A novel constraint‐based genetic algorithm solution for SHE technique in modified PUC‐5 inverter (original) (raw)

The selective harmonic elimination (SHE) is a preferable modulation technique in medium and high power converters applications as it enables for using low switching frequency with high flexibility to eliminate specific harmonics. The digital implementation of the SHE is a challenging issue as it requires a very accurate generation of the switching pulses. The theoretical calculation of the switching angles cannot guarantee the same results when digitally implemented by digital controllers. The digitizing process with a relatively low sampling frequency due to the digital implementation introduces error for each applied switching angle. Consequently, the applied switching angles will not match the theoretical ones resulted in residual errors for the selected harmonics that should be eliminated. This paper presents a new approach to improve SHE accuracy by online prediction and implementing of the closest true angles to minimize the residual harmonics.

The multilevel inverters (MLIs) are capable of handling large quantities of power and generating high-quality output voltages. Consequently, the size of the filters is reduced, and the circuitry is simplified. As a result, they have a diverse range of uses in the industrial sector, especially in smart grids. The input voltage boosting feature is required to utilize the MLI with renewable energy. In addition, a large number of components are required to attain higher output voltage levels, which increases the cost of the circuit and weight. A variety of MLI topologies have been identified to reduce losses, device quantity, and device ratings. The selective harmonic elimination (SHE) approaches reduce distinct lower order harmonics by computing the ideal switching angles. This research presents a nine–level Packed E–Cell (PEC–9) inverter that uses selective harmonic elimination to eliminate total harmonic distortion. In order to calculate the best switching angle, the reptile search a...

This paper introduces an effective Selective Harmonic Elimination (SHE) modulation technique in a five, seven, and nine-level cascaded H-bridge (CHB) multilevel inverter (MLI). Minimization of the harmonics and device counts is the basis for the ongoing research in the area of MLI. Reduced harmonics and hence the lower Total Harmonic Distortion (THD), improve the output power quality. SHE is a low-frequency modulation scheme to achieve this goal. SHE techniques are used to eliminate the distinct lower-order harmonics by determining the optimum switching angles. These angles are evaluated by solving the non-linear transcendental equations using any optimization technique. For this purpose, the Crystal Structure Algorithm (CryStAl) has been used in this paper. It is a metaheuristic, nature-inspired, and highly efficient optimization technique. CryStAl is a simple and parameter-free algorithm that doesn’t require the determination of any internal parameter during the optimization proce...

ABSTRACT:The three level inverters have been found wide application in industry from the prior for converting DC voltage to AC voltage. The main problem in these equipment’s is the existence of harmonic in output voltage. THD is a very important factor to determine losses in the equipment’s such as induction motor, transformers and etc. Loss plays an important role in determining the cross section in distribution network cables and overhead lines, hence the exact determination is important. In prior literature, to determine the amount of THD, approximate methods have been used. They have considered some limited low order harmonics. In this paper, to determine the exact amount of phase voltage THD (PVTHD), an exact method based on extracting formula is presented. The proposed methods consider all harmonic orders and can be utilized for each number of switching angles. Another feature of introducing methods is presented analytical formulas for phase voltage THD that eases finding thos...

Abstract: The quality of the inverter output is a major concern when renewable energies are to be connected to the grid. Particularly, the harmonic distortion is a headache to the system designer and may lead to malfunctioning of the overall system. In this work, the problem of harmonic elimination through optimizing the firing angles in a three phase PWM inverter is addressed. Harmonic elimination techniques give an improved performance by cancelling the most problematic harmonics. The Spiral optimization technique results in a further reduction in the harmonic distortion. In this approach, the ONand OFF instances (firing angles) of the switches to eliminate some desired harmonics are pre-calculated. These firing angles are stored in a microprocessor which produces the pulses with predetermined timing corresponding to the desired harmonics to be eliminated.