Selecting a Single-phase Transformer for Battery Charger Development using CAD Approach

Abstract

A single-phase transformer was needed to develop a 12V constant-voltage battery charger for a relay protection system. The transformer's power rating was estimated as 500VA for a maximum battery voltage fall of 3V. An efficiency/power-factor product of 0.81(p.u.) was stipulated. A computer software application package was developed to facilitate the designing exercise. In this paper, the author provides details of the generation of the relevant transformer operational equations in which practical considerations were duly reflected. Computer programs were written using the generated equations in the MATLAB programming language, which conduced to the production of a single-phase transformer design software application package. On test-running the package for the design specifications of the needed transformer, the following major details were obtained: The Iron-Core Details included the Diameter of Circumscribing Circle = 6.9469cm; Centre-to-Centre Distance of the Core = 8.0244cm; Total Height of the Core =17.7310cm; Total Length of the Core = 12.6846cm;Total thickness of the Core = 4.6602cm; Magneto motive Force (mmf) = 943.1818AT; while The Winding Details included HV Winding Turns = 415; LV Winding Turns = 24; HV Standard Wire Gauge = 18; LV Standard Wire Gauge =5; HV Phase Current = 2.2727A; LV Phase Current = 41.6667A. From the applicability check feature incorporated in the software package, a satisfactory transformer design was no doubt ascertained.