DC-DC Converter for remote power feeding

• US 4,507,721 A
• Filed: 07/21/1983
• Issued: 03/26/1985
• Est. Priority Date: 07/28/1982
• Status: Expired due to Term

• Current Assignee: Nippon Telegraph and Telephone Corporation
• Original Assignee: Nippon Telegraph and Telephone Corporation
• Inventors: Yamano, Seiichi, Ogiwara, Haruo
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): JONES, JUDSON
• Application Number:
  US06/515,754
• Time in Patent Office: 614 Days
• Field of Search: 363/18, 363/19, 363/20, 363/21, 363/22, 363/23, 363/24, 363/25, 363/26, 363/126, 363/39, 363/40, 363/45, 363/46, 336/84 C, 336/84 M
• US Class Current: 363/20
• CPC Class Codes: H02M 3/335 using semiconductor devices only

Abstract

A floating type DC-DC converter for remote power feeding is connected via a power separating filter to a signal line on which an AC signal is superimposed on DC power. The DC power separated by the power separating filter is stored in an input capacitor and is supplied by a switching operation of a switching element to the primary winding of a transformer and AC power induced in its secondary winding is supplied to an output capacitor after being rectified by a rectifying element. An electrostatic shield layer is interposed between the primary and secondary windings of the transformer and is connected to the capacitor connected to one of the primary and secondary windings. Rectifying element or switching element connecting means is provided by which an AC voltage induced in the winding portion on one side of the center winding point of the other of the primary and secondary windings and an AC voltage induced in the winding portion on the other side of the center winding point of said other winding are made substantially symmetrical with respect to the center winding point, opposite in polarity and substantially equal in amplitude to each other.

Claims

1. A DC-DC converter for remote power feeding which is connected via a power separating filter to a signal line on which an AC signal is superimposed on DC power, comprising:

an input capacitor connected to said power separating filter and supplied with the DC power separated by said power separating filter;

a transformer whose input and output sides float off ground, said transformer including a primary winding coupled to a pair of input terminals, a secondary winding having its opposing ends coupled to a pair of output terminals respectively, and an electrostatic shield interposed between said primary and secondary windings, one of said input terminals of said primary winding being connected to one side of said input capacitor, and said secondary winding being opened at its center winding point to provide two center terminals;

switching means connected between the other input terminal of said primary winding and the other side of said input capacitor, for supplying electric energy stored in said input capacitor to said primary winding through a switching operation; and

voltage balancing means operative to cause the AC voltage induced in a one half winding portion of one of said windings, relative to a center point on said one of said windings, to be substantially equal in potential and substantially opposite in polarity to the AC voltage induced in the other half winding portion of said one of said windings thereby to suppress common mode noise resulting from operation of said switching means, said voltage balancing means including rectifying means connected between said two center terminals of said secondary winding, and an output capacitor connected between said output terminals of said secondary winding;

said electrostatic shield being connected to a zero potential point in the primary side circuit which includes said primary winding, said switching means and said input capacitor.

2. A DC-DC converter for remote power feeding which is connected via a power separating filter to a signal line on which an AC signal is superimposed on DC power, comprising:

an input capacitor connected to said power separating filter and supplied with the DC power separated by said power separating filter;

a transformer whose input and output sides float off ground, said transformer including a primary winding coupled to a pair of input terminals, a secondary winding having its opposing ends coupled to a pair of output terminals respectively, and an electrostatic shield interposed between said primary and secondary windings, one of said input terminals of said primary winding being connected to one side of said input capacitor;

switching means connected between the other input terminal of said primary winding and the other side of said input capacitor for supplying electric energy stored in said input capacitor to said primary winding through a switching operation; and

voltage balancing means operative to cause the AC voltage induced in a one half winding portion of one of said windings, relative to a center point on said one of said windings, to be substantially equal in potential and substantially opposite in polarity to the AC voltage induced in the other half winding portion of said one of said windings thereby to suppress common mode noise resulting from operation of said switching means, said voltage balancing means including first and second rectifying means respectively connected to said output terminals of said secondary winding in series thereto in the forward direction, and an output capacitor connected between both ends of the series connection of said first rectifying means, said secondary winding and said second rectifying means;

said electrostatic shield being connected to a zero potential point in the primary side circuit which includes said primary winding, said switching means and said input capacitor.

3. A DC-DC converter for remote power feeding which is connected via a power separating filter to a signal line on which an AC signal is superimposed on DC power, comprising:

an input capacitor connected to said power separating filter and supplied with the DC power separated by said power separating filter;

a transformer whose input and output sides float off ground, said transformer including a primary winding, a secondary winding, and an electrostatic shield between said primary and secondary windings, said primary winding being connected to said input capacitor, said primary winding being opened at its center winding point to provide two center terminals;

switching means connected between said two center terminals of said primary winding; and

voltage balancing means operative to cause the AC voltage induced in a one half winding portion of one of said windings, relative to a center point on said one of said windings, to be substantially equal in potential and substantially opposite in polarity to the AC voltage induced in the other half winding portion of said one of said windings thereby to suppress common mode noise resulting from operation of said switching means, said voltage balancing means including rectifying means one side of which is connected to one end of said secondary winding, and an output capacitor connected between the other end of said secondary winding and the other side of said rectifying means;

said electrostatic shield being connected to a zero potential point in the secondary side circuit which includes said secondary winding, said rectifying means and said output capacitor.

4. A DC-DC converter for remote power feeding which is connected via a power separating filter to a signal line on which an AC signal is superimposed on DC power, comprising:

an input capacitor connected to said power separating filter and supplied with the DC power separated by said power separating filter;

a transformer whose input and output sides float off ground, said transformer including a primary winding, a secondary winding, and an electrostatic shield interposed between said windings, said primary winding being connected to a pair of input terminals and said secondary winding being coupled to a pair of output terminals;

first and second switching means connected respectively to said input terminals of said primary winding in series thereto, the opposing ends of the series connection of said first switching means, said primary winding and said second switching means being connected respectively to the opposite sides of said input capacitor; and

voltage balancing means operative to cause the AC voltage induced in a one half winding portion of one of said windings, relative to a center point on said one of said windings, to be substantially equal in potential and substantially opposite in polarity to the AC voltage induced in the other half winding portion of said one of said windings thereby to suppress common mode noise resulting from operation of said switching means, said voltage balancing means including rectifying means connected to one of said output terminals of said secondary winding in series thereto, and an output capacitor connected between the opposing ends of the series connection of said secondary winding and said rectifying means;

said electrostatic shield layer being connected to a zero potential point in the secondary side circuit including said secondary winding, said rectifying means and said output capacitor.