Electrical machine comprising a rotor

Abstract

The electrical machine (100) comprises: • a first part (101) comprising coils (102) and a second part (103) comprising magnetic elements (104) that are intended to interact magnetically with the coils (102), one of the first and second parts (101, 103) forming a rotor of the electrical machine (100) that is able to perform a rotational movement about an axis (Al) of rotation; • a power conversion system (105), the coils (102) being electrically connected to the power conversion system (105); • a first power bus (106) and a second power bus (107); • a connection of the power conversion system (105) to the first power bus (106) and to the second power bus (107); the electrical machine (100) being configured such that one of the first and second power buses (106, 107) is intended to be connected to ground.

Description

Electric machine comprising a rotor Technical field of the invention

[0001] The technical field of the invention relates to electrical machines. The invention relates in particular to an electrical machine comprising a first part comprising coils and a second part comprising magnetic elements intended to cooperate magnetically with the coils. State of the prior art

[0002] An electric machine conventionally comprises a rotor and a stator arranged to cooperate together to set the rotor in motion when the electric machine is operating in motor mode.

[0003] For example, the electrical machine may include the stator equipped with coils and surrounding the rotor then equipped with magnetic elements. In this case, the power supply to the coils makes it possible to generate magnetic fields cooperating with the magnetic elements to ensure the rotation of the rotor.

[0004] It is known to electrically connect the coils to a power converter to, for example, allow the variation of the speed of the rotor of the electric machine to adapt the efficiency of the electric machine.

[0005] The use of the power converter can lead to the appearance of a problem related to electromagnetic compatibility (also known by the abbreviation CEM, or EMC corresponding to the English "Electromagnetic Compatibility"). Indeed, when a cable is used to electrically connect the power converter to the coils, this cable is traversed, during the operation of the electrical machine, by PWM signals (abbreviation of "Pulse Width Modulation") which carry numerous high-frequency harmonics, for example frequencies between a few tens of kilohertz and a hundred kilohertz. These harmonics impact the EMC balance of the system comprising the electrical machine, the power converter and the cable, this EMC balance being linked to conducted disturbances, iethose induced by electrical conductors such as the cable, and / or to emitted disturbances, i.e. those carried by an electric or electromagnetic field. This problem becomes all the more sensitive when it is necessary to make several different systems work in the same environment, for example in a limited space, particularly as is the case for embedded systems: the problems of parasitic interactions then become very complex and the length of the cable then becomes a critical parameter.

[0006] To address this issue, efforts have been made to minimize the length of the connection (i.e. the cable) between the power converter and the electrical machine. To this end, it has been proposed to directly integrate the converter in the electrical machine; this makes it possible to optimize the EMC parameters and to create a fully integrated converter-machine assembly also known as a "smart machine" in English. This converter-machine assembly makes it possible to regulate, thanks to electronics embedded in this assembly, its operating parameters. Although the solution described in this paragraph is effective, the integration of the power electronic components (i.e. the components used to form the power converter) remains difficult, especially when the environment is complex, for example subject to high temperatures, for example strictly above 220°C.

[0007] Thus, an electrical machine with an integrated power converter is known from the prior art, which proposes to share the converter housing and the rotor and stator. In this case, the coils remain powered by a three-phase or multi-phase coupling (i.e. with a number of phases greater than or equal to 4). To this end, it is for example possible to cite patent US9539909 which presents a structure of an electrical machine with star couplings. Such an electrical machine must take into account floating potentials and remains complex to manufacture. Subject of the invention

[0008] The object of the invention is to simplify the structure of the electrical machine, in particular while improving its safety from an electrical point of view.

[0009] To this end, the invention relates to an electrical machine comprising: • a first part comprising coils and a second part comprising magnetic elements intended to cooperate magnetically with the coils, one of the first and second parts forming a rotor of the electrical machine capable of performing a rotational movement along an axis of rotation; • a power conversion system, the coils being electrically connected to the power conversion system; • a first power bus and a second power bus; • a connection of the power conversion system to the first power bus and to the second power bus; the electrical machine being configured so that one of the first and second power buses is intended to be connected to ground.

[0010] Providing an electrical machine in which said one of the first and second power buses is intended to be connected to ground makes it possible to avoid the presence of floating potentials as in the case of star couplings of the state of the art. As a result, the electrical machine is simpler to manufacture because this makes it possible to reduce the constraints linked to the electrical insulation of components of the electrical machine.

[0011] The electric machine may further comprise one or more of the following characteristics.

[0012] According to a characteristic of the electric machine, the electric machine comprises a frame having a reference potential forming the ground to which said one of the first and second power buses is connected (i.e. electrically connected), preferably the reference potential is intended to be connected to the ground according to a ground connection diagram.

[0013] This connection to the frame of the electric machine forming the ground allows to have the highest potential identical on each of the coils from which it results that the maximum voltage seen by each of the coils during operation of the electric machine in motor mode can always be the same.

[0014] According to a characteristic of the electric machine, the electric machine comprises separate elementary magnetic switching modules each comprising: • only one of the coils; • a switching cell secured to the coil of said elementary magnetic switching module and electrically connected to the coil of said elementary magnetic switching module; the elementary magnetic switching modules being distributed radially around the axis of rotation, the power conversion system comprising the switching cells, the connection being such that each switching cell is electrically connected to the first power bus and to the second power bus so that all the switching cells are electrically mounted in parallel.

[0015] Such an electrical machine proposes to divide the power conversion system into a plurality of switching cells each associated with one of the coils, resulting in the stresses applied to each of the coils being significantly reduced. A reduction in stresses makes it easier to design and produce the electrical machine.

[0016] According to a characteristic of the electrical machine, each elementary magnetic switching module is configured to allow a transfer of energy, independently of the other elementary magnetic switching modules, between the coil that it comprises and the first and second power buses.

[0017] This allows for the provision of specific operating controls for the power conversion system.

[0018] According to a feature of the electric machine, the electric machine comprises a control device for controlling the operation of the power conversion system, the power conversion system comprising the set of switching cells

[0019] Thus, the control device, also called control electronics, then makes it possible to adjust the operation of the power conversion system (for example according to the rotation speed of the rotor and / or the torque supplied to the rotor), in particular in the case where each of the elementary switching modules can be controlled from independently.

[0020] According to a characteristic of the electrical machine, each coil comprises a first terminal and a second terminal, each elementary magnetic switching module is such that: • the switching cell of said elementary magnetic switching module comprises a first connection terminal electrically connected to the first power bus, a second connection terminal electrically connected to the second power bus and a third connection terminal, the first terminal of the coil, electrically connected to said switching cell, being electrically connected to the third connection terminal; • the switching cell of said elementary magnetic switching module comprises a switch and a diode, said switch being electrically connected, on the one hand, to the first connection terminal of said switching cell and, on the other hand, both to the second connection terminal of said switching cell via said passing diode in the direction of the second connection terminal of said switching cell and to the third connection terminal, the switch of said switching cell being configured to be controlled by the control device; and the power conversion system comprises a branch connecting the first power bus and the second power bus, the branch comprising, successively from the first power bus to the second power bus: • a diode passing only towards the second power bus; • a coil connection point electrically connected to the second terminal of each of the coils; • a switch configured to be controlled by the control device.

[0021] This allows the various elementary magnetic switching modules to be controlled / piloted independently.

[0022] According to a characteristic of the electric machine, the electric machine is such that: • it comprises a first printed circuit on which the first and second power buses are mounted; • each elementary magnetic switching module comprises a second printed circuit which is specific to it and supports components of the switching cell of said elementary magnetic switching module, the coil of said elementary magnetic switching module being electrically connected to said second printed circuit and mechanically fixed relative to said second circuit printed; • the second printed circuits are connected to the first printed circuit so as to provide electrical connection logic for the switching cells to the first power bus and to the second power bus.

[0023] This has the advantage of organizing the structure of the electrical machine to facilitate its assembly and to simplify its troubleshooting if one of the elementary magnetic switching modules should fail: the possibility of selectively replacing one of the elementary magnetic switching modules is also part of sustainable development.

[0024] According to a characteristic of the electric machine, the electric machine is such that: • it comprises a third printed circuit separate from the first printed circuit and the second printed circuits; • for each switching cell, the components of said switching cell comprise the switch of said switching cell, and the diode of said switching cell; • the branch diode is electrically connected to all the elementary magnetic switching modules in order to ensure, depending on the control of the power conversion system, a freewheel phase for all or part of the elementary magnetic switching modules, the branch diode being mounted on the third printed circuit; • the branch switch is electrically connected to all the elementary magnetic switching modules and is configured to be controlled in order to ensure, depending on the control of the power conversion system, a demagnetization phase for all or part of the elementary magnetic switching modules, the branch switch being mounted on the third printed circuit.

[0025] This limits the number of components used by the power conversion system. Relocating the switch and the diode from the branch to the first printed circuit board also facilitates their cooling by moving them away from the coils and therefore also simplifies the thermal management of the entire electrical machine. Indeed, since the branch is common to all the elementary magnetic switching modules, it will be heavily used during operation of the electrical machine: the relocation made possible by the presence of the third printed circuit board then allows it to be moved away from other "hot spots" formed by the elementary magnetic switching modules.

[0026] According to a characteristic of the electric machine, each elementary magnetic switching module comprises a material mechanically securing and thermally its second circuit and its coil.

[0027] This improves the heat dissipation of the magnetic switching module as a whole while contributing to the formation of an inseparable and manipulable assembly (mechanical consistency).

[0028] According to a characteristic of the electrical machine, the switch of each switching cell is a transistor, the switch of the branch is a transistor and the control device is electrically connected to a control electrode of each of the switches of the switching cells and to a control electrode of the switch of the branch.

[0029] Thus, there is no need to galvanically isolate the control device from the switches.

[0030] According to a characteristic of the electrical machine, the control device comprises a first control module and at least one second control module, the first control module being configured to generate digital control signals and the second control module being configured to shape at least one digital control signal, received from the first control module, intended for at least one actuator of the power conversion system, the distance separating said second control module from said at least one actuator being less than the distance separating said first control module from said at least one actuator.

[0031] The distance from the first control module allows the integration into its operation of complex calculation and control components which are more sensitive to vibrations, and / or temperature and / or EMC disturbances, and which could not operate optimally near the coils, particularly in the casing of the electrical machine.

[0032] According to a characteristic of the electric machine, the electric machine comprises a casing in which the elementary magnetic switching modules are arranged, and each switching cell is thermally coupled to the casing to ensure a heat exchange between said switching cell and the casing.

[0033] This advantageously allows the electric machine to be cooled, particularly at the level of its elementary magnetic switching modules.

[0034] The invention also relates to an energy production device comprising the electrical machine as described, said one of the first and second power buses being connected to ground.

[0035] The advantages of such a device arise from those of the electric machine given above in the context of the device where the electric machine is placed in an operating environment.

[0036] Other advantages and features may emerge from the detailed description that follows. Brief description of the drawings

[0037] The invention will be better understood upon reading the following detailed description, given solely by way of non-limiting example and made with reference to the appended drawings listed below.

[0038] Figure 1 schematically represents, in a side view, an electric machine according to a particular embodiment of the invention.

[0039] Figure 2 schematically represents the electric machine of Figure 1 in a perspective view.

[0040] Figure 3 represents the electrical machine of Figure 2 from which a casing has been removed to reveal the stator and the rotor.

[0041] Figure 4 represents, in a perspective view, the electric machine as visible in Figure 3 from another angle of view.

[0042] Figure 5 represents an electrical diagram of the electrical machine according to a particular embodiment of the invention.

[0043] Figure 6 shows the electric machine of Figure 3 with the rotor and a shaft of the electric machine coupled to said rotor removed.

[0044] Figure 7 shows Figure 6 in which a ferromagnetic ring of the stator has been removed to reveal coils of the electric machine.

[0045] Figure 8 shows, in a perspective view, the rotor of the electric machine coupled to the shaft.

[0046] Figure 9 represents, in a perspective view, the electric machine of Figure 1 and Figure 2 for which the rotor, the shaft and parts of the casing have been removed in order to visualize a particular embodiment of an arrangement of elementary magnetic switching modules of the electric machine thermally coupled to the casing.

[0047] Figure 10 represents, in a perspective view, a particular embodiment of an elementary magnetic switching module of the electrical machine according to one embodiment of the invention.

[0048] Figure 11 represents, in a more detailed view, a portion of the electrical diagram of figure 5 centered on an elementary magnetic switching module of index A.

[0049] Figure 12 schematically represents a rotor and a stator of the electric machine, according to a sectional view in the axis of the shaft coupled to the rotor.

[0050] Figure 13 schematically illustrates an energy production device according to a particular embodiment of the invention.

[0051] In these figures, the same references are used to designate the same elements. The elements represented in the different figures are not necessarily drawn to scale in order to facilitate understanding of the figures. Detailed description

[0052] In the present description, a component may be chosen from: a diode, a switch, a connection terminal, a coil. Such a component may be a electrical or electronic component.

[0053] By "branch" when speaking of an electrical diagram or an electrical circuit, we mean an electrical link which may include a wire and / or an electrical track and / or one or more components.

[0054] By "connection terminal" is meant in particular a specific terminal block or any connection point allowing components to be connected together in a removable or non-removable manner.

[0055] In this description, the concept of piloting is understood as a specifically adapted command. Thus, "piloting" has the same meaning as "commanding".

[0056] The invention relates to an electric machine 100, a particular example of which is illustrated in FIGS. 1 to 5. The electric machine 100 comprises a first part 101 comprising coils 102 and a second part 103 comprising magnetic elements 104 (FIGS. 3 and 4) intended to cooperate magnetically with the coils 102. One of the first and second parts 101, 103 forming a rotor of the electric machine 100 capable of performing a rotational movement along an axis A1 of rotation. Thus, the axis A1 of rotation is the axis of rotation of the rotor of the electric machine 100. In other words, the first part 101 and the second part 103 have a degree of freedom in rotation relative to each other. The electric machine 100 comprises a power conversion system 105, the coils 102 being electrically connected to the power conversion system 105 (as shown for example in Figures 3, 4 and 5).The electronic machine 100 comprises a first power bus 106 and a second power bus 107, and a connection of the power conversion system 105 to the first power bus 106 and to the second power bus 107 as shown for example in Figures 3, 4 and 5. The electrical machine 100 is configured such that one of the first and second power buses 106, 107 is intended to be connected to ground.

[0057] The fact of providing that the electric machine 100 is configured to be connected to said one of the first and second power buses 106, 107 to ground makes it possible to avoid the presence of floating potentials during the operation of the electric machine 100 as in the case of star couplings of the state of the art. As a result, the electric machine 100 is simpler to manufacture because this makes it possible to reduce the constraints linked to the electrical insulation of components of the electric machine 100.

[0058] According to a particular embodiment, the electric machine 100 may comprise the ground to which said one of the first and second power buses 106, 107 is connected.

[0059] In the example illustrated in figures 3 to 5, the stator, then formed by the first part 101, comprises eight coils 102, notably referenced LA to LH (figure 5). This number of coils 102 is not limiting, the electric machine 100 being able to comprise more, or fewer, depending on the technical needs.

[0060] The stator may comprise, as is notably visible in figures 3, 4 and 6, a ring 108 surrounding the coils 102 and comprising projections, also called teeth in the technical field, each locally forming a ferromagnetic core 109 of only one of the corresponding coils. There are therefore as many cores 109 as there are coils. 102. For example, each core 109 is intended to increase the magnetic induction generated by the corresponding coil 102 when the electric machine 100 operates in motor mode. The ring 108 and the cores 109 form in particular a single part also called a mechanical part. For example, said part may comprise a ferromagnetic material, such as an electrical steel based on iron and silicon or may be made of a laminated ferromagnetic material such as an electrical steel based on iron and silicon.

[0061] The or each coil 102 may comprise a winding, also called a coil, of wires made of a suitable material such as copper or aluminum, insulated from each other by a layer of dielectric called enamel that comprises said coil 102. Where appropriate, the core associated with the corresponding coil 102 is arranged in the winding of the coil 102 which surrounds said core 109.

[0062] In Figure 7, the first part 101 is shown for which the ring 108 has been removed in order to better visualize the coils 102 surrounded by the ring 108.

[0063] The rotor, for example formed by the second part 103 in figures 3, 4 and 8, comprises the magnetic elements 104, for example six in number. This number of magnetic elements 104 is not limiting, the electric machine 100 being able to comprise more, or fewer, according to the technical needs and in particular according to the number of coils 102 provided.

[0064] Each magnetic element 104 may be made of a ferromagnetic material such as solid or laminated steel based on iron and silicon.

[0065] The rotor may further comprise a disc 111 secured to a shaft 110, for example by suitable mounting, which comprises the electromagnetic machine 100. The magnetic elements 104 extend radially at regular intervals from the periphery of the disc 111 towards the ring 108 which then surrounds the magnetic elements 104.

[0066] The disc 111 and the magnetic elements 104 can be made of the same material and, for example, form the same part.

[0067] Thus, the magnetic elements 104 can each form a portion of the same part or, where appropriate, be formed by separate parts.

[0068] The shaft 110 may be made of steel, such as 41 xx steel or A4 stainless steel.

[0069] The electric machine 100 can be a synchronous or asynchronous machine. In the example illustrated in Figures 1 to 5, the electric machine 100 is synchronous.

[0070] The first power bus 106 and the second power bus 107 may each comprise a ring, for example made of copper, and an arm, for example made of copper, integral with the ring and extending from the ring in a direction opposite to the rotor, for example for the purpose of connecting said first and second power buses 106, 107 to an electrical power source 130 or to an electrical energy accumulator. The ring shape makes it possible to connect parts of the power conversion system 105 distributed around the axis of rotation A1 and in particular around the rotor.

[0071] The electric machine 100 can operate in motor mode. In this case, the coils 102 can be driven (i.e. controlled) to cooperate with the magnetic elements 104 to ensure the rotation of the rotor. In this case, the electric machine 100 allows the conversion of electrical energy into mechanical energy. The shaft 110 is then a motor shaft. For example, the electric machine 100 can be a vehicle engine, such as a motor vehicle. In motor mode, the electric machine 100 can comprise, or be connected to, the electrical power source 130 (FIG. 5) via its first and second power buses 106, 107.

[0072] The electric machine 100 can operate in generator mode. In this case, mechanical energy is supplied to the rotor, for example via the shaft 110 then driven in rotation by this mechanical energy, and the cooperation between the magnetic elements 104 and the coils 102 makes it possible to generate electrical energy (for example an electric current) from the coils 102. In generator mode, the electric machine 100 can comprise, or be connected to, the electrical energy accumulator for energy storage or to any other system requiring an electrical energy supply, via its first and second power buses 106, 107.

[0073] As mentioned above, the electric machine 100 may comprise the electrical power source 130 (FIG. 5). Preferably, the first power bus 106 is electrically connected to the negative terminal (then grounded, the negative terminal is said to be common with ground) of the electrical power source 130, and the second power bus 107 is electrically connected to a positive terminal of the electrical power source 130.

[0074] In generator mode of the electric machine 100, the difference is that the coils 102 and the first and second power buses 106, 107 form a power supply, the grounding being able to be ensured in the same way as in the motor mode. Thus, everything that applies in the present description to the electric machine 100 in motor mode can be transposed to the generator mode by considering that the operation of the electric machine 100 is reversed.

[0075] The role of the power conversion system 105 is to participate in the control of the coils 102 to allow the rotation of the rotor or the recovery of electrical energy in a satisfactory manner.

[0076] Preferably, the electric machine 100 comprises a frame 112. An example of a frame 112 is visible in FIGS. 1 and 2. The frame 112 has a reference potential forming the ground to which said one of the first and second power buses 106, 107 is connected. This connection to the frame 112 of the electric machine 100 forming the ground makes it possible to have the highest potential identical on each of the coils 102, from which it follows that the maximum voltage seen by each of the coils 102 during operation of the electric machine 100 in motor mode can always be the same; it is then easier to size the components (i.e. the diodes and the transistors as notably described below) of the electric machine 100. An advantage of benefiting from a reference potential formed by the frame 112 of the machine 100 electric is that the 100 electric machine then does not present any problems linked to the neutral system as in the case of a star-coupled structure of the prior art: safety, in particular the protection of people, is simplified and improved.

[0077] Preferably, the reference potential is connected, or intended to be connected, to the earth according to an earth connection scheme, for example, in accordance with the environment in which the electrical machine is placed (we also speak of "earth system", for example using a differential circuit breaker, or "neutral system"). This earth connection implies that the mass ultimately corresponds to the earth. Earthing makes it possible to improve electrical protection, particularly with regard to the safety of people.

[0078] The frame 112 of the electric machine 100 corresponds to an envelope in which the rotor and the stator are housed in whole or in part. In addition to grounding, the frame 112 may also have the role of heat sink (for this purpose, for example, the frame 112 comprises cooling fins 131 on its outer surface), the role of magnetic shielding, and may participate in the mechanical encapsulation of the rotor and the stator, in particular as part of a casing 113 forming an envelope of the electric machine 100.

[0079] The frame 112 may be made of cast metal (e.g., cast iron, steel, or aluminum).

[0080] In fact, the electric machine 100 may comprise the casing 113 comprising the frame 112 and first and second flanges 133, 134 offset on either side of the frame 112 along the axis A1 of rotation and fixed to the frame 112 (Figures 1 and 2). Preferably, the first and second flanges 133, 134 each comprise a holding part 133a, 134a, for example comprising a ball bearing (not visible in Figures 1 and 2), the holding parts 133a, 134a serve in particular to ensure mounting of the rotor according to a pivot connection relative to the stator in order to guide the rotor in a suitable manner in rotation via the shaft 110 which cooperates with the two holding parts 133a, 134a.

[0081] The shaft 110 may pass through each of the holding parts 133a, 134a (Figures 1 and 2), or only one of the holding parts 133a, 133b, to be mechanically coupled to any type of suitable mechanical member to be set in motion such as a wheel of a motor vehicle or to a generator of a movement to drive the shaft 110 in rotation and generate electricity via the coils 102.

[0082] Preferably, the first and second flanges 133, 134 each comprise a portion 133b, 134b fixed to the casing 112 to participate in the formation of the housing 113 and serving as a fixing support for the corresponding holding part 133a, 133b of said first flange 133 or second flange 134. The portions 133b, 134b of the first and second flanges 133, 134 may comprise cooling fins 131 to participate in the cooling of the electric machine 100. The portions 133b, 134b of the first and second flanges 133, 134 may be made of the same material as the casing 112. Alternatively, the portions 133b, 134b of the first and second flanges 133, 134 may be made of a material different from that of the carcass 112; for example the carcass 112 may be made of cast iron and the parts 133b, 134b of the first and second flanges 133, 134 may be made of aluminum.

[0083] The electric machine 100 may comprise a position encoder 135 mounted along the shaft 110, for example on the side of an external face of the casing 113. For example, in FIG. 1 the position encoder 135 is fixed to the part 134a for holding the second flange 134. The role of the position encoder 135 is to provide data regarding the position of the shaft 110 intended to participate in the control of the coils 102. The electric machine 100 may also be without a position encoder 135: in this case the electric machine 100 is considered to be operating in autopilot mode.

[0084] The first and second flanges 133, 134 may be assembled to the carcass 112 by any suitable mechanical means such as for example using screws (not shown). Furthermore, to allow the shaft 110 to extend out of the casing 113, the first flange 113a may comprise an opening 114 for the passage of the shaft 110 (figure 9) at the periphery of which the holding part 133a is mounted (holding part 133a not visible in figure 9 because removed), the same principle may apply to the second flange 134.

[0085] The electric machine 100 makes it possible, thanks to the use of the mass as mentioned above, to limit the voltage at the terminals of the coils 102 for example by 1 / 3 compared to a star-coupled structure.

[0086] Preferably, the electric machine 100 comprises separate elementary magnetic switching modules 115, notably visible in figures 3, 4, 5, 6, 7, 9, 11 and an example of which is illustrated individually in figure 10. Each elementary magnetic switching module 115 comprises only one of the coils 102 (LA to LH in figure 5) and is notably shown diagrammatically by dotted lines in figures 5 and 11, and a switching cell 116 secured to the coil 102 of said elementary magnetic switching module 115 and electrically connected to the coil 102 of said elementary magnetic switching module 115. By "secured" is meant here mechanically secured, notably in the sense that the corresponding coil 102 is fixed relative to the switching cell 116 to which it is secured. The elementary magnetic switching modules 115 are distributed radially around the axis A1 of rotation.The power conversion system 105 comprises the switching cells 116. The connection is such that each switching cell 116 is electrically connected to the first power bus 106 and to the second power bus 107 so that all the switching cells 116 are electrically connected in parallel. This parallel connection is notably illustrated in the electrical diagram of FIG. 5. Thus, such an electrical machine 100 proposes to divide the power conversion system 105 at least into a plurality of switching cells 116 each associated with one of the coils 102, from which it follows that the stresses applying to each of the coils 102 are significantly reduced in comparison with a star-coupled structure. These stresses are notably electrical stresses on. electrical insulation due to the electrical potentials seen by the coils 102 and necessary for the operation of the electric machine 100. Making each coil 102 integral with the switching cell 116 which then participates in its control allows integration of the switching cells 116 directly into the electric machine 100 as close as possible to the corresponding coils 102, in particular inside the carcass 112 of the electric machine 100: this results in better integration of the electric machine 100 having an influence on the reduction of constraints. The parallel connection proposed here allows modularity in the design and construction of the electric machine 100.Thus, it is possible, for example, to insert a deliberately empty space between two adjacent elementary magnetic switching modules 115, whereas this space could, due to its volume, allow the integration of an elementary magnetic switching module 115. In other words, for a given size of the first part 101 of the electric machine 100, it is possible to adjust the number of elementary magnetic switching modules 115 according to the desired power for the electric machine 100 without having to produce a new structure for the electric machine 100: the parts used in the composition of the electric machine 100 are then standardized and the choice of parts, in particular the number of elementary magnetic switching modules 115, makes it possible to limit the cost of the electric machine 100 according to the desired power for this electric machine 100.

[0087] In other words, the elementary magnetic switching modules 115 each offer integration such that it makes it possible to develop electrical machines 100 with extended functions in terms of operation, reconfiguration and operational safety. Furthermore, combined with the fact that one of the first and second power buses 106, 107 is connected, or intended to be connected, to ground, this makes it possible to simplify the electrical insulation within the electric machine 100 by simplifying the map of electrical potentials within the elementary magnetic switching modules 115.

[0088] The switching cells 116 are configured to ensure, by means of suitable control signals for example provided by a control device 117 described in more detail below, locally the circulation of a current in the coil 102 and therefore the operation of the corresponding elementary magnetic switching module 115 in its entirety.

[0089] The switching cells 116 are therefore preferably each placed at the level of the corresponding coil 102 which is then electrically connected, and in particular mounted on, the switching cell 116. This makes it possible to eliminate a cable connecting, for example, a power conversion system located at a distance from the rotor and the stator, for example outside the frame 112, and therefore to limit the problems of electromagnetic compatibility and the disturbances which result therefrom. The elimination of this cable also makes it possible to have better control of the voltage fronts that each switching cell 116 imposes on the coil 102 of the elementary switching module 115. magnetic comprising said switching cell 116.

[0090] The fact of having a single coil per elementary magnetic switching module 115 is that this makes it possible, unlike elementary magnetic switching modules which would comprise several, to limit the electrostatic stresses because the inter-turn stresses of a corresponding coil 102 are better controlled due to a shorter winding length compared to a winding comprising several coils.

[0091] Furthermore, this distribution in elementary magnetic switching modules 115 makes it possible to avoid the need for a centralized conversion structure with star couplings which would supply all the coils via a conventional three-phase or even multi-phase coupling. The use of elementary magnetic switching modules 115, and therefore of switching cells 116, makes it possible to distribute the power conversion system 105 within the electrical machine 100, thereby reducing the constraints which apply to the latter, in particular: • each switching cell 116 only supplies one of the coils 102, the voltage constraints which apply to the components, in particular power components such as a transistor and a diode as will be seen later, of the switching cell 116 are limited; this makes it possible to envisage suitable operating ranges or even to use lower-cost components (the power components may have lower ratings and not require galvanic isolation: overall this can make it possible to limit the number of components of the electrical machine 100 and therefore the cost); • this allows each switching cell 116 to be integrated as close as possible to the coil 102 to which it is electrically connected, thus providing obvious advantages in terms of EMC since the wired connection between the power conversion system 105 and the coils can be reduced, if necessary this also allows the use of SiC components (i.e. using, or based on, Silicon Carbide) or GaN (i.e. using, or based on, gallium nitride) within these switching cells 116, these components (in particular diodes and transistors) have increased performance in terms of operating frequency, electrical losses (heating of the components) and compactness, for example, SiC remains stable even at approximately 200°C which allows the SiC-based components to be placed at the heart of the electric machine 100 even near hot spots; • the switching cells 116 described make it possible, due to the connection, or the intended connection, to the ground of said one of the first and second power buses 106, 107, to control the switching cells 116 without needing to provide galvanic isolation on the routing of the control signals (the control device 117, described in more detail below, and the power conversion system 105 can then be referenced to a single neutral point, i.e. ground); • the parallel connection with grounding has an advantage from the point of view of the EIS (abbreviation for “Electrical Insulation System”) of the electric machine 100 in the sense that the coils 102 then see identical voltage constraints, unlike star-coupled structures, thus allowing greater flexibility in the design of the electrical insulation of the electric machine 100.

[0092] According to a particular embodiment, each elementary magnetic switching module 115 can be configured to allow a transfer of energy, independently of the others of the elementary magnetic switching modules 115, between the coil 102 that it comprises and the first and second power buses 106, 107. This makes it possible to provide specific operating controls for the power conversion system 105. For example, this can make it possible to compensate for mechanical defects, to envisage redundancies for applications whose operational safety is critical or even to bring out new adjustment parameters to obtain a nominal operating point of the electric machine 100. In other words, it is then possible to improve the overall operation of the electric machine 100 by allowing a local adjustment of the operation for each elementary magnetic switching module 115 if necessary.This independent energy transfer is made possible in particular by the parallel assembly mentioned above. By "independently", it is understood here in particular that each coil 102 can be activated without its activation causing the activation of another of the coils 102.

[0093] What has been described above results in a need to control / command the power conversion system 105 to implement the energy transfer independently / selectively. To this end, the electric machine 100 may comprise the control device 117 (for example as illustrated in FIGS. 3 to 7) to control the operation of the power conversion system 105, the power conversion system 105 comprising all (i.e. all) switching cells 116. Thus, the control device 117, also called control electronics, then makes it possible to adjust the operation of the power conversion system 105, in particular in the case where each of the switching cells 116 can be controlled independently, for example by taking into account the information from sensors present on the electric machine 100 (e.g.135 position encoder, rotor speed sensor, temperature sensor, or any other type of sensor providing relevant information in the context of the operation of the 100 electric machine in order to adjust its operation).

[0094] For example, the control device 117 may comprise all the means necessary to generate control signals and propagate them to the power conversion system 105. Such means may comprise a processor and a suitable program executed by the processor to control the electric machine 100.

[0095] An exemplary embodiment is now described allowing the implementation of a control of the elementary magnetic switching modules 115 in a selective / independent manner. According to this example, in particular illustrated according to a particular embodiment in FIGS. 5 and 11, each coil 102 comprises a first terminal 118a and a second terminal 118b, and each elementary magnetic switching module 115 is such that: • the switching cell 116 of said elementary magnetic switching module 115 comprises a first connection terminal 119a electrically connected (ie connected) to the first power bus 106, a second connection terminal 119b electrically connected (ie connected) to the second power bus 107 and a third connection terminal 119c, the first terminal 118a of the coil, electrically connected to said switching cell 116, being electrically connected (ie connected) to the third connection terminal 119c; • the switching cell 116 of said elementary magnetic switching module 115 comprises a switch 120, TA (figure 11, and referenced TA to TH in figure 5) and a diode 121, DA (figure 11, and referenced TA to TH in figure 5), said switch 120 being electrically connected, on the one hand, to the first connection terminal 119a of said switching cell 116 and, on the other hand, both to the second connection terminal 119b of said switching cell 116 via said diode 121, DA (figure 11, and referenced DA to DH in figure 5) passing towards the second connection terminal 119b of said switching cell 116 and to the third connection terminal 119c, the switch 120, TA (figure 11,and referenced TA to TH in figure 5) of said switching cell 116 being configured to be controlled by the control device 117 for example the control device 117 is configured to control the switch 120 to vary it between an open state and a closed state., In this case, the power conversion system 105 further comprises a branch 122 connecting the first power bus 106 and the second power bus 107 (i.e. the branch 122 is electrically connected via its two opposite ends respectively to the first power bus 106 and to the second power bus 107), the branch 122 comprising, successively from the first power bus 106 to the second power bus 107: • a diode 123 passing only in the direction of the second power bus 107, this diode 123 is in particular a power diode and its role is that of a freewheel diode; • a connection point 124 of the coils 102 electrically connected (ie connected) to the second terminal 118b of each of the coils 102; • a switch 125 configured to be controlled by the control device 117, for example the control device 117 is configured to control the switch 125 to vary it between an open state and a closed state. Each switching cell 116 comprising the corresponding diode 121, the corresponding diodes are referenced DA to DH in Figure 5. Each switching cell 116 comprising the corresponding switch 120, the corresponding switches 120 are referenced TA to TH in Figure 5. This makes it possible to independently control / drive the different elementary magnetic switching modules 115 via the switching cells 116. In particular, as a function of the commands generated by the control device 117 intended for the switch of the branch 122 and each of the switches 120 of the switching cells 116. In a motor mode of the electric machine 100, this makes it possible for each coil 102 (i.e. for each elementary magnetic switching module 115) to selectively allow its power supply, its demagnetization or its placement in a freewheel mode in which it has no influence on the rotation of the rotor.For each magnetic switching cell 116, the diode 121 is in particular a power diode 121 whose role is to close the current circuit during a demagnetization phase of the coil 102 electrically connected to said switching cell 116. The transistors mentioned in this paragraph are in particular power transistors.

[0096] Branch 122 is “factored” for all of the coils 102 so as to limit the number of components within the electric machine 100. This branch 122 makes it possible in particular to have a common point (via the connection point 124) to connect all of the coils 102 and allow the demagnetization of the magnetic circuit of the electric machine 100.

[0097] In fact, as shown in Figures 5 and 11, each elementary magnetic switching module 115 can comprise: • a first branch electrically connected to the first connection terminal 119a and to the second connection terminal 119b, this first branch successively comprising, from the first connection terminal 119a, the switch 120 of the switching cell 116 of said elementary magnetic switching module 115, the third connection terminal 119c of the switching cell 116 of said elementary magnetic switching module 115 and the diode 121 of the switching cell 116 of said elementary magnetic switching module 115; • a second branch electrically connected to the third electrical connection terminal 119c and to a fourth connection terminal 119d belonging to the switching cell 116 of said elementary magnetic switching module 115, the second branch comprising the coil 102 of said elementary magnetic switching module 115 then electrically connected to the third connection terminal 119c and to the fourth connection terminal 119d respectively via its first terminal 118a and its second terminal 118b.

[0098] The connection point 124 of the coils 102 electrically connected to the second terminal 118b of each of the coils 102 makes it possible to connect all the coils 102 to a common point in the electrical circuit of the electric machine 100, which allows the demagnetization of the magnetic circuit (i.e. the coils 102). The sharing of the branch 122 by its electrical connection to all the elementary magnetic switching modules 115 makes it possible to limit the overall number of components of the electric machine 100.

[0099] Demagnetization, also called the demagnetization phase of an elementary magnetic switching module 115, ensures that the coil 102 of this elementary magnetic switching module 115 is no longer the seat of a residual magnetic flux which could oppose the relative movement between the rotor and the stator in motor mode and produce overvoltages at the terminals of the corresponding switch 120 (the problem transposing in a similar manner when the electric machine 100 operates in generator mode).

[0100] Freewheel mode, also called freewheel phase, allows the module to be placed 115 elementary magnetic switching in a mode where: • it does not participate in the rotation of the rotor in motor mode; • it does not recover energy from the rotor in generator mode.

[0101] For example, to allow the connection point 124 of the coils 102 to be electrically connected to the second terminal 118b of each of the coils 102, each cell 116 switching may include the fourth connection terminal 119d then electrically connected to the connection point 124.

[0102] Thus, more generally, the control device 117 can be configured so as to allow control of the elementary magnetic switching modules 115 in order to selectively place each of the elementary magnetic switching modules 115 in one of the following phases: a magnetic cooperation phase, the freewheel phase, the demagnetization phase. The magnetic cooperation phase can be a power supply phase in which the coil 102 is powered so as to generate a magnetic field (in motor mode) or a recovery phase in which the coil 102 generates electrical energy (in generator mode).

[0103] According to an exemplary embodiment, illustrated without limitation in figures 3, 4, 6, 7, the electric machine 100 may comprise a first printed circuit 126 on which the first and second power buses 106, 107 are mounted. In this exemplary embodiment, each elementary magnetic switching module 115 comprises a second printed circuit 127 which is specific to it and supports components of the cell. 116 switching of said elementary magnetic switching module 115, the coil 102 of said elementary magnetic switching module 115 being electrically connected to said second printed circuit 127 and mechanically fixed relative to said second printed circuit 127. In addition, the second printed circuits 127 are connected to the first printed circuit 126 so as to provide a logic for electrical connection of the switching cells 116 (where appropriate via the first and second connection terminals 119a, 119b) to the first power bus 106 and to the second power bus 107 in particular with a view to authorizing the supply of at least one of the coils 102.This has the advantage of organizing the structure of the 100 electric machine to facilitate its assembly and to simplify its troubleshooting if by chance an elementary magnetic switching module 115 becomes faulty: the possibility of selectively replacing one of the elementary magnetic switching modules 115 is also part of sustainable development.

[0104] Thus, the elementary magnetic switching modules 115 are preferably removable. They can then each be fixed within the electric machine 100 by reversible mounting means to allow the disassembly, in particular independent, of each of the elementary magnetic switching modules 115 with a view to its replacement if necessary.

[0105] According to a particular non-limiting embodiment, for each switching cell 116, the second circuit 127 of said switching cell 116 comprises the first, second, third and fourth connection terminals 119a, 119b, 119c, 119d and the components of the switching cell 116 are the switch 120 and the diode 121 mounted on said second printed circuit 127 so as to be electrically connected in series with each other by said second printed circuit 127 on the first branch mentioned above connecting the first connection terminal 119a of the switching cell 116 and the second connection terminal 119b; the coil 102 connected to said switching cell 116 being connected via its first terminal 118a to the third terminal 119c for connection to said second circuit 127 and via its second terminal 118b to the fourth terminal 119d for connection to said second circuit 127.The person skilled in the art understands from Figure 11 that, for the or each switching cell 116, the third connection terminal 119c of said switching cell 116 can be arranged on the electrical path between the switch 120 and the diode 121 of said switching cell 116; this being only one example of integration that can be adapted according to the needs. According to this particular embodiment, the first printed circuit 126 can comprise means intended to allow: • to electrically connect all the first connection terminals 119a of the switching cells 116 to the first power bus 106, for example using screws 136a which ensure both the passage of current between the first power bus 106 and the first connection terminals 119a, and the mechanical retention of the first power bus 106 to the first printed circuit 126 (figures 3, 6, 7 and 10); • to electrically connect all the second connection terminals 119b of the switching cells 116 to the second power bus 107, for example using screws 136b which ensure both the passage of current between the second power bus 107 and the second connection terminals 119b, and the mechanical retention of the second power bus 107 to the first printed circuit (figures 3, 6, 7 and 10); • electrically connect together all the fourth connection terminals 119d to a single track of the first circuit 126, this track then being electrically connected to the connection point 124.

[0106] The electric machine 100 may comprise a third printed circuit 137 distinct from the first printed circuit 126 and the second printed circuits 127. The diode 123 of the branch 122 and the switch 125 of the branch 122 are mounted on this third printed circuit 137 (figures 3, 4, 6, 7). In other words, the branch 122 is notably formed on the third printed circuit 137. The fact of providing a third specific printed circuit 137 is that this makes it possible to position the components of the branch 122 more easily, for example by moving them away from the heat source that can form the set of elementary magnetic switching modules 115. Thus, the third printed circuit 137 is notably distant from the second printed circuits 127.

[0107] The third printed circuit 137 can be arranged in a housing 138 (figures 1, 2 and 9) preferably arranged on the outside of the casing 113 of the electric machine 100, thus making it possible to relocate the location of the branch 122 for thermal reasons so as to limit its heating. This housing 138 can be welded or screwed to the frame 112.

[0108] According to one embodiment, for each switching cell 116, the components of said switching cell 116 may comprise the switch 120 of said switching cell 116, and the diode 121 of said switching cell 116. The diode 123 of the branch 122 is electrically connected to all the elementary magnetic switching modules 115 (in particular via the connection point 124) in order to ensure, depending on the control of the power conversion system 105, a freewheel phase for all or part of the (i.e. for at least one of the) elementary magnetic switching modules 115, the diode 123 of the branch 122 being mounted on the third printed circuit 137.The switch 125 of the branch 122 is electrically connected to all the elementary magnetic switching modules 115 (in particular via the connection point 124) and is configured to be controlled in order to ensure, depending on the control of the power conversion system 105, a demagnetization phase for all or part of the (i.e. for at least one of the) elementary magnetic switching modules 115, the switch 125 of the branch 102 being mounted on the third printed circuit 137. This makes it possible to limit the number of components used by the power conversion system 105. The relocation of the switch 125 and the diode 123 of the branch 122 on the third printed circuit 137 also makes it possible to facilitate their cooling by moving them away from the coils 102 and therefore also to simplify the. thermal management of the entire 100 electric machine because the switch 125 and the diode 123 of the branch 122 are in particular the most stressed components of the 100 electric machine.

[0109] Thus, the branch 122 may be partly formed by electrically conductive tracks of the third printed circuit 137. The branch 122 may then be electrically connected to the first and second power buses 106, 107 via its longitudinal ends, for example via the first printed circuit 126 to which the third printed circuit 127 is preferably electrically connected. The first printed circuit 126 may then comprise necessary means, such as electrically conductive tracks, for connecting the two longitudinal ends of the branch 122 to the first and second power buses 106, 107. Furthermore, the first printed circuit 126 may comprise necessary means, such as electrically conductive tracks, for electrically connecting the fourth connection terminals 119d of the second printed circuits 127 to the connection point 124 formed on the third printed circuit 137.Thus, the third printed circuit 137 can be kept at a distance from the second printed circuits 127 using the first printed circuit 126 which then serves as an interface to which the second circuits are electrically connected. 127 printed and the third circuit 137 printed according to a suitable electrical connection logic.

[0110] Each elementary magnetic switching module 115 may comprise a material 128 (shown schematically in FIG. 10 in an exaggerated manner by dotted lines because this material 128 is not really visible to the naked eye due to the fact that this material 128 may be in the form of a covering layer of a few micrometers and typically less than 100 micrometers) mechanically and thermally securing its second printed circuit 127 and its coil 102, the mechanical securing making it possible to provide mechanical coherence to avoid vibrations. This material 128 is not visible in the figures other than figure 10 in the sense that it is an impregnation material, conventionally transparent, used to impregnate (i.e. cover in whole or in part) the elementary magnetic switching module 115. [yes] Material 128 may be a polymer resin conventionally used in electrical machines to impregnate components. Since such material 128 is known per se, it is not described in further detail in this detailed description.

[0112] Material 128 is also known in the field of electrical machines as impregnation material 128 or encapsulation material 128.

[0113] In particular, the material 128 can further cover the diode 121 and the switch 120 of the switching cell 116 of the corresponding elementary magnetic switching module 115; this makes it possible to improve the heat dissipation of the elementary magnetic switching module 115 as a whole by eliminating air voids within it which are harmful to thermal conduction, while making it possible to form an inseparable and manipulable assembly.

[0114] For example, the switch 120 of each switching cell 116 is a transistor, the switch 125 of the branch 122 is a transistor and the control device 117 is electrically connected to a control electrode 120a of each of the switches 120 of the switching cells 116 and to a control electrode 125a of the switch 125 of the branch 122. Thus, it is understood that there is no need to galvanically isolate the control device 117 from the switches 120, 125 (physical electrical links to the control electrodes are possible). This makes it possible to simplify the electric machine 100, to reduce the manufacturing costs of the electric machine 100 and to optimize the thermal operating range of the electric machine 100. The reduction in costs is linked to the fact that there is no need to have galvanic isolation for example by using phototransistors controlled via a light signal thus ensuring galvanic isolation.

[0115] In Figures 3, 4, 6, 7, 9, 10, the diodes 121, 123 and the transistors 120, 125 are each represented as an example by a TO-220 package which integrates the desired electronic function.

[0116] The transistors 120, 125 mentioned above may be metal-oxide gate field effect transistors, more commonly known as MOSFETs. MOSFET is the abbreviation for Metal Oxide Semiconductor Field Effect Transistor.

[0117] Although it is possible not to use galvanic isolation in the context of controlling the switches 120, 125 of the switching cells 116 and of the branch 122, the use of galvanic isolation can still be achieved. For this purpose, the switches 120 of the switching cells 116 may be phototransistors and the switch 125 of the branch 122 may be a phototransistor. In this case, the control device 117 comprises optoelectronic devices each configured to transform an electrical signal into a light signal making it possible to control only one of the phototransistors.

[0118] According to one embodiment, the control device 117 may comprise a first control module 117a and at least one second control module 117b. The first control module 117a (also called remote control) is configured to generate digital control signals and the, or where appropriate each, second control module 117b is configured to shape at least one digital control signal, received from the first control module 117a (in particular by wired connection), intended for at least one actuator of the power conversion system 105, the distance separating said second control module 117b from said at least one actuator 120, 125 being less than the distance separating said first control module 117a from said at least one actuator 120, 125.The distance of the first control module 117a makes it possible to incorporate in its operation complex calculation and control components which are more sensitive to vibrations and temperature and could not operate optimally near the coils 102, in particular in the casing 112 of the electric machine 100. Thus, the first control module 117a can determine when the actuators (i.e. the switches 120, 125) must be switched and generated. digital control signals for controlling the actuators. These digital control signals can then propagate to the vicinity of the actuators to be transformed into signals compatible with the actuators to be controlled, keeping digital control signals as close as possible to the actuators makes it possible to limit EMC problems. For example, the first control module 117a may comprise one or more microprocessors or other components sensitive to temperature and / or EMC and / or to mechanical vibration problems: they are then remote from the rotor / stator assembly, or even outside the casing 112, for example in the housing 138 to be protected. In particular, the first control module 117a is arranged in the housing 138 and mounted on a fourth printed circuit 139.This fourth printed circuit 139 can be electrically connected to the first printed circuit 126 which then participates in the routing of the digital control signals, for example via electrically conductive tracks adapted towards the second modules 117b.

[0119] In particular, the actuators are the switches 120 of the switching cells 116 and the switch 125 of the branch 122.

[0120] The electrical machine 100 may comprise, for each switch 120, 125, a second control module 117b which is specific to it and arranged in proximity (for example as close as mechanical integration allows, such as for example a few centimeters) to the switch 120, 125 to be controlled. There are therefore here as many second control modules 117b as there are switches forming a set of switches 120, 125 comprising the switches 120 of the switching cells 116 and the switch 125 of the branch 122. In this case, the second module 117b intended to control the switch 125 of the branch 122 may be mounted on the third printed circuit 137; the first printed circuit 126 then participates in the routing of the digital control signal from the first module 117a to said second module 117b.Furthermore, in this case, for each elementary magnetic switching module 115, one of the second modules 117b specific to it is mounted on its second printed circuit 127 to control the switch 120 of the switching cell 116 of said elementary magnetic switching module 115; the first printed circuit 126 then participates in the routing of the digital control signal from the first module 117a to said second module 117b. This allows a satisfactory distribution with respect to EMC.

[0121] In particular, the second control module 117a is configured to pass the corresponding digital control signal, for example in 0.5V, into a voltage adapted to the control of the corresponding actuator; for example this voltage adapted to the control of the actuator is at a higher voltage level or corresponds to a passage into a bipolar power supply.

[0122] The elementary magnetic switching module 115 may comprise a spacer 129 which makes it possible to ensure suitable positioning between the coil 102 and the second printed circuit 127 to which the coil 102 is connected (figure 10). This spacer 129 makes it possible, in particular during manufacturing, to carry out an impregnation reproducible by the material 128. The spacer 129 can be made of ceramic or temperature-resistant polymers such as PEEK (abbreviation for “PolyEtherEtherKetone” in English).

[0123] Figure 10 shows by way of example the first and second connection terminals 119a, 119b in the form of electrically conductive holes formed in the second printed circuit 127 and allowing the screws 136a, 136b to be screwed in to allow the first and second connection terminals 119a, 119b to be electrically connected respectively to the first power bus 106 and to the second power bus 107.

[0124] In particular, the switching cells 116 electrically connected in parallel, and in particular according to the electrical diagram of FIG. 5, result in great flexibility as regards the control part of the electric machine 100 because each elementary magnetic switching module 115 can be selectively placed in a state in which its coil 102 is powered, in a state where it is placed in freewheel (freewheel phase), in a state where its coil 102 is demagnetized. For example, on the basis of FIG. 5, it is possible to summarize the commands, in particular to T CO m and Ti in the following table: In which: • T com represents switch 125 of branch 122 which can occupy the controlled state (switch 125 closed) or the non-controlled state (switch 125 open); • Dcom represents diode 123 of branch 122 which can be blocked or passing depending on the circulating currents; • Ti represents the switch 120 of the switching cell 116 of index i; • Di represents the diode 121 of the switching cell 116 of index i which can be blocked or conductive depending on the circulating currents; the index i can vary depending on the number of elementary magnetic switching modules 115. In the example illustrated in figure 5 which represents the electromagnetic machine 100 with eight coils, the index i varies from A to H. In this case, the control device 117 allows operation of each of the coils 102 in multiphase, in particular on four phases, and allows more possibilities as regards the freewheel phases compared to a star-coupled structure. In fact, in the freewheeling phase, it is necessary to guarantee the flow of current in the coil 102 without energy input from the electrical power source 130; the coil 102 cannot undergo sudden current variations, the role of the freewheeling phase is then to avoid this. During the freewheeling phase, the magnetic energy stored in the stator and the rotor hardly decreases. In the demagnetization phase, thanks to the two diodes Di and D CO m, the potential at the terminals of the corresponding coil 102 is reversed and the magnetic energy can return to the electrical power source 130 which can be a voltage source.

[0125] Conventionally, each elementary magnetic switching module 115 is configured to induce a magnetic field having a positive pole and a negative pole when its coil 102 is powered appropriately.

[0126] For example, the windings of the coils 102 may be arranged so that the magnetic flux is reversed every other coil in the succession of elementary magnetic switching modules 115 by reasoning by pair of coils 102 facing each other with respect to the rotation axis A1. This does not impact the normal operation of the electric machine 100, but it may offer different control solutions in degraded mode, i.e. in the event of failure of one or more elementary magnetic switching modules 115, by having the possibility of "forcing" the demagnetization or freewheeling phases via the elementary magnetic switching modules 115 still operational: this makes it possible to ensure an equivalent of the corresponding operating phase of the faulty elementary module(s) 115 using the operating phases of the elementary modules 115 operational in a degraded operating mode of the electric machine 100.

[0127] According to the particular embodiment of figure 5 with eight elementary magnetic switching modules 115, the coils 102 can be arranged as shown diagrammatically in figure 12 so that by taking a predetermined direction Fl of orientation we have successively: • a first elementary magnetic switching module of index A which presents, depending on the direction of orientation, its negative pole then its positive pole; • a second elementary magnetic switching module of index B which presents, depending on the direction of orientation, its positive pole then its negative pole; • a third elementary magnetic switching module of index C which presents, depending on the direction of orientation, its negative pole then its positive pole; • a fourth elementary magnetic switching module of index D which presents, depending on the direction of orientation, its positive pole then its negative pole; • a fifth elementary magnetic switching module of index E which presents, depending on the direction of orientation, its positive pole then its negative pole; • a sixth elementary magnetic switching module of index F which presents, depending on the direction of orientation, its negative pole then its positive pole; • a seventh elementary magnetic switching module of index G which presents, depending on the direction of orientation, its positive pole then its negative pole; • an eighth elementary magnetic switching module of index H which, depending on the direction of orientation, has its negative pole then its positive pole which is then proximal to the negative pole of the first elementary magnetic switching module of index A. This makes it possible to create pairs of coils 102 (i.e. operating phase pairs) formed by the following pairs (A; E), (B; F), (C; G) and (D; H), thus making it possible to place the coils 102 in such a way that the magnetic fluxes created by each of them add up, but in such a way that from one phase pair to the next there is an alternation in the direction of the magnetic flux.

[0128] It follows from what has been described above that it is preferred to implement means allowing dissipation of heat generated by the elementary magnetic switching modules 115, or even to cool them voluntarily. For this purpose, the electric machine 100 may comprise the casing 113 in which the elementary magnetic switching modules 115 are arranged, and each switching cell 116 is thermally coupled to the casing 113 to ensure a heat exchange between said switching cell 116 and the casing 113. To improve the dissipation of heat to the outside, the casing 113 may comprise cooling fins 131 for example formed by the fins 131 of the frame 112 and the fins 131 of the first and second flanges 133, 134.

[0129] More particularly, the casing 113 may comprise a thermally conductive ring 132 (for example visible in FIG. 9) thermally coupled to the elementary magnetic switching modules 116. The thermally conductive ring 132 may participate in passive or active cooling. In the context of passive cooling, the thermally conductive ring 132 may be configured to allow the circulation of a heat transfer fluid inside the thermally conductive ring 132. In the context of passive cooling, the thermally conductive ring 132 may be thermally coupled to the fins 131 mentioned above; the thermally conductive ring 132 may then be made of aluminum.

[0130] The thermally conductive ring 132 may have an internal surface having faces, preferably flat, each in contact with only one of the elementary magnetic switching modules 115 (each elementary magnetic switching module 115 being in thermal contact with one of said faces) which may also be mechanically mounted on this face to ensure its retention within the The electric machine 100 and its thermal coupling to said face. Thus, in the example illustrated in figure 9 with eight elementary magnetic switching modules 115, the internal surface is formed by the faces arranged so that the internal surface has an octagonal section in a plane orthogonal to the axis Al of rotation.

[0131] Preferably, for each elementary magnetic switching module 115, the switch 120 and the diode 121 of its switching cell 115 are mounted on one of the faces of the internal surface of the thermally conductive ring 132 to be fixed there and thermally coupled there.

[0132] The thermally conductive ring 132 may be an integral part of the first flange 133.

[0133] The invention also relates to an energy production device 1000 comprising the electric machine 100 as described (FIG. 12) of which said one of the first and second power buses 106, 107 is connected to ground. The energy produced may be mechanical energy supplied at the output of the electric machine 100 by the rotor (motor mode) to a consumer 1001 of mechanical energy by exploiting the electrical power source 130. The energy produced may be electrical energy from the coils 102 due to the rotation of the rotor, for example mechanically actuated via the shaft 110 by a device 1002 for supplying mechanical energy; the energy produced may be supplied to a consumer 1003 of electrical energy such as the electrical energy accumulator.

[0134] The 100 electric machine according to the present invention finds an industrial application in the manufacture of such electric machines and their use. More particularly, the 100 electric machine according to the present invention can be addressed to the technical field of electric mobility, i.e. the 100 electric machine can be a motor for example of a motor vehicle.

Claims

Claims 1. Electric machine (100) comprising: • a first part (101) comprising coils (102) and a second part (103) comprising magnetic elements (104) intended to cooperate magnetically with the coils (102), one of the first and second parts (101, 103) forming a rotor of the electric machine (100) capable of performing a rotational movement along an axis (Al) of rotation; • a power conversion system (105), the coils (102) being electrically connected to the power conversion system (105); • a first power bus (106) and a second power bus (107); • a connection of the power conversion system (105) to the first power bus (106) and to the second power bus (107); the electric machine (100) being configured so that one of the first and second power buses (106, 107) is intended to be connected to ground.

2. Electric machine (100) according to claim 1, characterized in that it comprises a frame (112) having a reference potential forming the ground to which said one of the first and second power buses (106, 107) is connected, preferably the reference potential is intended to be connected to the ground according to a ground connection scheme.

3. Electrical machine (100) according to any one of claims 1 to 2, characterized in that it comprises separate elementary magnetic switching modules (115) each comprising: • only one of the coils (102); • a switching cell (116) secured to the coil (102) of said elementary magnetic switching module (115) and electrically connected to the coil (102) of said elementary magnetic switching module (115); the elementary magnetic switching modules (115) being distributed radially around the axis (Al) of rotation, the power conversion system (105) comprising the switching cells (116), the connection being such that each switching cell (116) is electrically connected to the first power bus (106) and to the second power bus (107) so that all the switching cells (116) are electrically connected in parallel.

4. Electric machine (100) according to claim 3, characterized in that each elementary magnetic switching module (115) is configured to allow a transfer of energy, independently of the others of the elementary magnetic switching modules (115), between the coil (102) which it comprises and the first and second power buses (106, 117).

5. Electrical machine (100) according to any one of claims 3 to 4, characterized in that it comprises a control device (117) for controlling the operation of the power conversion system (105), the power conversion system (105) comprising all of the switching cells (116).

6. Electric machine (100) according to claim 5, characterized in that each coil (102) comprises a first terminal (118a) and a second terminal (118b), in that each elementary magnetic switching module (115) is such that: • the switching cell (116) of said elementary magnetic switching module (115) comprises a first connection terminal (119a) electrically connected to the first power bus (106), a second connection terminal (119b) electrically connected to the second power bus (107) and a third connection terminal (119c), the first terminal (118a) of the coil, electrically connected to said switching cell (116), being electrically connected to the third connection terminal (119c); • the switching cell (116) of said elementary magnetic switching module (115) comprises a switch (120) and a diode (121), said switch (120) being electrically connected, on the one hand, to the first connection terminal (119a) of said switching cell (116) and, on the other hand, both to the second connection terminal (119b) of said switching cell (116) via said diode (121) passing towards the second connection terminal (119b) of said switching cell (116) and to the third connection terminal (119c), the switch (120) of said switching cell (116) being configured to be controlled by the control device (117);and in that the power conversion system (105) comprises a branch (122) connecting the first power bus (106) and the second power bus (107), the branch comprising, successively from the first power bus (106) to the second power bus (107): a diode (123) passing only in the direction of the second power bus (107); a connection point (124) of the coils (102) electrically connected to the second terminal (118b) of each of the coils (102); • a switch (125) configured to be controlled by the control device (117).

7. Electric machine (100) according to any one of claims 3 to 6, characterized in that: • it comprises a first printed circuit (126) on which the first and second power buses (106, 107) are mounted; • each elementary magnetic switching module (115) comprises a second printed circuit (127) specific to it and supporting components of the switching cell (116) of said elementary magnetic switching module (115), the coil (102) of said elementary magnetic switching module (115) being electrically connected to said second printed circuit (127) and mechanically fixed relative to said second printed circuit 127; • the second printed circuits (127) are connected to the first printed circuit (126) so as to provide electrical connection logic for the switching cells (116) to the first power bus (106) and to the second power bus (107).

8. Electric machine (100) according to claim 7, characterized in that each elementary magnetic switching module (115) comprises a material (128) mechanically and thermally securing its second circuit (127) and its coil (102).

9. Electric machine (100) according to claim 6 and any one of claims 7 to 8, characterized in that: • it comprises a third printed circuit (137) separate from the first printed circuit (126) and the second printed circuits (127); • for each switching cell (116), the components of said switching cell (116) comprise the switch (120) of said switching cell (116), and the diode (121) of said switching cell (116); • the diode (123) of the branch (122) is electrically connected to all the elementary magnetic switching modules (115) in order to ensure, depending on the control of the power conversion system (105), a freewheel phase for all or part of the elementary magnetic switching modules (115), the diode (123) of the branch (122) being mounted on the third printed circuit (137); • the switch (125) of the branch (122) is electrically connected to all the elementary magnetic switching modules (115) and is configured to be controlled in order to ensure, depending on the control of the power conversion system (105), a demagnetization phase for all or part of the elementary magnetic switching modules (115), the switch (125) of the branch (122) being mounted on the third printed circuit (137).

10. Electrical machine (100) according to claim 6 or claim 6 and any one of claims 7 to 9, characterized in that the switch (120) of each switching cell (116) is a transistor, the switch (125) of the branch (122) is a transistor and the control device (117) is electrically connected to a control electrode (120a) of each of the switches (120) of the switching cells (116) and to a control electrode (125a) of the switch (125) of the branch (122).

11. An electrical machine (100) according to claim 5 or claim 5 and any one of claims 6 to 10, characterized in that the control device (117) comprises a first control module (117a) and at least one second control module (117b), the first control module (117a) being configured to generate digital control signals and the second control module (117b) being configured to shape at least one digital control signal, received from the first control module (117a), to at least one actuator of the power conversion system (105), the distance separating said second control module (117b) from said at least one actuator (120, 125) being less than the distance separating said first control module (117a) from said at least one actuator (120, 125).

12. Electric machine (100) according to claim 3 or according to claim 3 and any one of claims 4 to 11, characterized in that the electric machine (100) comprises a casing (113) in which the elementary magnetic switching modules (115) are arranged and in that each switching cell (116) is thermally coupled to the casing (113) to ensure a heat exchange between said switching cell (116) and the casing (113).

13. Device (1000) for producing energy comprising an electric machine (100) according to any one of claims 1 to 12 of which said one of the first and second power buses (106, 107) is connected to ground.

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