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This paper presents a design and implantation of a modified topology for multilevel inverter (MLI). The proposed topology can be utilized in both symmetrical and asymmetrical source configuration. The proposed topology composed of cascaded basic module with H-bridge. The proposed concept is compared with conventional and some recent topologies. As a results proposed topology required less number of...
This paper presents the particle swarm optimization based harmonic elimination pulse width modulation (HEPWM) technique for three-phase voltage source inverter (VSI) to reduce predominant lower order harmonics at its output. The switching strategy of power semiconductor devices of VSI decides the nature of its output voltage. In this regard, the switching strategy can be broadly classified as lower...
Neutral point potential oscillation at low frequency is an important issue in four pole neutral point clamped converter since this leads to the extra voltage stress on the split DC-link capacitors. The detailed analysis indicates such oscillation is closely associated with the neutral point current at low frequency, so this paper explores their relationship, and presents the modulation techniques...
In order to reduce the size of high-voltage flying capacitors in the five-level hybrid-clamped inverter, an improved modulation strategy based on phase-shifted PWM (PSPWM) is proposed in this paper. The four carrier waves are redistributed and the charge/discharge time of the high voltage capacitor can be largely reduced. The only disadvantage of this PWM scheme is that the harmonic characteristic...
This paper proposes a single-phase ac-dc-ac converter composed of two three-leg converters connected in series with an H-bridge on its grid side. The proposed converter allows to feed the load voltage with sinusoidal voltages with constant amplitude and frequency and to operate with sinusoidal grid current with high power factor. Besides, the converter can be used to mitigate fundamental overvoltage...
Obtaining better harmonic profile at relatively lower switching frequencies is one of the key tasks in the present day power electronics world. Several pulse width modulation (PWM) techniques have been developed earlier in time, to reduce the harmonic content from the output of the inverter. Dodecagonal space vector generation scheme is one of them, which eliminates the most dominant lower order harmonics...
This paper presents a selective harmonics reduction for a 3(n+1) shared switch inverter topology utilizing optimal arrangement of the n-modulated signal. Under different modulation indices and operating power frequencies the purpose of the proposed procedure is to select an optimal load connection and/or modulation offsetting based on the desired objective function. Three performance indices are studied...
Multilevel current source converter (MCSC) is an effective way to increase the power rating of conventional current source-fed motor drive, especially its current rating. However, there are still several challenges existing in this kind of configuration, which mainly focus on its space vector modulation (SVM) technique and the inherent DC current imbalance issue. In this paper, an SVM scheme with...
Advent of Modular multilevel converters (MMC) made the voltage sourced high voltage direct current (HVDC) transmission systems a reality mainly due to its modular structure, scalability and reliability. For these converters, minimization of sub-module (SM) capacitor voltage spread without increasing the switching frequency is the biggest challenge as it directly affects the efficiency and cost. Moreover,...
This paper presents the analysis of harmonic and switching loss for two-level space vector based pulse width modulation (PWM) schemes. The harmonic performance of the inverter is evaluated through weighted voltage total harmonic distortion for different modulation indices. To calculate switching loss, analytical expressions for switching instants are generated by comparing the triangular carrier signal...
This paper proposes the pulse width modulation (PWM) technique for the five-phase open-end winding induction motor (FPOEWIM) drive fed from five-phase dual inverter (FPDI) with a single dc source. The selected method gives the advantages of reduced switching losses specifically for induction motor drives working with higher power factors with the elimination of common-mode current (CMC). The method...
An efficient modulation stage is required for power conversion to achieve a good performance fulfilling the requirements of output filtering. On a high competitive market, the ability to adjust output harmonic content beforehand is required to adapt to a wide range of operating conditions. For this purpose, selective harmonic mitigation (SHM) is a very attractive solution for high-power applications...
In the single-phase grid-connected inverter systems the high quality Total Harmonic Distortion (THD) factor must always be considered. In cases, when the supplying voltage is reduced, the output voltage can still be assured constant in the limited range by using the over-modulation strategy that also enables better utilization of dc bus. Unfortunately, this operation incurs high order harmonics' force...
Conventional single phase inverter offers a square wave output which when applied to electrical appliances may damage the later reducing its efficiency and life as this inverter output waveform is not sinusoidal and contains lower and higher order harmonics in addition to fundamental. On the other hand Selective Harmonic Elimination with Pulse Width Modulation (SHE-PWM) offers a fine control of the...
Because of the high dv/dt and di/dt, pulse width modulation inverters and rectifiers introduce high harmonic noise and EMI noise. Using advanced modulation techniques to reduce the harmonic and EMI noise is a promising and practical technique for industrial applications because it does not have extra hardware requirement and can increase the power density. Based on the analysis of the total energy,...
To avoid large overvoltage when the current of the dc-link inductor is interrupted, overlap time is added to the drive signals in current source converters, which results in the extra harmonic in grid current. Waveforms of AC side current before and after added overlap time are achieved from analysis of the current commutation process. The expression of overlap current is given according to the pulse...
To eliminate current harmonics and improve voltage utilization. When traction motor was run in high speed area, a new method is proposed that solve the harmonics component is high and transition which from SPWM to SHEPWM then to six-step mode on the condition of low switch frequency. The method was introduced, principles were analyzed and formulas were derived in this paper. The validity of the proposed...
This work analyzes some possible converter switching strategies so as to achieve higher efficiency and better current waveforms in a high power and low cost three-phase and three-level active AC-DC conversion.
A conventional 3-level PWM Inverter and a Cascaded Multilevel Inverter, both rated at 230Vrms voltage output and 3KW are analysed using the Switching Function. The PWM signal for the 3-level inverter is derived by applying the Switching Function Technique to the equal area principle. For the Cascaded Multilevel Inverter the Switching Function Technique is initially applied to each H-bridge, and then...
Generally, drive manufacturers include input filters and/or output filters to meet system requirements. Depending on damping, these filters have the potential to introduce resonant conditions. Often the switching frequency changes with the rotational speed of the drive machine leading to the possibility that switching harmonics align with the resonant peak of the filters. As the frequency of the drive...
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