Electricity: power supply or regulation systems – Output level responsive – Using a three or more terminal semiconductive device as the...
Reexamination Certificate
2001-05-18
2002-09-17
Berhane, Adolf Deneke (Department: 2838)
Electricity: power supply or regulation systems
Output level responsive
Using a three or more terminal semiconductive device as the...
C363S021060
Reexamination Certificate
active
06452367
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a multi-outputting power supply circuit including a main-output circuit section and at least one sub-output circuit section, and more particularly, to the multi-outputting power supply circuit, in which, the sub-output circuit section is controlled by a magnetic amplifier.
The present application claims priority of Japanese Patent Application No. 2000-149127 filed on May 19, 2000, which is hereby incorporated by reference.
2. Description of the Related Art
As shown in
FIG. 11
, this kind of a conventional multi-outputting power supply circuit
100
is mainly made up of an input circuit section
1
, a transformer
2
, a main-output circuit section
3
, and a plurality of sub-output circuit sections
4
,
5
, . . .
The input circuit section
1
is provided with a direct current power supply section
1
a
, an input smoothing capacitor
1
b
, a PWM (Pulse width Modulation) controlling circuit
1
c
, and a main-switch made up of for example, an N channel type MOS transistor (hereinafter may be referred to as NMOS
1
d
). The transformer
2
includes a primary winding
2
a
connected with input circuit section
1
, a plurality of secondary windings
2
b
,
2
c
,
2
d
, connected respectively with sub-output circuit sections
4
,
5
, . . . .
The main output circuit section
3
is provided with a first diode
3
a
, a smoothing choke coil
3
b
, a second diode
3
c
, a smoothing capacitor
3
d
, a dummy resistor
3
e
, and a constant-voltage controlling circuit
3
f
, thus supplying an electric power to a load RL
1
. The sub-output circuit section
4
is provided with a magnetic amplifier
4
a
, the third diode
4
b
, a smoothing choke coil
4
c
, the fourth diode
4
d
, a smoothing capacitor
4
e
, a constant-voltage controlling circuit
4
f
, resistors
4
g
and
4
h
, a transistor
4
I, and diode
4
j
. The sub-output circuit section is connected to a load RL
2
. The sub-output circuit section
5
is the same structure as the sub-output circuit section
4
, and is connected to a load RL
3
. And the multi-outputting power supply circuit may be provided with a electric dummy circuit
3
g
as shown in
FIG. 12
instead of a dummy resistor
3
e
. The electric dummy circuit
3
g
is provided with a resistor
3
h
, a NMOS
3
I, an output electric current detecting circuit
3
j
, and resistor
3
k
, and becomes ON state so as to flow dummy electric current through a resistor
3
h
only when a load is light.
With the above configuration, main output circuit section
3
is capable of outputting more electric power under less load variation than any sub-output power sections
4
,
5
, . . . .
And a duty ratio of switching in a primary side (input circuit section
1
) is controlled by a negative feedback signal fed to the primary side, based on an output voltage variation of a secondary side (main output circuit section
3
).
In each of sub-output circuit sections
4
,
5
, . . . , magnetic amplifier
4
a
controls an alternating current voltage having a specified duty ratio based on an output voltage fed from main output circuit section
3
, hereby producing output voltage having a specified level.
Next, an operation principle of magnetic amplifier
4
a
will be described in detail, with reference to
FIGS. 13 and 14
.
FIGS. 13 and 14
are illustration for explaining an operation principle of the magnetic amplifier
4
a
as shown in FIG.
11
.
As shown in
FIG. 14
, when a pulse electric current with a pulse width×&mgr;s flows, the magnetic amplifier
4
a
is an ON state. Here, even if the pulse electric current repeats a shifting between the ON state and an OFF state, a magnetic state of a magnetic amplifier
4
a
will can only go and back between a point A and a point B, in which, the point A corresponds to a maximum value of pulse current and the point B corresponds to a magnetic field zero or an electric current zero, and the magnetic amplifier
4
a
remains in the on state. However, while pulse electric current is the OFF state, because a slight electric current (that is to say, reset current) flows through the magnetic amplifier
4
a
in the opposite direction to the pulse electric current, a magnetic state of a magnetic amplifier
4
a
shifts to a point C, and the magnetic amplifier
4
a
becomes in the OFF state. In this state, even if a voltage E is supplied to the magnetic amplifier
4
a
in the positive direction, electric current does not flow at once, however, the electric current begins to flow after &Dgr;T time.
&Dgr;T is obtained by the following formula.
Magnetic flux (&phgr;)=The product of voltage and Time (E×T) Equation 1
&Dgr;T=&Dgr;&phgr;/E Equation 2
PWM is executed by controlling the &Dgr;T by the reset current. Here, when the following formula is satisfied, the current does not flow at all.
X=&Dgr;T Equation 3
That is to say, PWM is executed at range from 0 to 100 percent by adjusting a width of &Dgr;&phgr; of magnetic amplifier
4
a.
In the multi-outputting power supply circuit
100
, the direct current input power voltage V
1
a
is produced in the direct current power section
1
a
, and is output. The direct current input power voltage V
1
a
is smoothed by the input smoothing capacitor
1
b
. A control signal V
1
c
with a pulse width corresponding to a fixed frequency and a detective signal V
3
f
is produced. The direct current input power voltage V
1
a
is controlled for an ON or OFF state so as to produce an alternating current voltage V
1
d
with a pulse width corresponding to a fixed frequency and detective signal V
3
f
. The alternating current voltage V
1
d
is transformed by the transformer
2
so as to produce an alternating current voltage V
2
b
and the alternating current voltage V
2
c
, V
2
d.
The alternating current voltage V
2
b
is smoothed by the first diode
3
a
so as to produce a pulsating voltage V
3
a
. Electromagnetic energy of the pulsating voltage V
3
a
is stored in the smoothing choke coil
3
b
. When the first diode
3
a
becomes in an OFF state and the second diode
3
c
becomes in an ON state, the electromagnetic energy is then supplied to the smoothing capacitor
3
d
. The pulsating voltage V
3
a
is smoothed by the smoothing capacitor
3
d
so as to produce a direct current output power voltage V
3
. The direct current output power voltage V
3
is supplied to the dummy resistor
3
e
and the load RL
1
. When the direct current output power voltage V
3
changes, the constant-voltage controlling circuit
3
f
detects a change of the direct current output power voltage V
3
so as to produce the detective signal V
3
f
. The detective signal V
3
f
is supplied to the PWM controlling circuit
1
c
, and a pulse width of the alternating current voltage V
1
d
is controlled for negative feed-back by the PWM controlling circuit
1
c.
The alternating current voltage V
2
c
according to a turn ratio between the primary winding
2
a
and the secondary winding
2
c
is produced based on a duty ratio predetermined by the PWM controlling circuit
1
c
at the secondary winding
2
b
of the transformer
2
. The alternating current voltage V
2
c
is smoothed by the third diode
4
b
through the magnetic amplifier
4
a
so as to produce a pulsating voltage V
4
b
. The electromagnetic energy of the pulsating voltage V
4
b
is stored in the smoothing choke coil
4
c
. When the third diode
4
b
becomes in an OFF state and the fourth diode
4
d
becomes in an ON state, the electromagnetic energy is supplied to the smoothing capacitor
4
e
. The pulsating voltage V
4
b
is smoothed by the smoothing capacitor
4
e
so as to produce a direct current output power voltage V
4
. And a direct current output power voltage V
4
is output from the sub-output circuit section
4
to the load RL
2
. Stabilizing the direct current output power voltage v
4
is performed by using a hysteres is characteristic of the magnetic amplifier
4
a
. That is to say, a change of the direct current output power voltage V
4
is
McGinn & Gibb PLLC
NEC Corporation
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