DE112023000757T5 - Integrated magnetic device - Google Patents

Abstract

The present invention relates to an integrated magnetic device (10) comprising at least three coils (11, 12, 13), each formed by at least one winding (111, 112, 113, 111', 112', 113') around a ferrite rod (121, 122, 123), the coils (11, 12, 13) being arranged to form an equilateral triangle, the device comprising a central element (20) made of ferrite arranged between the three coils (11, 12, 13).

Description

The present invention relates to an integrated magnetic device and in particular to an integrated magnetic device, also called transformer, for a three-phase resonant converter.

The invention finds particular application in the field of high-voltage systems with voltages of more than 60 V, e.g. more than 300 V, e.g. 800 V.

Three-phase resonant converters are electronic circuits that sometimes contain transformers.

Due to their high efficiency, wide voltage range, low current ripple and high power, they are often used in battery charging applications, for example.

The magnetic components, such as the transformers, which are integrated into the converters, are therefore of great importance for the performance of the converters, as they define their strength.

Three-phase transformers are already known, comprising three coils formed by a winding around a ferrite rod or core and arranged in the same plane in an aluminum casing. This type of transformer has several disadvantages that limit its performance. These disadvantages include a large drop in inductance when the transformer is arranged in the aluminum casing, unbalanced currents, an uneven resonance frequency and high losses in the aluminum casing.

There are solutions that try to improve these transformers.

The patent US10186974B2 describes a transformer with two additional ferrite legs placed on one side and the other side of the end coils. By adding these two ferrites, the magnetic volume of the transformer is increased, and the losses in the housing remain high.

The patent CN212010657U describes a transformer with additional magnetic plates surrounding the coils. Adding these plates increases the magnetic volume of the transformer and unbalanced currents still exist.

The object of the present invention is therefore to eliminate one or more disadvantages of the prior art devices by proposing an integrated magnetic device designed to limit the drop in the value of the inductances in the aluminum housing, unbalanced currents and an uneven resonance frequency, as well as high losses in the aluminum housing. This integrated magnetic device forms, for example, a three-phase transformer.

To this end, the present invention proposes an integrated magnetic device comprising at least three coils, each formed by at least one winding around a ferrite rod, the coils being arranged to form an equilateral triangle, the device comprising a central element made of ferrite arranged between the three coils.

This single-leg center element allows for continuous flow with low ferrite losses.

It is possible that this central element with one leg does not have a winding arranged around it.

Each bar can have, in a plane perpendicular to its longitudinal axis, a cross-section that has the same shape as the other bars and is different from that of the central element in that plane. For example, the cross-section of the bars is circular and that of the central element is not circular. For example, in the plane perpendicular to their longitudinal axis, the bars have exactly the same shape. In this case, all the bars have a cross-section in the shape of a circle with the same radius.

According to one embodiment of the invention, the central element has a height H which corresponds to the height h of a coil.

According to one embodiment of the invention, the three bars each have at least one air gap.

According to one embodiment of the invention, the ferrite element has no air gap.

Since the center section has no air gap, the phases are decoupled, meaning that the flux generated by one phase is not coupled by the other phases.

According to one embodiment of the invention, the ferrite element has a columnar central portion from which three legs extend.

According to an embodiment of the invention, the shape of the legs is adapted to fit between the coils. In a plane perpendicular to the longitudinal axes of the rods, each rod can have a dimension which initially decreases in a direction away from the central portion and then increases towards the end of that leg.

According to one embodiment of the invention, the end of each leg is flat.

According to an embodiment of the invention, a second triangular ferrite element is arranged on top of the central ferrite element. In a variant, a portion of each bar may be formed integrally with the corresponding portion of the other bars, and this part may form the upper portion of the integrated magnetic device.

According to an embodiment of the invention, a third triangular ferrite element is arranged on the underside of the central ferrite element. In a variant, the central element and a portion of each rod can be formed in one piece and form the lower portion of the integrated magnetic device.

The invention also relates to the use of the device according to the invention in a motor vehicle, in particular for supplying power to a unit for storing electrical energy in a vehicle. The unit for storing electrical energy is, for example, a battery, which can have a nominal voltage corresponding to the values mentioned above.

• - 1 die Leistungsauslegung eines CLLLC-Wandlers,
• - 2 eine schematische Darstellung einer Draufsicht der integrierten magnetischen Vorrichtung gemäß einer Ausführungsform der Erfindung,
• - 3 eine schematische Darstellung einer Draufsicht des Mittelelements der integrierten magnetischen Vorrichtung gemäß einer Ausführungsform der Erfindung,
• - 4 eine Schnittdarstellung einer erfindungsgemäßen Vorrichtung mit einem Aluminiumgehäuse,
• - 5 ein Schaubild des Magnetkreises der Vorrichtung gemäß einer Ausführungsform der Erfindung.

Further objects, features and advantages will be better understood and made clearer by reading the description given below with reference to the accompanying exemplary figures. In the figures:

• - 1 the performance design of a CLLLC converter,
• - 2 a schematic representation of a top view of the integrated magnetic device according to an embodiment of the invention,
• - 3 a schematic representation of a plan view of the central element of the integrated magnetic device according to an embodiment of the invention,
• - 4 a sectional view of a device according to the invention with an aluminum housing,
• - 5 a diagram of the magnetic circuit of the device according to an embodiment of the invention.

The invention relates to an integrated magnetic device.

According to one embodiment of the invention, this magnetic device is a transformer for a three-phase resonant voltage converter. The three-phase resonant voltage converter is an LLC, CLLC, CLLLC, LC or CLC three-phase resonant voltage converter. The power design of a CLLLC converter is in 1 shown.

2 illustrates an integrated magnetic device 10 according to the invention.

The magnetic device 10 comprises at least three coils 11, 12, 13, each formed of at least one primary winding 111, 112, 113 and one secondary winding 111', 112', 113' around a rod or core 121, 122, 123 made of ferrite.

According to one embodiment of the invention, these three bars 121, 122, 123 each have at least one air gap.

The magnetic device according to the invention has a triangular geometry. This means that the three coils are arranged to form an equilateral triangle. More precisely, each coil is arranged at the level of the edge of a triangle.

Because the arrangement corresponds to an equilateral triangle, it is possible to ensure a balance between the electrical parameters such as the inductances of each coil and to reduce the magnetic volume.

In the context of the invention, the device comprises a central element 20 made of ferrite, which is arranged between the three coils 11, 12, 13, as in 3 can be seen in detail. This middle element 20 has no air gap.

The central element 20 without an air gap enables decoupling of the phases and compensation of inductance losses. This element 20 also makes it possible to concentrate the magnetic leakage flux inside the transformer.

According to an embodiment of the invention, the element 20 has a height H which corresponds to the height h of a coil 11, 12, 13. The height h of a coil is defined by the distance between its two ends.

According to one embodiment of the invention, the ferrite element 20 has a columnar central portion 24 from which three legs 21, 22, 23 extend.

The shape of the legs is adapted to fit between the coils. This means that each leg has two rounded sides whose contours follow the shape of a coil. The sides of two adjacent legs form a curve 220, 230, 240 that follows the contour of a coil 11, 12, 13.

This center element 20 with one leg enables a continuous flow with low ferrite losses.

According to one embodiment of the invention, the end 211, 212, 213 of each leg 11, 12, 13 is flat. This means that each end forms a flat plane in the height direction H.

According to an embodiment of the invention, a second triangular ferrite element 40 is arranged on the upper side of the ferrite element 20, i.e. on the side which lies in the plane of the upper side of the coils.

According to an embodiment of the invention, a third triangular ferrite element 50 is arranged on the lower side of the ferrite element 20, i.e. on the side which lies in the plane of the lower side of the coils.

The term upper is defined as the opposite of the term lower, with each term representing one of the two ends of the coils.

According to one embodiment of the invention, the edges of the second element 40 and the third element 50 are sharp or rounded.

According to one embodiment of the invention, the magnetic device 10 is arranged in an aluminum housing 60 which is 4 shown.

Since the central element 20 has no air gap, the phases are decoupled, which means that the flux generated by one phase is not coupled through the other phases. Under this assumption, the device 10 can be equipped with the magnetic circuit of 5 be analyzed.

In this circuit, Rc is the magnetic material, e.g. ferrite, the magnetic resistance Rg is the magnetic resistance of the air gap, Rw is the magnetic resistance of the coil window, Np1 is the number of turns in the primary phase 1, Ns1 is the number of turns in the secondary phase 1, Ip1 is the primary current in the phase 1, and Is1 is the secondary current in the phase 1.

$$L_{lkg-s}=\frac{N_{s1}^2}{R_w}$$

$$L_m=\frac{N_{p1}^2}{R_g}$$

Assuming that the magnetic resistance of the magnetic material is negligible, equivalent magnetic circuits can be derived, and it is possible to calculate the magnetic inductance, the inductance loss on the primary side and the inductance loss on the secondary side according to the following formulas: $$L_{lkG-p}=\frac{N_{p1}^2}{R_w}$$

$$L_{lkG-s}=\frac{N_{s1}^2}{R_w}$$

$$L_m=\frac{N_{p1}^2}{R_G}$$

The following results are obtained for a device according to the invention: [Table 1] Np/Ns=12/10 Llkg-p1 (µH) Llkg-p2 (µH) Llkg-p3 (µH) Inductance of the magnetic device without aluminum housing 4.64 4.60 4.64 Inductance of the magnetic device in an aluminum housing 4.44 4.51 4.50 inductance loss % 4.3 1.9 2.8

These results show that with an integrated magnetic device according to the invention it is possible to obtain inductances with values that do not drop when using the aluminum housing. In fact, the inductance drop inside the aluminum housing is always lower than 5%.

With such a device it can also be observed that the magnetic flux density in the central element 20 has a nearly continuous value and consequently very low hysteresis losses.

According to a variant of the invention, the angles of the central element 20 are increased in order to increase the inductance loss.

According to a further variant of the invention, the device comprises a fourth coil to enable a low-voltage outlet, for example for use in a component for supplying power to a unit for storing electrical energy of a vehicle, also called "OBC/DCDC".

The invention also relates to a three-phase resonant converter with a magnetic device according to the invention.

The invention also relates to the use of the three-phase resonant converter according to the invention in a combustion engine, electric or hybrid vehicle.

The scope of the present invention is not limited to the details given above, and is capable of embodiment in many other specific forms without departing from the spirit and scope of the invention. Accordingly, the present embodiments are intended to be are for illustrative purposes only and are subject to change without departing from the scope defined by the claims.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• US10186974B2 [0008]
• CN212010657U [0009]

Claims (10)

Transformer (10) with at least three coils (11, 12, 13), each formed from at least one winding (111, 112, 113, 111', 112', 113') around a ferrite rod (121, 122, 123), the coils (11, 12, 13) being arranged to form an equilateral triangle, characterized in that it has a central element (20) made of ferrite which is arranged between the three coils (11, 12, 13), the three rods (121, 122, 123) each have at least one air gap and the central element (20) made of ferrite has no air gap. transformer to claim 1 , in which the central element (20) has a height H which corresponds to the height h of a coil (11, 12, 13). transformer to claim 1 or 2 , in which the central element (20) has no winding arranged around it. Transformer according to one of the preceding claims, in which each bar (121, 122, 123) has, in a plane perpendicular to its longitudinal axis, a cross-section which has the same shape as that of the other bars and which differs from that of the central element (20) in that plane. Transformer (10) according to one of the Claims 1 until 4 , in which the ferrite element (20) has a columnar central section (24) from which three legs (21, 22, 23) extend. Transformer (10) after claim 5 , in which the shape of the legs (21, 22, 23) is adapted to fit between the coils (11, 12, 13). Transformer (10) according to one of the Claims 5 or 6 , in which the end (211, 212, 213) of each leg (11, 12, 13) is flat. Transformer (10) according to one of the Claims 1 until 7 , in which a second, triangular element (40) made of ferrite is arranged on top of the central element (20) made of ferrite. Transformer (10) according to one of the Claims 1 until 8 , in which a third, triangular element (50) made of ferrite is arranged on the underside of the element (20). Use of the transformer (10) according to one of the Claims 1 until 9 in a motor vehicle for supplying power to a unit for storing electrical energy.

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