DE212015000259U1 - Transformer with integrated inductor - Google Patents

Abstract

Integrated inductor transformer comprising: - a first magnetic body (1) and a second magnetic body (2) which are independent of one another, wherein the first magnetic body (1) and the second magnetic body (2) each comprise a plate (1a, 2a) from which a core (1b, 2b) with a cylindrical or polygonal cross-section is derived; and primary and secondary windings (5) arranged so as to surround a tubular core (7b) of a coil (7) of electrical insulating material, the cores (1b, 2b) being located in the tubular cavity of the coil (7) are arranged and the ends of the cores (1b, 2b) face each other with a predetermined distance, characterized in that - the primary and secondary windings (5) are each formed by a turn comprising a plurality of threads which are individually interwoven, with three insulation layers; and - one of the bases (7a) of the coil (7) has extensions which, together with end edges, are formed with a series of openings adapted to receive inserted flat contact pins (3) or plugs (4) End portions are bent against the extensions, so that coplanar flat mounting and terminals are provided.

Description

The disclosure generally relates to the field of power transformers. In particular, the disclosure relates to a transformer of a very compact size intended for fast charging of batteries, the transformer incorporating a resonant inductor. The transformer has magnetic covers and windings wound around a tubular core of a coil and is intended for surface mount (SMD).

State of the art

In order to carry out the charging of high voltage batteries (250-450 V), which is used, for example, in hybrid or electric vehicles to power the engine and the entirety of the vehicle's electrical and electronic devices, different systems connected to the grid can be used (50/60 Hz) or connected to a power source (AC or DC).

For the charging of said batteries, there are mainly two separate power electronics topologies, the ZVS and the Full Bridge Resonant LLC. Both topologies allow the development of a high-efficiency converter (> 90%).

Resonant LLC circuits are preferred because, in addition, they reduce the problems derived from electromagnetic interference (EMI) by means of a soft switching, and therefore their use is greater than that of the ZVS systems. The switching frequency range in the resonant LLC circuits is usually 70-350 kHz. In addition, this type of circuit, by using a power of 3.5 kW, allows a full charge of the batteries overnight (about eight hours). It is also possible to use higher powers (7 kW, 22 kW, 43 kW) to allow faster charging of the batteries.

An LLC topology generally requires two inductors (or chokes), a series inductor, L _R , and a parallel inductor, L _P , associated with a capacitor C _R to form a resonant tank ( 1 ). In many cases, and to reduce the use of magnetic devices associated with only two components, the aforementioned inductor L _{P is} preferably integrated within the transformer itself.

A transformer in which the mentioned inductor L _{P is} integrated is known, for example, from Patent ES-B1-2393695 known. In contrast to the transformer proposed here, in the cited Spanish patent, the windings used are planar windings which occupy a smaller volume while retaining the transformer structure and not windings which are wound around a tubular core of a coil and not of a material high mechanical and thermal characteristics are formed.

From the utility model CN 201829300 U For example, a transformer is known which resembles the latter but with a different structure, with contact pins for mounting on a circuit.

On the other hand, in the current state of the art, no transformer is known which integrates an inductor with windings wound around a coil and made by a design and a material with high mechanical and thermal characteristics in which one of the bases of the coil additionally has openings with openings for the introduction of terminals, with a sufficient cross-section, to allow the transmission of high currents and at the same time to provide a mechanical holding force, wherein such terminals occupy an education that allow automatic surface mounting of the transformer and a connection thereof.

Description of the invention

In order to overcome the limitations of the prior art, there is provided a type of transformer which is particularly suitable for charging batteries, in which the voltage level of the rectified current adapts to the voltage of the battery, and in which it is insulated against dangerous voltages is provided to prevent damage to an end user.

The transformer also has special terminals (contact pins / plugs) designed for surface mount technology (SMD) to allow the proposed transformer to be automatically welded directly to a metal substrate (IMS, IMS) and thereby the Integration of higher energy densities and better mechanical and thermal performances.

The proposed integrated inductor transformer, as well as the prior art transformers, comprises two magnetic bodies which are independent of each other, each of which comprises a plate of which a cylindrical or polygonal core is formed Cross-section derives; and primary and secondary windings arranged to surround a tubular core of a coil of electrical insulating material in which the cores of cylindrical or polygonal cross-section are disposed in the tubular cavity of the coil so that their ends are at a predetermined pitch stand opposite.

Typically, the primary and secondary windings are each formed of a turn comprising a plurality of filaments individually interwoven with three insulation layers, and one of the bases of the coil has extensions which, together with end edges, are formed with a series of apertures which are adapted to receive inserted flat contact pins or plugs with their end portions bent against the extensions to provide coplanar flat mounting and connection terminals.

The openings of the base of the coil preferably have two different dimensions. The larger size openings are primarily used to accommodate the fishing pins for the primary and secondary windings, while the smaller size holes accommodate the connectors for connecting the primary and secondary windings to a thermal sensor (eg, an NTC sensor). In one embodiment, the flat contact pins and the plugs are of a tin-plated phosphor bronze alloy.

The plates forming the magnetic bodies may also have an "E" shaped configuration, with one leg being derived from each end of the plate. The legs are dimensioned such that when the magnetic bodies are oppositely arranged with their cores, the ends of said cores remain separated at this predetermined distance, since the legs of the two plates remain opposite the ends thereof.

The three insulating layers may comprise a polyamide adhesive tape surrounding the interlaced filaments. Preferably, the filaments of the primary and secondary windings have a thickness of about 0.05 to 0.2 millimeters (mm).

Preferably, said magnetic bodies are of a manganese-zinc ferrite material and the coil is of a plastic material selected from PET, LCP, phenolic resin or a flame retardant material.

By using a ferrite magnetic body with few losses and high heat resistance, as well as using thin interlaced conductive filaments arranged parallel to the primary and secondary windings, the proposed transformer makes it possible to increase the losses with respect to the input voltage range and allows actual consumption according to the state of charge of the battery.

In addition, the use of said isolated braided conductive filaments allows the requirement of throw distance and creep according to safety standards ( EN 60950, EN 61558-1-2-17 , etc.).

The use of a thermal sensor, which may be integrated within the primary and secondary windings, also allows the heating of the transformer to be controlled. The detection of this heating is analyzed by means of electronics which is able to reduce the energy during the charging of the battery when the transformer heats up too much, thus preventing any overheating.

The proposed transformer allows operation at a power density of 20-25 W / cm ³ and a current density of up to 6-7.5 A / mm ² under suitable cooling conditions.

Description of exemplary embodiments

The foregoing and other advantages and features will be better understood by reference to the following detailed description of an embodiment with reference to figures of a drawing, which are to be considered in an illustrative and non-restrictive manner, wherein:

1 an example of a topology of a resonant LLC converter is;

2 Figure 3 is a perspective view of the proposed transformer according to an exemplary embodiment;

3 an exploded perspective view of each of the parts of the transformer 2 is;

4 an example of the mounting method of the terminals shows; and

5 Figure 4 is a perspective view of the transformer according to an embodiment in which an air gap is used to integrate the L _P value.

2 shows an embodiment of the proposed transformer. In particular, the training shows 2 a transformer suitable for surface mount technology (SMD) which is used for the conversion of energy in the switching mode for power values in the range of 3 to 7 kW. As can be seen, the transformer has a low profile (less than 40 mm height), which results in being a very robust solution with small dimensions, being a suitable device for associating with lower level electronic boards and for their direct mounting on a metallic substrate IMS (Isolated Metal Substrate).

In 2 One can clearly see that in the proposed transformer one of the bases of the coil 7 Renewals 7a which, together with end edges, are formed with a series of openings which are adapted to inserted clamps, such as flat contact pins 3 or plug 4 with their end portions bent against the extensions (90 degrees cranked) to provide coplanar flat mounting and termination terminals.

3 shows the mechanical exploded view of the preceding 2 , In 3 It can be seen that the proposed transformer two magnetic body, a first magnetic body 1 and a second magnetic body 2 , which are independent of each other, these "E" -shaped magnetic bodies of a plate 1a . 2a are formed, each of which is a core 1b . 2 B with a cylindrical cross-section (without being limiting, since the mentioned core may have a polygonal cross-section). From each end of the magnetic body 1 . 2 out a leg is derived 1c . 2c which is dimensioned such that when the magnetic body with their cores 1b . 2 B placed opposite, the ends of said cores 1b . 2 B stay separated with this predetermined distance.

The magnetic bodies are preferred 1 . 2 from a manganese-zinc ferrite material (MnZn). This ferrite material used has a structure exhibiting low iron loss and a flat temperature response to overheat the magnetic body 1 . 2 to prevent. Each magnet body has a particular shape, being larger but with a lower height than other conventional ferrite bodies, such as those in the international art Standard IEC-62317-13 be mentioned is. The use of this type of ferrites allows a power transfer of up to 4 kW in the frequency range of 70-350 kHz, which is reserved for LLC switching operation.

On the other hand, the primary and secondary windings become 5 arranged such that it has a tubular core 7b a coil 7 surrounded, which has narrow dimensions and reinforced walls to the introduction of the cores 1b . 2 B to allow. The coil used 7 has a required robustness value to meet the limitations of the AEC-Q200 standard pertaining to the automotive field, whereby the proposed transformer is particularly useful for charging batteries in hybrid and / or electric vehicles.

The coil is preferred 7 made of a plastic material such as PET, LCP, a phenolic resin or a flame retardant material which allows to withstand a temperature range of -40 / + 155 ° C.

In order to allow winding of the windings, a nested winding technique is used which improves the coupling between the primary winding and the secondary winding to reduce the additional AC losses due to high frequency effects (superficially induced currents, flow effects in the gap, etc.).

In particular, the primary and secondary windings 5 from one turn (see 5 ) formed a plurality of filaments which are individually (for example stranded filaments) intertwined with three insulating layers, for example by means of a polyamide adhesive tape which surrounds the intertwined filaments. The type of filaments has high mechanical and thermal properties, so that the turn in each position three layers of insulating material according to the requirements of safety standards EN-60950, EN-61558 and EN-60664-1 having. The thickness of the filaments is about 0.05 to 0.2 mm to reduce the frequency effect through a better compromise between the Foucault current within the filament and the proximity between the parallel filaments.

As previously mentioned, the base points 7a the coil 7 Extensions, which are provided with a series of openings (of different dimensions), which are adapted to inserted flat contact pins 3 or plug 4 for mounting and connecting the transformer. The flat contact pins 3 be used for supplying the two windings, primary and secondary winding 5 and the plugs 4 are used for connection to an NTC thermal sensor embedded in said windings. These flat contact pins are preferred 3 and these plugs 4 made of a tinned phosphor bronze alloy.

4 shows the introduction process (steps 400 . 401 ) and the hiring process (step 402 ) one of the terminals, in particular one of the flat contact pins 3 into the corresponding opening of the base 7a the coil 7 , This type of assembly allows to ensure a degree of co-planarity of up to about 500 ☐m between the different terminals, allowing the transmission of high currents through the transformer.

5 shows another embodiment of the proposed transformer. In this case, if the ends of the cores 1b . 2 B in the tubular cavity of the coil 7 are arranged, no direct contact between the two ends is made, but it is an air gap 6 , a predetermined distance that is non-zero, with the aim of correcting the magnetizing inductance to the required L _P value for the LLC operation.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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 assumes no liability for any errors or omissions.

Cited patent literature

• ES 2393695 B1 [0006]
• CN 201829300 U [0007]

Cited non-patent literature

• EN 60950, EN 61558-1-2-17 [0018]
• Standard IEC-62317-13 [0030]
• EN-60950, EN-61558 and EN-60664-1 [0034]

Claims (11)

Transformer with integrated inductor, comprising: - a first magnetic body ( 1 ) and a second magnetic body ( 2 ), which are independent of each other, wherein the first magnetic body ( 1 ) and the second magnetic body ( 2 ) one plate each ( 1a . 2a ), from which a core ( 1b . 2 B ) with cylindrical or polygonal cross section; and primary and secondary windings ( 5 ), which are arranged so that they form a tubular core ( 7b ) of a coil ( 7 ) surrounded by electrical insulation material, the cores ( 1b . 2 B ) in the tubular cavity of the coil ( 7 ) are arranged and the ends of the cores ( 1b . 2 B ) with a predetermined distance, characterized in that - the primary and secondary windings ( 5 ) are each formed of a turn comprising a plurality of threads which are individually interlaced, with three insulation layers; and - one of the bases ( 7a ) of the coil ( 7 ) Has extensions which, together with end edges, are formed with a series of openings adapted to insert flat contact pins ( 3 ) or plug ( 4 ) with their end portions bent against the extensions to provide coplanar flat mounting and connection terminals. Transformer according to claim 1, characterized in that the series of openings comprise different dimensions, wherein a first group of openings of larger size is adapted to the flat contact pins ( 3 ) for the supply of the primary and secondary windings ( 5 ). Transformer according to claim 2, characterized in that a second set of smaller size openings are adapted to connect the plugs ( 4 ) for the connection of the primary and secondary windings ( 5 ) to a heat sensor. Transformer according to one of the preceding claims, characterized in that the flat contact pins ( 3 ) and the plugs ( 4 ) are made of a tin-plated phosphor bronze alloy. Transformer according to one of the preceding claims, characterized in that the plates ( 1a . 2a ) the magnetic body ( 1 . 2 ) form an "E" -shaped formation, wherein from each end of the magnetic body ( 1 . 2 ) a leg ( 1c . 2c ). Transformer according to claim 5, characterized in that the legs ( 1c . 2c ) are dimensioned such that when the magnetic bodies ( 1 . 2 ) with the cores ( 1b . 2 B ), the ends of said cores ( 1b . 2 B ) remain separated with the predetermined distance. Transformer according to one of the preceding claims, characterized in that the magnetic bodies ( 1 . 2 ) are made of a manganese-zinc-ferrite material. Transformer according to Claim 1, characterized in that the filaments of the primary and secondary windings ( 5 ) have a thickness of about 0.05 to 0.2 mm, Transformer according to claim 1, characterized in that the three insulating layers comprise a polyamide adhesive tape which surrounds the interlaced filaments. Transformer according to claim 1, characterized in that the coil ( 7 ) is made of a plastic material selected from PET, LCP, phenolic resin or a flame retardant material. Transformer according to one of the preceding claims, characterized in that the height of the unit or the distance between the outer surfaces of the two plates ( 1a . 2a ) is less than or equal to 40 mm.

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