Electricity: power supply or regulation systems – External or operator controlled – Phase controlled switching using electronic tube or a three...
Reexamination Certificate
2000-03-02
2001-08-28
Wong, Peter S. (Department: 2838)
Electricity: power supply or regulation systems
External or operator controlled
Phase controlled switching using electronic tube or a three...
C323S908000
Reexamination Certificate
active
06281669
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a circuit arrangement and method for limiting current for consumers of alternating current.
A number of consumers, for instance assemblies, assembly units, modems, personal computers, printers, and monitors, and so on, are connected to an inverter at the output side. These consumers are mostly dimensioned for operation at a low-impedance network, the result of which is high inrush currents. A consumer's inrush current often amounts to a multiple of its nominal current. This high inrush current results in a voltage dip at the output of the inverter. In turn, a voltage dip gives rise to failures in the other consumers that are connected to the inverter. In order to avoid a high current flow through a consumer that is connected to an inverter, these often have current limiting devices that consist of a choke, which are arranged at the inverter at the output side.
The disclosure document German Patent Application No. 35 02 195 teaches a limiting circuit for alternating current. In this current limiting circuit, a variable resistance is connected to the terminals of a bridge rectifier circuit for the purpose of limiting the current. This variable resistance consists of a parallel circuit composed of a first series circuit, which is formed by two resistors, and a second series circuit, which is formed by the collector-emitter system of a transistor and an additional resistor. The transistor is controlled via the voltage splitter of the first series circuit and an additional transistor.
The U.S. Pat. No. 4,396,882 teaches a circuit arrangement of an inrush current limiter.
SUMMARY OF THE INVENTION
It is an object of the present invention to set forth a circuit arrangement and a method for limiting current for an alternating current consumer.
This object is achieved in accordance with the invention in a circuit arrangement for limiting current, particularly for limiting an inrush current, for at least one consumer connected to an inverter, said circuit arrangement comprising: a rectifier unit and a current limiting unit. The rectifier unit arranged in series with said consumer, said rectifier unit having: a first input-side terminal, a second input-side terminal, a first output-side terminal, and a second output-side terminal, said rectifier unit for rectifying an alternating current delivered by said inverter to said consumer and flowing through said first and second input-side terminals. The current limiting unit having: a first input connected to said first output-side terminal of said rectifying unit; a second input connected to said second output-side terminal of said rectifying circuit; a reference voltage source having an input connected to said first input of said current limiting unit and an output; a series circuit connected across said first and second inputs of said current limiting unit, said series circuit including a measuring shunt connected in series with a controlled system of a first switching element, said measuring shunt having a first input connected to said first input of said current limiting unit and a second input connected to an input of said controlled system of said first switching element, said controlled system of said first switching element having an output connected to said second input of said current limiting unit, said first switching element having a control input; and a current regulator having a first input connected to said input of said controlled system of said first switching element, a second input connected to said output of said reference voltage source, and an output connected to said control input of said first switching element.
This object is also achieved in accordance with the invention in a method for limiting a current, particularly for limiting an inrush current, for at least one consumer that is connected to an alternating current voltage source, said method comprising the steps of: rectifying an alternating current delivered by said alternating current voltage source to said consumer; applying said rectified alternating current to an input of a current limiting unit; and limiting said alternating current flowing through said consumer to a predetermined value with said current limiting unit when a permissible current value is exceeded.
These and other features of the invention(s) will become clearer with reference to the following detailed description of the presently preferred embodiments and accompanied drawings.
REFERENCES:
patent: 4396882 (1983-08-01), Kellenbenz
patent: 32 41 668 C2 (1984-05-01), None
patent: 35 02 195 A1 (1986-07-01), None
patent: 35 02 195 (1986-07-01), None
patent: 39 32 776 A1 (1991-04-01), None
Laxton Gary L.
Schiff & Hardin & Waite
Siemens Aktiengesellschaft
Wong Peter S.
LandOfFree
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