جستجوی مقالات مرتبط با کلیدواژه "مبدل کاهنده" در نشریات گروه "برق"

A step-down converter based on buck and buck-boost converters with a loss reduction technique is proposed in this paper. Utilizing non-electrolytic capacitors in the implementation of the proposed converter has resulted in an increase in circuit life and a reduction in weight and volume. This paper compares the proposed converter to other buck converters. To increase the output efficiency of the converter in comparison to other structures, a new method based on determining the working duty-cycles has been employed to reduce the losses of the converter, resulting in an increase in the converter's output efficiency. In order to demonstrate the differences in efficiency between the proposed method and the conventional method, the efficiency of the converter has been calculated using real-world conditions and the output loss results have been compared. In addition, the proposed converter has a common ground with the input source and has a suitable reduction gain. Finally, this converter has been implemented as a PCB and tested with 100 watts of output power.

This paper presents a new step-down resonant dc-dc converter derived from the family of Switched-Resonator converters (SwRC). Soft-switching conditions are provided for both switches at turn on and turn off transitions by switching under zero-current (ZCS). ZCS technique switching losses and enables the converter to operate at higher switching frequencies which enhances the converter power density. Moreover, it gives better efficiency with few element count and decrease the implementation cost. Due to the turning-off of the resonant diode under ZCS condition, the problem of reverse recovery which is a problematic issue especially in fast diodes is obviated. By employing a simple LC resonant network, soft-switching condition is provided for all the semi-conductor devices. The circuit is simulated by PSpice software and the results are presented. Experimental results from a laboratory prototype are also presented. Simulation and practical results confirm integrity of the presented theoretical analysis and show the full-load efficiency at 92.32%.

In this paper, a novel structure based on Bridgeless AC/DC Converters for BLDC Motor is proposed. For now, to drive this kind of dc motors, step down and step up converters and converters with capability of increase and decrease in output voltage with bridgeless diode structures are presented. In this paper by using a novel structure, this possibility is provided to have a converter that can work in desired and separate states such as buck, boost or buck boost operations. In this paper focus will be upon buck-boost operation to access appropriate usage of both decrease and increase at output voltage advantages. Also this converter would not need to a diode bridge at primary of circuit. At output of this converter only a dc-link capacitor exists, that it will decrease the need of electrolytic capacitors that result to decreased circuit volume and cost. Removing of input diode bridge and input dc-link capacitor has caused to a better quality of input current waveforms. As well as, power factor for input power supply of this converter will work near to unit amounts.

In this paper, a new form of signal flow graph technique is used for modeling a bidirectional buck-boost converter and extracting the needed transfer functions. The signal flow graph method has a more simple process in comparison with other modeling techniques. The modeled converter is employed in energy management system of an electric vehicle. The energy system of the electric vehicle is composed of two energy sources; ultra-capacitor and battery pack. The proposed hybrid source has the advantages like: high energy density transmission and high instantaneous power output on the ultra-capacitor. Here, by using the mentioned converter, the energy management between the two sources is performed. Furthermore, the needed configuration for energy management system is presented and a proper controller based on obtained model for energy management in hybrid sources is proposed. Finally, the simulation results are brought to verify the precision of the proposed modeling technique and effectiveness of it in energy management system of an electric vehicle.