifunctional operation. Simulations show that the dynamic saturation prevents the inverter to inject low-order harmonics, while ensuring the operation below the system rated current. Furthermore, control performance is evaluated for five grid-connected PV system in parallel association, in order to show the effectiveness of proposed control strategy for various dispersed PV systems in the grid. To ensure that the proposed method is applied with the maximum efficiency of the PV system, this work compares, during inverter multifunctional operation, the instantaneous and dynamic efficiency between three MPPT algorithms proposed in literature: perturb and observe; dP - perturb and observe; modified perturb and observe.
	State Current Controller With Oscillatory Terms For Three-Level Grid-Connected PWM Rectifiers Under Distorted Grid Voltage Conditions   By Andrzej GALECKI	[View]   [Download]
Abstract: This paper presents the design of a control systemof a three-phase three-level pulse-width modulated rectifier operated under unbalanced and distorted grid voltage conditions. The developed scheme is based on a voltage-oriented control method. Instead of proportional-integral current controllers a state-feedback current controller in rotating reference frame is used. In order to achieve a zero steady-state current control error in response to step commands, integral terms are incorporated into the current control scheme. Similarly, to ensure the rejection of the sinusoidal component of current control error caused by unbalance and distortion in the grid voltage, the oscillatory terms are added to the current control system. To calculate the current controller gains, an augmented plant model is developed and linear-quadratic optimization method is applied.
	Static Synchronous Generator Model for Grid-tied PWM Inverters of Renewable Energy Generation   By Liansong XIONG	[View]   [Download]
Abstract: Three-phase PWM inverters function as energy converters and grid-connected power generators in renewable energy generation systems, and its dynamic and stability characteristics affect the security and reliability of the entire generator sets and even the connected grid. The three-phase PWM inverters based on the VSG (Virtual Synchronous Generator) technology, which is referred to as the Static synchronous generator (SSG) in this article, possess the operation characteristics of Rotational Synchronous Generator (RSG), and thus enables a compatible connection of the new energy to the conventional power grid. This paper analyzes the inherent unity of SSG and RSG by the mathematical model and physical mechanisms, and applies the concept, tools and methods of the stability analysis in RSG to the SSG system. The equivalent inertia, damping and synchronizing coef_cients are introduced for the dynamic analysis of SSG and the small-disturbance stability is analyzed accordingly.
	System Identification and Adaptive Control of a DC-DC Converter using a Current Balancing ON/OFF Control Technique for Optimal Transient Performance   By Chen WANG	[View]   [Download]
Abstract: This paper presents a novel adaptive control technique for the output voltage regulation of a dc-dc buck converter application. In particular, it focuses on the impact of unexpected system parameter variation on the static and dynamic performance of the system. We apply a Fast Affine Projection (FAP) technique for the purposes of parameter estimation. This technique has previously been shown by the authors to offer excellent performance as a system identification algorithm for power electronic systems. The FAP algorithm is computationally efficient, exhibits fast parameter estimation convergence, and is highly accurate. The estimated parameters are used to develop a novel Current Balancing ON/OFF (CBOO) switching strategy during transient periods of operation. Here, constant 'ON' and constant 'OFF' periods are calculated, based on the specific parameter estimation output to achieve optimal control performance and significantly improve the dynamic response of the dc-dc converter. Simulation results demonstrate that, in comparison to classic PI control schemes, the proposed method exhibits superior dynamic performance.
	Unified Fuzzy-Logic Based Controller for Dual Function 4-Leg Shunt APF with Predictive Current Control   By Ahmed ABDELSALAM	[View]   [Download]
Abstract: Due to the rapid increase of nonlinear and unbalanced reactive loads in 4-wire distribution systems, various power quality issues such as harmonics current, unbalanced load currents, neutral current and low power factor occur. The need for green and renewable energy sources increases daily due to increase in demand for electrical power. Photovoltaic (PV) energy is an important renewable technology that requires an inverter to interface with the electrical distribution systems. Conventionally, shunt active power filter (APF) is connected in parallel to perform power conditioning tasks such as harmonic elimination, reactive power compensation, load balancing, and neutral current elimination. This paper presents a unified Fuzzy-Logic based Controller for a 4-leg APF preforming as a dual-function converter. The presented system achieves power quality tasks like: (i) reactive power compensation, (ii) harmonics current elimination, (iii) neutral current mitigation and (iv) system line-currents balance in addition to transfer locally generated renewable energy to the grid utilizing only one power electronic based converter.
	Variable Carrier Frequency Deadbeat Control for Single Phase and Three Phase Utility Interactive Inverter using SoC-FPGA   By Tomoki YOKOYAMA	[View]   [Download]
Abstract: Variable carrier frequency control of PWM inverter based on deadbeat control using SoC-FPGA based hardware controller was proposed. The inductor current was controlled using digital hysteresis method and the output current was controlled using deadbeat control with disturbance compensator. As the result, the control accuracy and the efficiency of the inverter can be adjustable with superior tracking accuracy to the reference current. Also extension to the three phase system were considered. Verifications were carried out through simulations and experiments.