Browse Prior Art Database

Three Phase Differential Line Filter

IP.com Disclosure Number: IPCOM000107906D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 46K

Publishing Venue

IBM

Related People

Carroll, LB: AUTHOR [+2]

Abstract

Power supplies with buck derived active power correction circuitry require a line filter to smooth out the input current. The line filter can be physically large since high power units typically have relatively low switching frequencies. This invention allows the use of lower voltage rated capacitors, which can be a great advantage when selecting capacitors by allowing flexibility in choosing capacitor construction. (Image Omitted)

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Three Phase Differential Line Filter

      Power supplies with buck derived active power correction
circuitry require a line filter to smooth out the input current.  The
line filter can be physically large since high power units typically
have relatively low switching frequencies.  This invention allows the
use of lower voltage rated capacitors, which can be a great advantage
when selecting capacitors by allowing flexibility in choosing
capacitor construction.

                            (Image Omitted)

      The capacitors are connected in a wye configuration with a
pseudo-neutral connection.  This reduces the voltage that the
capacitor sees compared to a conventional delta connection.  In
addition, resistors are added in parallel with the capacitors to keep
the capacitor voltages balanced, and provide some additional damping
effect.  Only one common-mode capacitor connected to ground is
required instead of three if C2 is greater the Cy.

      Another potential advantage of this circuit is its ability to
distribute a voltage transient to all three capacitors.  If a voltage
transient occurs on just one phase of the source, instead of just the
associated capacitor seeing the entire transient, the pseudo-neutral
point will shift, causing all capacitors to see a reduced amount of
the transient.

      Disclosed anonymously.