AXIAL FLUX BRUSHLESS SYNCHRONOUS MOTOR, CRYOGENIC SYSTEM INCLUDING THE MOTOR AND RELATED METHOD OF OPERATION OF THE SYSTEM.

Description

DESCRIPTION Attached to a patent application for an INDUSTRIAL INVENTION having by title “SYNCHRONOUS AND BRUSHLESS AXIAL FLUX MOTOR, CRYOGENIC SYSTEM INCLUDING THE ENGINE AND RELATED “METHOD OF OPERATION OF THE SYSTEM” On behalf of: ENERGY TECHNOLOGY SRL SOLIDARITY STREET 2 / 1, CRESPELLANO VILLAGE 40056 VALSAMOGGIA BO ******* The present invention relates to the technical field of electric motors, in particularly that of synchronous, brushless and axial flux motors. The present invention relates to a synchronous and frictionless motor. axial flow brushes, a cryogenic system comprising the 5 the aforementioned engine and a method of operation of the cryogenic plant same. The axial flux synchronous motor sector has been representing for some years an interesting solution in the automotive industrial sector, marine propulsion and electric vehicles. 10 In fact, it is known that electric machines in the flow configuration Axial and permanent magnets typically provide higher torque for a given motor volume compared to a flux synchronous machine radial since the area of ​​the active magnetic surface is the rotor face of the engine rather than the outside diameter. 15 The useful surfaces for the production of torque, in fact, or rather the surfaces where the conductors and permanent magnets are arranged, they are therefore perpendicular to the axis of the machine. If in the radial flow machine the torque-diameter relationship goes with the second power, in the axial flux machine this relationship goes with the 20 third power. Why it is known as axial flux motors vs. a motor radial engines of equal power are much more compact and lighter with a higher power and torque density. Axial flux electric motors also have an external appearance 5 different from radial flux motors; with the same torque developed, the Axial flux motors have a larger diameter but smaller width, with a reduced axial bulk. It is known that, if in radial flow machines most of the windings is not active, in axial flux motors 100% 10 of the winding is active with significant benefits from the point of view of the power-to-weight ratio. It is also known that copper windings and / or permanent magnets if made using superconducting materials allow to increase the electric current density in the windings and the flux density 15 magnetic inductor to the air gap, keeping the losses to zero excitation and eliminating problems due to the flow outflow, i.e. the loss of magnetic flux. Superconductors, in fact, are characterized by a high current density and from zero electrical resistance to the passage of a DC current and, therefore, 20 from the absence of losses due to the Joule effect. This results in a reduction of the weight of the windings, in a reduction of the section and an increase of the efficiency at any speed. In this context, the technical task underlying the present invention is to propose a synchronous and brushless axial flux motor that 25 overcomes the above-mentioned drawbacks. In particular, it is the purpose of the present invention to make available a highly advanced and eco-friendly brushless electric motor in terms of energy efficiency. A further aim of the present invention is therefore to 30 to provide an extremely compact and lightweight engine. A further aim of the present invention is therefore to to provide an engine with high efficiency, therefore, a higher power and torque density than a radial engine equal power. The present invention also relates to a cryogenic plant for cooling a cryogenic fluid passing through a cryostat. The present invention also relates to a method of operation of a cryogenic plant. The technical task and the specified purposes are substantially achieved by a synchronous and brushless electric motor, a cryogenic system and a method of operating a cryogenic plant comprising the technical characteristics set out in one or more of the attached claims. Further features and advantages of the present invention will appear. made clearer by the indicative, and therefore non-limiting, description, of some preferred but not exclusive embodiments of an engine brushless electric, as illustrated in the attached drawings where: - Figure 1 shows a perspective view of the engine under investigation. present invention; - Figure 2 shows a first cross-section of the engine in question. of the present invention; - Figure 3 shows a perspective view of the rotor discs, with their respective permanent magnets, of the motor illustrated in the previous figures 1 and 2 and subject of the present invention; - Figure 4 shows a schematic view of the stator yoke of the motor subject of the present invention; - Figure 5 shows a schematic view of the stator crown, with the wound superconducting coils (HTS coils), the subject of this invention; - Figure 6 shows a schematic view of a superconducting coil (HTS coil) of the engine subject of the present invention; - Figure 7 shows a schematic view of a section of the engine subject of the present invention. Figure 1 shows the cross-section of an electric motor. synchronous and brushless axial flux in accordance with this invention which for simplicity of description will be referred to below as engine 1. In particular, as illustrated in Figures 1-5, the present invention is refers to an engine 1 that has at least: - a rotor defined by a first rotor disk 2; - a first plurality of anchored (i.e. fixed in use) permanent magnets 3 mechanically to the first rotor disc 2; and - a stator defined by a stator crown 4 comprising a 5 plurality of ferromagnetic nuclei 5 and a plurality of cross-sections of winding and a respective plurality of supporting structures 6 defining containment sites for ferromagnetic cores 5. Note that the sections are wrapped around the support structures 6 of the winding. 10 Each section of the winding defines a plurality of coils 7 made of superconductive material (HTS - High Temperature coils) \Superconductor). According to one aspect of the invention, the engine 1 also comprises a second rotor disk 8 and a second plurality of permanent magnets 15 9 anchored (i.e. fixed in use) to the second rotor disc 8. Both the first rotor disc 2 and the second rotor disc 8 rest each on bearings, fitted between the cryostat itself and the rotor discs (2,8). Permanent magnets 3 and 9 include rare earth synthesis magnets, 20 in particular Neodymium-Iron-Boron (NdFeB) magnets. Magnets made from NFB alloy are among the strongest magnets of permanent high resistance to demagnetization in the market of sintered rare earth magnets. In accordance with an embodiment shown in figure 3 the first plurality 25 of permanent magnets 3 faces the second plurality of magnets permanent 9. The first plurality of permanent magnets 3 of the first rotor disk 2 and the second plurality of permanent magnets 9 of the second rotor disk 8 can be arranged with each other so that a North pole of one 5 permanent magnet of the first rotor disk 2 faces one pole South of a permanent magnet of the second rotor disk 8, and, furthermore in so that a south pole of a permanent magnet of the first rotor disk 2 is facing a North pole of a second permanent magnet rotor disc 8. 10 In accordance with the same embodiment on the first rotor disc 2 and on the second rotor disk 8, according to an exemplary and non-explanatory aspect limiting, twelve permanent magnets are placed. Furthermore, both the first rotor disc 2 and the second rotor disc 8 are keyed on the same “Z” axis and rotate at the same speed (figure 3) and 15 constitute the excitation (or “field”) winding. According to another aspect, the stator crown 4 comprises a plurality of support structures 6, in each of which a first location 6a is defined and a second seat 6b (clearly visible in figure 4). Each seat (6a, 6b) is configured to partially contain a 20 ferromagnetic nucleus 5. In other words, such support structures 6 are defined to contain partially a ferromagnetic core 5 and constitute the stator yoke which is crossed in the axial direction (parallel to the “Z” axis) by the lines of force of the magnetic field produced by permanent magnets 3 and 9. 25 According to an embodiment shown in figure 5 the stator crown 4 is It presents a structure with cavities and teeth so as to make the engine 1 magnetically anisotropic. According to the same embodiment, the ferromagnetic cores 5 are considered as the teeth of the stator crown 4. 30 In one aspect, ferromagnetic cores 5 are made of laminations ferromagnetic in order to reduce the losses due to the Joule effect due to the currents induced in them. From another point of view, the arrangement of the 7 coils was chosen in based on the cave star theory. Each ferromagnetic core 5 is inserted into the first and / or second 5 location of structure 6a and / or 6b. Each ferromagnetic core 5 also has two ends 5a and 5b (clearly visible in figure 5) each facing the first plurality of magnets permanent 3 of the respective first rotor disc 2 and / or to the second plurality of permanent magnets 9 of the second rotor disc 8. 10 In other words, within the first and / or second location of the structure 6a and / or 6b is placed a core of ferromagnetic material 5, also trapezoidal in shape which has two plates at the ends 5a and 5b ferromagnetic material 5. The stator yoke also features a plate-like element 10 15 appropriately shaped and preferably made of steel. The HTS tape of each reel 7 is wound onto this element 10 metal plate, after electrical insulation, as a title exemplary and not limiting, to be made using kapton or paint insulation applied to element 10 itself. 20 With reference to figure 6, each coil 7 comprises a first portion 7a and a second portion 7b. The first portion 7a is inserted into the use in the first seat 6a of the structure of support 6 while the second portion 7b is inserted in use in the second seat 6b of support structure 6. 25 According to one embodiment, each coil 7 is configured to define a double pancake configuration. As shown in figures 6 and 7, the first portion 7a of the coil 7 and the second portion 7b of coil 7 are defined by a single HTS tape, in particular the first portion 7a of the coil 7 is defined by a 30 portion of HTS tape wound from the outside to the inside of the reel 7 and the second portion 7b of the coil 7 is defined by a portion of the HTS tape wound from the inside to the outside of the reel 7. In other words, an HTS tape is used to wrap each reel 7 in a double pancake configuration. The double pancake configuration consists of two windings at 5 pancakes, arranged parallel to each other, with ribbon HTS that passes continuously from one section of the winding to another. Each pancake consists of a single layer of N turns isolated from each other and concentric. The peculiarity of this configuration lies in the fact that the first portion 7a 10 of coil 7 is wound from the outside to the inside, while the second portion 7b of coil 7 is wound from the inside out. In this way, the two terminals of coil 7 are both on the outside and therefore easily reachable. The engine 1 further comprises a cryostat 11 configured for 15 define a circulation conduit for a cryogenic fluid. This cryostat it develops around an external perimeter of the stator 4 and is configured to affect each coil 7 of the plurality of coils 7. In other words, the 7 superconducting coils that make up the armature of the engine must be entered in a suitable cryostat 11. 20 Both the first rotor disc 2 and the second rotor disc 8 rest on bearings stuck in cryostat 11. The cryostat 11 has an inlet opening 12 and an outlet opening 13 to allow the fluid to be infused and extracted respectively cryogenic in the circulation duct. 25 It should also be noted that the cryostat 11 is configured to accommodate in the circulation duct coils 7. In other words, the cryostat 11 can be shaped like a vessel. Inside this vessel a suitable cryogenic fluid, for example nitrogen is flowed to maintain the temperature of 30 operation (Top) of the 7 coils below a critical temperature (T ). c The value of the critical temperature T is characteristic of the material, that is c of the HTS tape used for each reel. The critical temperature Tc is the temperature beyond which the superconductive material from which the coils (7) are made loses its 5 superconductive characteristic and returns to being a ceramic material insulating. In other words, a cryocooler (i.e. a cryogenic refrigerator) is designed to provide all the cooling power needed to dispose of that is, remove the heat associated with the losses of each coil 7 and 10 maintain the Top operating temperature at the preset value. The HTS tape with which the 7 coils are made, in fact, when working in magnetic field / alternating current regime (as in the case of the armature of a synchronous machine), becomes the site of electrical losses called AC-Loss. 15 The increase in the Top operating temperature determines a reduction of energy costs for operating the system. In fact, with the same mechanical power of the compressor and therefore of energy consumption, the cooling power of a cryocooler is highly dependent on the temperature at which it is produced. 20 To limit the thermal load associated with AC losses (i.e. AC-Loss) of the coils 7, and thus dispose of only the heat associated with these losses, according to one aspect of the present invention the core ferromagnetic 5 of each coil 7 is arranged outside the cryostat 11. In this way, even if separated by a few millimetres, coil 7 and the 25 respective ferromagnetic core 5 will work at different temperatures: 40 / 50 K and 300K, respectively. According to a further aspect the cryostat 11 defines a vacuum chamber 40 (inside which to create a vacuum) to ensure that the temperature difference between the internal and external environment 30 kept constant and the heat exchange between the two environments (inside and outside the room) you know at least. The cryostat 11 therefore defines a support structure for the motor 1, a confinement chamber for each ferromagnetic core 5 and another vacuum chamber 40 (visible in figure 2). To create a vacuum inside the vacuum chamber 40, the cryostat 11 5 has a conduit 20 connected to a valve (which, in turn, in use it can be connected to a vacuum pump to extract the air from inside of the vacuum chamber 40 creating the vacuum). In one aspect, the walls of cryostat 11 are polished (to reduce radiation). 10 From another perspective, the only points where there is no void inside the cryostat 11 of the engine 1 which is the subject of the present invention they were made in minimal dimensions. According to an embodiment shown in figure 7 since the cores of ferromagnetic material 5 perform the function of conveying the lines of 15 magnetic field strength and maintain high flux density value magnetic concatenated with the coils 7, despite the presence of the cryostat 11, it is possible to identify a mechanical air gap “M” and an air gap electromagnetic “E”. The mechanical air gap “M” is the space existing between the end of the core 20 ferromagnetic (e.g. the upper end 5a) and a magnet permanent (for example of the first plurality of permanent magnets 3). Preferably, according to one aspect, the mechanical air gap “M” is included between 0.2 mm and 1 mm; even more preferably between 0.5 mm and 0.85 mm. This mechanical air gap “M” is measured along the “Z” axis between the plate 25 ferromagnetic material 5a and the edge of a permanent magnet 3. The electromagnetic air gap “E” is, instead, the space existing between the edge of each coil 7 and the edge of each permanent magnet 3 of the first rotor disc 2 or second rotor disc 8: the mean circumference of the electromagnetic air gap “E” is taken as a reference for the estimation of the 30 electrical and magnetic quantities for sizing purposes. In addition, according to the embodiment shown in figure 7, the mechanical air gap “M” has a lower value than the air gap electromagnetic “E”. According to one aspect of the present invention, the cryostat 11 comprises at least one sensor configured to monitor a magnetic field 5 generated by each coil 7, and / or an operating temperature of each coil 7 and / or a current through each coil 7. Engine 1 also includes a control unit (not shown) to which is associated with at least one sensor and configured to regulate a flow in use of the cryogenic fluid in the circulation duct as a function of a field 10 magnetic, and / or a temperature and / or a current measured by the sensor. Preferably, the engine 1 comprises at least one control valve of the flow of the cryogenic fluid in the circulation duct as a function of a magnetic field, and / or a temperature and / or a current measured by the sensor. 15 According to this aspect, the control unit is connected to the valve for regulate its opening, and thus regulate the flow of fluid accordingly cryogenic in the circulation duct. According to the invention, a cryogenic plant is also defined comprising a motor 1 and a fluid inlet circuit 20 cryogenic (preferably cryogenic fluid) in the circulation line. In particular, a cryogenic fluid injection circuit is connected to the inlet opening 12 and the outlet opening 13 of the cryostat 11 of the engine 1. Engine 1 is in use configured to convey part of its power to drive the compressor which transfers power to the cryostat 25 11 so as to generate a flow of the cryogenic fluid between the opening of inlet 12 and outlet opening 13 of cryostat 11. In other words, engine 1 is in use configured to transfer power produced by the compressor which supplies the same to the cryostat 11 for move the cryogenic fluid inside the circulation duct, 30 therefore, to ensure that the coils 7 are kept at their temperature operating temperature T , without exceeding the critical temperature T . op c In fact, the three input ducts 14, 15 and 16 are also fixed to the stator. for electrical cables, in particular one for each of the three phases. Therefore, each coil 7 works in AC mode and is monitored so that the field magnetic, temperature and current do not exceed critical values. 5 The present invention also includes a method of operation of a cryogenic plant including the phases of feed the cryogenic plant with cryogenic fluid at a temperature default, convey the power generated by motor 1 to the duct of circulation to generate a flow of the cryogenic fluid between the opening of 10 inlet 12 and outlet opening 13 of the cryostat 11 and finally cool the coils 7 by means of the cryogenic fluid passing through the duct circulation, in particular from the inlet opening 12 to the outlet opening 13 of the cryostat 11. It should be noted that, according to the invention, the engine 1 could be 15 applied in various industrial sectors such as automotive, propulsion marina and electric vehicles. Furthermore, advantageously, the engine 1 can be applied to the cryogenic plant compressor, to operate it. Advantageously, the engine 1 according to the present invention allows 20 to overcome the aforementioned defects present in the prior art. Advantageously, a 1 motor with an energy efficiency is provided very high (around 99%), highly advanced and environmentally friendly in terms of energy efficiency. In other words, the engine 1 which is the subject of the present invention is compliant 25 to the IE4 regulation on energy efficiency. Advantageously, the 1-engine is much more compact and lighter than the as can be found in the known art, in fact, currently an electric motor conventional type with a power of 500 kW weighs 330 kg while the engine 1 which is the subject of the present invention has a weight of 30 kg, a 30 external diameter of approximately 250 mm and a thickness of approximately 100 mm. In particular, the compactness and lightness of the engine 1 is achieved through an optimised use of the materials and components used to create its internal structure. This feature allows the use of engine 1 also on airplanes. THE AGENCY Eng. Simone Milli (Registered no. 1517 BM)

Claims

1. Axial flux synchronous brushless motor (1) having at least: - a rotor defined by a first rotor disc (2); - a first plurality of permanent magnets (3) mechanically anchored to the first rotor disc (2); - a stator defined by a stator crown (4) comprising a plurality of ferromagnetic cores (5) and a plurality of winding sections and a respective plurality of support structures (6) defining containment seats for said ferromagnetic cores (5) and support seats for the aforementioned winding sections; each winding section defines a plurality of coils (7) made of superconductive material (HTS coils);said engine (1) being characterised by further comprising a cryostat (11) configured to define a circulation conduit for a cryogenic fluid, said cryostat (11) extending around an external perimeter of said stator and configured to affect each coil (7) of said plurality of coils (7), the cryostat (11) having an inlet opening (12) and an outlet opening (13) to permit respectively the admission and extraction of the cryogenic fluid into the circulation conduit.; 2. Motor (1) according to claim 1, wherein said cryostat (11) comprises at least one sensor configured to monitor a magnetic field generated by each coil (7), and / or an operating temperature of each coil (7) and / or a current flowing through each coil (7), said motor (1) further comprising a control unit to which the at least one sensor is associated and in use configured to regulate a flow of said cryogenic fluid in the circulation duct as a function of a magnetic field, and / or a temperature and / or a current measured by said sensor. Ing. Simone Milli (Registered No. 1517 BM) 61 .E3414.12.IT.9 AP / SM 3. Engine (1) according to claim 2, wherein said control unit is configured to increase said flow of cryogenic fluid in the circulation duct if said magnetic field, and / or temperature and / or current exceed pre-set threshold values.

4. Motor (1) according to any of the preceding claims, wherein the rotor also comprises a second rotor disc (8) and a second plurality of permanent magnets (9) mechanically anchored to the second rotor disc (8).

5. Motor (1) according to any of the preceding claims and claim 4, wherein said first plurality of permanent magnets (3) faces the second plurality of permanent magnets (9). 15 6. Motor (1) according to claim 5, wherein the permanent magnets of the first rotor disc (2) and the permanent magnets of the second rotor disc (8) are arranged in such a way that a North pole of a permanent magnet of the first rotor disc (2) faces a South pole of a permanent magnet of the second rotor disc (8).

7. A motor (1) according to any preceding claim, wherein each support structure (6) defines a first seat (6a) and a second seat (6b), each seat configured to partially contain a ferromagnetic core (5); and wherein each coil (7) comprises 25 a first portion (7a) and a second portion (7b), the first portion (7a) being inserted, in use, into the first seat (6a) and the second portion (7b) being inserted, in use, into the second seat (6b).

8. Motor (1) according to any of the preceding claims and claim 7, wherein the first portion (7a) of the coil (7) and the second portion (7b) of the coil (7) are defined by a single tape, in particular the first portion (7a) of the coil (7) is defined by a portion of the tape wound from the outside towards the inside of the coil (7) and the second portion (7b) of the coil (7) is defined by a portion of the tape wound from the inside towards the outside of the coil (7).

9. Motor (1) according to any of the preceding claims, wherein each ferromagnetic core (5) is inserted within the first seat (6a) and / or the second seat (6b), each ferromagnetic core (5) furthermore has two ends (5a and 5b) each facing the permanent magnets (3 and / or 9) of the respective first rotor disc (2) and / or second rotor disc (8).

10. Engine (1) according to any of the preceding claims, wherein each coil (7) is configured to define a double pancake configuration.

11. Motor (1) according to one or more of the preceding claims, wherein the permanent magnets (3 and 9) comprise sintered rare earth magnets, in particular Neodymium-Iron-Boron magnets.

12. Engine (1) according to one or more of the preceding claims, wherein the cryostat (11) is configured to house, in the circulation duct, the aforementioned coils (7).

13. Engine (1) according to one or more of the preceding claims, wherein the cryostat (11) defines a vacuum chamber (40), has a duct (20), and a valve.

14. Cryogenic system comprising an engine (1) according to any of the preceding claims, and a circuit for introducing the cryogenic fluid into the circulation duct, in particular for introducing liquid nitrogen, connected to the inlet opening (12) and to the outlet opening (13) of the cryostat (11) of said engine (1), said engine (1) being in use configured to convey part of its power to power the cryostat (11) and the inlet circuit so as to create a flow of the cryogenic fluid between the inlet opening (12) and the outlet opening 5 (13) of said cryostat (11).

15. Method of operation of a cryogenic system according to the preceding claim, comprising the steps of: - supplying the cryogenic system with cryogenic fluid at a predefined temperature io; - conveying the power of the motor (1) to supply the cryostat (11) so as to generate a flow of the cryogenic fluid between the inlet opening (12) and the outlet opening (13) of said cryostat (11); - cooling said coils (7) by means of said cryogenic fluid flowing 15 in the circulation duct, in particular from the inlet opening (12) to the outlet opening (13) of said cryostat (11).