Electrical transmission or interconnection systems – Anti-induction or coupling to other systems – Magnetic or electrostatic field control
Patent
1997-03-12
2000-01-11
Paladini, Albert W.
Electrical transmission or interconnection systems
Anti-induction or coupling to other systems
Magnetic or electrostatic field control
307 89, 332 12, 361143, H05K 900
Patent
active
060139579
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to arrangements for reducing the electromagnetic field emitted by electronic power equipment.
One such item of electronic power equipment, an AC to DC converter, for example, comprises electronic switches generating an electromagnetic field which, because of the powers involved, is very intense and requires arrangements for reducing propagation thereof outside the equipment. In this respect, known solutions rely on shielding and filtering.
When such solutions are applied to equipment of relatively low power and small volume, they are effective for reasonable cost. Nevertheless, with the increase in power of electronic power equipment, and thus with the increasing volume thereof, such arrangements are becoming unacceptable, not only in terms of cost, but also in terms of volume and of weight, while the increase in switching speeds further increass the levels of emitted radiation.
An object of the present invention is thus to provide arrangements seeking to reduce the electromagnetic field emitted by electronic power equipment effectively and at low cost, with a corresponding reduction in requirements concerning filtering and shielding when they remain necessary.
The arrangements of the invention seeking to reduce the electromagnetic field emitted by electronic power equipment essentially comprise an antenna element placed in the vicinity of a radiating conductor of the equipment so as to absorb the electromagnetic energy reaching it by coupling with the radiating conductor, thereby reducing the energy that is radiated into the space surrounding both of them.
In one embodiment, when the radiating conductor is a monopole (radiating a field that is essentially electric), the antenna element is also a monopole constituted by a conductor of the same length and the same shape as the radiating conductor, and connected to ground at one of its ends.
In another embodiment, when the radiating conductor is a loop (radiating a field that is essentially magnetic), the antenna element is also a loop formed by a conductor having the same path, length, and area as the radiating conductor.
The various objects and characteristics of the invention appear more clearly in the light of the following description of an embodiment of the invention, given with reference to the accompanying figures, in which:
FIG. 1 is a circuit diagram by way of example of a DC chopper that can be used in electronic power equipment;
FIG. 2 shows the voltage and the current in the switching transistor T of the FIG. 1 circuit;
FIG. 3 shows the same circuit of FIG. 1, but it also indicates the monopoles that generate an electric field;
FIG. 4 is the same circuit again, but with indications showing the loops that generate a magnetic field;
FIG. 5 is an illustration of arrangements in a first embodiment of the invention for reducing the electromagnetic field emitted by a radiating monopole;
FIG. 6 is an illustration of a second embodiment of arrangements of the invention for reducing the electromagnetic field emitted by a radiating loop;
FIG. 7 is a graph showing experimental results for the arrangements of FIG. 5; and
FIG. 8 is a graph showing experimental results for the arrangements of FIG. 6.
The present invention is applied to reducing the electromagnetic field emitted by electronic power equipment.
An example of such electronic power equipment is an AC to DC converter, including electronic switches that generate an electromagnetic field. One example of such an electronic switch is shown in FIG. 1. This figure is a schematic of a DC chopper comprising a DC source E (e.g. a rectifier), a filter capacitor C, a switching transistor T, a free-wheel diode D, and a load represented by a current generator Io.
FIG. 2 is a diagram showing the voltage Vk across the terminals of the switching transistor T and the current Ik flowing through it during each period that the switching transistor T is ON and is OFF. It can be seen that the voltage Vk across the terminals drops suddenly to zero while the current Io in the load is establis
REFERENCES:
patent: 1896819 (1933-02-01), Hyde
patent: 4187447 (1980-02-01), Stout et al.
patent: 5541609 (1996-07-01), Stutzman et al.
patent: 5598079 (1997-01-01), Robert
Gonzalez Juan
Puzo Antoine
Alcatel
Paladini Albert W.
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