Electric power conversion systems – Current conversion – Including d.c.-a.c.-d.c. converter
Reexamination Certificate
2000-08-22
2002-08-13
Nguyen, Matthew (Department: 2838)
Electric power conversion systems
Current conversion
Including d.c.-a.c.-d.c. converter
C363S021180
Reexamination Certificate
active
06434026
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to generally to computer power supply systems and specifically to an improved multiple output power supply circuit.
BACKGROUND OF THE INVENTION
Many server computer systems utilize multiple output power supply circuits.
FIG. 1
shows a conventional multiple output power supply circuit. The circuit comprises an input voltage
10
, coupled to a first capacitor
14
and a transformer
18
. The transformer
18
is coupled to a first diode
12
, a switch
20
and two rectifiers
70
,
80
. The first rectifier
70
comprises a first winding
26
, a MAGAMP core
24
, a second diode
30
, a third diode
32
, a MAGAMP Driver
38
, a first inductor
40
, a first freewheeling diode
42
, a second capacitor
50
, a first resistor
58
, a second resistor
60
, and a first error amplifier
62
. The second rectifier
80
comprises a second winding
28
, a third diode
34
, an optocoupler
36
, a third resistor
37
, a second inductor
44
, a second freewheeling diode
46
, a second error amplifier
48
, a third capacitor
52
, a fourth resistor
54
, and a fifth resistor
56
.
The first rectifier
70
is coupled to the transformer
18
via the first winding
26
wherein the first winding
26
is coupled to the MAGAMP core
24
and the first freewheeling diode
42
. The MAGAMP core
24
is coupled to the second diode
30
and the third diode
32
wherein the third diode
32
is coupled to the first freewheeling diode
42
. The second diode
30
is coupled to the MAGAMP Driver
38
wherein the MAGAMP Driver
38
is further coupled to the first error amplifier
62
. The first freewheeling diode
42
is coupled the third diode
32
and to the first inductor
40
wherein the first inductor
40
is further coupled to the second capacitor
50
. The second capacitor
50
is coupled to the first resistor
58
wherein the first resistor
58
is further coupled to the second resistor
60
. The first and second resistors
58
,
60
are coupled to the first error amplifier
62
.
The second rectifier
80
is coupled to the transformer via the second winding
28
wherein the second winding
28
is coupled to the fourth diode
34
and the second freewheeling diode
46
. The second freewheeling diode
46
is coupled to the second inductor
44
and the third capacitor
52
. The switch
20
is coupled to a driver
16
wherein the driver
16
is coupled a pulse width modulator
22
. The pulse width modulator
22
is coupled to the optocoupler
36
wherein the optocoupler
36
is coupled to the third resistor
37
. The third resistor
37
is coupled to the second error amplifier
48
wherein the second error amplifier
48
is coupled to the third resistor
54
and the fourth resistor
56
.
The input voltage
10
is switched on and off at a very high frequency via the primary winding
4
-
6
of transformer
18
and switch
20
. The switch
20
is switched on and off by the pulse width modulator
22
and the driver
16
. The primary energy is transformed to the rectifiers
70
,
80
by means of the first and second windings
26
,
28
. Consequently, a main output voltage
66
is obtained by rectifying the switched voltage developed across the second winding
28
with the fourth diode
34
and the second freewheeling diode
46
. The rectified voltage is then averaged by the second inductor
44
and the third capacitor
52
thereby producing the main output voltage
66
. Furthermore, the main output voltage
66
is regulated by a feedback loop comprising the second error amplifier
48
, the optocoupler
36
and the pulse width modulator
22
.
Similarly, a second output voltage
64
is obtained by rectifying the switched voltage developed across the first winding
26
with the third diode
32
and the first freewheeling diode
42
. The rectified voltage is then averaged by the first inductor
40
and the second capacitor
50
thereby producing the second output voltage
64
. The second output voltage
64
is regulated by modulating the switched voltage developed across the first winding
26
with the MAGAMP core
24
, the MAGAMP driver
38
, and the first error amplifier
62
.
The transformer
18
is chosen whereby the duty ratio of forward energy transfer is close to 25%. This is done to provide regulated outputs for 20 ms interruptions of the AC line voltage. Because the forward energy is transferred 25% of the time, the third diode
32
and the fourth diode
34
are conducting the current for 25% of the time. Consequently, the first freewheeling diode
42
and the second freewheeling diode
46
are conducting the current for the remaining 75% of the time. Because power is dissipated when the diodes are conducting current, power is dissipated for 75% of the time while the freewheeling diodes
42
,
46
are conducting the current. This dissipation of power significantly reduces the overall efficiency of the conventional multiple output power supply circuit.
Accordingly, what is needed is a more efficient multiple output power supply circuit. The circuit should be simple, cost effective and capable of being easily adapted to current technology. The present invention addresses such a need.
SUMMARY OF THE INVENTION
A multiple output power supply circuit is disclosed. The power supply circuit comprises an input voltage wherein the input voltage is coupled to a driver and a transformer coupled to the input voltage wherein the transformer is coupled to at least one switch. The power supply circuit further comprises at least two rectifiers, each of the at least two rectifiers coupled to the transformer via a winding, each of the at least two rectifiers comprising at least one diode and a controlled switching device coupled in parallel.
According to the present invention, the circuit in accordance with the present invention provides multiple power outputs in a substantially more efficient manner.
REFERENCES:
patent: 4275341 (1981-06-01), Huber et al.
patent: 4733326 (1988-03-01), Harsch et al.
patent: 5373434 (1994-12-01), Malik
patent: 5400239 (1995-03-01), Caine
patent: 5402301 (1995-03-01), Mori et al.
patent: 5818704 (1998-10-01), Martinez
patent: 5909353 (1999-06-01), Alberter et al.
patent: 5946207 (1999-08-01), Schoofs
Hemena William
Malik Randhir S.
Nguyen Matthew
Sawyer Law Group LLP
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