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Featured with the simple structure, V-clamp multilevel converter (VMC) shows good prospect in the high-voltage and high-power applications. But VMC is endangered by the deviation of dc-link capacitors voltage, especially under the high modulation index (MI) and high power factor (PF) condition. Thus, a voltage balancing strategy for three-phase seven-level VMC is proposed in this paper. This strategy re-designs the carriers and reference to achieve capacitors voltage balancing with reduced switching actions. Besides, an active compensation control for capacitors voltage is presented to improve the dynamic performance. Compared with the conventional virtual space vector modulation, the proposed strategy significantly reduces the switching loss while provides a better output voltage under the high MI and high PF condition. The simulation model and experimental prototype of VMC with 7.2kW/220V are constructed to verify the validity of the proposed strategy.

This paper introduces an advanced space vector modulation technique for three-level neutral-point-clamped (3L-NPC) converters. The studied 3L-NPC converters within aircraft electric starter generator (ESG) systems normally operate at high modulation index, low pulse ratio and full power factor range for most of the operation time. Conventional modulation techniques exhibit large neutral point voltage ripple and possible voltage imbalance under such conditions. The increase of neutral point voltage ripple implies significant increase in converter capacitor size and decrease in capacitor reliability. The modulation technique introduced in this paper achieves improved neutral point voltage balancing within each switching period through enhanced applications of small vectors and restriction on medium vectors. The advanced implementation of small vectors is achieved using a sharing factor aided by a robust incremental current prediction procedure. With the predicted machine currents, the proposed method enables the optimum application of small vectors to balance the neutral point voltages. Simulation results based on a PLECS/Simulink model and experimental results obtained from a 45kVA, 32krpm aircraft electric starter generator prototype platform validate the reduction of the neutral point voltage ripple.

The Neutral Point Clamped (NPC) Multi-Level Inverters (MLI) have been ruling the power electronics industries for the past two decades. The Multi-Carrier Pulse Width Modulation (MCPWM) is common PWM techniques which are widely used in NPC-MLI applications. However, MCPWM is not having a good impact on the balancing of DC-link voltages, Common Mode Voltage (CMV) and limiting the Total Harmonics Distortion (THD). The Selective Harmonic Elimination (SHE) technique is introduced for reducing the THD, however all the switching angles should be maintained less than $\pi $ /2 to keep the eliminated harmonics at constant level which narrows down the modulation index range. Hence, in recent days Space Vector Modulation (SVM) technique is widely used in NPC-MLI, which gives better DC-link voltage balancing, self-neutral point balancing, near-zero CMV reduction, better-quality harmonics profile and switching loss minimization. Hence, it is a preferred solution for the majority of electrical conversion applications such as electric traction, high power industrial drives, renewable power generation, and grid-connected inverters, etc. The paper gives a comprehensive review of the SVM for NPC-MLI. First, this paper deliberates the state of art for two-level SVM and extends it to three-level (3L) SVM. Also compares the 3L SVM performance with other MCPWM techniques. Followed by the various modified MLI SVM techniques in terms of their implementations, DC-link capacitor balancing, and reduction of CMV. Further, the review of MLI SVM is widened to open-end winding Inverters and multiphase MLIs. The final part of this paper discussed the future trends and research directions on MLI SVM techniques and its applications.

Cascaded H-Bridges Multilevel Inverters are an innovative and promising solution in different application fields. This topology allows obtaining an improvement in the performance (e.g. reduced harmonic content, the low voltage stress on power components, and high efficiency) in respect to the traditional two-level inverters. In this context, the Multicarrier-PWM strategies play an important role thanks to their features. This paper presents an experimental investigation on the performance of a three-phase five-level Cascaded H-Bridge inverter by using different PWM modulation strategies. In particular, the paper is focused on the experimental validation of the main features of Multicarrier PWM taken into account by varying the modulation index and the switching frequency.

A 21-concentric 42-sided polygonal space vector structure (SVS) for suppression of lower order harmonics for Open-End Induction Motor drive applications is proposed in this work. The Open-End Induction Motor is fed with primary and secondary inverters from either side. The primary inverter providing active power for motor operation is fed with an active DC link. The primary inverter is switched at low switching frequency to minimize stress on high voltage switching devices. As a result, the primary inverter consists of lower order harmonics in the pole voltage. The secondary inverter is employed only to suppress the harmonics generated by primary inverter and does not contribute any active power for motoring operation. Hence, the secondary inverter can be fed with a capacitive supply balanced at a nominal voltage. The secondary inverter, operating at lower voltages is switched with high frequency to suppress the lower order harmonics upto 39th order in the motor phase voltage. The advantages of polygonal space vector structures are retained throughout the modulation index, by generating 21-concentric layers of 42-sided polygons. This results in lower switching losses in low frequency switching main inverter and low voltage secondary inverter. A single DC link is employed in the power circuit topology to facilitate four-quadrant operation of the inverter. The proposed scheme is tested in MATLAB simulations and laboratory prototype. The simulation and experimental results are presented.

This paper presents a comparison of the efficiency and computational complexity of successive interference cancellation (SIC) and ordered successive interference cancellation (OSIC) detectors in massive MIMO systems using QAM modulation. The challenge for the signal detectors of these systems is that as the number of antennas increases the detector complexity also increases. Therefore, so is important to have an efficient low-complexity detector. These four detectors are evaluated in a system of 16 antennas in transmission, 64, 100 and 200 antennas in reception using 4 QAM, 16 QAM, and 64QAM modulators, to evaluate the efficiency and computational complexity of each detector by increasing the number of receiving antennas and with different QAM modulation. With the result that increasing the number of antennas and decreasing the modulation index improves the performance of the system, since the higher the gain, the lower the probability of signal loss. The evaluation of the detectors in these systems shows that the OSIC detectors present better performance but have greater computational complexity.

This paper demonstrating a successful photonics generation of 60GHz millimeter-wave by quadrupling a 15GHz RF signal with an unbalanced Mach-Zehnder modulator (UMZM). With a 4ps delay between the two arms of UMZM and by controlling the modulation index of UMZM, only two side bands can be generated along with the main carrier, which is suppressed by a band pass filter. Hence, a millimeter-wave of 60GHz is generated with a total suppression of undesired low/high-order harmonics. Moreover, an optical comb with spacing of 30GHz is generated using a cascade of intensity and phase modulators and utilized for an optical wavelength-division multiplexing (WDM) transmission system at data rate of 5Gbps for each user. Results show that the system maintains good bit error rate performance up to a receiver sensitivity of −22dBm.

Common-mode voltage (CMV) is one of the major concerns in modern motor drive techniques. To alleviate the CMV issue, a series of different pulse width modulation (PWM) methods have been proposed, which are particularly effective when the motor phases have even numbers, such as six phases. This paper proposes a new modulation method based on the traditional sinusoidal PWM (SPWM) to fully eliminate the CMV in a dual-three-phase motor drive system, thereby helps the sizing shrinking of the CM choke. Both mathematical models and experiments indicate its effectiveness in the full linearity range of the modulation index. Such a method has been implemented in the field-programmable gate array (FPGA) to widen its control bandwidth.

This paper proposes a multioutput hybrid bipolar converter (MOHBC) and a different operational approach for achieving maximum power point tracking (MPPT) operation for photovoltaic systems. The proposed MOHBC simultaneously provides bipolar DC (inverted and non-inverted) and AC outputs and is designed by the integration of Cuk and SEPIC converters with some circuit modifications. For the proposed MOHBC, two control parameters; the duty ratio d and the modulation index $m_{\mathrm{a}}$ are used to control the bipolar DC and AC output, respectively. The MPPT operation is achieved by controlling d and $m_{\mathrm{a}}$ in four different operating modes of the proposed MOHBC. The steady-state and transient response of the proposed MOHBC during the MPPT operation in four different modes are verified using PSIM. Finally, a comparative analysis of MPPT operation in the different modes is carried out in this work.

In Modular Multilevel Converter (MMC), submodule capacitor value determines the overall cost, size, and weight of the converter. Minimizing the submodule capacitance value without increase in the voltage ripple is a challenge. Injecting the Second Harmonic line frequency component in Circulating Current(SHCC) is a well-explored idea to reduce the voltage ripple in the submodule capacitors. In this paper, this idea is extended to MMCs operating in the over-modulation range. Optimization plots corresponding to SHCC amplitude at any given modulation index to achieve the minimum possible submodule capacitor voltage ripple are presented. From these plots, the most optimal operating point is identified at which the requirement for the submodule capacitance reduces to 15.2% of the conventional operation(unity modulation index, zero SHCC). The price for this remarkable improvement is paid by the slight increase in conduction losses as the SHCC injection increases the arm current rms value. Wide range of modulation indices and SHCC injection indices are considered to obtain different optimal points for different requirements which are presented in detail.

The alternate arm converter (AAC) is being considered as a potential alternative for MMC in HVDC applications because of lower energy storage requirement and dc-fault tolerant capability. However, to achieve energy balancing over wide range of operating modulation indices, it requires a dedicated controller that needs to exchange the unbalanced energies between the upper and lower arms of each phase-leg to achieve the balancing of its SMs capacitor voltages. In this paper, a new control scheme is proposed for AAC to balance its SMs capacitor voltages. The proposed scheme is based on the constant overlap-time and the magnitude of current during overlap-time is varied depending on the operating modulation index and power-factor. As the overlap-time is kept constant in the proposed control scheme, the operation of AAC can be extended to higher modulation range without increasing the number of SMs per arm. A detailed analysis of arm energy in AAC is presented to determine the required magnitude of current to be injected during the overlap for energy balancing. The efficacy of the analysis and the control scheme is verified using simulation and experimental studies on a scaled down laboratory prototype.

A current-source inverter (CSI) has a natural output voltage boost feature that can be advantageous for traction applications. Switching frequency is one of the easily-controlled variables that can be adjusted to improve the CSI efficiency at different operating points when the boost function is used. This paper investigates a CSI-based double-pulse test (DPT) measurement that mimics normal operation of the CSI. A loss model of the CSI is developed based on the CSI-type DPT experimental results. The impacts of the switching frequency and voltage boost ratio on the CSI efficiency and output voltage ripple are investigated. Based on the loss model, a genetic algorithm has been introduced that makes it possible to optimize the CSI's switching frequency and modulation index to maximize its efficiency under any desired operating condition.

Hybrid modular multilevel converter (Hyb-MMC) consisting of a mix of half bridge (HB) and full bridge (FB) submodules (SMs) has emerged as a topology capable of handling reduced dc voltage conditions without causing large increase in capital cost and losses. However, successful application of Hyb-MMC requires suitable modulation schemes that can establish stable operation. The challenge intensifies in cases of reduced dc voltage operation where the modulation index reaches values much higher than unity. This work proposes a method in which the arm voltage reference is divided between the HB and FB SMs such that the energy balance for both the groups (HB and FB) are maintained independently. The mathematical basis of the method of division of the arm voltage reference has been derived and the upper limit of modulation index for stable operation with the proposed strategy is computed. The method is tested by applying it on a Hyb-MMC simulation in EMTDC/PSCAD platform.

Three-level neutral-point clamped inverter (3LNPCI) is a widely popular topology in the realm of multi-level inverters. The low frequency third-harmonic neutral-point (NP) current in a 3L-NPCI and the corresponding NP-voltage oscillations on the DC-side are known characteristics of the 3L-inverter. In this paper, a quantitative analysis is presented for characterizing the DC-side third-harmonic phenomena observed in 3LNPCI. Departing from the traditional space-vector perspective, an alternate formulation based on time-domain functions and Fourier-series is adopted, and an analytical expression for the 3rd harmonic NP-current is derived as a function of inverter modulation index and load power factor–this is applicable for all conventional carrier-based PWM techniques employed on 3LNPCIs. The corresponding NP-voltage variation on the DC-side and its translation onto the AC-side as low-frequency harmonic distortions in the inverter output voltage are analytically quantified. Based on this, a model-based observer is designed to mitigate the AC side distortions through accurate estimation of the disturbance variables and feed-forward cancellation. Experimental results along with a full-order switched model simulation of a three-phase 3L-NPCI system validate the theoretical analysis and mitigation technique proposed in this paper.

Due to the employment of three-level neutral-point-clamped (3L-NPC) converters in the aircraft electric starter/generator (ESG) systems, the pulse-width-modulation (PWM) strategy plays a significant role in the converter-fed PMSM drives. However, the studied ESG system operates under a high modulation index and low power factor conditions during generation mode. It means the neutral-point (NP) voltage imbalance issue will become aggravated. Regarding the reliability and efficiency of high-speed motors, reduced common-mode voltage (CMV) is favorable for the lifetime of bearing insulation. Also, a definite aircraft DC-bus voltage of 270VDC causes deep flux-weakening currents when the machine operates at a high-speed. Additionally, the applied modulation scheme desires short execution-time for the purpose of algorithmic-efficiency. In this paper, a high-performance PWM strategy is proposed to achieve a higher DC-link voltage utilization, CMV reduction, capacitor voltage balance and simple implementation at the same time.

Impedance-source inverters (ZSIs) are getting more popular in renewable energy generation over conventional inverters due to their inherent boosting characteristic and shoot-through invulnerability. However, most of the ZSI expansion abilities are somehow restricted by the component stresses and inferior performance, particularly at extreme duty operation. This paper presents a class of series switched quasi impedance-source inverters (SS-qZSIs). The introduced inverters offer superior boosting ability with a bit higher modulation index, and low voltage stresses on the capacitors ensuring reduced size, weight, cost, and improved power density. The working principle, steady-state analysis, and the design procedures for selecting circuit parameters are addressed. The inductor current ripple can be improved with enhanced boosting by proper control of the boost-network active switch. A full comparison with similar topologies is also presented. The features offered are more suitable for power generation from intermittent renewable sources like solar photovoltaic and fuel cell systems. MATLA simulation and experimental testing results are provided for the validation of proposed theory.

Pulse width modulation (PWM) methods are important for the detection performance of a sound navigation and ranging (sonar) system because they determine the output noise of the system. However, only few studies have been conducted on PWM methods for reducing harmonics of a sonar system. In this study, we propose a discontinuous pulse width modulation (DPWM) method for three-leg two-phase (3L2P) inverters. Further, we derive a complete harmonic solution for a double-variable-controlled waveform for the proposed DPWM and conventional continuous pulse width modulation (CPWM) methods. Using these harmonic solutions, we analyze the normalized weighted total harmonic distortion (NWTHD) characteristics according to the modulation index (MI) of the inverter and phase difference of the output voltage for each method. Further, based on the results, we present a superiority map between the conventional CPWM and proposed DPWM methods in terms of the NWTHD. An NWTHD measurement experiment was performed to verify the proposed method. The experiment included additional evaluations of switch losses, phase difference variability, and voltage utilization, which are important factors for sonar systems. This is because improving only NWTHD performance while other factors degrade is not very useful. The results of the experiment confirm that the NWTHD for the proposed DPWM method was 92.5% of that for the conventional CPWM method. We confirm that the mean error of the NWTHD between the analytical and experimental values under similar conditions was less than ~2.2%. In addition, it was verified that the important factors, except NWTHD, were the same throughout additional experiments. Therefore, if the CPWM or DPWM method is selected based on the proposed selection criteria, realizing advantageous operation in terms of the NWTHD is possible.

This paper proposes open fault diagnosis and tolerance control methods for grid-connected hybrid active neutral-point-clamped (ANPC) inverters with optimized carrier-based pulse width modulation. The hybrid ANPC inverter is composed of silicon carbide metal-oxide-semiconductor field effect transistors and Si-insulated gate bipolar transistors. Open faults of switch devices lead to the distortion of output currents, inverter performance degradation, and low reliability. Therefore, the open-circuit fault diagnosis and the tolerance control methods should be handled to improve the reliability of the inverter. The fault tolerance control methods for grid-connected inverters should also consider the fixed voltage modulation index as the modulation index is fixed. In this study, the proposed fault tolerance control method handles the open fault without reducing the modulation index. The implementation of the proposed method is easy and can be conducted through a simple change in the reference waveform. The effectiveness of the proposed fault detection and fault tolerance control methods was verified through the simulation and experimental results.

In recent years, T-type three-level inverter (TLI) has attracted attentions due to its advantages, such as simple structure and higher efficiency. Neutral point voltage (NPV) is very critical for its normal operation, and the necessary conditions of maintaining NPV balance respectively in a switching cycle and in a fundamental cycle are simply reviewed in this paper. With the increment of power switches, the reliability of T-type TLI becomes particularly important. When switch faults occur, fault-tolerant control strategies are usually adopted. However, in existing literatures, it is unknown whether the NPV balance can be still maintained under different fault types. Therefore, the application range of a fault-tolerant control is also unknown. In this paper, based on the necessary conditions of maintaining NPV balance, the application ranges of two representative fault-tolerant control strategies are revealed under different open-circuit (OC) fault types in inner switch. It found that the application ranges are closely related to the modulation index, load power factor (PF) and OC fault type. Finally, the correctness of the theoretical analysis is verified by the experimental results.

This paper proposes a systematic design procedure with comprehensive consideration of the internal and external dynamics in modular multilevel converter high voltage direct current (MMC-HVDC) transmission system. Previous studies on MMC parameter selection separately deal with each specific component such as energy storage capacity for voltage ripple of sub-module (SM) capacitor, arm inductance for second harmonic circulating current reduction, maximum allowable modulation index for MMC operating condition, which considered only a single purpose. However, the parameters respond dynamically to their characteristics and interact directly with the MMC performance, power system conditions, and specific requirements. In this study, we investigate the mutual relationships between the parameters and their performance. Then, we determine the parameter values based on a proposed systematic design procedure with the desired objectives and restricted conditions, which could be cumbersome and time-consuming to approach proper and acceptable parameter values. Therefore, this study could provide engineering evaluations and insights to help MMC-HVDC system engineers and project developers in intuitive approaches regarding the design aspects of the technology requirement challenges. The efficacy and accuracy of the analysis and design method for the MMC-HVDC system parameters were validated by PSCAD/EMTDC time-domain simulation and real-time digital simulation with hardware-in-loop system.

The multilevel inverter is a power electronic circuit that can give output voltage with multiple levels and be worked in inverter or rectifier mode. It is a highly efficient technique for DC to AC power conversion in solar photovoltaic systems due to its low total harmonic distortion (THD), low switching loss, low electromagnetic distortion for medium voltage and high-power applications. This paper describes a newly effective topology which has only eighteen switches, six voltage sources and six power diodes for three phase seven level inverter. For the controlling process of multilevel inverter different phase disposed carrier wave modulations are used. The aim is to thoroughly investigate and evaluate some optimum conditional points for these control techniques based on which proposed inverter will be more feasible and efficient. The effectiveness of the proposed system has been verified through simulation analysis in the MATLAB/Simulink software environment. From the simulation, it is observed that the proposed topology reduces the number of switches, voltage sources and power diodes among existing topologies. Based on the simulation result, it is also observed that the optimum modulation index and carrier frequency for PODSPWM are 1.10 and 1000Hz and for PODTRPWM are 1.10 and 1000Hz and for PODSDPWM are 1.0 and 1000Hz and also for PODTHPWM is 1.0 and 1000Hz and PODTRPWM offers better result in terms of THDs and PODSDPWM offers less switching losses among different topologies. The proposed asymmetric multilevel inverter offers less amount of switching devices. Besides, the efficiency of the inverter is increased due to minimum switching loss as well as reduced overall system installation cost.

This paper gives an insight on the simulative and theoretical analysis of the Optical Single Sideband(OSSB) with 90° and 120° phase shift using Mach Zehnder Modulator(MZM) and Optical Vestigial Sideband(OVSB) modulation techniques. It considers the issue of Chromatic Dispersion(CD) in Single Mode Fibers(SMF) and Non-Linearity of the transmitter system due to the presence of second and higher-order sidebands. The ubiquity of second and higher-order harmonics degrades the nature of signal in long-haul transmissions. The RF signal at the intake of MZM is divided equally with the help of an electrical hybrid coupler providing the phase shift of 90° and 120° to generate the OSSB. Whereas, the RF signal at the input of MZM with 90° phase shift passed through Fiber Bragg Grating(FBG) filter is used to generate OVSB. The 2nd and higher-order sidebands generated are due to the non-linearity of the MZM relying on the modulation index. It was observed that suppression of higher-order sidebands with an increase in Extinction Ratio. This work is evaluated on the basis of the extinction ratio of MZM, modulation index, and received RF power. The OSSB with 120° phase shift suppresses the second and higher-order sidebands which diminish the effect of chromatic dispersion resulting in the good long-haul transmission system.

The present paper represents the analysis of effect of modulation Index on performance of Single phase front end converter by varying the modulation index. The front end converter is basically AC to DC converter. The developed mathematical model is converter in Simulink model. These front end converter simulink model is simulated on MATLAB-Simulink using different value of modulation index. The effects of variation in modulation index is reflected in %THD, overshoot and under shoot, and stability. Pulse Width Modulation techniques are basically used to reduce the average delivered power so that energy can be saved. Many PWM based schemes have become popular but these techniques are utilized to switching frequency and fundamental frequency.

Simultaneous wireless information and power transfer is an emerging technique in neurotechnology. This work presents an efficient transmitter for both power transfer and downlink data communication to multiple, miniaturised and inductively-powered chips. We designed, implemented and tested a radio-frequency transmitter operating at 433.92 MHz of the industrial, scientific and medical band. A new structure is proposed to efficiently modulate the carrier, exploiting an amplitude-shift keying modulation reaching a data rate as high as 20 Mbps together with a variable modulation index as low as 8%.

A Markov chain is applied to build a complete model to analyze the modulation process of 4-ary MSK signals and to derive the analytic expressions of the spectrum when the modulation index h=1/2. In the derivation process, the autocorrelation function is derived first, and the spectral expressions are obtained from the autocorrelation function by Fourier transform. The accuracy of the expressions is then confirmed by numerical simulation of the MSK signal using MATLAB. Finally the specific bandwidth power output graphs, which objectively and clearly express the spectrum roll-off rate. The results show that the 4-ary MSK has better spectral efficiency and characteristics than the binary system, which is more conducive to improving the communication rate and utilizing the limited bandwidth. For the next step to improve the spectrum structure, System BER, optimize the spectrum characteristics of the preliminary work made.

An overmodulation method is proposed for an in-wheel system where two motors are coupled to a sum gear. In the dual-motor dual-inverter single shaft systems, the output voltage magnitudes of two inverters are not the same in the overmodulation range due to the angle offset between two motors. In this paper, to maintain torque balance in the overmodulation region, holding vectors are defined between adjacent vertices of two voltage hexagons. Around these vectors, the holding region is also defined by the holding angle. If a reference voltage vector is in the holding region, it is modulated to the holding vector. Otherwise, it is modulated to the vector on the arc of inscribed circle. For a given the modulation index (MI), the holding angle is obtained based on the Fourier series expansion. The proposed method keeps the output voltages of two inverters the same even if two motors have the angle offset. Further, it has the characteristic of maintaining the linearity between the reference and output MI to the maximum MI. The proposed overmodulation method is demonstrated by simulation and experimental results.

In this paper, a novel six-level T-type Active Neutral-Point-Clamped (6L-TANPC) inverter has been proposed. The hybrid topology stems from the structures of four-level ANPC inverter and three-level T-type inverter. The integration of T-type path selector into ANPC sub-circuits results in the capability of increasing number of level, flexibility of increasing the operating voltage, and reduction of device count compared to the existing similar type of converters. Furthermore, this topology produces low harmonic distortion due to the effective commutation process and absence of flying capacitor, where THD of line voltage is 13.52 % at unity modulation index. The effectiveness of the proposed topology has been verified through simulation and experimental results.

As a critical specification for the dc-link design of a voltage source inverter (VSI), the root-mean-square (RMS) value of the capacitor current should be accurately determined. Various work has been done on the modeling and analysis for the dc-link current, however an accurate model for the dc-link capacitor current still needs to be developed, especially for multilevel inverters. In this work, a detailed model for the dc-link capacitor current of a three-level VSI is proposed, and based on the model, the closed-form expression of dc-link capacitor RMS current is derived from the switching states of space vector pulse width modulation (SVPWM). The expression is a function of the modulation index and power factor, and can be used to estimate the maximum dc-link capacitor RMS current. Both simulation and experimental results are presented to validate the accuracy of the proposed model and the derived expression of the dc-link capacitor RMS current.

This paper presents a new class-AB current multiplier using fully differential hyperbolic sine transconductors based on floating-gate transistors. The proposed multiplier is developed from a hyperbolic sine multiplication identity which inherently provides a class-AB operation. The proposed multiplier was designed using 0.35 µm AMS CMOS process. Simulation results show that the proposed multiplier achieves -30 dB THD for high input modulation index of 23 while utilizing power consumption of 60 nW under a supply voltage of 3 V.

In multilevel inverter (MLI), a series of several power switches with many low voltage dc sources are utilized in order to synthesize a staircase voltage waveform. Multilevel converter has several advantages compared to traditional multilevel inverter. In this paper a new modified topology along with its cascaded connection have been proposed. This paper also talked about their symmetrical and asymmetrical configurations along with their voltage THDs and current THDs also. Their performances have been analyzed at different modulation index. Finally simulations are carried out in MATLAB 18b platform.

This paper presents the Single-Phase AC-AC Matrix Converter that using 4-units of the bidirectional switches as main power switching devices. This converter can be converted the utility 1-phase sinusoidal supply voltage into a variable voltage of the PWM pattern by adjusting the switching frequency of the control signal and modulation index of the PWM signals. The modulation indexes are 0.2, 0.4, 0.6, 0.8, and 1.0 and the output voltages are 12.5Hz, 25Hz, 50Hz, and 100Hz. The waveforms of the voltages and the currents of the single-phase AC-AC matrix converter for the simulation result with MATLAB/Simulink program and the experimental result are observed with the passive loads. Moreover, the efficiency is measured.

This paper performs a comparative analysis of overmodulation methods for AC electric drives. Criteria for the analysis considers three aspects: output vs. commanded modulation index (i.e., linearity); harmonic content; and the number of commutations (i.e., switching losses). The analysis focuses on existing methods reported in the literature. Improvements for the existing methods will be proposed as a result of the analysis. The analysis is experimentally validated on a three-phase three-level Neutral-Point-Clamped (NPC) inverter.

In this paper, a novel SVPWM strategy for open-winding machine fed by common DC-bus dual two-level 3-phase inverters is proposed to reduce current ripples. In the proposed SVPWM strategy for open-winding, each of six sectors in the space vector plane is further divided into three sub-sectors, in which the optimal effective and zero voltage vector action sequences are found to be different. Consequently, different effective and zero voltage vector action sequences are employed in three sub-sectors. Compared with the conventional SVPWM for open-winding, the proposed SVPWM strategy produces similar current harmonics in low modulation index region, but generates much lower current harmonics in high modulation index region without increasing switching frequency, as confirmed by simulation and experiments. Moreover, a zero sequence control method is proposed to suppress zero sequence current and also verified by experiment results.