P. M. Meshram

Bio: P. M. Meshram is an academic researcher from Yeshwantrao Chavan College of Engineering. The author has contributed to research in topics: Pulse-width modulation & Topology (electrical circuits). The author has an hindex of 10, co-authored 24 publications receiving 822 citations. Previous affiliations of P. M. Meshram include Visvesvaraya National Institute of Technology.

A Simplified Nearest Level Control (NLC) Voltage Balancing Method for Modular Multilevel Converter (MMC)

Abstract: In this paper, a simplified nearest level control balancing method for modular multilevel converter is presented. The proposed method neither requires individual sorting of the submodule voltages nor the redundancy of the switching states. Once the sorting of the submodules is done on the basis of the number of the submodules to be switched on, the identifications of the submodules can be carried out throughout the stages of the implementation of the this method. The proposed method also does not require the individual submodule status in the gate pulse generation stage. The gate logic in the presented method can be implemented with the help of the switching states of the voltage levels. Those simplifications and removing of the some of the stages by the proposed balancing method may ease and lead to the less processor time at the implementation level. The pictorial presentation further helps in consolidating the understanding of the different stages of the method. Rigorous simulations are carried out for open and one of the prominent closed-loop applications, i.e., modular multilevel converter-based high-voltage direct current to demonstrate the validity and effectiveness of the proposed simplified balancing method under normal and emergency conditions.

Tuning of PID controller using Ziegler-Nichols method for speed control of DC motor

Abstract: In this paper, a weighted tuning methods of a PID speed controller for separately excited Direct current motor is presented, based on Empirical Ziegler-Nichols tuning formula and modified Ziegler-Nichol PID tuning formula. Both these methods are compared on the basis of output response, minimum settling time, and minimum overshoot for speed demand application of DC motor. Computer simulation shows that the performance of PID controller using Modified Ziegler-Nichols technique is better than that of traditional Ziegler-Nichols technique.

A Three-Phase Hybrid Cascaded Modular Multilevel Inverter for Renewable Energy Environment

Abstract: This paper presents a three-phase hybrid cascaded modular multilevel inverter topology which is derived from the proposed modified H-bridge module. This topology results in the reduction of number of power switches, losses, installation area, voltage stress and converter cost. For renewable energy environment such as photovoltaic (PV) connected to the microgrid system, it enables the tranformerless operation and enhances the power quality. This multilevel inverter is an effective and efficient power electronic interface strategy for renewable energy systems. The basic operation of single module and the proposed cascaded hybrid topology is explained. The ability to operate in both symmetrical and asymmetrical modes is analyzed. The comparative analysis is done with classical cascaded H-bridge and flying capacitor multilevel inverters. The nearest level control method is employed to generate the gating signals for the power semiconductor switches. To verify the applicability and performance of the proposed structure in PV renewable energy environment, simulation results are carried out by MATLAB/Simulink under both steady-state and dynamic conditions. Experimental results are presented to validate the simulation results.

Optimal tuning of PI controller for speed control of DC motor drive using particle swarm optimization

Abstract: This paper present a method to determine the optimal tuning of the PI controller parameter on Direct current (DC) motor drive system using particle swarm optimization (PSO) algorithm, Ziegler-Nichols (ZN) tuning and Modified Ziegler-Nichols (MZN) tuning method. The main objective of this paper is to minimize transient response specifications chosen as rise time, settling time and overshoot, for better speed response of DC motor drive. The speed control of DC motor is done using PI and PID controllers. Implementation of PID controller for DC motor speed control is done using ZN and MZN tuning method. For PSO algorithm technique, PI controller is used to improve the performance of DC motor speed control system. A comparison is made on the basis of objective function (rise time, settling time and overshoot) from output Step responses. The proposed approach had superior features, including easy implementation, stable convergence characteristic, and good computational efficiency. Fast tuning of optimum PI controller parameters yields high-quality solution. Compared with traditional ZN method and MZN method, the proposed method is found indeed more efficient and robust in improving the step response of DC motor drive system.

Simplified Space Vector Modulation Techniques for Multilevel Inverters

Abstract: This paper presents simplified techniques for the space vector modulation (SVM) of any n -level multilevel inverter. Three techniques have been presented to simplify the identification of the nearest three vectors to the reference vector. The first two techniques are based on resolving the multilevel inverter space vector diagram into appropriate two-level hexagons. This results in simplification of the multilevel SVM problem into a two-level SVM problem. The third technique is an algorithm-based technique which makes use of a 60°-spaced gh coordinate system to perform the SVM of a multilevel inverter. Switching sequence design for all the three techniques is presented with the aim of minimization of the device switching frequency. Simulation and experimental results have been provided to verify the feasibility of the proposed techniques. Simulation results are provided for up to 21-level cascaded H-bridge (CHB) inverters, while the experimental verification is done on a five-level laboratory prototype. Although only the CHB inverter is considered in this study, the proposed techniques are perfectly general and can be applied to all types of multilevel inverters, and are extendable to any number of levels.

Multi-level conversion : high voltage choppers and voltage-source inverters

Abstract: The authors discuss high-voltage power conversion. Conventional series connection and three-level voltage source inverter techniques are reviewed and compared. A novel versatile multilevel commutation cell is introduced: it is shown that this topology is safer and more simple to control, and delivers purer output waveforms. The authors show how this technique can be applied to either choppers or voltage-source inverters and generalized to any number of switches.<>

Evolution of Topologies, Modeling, Control Schemes, and Applications of Modular Multilevel Converters

Abstract: Modular multilevel converter (MMC) is one of the most promising topologies for medium to high-voltage high-power applications. The main features of MMC are modularity, voltage and power scalability, fault tolerant and transformer-less operation, and high-quality output waveforms. Over the past few years, several research studies are conducted to address the technical challenges associated with the operation and control of the MMC. This paper presents the development of MMC circuit topologies and their mathematical models over the years. Also, the evolution and technical challenges of the classical and model predictive control methods are discussed. Finally, the MMC applications and their future trends are presented.

Modular Multilevel Converter With Different Submodule Concepts—Part I: Capacitor Voltage Balancing Method

Abstract: This paper presents a modulation strategy for the modular multilevel converter (MMC) which provides the voltage balancing of the capacitors of different submodules comprising the converter. Not only is this modulation applicable to MMCs constructed with classic two level (2L) submodules, but it is also effective for arrangements with different submodule concepts, for instance, topologies like neutral point clamped (NPC), flying capacitors (FCs), neutral point piloted (NPP), etc. Therefore, firstly, the general modulation philosophy is explained applied to the two level (2L) submodule concept, and secondly, the extension to 3L-NPC and 3L-FC submodule topologies is analyzed. After that, the validation of the studied modulation strategy is carried out by means of successful simulation results, at different switching frequencies and number of submodules. The corresponding experimental results are shown in Part II of this paper after having implemented the aforementioned modulation strategy in a real test bench. In addition to this, a comparison based on thermal analysis and sizing of elements among the four studied submodule topologies is also included.

A Square T-Type (ST-Type) Module for Asymmetrical Multilevel Inverters

Abstract: This paper introduces a new module for asymmetrical multilevel inverters with a low number of components. The module is a square combination of two back-to-back T-type inverters and some other switches. A square T-type module produces 17 levels by 12 switches and 4 unequal dc sources (two 3 V DC and two 1 V DC). Also, it can be extended as a cascade connection in two strategies to achieve more levels. The module and its cascade connection are suitable for the applications in several dc sources systems such as photovoltaic farms, which lead to a modular topology with more voltage levels at higher voltages. Inherent creation of the negative voltage levels without any additional circuit (such as H-bridge circuit) is one of the main features of the proposed module. The low total harmonic distortion of the output voltage/current and low number of semiconductors are among the other advantages of the proposed module. A nearest level control method as a switching technique is used to produce high quality output voltage with lower harmonic contents. Simulations have been performed in MATLAB/Simulink and a prototype is implemented in the Power Electronics Laboratory; both the simulation and experimental results show a good performance.

A comprehensive review on reduced switch multilevel inverter topologies, modulation techniques and applications

Abstract: Recently multilevel inverters (MLI) have attracted more attention in research and industry, as they are changing into a viable technology for several applications. The concept of MLI was introduced for high power and high/medium voltage applications as they can provide an effective interface with renewable energy sources. Developing of reduced switch MLI topology has been a rapid research topic since the past decade, which has not been reviewed so far. Therefore, this review article focuses on the different reduced switch MLI topologies under three categories such as symmetric, asymmetric and hybrid configurations. The important knowledge on these topologies is carefully tabulated based on the three categories in the comparison tables to understand the essential parameters of the MLI topologies. These configurations are not only generating higher voltage levels to improve the power quality but also to reduce the passive filter requirements. Also, this review includes a detailed perspective of various modulation techniques and control strategies for MLI topologies. In addition to that, the different performance parameters of MLI and its calculation methods are discussed with appropriate mathematical expression. This review will help in the selection of appropriate MLI topology for FACTS, motor drives and renewable applications.