Rotor arrangement, electric machine and method

Abstract

A rotor arrangement (50) comprises a rotor core (52), first permanent magnets (71) and second permanent magnets (72), wherein the first permanent magnets (71) have a first magnetic material with a first magnetic coercive field strength and the second permanent magnets (72) have a second magnetic material with a second magnetic coercive field strength, wherein the first magnetic coercive field strength is higher than the second magnetic coercive field strength, wherein the rotor arrangement (50) alternately comprises two adjacent first pole regions (68, 61; 64, 65) with the first permanent magnets (71) and two adjacent second pole regions (62, 63; 66, 67) with the second permanent magnets (72), wherein the two adjacent first pole regions (68, 61;64, 65) are magnetized oppositely to each other in order to enable a first number of poles of the rotor arrangement (50) by remagnetizing the second pole regions (62, 63, 66, 67) opposite to the respective adjacent first pole region (68, 61, 64, 65) and to enable a second number of poles of the rotor arrangement (50) by remagnetizing the second pole regions (62, 63, 66, 67) in accordance with the respective adjacent first pole region (68, 61, 64, 65), wherein the first number of poles is twice as large as the second number of poles.;

Description

[0001] The invention relates to a rotor arrangement, an electric machine and a method for operating an electric machine.

[0002] EP 2 246 961 A1 shows a permanent magnet rotor in which a magnetic pole is formed from a first permanent magnet (71) and a second permanent magnet (72), wherein the products of the coercive force are different with the magnetization direction.

[0003] The JP 5 355 055 B2 shows a rotor that has magnets with variable magnetic force and magnets with fixed magnetic force.

[0004] The JP 6 371 550 B2 shows an electric machine in which a permanent magnet is magnetized by a magnetic field, the magnetic field being formed by an armature current.

[0005] EP 2 360 814 B1 shows a rotor with a rotor core and rotor poles, using two or more types of permanent magnets.

[0006] EP 2 136 467 B1 shows a permanent magnet rotor arrangement in which two types of permanent magnets with different shapes or different magnetic properties are used.

[0007] The CN 114 498 983 B shows a motor with adjustable magnetic flux and variable magnetic circuit with three sections and series / parallel connection.

[0008] It is therefore an object of the invention to provide a new rotor arrangement, a new electric machine and a new method for operating an electric machine.

[0009] This problem is solved by the subject matter of claim 1 and the dependent claims.

[0010] A rotor assembly comprises a rotor core, first permanent magnets, and second permanent magnets, wherein the first permanent magnets have a first magnetic material with a first magnetic coercive field strength, and the second permanent magnets have a second magnetic material with a second magnetic coercive field strength, wherein the first magnetic coercive field strength is higher than the second magnetic coercive field strength, wherein the rotor assembly alternately has two adjacent first pole regions with the first permanent magnets and two adjacent second pole regions with the second permanent magnets, wherein the two adjacent first pole regions are magnetized oppositely to each other.The rotor arrangement is designed to enable a first number of poles by remagnetizing the second pole regions in the opposite direction to the adjacent first pole region, and to enable a second number of poles by remagnetizing the second pole regions in the same direction as the adjacent first pole region, with the first number of poles being twice the second number of poles. The rotor arrangement allows for a change in the number of rotor poles, requiring the remagnetization of only half of the pole regions. Changing the number of poles allows for influencing machine characteristics such as the torque-speed characteristic or the efficiency.

[0011] According to a preferred embodiment, the first magnet material comprises neodymium-iron-boron. This magnet material has a high coercive field strength and enables a high torque.

[0012] According to a preferred embodiment, the first magnetic material has a magnetic coercive field strength which is greater than at least one first limiting coercive field strength from a first group consisting of: - 400,000 A / m, - 500,000 A / m, - 600,000 A / m, and - 700,000 A / m.

[0013] Magnet reversal can be easily avoided at these coercive field strengths.

[0014] According to a preferred embodiment, the second magnetic material comprises at least one magnetic material from a group of magnetic materials consisting of: - Aluminum-nickel-cobalt, and - Iron nitride.

[0015] These magnetic materials can be easily remagnetized.

[0016] According to a preferred embodiment, the second magnetic material has a magnetic coercive field strength which is smaller than at least a second limiting coercive field strength from a second group consisting of: - 300,000 A / m, - 250,000 A / m, - 200,000 A / m, and - 150,000 A / m.

[0017] A remagnetization can be achieved in this way.

[0018] According to a preferred embodiment, an electric machine has such a rotor arrangement, a stator arrangement and a current supply arrangement, wherein the stator arrangement has a winding arrangement, and wherein the current supply arrangement is configured to - in an operating mode to energize the winding arrangement to generate torque in the rotor arrangement and - to perform a remagnetization of the second pole areas in a configuration mode by energizing the winding arrangement.

[0019] Such an electric machine has many uses.

[0020] A method for operating an electric machine, wherein the electric machine comprises a rotor arrangement, a stator arrangement, and a current supply arrangement, wherein the stator arrangement comprises a winding arrangement, wherein the rotor arrangement comprises a rotor core, first permanent magnets, and second permanent magnets, wherein the first permanent magnets comprise a first magnetic material with a first coercive field strength, and the second permanent magnets comprise a second magnetic material with a second coercive field strength, wherein the first coercive field strength is higher than the second coercive field strength, and wherein the rotor arrangement alternately comprises two adjacent first pole regions with the first permanent magnets and two adjacent second pole regions with the second permanent magnets, wherein the two adjacent first pole regions are magnetized oppositely to each other, and comprises the following steps: A) Under a given first condition, the second pole regions are remagnetized by energizing the winding arrangement using the energizing arrangement into a first configuration state in which the second pole regions are magnetized opposite to the respective adjacent first pole region in order to effect a first number of poles of the rotor arrangement, and B) Under a given second condition, the second pole regions are remagnetized into a second configuration state by energizing the winding arrangement using the energizing arrangement, in which the second pole regions are magnetized according to the respective adjacent first pole region in order to effect a second number of poles of the rotor arrangement, wherein the first number of poles is twice as large as the second number of poles.

[0021] This allows for the targeted setting of a configuration state.

[0022] According to a preferred embodiment, the method comprises the following step: C) The winding arrangement is energized by the current-energizing arrangement to generate a torque in the rotor arrangement, the current-energizing being carried out depending on whether the second pole regions are in the first configuration state or in the second configuration state.

[0023] The winding arrangement can therefore be operated for both configuration states.

[0024] According to a preferred embodiment, the method comprises the following step: D) Under a specified third condition, the second pole regions are brought into a third configuration state by energizing the winding arrangement using the energizing arrangement, in which the second pole regions are demagnetized.

[0025] Further details and advantageous embodiments of the invention will become apparent from the exemplary embodiments described below and illustrated in the drawings, which are in no way to be understood as limiting the invention, as well as from the dependent claims. It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the present invention. It shows: Fig. 1 in a schematic representation a vehicle with an electric motor, Fig. 2 in a schematic top view the electric machine of Fig. 1 in a first state, Fig. 3 in a schematic top view the electric machine of Fig. 1 in a second state, Fig. 4 in a schematic top view the electric machine of Fig. 1 in a third state, and Fig. 5 a bra characteristic curve of two permanent magnetic materials.

[0026] In the following, identical or similarly functioning parts are designated with the same reference symbols and are usually described only once. The description builds upon itself across figures to avoid unnecessary repetition.

[0027] Fig. Figure 1 shows a schematically indicated vehicle 10 with an electric machine 20.

[0028] Vehicle 10 is preferably a battery-powered electric vehicle or a hybrid vehicle.

[0029] The electric machine 20 has a rotor arrangement 50, a stator arrangement 30 and a current supply arrangement 23.

[0030] The stator arrangement 30 has a winding arrangement 39 and preferably a stator core 40. The stator core 40 is, for example, designed as a laminated core.

[0031] In the exemplary embodiment, the winding arrangement 39 has eight windings 31 to 38. In the exemplary embodiment, the windings 31 to 38 are designed as concentrated windings, but they can also be designed as distributed windings.

[0032] Preferably, the windings 31 to 38 can each be individually controlled by the current supply arrangement 23.

[0033] The power supply arrangement 23 includes, for example, an inverter, in particular a pulse inverter.

[0034] In this diagram, each of the windings 31 to 38 can be individually energized. A combination of windings is also possible, for example as a delta or star connection.

[0035] Fig. Figure 2 shows the electric machine 20 with the stator arrangement 30 and the rotor arrangement 50.

[0036] The rotor arrangement 50 has a rotor core 52 and pole areas 61 to 68.

[0037] In pole areas 61, 64, 65 and 68, first permanent magnets 71 are provided, and these pole areas are hereinafter referred to as first pole areas.

[0038] Second permanent magnets 72 are provided in pole areas 62, 63, 66 and 67, and these pole areas are referred to below as second pole areas.

[0039] The first permanent magnets 71 have a first magnetic material with a first magnetic coercive field strength, and the second permanent magnets 72 have a second magnetic material with a second magnetic coercive field strength, wherein the first magnetic coercive field strength is higher than the second magnetic coercive field strength.

[0040] As magnetic coercive field strength Hc The term coercive field strength refers to the magnetic field strength required to demagnetize a ferromagnetic material previously charged to saturation flux density, such that the resulting total flux or local flux density is zero. The higher the coercive field strength, the better a magnetic material retains its magnetization when exposed to an opposing field.

[0041] As coercive field strength H c The coercive field strength H is given here. cJ used for magnetic polarization.

[0042] As shown, the rotor arrangement 50 has alternating two adjacent first pole areas 68 and 61 or 64 and 65 with the first permanent magnets 71 and two adjacent second pole areas 62 and 63 or 66 and 67 with the second permanent magnets 72.

[0043] In each of the pole areas 61 to 68, one permanent magnet 71 or 72 or several permanent magnets 71 or 72 can be provided.

[0044] The permanent magnets 71 and 72 can be arranged in a surface array or as embedded magnets. In the exemplary embodiment, the permanent magnets 71 and 72 are arranged as embedded magnets in a V-shape with two layers. In the exemplary embodiment, each pole region 61 to 68 contains four permanent magnets 71 and 72, respectively.

[0045] The two adjacent first pole regions 68 and 61 or 64 and 65 are magnetized in opposite directions.

[0046] The first magnet material preferably consists of neodymium-iron-boron. Neodymium-iron-boron has a high magnetic coercivity of 800 × 10⁻⁶. 3 A / m up to 950 · 10 3 A / m. It is therefore difficult to remagnetize such a magnetic material. A high field strength is required for demagnetization.

[0047] The first magnetic material preferably has a magnetic coercive field strength that is greater than at least one first limiting coercive field strength from a first group consisting of: - 400,000 A / m, - 500,000 A / m, - 600,000 A / m, and - 700,000 A / m.

[0048] Such magnetic materials advantageously retain their magnetization.

[0049] Preferably the second magnetic material comprises at least one magnetic material from a group of magnetic materials consisting of: - Aluminum-nickel-cobalt, and - Iron nitride.

[0050] Aluminium-nickel-cobalt has a comparatively low coercive field strength of 30 · 10 3 A / m up to 150 · 10 3 A / m. It is therefore relatively easy to remagnetize such a magnetic material.

[0051] The second magnetic material preferably has a magnetic coercive field strength that is smaller than at least a second limiting coercive field strength from a second group consisting of: - 300,000 A / m, - 250,000 A / m, - 200,000 A / m, and - 150,000 A / m.

[0052] Such magnetic materials can be more easily remagnetized.

[0053] By using the second magnetic material, it becomes possible to remagnetize the second permanent magnets 72 by applying a strong current to the winding arrangement 39. This strong current is preferably applied as a short current pulse with high current intensity and thus high field strength. The first magnetic material, with the higher coercive field strength, retains its magnetization direction.

[0054] In the exemplary embodiment, pole area 68 towards the stator 30 is a south pole, pole area 61 is a north pole, pole area 64 is a south pole and pole area 65 is a north pole.

[0055] In the exemplary embodiment, the current magnetization is such that pole region 62 is a south pole, pole region 63 is a north pole, pole region 66 is a south pole and pole region 67 is a north pole.

[0056] Thus, the second pole regions 62, 63, 66 and 67 are magnetized in the opposite direction to the respective adjacent first pole regions 61, 64, 65 and 68, respectively, and in this state the rotor arrangement 50 has a first number of eight poles.

[0057] This is referred to as the first configuration state.

[0058] Fig. Figure 3 shows the rotor arrangement 50 in a second configuration state. The first pole regions 61, 64, 65, 68 are unchanged. The second pole regions 62, 63, 66, 67 are remagnetized so that they are each magnetized in a direction corresponding to the adjacent first pole region 61, 64, 65 and 68.

[0059] In the exemplary embodiment, pole areas 61 and 62 are therefore north poles towards the stator 30, pole areas 63 and 64 are south poles, pole areas 65 and 66 are north poles and pole areas 67 and 68 are south poles.

[0060] Two adjacent pole areas with the same magnetization act as one larger common pole area. As a result, the rotor arrangement 50 has a second number of poles of four; the first number of poles is thus twice as large as the second number of poles.

[0061] The number of poles influences the characteristics of the electric machine 20. For example, a low number of poles can be advantageous for high speeds because the electrical frequency in the machine is reduced, resulting in lower iron losses. Conversely, a higher number of poles can be advantageous for high torque at low speeds.

[0062] Preferably, the first and second configuration states are set automatically depending on the operating point of the electric machine. However, the configuration state can also be set based on user input. This allows the operating ranges and efficiency to be influenced by the remagnetization.

[0063] Changing the number of poles in the rotor arrangement also necessitates an adjustment of the current supply arrangement 23. For this purpose, it is advantageous if the windings 31 to 38 can be controlled at least partially independently of one another.

[0064] In the exemplary embodiment of Fig. 1 The stator arrangement has eight stator poles 31 to 38. Multiphase electric machines 20 are preferably used as the drive, in particular a three-phase electric machine 20. The number of poles of the stator 30 preferably corresponds to the number of rotor poles.

[0065] The current supply arrangement 23 is preferably designed to - in an operating mode to energize the winding arrangement 39 to generate a torque in the rotor arrangement 50 and - to perform a remagnetization of the second pole areas 62, 63, 66, 67 in a configuration mode by energizing the winding arrangement 39.

[0066] Remagnetization requires very high magnetic fields and therefore very high currents through the corresponding windings. This is preferably achieved by generating short current pulses with high current intensity. The short duration of these pulses prevents damage to the winding.

[0067] The method for operating the electric machine 20 can be described as follows: A) Under a given first condition, the second pole regions 62, 63, 66, 67 are remagnetized into a first configuration state by energizing the winding arrangement 39 using the energizing arrangement 23, in which the second pole regions 62, 63, 66, 67 are magnetized opposite to the respective adjacent first pole region 61, 64, 65, 68 in order to effect a first number of poles of the rotor arrangement 50, and B) Under a given second condition, the second pole regions 62, 63, 66, 67 are remagnetized into a second configuration state by energizing the winding arrangement 39 using the energizing arrangement 23, in which the second pole regions 62, 63, 66, 67 are magnetized according to the respective adjacent first pole region 61, 64, 65, 68 in order to effect a second number of poles of the rotor arrangement 50, wherein the first number of poles is twice as large as the second number of poles.

[0068] The procedure preferably includes the following step: C) The winding arrangement 39 is energized by the current-energizing arrangement 23 to generate torque in the rotor arrangement 50, the energizing being carried out depending on whether the second pole sections 62, 63, 66, 67 are in the first configuration state or the second configuration state. The energizing for driving or braking torque generation is thus adapted to the current configuration state.

[0069] Fig. Figure 4 shows a third configuration state in which the second pole regions 62, 63, 66, 67 are demagnetized. This prevents them from acting as magnetic rotor poles. This is advantageous, for example, to reduce drag losses during idling.

[0070] A corresponding procedure preferably includes the following step: D) Under a predetermined third condition, the second pole regions 62, 63, 66, 67 are brought into a third configuration state by energizing the winding arrangement 39 using the energizing arrangement 23, in which the second pole regions 62, 63, 66, 67 are demagnetized. This leaves only the four poles of the first pole regions 61.

[0071] Fig. Figure 5 shows a BH characteristic curve in which the remanent flux density B is plotted against the magnetic field H.

[0072] Line 91 is typical for a first magnetic material with high coercive field strength.

[0073] Line 92 is typical for a second magnetic material with low coercive field strength.

[0074] The first magnetic material has increased resistance to demagnetization and is not affected during the magnetization of the second magnetic material.

[0075] Naturally, various variations and modifications are possible within the scope of the present invention.

[0076] In a simple embodiment, only two first pole regions and two second pole regions are provided. More pole regions can also be provided, for example, six first pole regions and six second pole regions. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 2 246 961 A1

[0002] JP 5 355 055 B2

[0003] JP 6 371 550 B2

[0004] EP 2 360 814 B1

[0005] EP 2 136 467 B1

[0006] CN 114 498 983 B

[0007]

Claims

[1] Rotor arrangement (50) comprising a rotor core (52), first permanent magnets (71) and second permanent magnets (72), wherein the first permanent magnets (71) comprise a first magnetic material with a first magnetic coercive field strength and the second permanent magnets (72) comprise a second magnetic material with a second magnetic coercive field strength, wherein the first magnetic coercive field strength is higher than the second magnetic coercive field strength, wherein the rotor arrangement (50) alternately comprises two adjacent first pole regions (68, 61; 64, 65) with the first permanent magnets (71) and two adjacent second pole regions (62, 63; 66, 67) with the second permanent magnets (72), wherein the two adjacent first pole regions (68, 61;64, 65) are magnetized oppositely to each other in order to enable a first number of poles of the rotor arrangement (50) by remagnetizing the second pole regions (62, 63, 66, 67) opposite to the respective adjacent first pole region (68, 61, 64, 65) and to enable a second number of poles of the rotor arrangement (50) by remagnetizing the second pole regions (62, 63, 66, 67) in accordance with the respective adjacent first pole region (68, 61, 64, 65), wherein the first number of poles is twice as large as the second number of poles.; [2] Rotor arrangement (50) according to claim 1, wherein the first magnet material comprises neodymium-iron-boron. [3] Rotor arrangement (50) according to claim 1 or 2, wherein the first magnetic material has a magnetic coercive field strength which is greater than at least one first limiting coercive field strength from a first group consisting of: - 400,000 A / m, - 500,000 A / m, - 600,000 A / m, and - 700,000 A / m. [4] Rotor arrangement (50) according to one of the preceding claims, wherein the second magnet material comprises at least one magnet material from a group of magnet materials consisting of: - Aluminum-nickel-cobalt, and - Iron nitride. [5] Rotor arrangement (50) according to one of the preceding claims, wherein the second magnet material has a magnetic coercive field strength which is smaller than at least a second limiting coercive field strength from a second group consisting of: - 300,000 A / m, - 250,000 A / m, - 200,000 A / m, and - 150,000 A / m. [6] Electric machine (20) comprising a rotor arrangement (50) according to one of the preceding claims, a stator arrangement (30) and a current supply arrangement (23), wherein the stator arrangement (30) comprises a winding arrangement (39), and wherein the current supply arrangement (23) is designed to - in an operating mode to energize the winding arrangement (39) to generate a torque in the rotor arrangement (50) and - to perform a remagnetization of the second pole areas (62, 63, 66, 67) in a configuration mode by energizing the winding arrangement (39). [7] Method for operating an electric machine (20), wherein the electric machine (20) comprises a rotor assembly (50), a stator assembly (30) and a current supply assembly (23), wherein the stator assembly (30) comprises a winding assembly (39), wherein the rotor assembly (50) comprises a rotor core (52), first permanent magnets (71) and second permanent magnets (72), wherein the first permanent magnets (71) comprise a first magnetic material with a first coercive field strength and the second permanent magnets (72) comprise a second magnetic material with a second coercive field strength, wherein the first coercive field strength is higher than the second coercive field strength, wherein the rotor assembly (50) alternately comprises two adjacent first pole regions (68, 61; 64, 65) with the first permanent magnets (71) and two adjacent second pole regions (62, 63; 66, 67) with the second permanent magnets (72) wherein the two adjacent first pole regions (68, 61;64, 65) are magnetized oppositely to each other, the method comprising the following steps:; A) Under a given first condition, the second pole regions (62, 63, 66, 67) are remagnetized into a first configuration state by energizing the winding arrangement (39) using the energizing arrangement (23), in which the second pole regions (62, 63, 66, 67) are magnetized opposite to the respective adjacent first pole region (68, 61; 64, 65) in order to effect a first number of poles of the rotor arrangement (50), and B) under a given second condition, the second pole regions (62, 63, 66, 67) are remagnetized into a second configuration state by energizing the winding arrangement (39) using the energizing arrangement (23), in which the second pole regions (62, 63, 66, 67) are magnetized according to the respective adjacent first pole region (68, 61, 64, 65) in order to effect a second number of poles of the rotor arrangement (50), wherein the first number of poles is twice as large as the second number of poles. [8] The method of claim 7, comprising the following step: C) The winding arrangement (39) is energized by the current supply arrangement (23) to generate a torque in the rotor arrangement (50), the current supply being carried out depending on whether the second pole regions (62, 63, 66, 67) are in the first configuration state or in the second configuration state. [9] The method of claim 7 or 8, comprising the following step: D) Under a specified third condition, the second pole regions (62, 63, 66, 67) are brought into a third configuration state by energizing the winding arrangement (39) using the energizing arrangement (23), in which the second pole regions (62, 63, 66, 67) are demagnetized.

Images