STABILITY ANALYSIS OF SEPIC CONVERTER USING MATLAB/SIMULINK
DC-DC converter is a converter where we are regulating the input voltage to get the desired output voltage which is either greater than or equal to or less than the input voltage with positive or negative polarity. A lot of dc-dc converters are available in the world out of which SEPIC (Single-Ended Primary-Inductor Converter) converter is one of them. To analyse the converter, a lot of techniques are available. This paper presents the use of MATLAB/SIMULINK to study the stability of the converter. The state space technique is applied to this higher order converter and converted into transfer function. The reduced order technique is applied to the system and compared with the higher order system which gives approximate results for all type of analysis.
CONTROLLER DESIGN FOR SEPIC CONVERTER USING MODEL ORDER REDUCTION
A SEPIC (Single-Ended Primary Inductor Converter) is a DC-DC converter, capable of operating both in stepup or step-down mode and widely used in battery-operated applications. There are two possible modes of operation in the SEPIC converter: Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM). This paper presents modeling of a SEPIC converter operating in CCM using the State-Space Averaging (SSA) technique. SEPIC converter consists of two inductor and two capacitor hence it is fourth order dc-dc converter. Design of feedback compensator for fourth order system is quite complex. In this paper, model order reduction technique is used for controller design of SEPIC converter. First small signal dynamic model for SEPIC converter is obtained using SSA technique which provides fourth order transfer function. Then this fourth order transfer function is reduced to second order using Padé approximation. Then the compensator is designed for the reduced order model of the SEPIC converter. Result shows that the compensator designed for reduced order model gives the quite satisfactory response with the original system. KeywordsSEPIC Converter, CCM, State-Space Averaging, Model Order Reduction, Padé-Approximation, Compensator
Carbon Dioxide Elimination from Circle Systems
Ten various circle systems were studied in model experiments. All the experiments were performed using a Waters cannister containing 675–685 g of Durasorbr̀. 300 ml of carbon dioxide were supplied to the system per min. The efficacy of these systems was expressed as the time taken to demonstrate a concentration of 0.6% carbon dioxide in the gas mixture supplied to the patient connection during each respiratory cycle. The carbon dioxide elimination was studied at a gas flow of 2, 4 and 6 1 per min. All the systems showed an effective carbon dioxide elimination for 6 h or more at a flow of 2 1. An increasing efficacy was found with increasing flow, but to a varying extent.