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This paper presents a method for switching reduction in cascaded H-bridge converters. Given the wide applicability of this topology, it would be especially desirable to increase its efficiency with switching losses reduction techniques. Since this type of converter requires voltage balancing methods, several modulation methods consider the possibil...
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... test bench includes a 20 kVA-power laboratory CHB converter with three phases and two modules per phase, as in Figure 1. Figure 2a shows an individual H-Bridge module; Figure 2b shows the whole converter, and Table 1 shows the converter's main characteristics. The converter control hardware includes one local control unit per module plus a central control unit. ...Context 2
... 4. Effective transistors' switching frequency (Hz). Phase 1 Phase 2 Phase 3 Module 1 Module 2 Module 1 Module 2 Module 1 Module 2 1 690 1100 1200 810 835 875 2 780 740 750 815 960 690 3 820 610 610 770 605 870 4 1220 200 1285 190 1460 200 5 1980 780 1960 790 1990 785 6 1950 280 1940 230 1950 270 ...Similar publications
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Citations
... Of these, cascaded H-bridge (CHB) topologies have advantages over other MLI topologies (e.g., layout simplicity, extreme modularity, and construction and control simplicity) because they are free of voltage-balance issues. Moreover, compared to other MLI topologies, CHB topologies use the fewest components at the same voltage levels [3,4]. Asymmetrical CHB topologies have been proposed in which the DC voltages are not symmetrical. ...
Different multilevel converter topologies have been presented for achieving more output voltage steps, hence improving system performance and lowering costs. In this paper, a hybrid multilevel inverter (MLI) topology is proposed for active-power-filter applications. The proposed MLI is a combination of two standard topologies: the cascaded H-bridge and the three-phase cascaded voltage source inverter. This configuration enhances the voltage levels of the proposed MLI while using fewer switches than typical MLI topologies. The proposed MLI was developed in the MATLAB/Simulink environment, and a closed-loop control technique was used to achieve a unity power factor connection of the PV modules to the grid, as well as to compensate for harmonics caused by nonlinear loads. To demonstrate that the configuration was working correctly and that the control was precise, the proposed MLI was constructed in a laboratory. A MicroLabBox real-time controller handled data acquisition and switch gating. The proposed topology was experimentally connected to the grid and the MLI was experimentally used as an active power filter to compensate for the harmonics generated due to nonlinear loads. This control technique was able to generating a sinusoidal grid current that was in phase with the grid voltage, and the grid current’s total harmonic distortion was within acceptable limits. To validate the practicability of the proposed MLI, both simulation and experimental results are presented.
The true-type test platform is widely used to evaluate whether relay protection devices are effective and accurate in handling simulated single-phase ground faults. However, since the system scale needs to be increased or decreased by switching capacitors connected in parallel on the feeder line, uncontrolled switching of capacitors may cause the magnetic latching relay to burn out. This article studies the transient process of switching and analyzes the reasons for relay burnout. Switching capacitors at non-current zero-crossing points will produce a large inrush overvoltage, which will burn the relay. To solve this problem, a switching control strategy based on delay compensation is proposed to ensure no inrush overvoltage during the switching process, improve the service life of the magnetic latching relay, and improve the safety of the power capacitor.
Due to differences of solar irradiance, ambient temperatures, or inconsistent degradation of photovoltaic (PV) modules, the unbalanced output power between cascaded H-bridge (CHB) legs will lead to the unbalanced or even distorted grid currents between three phases. This article proposes a novel CHB-based PV grid-tied system integrating centralized energy storage (CHB-PV/ES), which can realize power balanced operation by utilizing the centralized energy storage (ES) interconnecting the CHB three-phase sub-modules (SMs) by isolated DC/DC converter. In addition, the centralized ES group can facilitate the regulation between grid-tied power references and PV power generation, such as stabilizing the power injected into the grid by smoothing the PV power, as well as responding to changes in grid-tied power references. The configuration and security domain of PV and centralized ES SMs are critical factors for CHB-PV/ES, which are thoroughly analyzed in this article to ensure safe system operation. The simulation and experimental results validate the effectiveness of the proposed CHB-PV/ES scheme.
This paper deals with the implementation and performance analysis of discrete-time sliding mode (DTSM) current control applied to a seven-level cascade H-bridge converter to track three-phase reference currents for a reactive load. The converter output voltages are synthesized using a modulation scheme based on phase-shifted carrier modulation. Simulation and experimental tests have been added to demonstrate the performance of the proposed controller. At the same time, the effectiveness of the DTSM is verified under transient and steady-state conditions, respectively, by measuring the total harmonic distortion and the mean square error.