Abstract
In power electronic applications, especially high power and medium voltage, multilevel inverters (MLIs) have been commonly used. MLIs ensure high quality load voltage and lower Total Harmonic Distortion (THD) than traditional inverter. In this paper, a multilevel inverter structure with reduced number of power switches is proposed. The proposed multilevel inverter is lower costed than conventional MLI. Also, a Genetic Algorithm (GA) based Selective Harmonic Elimination (SHE) technique has been used for the first time in the proposed MLI structure with reduced number of switches. The proposed GA based SHE technique computes the optimum switching angles by solving nonlinear harmonic equations of multilevel inverter. Both Isochronous switching (IS) and SHE techniques have been applied to proposed MLI to demonstrate the effectiveness of the GA based SHE technique. Simulation and experimental results for 7, 11 and 13-level have been obtained. Results of 11-level inverter is analysed and given in detail. Results have clearly proved that desired order harmonics in proposed MLI topology can be eliminated by using GA based SHE technique and lower THD on the load voltage has been provided.
Highlights
Multilevel inverter has been an alternative DC/AC power conversion device instead of traditional two-level inverter in high power and medium voltage applications
The nonlinear Selective Harmonic Elimination (SHE) equations have been solved by Genetic Algorithm (GA) software coded in MATLAB
The proposed multilevel inverter structure has more compact design and has lower construction cost when compared to conventional multilevel inverter
Summary
Multilevel inverter has been an alternative DC/AC power conversion device instead of traditional two-level inverter in high power and medium voltage applications. The voltage stress on semiconductor switches increases with rising desired power and voltage. Semiconductor power switches qualified enough to withstand medium voltage levels can’t be produced with available technology, usage of MLI has become more popular in medium voltage [1], [2]. The first type of multilevel inverters was cascaded Hbridge multilevel inverter and presented in 1975. Diode clamped multilevel inverter (DCMLI) and capacitor clamped multilevel inverter (CCMLI) topology were developed, respectively [3], [4]. DCMLI structure has Manuscript received 14 December, 2018; accepted 4 February, 2019.
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