The study of five-level inverters with the various PWM
The energy indicators of multilevel voltage converters are analyzed. The relevance of the research is indicated by the increasing demands of technological processes for the economic use of electric energy, the reduction in power consumed by semiconductor converters, and also to the level of regulated reactive power. The converter considered is a five-level voltage inverter. As the topology of the converter, the structure of the inverter on H-bridges is considered. The article presents two-stage three-phase circuits with the connection of inverter cells to wye. Possible states of electronic keys and their corresponding operating modes are described. The voltage of constant voltage sources is 535 V. In the article algorithms for the formation of pulse-width modulation (PWM) are considered: Phase Opposition Disposition, Alternative Phase Opposition Disposition and Hybrid methods with zero sequence sinusoidal shape of the modulate voltage or with triangular shape of the modulate voltage. As a criterion for evaluating the quality of the inverter's output voltage, total harmonic distortion and line-to-line voltage were adopted. A harmonic voltage spectrum is developed for various control methods of the converter. Possible ways of reducing the harmonic coefficient, as well as increasing the amplitude modulation factor, are shown, by using various methods of forming the pulse-width modulation.
Comparison of PWM Techniques for a three level Modular Multilevel Inverter
Abstract Modular multilevel converter (MMC) is a kind of multilevel inverter topology suitable for HVDC and medium voltage applications. These types of converters are designed inorder to mitigate the drawbacks of conventional multilevel inverters like the difficulty of capacitor voltage balancing during higher level of operation, the need for output filters and interfacing transformer. The chopper cell configuration or half bridge cell is the simplest submodule configuration of MMC. In this paper, different Carrier based pulse width modulation techniques for chopper cell based MMC are compared for a lagging power factor load. Simulation analysis has been done using MATLAB/Simulink and the results are verified.
The Effectiveness of Two Approaches to the Teaching of High School American History
The purpose of this study was to test the effectiveness of studies in depth utilizing selected materials which had been developed for teaching high school American history.