Electrical transmission or interconnection systems – Plural supply circuits or sources – One source floats across or compensates for other source
Reexamination Certificate
2002-08-28
2004-08-03
Riley, Shawn (Department: 2838)
Electrical transmission or interconnection systems
Plural supply circuits or sources
One source floats across or compensates for other source
C307S066000
Reexamination Certificate
active
06770984
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to the field of voltage regulators, and especially relates to an uninterruptible power supply.
BACKGROUND OF THE INVENTION
Please refer to FIG.
1
(
a
) which is a schematic diagram illustrating an isolated type of a mechanical regulator according to the prior art. As shown in FIG.
1
(
a
), the isolated type of a mechanical voltage regulator
100
includes an isolated transformer
101
, a relay
102
, and an input voltage sensor
103
. The input voltage sensor
103
is used to sense the input voltage V
in
, and then a trigger signal is generated thereby in order to actuate the relay
102
. Accordingly, the turn ratio of the isolated transformer
101
can be adjusted by turning on and off the relay
102
. By the adjustment of the turn ratio, the output voltage V
out
can be stabilized at a predetermined level.
Please refer to FIG.
1
(
b
) is a schematic diagram illustrating a non-isolated type of a mechanical voltage regulator according to the prior art. As shown in FIG.
1
(
b
), the non-isolated type of a mechanical regulator
200
includes a non-isolated transformer
201
, a relay
202
, and an input voltage sensor
203
. The input voltage sensor
203
is used to sense the input voltage V
in
, and then a trigger signal is generated thereby in order to actuate the relay
202
. Accordingly, the turn ratio of the isolated transformer
201
can be adjusted by turning on and off the relay
202
. By the adjustment of the turn ratio, the output voltage V
out
can be stabilized at a predetermined level.
According to the aforementioned art, the employment of the tap-changing transformers
100
,
200
was often adopted in stabilizing the system voltage at a customer side. By tuning the transformer taps to reach the expected turn ratio, the input voltage can be boosted or reduced to meet the application need while the load voltage is maintained at a certain level. This strategy seems feasible, yet their speed response and voltage regulation are restricted to the use of mechanical tap changers. Moreover, the bulk volume of the transformer may deteriorate the system encasement, thereby affecting the cost of the system.
Please refer to FIG.
2
(
a
). FIG.
2
(
a
) is a schematic diagram illustrating an electronic voltage regulator according to the prior art. As shown in FIG.
2
(
a
), the electronic voltage regulator
300
consists of at least one electronic switch
301
, at least one resistor
302
, at least one capacitor
303
, and at least one inductor
304
. Also a high frequency electrical switching technique is employed in the electronic voltage regulator
300
to stabilize the output voltage V
out
.
Please refer to FIG.
2
(
b
). FIG.
2
(
b
) is a schematic diagram illustrating an electronic voltage regulator according to the prior art. As shown in FIG.
2
(
b
), the electronic voltage regulator
400
consists of at least one electronic switch
401
, at least one resistors
402
, at least one capacitors
403
, and at least one inductor
404
. Also a high frequency electrical switching technique is employed in the electronic voltage regulator
300
to stabilize the output voltage V
out
.
The conventional electronic voltage regulators employ the power transistors and inductors to regulate input energy and increase the circuit ability to stabilize the output voltage. However, in these cases there exist large voltage phase differences between the system input and output. An additional safety design for an I/O bypass circuit becomes difficult and may degrade the operational reliability of the system. Besides, it is also hard to expand the voltage regulators with the function of Uninterruptible Power Supplier (UPS) due to less possibility of embedding DC batteries in these systems. It is therefore attempted by the applicant to deal with the above situation encountered with the prior art.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to propose an electronic voltage regulator and a control method thereof. Especially, when the electronic voltage regulator further includes an energy storage device, the inventive voltage regulator can be used as an uninterruptible power supply.
According to an aspect of the present invention, the electronic voltage regulator includes input terminals electrically connected to an power source which provides an input voltage, output terminals for providing a stable output voltage, a power converter electrically connected to the power source for generating a DC voltage and then converting the DC voltage to generate a compensation voltage to compensate the output voltage when the output voltage is different from a predetermined value, a switch with a first terminal electrically connected to the power source, a transformer with a primary winding and a secondary winding, wherein a first terminal of the primary winding electrically connected to an output terminal of the power converter, a second terminal of the primary winding electrically connected to a second terminal of the output terminals, a first terminal of the secondary winding electrically connected to a first terminal of the output terminals, a second terminal of the secondary winding electrically connected to a second terminal of the switch, and a third terminal of the switch electrically connected to the first terminal of the primary winding, and a switching control device electrically connected to the power converter for controlling the power converter to stabilize the output voltage.
Preferably, the power source is an AC power.
Preferably, the electronic voltage regulator further includes a DC-DC converter electrically connected to the DC voltage for providing a transformation of the DC voltage.
Preferably, the electronic voltage regulator further comprises a energy storage device electrically connected to the DC-DC converter in which the electric energy of the DC voltage charges the energy storage device through the DC-DC converter when the input voltage is within a specific range, and the electric energy of the energy storage device is transformed to compensate the DC voltage when the input voltage is out of the specific range.
Preferably, the energy storage device is a battery.
Preferably, the electronic voltage regulator is an uninterruptible power supply (UPS).
Preferably, the DC voltage is a DC-Bus voltage.
Preferably, the transformer is a variable voltage source depending on a connection configuration of the switch.
Preferably, the switching control device controls the compensation voltage having a phase difference with the input voltage and thereby keep the compensating power to be a positive value.
Preferably, the connection configuration of the switch includes a first connection configuration in which the second terminal of the switch is electrically connected to the first terminal of the switch to form a conducting path when the input voltage is within a specific range, and a second connection configuration in which, the second terminal of the switch is electrically connected to the third terminal of the switch to form a conducting path when the input voltage is out of the specific range.
Preferably, the power converter further includes an output switch assembly electrically connected to the DC voltage for converting the DC voltage to provide the compensation voltage to stabilize the output voltage.
Preferably, the switching control device obtains one group of voltages and one group of phases by feedback of the input voltage, the output voltage, and the DC voltage and thereby a pulse width modulation (PWM) signal is generated through the output switch assembly to stabilize the output voltage.
Preferably, the switching control device includes a DC voltage sensor unit electrically connected to the DC voltage for sensing the DC voltage to generate a first signal according to a magnitude of the DC voltage, a first voltage compensator unit electrically connected to the DC voltage sensor for transforming the first signal to a second signal, an input voltage sensor unit electrically connected to the pow
Pai Fu-Sheng
Tsai Ming-Tsung
Delta Electronics , Inc.
Riley Shawn
Volpe and Koenig P.C.
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