Computer-aided design and graphics applied to the study of inductor-energy-storage DC-to-DC electronic power converters

The power handling portion of most regulated dc-to-dc electronic power conditioning circuits using a single self inductor for energy storage and transfer can usually be represented by one of three basic or canonical circuit forms. (1) The circuit elements, consisting of an inductor, a transistor switch, a diode, and a filter capacitor may be arranged with appropriate topology to yield a voltage step-up converter, a current step-up converter, or a voltage step-up/current step-up converter. The design of a power converter requires making a number of decisions relating to the parameters of the circuit, including choice of semiconductor elements, filter capacitor, magnetic core material, magnetic path configuration and winding wire size. In the past, converter designs generally have required that several trial combinations of core size and permeability be tested by hand calculations. Experience and intuition were relied on to narrow the range of core size and permeability before starting the trial design computations. Recently, several computer-aided procedures have been described for use in the design of the inductor for a single type of converter (2, 3) This paper presents the results of the development of a series of nine programs which may be used to design the inductor in each of three basic converter forms in which the transistor switch is controlled by a regulator employing a constant frequency, constant on-time, or constant off-time pulse-width modulator. These nine programs, which contain the design algorithms and evaluation segments, are augmented by three additional programs which generate displays on a storage oscilloscope driven by the computer. These displays have proved to be extremely useful in evaluating the characteristics of the various converter-regulator combinations from an overall or global point of view.