scispace - formally typeset
Search or ask a question
Journal ArticleDOI

A Novel Asymmetrical 21-Level Inverter for Solar PV Energy System With Reduced Switch Count

TL;DR: In this article, a novel asymmetric 21-level multilevel inverter topology for solar PV application is presented, where the PV voltage is boosted over the DC link voltage using a three-level DC-DC boost converter interfaced in between the solar panels and the inverter.
Abstract: This article presents a novel asymmetrical 21-level multilevel inverter topology for solar PV application. The proposed topology achieves 21-level output voltage without H-bridge using asymmetric DC sources. This reduces the devices, cost and size. The PV standalone system needs a constant DC voltage magnitude from the solar panels, maximum power point tracking (MPPT) technique used for getting a stable output by using perturb and observe (P&O) algorithm. The PV voltage is boosted over the DC link voltage using a three-level DC-DC boost converter interfaced in between the solar panels and the inverter. The inverter is tested experimentally with various combinational loads and under dynamic load variations with sudden load disturbances. Total standing voltage with a cost function for the proposed MLI is calculated and compared with multiple topologies published recently and found to be cost-effective. A detailed comparison is made in terms of switches count, and sources count, gate driver boards, the number of diodes and capacitor count and component count level factor with the same and other levels of multilevel inverter and found to be the proposed topology is helpful in terms of its less TSV value, devices count, efficient and cost-effective. In both simulation and experimental results, total harmonic distortion (THD) is observed to be the same and is lower than 5% which is under IEEE standards. A hardware prototype is implemented in the laboratory and verified experimentally under dynamic load variations, whereas the simulations are done in MATLAB/Simulink.

Content maybe subject to copyright    Report

Citations
More filters
Journal ArticleDOI
TL;DR: In this paper , a new single-phase asymmetrical multilevel inverter (MLI) that can generate 33 levels at the output with fewer components and lower total standing voltage (TSV) at the switches is presented.
Abstract: Multilevel inverters with a high device count, low boosting and DC voltage imbalance are all common problems exists in the traditional topologies. In this article, a new single-phase asymmetrical multilevel inverter (MLI) that can generate 33 levels at the output with fewer components and lower total standing voltage (TSV) at the switches is presented. The multiple input sources of the proposed inverter make it suited for the use in renewable energy generating systems which have a variety of DC sources. The stress distribution among the switches is investigated that reduces the use of high rated devices with which overall cost of the inverter gets reduced. The topology can be extended by adding the circuits in series for higher levels. The performance of the inverter is calculated considering a variety of critical parameters such as TSV, cost function (CF), power loss, and efficiency calculations. The MLI is tested under dynamic load conditions with sudden load disturbances with a range of combinational loads and it has been determined to be stable throughout its operation. A detailed comparison is made based on stress across the switches, stress distribution, switches count, DC sources count, gate driver circuits, component count factor, TSV, CF, and other existing topologies using graphical representations and shown to be cost-effective and superior in all aspects. The total harmonic distortion (THD) derived from simulation and experiment complies with IEEE standards. The proposed framework has been developed in MATLAB/Simulink and tested in a laboratory environment with hardware.

9 citations

Journal ArticleDOI
TL;DR: In this paper , the authors proposed two types of FPGA-based digital switching controllers, namely selective harmonic elimination (SHE) and sinusoidal pulse width modulation (SPWM), for a 21-level multilevel inverter.
Abstract: Multilevel inverters are a type of power electronic circuit that converts direct current (DC) to alternating current (AC) for use in high-voltage and high-power applications. Many recent studies on multilevel inverters have used field-programmable gate arrays (FPGAs) as a switching controller device to overcome the limitations of microcontrollers or DSPs, such as limited sampling rate, low execution speed, and a limited number of IO pins. However, the design techniques of most existing FPGA-based switching controllers require large amounts of memory (RAM) for storage of sampled data points as well as complex controller architectures to generate the output gating pulses. Therefore, in this paper, we propose two types of FPGA-based digital switching controllers, namely selective harmonic elimination (SHE) and sinusoidal pulse width modulation (SPWM), for a 21-level multilevel inverter. Both switching controllers were designed with minimal hardware complexity and logic utilisation. The designed SHE switching controller mainly consists of a four-bit finite state machine (FSM) and a 13-bit counter, while the SPWM switching controller employs a simple iterative CORDIC algorithm with a small amount of data storage requirement, a six-bit up-down counter, and a few adders. Initially, both digital switching controllers (SHE and SPWM) were designed using the hardware description language (HDL) in Verilog codes and functionally verified using the developed testbenches. The designed digital switching controllers were then synthesised and downloaded to the Intel FPGA (DE2-115) board for real-time verification purposes. For system-level verification, both switching controllers were tested on five cascaded H-Bridge circuits for a 21-level multilevel inverter model using the HDL co-simulation method in MATLAB Simulink. From the synthesised logic gates, it was found that the designed SHE and SPWM switching controllers require only 186 and 369 logic elements (LEs), respectively, which is less than 1% of the total LEs in an FPGA (Cyclone IV E) chip. The execution speed of the SHE switching controller implemented in the FPGA (Cyclone IV E) chip was found to be a maximum of 99.97% faster when compared with the microcontroller (PIC16F877A). The THD percentage of the 21-level SHE digital switching controller (3.91%) was found to be 37% less than that of the SPWM digital switching controller (6.17%). In conclusion, the proposed simplified design architectures of SHE and SPWM digital switching controllers have been proven to not only require minimal logic resources, achieve high processing speeds, and function correctly when tested on a real-time FPGA board, but also generate the desired 21-level stepped sine-wave output voltage (±360 VPP) at a frequency of 50 Hz with low THD percentages when tested on a 21-level cascaded H-Bridge multilevel inverter model.

8 citations

Journal ArticleDOI
TL;DR: A comprehensive overview of recently developed multilevel inverters and a solution for developing the MLIs for future research on renewable energy applications is provided in this article , where the design and functioning of each topology as well as each group are examined in this study.

8 citations

Proceedings ArticleDOI
21 May 2021
TL;DR: In this article, the authors analyze the multilevel inverters (MLI) topologies into two categories which are symmetric and asymmetric configuration which contain the reduced number of switches.
Abstract: Multilevel inverters (MLIs) are extremely influential in renewable energy systems, are used to convert DC power into AC. MLIs are more beneficial in comparison to the two-level conventional inverter in terms of lower total harmonic distortion (THD), lesser electromagnetic interference (EMI), increases the capability of fault tolerance, and are more efficient. The major aspect of this review article is to analyze the recent (MLI) topologies into two categories which are symmetric and asymmetric configuration which contains the reduced number of switches $(\mathrm{N}_{\mathrm{S}\mathrm{W}})$. currently, Researchers have an eye on the using reduced number of components in MLI topologies for lesser voltage stress and high efficiency. Performance parameters such as total standing voltage (TSV), THD, and modulation techniques are briefly discussed in this article. furthermore, the general comparison of these topologies is depicted in tabular & graphical representation based on the required number of switches, number of the gate drivers $(\mathrm{N}_{\mathrm{G}\mathrm{D}})$, Number of dc voltage sources $(\mathrm{N}_{\mathrm{D}\mathrm{C}})$, THD, and the number of level $(\mathrm{N}_{\mathrm{L}})$ that are obtained through the multilevel inverter topologies.

7 citations

References
More filters
Journal ArticleDOI
TL;DR: A model-predictive-based controller with a fixed step that is combined with the traditional incremental conductance (INC) method improves the speed at which the controller can track rapid changes in solar insolation and results in an increase in the overall efficiency of the PV system.
Abstract: This study presents a high-efficient maximum power point tracking (MPPT) of photovoltaic (PV) systems by means of model-predictive control (MPC) techniques that is applied to a high-gain DC-DC converter. The high variability and stochastic nature of solar energy requires that the MPPT control continuously adjust the power converter operating point in order to track the changing maximum power point; a concept well known in the literature. The main contribution of this study is a model-predictive-based controller with a fixed step that is combined with the traditional incremental conductance (INC) method. This technique improves the speed at which the controller can track rapid changes in solar insolation and results in an increase in the overall efficiency of the PV system. The controller speeds up convergence since MPC predicts error before the switching signal is applied to the high-gain multilevel DC-DC converter and thus is able to choose the next switch event to minimise error between the commanded and actual converter operation. Comparing the proposed technique to the conventional INC method shows substantial improvement in MPPT effectiveness and PV system performance. The performance of the proposed MPC-MPPT is analysed and validated experimentally.

73 citations

Journal ArticleDOI
TL;DR: In this paper, the performance of new Extremum Seeking Control scheme which has two adaptive control loops: (1) the searching loop locates the global maximum power point by sweeping the photovoltaic pattern based on an asymptotic dither; (2) the tracking loop finds and tracks accurately the Global Maximum Power Point based on similar loop used in Perturbed-based extremum seeking control schemes proposed in the literature.

72 citations

Journal ArticleDOI
TL;DR: In this article, a hybrid cascade multilevel inverter (HCFMLI) topology with bottom standard three-leg and H-bridge cells is introduced for various objectives, such as minimum number of switches and capacitors, and minimum standing voltage on switches for producing maximum output voltage steps.
Abstract: This paper introduces a hybrid cascade multilevel inverter (HCFMLI) topology with bottom standard three-leg and H-bridge cells. The optimal structures of HCMLI are investigated for various objectives, such as minimum number of switches and capacitors, and minimum standing voltage on switches for producing maximum output voltage steps. The suggested topologies introduced herein are most reliable and cost effective when compared with other multilevel based architectures. The operation and performance of the suggested HCMLI's has been verified by the simulation and prototype verifications. Finally, adequate results are presented to confirm the findings.

63 citations

Journal ArticleDOI
25 May 2018-Energies
TL;DR: In this paper, a modified Perturb & Observe (P&O) maximum power point tracking (MPPT) algorithm using fuzzy logic-based variable step size was proposed to overcome some of the limitations associated with the conventional P&O MPPT tracking method.
Abstract: This paper presents a Modified Perturb & Observe (P&O) Maximum power point tracking (MPPT) algorithm using fuzzy logic-based variable step size to overcome some of the limitations associated with the conventional P&O MPPT tracking method to improve the transient response and reduce the steady-state terminal voltage oscillations. The proposed MPPT algorithm was implemented and tested on an indoor emulated PV source that is constructed from a conventional solar panel and a DC power supply, a boost DC-DC converter and a dSPACE-based MPPT controller. The advantage of implementing this testing platform for MPPT is easy implementation and indoor testing of MPPT algorithms and DC-DC power converters. Thus, dependency on atmospheric conditions such as irradiance level can be avoided. Details of the emulated PV source mathematical model and electrical characteristics, the proposed MPPT algorithm via dSPACE, simulation and test results were presented in the paper.

61 citations

Journal ArticleDOI
TL;DR: A comparative review between different algorithms for maximum power point (MPP) tracking is presented, particularly focusing on Numerical Method (NM) techniques, which have been neglected by most of the MPPT review papers.
Abstract: A comparative review between different algorithms for maximum power point (MPP) tracking is presented, particularly focusing Numerical Method (NM) techniques. This paper presents a wide range of efficient NM schemes which have been neglected by most of the MPPT review papers. As, NM techniques are one of the simplest and fastest tracking algorithms. These techniques offer advantages of exact MPP tracking, standalone applications, flexible searching step sizes and no steady state oscillations. In addition, many different MPPT schemes are discussed and compared with the NM techniques. There are many ways of grouping and categorizing the MPPT algorithms for the Photovoltaic (PV) Array. However, evaluation of the NM schemes in comparison with other techniques is provided effectively through analog and digital classification, in terms of implementation and circuitry involved. Therefore, a comparative review majorly focusing on the importance of NM schemes to track the MPP is presented in comparison with other techniques, through analog and digital classification.

54 citations