Selection Of Switching Angles Research Articles

Total harmonic distortion minimisation in multilevel inverters using the teaching–learning-based optimisation algorithm

ABSTRACTIn this article, the minimisation of total harmonic distortion (THD) of the output voltage of a multilevel inverter is studied. The harmonic component of output voltage in the inverter is reduced in THD minimisation. The output voltage THD in multilevel inverters is minimised by proper selection of switching angles. The teaching–learning-based optimisation algorithm is used to find the optimum switching angles in order to generate the desired voltage value in the possible minimum THD. Experimental and simulation results depict advantages of this approach compared to published papers which discus this concept using genetic algorithm. The experiments conducted on a seven-level inverter confirm the feasibility of this approach.

Harmonics elimination in multilevel inverter with unequal DC sources by fuzzy-ABC algorithm

The harmonious appearance in multilevel inverter output voltage is more for the case of unequal DC sources. In this paper, a hybrid technique incorporating fuzzy inference system (FIS) and artificial bee's colony (ABC) algorithm is proposed. FIS is a rule-based artificial intelligent technique which is used for generating the data set in terms of switching angle, harmonic voltage and harmonic distortion. The data set is generated as per the behaviour of the multilevel inverter without using any harmonic elimination technique. In the generated data set, the switching angle and the harmonic voltage are categorised as SMALL, MEDIUM and LARGE. Then, the ABC algorithm is used to optimise the selection of switching angles from the training data set. The performance of the proposed hybrid technique is tested on a 7-level cascade H-bridge inverter for different voltage levels of unequal DC sources using MATLAB/SIMULINK platform. The effectiveness and superiority of the proposed technique is evaluated by comparing the reduction capacity of total harmonic distortion for different voltage levels of unequal DC sources with particle swarm optimisation (PSO) algorithm and fuzzy-PSO algorithm.

Selective elimination of harmonic contents in an uninterruptible power supply: an enhanced adaptive hybrid technique

In today's commercial world, uninterruptible power supply (UPS) is playing a significant role in preventing the computer from power failure. Inverter is one of the essential components of UPS that performs DC–AC conversion. In this process, there is a possibility of generation of harmonic peaks because majority of the power utilities are nonlinear loads. In UPS powered by a multilevel inverter, the harmonics can be eliminated by an optimal selection of switching angles. In this study, the authors propose a hybrid technique to entirely eliminate the harmonics. The proposed hybrid technique utilises an iterative technique and fuzzy logic for the optimal selection of switching angles. A hybrid evaluation technique is used to evaluate the optimum switching angles that are obtained from the iteration as well as the fuzzy logic. The proposed technique is tested with a three-level H-bridge inverter and the resultant fundamental and harmonics voltage are analysed. The experimental result shows the efficiency of the proposed technique in eliminating the harmonics that are generated by the inverter. The proposed technique is implemented in MATLAB and its performance is evaluated using diverse test results.