Hybrid Cascaded Multilevel Inverter Research Articles

Hybrid Cascaded Inverter-Based Integrated Hybrid Power Supply Using Nonconventional Energy Sources

In this research, a hybrid integrated topology that would work very well for applications involving distribution generation has been suggested. The Photovoltaic and Fuel Cell source are used to power the hybrid integrated topology's power supply. Photovoltaic source is utilized as the main power and runs very near to its Maximum Power Point, while the fuel cell section serves merely as a DC supply and feeds just the power that is needed to make up the difference. The integrated approach improves the overall power level that is supplied because of the presence of the fuel cell in parallel with the photovoltaic source. This may be achieved by smoothing out the voltage stress that are brought by the photovoltaic system's output. Another important characteristic is that the load may be fuelled by photovoltaic energy in any quantity, even if that quantity is relatively low. This is a feasible regardless of the size of the photovoltaic system. In addition, excess power may be sent to the electrolysis load, which results in the source of energy being used in the most effective manner possible. When converting voltages, a Hybrid Cascaded Multilevel Inverter (HCMI) topology is preferred over a conventional three phase inverter because it has the advantages of a gradual decrease in switching losses, a low total harmonic distortion, and a minimum power loss. This in comparison to the conventional three phase inverter, has none of these advantages. In addition to that, the voltages might be converted in a more effective way using this design. The suggested system has a number of desirable qualities, and the most notable are its low operational costs, its user-friendly layout, and its high level of durability.

Field programmable gate array-based new fusion control for photovoltaic inverter

This paper proposes a new fusion of digital controls for Photovoltaic (PV) fed DC-DC-AC inverter. The proposed PV-DC-DC-AC design includes the control for voltage regulation of the closed-loop buck converter by combining two duty cycles of Digital Proportional Integral-Digital Pulse Width Modulation (DPI-DPWM) and Maximum Power Point Tracking (MPPT) for one of the DC supply (9V) of the 81-level Trinary Cascaded Hybrid Multi-Level Inverter (TCHMLI). The control for the DC-DC converter is provided by the DPWM techniques, and the TCHMLI requires 16 switching patterns that are to be controlled by the Half Height-Switching Angle Method (HH-SAM). The real-time implementation for the proposed fusion control is verified with a resolution of 28 and 210 bits and validated using Field Programmable Gate Array (FPGA). The hardware result of the proposed photovoltaic inverter is compared with the existing methods and proves to be feasible.

A Three-Phase Hybrid Cascaded Multilevel Inverter with Multicarrier PWM technique

Multilevel voltage source inverter has drawn tremendous importance in the area of high power applications. This paper presents a three-phase modified hybrid cascaded multilevel inverter incorporating a standard three-leg inverter with H-bridge cells in series with each leg. The switching scheme with the multicarrier level shifted sinusoidal PWM is implemented to produce the five-level voltage at the output. Simulations have been performed using MATLAB to study voltage levels, modulation scheme, and THD. Finally, the possibilities of future works are addressed.

Harmonic Reduction in Hybrid Cascaded Multilevel Inverter Using Modified Grey Wolf Optimization

This article proposes a modified grey wolf optimization (MGWO) which has improved rate of convergence and avoids local optima stagnation. This is achieved by improving the exploration-exploitation balance in conventional grey wolf optimization (GWO). Moreover, the use of weighted-distance strategy allows quick identification of the global optima in the proposed MGWO. This optimization is then applied for the control of a three-phase, 11-level hybrid cascaded multilevel inverter (HC-MLI). Selective harmonic elimination pulsewidth modulation technique is implemented through MGWO which generates optimal switching angles for the HC-MLI so as to eliminate lower order harmonics such as 5th, 7th, 11th, and 13th from the output voltage. In MGWO optimized HC-MLI, balancing of capacitor voltage is made possible at higher modulation index by making use of the available redundant switching states. The performance of the proposed work is validated through simulation and experimentation on a 1.5 kW prototype. The results obtained through simulation show that the MGWO algorithm is more efficient and accurate than other reported algorithms such as GWO, genetic algorithm, and particle swarm optimization in terms of performance, harmonic reduction, and convergence rate.

Harmonic Minimization in Three-Phase Hybrid Cascaded Multilevel Inverter Using Modified Particle Swarm Optimization

This paper proposes a modified particle swarm optimization (MPSO) for fast convergence and harmonic minimization in three-phase eleven-level hybrid cascaded multilevel inverter (HC-MLI). Selective harmonic elimination pulsewidth modulation (SHE-PWM) technique implemented through MPSO has been used in the proposed work for synthesizing an eleven-level output voltage using two dc sources, a precharged capacitor, and twelve switches. The switching angles of the three-phase eleven-level HC-MLI has been computed for eliminating specified lower order odd harmonics such as 5th, 7th, 11th, and 13th from the output voltage of the HC-MLI. In the proposed MPSO optimized HC-MLI, capacitor voltage balance is also ensured even at higher modulation indices by utilizing the redundant switching states available at different switching instances of the HC-MLI. The performance of the MPSO optimized three-phase eleven-level HC-MLI has been verified through simulation and experimentation on a 1.5-kW prototype using closed-loop control. The results obtained through MPSO are compared with the results obtained through genetic algorithm (GA) and particle swarm optimization (PSO) in terms of convergence rate and harmonic content. It has been found that MPSO gives improved results in comparison to GA and PSO.

Cascaded Hybrid Multi-level Inverter for Selective Harmonics Elimination

This paper aimed at the prospect of an optimized algorithm for Selective Harmonic Elimination (SHE) through a hybrid control mechanism using fmincon and Newton–Raphson iterative method. In search of minimizing the Total Harmonic Distortion (THD), appropriate multi-level sequences and firing angles are used. This technique not only reduces the execution time but also improves the convergence rate. MATLAB simulations confirm that the algorithm is robust and the desired response is achieved within a few iterations for any range of modulation index. PSpice simulation verifies the successful removal of harmonics and confirms THD lies within limits specified by IEEE 519 standard. The implementation of this SHEPWM algorithm will improve the working of cascaded multi-level inverters by increasing their efficiency rate with respect to their speed.

Hybrid Cascaded Multilevel Inverter (HCMLI) With Improved Symmetrical 4-Level Submodule

This letter proposes an improved symmetrical 4-level submodule as a basic cell for generating multiple dc voltage levels. A hybrid cascaded multilevel inverter (HCMLI) topology is formed by the combination of n submodules and a full-bridge. A comparative analysis against the recent multilevel inverters reveals that the proposed topology requires less number of switches and dc sources. In addition, the proposed submodule reduces the number of conducting switch and gate driver requirements compared to the widely used half-bridge submodule. To validate the operation of the proposed HCMLI topology, experimental results of a 9-level single-phase inverter controlled by selective harmonic elimination pulse-width-modulation is presented.

On Optimization of Manufacturing of Transistors in Hybrid Cascaded Multilevel Inverter to Increase Their Density

On Optimization of Manufacturing of Transistors in Hybrid Cascaded Multilevel Inverter to Increase Their Density

A Hybrid Cascaded Multilevel Inverter with Diode Assisted Boosting Network

This paper investigates a diode assisted cascaded H-bridge multilevel inverter to serve as an alternative to the traditionally available pulse width modulated inverters for large hybrid electric vehicle (HEV) drive train applications. This research extends earlier work which involved constant equal dc sources with invariant behaviour to include variable dc sources which improves its voltage transfer ratio and the voltage rating of the capacitors is thus reduced. The implemented diode assisted cascaded H-bridge MLI uses lower power rated switches, can be used for active as well as reactive power compensation and contains less number of switching devices and isolated DC sources. The proposed method results in equalized current stresses across all the components. A modified carrier-cascaded PWM method is used to accomplish the control of the inverter and equalization of voltage. Investigation of the total harmonic distortion is done for a wide range of possible output control voltages and a number of voltage levels are used to obtain the desired waveform.. Theoretical analysis is verified by simulation in MATLAB/Simulink environment and experimental implementation.

Hardware Implementation of Cascaded Hybrid Multilevel Inverter with Reduced Number of Switches

<p class="JESTECAbstract">This paper presents the comparison of various multicarrier Pulse Width Modulation (PWM) techniques for the Cascaded Hybrid Multi Level Inverter (CHBMLI). Due to switch combination redundancies, there are certain degrees of freedom to generate the five level AC output voltage. This paper presents the use of Control Freedom Degree (CFD) combination. The effectiveness of the PWM strategies developed using CFD are demonstrated by simulation and experimentation. The simulation results indicate that the chosen five level inverter triggered by the developed Phase Disposition(PD), Phase Opposition and Disposition(POD), Alternate Phase Opposition and Disposition (APOD), Carrier Overlapping (CO), Phase Shift (PS) and Variable Frequency (VF)<strong> </strong>PWM strategies developed are implemented in real time using FPGA. The simulation and experimental outputs closely match with each other validating the strategies presented.</p>

A Predictive Capacitor Voltage Control of a Hybrid Cascaded Multilevel Inverter With a Single DC-Link and Reduced Common-Mode Voltage Operation

For cascaded multilevel inverter topologies with a single dc supply, closed-loop capacitor voltage control is necessary for proper operation. This paper presents zero and reduced common-mode voltage (CMV) operation of a hybrid cascaded multilevel inverter with predictive capacitor voltage control. Each phase of the inverter is realized by cascading two- three-level flying capacitor inverters with a half-bridge module in between. For the presented inverter topology, there are redundant switching states for each inverter voltage levels. By using these switching state redundancies, for every sampling instant, a cost function is evaluated based on the predicted capacitor voltages for each phase. The switching state that minimizes cost function is treated as the best and is switched for that sampling instant. The inverter operates with zero CMV for a modulation index upto 86%. For modulation indices from 86% to 96%, the inverter can operate with reduced CMV magnitude ( $V_{\rm dc}/18$ ) and reduced CMV switching frequency using the new space-vector pulsewidth modulation (SVPWM) presented herein. As a result, the linear modulation range is increased to 96% as compared to 86% for zero CMV operation. Simulation and experimental results are presented for the inverter topology for various steady state and transient operating conditions by running an induction motor drive with open loop $V/f$ control scheme.

Prediction of a New Cascaded Hybrid Multilevel Inverter with Less Device Count

<p>Multilevel inverters have been opted for high power applications due to reduced harmonic distortion, less device voltage stress and modular structure. This work proposes new modified hybrid H-bridge multilevel inverter using auxiliary switch. This proposed inverter produces five levels output with five power devices and clamping diodes as a phase voltage and nine levels as a line voltage.The levels of the inverters are decided based on the phase voltage not on the line voltage. In this paper the performance of the proposed inverter are measured in terms of line voltage. However, by increase in the number of levels the proposed inverter with reduced number of switches produces low switching losses and improves the efficiency of the inverter. This method achieves the variation of Total Harmonic Distortion (THD) in the inverter and output voltage is observed for various modulation indices. Simulation is performed using MATLAB-SIMULINK for line to line output voltage. Variable Amplitude Phase Disposition (VAPD) strategy provides output with relatively low distortion for all the strategies. It is also seen that VAPOD is found to perform better for all strategies since it provides relatively higher fundamental RMS output voltage.</p>

A Cascaded Hybrid Multilevel Inverter Incorporating a Reconfiguration Technique for Low Voltage DC Distribution Applications

A cascaded hybrid multilevel inverter including a reconfiguration technique for low voltage dc distribution applications is proposed in this paper. A PWM generation fault detection and reconfiguration paradigm after an inverter cell fault are developed by using only a single-chip controller. The proposed PWM technique is also modified to reduce switching losses. In addition, the proposed topology can reduce the number of required power switches compared to the conventional cascaded multilevel inverter. The proposed technique is validated by using a 3-kVA prototype. The switching losses of the proposed multilevel inverter are also investigated. The experimental results show that the proposed hybrid inverter can improve system efficiency, reliability and cost effectiveness. The efficiency of proposed system is 97.45% under the tested conditions. The proposed hybrid inverter topology is a promising method for low voltage dc distribution and can be applied for the multiple loads which are required in a data center or telecommunication building.

Modeling and Analysis of Variable Frequency Inverted Sine PWM Technique for a Hybrid Cascaded Multilevel Inverter

In cascaded H-bridge multilevel inverter, a variable frequency inverted sine PWM technique is modeled for hybrid electric vehicles. It has a particular advantage of increasing power which is achieved using series connection of H-bridge and also this topology is capable to produce superior spectral quality with considerable improvement of fundamental voltage. The variable frequency inverted sine PWM technique produces lesser torque ripple and enhances the fundamental output voltage mainly at lower modulation index ranges. The topologies of multilevel inverter are flying capacitor, diode clamped and cascaded inverter. In the paper, we will discuss about the cascaded multilevel inverter based on inverted sine PWM technique. The two switching strategies widely used to control multilevel inverters are constant frequency inverted sine PWM (CF-ISPWM) and variable frequency inverted sine PWM (VF-ISPWM). This implies that switch utilization substantially reduces 32.35% of the constant frequency inverted sine PWM switching technique. The performance of the technique is validated in terms of Total Harmonic Distortion (THD) and Torque ripple which significantly reduces when compared to constant frequency ISPWM. The analysis of conventional triangular PWM inverter and inverted sine PWM inverter using constant and variable switching scheme is done in MATLAB Simulink and verified experimentally by FPGA Spartan 3E processor.

Modified Cascaded Multilevel Grid-Connected Inverter to Enhance European Efficiency and Several Extended Topologies

This paper proposes a modified cascaded multilevel grid-connected inverter (MCM-GCI) suitable for photovoltaic grid-connected generation system, which considers wide operation range, low grid current total harmonics distortion (THD), and high European efficiency. In the proposed topology, a bidirectional power switch is added to the standard single-phase cascaded multilevel inverter (CMI) to implement the transformation between CMI mode and H-bridge inverter (HBI) mode. An online topology transformation approach of the MCM-GCI is proposed to guarantee the topology modes transformed safely and smoothly. The proposed MCM-GCI operates in CMI mode when the PV arrays’ output voltage and power are low, and transforms into HBI mode when the PV arrays’ output voltage and power are high. Experimental results of five-level MCM-GCI are represented to validate the feasibility of the proposed topology and it is also compared with other three classic grid-connected inverters to highlight its advantages. Furthermore, more structures based on hybrid CMI, which possess the topology transformation ability, are shown to further improve the generation range and obtain a higher efficiency of the system.

A Novel Quadrant Search Based Mitigation Technique for DC Voltage Fluctuations in Multilevel Inverters

The hybrid cascaded multilevel inverter (HCMLI) is a popular converter topology that is being increasingly used in high power medium voltage drives. The intricacy of the control technique for a HCMLI increases with the number of levels and due to fluctuating dc voltages. This paper presents a novel offline quadrant search based space vector modulation technique to synthesize a sinusoidal output from a dispersed pattern of voltage vectors due to different voltages in the auxiliary unit. Such an investigation has never been reported in the literature and it is being attempted for the first time. The method suggested distributes the voltage vectors for a reduced total harmonic distortion at minimal computation. In addition, the proposed algorithm determines the maximum modulation index in the linear modulation range in order to synthesize a sinusoidal output for both normal and abnormal vector patterns. It is better suited for a wide range of practical applications. It is particularly well suited for renewable source fed inverters which utilize large capacitor banks to maintain the dc link, which are prone to such slow fluctuations. The proposed quadrant search space vector modulation technique is simulated using MATLAB/SIMULINK and implemented using a Nexys-2 Spartan-3E FPGA for a developed prototype.

Simulation of Fuzzy Logic Controller for PEM Fuel Cell Based Hybrid Cascaded Multilevel Inverter

The power generated in a proton exchange membrane fuel cell based system depends on the hydrogen and oxygen flows, the regulation of pressure and management of water and heat .One of the important operating variable is the reactant utilization which is directly proportional to fuel cell stack current. When a load is connected to the fuel cell system, the control system must control the flow rate of hydrogen in order to avoid degradation of fuel cell (FC) voltage. Therefore, the objective of the paper is to regulate the input fuel flow to achieve the desired output power. Various control strategies proposed in the literature do not consider the dynamic model of fuel cell system and fuel flow controller. This paper presents the development of fuzzy logic controller for fuel cell based Hybrid Cascaded MultiLevel Inverter(MLI). A MATLAB/SIMULINK control structure for the overall FC based system has been presented which includes the local fuzzy controllers for Interleaved Boost Converter (IBC), HCMLI and the fuel cell. The performance has been compared with PI controller.

Fuel cell Powered Hybrid Cascaded Multilevel Inverter Applied To Induction Machine

Fuel cell Powered Hybrid Cascaded Multilevel Inverter Applied To Induction Machine

81 Levels Trinary Hybrid Cascaded Multilevel Inverter

Multilevel inverters are increasingly used in medium and high power applications owing to advantages such as modularity, low power dissipation on switching devices and reduced harmonic distortion at the output of the inverter. The MLI structure used in this paper incorporates four H-bridges cascaded together with trinary mode of selection of dc power supply that facilitates 81 levels of output voltage. The designed 81 level Trinary Hybrid Cascaded Multilevel Inverter (THCMLI) uses bipolar multi-carrier pulse width modulation strategy. The performance quality in terms of THD, crest factor, form factor, and power distortion factor are evaluated for different modulation indices. From simulated results it is observed that the THD of the 81level is reduced satisfactorily in POD PWM and power distortion is reduced in PD PWM strategy and high RMS value of output voltage is achieved in APOD PWM strategy when compared with other strategies with FAFF and FAVF for THCMLI. Increased number of voltage levels upto 81 levels in the output waveform is obtained shows the improved quality and nearness to sinewave with sixteen switches.

Energy Management system for Hybrid RES with Hybrid Cascaded Multilevel inverter

In this paper, we propose an energy management system with hybrid solar and wind renewable energy system (RES) with Multilevel inverter to give a lossless power to load. This system continuously receives the battery storage and power consumption after it checks the these value with default value if power consumption is exceeds default value means it turn off the loads. We are assigns the priority to the loads in order to overcome the user inconvenient. To increase PV module output MPPT is used. The existing system uses only boost converter, in our paper boost converter is combined with buck converter used because the PV module can produce high voltage than DC-bus voltage. Buck converter used to step down purpose. In this system on-line configuration check and buck-boost mode transition will be presented. Experimental results measured from three-string MPPTs with EMS the maximum power level of 10 kW are used to verify the analysis and discussion with hybrid cascaded multilevel inverter. DOI: http://dx.doi.org/10.11591/ijece.v4i1.4529