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This paper presents a simplified direct modulation prediction approach for modular multilevel converters (MMC). By using the Euler approximation, the grid-side and circulating currents are firstly predicted to obtain the values in the next switching cycle. Then the modulations are directly calculated based on the established mathematical models for the six-arms of MMC. Subsequently, the capacitor...
In this paper, a new quasi Z-source inverter based on new capacitor basic units (CAQZSI) is proposed. It is possible to develop the proposed topology by using n numbers of the basic units that is one of the main advantages of the proposed CAQZSI. The boost factor equation, voltage and current equations of the capacitors, diodes and inductors are obtained for the proposed topology and developed CAQZSI...
The modular multilevel converter (MMC) is considered among the top choices for very high-power applications due to its superior features. To operate with good performance, effective control and modulation techniques are required to suppress the detrimental effects, including the circulating current and the capacitor voltage ripples. This paper proposes an efficient variable nearest level control-model...
A modular multilevel converter (MMC) with traditional cascaded PI control structure suffers from poor steady state and dynamic performance. This is due to the limited harmonic rejection capability of PI controller thus failing to alleviate even order harmonics in circulating current and due to the slower outer average voltage control loop resulting in significant deviation in submodule capacitor voltages...
For the discussion about the neutral point potential (NPP) control of single phase three-level rectifiers, most of the methods solve the NPP problem by adjusting the zero-sequence voltage under symmetrical load conditions. However, when one phase voltage reaches to the maximum voltage, the other phase voltage goes to the minimal voltage. As a result, the NPP control ability is limited since there...
As a key component of DC medium voltage breaker, the switch mechanism is required to open in high-speed and can withstand the breaking voltage which is generated during opening motion. Thus, the design of driving circuit of switch mechanism is very important to optimize the mechanism structure and improve mechanism opening characteristics. First the motion principle of high-speed switch was given...
The specific problems of the disconnection of HVDC breakers need an analysis of performances at laboratory scale. In the study of hybrid circuit breakers with commutation, three steps are necessary: modeling, simulation and experimental tests. The paper presents a modeling procedure for a hybrid commutation breaker intended to operate using resonant circuits phenomenon. Using the Matlab platform,...
This paper proposes a digitally controlled bipolar converter for dc micro grids. The bipolar converter configuration is based on the combination of SEPIC and CUK converter with the modifications in both the converters. In the proposed bipolar converter, the equivalent series resistance (ESR) of the transfer floating capacitor is increased by inserting a series resistance in the both SEPIC and CUK...
A control strategy to manage the circulating current content in a Modular Multilevel Converter in direct AC-AC topology is proposed in this article. The converter is connected in three-phase YDY configuration which forms a closed delta path for free current circulation while keeping outsider waveforms with low THD content. Circulating current correction becomes necessary face to any kind of unbalance...
The objective of this paper is to underline the potential as well as the control advantages of the modular-multilevel high-voltage-direct-current converter (MMC-HVDC). Firstly, a brief overview of the MMC-HVDC technology is given and the detailed equivalent model for this converter is presented. Secondly, a heavy focus is applied to the control of a converter substation. Thirdly, a Matlab simulation...
Modular multilevel converters (MMC) have been at the heart of numerous research projects and publications over the last decade. This topology is particularly challenging when it comes to real-time simulation; it has thousands of power-switching devices, control signals, and differential equations to solve. This has led to various models with different levels of detail. Although, all models are equally...
This work shows analysis and design of a non-inverter asynchronous buck-boost dc-to-dc converter as a battery charger for an MPPT solar system. Circuit design, simulations and implementation are also shown for a solar panel with variable load.
The paper proposes a new step-up topology with high step-up conversion ratio. Dc analysis is performed and the static characteristics are derived revealing that the static conversion ratio exhibits a high voltage boost, the converter still operating at reasonable duty cycles. Compared to a classical Boost, the static conversion ratio at the same duty cycle D is (1+nD) time higher, where n is the transformer...
Paper deals with analysis and modeling of a new type of single-phase supplied single leg LC matrix converter (SLLC MxC) with two phase outputs. Its schematic arrangement consists of one-leg half-bridge matrix converter, network with a neutral point, LC filters, switched capacitor and passive or active load. As the harmonic analysis of the voltage of both phases gives a very high value of total harmonic...
One of the most important goals for this study is to reveal an effective way to develop systematically the state equations that define the analog circuits (linear, non-linear, timeinvariant etc.) with excess elements. These equations can be depicted in various forms, like symbolic form, numeric-symbolic form, numeric-normal form. At the beginning, we designed the calculation method and afterwards...
Industry development and quality assurance in this field always addresses energy requirements that are likely to grow in the future. Among renewable energy sources, it is impossible not to mention the powerful increasing development of wind and sun energy systems. These sources of energy bring a large amount of electricity to almost all European countries. It is therefore possible to say that these...
This paper aims to study an active-clamped resonant flyback converter. The proposed resonant technique can increase the zero-voltage switching (ZVS) range. Gallium Nitride high electron mobility transistor (GaN HEMT) devices are also applied in this study to reduce the switching losses at high-frequency operation. Synchronous rectifier is designed on secondary side to minimize the conduction losses...
High voltage direct current (HVDC) transmission systems play an increasingly important role in offshore wind energy and long distance energy transmission systems. Modular multilevel converter (MMC) is an attractive topology for HVDC systems, due to its good modularity, scalability and inherent fault tolerant capabilities. For such topology, model predictive control (MPC) is a promising alternative...
Because the numerous nonlinear components and fiber interfaces are used in Module Multiple Converter (MMC), the HIL test of MMC with detailed EMT model and the full-scale interface is hard to be implemented. In recent years, this existing disadvantage caused the MMC controller hardware and software difference between the HIL test and real project. In this paper, a detailed EMT model of hybrid MMC...
This paper proposes a methodology of design and control, and shows the main simulation and experimental results for a LLCC Series-parallel resonant converter applied to Wireless Power Transmission (WPT) in-motion. Using Induced Power Transfer (IPT) and considering a near-field energy-transfer method (less than 20 cm), the converter is applied in a small scale electric vehicle (EV). The modeling was...
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