Electric power conversion systems – Current conversion – Having plural converters for single conversion
Patent
1996-06-24
1998-05-12
Berhane, Adolf
Electric power conversion systems
Current conversion
Having plural converters for single conversion
363 17, 363134, 315279, H02M 3335
Patent
active
057515662
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a lighting system which includes a constant-current regulator. The system of the present invention is particularly applicable to airfield lighting.
BACKGROUND INFORMATION
Constant-current regulators are required in widely different fields of technology. Particularly when lighting systems have to be operated at a defined and constant brightness, such as in the case of airfield lighting systems but also in lighting systems for theaters and television studios, stringent requirements are placed on a current intensity or voltage which are constant with respect to time and with comparatively high electrical powers. However, the same also applies in principle to metallurgy, for example, when operating furnaces which are operated at high power. A regulator which is described in the French Patent Application No. 14 69 154 can be used, for example, for such applications.
Particularly in the case of systems for airfield lighting, groups of lighting elements are in each case operated at a constant current intensity via series transformers. In such a case, the individual lighting elements are connected in series via "lamp transformers". If a lighting element fails, the associated lamp transformer is controlled to saturation.
Conventional constant-current regulators for such applications operate on the basis of the required electrical powers with thyristor circuits. U.S. Pat. No. 3,743,921 describes a system having a large number of lighting elements in a secondary circuit which are intended to be operated at the same brightness. A device which monitors and adjusts the triggering point of the individual thyristors is required for the regulator circuit using thyristors. The known principle of phase-gating control is used, and the primary of the series transformer is supplied with the required power via the thyristor circuit. The required actual value
ominal value comparison is in each case performed using an ammeter on the secondary side and feedback to the primary, with a nominal-value transmitter for the purpose of activation of the regulator.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an improved system for lighting an airfield. The object is achieved according to the present invention, in that a power which is applied to the basic voltage is produced by means of a separate winding of the step-up transformer or of a separate transformer having a primary winding and a secondary winding, and in that a switch-mode regulator module regulates only the power which is applied to the basic voltage. Thus, the switch-mode regulator module drives the primary winding element of the step-up transformer or of the separate transformer having a primary and secondary winding. The primary windings are driven using a transistor circuit.
The system according to the present invention includes a constant-current regulator having a step-up transformer with units for nominal-value presetting and actual value detection and for actual value
ominal value comparison, the primary of the step-up transformer being assigned the unit for selection of a basic voltage.
According to the present invention, the means for actual value
ominal value comparison are preferably digital switching means. The switch-mode regulator module can now advantageously drive the primary winding of the step-up transformer directly using a transistor circuit since only comparatively low powers, e.g., 5 to 20% of the total power, are regulated.
With the present invention, it is particularly advantageous that virtually no harmonics are fed back into the power supply. In contrast to known systems, no inductor is absolutely essential for the series transformer. The charging of the cable capacitance is carried out by means of a sinusoidal current so that the previously observed resonance phenomena in the current no longer occur.
The constant-current regulator according to the present invention is preferably designed so that the regulator output stage is designed, e.g., for about only
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patent: 3440519 (1969-04-01), Macemon
patent: 3743921 (1973-07-01), Legg et al.
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patent: 4733158 (1988-03-01), Marchione et al.
patent: 4853832 (1989-08-01), Stuart
patent: 4965508 (1990-10-01), Soan
patent: 5189599 (1993-02-01), Messman
patent: 5610452 (1997-03-01), Shimmer et al.
Berhane Adolf
Siemens Aktiengesellschaft
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