Search

In this article, we propose a modified finite-set model predictive control (M-FS-MPC) for multilevel switching-mode operation of grid-connected nine-level packed E-cell (PEC9) inverter. With a single-dc source, six power switches, back-to-back-connected switches as bidirectional and two capacitors horizontally extended, PEC9 inverter topology has remarkably reduced the components count. Packed E-cell (PEC) prominent feature has the capability of switching among different multilevel voltages: nine-, seven-, or five-level under faulty switch cases without any structural modification and only if the controller is appropriately designed. M-FS-MPC is proposed to operate the grid-connected PEC with the multilevel switching mode under bidirectional switch fault operation. Switching among five-, seven-, or nine-level voltages is attained by proper dc capacitors’ voltages regulation, whereas the desired current injection with low total harmonic distortion (THD) and requested power factor for addressing grid connectivity applications is guaranteed. The system discrete model is developed and the experimental results verify the performance and robustness of M-FS-MPC in targeting the capability of PEC multilevel switching-mode operation and grid connectivity requirements in both steady and transient states.

Seven-level packed U-cell (PUC7) is known as a cost-effective low-component multilevel inverter. However, PUC7 challenge is the capacitor voltage balancing; so, it conventionally needs an additional voltage control integrated into the current control loop. Because of extra variables, the control problem is further complicated for the grid-connected PUC7. This article proposes an optimized sliding-mode control (OSMC) based on the current dynamical model to track the load current reference and to self-balance the capacitor voltage in both grid-connected and stand-alone operations. By optimizing the OSMC control factor using a visual-based optimization method, PUC7 switching operation is controlled to self-balance the capacitor voltage while any extra voltage controller is needed. An adaptive control law has been also proposed for self-tuning of the PUC7 current reference to track the load and dc source variations. Experimental and simulation results of PUC7 prove the excellent performance of the proposed OSMC in achieving capacitor self-voltage balancing operation.

This paper presents a direct non-linear based predictive control for a single-phase Shunt Active Power Filter nine-level Packed E-Cell inverter (SAPF-PEC9). The proposed control based on a Finite Set Model Predictive Control (FS-MPC) has been designed to compensate the reactive power requested by the nonlinear load at the Point of Common Coupling (PCC). An outer loop consisting of a PI regulator together with a low pass filter is used to regulate the main capacitor voltage and to inject the proper filter reference current. Meanwhile, the overall design is very simple where a very fast and robust controller is achieved. Moreover the nine-level converter operation together with the direct predictive approach allows the reduction of the passive filter at the shunt converter terminals. Hence a microscale filter is obtained. The performance of the proposed hybrid controller in reactive power compensation, harmonics suppression and unity power factor operation is investigated under stiff grid conditions (zero impedance) through both normal and dynamic load-change operation. Simulation results are provided to validate the fast and effective dynamic performance, the very low harmonic content in the mains current as well as the DC capacitors balancing of the PEC inverter.

In this paper, a fixed switching frequency model predictive current controller is designed and implemented on a sensorless five-level packed U-cell (PUC5) inverter interfacing the utility. The predictive control methodology is based on a voltage vector generation technique for the cost function optimization by nullifying its derivative. The aim of the controller is to allow a fixed-frequency operation with no iterations while operating as a utility line current regulator. A pulsewidth modulator based on employing PUC5 redundant switching states fixes the PUC5 auxiliary dc bus capacitor voltage to its desired level with no necessity of a regulator; the overall technique reduces system complexity with less sensors and no loops in the predictive algorithm making it suitable for industrial applications. System discrete model is developed and experimental results verify the performance of the designed controller in making a fast response in regulating the grid current and balancing the capacitor voltage.

Many control techniques for three-phase active filters with the aim of improving the power factor and reducing the current harmonic distortion at the source level exist today and are widely reported in the scientific literature. Almost all of these methods are designed for a perfect sine-wave source and do not perform sinusoidal current when voltages are distorted or unbalanced. The work developed in this paper concerns the active filtering on a perturbed and unbalanced network. First, the proposed control method is described and validated by simulations and experimental results, and then the proposed method is compared to the classical control laws such as the original p-q theory, the modified p-q theory and the p − q − r method. Experimental results are conducted on a three-wire low power distribution network under perturbed voltage and non-linear load using a DSPACE control system. The assessment is performed on the source currents after filtering, and a comparative evaluation in terms of unbalance factor and current Total Harmonic Distortion ( THD i ) is carried out for all methods.

This document describes the Model Predictive Control MPC for a three-phase to three-phase direct matrix converter with an L filter at the input and a C filter at the output for networks connection applications and wind turbines. This AC/AC converter allows the generation of sinusoidal output voltages with variable frequency, input currents with low harmonic distortion and a unit power factor at the source. The work begins by developing the equations of the system, designing the predictive control of the system in the DQ rotating frame. The proposed MPC control uses a cost function J to select the switching state to be applied to the next switching. This gives a sinusoidal output voltage and input currents in phase with the input voltage. Simulations using Matlab/Simulink are presented to validate the proposed control scheme.

Multilevel, transformer-less inverters are becoming more and more a subject of interest in grid connected photovoltaic system due to their low cost and high efficiency features. However, most of the designed grid tied systems show more than one stage conversion process to inject the amount of power generated to the grid. Mainly, a DC-DC conversion stage is always requested between the Photovoltaic (PV) panel and the inverter. In this paper, a single-stage grid connected design based on seven level packed U-cell inverter controlled by a finite-set model predictive algorithm with a maximum power point tracking capability is presented as a competitive single-stage/phase grid-connected topology. The overall design is less complex compared to existing topologies where a maximum power point operation of the PV system is well achieved without the use of a boost converter. A predictive algorithm takes in action of the inverter control. Simulation results in MATLAB/SIMULINK are presented to validate the proposed design in both constant and variable irradiation conditions.

This paper presents a new insertion index generation method to control modular multilevel converter's (MMC) topology. Unlike classical closed-loop methods, where the sum of all measured capacitor voltages per arm is used in the generation process of insertion indices, the proposed method uses available leg average voltage, i.e., the arithmetic mean of per leg available upper and lower arm voltages. Full mathematical development of available arm voltage ripple expressions is presented. Impact of the insertion method on arm voltages driving input and output currents is thoroughly evaluated and discussed. The proposed method inherently stabilizes arm stored energy; thus, no additional control loops are required to achieve regulation of arms energy difference. Moreover, the number of measured signals to be fed back to a high-level controller is reduced to half. Analytical findings along with experimental results obtained on a 6-kVA, 10-cells-per-arm MMC proved the effectiveness of the proposed method.

In this paper, a novel controller based on the predictive technique has been introduced for a neutral-point-clamped grid-tied inverter. The aim of the developed method is to achieve a constant system switching frequency operation. The proposed method generates the voltage vector by nullifying the derivative of the cost function of a finite-set model predictive controller. The developed controller takes in action of injecting the desired grid current while a closed-loop space vector modulator regulates the capacitors voltages. A comparative study with a similar model predictive algorithm with constant switching frequency (MPC-CSF) is introduced and discussed in terms of computational complexity. Experimental results are provided to verify the performance and robustness of the new method over MPC-CSF with its ability of injecting a very low total harmonic distortion to the grid with almost unity power factor during normal and transient operations.

In this paper a fixed-switching frequency Pulse width modulator (PWM) based-Sliding Mode Control (SMC) is proposed and applied to a single phase/Five-Level/Sensor-less Packed U-Cell (PUC5) interfacing the utility. The new design takes the advantage of chattering compensation when Gao's reaching law is adopted. SMC-based controller takes in action of maintaining the utility current at a desired reference value with unity power factor and fixed-switching frequency operation. Due to self-voltage balancing feature of PUC5 inverter, auxiliary DC capacitor voltage is regulated through redundant switching states while no sensor, neither regulator are needed. The overall SMC-PWM proposed controller is less complex, more robust towards external disturbances making it suitable for single-phase renewable energy systems interfacing the utility. Simulation results on MATLAB/Simulink are provided to confirm the effectiveness and robustness of the proposed controller

In this paper an Artificial Neural Network (ANN) controller based on Levenberg-Marquart algorithm is designed and applied to a five-level sensor-less Packed U-cell (PUC5) inverter operating as grid connected mode. The advantage of the proposed design is that there is no longer required to the conventional parameters tuning snag confronted with the traditional Proportional Integral (PI) method. An offline algorithm takes in action of the controller parameters tuning calculation. The proposed ANN regulates the grid line current while the DC bus voltage is maintained constant with no need of regulator as the capacitor is self-voltage balanced in PUC5 topology. The overall design is simple as less tuning, sensors and regulators are requested compared to the conventional PI compensator case. Simulation results on MATLAB/Simulink are conducted to validate the performance of the controller in both steady and dynamic state where low Total Harmonic Distortion (THD) of the line current and high dynamic system response can be identified.

In this paper, two control methods based on predictive technique have been proposed for NPC grid tied inverter. The first method is the well-known Finite Set Model Predictive Controller (FS-MPC). It deals with the finite number of the converter switching states that optimizes a predefined cost function. The absence of the modulator in steady state performance results in generating variable switching frequency increasing system losses. Model Predictive Control with constant switching frequency (MPC-CSF), is introduced and discussed. The algorithm of MPC-CSF works in finding the optimal angle of the voltage vector in the first loop and then in finding the optimal amplitude of the voltage vector in the second loop. Simulations for the two proposed concepts were performed on Matlab/Simulink in order to verify their performance. Both methods are compared with respect to their complexity, simplicity, ability to inject current with low THD, dynamic response, and capacitor voltage balance.

In this paper, a fixed-frequency pulsewidth modulation (PWM) based on sliding-mode current controller is designed and applied to a utility interface three-phase/wire/level neutral-point-clamped inverter. The proposed design methodology of the sliding-mode control is based on a constant switching frequency operation and on Gao’s reaching law that allows chattering compensation. The aim of the controller is to inject a controlled active power from renewable energy sources into the grid while controlling the power factor and minimizing supply current harmonics. Moreover, the dc-link voltages across the split capacitors are controlled with a simple proportional–integral (PI) regulator. Experimental results show the advantages of the proposed control algorithm in terms of fast dynamic response, low voltage ripple on the dc bus, low current Total Harmonic Distortion, and robustness toward external perturbations from the dc and ac sides; moreover, a comparison with a PWM–PI current controller is presented.

This paper presents a closed-loop space vector modulation (SVM)-based sliding mode controller (SMC) for a three-level grid-connected neutral point clamped (3L-NPC) inverter. The nonlinear SMC based on Gao's reaching law has been designed to control the grid current and inject desired amount of active and reactive power into the network. Due to using single dc source at the NPC inverter dc bus, neutral point voltage is controlled through redundant switching states and instantaneous dc voltage feedback integrated into SVM technique. Meanwhile, there is no external voltage controller involved, thus no associated fine tuning issues are existed. The performance of the proposed hybrid controller to inject a desired active/reactive power to the grid is investigated through external perturbations such as change in the line current amplitude/phase shift, ac voltage fluctuation, as well as dc voltage variation. Full converter state-space model was developed and simulated. Experimental results are provided to verify the fast dynamic performance, low content of line current THD%, and good voltage balancing of dc bus capacitors of the NPC inverter.

In this paper, a model-predictive control (MPC) has been designed and implemented on the packed U-cell (PUC) inverter, which has one isolated dc source and one capacitor as an auxiliary dc link. The MPC is designed to regulate the capacitor voltage at the desired magnitude to have seven voltage levels at the output of the inverter. Since grid-connected application is targeted by this application, the inverter should be capable of supplying requested amount of active and reactive power at the point of common coupling (PCC) as well. Therefore, MPC should also consider the line-current control to monitor the exchange of reactive power with the grid while injecting appropriate active power at low total harmonic distortion (THD). Various experimental tests including change in dc-source voltage, active power variation, and operation at different power factor (PF) have been performed on a laboratory prototype to validate the good performance obtained by the proposed MPC. The dynamic performance of the controller during sudden changes in dc capacitor voltage, supply current, and PF demonstrates the fast and accurate response and the superior operation of the proposed controller.

The integration of renewable energy sources alter the radial nature of the conventional distribution network and causes the power flow to reverse in some periods. As the voltage regulator is normally designed for unidirectional power flow, this may cause voltage violations on the distribution feeder resulting in faults and cuts. To solve this problem, monitoring of the distribution network is essential before taking any control or protection measures. From this fact emerges the importance of reverse power flow detection. In this paper, the optimal phasor measurement placement for reverse power flow detection is discussed. An extensive literature review and a comparison among a wide range of existing optimization algorithms is done. Then genetic algorithm is selected to solve this problem. Global Optimization Tool of Matlab are used to test the proposed algorithm on IEEE-14 and IEEE-39 node test feeders.

A new bidirectional Z-source Matrix Converter is introduced and designed to be implemented in a Wind Energy Conversion System (WECS) using a direct-drive Permanent Magnet Synchronous Generator (PMSG). It is designed to overcome the main constraints of matrix converters such as their relatively complex modulation techniques, their high number of semiconductor switches and their voltage gain limited to 0.866. It is implemented in a PMSG-based WECS. The control strategy is based on the Rotor-Flux-Orientation Control and the optimal Tip Speed Ratio (TSR) Maximum Power Point Tracking (MPPT) algorithm while the modulation technique is the Space Vector Modulation (SVM). The performances of the overall WECS with the proposed control strategy are examined under wind speed variations. The impact of wind speed intermittency on the frequency responses is evaluated and results show that the Series Z-Source Very Sparse Matrix Converter (SZS-VSMC) is a promising solution for storage-free step-up AC-AC conversion applied in PMSG-based WECSs. The effectiveness of the proposed power converter and its implementation are verified using MATLAB/Simulink simulations performed initially with a RL load and then connected to the grid.

This paper discusses an existing Direct Power Control algorithms for three-phase three-level with neutral-point clamped (NPC) rectifiers. Direct Power Control, or DPC, implies the creation of the control algorithm in order to directly control both the active and reactive powers consumed by the rectifier, increasing the grid's power factor and reducing its current total harmonic distortion. Throughout this document, we will focus on one control algorithm directly related to DPC, through which we can achieve the rectifier control. The chosen method is the virtual flux based on DPC with space vector modulation. We will develop the mathematical model stemming from this algorithm and its operation under variable load. These tests and implementations will allow us to assert the superiority of virtual flux DPC with space vector modulation algorithm over conventional control techniques, verify the results obtained through the studied literature, and demonstrate the capacity of the algorithm to abide by the requirements and constraints. These tests will valorize, when working with medium to high power loads, the advantages of a multi-level inverter.

In this paper, a new control design is developed for the Packed U-Cells (PUC) inverter. A fixed-switching frequency Model Predictive-based (MPC) algorithm is introduced for the sensor-less five-level (PUC5) inverter to regulate the current injected to the utility when it operates in grid connection mode. The proposed method generates the candidate vector that minimizes the well-known Finite Set Model Predictive (FS-MPC) cost function. Besides, the sensor-less voltage control of PUC5 takes in action of stabilizing DC capacitor voltages with no need of additional regulator. Less complexity with no sensors, nor required iterations are obtained. Discrete system model has been introduced and developed. Simulation results on MATLAB/Simulink are provided to confirm the effectiveness and robustness of the proposed algorithm.

In this paper, a modified Sheppard–Taylor converter operating in continuous inductor current mode and discontinuous capacitor voltage mode (CICM/DCVM) is studied and implemented. The operation sequences are described and the averaged model of the converter over a switching cycle is developed. With the obtained, the dc characteristics of the converter were derived, and design criteria for components selection to ensure DCVM operation were reported. The converter is then used for power factor correction in a single-phase rectifier with a front-end diode-bridge. This mode of operation provides the converter some desirable features: zero-voltage turnoff switching and natural purely resistive behavior at low dc output voltage level. This can be achieved by simply using an open-loop control, which offers better reliability than the CICM/CCVM previously reported in the literature, where feedback control is required. The theoretical study of the converter is presented and validated through experimental measurements carried out on a 500 W laboratory prototype. It is shown that this rectifier exhibits an input power factor higher than 99.7% and a source current distortion lower than 6% at small output voltage level.

This paper introduces a new insertion index selection method to control a Back-to-Back Modular Multilevel Converter (MMC) laboratory platform. The test bench is based on a Power-Hardware-In-the-Loop (PHIL) setup constructed from two 6kVA, 3-phase, 10 cells per arm MMC systems connected in Back-to-Back configuration. The proposed insertion index selection method uses the arithmetic mean of available upper and lower arm voltages in a leg to generate insertion indices; unlike classical closed-loop methods which use the available arm voltage of each arm (i.e. sum of measured capacitor voltages in an arm). For this purpose, a detailed mathematical derivation of available arm voltage ripple equations is introduced. Furthermore, impact of the proposed insertion method on inserted arm voltages that drives input and output currents is thoroughly explored. No additional control loops for arm energy difference are required, as the proposed method inherently achieves arm energy stabilization. Nevertheless, the number of measured signals to be fed back to a high-level controller is reduced to half. The PHIL setup is formed of MMC-1 which emulates an AC grid and MMC-2 which is controlled as a grid tied converter. Analytical findings along with experimental results obtained from the Back-to-Back PHIL setup proves the effectiveness of the proposed method.

In order to correct the power factor and limit the flow of harmonics in the source, the effectiveness of active power filters associated to control law is no longer to be demonstrated. Almost all of these methods are designed for a perfect sinusoidal source and do not produce sinusoidal current when the voltages are disturbed. The work developed here concerns active filtering on a perturbed network, that is to say the presence of voltage harmonics at the connection point in addition to a system of unbalanced voltages. A proposed method called DCAP (Direct Control for Active Power) is based on new definition of the sinusoidal active currents desired on the source and assuming a unity power factor under perturbed and polluted system voltages that leads to the DCAP control strategy for active filter. This method considers the active power and the effective value of the fundamental of the voltage is described and its results are compared with those obtained by the p-q theory, the modified p-q theory and the p-q-r method for application on a three-wire disturbed and non-linear load distribution network. The comparison concerns the harmonic distortion rate (THD) of the desired currents obtained on the source as well as Unbalance Factor (UF) of the system of these currents.

There are today many techniques for controlling active filters on single-phase networks in order to correct the power factor and limit the harmonics consumed at the source. Almost all of these methods are determined for a perfect sinusoidal source. The work developed here concerns the taking into account of a perturbed network, that is to say the presence of voltage harmonics at the connection point. The results are validated by experiment on a low power system.

The massive penetration of renewable energy sources in grid-tied systems has boosted the improvement of conventional control solutions to fulfill the requirements demanded during grid faults. In this paper, balanced positive-sequence reference extraction method (BPSC) is proposed with the predictive technique to control the 3L-NPC inverter under grid sags. Only positive sequence extraction is needed to inject properly the generated reference currents through MPC controller. Moreover, no additional phase-locked loop synchronization technique is required. A Second Order Generalized Integrator filter is added for voltage sequences extraction. The overall discrete system model is developed. Simulation results show the advantages of the proposed algorithm in terms of injecting a set of balanced grid current with low harmonic content during grid sags.

This paper Introduces a novel voltage vector generation method for fixed switching frequency scheme of a finite-control set model predictive control (FS-MPC). The main feature of the proposed work is to search the optimum voltage vector responsible of minimizing the cost function. A novel algorithm based on two searching loops is introduced, the first loop optimizes the voltage vector angle while the second one defines its correspondent modulus. The optimal combination is then generated into a FS-MPC algorithm to control a 3L-NPC grid-tied inverter. A closed-loop space vector modulator takes in action of firing the switches and balancing the two DC capacitors of the inverter. The overall discrete model in (dq) frame is developed. The design of the proposed algorithm is then detailed. Simulation results verifies the effectiveness of the proposed method in fulfilling grid requirements during normal operation and against external disturbances.

This paper discusses the design and topology of the indirect matrix converter. The double space vector modulation technique (DSVPWM) is applied on the system and a unity power factor was accomplished along with desired sinusoidal input and output waveforms. The whole system is simulated using Matlab/Simulink, and the results prove to comply with the existing power quality standards.

In this paper a simple control method involving new insertion index selection scheme for control of Modular Multilevel Converters (MMC) is proposed. In contrast with classical closed-loop methods, where all available arm voltages are measured and used in the generation process of insertion indices, this method uses available average voltage, i.e. the arithmetic mean of available upper and lower arm voltages per leg. Thus, number of measured signals to be fed back are reduced to half. Moreover, development of available arm voltage ripple expressions along with the thorough evaluation of the proposed insertion method impact on arm voltages driving input- and output-currents are presented and discussed. Finally, analytical findings along with simulation results proved the effectiveness of the proposed method.

The aim of this paper is to introduce power quality added function to the standard Vienna rectifier in order to compensate reactive power and to cancel current-type harmonics drawn by nonlinear loads connected to the same point of common coupling. A theoretical investigation that demonstrates the ability of such topology to compensate harmonics and limited reactive power is first presented. Then, the design and implementation of a linear quadratic regulator with integral action is presented. The converter is controlled as a whole i.e., a multiple-input-multiple-output system, and uses an augmented model that was developed in the d- q frame. Experimental results obtained with a digital-signal-processor-based DS1103 controller and the converter operating at a 20-kHz switching frequency proved the effectiveness of the theoretical study and the high performance of the proposed control strategy in compensating load harmonics and limited reactive power.

Nowadays, grid faults consist anxious problem for grid inverters controller design. Conventional controllers are based on linear regulators such as PI and PR. This paper proposes a model predictive algorithm based on PNSC reference generation method to control the 3L-NPC inverter under grid voltage sags. The novel algorithm allows the easy inclusion of system nonlinearities, thus no additional fine tuning parameters are required. Moreover, no additional phase-locked loop synchronization technique is needed, reducing system complexity. A SOGI filter is added for voltage sequences extraction. The overall discrete model of the system is developed. Two-step horizon MPC algorithm is introduced for time delay compensation. Simulation results show the advantages of the proposed technique in terms of low harmonic line current content, low switching frequency operation, DC voltages balancing, good dynamic response and robustness to grid sags.

In this paper, two current reference extraction methods for harmonic compensation in single-phase active power filters are presented and evaluated. The first method known as the ip-iq technique is based on the fundamental extraction from the load current, whereas the second strategy which is the Direct Control for Active Power (DCAP) method employs power calculation leading to a new definition for active current in case of perturbed source voltages. The comparison is carried on in terms of DC voltage regulation in case of disturbed source voltage. First, both control schemes are analyzed based on the obtained reference currents using simulation results. It is shown that the DCAP is more accurate on the reference current extraction than the ip-iq method. Next, the performance of the DCAP method in terms of current distortion and power factor in presence of a highly perturbed source voltage is demonstrated.

this paper introduces a new control scheme based on a Finite Set-Model Predictive Control (FS-MPC) and aims of a fixed switching frequency operation. The proposed scheme allows of obtaining a voltage vector that is responsible of nullifying the cost function's derivative for its optimization. Moreover, a closed-loop space vector modulation (SVM) based on the proposed predictive control scheme is introduced for a three-level grid connected inverter. The proposed algorithm that injects a desired current to the grid is investigated through external perturbations such as change in the line current amplitude as well as DC voltage variation. Discrete-time system model was developed and simulated. Simulation results on MATLAB/Simulink are provided to verify the fast dynamic performance, and good voltage balancing of DC bus capacitors of the NPC inverter.

Due to demand increasing, most of power networks operate close to their stability limits. The high demand and the reduction of non-renewable energy sources impose the insertion of renewable energy sources. Their non-supervised insertion can cause voltage instability. In order to avoid this instability, a coordinated secondary voltage control system (CSVC) should be implemented. This paper describes the proposed procedure of CSVC system implementation. It is composed by three steps. The first step is the power network partitioning based on Self Organizing Map algorithm, the second one is the pilot buses selection based on the reduced Jacobian matrix and on voltage security performance index, and the third one is the CSVC system implementation based on the hybrid control approach using generators and shunt elements. These three steps are described in details in this paper. This procedure is used to maintain the voltage stability of large network. In this paper its efficiency is validated for small network also. Therefore it is implemented on the IEEE 39 bus system.

Modular Multilevel Converters (MMC) processing phase quantities at low frequency are vulnerable to high cell voltage ripples. MMC upper and lower arms processes pulsating power at fundamental and second harmonic phase components. As a consequence, arms are expected to buffer the energy difference exchanged between DC-link and each AC-phase. This buffered energy is translated into increased cell voltage ripple when operating at low phase frequency. Several remedies have been presented in literature, which can be classified under software and hardware methods. To address this short-come we introduced a plug-in hardware alternative that permit energy exchange between cells from upper and lower arms thus remarkably reducing capacitor voltage ripples caused by out of phase energy variations. The proposed method can improve MMC performance over the full operation region and is mainly attractive to low frequency operation such as in variable-speed motor drives where higher-than-nominal torques might be required for a wide speed range. Performed simulations over a synchronous machine using maximum torque per current control technique, conforms well with the analytical findings and shows the effectiveness of the proposed method.

This paper presents a new control technique applied on a multilevel inverter recently launched, the Packed U-Cells also known as PUC inverter. PUC became the interest of several studies for different applications mainly for the grid connected systems. In this work, Model Predictive Control (MPC) is used to control the grid current and the auxiliary capacitor voltage in the grid connected PUC inverter. Matlab-Simulink-SimPowerSystems is used to validate the good dynamic performance of the proposed controller applied on the PUC inverter.

New definition for active current in case of perturbed source voltages is developed and employed as reference compensation currents for an active power filter. In this paper, different control methods using the instantaneous power theory approach are applied to the 3-phase 4-wire split-capacitor Shunt Active Power Filter (SAPF). The control techniques that have been considered for comparison are: the original p-q method, the modified p-q, the pseudo-mapping matrix, the p-q-r theory, the NF p-q method, and the proposed Direct Control for Active Power (DCAP) novel method issued from the novel definition of active current. All these control schemes are compared in two aspects. First, a qualitative comparison, based on simulation results, is performed on the source and neutral currents in all cases of sine-wave/distorted and balanced/unbalanced source voltages. Then, a quantitative comparison is carried out to evaluate the performance of each method in different operating conditions. Three indexes are used for this assessment: 1) the current Unbalance Factor (UFi) in accordance with IEEE 1195-1995, 2) the Total Harmonic Distortion (THD), and 3) the rate of neutral current compensation. It will be proven that the DCAP method ensures sinusoidal and balanced source currents with a THD and an UF that meet the standard requirements in all cases of operation, as well as a compensated neutral current on the source side.

The grid connectivity requirements imposed today, ask for an accurate controller design able to deal with system constraints and nonlinearities. In order to fulfill grid international standards, this paper details a Finite control set model predictive controller called FCS-MPC as part of controlling an energy conversion system. It uses a discrete time 3L-NPC inverter model (in the α-β frame) to predict the future values of the injected current and DC capacitors voltages. Switching pulses are chosen to ensure the optimum errors between the controlled variables and its desired values. Simulations results for both one-step and two-step horizon have been introduced to verify system robustness and dynamic response against variations of the DC link voltage, AC side current/voltage and reactive power. Low current-distortion levels with an arbitrary power factor prove the system performance when a two-step horizon control algorithm is adopted.

In this paper, sliding-mode control is applied on multi-input/multi-output (MIMO) nonlinear systems. A novel approach is proposed, which allows chattering reduction on control input while keeping high tracking performance of the controller in steady-state regime. This approach consists of designing a nonlinear reaching law by using an exponential function that dynamically adapts to the variations of the controlled system. Experimental study was focused on a MIMO modular robot arm. Experimental results are presented to show the effectiveness of the proposed approach, regarding particularly the chattering reduction on control input in steady-state regime.

In this study, a small-signal model-based linear control design of a single-phase AC-DC dual boost power factor correction (PFC) pre-regulator is presented. The converter consists of two interleaved boost converters. A high rated main boost, used for current wave-shaping and energy control, operates at low frequency; whereas an auxiliary boost uses a low rated device operating at high frequency and is controlled to compensate the low-frequency ripple generated by the main boost. The control scheme proposed for the dual PFC is based on a small-signal averaged model of the converter, which is developed using the state-space average modelling technique along with the small-signal linearisation process. The linear controllers are designed in the frequency domain, and are adjusted in order to ensure the required performance of the PFC, namely a close-to-unity input power factor and a regulated DC voltage. Experimental results based on a laboratory 1 kW prototype validate the proposed theoretical approach.

A new single-phase power factor corrector (PFC) based on the Sheppard-Taylor topology is studied. Compared with conventional PFCs, this topology facilitates a better input current tracking, lower voltage stresses across the devices and larger output voltage range for the same operating area. The converter is integrated as a PFC at the DC-end of a single-phase diode bridge. Pulse-width-modulated (PWM) multi-loops control schemes are proposed and developed in order to ensure a unity power factor at the AC-source side and a regulated voltage at the DC-load side. The first control method uses the simple and robust hysteretic-based controller; the second employs a conventional PI regulator; and the third is based on the model nonlinearity compensation approach. The design of the last two control methods is based on the knowledge of a mathematical model that would accurately represent the converter. This model is developed in this paper using the state-space averaging technique, and then the small-signal transfer functions of the converter are derived for linear control design purpose. The performance of the different control strategies is evaluated through simulation experiments carried out on a numerical version of the converter. The implemented model of the converter is obtained by using the switching function technique. The control system is tested under both rated and disturbed operating conditions. The system performance is evaluated in terms of source current total harmonic distortion (THD), input power factor, DC voltage stabilization, and regulation following load variations.

In this paper, the design and implementation of a new multiple-input-multiple-output linear control technique based on a theoretically established and experimentally validated small- signal model for the three-phase three-level boost-type ac/dc Vienna converter are presented. Averaging and local linearization techniques are used to derive the dynamic model expressed in the dqo reference frame. The resulted transfer functions are discretized for the sake of a digital controller design. Multiple-loop control strategy is adopted and consists of inner current feedback loops, which are based on the straightforward looping technique that neglects interactions between the dq components of control inputs and currents, respectively, and of an outer voltage loop, which is designed to ensure dc voltage regulation by adjusting the magnitude of the references for the inner current loops. The output dc voltage unbalance is also controlled in the inner loops. The proposed modeling and control approaches are first simulated and then validated on a 1.5-kW laboratory prototype supported by the DS 1104 digital real-time controller board of dSPACE. The obtained results prove the accuracy of the proposed new small-signal model and, therefore, its reliability for dynamic analysis and control design purposes. It is also proved that a judicious choice of controller parameters, as well as an adequate rating of boost inductors, allows one to meet the IEEE standard requirements in terms of ac line-current total harmonic distortion and power factor. The efficiency of the proposed control technique is maintained in case of disturbances occurring on both source and load sides.

This paper presents and analyzes experimental results of a new discrete multiloop nonlinear control scheme, applied to a 1.5-kW laboratory prototype of a three-phase/level/switch boost-type Vienna rectifier. As for most split dc-bus voltage switched-mode rectifiers, the proposed control technique aims to ensure ac line currents shaping, output dc-bus voltage regulation and dc load unbalance compensation. The proposed technique is based on the dq nonlinear averaged model of the converter. To cancel the inherent nonlinearity of the converter, an input- to-output transform is applied to both inner and outer loops, thus linearizing the system and allowing the application of conventional linear pole placement method for controller tuning. The rectifier performance, during both nominal and severe operating conditions, are then evaluated in real-time using the dSPACE DS 1104 controller board, supported by a Matlab/Simulink real-time workshop environment.

In this paper, a large-signal modeling technique has been developed for a three-phase, three-level Vienna rectifier operating in continuous conduction mode. The considered circuit is a fifth-order system with time-varying variables on the ac side. This model is first established in the direct abc reference frame using the state space averaging technique, then modified through an abc/dqo transform and adequate duty cycle alteration to avoid time-dependency. The system stability in a closed loop, using a multiloop PI-based control scheme, is proved by the convergence of the phase plane trajectories to the nominal point for any initial condition. These curves are drawn as ac line peak currents as a function of total output dc voltage. The different relationships governing the system inputs/outputs are verified not only for the nominal operating point, but also for a wide operation range. The accuracy of the proposed model is verified on a 1.5-kW experimental prototype controlled by the DS-1104 board of dSPACE. The converter large signal behavior is experimentally analyzed using output time domain responses toward different input variations. Significantly high accordance between the experimental results and the theoretical model, implemented with SIMULINK/Matlab, is verified.

In this paper, a component efficient multilevel rectifier is modeled and controlled using Model Predictive Control (MPC) technique. The recently introduced Capacitor Tied Switches (CTS) converter structure features two distinct dc-load terminals which can operate at different voltage levels while experiencing high voltage levels at the ac-side terminals. The CTS converter structure inherits attractive features from the efficiency and power quality perspectives, with excellent topology performance which was validated through different simulation scenarios.

The non-supervised insertion of renewable energy sources into electric power networks causes fluctuations that may lead to voltage instability. The simple and coordinated secondary voltage control systems are used to avoid this instability. To obtain maximum regulation performance with optimized number of controllers, an appropriate selection of pilot buses is suggested. In this paper new algorithm is proposed to select optimal pilot buses. This method is based on the singular decomposition of the reduced Jacobian matrix with the voltage security margin index. To evaluate the efficiency of this algorithm, a comparison with the Bifurcation, Clustering with Node-Partitioning Around Medoids and the Hybrid algorithms is proposed. The simulation results show that the proposed algorithm gives optimal pilot buses according to the selection criteria (explained later in the paper).

In this paper a new single-phase five-level buck-boost active rectifier is introduced called capacitor tied switches (CTS). The proposed rectifier has two independent DC outputs that can be connected to two different loads. Different switching states and the average mode of the proposed topology are analyzed to design the associated controller aims at regulating the two output DC voltages, generating five-level voltage at the input of the rectifier and finally draw unity power factor and sinusoidal current from AC grid. From AC grid view, the rectifier works in boost mode however the generated DC voltage can be split into two separate outputs which may be less than the AC peak voltage or even more leads to work in both buck and boost operation mode. Full simulation results are shown and analyzed to validate the effective operation and good dynamic performance of the proposed five-level buck-boost rectifier.

The aim of this paper is to compare the performance of the single-phase shunt active power filter (SPSAPF) and the single-phase shunt hybrid power filter (SPSHPF) that adopt both an indirect current control scheme with a unipolar pulse width modulation (U-PWM) strategy. The SPSHPF topology includes, in addition to the components of the SPSAPF, a power factor correction capacitor connected in series with a transformer. The primary winding of the transformer is connected to the single-phase voltage-source inverter, which is the main part of the filter. The indirect current control technique that is implemented for both filters is based on extracting the source current reference from the distorted waveform of the load current. The U-PWM control technique is based on comparing simultaneously a triangular high frequency carrier signal with a slow-varying regulation signal and its opposite. The double comparison process results in the gate signals for the semiconductors. A laboratory prototype for each filter is built. It is demonstrated that the rating of the inverter used in the SPSHPF is three to four times lower than the one corresponding to the SPSAPF. In addition, the performance of the SPSHPF is found to be much better than that of the SPSAPF as far as the line current distortion is concerned.

This paper presents a performance evaluation of three-phase, three-switch, three-level, fixed-frequency pulse-width-modulated (PWM) rectifier, when an inductive connection is added between the DC-side capacitive mid-point and the AC-side source neutral. A new continuous-mode model that takes into account the presence of the added zero-sequence inductor is developed using the state-state averaging technique in the synchronous frame. The stability and the performance of the converter in terms of input current Total Harmonic Distortion (THD), power factor and DC voltage regulation are investigated, even for operation under unbalanced DC loads. The converter characteristics are evaluated for different values of the zero-sequence inductor in an attempt to derive useful optimized criteria for the design of the converter. The proposed study is supported by numerical simulations that are carried out a switching-functions-based model of the converter.

This paper studies the application of fuzzy logic control on a five degrees of freedom (DOF) robot arm, the Maker 100 of U.S. Robots. The elaboration of the fuzzy control laws is based on two structures of coupled rules fuzzy PID controllers. The fuzzy PID controllers are numerically simulated and the simulation results confirm the success of the fuzzy PID control in trajectory tracking problems. Seeking a performance optimization, a systematic study of the choice of tuning parameters of the controllers is done. The success of the proposed fuzzy control law is again affirmed by a comparative evaluation with respect to the computed torque control method and the direct adaptive control method, the last two controls being also numerically implemented using the same dynamic model of the robot arm.

In this paper, a new control strategy based on the pulsewidth-modulation technique is proposed and applied to an active-current-injection-based unity-power-factor three-phase ac-dc converter. The control circuit of the converter consists of a multivariable inner current regulator and an outer voltage regulator. Based on linear control techniques, the control circuit has been designed. Averaging techniques are used to derive a linear small-signal model of the converter in the frequency domain. Numerical simulations using the Power System Blockset tool of Matlab/Simulink highlight the performance of the proposed control scheme. Experimental results obtained on a 2-kW prototype validate the theoretical approach described in the paper.