A modified cascaded h-bridge multilevel inverter based on particle swarm optimisation (PSO) technique

The Selective Harmonic Elimination Pulse-Width Modulation (SHE-PWM) is an effective method for harmonic elimination in multilevel inverter. This paper presents the solutions of Selective Harmonic Elimination (SHE) problem based on Genetic algorithm (GA) and Particle Swarm Optimization (PSO) techniques. Total Harmonic Distortion (THD) of output voltage is minimized maintaining selected harmonics within allowable limits. A comparison has been drawn between GA and PSO techniques related to optimization.

For medium- and high-power electronic application technologies, the three-level neutral-point-clamped (3L-NPC) inverter is an effective solution and modulation method is one of its research focuses. There are many modulation strategies for the 3L-NPC inverter, among them, the selective harmonic elimination pulse width modulation (SHEPWM) and selective harmonic mitigation pulse width modulation (SHMPWM) techniques are very useful technologies since they have the characteristics of selective harmonics reduction or elimination. In this paper, simulation models of the 3L-NPC inverter with 10kV grid based on total harmonic distortion (THD) using the SHEPWM and SHMPWM techniques are built in MATLAB/SIMULINK. Here, both the SHEPWM and SHMPWM techniques use fifteen switching angles to generate the switching pattern and the solutions of the nonlinear transcendental equations for these two kinds of PWM techniques are obtained by using the fmincon function with THD-based objective function in MATLAB. Finally, the comparative analysis of the SHEPWM and SHMPWM techniques for the 3L-NPC inverter with 10kV grid based on the THD of voltage and current up to the 50th and the 100th is proposed to verify the respective advantages of the SHEPWM and SHMPWM techniques in different harmonic suppression cases.

Renewable energy has a great importance for power generation as it does not use the fossils fuels. Energy generated from alternative energy sources are weather dependent. To generate a continuous power to meet the load requirements, Battery energy storage system are used. Power conversion process must be much efficient as possible to convert the DC stored energy into AC. This conversion process is usually done by the help of inverters. This paper gives the brief overview on three main categories of multilevel inverter like cascaded h-bridge, neutral point clamped and flying capacitor multilevel inverter and highlights their advantages which can also help the scholars to deeply explore the categories of multilevel inverter. Harmonic elimination is usually done by controlling the switching angles of the inverter. Among all the switching angles techniques, selective harmonic elimination pulse width modulation (SHEPWM) technique is widely used, that has also discussed in this paper. Furthermore, to eliminate the harmonics using SHEPWM, it has the set of nonlinear transcendental equations, these set of equations can be effieceintly solved by the optimization methods. The most efficient and reliable optimization method like particle swarm optimization has been discussed with multiple objective functions in this paper. This paper will help the scholars to understand the finest category of multilevel inverter for harmonic elimination in terms of efficiency and output quality.

This paper proposes two different techniques to optimize the harmonic content in 15-level cascaded H-bridge multi-level inverter (MLI). The proposed techniques are used to determine the switching angle for cascaded H-bridge MLI by solving the non-linear equation using Genetic algorithm (GA) and Newton Raphson (NR) method. Operation for medium voltage and High power converter requires a high-quality waveform with low switching loss. The quality of waveform depends on the number of voltage levels. Higher the voltage level, less will be the harmonics content of different orders. Dominant orders of harmonics have more deteriorating effect in the output wave shape of the inverter. If they are reduced, it will improve the nature of the wave shape. This may be done by applying selective harmonics elimination (SHE) technique. Genetic Algorithm (GA) and Newton-Raphson (NR) techniques have been used in SHE for generating switching pulses for a cascaded multilevel inverter. The simulated results have been presented in this paper indicating the elimination of dominant order of harmonics.

<p>This paper proposes a Multilevel Inverter (MLI) which focuses on two objective , minimal voltage sources and lesser switching component. The proposed Asymmetrical Cascaded Multilevel Inverter (ACMLI) is able to achieve the objective by selectively opting the voltage level of DC sources chosen and implementing the mathematical operation of addition and subtraction on the DC sources. This system also utilizes multiple carrier sinusoidal pulse width modulation technique (MCS-PWM) for operating the switches. It is found that the number of switches required for proposed modular bridge ACMLI and modified H bridge ACMLI was lesser than the traditional Cascaded H bridge Multilevel Inverter (CHB-MLI). It is also evident that the number of DC voltage sources and filter required for smoothing the output waveform is reduced compared to the traditional MLI. The Total Harmonic Distortion (THD) for the proposed circuit was simulated and analyzed in MATLAB Simulink environment and the results are found to be very less and satisfactory. The proposed circuit can find its application in integrating Renewable Energy Sources (RES) to the utility grid, Electrical Vehicle (EV) , harmonic reduction and so on. The simulation results of the proposed circuits are tabulated and compared with the traditional cascaded MLI.</p>

Selective Harmonics Elimination (SHE) technique of power electronic converters can be generally defined as calculation of the optimized switching angles at any desired output (fundamental) voltage component to eliminate a set of preferred lower order harmonic components. This low switching frequency method adds values to Multilevel Inverter (MLI) based systems for the reason that MLI’s have the ability to synthesize waveforms closer to sinusoidal with a better harmonics spectrum. The traditional method for finding the optimized switching angles is by solving the Fourier non-linear transcendental equations of the MLI output voltage and various algorithms like Newton-Raphson (NR) algorithm, Genetic algorithm (GA), Resultant theory, Walsh function etc. are available. This paper proposes a novel approach for performing SHE in MLI working with both equal and unequal dc voltages. The basic principle in which the proposed technique works is a combined effect of equal area criteria and negative harmonics injection techniques. The major advantage is that the proposed methodology comprises of four simple equations for performing SHE instead of solving the complex non-linear transcendental equation. The computational efficiency of this algorithm is evaluated through comparison with traditional NR and GA. In addition, a prototype of three-phase seven-level cascaded MLI is designed through which several informative results are investigated and the effectiveness of the proposed algorithm is proved.

Nowadays, voltage source multilevel inverters are being used extensively in industry due to its many advantages, compared to conventional two level inverters, such as higher output voltage at low switching frequency, low voltage stress(dv/dt), lower total harmonic distortion (THD), less electro-magnetic interference (EMI), smaller output filter and higher fundamental output. However, the evaluation of multilevel inverter losses is much more complicated compared to two level inverters. This paper proposes an on-line model for precise calculation of conduction and switching losses for cascaded h-bridge multilevel inverter. The model is simple and efficient and gives clear process of loss calculation. A singlephase 7-level cascaded h-bridge with IGBT's as switching devices has been used as a case study of the proposed model. The inverter has been controlled using selective harmonic elimination in which the switching angles were determined using the Genetic Algorithm (GA). MATLAB-SIMULINK is used for the modelling and simulation.

Conversion of DC to AC is widely used as an essential need for the power system to harness renewable power source in this era. Multilevel inverter is a mechanism which capable of harnessing these renewable energies. Unfortunately, harmonics occur in the system due to distortions and causing much unwanted problems at the power output. Therefore, the elimination of harmonics and reduce Total Harmonics Distortion (THD) are needed to maintain good power output. Application of Selective Harmonics Elimination Pulse Width Modulation (SHEPWM) can be used in the multilevel inverter to solve the problem. In this paper, optimization algorithms such as Particle Swarm Optimization (PSO), Whale Optimization Algorithm (WOA) and Sine Cosine Algorithm (SCA) were applied for finding suitable switching angle for SHEPWM. The calculated switching angle was applied into seven-level five-phase multilevel inverter for various modulation indexes. In addition, the simulation of the multilevel inverter also done using PSIM software. The results show that the selective lower order harmonics, 3 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rd</sup> and 7 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> are completely eliminated for all three algorithms. In addition, the time taken for newly discovered algorithms to find switching angles for seven-level five-phase inverter is faster compared to PSO.

In the modern world with the advancement of technologies in solid-state electronics, the use of power electronics devices is playing a crucial role in the conversion and control of electric power. By using these innovative devices in 3-phase voltage source inverters, precise and smooth control over the conversion of electrical power can be achieved. But on the other hand, this leads to Total Harmonic Distortion (THD) leading to an adverse effect on the overall system performance. The optimization technique has emerged as a newly popular method for selective harmonic elimination. The main focus of this paper is on simulation study for harmonic analysis of 3-phase voltage source inverter by using particle swarm optimization (PSO) technique. By considering the expression of THD as an objective function, optimization is achieved in the PSO algorithm. This paper also discusses the harmonic analysis of the proposed inverter for conventional PWM techniques such as sinusoidal pulse width modulation (SPWM) and trapezoidal pulse width modulation (TPWM). The harmonic spectrum of the output voltage of the inverter is compared for SPWM, TPWM, and PSO by using MATLAB. From THD analysis, it is observed that PSO gives better performance than other conventional techniques.

Multilevel inverter has played a vital role in medium and high power applications in the recent years. In this paper, Reduced Switch Count Multi Level Inverter structure (RSCMLI) topology is presented with different pulse width modulation techniques. The harmonic level analysis is carried out for the reduced switch count multilevel inverter with the different PWM technique such as with Alternate Phase Opposition Disposition (APOD) method, In Phase Disposition (IPD) method and multi reference pulse width modulation method for five level, seven level , nine level and eleven level inverter. The simulation results are compared with the cascaded H Bridge Multi Level Inverter (CHBMLI). The nine level RSCMLI inverter with APOD method is used for the Distribution Static Synchronous Compensator (DSTATCOM) application in the nonlinear load connected system for power factor improvement. The result shows that the harmonic level and the number of switches required for RSCMLI is reduced compared to CHBMLI. RSCMLI employed in DSTATCOM improves the power factor and harmonic level of the system when it is connected to the nonlinear load.

In this paper, we present a comprehensive and in-depth investigation on the optimization of Proportional-Integral (PI) controller tuning for achieving stability and desired overshoot in the step response. The main objective of this study is to compare the effectiveness of Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) techniques in finding the optimal parameters for the PI controller. The PI controller is a widely used control algorithm that plays a crucial role in many industrial processes. Its tuning greatly affects the system's performance, particularly in terms of stability and overshoot. Therefore, finding the optimal tuning parameters is of utmost importance. To address this optimization problem, we propose the utilization of two popular metaheuristic algorithms, GA and PSO. These algorithms are known for their ability to efficiently search through large solution spaces and find near-optimal solutions. By applying these algorithms to the PI controller tuning problem, we aim to determine which technique yields better results in terms of stability and overshoot tuning. In our comparative study, we provide a detailed explanation of both GA and PSO algorithms, focusing on their working principles and mathematical formulations. We also describe how these algorithms can be applied to the PI controller tuning problem. Furthermore, we highlight the key differences between GA and PSO, shedding light on their strengths and weaknesses. To assess the performance of GA and PSO, we conduct several experiments using different benchmark functions and step response models. We measure the stability and overshoot metrics for various parameter settings obtained through GA and PSO. By thoroughly analyzing the obtained results, we draw meaningful conclusions regarding the effectiveness of each technique. Our findings demonstrate that both GA and PSO exhibit promising results in optimizing PI controller tuning. These observations provide valuable insights and guidelines for choosing the appropriate algorithm based on specific control requirements. In conclusion, this comparative study is thought to contribute to the field of control systems engineering by offering a comprehensive analysis of GA and PSO techniques in the context of PI controller tuning. By highlighting their strengths and weaknesses, it is aimed to provide researchers and practitioners with valuable information for making informed decisions when optimizing control parameters for stability and overshoot reduction purposes.

Multilevel inverters (MLIs) are increasingly used in real time applications. Among several pulse width modulation (PMW) techniques currently deployed for the control of MLIs, selective harmonic elimination PWM (SHEPWM) technique arguably gives the best performance due to its direct harmonic mitigation capability. However, real time application of SHEPWM technique is presently infeasible due to the heavy computational cost involved in solving the transcendental nonlinear equations known as selective harmonic elimination (SHE) equations, which characterize the harmonics that are selected for elimination or mitigation. This paper presents a twostage approach to the online generation of switching angles that mitigate selected lower-order harmonics in multilevel inverters. The first stage involves an offline solution of SHE equations using ant colony optimisation (ACO). In the second stage, ACO computed results are used to train an artificial neural network (ANN) predictive model. The results obtained from the simulation of the proposed method in MATLAB/SIMULINK environment show that the method is highly efficient and accurate.

This paper focuses on the development of open and closed loop system for nine level cascaded H-Bridge multilevel inverter (CHBMLI). Inverters are often used to provide power to electronics in case of a power outage where no power is available. An inverter converts a DC voltage into an AC voltage. But main drawbacks of these inverters are high harmonic content and limited power applications. This is the main problem identified in conventional system. In order to overcome this problem, a new topology of CHBMLI is presented, which increases the level number of output waveform and thereby reduces the low-order harmonics and THD. The proposed system consists of a PV module, DC-DC converter with capacitor filter and DC-AC multilevel inverter. In this paper, an equal pulse width modulation (E-PWM) technique, applicable for proposed CHBMLI is presented. The proposed nine level cascaded H-bridge multilevel inverter achieves higher power ratings, and also enables the use of renewable energy sources in an efficient manner. Simulation results are compared with theoretical results.Index terms- cascaded H-bridge multilevel inverter (CHBMLI); Equal pulse width modulation (EPWM); Total harmonic distortion (THD); Photovoltaic (PV); Separate DC sources (SDCS).

In this paper, PSO (Particle Swarm Optimization) based technique is proposed to derive optimized switching angles that minimizes the THD (Total Harmonic Distortion) and reduces the effect of selected low order non-triple harmonics from the output of the multilevel inverter. Conventional harmonic elimination techniques have plenty of limitations, and other heuristic techniques also not provide the satisfactory results. In this paper, single phase symmetrical cascaded H-Bridge 11-Level multilevel inverter is considered, and proposed algorithm is utilized to obtain the optimized switching angles that reduced the effect of 5th, 7th, 11th and 13th non-triplen harmonics from the output voltage of the multilevel inverter. A simulation result indicates that this technique outperforms other methods in terms of minimizing THD and provides high-quality output voltage waveform

In this study, a new switched-capacitor-based seven-level inverter topology with a photovoltaic system is presented. The proposed topology requires a smaller number of devices and has the ability to self-balance the voltage across the capacitor. The proposed topology configuration is simple and has the ability to extend to higher levels of voltage. This multilevel inverter topology is suitable for low- and medium-voltage applications with photovoltaic (PV) system integration. To improve the PV system efficiency as an input of a DC–DC boost converter, a Fuzzy logic-based maximum power point controller technique is used. A PV system with a DC–DC boost converter integrates with the proposed seven-level inverter topology. The anti-predatory particle swarm optimization (APSO) technique is used to solve the non-linear transduction equations of the seven-level PV switched-capacitor-based multilevel inverter (7L−PV−SCMLI) topology. The proposed APSO is described to minimize the harmonics in the multilevel inverter (MLIs), which is a complex optimization problem involving a non-linear transcendental equation. Furthermore, APSO can be applied in order to solve non-linear transcendental equations for all symmetrical and asymmetrical MLIs that have equal and non-equal DC sources. The APSO-based selected harmonic elimination (SHE) technique obtained the best switching angle value, and the optimized obtained switching angles reduced the total harmonic distortion (THD) of 7L−PV−SCMLI.