direct current
Recently Published Documents

This paper proposes a battery charger solution based on the Zeta DC/DC converter to provide a general interface between batteries and microgrid direct current (DC) buses. This solution enables to interface batteries and DC buses with voltage conversion ratios lower, equal, and higher than one using the same components and without redesigning the control system, thus ensuring global stability. The converter controller is designed to require only the measurement of a single inductor current, instead of both inductors currents, without reducing the system flexibility and stability. The controller stability is demonstrated using the sliding-mode theory, and a design procedure for the parameters is developed to ensure a desired bus performance. Finally, simulations and experiments validate the performance of the proposed solution under realistic operation conditions.

<p class="Abstract">The conventional three-phase alternating current (AC) to direct current (DC) converter can be modified using two isolated-gate bipolar transistor (IGBT) as by-pass switches connected to tapping points on the secondary side of the transformer. This scheme yields a reduction in both harmonic contents and reactive volt-ampere absorption. This modified converter possibly eliminates the need for an on-load tap-changer on the converter transformer. The modified AC/DC converter is fully analyzed and implemented under balanced conditions using MATLAB-Simulink. The expressions of the output DC voltage are derived for different cases. The supply current harmonic contents, the reactive power absorption and the power factor have been compared for three schemes; the conventional bridge, the modified bridge using one by-pass IGBT valve and the modified bridge with two by-pass IGBT valves. </p>

The reconfigurable of the differentiator and integrator based on current conveyor transconductance amplifiers (CCTAs) have been presented in this paper. The proposed configurations are provided with two CCTAs and grounded elements. The configurations can be operated in the differentiator and integrator by selecting external passive elements. The input and output currents have low and high impedances, respectively; therefore, the configurations can be cascaded without additional current buffer. The proposed configurations can be electronically tuned by external direct current (DC) bias currents, and it also has slight fluctuation with temperature. An application of universal filter is demonstrated to confirm the ability of the proposed configurations. The results of simulation with Pspice program are accordance with the theoretical analysis.