Extreme environment natural electromagnetic magnetic levitation three-phase permanent magnet synchronous motor

Abstract

The invention relates to a three-phase permanent magnet synchronous motor with natural electromagnetic levitation for extreme environments, belonging to the field of magnetic levitation three-phase permanent magnet motors. It solves the problems of high cost of levitation of the motor rotor, high volume of magnetic bearings in magnetic levitation motors, and complex controllers. The start-up protection mechanical bearing clearance at the end of the rotor core is set to 0.1mm to 0.5mm; the stator core is divided into three or more sections, with gaps between adjacent sections; the stator winding is divided into multiple pairs of windings symmetrically distributed along a circumference of 180°; the maximum number of winding pairs per phase is Kpm = Z / (2m), and the tail ends of adjacent windings of each phase are connected in series to form a branch, which is then connected in series with the tail ends of adjacent windings symmetrically distributed at 180° to form another branch. The two symmetrical branches are then connected to form a 180° symmetrical parallel branch, thereby generating three-phase ports of the three-phase winding and a midpoint of the three-phase winding. The invention is primarily used in extreme environments.

Description

Technical Field

[0001] The present invention belongs to the field of magnetic suspension three-phase permanent magnet motors, and in particular relates to a suspension three-phase permanent magnet synchronous motor used in extreme environments. Background Art

[0002] Extreme environments also require motion control components. For example: spacecraft need to operate at high speeds under low temperature conditions, and the life of mechanical bearings is too short. Therefore, motors with suspension capabilities are required. The temperature difference between day and night on the surface of the moon is extremely large, reaching -180℃ to +150℃. Probes and patrol probes working on the moon are exposed to this extreme environment, so servo drive components that can directly operate in this extreme environment are needed. For example: large mechanical equipment used in extreme space environments, manipulators (robots) outside satellite cabins, power generation systems and energy storage systems used in extreme space environments, etc. Similarly: the earth also has extreme environments such as: nuclear radioactive environments, extreme temperature difference environments, sudden dangerous environments, etc.

[0003] The key to overcoming extreme temperature differences is that traditional bearings use negative clearance to improve accuracy. Thermal expansion and contraction of mechanical bearings inevitably lead to damage, seizure, or wear. Therefore, a bearingless design is often chosen to address this challenge.

[0004] However, the cost of levitating a motor's rotor is prohibitive. Typically, the magnetic bearings occupy 60% of the motor's volume, and the controllers for these bearings are expensive and complex. This makes magnetic levitation motors a costly luxury, making them unattainable. Therefore, these issues urgently need to be addressed. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems of high cost of suspending the motor rotor, high volume of magnetic bearings in magnetic levitation motors, and complex controllers. The present invention provides a natural electromagnetic magnetic levitation three-phase permanent magnet synchronous motor in extreme environments.

[0006] The extreme environment natural electromagnetic magnetic levitation three-phase permanent magnet synchronous motor is a fractional slot concentrated winding motor. The ratio of the number of slots to the number of phases of the motor is Z / m, and Z / m is an even number. The windings of each phase of the motor are symmetrically distributed along the circumference of 180° and generate 180° symmetrical couple torques. The motor includes a rotor and a stator sleeved outside the rotor, and the stator is fixed to the stator housing.

[0007] The rotor includes a rotor core and a rotor permanent magnet; the rotor permanent magnet is arranged on the rotor core, and the start-up protection mechanical bearing clearance at the end of the rotor core is set to 0.1mm to 0.5mm;

[0008] The stator includes a stator core and a stator winding. The stator winding is wound on the stator core, and the stator core is axially divided into three or more sections, with a gap between two adjacent sections. The stator winding is a three-phase winding.

[0009] The stator winding is divided into multiple pairs of windings symmetrically distributed along the circumference at 180°; the maximum number of winding pairs per phase is Kpm=Z / (2m), the tail ends of adjacent windings of each phase are connected in series to form a branch, and the tail ends of adjacent windings symmetrically distributed at 180° are connected in series to form another branch, and the two symmetrical branches are then connected to form a 180° symmetrical parallel branch. The principle of parallel connection is: when the number of pole pairs P is an even number, the two symmetrical branch windings are connected in parallel at the head and tail ends; when the number of pole pairs P is an odd number, the two symmetrical branch windings are connected in parallel at the head and tail ends; one end of the parallel branch winding serves as the midpoint of the phase winding, and the other end of the parallel branch winding serves as the phase port; thereby generating three-phase ports of the three-phase winding and a midpoint of a three-phase winding.

[0010] Preferably, the number of rotor pole pairs P=10 or P=14, the number of tooth slots Z=12, and the number of phases m=3.

[0011] Preferably, each phase winding forms one or more pairs of 180° symmetrical parallel branches.

[0012] Preferably, the motor stator core is divided into multiple sections, the stator core section gap λd = δK1, where δ is the electromagnetic air gap of the motor, the rotor core section gap λr = λd, K1 is the first coefficient, and the value range of K1 is 1 to 2.

[0013] Preferably, the rotor core segment gap at both ends of the rotor axial direction is: λrd=K2λr1=K2λd, wherein λr1 is the remaining rotor core segment gap except the rotor core segment gap at both ends of the rotor axial direction; λd is the stator core segment gap, K2 is the second coefficient, and the value range of K2 is 1.5 to 2.

[0014] Preferably, when λd or λr is less than 4 to 5 times the axial length of each segment, the axial magnetic levitation stiffness is approximately proportional to the number of segments n, the maximum stiffness of the axial passive magnetic levitation after segmentation is close to 0.95nK, and the axial effective working range of the magnetic levitation is close to 0.95λd or 0.95λr, where K is the stiffness of the single-segment axial passive magnetic levitation.

[0015] Preferably, the rotor permanent magnet is realized by samarium cobalt magnet.

[0016] Preferably, the number of segments of the stator core and the number of segments of the rotor core are both 5.

[0017] The beneficial effects brought by the present invention are:

[0018] This invention requires no additional sensors or controllers, replacing traditional mechanical bearings with protective bearings with a clearance of 0.1-0.5mm, enabling it to withstand heavy loads and extreme all-weather environments. It incorporates both radial active natural magnetic levitation technology and axial passive magnetic levitation technology, while also offering excellent motor drive capabilities.

[0019] The advancement, simplicity and reliability of the present invention are all principle-based, that is, the advancement, simplicity and reliability are naturally possessed.

[0020] This invention overcomes the challenges of application in extreme temperature environments, eliminating the problem of bearing clearance damage, seizure, or wear caused by thermal expansion and contraction in mechanical bearings in these extreme environments. The motor can be used in large-scale mechanical equipment in extreme space environments, including satellite manipulators (robots) and power generation and energy storage systems used in extreme space environments. It can also be used in Earth's extreme environments, such as nuclear radiation environments, environments with extreme temperature differences, and environments with sudden dangers. This paves the way for the future development of my country's spacecraft.

[0021] The advancement, simplicity and reliability of the present invention are all principle-based, that is, the advancement, simplicity and reliability are naturally possessed. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 1 is an axial cross-sectional view of the natural electromagnetic levitation three-phase permanent magnet synchronous motor in an extreme environment according to the present invention; wherein reference numeral 6 represents the stator core segment gap, and reference numeral 7 represents the rotor core segment gap;

[0023] Figure 2 A schematic diagram of the winding of the three-phase winding of a motor with 10 poles and 12 slots according to the present invention; wherein each phase has a pair of parallel branches;

[0024] Figure 3 A schematic diagram of the winding of the three-phase winding of a motor with 14 poles and 12 slots according to the present invention; wherein each phase has a pair of parallel branches;

[0025] Figure 4 A schematic diagram of the winding of the three-phase winding of a motor with 10 poles and 12 slots according to the present invention; wherein each phase has a pair of parallel branches;

[0026] Figure 5 The present invention is a schematic diagram of the winding of the three-phase winding of a motor with 10 poles and 12 slots, wherein each phase has two pairs of parallel branches.

[0027] Figure 6 The present invention is a schematic diagram of the winding of the three-phase winding of a motor with 10 poles and 12 slots; wherein each phase has a pair of parallel branches and a pair of short-circuit windings.

[0028] Figures 2 to 6In the figure, the reference sign O is the midpoint of each phase winding, that is, the midpoint of the three-phase winding. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0031] Specific implementation method 1. Figure 1 This embodiment describes an extreme environment natural electromagnetic magnetic levitation three-phase permanent magnet synchronous motor described in this embodiment. The motor is a fractional slot concentrated winding motor. The ratio of the number of slots to the number of phases of the motor is Z / m, and Z / m is an even number. Each phase winding of the motor forms a winding symmetrically distributed along the circumference of 180° and generates a 180° symmetrical couple torque. The motor includes a rotor and a stator sleeved outside the rotor, and the stator is fixed to the stator housing 5.

[0032] The rotor includes a rotor core 3 and a rotor permanent magnet 4; the rotor permanent magnet 4 is arranged on the rotor core 3, and the start-up protection mechanical bearing clearance at the end of the rotor core 3 is set to 0.1mm to 0.5mm;

[0033] The stator includes a stator core 1 and a stator winding 2. The stator winding 2 is wound on the stator core 1. The stator core 1 is axially divided into three or more sections, and there is a gap between two adjacent sections. The stator winding 2 is a three-phase winding.

[0034] The stator winding 2 is divided into multiple pairs of windings symmetrically distributed along a circumference of 180°. The maximum number of winding pairs per phase is Kpm = Z / (2m). The tail ends of adjacent windings of each phase are connected in series to form a branch. The tail ends of adjacent windings symmetrically distributed 180° are then connected in series to form another branch. The two symmetrical branches are then connected to form a 180° symmetrical parallel branch. The principle of parallel connection is: when the number of pole pairs P is even, the two symmetrical branch windings are connected in parallel end to end; when the number of pole pairs P is odd, the two symmetrical branch windings are connected in parallel end to end. One end of the parallel branch winding serves as the midpoint of the phase winding, and the other end of the parallel branch winding serves as the phase port. The three-phase windings of the motor are each formed into 180° symmetrical parallel branches, thus generating the three-phase ports of the three-phase winding and the midpoint of the three-phase winding. Ultimately, a special 180° symmetrical parallel three-phase winding is formed. Each phase winding of the present invention has one or more pairs of 180° symmetrical parallel branches. The currents in these 180° symmetrical parallel branches are the same in principle when there is no deviation in the stator and rotor air gaps.

[0035] Furthermore, each phase winding forms one or more pairs of 180° symmetrical parallel branches. In order to obtain axial passive magnetic levitation capability, the stator winding 2 does not need to be segmented along with the stator core 1.

[0036] During operation, there is an attractive force between the stator core 1 and the rotor permanent magnet 4. Due to the action of the bearing, the air gap between the stator and the rotor is kept equal, and the attractive force is equal everywhere along the circumference. The bearing makes the radial attractive force within the motor air gap equal everywhere and cancels each other out. However, if the motor rotates and the bearing fails, and there is a deviation in the air gap on both sides of 180°, the permanent magnet rotor body will be attracted to the side with the smaller air gap. The back electromotive force of the parallel branch on the side with the smaller air gap increases, and the current decreases. Conversely, the back electromotive force of the parallel branch on the side with the larger air gap decreases, and the current increases. Therefore, the radial tension on the side with the larger air gap increases, and the radial tension on the side with the smaller air gap decreases, which inevitably causes the air gap to change in the direction of smaller deviation and stabilizes the air gap deviation. Therefore, after the motor rotates, the present invention has the ability to restore the centering of the radial natural magnetic suspension. Because when the motor is not started, in the initial state, the permanent magnet rotor body will be randomly attracted to the side with the smaller air gap, the permanent magnet rotor body is radially unstable when the motor is not started. Therefore, the present invention uses a start-up protection mechanical bearing. The present invention has perfect dynamic radial natural electromagnetic levitation and passive axial magnetic levitation functions by adopting a traditional motor driving method without any additional sensors and controllers.

[0037] Furthermore, the number of rotor pole pairs P = 10 or P = 14, the number of tooth slots Z = 12, and the number of phases m = 3. Z / m = 12 / 3 = 4 is an even number, so each phase winding of this type of motor can form a winding that is symmetrically distributed along the circumference 180° and can generate a 180° symmetrical couple torque. In addition, the winding connections of the motors with P = 10 or P = 14, the number of stator poles (number of tooth slots) Z = 12, and the number of phases m = 3 are the same.

[0038] For further details, see Figure 2 and Figure 3 To illustrate this embodiment, when the number of rotor pole pairs P=10 or P=14, Z / m=12 / 3=4, each phase winding of the stator winding 2 has 4 groups of winding elements, wherein the 4 groups of windings are divided into Kpm=Z / (2m)=2 pairs of windings symmetrically distributed along the circumference at 180°, each group has 2 adjacent windings, which are connected in series tail to tail, and the 2 adjacent windings are connected in series to form a branch, and the 2 windings in the group symmetrically distributed 180° with the group constitute another branch; similarly, the other three groups of windings in this phase are all connected in the same way: the 2 adjacent windings in each group are connected in series tail to tail, and the 2 adjacent windings are connected in series to form a branch; the three groups symmetrically distributed 180° with the other three groups of windings in this phase respectively constitute another branch. Then, the two symmetrical branches formed by the two groups of windings with 180° symmetrical distribution are connected to form a parallel branch. The principle of parallel connection is: when the pole pair number P is an even number, the two parallel branch windings are connected in parallel from head to tail; when P is an odd number, the two parallel branch windings are connected in parallel from head to head and from tail to tail, with one end of the two parallel branch windings serving as the midpoint of the phase winding. In the present invention, when P is an even number, the two parallel branch windings are connected in parallel from head to tail. The U-phase winding of the present invention has a pair of 180° symmetrical parallel branches, a midpoint, and a U-phase winding port. Similarly, the three-phase windings of the motor are formed into 180° symmetrical parallel branches according to this method. In addition, the U, V, and W three-phase ports of the three-phase winding and the midpoint of the three-phase winding are formed. In other words, a special 180° symmetrical parallel three-phase winding is finally formed.

[0039] Each phase winding of the present invention has one or more pairs of 180° symmetrical parallel branches. The currents in these 180° symmetrical parallel branches are, in principle, identical when the stator and rotor air gaps are uniform. As is well known, there is an attractive force between the stator core 1 and the rotor permanent magnets 4. The bearings maintain the air gap between the stator and rotor equal, and the attractive force is constant along the circumference. The bearings ensure that the radial attractive forces within the motor air gap are uniform and cancel each other out. However, if the motor rotates and the bearings fail, the air gaps on either side of the 180° axis will inevitably deviate. In this case, the permanent magnet rotor will be attracted toward the side with the smaller air gap, and the back EMF of the parallel branch on the side with the smaller air gap will inevitably increase, reducing the current. Conversely, the back EMF of the parallel branch on the side with the larger air gap will decrease, increasing the current. Consequently, the radial tension on the side with the larger air gap increases, while the radial tension on the side with the smaller air gap decreases, inevitably causing the air gap to shift in the direction of decreasing deviation and stabilizing the air gap deviation. Therefore, after the motor rotates, the present invention possesses the ability to restore alignment through radial natural magnetic levitation.

[0040] In this embodiment, when Z / m=12 / 3=4, the number of rotor pole pairs P=10, each phase winding of the stator winding 2 has 4 groups of winding elements, and each group has 2 adjacent windings, the winding of the three-phase winding of the motor is specifically referred to Figure 2 When Z / m=12 / 3=4, rotor pole pair number P=14, each phase winding of stator winding 2 has 4 groups of winding elements, and each group has 2 adjacent windings, the winding of the motor three-phase winding is specifically referred to Figure 2 .

[0041] For further details, see Figure 4To illustrate this preferred embodiment, when the number of rotor pole pairs P=10, Z / m=12 / 3=4, each phase winding of the stator winding 2 has 4 groups of winding elements, which are divided into Kpm=Z / (2m)=2 pairs of windings symmetrically distributed along the circumference at 180°. Each group has only one winding and one branch, and the group symmetrically distributed 180° with the group constitutes another branch. Similarly, the other three groups of windings in this phase also have only one winding and one branch adjacent to each other. The three groups symmetrically distributed 180° with the other three groups of windings in this phase respectively constitute another branch. Then, the two symmetrical branches formed by the two groups of windings symmetrically distributed 180° are connected. The principle of parallel connection is: when the number of pole pairs P is even, the two parallel branch windings are connected in parallel from head to tail; when P is odd, the two parallel branch windings are connected in parallel from head to head and from tail to tail, with one end of the two parallel branch windings serving as the midpoint of the phase winding. In the present invention, when P is even, the two parallel branch windings are connected in parallel from head to tail. The U-phase winding of the present invention has a pair of 180° symmetrical parallel branches, a midpoint, and a U-phase winding port. Similarly, the three-phase windings of the motor are formed into 180° symmetrical parallel branches according to this method. Furthermore, the U, V, and W three-phase ports of the three-phase winding and the midpoint of the three-phase winding are formed. This ultimately forms a special 180° symmetrical parallel three-phase winding.

[0042] Each phase winding of the present invention has one or more pairs of 180° symmetrical parallel branches. The currents in these 180° symmetrical parallel branches are the same in principle when there is no deviation in the stator and rotor air gaps.

[0043] During application, there is an attractive force between the stator core 1 and the rotor permanent magnet 4. Due to the action of the bearing, the air gap between the stator and the rotor is kept equal, and the attractive force is equal everywhere along the circumference. The bearing makes the radial attractive force in the motor air gap equal everywhere and cancels each other out. However, if the motor rotates and the bearing fails, there will inevitably be a deviation in the air gap on both sides of 180°. At this time, the permanent magnet rotor body will be attracted to the side with a smaller air gap, and the back electromotive force of the parallel branch on the side with a smaller air gap will inevitably increase, and the current will decrease; on the contrary, the back electromotive force of the parallel branch on the side with a larger air gap will decrease, and the current will increase, so the radial tension on the side with a larger air gap will increase, and the radial tension on the side with a smaller air gap will decrease, which will inevitably cause the air gap to change in the direction of smaller deviation and stabilize the air gap deviation. Therefore, after the motor rotates, the present invention has the ability to restore the centering of the radial natural magnetic suspension.

[0044] For further details, see Figure 5In this preferred embodiment, when the number of rotor pole pairs P=10 and Z / m=12 / 3=4, each phase of the stator winding 2 has four groups of winding elements, which are divided into two pairs of windings symmetrically distributed along the circumference at Kpm=Z / (2m). Each group has two windings and two branches, and the two windings in the group symmetrically distributed 180° with the group constitute the other two branches. Similarly, the other three groups of windings in this phase also have two windings and two branches, which are symmetrically distributed 180° with the other three groups of windings in this phase. The three groups symmetrically distributed at 180° constitute the other two branches respectively; then each two symmetrical branches formed by the two groups of windings symmetrically distributed at 180° are connected to form a parallel branch winding; the principle of parallel connection is: when the pole pair number P is an even number, the two parallel branch windings are connected in parallel from head to tail; when P is an odd number, the two parallel branch windings are connected in parallel from head to head and from tail to tail, and one end of the two parallel branch windings serves as the midpoint of the phase winding; in the present invention, when P is an even number, the two parallel branch windings are connected in parallel from head to tail.

[0045] The U-phase winding of the present invention has two pairs of 180° symmetrical parallel branches, a midpoint, and a U-phase winding port. Similarly, the three-phase windings of the motor are each formed into 180° symmetrical parallel branches according to this method. Furthermore, the U, V, and W phase ports of the three-phase winding and the midpoint of the three-phase winding are formed. This ultimately forms a special 180° symmetrical parallel three-phase winding.

[0046] In the preferred embodiment of the present invention, there is an attractive force between the stator core 1 and the rotor permanent magnet 4. Due to the action of the bearing, the air gap between the stator and the rotor is kept equal, and the attractive force is equal everywhere along the circumference. The bearing makes the radial attractive force in the motor air gap equal everywhere and cancels each other out. However, if the motor rotates and the bearing fails, there will inevitably be a deviation in the air gap on both sides of 180°. At this time, the permanent magnet rotor body will be attracted to the side with a smaller air gap, and the back electromotive force of the parallel branch on the side with a smaller air gap will inevitably increase, and the current will decrease. Conversely, the back electromotive force of the parallel branch on the side with a larger air gap will decrease, and the current will increase. Therefore, the radial tension on the side with a larger air gap will increase, and the radial tension on the side with a smaller air gap will decrease, which will inevitably cause the air gap to change in the direction of smaller deviation and stabilize the air gap deviation. Therefore, after the motor rotates, the present invention has the ability to restore the centering of the radial natural magnetic suspension.

[0047] For further details, see Figure 6To illustrate this preferred embodiment, when the number of rotor pole pairs P = 10, Z / m = 12 / 3 = 4, each phase of the stator winding 2 has 4 groups of winding elements, which are divided into Kpm = Z / (2m) = 2 pairs of windings symmetrically distributed along the circumference at 180°. Each group has only one winding and one branch. Similarly, each of the other three groups of windings in this phase has only one winding and one branch. Then, the two symmetrical branches formed by the two groups of windings symmetrically distributed at 180° are connected to form a parallel branch winding. The principle of parallel connection is: when the number of pole pairs P is an even number, the two parallel windings are connected. The branch windings are connected in parallel from head to tail. When P is an odd number, the two parallel branch windings are connected in parallel from head to head and from tail to tail, with one end of the two parallel branch windings serving as the midpoint of the phase winding. In the present invention, when P is an even number, the two parallel branch windings are connected in parallel from head to tail. The U-phase winding of the present invention has a pair of 180° symmetrical parallel branches, a midpoint, and a U-phase winding port. Similarly, the three-phase windings of the motor are formed into 180° symmetrical parallel branches according to this method. Furthermore, the U, V, and W phase ports of the three-phase winding and the midpoint of the three-phase winding are formed. This ultimately forms a special 180° symmetrical parallel three-phase winding.

[0048] There is an attractive force between the stator core 1 and the rotor permanent magnet 4. Due to the action of the bearing, the air gap between the stator and the rotor is kept equal, and the attractive force is equal everywhere along the circumference. The bearing makes the radial attractive force in the motor air gap equal everywhere and cancels each other out. However, if the motor rotates and the bearing fails, there must be a deviation in the air gap on both sides of 180°. At this time, the permanent magnet rotor body will be attracted to the side with a smaller air gap, and the back electromotive force of the parallel branch on the side with a smaller air gap will inevitably increase, and the current will decrease; on the contrary, the back electromotive force of the parallel branch on the side with a larger air gap will decrease, and the current will increase, so the radial tension on the side with a larger air gap will increase, and the radial tension on the side with a smaller air gap will decrease, which will inevitably cause the air gap to change in the direction of smaller deviation and stabilize the air gap deviation. Therefore, after the motor rotates, the present invention has the ability to restore the centering of radial natural magnetic suspension. In order to increase the natural magnetic suspension restoring force, Figure 6The present invention adds a short-circuit winding specifically designed to enhance the natural magnetic levitation restoring force to adjacent slots in each phase. Based on the same principle, an attractive force exists between the stator core 1 and the rotor permanent magnets 4. The bearings maintain the air gap between the stator and rotor equal, and the attractive force is equal everywhere along the circumference. The bearings ensure that the radial attractive forces within the motor air gap are equal and cancel each other out. However, if the motor rotates and the bearings fail, there will inevitably be a deviation in the air gaps on either side of the 180° axis. In this case, the permanent magnet rotor will be attracted toward the side with the smaller air gap, and the back EMF deviation of the parallel short-circuit winding branch on the side with the smaller air gap will inevitably increase, reducing the current. Conversely, the back EMF deviation of the parallel short-circuit winding branch on the side with the larger air gap will decrease, increasing the current. Consequently, the radial tension on the side with the larger air gap increases, while the radial tension on the side with the smaller air gap decreases, inevitably causing the air gap to shift in the direction of decreasing deviation and stabilizing the air gap deviation. Since the magnitude of the radial natural magnetic levitation restoring force is proportional to the square of the back EMF deviation, the method of adding a dedicated radial natural magnetic levitation winding according to the present invention can be used when necessary.

[0049] Furthermore, the motor stator core 1 is divided into multiple segments, with a stator core segment gap λd = (1-2)δ, where δ is the electromagnetic air gap of the motor, and a rotor core segment gap λr = λd. Since the rotor is axially segmented, segment gaps exist in the rotor.

[0050] Furthermore, the rotor core segment gap at both ends of the rotor axial direction is: λrd=(1.5~2)λr1=(1.5~2)λd, where λr1 is the remaining rotor core segment gap except the rotor core segment gap at both ends of the rotor axial direction; λd is the stator core segment gap.

[0051] Furthermore, when λd or λr is less than 4 to 5 times the axial length of each segment, the axial magnetic levitation stiffness is approximately proportional to the number of segments n. The maximum stiffness of the segmented axial passive magnetic levitation approaches 0.95nK, and the axial effective working range of the magnetic levitation approaches 0.95λd or 0.95λr, where K is the stiffness of the single-segment axial passive magnetic levitation.

[0052] Furthermore, the rotor permanent magnet 4 is realized by using samarium cobalt magnet.

[0053] Furthermore, the number of segments of the stator core 1 and the number of segments of the rotor core 3 are both five.

[0054] By adopting the radial natural electromagnetic magnetic suspension technology, axial passive magnetic suspension and auxiliary mechanical bearings of the present invention, the above-mentioned volume, loss and cost are completely eliminated.

[0055] In order to further improve reliability, the present invention adds special mechanical auxiliary bearings to adapt to large loads and all-weather extreme environments.

[0056] This invention eliminates the need for additional sensors or controllers, replacing traditional mechanical bearings with protective bearings with a clearance of 0.1mm to 0.5mm, enabling it to withstand heavy loads and operate in extreme all-weather environments. It incorporates both radial active natural magnetic levitation and axial passive magnetic levitation technologies, offering superior motor drive capabilities. The heat source for this inner rotor motor is located on the stator side, preventing the rotor from generating heat. This makes it insensitive to extreme vacuum environments and allows for all-weather operation.

[0057] The advancement, simplicity and reliability of the present invention are all principle-based, that is, the advancement, simplicity and reliability are naturally possessed.

[0058] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the invention. It should be understood that many modifications may be made to the illustrative embodiments, and that other arrangements may be devised, without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in ways other than those described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be employed in conjunction with other described embodiments.

Claims

1. A three-phase permanent magnet synchronous motor with natural electromagnetic levitation in an extreme environment, wherein the motor is a fractional slot concentrated winding motor, the ratio of the number of slots to the number of phases of the motor is Z / m, and Z / m is an even number, characterized in that: Each phase winding of the motor forms a winding that is symmetrically distributed along the circumference at 180°, and generates a 180° symmetrical couple torque; the motor includes a rotor and a stator sleeved outside the rotor, and the stator is fixed on a stator housing (5); The rotor comprises a rotor core (3) and a rotor permanent magnet (4); the rotor permanent magnet (4) is arranged on the rotor core (3), and the start-up protection mechanical bearing clearance at the end of the rotor core (3) is set to 0.1 mm to 0.5 mm; The stator comprises a stator core (1) and a stator winding (2); the stator winding (2) is wound on the stator core (1); the stator core (1) is axially divided into three or more sections, and a gap exists between two adjacent sections; the stator winding (2) is a three-phase winding; The stator winding (2) is divided into multiple pairs of windings symmetrically distributed along a circumference of 180°; the maximum number of winding pairs per phase is Kpm=Z / (2m), the tail ends of adjacent windings of each phase are connected in series to form a branch, and the tail ends of adjacent windings symmetrically distributed at 180° are connected in series to form another branch, and the two symmetrical branches are then connected to form a 180° symmetrical parallel branch. The principle of parallel connection is: when the number of pole pairs P is an even number, the two symmetrical branch windings are connected in parallel at the head and tail ends; when the number of pole pairs P is an odd number, the two symmetrical branch windings are connected in parallel at the head and tail ends; one end of the parallel branch winding serves as the midpoint of the phase winding, and the other end of the parallel branch winding serves as the phase port; thereby generating three-phase ports of the three-phase winding and a midpoint of a three-phase winding.

2. The extreme environment natural electromagnetic magnetic levitation three-phase permanent magnet synchronous motor according to claim 1, characterized in that: The number of rotor pole pairs P=10 or P=14, the number of tooth slots Z=12, and the number of phases m=3.

3. The extreme environment natural electromagnetic magnetic levitation three-phase permanent magnet synchronous motor according to claim 1, characterized in that: Each phase winding forms one or more pairs of 180° symmetrical parallel branches.

4. The extreme environment natural electromagnetic magnetic levitation three-phase permanent magnet synchronous motor according to claim 1, characterized in that: The stator core segment gap λd=δK1, where δ is the electromagnetic air gap of the motor, the rotor core segment gap λr=λd, and K1 is the first coefficient, and the value range of K1 is 1 to 2.

5. The extreme environment natural electromagnetic magnetic levitation three-phase permanent magnet synchronous motor according to claim 1, characterized in that: The rotor core segment gap at both ends of the rotor axial direction is: λrd=K2λr1=K2λd, where λr1 is the remaining rotor segment gap except the rotor segment gap at both ends of the rotor axial direction; λd is the stator core segment gap, K2 is the second coefficient, and the value range of K2 is 1.5 to 2.

6. The extreme environment natural electromagnetic magnetic levitation three-phase permanent magnet synchronous motor according to claim 4, characterized in that: When λd or λr is less than 4 to 5 times the axial length of each segment, the axial magnetic levitation stiffness is approximately proportional to the number of segments n. The maximum stiffness of the segmented axial passive magnetic levitation approaches 0.95nK, and the axial effective working range of the magnetic levitation approaches 0.95λd or 0.95λr, where K is the stiffness of the single-segment axial passive magnetic levitation.

7. The extreme environment natural electromagnetic magnetic levitation three-phase permanent magnet synchronous motor according to claim 1, characterized in that: The rotor permanent magnet (4) is realized by using samarium cobalt magnetic steel.

8. The extreme environment natural electromagnetic magnetic levitation three-phase permanent magnet synchronous motor according to claim 4, characterized in that: The number of segments of the stator core (1) and the number of segments of the rotor core (3) are both 5.

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