Patent Application
20230360845
This application claims the benefit of priority to United Kingdom Patent Application No. 2206600.5 filed on May 5, 2022. The entire contents of this application are hereby incorporated herein by reference.
This application relates to a winding arrangement of an electrical transformer, and an electrical transformer including the winding arrangement.
Murata's pdqb winding technology makes it possible to achieve the theoretically minimum level of high frequency conductor losses in high-power, high-frequency transformers (which typically have operating parameters above 10 kW and 10 kHz). Murata's pdqb technology is described in UK patent application publication GB2574481A and international patent application publication WO 2019/234453 A1, which are hereby incorporated by reference in their entirety.
Further, Murata's thermal management technology makes it possible to extract heat generated in compact transformer structures effectively. Murata's thermal management technology is described in UK patent application publications GB2597670A and GB2597470A, and international patent application publications WO 2022/023744 A1 and WO 2022/018436 A1, which are hereby incorporated by reference in their entirety.
Moreover, there are a number of parameters, approximately 40, that affect the design of a high-power, high-frequency transformer. These include the primary voltage, secondary voltage, rated power (continuous), operating frequency, primary inductance, secondary inductance, leakage inductance, primary DC resistance, secondary DC resistance, primary AC resistance, secondary AC resistance, and the interwinding capacitance. Different parameters have a different degree of significance for different applications of the transformer, making it difficult provide a single construction or even a small group of different constructions that will be suitable for all these applications.
Previous attempts to provide a universal transformer have included using different core sizes and/or core assemblies to make the transformer suitable for different voltage and frequency levels.
A power level in the range of 30 kW to 70 kW is desirable for many applications. For example, a 50-kW power level is a reasonable power level that would cover over 90% of common applications.
It is desirable to provide an improved, cost-effective single transformer construction applicable to many applications. In particular, a construction where only minor adjustments can make the transformer universal for the above-mentioned power level over a range of voltages and frequencies of operation.
According to a first preferred embodiment of the present invention, a winding arrangement for an electrical transformer is provided. The winding arrangement includes a primary coil and a secondary coil. The primary coil and the secondary coil each include a first section and a second section, and each of the first and second sections include a first set of turns having a first diameter and a second set of turns having a second diameter. The first diameter is larger than the second diameter. The first section and second section of the primary coil are electrically connected in parallel and are wound around a common winding axis, with the second set of turns of the second section positioned within the first set of turns of the first section, and the second set of turns of the first section positioned within the first set of turns of the second section, when viewed along the common winding axis. The first section and second section of the secondary coil are electrically connected in parallel and are also wound around the common winding axis, with the second set of turns of the second section positioned within the first set of turns of the first section, and the second set of turns of the first section positioned within the first set of turns of the second section, when viewed along the common winding axis. The turns of the primary coil are interleaved with the turns of the secondary coil.
Optionally, the primary coil is interleaved with the secondary coil such that each turn of the secondary coil is disposed between two turns of the primary coil when viewed along a direction perpendicular to the common winding axis.
Optionally, the primary coil is interleaved with the secondary coil such that the turns of the first set of turns of the primary coil and the turns of the first set of turns of the secondary coil alternate along the common winding axis, and the turns of the second sets of turns of the primary coil and the turns of the second sets of turns of the secondary coil alternate along the common winding axis.
Optionally, the primary coil is identical to the secondary coil.
Optionally, the secondary coil is rotated by 180° about the common winding axis relative to the primary coil.
Optionally, the winding arrangement further includes one or more additional secondary coils. The one or more additional secondary coils each include a first section and a second section, and each of the first and second sections include a first set of turns having the first diameter and a second set of turns having the second diameter. The first section and second section of each additional secondary coil are electrically connected in parallel and are wound around the common winding axis, with the second set of turns of the second section positioned within the first set of turns of the first section, and the second set of turns of the first section positioned within the first set of turns of the second section, when viewed along the common winding axis. The turns of the primary coil are interleaved with the turns of the one or more additional secondary coils.
Optionally, the primary coil is interleaved with the secondary coil and the one or more additional secondary coils such that: each turn of the secondary coil is disposed between two turns of the primary coil when viewed along a direction perpendicular to the common winding axis, and each turn of the one or more additional secondary coils is disposed between two turns of the primary coil when viewed along the plane containing the common winding axis.
Optionally, the primary coil is interleaved with the secondary coil and the one or more additional secondary coils such that the turns of the first set of turns of the primary coil and the turns of the first set of turns of the secondary coil alternate along a first portion of the common winding axis, and the turns of the second sets of turns of the primary coil and the turns of the second sets of turns of the secondary coil alternate along the first portion of the common winding axis, and the turns of the first set of turns of the primary coil and the turns of the first set of turns of the one or more additional secondary coils alternate along a second portion of the common winding axis, and the turns of the second sets of turns of the primary coil and the turns of the second sets of turns of the one or more additional secondary coils alternate along the second portion of the common winding axis.
Optionally, the number of turns in the primary coil is greater than or equal to the combined total number of turns in the secondary coil and the one or more additional secondary coils.
Optionally, the winding arrangement includes up to nine additional secondary coils.
Optionally, the secondary coil and the one or more additional secondary coils are stacked such that the secondary coil and the one or more additional secondary coils fully overlap when viewed along the common winding axis.
Optionally, the primary coil and the secondary coil fully overlap when viewed along the common winding axis.
Optionally, for each coil, the number of turns in the first set of turns of the first section and the number of turns in the first set of turns of the second section of are equal, and the number of turns in the second set of turns of the first section and the number of turns in the second set of turns of the second section of are equal.
Optionally, for each section of each coil the number of turns in the first set of turns is equal to the number of turns in the second set of turns of that section.
Optionally, the first sets of turns and the second sets of turns of each coil are concentric about the common winding axis.
Optionally, the turns of each of the coils includes a rectangular, square, or circular shape about the winding axis; and/or each set of turns is arranged helically around the common winding axis.
Optionally, each of the coils are formed from aluminum wire.
Optionally, each of the coils is formed from flat wire.
Optionally, the flat wire has a width of between 10 mm and 15 mm, and a thickness of between about 0.8 mm and about 1.2 mm, preferably a thickness of about 1 mm.
Optionally, each of the coils are encased in a potting material.
Optionally, each coil includes connection terminals extending parallel or substantially parallel to the direction of the common winding axis, for allowing an electrical connection to be made with that coil.
Optionally, the connection terminals of the primary coil and the connection terminals of the secondary coil or coils are located on opposing sides of the winding arrangement.
According to a second preferred embodiment of the present invention, a winding arrangement for an electrical transformer is provided. The winding arrangement includes a primary coil and plurality of secondary coils. The primary coil includes a first section and a second section, and each of the first and second sections include a first set of turns including a first diameter and a second set of turns including a second diameter. The first diameter is larger than the second diameter. The first section and second section of the primary coil are electrically connected in parallel and are wound around a common winding axis, with the second set of turns of the second section positioned within the first set of turns of the first section, and the second set of turns of the first section positioned within the first set of turns of the second section, when viewed along the common winding axis. Each of the plurality of secondary coils includes a first set of turns including the first diameter and a second set of turns including the second diameter, both wound around the common winding axis. The turns of the primary coil are interleaved with the turns of the plurality of secondary coils.
Optionally, the primary coil is interleaved with the secondary coils such that each turn of the plurality of secondary coils is disposed between two turns of the primary coil when viewed along a direction perpendicular to the common winding axis.
According to a third preferred embodiment of the present invention, an electrical transformer is provided. The electrical transformer includes a transformer core; and the winding arrangement of the first or second preferred embodiments arranged around the transformer core.
The winding arrangements of the first and second preferred embodiments reduce losses caused by the proximity effect, due to the interleaving of the primary and secondary coils. Moreover, the winding arrangements allow multiple secondary coils to be used, while retaining a compact structure and small footprint, allowing a transformer including the winding arrangement to power multiple circuits and/or provide redundancy in both high- and low-current situations. Lastly, when multiple secondary coils are used, series and parallel connections between the secondary coils can be tailored to allow the transformer to operate with the desired power over large voltage and frequency ranges.
According to a fourth preferred embodiment of the present invention, an electrical transformer is provided. The electrical transformer of the fourth preferred embodiment is described in the following clauses:
The electrical transformer of the fourth preferred embodiment provides a number of advantages. The semi-open construction enhances the cooling of the transformer core and winding, while also reducing the weight and cost of the device. Moreover, the electrical transformer is modifiable after installation, thus providing an adaptable transformer that is applicable to many applications, and universal over power ratings in the range of about 50 kW to about 100 kW.
In particular, a simple change of the plurality of thermally conductive sections (between those with and without radiating fins) and/or a simple change of the lower panel (such as introducing a cooling plate) means that the transformer can be made suitable for various different forced air cooled, natural convention cooled, or water cooled plate mounted constructions. The winding arrangement can also be changed after initial installation. These modifications are easily performed by, for example, using releasable connections, helping to provide a universal transformer construction.
The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.
The transformer 200 can be a high-frequency transformer, a high-voltage transformer, a high-power transformer, a high-power, high-frequency transformer, a high-voltage high-frequency high-power transformer, or the like. A single-phase shell-type transformer is considered in
The winding unit 204 includes at least one primary coil and one or more secondary coils encased in a potting material. The coils in the winding unit 204 share a common winding axis. The winding unit 204 is arranged around the transformer core 202. Specifically, the winding unit 204 surrounds the central portion (the middle strut) of the transformer core as shown in
A number of different winding arrangements could be used for in the winding unit 204. For example, round wire windings, flat wire windings, or even litz wire may be used. The windings may be formed from square or substantially square turns. The winding unit 204 as a whole including the potting material may therefore a be a square toroidal (donut) shape, as shown in
Alternatively, other winding arrangements could be used. More than one set of windings may be used in the winding unit 204, and each set of windings may contain a number of different coils, for example a primary and one or more secondary coils. The windings in the winding unit 204 may be insulated and protected due to the potting material. The potting material may be cast resin or epoxy or the like. Other transformer grade potting materials can be used, including silicon. The potting material can have a temperature class of class H or higher. However, for certain applications Class B or Class F potting materials may also be used.
In general, any winding configuration may be used with the transformer core 202 and housing 208. Specific configurations of possible winding arrangements in some preferred embodiments of the present invention will be discussed in more detail later in
Returning to
In the present preferred embodiment, the housing includes two open sides, marked by arrows A, BA, B in
This semi-open construction has a number of benefits. Rather than the entire transformer being encased in a potting material, the hybrid construction where only the winding unit 204 is encased in a potting material results in a reduced weight and manufacturing cost. Moreover, cooling for the winding unit 204 is improved by allowing portions of the winding unit 204 to be exposed to the surrounding air, without including a completely exposed coils (i.e. an unpotted winding unit) and the associated challenges that such a configuration would present (for example movement of the coils, insulation, and vulnerability to damage). The semi-open construction of preferred embodiments of the present invention is specifically configured to optimize the trade-off between enhanced cooling and reduced weight versus retaining the structural integrity of the transformer.
In more detail, the housing 208 includes an upper panel 210 and a lower panel 212 disposed on opposing sides of the transformer. The upper and lower panels 210, 212 both extend in planes normal to a winding axis of the winding unit 204. In other words, the upper panel 210 is located on the top surface of the transformer 200 in
The upper and lower panels 210, 212 are in contact with the transformer core 202 on the top and bottom sides of the transformer 200. The remaining four sides of the transformer 200 do not include panels in the preferred embodiment shown in
In general, of the four open sides A, B, C, D shown in
The upper and lower panels 210, 212 may be formed from sheets of material with a high thermal conductivity that will not disrupt the magnetic properties of the transformer, for example a non-magnetic metal could be used, such as aluminum or copper. In some preferred embodiments, alternative materials may be used for the upper panel 210, such as a non-metallic material. The connection terminals 206 for the primary coil and secondary coil may extend through the upper panel 210, to allow ease of access.
As can be seen from
The first set of thermally conductive sections 214 extend between the upper panel 210 and the lower panel 212 and are in thermal contact with the upper panel and lower panel. Each of the first set of thermally conductive sections 214 is also positioned in thermal contact with the transformer core 202 and the winding unit 204. The first set of thermally conductive sections 214 includes four thermally conductive sections located towards the four corners of the lower panel 212. In other words, two of the first set of thermally conductive sections 214 are located on one side of the winding unit 204, with the transformer core 202 positioned between those two thermally conductive sections 214, and the other two of the thermally conductive sections 214 are located on the opposing side of the winding unit 204, also on either side of the transformer core 202. Each of first set of thermally conductive sections 214 extend in a lengthwise direction parallel or substantially parallel within manufacturing and/or measurement tolerances to the winding axis of the winding unit 2014.
The second set of thermally conductive sections 216 are disposed between the upper panel 210 and the winding unit 204 and are in thermal contact with both the upper panel 210 and the winding unit 204. The second set of thermally conductive sections 216, as best seen in
The third set of thermally conductive sections 218 are disposed between the lower panel 212 and the winding unit 204, and in thermal contact with the lower panel 212 and the winding unit 204. The third set of thermally conductive sections 218 are located between the lower surface of the winding unit 204 and the upper surface of the lower panel 212. The third set of thermally conductive sections 218 includes two thermally conductive sections in the present preferred embodiment. Each of the third set of thermally conductive sections 218 extends in a lengthwise direction parallel or substantially parallel within manufacturing and/or measurement tolerances to the plane of the core layer in the transformer core 202, and perpendicular or substantially perpendicular within manufacturing and/or measurement tolerances to the winding axis of the winding unit 204. The third set of thermally conductive sections 218 are best seen in
Each of the plurality of thermally conductive sections 214, 216, 218 performs a number of functions.
First, the plurality of thermally conductive sections 214, 216, 218 retain the winding unit 204 within the housing 208 and prevent any movement of the winding unit 204 within the housing 208. All degrees of freedom of the winding (movement in any direction) is prevented by the plurality of thermally conductive sections 214, 216, 218.
Second, the plurality of thermally conductive sections 214, 216, 218 extract heat from the transformer core 202 and the winding unit 204. Each of the plurality of thermally conductive sections 214, 216, 218 is positioned in thermal contact with the transformer core 202 and/or the winding unit 204, depending on the specific preferred embodiment. In the preferred embodiment of
Heat from the transformer core 202 and the winding unit 204 is transferred to the plurality of thermally conductive sections 214, 216, 218 through conduction. This heat extracted by the plurality of thermally conductive sections 214, 216, 218 can be removed via various different cooling structures, which will be discussed later. The plurality of thermally conductive sections 214, 216, 218 therefore act as cooling channels within the housing 208.
The plurality of thermally conductive sections 214, 216, 218 provide effective removal of heat from the interior of the transformer 200e. This allows the correct temperature levels to be maintained inside the transformer 200, which prevents damage or failure of the transformer 200 from occurring.
Some or all of thermally conductive sections may be exposed as well as the winding unit 204, due to the one or more open sides. In the present preferred embodiment, the two open sides A, B that expose the winding unit 204 also expose a portion of each of the plurality of thermally conductive sections 214, 216, 218. This allows and airflow to reach the plurality of thermally conductive sections 214, 216, 218 to aid cooling, as will be discussed in more detail below. The two open sides C, D that expose the transformer core 202 also expose a portion of the first set of thermally conductive sections 214.
The plurality of thermally conductive sections 214, 216, 218 can be made from a material with a high thermal conductivity that will not disrupt the magnetic properties of the transformer, for example a non-magnetic metal could be used, such as aluminum or copper. Each of the plurality of thermally conductive sections 214, 216, 218 may be made out of the same material, or out of various different materials. Blocks of aluminum can be used as the plurality of thermally conductive sections 214, 216, 218, due to the lightweight properties of aluminum.
The housing 208 may be releasably secured together. In particular, some or all of the plurality of thermally conductive sections 214, 216, 218 may be releasably secured to the upper and/or lower panels 210, 212.
In the present preferred embodiment, each of the first set of thermally conductive sections 214 is releasably secured to the upper panel 210 at a first end of the thermally conductive section 214, and releasably secured to the lower panel 212 at a second end of the thermally conductive section 214. Each of the second set of thermally conductive sections 216 is releasably secured to the upper panel 210. Each of the third set of thermally conductive sections 218 is releasably secured to the lower panel 212.
In the present preferred embodiment, the plurality of thermally conductive sections 214, 216, 218 are releasably secured using screw attachments. This is shown in
The releasable connections between the upper and lower panels 210, 212 and the plurality of thermally conductive sections 214, 216, 218 mean that the transformer housing 208 can be easily dismantled and reassembled. This means that the configuration of the transformer housing 208 can be modified after installation, creating a more versatile transformer which may be applied to various different applications.
Optionally, the transformer 200 can include one or more additional thermally conductive sections 220, best seen in
The additional thermally conductive sections 220 perform a similar heat extraction function as the plurality of thermally conductive sections 214, 216, 218, and the description above for the plurality of thermally conductive sections 214, 216, 218 applies analogously. Namely, the additional thermally conductive sections 220 can be made from a material with a high thermal conductivity that will not disrupt the magnetic properties of the transformer. The additional thermally conductive sections 220 provide further improvements in the cooling of the transformer 202, as the additional thermally conductive sections 220 can extract heat from the most central portion of the transformer 200.
The additional thermally conductive sections 220 may also be attached to the upper panel 210 and/or lower panel 212 by a releasably securing structure, such as a screw. Alternatively, the additional thermally conductive sections 220 may be held in position by a gluing or a tight fit arrangement. Moreover, the additional thermally conductive sections 220 may be incorporated into the potting material of the winding unit 204 in some preferred embodiments, as discussed in more detail later.
The housing 208 may include gaps 222 between the one or more additional thermally conductive sections 220 and the second set of thermally conductive sections 216, as best seen in
The housing 208 may further include gaps 224 between the ends of each of the third set of thermally conductive sections 218 and the first set of thermally conductive sections 214. The gaps 224 also prevent eddy currents and shorting, similarly to the gaps 222. Due to the gaps 222 and gaps 224, an electrically conductive path round the perimeter of the transformer 200 through the plurality of thermally conductive sections 214, 216, 218 and the additional thermally conductive sections 220 is advantageously prevented.
In the preferred embodiment shown in
When the winding unit 254 is fitted into the housing 208, the pair of protrusions 260 extend between the winding unit 254 and the lower panel 212. The pair of protrusions 260 may be formed from the potting material. In other words, the potting material surrounding the coils within the winding unit 254 and the potting material forming the protrusions 260 may be formed as one integral piece (formed as a single unit).
In some preferred embodiments, the protrusions 260 may themselves be releasably secured to the lower panel 212, in a similar fashion to the plurality of thermally conductive sections 214, 216, 218, for example by screw fixings. The protrusions 260 may include aluminum blocks molded into the potting material, into which a screw or the like can engage to couple the protrusions 260 to the lower panel 212. This can provide a strong mechanical fixing, with all the possible degrees of freedom of movement of the winding unit 254 restricted.
In both preferred embodiments of the winding unit 204 and 254, the winding unit may be formed by injection molding, specifically insert molding or overmolding. The coils in the winding unit are positioned into a mold, such as a Teflon or silicone mold, and then the potting material is cast into the mold to encase the coils, and optionally form the protrusions 260. The mold is then removed to leave the integrally formed winding unit 204, 254. The mold may be formed of two halves which can be disconnected from each other after the molding process, to release the finished winding unit 204, 254. Other methods of forming the winding unit 204, 254 are also possible.
In further preferred embodiments, when the one or more additional thermally conductive sections 220 are included, the one or more additional thermally conductive sections 220 may be formed integrally with the winding unit 204, 254. In other words, the one or more additional thermally conductive sections 220 may also be positioned within the mold prior to the introduction of the potting material, such that portions of the one or more additional thermally conductive sections 220 may be incorporated into (encased in) the potting material in the completed winding unit 204, 254. The additional thermally conductive sections 220 will then be integral with the winding unit 204, 254.
In the case of the winding unit 204 of
Molding the winding unit together with the additional thermally conductive section 220 to form a single integral unit means that when the winding unit 204 is arranged around the transformer core 202, the additional thermally conductive sections 220 will be held securely against the central portion of the transformer core 202 by the potting material.
The above-described preferred embodiments provide a number of advantages. First, the hybrid semi-potted and open construction, where just the winding unit is potted and sides of the housing remain open, means that cooling air can reach the winding unit with ease. However, due to the potting material around the windings, the challenges associated with fully exposed windings, such as movement of the coils, insulation and vulnerability to damage, are negated.
Moreover, the reduction in the amount of potting material needed leads to a reduction in manufacturing costs, as well as a reduction in the weight of the device. For example, a typical dimension of the transformer 200 of the above preferred embodiments is about 200 mm by about 140 mm by about 110 mm within manufacturing and/or measurement tolerances. In transformers of this size, approximately 6 kg to approximately 7 kg of potting material can be removed due to the hybrid construction, compared to a comparably sized fully potted or enclosed transformer of the type shown in
In addition, the above-described construction, particularly the plurality of thermally conductive sections 214, 216, 218 mean that the winding unit 204, 254 is securely held in a fixed position with respect to the transformer core 202 and housing 208, with all degrees of freedom of movement restricted. This ensures optimal performance of the device, as well as increasing durability.
Furthermore, the releasable securing of the various components of the housing 208 mean that the transformer 200 can be readily dismantled and reassembled, leading to a transformer 200 that is modifiable after construction. For example, the winding unit 204, 254 used in the transformer 200 may be removed and replaced with a different winding unit configuration. Moreover, the transformer 200 can easily be modified between different cooling arrangements, as outlined in more detail below. Therefore, the transformer 200 of the preferred embodiments described above provides a adaptable yet compact construction.
As well as holding the housing 208, and fixing the winding unit 204 in place, the plurality of thermally conductive sections 214, 216, 218 act as cooling channels, along with additional thermally conductive sections 220, to create a thermal conduction circuit. The thermal conduction circuit allows heat to be removed from the windings and the transformer core 202. The positions of the thermally conductive sections 214, 216, 218 are selected such that they provide the most efficient heat conduction paths from the hottest areas of the transformer 200 during operation.
The transformer 200 can be optimized for water cooling arrangement. For example, the transformer 200 can be cold plate mounted to remove the heat extracted by the plurality of thermally conductive sections 214, 216, 218 and the additional thermally conductive sections 220.
In one preferred embodiment, the lower panel 212 may be mounted onto a cold plate, so as to be in thermal contact with the cold plate. In another preferred embodiment, the lower panel 212 may itself be a cold plate. A cold plate may also be referred to as a cooling plate, and is typically water cooled. Heat is able to flow through the plurality of thermally conductive sections 214, 216, 218 and the additional thermally conductive sections 220, into the lower panel 212, to be removed from the transformer 200.
Other cooling methods are possible. For example, alternatively to the cooling plate arrangement described above, or in addition to the cooling plate arrangement, in some preferred embodiments, one or more of the plurality of thermally conductive sections 214, 216, 218 may include radiating fins. The radiating fins increase the surface area of the plurality of thermally conductive sections 214, 216, 218. These radiating fins may be cooled by forced air cooling or natural air cooling, to remove heat from the plurality of thermally conductive sections 214, 216, 218 that has been extracted from the winding unit 204, 254 and/or transformer core 202. The open sides of the housing 208 allow the airflow to reach the plurality of thermally conductive sections 214, 216, 218 in order to cool the radiating fins.
Radiating fins may be included on the outer surfaces of any or all of the plurality of thermally conductive sections 214, 216, 218.
The releasably secured connection between the components of the housing 208, particularly the plurality of thermally conductive sections 214, 216, 218 and the upper and lower panels 210, 212, means that the transformer 200, 300 can be easily swapped between different cooling configurations, for example attaching to different cooling plates, or swapping out thermally conductive sections without radiating fins for thermally conductive sections with radiating fins as necessary. In other words, a simple change of the plurality of thermally conductive sections 214, 216, 218 and/or lower panel 212 mean that the transformer 200, 300 can be made suitable for various different forced air cooled, natural convention cooled or water cooled plate mounted constructions. This modification is easily performed, for example, using the screw fastenings described in
Typically, a cold plate will be used for transformers 200, 300 with a higher power, to provide active cooling of the transformer. Water cooled cold plates can therefore provide a considerable boost in the level of the power that can be derived from the transformer 200, 300 without overheating.
The transformer 200, 300 according to a preferred embodiment of the present invention is therefore compatible with almost all cooling techniques used in the industry for applications over various different power levels. The above-described transformer construction therefore provides a universal high-frequency transformer design that can be adapted to be used in almost all applications with a power rating in the range of about 50 kW to about 100 kW. Of course, the features of the preferred embodiments described above may also be applied to transformers with different power ratings.
Optionally, some or all of the plurality of thermally conductive sections 214, 216, 218 include at least one outer surface that is colored black. In some preferred embodiments, the entire surface of one or more of the thermally conductive sections 214, 216, 218 may be colored black. This coloring can lead to better heat radiation, and therefore improved cooling, due to the increase in black body radiation. In some preferred embodiments, the outer surfaces of the upper and lower panels 210, 212 may also be colored black.
In initial tests, coloring the thermally conductive sections 214, 216, 218 in a black color allowed the transformer to be used at approximately 5 kW higher power for the same temperature increase.
Returning to
The thermally conductive plate 228 is best seen in
The transformer core 602 including multiple core layers may optionally include one or more secondary thermally conductive plates 628 disposed between the core layers, as shown in
The thermally conductive plates 228, 628 are positioned in planes which are parallel or substantially parallel within manufacturing and/or measurement tolerances to the magnetic field inside the transformer core 202, 602, so as to have no effect on the magnetic circuit. The thermally conductive plates 228, 628 can be made from a material with a high thermal conductivity that will not disrupt the magnetic properties of the transformer, such as aluminum. For example, a non-magnetic metal could be used, such as aluminum or copper.
Of course, in general various transformer core constructions may be used, with any number of core layers being included, and different combinations of the thermally conductive plates 228, 628.
A number of different windings arrangements according to preferred embodiments of the present invention will now be described. Each of the winding arrangements described below could be used in the winding units 204, 254 of any of the preferred embodiments of the transformers 200, 300 described above. Alternatively, the winding arrangements described below could also be used in any other type of electrical transformer.
The winding arrangement 700 includes a primary coil 702 and a secondary coil 704. The primary coil 702 includes a first section 710 and a second section 720. The first section 710 is shown in isolation in
The first section 710 of the primary coil 702 includes a first set of turns 712 including a first diameter and a second set 714 of turns including a second diameter. The first set of turns 712 and second set of turns 714 are wound around a common winding axis, and each set of turns may include one or more individual turns. The first diameter is larger than the second diameter, such that when viewed along the common winding axis, the first and second set of turns are concentric with the second set of turns 714 located inside the diameter of the first set of turns 712.
The first section 710 is formed from a single integral piece of wire, to form a continuous electrically conductive path. In other words, a final turn of the first set of turns 712 is connected to a first turn of the second set of turns 714, as shown in
Similarly, the second section 720 of the primary coil 702 includes a first set of turns 722 including a first diameter and a second set 724 of turns including a second diameter smaller than the first diameter, with each set of turns including one or more individual turns and being arranged concentrically around a common winding axis. The first and second diameters of the second section 720 are the same as those for the first section 710. The first set of turns 722 and the second set of turns 724 of the second section 720 are also formed from a continuous piece of wire.
The first section 710 and second section 720 of the primary coil are electrically connected in parallel to form the primary coil 702. This electrical connection may be made via connecting or joining the connection terminals 716, 726 of each of the first and second sections 710, 720. In particular, the connection terminal 716 at a first end of the first section 710 and the connection terminal 726 at a first end of the second section 720 can be connected together, and the connection terminal 716 at a second end of the first section 710 and the connection terminal 726 at a second end of the second section 720 can be connected together.
In the primary coil 702, the second set of turns 724 of the second section 720 are positioned within the first set of turns 712 of the first section 710, and the second set of turns 714 of the first section 710 are positioned within the first set of turns 722 of the second section 720, when viewed along the common winding axis. By “positioned within” it is meant that the second set of turns 724 of the second section 720 are inside the first set of turns 712 of the first section 710, with both the second set of turns 724 and the first set of turns 712 located within the same plane extending perpendicularly or substantially perpendicular within manufacturing and/or measurement tolerances to the common winding axis. Similarly, the second set of turns 714 of the first section 710 are positioned within the first set of turns 722 of the second section 720 such that the second set of turns 714 are located inside the first set of turns 722 and both are located within the same plane extending perpendicularly or substantially perpendicularly within manufacturing and/or measurement tolerances to the common winding axis.
The first set of turns 712 of the first section 710 and the first set of turns 722 of the second section 720 fully overlap when viewed along the common winding axis, and the second set of turns 714 of the first section 710 and the second set of turns 724 of the second section 720 fully overlap when viewed along the common winding axis. In other words, the first and section seconds 710, 720 include the same footprint.
As well as the primary coil 702 described above, the winding arrangement 700 of
The winding arrangement 700 including both the primary and secondary coils 702, 704 is formed by interleaving the turns of the primary coil 702 with the turns of the secondary coil 704. The primary and secondary coils 702, 704 are interleaved such that each turn of the primary coil 702 (each turn of the first and second sets of turns 712, 714, 722, 724 of both the first and second sections 710, 720 of the primary coil 702) is positioned between two turns of the secondary coil 704 when viewed along a direction perpendicular to the common winding axis. Similarly, each turn of the secondary coil 704 is positioned between two turns of the primary coil when viewed along a direction perpendicular to the common winding axis. Put another way, each turn of the secondary coil 704 includes turns of the primary coil 702 located above and below the secondary coil turn.
In other words, along the direction of the common winding axis, the turns in the winding arrangement 700 alternate between the primary coil 702 and the secondary coil 704. Specifically, the turns of the first sets of turns 712, 722 of the primary coil 702 and the turns of the first sets of turns of the secondary coil 704 alternate along the common winding axis, and the turns of the second sets of turns 714, 724 of the primary coil 702 and the turns of the second sets of turns of the secondary coil 704 alternate along the common winding axis.
The interleaving of the primary and secondary coils 702, 704 is shown in
Due to the above-described interleaving of the primary and secondary coils 702, 704, sections of the coils 702, 704 carrying currents in the same direction are not disposed directly adjacent to each other. This has the advantageous effect of reducing the losses caused by the proximity effect.
Moreover, the winding arrangement 700 is able to handle high currents due to the primary and secondary coils 702, 704 being formed from the two sections 710, 720 connected in parallel. This is because each section of each coil will only receive half the input current due to the parallel connection of the two sections. In some preferred embodiments the current level may be as high as approximately 1200 A. A winding arrangement suitable for low-current applications will be discussed in relation to
For each of the primary coil 702 and the secondary coil 704 in the winding arrangement 700, the number of turns in the first set of turns 712, 722 of each of the first and second sections 710, 720 of that coil are equal, and the number of turns in the second sets of turns 714, 724 of each of the first and second sections 710, 720 of that coil are equal. In other words, for a given coil 702, 704, the first section 710 and second section 720 both include the same number of turns in their respective first set of turns 712, 722, and the first section 710 and second section 720 both include the same number of turns in their respective second set of turns 714, 724.
Therefore, the first section 710 of each coil 702, 704 is identical to the second section 720 of that coil, other than the folding direction of the connection terminals 716, 726 (best seen from a comparison of
In some preferred embodiments, within each coil section 710, 720 there may be more turns in the first set of turns 712, 722 than in the second set of turns 714,274. For example, in the present preferred embodiment, as shown in
Returning to
In addition, in the preferred embodiment of the winding arrangement 700 shown in
The above-described folding configuration of the connection terminals 716, 726 has the advantage that each point of connection to the primary and secondary coils 702, 704 can be located on the same side of a transformer 200 including the winding arrangement. This is shown in the transformer 200 of
In alternative preferred embodiments, other folding configurations are possible for the connection terminals 716, 726. For example, the connection terminals 716, 726 could be folded in different directions to each other. For example, in one preferred embodiment, one or more of the connection terminals 716, 726 may be folded so as to extend along the common winding axis in one direction, and the remaining connection terminals 716, 726 may be folded so as to extend along the common winding axis in the opposing direction. In some preferred embodiments, the connection terminals 716, 726 could differ for each of the primary and secondary coils 702, 704. For example, the direction of extension of the connection terminals 716, 726 for the primary coil 702 may be in a different direction, for example, an opposing direction, to the extension of the connection terminals 716, 726 for the secondary coil 704. In some preferred embodiments, the connection terminals 716, 726 may extend along a direction other than the direction of the common winding axis. The folding configuration and direction of the connection terminals 716, 726 is chosen to locate the connection points to the coils 702, 704 at the desired position when the winding arrangement is used in a transformer device.
In the winding arrangement 700 of
Put another way, the winding arrangement 700 of
In an alternative preferred embodiment, the connection terminals 716, 726 of the primary and secondary coils 702, 704 may be located on the same side of the winding arrangement. In other words, the winding arrangement may be formed using two of the coils 702, 704 shown in
In general, the turns of each of the coils 702, 704 in the winding arrangement 700 have a square shape about the winding axis. However a rectangular square, or circular shape, or various other shapes may also be used.
Each set of turns of each coil 702, 704 is arranged (wound) helically around the common winding axis. In other words, each coil 702, 704 is formed from a first helically wound first section 710 connected in parallel with a second helically wound second section 720.
When the winding arrangement 700 of
The winding arrangement of preferred embodiments of the present invention may also be used in applications with multiple secondary coils.
Each of the secondary coils 802, 804 include a first section 810 and a second section 820 connected in parallel and wound together around a common winding axis, in a similar manner to the primary coil 702.
The first section 810 of the secondary coils 802, 804 includes a first of turns 812 including a first diameter and a second set 814 of turns including a second diameter smaller than the first diameter, and the second section 820 of the secondary coils 802, 804 includes a first of turns 822 including a first diameter and a second set 824 of turns including a second diameter smaller than the first diameter.
A first section 810 as shown in
In other words, the first section 810 and a second section 820 of the secondary coils 802, 804 are analogous to the first and second sections 710, 720 described above. The other features described above for the primary coil 702 apply analogously to the secondary coil 802 and additional secondary coil 804 and will therefore not be repeated here.
As shown in
The connection terminals 816, 826 of the secondary coils are folded so as to extend in a direction parallel or substantially parallel within manufacturing and/or measurement tolerances to the direction of the common winding axis, in this case in the same direction as the connection terminals 716, 726 of the primary coil 702 when the secondary coils 802, 804 are combined with the primary coil 702 (as shown in
To form the complete winding arrangement 800 shown in
In the present preferred embodiment, the primary coil 702 is interleaved with the secondary coils 802, 804 such that each turn of the secondary coil 802 is disposed between two turns of the primary coil 702 and each turn of the additional secondary coil 804 is disposed between two turns of the primary coil 702, when viewed along a direction perpendicular to the common winding axis. Therefore, each turn of each secondary coil 802, 804 has turns of the primary coil 702 located above and below the secondary coil turn. Once interleaved, each of the primary coil 702, secondary coil 802, and additional secondary coil 804 fully overlap when viewed along the common winding axis.
In the present preferred embodiment, the secondary coils 802 and 804 are stacked one on top of the other. This means that the secondary coil 802 interleaves with the primary coil 702 in a first portion of the primary coil 702 (the upper portion of the primary coil 702 in
In an alternative preferred embodiment, the secondary coil 802 and additional secondary coil 804 could interleave with each other as well as the primary coil 702. This will be described in more detail in relation to
The interleaving of the primary coil 702 with the secondary coils 802, 804 again reduces the proximity effect by ensuring conductors carrying like currents are not positioned against each other.
Moreover, similarly to the primary coil, each secondary coil is formed by two coil sections in parallel. In other words,
In further preferred embodiments, more than two secondary coils may be used. In other words, the winding arrangement may include more than one additional secondary coil.
The secondary coils 1002, 1004, 1006, 1008 of
However, the preferred embodiment of
The secondary coil arrangement 1000 of
Of course, other numbers of secondary coils may be used. In general, up to twenty secondary coils, or up to ten secondary coils may be used.
The shape of the primary and secondary coils in the above mentioned preferred embodiments provides flexibility to accommodate multiple secondary coils within the same footprint and volume. The coils of the winding arrangement stack around the common winding axis to provide a very compact arrangement, while also preventing proximity effect losses.
Including multiple secondary coils in the winding arrangement provides a number of benefits, including the ability to power multiple circuits, as well as providing redundancy.
In general, when multiple secondary coils are used, the number of turns in the primary coil 702 is greater than or equal to the combined total number of turns in the secondary coils (the secondary coil and the one or more additional secondary coils). For example, when using a primary coil 702 with ten turns in each coil section (for example, five turns in the first set of turns of each coil section, and five turns in the second set of turns in each coil section), a single secondary coil with up to ten turns in each coil section may be used, or two secondary coils with up to five turns in each coil section each may be used, or five secondary coils with two turns in each coil section each may be used. It is also possible, however, for the primary coil to include fewer turns than the combined total number of turns in the secondary coils in some preferred embodiments.
Each of the above-described preferred embodiments uses secondary coils with two sections connected in parallel, for higher current applications.
Put another way, each secondary coil 1102, 1104 in
In
The two secondary coils 1102, 1104 are both wound around a common winding axis. The secondary coils 1102 and 1104 are stacked such that the secondary coils fully overlap when viewed along the common winding axis.
The secondary coils 1102, 1104 of
As before, more than two secondary coils may be used. Up to twenty secondary coils, or up to ten secondary coils may be used.
Regardless of the number of secondary coils, due to the construction of the secondary coils, they can be neatly stacked together to form a more compact winding arrangement. The stacking arrangement in one preferred embodiment of the present invention including ten secondary coils (the preferred embodiment of
As in the previous preferred embodiments, the number of turns in the primary coil may be greater than or equal to the combined total number of turns in the plurality of secondary coils.
In general, various numbers of turns and various numbers of secondary coils may be used. In a specific preferred embodiment, the secondary coil arrangement 1260 shown in
The number or turns shown in the drawings and given as examples in the description above are for exemplary purposes only. In general, in each preferred embodiment various different numbers of turns may be used in each coil.
In some preferred embodiments, the high current secondary coils of
Any of the above-described winding arrangements may be used with the hybrid construction transformer described in relation to
Moreover, the above-described winding arrangements may be used in combination with the cooling plate arrangement described in UK patent application publication GB2597470A and international patent application publication WO 2022/018436 A1, which are hereby incorporated by reference in their entirety.
The winding arrangements of each of the preferred embodiments described above are formed from flat wire. However, in some preferred embodiments other types of wire may also be used, such as round wire windings or the like.
The wire used in the winding arrangements of each of the preferred embodiments may be formed from various electrically conductive materials, such as copper or the like. However, in a preferred embodiment of the present invention, the wire used in the winding arrangement is formed from aluminum, as outlined below.
Traditionally, copper litz wires and copper foils are used in high frequency transformers. Murata's pdqb type windings (UK patent application publication GB2574481A and international patent application publication WO 2019/234453 A1) made it possible to use flat copper conductors in high-power, high-frequency transformers. In the preferred embodiment of the present invention aluminum wires, including, for example, aluminum flat wires, are used. Aluminum has not previously been used as a conductor in the windings of high-frequency, high-power transformers.
The use of aluminum as the conductive material in the windings has a number of benefits, particularly in larger high frequency transformers, which are becoming more prevalent due to new applications such as use in electric vehicles. First, aluminum has a lower density than traditional conductors such as cooper, and therefore leads to weight savings. Moreover, aluminum is cheaper than traditional conductors such as copper, leading to a lower manufacturing cost.
Second, carefully selected design parameters can be used with the aluminum windings to provide further benefits. The size of the thickness of the wire conductor is selected to be thicker than twice the skin depth of aluminum. This slight oversizing of the aluminum conductor means that there is an unused area within the center of the aluminum conductor (unused in the sense that it contains a very low or zero current density).
Therefore, a central volume with a very low or zero current density runs along the entire length of the aluminum conductor. This central volume acts as a cooling channel running through the aluminum conductor itself, to allow heat generated within the aluminum conductor to travel along and eventually out of the aluminum conductor. In other words, the size of the aluminum conductor is chosen to make a positive use of the skin depth and proximity effect in the aluminum conductor.
In a particular preferred embodiment, the flat wire has a width of between about 10 mm and about 15 mm within manufacturing and/or measurement tolerances, and a thickness of between about 0.8 mm and about 1.2 mm within manufacturing and/or measurement tolerances. The thickness of the flat wire can be about 1 mm within manufacturing and/or measurement tolerances. The width and thickness directions are the directions perpendicular or substantially perpendicular within manufacturing and/or measurement tolerances to the direction of the extension of the wire, i.e. perpendicular or substantially perpendicular within manufacturing and/or measurement tolerances to the direction the current flows in. The width direction is the larger dimension of the wire perpendicular to the extension of the wire, and the thickness direction is the smaller dimension of the wire perpendicular to the extension of the wire.
In a first preferred embodiment, the flat wire has a width of 15±2 mm within manufacturing and/or measurement tolerances and a thickness of 1.0±0.2 mm within manufacturing and/or measurement tolerances. In a second preferred embodiment, the flat wire has a width of 10±2 mm within manufacturing and/or measurement tolerances, and a thickness of 1.0±0.2 mm within manufacturing and/or measurement tolerances.
The dimensions of the flat wire above may be used with any conductive material, such as copper. However, the dimensions above are specifically tailored to achieve the maximal beneficial effects, such as the cooling benefit, when aluminum is used as the conductive material.
In some preferred embodiments a mix of conductive materials may be used, for example different conductive materials may be used in each of the primary and secondary coils.
The hybrid transformer construction of
Moreover, in each of the preferred embodiments described above, where multiple secondary coils are used, when the winding arrangement is used in a transformer two or more of the secondary coils may be connected together in series, or may be connected together in parallel, or may be connected together using a combination of series and parallel connections. For example, the two secondary coils 802, 804 shown in
By modifying the series and parallel connections between the secondary coils (when multiple secondary coils are present in the winding arrangement), the transformer can be adjusted to be used over a larger voltage and frequency ranges. For example, in some preferred embodiments, a transformer using the winding arrangements with multiple secondary coils as described above can be used in the voltage range of about 100 V to about 1100 V, and the frequency range of about 5 kHz to about 120 kHz. In other words, modifying the series and parallel connections of the secondary coils allows the winding arrangement to be swapped between a high-current, low-voltage situation or a low-current, high-voltage situation, depending on the series and/or parallel connections made between the secondary coils. Therefore, only minor adjustments to these series and parallel connections can make the transformer universal over the desired power level, for example approximately 50 kW to approximately 100 kW.
Previous attempts to provide a universal transformer have included using different core sizes and/or core assemblies to make the transformer suitable for different voltage and frequency levels. This is not necessary with the above-described hybrid transformer construction and winding arrangements.
In general, the above-described concepts and preferred embodiments may be applied to all high-power, high-frequency transformers including those with higher or lower power ratings than about 50 kW. Moreover, the concepts described herein could also be used in high-power inductors or the like.
In use in a transformer, the connection terminals of the primary coil of the winding arrangements described above act as input terminals for an alternating current (AC) voltage source. This will result in an AC voltage being produced at the connection terminals of the one or more secondary coil(s). In other words, the connection terminals of the one or more secondary coil(s) act as output terminals. A load may be connected across the output terminals. In some preferred embodiments, by varying the number of turns in each coil, a step-up or step-down in voltage can be achieved.
A transformer according to preferred embodiments of the present invention may be used individually or as a bank of connected or unconnected transformers. Transformers according to preferred embodiments of the present invention may be used in various applications, such as use in a vehicle, for example in a regenerative braking system, or in power generation equipment, particularly in renewable energy systems, or in DC-DC converters, power inverters, radio-frequency electronic equipment, or in miniature scale transformers. It is noted that this list is not intended to be exhaustive, and that other applications are also contemplated.
While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2206600.5 | May 2022 | GB | national |
