The present invention relates to a method and a device for supplying a magnetic coupler.
Magnetic couplers (multi-interphase transformers) are used for example to connect a load to a polyphase supply source.
It is known to use polyphase supply sources which can generate N periodic supply currents or voltages which are offset angularly relative to one another, N being an integer which is greater than or equal to 4. The angular offsets between the supply currents or voltage used are uniformly distributed between 0 and 2π rad. Angular offset of 2π rad corresponds to a period of the current or voltage.
Known magnetic couplers comprise several pairs of windings, each pair being formed by a first and a second adjacent winding which are connected to one another magnetically by means of a core made of magnetic material, or a magnetic core. Different structures of known magnetic couplers are described in the following article:
“Modeling and Analysis of Multi-Interphase Transformers for Connecting Power Converters in Parallel”, IN GYU PARK and SEON IK KIM, Dept. of Control and Instrumentation Eng., Wonkwang University, Iksan, Chonbuk, 570-749 Korea, IEEE 1997.
The known methods for supplying these couplers consist in supplying the first winding of each pair with a supply current or voltage which is offset angularly by an angle α relative to the supply current or voltage of the second winding of the same pair.
In the known methods, the angle α is equal to 2π/N for each pair of windings.
The magnetic couplers thus supplied function correctly but are cumbersome. It is now desirable to reduce the size of these magnetic couplers.
The object of the invention is thus to propose a method for supplying a magnetic coupler which, for the same performance level, makes it possible to reduce the size of the magnetic coupler. The object of the invention is thus a method for supplying a magnetic coupler in which the absolute value of the angle α is greater than or equal to
for at least one pair of windings.
It has been observed that, for the same performance level, selecting the absolute value of the angle α as being greater than or equal to
for at least one pair of windings reduces the maximum magnetic flux which passes through the magnetic core which connects the windings of this pair. In fact, by imposing a value of this type for the absolute value of the angle α for at least one of the pairs of windings, the situation is approached in which the angular offset of the supply currents or voltages of this pair of windings is equal to π rad, which corresponds to an optimal reduction of the maximum magnetic flux which can be observed in the magnetic core which connects these two windings.
Since the maximum magnetic flux which passes through the cross-section of a magnetic core is reduced, it is possible to reduce the dimensions of this magnetic core, in such a way that the size of the coupler is also reduced.
In addition, because of the regular distribution of the angular offsets of the N supply currents or voltages, the current or voltage harmonics in the load supplied by means of this coupler are reduced.
The embodiments of this supply method can comprise one or more of the following characteristics:
for each pair of windings;
for each pair of windings;
pairs of windings, to π for two pairs of windings, and to −[(N/2)−1]·(2π/N) for the other pairs of windings.
These embodiments of the supply method also have the following advantages:
for, each pair of windings, makes it possible to reduce the size of the magnetic coupler;
for each pair of windings makes it possible to obtain optimal reduction of the size of the magnetic coupler; and
The object of the invention is also a device for supplying an electric dipole, this device comprising:
The embodiments of this device can comprise one or more of the following characteristics:
These embodiments of the supply device also have the following advantages:
The invention will be better understood by reading the following description, provided solely by way of example and with reference to the drawings, in which:
The dipole 4 is a resistor, for example.
The filter 6, is for example, a filter comprising only a filtering capacitor 12 which is connected parallel to the terminals of the dipole 4. In this case, the device 2 makes it possible to avoid the use of a filtering inductor.
The device 2 comprises a polyphase voltage source 16 and a magnetic coupler 18 in order to connect the source 16 to the dipole 4.
The source 16 is an N-phase source with N being an integer greater than or equal to 4. The source 16 thus supplies N voltages Vi, in which the value i is the number of the phase contained between 0 and N−1. By convention, the angular offset between the voltages V0 and Vi is equal to
The angular offsets between the voltages V0 to VN−1 are thus regularly distributed between 0 and 2π rad, as illustrated in
In
In this case, the amplitudes of the voltages V0 to VN−1 are all identical, since all the voltages V0 to VN−1 have the same periodic wave forms which are offset relative to one another by angular offset equal to
In
In order to simplify
The source 16 is, for example, a polyphase supply network, a polyphase voltage inverter or chopper, a controllable voltage rectifier formed by diodes and thyristors, or a primary stage of a “flyback” supply. These periodic voltages Vi are not necessarily sinusoidal, but are, for example, rectangular or triangular, and can comprise a continuous component.
In this embodiment, the coupler 18 comprises N monophase transformers Tr0 to TrN−1. Each transformer is formed by a primary winding e1i and an adjacent secondary winding e2i which are coupled magnetically to one another by means of a magnetic core ni, in which i is the same value as that previously used.
Each transformer forms a pair of windings which are connected to one another magnetically by means of the magnetic core.
In this case, the N transformers Tri are magnetically independent from one another.
In order to simplify the Fig., only three transformers Tr0, Tr1 and TrN−1 have been represented in
Each primary winding e1i is directly connected by one end to the source Si.
The secondary winding e2i of each transformer Tri is connected to the source Si−1 by means of the primary winding e1, i−1 of the transformer Tri−1. If the value i is equal to 0, the secondary winding e20 is connected to the source SN−1 by means of the winding e1,N−1 of the transformer TrN−1.
The end of each secondary winding which is not connected to one of the sources Si is directly connected to a mid-point 24, which itself is directly connected to the input 8 of the filter 6.
The mode of operation of the device 2 will now be described in relation to the method in
Initially, during a step 30, the angular offset of each source S0 to SN−1 is regulated in such a way that the supply voltage of the primary winding e1i of each transformer is offset by an angle α, the absolute value of which is greater than
relative to the supply voltage of the secondary winding e2i of the same transformer. In this case, the angular offset of the sources S0 to SN−1 is regulated in such a way that the absolute value of the angle α is contained between
for the windings of each transformer.
More specifically, the angular offset of the sources Si is regulated in such a way that the absolute value of the angular offset α between the supply voltages of the windings e1i and e2i is equal to:
When N is even, the angle α is equal to [(N/2)−1]·(2π/N) for the
first transformers, π for the
and the Nth transformer, and −[(N/2)−1]·(2π/N) for the other transformers.
When N is a multiple of 4, two formulae for calculating the angle α are thus applicable, since N is then also even.
Subsequently, during a step 34, the windings of each transformer are supplied by means of supply voltages which have an angular offset relative to one another by an angle α, as determined during the step 30.
Selection of this type of the angle α reduces as far as possible the maximum magnetic flux which passes through the cross-section of the magnetic cores n0 to nN−1, in such a way that this cross-section can be reduced, which reduces the global size of the coupler 18. The maximum magnetic flux through the cross-section of the magnetic core is reduced, since increasing the phase displacement between the primary and secondary windings signifies a move away from the situation in which, at a given moment, the maximum magnetic fields created by these two windings are combined inside the magnetic core.
The device 40 comprises the supply source 16 and a magnetic coupler 42. The coupler 42 differs from the coupler 18 only in the fact that the primary and secondary windings of each transformer are connected directly to respective voltage sources Si. The supply method is identical to that described in relation to
In
The device 50 comprises the supply source 16 connected to the dipole 4 by means of a magnetic coupler 54.
In the coupler 54, the mid-point 24 is connected to a reference potential M1, and no longer to the input 8 of the filter 6.
In this embodiment, each transformer Tri comprises in addition to the pair of windings e1i and e2i a pair of windings e3i and e4i. The windings e3i and e4i are coupled magnetically to the windings e1i and e2i by means of the magnetic core ni. The pair of windings e3i and e4i is electrically isolated from the windings e1i and e2i.
One end of the winding e3i is connected by means of a diode di to a common point 58. The cathode of the diode di faces the common point 58.
The common point 58 is directly connected to the input 8 of the filter 6.
The other end of the winding e3i is directly connected to an end of the winding e4,i+1 of the following transformer Tri+1. The end which is not connected to the winding e3i of the winding e4,i+1 is connected to a reference potential M2 which is isolated electrically from the potential M1.
The end which is not connected to the common point 58 of the winding e3,N−1 is directly connected to an end of the winding e40.
The method for supplying the coupler 54 is the same as that described with reference to
In this case, the coupler 60 comprises a monolithic magnetic core 62 with a plurality of horizontal branches B0 to BN−1. In
In this case, each of the legs 64 and 66 forms a loop or a circuit which is closed on itself, and connects all the branches Bi.
A conductor forms a winding ei around each horizontal branch Bi. An end of each winding ei is connected directly to a common point 68, and the common point 68 is connected, for example by means of the filter 6, to the dipole 4.
The other end of each winding ei is connected to a respective source Si of the supply source 16.
In this case, the adjacent windings ei, ei+1 which are supported by two successive horizontal branches Bi, Bi+1 form a pair of windings which are connected to one another magnetically by means of the core 62. However, unlike the preceding embodiment, in this case a single winding can belong to two different pairs of adjacent windings. This situation is illustrated in
The method for supplying the coupler 60 is identical to that described with reference to
In
The coupler 70 differs from the coupler 60 substantially in that the vertical legs 64 and 66 are replaced by vertical uprights 74 and 76 respectively. Thus, the uprights 74 and 76 connect the ends of the branches B0 to BN−1 magnetically. However, in this embodiment, the uprights 74 and 76 do not form a loop or circle which is closed on itself and connects all the branches Bi.
The other characteristics represented in
The method for supplying the coupler 70 is identical to that described with reference to
Many other embodiments of the preceding supply devices and of the supply method are possible. For example, the monophase voltage sources of the source 16 can be replaced by monophase current sources which can be regulated. In this case, the supply method is identical to that in
In the embodiment in
Preferably, the source 16 is formed by N monophase sources, the angular offset of which is not adjustable. In these conditions, the step 30 of the method in
Number | Date | Country | Kind |
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05 07136 | Jul 2005 | FR | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/FR2006/001579 | 7/4/2006 | WO | 00 | 5/14/2008 |
Publishing Document | Publishing Date | Country | Kind |
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WO2007/006902 | 1/18/2007 | WO | A |
Number | Name | Date | Kind |
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4931919 | Nguyen et al. | Jun 1990 | A |
5337227 | Stacey et al. | Aug 1994 | A |
5703767 | Stacey et al. | Dec 1997 | A |
6650557 | Ferens et al. | Nov 2003 | B2 |
7026727 | Readio et al. | Apr 2006 | B2 |
Number | Date | Country | |
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20080218150 A1 | Sep 2008 | US |