Selective Harmonic Elimination of Cascaded Multilevel Inverter Using BAT Algorithm

<span>In this paper, modified multilevel inverter, via addition of an auxiliary bidirectional switch, based on Newton Raphson (NR) and Particle Swarm Optimization (PSO) techniques is presented. The NR and PSO techniques were employed for selective harmonics elimination (SHE) solution in a modified Cascaded H Bridge Multilevel inverter (CHB-MLI). The Selective Harmonic Elimination Pulse-Width Modulation (SHE-PWM) is a powerful technique for harmonic minimization in multilevel inverter. The NR and PSO techniques were used to determine the switching angles by solving the non-linear equations of the output voltage waveform of the modified CHB-MLI in order to control the fundamental component and eliminate some low order harmonics. The proposed NR and PSO techniques are capable to minimize the Total Harmonic Distortion (THD) of the output voltage of the modified inverter within allowable limits. This paper aims to modeling and simulation by MATLAB of the modified topology of the CHB-MLI for a single-phase prototype for 13-levels. The inverter offers less THD and greater efficiency using PSO control algorithm compared with the NR algorithm. <br https://server9.kproxy.com/servlet/redirect.srv/sruj/snbzofspy/skvyzff/p1/> The performance of the proposed controllers based on NR and PSO techniques is verified through simulation.</span>

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.

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.

Various control and modulation techniques such as Sine Pulse Width Modulation (SPWM), Space Vector modulation (SVM) and Selective Harmonic Elimination (SHE) have been used for multilevel inverter (MLI). The best method is SHE due to low switching losses and it suppress the specific unwanted harmonic. The various algorithms such as Genetic Algorithm (GA), bee algorithm, resultant theory and swarm intelligence have been applied by researchers. In this paper, a comparative analysis of SHE based seven levels inverter have been made using Particle Swarm Optimization (PSO), Simulated Annealing (SA), Bat Algorithm (BA) and Cuckoo Search Algorithm (CSA). The simulation has been done by MATLAB for seven level and the performance has been verified experimentally.

This paper presents the multi carrier pulse width modulation (MCPWM) and selective harmonic elimination (SHE) technique for cascade multilevel inverter (CMI) to reduce the total harmonic distortion (THD) of the output voltage waveform. A comparison has been done between the SHE and MCPWM technique to show the advantage of SHE technique over the MCPWM technique. To find the accuracy of total harmonic distortion (THD) between the MCPWM and SHE technique is achieved by comparing the FFT based result for nine level cascade multilevel inverter.

This paper presents a transformer-less electrical converter is a power converter that synthesizes voltage from several levels of DC voltages. In Transformer-less electrical converter, selective harmonic elimination is major one for each medium-and high-voltage applications. The performance of output voltage and power is increased with the reduction of total harmonic distortion. Harmonic elimination in Transformer-less inverters established huge thought for past few decades with the smallest total harmonic distortion. But, the elimination of selective harmonics in Transformer-less electrical converter still experiences certain drawbacks. Recently, several analysis works are introduced for enhancing the performance of output voltage and power in transformerless electrical converter. In an existing hybrid formula was projected in seven-level Transformer-less electrical converter for selective harmonic elimination with condensed switches. HERIC optimization based mostly Selective harmonic elimination methodology is proposed for selective harmonic elimination with known optimum switching angle. Then, switching angle is measured and initialized for activity of the memetic optimization. The output voltage improvement is earned by proposing a shuffled frog leaping switching angle optimization based mostly selective harmonic elimination methodology in transformer-less inverters. After initializing switching angles, shuffled frog leaping switching angle optimization algorithm is utilized for selective harmonic elimination. A 120W model was also designed and tested in the laboratory, and the simulation and experimental results are finally conferred to show the wonderful performance of the proposed PV electrical converter.

The modular multilevel converter (MMC) has proven itself as an exceptionally effective converter in High Voltage DC (HVDC) applications, due to its modularity, reliability and robustness. Yet, it requires unique modulation techniques to accomplish the troublesome capacitor voltage balancing. In this paper, a Modified Selective Harmonic Elimination (M-SHE) is introduced where the switching of the submodules is done in a certain preconfigured arrangement which accomplishes the required capacitor balancing. The proposed modulation technique is then compared with Third Harmonic Injection — Phase Shift — Sinusoidal Pulse Width Modulation (THI-PS-SPWM) and with the Classical Selective Harmonic Elimination (SHE). Performance of the proposed M-SHE, classical SHE and THI-PS-SPWM for a five-level MMC unit is evaluated based on time-domain simulation studies in the MATLAB/SIMULINK software. The reported study results demonstrate that the M-SHE satisfies capacitor balancing and has lower Total Harmonic Distortion (THD) than the classical SHE and THI-PS-SPWM.

This article presents a hybrid method to solve the selective harmonic elimination (SHE) problem for an adaptive DC bus multilevel inverter (MLI) topology. The proposed hybrid method combines the Grey wolf optimization (GWO) technique and Newton-Raphson (NR) numerical method which drastically minimizes the computational time and further improves the accuracy of the SHE solution. The technique is essentially divided into two stages. In the exploration stage, GWO explores the entire search space of SHE problem and provides initial values of switching angles for a given modulation index with a fast rate of exploration. In the exploitation stage, the NR method uses these initial switching angles as input to iteratively determine the optimum value of the firing angles. This GWO-inspired iterative methodology is implemented on a hybrid MLI topology for photovoltaic (PV) system applications. The performance of proposed SHE method is compared with recently developed metaheuristic SHE techniques based on some key performance indices. From an application point of view, the 11-Level MLI is tested on a PV battery-based stand-alone system to determine the effectiveness of the proposed method in MATLAB/Simulink environment. Finally, a small-scale experimental prototype is developed to validate the proposed method.

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.

Utilization of Exchange Market Algorithm (EMA) for selective harmonic elimination (SHE) in cascaded multilevel inverters (CMIs) is investigated in this paper. The nonlinear SHE equations are derived for a 7-level CMI based on the Fourier expansion of the output voltage waveform. A cost function is constructed according to the SHE equations and optimization is performed with EMA. In order to compare the results, the SHE equations are also solved with Genetic Algorithm (GA) with similar parameters as used for EMA. Optimization results prove that EMA is superior to GA in terms of convergence rate, and achieving exact global minima. For verifying the optimization results, simulations are performed on a 7-level CMI for different modulation indices.

This research compared the performance of PWM (Pulse Width Modulation) inverter and multilevel inverter in terms of their output voltage and current total harmonic distortion (THD). The inverters were designed to have the output voltage of 220 V at 50 Hz. The input voltage for both inverters are 400 VDC. For PWM inverter, the PWM technique utilized was sinusoidal PWM (SPWM) and for multilevel converter, the number of voltage level is five with diode-clamped topology. The study included circuit implementation, analysis, and THD calculation, all of which were carried out through simulation using PSpice software. In controlling the SPWM inverter output, the adjusted parameters included amplitude modulation ratio, frequency modulation ratio, and filter components’ parameters. On the other hand, the firing angles of the switching components were designated as controlling parameters in multilevel inverter. From the study, it was found that the best THD values of the designed SPWM inverter are 4.2% (voltage) and 1.7% (current), while those of multilevel inverter are 27% and 11%, for voltage and current, respectively. Thus, it can be concluded that SPWM inverter is better than 5-level inverter for the application in solar panel due to its lower THD. In our study, 5-level inverter did not satisfy the THD requirement specified in IEEE 512-1992, i.e. 5%.

Selective harmonic elimination (SHE) is a widely used method to minimize the amount of total harmonic distortion (THD) in multilevel inverters. The main challenge associated with SHE method is to solve multiple variable high order nonlinear equations to obtain desired switching angles. To overcome this problem, a new online approach is provided in this paper which does not require solving complex nonlinear equations. In this method, artificial neural networks (ANNs) are used to determine the switching angles to minimize the THD amount of the ac side voltage of an 11-level cascaded Half-bridge (CHB) multilevel inverter. However, unlike offline methods, ANN is updated online, without using any data gained from solving SHE equations. Finally, Simulation results are illustrated and compared with other offline methods.

Power electronic converters for medium and high power / voltage applications employ low frequency synchronous fundamental switching to minimize semiconductor switching losses. There are two major approaches to converter switching angles determination - Selective Harmonic Elimination (SHE) and Total Harmonic Distortion (THD) minimization. For the THD minimization, converter switching angles are found to assure minimum THD criterion without taking care of frequency spectrum. For the SHE approach, all degrees of freedom due to available amount of switching angles are spent on elimination of low order harmonics. Recently suggested combined approach suggests spending some degrees of freedom on certain harmonics elimination and the rest for minimizing THD. This generalized problem formulation includes classic minimal THD and SHE problems as special cases. The paper presents comprehensive results on combined SHE and THD minimization for a staircase modulation of a single-phase converter with 5, 6, 7 and 8 switching angles (6, 7, 8 and 9 non-negative voltage levels).

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.

Multilevel inverters (MLIs) are widely recommended for DC to AC power conversion as per the load requirements. The MLIs are preferred over other types of multilevel and conventional converters due to their ability to produce staircase output voltage waveforms with superior harmonics profile. However, the performance of MLIs largely depends on the modulation strategy employed. Among the various modulation techniques, the selective harmonic elimination (SHE) method is more efficient in eliminating low-order harmonics from the voltage waveform produced by MLIs. Proper mitigation of the dominant low-order harmonics results in reduction in switching losses in the semiconductor devices and improves the efficiency of the inverter. However, the analytical solution of the nonlinear SHE equations constitutes the main challenge. Over last few decades, various solving algorithms and techniques such as algebraic methods such as resultant theory, numerical techniques and optimization algorithms have been developed and proposed for selective elimination of unwanted harmonics. This review paper presents the various aspects of the problem formulations for SHE technique. Moreover, the detailed principle operation for five different SHE problem-solving techniques is also discussed in this paper. Solution trajectories corresponding to multiple solutions, PWM waveforms with single and multiple transitions at each voltage level and also for pulse-width-amplitude modulation are evaluated and presented to help the researchers gain better insight into the SHE problem and its solution.