Browse Prior Art Database

Phase Shift Modulator with 0o to 180o Phase Shift Capability

IP.com Disclosure Number: IPCOM000109196D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 2 page(s) / 78K

Publishing Venue

IBM

Related People

Bogdan Jr, CA: AUTHOR

Abstract

Disclosed is a circuit which phase-shift modulates two square-waves and extends the modulation range to its extremes: in-phase (zero degrees phase-shift) to one-hundred and eighty degrees out of phase. The circuit is used to control the drive sequence of the power switches in a Phase-Shifted Full-Bridge DC/DC power converter.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 64% of the total text.

Phase Shift Modulator with 0o to 180o Phase Shift Capability

       Disclosed is a circuit which phase-shift modulates two
square-waves and extends the modulation range to its extremes:
in-phase (zero degrees phase-shift) to one-hundred and eighty degrees
out of phase.  The circuit is used to control the drive sequence of
the power switches in a Phase-Shifted Full-Bridge DC/DC power
converter.

      In the figure, the fixed-frequency clock and its complement set
the timing for the modulator.  The signal AOUT toggles with each
rising edge of CLOCK and thus is a square-wave at 1/2 the clock
frequency.  The remainder of the circuitry develops the signal COUT,
which is also a square-wave at 1/2 the clock frequency.  It, however,
may be phase-shifted up to 180o from AOUT, depending on the status of
the RAMP, EAOUT, and INHIBIT signals.

      When the modulator controls a Phase-Shifted Full-Bridge
converter, the RAMP signal is a scaled real-time sample of the
converter's output inductor current.  The EAOUT signal is the output
of the error amplifier, which is the amplified difference between the
output voltage of the converter and a reference.  When the
converter's output voltage is in regulation, EAOUT represents the
average output current of the converter.  INHIBIT forces the
phase-shift to zero degrees; it typically will be active (high) in a
fault condition.

      Under normal operating conditions (when the converter is in
regulation), the amount of...