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This paper introduces a hybrid multilevel inverter (MLI) with reduced switch count, which can generate higher output voltage level with minimum number of DC input sources. The operation of this proposed MLI is carried out with unequal DC sources to achieve the desired output voltage level. The reduced MLI output voltage is set to minimal total harmonic distortion (THD) with the help of modified JAYA (MJAYA) algorithm. A JAYA algorithm with improved steps by adopting an accelerating parameter has been proposed in this research work to obtain a faster convergence of the objective function. The MJAYA algorithm has provided the suitable switching angles for the proposed three-phase 15-level MLI and reduced the output voltage THD to 2.23%, which satisfies the standard set by IEEE-519. To prove the efficiency of this proposed modified algorithm, the comparative analysis is carried out through MATLAB program and Simulink tool using common JAYA and modified particle swarm optimisation algorithms. The performance and productivity of the proposed MLI have been investigated through simulation and experimental setups. [ABSTRACT FROM AUTHOR]

In this paper, some recently proposed multilevel power converters are investigated for their fault-tolerant capabilities and improved reliability. These reported topologies are generally reduced device multilevel inverter (RD-MLIs) configurations that cannot tolerate switch failures due to absence of redundant states. Present work therefore aims to incorporate open-circuit fault-tolerant capability by adding few redundant states in switching sequences of existing topologies. The work in this paper objectively presents two existing topologies of five-level and seven-level Multi-Level Inverters (MLIs) modified for fault-tolerant (FT) capability against single switch open-circuit (OC) faults. The modification for fault-tolerant feature (FT-MLI) has intrinsic self-voltage balancing capability, low cost and control simplicity. The modified FT-MLI uses multi-carrier sinusoidal pulse-width modulation (SPWM) technique to generate control switching pulses as per desired switching sequences. Simulation and experimental results of these modified FT-MLI topologies under healthy, faulty and post-fault mode are presented and discussed. Experimental results verify the feasibility and effectiveness of these modified FT-MLI topologies which are suitable for safety-critical applications. [ABSTRACT FROM AUTHOR]

This paper presents a finite control set model predictive control (FCS-MPC) approach for two induction machines driven by a nine-switch inverter (NSI). In the traditional approach, two separate voltage source inverters are necessary to drive the independent induction motors. In the proposed method, the nine-switch inverter is used to control the separate motors with a reduced number of switching devices compared to traditional method. A robust control strategy that eliminates the interactions between separate mechanical loads is required to achieve a proper independent speed and torque control for two induction machines through the NSI. To ensure the reliability of the machine operation, the indirect-field oriented control-based model predictive control strategy is proposed. The proposed control strategy is experimentally validated across the 3.2 kW SiC-based NSI prototype. The control algorithm is performed on an Altera Cyclone IV Field-programmable gate array. The experimental results demonstrate that the proposed dual-model predictive control method provides a good and robust motor control operation under different loading conditions. Two induction motors are successfully controlled, and the independent speed and torque control are achieved. [ABSTRACT FROM AUTHOR]

Cascaded multilevel inverters have been increasingly used in industrial applications. However, the quality of the output voltage of these inverters depends highly on the modulation techniques. One of the factors affecting the quality of the inverter output voltage is the existence of common mode voltage. This affects the life of three-phase electric motors connected to the inverter. This paper presents a method of modulating the carrier frequency for cascaded multilevel inverters to reduce common mode voltage and harmonics. In the proposed method, the carrier frequency modulator is considered an adaptive controller and the carriers are completely controlled by the control signal. Changes of control signals such as amplitude, frequency, and phase angle make the carrier frequency vary accordingly. In addition, the ability to reduce common mode voltage also helps increase the amplitude of the inverter output voltage. Moreover, an algorithm for reduction of switching commutations is also proposed to reduce the switching loss. The simulation and experiment results based on a cascaded 5-level three-phase inverter system with an induction motor load have confirmed the performance of the proposed method compared to that of the methods using unmodulated carriers through the comparison of output harmonics and number of switching commutations. [ABSTRACT FROM AUTHOR]

In this paper, Tunable Self-Oscillating Switching (TSOS) technique for Dynamic Wireless Charging (DWC) of Electric Vehicle (EV) is investigated. TSOS is a suitable option for DWC, which has parameter variation and requires fast frequency tracking. The system consists of a high-frequency full-bridge inverter, a series–series compensated loosely coupled transformer that is created by Unequal Double D (UDD) coils and a Li-Ion battery as the load that is connected to the output of the full-bridge rectifier. To achieve high efficiency and energy transfer and realise zero voltage switching, the phase of total impedance in steady state condition is investigated. To limit the overshoot of current in the system, a variable phase control method is proposed. Also, an investigation on the proper point to start the charger is performed to decrease the overshoot of current and increase the efficiency. Using this method, overshoot of current could be limited to 50% and energy efficiency could be at least 92.68%. To analyse this method, simulation is done in the Simulink/MATLAB, and to verify the results, a laboratory prototype is implemented. Abbreviations:TSOS: Tunable Self-Oscillating Switching; DWC: Dynamic Wireless Charging; EV: Electric Vehicle; DD: Double D; UDD: Unequal Double D; IPT: Inductive Power Transfer; CT: Current Transformer; MCU: Micro Controller Unit; SOS: Self-Oscillating Switching; ZVZCS: Zero Voltage and Zero Current Switching; EMI: Electromagnetic Interference; SS: Series–Series; PLL: Phase-Locked Loop; DC: Direct Current [ABSTRACT FROM AUTHOR]

Multilevel inverter (MLI) generates stepped voltage with appropriate switching combination of power devices, thus restraining the requirement of filter circuit for an efficient power conversion. MLIs are attracting due to some of the major features like economic cost, installation space, bulkiness, complexity along with its enormous applications in industries like cement factory, ceramic industry, aerospace applications etc. In this paper, a single-phase generalised inverter based on five different algorithms is proposed that uses the minimum of overall power components. The presented topology can be used in low and medium voltage applications. To verify the simulation results obtained by MATLAB/Simulink, DS1103 controller is used to generate the corresponding experimental results by developing a prototype model in the laboratory. Nevertheless, a comparative assessment for the different required components of the proposed topology is carried out with some recently developed topologies. Reduction in power switches, driver circuits and DC voltage sources reduces the size, cost, complexity and enhances the overall performance. In addition, level per switch ratio is added in this paper to decide the effectiveness of the proposed topology. [ABSTRACT FROM AUTHOR]

In this paper, modelling and hardware implementation of three-phase interleaved inverter-based shunt active power filter (SAPF) is proposed to mitigate current harmonics, reactive power for ensuring unity power factor and load balancing without shoot-through effect. Shoot-through effect is one of the hazardous issues in conventional voltage source inverters such as damage of power electronic switches, electromagnetic interference, ringing in the power circuitry. The present power system has inevitable non-linear loads which create large variations in the supply voltage distortions. Therefore, the compensation capability and efficiency of the SAPFs degrades. A novel predictive tuned filter is proposed in this paper to estimate the variations in the amplitude of supply voltage, frequency and harmonics for extracting the fundamental voltage signal. The fundamental extracted signal is further processed for reference current generation using generalized p-q theory. The performance of the proposed system is simulated using MATLAB®/Simulink environment and tested under different supply voltage conditions. The simulation results have been validated by developing a prototype in the laboratory by using a dSPACE1104 controller. It is found from the simulated and experimental results that the proposed system is fast, robust and accurate which improves the power quality without shoot-through problem. [ABSTRACT FROM AUTHOR]

Current repetitive control strategy for a 4-leg APF is usually of a poor speed in responding to the drastic changes in load harmonic profile. In this paper, a dual closed-loop current controller composed of a repetitive control-based outer loop and a PI-based inner loop is proposed to improve the performance of a 4-leg APF, with a focus on response speed and harmonic current compensation gain. The principle of the dual loop controller is explained in detail, and the stability of the system is analysed thoroughly. To further decrease the inherent time delay associated with the PWM strategy, a zero-sequence-voltage-based PWM strategy is proposed to solve the complexity in the implementation of 3D-SVPWM methods. By formulating the relationship between the duty ratio of the neutral leg control pulse and the zero-sequence-component of the reference voltages, the duty ratios of the other three legs can be calculated conveniently. The simulation and lab experiment results are provided to verify the correctness and effectiveness of the proposed dual closed-loop current controller and the zero-sequence-voltage-based PWM strategy. [ABSTRACT FROM AUTHOR]

The currently used hysteresis method is of low control accuracy, and the PWM-based strategy fails to provide a high enough response speed; thus, there is always a trade-off between the performances of control accuracy and response speed for a four-leg shunt active power filter (APF) to cope with the large variation in the load harmonic profile. First, an improved SVPWM strategy is proposed in this paper; with the aim to increase the response speed of a four-leg APF by simplifying the implementation of current 3D-SVPWM methods, the principle and realisation of this strategy are explained in detail. Based on these works, a compound PWM algorithm that effectively integrates the improved SVPWM and a PI-based current hysteresis method is proposed to simultaneously guarantee a higher response speed and a higher control accuracy for a four-leg APF. The realisation and parameter tuning of the compound PWM are elaborated. The correctness and effectiveness of the improved SVPWM and the compound PWM strategy are verified by simulations using Matlab/Simulink software. Finally, experimental results on a four-leg APF implemented in a closed-loop real-time simulation platform are presented. [ABSTRACT FROM AUTHOR]

This paper deals with space vector modulation of a Z-source 9-switch inverter for electric vehicle application. Indeed, the Z-source 9-switch inverter can supply two induction motors of two-driving wheels electric vehicle. The proposed electric vehicle powertrain composed mainly of a Z-source structure contains inductances and capacitors, and 9-switch power inverter forms two virtual three-phase inverters. So, the Z-source 9-switch inverter structure minimises the number of power switches, the volume and therefore the cost of the electric vehicle powertrain. In this context, an adapted space vector modulation of a Z-source 9-switches inverter is developed in order to ensure simultaneously an independent control of two induction motors and boost the output voltage of batteries. Experimental and simulation results have been carried out to demonstrate the effectiveness of the developed system. [ABSTRACT FROM AUTHOR]

The increased component requirement to realise multilevel inverter (MLI) fallout in a higher fault prospect due to power semiconductors. In this scenario, efficient fault detection and diagnosis (FDD) strategies to detect and locate the power semiconductor faults have to be incorporated in addition to the conventional protection systems. Even though a number of FDD methods have been introduced in the symmetrical cascaded H-bridge (CHB) MLIs, very few methods address the FDD in asymmetric CHB-MLIs. In this paper, the gate-open circuit FDD strategy in asymmetric CHB-MLI is presented. Here, a single artificial neural network (ANN) is used to detect and diagnose the fault in both binary and trinary configurations of the asymmetric CHB-MLIs. In this method, features of the output voltage of the MLIs are used as to train the ANN for FDD method. The results prove the validity of the proposed method in detecting and locating the fault in both asymmetric MLI configurations. Finally, the ANN response to the input parameter variation is also analysed to access the performance of the proposed ANN-based FDD strategy. [ABSTRACT FROM PUBLISHER]

This paper proposes a novel switching method with the neutral-point voltage control in a single-phase neutral-point-clamped three-level inverter (SP-NPCI) used in photovoltaic systems. A proposed novel switching method for the SP-NPCI improves the efficiency. The main concept is to fix the switching state of one leg. As a result, the switching loss decreases and the total efficiency is improved. In addition, it enables the maximum power-point-tracking operation to be performed by applying the proposed neutral-point voltage control algorithm. This control is implemented by modifying the reference signal. Simulation and experimental results provide verification of the performance of a novel switching method with the neutral-point voltage control. [ABSTRACT FROM AUTHOR]

In this paper, a new cascade multilevel inverter based on series connection of several basic units is proposed. The basic topology consists of 5 dc voltage sources and 12 switches. The required mathematical analysis consisting of voltage on switches, power losses and the values of dc voltage sources is provided. To verify the advantages of proposed topology, the suggested structure is compared with other multilevel inverter topologies in terms of used dc voltage sources, switches, voltage on switches and the number of on-state switches. The proposed structure uses the least numbers of dc voltage sources and switches compared to other multilevel inverters for the same number of levels. Also, voltage rating on the switches in the proposed topology is less than other topologies. These characteristics cause the weight, size and cost of proposed topology to be reduced. The proposed inverter is implemented using experimental setup. The experimental results verify the performance of proposed structure. [ABSTRACT FROM AUTHOR]

This paper presents a novel design method of bandstop filters (BSFs) and dual-band bandstop filter (DBBSF) with completely controlled bandwidth and centre frequency, high rejection levels at mid-stopband and compact sizes. First, bandstop units with simple structures are proposed. Through theoretical analysis, the centre frequency and bandwidth of the bandstop units can be independently controlled by tuning the parameters of the loaded stubs. Then, single-band, dual-band bandstop units and compact J-inverters are adopted to design the filters. Finally, to demonstrate the proposed design method, 2-order, 3-order and dual-band BSFs are fabricated and measured. From the experimental results, the maximum rejection levels at mid-stopband of 2- and 3-order are around 50 dB and 70 dB, respectively. The two stopbands of the DBBSF can be fully controlled. The measured maximum rejection levels at the two mid-stopbands are both around 60 dB. Furthermore, all the simulation and measurement show good agreement. [ABSTRACT FROM PUBLISHER]

This paper presents the design of capacitive wireless power transfer systems based on a Class-E inverter approach. The main reason for adopting the Class-E inverter approach is because of its high efficiency, theoretically 100%. However, the operation of a Class-E inverter is highly sensitive to its circuit’s parameters. In a typical capacitive wireless power transfer application, the capacitive coupling distance between plates is subject to changes, and hence its power transfer efficiency is greatly affected if the Class-E inverter is properly tuned. This drawback motivates us to develop an auto frequency tuning algorithm for a Class-E inverter which maintains its power transfer efficiency in spite of the variations of capacitive coupling distances between plates and circuit’s parameters. Finally, simulation and experiment are carried out to verify the effectiveness of the auto frequency tuning algorithm. [ABSTRACT FROM AUTHOR]

In this paper, analysis and design of fault-tolerant converter topology for direct torque-controlled (DTC) induction motor (IM) drive suitable for low, medium and high power applications is proposed. The proposed converter topology can restore normal operation of the drive after the occurrence of open-circuit or short-circuit of power switches in the inverter. It consists of a current-controlled three-level boost converter (TLBC) to boost the dc-link voltage at input terminals of an inverter during post-fault, balance the voltages at dc-link capacitors and retains all the advantages of the conventional IM drive. Simulation and experimental results are presented for pre- and post-fault operation. The results are compared with conventional fault-tolerant DTC of the drive to highlight the merits of proposed converter. [ABSTRACT FROM AUTHOR]

The topology of the energy-saving single-phase full-bridge resonant-pole soft-switching inverter is proposed to improve the power conversion efficiency of the single-phase full-bridge inverter. The auxiliary circuit is connected with the bridge arm of the inverter and contains only one auxiliary switch and a few passive devices, which is conducive to reducing the hardware cost of the auxiliary circuit and simplifying the control of the auxiliary circuit, so as to improve the reliability and practicability of the inverter. During the operating process of the inverter, the main switch and the auxiliary switch can achieve soft-switching by using the auxiliary circuit, and the energy-saving operation of the inverter can be realised by reducing the switching loss. In this paper, the operating process of the circuit and the realisation condition of the soft-switching are analysed. The experimental results on a single-phase prototype with the rated power of 3 kW show that the switching device can achieve soft-switching, and the efficiency of the prototype at the rated power reaches 98.6%, which lays a theoretical and technical foundation for the further research and development of a new practical high-performance single-phase full-bridge soft-switching inverter. [ABSTRACT FROM AUTHOR]

A proposed topology for a high-efficiency single-stage single-Phase boost inverter with a simple circuit configuration and a low component count is proposed in this paper. The proposed inverter produces instantaneous output voltages higher than the input dc voltage without an intermediate power conversion stage. A new control scheme is designed that enables the proposed inverter topology to produce a low distortion sinusoidal output waveforms and provide good load voltage regulation. The inverter circuit topology and modes of operations are fully described and simulated using Matlab/Simulink. The simulation results are presented illustrating the claimed boosting characteristics, sinusoidal output wave forms and good load regulation capability of the proposed inverter. The validity and effectiveness of the proposed inverter are verified experimentally by building a laboratory model using the digital signal processor (Model DS1104). The experimental results are presented confirming the claimed features of the inverter. [ABSTRACT FROM AUTHOR]

In this paper we propose a novel idea for the synthesis of active circuits. We deal with the use of unity gain cells (voltage followers, voltage inverters, current followers, current inverters) for the design of simulated grounded inductors, multifunction filters and oscillators. The starting point of the proposed idea is the operation on the signal-flow graphs for such synthesis. We show that, thanks to the proposed technique, a wide number of active networks can be synthesised where all used passive components are grounded. [ABSTRACT FROM PUBLISHER]

This paper presents a supervisory fuzzy neural network control (SFNNC) method for a three-phase inverter of uninterruptible power supplies (UPSs). The proposed voltage controller is comprised of a fuzzy neural network control (FNNC) term and a supervisory control term. The FNNC term is deliberately employed to estimate the uncertain terms, and the supervisory control term is designed based on the sliding mode technique to stabilise the system dynamic errors. To improve the learning capability, the FNNC term incorporates an online parameter training methodology, using the gradient descent method and Lyapunov stability theory. Besides, a linear load current observer that estimates the load currents is used to exclude the load current sensors. The proposed SFNN controller and the observer are robust to the filter inductance variations, and their stability analyses are described in detail. The experimental results obtained on a prototype UPS test bed with a TMS320F28335 DSP are presented to validate the feasibility of the proposed scheme. Verification results demonstrate that the proposed control strategy can achieve smaller steady-state error and lower total harmonic distortion when subjected to nonlinear or unbalanced loads compared to the conventional sliding mode control method. [ABSTRACT FROM PUBLISHER]

The equivalent relationship between the carrier-based modulation (CBPWM) and the space vector modulation (SVPWM) based on the flying capacitor multilevel inverters has not been analysed systematically. Due to the redundancies of the flying capacitor multilevel inverters, this paper firstly focuses on the switching sequence and the working ratio of each switching state and then proposes a novel method of decomposing modulation wave. This method can distribute the ratio of redundancies arbitrarily to satisfy the requirements of the output. Taking three- and five-level inverters as examples, by injecting a zero-sequence voltage into the CBPWM modulation wave and then decomposing the new modulation wave, we can get the same sequence of SVPWM modulation. This method takes the advantages of using simple CBPWM to realise the complex output of SVPWM, such as double- and quadruple-frequency output. At last, we deduce the equivalent relationship between the SVPWM and CBPWM in n-level with an arbitrary number of segments. Experimental results verify the correctness of the equivalent relationship. [ABSTRACT FROM AUTHOR]

This paper presents a high-levels multilevel inverter (MLI) with a reduced number of the required switches. Forty-nine levels can be obtained in the output voltage from this circuit by using only 12 semiconductor switches, while in conventional topologies of MLI, a higher number of switches is required producing a lower number of levels in the output voltage. Reduction in the number of semiconductor switches, gate drivers, DC voltage sources and increasing the number of voltage levels are advantages of the proposed MLI compared with other topologies. These advantages result in smaller size, lower loss and low installation cost. Total harmonic distortion (THD) in the output waveform of the inverter is very low, thus, using a filter to improve the output waveform is not needed. A switching pulse system has been presented to produce nearly sinusoidal waveforms. Mathematical relations and switching states of the proposed topology have been discussed. Simulation results have been obtained and studied. The prototype of the modified MLI has been built and tested in the laboratory using a dSPACE (DS1104) evaluation board in order to verify the simulation results. Several of the experimental results of the proposed topology have been included and discussed. [ABSTRACT FROM AUTHOR]

This paper presents a direct model-based predictive control scheme for voltage source inverters (VSIs) with reduced common-mode voltages (CMVs). The developed method directly finds optimal vectors without using repetitive calculation of a cost function. To adjust output currents with the CMVs in the range of –Vdc/6 to +Vdc/6, the developed method uses voltage vectors, as finite control resources, excluding zero voltage vectors which produce the CMVs in the VSI within ±Vdc/2. In a model-based predictive control (MPC), not using zero voltage vectors increases the output current ripples and the current errors. To alleviate these problems, the developed method uses two non-zero voltage vectors in one sampling step. In addition, the voltage vectors scheduled to be used are directly selected at every sampling step once the developed method calculates the future reference voltage vector, saving the efforts of repeatedly calculating the cost function. And the two non-zero voltage vectors are optimally allocated to make the output current approach the reference current as close as possible. Thus, low CMV, rapid current-following capability and sufficient output current ripple performance are attained by the developed method. The results of a simulation and an experiment verify the effectiveness of the developed method. [ABSTRACT FROM PUBLISHER]

Nine-switch inverter with two sets of three-phase outputs is an improved topology proposed in place of the 12-switch back-to-back converters and has therefore attracted much attention in recent years. This inverter can be used with two conventional pulse width modulation approaches: different frequency and the constant frequency. One disadvantage of using this modulation method is the possibility of short-circuits in the legs (shoot-through), which decreases the reliability of converter and system. This paper presents a new modulation technique, in which switching pulses of nine-switch inverter are produced by not only the original carrier signals but also through two auxiliary carrier signals. In this method, adjustable three-phase voltages are produced in the inverter’s terminals, and so there is no possibility of any shoot-through in the inverter’s legs. The suggested reliable modulation approach does not rely on any information about the load polarity, as switching is performed by a simple and reliable algorithm. The result is the considerably better waveform quality of the output voltages in comparison with other methods. To verify the analysis, an experimental platform based on DSP is built. The simulation and experimental results are given to demonstrate the effectiveness and feasibility of this new approach. [ABSTRACT FROM AUTHOR]

This paper deals with fast-scale non-linear distortion behaviours including asymmetrical period-doubling bifurcation and zero-crossing distortion in peak-current-controlled buck–boost inverters. The underlying mechanisms of the fast-scale non-linear distortion behaviours in inverters are revealed. The folded bifurcation diagram is presented to analyse the asymmetrical phenomenon of fast-scale period-doubling bifurcation. In view of the effect of phase shift and current ripple, the analytical expressions for one pair of critical phase angles are derived by using the design-oriented geometrical current approach. It is shown that the phase shift between inductor current and capacitor voltage should be responsible for the zero-crossing distortion phenomenon. These results obtained here are useful to optimise the circuit design and improve the circuit performance. [ABSTRACT FROM AUTHOR]

This paper proposed a novel three-phase single-capacitor Z-source inverter (SC-ZSI) topology and a one-cycle control (OCC) method for three-phase SC-ZSI. It uses a unique single-capacitor Z-source impedance network for boosting its output voltage. Comparing with SL-ZSI and SL-qZSI, the proposed SC-ZSI reduces capacitor voltage stress and inductor current stress with the same boost factor. Comparing with L-ZSI, SL-ZSI, and SL-qZSI, the proposed SC-ZSI can provide a high boost factor with a small shoot-through duty ratio. A novel OCC method for three-phase SC-ZSI with unity-power-factor correction is proposed. The method is composed of two parts and described in detail. One part is the OCC for DC link voltage, and the other part is three-phase AC voltage OCC based on SVPWM. The simulation and experimental results show that the topology of SC-ZSI is correct and the OCC for SC-ZSI is effective. [ABSTRACT FROM AUTHOR]

In this paper, an enhanced Z-source inverter (ZSI) is introduced for controlling the speed of permanent magnet brushless DC motor (PMBLDCM) drive. It is the extension of the conventional ZSI and the elements used in the circuit are the same as those of the conventional ZSI, except that the position of Inverter Bridge and diode would be exchanged from the classical circuit diagram. This exchanged circuit avoids the startup path of the inrush current and hence reduces the inrush current and improves the motor efficiency. Different modes of enhanced ZSI are studied with PMBLDCM. The voltage polarity of Z-source capacitors in the proposed circuit is the same as that of the input voltage polarity. Furthermore, to get the same voltage boost, the capacitor voltage stress is reduced to a significant extent. The speed control capability of the proposed brushless DC motor drive is compared with that of the conventional ZSI. The proposed ZSI is implemented in MATLAB/Simulink working platform and the output performance is evaluated. Also, the performance of voltage ratio is analysed both by simulation and mathematical models. All these analyses are known to express the innovative features of the proposed system. [ABSTRACT FROM PUBLISHER]

The design of a voltage source inverter (VSI) control system requires knowledge about its continuous or discrete model. The output filter inductance and the equivalent serial resistance, which is partly the result of power losses in the core, have values at the operating point that are significantly different from the assigned nominal values, particularly for iron-powder cores. Measurements using standard laboratory equipment are not sufficient because it is impossible to get the voltage and current of the operating point. So the best solution is to measure the Bode plots of the inverter control function at the operating point, to estimate the results of the measurements using the proper analytic function and to calculate the real values of the inverter parameters. Knowledge about the equivalent serial resistance enables the estimation of the inverter power losses. Two approaches to measurements are shown – one that does not require any additional equipment and the other that uses a specialised system to automatically measure the Bode plots. The advantages and disadvantages of both approaches are presented. These measurements enable the validation of the coil core magnetic material by taking into account the power losses. The applications of the measurements in the control design are shown. [ABSTRACT FROM AUTHOR]

A novel topology of the modular multilevel inverter with the ability to boost the input voltage is proposed in this work. The proposed single-source structure requires neither any external controller nor transformers to balance the voltages of the capacitors. In addition, the output voltage polarity of the inverter is generated inherently with a low switching frequency, making it suitable for both residential and industrial applications. The Nearest Level Modulation (NLM) is applied to control the operation of the inverter. The detailed comparative analysis of the proposed inverter with other inverters indicates that the proposed structure can produce similar voltage levels with a fewer number of elements and less voltage stresses. Moreover, to verify the performance of the proposed converter, a single-phase 13-level prototype was implemented in the laboratory environment and the test results were compared to the simulation ones. The advantages of low harmonic contents with Total Harmonic Distortion (THD) of 6.5% and 92.69% efficiency make the proposed inverter appropriate for applications with a limited number of low voltage sources. [ABSTRACT FROM AUTHOR]

Due to the distortion of air gap magnetic field and the inherent non-linear characteristics of the inverter, the stator current of permanent magnet synchronous motor (PMSM) contains a large number of high order harmonic components, which distorts the current waveform and generates torque ripple, limiting the application of the PMSM in high speed and precision situations. To solve this problem, a harmonic current suppression method is proposed based on synchronous rotating coordinate transformation theory and adaptive filtering algorithm. The PMSM harmonic mathematical model is established and the coordinate transformation method is used to extract the 5th and 7th harmonic currents. On the basis of the original double closed-loop control system, the harmonic current loop is added, and the harmonic components are suppressed by injecting harmonic voltages. In order to improve the filtering effect and reduce the harmonic content, an adaptive filter is designed to replace the conventional low pass filter in the process of harmonic current extraction. According to the results of coordinate transformation, the adaptive filter continuously adjusts the parameters online through the least mean square (LMS) algorithm to extract the harmonic current. The simulation and experimental results proved the correctness and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This work introduces a new passive filter structure for a pulse width modulated inverter used in standalone applications. The proposed structure consists of an additional capacitor connected across the resistance-capacitance branch of the traditional LCR filter and an additional resistor connected across the trap filter capacitor in the traditional (LC)trap-LCR filter configuration which helps to reduce damping power loss and increase harmonic attenuation while maintaining the same overall filter size of conventional filters. A comprehensive parameter design procedure of the proposed filter is introduced which considers inverter switching frequency and choice of damping components. Further, particle swarm optimisation algorithm is newly employed in this work to minimise resonant peaking on the premise of allowable values of overall filter inductance, capacitance and resistance. Simulation and experimental results are presented to analyse the performance of the proposed filter and a comparison is established with other passive filter topologies. A five-level inverter with the proposed filter is implemented using a SPARTAN- 6 XC6SLX25 processor on an experimental set-up. The experimental results show an attractive performance of the proposed filter in providing improved inverter output waveforms, significant harmonic reduction in the high-frequency band, reduced resonant peaking, lesser harmonic distortion and lower damping power loss. [ABSTRACT FROM AUTHOR]

In the last decade, the impedance source networks have been vastly used in electrical power conversion such as in electric vehicles, industrial machines, medical systems and avionics, with considerable efficiency improvements. In this study, two new impedance source network topologies for inverter applications have been designed and tested. The first one is a one-cell switched inductor (SL), the second is a two-cell switched inductor (X-SL) combined with the classical Z-source inverter (ZSI). This novel combination allows the switched inductor to store the unused source energy in the interval when the source separates from the ZSI network during the shoot-through zero state. The design is generalised by adding multiple branches of series inductors and diodes which further improve the circuit performance. The National Instrument Multisim programme is used for the simulations of the new topologies. Both of the proposed topologies, SL combined with classical ZSI (SL&ZSI) and X-SL combined with classical ZSI (X-SL&ZSI), are tested with specific inductance and capacitance values. Major improvements are observed in the boost factor and the elimination of the start-up inrush current for both topologies, compared to the classical ZSI scheme. Furthermore, in both topologies, a significant reduction in the capacitor stress levels is obtained. [ABSTRACT FROM AUTHOR]

In this article, a new low-power multiple-input, single-output (MISO) multi-mode universal biquad operational transconductance amplifier-capacitor (OTA-C) filter with a minimum number of active and passive components is proposed. The proposed filter employs three OTAs, one inverter and two grounded capacitors. The proposed filter can realise all filter frequency responses including low-pass (LP), band-pass (BP), high-pass (HP), band-stop (BS) and all-pass (AP) in all operation modes including voltage, current, tranasresistance and transconductance modes using the same topology. Furthermore, sensitivity analysis is done which shows that the proposed filter has a low sensitivity to the values of the active and passive elements. The proposed filter is simulated in HSPICE using 0.18 µm CMOS technology. The HSPICE simulation results demonstrate that the proposed filter consumes only 35 μW at 2.5 MHz from a ±0.5 V supply voltage, while all of the transistors are biased in strong inversion region. Also, the simulation results are in a close agreement with the theoretical analysis which is done in MATLAB. Furthermore, the process, voltage and temperature variation simulations are done to study the effect of non-idealities on the performance of the proposed filter. It is shown that the simulation results justify a 4.8%, 0.8% and 20% variations of the centre frequency for process, voltage and temperature, respectively. Finally, Monte-Carlo, noise and transient simulations are done to justify the good performance of the proposed filter performance. [ABSTRACT FROM AUTHOR]

This study puts forward an efficient unit cell to be taken in use in multilevel inverter assemblies. The proposed structure is in line with reductions in number of direct current (dc) voltage sources, insulated-gate bipolar transistors (IGBTs), gate driver circuits, installation area, and hence the implementation costs. Such structural savings do not sacrifice the technical performance of the proposed design wherein an increased number of output voltage levels is attained, interestingly. Targeting a techno-economic characteristic, the contemplated structure is included as the key unit of cascaded multilevel inverters. Such extensions require development of applicable design procedures. To this end, two efficient strategies are elaborated to determine the magnitudes of input dc voltage sources. As well, an optimisation process is developed to explore the optimal allocation of different parameters in overall performance of the proposed inverter. These parameters are investigated as the number of IGBTs, dc sources, diodes, and overall blocked voltage on switches. In the lights of these characteristics, a comprehensive analysis is established to compare the proposed design with the conventional and recently developed structures. Detailed simulation and experimental studies are conducted to assess the performance of the proposed design. The obtained results are discussed in depth. [ABSTRACT FROM PUBLISHER]

This article presents a novel control strategy for a 1-ϕ 2-level grid-tie photovoltaic (PV) inverter to enhance the power quality (PQ) of a PV distributed generation (PVDG) system. The objective is to obtain the maximum benefits from the grid-tie PV inverter by introducing current harmonics as well as reactive power compensation schemes in its control strategy, thereby controlling the PV inverter to achieve multiple functions in the PVDG system such as: (1) active power flow control between the PV inverter and the grid, (2) reactive power compensation, and (3) grid current harmonics compensation. A PQ enhancement controller (PQEC) has been designed to achieve the aforementioned objectives. The issue of underutilisation of the PV inverter in nighttime has also been addressed in this article and for the optimal use of the system; the PV inverter is used as a shunt active power filter in nighttime. A prototype model of the proposed system is developed in the laboratory, to validate the effectiveness of the control scheme, and is tested with the help of the dSPACE DS1104 platform. [ABSTRACT FROM AUTHOR]

This article proposes a direct approach for the prediction of inverter efficiency using MATLAB/Simulink, instead of an indirect loss calculation approach based on analytical models. In analytical approach, efficiency is obtained by calculating individual losses separately, such as switching losses, conduction losses and harmonic losses using analytical models. However, this approach requires accurate analytical models and complicated calculations, due to the variation in the switching frequency, switching transient and modulation techniques. In the proposed approach, the actual waveform of the inverter system is directly generated using MATLAB/Simulink. The instantaneous voltage and current waveform including switching transients are generated. Thus, the proposed approach is very simple and convenient for efficiency prediction. The proposed approach also works for any system parameters or control methods, such as various pulse-width modulation (PWM) techniques, different switching frequencies, switching devices and load types. The proposed approach can be adopted for the efficiency prediction of any switching strategies and any types of inverters such as neutral-point-clamped (NPC) inverters, H bridge inverters and H5 topology, since the topologies are modelled as circuits in the MATLAB/Simulink program and no analytical model is required for the proposed approach. Furthermore, the proposed approach can provide operation techniques and conditions such as PWM techniques and switching frequency that offer high efficiency. In this article, inverter performance is evaluated for various PWM techniques and switching frequencies. The PWM technique and switching frequency that offer high efficiency is obtained. Finally, the proposed approach is verified by experimental results. [ABSTRACT FROM PUBLISHER]

For improving the alteration performance of multilevel inverter, selective harmonics elimination methods play a significant role. In this document, an incorporated method is suggested for removing the harmonics of multilevel inverter with uneven DC sources. The suggested incorporated method is the mixture of fuzzy logic intelligent system and particle swarm optimisation (PSO) algorithm. For generating the training information set in terms of switching angle, Fuzzy is one of the synthetic intelligent methods which apply harmonic voltage and harmonic distortion. PSO is one of the swarm intelligence-based optimisation algorithms which is employed for choosing optimal switching angle from the training data set. The suggested hybrid method is executed in MATLAB/Simulink platform. At dissimilar unequal input voltage levels, the performance of the suggested method is checked by cascade H-bridge multilevel inverter. The production of the suggested method is compared with the theoretical effects. [ABSTRACT FROM AUTHOR]