Integrated modular electric drive for electric machines

Abstract

Integrated electric drive system (1) for an electric machine, in particular of the axial - flux permanent -magnet type, comprising a plurality of drive modules (2), wherein each drive module (2) comprises a stator winding module (3) which is part of a stator element (4) of the electric machine; and an electronic converter module (6) electrically connected to the stator winding (3), wherein said electronic converter module (6) and said stator winding module (3) are made on a same module substrate (7), and wherein the drive modules (2) of the plurality of drive modules (2) are electrically independent of each other.

Description

[0001] Integrated modular electric drive for electric machines

[0002] TECHNICAL FIELD

[0003] The present invention refers to an integrated electric drive system for an electric machine and to a method for making said integrated electric drive system . Furthermore , the present invention refers to an electric machine , in particular of the axial - f lux permanent -magnet type , comprising said drive system .

[0004] STATE OF THE ART

[0005] An electric machine (or electric motor) usually exploits the principles of electromagnetism to convert electrical energy into mechanical energy, wherein the electrical energy may be taken from a batter , for example . The fundamental components of an electric machine are the stator ( f ixed component ) and the rotor (moving or rotating component ) . The stator comprises a plurality of windings or coils that are traversed by the electric current to create a magnetic f ield . The created magnetic f ield interacts with the rotor causing it to turn .

[0006] In order to convert direct electric current deriving for example from the battery into alternating electric current , the electric machines further comprise an electronic converter ( inverter) . In this way, the current applied to the windings can be used to control the speed and direction of the motor by varying the frequency .

[0007] The great interest in recent decades in the use of electric machines and motors has led to a strong acceleration in industrial and university research in this sector . For example , to reduce the sizes of the electric machines and to improve their ef f iciency, methods for making stator windings are known that make use of the same industrial production techniques used for printed circuits . In addition, conf igurations are known in which the stator windings are integrated with sensors for monitoring and controlling the current and position of the rotors .

[0008] However , although current research of fers solutions capable of making electric machines , or at least some components thereof , more compact and ef f icient , conf igurations of electric machines known in the literature are subj ect to failure and require careful maintenance to avoid mal functions . For example , in the event of a failure of a component or a portion of the component , it usually necessary to replace the entire component , if not the entire motor . In addition, to overcome the problem of overheating of certain parts of the motor , electric machines are often provided with cooling systems . However , the conf igurations known in the literature of fer component cooling solutions that are complex, bulky and / or easily susceptible to failure .

[0009] Document JP 2014176151 A discloses a coil drive apparatus comprising a circuit board having an electric circuit containing power modules , a coil electrically coupled to the power modules , and a substrate on which the power modules are mounted and on which the coil is f ixed .

[0010] Document US 2024 / 072591 Al discloses an axial f ield drive device comprising a housing and a rotor rotatably coupled to the housing . The rotor comprises a rotation axis and magnets . A stator assembly is coupled to the housing coaxially and adj acent to the rotor and comprises a printed circuit board ( PCB) with electrically conductive coils and an internal air duct for cooling the stator assembly .

[0011] Document US2014 / 191624 Al discloses an electric machine comprising a stator , a module comprising at least one electromagnetic coil and a switch .

[0012] Although these documents describe integrated electric drive apparatuses , the solutions of fered are not able to overcome the problems proposed regarding the compactness of the various components and the corresponding cooling .

[0013] Therefore , it is an obj ect of the present invention to provide an ef fective and easy- to-apply solution to the problems mentioned above relating to the integration of the components of an electric machine and their cooling . In particular , it is an obj ect of the present invention to provide an integrated electric drive system which has high performance , has a high failure resilience and of fers ease of assembly and maintenance .

[0014] BRIEF DESCRIPTION OF THE INVENTION

[0015] These obj ects are achieved by an integrated electric drive system, by an electric machine and by a method for making the drive system according to the claims at the end of the present description .

[0016] In a f irst aspect of the invention, there is provided an integrated electric drive system for an electric machine , in particular of the axial - f lux permanent -magnet type , comprising a plurality of drive modules , wherein each drive module comprises : a stator winding module which is part of a stator element of the electric machine ; and an electronic converter module electrically connected to the stator winding , wherein said electronic converter module and said stator winding module are made on a same module substrate , and wherein the drive modules of the plurality of drive modules are electrically independent of each other , wherein the module substrate on which the electronic converter module and the stator winding module are made is made of ceramic insulating material with high thermal conductivity .

[0017] It is noted that in the context of this description the term " drive" or " electric drive" for an electric machine means a system that controls the power supply and management of the electric motor and is responsible for converting the electric energy supplied by a power supply source into an appropriate format for powering and controlling the electric motor . Specif ically, the " drive" or " electric drive" according to the present description is understood to consist of an electronic converter electrically coupled to at least one coil element that is part of a stator . Since in the specif ic case of this description the electric drive is incorporated, or integrated, into the electric machine that must be powered, this is referred to as an " integrated electric drive" .

[0018] Thanks to this conf iguration of the drive system, it is possible to reach a deep integration between motor and converter as the non- rotating parts , i . e . the stator and the converter , can be made on the same substrate in a single production process . This results in a reduction in manufacturing costs , increased reliability due to the elimination of connectors as well as higher power density .

[0019] Furthermore , the drive system described herein is a modular system in that it is possible to make drive modules containing stator and converter portions capable of operating independently . These modules can be assembled together ( for example , j uxtaposed and / or stacked) so as to make drives of dif ferent and scalable power . Thi s results in a lower maintenance cost as each module can be replaced independently as well as increased reliability as the single module can be removed allowing the drive system to operate at reduced power . In addition, a lower design cost is obtained thanks to the scalability of the power .

[0020] In a second aspect of the invention there is provided an electric machine , in particular of the axial - f lux permanent magnet type , comprising the drive system according to the f irst aspect .

[0021] In a third aspect of the invention there is provided a method for making an integrated electric drive system according to the f irst aspect , comprising : making a drive module from a module substrate and forming a stator winding and an electronic converter module on said module substrate ; repeating the realization of the drive module several times so as to obtain a plurality of drive modules ; and assembling the plurality of drive modules , in particular by coupling a connection region of a f irst drive module with a connection region of a second drive module , to obtain the integrated electric drive system arranged on a plane , in particular having the shape of a circular crown, wherein the drive modules of the plurality of drive modules are electrically independent of each other .

[0022] BRIEF DESCRIPTION OF THE DRAWINGS

[0023] These and other aspects of the present invention will become more apparent in light of the following description of certain preferred embodiments described below .

[0024] Fig . 1A shows a schematic representation of an integrated electric drive system according to an example .

[0025] Fig . IB shows a schematic representation of the integrated electric drive system of f igure 1A coupled with two rotors .

[0026] Fig . 2 shows a drive module according to an example .

[0027] Fig . 3A schematically shows an example of two drive modules stacked one above the other .

[0028] Fig . 3B schematically shows a drive module with a cooling system according to an example .

[0029] Fig . 3C schematically shows a drive module with a cooling system according to another example .

[0030] DETAILED DESCRIPTION

[0031] Figures 1A and IB schematically show an integrated electric drive system 1 having the shape of a disc , more precisely of a circular crown, for use in an electric machine , for example an axial - f lux permanent -magnet machine . Advantageously, the system 1 is composed of a plurality of drive modules 7 arranged next to each other . Each single drive module 7 includes a stator winding module 3 and an electronic converter module 6 which is connected to the stator winding module 3 via electrical connection, for example via a connection branch 15 ( see f igure 2 ) .

[0032] From f igure 1A it is noted that all the electronic converters 6 and all the stator windings 3 present in the system 1 are arranged on a system substrate 13 which has the shape of the circular crown . However , the entire system substrate 13 is divided into a plurality of module substrates 7 , and a single electronic converter module 6 and a single stator winding module 3 are formed on each of these module substrates 7 . Specif ically, each drive module 2 consists of a single electronic converter module 6 electrically connected to a corresponding stator winding module 3 , both formed on a same module substrate 7 . The sum of all drive modules 2 forms the entire integrated electric drive system 1 , i . e . the sum of all module substrates 7 forms the entire system substrate 13 . Therefore , each drive module 2 has the shape of a crown sector and represents a sort of "wedge" of the entire system 1 .

[0033] The drive modules 2 , although physically connected to form the entire system 1 , are electrically independent of each other . This means that (within the drive system 1 ) the electronic converter module 6 is electrically connected only to the stator winding module 3 of a same drive module 2 and that converter modules 6 present on dif ferent drive modules 2 are not directly electrically connected to each other . This means that from the electronic point of view, two converter modules 6 present on dif ferent drive modules 2 can possibly only be indirectly connected to each other , for example by means of a common battery . Similarly, the stator winding module 3 (within the drive system 1 ) is electrically connected only to the electronic converter module 6 of a same drive module 2 and that stator winding modules 3 present on dif ferent drive modules 2 are not electrically (directly) connected to each other . In other words , each electronic converter module 6 serves to power only the stator winding module 3 which is located on the same module substrate 7 . Therefore , the drive modules 2 operate independently of each other . In this way, in the event of failure of an electronic converter module 6 and / or of a stator winding module 3 , the electric machine can continue to operate equally since the failure will not af fect the operation of the other modules 2 , or of the other converters 6 and windings 3 .

[0034] It is noted that the stator windings 3 are all located in an inner region of the circular crown and that the combination of all these stator windings 3 results in a stator element 4 ( schematically delimited by the dashed circumference shown in f igure 1A) . In other words , each stator winding module 3 is a part of the stator element 4 of the electric machine .

[0035] The integrated electric drive 1 therefore acts as a stator element ( f ixed component of the electric machine) and is conf igured to couple to a rotor system ( rotating part of the electric machine) . As schematically shown in f igure IB , two rotors 14 may be coupled to the drive system 1 to convert electrical energy to mechanical energy via electromagnetic coupling . As already noted, the stator element 4 of the drive system 1 is concentrated in the innermost area of the circular crown where the stator windings 3 are actually present . Consequently, for optimal coupling between stator component and rotor component , the size of the rotors 14 will be limited to this inner region of the crown . In other words , the diameter of the rotors 14 will roughly correspond to the diameter of the stator 4 or the dashed circumference of f igure 1A .

[0036] In one example , at least two of the plurality of drive modules 2 are assembled together side by side on a plane to form the system substrate 13 . To carry out this assembling , each drive module 2 comprises at least one connection region 8 adapted to connect a f irst drive module 2 next to a second drive module 2 and to determine an assembly between said f irst drive module 2 and said second drive module 2 . The connection region 8 can be on a module substrate portion 7 . As shown in f igure 2 , the connection region 8 may extend on the lateral sides of the drive module 2 , i . e . of the circular crown sector . In this way, by f lanking the plurality of drive modules 2 and assembling them, for example by mechanically constraining the corresponding connection regions 8 , the drive system 1 is obtained in the form of a circular crown extending on a plane . By way of example , the mechanical constraint can be obtained by means of a support structure having the shape of a circular crown in which a plurality of housings are obtained to f ix (by means of interlocking , gluing , screws or other methods ) the various drive modules 2 in the desired position .

[0037] Such a conf iguration makes it possible to make a highly integrated and simplif ied mechanical support structure , eliminating the need for two dif ferent housings , one for the motor and one for the converter . This aspect , combined with the elimination of the power and signal connections and therefore of the related connectors , makes it possible to signif icantly increase the power density of the entire system, as well as its reliability . It is noted from f igure 2 how the winding module 3 is represented by a planar coil formed as an element of a printed circuit and connected to the electronic converter module 6 via a circuit branch 15 . For this , known techniques may be used to make printed circuit boards .

[0038] In one example , both the stator winding module 3 and the electronic converter module 6 are made on at least one metal layer applied on the module substrate 7 by active metal brazing , direct bonded copper , or similar techniques .

[0039] Figure 2 shows a stator winding module 3 comprising a single planar coil . Alternatively, the stator winding module 3 may comprise a plurality of coils all electrically connected to the same electronic converter module 6 of the single drive module 2 .

[0040] The planar conf iguration makes the integrated electric drive system 1 according to the present disclosure particularly suitable for use in an axial - f lux permanent -magnet electric machine . These types of electric machines are characterized by having f lux lines that close axially instead of radially, as happens in the most widespread radial f lux machines . In this way, a reduced axial footprint is achieved at the same developed torque . The f latness combined with modularity, representative of this structure of the drive system 1 , makes it particularly easy to integrate the motor / power converter . The integration is in fact implemented by making the stator winding module 3 and the power converter module 6 on a single support (module substrate 7 ) , through a single production process . This integration simplif ies the design and assembly steps of not only the single drive module 2 , but also of the entire drive system 1 . In fact , once the traces have been made , it is suf f icient to carry out a single further soldering step using the well -known techniques adopted for traditional printed circuit boards ( PCBs ) .

[0041] In particular , the module substrate 7 on which the electronic converter module 6 and the stator winding module 3 are made is made of ceramic insulating material with high thermal conductivity . For example , the ceramic insulating material with high thermal conductivity may comprise A12O3and / or Si3N4or similar materials . In this way, a better heat removal capacity is determined which leads to a high overloadability and higher power density .

[0042] It is noted that in an integrated electric drive system, integration is usually achieved by making the various components (e . g . the stator winding , the electronic converter , the heat sink and possibly the casing) that are separate , which perform dif ferent functions (e . g . electrical insulation, heat removal , structural support ) and that are subsequently assembled together to achieve integration . Similarly, in the case of an integrated modular electric drive system, the stator winding module , the electronic converter module , the heat sink module and possibly a housing module are usually made separately, with dif ferent functions and which are subsequently assembled .

[0043] The adoption of a ceramic insulating material with high thermal conductivity as in the case of the present invention allows instead to make the parts that perform, at the same time , the dif ferent structural , electrical insulation and heat removal functions . In this way, it is possible to make with a single production process , for example by active metal brazing , direct bonded copper , or similar techniques , some parts that already integrate the stator winding module and the electronic converter module within them, but also a heat sink module and a structural support module ( the substrate) .

[0044] Ultimately, the use of a ceramic insulating material with high thermal conductivity for the module substrate therefore has the dual function of structural support and heat exchange . Although the use of material with high thermal conductivity may be known in the context of the integrated electric drive systems , this material is only used in order to make the heat sink element which represents a separate component from the substrate which supports the stator winding and / or the electronic converter . Therefore , in this case it would be necessary to use at least two distinct production processes to form the support and the heat sink .

[0045] Compared to the materials used for known systems , for example plastic materials used in the printed circuits for integrated systems , the ceramic material used for the drive system 1 according to the present disclosure has a higher heat exchange coef f icient . Specif ically, it ranges from 0 . 3 W / mK for the FR4 composite material , typically used for the creation of the printed circuits , to 80 W / mK for a ceramic substrate . Therefore , the use of a support in FR4 (as for a traditional PCB) cannot be compared in terms of heat dissipation to a support in ceramic insulating material with high thermal conductivity such as for example A12O3and / or Si3N4, mentioned above . In one example , at least two drive modules 2 are assembled together one above the other and coupled by means of one or more spacers 9 adapted to ensure electrical insulation between the drive modules 2 . This is represented for example in f igure 3A which shows two drive modules 2 conf igured in a sandwichlike manner one above the other . Each sandwich- like coupling of two drive modules 2 may be assembled to a similar coupling by the j unction of corresponding connection regions 8 . In this way, the resulting drive system 1 is composed of two parallel planar crowns (arranged one above the other) . The system may possibly comprise more than two drive modules 2 stacked one above the other . In this way, a drive of dif ferent power can be made without however increasing the radial sizes of the stator element .

[0046] In particular , a space 10 conf igured to f low a cooling f luid can be determined between the two drive modules 2 assembled one above the other . The cooling f luid serves to remove heat from the drive system 1 and may be a gas , or mixture of gases such as air , or a liquid . The use of a cooling f luid is combined with the use of a high heat exchange coef f icient material for the module substrate 7 to improve heat extraction .

[0047] Figures 3B and 3B show further examples for cooling the system

[0048] 1 .

[0049] In one example , the drive module 2 comprises a cooler 11 having at least one conduit 12 for f lowing a cooling f luid (gas or liquid) , wherein the cooler 11 is positioned at the electronic converter module 6 . In another example , the drive module 2 comprises a cooler 11 having at least one conduit 12 for f lowing a cooling f luid (gas or liquid) , wherein the cooler 11 is positioned at a peripheral region of the winding module 3 .

[0050] In a further example , the drive module 2 comprises a cooler 11 having at least one conduit 12 for f lowing a cooling f luid (gas or liquid) , wherein the cooler 11 is positioned at a peripheral region of the winding module 3 and the electronic converter module 6 .

[0051] It is noted that in all of the aforementioned examples , the conduit 12 is conf igured to f low a gas but also possibly a liquid therein . The conduit 12 can then be at least partially a closed conduit . The possibility of using a liquid, instead of or in addition to the gas (e . g . air) , can greatly increase the cooling ef fect by the cooler 11 .

[0052] Figures 3B and 3C show a cooler 11 with two conduits 12 for the entry and exit of the cooling f luid . It is apparent that the cooler 11 may comprise a dif ferent number of conduits 12 and that the drive module 2 may comprise a combination of multiple coolers positioned in distinct regions of the drive module 2 . Compared to the cooling mode using a cooling f luid passing between two drive modules 2 stacked one above the other ( f igure 3A) , this cooling mode ( f igures 3B and 3C) is simpler from the constructional and structural point of view .

[0053] The integrated electric drive system 1 described herein may be made by an assembly process of several drive modules 2 . In particular , the single drive module may be made from a module substrate 7 . This can have the form of a circular crown sector , for example . Above the module substrate , the electronic converter module 6 and the stator winding module 3 , which in turn may include one or more coils as explained above , are formed, respectively . The stator winding 3 and the electronic converter module 6 can be made on at least one metal layer applied on the module substrate 7 by active metal brazing , direct bonded copper , or similar techniques .

[0054] The realization of the drive module 2 is repeated several times thus obtaining a series of drive modules 2 , for example twelve as shown in f igure 1A .

[0055] The various drive modules 2 are then assembled to obtain the integrated electric drive system 1 arranged on a plane . The drive system 1 takes on the form of a disc , or rather a circular crown . The assembly is such that the single drive modules 2 are electrically independent of each other .

[0056] In addition to this assembling on a plane , the realization method comprises assembling at least two drive modules 2 one above the other and their coupling by means of one or more spacers 9 adapted to ensure electrical insulation between the drive modules 2 . By connecting together pairs of stacked modules , an integrated electric drive system 1 is obtained formed by two discs ( circular crowns ) arranged one above the other . The system may possibly comprise more than two drive modules 2 stacked one above the other .

[0057] Of course , all the technical features described above in relation to the individual drive modules 2 and the integrated electric drive system 1 can be obtained with appropriate steps of the aforementioned realization method . In order to satisfy further and contingent needs , a person skilled in the art may make numerous further modif ications and variations to the integrated electric drive system 1 , the electric machine and the realization method described above , all of which are included in the scope of protection of the present invention, as def ined by the attached claims .

Claims

CLAIMS1. Integrated electric drive system (1) for an electric machine, in particular of the axial-flux permanent -magnet type, comprising a plurality of drive modules (2) , wherein each drive module (2) comprises: a stator winding module (3) which is part of a stator element (4) of the electric machine; and an electronic converter module (6) electrically connected to the stator winding module (3) , wherein said electronic converter module (6) and said stator winding module (3) are made on a same module substrate (7) , and wherein the drive modules (2) of the plurality of drive modules (2) are electrically independent of each other, wherein the module substrate (7) on which the electronic converter module (6) and the stator winding module (3) are made is made of ceramic insulating material with high thermal conductivity .

2. Integrated electric drive system (1) according to claim 1, wherein the ceramic insulating material with high thermal conductivity comprises A12O3and / or Si3N4or similar materials.

3. Integrated electric drive system (1) according to one of the preceding claims, wherein both the stator winding module (3) and the electronic converter module (6) are made on at least one metal layer applied on the module substrate (7) by active metal brazing, direct bonded copper, or similar techniques .

4. Integrated electric drive system (1) according to one of the preceding claims, wherein each drive module (2) has the shape of a sector of a circular crown.

5. Integrated electric drive system (1) according to one of the preceding claims, wherein at least two modules of the plurality of drive modules (2) are assembled together side by side on a plane to form a substrate of the system (13) .

6. Integrated electric drive system (1) according to claim 5, wherein each drive module (2) comprises at least one connection region (8) adapted to connect a first drive module (2) next to a second drive module (2) and to determine an assembly between said first drive module (2) and said second drive module (2) , wherein in particular said connection region (8) is located on the module substrate portion (7) .

7. Integrated electric drive system (1) according to one of the preceding claims, wherein at least two drive modules (2) are assembled together one above the other and coupled by means of one or more spacers (9) adapted to ensure electrical insulation between the drive modules (2) .

8. Integrated electric drive system (1) according to claim 7, wherein between the two drive modules (2) assembled one above the other a space (10) configured to flow a cooling fluid is determined.

9. Integrated electric drive system drive system (1) according to one of the preceding claims, wherein the drive module (2) comprises a cooler (11) having at least one conduit(12) for flowing a cooling fluid, wherein the cooler (11) is positioned at the electronic converter module (6) .

10. Integrated electric drive system (1) according to one of the preceding claims, wherein the drive module (2) comprises a cooler (11) having at least one conduit (12) for flowing a cooling fluid, wherein the cooler (11) is positioned at a peripheral region of the winding module (3) .

11. Integrated electric drive system (1) according to one of the preceding claims, wherein the drive module (2) comprises a cooler (11) having at least one conduit (12) for flowing a cooling fluid, wherein the cooler (11) is positioned at a peripheral region of the winding module (3) and of the electronic converter module (6) .

12. Electric machine, in particular of the axial-flux permanent -magnet type, comprising the drive system (1) according to one of the preceding claims.

13. Method for making an integrated electric drive system (1) according to one of the preceding claims, comprising: making a drive module (2) from a module substrate (7) and forming a stator winding (3) and an electronic converter module (6) on said module substrate (7) ; repeating the realization of the drive module (2) several times so as to obtain a plurality of drive modules (2) ; and assembling the plurality of drive modules (2) , in particular by coupling a connection region (8) of a first drive module (2) with a connection region (8) of a second drive module (2) , to obtain the integrated electric drive system (1)arranged on a plane, in particular having the shape of a circular crown, wherein the drive modules (2) of the plurality of drive modules (2) are electrically independent of each other .

14. Method according to claim 13, wherein the stator winding (3) and the electronic converter module (6) are made on at least one metal layer applied on the module substrate (7) by active metal brazing, direct bonded copper, or similar techniques .

15. Method according to claim 13 or 14, further comprising assembling at least two drive modules (2) one above the other and coupling them by means of one or more spacers (9) adapted to ensure electrical insulation between the drive modules (2) .

16. Method according to one of claims 13 to 15, wherein the stator winding module (3) and the electronic converter module (6) are made on a single module substrate (7) through a single production process.

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