Electric power conversion systems – Current conversion – Including d.c.-a.c.-d.c. converter
Reexamination Certificate
1999-08-11
2001-12-25
Nguyen, Matthew (Department: 2838)
Electric power conversion systems
Current conversion
Including d.c.-a.c.-d.c. converter
Reexamination Certificate
active
06333862
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power supply, in particular to a switched mode power supply (SMPS) and a method of controlling the same.
2. Description of the Background Art
In a conventional switched mode power supply (SMPS), when the electrical loads connected with an output terminal of the switched mode power supply do not draw electric power, the switched mode power supply assumes a standby state. Only is when the electric loads require power, the SMPS provides power to the electric loads, by operating in a normal mode.
FIG. 1
illustrates a circuit of a switched mode power supply which is composed of a main power unit, an auxiliary power unit and a controller.
The main power unit includes an input filter unit
101
removing noise from AC power supplied from an AC power source, a rectification/smoothing unit
102
rectifying the AC power to DC by a full wave rectification and smoothing the DC voltage to a certain level, a main transformer
104
to a primary winding of which is repeatedly supplied and disconnected DC power supplied from the rectification/smoothing unit
102
in accordance with an ON/OFF operation of a switching device Q
1
, a snubber
103
removing noise from power supplied to the primary winding of transformer
104
, the noise generated when the switching device Q
1
is operated, a rectification/smoothing unit
105
rectifying AC voltages induced in the secondary windings of the main transformer
104
and smoothing the resulting DC voltage to a certain level, a rectification/smoothing unit
105
-
1
generating a certain direct current voltage from the AC voltage induced in an auxiliary winding of the main transformer
104
, and a driving controller
106
receiving an output voltage of the rectification/smoothing unit
102
and the direct current voltage from the rectification/smoothing unit
105
-
1
and controlling an ON/OFF operation of the switching device Q
1
in accordance with a control signal from a signal feedback unit
107
, which will be explained later.
The auxiliary power unit includes a driving controller
111
receiving an output voltage of the rectification/smoothing unit
102
and controlling an ON/OFF operation of a switching device Q
2
, and an auxiliary transformer
108
to a primary winding of which is repeatedly supplied and disconnected the output voltage of the rectification/smoothing unit
102
in accordance with the ON/OFF operation of the switching device Q
2
thereby inducing an AC voltage in a secondary winding of the auxiliary transformer
108
which is connected to a rectification/smoothing unit
109
and a rectification/smoothing unit
109
-
1
. The rectification/smoothing unit
109
-
1
rectifies the AC voltage induced in the secondary winding of auxiliary transformer
108
and outputs a certain direct current voltage to the driving controller
111
in accordance with the switching operation of the switching device Q
2
. The rectification/smoothing unit
109
rectifies the voltage induced in the secondary winding of the auxiliary transformer
108
in accordance with a switching operation of the switching device Q
2
and smoothes the thusly rectified a direct current voltage. The auxiliary power unit also includes a snubber
110
removing noise which is generated in the auxiliary transformer
108
when the switching device Q
2
is operated.
The control unit includes a microcomputer
114
receiving as its supply power in a normal operating mode an output voltage among the output voltages outputted from the rectification/smoothing unit
105
, and also receiving an output voltage of the rectification unit
109
as a supply voltage in a power saving mode. The microcomputer
114
outputs a control signal for controlling an ON/OFF operation of the switching device Q
1
in the normal mode. The control unit also includes a signal feed back unit
107
detecting information on the state of the power consumption of loads connected to the output terminals of the rectification smoothing unit
105
receiving a control signal from the microcomputer
114
10
and transferring the information and the control signal to the driving controller
106
, a timer
112
generating a timing signal and supplying the thusly generated timing signal to the microcomputer
114
, and a backup unit
113
receiving a direct current voltage from the rectification/smoothing unit
105
and also from the rectification/smoothing unit
109
and storing backup power for operating of the microcomputer
114
in the standby mode.
As shown in
FIG. 2
illustrating in detail the circuit of
FIG. 1
, the rectification/smoothing units
105
,
105
-
1
,
109
and
109
-
1
are circuits each formed of a diode D
1
-DM, DD
5
-DD
6
and a capacitor C
1
-CM, CC
5
-CC
6
. The rectification/smoothing unit
109
further includes a regulator
109
-
2
and a diode DD
7
.
The operation of the thusly constituted conventional switched mode power supply will be explained.
When AC mains power is applied into the input filter unit
101
, the input filter unit
101
removes noise from the AC mains power and outputs it to the rectification/smoothing unit
102
. The rectification/smoothing unit
102
rectifies the noise-removed AC power by a full wave rectification, smoothes it, and then outputs a certain level direct current voltage to the primary windings of the transformers
104
and
108
.
At this time, as the driving controller
106
in the main power unit turns on/off the switching device Q
1
on/off, AC voltages are induced in the secondary windings of the main transformer
104
and are applied to the rectification/smoothing unit
105
. As the driving controller
111
in the auxiliary power unit turns the switching device Q
2
on/off, an AC voltage is induced in the secondary winding of the auxiliary transformer
108
and is applied to the rectification/smoothing unit
109
.
The rectification/smoothing unit
105
outputs the DC voltages which are smoothed after a half wave rectification to the loads (not shown), and the rectification/smoothing unit
109
outputs a regulated voltage, which is smoothed after a half wave rectification through the regulator circuit
109
-
2
and the diode DD
7
. At this time, the regulated voltage outputted from the rectification/smoothing unit
109
is supplied to the back-up unit
113
and the microcomputer
114
via a line connected with diode DD
7
.
In the normal mode in which the loads normally consume power, the rectification/smoothing unit
105
outputs a plurality of output voltages, and if one of the output voltages is applied as a supply voltage of the microcomputer
114
, a positive voltage is applied at the output terminal of the diode DD
7
connected with the output terminal of the rectification/smoothing unit
109
, so that the diode DD
7
does not forwardly conduct. Therefore, the regulated voltage outputted from the rectification/smoothing unit
109
is not applied to the microcomputer
114
. The microcomputer
114
receives a supply voltage from the rectification/smoothing unit
105
and controls the entire operations of the system based on a timing signal generated by the timer
112
for thereby controlling the power state of the loads.
When the microcomputer
114
checks the power consumption state of the loads, if it is judged that the loads do not consume much power, the microcomputer
114
controls the system and changes the normal mode into a power saving mode.
In the power saving mode, the microcomputer
114
outputs an ON/OFF control signal which controls the switching device Q
1
at a low frequency by controlling the driving controller
106
via the signal feedback unit
107
so that power corresponding to the lower power consumption of the loads is outputted. Namely, when the microcomputer
114
increases the ON/OFF operation time of the switching device Q
1
, the levels of the voltages induced in the secondary windings of the main transformer
104
are decreased. Therefore, the rectification smoothing unit
105
which receives the lower voltage levels supplies DC voltages co
Lee Dong Ju
Pyeon Dae Beum
LG Electronics Inc.
Nguyen Matthew
LandOfFree
Switched mode power supply and controlling method thereof does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Switched mode power supply and controlling method thereof, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Switched mode power supply and controlling method thereof will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2581645