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A new dual-input and dual-output switched capacitor (SC) converter is designed to operate with two independent voltage sources that provides two different output voltages. The only converter generates 32 voltage conversion ratios (VCRs). The converter is portable to operate with one or two input sources alternatively and having the ability to vary 32 voltage ratios. An efficient low power SC converter...
This paper presents an investigation of the chaotic behavior of power electronic converters. The DC-DC converters are highly nonlinear devices. The switches and passive components make the behavior of these converters difficult to be characterized with the conventional analytical tools. Therefore, investigating modeling methods and analysis is necessary. Knowing the behavior of these converters allows...
In this paper, the energy conservation law in physics is introduced into the control prototype of boost converters. Firstly, the input and output energy and the energy changes in the reactive components in each switching cycle are analysed. Then an energy balance control (EBC) method is designed based on the energy conservation law, which is independent of converter work modes, continuous conduction...
This paper proposes a transient modeling and analysis method for the fractional-order DC-DC converters in continuous conduction mode (CCM), in which a fractional-order Buck converter is taken as an example. By extending the usage of equivalent small parameter method (ESP), the converter is modeled by a general state vector differential equation. Then by adopting the principle of harmonic balance,...
Transformerless inverters are being widely used in low power grid-connected photovoltaic (PV) generation systems. Transformer elimination has many advantages; it reduces cost, size, weight and also increases the whole system efficiency. However, once the transformer is removed, there is no galvanic isolation between grid and PV array and, as a consequence, a leakage current may appears due to the...
Input current of a Current Fed Switched Inverter (CFSI) contains the switching frequency component (75 kHz) and a second harmonic component of line frequency (100 Hz) apart from the DC part. In prior designs, the second harmonic component was suppressed by increasing the size of passive components (inductor or capacitor), which makes the inverter implementation bulky. This paper presents a control...
Modular multilevel converters (MMC) have many advantages owing to their power-stage modularity. However, this modularity does not extend directly to the control. Particularly, the balancing control usually requires central coordination and increases in complexity with the system size. This paper presents a balancing control method for a more general modular multilevel converter with series and parallel...
Since the capacitor equivalent series resistance (ESR) above 1kHz almost stays constant, dc-link current root-mean-square (RMS) closed form equation is an easy way to evaluate the capacitor losses from the switching harmonic currents (SHCs). But when the ac current contains multiple low order harmonics (LOHs), their impacts on the dc-link has not been systematically studied. In this paper, a straightforward...
This paper presents an indirect model predictive control to develop a direct power regulator for a modular multilevel converter connected to a high voltage direct current bus line, where the main task is to bidirectionally transfer active power to the grid and simultaneously compensate reactive power. The main advantage, of the proposed dynamic matrix control methodology, is to capture the system...
This paper proposes a high efficient soft-switching multiple-input positive buck-boost converter. Multiple-input converters (MIC) use usually forward-conducting-bidirectional-blocking (FCBB) switches to control their input voltages and currents. However, these FCBB switches may decrease the overall system efficiency because of their switching losses. This paper applied a soft-switching method into...
This paper presents a new topology of multilevel converter that allows to increase the number of output voltage levels reducing the numbers of semiconductors necessary in comparison with the standard multilevel converters like Active Neutral Point Clamped (ANPC) and Stacked Multicell Converter (SMC). This new topology called Reduced Multilevel Converter (RMC) consists of a tandem connection of basic...
The purpose of this study is to design a LQR controller for the SEPIC (Single-Ended Primary-Inductor Converter) converter which is widely employed in industrial DC-DC power conversion and is also starting to see widespread use in PV applications. Circuit-Averaging-Method is used to acquire the mathematical model of the given system. Controllers are designed based on the Small-Signal model. LQR and...
This paper presents discontinuous pulse width modulation (DPWM) scheme for a modular multilevel converter (MMC) to achieve an advanced switching losses reduction. The MMC is considered to be one of the most attractive multilevel topology for high-power applications because of the features of its high power quality, modularity, and availability. However, the MMC has large switching losses because of...
Boost type converters are commonly used as pre-regulators in applications such as photovoltaics, battery storage, and power factor correction. Normally, non-isolated step-up conversion is done using traditional hard-switching boost topologies, but these suffer from low efficiency due to hard switching transitions. Soft-switching boost topologies present an opportunity to increase switching frequency...
A high step-up switched-capacitor based converter is proposed in this paper. The proposed converter features high conversion ratio, low voltage stress and continuous input current, which makes it very suitable for renewable energy applications like photovoltaic systems. More importantly, the proposed switched-capacitor cells in series with converter can be generalized in two ways, resulting in dc-dc...
The advantages of the Modular Multilevel Converter (MMC) as a Voltage Source Converter (VSC) is well known. These includes scalability, increased reliability, lower Total Harmonic Distortion (THD) in output variables, fault tolerance and so forth. The MMC has found its most application in High Voltage DC (HVDC) systems again because of the stated advantages. In the analysis of such systems, because...
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...
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...
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...
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...
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