Showing papers on "H bridge published in 2017"
TL;DR: In this paper, a fault-tolerant structure and its controlling method for a cascaded H-bridge multilevel inverter is introduced, which is able to isolate and eliminate the defective module from the whole system.
Abstract: In this study, a fault-tolerant structure and its controlling method for a cascaded H-bridge multilevel inverter is introduced. When a fault occurs in one of the modules, the proposed circuit is able to isolate and eliminate the defective module from the whole system. The isolation and elimination is done by four relays in each module and a controlling circuit. This solution makes the system continue the normal operation by means of the remained healthy modules with decreased output voltage level. Therefore, the whole system failure will be prevented and higher reliability of the inverter will be guaranteed. Principles of operation and the controlling method are presented in this study. Reliability evaluation and comparison of the proposed fault-tolerant structure and the conventional one are considered. To ensure the correct performance of the proposed cascaded H-bridge multilevel inverter, a prototype has been synthesised in the laboratory. The obtained results affirm higher reliability and mean time to failure of the proposed circuit, so suitability of the proposed structure for sensitive industrial applications is confirmed.
99 citations
TL;DR: A new fault-tolerant solution for cascaded H-bridge (CHB) converters, which generates equal output voltages in both prefault and single fault conditions is presented.
Abstract: This paper presents a new fault-tolerant solution for cascaded H-bridge (CHB) converters, which generates equal output voltages in both prefault and single fault conditions. To generate a balanced three-phase voltage with the highest amplitude regardless of the fault location and its type, an auxiliary module is employed in series with the CHB converter. The auxiliary module is a two-level voltage-source inverter with a capacitive dc link. The module is brought to the circuit after fault detection and its capacitor is charged by a novel algorithm to the reference value. Then, using the space vector modulation, the inverter's reference space vector is synthesized and the voltage of auxiliary module is kept constant. The validation of the proposed method is confirmed by simulations and experiments on a three-phase five-level CHB converter.
98 citations
TL;DR: The experimental validation of this structure on a reduced-size single-phase laboratory prototype confirms the interest of the proposed PV multistring architecture.
Abstract: For large-scale photovoltaic (PV) systems, the multistring configuration is becoming more and more attractive compared with the classical central inverter, since it results in better energy yield by realizing distributed maximum power point tracking. Among the existing solutions, an attractive topology consists in a single dc bus bar collector cascaded H-bridge (CHB) inverter. Through the use of a single dc bus bar collector, the CHB inverter presents inherent balanced operation while the multistring PV-system is fully decoupled from the grid-tie inverter. This paper proposes the experimental validation of this structure on a reduced-size single-phase laboratory prototype. Results confirm the interest of the proposed PV multistring architecture.
97 citations
TL;DR: In this paper, the authors provided an extensive theoretical analysis of DC-link voltage ripple for full-bridge (H-bridge) inverters, with simulation and experimental verifications, considering a DC source impedance (nonideal DC voltage source).
Abstract: Direct current (DC)-link voltage ripple analysis is essential for determining harmonic noise and for DC-link capacitor design and selection in single-phase pulse-width modulation (PWM) inverters. This paper provides an extensive theoretical analysis of DC-link voltage ripple for full-bridge (H-bridge) inverters, with simulation and experimental verifications, considering a DC source impedance (non-ideal DC voltage source). The DC voltage ripple amplitude is theoretically estimated as a function of the output current, both amplitude and phase angle, and the modulation index. It consists of a switching frequency component and a double-fundamental frequency component (i.e., 100 Hz), thereby both components are considered in the analysis. In particular, the peak-to-peak distribution, maximum amplitude, and root mean square (RMS) values of the voltage switching ripple over the fundamental period are obtained. Based on the DC voltage requirements, simple and effective guidelines for designing DC-link capacitors are obtained.
96 citations
TL;DR: A modification of this conventional modulation method using variable shift angles between the power cells is introduced, which leads to the elimination of harmonic distortion of low-order harmonics due to the switching (triangular carrier frequency and its multiples) even under unbalanced operational conditions.
Abstract: Multilevel cascaded H-bridge converters have become a mature technology for applications where high-power medium ac voltages are required. Normal operation of multilevel cascaded H-bridge converters assumes that all power cells have the same dc voltage, and each power cell generates the same voltage averaged over a sampling period using a conventional phase-shifted pulse width modulation (PWM) technique. However, this modulation method does not achieve good results under unbalanced operation per H-bridge in the power converter, which may happen in grid-connected applications such as photovoltaic or battery energy storage systems. In the paper, a simplified mathematical analysis of the phase-shifted PWM technique is presented. In addition, a modification of this conventional modulation method using variable shift angles between the power cells is introduced. This modification leads to the elimination of harmonic distortion of low-order harmonics due to the switching (triangular carrier frequency and its multiples) even under unbalanced operational conditions. The analysis is particularized for a three-cell cascaded H-bridge converter, and experimental results are presented to demonstrate the good performance of the proposed modulation method.
90 citations
TL;DR: In this article, a general solution for the required zero-sequence voltage/current for any kind of unbalanced condition is provided, and the obtained solutions show that a singularity for both configurations exists under specific conditions, leading to infinite zero sequence requirement.
Abstract: The aim of this paper is to investigate the ability of cascaded H-bridge STATic COMpensator in star and delta configuration to exchange negative-sequence current with the connecting grid. Zero-sequence voltage for the star and zero-sequence current for the delta configuration are utilized to guarantee dc-capacitor voltage balancing. A general solution for the required zero-sequence voltage/current for any kind of unbalanced condition is provided. The obtained solutions show that a singularity for both configurations exists under specific conditions, leading to infinite zero-sequence requirement. In case of star configuration, this singularity occurs when the amplitude of the positive- and negative-sequence components of the current output of the converter are equal. Analogously, the singularity for the delta configuration occurs when the amplitude of the positive- and negative-sequence components of the voltage at the converter terminals are equal. This singularity impacts the ratings of the system and imposes a limitation in the utilization of the compensator for unbalance compensation purposes, both in industrial and utility applications. Experimental results are presented to validate the theoretical analysis.
88 citations
TL;DR: In this article, a cascaded H-bridge multilevel converter (CHB-MC)-based StatCom system is proposed to operate with extremely low dc capacitance values.
Abstract: This paper introduces a cascaded H-bridge multilevel converter (CHB-MC)-based StatCom system that is able to operate with extremely low dc capacitance values. The theoretical limit is calculated for the maximum capacitor voltage ripple, and hence minimum dc capacitance values that can be used in the converter. The proposed low-capacitance StatCom ( LC -StatCom) is able to operate with large capacitor voltage ripples, which are very close to the calculated theoretical maximum voltage ripple. The maximum voltage stress on the semiconductors in the LC -StatCom is lower than in a conventional StatCom system. The variable cluster voltage magnitude in the LC -StatCom system drops well below the maximum grid voltage, which allows a fixed maximum voltage on the individual capacitors. It is demonstrated that the proposed LC -StatCom has an asymmetric V–I characteristic, which is especially suited for operation as a reactive power source within the capacitive region. A high-bandwidth control system is designed for the proposed StatCom to provide control of the capacitor voltages during highly dynamic transient events. The proposed LC -StatCom system is experimentally verified on a low-voltage seven-level CHB-MC prototype. The experimental results show successful operation of the system with ripples as high as 90% of the nominal dc voltage. The required energy storage for the LC -StatCom system shows significant reduction compared to a conventional StatCom design.
86 citations
TL;DR: The proposed method along with the presented topology can achieve voltage balance in spite of the power flow direction, simplification of the controller for the dc–dc modules and can also bear unbalanced power flow.
Abstract: A bidirectional high-frequency isolated ac–dc converter for utility direct interfaced electric vehicle charger with vehicle-to-grid (V2G) capability is presented in this paper. This type of charger can achieve the direct utility interface with medium voltage input. It is composed of multilevel cascaded H-bridge ac–dc converter as the first stage and modular current-fed dual active bridge dc–dc converters as the second stage. For the cascaded H-bridge converter, a unified control to balance the cascaded H-bridge dc voltages is proposed for both charging and discharging modes. For the second dc–dc isolation stage, the current-fed dual active bridge converter is used in facing of the wide conversion gain in battery charging application and also to reduce the charging current ripple. Meanwhile, to improve the system flexibility and reliability, decentralized control is utilized for individual current-fed dual active bridge converters in view of the battery charging profile. The proposed method along with the presented topology can achieve voltage balance in spite of the power flow direction, simplification of the controller for the dc–dc modules and can also bear unbalanced power flow. The simulation and experimental results have been presented to show the effectiveness of the proposed control.
73 citations
TL;DR: This paper is focused on improving the post-fault performance of cascaded H-bridge multilevel inverters by decreasing the common-mode voltage through an algorithm and a modified technique to calculate the references of inverter phase voltages under faulty conditions.
Abstract: This paper is focused on improving the post-fault performance of cascaded H-bridge multilevel inverters by decreasing the common-mode voltage. First, an algorithm is proposed to determine the optimal post-fault state among all possible states, which have the same maximum available voltage. Furthermore, a modified technique is proposed to calculate the references of inverter phase voltages under faulty conditions. This technique leads to a decrease in the common-mode voltage when the required output voltage is less than its maximum value. These solutions are mutually employed in the post-fault control system. Simulation and experimental results confirm the effectiveness of the proposed solutions in comparison with the existing methods in different cases.
73 citations
TL;DR: This paper quantifies the performance of, and experimentally confirms, the recently proposed delta-connected CHB converter for PV applications as an alternative configuration for large-scale PV power plants.
Abstract: The cascaded H-bridge (CHB) converter is becoming a promising candidate for use in next generation large-scale photovoltaic (PV) power plants. However, solar power generation in the three converter phase-legs can be significantly unbalanced, especially in a large geographically-dispersed plant. The power imbalance between the three phases defines a limit for the injection of balanced three-phase currents to the grid. This paper quantifies the performance of, and experimentally confirms, the recently proposed delta-connected CHB converter for PV applications as an alternative configuration for large-scale PV power plants. The required voltage and current overrating for the converter is analytically developed and compared against the star-connected counterpart. It is shown that the delta-connected CHB converter extends the balancing capabilities of the star-connected CHB and can accommodate most imbalance cases with relatively small overrating. Experimental results from a laboratory prototype are provided to validate the operation of the delta-connected CHB converter under various power imbalance cases.
70 citations
TL;DR: In this paper, the authors proposed a power routing for cascaded H-bridge (CHB) converters, with the purpose of delaying the failure of the system, where a third harmonic injection into the duty cycles allows extending the imbalance capability of the structure.
Abstract: Modular power converters are expected to play a major role in medium- and high-voltage/power applications. Normally, each module processes the same amount of power; however, this does not take into consideration that different modules can have a different remaining useful lifetime. This paper proposes the concept of power routing for cascaded H-bridge (CHB) converters, with the purpose of delaying the failure of the system. A third-harmonic injection into the duty cycles allows extending the imbalance capability of the structure, keeping the CHB operational even if some power paths are completely unloaded. Analytic investigation in conjunction with simulation and experimental measurements demonstrate the power routing by means of the proposed method.
TL;DR: In this article, a double level circuit is proposed to increase the output voltage level to nearly twice that of a conventional cascaded H-bridge multilevel inverter, where phase disposition carriers with sinusoidal reference have been used for generating the gating signal of switches to achieve high quality output voltage waveform.
Abstract: In this study, a new multilevel inverter configuration which introduces a combination of cascaded H-bridge multilevel inverter with a double level circuit is proposed. The double level circuit is a half-bridge inverter when combined with a cascaded H-bridge multilevel inverter, will increase the output voltage level to nearly twice that of a conventional cascaded H-bridge multilevel inverter. The effectiveness of the proposed configuration is demonstrated with five different cases of cascaded H-bridge multilevel inverter configurations. Phase disposition carriers arrangement with sinusoidal reference has been utilised in pulse width modulation for generating the gating signal of switches to achieve high-quality output voltage waveform. A comparison is carried out with different parameters such as %total harmonic distortion, distortion factor, the maximum voltage step of output voltage level and peak inverse voltage. Analysis of power loss and theoretical calculation of %total harmonic distortion is described. Also, a new method for calculating the overall component count is discussed. As a result, the proposed configuration requires lesser component count for generating higher output voltage level with lower %total harmonic distortion. Selected simulation and experimental results are shown to verify and validate the proposed multilevel inverter configuration.
TL;DR: Experimental results based on a 430 V, 10 kW, three-phase, seven-level cascaded H-bridge converter prototype confirm superior performance of the optimal zero-sequence injection technique.
Abstract: Photovoltaic (PV) power generation levels in the three phases of a multilevel cascaded H-bridge (CHB) converter can be significantly unbalanced, owing to different irradiance levels and ambient temperatures over a large-scale solar PV power plant. Injection of a zero-sequence voltage is required to maintain three-phase balanced grid currents with unbalanced power generation. This study theoretically compares power balance capabilities of various zero-sequence injection methods based on two metrics which can be easily generalised for all CHB applications to PV systems. Experimental results based on a 430 V, 10 kW, three-phase, seven-level cascaded H-bridge converter prototype confirm superior performance of the optimal zero-sequence injection technique.
TL;DR: In this paper, the impact of switching harmonics on the instantaneous power distribution in the cells of a cascaded H-bridge-based STATCOM when using phase-shifted pulse width modulation is investigated.
Abstract: The purpose of this paper is to investigate the impact of switching harmonics on the instantaneous power distribution in the cells of a cascaded H-bridge-based STATCOM when using phase-shifted pulse width modulation. The case of high- and low-switching frequency for the converter cells is investigated and the interaction between voltage and current harmonics is analyzed. It is shown that in both cases, this interaction results in an uneven power distribution among the cells in the same phase leg, leading to drifting of the dc-capacitor voltages and thereby the need for proper stabilization control loops. It is also shown that the selected frequency modulation ratio affects the active power distribution among the cells. In particular, the selection of a noninteger frequency modulation ratio helps in providing a more uniform power distribution among cells of the same phase leg, thus contributing to the capacitors balancing. A methodology for optimal selection of the frequency modulation ratio is given. Theoretical conclusions are validated through simulation and experimental results.
TL;DR: The proposed predictive controller belongs to the finite-control-set model predictive control (FCS-MPC) family and is designed to extract unbalanced power from each CHB converter phase while providing balanced power to the grid.
Abstract: This paper presents a predictive control strategy for grid-connected cascaded H-bridge (CHB) converters under unbalanced power generation among each converter phase. The proposed controller belongs to the finite-control-set model predictive control (FCS-MPC) family and is designed to extract unbalanced power from each CHB converter phase while providing balanced power to the grid. The key novelty of this strategy lies in the way the unbalanced power generation among the phases is explicitly considered into the optimal control problem. Power balance is achieved by enforcing the CHB converter to work with a suitable zero-sequence voltage component. The proposed predictive controller is directly formulated in the original $abc$ -framework to account for the common-mode voltage. Simulation and experimental results are provided to verify the effectiveness of the proposed FCS-MPC strategy.
TL;DR: In this article, a multilevel inverter based on three-phase H-bridge inverters for an open-end winding induction motor drive is presented and its fault-tolerance capability is investigated.
Abstract: In this paper, a multilevel inverter based on three-phase H-bridge inverters for an open-end winding induction motor drive is presented and its fault-tolerance capability is investigated. The multilevel topology is obtained using three wye-connected three-phase H-bridge inverters to supply open-end winding induction motors. This topology has the ability to extend the maximum voltage applied to the motor windings up to two times the dc supply voltage of the three-phase inverters. For a given induction motor voltage, the topology allows the use of dc sources with a lower voltage rating. Consequently, faster power semiconductors can be used. This multilevel topology can be directly controlled by modifying known modulation concepts, such as sinusoidal pulse width modulation (PWM). In this study, two sinusoidal PWM modulation techniques will be implemented: the level-shifted carriers (phase disposition) and the phase-shifted modulator. Fault-tolerant operation under an open-switch fault without adding any extra components and without changing the modulation strategy is also proposed, adding fault-tolerant capability to the new topology. Experimental results of this multilevel inverter in normal operation and in fault tolerant mode are presented. The obtained results confirm the fault effectiveness of the proposed multilevel topology.
TL;DR: The proposed single-stage quasi-cascaded H-bridge five-level boost inverter has the advantages over the CHB quasi-Z-source inverter in cutting down passive components and size, cost, and weight of the proposed inverter are reduced.
Abstract: Latterly, multilevel inverters have become more attractive for researchers due to low total harmonic distortion in the output voltage and low electromagnetic interference. This paper proposes a novel single-stage quasi-cascaded H-bridge five-level boost inverter (qCHB-FLBI). The proposed five-level inverter has the advantages over the CHB quasi-Z-source inverter in cutting down passive components. Consequently, size, cost, and weight of the proposed inverter are reduced. Additionally, the proposed qCHB-FLBI can work in the shoot-though state. A capacitor with low voltage rating is added to the proposed topology to remove an offset voltage of the output ac voltage when the input voltages of two modules are unbalanced. Besides, a simple PID controller is used to control the capacitor voltage of each module. This paper presents circuit analysis, the operating principles, and simulation results of the proposed qCHB-FLBI. A 1.2-kVA laboratory prototype was constructed based on a DSP TMS320F28335 to validate the operating principle of the proposed inverter.
TL;DR: In this paper, the delta-connected cascaded H-bridge converter has been applied to compensate flicker and unbalance load to meet power quality requirement, and a dc capacitor voltage-balancing technique for the converter is presented.
Abstract: The delta-connected cascaded H-bridge converter has been applied to compensate flicker and unbalance load to meet power quality requirement. Based on the detailed power analysis, this paper presents a dc capacitor voltage-balancing technique for the converter. This paper also proposes a current limit control technique to avoid overstressing the power semiconductor devices of the converter. The control techniques in this paper are verified in a 220-V, 1-kVA laboratory test bench.
TL;DR: To eliminate the differences of three clustered voltages, a new clustered voltage balancing control is proposed by regulating negative sequence modulation reference voltage in the dq frame and the effectiveness of the proposed control is verified by experimental results.
Abstract: To explore the clustered voltage balancing mechanism of the star-connected cascaded H-Bridge (SCHB) STATCOM, this paper analyzes the relationship between the active power and the control variables—modulation reference voltages in a dq frame through positive and negative sequence component decomposition. The derived relationship in the dq frame reveals that the negative sequence modulation reference voltage is capable of redistributing the active power among three phases and also the SCHB STATCOM features the clustered voltage self-stabilizing without any additional clustered voltage balancing control. To eliminate the differences of three clustered voltages, a new clustered voltage balancing control is proposed by regulating negative sequence modulation reference voltage in the dq frame. Its balancing mechanism is analyzed in detail and a simple implementation is presented as well. The effectiveness of the proposed control is verified by experimental results on a 400 V/15 kvar SCHB STATCOM.
TL;DR: In this article, the voltage balancing strategy to manage the peak current or the modulation index was proposed, and all the asymmetrical grid voltages were considered in the proposed method to satisfy the grid fault operation.
Abstract: As more distributed renewable energy sources are installed in the utility grid, the static synchronous compensators are applied to manage the power factor and the grid voltage in the medium-voltage level of the power system. The cascaded multilevel converter with single-star topology is well applied to this application. The dc-capacitor voltage balancing control is a fundamental issue, and it can be accomplished by negative-sequence current and/or zero sequence voltage injection. Unfortunately, the zero sequence voltage injection increases the risk of over-modulation and the negative-sequence current injection results in high peak current. This paper provides the voltage balancing strategy to manage the peak current or the modulation index. Besides, all the asymmetrical grid voltages are considered in the proposed method to satisfy the grid fault operation. Laboratory test results verify that the proposed method limits the peak current or manages the modulation index during the grid fault operations.
TL;DR: The reliability improvement strategy for newly developed five-level transistor clamped H-bridge-based cascaded inverter is proposed which can be generalised for any number of levels and the proposed fault tolerant strategy does not require any kind of external circuit for maintaining its capacitor voltage in the balanced state.
Abstract: Reduced voltage stress and low-total harmonic distortion are the main causes for such widespread application of multilevel inverters (MLIs) in various industrial sectors. However, reliability is one of the major concerns of MLIs as it uses a large number of switches as compared with two-level inverters. Therefore, a newly developed transistor clamped H-bridge inverter is proposed in the literature which uses a relatively less number of switches and DC sources as compared with cascaded H-bridge but lacks in reliability due to the absence of redundant states. Hence, in this study, the reliability improvement strategy for newly developed five-level transistor clamped H-bridge-based cascaded inverter is proposed which can be generalised for any number of levels. In the proposed fault tolerant strategy, the fault can be broadly classified based on the two main legs of the proposed inverter. Moreover, the proposed fault tolerant strategy does not require any kind of external circuit for maintaining its capacitor voltage in the balanced state. Finally, to validate the concept, a laboratory prototype of the five-level inverter is developed and results are obtained successfully.
TL;DR: In this article, the effect of adding parallel and series reactors on the LC-StatCom system's V-I characteristic is analyzed and a new configuration, which fully compensates for the lost operating area of the system, is introduced.
Abstract: The cascaded H-bridge (CHB) low-capacitance StatCom (LC-StatCom) has a limited operating area in the inductive region compared to a conventional StatCom's V–I characteristic. This limitation for operation in the inductive region is considered to be the biggest disadvantage of CHB LC-StatCom. In this paper, the effect of adding parallel and series reactors on the LC-StatCom system's V–I characteristic is analyzed. Then, a new configuration, which fully compensates for the lost operating area of the LC-StatCom, is introduced. A scaled down single-phase seven-level laboratory prototype is used to confirm practicability of the proposed system.
TL;DR: In this article, a single-phase cascaded H-bridge multi-level active power filter (APF) is proposed to deal with the power quality problems in the AC electric railway systems.
Abstract: A single-phase cascaded H-bridge multi-level active power filter (APF) to deal with the power quality problems in the AC electric railway systems is presented. The APF can connect to the traction busbar directly without any transformer or resonance branch. The direct current control combining the current decoupling transformation is introduced in the control strategy. This strategy simplifies the control system, enabling the least amount of current measurement with the existing sensors and removing complex current reference extraction algorithms. The control system design process, especially for the parameter tuning, is mainly discussed. Finally, simulation and experimental results verify the effectiveness of the proposed APF system applied in the AC electric railway systems.
TL;DR: In this paper, a hybrid modulation technique is introduced that uses SHCM-PWM under steady state and phase-shift PWM (PSPWM) under transient to extend the modulation index range and ensure that SHCM -PWM can process four-quadrant active and reactive power.
Abstract: The selective harmonic current mitigation pulsewidth modulation (SHCM-PWM) technique can be used in cascaded multilevel converters to extend the harmonic reduction spectrum, reduce the coupling inductance and increase the efficiency. The offline SHCM-PWM technique has small number of switching transitions as its switching angles can only change once in a fundamental cycle and relatively long time delays because it uses FFT. As a result, its dynamic response has a lot to desire. As it will be proven in this paper, in four-quadrant power converters, to have a good transient dynamic response, both active and reactive power must be controlled at least two times in a fundamental cycle. In this paper, a hybrid modulation technique is introduced. The proposed technique uses SHCM-PWM under steady state and phase-shift PWM (PSPWM) under transient. In addition, in order to extend the modulation index range and ensure that SHCM-PWM can process four-quadrant active and reactive power, the constraints of the switching angles for the SHCM-PWM are modified. Simulations and experiments are conducted on a seven-level cascaded H-bridge converter to verify the proposed technique.
TL;DR: In this paper, a new configuration of switches for H-bridge multilevel inverter (MLI) to provide five voltage levels as output is presented and two H-Bridges are joined in cascaded fashion to provide output of a nine level inverter.
TL;DR: In this article, the authors identify $PQ$ plane operating points available when using symmetric and asymmetric grid-interactive CHB converter topologies, and determine the factors that prevent utilization of other converter output points.
Abstract: Cascaded H-bridge (CHB) multilevel converters are being considered as a promising option for interfacing renewable energy resources with the grid due to their modularity, scalability, and increased efficiency when compared with traditionally used two-level inverters. When used as grid interfaces, CHB converters should be capable of controlling the injected active and reactive power while also satisfying operating criteria such as grid standards, e.g., IEEE 519. This paper aims to identify $PQ$ plane operating points available when using symmetric and asymmetric grid-interactive CHB converter topologies, and to determine the factors that prevent utilization of other converter output points. Notably, for asymmetric CHB converters, a technique is proposed to identify discordant output points where power is transferred between cells within a leg, e.g., one cell has a net regenerative power flow while the overall CHB leg does not. This work ( i ) provides distribution engineers with information regarding the active and reactive power that can feasibly be generated by grid-interactive CHB converter topologies, ( ii ) creates a framework for assessing operating point trajectories when altering the steady-state operation of grid-tied CHB converters, ( iii ) provides a basis for selecting and modifying steady-state pulse-width modulation generation techniques in order to meet desired performance criteria, and ( iv ) presents analytical techniques that can be built upon to facilitate analysis of grid-interactive CHB under conditions such as grid imbalance or during continued operation after CHB cell faults.
26 Mar 2017
TL;DR: In this article, a single-phase H-Bridge transformerless inverter with common ground for grid-connected photovoltaic systems (Siwakoti-H) is proposed.
Abstract: This paper proposes a new single-phase H-Bridge transformerless inverter with common ground for grid-connected photovoltaic systems (hereafter it is called ‘Siwakoti-H’ inverter) The inverter works on the principle of flying capacitor and consists of only four power switches (two reverse blocking IGBT's (RB-IGBT) and two MOSFET's), a capacitor and a small filter at the output stage The proposed topology share a common ground with the grid and the PV source A Unipolar Sinusoidal Pulse-Width Modulation (SPWM) technique is used to modulate the inverter to minimize switching loss, output current ripple and filter requirements The main advantages of the new inverter topology are the elimination of the leakage current and ability to provide reactive power to the grid Further, the peak of output ac voltage is equal to input dc-voltage (unlike NPC and ANPC type which requires two times of the peak ac-voltage magnitude) Simulation as well as experimental results from a 1 kW prototype are presented at the end of the paper to prove the concept and also the theoretical analysis presented
01 Sep 2017
TL;DR: The cascaded H-bridge multi-level inverter topology quashes the THD and harmonics and is studied in this paper by using MATLAB simulation.
Abstract: The traditional inverters have the drawbacks of Harmonics as well as Total Harmonic Distortion (THD). The analysis of THD and harmonics are studied in this paper by using MATLAB simulation. The cascaded H-bridge multi-level inverter configuration is used. The used configurations contain less number of switches and produce lesser harmonics in the output voltage. The harmonics and THD at the output of cascaded H-bridge inverter of different levels i.e., three-level, five-level, seven-level, nine-level and eleven-level are studied and compared. The cascaded H-bridge multi-level inverter topology quashes the THD and harmonics.
TL;DR: This study presents a comparison of power and energy distribution of three-phase cascaded H-bridge multilevel inverter for the phase-sh shifted and the level-shifted carrier PWM (phase disposition).
Abstract: Among the different multilevel topologies for inverters, cascaded H-bridge multilevel topology has been a good solution for high-power medium-voltage applications because of its modularity structure, voltage balancing, separated DC sources, harmonics reduction, reliability and lower stresses on switching devices. The most widely used pulse width modulation (PWM) techniques for cascaded H-bridge multilevel inverter are known as phase shifted and level shifted. This study presents a comparison of power and energy distribution (inter-phase and inter-bridge power and energy) of three-phase cascaded H-bridge multilevel inverter for the phase-shifted and the level-shifted carrier PWM (phase disposition). A detailed comparison of different PWM techniques with reference to total harmonic distortion in the output voltages, both cases using a filter and without filter are presented also in this study. Simulation for 11-level cascaded H-bridge inverter is carried out in MATLAB/SIMULINK and simulation results are presented.
Journal Article•
TL;DR: An overview and an experimental validation of the MC SPWM techniques for a three-phase, five-level, cascaded H-Bridge inverter with FPGA controller-based is presented.
Abstract: The FPGA represents a valid solution for the design of control systems for inverters adopted in many fields of power electronics because of its high flexibility of use. This paper presents an overview and an experimental validation of the MC SPWM techniques for a three-phase, five-level, cascaded H-Bridge inverter with FPGA controller-based. Several control algorithms are implemented by means of the VHDL programming language and the output voltage waveforms obtained from the main PWM techniques are compared in terms of THD%. Simulation and experimental results are analyzed, compared and discussed.