Switching power supply utilizing magnetically coupled series...

Details Switching power supply utilizing magnetically coupled series... Switching power supply utilizing magnetically coupled series...

1999-12-06

2001-06-26

Sterrett, Jeffrey (Department: 2838)

Electric power conversion systems

Current conversion

Including d.c.-a.c.-d.c. converter

C363S132000

Reexamination Certificate

active

06252782

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a switching power supply apparatus for supplying a regulated dc voltage to an industrial or consumer electronic appliance.
In recent years, the demand has been increasing greatly for switching power supply apparatus which is smaller in size, more stable in output and higher in efficiency, as electronic appliances decrease in size, price, high performance and power-conserving design advances.
As an example of a prior art switching power supply apparatus that addresses such requirements, a full bridge converter will be elucidated with reference to FIG.
6
. The drawing of
FIG. 6
is a circuit diagram showing the configuration of the prior art full bridge converter.
In
FIG. 6
, an input dc power supply
111
is connected between input terminals
112
a
and
112
b.
A first switching device
121
a
and a second switching device
122
a
are connected in series between the input terminals
112
a
and
112
b,
and are turned on alternately, with a duty ratio below 50% interleaving therebetween, by control signals supplied from a control circuit
171
. A third switching device
123
a
and a fourth switching device
124
a
are connected in series between the input terminals
112
a
and
112
b.
The third switching device
123
a
is controlled so as to turn on and off repetitively with the same timing as the second switching device
122
a.
The fourth switching device
124
a
is controlled so as to turn on and off repetitively with the same timing as the first switching device
121
a.
A parasitic capacitor is formed in parallel with each of the first switching device
121
a,
second switching device
122
a,
third switching device
123
a,
and fourth switching device
124
a.
In
FIG. 6
, the respective parasitic capacitors are shown as capacitors
121
c,
122
c,
123
c,
and
124
c.
A transformer
131
has a primary winding
131
a,
a first secondary winding
131
b,
and a second secondary winding
131
c.
The turns ratio of the primary winding
131
a,
the first secondary winding
131
b,
and the second secondary winding
131
c
is n:1:1. A first terminal of the primary winding
131
a
of the transformer
131
is connected to a connection point between the first switching device
121
a
and the second switching device
122
a.
A second terminal of the primary winding
131
a
of the transformer
131
is connected to a connection point between the third switching device
123
a
and the fourth switching device
124
a.
The operation of the prior art full bridge converter will be described below with reference to FIG.
7
. The drawing of
FIG. 7
is a waveform diagram for explaining the operation of the full bridge converter according to the prior art.
In
FIG. 7
, G
1
, G
2
, G
3
, and G
4
are the control signals supplied to the first to fourth switching devices
121
a,
122
a,
123
a,
and
124
a,
respectively.
In
FIG. 7
, V
122
indicates the voltage applied to the second switching device
122
a,
V
124
indicates the voltage applied to the fourth switching device
124
a,
and V
131
a
the voltage applied to the primary winding
131
a
of the transformer
131
.
In
FIG. 7
, I
131
a
indicates the current flowing in the primary winding
131
a
of the transformer
131
, I
121
indicates the current flowing in the parallel circuit consisting of the first switching device
121
a
and the capacitor
121
c.
And, the waveform of I
122
represents the current flowing in the parallel circuit consisting of the second switching device
122
a
and the capacitor
122
c.
To indicate the variation over time of the operating condition, time is plotted on a time scale of T
0
to T
4
in FIG.
7
.
At time T
0
, when the first switching device
121
a
and the fourth switching device
124
a
are simultaneously turned on by the control signals G
1
and G
4
from the control circuit
171
, the voltage V
131
a
being applied to the primary winding
131
a
of the transformer
131
becomes the input voltage Vin. Voltage V
131
b
on the first secondary winding
131
b
of the transformer
131
and voltage V
131
c
on the second secondary winding
131
c
both becomes a voltage Vin
.
As a result, a diode
161
is turned on and a diode
162
is turned off, so that voltage V
163
across a third inductor
163
is a voltage Vin
−Vout. Further, the sum of the magnetizing current in the primary winding
131
a
of the transformer
131
and a primary side converted current of the current flowing in the third inductor
163
flows into the first switching device
121
a.
The primary side converted current is the component such that a current flowing in the third inductor
163
is converted into the current flowing through the primary winding
131
a.
However, at time T
0
, at the instant when the first switching device
121
a
changes from the OFF state (nonconductive state) with a voltage Vin/2 applied thereto to the ON state (conductive state), the discharging of the capacitor
121
c
and the charging of the capacitor
122
c
occur instantaneously. This causes a spike current to flow, as shown with I
121
of FIG.
7
.
At time T
1
, when the first switching device
121
a
and the fourth switching device
124
a
are simultaneously turned off, the secondary current in the transformer
131
flows being split between the first secondary winding
131
b
and the second secondary winding
131
c
so that no discontinuity is caused in the magnetizing energy of the third inductor
163
. At this time, the diodes
161
and
162
are both ON, and the voltages V
131
b
and V
131
c
on the first and second secondary windings
131
b
and
131
c
both become zero.
The voltage V
163
across the third inductor
163
is then a voltage −Vout. Further, at the instant that the first switching device
121
a
and the fourth switching device
124
a
are turned off, an unwanted resonant voltage such as shown in V
131
a
in
FIG. 7
occurs due to leakage inductance of the transformer or energy stored in inductance parasitizing on wiring.
At time T
2
, when the second switching device
122
a
and the third switching device
123
a
are simultaneously turned on, the voltage V
131
a
being applied to the primary winding
131
a
of the transformer
131
becomes the voltage −Vin. Then, the voltages V
131
b
and V
131
c
on the first and second secondary windings
131
b
and
131
c
of the transformer
131
both become a voltage −Vin
. As a result, the diode
161
is turned off and the diode
162
is turned on, and the voltage V
163
across the third inductor
163
becomes a voltage Vin
−Vout.
At this time, the sum of the magnetizing current in the primary winding
131
a
of the transformer
131
and the primary side converted current of the current flowing in the third inductor
163
flows through the second and third switching devices
122
a
and
123
a.
The primary converted current is the component such that a current flowing in the third inductor
163
is converted into the current flowing through the primary winding
131
a.
Further, at time T
2
, at the instant when the second switching device
122
a
and the third switching device
123
a
are simultaneously turned on, spike noise occurs, just as at time T
0
.
At time T
3
, when the second switching device
122
a
and the third switching device
123
a
are simultaneously turned off, the secondary current in the transformer
131
flows being split between the first secondary winding
131
b
and the second secondary winding
131
c
so that no discontinuity is caused in the magnetizing energy of the third inductor
163
.
As a result, the diodes
161
and
162
are both turned on, and the voltages V
131
b
and V
131
c
on the first and second secondary windings
131
b
and
131
c
both become zero. At this time, the voltage V
163
across the third inductor
163
is a voltage −Vout. Further, at time T
3
, at the instant when the second switching device
122
a
and the third switching device
123
a
are simultaneously turned off, an unwanted resonant voltage occurs, just as at time T
1
.
At time

Affiliated with

Also associated with

Rating

Switching power supply utilizing magnetically coupled series... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Switching power supply utilizing magnetically coupled series..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Switching power supply utilizing magnetically coupled series... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2503396