Electric power conversion systems – Current conversion – Having plural converters for single conversion
Reexamination Certificate
2001-01-29
2002-04-30
Nguyen, Matthew (Department: 2838)
Electric power conversion systems
Current conversion
Having plural converters for single conversion
C307S066000, C307S082000
Reexamination Certificate
active
06381156
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an uninterruptible duplexed power supply system for driving a load by the rectified output from a commercial alternating current power supply (AC), for instance, during normal operation and for driving the load by the output from a direct current power supply such as a rechargeable battery in the event of an abnormality such as a power outage, and more particularly relates to an uninterruptible duplexed power supply system used for the operation of critical devices such as burglar alarms, fire alarms, communications systems, information systems (such as server computers and factory automation personal computers), precision medical devices, and automated machinery, and to a unit plug-in structure for an uninterruptible duplexed power supply system. “Power outage” as used herein refers to the cutoff of the supply of power (current), such as when the power supplied from an electric company is cut off, or when the supplied power is cut off because a breaker is tripped, a device is unplugged, a wire is cut, or the like.
2. Description of the Related Art
Continuous, uninterrupted operation 24 hours a day for five years, for example, is required of server computers and the like in particular, and the power supply system shown in
FIG. 9
, for instance, is typical of the structure thereof. This system comprises an uninterruptible power supply (UPS)
90
connected to a commercial AC power supply, two switching power supplies
91
and
92
to which the switching power supply that serves as the server computer power supply is connected in parallel for the sake of safety (duplexing), and two sets of diodes
93
and
94
for preventing the current outputted from either of these switching power supplies
91
and
92
from sneaking into the other switching power supply, and is designed so that electrical power can be supplied at all times to the load. Therefore, if the switching power supply
91
should suffer a malfunction due to a lightning surge, any of various impulse surges, or the like being introduced into the AC input line, then the other switching power supply
92
will take over and be able to supply power to the load.
With the above structure, because the switching power supplies
91
and
92
are connected in series to the uninterruptible power supply
90
, the total efficiency, which is obtained by multiplying the 75 to 80% efficiency of the switching power supplies
91
and
92
by the 75 to 80% efficiency of the uninterruptible power supply
90
, is only about 55 to 64%, so there is a problem with energy loss.
Another problem is that because the uninterruptible power supply
90
and the two switching power supplies
91
and
92
are all separate components, not only is a large amount of space required, but the cost is also high.
Also, the two diodes
93
and
94
for preventing sneak current are required for each of the two switching power supplies
91
and
92
, so a total of four or more diodes are required, which makes the system bulkier and leads to lower efficiency through diode forward loss.
The inventors have previously proposed a solution to the above problems. This is discussed in Japanese Patent No. 2,702,048, in which a primary circuit, equipped with a rectification circuit for rectifying the alternating current from a commercial AC power supply and switching elements or the like provided on the output side of this rectification circuit, is connected to the primary winding of a high-frequency transformer, a secondary DC output circuit that supplies power to the load is connected to the secondary winding of this high-frequency transformer, and a battery-side converter circuit equipped with switching elements or the like for operating according to the operating state of the primary circuit is connected to the tertiary winding of the high-frequency transformer. The result is an uninterruptible switching regulator (uninterruptible duplexed power supply system) that integrates the primary circuit (AC power supply circuit), the battery-side converter circuit, the switching circuit provided on the output side of these, and the secondary DC output circuit that supplies power to the load.
Nevertheless, although the load can be driven on an emergency basis by the battery-side converter circuit if the primary circuit should suffer a malfunction, the damaged parts in the malfunctioned primary circuit have to be replaced. This replacement requires that the computer be temporarily shut down by a specific operation, and the power supply then turned off, and this shutdown operation is not only troublesome, but the computer cannot be operated during the replacement work, resulting in the problem that the safety and reliability of the power supply cannot be fully ensured.
It is also difficult in structural terms to perform the above-mentioned replacement of damaged parts in the primary circuit right in the middle of (for a short time) the drive of the load by the battery-side converter circuit.
Accordingly, the method that had to be adopted up to now was to connect the above-mentioned uninterruptible switching regulator (uninterruptible duplexed power supply system) in parallel, just as with the switching power supplies
91
and
92
in FIG.
9
. Furthermore because the connection is in parallel, the diodes
93
and
94
in
FIG. 9
are needed to prevent sneak current, and the only effect is that the uninterruptible power supply (UPS)
90
is unnecessary, so there is still room for improvement in terms of reducing the size so as to take up less space, and lowering cost.
SUMMARY OF THE INVENTION
In light of the above situation, it is an object of the present invention to provide an uninterruptible duplexed power supply system that is highly reliable and has excellent durability, with which a more compact size and higher efficiency are both achieved, and with which a malfunction of the power supply circuit can be repaired in a live state.
In order to achieve the stated object, the present invention is characterized in. that there are provided a first unit that uses a first power supply as its input source and that houses a first primary circuit equipped with a switching element on the output side, and a second unit that uses the first power supply or a second power supply that is different from the first power supply and that houses a second primary circuit equipped with a switching element on the output side, a main component to which the outputs of the first unit and second unit are inputted comprises a primary winding of a high-frequency transformer to which the first unit and the second unit are connected via a connection component, a secondary DC output circuit that is connected to a secondary winding of the high-frequency transformer and supplies electrical power to a load, a PWM control circuit for keeping the output from this secondary DC output circuit at a constant voltage, and a battery-side converter circuit that is connected via a tertiary winding of the high-frequency transformer, is equipped with a switching element on the output side, and is used for charging a rechargeable battery for backup in the event of a power outage, the first unit and the second unit can be installed or removed in a live state between a connected state in which they are electrically connected to the two primary windings of the high-frequency transformer and a disconnected state in which this connected state has been released, and the output signals from the PWM control circuit are inputted to the gate circuits of the various switching elements of the first unit, second unit, and battery-side converter circuit.
Therefore, if the supply of power to the load is cut off due to a power outage in the input of the first unit and second unit, power can be instantaneously supplied from a rechargeable battery and the load can be driven on an emergency basis, without being shut down, for a time corresponding to the capacitance of the rechargeable battery. Also the durability of the power supply system can be enhanced co
Imanishi Tsurayoshi
Sakai Setsuo
Armstrong Westerman & Hattori, LLP
Nihon Protector Co., Ltd.
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