Bridge less interleaved SEPIC
Bridge less interleaved SEPIC converter based power factor correction for nonlinear loads.
The need for solid-state ac-dc converters to improve power quality in terms of power factor correction, reduced total harmonic distortion at input ac mains, and precisely regulated dc output has motivated the investigation of several topologies based on classical converters such as buck, boost, and buck-boost converters. Best project center in tirunelveli. Boost converters operating in continuous-conduction mode have become particularly popular because reduced electromagnetic interference levels result from their utilization.
Within this context, this paper introduces a bridgeless boost converter based on a three-state switching cell (3SSC), whose distinct advantages are reduced conduction losses with the use of magnetic elements with minimized size, weight, and volume. The approach also employs the principle of interleaved converters, as it can be extended to a generic number of legs per winding of the autotransformers and high power levels. A literature review of boost converters based on the 3SSC is initially presented so that key aspects are identified. The theoretical analysis of the proposed converter is then developed, while a comparison with a conventional boost converter is also performed. An experimental prototype rated at 1 kW is implemented to validate the proposal, as relevant issues regarding the novel converter are discussed.
Model-Based Current Control for Single-Phase Grid-Tied Quasi-Z-Source Inverters With Virtual Time Constant
In this paper, a model-based current control (MBCC) approach with a compensating of dc-side inductor current ripple, active damping, and virtual time constant is proposed for single-phase grid-tied quasi-Z-source inverters with an LCL filter. The idea behind the ripple compensation is based on the inherent relationship between the ripple components of the dc-side inductor and capacitor voltages. It is shown that dc-side inductor current ripple can be compensated if the conventional simple boost control involving proportional-integral (PI) controllers is modified by subtracting the measured dc-side inductor voltage from the error signal of the first PI controller. Also, it is shown that the proposed MBCC causes the ac-side inverter current to track its reference in all circumstances. In addition, a virtual time constant is added to the control variable so that the dynamics of the ac-side inverter current can be adjusted as desired. Finally, in order to damp the LCL resonance, an active damping method is employed in the closed-loop system by modifying the ac-side reference inverter current. Experimental results are presented to show the validity and performance of the proposed control approach.
Three-Port Bridgeless PFC-Based Quasi Single-Stage Single-Phase AC–DC Converters for Wide Voltage Range Applications
Quasi single-stage single-phase ac-dc power converters based on a three-port bridgeless power factor corrector (TPB-PFC) are proposed in this paper. The TPB-PFC, which is able to provide an ac input port, a dc load port, and a dc bus port simultaneously, is derived by introducing a new dc load port into a conventional bridgeless PFC. The load, whose voltage can be either lower or higher than the peak amplitude of the ac line voltage, is connected to the dc load port of the TPB-PFC directly. Therefore, the ac input power can be fed to the dc load with the single-stage power conversion when the instantaneous ac voltage is lower than the voltage of the dc load. Although another dc-dc converter is required to accomplish the power transmission between the dc bus port and the dc load port of the TPB-PFC, the power rating and losses of the dc-dc converter are reduced significantly, in comparison with a two-stage ac-dc converter. Furthermore, the switching losses of the TPB-PFC are reduced thanks to the three-level characteristic of the proposed converter. The topology derivation, operation principles, modulation strategies, and characteristics of the proposed ac-dc converter are analyzed and verified experimentally with a 2-kW prototype.
https://www.facebook.com/pages/AB-TECHNO-SOLUTIONS/713942458746123
