Title: Isolated digitally controlled voltage mode forward converter with excellent audio rejection

Authors: M.G. Rajesh Kumar; G. Sajitha; A.R. Krishnan; Thomas Kurian

Addresses: Vikram Sarabhai Space Centre, Indian Space Research Organization, Trivandrum – 695022, India ' Vikram Sarabhai Space Centre, Indian Space Research Organization, Trivandrum – 695022, India ' Vikram Sarabhai Space Centre, Indian Space Research Organization, Trivandrum – 695022, India ' Department of Avionics, Indian Institute of Space Science and Technology, Department of Space, Government of India, Trivandrum – 695022, India

Abstract: This paper presents the implementation of feedforward in digital domain to meet the audio susceptibility as per MIL STD 461C for voltage mode digitally controlled DC-DC converters. The feed-forward is accomplished through the estimation of duty ratio based on the input voltage at every switching cycle. The prototype converter developed is having galvanic isolation in the forward and feedback path and is based on single ended forward topology. An optimised discrete controller is provided in the feedback path to achieve desired dynamic performance. The feed forward scheme was implemented along with discrete feedback controller using a 16-bit fixed point microcontroller. The design of optimised discrete compensator and the audio rejection of a converter with such a feedback controller are presented. The simulation model of the converter with proposed digital feed forward/feedback controller using SIMULINK and its results against input disturbances are also presented. Experimental results are presented in this paper to validate the theoretical analysis.

Keywords: DC-DC converters; digital control; feedforward control; PID control; audio susceptibility; duty ratio estimator; audio rejection; feedback control; simulation.

DOI: 10.1504/IJPELEC.2013.057040

International Journal of Power Electronics, 2013 Vol.5 No.3/4, pp.200 - 215

Accepted: 26 May 2013
Published online: 06 Oct 2013 *

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