Electric power conversion systems – Current conversion – With condition responsive means to control the output...
Reexamination Certificate
1999-09-17
2001-05-29
Wong, Peter S. (Department: 2838)
Electric power conversion systems
Current conversion
With condition responsive means to control the output...
C363S127000
Reexamination Certificate
active
06239994
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to switching power converter circuits employing secondary side regulation and, more particularly, to double ended switching power converters employing secondary side regulation circuitry to produce dual and/or interleaved outputs.
2. Related Art
FIGS. 1-4
are schematic diagrams showing power converter circuits employing secondary side regulation to produce two output voltages Vout
1
and Vout
2
.
FIG. 1
employs a saturable reactor (mag amp) circuit including a transformer XFRMR (only the secondary winding being shown) coupled to two output regulation circuits. Each regulation circuit includes a series coupled saturable inductor L
3
, L
4
connected from one end of the XRFMR to a shunt diode D
1
, D
2
, respectively. First transistors Qa, Qc are coupled in series with the saturable inductors L
3
, L
4
, respectively, with their drains terminating at nodes from which second transistors Qb, Qd are respectively connected in a shunt relationship to ground. Output filter inductors L
1
, L
2
are coupled from the common nodes of Qa, Qb, and Qc, Qd, respectively, to filter capacitors C
1
and C
2
. The regulated output voltages Vout
1
and Vout
2
are taken across filter capacitors C
1
and C
2
, respectively.
A control circuit suitable for controlling diodes D
1
, D
2
and transistors Qa, Qb, Qc, and Qd may be selected from any of the known circuits as would be readily apparent to one skilled in the art.
FIG. 2
shows a schematic diagram for another switching power converter circuit employing secondary side regulation. While the output filter configuration of the circuit shown in
FIG. 2
is the same as that shown in
FIG. 1
, the arrangement of the regulation circuit elements differs. In particular, a single series diode D
1
is employed instead of saturable inductors L
3
, L
4
and shunt diodes D
1
and D
2
. Further, transistors Qa and Qc are both coupled in series with diode D
1
where the drains of transistors Qa and Qc are coupled together. The sources of transistors Qa and Qc are coupled to shunt transistors Qb and Qd, respectively. The regulated output voltages Vout
1
and Vout
2
are taken across output filter capacitors C
1
and C
2
, respectively.
A control circuit suitable for providing control signals to transistors Qa, Qb, Qc and Qd may be selected from any of the known circuits as would be apparent to one skilled in the art in view of the above disclosure.
FIG. 3
shows a schematic diagram of yet another switching power converter circuit employing secondary side regulation. In that circuit, back-to-back transistors Qa
1
and Qa
2
are coupled in series between the XFRMR and the output filter inductor L
1
. Transistor Qb provides a shunt circuit from the back-to-back transistors to ground. Similarly, back-to-back transistors Qc
1
and Qc
2
are coupled in series between the XFRMR and the output filter inductor L
2
, with transistor Qd providing a shunt circuit to ground. The regulated output voltages Vout
1
and Vout
2
are taken across filter capacitors C
1
and C
2
, respectively. A control circuit suitable for providing control signals to transistors Qa
1
, Qa
2
, Qb, Qc
1
, Qc
2
, and Qd may be selected from any of the known circuits as would be apparent to one skilled in the art having viewed the above disclosure.
FIG. 4
shows a schematic diagram of still another switching power converter circuit employing secondary side regulation. The circuit of
FIG. 4
is substantially similar to the circuit of
FIG. 3
except that back-to-back transistors Qa
1
and Qa
2
are replaced with an AC switch Qac
1
and back-to-back transistors Qc
1
and Qc
2
are replaced with AC switch Qac
2
.
There is, however, a need in the art for a new circuit topology and control method to obtain secondary side regulation which results in improvements in cost and efficiency.
SUMMARY OF THE INVENTION
The present invention includes a switching power converter, comprising:
a secondary side transformer winding having first and second ends across which an AC voltage is inducible;
a first regulation circuit including: a first switching element having a power terminal coupled to the first end of the secondary side transformer winding and another power terminal coupled to a first intermediate node; a second switching element having a power terminal coupled to the first intermediate node and another power terminal coupled to a common node; and a first inductor coupled from the first intermediate node to a first output node;
a second regulation circuit including: a third switching element having a power terminal coupled to the second end of the secondary side transformer winding and another power terminal coupled to a second intermediate node; a fourth switching element having a power terminal coupled to the second intermediate node and another power terminal coupled to the common node; and a second inductor coupled from the second intermediate node to a second output node; and
a control circuit operable to deliver respective drive signals to respective control terminals of the first, second, third, and fourth switching elements such that the switching elements turn on and off in such a manner that first and second regulated voltages appear between the first and second output nodes and the common node, respectively.
Other objects, features, and advantages will be apparent to those skilled in the art from the disclosure herein.
REFERENCES:
patent: 5528480 (1996-06-01), Kikinis et al.
patent: 5798633 (1998-08-01), Larsen et al.
patent: 6026005 (2000-02-01), Abdoulin
International Rectifier Corp
Laxton Gary L.
Ostrolenk, Faber, Gerb & Soffen, LLP.
Wong Peter S.
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