AT15950U1 - Small-sized transformer for a control gear for bulbs - Google Patents

Abstract

The invention relates to a transformer (T1) for a driver circuit for operating a light-emitting means (LED), wherein the transformer (T1) has a primary winding (W1) formed as a first planar coil (L2a); and a secondary winding (W2) formed as a second planar coil (L2b); and a first core (K1) that substantially interacts electromagnetically with only the first planar coil (L2a); and a second core (K2) that interacts electromagnetically with both the first planar coil (L2a) and the second planar coil (L2b).

Description

description

SMALL-CONSTRUCTING TRANSFORMER FOR AN OPERATING DEVICE FOR LIGHTING AGENTS The invention relates generally to the field of operating devices for lamps, in particular LEDs, and in particular a transformer for an operating device.

Driver circuits, for example for operating light-emitting diodes, are basically known from the prior art. For example, illuminant converters with a resonance circuit are used as driver circuits, hereinafter referred to as resonance converters. With these resonance converters, a (series) resonance circuit is supplied by means of an alternating voltage. The resonance circuit in turn supplies a primary winding of a transformer with energy. The secondary winding of the transformer supplies an illuminant from the energy of the AC voltage. The supply voltage supplied to the illuminant must typically be a direct voltage. In principle, this can be done, for example, by a rectifier circuit connected downstream of the transformer.

The resonance converter is thus an electrical circuit that can be supplied with an input voltage and can be connected to the lamps, such as one or more LEDs, in order to be able to electrically operate the lamp in a defined manner.

In order to be able to transport the energy from the resonance circuit to the load, the load is coupled to the resonance circuit via an ideal transformer or the transformer. The transformer serves as a galvanic barrier or as a galvanic barrier between the generated alternating voltage and that for operating the illuminant direct voltage. This galvanic isolation may be required when using resonance converters to operate lamps and, among other things, is a security requirement.

The transformer can not be designed as an ideal transformer due to its structural design. Components of the transformer and components of the resonance circuit are thus combined in the practical implementation of the resonance converter. In particular, the magnetization inductance and the leakage inductance of the transformer are used.

The resonance circuit for resonance converters consists at least of a shunt coil. The shunt coil is provided to be able to transport the energy provided by the AC voltage to the load. The respective inductance for a resonance converter must be designed in such a way that its magnetic flux density, its oscillation frequency and also its loss parameters such as leakage inductance, skin effect and proximity effect are adapted to the respective requirements in the resonance converter. The respective inductance for a resonance converter can be provided in a wide variety of form factors. Coils are widely used, the turns of which are wound around a ferrite core.

[0007] In a resonance converter, the inductance used has two different properties.

On the one hand, the inductance is provided in order to efficiently store energy of the AC voltage provided. On the other hand, the energy of the AC voltage provided should be efficiently transferred to the load via the transformer. Both properties are more or less mutually exclusive, so that in the practical design of the inductance for a resonance converter, compromise solutions are always used in order to be able to fulfill the two properties simultaneously.

When designing the inductance, the leakage inductance is crucial. The problem here is that the leakage inductance is only a secondary parameter of an inductance, which results from structural conditions and is very difficult to consciously set. In addition, the leakage inductance changes very strongly depending on the magnetic flux density. Thus, either the maximum magnetic flux density is limited or the magnetic flux density is varied such that this is disadvantageous for the functionality of a resonance

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Patent Office is a converter.

In addition, an inductance for a resonance converter is usually developed through complex iterative and empirical approaches. Such results for an inductance are then highly precise, but cannot be produced in large numbers.

An object of the present invention is to propose a transformer for an operating device with a small size, but which is preferably easily adjustable in terms of different electrical characteristics.

[0012] The object is achieved with the measures described in the independent claims. Advantageous embodiments are described in the respective dependent claims.

In particular, the object is achieved by a transformer for a driver circuit for operating a lamp. For this purpose, the transformer has a primary winding which is designed as a first planar coil. The transformer has a secondary winding which is designed as a second planar coil. The transformer has a first core, which essentially only interacts electromagnetically with the first planar coil. The transformer also has a second core which is separate from the first core and which interacts electromagnetically both with the first planar coil and with the second planar coil.

The inventive design of the transformer with two cores and the corresponding different arrangement of the first planar coil or the second planar coil on the respective core, the main inductance and the leakage inductance of the resonance converter can be set separately. According to the invention, the primary winding of the transformer can generate a magnetic flux independently of the secondary winding. Thus, by appropriately designing the first planar coil and the first core, independent of the second planar coil and the second core, very good energy intermediate storage of the energy provided as well as the almost lossless energy transmission to the load can be achieved.

The first planar coil is thus not strongly coupled to the secondary side of the transformer and can be designed as a linearized inductor. As a choke inductor, the first planar coil can ideally store the energy in the form of its magnetic field.

In contrast to the first planar coil, the second planar coil is primarily provided for efficient energy transmission between the primary side and the secondary side due to the very good coupling of the primary winding and the secondary winding on the second core.

[0017] Planar coils are also referred to as flat coils. A planar coil is a coil formed in one plane, which consists of one or two lines (bifilar). This enables the primary winding and the secondary winding of the transformer to be formed in at least one plane. The transformer can thus be significantly reduced in size. When used in a resonance converter, the transformer is a component that influences the dimensions of the housing. A reduction in the transformer size with the same electrical property thus leads to a reduction in the size of the entire driver circuit for lamps.

[0018] The use of planar coils enables the main and leakage inductance of the transformer to be adjusted more easily.

The first planar coil and / or the second planar coil are designed, for example, as a bifilar coil, that is to say the respective planar coil is designed with a pair of conductors. When the current flows in opposite directions, the two magnetic fields that are created thereby almost cancel each other out. The current flows back and forth through the bifilar conductor. The bifilar or n-filar transformer has a particularly good impulse transmission behavior.

In a preferred embodiment, the primary winding is both around the first core

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Patent office and arranged around the second core. Furthermore, the secondary winding is only arranged around the second core. The targeted electromagnetic interaction of the respective planar coil with the respective core is thus improved. With this arrangement, the transformer has a much better magnetic conductivity than air and thus enables a stronger magnetic flux.

[0021] In a preferred embodiment, the first core is rod-shaped and / or the second core is rod-shaped. The rod-shaped configuration of the first core and / or the second core directs the magnetic flux in the core and creates an I shape for each of the cores. The construction according to the invention differs from the known so-called core design, since according to the invention the windings are not placed separately on the two outer legs, but the primary winding is guided around a first core and a second core, while the secondary winding is only guided around the second core. The first planar coil thus interacts with both the first core and the second core. The cross section of the respective core is selected in relation to the number of turns of the primary winding or the secondary winding. The flux density at the maximum permissible voltage is close to the permissible magnetic saturation flux density.

In a preferred embodiment, the first core and the second core are designed in an El shape, the primary winding being arranged around a center leg of the first core and also around a center leg of the second core. The secondary winding is only arranged around the middle leg of the second core. By designing the core with a middle leg, an El core shape is obtained. This differs from the known jacket design, since in the jacket design both turns are arranged on a central leg, either side by side or one above the other. In the el-shape of the cores, the middle leg is supplemented by two outer legs, each of which has no turns.

By using two cores in a transformer according to the invention, the main inductance can now be set separately from the leakage inductance, for example by different core diameters of the middle leg or by different diameters of the middle leg and outer leg. The first core thus essentially only interacts electromagnetically with the first planar coil. The second core then interacts electromagnetically both with the first planar coil and with the second planar coil.

The inductance of the first planar coil and the second planar coil results from the number of turns and from the material enclosed by the coil and the dimensions. The first planar coil and the second planar coil preferably have a plurality of turns in order to increase the inductance. Due to the magnetic interlinking of the individual turns of the first planar coil and / or the second planar coil with one another, due to the spatially close arrangement of the individual turns, the inductance of the first planar coil and / or the second planar coil increases in square with the number of turns. A doubling of the number of turns with the same geometrical dimensions thus quadruples the inductance. A further space saving is thus achieved by increasing the number of turns. The term winding is equated with the term winding in this application.

Preferably, the first planar coil has a higher number of turns than the second planar coil. The leakage inductance results from the first planar coil, which is formed around the first core, so that a higher number of turns leads to improved intermediate storage of the energy provided.

[0026] In a preferred embodiment, the primary winding and / or the secondary winding are formed by a spiral-shaped or rectangular conductor track. This simplifies the manufacturing process for the transformer and enables the manufacture of transformers for resonance converters in very large numbers. The longer the conductor tracks are, the greater the inductance of the respective coil. Due to a different design

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Patent office design of primary winding and secondary winding, the inductances can be set separately.

Preferably, the primary winding and the secondary winding are arranged on a common circuit board. This enables a further space saving and downsizing of the transformer. The primary winding and the secondary winding are either wound or preferably arranged as conductor tracks. The windings are designed, for example, as conductor tracks. The conductor tracks are preferably laminated as a printed circuit from a copper foil. An etching process enables the conductor tracks to be designed easily on the circuit board.

The circuit board is preferably constructed in layers, the primary winding being arranged in a first circuit board layer and the secondary winding being arranged in a second circuit board layer. The windings of the respective planar coil can thus be distributed on different levels. This reduces the space requirement of the transformer.

[0029] In a preferred embodiment, the printed circuit board is constructed in layers, the primary winding being arranged in at least two printed circuit board layers and / or the secondary winding being arranged in at least two printed circuit board layers. On the one hand, this reduces the space requirement of the respective coil, on the other hand, parasitic effects can be further reduced by placing opposing current paths in different layers one above the other. The number of turns can thus be increased further without additionally increasing the area of the printed circuit board.

[0030] In an advantageous embodiment, the first core is a two-part core and has a first air gap. In order to have ideal energy transfer properties, the second core - which interacts with both the first planar coil and the second planar coil - should have no air gap or a much smaller air gap. This second core is responsible for the transmission properties of the transformer and transports the energy provided to the load almost without loss if there is no air gap. The first air gap increases the leakage inductance. The energy is thus stored primarily in the first core of the transformer, so that the first transformer core is used for intermediate storage of the magnetic energy for use in the resonance converter. This buffering is set with the length of the first air gap in the magnetic circuit. Thus, the storage of the electromagnetic energy and the lossless transmission as the main properties of the transformer are decoupled from one another and can be set differently.

[0031] In a preferred embodiment, the second core is a two-part core and has a second air gap. The length of the first air gap is preferably different from the length of the second air gap. The length of the second air gap is preferably substantially less than the length of the first air gap. In this way, the leakage inductance of the transformer can be further adjusted. To improve production, the second core is also made in two parts, so that a second air gap cannot be completely prevented. Thus, the storage of the electromagnetic energy and the lossless transmission as the main properties of the transformer are still decoupled from one another and can be set differently.

If an El-shaped core is used, the respective air gap is preferably formed on the central leg of the core in order to maximize the electromagnetic interaction with the respective planar coil.

[0033] The main transformer material used is ferromagnetic materials, for example ferrites. Ferromagnetic material in the core has a much better magnetic conductivity than air and thus enables a stronger magnetic flux. In a preferred embodiment, the first core is made from a material different from the material of the second core. In this way, the magnetic resistance of the first

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Core differ from the second core, whereby the resulting inductors can vary further. To increase the magnetic resistance and the associated size reduction, the first planar coil preferably has a soft magnetic first core. In contrast to hard magnetic materials, the hysteresis loss when remagnetizing is kept small.

[0034] The first core preferably has geometric dimensions that are different from the geometric dimensions of the second core. Thus, for example, the thickness of the middle leg and / or the dimensions of the outer legs and / or the diameter of the core bar of the respective cores can be of different sizes. Thus, the resulting inductance will continue to vary between the first coil and the second coil.

In a preferred embodiment, the transformer has a third core which essentially only interacts electromagnetically with the secondary winding. In this way, three separate cores are provided in the transformer, only the second core interacting electromagnetically with the first planar coil and the second planar coil. In this way, the property with regard to the lossless transmission of energy can be set independently of the storage of the electromagnetic energy.

The object is further achieved by a resonance converter for operating at least one lamp, for example an LED section. The resonance converter has a half-bridge circuit with two switches connected in series, which are controlled by a control circuit. The resonance converter also has a resonance circuit supplied starting from a center point of the two switches. The resonance converter furthermore has a transformer which is fed on the primary side with an AC voltage provided by the resonance circuit, the energy of the AC voltage being used on the secondary side to operate the illuminant.

A resonance converter, also as a resonance converter, operates an energy transmission in the region of a resonance point. For power applications, the aim is to minimize the power loss during the switching operations in the switches. In this case, the voltage is either always switched at zero crossing, English: Zero Voltage Switching (ZVS) or always switched at zero current, English: Zero Current Switching (ZCS). The energy-transmitting path, including the transformer, forms a resonant circuit with capacitors and inductors, which also determines the range of the switching frequency.

[0038] According to the invention, the primary winding of the transformer is designed as a first planar coil. The secondary winding of the transformer is designed as a second planar coil. A first core of the transformer essentially only interacts electromagnetically with the first planar coil. A second core of the transformer interacts electromagnetically both with the first planar coil and with the second planar coil.

In this way, a resonance converter is obtained which has both good properties with regard to the lossless transmission of energy from the primary side to the secondary side of the transformer, and also has an efficient intermediate storage of the energy provided. The resonance converter can be made miniaturized in this way, since the planar coils used take up less volume.

Preferably, the secondary winding of the transformer has a center tap, so that the transformer on the secondary side provides a current path for each of the two polarities of the AC voltage. In this way, the secondary winding forms two planar coils, whereby the space requirements of the resonance converter are reduced more. In addition, an effective rectification is obtained in this way, since the transformer with a center tap on the secondary winding offers energetic advantages over rectification by means of a rectifier circuit.

The resonance converter adjusts the timing of the two switches of the holder circuit via a control circuit.

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Patent Office [0042] A shunt coil of the resonance circuit is preferably formed by the first planar coil. A resonance coil of the resonance circuit is further preferably formed at least partially by the first planar coil. The non-ideal properties of a transformer can now be used very specifically to combine components of the resonance circuit and the transformer. This combination is significantly improved by two separate cores in the transformer, because the leakage inductance can now be set separately from the main inductance of the transformer. The targeted adjustability can save additional compensating components.

The improved combination of components thus reduces the number of components in the resonance converter and the space requirement of the resonance converter.

The resonance converter is preferably an LLC converter, so that the resonance circuit consists of a resonance capacitance, a resonance coil and a shunt coil. These electrical components of the resonance circuit can now be formed at least in part very effectively by the transformer according to the invention.

The object is achieved in particular by a resonance circuit for a resonance converter for operating at least one light source, for example an LED track. An AC voltage is supplied to the resonance circuit on the input side. On the output side of the resonance circuit, a transformer is connected in order to provide the energy of the AC voltage to the illuminant. The primary winding of the transformer is designed as a first planar coil. The secondary winding of the transformer is designed as a second planar coil. A first core of the transformer essentially only interacts electromagnetically with the first planar coil. A second core of the transformer interacts electromagnetically both with the first planar coil and with the second planar coil.

A shunt coil of the resonance circuit is preferably formed by the first planar coil. A resonance coil of the resonance circuit is further preferably formed at least partially by the first planar coil.

The above-mentioned configurations of the transformer are used both for the transformer in the resonance converter and for the transformer connected downstream of the resonance circuit.

The described resonant circuit, the described resonant converter or the described transformer are preferably used in an electronic ballast for operating a lamp. The ballast for lamps is used to control the voltage or current through the lamp. It can be installed as a separate component in the luminaire or can also be integrated in the lamp. The ballast can be equipped with a control interface, for example a DALI interface, in order to receive control, monitoring and / or emergency commands and to implement them directly on the illuminant.

The invention and further embodiments and advantages of the invention are explained in more detail below with reference to figures, the figures merely describing exemplary embodiments of the invention. Identical components in the figures are provided with the same reference symbols. The figures are not to be regarded as true to scale, individual elements of the figures can be shown in an exaggerated size or in an exaggeratedly simplified manner.

[0050] It shows:

[0051] FIG. 1 shows a sectional illustration of a transformer according to the prior art;

2 shows a perspective view of a first exemplary embodiment of a transformer according to the invention;

Fig. 3 is a sectional view of the transformer according to the invention shown in Fig. 2 as a plan view of a first sectional plane A-A ';

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4 shows a sectional view of the transformer according to the invention shown in FIG. 2 as a plan view of a second sectional plane B-B ';

Fig. 5 is a sectional view of the transformer according to the invention shown in Fig. 2 as a top view of a third sectional plane C-C ';

Fig. 6 is a sectional view of the transformer according to the invention shown in Fig. 2 along the first sectional plane A-A ';

7 shows a sectional illustration of a second exemplary embodiment of a transformer according to the invention;

[0058] FIG. 8 shows a sectional illustration of a third exemplary embodiment of a transformer according to the invention;

9 shows a sectional illustration of a fourth exemplary embodiment of a transformer according to the invention;

10 shows an electrical circuit of a resonance circuit according to the invention with a downstream transformer according to the invention;

11 shows a block diagram of an exemplary embodiment of a resonance converter according to the invention.

1 shows a transformer according to the prior art as a sectional view. The transformer T1 has a primary winding W1 and a secondary winding W2. Both the primary winding W1 and the secondary winding W2 are wound around a middle leg MS of a core K of the transformer. The transformer is a so-called jacket transformer and has a core K in jacket design. 1, the primary winding W1 and the secondary winding W2 are located one above the other on the middle leg MS of the core K. In this design, the middle leg MS is supplemented by two outer legs that do not have any turns.

Thus, both the primary winding W1 and the secondary winding W2 interact electromagnetically in connection with the core K.

A disadvantage of the construction according to FIG. 1 is the comparatively large volume of the transformer.

Furthermore, the main properties of the energy storage and the lossless transmission of energy required for a transformer in a resonance converter cannot be uncompromisingly combined, so that the transformer is either a good energy storage or a good energy exchanger.

2 shows a first exemplary embodiment of a transformer T according to the invention in a perspective view. A circuit board LP is shown horizontally. The primary winding W1 and the secondary winding W2 are arranged on the printed circuit board LP. The primary winding W1 is designed as a first planar coil L2a. The secondary winding W2 is designed as a second planar coil L2b. Both the primary winding W1 and the secondary winding W2 each have a single turn. The number of turns of the primary winding W1 and the secondary winding W2 can be significantly higher, with a plurality of turns being dispensed with in this illustration. Alternatively, the primary winding W1 and the secondary winding W2 can also be designed as bifilar coils.

According to the invention it is provided that the transformer T1 has a first core K1 and a second core K2. 2, both the first core K1 and the second core K2 are formed in two parts, so that simplified production is possible. The respective first parts of the first core K1 and the second core K2 are designed in an E-shape. The respective second parts of the first core K1 and the second core K2 are plate-shaped or bar-shaped.

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Patent Office The first core K1 and the second core K2 are integrated in the circuit board LP such that the primary winding W1 is arranged both around the first core K1 and around the second core K2. The primary winding W1 thus interacts electromagnetically with the first core K1 and the second core K2. In contrast, the secondary winding W2 is arranged only around the second core K2, so that essentially only the second core K2 interacts electromagnetically with the secondary winding W2.

The transformer T1 according to the invention thus has two cores K1, K2. The second core K2 is surrounded by both the primary winding W1 and the secondary winding W2. This results in a significantly stronger energy coupling between the primary winding W1 and the secondary winding W2 at the second core K2. The second core K2 thus ensures the low-loss or lossless transport of the energy from an AC voltage provided on the primary winding W1 to a load connected to the secondary winding W2.

In contrast, only the primary winding W1 is arranged around the first core K1 or the secondary winding W2 is not arranged around the first core K1. The energy coupling of the primary winding W1 to the secondary winding W2 on the first core K1 is thus significantly lower compared to the energy coupling on the second core K2.

The first core K1 can thus be used to set the leakage inductance and accordingly serves for the intermediate storage of the energy when used in a resonance converter.

Due to the different electromagnetic interaction, the two main properties of the transformer T1 can be divided between the two cores K1, K2. In this way, the leakage inductance can be set in a targeted manner via the first core K1, since the energy is essentially transmitted at the second core K2. Thus, by appropriately designing the two cores K1 and K2, the property with regard to the inductance of a resonance circuit for a resonance converter and the property of the transformer as an ideal transformer can be optimized.

This optimization takes place, for example, by forming a first air gap LS1 on the first core K1 and no air gap on the second core K2. The magnetic resistance R _m and, as a result, the magnetic flux Φ at the first core K1 is significantly increased by the first air gap LS1. In conclusion, the leakage inductance for temporarily storing the energy is significantly improved. Alternatively, an air gap LS2 is also provided on the second core K2. The first air gap LS1 has a length that is increased by the second air gap LS2, in order not to significantly impair the transformer property of the second core K2.

This optimization is also carried out, for example, by a higher number of turns of the primary winding W1 compared to the number of turns of the secondary winding W2. With the same core cross section, the higher number of turns significantly increases the inductance, formed by the first core K1, and increases the buffering property of the transformer.

Alternatively or additionally, the first core K1, in contrast to the second core K2, is formed with a soft magnetic core material. The primary winding W1 then acts as a choke coil.

[0076] Alternatively, the core diameter of the first core K1 is increased compared to the core diameter of the second core K2. This additionally increases the magnetic flux.

In the following FIGS. 3 to 6, different sectional representations along or on different sectional planes A-A ', B-B' and C-C 'of the transformer T according to the invention shown in FIG. 2 are shown.

FIG. 3 shows a sectional illustration of the transformer according to the invention shown in FIG. 2 as a top view of a first sectional plane A-A '. The primary winding W1 is rectangular and spiral around both the first core K1 and the second core K2

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Patent Office trained around. In contrast, the secondary winding W2 is rectangular and spirally arranged only around the second core K2. A current flowing through the primary winding W1 induces a voltage due to the magnetic properties of the first core K1 and the second core K2. In contrast, a current flowing through the secondary winding W2 will only induce a voltage based on the second core K2.

If the two cores K1 and K2 are dimensioned differently, different inductances are generated and the different properties of the transformer T1 are optimally adapted. The coupling between the primary side and the secondary side of the transformer T1 necessary for transmitting the energy is thus carried out primarily on the second core K2. In contrast, the high magnetic flux required for the intermediate storage of the energy is obtained through the first core K1.

The cores K1 and K2 each have a central web MS, around which the windings W1, W2 are arranged.

In Fig. 3, the cores K1 and K2 are of the same size in order to enable simplified production. Alternatively, the central web MS of the first core K1 can be made larger than the central web MS of the second core K2 in order to further increase the magnetic flux at the first core K1.

4 shows a sectional illustration of the transformer according to the invention shown in FIG. 2 as a top view of a second sectional plane BB '. The second core K2 is formed in an El shape and constructed in two parts. A second air gap LS2 is provided in the core K2 in order to influence the magnetic resistance R _{M of} the second core K2. For the sake of completeness, the primary winding W1 and the secondary winding W2 around the middle leg MS of the second core K2 are also shown on the printed circuit board LP.

5 shows a sectional illustration of the transformer according to the invention shown in FIG. 2 as a top view of a third sectional plane CC '. The first core K1 is formed in an El shape and constructed in two parts. A first air gap LS1 is provided in the core K1 in order to influence the magnetic resistance R _{M of} the first core K2. The primary winding W1 around the middle leg MS of the first core K1 is also shown on the printed circuit board LP.

The first air gap LS1 has a greater length than the second air gap LS2 of the second core K2. Various magnetic resistances R _M are thus set on the cores K1, K2, the larger air gap LS1 having the result that the leakage inductance of the transformer T1 is substantially increased, as a result of which the intermediate storage of energy is improved. The second air gap LS2 has a substantially shorter length than the first air gap LS1 or is not present at all in order not to impair the transmission properties.

FIG. 6 shows a sectional illustration of the transformer according to the invention shown in FIG. 2 along the first sectional plane A-A '. The circuit board LP is formed in one layer. The primary winding W1 is arranged on the printed circuit board LP around the first core K1 and the second core K2. The secondary winding W2 is arranged around the second core K2 on the printed circuit board LP. The primary winding W1 and the secondary winding W2 are designed as planar coils L2a and L2b. The windings W1, W2 are preferably placed as conductor tracks on the circuit board LP. The conductor tracks of the windings W1, W2 can be arranged in a bifilar manner. The circuit boards can be applied using printing technology or can be obtained from a copper foil layer in an etching process. This enables inexpensive and mass-produced manufacture of the transformer.

The conductor tracks of the windings W1, W2 are preferably spiral-shaped in order to enable a higher number of turns and a longer conductor track length. The inductivities of the transformer T1 can thus be further optimized.

7 is a sectional view of a second embodiment of an invented invention

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Represented transformer T1 according to the invention. The same view was chosen as in Fig. 6. In contrast to FIG. 6, the printed circuit board LP in FIG. 7 is formed in two layers. The primary winding W1 is formed in a first circuit board layer LPS1. The secondary winding W2 is formed in a second circuit board layer LPS2. In this way, a further reduction in space is obtained since the windings W1 and W2, which are designed in the form of spirals, are now formed in two different planes. The volume of the transformer T1 is thus further reduced. In addition, the distances between the turns can be increased, so that the proximity effect is reduced.

8 shows a sectional illustration of a third exemplary embodiment of a transformer according to the invention. The same view as in FIGS. 6 and 7 was chosen. In contrast to FIG. 6, the printed circuit board LP in FIG. 7 is formed in four layers with the layers LPS1, LPS2, LPS3 and LPS4. The primary winding W1 is arranged in a first layer LPS1 and in a third layer LPS3. The secondary winding W2 is arranged in a second layer LPS2 and in a fourth layer LPS4. The number of layers can be increased further, in particular different number of layers can be provided for the different windings W1, W2. The primary winding W1 has a larger number of turns than the secondary winding W2, as a result of which a greater leakage inductance and consequently a greater temporary storage of energy is achieved. In principle, the higher number of layers results in a further reduction in the area of the transformer T and in particular a reduction in the volume of the transformer T. The individual layers LPS1 and LPS3 or LPS2 and LPS4 of the individual windings W1, W2 are connected, for example, by means of vias. It can also be provided that the printed circuit board LP has two conductor track layers, a first conductor track layer being arranged on a first upper side of the printed circuit board LP and a second conductor track layer being arranged on a second upper side of the printed circuit board LP opposite the first upper side.

9 shows a sectional illustration of a third exemplary embodiment of a transformer T according to the invention. The same view was chosen as in Fig. 3. In contrast to FIG. 3, a third core K3 is arranged in FIG. 9. The secondary winding W2 is arranged around the second core K2 and the third core K3. Thus, only the secondary winding W2 is arranged around the core K3. This further increases the adjustability of the inductances of the transformer T1, since the leakage inductance on the secondary side can now be adjusted in an improved manner.

For all the transformers T1 shown, it is also shown in FIG. 9 that a center tap M1 is arranged on the secondary winding W2. The third core K3 can in turn be made with a material different from the second core K2 and have other geometrical dimensions, for example air gap length or core diameter.

10 shows an electrical circuit of a resonance circuit RK according to the invention with a transformer T1 connected downstream. The resonant circuit RK is shown in Fig. 10 as an LLC resonant circuit. The electrical resonance circuit RK consists electrically of three components connected in series. A resonance capacitor C1 is connected in series with a resonance coil L1. The resonance coil L1 is connected in series with a shunt coil L2. The resonance capacitor C1, the resonance coil L1 and the shunt coil L2 form the LLC resonance circuit RK, hereinafter referred to as resonance circuit RK. The voltage across the shunt coil L2 is provided to an ideal transformer. The ideal transformer has a primary winding W1 and a secondary winding W2.

If we now consider a practical implementation of the transformer T1, the first planar coil L2a forms both the primary winding W1 and the shunt coil L2. The resonance coil L1 is also formed by the planar coil L2a. The first planar coil L2a of the transformer T1 according to the invention thus forms the primary winding 1, the resonance coil L1 and the shunt coil L2. Since the primary winding W1 according to the above embodiment10 / 23

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Patentamt gene over number of turns, air gap length, core material, core dimensions can be set as desired, the desired magnetization inductance and leakage inductance can be obtained by the appropriate design of the first planar coil L2a and the first core K1 independently of the second core K2 and the second planar coil L2b. A reduction in the components and a reduction in the space required for the resonance circuit RK is thus obtained.

The resonance circuit RK in FIG. 10 is purely exemplary. Alternatively, the resonance circuit RK can only consist of a shunt coil L2. Alternatively, the resonance circuit RK can also be an LCC resonance circuit. Alternatively, a parallel resonance circuit RK can also be formed.

11 shows a resonance converter according to the invention. 11 shows the schematic structure of an LLC converter as a representative of the resonance converter. Alternatively, an LCC converter or any other resonance converter can also be included under the concept of the invention. A control circuit SE controls an inverter half bridge HB with two switches S1, S2, which are connected in series. The switches S1, S2 are designed as a MOSFET. As shown in FIG. 11, the half-bridge circuit HB is supplied by an input voltage, which is exemplarily shown as bus voltage V _B us. Instead of a bus voltage, which is normally a DC voltage, ie a DC voltage, a rectified AC voltage can also be used to supply the half-bridge HB.

Starting from a center point M of the half-bridge HB, or the two switches S1, S2, the resonance circuit RK is now supplied, which according to FIG. 11 is formed from a series connection of the resonance capacitor C1, the resonance inductance L1 and the first planar coil L2a , The first planar coil L2a forms the primary winding W1 of the transformer T1 according to the invention and, as explained in FIG. 10, also represents the shunt coil L2.

Starting from the resonant circuit RK, the transformer T1 is now supplied with an alternating voltage on the primary side. The transformer T1 has a secondary winding W2 with a center tap M1 in order to form the inductors L2b, L2c shown in FIG. 11. The inductors L2b and L2c are arranged on the secondary side of the transformer T1 and are formed as a second planar coil by the secondary winding W2.

Starting from the inductors L2b and L2c, one current path SP1 or SP2 is then supplied in each case. The current paths SP1 and SP2 thus each connect one side of the inductance L2b, L2c to a connection point CP, each current path SP1, SP2 having a diode D1, D2 for rectification.

The first current path SP1 has the diode D1, while the second current path SP2 has a second diode D2. An induced current I _S pi is transmitted via the first current path SP1, and an induced current I _S p _{2 is} transmitted via the current path SP2. On the other hand, the connection point CP connects an output connection E1 of the resonance converter to which, for example, a load LED, for example a lamp, and in particular at least one LED can be connected.

Between the connection point CP and the output terminal E1, a smoothing capacitor C2 is also connected to its higher potential side, wherein the lower potential side of the second capacitor C2 can be at the secondary-side ground potential of the transformer.

The control circuit SE controls the higher potential switch S1 of the half bridge HB via a control signal HS ("high side signal), while it controls the lower potential switch S2 of the half bridge with a signal LS (" low side signal). The control circuit SE switches the switches S1, S2, which are preferably transistors, for. B. FET, MOSFET, are formed alternately to provide an alternating voltage for the transformer T1 at the center point M of the half bridge HB.

11, the primary winding W1 of the transformer T1 is connected on its lower-potential side to the primary-side ground, as is the lower-potential side

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The center tap M1 of the secondary winding W2, however, serves to provide currents or voltages at the connection point CP which are essentially symmetrical about a zero point.

Via the diodes D1 and D2, a direct current or a direct voltage is provided at the connection point CP in order to operate the load LED. 11, the secondary mass can either be connected to the primary mass or can be provided in isolation from it.

Overall, the voltage at the output terminal E1 or the current I _S pi or I _S p ₂ depends on the voltage applied to the primary-side inductance of the transformer T1 or the waveform of the voltage. These can be set by changing a clocking or switching frequency of the switches S1, S2 or a duty cycle of the half-bridge circuit HB, ie in particular a change in the switch-on time of the switches S1, S2.

Due to the configurations of the transformer T1 in the manner according to the invention there is a galvanic separation of the primary winding W1 and the secondary winding W2, whereby the overall size of the transformer T1 is reduced and the number of components is further reduced. The resonance converter according to the invention comprises a transformer T1, the inductance of which can be set separately from one another by means of two separate cores K1, K2.

In the context of the invention, all the elements described and / or drawn and / or claimed can be combined with one another as desired.

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LIST OF REFERENCE NUMBERS:

C1 resonant capacitor C2 charging capacitor D1, D2 rectifier diode K1 First core K2 Second core K3 Third core L1 resonance coil L2 Shuntspule L2a primary coil of the transformer L2b secondary coil of the transformer LED Lamp LP circuit board LPS1- -LPS4 layers of the circuit board LS1 First air gap LS2 Second air gap M Center of the half bridge M1 Center tap of the secondary winding MS Metatarsal of the nucleus RK resonant circuit S1 first switch of the half bridge S2 second switch of the half bridge SE control circuit SP1 First signal path SP2 Second signal path T1 transformer W1 primary W2 secondary winding φΡ Magnetic flux of the primary side ®S Magnetic flux of the secondary side

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Claims (10)

Expectations 1. Transformer (T1) for a driver circuit for operating a lamp (LED), characterized in that the transformer (T1) has: - A primary winding (W1), designed as a first planar coil (L2a); - A secondary winding (W2), designed as a second planar coil (L2b); - a first core (K1) which essentially only interacts electromagnetically with the first planar coil (L2a); and - A second core (K2) which interacts electromagnetically both with the first planar coil (L2a) and with the second planar coil (L2b). 2. Transformer according to claim 1, characterized in that the primary winding (W1) is arranged both around the first core (K1) and around the second core (K2) and wherein the secondary winding (W2) only around the second core (K2 ) is arranged around; and / or that the first core (K1) is rod-shaped and / or that the second core (K2) is rod-shaped; and / or that the first core (K1) and the second core (K2) are designed in an El shape; wherein the primary winding (W1) is arranged around a middle leg (MS) of the first core (K1) as well as around a middle leg (MS) of the second core (K2); and wherein the secondary winding (W2) is arranged only around the middle leg (MS) of the second core (K2); and / or that the first planar coil (L2a) and the second planar coil (L2b) have a plurality of turns, the first planar coil (L2a) having a higher number of turns than the second planar coil (L2b). 3. Transformer according to one of the preceding claims, characterized in that the primary winding (W1) and / or the secondary winding (W2) is formed by a spiral or rectangular conductor track; and / or that the primary winding (W1) and the secondary winding (W2) are arranged on a common printed circuit board (LP). 4. Transformer according to one of the preceding claims, characterized in that the first core (K1) is a two-part core with a first air gap (LS1); and / or that the first core (K1) is made of a material different from the material of the second core (K2); and / or that the first core (K1) has geometric dimensions that are different from the geometric dimensions of the second core (K2). 5. Transformer according to one of the preceding claims, characterized in that the transformer (T1) has a third core (K3) which essentially only interacts electromagnetically with the second planar coil (L2b). 6. Resonance converter for operating at least one light source (LED), for example an LED section, the resonance converter having: a half-bridge circuit (HB) with two switches (S1, S2) connected in series and controlled by a control circuit (SE), a resonance circuit (RK) supplied from a center point (M) of the two switches (S1, S2), - A transformer (T1), which is fed on the primary side with an AC voltage provided by the resonance circuit (RK), the energy of the AC voltage being used on the secondary side to operate the illuminant; characterized in that the primary winding (W1) of the transformer (T1) is designed as a first planar coil (L2a); and 14/23 AT15 950U1 2018-10-15 Austrian Patent office that the secondary winding (W2) of the transformer (T1) is designed as a second planar coil (L2b); and that a first core (K1) of the transformer (T1) essentially only interacts electromagnetically with the first planar coil (L2a); and that a second core (K2) of the transformer (T1) interacts electromagnetically both with the first planar coil (L2a) and with the second planar coil (L2b). 7. resonance converter according to claim 6, characterized in that the secondary winding (W2) has a center tap (M1), so that the transformer (T1) on the secondary side provides a current path (SP1, SP2) for each of the two polarities of the AC voltage; and / or that a shunt coil (L2) of the resonance circuit (RK) is formed by the first planar coil (L2a); and / or that a resonance coil (L1) of the resonance circuit (RK) is at least partially formed by the first planar coil (L2a). 8. resonance circuit for a resonance converter for operating at least one illuminant (LED), for example an LED section, - An alternating voltage is supplied to the resonance circuit (RK) on the input side; - The resonance circuit (RK) on the output side is followed by a transformer (T1) in order to provide the energy of the AC voltage to the illuminant (LED); characterized in that the primary winding (W1) of the transformer (T1) is designed as a first planar coil (L2a); and that the secondary winding (W2) of the transformer (T1) is designed as a second planar coil (L2b); that a first core (K1) of the transformer (T1) essentially only interacts electromagnetically with the first planar coil (L2a); and that a second core (K2) of the transformer (T1) interacts electromagnetically both with the first planar coil (L2a) and with the second planar coil (L2b). 9. resonant circuit according to one of claims 8, characterized in that the primary winding (W1) forms a shunt coil (L2) of the resonant circuit (RK); and / or that the primary winding (W1) at least partially forms a resonance coil (L1) of the resonance circuit (RK); and / or that the first core (K1) is a two-part core with a first air gap (LS1); and / or that the second core (K2) is a two-part core with a second air gap (LS2). 10. Control gear for light sources, in particular LED converters, characterized in that the control gear has a transformer according to one of claims 1 to 5. 8 sheets of drawings 15/23 AT15 950U1 2018-10-15 Austrian Patent Office 1.8 Fig. 1 - State of the art 16/23 AT15 950U1 2018-10-15 Austrian Patent Office 2.8 Fig. 2 17/23 AT15 950U1 2018-10-15 Austrian Patent Office 3.8 A ' Fig. 3 18/23 AT15 950U1 2018-10-15 Austrian Patent Office 4.8 B B ' Figure 4 C ' Fig. 5 19/23 AT15 950U1 2018-10-15 Austrian Patent Office 5.8 K1 K2 Fig. 6 20/23 AT15 950U1 2018-10-15 Austrian Patent Office 6Z8 K3 zzzzzzzzAzZvzzzzzzzzzzzzzz / zxxxzxzJxxzxzxzxxxzzzxzxzz. zzzzzzzzzzzzzzzzzzzzzzzzzzz V W1 λλλζλλλλλλλλλζ Fig. 9 <χλχχλλλχχχχχλ7ΖΖ /// Ζ /// Ζ / Ζ zzzzzzzzzzzzzzzzzzzzzzzzzzz. ZZZZZZXZZZXZXZXZZZXZX / XZXZZ, ZZZZZZZZXXZXXZZZXZXXX / XX / XZ, / zzxxzzxxxxxzzxzzxzxzxxxzxz, ZZXXXXX / XXXXXZXZXXXX / ZXZXX / XZX / XZX / XZX / XZX ZZZZZZZZZZZZZZZZZZZZZZZZZZZ; zzzzzzzzzzzzzzzzzzzzzzzzzzz * zzzzzzzzzzzzzzzzzzzzzzzzzzz, M1 W2 21/23 AT15 950U1 2018-10-15 Austrian Patent Office 7.8 Fig. 10 22/23 AT15 950U1 2018-10-15 Austrian Patent Office 8.8 Q LU i-CH— | i * I Fig. 11 r — I <S <“vj 23/23