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Switched-Mode Post Regulation Technique for DC-DC Converters

IP.com Disclosure Number: IPCOM000114253D
Original Publication Date: 1994-Nov-01
Included in the Prior Art Database: 2005-Mar-28
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Lange, GG: AUTHOR [+2]

Abstract

Disclosed is a technique to regulate multiple independent voltages from a DC-DC converter with conventional trailing-edge Pulse Width Modulation (PWM) and current programmed control of all outputs. The technique uses a connection of current sensing transformers to remove undesirable current components that would otherwise appear in the major output's current control signal. It permits the use of an active semiconductor switch and conventional control techniques to perform post regulation without the disadvantages of alternative methods.

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Switched-Mode Post Regulation Technique for DC-DC Converters

      Disclosed is a technique to regulate multiple independent
voltages from a DC-DC converter with conventional trailing-edge Pulse
Width Modulation (PWM) and current programmed control of all outputs.
The technique uses a connection of current sensing transformers to
remove undesirable current components that would otherwise appear in
the major output's current control signal.  It permits the use of an
active semiconductor switch and conventional control techniques to
perform post regulation without the disadvantages of alternative
methods.

      The Figure illustrates the technique on a two-output DC-DC
converter.  The primary winding of the power transformer T1 is
energized by one of many possible arrangements of power switchers,
drive circuits, and control components.  It is desired to control the
output voltages V01 and V02 that are derived from the secondary
windings of T1.  Pulse width modulation of the voltage on the primary
of T1 controls the main (high current) output V01, while truncation
of the pulse by power transistor switch Q1 regulates the auxiliary
(lower current) output V02.  The waveforms in the Figure show the
durations t1 and t2 of the resulting pulses with period T that
produce the output voltages.

      Trailing-edge PWM with current programmed control terminates
the power pulses to the outputs when currents in their respective
secondary windings reach levels necessary t...