Faculty Publications
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Publications by NITK Faculty
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Item Digital Control System Based Isolated Totem Pole Converter for Electric Vehicle Onboard Chargers(Institute of Electrical and Electronics Engineers Inc., 2025) Das, A.K.; Raushan, R.; Kumar, P.The Totem-Pole converter is well-suited for lowpowered electric vehicle (EV) applications. The isolated configurations of such converters provide single-stage power conversion that overcomes the more conversion stages. A robust controller can satisfy the converter operations efficiently for on-board charging applications. In this paper, a modified digital control method for totem-pole PFC cascaded active flyback DC-DC converters functioning in discontinuous conduction mode (DCM) is proposed. The auxiliary switch and clamp capacitor are used to recycle the stored energy in the transformer to reduce the spike voltage. The main purpose of adding PFC is to obtain the input current in phase with the input voltage, keeping total harmonic distortion (THD) low to improve the efficiency of the converter. © 2025 IEEE.Item Fast start crystal oscillator design with negative resistance control(Elsevier B.V., 2019) Kumar, P.; Rekha, S.Clock is an essential part of most of the integrated circuits as time base reference. It must be very accurate, highly reliable and readily available as soon as it is enabled. In all types of oscillator architectures, crystal oscillator is the most accurate and stable clock generator. But usually the crystal oscillator circuit suffers from slow startup. Therefore, it is essential to improve the startup time with optimally controlled crystal drive such that crystal drive power rating is not compromised. We propose a method that discusses about increasing the negative resistance during startup, using a startup circuit for fast start. Once the reliable startup is achieved, the negative resistance is decreased and the startup circuit is disconnected. The reduction in negative resistance is done with current steps and there are two ways in which it is achieved, the Digital control method and Analog control method. In digital control method, the current steps are timed at regular intervals and in analog control method, oscillator output amplitude is given as feedback to the startup circuit there by reducing the negative resistance. In the 32768 Hz real time clock generating oscillator, the startup time can be improved from 330 ms to 220 ms using the conventional startup method. With the proposed digital control method, lesser startup time of 160 ms is achieved and in analog control method it is further reduced to 120 ms. © 2018 Elsevier B.V.