Electricity: battery or capacitor charging or discharging – Serially connected batteries or cells – Having variable number of cells or batteries in series
Reexamination Certificate
2000-06-15
2001-03-13
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Serially connected batteries or cells
Having variable number of cells or batteries in series
C307S066000
Reexamination Certificate
active
06201371
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an uninterruptible power supply apparatus, in particular to an uninterruptible power supply apparatus in which power consumption of the apparatus, load apparatus, and peripheral devices can be reduced in accordance with the operating conditions of the load apparatus such as a computer and the like connected to the uninterruptible power supply apparatus.
BACKGROUND OF THE TECHNOLOGY
As uninterruptible power supply apparatuses, an apparatus called continuous commercial power feeding system has hereto been employed. In this system, in normal operation, the input power is directly supplied to a load while charging a battery through a charging circuit; and, in the event of a power failure, power is supplied from the battery by mechanically switching a relay from commercial power supply to an inverter circuit. Although this system has an advantage of a low cost and a low loss because the specification has now become standard, it suffered problems of being susceptible to the fluctuation of the commercial power supply as the input power is directly supplied to the load and also being difficult to make it smaller and lighter because a large size transformer is required. It also suffers added disadvantage of requiring a switching time in the event of a power failure for mechanically switching a relay to obtain power from the battery. For instance, when a computer is used as a load apparatus, fluctuation of the power supply voltage or suspension of power supply during the period of switching may cause malfunction of the computer, leaving room for improvement.
There was available a continuous commercial power feeding system with auto voltage regulation function in which the continuous commercial power feeding system had been improved by the use of a voltage step-up/step-down circuit to cope with a fluctuation of the commercial power. With this system, it was possible to maintain the supply voltage to the load within a predetermined range by stepping up the output voltage when the supply voltage had dropped and stepping down the output voltage when the supply voltage had increased. This way, it became possible to supply a stable voltage to the load when compared with the aforementioned system; for example the output voltage range could be maintained at 100+/−10 V for an AC input voltage of 100 V. However, in this system, too, perfectly stable supply of voltage to the load was not possible because of the time required for switching for voltage step-up or step-down. Also, there was a risk of accelerating deterioration of the battery due to battery backed-up operation for several seconds during switching for voltage step-up or step-down. Furthermore, problems of difficulty for smaller size and lighter weight design remained to be solved.
As another system other than the continuous commercial power feeding system, a continuous inverter power feeding system has been in actual use. In this system, in the normal condition, power is supplied to a load apparatus by first converting commercial power supply into a DC power followed by reconverting it back to an AC power by an inverter circuit while at the same time charging a battery with a charging circuit. In the event of a power failure, power is supplied to the load apparatus by operating the inverter circuit using the battery as the power supply. In this system, as power is supplied via an inverter circuit, it is always possible to supply a nearly constant voltage within a range of +/−3% to the load even when there is a fluctuation in the commercial power supply. Also, as there is no mechanical switching circuit, it is possible to supply power to the load apparatus without instantaneous interruption even in the event of a power failure. Furthermore, as a large size transformer is not required, it does not suffer the problems of the above-described continuous commercial power feeding system.
However, from the standpoint of power saving, the continuous inverter power feeding system in which an internal circuit was in constant operation consumed more power and was clearly inferior to the two earlier described types of continuous commercial power feeding system.
As an uninterruptible power supply apparatus has been designed and developed with a view to protecting supply of power to connected load apparatus such as a computer and the like, there has only been a notion of improving efficiencies of the AC-to-DC converter or DC-to-AC inverter from the power saving standpoint of the main unit of an uninterruptible power supply apparatus of the continuous inverter power feeding type. As one of the approaches toward this, there has been proposed a power-saving type uninterruptible power supply apparatus in which the voltage at which the efficiency of the load apparatus is the highest and the power dissipation is the lowest is judged by varying the inverter voltage within the allowable input voltage range of the load apparatus, and the inverter output voltage is fixed at the judged voltage during operation.
However, in the conventional uninterruptible power supply apparatus of the continuous inverter power feeding type, almost no consideration has been made on the power saving of the uninterruptible power supply apparatus as a whole or, further, power saving of the total system including the connected load apparatus such as a computer and peripheral devices connected to the load apparatus such as a printer, display, and the like. For this reason, power has been wasted when viewed as a total system, presenting problems to be improved.
The present invention addresses these problems and aims at achieving power saving of an uninterruptible power supply apparatus of the continuous inverter power feeding type as a whole as well as power saving of the total system including the uninterruptible power supply apparatus and connected load apparatus such as a computer and peripheral devices attached to the load apparatus.
SUMMARY OF THE INVENTION
In order to achieve the above objective, the uninterrupitble power supply apparatus of the present invention provides an uninterruptible power supply apparatus of continuous inverter power feeding type comprising power supply input means for supplying commercial power to the apparatus, an AC-to-DC converter for converting an AC output of the power supply input means into a DC output, a built-in rechargeable battery, a charging circuit for charging the rechargeable battery, a DC-to-AC inverter for converting the DC output from the AC-to-DC converter or from the rechargeable battery, and a control circuit for performing various control of the apparatus, in which normal supply of power to a connected load apparatus in the event of a power failure can be maintained by supplying power from the rechargeable battery. The uninterruptible power supply apparatus further comprises a power supply circuit for transferring an AC output from the power supply input means to the control circuit, a switch “a” connected to the power supply input means, a switch “b” for changing the route of supplying power, and a load current detecting circuit for measuring the current flowing in the load apparatus so that the control circuit switches the switch “a” and switch “b” depending on the output from the load current detecting circuit.
In this configuration, when the value of a current detected by the load current detecting circuit has become equal to or lower than a predetermined value, the switch “a” is opened so that the power supply input means and the switch “b” are directly connected thereby suspending the supply of power to the uninterruptible power supply apparatus main circuit consisting of the AC-to-DC converter, the rechargeable battery, the charging circuit, and the DC-to-AC inverter. When the value of a current detected by the load current detecting circuit has become equal to or higher than a predetermined value, supply of power to the uninterruptible power supply apparatus main circuit can be resumed thereby allowing power saving of not only the apparatus alone
Kawabe Toshiyuki
Satoh Tatsuhiko
Matsushita Electric - Industrial Co., Ltd.
McDermott & Will & Emery
Tso Edward H.
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