Electric lamp and discharge devices: systems – Periodic switch in the supply circuit – Impedance or current regulator in the supply circuit
Patent
1999-02-17
2000-07-18
Philogene, Haissa
Electric lamp and discharge devices: systems
Periodic switch in the supply circuit
Impedance or current regulator in the supply circuit
315209R, 315244, 315207, 315DIG7, 363 47, 363 48, H05B 3702
Patent
active
060912073
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a circuit for operating a load, in particular an operating circuit for a low-pressure discharge lamp. It is primarily concerned with an operating circuit in which a rectified AC supply voltage is used to operate a half-bridge oscillator as frequency generator for lamp operation. Nevertheless, the invention is not restricted either to a lamp as load or to a half-bridge oscillator.
A significant criterion for practical application of such circuits is electromagnetic compatibility with regard to interference sent into the mains power supply and with regard to the harmonic content of the supply current drawn. A further development of such a circuit which is very effective in this respect consists in introducing at least one pump path between the load circuit side and the power supply side of the frequency generator structure. The pump paths generally contain capacitors as impedances--but not necessarily or necessarily exclusively. With regard to the prior art, reference is made to European Patents 0 244 644 B1, 0 253 224 B1 and 0 372 303 B1. Such pump paths serve to transfer charge within the circuit with the aim of improving the harmonic structure of the supply current consumption. With regard to electromagnetic compatibility, the IEC Standard 61000/3/2, Class C and Class D, in particular, is taken into consideration within the scope of this invention.
For the sake of clarity, the description is based on a relatively simple pump path structure which corresponds to FIG. 1 in EP 0 244 644 B1. The prior art cited additionally shows different pump path structures which are also more complicated. These and further conceivable variations as well are included in the subject-matter of the main claim.
SUMMARY OF THE INVENTION
Accordingly, the invention is based on a circuit for operating a load, in particular a low-pressure discharge lamp, having a frequency generator structure for supplying the load with AC current, and having a pump path for improving the electromagnetic compatibility of the circuit, which pump path connects the load circuit to a power supply side of the frequency generator structure.
The problem underlying the invention in this case is that of improving a circuit of the generic type in a simple manner in terms of its operational properties.
This problem is solved by the fact that on the power supply side of the frequency generator structure, in a DC region a pump supporting coil is connected, upstream of the connection point of the pump path, in series with the pump path and with a path of the power supply, which pump supporting coil is designed with the purpose that in each AC cycle the load is charged and essentially completely discharged.
The dependent claims relate to preferred embodiments.
The circuit shown in FIG. 1 of EP 0 244 644 B1 is thus supplemented according to the invention by the fact that a pump supporting coil is inserted on the rectified power supply side of the frequency generator structure, to be precise on the power supply side upstream of the connection point (M2) of the pump path. The formulations of the claims should be understood such that the pump supporting inductor is discharged to very small coil current values, in comparison with the coil current maximum, in each region of a supply voltage or current period, i.e. also in the region of the maxima. In other words, the current characteristic curve is a curve which repeatedly oscillates back to zero or to a very small value (at load circuit frequency), the amplitude being modulated with the time characteristic of the rectified (pulsating) power supply voltage. These current impressing or charging operations of the pump supporting inductor ensure optimum support of the pumping action of the pump path in favour of improved electromagnetic compatibility. In particular, this also yields the advantage of being able to dimension the pump path to be smaller with regard to its impedance and thus of being able to save costs.
The position of the pump supporting inducto
REFERENCES:
patent: 4075476 (1978-02-01), Pitel
patent: 4396866 (1983-08-01), Bay et al.
patent: 4563719 (1986-01-01), Nilssen
patent: 4808887 (1989-02-01), Fahnrich et al.
patent: 5008597 (1991-04-01), Zuchtriegel
patent: 5488269 (1996-01-01), El-Hamamsy et al.
patent: 5757143 (1998-05-01), Hernandez Martucci et al.
Bessone Carlo S.
Patent-Treuhand-Gesellschaft fuer elektrische Gluelampen mbH
Philogene Haissa
LandOfFree
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