An Overview of Carrier-based Modulation Methods for Z-Source Inverter
---
paper_title: Voltage-Balancing Method Using Phase-Shifted PWM for the Flying Capacitor Multilevel Converter

paper_content:

Multilevel flying capacitor (FC) converters provide natural capacitor voltage balance under phase-shifted pulse width modulation (PS-PWM). However, natural balancing may not be robust enough to maintain the voltages at the reference values, especially under certain transient conditions. Furthermore, natural balancing dynamics depend on the load and it may be very slow in some practical applications. Therefore, a more robust balancing mechanism of maintaining the FC voltages at the desired values is required. This paper proposes a new closed-loop voltage-balancing method for the multilevel FC converters using PS-PWM. The proposed method balances the voltages of the FCs by modifying the duty cycle of each switch of the FC converter using a proportional controller. The crossed effect between FC currents and duty cycles is considered and is used for optimal FC voltage balancing. Simulation and experimental results verify that the proposed voltage-balancing method is very robust to different operating conditions, such as load transients, linear/nonlinear and unbalanced loads.
---
paper_title: Reduced PWM harmonic distortion for multilevel inverters operating over a wide modulation range

paper_content:

It is known that the optimal carrier based approach for modulating a multilevel converter is to use a phase disposition (PD) carrier arrangement with a common mode offset added to the reference waveforms to centre the implicitly selected space vectors. However, this strategy does not fully utilize all available voltage levels at lower modulation depths, with an odd level system only using odd voltage levels and an even level system only using even voltage levels as the modulation depth varies. Recent work has suggested that this is not the harmonically optimal approach at reduced modulation depths. This paper shows how up to a 40% reduction in harmonic distortion can be achieved if all available voltage levels are used throughout the linear modulation range. The improvement is achieved by adding a simple (1/2) carrier magnitude common mode dc offset in key modulation regions, which allows the converter to use all available voltage levels. The paper uses analytical spectral decomposition and harmonic flux trajectory analysis to propose a theoretical basis for this improvement, and to determine the precise points at which the (1/2) carrier magnitude offset should be added to achieve the harmonic improvement.
---
paper_title: Renewable Energy Conversion Transmission And Storage

paper_content:

renewable energy conversion transmission and storage is available in our book collection an online access to it is set as public so you can get it instantly. Our digital library saves in multiple locations, allowing you to get the most less latency time to download any of our books like this one. Kindly say, the renewable energy conversion transmission and storage is universally compatible with any devices to read.
---
paper_title: Modified Phase-Shifted PWM Control for Flying Capacitor Multilevel Converters

paper_content:

The issue of voltage imbalance remains a challenge for the flying capacitor multilevel converter. The phase-shifted pulsewidth modulation (PS-PWM) method has a certain degree of self-balancing properties. However, the method alone is not sufficient to maintain balanced capacitor voltages in practical applications. The paper proposes a closed-loop modified PS-PWM control method by incorporating a novel balancing algorithm. The algorithm takes advantage of switching redundancies to adjust the switching times of selected switching states and thus maintaining the capacitor voltages balanced without adversely affecting the system's performance. Key techniques of the proposed control method, including selection of switching states, calculation of adjusting times for the selected states, and determination of new switching instants of the modified PS-PWM are described and analyzed. Simulation and experimental results are presented to confirm the feasibility of the proposed method
---
paper_title: Extended operation of flying capacitor multilevel inverters

paper_content:

Recent research in flying capacitor multilevel inverters (FCMIs) has shown that the number of voltage levels can be extended by changing the ratio of the capacitor voltages. For the three-cell FCMI, four levels of operation are expected if the traditional ratio of the capacitor voltages is 1:2:3. However, by altering the ratio, the inverter can operate as a five-, six-, seven-, or eight-level inverter. According to previous research, the eight-level case is referred to as maximally distended (or full binary combination schema) since it utilizes all possible transistor switching states. However, this case does not have enough per-phase redundancy to ensure capacitor voltage balancing under all modes of operation. In this paper, redundancy involving all phases is used along with per-phase redundancy to improve capacitor voltage balancing. It is shown that the four- and five-level cases are suitable for motor drive operation and can maintain capacitor voltage balance under a wide range of power factors and modulation indices. The six-, seven-, and eight-level cases are suitable for reactive power transfer in applications such as static var compensation. Simulation and laboratory measurements verify the proposed joint-phase redundancy control.
---
paper_title: Complete low-cost two-stage electronic ballast for 70-W high-pressure sodium vapor lamp based on current-mode-controlled buck-boost inverter

paper_content:

In this paper a low cost electronic ballast for high pressure sodium vapor lamps (HPS) is presented. The proposed ballast is a two-stage circuit that requires only one switch and one inductor for each stage. The power factor correction (PFC) stage is a buck DC-to-DC converter operating in discontinuous conduction mode (DCM) to meet with the IEC-1000-3-2 Class C requirements. The inverter stage is a very low cost non-resonant topology, based on a buck-boost inverter controlled by means of a specific current mode control implementation. Besides, a novel and simple circuit, compatible with the presented inverter is proposed to ignite the lamp. Furthermore, this circuit implementation provides a protection against broken lamp.
---
paper_title: Reconfiguration of carrier-based modulation strategy for fault tolerant multilevel inverters

paper_content:

This paper focuses on the fault-tolerance potential of multilevel inverters with redundant switching states such as the cascaded multilevel inverters and capacitor self-voltage balancing inverters. The failure situations of the multilevel inverters are classified into two types according to the relationship between output voltage levels and switching states. The gate signals can be reconfigured according to the failure modes when some of the power devices fail. The reconfiguration method is discussed for phase disposition PWM strategy (PDPWM) and phase shifted PWM strategy (PSPWM) in the paper and it can be extended for other carrier-based PWM strategies easily. Balanced line-to-line voltage will be achieved with the proposed method when device failure occurs. Furthermore, the circuit structures can be the same as the general ones and the voltage stress of the devices does not increase. Simulation and experimental results are included in the paper to verify the proposed method.
---
paper_title: A comparative study of different multilevel inverters

paper_content:

The ordinary Voltage source inverter (VSI) has two output levels +V DC /2 and -V DC /2. For medium and high power applications, multi-stage VSI (series and/or parallel combinations) with suitable filter (for obtaining near sinusoidal waveform at the output) may be a solution but there are problems in matching of different stages, selection of bulky transformer and proper filter. The quality of both the output voltage and current waveforms with minimum ripple is obtained using high frequency switching along with various PWM techniques. These conventional two level inverters have some limitations in operating at high frequencies mainly due to switching losses and constraints in device rating. The problem is resolved by means of multilevel inverters (MLIs) which utilize lower switching frequencies and give high voltages with improved total harmonic distortion (THD) without use of filter. This paper gives a brief review on different MLI techniques with advantages and disadvantages of each technique. The main disadvantages of MLI are requirement for isolated power supplies, design complexity and switching control circuits for proper elimination of lower order harmonics.
---
paper_title: Model Predictive Control of Multilevel Cascaded H-Bridge Inverters

paper_content:

This paper presents a model predictive current control algorithm that is suitable for multilevel converters and its application to a three-phase cascaded H-bridge inverter. This control method uses a discrete-time model of the system to predict the future value of the current for all voltage vectors, and selects the vector which minimizes a cost function. Due to the large number of voltage vectors available in a multilevel inverter, a large number of calculations are needed, making difficult the implementation of this control in a standard control platform. A modified control strategy that considerably reduces the amount of calculations without affecting the system's performance is proposed. Experimental results for five- and nine-level inverters validate the proposed control algorithm.
---
paper_title: Power tracking for nonlinear PV sources with coupled inductor SEPIC converter

paper_content:

The photovoltaic (PV) generator exhibits a nonlinear i-v characteristic and its maximum power (MP) point varies with solar insolation. In this paper, a V2-based MP point tracking (MPPT) scheme is developed using a buck-boost transformation topology. Although several buck-boost transformation topologies are available we have considered here a coupled inductor SEPIC converter for experimentation. To achieve almost ripple-free array current we have used ripple steering phenomena with the help of integrated inductor. This integrated inductor not only reduces the magnetic core requirements but also improves converter performance. Mathematical models are formulated and tracking algorithm is evolved. A combined PV system simulation model is developed in the SIMULINK. For a given solar insolation, the tracking algorithm changes the duty ratio of the converter such that the solar cell array (SCA) voltage equals the voltage corresponding to the MP point. This is done by the tracking algorithm, which mainly computes the power proportional to square of terminal voltage and changes the duty ratio of the converter so that this power is maximum. The proposed algorithm is implemented in real-time with the help of Analog Device ADMC-401 DSP evaluation module. The tracking program is developed to perform experimental investigations using analog-to-digital converter (ADC) interrupt. Using this processor we are able to track the MP within 200 ms. The proposed peak power tracking effectiveness is demonstrated through simulation and experimental results.
---
paper_title: A symmetric carrier technique of CRPWM for voltage balance method of flying-capacitor multilevel inverter

paper_content:

This paper presents a simple carrier symmetric method for the voltage balance of flying capacitors in flying-capacitor multilevel inverters. The carrier-redistribution pulsewidth-modulation (CRPWM) method was reported as a solution for the voltage balance but it has a drawback at the transition of voltage level. To achieve the voltage balance of flying capacitors, the utilization of each carrier must be balanced during a half-cycle of the switching period such as phase-shifted PWM. However, the CRPWM method causes the fluctuation of flying-capacitor voltages because the balanced utilization of carriers is not achieved. Moreover, it does not consider that the load current change has an influence on flying-capacitor voltages by assuming that the current flows into the load. Therefore, the charging and discharging quantities of flying-capacitor voltages do not become zero during the switching period. To overcome the drawbacks of CRPWM, it is modified by the technique where carriers of each band are disposed of symmetrically at every fundamental period. Firstly, the CRPWM method is reviewed and the theory on voltage balance of flying capacitors is analyzed. The proposed method is introduced and is verified through simulation and experimental results.
---
paper_title: Comparison of Neutral-Point-Clamped, Symmetrical, and Hybrid Asymmetrical Multilevel Inverters

paper_content:

This paper presents a comparison of three topologies of multilevel inverters applied to drive an induction motor of 500 kVA/4.16 kV rating. The multilevel inverters analyzed are the following: a neutral-point-clamped inverter, a symmetrical cascaded multilevel inverter, and a hybrid asymmetrical cascaded multilevel inverter. The performance indexes used in the comparison are total harmonic distortion, first-order distortion factor, second-order distortion factor, common-mode voltage, semiconductor power loss distribution, and heat-sink volume. The multilevel inverters are designed to present 99% efficiency at the nominal operating point, and the aforementioned performance indexes are compared for distinct values of amplitude modulation depth.
---
paper_title: Three phase PWM boost-buck rectifiers with power regenerating capability

paper_content:

Three-phase pulsewidth-modulated (PWM) boost-buck rectifiers with power-regenerating capability are investigated. The converters under consideration are capable of: (1) both voltage step-up and step-down; (2) bidirectional power processing; and (3) almost unity-power-factor operation with nearly sinusoidal AC current. Expected advantages are: (1) applicability to lower voltage applications, e.g., direct retrofit to replace diode or thyristor rectifiers; (2) switching loss reduction in the inverter load; (3) low-order harmonic control in the inverter load output voltage; (4) blanking time effect mitigation in the inverter load; and (5) a modest level of voltage sag/swell compensation. In this paper, firstly, a step-by-step power stage derivation process is described. Then, taking the Cuk-Cuk realization as an example, its operating principle and modulation scheme are described. A steady-state model and dynamic model for controller design are also described. Representative results of circuit simulations and hardware experiments are presented. Through these procedures, the feasibility of the presented three-phase PWM boost-buck rectifier with power-regenerating capability is demonstrated.
---
paper_title: New Switching Strategy for Single-Mode Operation of a Single-Stage Buck–Boost Inverter

paper_content:

Generally, single-stage buck–boost inverters consist of distinct circuits operating individually in buck/boost or positive/negative modes, the latter definitely leading to crossover distortion in the output current. This paper proposes a switching strategy that changes the bimodal operation of a single-stage buck–boost topology to a single-mode inverter. This is due to the consequent voltage gain that ensures that the output voltage polarity, apart from its magnitude, is an exclusive function of the duty ratio. Operational principle and salient hardware design are explained with the help of equivalent circuits. Details about the dynamic model are presented, based on which controller design is carried out for both stand-alone and grid-connected operation. Experimental results obtained from a 300-W, 110-V laboratory prototype are presented to validate the performance of the proposed switching strategy.
---
paper_title: Repetitive-Based Controller for a UPS Inverter to Compensate Unbalance and Harmonic Distortion

paper_content:

This paper discusses a repetitive-based controller for an uninterruptible power supply (UPS) inverter. It is shown that a bank of resonant filters, used as a refinement term for harmonic compensation in earlier works, is equivalent to a repetitive scheme with a particular structure. The latter is implemented using a simple feedback array with a delay line, thus making the implementation relatively easy. More precisely, the repetitive scheme takes a negative feedback structure plus a feedforward path whenever the odd harmonics are considered for compensation only. The repetitive scheme, equivalent to the bank of resonant filters, acts as a refinement term to reject the harmonic distortion caused by the unbalanced and distorted load current, and thus, allowing the UPS inverter to deliver an almost pure sinusoidal balanced voltage. Experimental results in a 1.5 KVA three-phase inverter are included to show the performance of the proposed controller
---
paper_title: Progress in electrical energy storage system: A critical review

paper_content:

Abstract Electrical energy storage technologies for stationary applications are reviewed. Particular attention is paid to pumped hydroelectric storage, compressed air energy storage, battery, flow battery, fuel cell, solar fuel, superconducting magnetic energy storage, flywheel, capacitor/supercapacitor, and thermal energy storage. Comparison is made among these technologies in terms of technical characteristics, applications and deployment status.
---
paper_title: A multilevel inverter topology for inductively-coupled power transfer

paper_content:

This paper describes a multilevel inverter for delivering power to a set of frequency selectable induction heating targets for stimulating temperature sensitive polymer actuators. The proposed inverter topology overcomes the capacitor voltage balancing issue common to traditional multilevel inverters. This inverter is suitable for sustained real power transfer.
---
paper_title: A Survey on Neutral-Point-Clamped Inverters

paper_content:

Neutral-point-clamped (NPC) inverters are the most widely used topology of multilevel inverters in high-power applications (several megawatts). This paper presents in a very simple way the basic operation and the most used modulation and control techniques developed to date. Special attention is paid to the loss distribution in semiconductors, and an active NPC inverter is presented to overcome this problem. This paper discusses the main fields of application and presents some technological problems such as capacitor balance and losses.
---
paper_title: Enhanced power quality control strategy for single-phase inverters in distributed generation systems

paper_content:

Power electronic converters are commonly used for interfacing distributed generation systems to the electrical power network. This paper deals with a single-phase inverter for distributed generation systems requiring power quality features, such as harmonic and reactive power compensation for grid-connected operation. The idea is to integrate the DG unit functions with shunt active power filter capabilities. With the proposed approach, the inverter controls the active power flow from the renewable energy source to the grid and also performs the non-linear load current harmonic compensation keeping the grid current almost sinusoidal. The control scheme employs a current reference generator based on Sinusoidal Signal Integrator (SSI) and Instantaneous Reactive Power (IRP) theory together with a repetitive current controller. Experimental results obtained on a 4 kVA inverter prototype demonstrate the feasibility of the proposed solution.
---
paper_title: Power budgeting of a multiple-input buck-boost converter

paper_content:

The use of a multiple-input buck-boost converter for budgeting power between different energy sources is discussed. It is shown mathematically that the idealized converter can accommodate arbitrary power commands for each input source while maintaining a prescribed output voltage. Power budgeting is demonstrated experimentally for a real converter under various circumstances, including a two-input (solar and line-powered) system. A closed-loop control example involving simultaneous tracking of output voltage and set-point tracking of the solar array shows that an autonomous system is realizable.
---
paper_title: Z-source inverter

paper_content:

This paper presents an impedance-source (or impedance-fed) power converter (abbreviated as Z-source converter) and its control method for implementing DC-to-AC, AC-to-DC, AC-to-AC, and DC-to-DC power conversion. The Z-source converter employs a unique impedance network (or circuit) to couple the converter main circuit to the power source, thus providing unique features that cannot be obtained in the traditional voltage-source (or voltage-fed) and current-source (or current-fed) converters where a capacitor and inductor are used respectively. The Z-source converter overcomes the conceptual and theoretical barriers and limitations of the traditional voltage-source converter (abbreviated as V-source converter) and current-source converter (abbreviated as I-source converter) and provides a novel power conversion concept. The Z-source concept can be applied to all DC-to-AC, AC-to-DC, AC-to-AC, and DC-to-DC power conversion. To describe the operating principle and control, this paper focuses on an example: a Z-source inverter for DC-AC power conversion needed in fuel cell applications. Simulation and experimental results are presented to demonstrate the new features.
---
paper_title: Comparative Evaluation of Three-Phase Current Source Inverters for Grid Interfacing of Distributed and Renewable Energy Systems

paper_content:

Despite the rapid growth of self-commutated inverter technology, the well-known current source inverter (CSI) has not achieved significant practical application so far. This raised the question regarding the fundamental criteria that could either prevent or promote the use of such inverters, especially considering emerging fields of application such as grid integration of renewable sources. This paper will, thus, focus on a systematic comparison between circuits based on the CSI and voltage source inverter (VSI). For such purpose, dimensionless benchmark factors were derived. The pulse width-modulated CSI with its inherent step-up capability alongside the indirect CSI (ICSI) with only two high-frequency switches features very interesting characteristics in terms of low switching losses and high inductor power density. However, both topologies show constraints with respect to the provision of reactive power. Two experimental setups have been implemented demonstrating the technical feasibility of different CSI solutions as a grid interface.
---
paper_title: Impact of Hybrid Multilevel Modulation Strategies on Input and Output Harmonic Performances

paper_content:

This paper presents a detailed analysis of the impact of a hybrid multilevel modulation strategy on the harmonic content of the input currents and output voltages. Advantages and limitations of this modulation strategy are first discussed from the load point of view. This paper also proposes a new modulation strategy for hybrid multilevel inverters which can be used with asymmetrical multipulse connection of uncontrolled rectifiers to improve the input harmonic performance of adjustable-speed drives at every operating point. This new modulation strategy maintains the original capability to synthesize output voltages with reduced harmonic distortion and makes it possible to eliminate undesirable low-frequency harmonics from input currents in all operating ranges, even when the series-connected cells process distinct active power levels
---
paper_title: Neutral-Point Potential Balancing of a Five-Level Active Neutral-Point-Clamped Inverter

paper_content:

The five-level active neutral-point (NP)-clamped (ANPC) converter is a newly emerging topology which can overcome the drawbacks of traditional NP-clamped and flying-capacitor multilevel converters. This paper presents a comprehensive theoretical analysis of the NP potential balancing issue and demonstrates that the NP potential can be naturally balanced under ideal and steady conditions. An NP potential balancing method based on zero-sequence voltage injection is presented. By calculating the average NP currents of all key zero-sequence voltages, the most appropriate zero-sequence voltage is selected to generate the demanded NP current, which can also limit the switching frequency of the series-connected insulated-gate bipolar transistors to the fundamental frequency. A three-phase five-level ANPC inverter prototype is built up, and both steady and dynamic experimental results are presented to verify the validity of this method.
---
paper_title: Multilevel Inverter Topologies With Reduced Device Count: A Review

paper_content:

Multilevel inverters have created a new wave of interest in industry and research. While the classical topologies have proved to be a viable alternative in a wide range of high-power medium-voltage applications, there has been an active interest in the evolution of newer topologies. Reduction in overall part count as compared to the classical topologies has been an important objective in the recently introduced topologies. In this paper, some of the recently proposed multilevel inverter topologies with reduced power switch count are reviewed and analyzed. The paper will serve as an introduction and an update to these topologies, both in terms of the qualitative and quantitative parameters. Also, it takes into account the challenges which arise when an attempt is made to reduce the device count. Based on a detailed comparison of these topologies as presented in this paper, appropriate multilevel solution can be arrived at for a given application.
---
paper_title: Modeling and design of a neutral-point voltage regulator for a three-level diode-clamped inverter using multiple-carrier modulation

paper_content:

The three-level diode-clamped multilevel converter commonly called the neutral-point-clamped converter has become established to be a preferred topology for high-power motor drive applications operating at several kilovolts. Although solutions to the problem of maintaining a stable neutral-point voltage in the converter continue to be the topic of research, a simple solution based on a design-oriented dynamic model of the system is not widely known. This paper presents the design, analysis, and implementation of a simple neutral-point voltage regulator for a three-level diode-clamped multilevel inverter, which uses a multiple-carrier sine-triangle modulator in conjunction with a closed-loop controller for neutral-point regulation. Redundant state choices are controlled via a continuous offset voltage that regulates the dc injection into the midpoint of the dc bus. A small-signal transfer function is developed in closed form, for neutral-point regulation, with the voltage offset as the control variable. Besides maintaining dc-bus voltage balance, the use of the approach leads to a significant reduction in the voltage distortion at the neutral point, allowing a definitive reduction in the required dc bus capacitance. Analytical, computer simulation, and experimental results verifying the approach are presented in this paper.
---
paper_title: PWM methods to handle time delay in digital control of a UPS inverter

paper_content:

With the popularity of micro-processors, digital controllers are widely used in uninterruptible power supply (UPS) inverters. These digital control systems of UPS inverters require a time interval for sampling and computation, which sometimes affects the performance of inverters. In this paper, the problem of time delay in digital control of a UPS inverter is discussed. Then two novel pulsewidth modulation (PWM) methods, the two-polarity PWM method and the asymmetric PWM method, are proposed to handle the time-delay problem. Both of these PWM methods can achieve a wide range of duty ratio between 0.05-0.95, which is independent of inverter model. Furthermore, they are easy to implement using a digital micro-controller. Experimental results are presented in the paper to verify feasibility of the proposed PWM methods.
---
paper_title: Control of parallel inverters in distributed AC power systems with consideration of line impedance effect

paper_content:

The authors have developed a new control technique which allows paralleled inverters to share linear or nonlinear load in a distributed AC power supply system. This technique does not require control interconnections and automatically compensates for inverter parameter variations and line impedance imbalances. Experimental results are provided in the paper to prove the concept.
---
paper_title: Hybrid multilevel power conversion system: a competitive solution for high power applications

paper_content:

Use of multilevel inverters is becoming popular in recent years for high power applications. Various topologies and modulation strategies have been investigated for utility and drive applications in literature. Trends in power semiconductor technology indicate a trade-off in the selection of power devices in terms of switching frequency and voltage sustaining capability. New power converter topologies permit modular realization of multilevel inverters using a hybrid approach involving integrated gate commutated thyristors (IGCT) and insulated gate bipolar transistors (IGBT) operating in synergism. This paper is devoted to the investigation of a hybrid multilevel power conversion system typically suitable for high performance, high power applications. This system designed for 4.16 kV, /spl ges/100 hp load comprises of a hybrid seven-level inverter, a diode bridge rectifier and an IGBT rectifier per phase. The IGBT rectifier is used on the utility side as a real power flow regulator to the low voltage converter and as a harmonic compensator for the high voltage converter. The hybrid seven-level inverter on the load side consists of a high voltage, slow switching IGCT inverter and a low voltage, fast switching IGBT inverter. By employing different devices under different operating conditions, it is shown that one can optimize the power conversion capability of entire system. A detailed analysis of a novel hybrid modulation technique for the inverter, which incorporates stepped synthesis in conjunction with variable pulse width of the consecutive steps is included. In addition, performance of a multilevel current regulated delta modulator as applied to the single phase full bridge IGBT rectifier is discussed. Detailed computer simulations accompanied with experimental verification are presented in the paper.
---
paper_title: Comparison of different topologies of cascaded H-Bridge multilevel inverter

paper_content:

This paper mainly deals with three different topologies of cascaded H-Bridge multilevel inverter. The Existing Topology is a general type of multilevel inverter and has two DC sources for each phase. In Proposed Topology-I the number of DC sources has been reduced to one for all the three phases and the usage of transformers comes into picture. Proposed Topology-II has also only one DC source for all the three phases and the number of switches has been reduced than compare to all other proposed topologies of Cascaded H-bridge multilevel inverter. MATLAB simulations has been carried out for all three Topologies and compared with each other.
---
paper_title: Control Architecture for Parallel-Connected Inverters in Uninterruptible Power Systems

paper_content:

In this paper, a control strategy for the parallel operation of three-phase inverters forming an online uninterruptible power system (UPS) is presented. The UPS system consists of a cluster of paralleled inverters with LC filters directly connected to an ac critical bus and an ac/dc forming a dc bus. The proposed control scheme comprises two layers: 1) a local layer that contains a “reactive power-to-phase droop” in order to synchronize the phase angle of each inverter and a virtual resistance loop that guarantees equal power sharing among inverters; and 2) a central controller that guarantees synchronization with an external real/fictitious utility, and critical bus voltage amplitude restoration. Improved transient and steady-state frequency, active, reactive, and harmonic power sharing, and global phase-locked loop resynchronization capability are achieved. Detailed system topology and control architecture are presented in this paper. Furthermore, a mathematical model was derived in order to analyze critical parameters effects on system stability. The proposed control approach has been validated by means of experimental results obtained for several case-study scenarios.
---
paper_title: Different approaches to modelling single-phase voltage source inverters for uninterruptible power supply systems

paper_content:

The standard single-phase three-level voltage source inverter (VSI) for uninterruptible power supply systems consist of a pulse width modulation (PWM) modulator, an H-bridge, and an output inductance/capacitance filter. The design of most control systems requires the inverter small-signal model. Two approaches for the discrete modelling of the VSI can be considered. The first is based on solving the state space equations during the switching period, which yields a discrete model that depends on the single-edge or double-edge type of PWM model. The second approach is the based on the continuous model of the inverter, which is derived from measurements of the real inverter and its discretisation. Both models should regard the increase in the real value of the equivalent coil series resistance and changes in the filter coil inductance with the frequency and amplitude of the magnetising current. The design of the control system requires experimental estimation of the additional delays, which are outside of the models during the measurements and modelling. Both models are validated by comparing the closed-loop systems with the simple instantaneous controllers in the experimental model.
---
paper_title: A new cascaded multilevel H-bridge drive

paper_content:

In this paper, a general structure for cascaded power converters is presented in which any number of H-bridge cells having any number of voltage levels are series connected to form an inverter phase leg. Equations are introduced for determining an optimal voltage ratio of DC voltages for the H-bridge cells which will maximize the number of voltage levels obtainable resulting in high power quality. Special cases of the generalized inverter are presented including novel 11-level and 15-level inverters. Laboratory measurements demonstrate the proposed inverter performance.
---
paper_title: Control of a cascaded H-bridge multilevel converter for grid connection of photovoltaic systems

paper_content:

In this paper a control method for cascaded H-bridge multilevel converters for grid connection of photovoltaic systems is analyzed. The use of the multilevel converter introduces a series of advantages: improved power quality (lower current ripple), smaller filters, reduced switching frequency, no need of boost dc-dc stage and possible elimination of step-up transformer, all of which have a positive impact on the system efficiency. However it requires a more sophisticated control method specially due to dc-link voltage drifts produced by circulating power in the converter. The proposed control method is based on traditional voltage oriented control with a cascaded dc-link voltage control and grid current control loop. Two extra stages are added to this traditional control scheme, one to introduce maximum power point tracking for each module or string, and another to control the dc-link voltages drift due to circulating power in the converter. The latter is performed by the addition of a simple feedforward control strategy directly in the modulation stage. The proposed control method is modular and easy to adapt for any number of converters in series. Simulation results are presented to support the theoretical analysis.
---
paper_title: A New Family of Modular Multilevel Converter Based on Modified Flying-Capacitor Multicell Converters

paper_content:

Modular multilevel converters (MMCs) are one of the next-generation multilevel converters intended for medium/high-voltage high-power market. This paper initially studies a modified topology for flying-capacitor multicell converters (FCMCs) as a modular submultilevel module. The main advantage of the modified FCMC, in comparison with the conventional one, is that the number and voltage rating of the required dc voltage sources are halved. Afterward, the MMC that comprises the series connection of the modified FCMCs used as submultilevel modules is proposed. Simulation results and experimental measurements taken from the four-cell-five-level laboratory prototype system of the modified FCMC as a modular submultilevel module are presented in order to validate its performance and advantages. Moreover, simulation results and experimental measurements of three cascaded two-cell-three-level modules (ultimately seven-level proposed MMC) and four cascaded two-cell-three-level modules (ultimately nine-level proposed MMC) are presented in order to validate its viability, merits and the proposed control strategy.
---
paper_title: Extended-Boost $Z$ -Source Inverters

paper_content:

The Z-source inverter has gained popularity as a single-stage buck-boost inverter topology among many researchers. However, its boosting capability could be limited, and therefore, it may not be suitable for some applications requiring very high boost demand of cascading other dc-dc boost converters. This could lose the efficiency and demand more sensing for controlling the added new stages. This paper is proposing a new family of extended-boost quasi Z -source inverter (ZSI) to fill the research gap left in the development of ZSI. These new topologies can be operated with same modulation methods that were developed for original ZSI. Also, they have the same number of active switches as original ZSI preserving the single-stage nature of ZSI. Proposed topologies are analyzed in the steady state and their performances are validated using simulated results obtained in MATLAB/Simulink. Furthermore, they are experimentally validated with results obtained from a prototype developed in the laboratory.
---
paper_title: New type T-Source inverter

paper_content:

This paper presents different topologies of voltage inverters with alternative input LC networks. The basic topology is known in the literature as a Z-source inverter (ZSI). Alternative passive networks were named by the authors as T-sources. T-source inverter has fewer reactive components in comparison to conventional Z-source inverter. The most significant advantage of the T-source inverter (TSI) is its use of a common voltage source of the passive arrangement. Experimental results for the TSI are in agreement with theoretical and simulated prediction.
---
paper_title: Y-source impedance network

paper_content:

This paper introduces a Y-shaped impedance network for realizing converters that demand a high voltage gain while using a small duty ratio. To achieve that, the proposed network uses a tightly coupled transformer with three windings, whose obtained gain is presently not matched by existing networks operated at the same duty ratio. This capability has been demonstrated by mathematical derivation for the proposed network in comparison with other recently reported networks. To further prove the network performance, a single-switch dc-dc converter has been implemented with the network, before testing it experimentally. The results obtained clearly verify the network performance in addition to its higher power density that can generally be achieved by coupled magnetics.
---
paper_title: Improved Z-Source Inverter With Reduced Z-Source Capacitor Voltage Stress and Soft-Start Capability

paper_content:

This paper proposes an improved Z-source inverter topology. Compared to the traditional Z-source inverter, it can reduce the Z-source capacitor voltage stress significantly to perform the same voltage boost, and has inherent limitation to inrush current at startup. The control strategy of the proposed Z-source inverter is exactly the same as the traditional one, so all the existing control strategy can be used directly. A soft-start strategy is also proposed to suppress the inrush surge and the resonance of Z-source capacitors and inductors. The operation principle of the proposed topology and comparison with the traditional topology are analyzed in detail. Simulation and experimental results are given to demonstrate the new features of the improved topology.
---
paper_title: Distributed Impedance Network (Z-Network) DC–DC Converter

paper_content:

This paper presents a novel dc-dc converter incorporating a distributed impedance-source network (Z-source network, or Z-network) to achieve the buck (step-down) and boost (step-up) function of a transformer-isolated dc-dc converter. In this paper, the distributed impedance source network composed of an array of inductors and capacitors is coupled between power source and main switching devices. The great and unique feature about the distributed impedance source network dc-dc converter is that unlike the traditional V-source or I-source converters, it can be open- and short-circuited without damaging switching devices. Therefore, the desired buck and boost function can be achieved. Moreover, converter reliability can be greatly improved. A dc-dc converter using this proposed concept is built and tested. Its performances are verified with experimental results.
---
paper_title: Topological and Modulation Design of Three-Level Z-Source Inverters

paper_content:

This paper presents the development of two three-level cascaded Z-source inverters, whose output voltage can be stepped down or up unlike a traditional buck three-level inverter. The proposed inverters are designed using two three-phase voltage-source inverter bridges, supplied by two uniquely designed Z-source impedance networks and cascaded at either their DC sides to form a DC-link-cascaded Z-source inverter or AC outputs using single-phase transformers to form a dual Z-source inverter. For controlling both inverters, various modulation schemes are designed with their performances verified experimentally using an implemented laboratory prototype
---
paper_title: Z-source inverter

paper_content:

This paper presents an impedance-source (or impedance-fed) power converter (abbreviated as Z-source converter) and its control method for implementing DC-to-AC, AC-to-DC, AC-to-AC, and DC-to-DC power conversion. The Z-source converter employs a unique impedance network (or circuit) to couple the converter main circuit to the power source, thus providing unique features that cannot be obtained in the traditional voltage-source (or voltage-fed) and current-source (or current-fed) converters where a capacitor and inductor are used respectively. The Z-source converter overcomes the conceptual and theoretical barriers and limitations of the traditional voltage-source converter (abbreviated as V-source converter) and current-source converter (abbreviated as I-source converter) and provides a novel power conversion concept. The Z-source concept can be applied to all DC-to-AC, AC-to-DC, AC-to-AC, and DC-to-DC power conversion. To describe the operating principle and control, this paper focuses on an example: a Z-source inverter for DC-AC power conversion needed in fuel cell applications. Simulation and experimental results are presented to demonstrate the new features.
---
paper_title: Topological and Modulation Design of Three-Level Z-Source Inverters

paper_content:

This paper presents the development of two three-level cascaded Z-source inverters, whose output voltage can be stepped down or up unlike a traditional buck three-level inverter. The proposed inverters are designed using two three-phase voltage-source inverter bridges, supplied by two uniquely designed Z-source impedance networks and cascaded at either their DC sides to form a DC-link-cascaded Z-source inverter or AC outputs using single-phase transformers to form a dual Z-source inverter. For controlling both inverters, various modulation schemes are designed with their performances verified experimentally using an implemented laboratory prototype
---
paper_title: Multicarrier PWM strategies for multilevel inverters

paper_content:

Analytical solutions of pulsewidth-modulation (PWM) strategies for multilevel inverters are used to identify that alternative phase opposition disposition PWM for diode-clamped inverters produces the same harmonic performance as phase-shifted carrier PWM for cascaded inverters, and hybrid PWM for hybrid inverters, when the carrier frequencies are set to achieve the same number of inverter switch transitions over each fundamental cycle. Using this understanding, a PWM method is then developed for cascaded and hybrid inverters to achieve the same harmonic gains as phase disposition PWM achieves for diode-clamped inverters. Theoretical and experimental results are presented in the paper.
---
paper_title: A neutral-point potential balancing method for Z-source neutral-point-clamped (NPC) inverters by adding the shoot-through offset

paper_content:

Compared with the conventional buck-boost three-level inverters, the Z-source neutral-point-clamped (NPC) inverters have more simple structure with improved output waveform quality. But the neutral-point potential unbalance problem is still a drawback for their applications. Based on the research of SPWM modulation method and the analysis of the effect of the shoot-through states on the neutral-point potential, this paper proposes a neutral-point potential balancing method by adding the shoot-through offset which can be applied to the constant boost control and the third-harmonic-injection control. This new method is simple and has the advantage that the neutral-point potential unbalance problem can be improved with the high voltage gain, which is verified by simulation results.
---
paper_title: Modulation techniques applied to medium voltage modular multilevel converters for renewable energy integration: A review

paper_content:

Abstract Modular multilevel converters (MMC) inherent features are gaining more attention for dc voltage transmission systems. One of the main research paths regarding the converter performance deals with its voltage modulation. Specifically, for medium voltage applications with relatively small number of submodules, the voltage modulation techniques impact on the MMC performance needs to be studied. This work provides an extensive review of the carrier-based pulse with modulation (CB-PWM) techniques proposed to be applied on previous multilevel inverter versions. The CB-PWM methods were adapted to be compatible with an additional cell ranking and selection algorithm to ensure equal energy distribution on the arm cells. The state-of-the-art of zero sequence signals (ZSS) applied on three-phase inverters is also reviewed. The alliance between the ZSS with the CB-PWM, as well as the nearest level modulation (NLM), has an important impact on the MMC harmonic content, efficiency and voltage ripple of its cells capacitors. A 15 MW 28-cell-based MMC is used to investigate each particular combination between the modulation method and the common mode ZSS.
---
paper_title: A comparison of phase disposition and phase shift PWM strategies for modular multilevel converters

paper_content:

Modular Multilevel Converter (MMC) has proved to be an effective solution for high power applications, supplying low distorted output voltage and high fault tolerance. This paper presents a detailed performance comparison between phase disposition PWM (PDPWM) and phase shift PWM (PSPWM) schemes under normal condition, over-modulation, as well as carrier non-synchronization condition. Compared to the PSPWM strategy, the PDPWM has smaller line-to-line voltage distortion under normal condition, when the carrier frequencies are adjusted to achieve the same number of switch transitions over one fundamental cycle. In addition, the capacitor voltages are able to keep balanced without additional controllers. Under over-modulation condition, PDPWM can still achieve smaller voltage distortion without capacitor voltage deviation, while obvious voltage differences are observed with PSPWM, which shows an opposite trend toward that of normal condition. Moreover, asynchronous carriers have different impacts on the harmonic cancellation, which needs to be carefully considered in a hardware implementation. Simulation results for a three-phase nine-level inverter system generated with the Matlab/Simulink software are provided to support the theoretical considerations.
---
paper_title: A DC-Link Voltage Self-Balance Method for a Diode-Clamped Modular Multilevel Converter With Minimum Number of Voltage Sensors

paper_content:

Voltage balance issue of dc-link capacitors is very important for applications of a cascade multilevel converter or a modular multilevel converter. In this paper, a novel diode-clamped modular multilevel converter (DCM2C) topology is proposed and a power feedback control method is developed. With the developed control strategy, the proposed diode-clamped circuit becomes a controllable closed loop which enables the capacitor voltages to be clamped by low power rating clamping diodes. The proposed topology and control strategy has quicker response and requires much fewer voltage sensors than the normally used traditional method; therefore, the system performance improvement and cost reduction are expected. Based on the proposed DCM2C, a novel N +1-level cascade multilevel topology is proposed for a cascade active power filter (CS-APF). The simulation and experimental results from the CS-APF have demonstrated and verified the effectiveness of the proposed novel topology and control method.
---
paper_title: A Steady-State Analysis Method for a Modular Multilevel Converter

paper_content:

Modular multilevel converters (MMC) are considered a top converter alternative for voltage-source converter (VSC) high-voltage, direct current (HVDC) applications. Main circuit design and converter performance evaluation are always important issues to consider before installing a VSC-HVDC system. Investigation into a steady-state analysis method for an MMC-based VSC-HVDC system is necessary. This paper finds a circular interaction among the electrical quantities in an MMC. Through this circular interaction, a key equation can be established to solve the unknown circulating current. A new steady-state model is developed to simply and accurately describe the explicit analytical expressions for various voltage and current quantities in an MMC. The accuracy of the expressions is improved by the consideration of the circulating current when deriving all the analytical expressions. The model's simplicity is demonstrated by having only one key equation to solve. Based on the analytical expressions for the arm voltages, the equivalent circuits for MMC are proposed to improve the current understanding of the operation of MMC. The feasibility and accuracy of the proposed method are verified by comparing its results with the simulation and experimental results.
---
paper_title: Optimized space vector switching sequences for multilevel inverters

paper_content:

Previous work has shown that space vector modulation and carrier modulation for two-level inverters achieve the same phase leg switching sequences when appropriate zero sequence offsets are added to the reference waveforms for carrier modulation. This paper presents a similar equivalence between the phase disposition (PD) carrier and space vector modulation strategies applied to diode clamped, cascaded N-level or hybrid multilevel inverters. By analysis of the time integral trajectory of the converter voltage, the paper shows that the optimal harmonic profile for a space vector modulator occurs when the two middle space vectors are centered in each switching cycle. The required zero sequence offset to achieve this centring for an equivalent carrier based modulator is then determined. The results can be applied to any multilevel converter topology without differentiation. Discontinuous behavior is also examined, with the space vector and carrier based modulation methods shown to similarly produce identical performance. Both simulation and experimental results are presented.
---
paper_title: A Medium-Voltage Motor Drive With a Modular Multilevel PWM Inverter

paper_content:

This paper describes the control and operating performance of a modular multilevel PWM inverter for a transformerless medium-voltage motor drive. The inverter is prominent in the modular arm structure consisting of a cascaded stack of multiple bidirectional chopper-cells. The dominant ac-voltage fluctuation with the same frequency as the motor (inverter) frequency occurs across the dc capacitor of each chopper-cell. The magnitude of the voltage fluctuation is inversely proportional to the motor frequency. This paper achieves theoretical analysis on the voltage fluctuation, leading to system design. A downscaled model rated at 400 V and 15 kW is designed and built up to confirm the validity and effectiveness of the nine-level (17-level in line-to-line) PWM inverter for a medium-voltage motor drive.
---
paper_title: Z-source inverter

paper_content:

This paper presents an impedance-source (or impedance-fed) power converter (abbreviated as Z-source converter) and its control method for implementing DC-to-AC, AC-to-DC, AC-to-AC, and DC-to-DC power conversion. The Z-source converter employs a unique impedance network (or circuit) to couple the converter main circuit to the power source, thus providing unique features that cannot be obtained in the traditional voltage-source (or voltage-fed) and current-source (or current-fed) converters where a capacitor and inductor are used respectively. The Z-source converter overcomes the conceptual and theoretical barriers and limitations of the traditional voltage-source converter (abbreviated as V-source converter) and current-source converter (abbreviated as I-source converter) and provides a novel power conversion concept. The Z-source concept can be applied to all DC-to-AC, AC-to-DC, AC-to-AC, and DC-to-DC power conversion. To describe the operating principle and control, this paper focuses on an example: a Z-source inverter for DC-AC power conversion needed in fuel cell applications. Simulation and experimental results are presented to demonstrate the new features.
---
paper_title: Z-source inverter

paper_content:

This paper presents an impedance-source (or impedance-fed) power converter (abbreviated as Z-source converter) and its control method for implementing DC-to-AC, AC-to-DC, AC-to-AC, and DC-to-DC power conversion. The Z-source converter employs a unique impedance network (or circuit) to couple the converter main circuit to the power source, thus providing unique features that cannot be obtained in the traditional voltage-source (or voltage-fed) and current-source (or current-fed) converters where a capacitor and inductor are used respectively. The Z-source converter overcomes the conceptual and theoretical barriers and limitations of the traditional voltage-source converter (abbreviated as V-source converter) and current-source converter (abbreviated as I-source converter) and provides a novel power conversion concept. The Z-source concept can be applied to all DC-to-AC, AC-to-DC, AC-to-AC, and DC-to-DC power conversion. To describe the operating principle and control, this paper focuses on an example: a Z-source inverter for DC-AC power conversion needed in fuel cell applications. Simulation and experimental results are presented to demonstrate the new features.
---
paper_title: Maximum boost control of the Z-source inverter

paper_content:

This paper explores control methods for the Z-source inverter and their relationships of voltage boost versus modulation index. A maximum boost control is presented to produce the maximum voltage boost (or voltage gain) under a given modulation index. The control method, relationships of voltage gain versus modulation index, and voltage stress versus voltage gain are analyzed in detail and verified by simulation and experiment.
---
paper_title: Constant boost control of the Z-source inverter to minimize current ripple and voltage stress

paper_content:

This paper proposes two constant boost-control methods for the Z-source inverter, which can obtain maximum voltage gain at any given modulation index without producing any low-frequency ripple that is related to the output frequency and minimize the voltage stress at the same time. Thus, the Z-network requirement will be independent of the output frequency and determined only by the switching frequency. The relationship of voltage gain to modulation index is analyzed in detail and verified by simulation and experiments.
---
paper_title: A neutral-point potential balancing method for Z-source neutral-point-clamped (NPC) inverters by adding the shoot-through offset

paper_content:

Compared with the conventional buck-boost three-level inverters, the Z-source neutral-point-clamped (NPC) inverters have more simple structure with improved output waveform quality. But the neutral-point potential unbalance problem is still a drawback for their applications. Based on the research of SPWM modulation method and the analysis of the effect of the shoot-through states on the neutral-point potential, this paper proposes a neutral-point potential balancing method by adding the shoot-through offset which can be applied to the constant boost control and the third-harmonic-injection control. This new method is simple and has the advantage that the neutral-point potential unbalance problem can be improved with the high voltage gain, which is verified by simulation results.
---
paper_title: Modulation Schemes of Multi-phase Three-Level Z-Source Inverters

paper_content:

This paper investigates the modulation schemes of three-level multiphase Z-source inverters with either two Z-source networks or single Z-source network connected between the DC sources and inverter circuitry. With the proper offset added for achieving both desired four-leg operation and optimized harmonic performance, the proposed modulation schemes of four-leg three-level Z-source inverters can satisfy the expected buck-boost operation under unbalanced modulation conditions. Except of the modulation complexity hidden in the four-leg inverters, five-phase three-level Z-source inverters show totally different modulation requirement and output performance. For clearly illustrating the detailed modulation process, time domain analysis instead of the traditional multi-dimensional space vector demonstration is assumed which reveals the right way to insert shoot-through durations in the switching sequence with minimal commutation count. Lastly, the theoretical findings are verified in Matlab/PLECS simulation and experimentally using constructed laboratory prototypes.
---
paper_title: A novel space vector PWM for Z-source inverter

paper_content:

This paper presents a novel space vector pulse width modulation (SVPWM) technique for three phase Z-source inverter. The proposed modified SVPWM has an additional shoot-through state for boosting the dc link voltage of the inverter beside active and zero states. The shoot-through states are evenly assigned to each phase within zero state. So zero voltage period is diminished for generating a shoot-through time, and active states are unchanged. Simulation and experimental results are presented to demonstrate the new features.
---
paper_title: Reference Disposition Modulation Method for non-ideal Dual Z-Source Neutral-Point-Clamped Inverter

paper_content:

A single stage Z-source Neutral-Point-Clamped (NPC) inverter for buck-boost conversion is considered as a better alternative for the two-staged energy conversion in traditional inverters. The Dual Z-Source Network (DZSN) uses two distinct X-shaped impedance networks to connect two individual dc sources to the inverter circuit. The output voltage boosting can be achieved by selectively shooting-through the power sources in the dual networks. This study proposes a novel modulation method for integrating the shoot-through state to the traditional inverter switching. The performance of the proposed modulation method for DZSN is examined utilising attributes which include, voltage boosting, switching losses, efficiency, etc. In addition, this study also deals with non-ideal DZSN, where the circuit resistance and their respective voltage drops are considered. The presented modulation method uses a single carrier signal which is compared with two sets of sinusoidal reference signals to establish the switching. The theoretical findings of the proposed modulation method are verified using Matlab/Simulink and PSIM software. Moreover, an experimental NPC prototype was built and the results for the different values of modulation index are presented, which validate the applicability of proposed modulation method.
---
paper_title: Comparative Evaluation of Pulsewidth Modulation Strategies for Z-Source Neutral-Point-Clamped Inverter

paper_content:

Z-source neutral-point-clamped (NPC) inverter has recently been proposed as an alternative three-level buck-boost power conversion solution with an improved output waveform quality. In principle, the designed Z-source inverter functions by selectively “shooting through” its power sources, coupled to the inverter using two unique Z-source impedance networks, to boost the inverter three-level output waveform. Proper modulation of the new inverter would therefore require careful integration of the selective shoot-through process to the basic switching concepts to achieve maximal voltage-boost, minimal harmonic distortion, lower semiconductor stress and minimal number of device commutations per switching cycle. To date, the theoretical background on Z-source NPC modulation has not been fully established, and it is the theme of this paper to propose a number of enhanced voltage-boost pulse-width modulation (PWM) strategies for controlling the Z-source NPC inverter. While developing the PWM techniques, attention has been devoted to carefully derive them from a common generic basis for improved portability, easier implementation, and most importantly, assisting readers in understanding all concepts that have been presented. The presented strategies are also comparatively evaluated to identify their individual advantages and disadvantages, which are subsequently summarized in a comprehensive reference table. Lastly, simulation and experimental results are included for validating the performances and practicalities of the presented modulation schemes.
---
paper_title: Overview of Space Vector Modulations for Three-Phase Z-Source/Quasi-Z-Source Inverters

paper_content:

Three existing and one extended space vector modulations (SVMs) for the three-phase Z-source/quasi-Z-source inverter (ZSI/qZSI) are investigated. The different switching control patterns, the available maximum shoot-through duty ratio, the maximum voltage stress across the switch versus voltage gain, and efficiency are compared in detail. A total average switch device power taking into account the shoot-through current stress is proposed to evaluate the total stress of power switches. Simulation and experimental results of the prototyped qZSI verify the theoretical analysis. The six parts of shoot-through time intervals will reduce the inductor current ripples, and improve the qZSI efficiency. Also, the maximum voltage stress and total average switch power will benefit from the shoot-through division. However, the division method impacts these performances of qZSI.
---
paper_title: Three-Level AC–DC–AC Z-Source Converter Using Reduced Passive Component Count

paper_content:

This paper presents a three-level ac-dc-ac Z-source converter with output voltage buck-boost capability. The converter is implemented by connecting a low cost front-end diode rectifier to a neutral-point-clamped inverter through a single X-shaped LC impedance network. The inverter is controlled to switch with a three-level output voltage, where the middle neutral potential is uniquely tapped from the star-point of a wye-connected capacitive filter placed before the front-end diode rectifier for input current filtering. Through careful control, the resulting converter can accurately produce the correct volt-sec average at its output, while simultaneously achieving inductive voltage boosting. More interestingly, these performance features are achieved with no increase in the number of semiconductor commutations, and hence no increase in switching losses. The proposed converter therefore offers a low cost alternative to sensitive applications that need to ride-through frequent input voltage sags. For confirming the converter performance, experimental testing using a constructed laboratory prototype is performed with its captured results presented in a later section of the paper.
---
paper_title: Analysis of an ideal dual impedance network using reference disposition modulation

paper_content:

A single-impedance network consists of two inductors and capacitors connected in an X-shape to provide single-stage energy conversion. This structure eliminates the need for two-stage energy conversion that is currently employed in traditional converters. A dual-impedance network includes two individual sets of inductors and capacitors connected in parallel. This network possesses the flexibility of using two different sources as inputs to meet the load demand. In order to provide voltage boosting, the switching must be performed selectively to shoot-through (ST) the power sources. A modified modulation method has been implemented to introduce the ST for switching. The modified modulation method shares the operating principle with the in-phase disposition modulation method for multilevel inverters. However, the reference signals are dispositioned via the modified modulation method rather than employing carrier disposition via the traditional modulation methods. Therefore, the circuit analysis of a dual-impedance network is evaluated whose switching is achieved by a modified modulation method for an ideal condition. The simulations are carried out using the MATLAB/PSIM environment and the results are presented.
---
paper_title: Control of a Fuel Cell Based Z-Source Converter

paper_content:

This paper presents system modeling, modified space vector PWM implementation (MSVPWM), and control system design of a Z-source converter. For an electrical analysis of the fuel cell powered systems, the fuel cell system is modeled by an R-C circuit including its voltage-current polarization characteristics. A discrete-time state space equation is given to implement digital control and a space vector pulse-width modulation technique is modified to realize the shoot-through zero vectors that boost the dc-link voltage. Three discrete-time controllers and an asymptotic observer are designed.
---
paper_title: Impedance-Source Networks for Electric Power Conversion Part II: Review of Control and Modulation Techniques

paper_content:

Impedance-source networks cover the entire spectrum of electric power conversion applications (dc-dc, dc-ac, ac-dc, ac-ac) controlled and modulated by different modulation strategies to generate the desired dc or ac voltage and current at the output. A comprehensive review of various impedance-source-network-based power converters has been covered in a previous paper and main topologies were discussed from an application point of view. Now Part II provides a comprehensive review of the most popular control and modulation strategies for impedance-source network-based power converters/inverters. These methods are compared in terms of theoretical complexity and performance, when applied to the respective switching topologies. Further, this paper provides as a guide and quick reference for researchers and practicing engineers in deciding which control and modulation method to consider for an application in a given topology at a certain power level, switching frequency and demanded dynamic response.
---
paper_title: A hybrid PWM strategy for Z-source neutral-point-clamped inverter

paper_content:

This paper presents a hybrid PWM strategy for Z-source NPC converter. The technique combines the space-vector PWM with the ease of implementation of a triangular-comparision PWM. Such strategy reduces the effort of the algorithm calculation. The introduction of the distribution ratio in this technique, allows the development of a systematic approach for implementation of either conventional or any modified vector strategies, even including the shoot-through inherent of Z-source inverter. Also, the paper proposes a simple software algorithm to generate the hybrid modulation for the Z-source NPC inverter. Simulated and experimental results demonstrate the validity of the proposed method.
---

Title: An Overview of Carrier-based Modulation Methods for Z-Source Inverter

Section 1: Introduction
Description 1: This section introduces the reader to the context and significance of Z-Source Inverters (ZSIs) in energy conversion, contrasting them with traditional Voltage Source Inverters (VSIs) and Current Source Inverters (CSIs).

Section 2: Single-stage energy converters
Description 2: This section elaborates on the distinctions between two-stage and single-stage energy converters and discusses various single-stage converters, including ZSI, and their advantages.

Section 3: ZSI
Description 3: This section explores the general features, advantages, and drawbacks of ZSI, along with the different topological modifications like quasi-ZSI, embedded ZSI, and others.

Section 4: Two-level ZSI
Description 4: This section describes the topology and operation of two-level ZSI, highlighting the impedance network and the implementation of the shoot-through (ST) state for voltage boosting.

Section 5: Three-level ZSI
Description 5: This section covers the topology and operation of three-level ZSI configurations, their voltage boosting techniques, and the challenges in inserting ST states.

Section 6: Modulation methods
Description 6: This section provides an overview of pulse width modulation (PWM) techniques applied to ZSI, focusing on traditional PWM, and the need for insertion of ST states, with detailed descriptions of several carrier-based modulation methods.

Section 7: SBC method
Description 7: This section reviews the Simple Boost Control (SBC) method and its implementation for ZSI, along with its benefits and limitations.

Section 8: MBC method
Description 8: This section details the Maximum Boost Control (MBC) method, its improvements over SBC, and its drawback of introducing ripple components.

Section 9: MCBC method
Description 9: This section explains the Maximum Constant Boost Control (MCBC) method, highlighting its advantages in reducing ripple components and maintaining a constant duty ratio.

Section 10: POD modulation method
Description 10: This section outlines the Phase Opposition Disposition (POD) modulation method for traditional and three-level ZSI, focusing on voltage boosting and ST state insertion.

Section 11: In-phase disposition modulation method
Description 11: This section discusses the In-Phase Disposition (I-PD) modulation method, its harmonic reduction capability, and the adapted switching sequence for ZSI.

Section 12: Reference disposition modulation method
Description 12: This section reviews the Reference Disposition (RD) modulation method for ZSI, incorporating modified signals for ST state insertion and voltage boosting.

Section 13: Conclusions
Description 13: This section summarizes the review, discusses the efficacy of various carrier-based modulation methods for ZSI, and suggests preferred modulation techniques for specific application scenarios.

Section 14: Declarations of interest
Description 14: This section provides information regarding the authors' declarations of interest.