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In order to realize maximum power output of photovoltaics (PV), reduce line losses, and decrease abandoned solar energy during weak irradiance, a new medium voltage grid-connected PV system structure based on cascaded converters was proposed in this paper. A transformerless cascade step-up structure, instead of applying line-frequency step-up transformer, is proposed to connect PV directly to the...
According to the traditional control of three-phase inverter, basing on the transient mathematical model of second order of virtual synchronous generator, the three loops control of power-voltage-current with virtual synchronous generator (VSG) by using the feedback of capacitance's voltage and current was built. And the proportional and integral control was applied in the loop of voltage to ensure...
Parallel inverter technology is the basis for distributed power generation system to achieve high reliability, high redundancy, high capacity and high scalability, at the same time, it is also the key to the stable operation of distributed generation system. Traditional inverter technology requires low frequency transformer to achieve electrical isolation and voltage matching, which results in the...
This paper presents a comparative evaluation of the loss and thermal performance of two advanced three-level inverter topologies, namely the SiC based T-Type and the Hybrid-NPC, both of which are aimed at reducing the high switching losses associated with a conventional Si based T-Type inverter. The first solution directly replaces the 1200V primary Si IGBT switches with lower loss 1200V SiC MOSFETs...
The single-stage photovoltaic grid-connected system uses only once energy conversion to complete two functions: Maximum power point tracking (MPPT)and grid connected, so it has a large advantage of cost and efficiency. This paper research the Single Stage Three-phase Grid-connected Photovoltaic Inverter. Against the slow response of the DC bus voltage for the control of the traditional double-loop,...
In this paper, an efficiency comparison of neutral-point-clamped (NPC) inverters and bipolar switch NPC (T-Type) inverters is studied and the result shows that the T-Type inverter is more efficient at lower switching frequencies. Nevertheless, its efficiency suffers when the switching frequency increases due to high switching loss of the equipped high voltage power switches. In order to reduce switching...
The Maximum power point tracking (MPPT) algorithms are widely used in micro-inverters to maximize the PV panel's output power. The perturb and observe (P&O) algorithm is the most commonly used method due to its simple implementation. However, since the switching frequency of the BCM micro-inverter is variable, the switching duty ratio or the panel voltage could not be simply used as the perturbed...
The micro-converter Photovoltaic (PV) system which is composed of several cascaded Buck-Boost converters and a central inverter, enables each PV panel to operate at its local maximum power point (MPP). The cascaded buck-boost converter can operate in buck, boost or pass-through mode to realize a wide output voltage range without inverted polarity. However, there is a difficulty in keeping power balance...
This paper proposes a novel direct torque control (DTC) scheme to reduce the torque and stator flux ripples for permanent-magnet synchronous motor (PMSM) drives using a relatively low sampling frequency. Unlike the conventional DTC in which the voltage vectors are determined by hysteresis controllers, the proposed DTC uses nonlinear saturation comparators and a duty ratio modulation scheme for switch...
In this paper, a modulation strategy based on the circuit-level decoupling concept is proposed and investigated for the three-level four-leg neutral-point-clamped (NPC) inverter, with the aim of delivering power to all sorts of loads, linear/nonlinear and balanced/unbalanced. By applying the proposed modulation strategy, the four-leg NPC inverter can be decoupled into three three-level Buck converters...
Micro-inverters convert direct current (DC) from a single solar panel to alternating current (AC). Peak current control is a simple way to regulate the output current of the micro-inverter. In this way, the shape of the current reference will determine the total harmonics distortion (THD) of the output line current. However, several factors like valley switching turn-on delay and equivalent capacitor...
MPPT is widely used in photovoltaic (PV) systems. Among all MPPT schemes, ESC is attractive because it utilizes inverter decoupling ripple and reduces decoupling capacitor size. In this paper, an improved variable step-size ESC algorithm is proposed, which not only has the merits of conventional ESC but also automatically adjusts step-size to track PV module maximum power point (MPP). Compared to...
A study of an eight-transistor (8-T) SRAM cell and its implementation in carbon nanotube FET (CNTFET) technology is presented. CNTFETs have shown great potential as post-silicon CMOS technology due to their superior transport properties, improved current density and excellent robustness to process, voltage and temperature variations. HSPICE simulations demonstrate great advantages for this cell design...
In this paper, a circuit-level decoupling modulation strategy is proposed for the three-level (TL) neutral-point-clamped (NPC) inverters. With the proposed modulation scheme, the TL-NPC inverter can be decoupled into two three-level Buck converters in each defined operating section, which makes the controller design much simpler. The decoupling principle including the driving signal synthesis and...
In this paper three carbon nanotube FET based static memory cells are compared on read and write delays, energy consumption, and performance under diameter variation corners. The carbon nanotube FET is currently considered to be the possible ldquobeyond CMOSrdquo device due to its1-D transport properties that include low carrier scattering and ballistic transport. The memory cells are classified by...
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