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Go to Editorial ManagerThis paper presents a PWM AC/DC buck converter circuit incorporating a frontend rectifier followed by a DC/DC converter. Two transistors are used as a main and auxiliary switches. The proposed circuit provides zero-current (ZC) turn ON and zero-current/zero-voltage (ZCZV) turn OFF to the two transistors, besides zero-voltage turn ON to two diodes. Numerical methods are used to analyse and determine the performance of the converter system. A feed forward technique is employed to improve the performance of the converter over a range of output power.
The LCL Series Resonant Converter (LCL-SRC) type offer nearly load- independent output voltage under some operating conditions. By this way the output voltage can be regulated against a wide load and line variations with a small variation of switching frequency. In this paper a simple method for optimization of LCL-SRC is presented. This method takes the stored energy as a theoretical index to obtain the minimal size of the converter inductors L1 and L2 which contribute significantly to the converter size and weight. The Rac method for the analysis of resonant converter is discussed. This method was found fairly accurate for operation above resonant frequency.
This paper proposes a fuzzy logic based controller for boost type DC/DC converter. It forms an improvement to the dynamic performances of the well known PI like fuzzy controller which uses the output voltage error & its rate of change as an inputs. The proposed controller generates a duty ratio control signal through the addition of a weighted part of the input voltage and of the low pass filtered signal of the inductor current to that of the fuzzy controller which is fed by voltage error and a signal representing the differences of the output voltage from its low pass filtered version. The controlled boost DC/DC converter exhibited excellent performances under small and larger disturbances of the input voltage and output load resistance and also showed good reference tracking ability.
Among the soft-switching techniques, the Zero-Current Zero-Voltage Transition (ZCZVT) technique is used in this paper. It is based on the Resonant Transition Mechanism requirements, which permit newcomers to perceive the Resonant Transition techniques as a whole instead of dissimilar soft-switching techniques. The open loop operation of the power circuit (DC/DC Boost Converter) and control circuit have been implemented and tested with MatLab software. The simulation test facility and the analytical development tools being used are described. The derivation of closed loop control strategy based on fuzzy logic control with nonlinear fuzzy sets for input and output variables is described in detail. The closed loop simulation results that describe the performance of the proposed converter with this control strategy due to different effects are also included.
Continuously Variable Transmission (CVT) combines the efficiency of manual transmissions with the driving comfort of automatic transmissions while providing an infinite range of gear ratios, improved fuel economy, and enhanced acceleration performance. This study presents a comparative evaluation of CVT performance against manual and automatic transmissions in a parallel hybrid electric vehicle (HEV), focusing on fuel consumption and exhaust emissions. A baseline HEV model equipped with a CVT gearbox was selected from ADVISOR simulation software and subsequently modified by replacing the CVT with manual and automatic transmissions for comparison. Exhaust emissions, including catalytic converter pollutant reactions, were recorded for all configurations. Performance assessments were conducted using several global standard driving cycles to simulate real driving conditions. Results indicated that the CVT configuration achieved superior fuel economy and a significant reduction in exhaust emissions compared with manual and automatic transmissions. This improvement is attributed to the CVT’s effective control of speed ratio and overall transmission efficiency. The findings support the suitability of CVT gearboxes for urban hybrid vehicle applications due to their low fuel consumption and high efficiency in speed ratio control.