Simulation and implementation of FPGA based hybrid asymmetric multilevel inverter

This work focuses on proposing a new structure for asymmetric multilevel inverter. In the proposed topology, a switched capacitor (SC) and conventional series inverter are combined and connected in cascade. The proposed multilevel inverter finds its application in photovoltaic inverters which has numerous advantages. Firstly, it converts power for AC requirements from comparatively low DC voltage sources and with lower number of switching devices. Second, with the removal of transformers normally used for stepping up the voltage of each inverter stage the weight, volume and size of the whole system is reduced as the proposed topology can double the input voltage without a transformer. Symmetrical step control method (SSCM) and fundamental switching frequency method (FSFM) are applied to this proposed topology to actuate the power electronic switches for effective control and monitoring of voltage levels generated at the output. The simulation is executed using MATLAB/SIMULINK software. It was found that FSFM modulation technique results in a lower value of Total Harmonic Distortion (THD). The switching strategy is implemented with an FPGA device for the experimental prototype. The simulation and experimental result of single-phase 25-level inverter is given to demonstrate the precise operation of the suggested topology

Asymmetric Cascaded Multilevel Inverter with Unequal Dc Sources using SPWM and MSVPWM Topologies

This paper introduces the modeling design and simulation of seven and thirteen levels cascaded asymmetric multilevel inverter (MLI) with reduced number of switches.  MLI is the most efficient energy converters which are essentially appropriated for high power applications with decrease total harmonics distortion (THD). MLI doesn't only get high power in the output but it is also utilized in renewable energy resources such as fuel cells, wind and photovoltaic cells. This paper principally focuses on a hybrid cascaded MLI with two and three unequal dc supplies which decreases the number of semiconductor power switches. Sinusoidal PWM (SPWM) and modified space vector PWM (MSVPWM) techniques are used to improve an ac output with reduced THD. The gating pulses for seven and thirteen level hybrid cascaded converter using SPWM and MSVPWM techniques are introduced. The results of these proposed modulation strategies reduce the percentage magnitude of THD. The performance of the proposed SPWM and MSVPWM topologies are verified using seven and thirteen levels cascaded asymmetric MLI via simulink/matlab. Keywords: Sinusoidal Pulse Width Modulation (SPWM), Modified Space Vector Pulse Width Modulation (MSVPWM), Multilevel Inverter (MLI), Total Harmonics Distortion (THD)

Comparative performance of modular with cascaded H-bridge three level inverters

The conventional two-level inverter becomes no longer has the ability to cope with the high-power requirement, so this paper discusses two very common topologies of multilevel inverter like modular multi-level converter (MMC) and cascaded H-bridge (CHB) multi-level inverter for induction motor drive applications. This work attempts to investigate the comparison between MMC and CHB. The comparison is done in aspects of the configuration, concept of operation, advantages and disadvantages, the comparison is also consider output voltage (line to line) waveform, total harmonic distortion (THD) of the output line voltage waveform and the current drawn by both inverters. The performance of the inverters under carrier-based pulse width modulation (PWM) technique and mainly in-phase disposition (IPD), level shifted pulse width modulation is viewed. The paper discusses the comparison between the two multilevel inverters (MLIs) with motor drive applications especially induction motor. The operation of the motor is studied under certain value of load torque. The simulation results for the induction motor with the two inverters (modular multi-level and Cascaded H-bride) for three numbers of levels using MATLAB/Simulink are provided). The obtained results are encouraging and promising especially in the improvement of the THD% results

A Novel Hybrid Single-Phase Modular Multilevel Inverter Topology with Enhanced Number of Levels per Number of Devices

Inverters are important in the electrical industry, and there have been several advancements in this area. One of these is the multilevel inverter. A new single-phase inverter with seventeen levels is suggested in this study. To spread the load, the DC inputs will be paired in series/parallel. To generate a wider number of output level voltages, a combination of switching devices and DC sources will be utilized. The harmonic components will be lowered by employing the new modulation approach. THD rate analysis for eleven level and seventeen level structure is performed, and THD quality enhancement can be shown herein. The simulation of suggested multilevel converter is performed in Matlab/Simulink.Peer reviewe

A new boost switched capacitor seven-level grid-tied inverter

In this paper, a new switched capacitor-based multilevel inverter structure is suggested. The proposed topology can generate seven-level output voltage waveform using ten power electronic switches and two floating capacitors. This structure has the ability to boost the input DC voltage, up to 1.5 times. Although this topology can generate an output waveform with large number of levels, it does not increase the voltage stress on the power electronic switches. There is no need for capacitor voltage balancing in this structure since the capacitors are balanced through charging and discharging modes of operation. In addition, the suggested switched capacitor inverter reduces the number of input dc power supplies and uses a single dc source such as a photovoltaic (PV) panel. Since the proposed inverter is an neutral point clamp based multilevel inverter topology, the leakage current is minimized and as a result the overall efficiency of the proposed system is increased. The operation modes and steady-state analysis of the proposed structure are explained in detail. In order to validate the feasibility of the proposed topology, some experimental results are presented in the grid connected mode of operation

A modular switched-capacitor multilevel inverter featuring voltage gain ability

This paper proposes a modular switched-capacitor multilevel inverter with single dc source, which can obtain triple voltage gain by using two capacitors. It is worth noting that the inherent inversion capacity eliminates the Hbridge, which can effectively reduce the voltage stress of switches, and the maximum voltage stress (MVS) of all switches is kept within 2Vdc. In addition, the proposed inverter is able to integrate inductive load, and the capacitor voltage self-balancing can be achieved without any auxiliary circuits. Moreover, the modular inverter also has expandable structure which can generate more output levels and raise the voltage gain by employing multiple switchedcapacitor cells, meanwhile the MVS for all of the switches is kept within 2Vdc in the extended structure. Furthermore, comprehensive analysis and comparison with other multilevel inverter have been implemented to evaluate the superiority of the proposed topology. Finally, the steadystate and dynamic performance of the proposed inverter is validated through a seven-level inverter prototype, the correctness and feasibility of the proposed topology are verified by simulations and experiments