Method, stator and system for dynamic stator-rotor configuration of a permanent magnet synchronous machine

Abstract

The present invention relates to a method for the dynamic stator-rotor configuration of a permanent magnet synchronous machine, which comprises a rotor and a stator (100) with a plurality of iron-containing stator teeth (102). Each stator tooth (102) can be separated into a tooth stub (192) and a tooth tip (191), wherein the tooth stub and tooth tip form an intermeshing tongue and groove connection that is tensile in the radial direction of the stator, and the tooth tip is displaceable on the tooth stub in the axial direction of the stator. The tooth tips are connected to one another at one axial end of the stator via a ring having corresponding eyelets (112) with threaded drives.During operation of the permanent magnet synchronous machine, the entirety of the tooth tips (111) is displaced in the axial direction of the stator by means of at least two actuator motors (303) via threaded rods (301) and corresponding screw drives, thus dynamically varying the magnetic air gap field between the stator and rotor within the range of the displacement. The stator-rotor combination is modified by reducing the amount of iron material penetrated by a varying magnetic field with a respective magnetic flux density during operation of the permanent magnet synchronous machine, thereby reducing remagnetization losses. Furthermore, a segmentable stator and a system are presented with which the method can be implemented.

Description

[0001] The present invention relates to a method for dynamic stator-rotor configuration of a permanent magnet synchronous machine, which can reduce partial load losses. Furthermore, a segmentable stator and a system are presented with which the method can be implemented.

[0002] When using an electric vehicle, a wide variety of operating points occur depending on the driver's user profile. When designing a traction drive, a compromise must be found regarding losses occurring at different speeds and torques. A high magnetic flux density of an air gap field is advantageous for reducing losses during operation at low speeds and generating high torque, since losses in this operating range are primarily due to thermal losses and depend on the square of the phase current. With a higher magnetic air gap flux density, depending on the saturation state of the electrical steel sheet, the same torque can be generated with less phase current and thus lower thermal losses.However, operation at high speeds and low torque results in increased losses, as remagnetization losses, consisting of eddy current, hysteresis, and additional losses, depend on the speed and the square of the magnetic flux density. To accommodate different applications, such as highway or city traffic, it is therefore very advantageous to adapt the magnetic flux density during operation of the electric machine. State-of-the-art concepts using permanently buried permanent magnets and adjustable round bar magnets are known for this purpose. By rotating the round bar magnets, it is possible to align them with the magnetic field of the fixed magnets or to counteract it. Depending on the angle of rotation, this results in a strengthened or weakened magnetic air gap field.

[0003] The document DE 10 2021 109 653 A1 discusses a stator for an electrical machine in which a dovetail connection can be formed between a tooth shoe and the stator tooth at a radial end of a stator tooth, which is arranged on a stator yoke and firmly connected thereto.

[0004] Document DE 10 2015 110 652 A1 discloses a rotor-stator arrangement of a hybrid-excited synchronous machine, the rotor of which consists of an inner and an outer part. The inner and outer parts are connected via a dovetail joint.

[0005] The publication DE 10 2006 043 673 A1 describes a synchronous machine whose stator winding is arranged on every second stator tooth, separated as so-called main teeth from so-called follower teeth. Each main tooth has a substantially circular cross-section, so that a reduced iron cross-section is formed between the main teeth and the follower teeth, and the magnetic resistance at the air gap between the stator and rotor is essentially balanced between the main teeth and the follower teeth.

[0006] The publication US 2013 / 0 162 096 A1 describes an electrical machine in which a portion of each stator tooth is divided into a first and a second tooth section. Both tooth sections can be rotated relative to each other between a first position, in which the magnetic resistance between the tooth sections is low, and a second position, in which the magnetic resistance is relatively greater than in the first position, with the rotational axis being the rotor axis.

[0007] The document DE 10 2006 036 986 A1 deals with an electric motor with a mechanical field weakening device, which causes an axial displacement of a stator relative to the rotor, whereby a winding of the stator which is subjected to winding current can only partially act on a magnetic excitation field of the rotor, depending on the displacement.

[0008] Against this background, it is an object of the present invention to present a method for a permanent magnet synchronous machine that adapts the magnetic resistance between the stator and rotor to a specific requirement profile for a specific torque at a specific speed. This should make it possible to reduce remagnetization losses at high speeds. Furthermore, a device and a system with which the method can be implemented are to be presented.

[0009] To achieve the aforementioned objective, a method for dynamic stator-rotor configuration of a permanent magnet synchronous machine is proposed. The permanent magnet synchronous machine comprises a rotor and a stator with a plurality of iron-containing stator teeth, each stator tooth being separable into a tooth stub and a tooth tip. The tooth stub and tooth tip form an intermeshing tongue-and-groove connection that is tensile in the radial direction of the stator, with the tooth tip being displaceable on the tooth stub in the axial direction of the stator. The tooth tips are connected to one another at one axial end of the stator via a ring, for example, by means of a material connection.During operation of the permanent magnet synchronous machine, a magnetic air gap field between the stator and rotor in the area of the pushed-out stator tooth tips is dynamically varied by shifting the entire set of tooth tips in the axial direction of the stator.

[0010] In principle, the magnetic resistance changes with the variation of the air gap height, since air has a lower magnetic conductivity than, for example, iron electrical steel. By shifting the stator tooth tips, the air gap height and thus the magnetic resistance are increased in the area of the extended tooth tips, thereby reducing the magnetic air gap field and thus the remagnetization losses.

[0011] In one embodiment of the method according to the invention, the tongue and groove connection which is tensile in the radial direction of the stator is formed with a shape from the following list: T-shaped, wedge-shaped, dovetail-shaped.

[0012] In a further embodiment of the method according to the invention, the stator-rotor combination is modified by shifting the entire tooth tips out of the stator by a predetermined shift length, thereby reducing the amount of iron material that is penetrated by a varying magnetic field with a respective magnetic flux density during operation of the permanent magnet synchronous machine. At the same time, the magnetic resistance and thus the magnetic flux density in this region of the thus segmentable stator increase due to the lower magnetic conductivity of air compared to the tooth tips shifted out over the predetermined shift length.

[0013] In a further embodiment of the method according to the invention, the respective magnetic flux density is adjusted according to a respective operating point of the permanent magnet synchronous machine for a respective torque and a respective speed via a current flowing in coil windings guided around the stator teeth. The predetermined displacement length is determined by the respective operating point.

[0014] It is conceivable to adjust the displacement length specified by the respective operating point, for example, via at least two actuator motors, wherein the at least two actuator motors displace the entirety of the tooth tips within the stator.

[0015] In a further embodiment of the method according to the invention, a maximum displacement length is specified for operating points with high speeds and simultaneously low torque.

[0016] The maximum displacement length by which the entire tooth tips are displaced on the tooth stumps is, for example, 36% of the axial length of the stator. Depending on the design of the permanent magnet synchronous machine, this advantageously does not require any increase in installation space.

[0017] Furthermore, a stator for the dynamic stator-rotor configuration of a permanent magnet synchronous machine is claimed. The permanent magnet synchronous machine comprises a rotor and the stator, wherein the stator has a plurality of iron-containing stator teeth and a coil winding guided accordingly around the stator teeth. Each stator tooth is separable into a tooth stub and a tooth tip, wherein the tooth stub and tooth tip have an intermeshing tongue-and-groove connection that is tensile in the radial direction of the stator, and the tooth tip is displaceable on the tooth stub in the axial direction of the stator. The tooth tips are connected to one another at one axial end of the stator via a ring.The stator is designed to dynamically vary a magnetic air gap field between the stator and rotor during operation of the permanent magnet synchronous machine by shifting the entirety of the tooth tips in the axial direction of the stator and, in order to reduce magnetization losses, to reduce a quantity of iron material which is penetrated by a varying magnetic field with a respective magnetic flux density during operation of the permanent magnet synchronous machine when shifting the entirety of the tooth tips from the stator by a predetermined shift length.

[0018] The stator according to the invention represents a novel stator topology segmented into tooth stumps and tooth tips, wherein the tooth tips are adjustable, thus advantageously altering the magnetic resistance for the magnetic air gap field for part of the permanent magnet synchronous machine. This further advantageously makes it possible to significantly reduce the remagnetization losses at high speeds within the stator – for example, by up to 25% – while maintaining the same installation space. Furthermore, it is advantageously possible to increase torque at maximum speed, since less negative d-current needs to be regulated. In the case of an active short circuit, it is also conceivable to reduce a maximum transient short-circuit current, since less magnetic flux is interlinked in the coil windings at the time of a short circuit.This concept is particularly advantageous for permanent magnet synchronous machines with high magnet utilization and stator iron mass, which otherwise have high magnetization losses at high speeds.

[0019] In one embodiment of the stator according to the invention, the tongue and groove connection which is tensile in the radial direction of the stator has a shape from the following list: T-shaped, wedge-shaped, dovetail-shaped.

[0020] In a further embodiment of the stator according to the invention, the stator comprises at least two actuator motors. The at least two actuator motors are designed to displace the tooth tips. It is conceivable to arrange the at least two actuator motors, for example, on a bearing plate of a non-output side of the permanent magnet synchronous machine. The displacement of all the tooth tips, which are connected to one another via a ring made of, for example, sheet iron, for example by means of a material bond, is implemented, for example, by means of at least two threaded rods rotated by the at least two actuator motors, which axially displace the ring via eyelets with screw drives attached to the ring.

[0021] Furthermore, a system for dynamic stator-rotor configuration of a permanent magnet synchronous machine is claimed, which comprises the permanent magnet synchronous machine with a rotor and a stator according to the invention. The system is configured to carry out a method according to the invention, whereby the entirety of tooth tips connected to one another via the ring can be displaced by the predetermined displacement length and is displaced in order to vary the magnetic air gap field over the range of the displacement length between the stator and rotor.

[0022] In one embodiment of the system according to the invention, the system comprises a controller with a memory unit. The system is configured to carry out a method according to the invention in that the memory unit has a table with a respective displacement length assigned to a respective phase current value at a respective operating point of the permanent magnet synchronous machine. The controller is designed to adjust the respective current flowing in the coil windings guided around the stator teeth, determined by means of the table, according to the respective operating point for a respective torque and a respective speed, and to specify the respective displacement length. Values stored in the table are determined, for example, based on a special calculation method. It is conceivable to make the special calculation method available to the controller as an algorithm, thus eliminating the need for the table.On the other hand, it is conceivable that values entered in the table are determined on a test bench for a specific permanent magnet synchronous machine.

[0023] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

[0024] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

[0025] The characters are described coherently and comprehensively. Fig. 1 shows schematic axial full section and radial section views of an embodiment of the stator according to the invention. Fig. 2 schematically shows two positions of the tooth tips in the design of the stator according to the invention. Fig. 3 shows a schematic full-sectional view of a permanent magnet synchronous machine with the design of the stator according to the invention.

[0026] In Fig. 1 schematically shows an axial full-sectional view 100 and a radial sectional view 199 of an embodiment of the stator according to the invention. A stator yoke 114 has a plurality of segmentable stator teeth 102, in whose respective tooth grooves 103 a set of tooth tips 111 is actively displaceable or is displaced. In the full-sectional view 100, a right winding head 131 is shown on a right side of the stator yoke 114 and a left winding head 132 is shown on a left side of the stator yoke 114. The set of tooth tips 111 is connected at the left end in the full-sectional view 100 via a ring, to which eyelets for receiving a threaded gear 112, for example a ball screw drive, for a respective threaded rod are also attached. When the threaded rods rotate, the set of tooth tips 111 is axially displaced.To allow the entire set of tooth tips 111 to be pushed out of the stator yoke 114, the left-hand winding head 132 in the full-section view 100 is adapted accordingly. The radial sectional view 199 shows, enlarged, the stator yoke 194 with the respective tooth stock 192 and, for example, a dovetail-shaped tooth groove 193, in which the tooth tip 191 can be axially displaced while engaging in the same shape. A notch 197 for the dovetail shape can be, for example, 0.6 mm, whereby a tooth width 195 can be, for example, 5.7 mm and a tooth tip height 196 can be, for example, 6.3 mm.

[0027] In Fig. 2 schematically shows a full-sectional view with retracted tooth tips 210 and a full-sectional view with extended tooth tips 220 in the embodiment of the stator according to the invention. In the full-sectional view 220, the partially exposed tooth stumps of the stator yoke 114 essentially increase the magnetic resistance for a magnetic air gap field over a displacement length of the extended part of the entire set of tooth tips 111. This results from the lower magnetic conductivity of air compared to iron electrical sheets, which are usually used to form a stator. This advantageously reduces the magnetic flux density in a part of the stator and thus the remagnetization losses at high speeds and low torque.

[0028] In Fig.Figure 3 shows a schematic full-sectional view of a permanent magnet synchronous machine with the stator design according to the invention. A rotor 305 is inserted within the stator yoke 114. A ring or sheet iron ring 302, and thus the entire set of tooth tips 111 arranged on it, is displaced by means of threaded rods 301 rotated by actuator motors 303 located on a bearing plate of a non-output side 304 by means of screw drives in the eyelets. In the exemplary design shown, a maximum displacement length is approximately 36% of the active iron length of the permanent magnet synchronous machine, so that advantageously, there is no need to increase the installation space. List of reference symbols 100 Schematic of segmented stator 102 stator tooth 103 Tooth groove 111 Actively movable assembly at tooth tips 112 Eyelet with threaded drive for threaded rod 114 Stator yoke 131 winding head 132 Adapted winding head 191 Removed tooth tip 192 Tooth stump 193 Dovetail groove 194 Stator yoke 195 tooth width 196 tooth tip height 197 incision 199 Sectional view of stator tooth 210 Retracted tooth tips 220 Extended tooth tips 300 Sectional view of permanent magnet synchronous machine 301 threaded rod 302 ring or iron sheet ring 303 actuator motors 304 End shield of the non-drive side 305 Rotor

Claims

[1] Method for the dynamic stator-rotor configuration of a permanent magnet synchronous machine, which comprises a rotor (305) and a stator (100) with a plurality of iron-containing stator teeth (102), wherein the respective stator tooth (102) is separable into a tooth stub (192) and a tooth tip (191), wherein the tooth stub (192) and tooth tip (191) form an intermeshing tongue and groove connection which is tensile in the radial direction of the stator, wherein the tooth tip (191) is displaceable on the tooth stub (192) in the axial direction of the stator (100), in which the tooth tips (191) are connected to one another at an axial end of the stator (100) via a ring (302), and in which dynamically during operation of the permanent magnet synchronous machine by displacing the entirety of the tooth tips (111) in the axial direction of the stator (100) a magnetic air gap field between the stator (100) and rotor (305) is varied in the range of the displacement length. [2] Method according to claim 1, wherein the tongue and groove connection which is tensile in the radial direction of the stator (100) is formed with a shape from the following list: T-shaped, wedge-shaped, dovetail-shaped (193). [3] Method according to one of the preceding claims, in which the stator-rotor combination is modified by shifting the entirety of the tooth tips (111) from the stator (100) by a predetermined shift length, thereby reducing a material quantity of iron which is penetrated by a varying magnetic field with a respective magnetic flux density during operation of the permanent magnet synchronous machine, thereby reducing remagnetization losses. [4] Method according to claim 3, wherein the respective magnetic flux density is to be adjusted according to a respective operating point of the permanent magnet synchronous machine for a respective torque and a respective speed via a current flowing in coil windings guided around the stator teeth (102), in which the predetermined displacement length is predetermined by the respective operating point. [5] Method according to claim 4, in which a maximum displacement length is specified for operating points with high speeds and simultaneously low torque. [6] Stator for the dynamic stator-rotor configuration of a permanent magnet synchronous machine, which comprises a rotor (305) and the stator (100), wherein the stator (100) has a plurality of iron-containing stator teeth (102) and a coil winding correspondingly guided around the stator teeth (102), wherein the respective stator tooth (102) is separable into a tooth stub (192) and a tooth tip (191), wherein the tooth stub (192) and tooth tip (191) have an intermeshing, tensile-resistant tongue and groove connection in the radial direction of the stator (100), and the tooth tip (191) is displaceable on the tooth stator (192) in the axial direction of the stator (100), wherein the tooth tips (191) are connected to one another at an axial end of the stator (100) via a ring (302), wherein the stator (100) is designed toto dynamically vary a magnetic air gap field between the stator (100) and the rotor (305) during operation of the permanent magnet synchronous machine by shifting the entirety of the tooth tips (111) in the axial direction of the stator (100) and, in order to reduce remagnetization losses, to reduce a quantity of iron material which is penetrated by a varying magnetic field with a respective magnetic flux density during operation of the permanent magnet synchronous machine when shifting the entirety of the tooth tips (111) from the stator (100) by a predetermined shift length. [7] Stator according to claim 6, wherein the tongue and groove connection which is tensile in the radial direction of the stator (100) has a shape from the following list: T-shaped, wedge-shaped, dovetail-shaped. [8] Stator according to one of claims 6 or 7, wherein the stator (100) comprises at least two actuator motors (303), wherein the at least two actuator motors (303) are designed to displace the tooth tips (191) via threaded rods (301) by means of screw drives in the respective eyelets (112) of the ring (302). [9] System for dynamic stator-rotor configuration of a permanent magnet synchronous machine, comprising the permanent magnet synchronous machine with a rotor (305) and a stator (100) according to one of claims 6 to 8, wherein the system is configured to carry out a method according to one of claims 1 to 3, whereby the entirety of tooth tips (111) connected to one another via the ring (305) is displaceable by the predetermined displacement length and is displaced in order to vary the magnetic air gap field between the stator (100) and the rotor (305) over the range of the displacement length. [10] System according to claim 9, wherein the system comprises a controller with a memory unit and wherein the system is configured to carry out a method according to one of claims 4 or 5, in that the memory unit has a table with a respective displacement length assigned to a respective current value at a respective operating point of the permanent magnet synchronous machine and wherein the controller is designed to set the respective current flowing in the coil windings guided around the stator teeth (102) determined by means of the table according to the respective operating point for a respective torque and a respective speed and to specify the respective displacement length.

Images