Showing papers by "Ramesh Oruganti published in 2006"
TL;DR: In this paper, a 1-MHz asymmetrical half-bridge (AHB) topology is discussed, and a detailed and practical design for a 50-W AHB converter with 1MHz switching frequency was constructed, and the maximum efficiency of 91% was achieved.
Abstract: The asymmetrical half-bridge (AHB) topology discussed in this paper is one of the complementary driven pulse-width modulated converter topologies, which presents an inherent zero-voltage switching (ZVS) capability. In the previous work, the ideal operation of the converter and the ZVS realization process have been analyzed. However, the influence of the circuit parasitics on the output voltage drop and the design constraints of the circuit parameters to ensure the ZVS operation have not been investigated. The minimum load needed to ensure the ZVS operation is also not readily available. This paper presents a detailed and practical design for a 1-MHz AHB converter. A revised voltage transfer ratio of the converter is derived considering the influence of circuit parasitics and the ZVS transition. Two circuit parameters responsible for maintaining the ZVS operation are the transformer leakage inductance and the interlock delay time between the gate signals of two switches. A design method of the two parameters is proposed, which can ensure the ZVS transition. The possible ZVS range of the load variation is also investigated. A 50-W AHB converter with 1-MHz switching frequency was constructed, and a maximum efficiency of 91% was achieved.
68 citations
01 Nov 2006
TL;DR: The well-documented techniques in dc-dc converters namely, voltage and current-mode control techniques, are applied and investigated for a three phase rectifier and experimentally investigated results suggest that better performance can be achieved with the current mode controller.
Abstract: The challenge in controlling a three-phase PWM rectifier mainly arises from the fact that the state-space-averaged model reported in literature has a multi-input multi-output (MIMO) non-linear structure and furthermore exhibits non-minimum phase feature Recently, a dual single-input single-output (SISO) model developed for the rectifier showed that the dynamics of the d-axis is similar to that of a traditional dc-dc boost converter This finding makes it possible to extend the control design and system analysis techniques of dc-dc converters to these rectifiers In this paper, the well-documented techniques in dc-dc converters namely, voltage and current-mode control techniques, are applied and investigated for a three phase rectifier The steady-state and transient performances for step changes in output voltage reference, dc load, and supply voltage are experimentally investigated and the results obtained with the two control methods are compared Experimental results suggest that better performance can be achieved with the current mode controller The results also further justify the validity of the dual SISO model
8 citations
01 Nov 2006
TL;DR: In this article, a simple metric to measure and characterize the EMI spectrum of a power converter is presented based on the specification and thereby the size of an external passive filter required to meet the given EMI standards.
Abstract: The inherent switching of power devices in a switch mode power supply generates electromagnetic interference (EMI) noise This noise is dependent on several factors such as component layout, circuit parasitics, and the control techniques implemented Several methods have been reported in literature to curtail the EMI problem However, until now, a metric to compare the EMI spectra of power converters is not available in literature In this paper, a simple metric to measure and characterize the EMI spectrum of a power converter is presented The proposed technique is based upon the specification and thereby the size of an external passive filter required to meet the given EMI standards The use of the metric is demonstrated through the comparison of the quality of spectra of two different implementations of an industrial power converter The metric is also used to compare the spectra of a converter with two different switching schemes
2 citations
19 Mar 2006
TL;DR: In this paper, the authors presented a method of loss evaluation by measurement of temperatures of individual components and surrounding ambient, which was applied to the front-end power-factor corrected (PFC) rectifier of a commercial ac-dc converter.
Abstract: High power conversion efficiency is an important requirement of the front-end power-factor corrected (PFC) boost rectifier used in shaping the ac input current in a typical modern off-line power supply. A reasonably accurate estimate of the power losses in individual components is essential in order to improve the efficiency of the PFC rectifier. In this paper, difficulties in the measurement of individual component power losses with particular reference to an ac-dc converter are brought out. A method of loss evaluation by measurement of temperatures of individual components and surrounding ambient is presented. Experimental results carried out on the front-end boost PFC rectifier of a commercial ac-dc converter are presented to validate the loss estimation method.
2 citations