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Abstract: This paper describes a strategy to optimize the switching angle of a modified H-bridge single-phase seven-level inverter for stand-alone photovoltaic (PV) system. The inverter comprises a conventional H- bridge inverter and two bidirectional switches. It can generate seven-level output voltage level, namely +Vdc, +2/3Vdc, +1/3Vdc, 0, -1/3Vdc, -2/3Vdc and -Vdc. Optimized Harmonic Elimination Stepped Waveform (OHESW) technique was employed to improve the output waveform quality. Newton- Raphson method is engaged to solve the transcendental equations from OHESW technique which produces all possible solutions with any random initial guess. Among which sets, the one producing the least output-voltage THD was chosen. Computation resulting from the optimized switching angle was simulated. A small-scale laboratory prototype was built and tested. Its results indicated the proposed method''s effectiveness and the application feasibility of the fundamental frequency switching. [Copyright &y& Elsevier]

Abstract: Reduction of energy consumption has played a significant role in industry. This paper describes a study on reducing energy consumption by machining process improvements. Methods of reducing energy consumption in a manufacturing line consisting of multiple machines are verified. First, to consolidate the processes, a series of horizontal machining centers are replaced with a 5- axis machining center. The energy consumption can be reduced by approximately 8%. The cycle time also becomes shorter by approximately 20%. Since transfer equipment is not needed in the process, reduction of energy consumption by eliminating the equipment can also be expected. Second, energy consumption in the machine tool is classified in detail. As a result, it is found that coolant related equipment consumed approximately 54% of the overall energy. Thus, the efforts are focused on the equipment. Coolant consumption of each pump is investigated. Based on the result, the coolant pumps can be concentrated in a single unit. In addition, energy consumption of the through-spindle coolant system is reduced and coolant pressure is optimized. Herewith energy consumption can be reduced by approximately 26%. Finally, the inverter frequency is optimized. As a result, the overall energy consumption in the manufacturing line is reduced by approximately 42%. [Copyright &y& Elsevier]

Abstract: This paper presents the stability analysis based on impedance representation of a single phase inverter operating as voltage source, where the Nyquist criteria can be applied. The method can be used to study the stability of a micro-grid dominated by power electronics in isolated operation mode. First, a small signal input impedance model is described. The second methodology applies no energy storage at the AC and DC side of the inverter. For two methods a comparative evaluation with the measured impedance was realized. The obtained results show that the proposed method of no energy storage can be employed in the studies of stability for micro grid systems. [Copyright &y& Elsevier]

Abstract: This paper presented a single to three-phase induction motor drive system to provide variable output voltage and frequency. The proposed drive system employs only six IGBT switches, which form the front-end rectifier and the output inverter for the one step conversion from single-phase supply to output three-phase supply. The front-end rectifier permits bidirectional power flow and provides excellent regulation against fluctuations in source voltage. Moreover, it incorporates active input current shaping feature. The control strategy of the proposed drive system of three-phase induction motor is based on speed sensorless vector control technique. A low cost of motor drive and much more advantages can be achieved using the proposed drive system. Simulation and experimental results are carried out to analysis and explore the characteristics of the proposed drive system. [Copyright &y& Elsevier]

Abstract: This paper proposes a control strategy of a three –phase five-level double converter for induction motor drives. The converter consists of the five-level NPC rectifier, DC link, and the five-level NPC inverter. In this control strategy, the DC link voltages are controlled by using a closed loop with an optimized stabilization system called clamping bridge. It provides a fast and flexible control of the converter capacitor voltage. This method will redress the imbalance of DC link voltage. This control strategy is completely independent from the load control, leading to a simpler implementation. The three-phase five-level NPC rectifier-inverter system is an ideal interface between a utility and renewable energy sources such as photovoltaic or wind generator. [Copyright &y& Elsevier]

Abstract: This paper presents a new topology of three-level single phase photovoltaic (PV) and wind power hybrid inverter. It consists of three main circuits; they are a hybrid controller circuit, a charger circuit, a pulse driver and full bridge circuit. The inverter is installed in front of Electrical Energy and Industrial Electronic Systems (EEIES) Cluster, Universiti Malaysia Perlis, Northern Malaysia. Its main energy source is a PV array and wind power generation. In this research, AC three-level waveform and square wave single phase PV and wind power hybrid inverter are developed and created by a microcontroller PIC16F627A-I/P and analyzed their performance comparisons. The result shows that the AC waveform which is formed by the PV and wind power hybrid inverter will effect on AC load rms voltage, AC current and current total harmonic distortion (CTHD), for a load of 20W 220V 50Hz AC water pump, its AC load rms voltage and current are higher when the single phase PV and wind power hybrid inverter is formed as AC square wave than as AC three-level waveform, but the CTHD is lower when the single phase PV and wind power hybrid inverter is formed as AC three-level waveform than as AC square wave. [Copyright &y& Elsevier]

Abstract: This paper presents a robust fuzzy sliding mode control of a CSI based STATCOM. The dq-frame state space model is considered for nonlinear mathematical model for the system and controller design. A nonlinear fuzzy logic enhanced sliding mode controller has been proposed to provide active and reactive power control under various faulted operating conditions. Based upon the time domain simulations in MATLAB/SIMULINK environment the proposed controller is tested and it''s better performance is shown compare with the conventional PI controllers with respect to voltage stability, damping of power oscillations and improving of transient stability. [Copyright &y& Elsevier]

Abstract: Building integrated photovoltaic (BIPV) systems bring forward many requirements to grid-tied inverters in these aspects such as generating efficiency, shading effects, harmonic & reactive current compensation and quick economical payback, etc.. This paper presents a multi-functional utility interface of BIPV systems based on cascade multilevel converter. It has two operating modes: one is operated as grid-tied inverter at normal insolation level and the other is operated as active power filter (APF) at very low insolation level or at nighttime. Compared with traditional inverters, cascade multilevel converter is much more efficient and suitable for utility interface of BIPV system because it has the merits of high efficiency, minimum switching frequency, low switching stress and EMI, approximate sinusoidal waveform voltage output with low total harmonic distortion (THD), modular structure and good dynamic stability. Simulation and experimental results have verified its feasibility and advantage. [Copyright &y& Elsevier]

Abstract: This paper proposes a grid-connected wind energy conversion system (WECS) based on a PWM multilevel currentsource inverter (MCSI) topology. The topology used here is derived from the multilevel voltage-source inverter (MVSI) by dual conversion, this allows the wealth of existing knowledge relating to the operations, modulations and control strategies of multilevel VSI to be immediately applied to such multilevel CSI. The topology are supplied with two independent DC current-sources, 2n+1 current levels are obtained at the output. In the proposed control scheme, DC-link current controller is used to regulate and stabilize dc link current, output power factor controller is used to independently control the real power or reactive power, and unity power factor is easily achieved at grid side. Validation of models, control and steady-state and transient performances of a WECS based on 5-level CSI is carried out in the MATLAB/Simulink environment. [Copyright &y& Elsevier]

Abstract: This paper deals with a fault detection technique for insulated-gate bipolar transistors (IGBTs) open-circuit faults in voltage source inverter (VSI)-fed induction motor drives. The novelty of this idea consists in analyzing the pulse-width modulation (PWM) switching signals and the line-to-line voltage levels during the switching times, under both healthy and faulty operating conditions. The proposed method requires line-to-line voltage measurement, which provides information about switching states and is not affected by the load. The fault diagnosis scheme is achieved using simple hardware and can be included in the existing inverter system without any difficulty. In addition, it allows not only accurate single and multiple faults diagnosis but also minimization of the fault detection time to a maximum of one switching period (). Simulated and experimental results on a 3-kW squirrel-cage induction motor drive are displayed to validate the feasibility and the effectiveness of the proposed strategy. [Copyright &y& Elsevier]

Abstract: This paper presents a three-phase STATic synchronous COMpensator (STATCOM) based on a current source inverter. Instead of the typical three-phase current bridge inverter it is used a power converter topology with only a single-phase current bridge inverter. A dynamic model of the STATCOM in αβ coordinates is used as a basis for control design. The control system uses a cascade structure where a fast ac current inner loop and a slow dc current control outer loop is used. For the inner loop, is used a sliding mode technique to generate αβ space-vector modulation. This fast and robust controller the ac currents of the STATCOM are actively shaped, being possible to maintain the desired currents even with high ripple DC inductor current. For the outer loop, is used a PI controller. Computer simulations are presented allowing validating the proposed STATCOM and their control system. [Copyright &y& Elsevier]

Abstract: This paper presents a new topology of three-level transformerless photovoltaic (PV) inverter. It consists of three main circuits; they are a pulse driver circuit, a full bridge inverter circuit and a power factor correction circuit that have functions as production of pulse waves, to develop alternating current (AC) waveform and to stable voltage of PV array. The transformerless inverter is installed in front of Electrical Energy and Industrial Electronic Systems (EEIES) Cluster, Universiti Malaysia Perlis, Northern Malaysia. Its main energy source is a PV array that consists of three unit PV modules, each unit has 81 V, 60 W. In this research, optimization of current total harmonic distortion (CTHD) on AC three-level waveform transformerless PV inverter is developed and created by a microcontroller PIC16F627A-I/P with change maximum voltage angle of the AC three-level waveform from 200 to 1800. Resistive load of 30 W lamp and inductive load of 20 W water pump are applied to the transformerless PV inverter. The result shows that the less CTHD of 15.448% is obtained when the maximum voltage angle is 1340. [Copyright &y& Elsevier]

Abstract: Multilevel inverters are widely used in solar energy generation systems consist of various photovoltaic generators. These converters deliver distorted output waveforms. There are trascendental equations characterizing the harmonic content but the degree of the polynomial increases with the number of DC sources or the number of harmonics to be eliminated. Also, the solutions are discontinuous in some points. In this paper, a way is proposed to minimize the output harmonics of a multilevel inverter, especially those of lower order. The Particle Swarm Optimization algorithm used to minimize the Total Harmonic Distortion, subject to restrictions on the harmonic content allowed. The appropriate switching angles can be calculated to eliminate low order harmonics. The proposed method has been succesfully applied to a cascaded multilevel converter of seven levels. Then, this method can be extended to more levels inverters. In case of a real-time application, the method can be useful because the switching angles can be stored. [Copyright &y& Elsevier]

Abstract: Power Conditioning System (PCS) in the photovoltaic system requires reliable islanding detection function (passive or active) in order to know electrical grid status and operate the grid connected inverter properly. This paper proposes a passive islanding detection algorithm based on the grid harmonic components. It utilizes the fact that the equivalent harmonic components at the point of common coupling (PCC) are changed according to the grid connection status. This method shows reduced Non-Detection Zone (NDZ) and fast detection time compared to the conventional approach. The mathematical modeling is performed and verified by experimental result using high performance DSP controller [Copyright &y& Elsevier]

Abstract: Based on the principle and the mathematical model of Active Power Filter(APF), this paper proposes a improved method which is aiming to solve the selection for dc capacitor parameter. On the basis of the instantaneous reactive power theory the energy flow relationships of ac and dc sides in APF inverters for different compensation purposes are analyzed. The voltage fluctuation is caused by the inverter power losses and instantaneous active power ac component. Taking a three-phase non-controllable load as an example, the calculation method of capacitor parameter selection is given. The voltage fluctuation of dc capacitor is less than 0.55 per cent. Then it is turned out to be true by the outcome of emulation [Copyright &y& Elsevier]

Abstract: This paper presents a shunt Active Power Filter (APF) for power quality improvements in terms of harmonics and reactive power compensation in the distribution network. The compensation process is based only on source current extraction that reduces the number of sensors as well as its complexity. A Proportional Integral (PI) or Fuzzy Logic Controller (FLC) is used to extract the required reference current from the distorted line-current, and this controls the DC-side capacitor voltage of the inverter. The shunt APF is implemented with PWM-current controlled Voltage Source Inverter (VSI) and the switching patterns are generated through a novel Adaptive-Fuzzy Hysteresis Current Controller (A-F-HCC). The proposed adaptive-fuzzy-HCC is compared with fixed-HCC and adaptive-HCC techniques and the superior features of this novel approach are established. The FLC based shunt APF system is validated through extensive simulation for diode-rectifier/R–L loads. [Copyright &y& Elsevier]

Abstract: Carrier phase-shifted PWM is specially for cascaded inverter. It has high equivalent carrier frequency and low harmonic. The output between power units is balanced,and it is easy for expansion. SVPWM has low harmonic, high voltage utilization, and it is easy for digital realization. Based on the configuration of H-bridge cascaded multilevel inverter, this paper combines SVPWM and carrier phase-shifted SPWM. A simple algorithm of SVPWM is introduced. It hasn’t any trigonometric function and irrational number calculations, which simplifies the calculation process and makes the calculation results more accurate. Simulation verification is presented to confirm the capability of the novel algorithm. [Copyright &y& Elsevier]

Abstract: This paper describes not only the hardware architecture of the servo system composed by self-made inverter and permanent magnet synchronous motor, but also its measurement and control system software features. A communication system is built based on the Modbus-RTU protocols which contain the CRC data verification between IPC and the inverter. The measurement and control software of servo system which consists of self-made inverter and PMSM is realized. The results compare with the servo system which consists of Schindler''s ATV31 inverter and SIMO''s asynchronous motor. The experiment parameters include harmonic content which is contained by phase current and voltage, and also the motor speed. The results show that the measurement and control system is stable and reliable. Both the harmonic content of the Inverter output and the motor speed meet the requirements. [Copyright &y& Elsevier]

Abstract: The objective of this paper is to propose a series-parallel resonant high frequency inverter for stand-alone hybrid photovoltaic (PV)/wind power system in order to simplify the power system and reduce the cost. The proposed inverter consists of two power stages: a DC/DC resonant converter as the input stage and a full bridge DC/AC inverter as the output stage. The input converter is operated with phase shift control, which guarantees zero current switching for most power range. This resonant converter generates a high DC voltage, which is conditioned by the DC/AC inverter to generate the desired low frequency output voltage. The DC/AC inverter is controlled using a pulse width modulation strategy. Simulation and experimental results are given to verify the system''s efficiency and have shown the performance of the proposed inverter with desired features. [Copyright &y& Elsevier]

Abstract: In this paper, a new indirect method of sliding mode control (SMC) for series converter of unified power flow controller (UPFC) is proposed. In this method, the dynamic model of controller is obtained through special concepts of state variable transform, feedback linearization and differentially flat output. This new and simple control strategy has been developed base on the modified SMC principles which utilizes only the active and reactive output powers as the control inputs. Since these measurable control inputs are known as differentially flat outputs, they have a direct influence on the state variables of series converter to control them with the capability of power oscillation damping. The absence of discontinuous component input to UPFC controller avoids the chattering effect on state variables, especially on the dc capacitor voltage of inverters. For the validation of the proposed new controller, the obtained results were compared with results obtained from the PI controller. [Copyright &y& Elsevier]

Abstract: This paper put forward a new model to analyze the grounding effect on common mode interference of underground PWM inverter. Taking into account the grounding method,the author establishs a common mode equivalent circuit of underground inverter.After Comparison of calculation results by Matlab software simulation,it can be conclude that ungrounded neutral of transformer could redue common mode current in PWM system, but not very effective, the most efficient way is to increase grounding impedance of inverter and motor. [Copyright &y& Elsevier]

Abstract: This paper presents a digital signal processor (DSP) based algorithm to generate three-level output voltage using H-Bridge multilevel inverter (MLI). The developed sinusoidal pulse width modulation (SPWM) scheme is employed to achieve lower harmonic contents in the output waveforms of inverter. Since SPWM scheme does not utilize vector positions, any pre-calculated switching states are not required. In addition to this advantage of conventional SPWM, modulators eliminate only base band harmonics due to regular control scheme. Therefore, neglecting the side band harmonics limits the efficiency of SPWM scheme. The harmonics located in the side bands of carrier frequency are also eliminated by the enhanced SPWM scheme proposed in this study. The validation of the modelled system is verified with the total harmonic distortion (THD) analyzes. The control algorithm is developed using TMS320F2812 DSP that is a 32-bit fixed-point processor operating at 150MHz. The simulation and experimental results are compared to previous studies. The THD ratios of phase voltages and currents are measured loading the inverter with a three- phase 3kW asynchronous motor. The lowest THD ratios of voltage and current are obtained at 1.9% and 0.4%, respectively. [Copyright &y& Elsevier]

Abstract: The use of inverters in induction motor control has reduced classical motor faults, such as broken rotor bars or windings short-circuit, besides improving control performance. The control becomes faster and more precise, reducing peaks in current and torque, so that the motor can have a softer operation. On the other hand, new elements are included in the system and it will be necessary to take into account their faults. These elements are sensors and power electronic devices that since a control point of view are the system sensors and actuators. Fault tolerance tries to maintain the system under control in case a fault appears in the system. If this is not possible, it takes the system to a safe operational point. In this paper a fault-tolerant control for induction motors is designed. Based on a direct torque control, new control strategies have been added in case current sensor and power switch faults are detected. The challenge is to overcome these faults without any physical redundancy of sensors or power switches as other authors propose. With the proposed control, it will be possible to guarantee the motor operation in the whole speed–torque range with one or none current sensors instead of the two usually used, though the performance will be slightly worsened. In case of inverter faults, the operation range will be restricted but the performance with respect to the fault situation is improved. [Copyright &y& Elsevier]

Abstract: This paper reports a four switch based three-phase voltage source inverter using space vector pulse width modulation (SVPWM), and designed with a three-layer feed forward back propagation based artificial neural network (ANN). The input–output samples, obtained using simulations in Matlab Simulink, were used for the extensive training of the neural network. Matlab interface with National Instruments’ NI-USB-6259 BNC was used for implementing the designed scheme with calculated weights and biases. The designed ANN based SVPWM model receives command voltage and reference speed as the inputs and generates pulse width modulated waves for the four-switch three-phase inverter bridge. The V/f ratio can be controlled by controlling the input parameters of the ANN generating PWM pulses. The simulations and experimental results, and harmonic analysis with the designed ANN structure are presented at different base speeds. The designed model was tested in under modulation, over modulation and unity modulation mode of operation and tuned to give minimum total harmonic distortion. Harmonic results at different modulation indexes are also presented. The ANN based implementation reduces the complexity of control system and overall cost reduction is achieved by the combination of FSTPI and ANN. [Copyright &y& Elsevier]

Abstract: In this paper is proposed a nonlinear current-mode control for the fuel cell/battery/ultracapacitor hybrid power sources (HPS) that improves the ripple factor of the fuel cell current. The nonlinear current control is analyzed and designed using a systematic approach. The design goal is to generate an anti-ripple via buck current controlled source in order to mitigate the inverter current ripple. All the results have been validated in several simulations. The simulation results successfully show that nonlinear current-mode control determines in the low frequency-domain better performances than other current-mode control techniques, such as the hysteretic current-mode controller or the peak current-mode controller. The current ripple factor is one of the used performance indicators. [Copyright &y& Elsevier]

Abstract: This paper proposes a design method to improve the harmonic of output voltage of a single phase inverter with an L-C output filter using fuzzy logic controller (FLC). In practice, the harmonic characteristics of circuits are complicated and entangled. There are two kinds of harmonic sources that cause inverter output voltage waveform distortion: One is the PWM switching of inverter and the other is the nonlinear characteristics of the load. In general, PI feedback control by coefficient diagram method (CDM) is used to design the output voltage filter. The relation between the L-C value and the system time constant are described with the closed form and the filter values must be calculated repeatedly to satisfy the prescribed voltage total harmonic distortion (THD) of the system. Therefore, the MATLAB Fuzzy Logic Toolbox for the fuzzy logic control algorithm is proposed. The L-C value of the filter can be set to a fixed range in the nonlinear characteristic of the practical condition, to improve the harmonic of output voltage more effectively and to avoid repeated calculation. [Copyright &y& Elsevier]

Abstract: This paper proposes an extended direct power control (DPC) for a three-phase PWM multilevel inverter fed by photovoltaic generation system (PVGS) and connected of a grid. The model contains a detailed representation of the main components of the system that are the solar array, and the grid side inverter multilevel inverter NPC VSI. In order to extract the maximum amount of from the photovoltaic generator, we propose an intelligent control method (fuzzy logic controller) for the maximum power point tracking (MPPT) of a PVGS. The DPC approach for multilevel inverter NPC which makes it possible to achieve unity power factor (UPF) operation by directly controlling its instantaneous active and reactive power. The other is a fuzzy logic controller, in the multi-DC-bus voltage control loop, developed to provide active power command. To achieve UPF operation, the reactive power command is set to zero. It is shown via simulation results that the proposed DPC has high performance. Moreover, the controller multi DC bus link voltages based on fuzzy logic has excellent performance in transient and steady states, a good robustness, a good dynamic behaviour response, and a good rejection of impact of load disturbance. [Copyright &y& Elsevier]

Abstract: This paper describes a torque ripple reduction technique with constant switching frequency for direct torque control (DTC) of an induction motor (IM). This method enables a minimum torque ripple control. In order to obtain a constant switching frequency and hence a torque ripple reduction, we propose a control technique for IM. It consists of controlling directly the electromagnetic torque by using a modulated hysteresis controller. The design methodology is based on space vector modulation (SVM) of electrical machines with digital vector control. MATLAB simulations supported with experimental study are used. The simulation and experimental results of this proposed algorithm show an adequate dynamic to IM; however, the research can be extended to include synchronous motors as well. The implementation of the proposed algorithm is described. It doesn’t require any PI controller in the torque control loop. The hardware inverter is controlled digitally using a Texas Instruments TMS320F240 digital signal processor (DSP) with composed C codes for generating the required references. The results obtained from simulation and experiments confirmed the feasibility of the proposed strategy compared to the conventional one. [Copyright &y& Elsevier]

Abstract: In this paper, a novel control strategy for a nonlinear boost inverter is proposed. The idea is based on generating an autonomous oscillator that does not need an external reference signal. This aim is achieved by using energy-shaping methodology with a suitable Hamiltonian function which defines the desired system behavior. A phase controller is added to the control law in order to achieve 180°-synchronization between both parts of the circuit as well as synchronize the voltage output with a pre-specified signal, e.g. synchronization with the electrical grid. An adaptive control is designed for dealing with the common problem of unknown load. In order to analyze the stability of the full system, singular perturbation approach is used. The resulting control is tested by means of simulations. [ABSTRACT FROM AUTHOR]

Abstract: Selective Harmonic Elimination technique is one of the control methods applied in Voltage Source Inverters to eliminate the harmonics. However, finding the solutions for the harmonic reduction is a difficult problem to be solved. This paper presents an efficient and reliable Evolutionary Algorithms based solution for Selective Harmonic Elimination (SHE) switching pattern to eliminate the lower order harmonics in Pulse Width Modulation (PWM) inverter. Determination of pulse pattern for the elimination of lower order harmonics of a PWM inverter necessitates solving a system of nonlinear transcendental equations. Evolutionary Algorithms are used to solve nonlinear transcendental equations for PWM–SHE. In this proposed method, harmonics up to 19th are eliminated using Evolutionary Algorithms without using dual transformer. The experimental results are obtained and are validated with simulations using PSIM 6.1 and MATLAB 7.0. [Copyright &y& Elsevier]

Abstract: This paper presents the analysis and comparison of the main active techniques for islanding detection used in grid-connected microinverters for power processing of renewable energy sources. These techniques can be classified into two classes: techniques introducing positive feedback in the control of the inverter and techniques based on harmonics injection. Accurate PSIMTM simulations have been carried out in order to perform a comparative analysis of the techniques under study and to establish their advantages and disadvantages according to IEEE standards. [ABSTRACT FROM AUTHOR]

Abstract: Recent advances in the power system handling capabilities of static switches have made the use of the voltage source inverter (VSI) feasible at both transmission and distribution levels. Most of the control schemes introduced were designed either for eliminating current harmonics or eliminating voltage flickers or for load flow control. They are mostly based on the PI controller. None of these control schemes were based on a systematic optimal control law that can control the converters to achieve all purposes at the same time, load flow control, voltage flicker elimination and also current harmonics elimination. This paper presents three novel control strategies: optimal control with tracking according to desired steady-state behaviour, optimal control with linear quadratic tracker design, and optimal control with tracking with PI controllers. The strategies were tested using a power system distribution model. The presented results show that all three control strategies improve the performance of the load flow and eliminate the current harmonics and voltage flicker. The controller design based on the desired steady-state behaviour is superior compared to other way of designs as the low value of the weighting matrix Q is satisfactory to obtain the desired tracking. [ABSTRACT FROM AUTHOR]

Abstract: Inverters are such electronic devices that are extensively used to convert DC power to AC power in wide-range domestic and industrial applications. DC power is usually supplied from either national grid through the rectifiers or batteries for high and low energy demands, respectively. When they are employed to feed electrical devices the efficiency of these devices tends to decrease due to harmonic occurrence in them. One solution to this problem is the selective harmonic elimination which is required to solve multiple non-linear equations simultaneously. These equations are mainly function of the switching angles and are obtained from a type of inverter output voltage such as being unipolar, bipolar, etc. To eliminate one or more harmonics in these output voltages becomes a typical multivariate root-finding problem and its solution requires root-finding methods such as the Newton–Raphson method, the Broyden method etc. These methods can only produce a meaningful solution if initial values are properly guessed, but it is highly difficult task due to having no direct formula. In this paper, the hybrid genetic algorithm method based on the refinement of the genetic algorithms results through the Newton–Raphson method was used to simultaneously solve the non-linear equations. The results have shown a considerable effect on decrease in the total harmonic distortion, thereby increasing the efficiency of devices compared to conventional methods under the same conditions. [Copyright &y& Elsevier]

Abstract: In this paper, a cerebellar-model-articulation-controller (CMAC) neural network (NN) based control system is developed for a speed-sensorless induction motor that is driven by a space-vector pulse-width modulation (SVPWM) inverter. By analyzing the CMAC NN structure and motor model in the stationary reference frame, the motor speed can be estimated through CMAC NN. The gradient-type learning algorithm is used to train the CMAC NN online in order to provide a real-time adaptive identification of the motor speed. The CMAC NN can be viewed as a speed estimator that produces the estimated speed to the speed control loop to accomplish the speed-sensorless vector control drive. The effectiveness of the proposed CMAC speed estimator is verified by experimental results in various conditions, and the performance of the proposed control system is compared with a new neural algorithm. Accurate tracking response and superior dynamic performance can be obtained due to the powerful online learning capability of the CMAC NN. [Copyright &y& Elsevier]

Abstract: Flying capacitor multilevel inverters are increasingly used in industry applications. In order to improve the harmonic performance of the output voltage under low modulation index region, the paper presents a novel PWM method for flying capacitor multilevel inverters based on the idea of controlling freedom degree. The novel PWM method can balance the flying capacitor voltage in a certain period. The validity of the novel PWM method is demonstratedby the experimental results. [Copyright &y& Elsevier]

Abstract: This paper introduces a configuration aimed at switching losses reduction through a power leg constructed by combining a MOSFET and an IGBT. The combined use of these different switches leads to the turn-on losses reduction through the use of the faster freewheeling diode of the IGBT, and the turn-off losses reduction through use of the MOSFET’s lower losses because of the lack of tailing current, typical for IGBT’s. The introduced leg structure can be used to build single phase – full bridge invertors or three phase inverters. The proposed leg is realized, experimented and validated. [Copyright &y& Elsevier]

Abstract: This paper deals with the analyses carried out to assess the performance of the acceleration grid power supply of the ITER neutral beam injector; a model of the power supply is setup and simulations are run in both normal and anomalous operating conditions, with the aim of demonstrating the fulfilment of the requirements and to give inputs for the design of the equipments. The dynamic performance and the output voltage ripple are studied in normal operation on the basis of a conceptual design of the system; anomalous operating conditions, such as breakdown of the grids and sudden interruption of the beam current, are also analyzed and discussed. [Copyright &y& Elsevier]

Abstract: Boiling jet impingement cooling is currently being explored to cool power electronics components. In hybrid vehicles, inverters are used for DC–AC conversion. These inverters involve a number of insulated-gate bipolar transistors (IGBTs), which are used as on/off switches. The heat dissipated in these transistors can result in heat fluxes of up to 200W/cm2, which makes the thermal management problem quite important. In this paper, turbulent jet impingement involving nucleate boiling is explored numerically. The framework for these computations is the CFD code FLUENT. For nucleate boiling, the Eulerian multiphase model is used. The numerical results for boiling water and R113 jets (submerged) are validated against existing experimental data in the literature. Some representative IGBT package simulations that use R134a as the cooling fluid are also presented. [Copyright &y& Elsevier]

This paper describes a numerical approach to power-loss minimization in a fractional hp induction motor driven by a voltage-source inverter. The motor parameters are obtained from a genetic algorithm search. Optimum voltage and frequency excitations are arranged as a table for an energy-saving controller. The proposed method is useful under variable-torque load conditions. Simulation and experimental results are presented. [Copyright &y& Elsevier]

This paper proposes an optimized control approach of a Doubly-Fed Induction Motor (DFIM) based on a field weakening algorithm. This technique ensures a nearly doubled torque–speed operation region in the motor's acceleration and deceleration operation modes. The novelty of the proposed control lies in the fact of using a DFIM for Electric Vehicle (EV) applications where both stator and rotor circuits are connected to voltage source inverters controlled by Space Vector with Pulse Width Modulation (SVPWM) algorithms. Accordingly, the active power distribution law between the stator and rotor sides is thoroughly investigated. This law imposes a relationship between the rotor and stator pulsations leading to a new variation scenario in the DFIM speed. Besides, a Stator Flux Oriented Control (SFOC) is used to provide a decoupled control between the torque and the flux. Considering the voltage and current constraints in the structure, the reference flux is chosen such that the optimal torque for any operation mode, and at any given speed range, is achieved. Nevertheless, the speed measurement as well as the sensitivity to motor parameter variations remains a major limitation in the over-speed region. Therefore, a Sliding Mode Flux Observer (SMFO) is integrated into the control scheme to ensure a sensorless command. The performance of the proposed optimized control algorithm are assessed by computer numerical simulations and its effectiveness in terms of achieving maximum torque in a wide speed range is verified. [Display omitted] • Doubly-fed induction motor fed with two voltage source inverters for electric vehicle applications. • Analytical and graphical resolution based field-weakening control algorithm. • Maximum available torque and power in a wide speed range. [ABSTRACT FROM AUTHOR]

• Integrated design of heat sink considering the layout of power devices was performed. • Temperature distribution and fluid velocity filed of three heat sinks were analyzed. • Effects of fin thickness and flow rate on temperature and pressure drop was studied. • The accuracy of the numerical simulation results has been verified by the experiment. • The motor inverter with the new configuration heat sink achieves high power density. The rapid development of power electronic devices has made them have higher power density, which puts forward higher requirements for cooling technology. The contribution of this paper is the integrated design of the liquid cooled heat sink for a 30 kW motor inverter considering the distribution of power devices. In order to find an optimal heat sink configuration, the cooling performance of three different configurations of heat sinks was investigated. And the distribution characteristics of the temperature and fluid velocity field were compared and analyzed. The heat sink with serpentine channel configuration was selected due to its best temperature uniformity and cooling characteristic. In addition, the effects of geometric parameters (fin thickness) and flow parameters (flow rate) on cooling performance were further studied. On this basis, the geometrical configuration of the heat sink was optimized. The experimental results of the optimized heat sink are in good agreement with the numerical simulation results. The motor inverter achieves high power density of 9.677 kW/kg. [ABSTRACT FROM AUTHOR]

• 1, A new control method of the CFETR N-NBI accelerator grid power supply-conversion system topology is put forward. • 2, The proposed control method is based on master-slave architecture, the bottom slave is applied for rectifier and inverter, the top master is applied for AGPS. • 3, The control model of 3L-NPC rectifier and 5L-NPC/H inverterapplied for AGPS are developed. • 4, The adjustable DC-link voltage and phase-shifted carrier-pulse-width modulation are discussed, simulation results are performed that validate the new control method. The China Fusion Engineering Test Reactor (CFETR) uses a negative-ion neutral beam injection (N-NBI) system that requires a powerful acceleration grid power supply (AGPS). The AGPS is rated at -1000 kV/80 A and feeds one injector. AGPS-conversion system, which uses a three-level neutral-point-clamped active front-end rectifier as well as a five-level neutral-point-clamped / cascaded H-bridge inverter, was investigated in the reference design. Because the control problem of the conversion system is crucial for the AGPS, a well-designed control method can improve the steady-state performance during operation substantially. To achieve the full potential of the proposed design and meet the challenging demands of the CFETR N-NBI system, a new control method is proposed and investigated in this paper. Considering the requirement to provide a wide range output voltage, the new control method provides an adjustable DC-link voltage for the rectifier with unity power factor and a suitable modulation factor for the inverter, while maintaining a low ripple voltage of output voltage. The steady performance of the AGPS is successfully improved using phase-shifted carrier-pulse-width modulation. Simulation results are performed that validate the new control method. [ABSTRACT FROM AUTHOR]

This paper presents an extensive simulation-based and experimental validation of One-Cycle Control (OCC) over a nine-level power inverter using Cyclone III FPGA from Intel. OCC is a technique that exploits the nonlinear nature of multilevel power converters to overcome issues such as fast dynamic response, robustness and perturbations on either the source or the load side. Simulations performed in Modelsim demonstrate the elimination of dynamic and steady-state error between the switched output and reference signals on application of OCC. Simulink-based development and testing of the multilevel inverter model is also carried out under varying load conditions to record the reference signal, current, power factor and total harmonic distortion. The applied control scheme exhibits negligible current distortion and instability concerns when the converter is lightly loaded. Altera Quarturs II is further used for the VHDL-based implementation and experimental testing of the developed algorithm thus, validating the robustness of the control strategy. [ABSTRACT FROM AUTHOR]

• A comprehensive optimal coordination model of VPP and a novel distributed online algorithm are proposed. • The presented method significantly reduces the computational and communication complexity. • The VPP operator can generate the inventive signals based on privacy-protected measurement feedback. • Each device uses a closed-form strategy to update its setpoint locally based on currently observable information. • The optimality of the proposed algorithm is characterized and guaranteed mathematically. This paper presents a temporally coupled distributed online (TDO) algorithm to aggregate and coordinate numerous networked distributed energy resources (DERs) as a virtual power plant (VPP). A centralized stochastic optimization problem is formulated to minimize the long-term social utility loss while satisfying the voltage security, operational requirements of DERs, and VPP service requests. After that, we propose the TDO algorithm to reformulate the primary problem as an adaptation of online convex optimization (OCO). In particular, the temporally coupled constraints are well separated to each timeslot. In real-time operation, the VPP operator updates the incentives according to the measurement feedback. The smart energy gateways (SEGs) equipped at each node maximize their income and utility based on the received incentive signals through adjusting the setpoints of the governed photovoltaics (PV) inverters and electric vehicles (EVs). Unlike conventional distributed optimization algorithms where complicated iterative procedures between agents are unavoidable, the proposed TDO algorithm is computation- and communication-efficient since the SEG can directly employ the closed-form optimal setpoints without iterative communications once receiving the incentives. Furthermore, we design an incentive scheme to coordinate the SEGs based on the privacy protected nonintrusive measurements instead of direct control. Optimality and convergency of TDO are analyzed mathematically. Finally, the proposed method is corroborated numerically on a modified 33-node test feeder. A larger system is tested to validate the computational time performance. [ABSTRACT FROM AUTHOR]

Harmonic distortion is a crucial power quality (PQ) issue especially in microgrids. Distributed energy resources employ either synchronous generator or voltage source inverter to interface microsource with loads. This paper presents the analysis of the proportional resonant (PR) controller along with a selective harmonic compensator (SHC) for a stand-alone distributed generation inverter. Furthermore, a new improved triple-action controller (TAC) design is proposed and implemented. The proposed TAC consists of a conventional PR along with SHC, in addition to, a feed-forward current controller to achieve seamless sinusoidal voltage. This mitigate not only the total harmonic distortion (THD) but also individual harmonics to a level below the stated in IEEE/IEC standards. Moreover, optimize the TAC parameters to ensure its best performance. A comparative study of harmonic effects for various load-types are introduced. The voltage regulation and THD mitigation improved the power factor and efficiency, hence, it improved the PQ of the system. [ABSTRACT FROM AUTHOR]