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Summary The output power requirement of battery charging circuits can vary in a wide range, hence making the use of conventional phase shift full bridge DC‐DC converters infeasible because of poor light load efficiency. In this paper, a new ZVS‐ZCS phase shift full bridge topology with secondary‐side active control has been presented for battery charging applications. The proposed circuit uses 2 extra switches in series with the secondary‐side rectifier diodes, operating with phase shift PWM. With the assistance of transformer's magnetizing inductance, the proposed converter maintains zero voltage switching (ZVS) of the primary‐side switches over the entire load range. The secondary‐side switches regulate the output voltage/current and perform zero current switching (ZCS) independent of the amount of load current. The proposed converter exhibits a significantly better light load efficiency as compared with the conventional phase shift full bridge DC‐DC converter. The performance of the proposed converter has been analyzed on a 1‐kW hardware prototype, and experimental results have been included.

Abstract. The tangential stress and velocity field corresponding to the flow of a generalized Oldroyd-B fluid in an infinite circular cylinder will be determined by mean of Laplace and finite Hankel transform. The motion is produced by the cylinder, that after t = 0 + , begins to rotate about its axis, under the action of oscillating shear stress ΩR sin(ωt) given on boundary. The solutions are based on an important remark regarding the governing equation for the non-trivial shear stress. The solutions that have been obtained satisfy all imposed initial and boundary conditions. The obtained solution will be presented under series form in term of generalized G-function. The similar solutions for the ordinary Oldroyd-B fluid, Maxwell, ordinary Maxwell and Newtonian fluids performing the same motion will be obtained as special cases of our general solutions.