Natural magnetic levitation stepper motor for extreme environments

Abstract

The invention relates to a natural magnetic levitation stepper motor for use in extreme environments. The invention addresses the problem of existing magnetic levitation motors being expensive and unsuitable for use as motion control components in extreme environments. The invention comprises an outer stator and an inner rotor. The inner rotor comprises two rotor cores of identical structure arranged axially in parallel, with an axial permanent magnet disposed between the two rotor cores. The geometric axes of the two rotor units are offset by 1 / 2τ. The outer stator comprises a stator core and stator windings. The inner surface of the stator core is uniformly distributed with Z-shaped magnets. d stator slots; m-phase stator windings are wound in the stator slots, and each phase winding is Z-shaped and symmetrically distributed along the circumference at 180°. d The m-phase windings are connected end to end, and the m contacts formed by adjacent phase windings are connected to the driver. The driver controls the m-phase windings to be energized simultaneously according to the following rules: when any phase winding is energized, the other m-1 phase windings are connected in series and then energized in parallel with it; the energization order is switched sequentially.

Description

Technical Field

[0001] The invention relates to a stepping motor structure under extreme environments, and belongs to the field of motors under extreme environments. Background Art

[0002] Extreme environments also require motion control components. For example, spacecraft must operate at high speeds in low temperatures, which shortens the life of mechanical bearings. Therefore, motors with levitation capabilities are required. The temperature difference between day and night on the lunar surface is extremely large, reaching -180°C to +150°C. Probes and rover probes operating on the lunar surface are exposed to this extreme environment. Therefore, servo drive components that can operate directly in this extreme environment are needed. Another example is large mechanical equipment used in the extreme environment of space, manipulators (robots) outside satellite cabins, and power generation and energy storage systems used in the extreme environment of space. Similarly, Earth also has extreme environments, such as nuclear radiation environments, extreme temperature differences, and sudden hazardous environments. Currently, most space motion components use stepper motors, and their performance is unsatisfactory.

[0003] At present, there are no ideal motion control components for use in extreme environments at home and abroad.

[0004] 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.

[0005] However, the cost of levitating the motor rotor is prohibitive. Typically, the magnetic bearing accounts for 60% of the volume of a magnetic levitation motor, and the controller for the magnetic bearing is expensive and complex. This makes magnetic levitation motors a costly luxury and out of reach. Summary of the Invention

[0006] In view of the problem that existing magnetic levitation motors are high in cost and cannot be used as motion control components in extreme environments, the present invention provides a natural magnetic levitation stepping motor for use in extreme environments.

[0007] The natural magnetic levitation stepper motor for use in extreme environments of the present invention comprises an outer stator and an inner rotor. The inner rotor comprises two rotor cores of identical structure arranged axially in parallel, with an axial permanent magnet disposed between the two rotor cores. The geometric axes of the two rotor units are staggered by 1 / 2τ, where τ is the rotor tooth pitch.

[0008] The outer stator includes a stator core and a stator winding. The inner surface of the stator core is uniformly distributed with Z d stator slots, each stator tooth is evenly distributed with stator teeth;

[0009] The stator slots are wound with m-phase stator windings, and each phase winding is Z-shaped and symmetrically distributed along the circumference at 180°.d / m elements are connected in parallel to generate a 180° symmetrical couple torque; the conditions are met: Z d / m is an even number;

[0010] The m phase windings are connected end to end, and the m contacts formed by the adjacent phase windings are connected to the driver. The driver controls the m phase windings to be energized simultaneously according to the following rules:

[0011] When any phase winding is energized, the other m-1 phase windings are connected in series and then energized in parallel with it;

[0012] The power-on sequence is A→B→…→m→A→B.

[0013] Preferably, when m=5, the five-phase ten-wire stepper motor is constructed as follows:

[0014] Each phase winding is set to Z d / m=10 / 5=2 elements. Connect the two elements of each phase in parallel head-to-head and tail-to-tail to form two branches. The head ends of the five phases form the positive input ports of A, B, C, D, and E, and the tail ends of the five phases form the negative input ports of A, B, C, D, and E. The five-phase winding generates a restoring force against the radial deviation of the motor in 10 directions.

[0015] Each phase winding is connected end to end, with the drive end led out from five contacts. When the A phase winding is energized, the other four windings BCDE are connected in series and then energized in parallel with the A phase winding. The windings A-B-C-D-E-A-B are switched in sequence to make the rotor rotate step by step. The resulting step angle θ s =180° / PN r =180° / 5N r Where N r is the number of rotor teeth, and P is the number of pole pairs.

[0016] Preferably, when m=5, the five-phase six-wire stepper motor is constructed as follows:

[0017] Each phase winding is set to Z d / m=10 / 5=2 elements. Connect the two elements of each phase head-to-head and tail-to-tail in parallel to form two branches. The head ends of the five phases form the positive input ports of A, B, C, D, and E. The tail ends of the five phases are connected in parallel to form the midpoint port of the motor. The five-phase winding generates a restoring force against the radial deviation of the motor from 10 directions.

[0018] Each phase winding is connected end to end, with the drive end led out from five contacts. When the A phase winding is energized, the other four windings BCDE are connected in series and then energized in parallel with the A phase winding. The windings A-B-C-D-E-A-B are switched in sequence to make the rotor rotate step by step. The resulting step angle θ s =180° / PN r =180° / 5Nr Where N r is the number of rotor teeth, and P is the number of pole pairs.

[0019] Preferably, when m=4, the four-phase eight-wire stepper motor is constructed as follows:

[0020] Each phase winding is set to Z d / m=8 / 4=2 elements. Connect the two elements of each phase in parallel head-to-head and tail-to-tail to form two branches. The head ends of the four phases form the positive input ports of A, B, C, and D, and the tail ends of the four phases form the negative input ports of A, B, C, and D. The four-phase winding generates restoring forces against the radial deviation of the motor from eight directions.

[0021] Each phase winding is connected end to end, with the drive end led out from four contacts. When the A phase winding is energized, the other three windings BCD are connected in series and then energized in parallel with the A phase winding. The windings A-B-C-D-A-B are switched in sequence to make the rotor rotate step by step. The resulting step angle θ s =180° / PN r =180° / 5N r Where N r is the number of rotor teeth, and P is the number of pole pairs.

[0022] Preferably, when m=4, the four-phase five-wire stepper motor is constructed as follows:

[0023] Each phase winding is set to Z d / m=8 / 4=2 elements. The two elements of each phase are connected in parallel head-to-head and tail-to-tail to form two branches. The head ends of the four phases form the positive input ports of A, B, C, and D. The tail ends of the four phases are connected in parallel to form the midpoint port of the motor. The four-phase winding generates restoring force against the radial deviation of the motor from eight directions.

[0024] Each phase winding is connected end to end, with the drive end led out from four contacts. When the A phase winding is energized, the other three windings BCD are connected in series and then energized in parallel with the A phase winding. The windings A-B-C-D-A-B are switched in sequence to make the rotor rotate step by step. The resulting step angle θ s =180° / PN r =180° / 5N r Where N r is the number of rotor teeth, and P is the number of pole pairs.

[0025] Preferably, when m=3, the three-phase six-wire stepper motor is constructed as follows:

[0026] Each phase winding is set to Z d / m=8 / 4=2 elements. The two elements of each phase are connected in parallel head-to-head and tail-to-tail to form two branches. The head ends of the four phases form the positive input ports of the three phases A, B, and C, and the tail ends of the four phases form the negative input ports of the three phases A, B, and C. The three-phase winding generates a restoring force against the radial deviation of the motor from six directions.

[0027] The phase windings are connected end to end, with the drive end led out from three contacts. When the phase A winding is energized, the other two windings BC are connected in series and then energized in parallel with the phase A winding. The windings A-B-C-A-B are switched in sequence to make the rotor rotate step by step. The resulting step angle θ s =180° / PN r =180° / 5N r Where N r is the number of rotor teeth, and P is the number of pole pairs.

[0028] Preferably, when m=3, the three-phase four-wire stepper motor is constructed as follows:

[0029] Each phase winding is set to Z d / m=8 / 4=2 elements. The two elements of each phase are connected in parallel head-to-head and tail-to-tail to form two branches. The head ends of the three phases form the positive input ports of A, B, and C. The tail ends of the three phases are connected in parallel to form the midpoint port of the motor. The three-phase winding generates a restoring force against the radial deviation of the motor from six directions.

[0030] The phase windings are connected end to end, with the drive end led out from three contacts. When the phase A winding is energized, the other two windings BC are connected in series and then energized in parallel with the phase A winding. The windings A-B-C-A-B are switched in sequence to make the rotor rotate step by step. The resulting step angle θ s =180° / PN r =180° / 5N r Where N r is the number of rotor teeth, and P is the number of pole pairs.

[0031] Preferably, an auxiliary bearing is provided, and the bearing clearance of the auxiliary bearing is 0.1 to 1 mm.

[0032] Beneficial effects of the present invention: The present invention does not require any additional sensors and controllers, and changes the traditional mechanical bearings into additional protective bearings with a gap of 0.1 to 0.5 mm, which can adapt to large loads and all-weather extreme environments. The present invention naturally contains: radial active natural magnetic levitation technology, axial passive magnetic levitation technology, and has excellent motor drive functions. The heat source of the motor in the present invention is on the stator side, and the rotor does not generate heat, so it is not sensitive to the vacuum extreme environment and can work all day long. The natural electromagnetic magnetic levitation of the present invention can make the motor rotor rotate in a state with minimal energy loss, and at this time, the vibration and noise are minimal, just like the natural rotation of the earth and the sun in space.

[0033] This invention utilizes radial natural electromagnetic levitation technology, axial passive magnetic levitation, and auxiliary mechanical bearings to overcome the size, losses, and costs associated with traditional magnetic levitation motors. All currents in the motor windings contribute to the natural levitation of the motor rotor, providing a significant force for natural electromagnetic levitation.

[0034] 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a comparison diagram of the winding methods of the five-phase stepper motor windings, where Figure 1 (a) is a schematic diagram of the winding of a traditional five-phase six-wire stepper motor. Figure 1 (b) is a schematic diagram of the winding of a traditional five-phase ten-wire stepper motor. Figure 1 (c) is a schematic diagram of the winding of the natural magnetic levitation five-phase six-wire stepping motor of the present invention, Figure 1 (d) is a schematic diagram of the windings of the natural magnetic levitation five-phase ten-wire stepping motor of the present invention;

[0036] Figure 2 This is a comparison diagram of the winding methods of four-phase stepper motor windings, where Figure 2 (a) is a schematic diagram of the winding of a traditional four-phase five-wire stepper motor. Figure 2 (b) is a schematic diagram of the winding of a traditional four-phase eight-wire stepper motor. Figure 2 (c) is a schematic diagram of the winding of the natural magnetic levitation four-phase five-wire stepping motor of the present invention, Figure 2 (d) is a schematic diagram of the winding of the natural magnetic levitation four-phase eight-wire stepping motor of the present invention;

[0037] Figure 3 This is a comparison diagram of the winding methods of three-phase stepper motor windings, where Figure 3 (a) is a schematic diagram of the winding of a traditional three-phase four-wire stepper motor. Figure 3 (b) is a schematic diagram of the winding of a traditional three-phase six-wire stepper motor. Figure 3 (c) is a schematic diagram of the winding of the natural magnetic levitation three-phase four-wire stepping motor of the present invention, Figure 3 (d) is a schematic diagram of the winding of the natural magnetic levitation three-phase six-wire stepping motor of the present invention;

[0038] Figure 4 This is the wiring diagram of the five-phase stepper motor winding, where Figure 4 (a) is the winding connection principle diagram of a traditional five-phase ten-wire stepper motor. Figure 4 (b) is a schematic diagram of the winding connection principle of the natural magnetic levitation five-phase ten-wire stepping motor of the present invention;

[0039] Figure 5 This is the winding power supply schematic of a traditional five-phase ten-wire stepper motor;

[0040] Figure 6 This is a schematic diagram of the winding power supply principle of the natural magnetic levitation five-phase ten-wire stepping motor of the present invention;

[0041] Figure 7 This is a circuit diagram of the natural magnetic levitation motor driver of the present invention, wherein Figure 7 (a) is the circuit diagram of the three-phase four-wire natural magnetic levitation motor driver. Figure 7 (b) is the circuit schematic diagram of the four-phase eight-wire natural magnetic levitation motor driver. Figure 7 (c) is the circuit schematic diagram of the five-phase ten-wire natural magnetic levitation motor driver. DETAILED DESCRIPTION

[0042] 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.

[0043] 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.

[0044] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0045] Specific implementation method 1: Figures 1 to 7 This embodiment describes a natural magnetic levitation stepper motor for use in extreme environments, comprising an outer stator and an inner rotor. The inner rotor comprises two rotor cores of identical structure arranged axially in parallel, with an axial permanent magnet disposed between the two rotor cores. The geometric axes of the two rotor units are offset by 1 / 2τ, where τ represents the rotor tooth pitch.

[0046] The outer stator includes a stator core and a stator winding. The inner surface of the stator core is uniformly distributed with Z d stator slots, each stator tooth is evenly distributed with stator teeth;

[0047] The stator slots are wound with m-phase stator windings, and each phase winding is Z-shaped and symmetrically distributed along the circumference at 180°. d / m elements are connected in parallel to generate a 180° symmetrical couple torque; the conditions are met: Z d / m is an even number;

[0048] The m phase windings are connected end to end, and the m contacts formed by the adjacent phase windings are connected to the driver. The driver controls the m phase windings to be energized simultaneously according to the following rules:

[0049] When any phase winding is energized, the other m-1 phase windings are connected in series and then energized in parallel with it;

[0050] The power-on sequence is A→B→…→m→A→B.

[0051] The stepper motor is the only motor that has positioning capability and is also one of the most robust motors. The number of stator phases of mainstream stepper motors is m = 2, 3, 4, or 5, and the number of stator poles is 2P, which is also the number of stator slots Z. d =2P=4, 6, 8, 10, Z d / m is an even number. Generally, there are multiple small teeth on the stator slot, and the number of small teeth on the rotor is N r =Z r Many multi-tooth cores are used to increase the torque of the stepper motor and reduce the step angle θ of the stepper motor. s , usually the rotor core is divided into two sections, and the geometric axes of the two sections are staggered by 1 / 2τ. τ is the rotor tooth pitch, and an axial permanent magnet is embedded between the two sections of the core. This stepper motor is called an induction stepper motor. Compared with the traditional reactive stepper motor, the induction stepper motor has a permanent magnet added to the rotor structure, which can provide a higher working magnetic flux density of the soft magnetic material, and the stator excitation only needs to provide a changing magnetic field without providing the energy required for the working magnetic flux density. Therefore, the induction stepper motor has high efficiency, low current and low heat generation. Due to the presence of permanent magnets, the motor winding has a strong back electromotive force and its own damping effect is relatively good, making it relatively stable, low noise and low low-frequency vibration during operation. At the same time, due to the presence of permanent magnets, it naturally has the ability of axial passive magnetic suspension. To some extent, the induction stepper motor can be regarded as a low-speed synchronous motor. Each phase of the induction stepper motor has at least one pair of windings wound on two poles with a difference of 180°, Z d Because m is an even number, the number of windings per phase must be even. Consequently, each phase of an induction stepper motor can be arranged 180° symmetrically around the circumference, generating a 180° symmetrical couple torque. By connecting these 180° symmetrical windings in parallel, a radial dynamic natural electromagnetic restoring force is generated, while also possessing an axial passive magnetic levitation restoring force, thus naturally achieving full magnetic levitation.

[0052] When a stepper motor passes an electric pulse, the angle through which the rotor rotates is called the step angle θ. s ,θ s =180° / PN r

[0053] The stepper motor of this invention can be used in fields such as industry, aerospace, robotics, and precision measurement, such as servo mechanisms in satellites, optoelectronic theodolites for satellite tracking, military instruments, communications, and radar equipment. Because the naturally electromagnetically levitated multi-phase inductor stepper motor of this invention is equivalent to a synchronous motor, it facilitates vector control and intelligent control of the motor, significantly improving its operating accuracy and dynamic response. This allows the stepper motor to be used in medium- and low-power industrial applications and in high-speed, high-precision, and extreme environments in the aerospace field. The motor of this invention can operate at temperatures up to ±180°C.

[0054] The motor of this embodiment is described below through six embodiments.

[0055] Example 1, see Figure 1 、 Figures 4 to 6 , when m=5, the five-phase ten-wire stepper motor is:

[0056] Each phase winding is set to Z d / m = 10 / 5 = 2 elements, where an element refers to a set of windings. Two elements per phase are connected head-to-head and tail-to-tail in parallel to form two branches. The five-phase heads form the positive input ports of A, B, C, D, and E, and the five-phase tails form the negative input ports of A, B, C, D, and E. The five-phase windings generate restoring forces against radial deviations of the motor in 10 directions.

[0057] Each phase winding is connected end to end, with the drive end led out from five contacts. When the A phase winding is energized, the other four windings BCDE are connected in series and then energized in parallel with the A phase winding. The windings A-B-C-D-E-A-B are switched in sequence to make the rotor rotate step by step. The resulting step angle θ s =180° / PN r =180° / 5N r Where N r is the number of rotor teeth, and P is the number of pole pairs.

[0058] in Figure 1 (a) is a schematic diagram of the winding of a traditional five-phase six-wire stepper motor. Figure 1 (b) is a schematic diagram of the winding of a traditional five-phase ten-wire stepper motor. The corresponding wiring schematic diagram can be found in Figure 4 (a) The two elements of each phase winding are connected in series, and the phase windings are connected end to end to form five contacts. The power control is shown in Figure 1. Figure 5 As shown in the figure, when phase A is energized, the other four phases are connected in series and then energized in parallel with phase A. Figure 1(c) is a schematic diagram of the winding of the natural magnetic levitation five-phase six-wire stepping motor of the present invention.

[0059] Figure 1 (d) is a schematic diagram of the windings of the natural magnetic levitation five-phase ten-wire stepper motor of the present invention. The corresponding wiring schematic diagram is shown in Figure 4 (b), for stator Z d =2P=10, the two elements of each phase winding are connected in parallel, and the windings of each phase are connected end to end, and the power lines are drawn from five contacts. Usually, the five windings are energized at the same time, forming a parallel power-on mode with one branch being one winding and the other branch being four windings connected in series. Figure 6 As shown in the figure, by switching one winding branch of a phase in sequence, the rotor can be rotated step by step. The step angle is obtained according to the formula θ s =180° / PN r =180° / 5N r =0.75°, N r =50, then for two-phase, three-phase, four-phase, and five-phase motors, P=2, P=3, P=4, and P=5 are substituted into the formula to obtain the step angle: The calculated step angle is 1.8° for two-phase, 1.2° for three-phase, 0.9° for four-phase, and 0.72° for five-phase. The five-phase stepper motor has the highest resolution and the smallest detent torque. The stator structure and drive circuit are simpler than those of the four-phase stepper motor.

[0060] like Figure 5, traditional stepper motors cannot generate magnetic levitation restoring force, and rotor eccentricity will cause vibration and noise. Each phase winding of the present invention has a pair of 180° symmetrical parallel branches. When the rotor is eccentric, the current in these 180° symmetrical parallel branches generates a deviation current to realize active natural electromagnetic magnetic levitation restoring force. The natural electromagnetic magnetic levitation restoring force depends on the size of the deviation current generated when the rotor is eccentric, and has nothing to do with the motor load current. The current in these 180° symmetrical parallel branches is the same in principle when there is no deviation in the stator and rotor air gaps. There is an attraction between the stator core and the rotor core. Due to the action of the bearings, the air gap between the stator and the rotor is kept equal, and the attraction is equal everywhere along the circumference. The bearings make the radial attraction in the motor air gap equal everywhere and cancel each other out. The bearing clearance of the present invention is 0.1 to 0.5 mm. At this time, if there is a deviation in the air gap on both sides of 180°, the rotor body will be attracted to the side with the smaller air gap, and the back electromotive force (or transformer potential) of the parallel branch on the side with the smaller air gap will inevitably increase, and the current will decrease. Conversely, the back electromotive force (or transformer potential) of the parallel branch on the side with the larger air gap will decrease, and the current will increase. As a result, the radial tension on the side with the larger air gap will increase, and the radial tension on the side with the 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. For stepper motors, even when the motor is in the startup state and has not yet rotated, the transformer potential, that is, the dΨ / dt induced potential, already exists. Therefore, the present invention does not require any additional sensors and controllers and has the complete radial natural magnetic suspension recovery and alignment capability.

[0061] The driving circuit of the five-phase ten-wire motor in this embodiment is shown in FIG. Figure 7 (c) shown.

[0062] Example 2: When m=5, the five-phase six-wire stepper motor is:

[0063] Each phase winding is set to Z d / m=10 / 5=2 elements. Connect the two elements of each phase head-to-head and tail-to-tail in parallel to form two branches. The head ends of the five phases form the positive input ports of A, B, C, D, and E. The tail ends of the five phases are connected in parallel to form the midpoint port of the motor. The five-phase winding generates a restoring force against the radial deviation of the motor from 10 directions.

[0064] Each phase winding is connected end to end, with the drive end led out from five contacts. When the A phase winding is energized, the other four windings BCDE are connected in series and then energized in parallel with the A phase winding. The windings A-B-C-D-E-A-B are switched in sequence to make the rotor rotate step by step. The resulting step angle θ s =180° / PN r =180° / 5N r Where N r is the number of rotor teeth, and P is the number of pole pairs.

[0065] Example 3: When m=4, the four-phase eight-wire stepping motor is:

[0066] Each phase winding is set to Z d / m=8 / 4=2 elements. Connect the two elements of each phase in parallel head-to-head and tail-to-tail to form two branches. The head ends of the four phases form the positive input ports of A, B, C, and D, and the tail ends of the four phases form the negative input ports of A, B, C, and D. The four-phase winding generates restoring forces against the radial deviation of the motor from eight directions.

[0067] Each phase winding is connected end to end, with the drive end led out from four contacts. When the A phase winding is energized, the other three windings BCD are connected in series and then energized in parallel with the A phase winding. The windings A-B-C-D-A-B are switched in sequence to make the rotor rotate step by step. The resulting step angle θ s =180° / PN r =180° / 5N r Where N r is the number of rotor teeth, and P is the number of pole pairs.

[0068] Its driving circuit is shown in Figure 7 (b) shown.

[0069] Example 4: When m=4, the four-phase five-wire stepping motor is:

[0070] Each phase winding is set to Z d / m=8 / 4=2 elements. The two elements of each phase are connected in parallel head-to-head and tail-to-tail to form two branches. The head ends of the four phases form the positive input ports of A, B, C, and D. The tail ends of the four phases are connected in parallel to form the midpoint port of the motor. The four-phase winding generates restoring force against the radial deviation of the motor from eight directions.

[0071] Each phase winding is connected end to end, with the drive end led out from four contacts. When the A phase winding is energized, the other three windings BCD are connected in series and then energized in parallel with the A phase winding. The windings A-B-C-D-A-B are switched in sequence to make the rotor rotate step by step. The resulting step angle θ s =180° / PN r =180° / 5N r Where N r is the number of rotor teeth, and P is the number of pole pairs.

[0072] Example 5: When m=3, the three-phase six-wire stepper motor is:

[0073] Each phase winding is set to Z d / m=8 / 4=2 elements. The two elements of each phase are connected in parallel head-to-head and tail-to-tail to form two branches. The head ends of the four phases form the positive input ports of the three phases A, B, and C, and the tail ends of the four phases form the negative input ports of the three phases A, B, and C. The three-phase winding generates a restoring force against the radial deviation of the motor from six directions.

[0074] The phase windings are connected end to end, with the drive end led out from three contacts. When the phase A winding is energized, the other two windings BC are connected in series and then energized in parallel with the phase A winding. The windings A-B-C-A-B are switched in sequence to make the rotor rotate step by step. The resulting step angle θ s =180° / PN r =180° / 5N r Where N r is the number of rotor teeth, and P is the number of pole pairs.

[0075] Example 6: When m=3, the three-phase four-wire stepping motor is:

[0076] Each phase winding is set to Z d / m=8 / 4=2 elements. The two elements of each phase are connected in parallel head-to-head and tail-to-tail to form two branches. The head ends of the three phases form the positive input ports of A, B, and C. The tail ends of the three phases are connected in parallel to form the midpoint port of the motor. The three-phase winding generates a restoring force against the radial deviation of the motor from six directions.

[0077] The phase windings are connected end to end, with the drive end led out from three contacts. When the phase A winding is energized, the other two windings BC are connected in series and then energized in parallel with the phase A winding. The windings A-B-C-A-B are switched in sequence to make the rotor rotate step by step. The resulting step angle θ s =180° / PN r =180° / 5N r Where N r is the number of rotor teeth, and P is the number of pole pairs.

[0078] Its driving circuit is shown in Figure 7 As shown in (a).

[0079] The present invention can realize position and speed servo control without any additional sensors.

[0080] The present invention also has the advantages of a stepper motor:

[0081] (1) The motor has a simple and strong structure, simple manufacturing process and low cost. The rotor is made of laminated silicon steel sheets and uses only a small amount of axially embedded annular magnetic steel, which can operate at extremely high speeds. The stator coil is a concentrated winding, which is easy to embed, has short and firm ends, and works reliably. It can be used in various harsh, high-temperature and strong vibration environments.

[0082] (2) The loss mainly occurs in the stator, the motor is easy to cool, and a higher temperature rise is allowed.

[0083] (3) Convenient drive control, small number of power switching components, and low system cost.

[0084] Specific embodiment 2: This embodiment differs from embodiment 1 in that, in order to further improve reliability, the present invention adds a special mechanical auxiliary bearing to adapt to heavy loads and all-weather extreme environments. The bearing clearance of the auxiliary bearing is 0.1-1 mm.

[0085] To increase the load variation on the output shaft, an auxiliary bearing can be added. This auxiliary bearing can be smaller than a traditional bearing to reduce bearing friction. An elastic rubber ring can be placed around the outer diameter of the auxiliary bearing to provide mechanical cushioning, reducing motor vibration and noise. The bearing clearance of the auxiliary bearing can be increased from negative clearance to 0.1 to 1 mm. The restoring force of the natural electromagnetic levitation maintains the axis stability of the motor output shaft. Despite the presence of the auxiliary bearing, the natural electromagnetic levitation still allows the motor rotor to rotate with minimal energy loss, resulting in minimal vibration and noise, just like the natural rotation of the Earth and the Sun in space.

[0086] In a specific embodiment, the motor of the present invention uses a pair of auxiliary bearings with a bearing clearance of 0.1 to 0.5 mm. The number of windings per phase of the stepper motor is an even number, so each phase winding of this type of motor can form a winding symmetrically distributed 180° along the circumference and can generate a 180° symmetrical couple torque.

[0087] 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 used in conjunction with other described embodiments.

Claims

1. The natural magnetic levitation stepper motor used in extreme environments is characterized by: It includes an outer stator and an inner rotor. The inner rotor is composed of two rotor cores of the same structure arranged in parallel along the axial direction. An axial permanent magnet is set between the two rotor cores. The geometric axes of the two rotor units are staggered by 1 / 2τ. τ is the rotor tooth pitch. The outer stator includes a stator core and a stator winding. The inner surface of the stator core is uniformly distributed with Z d stator slots, each stator tooth is evenly distributed with stator teeth; The stator slots are wound with m-phase stator windings, and each phase winding is Z-shaped and symmetrically distributed along the circumference at 180°. d / m elements are connected in parallel to generate a 180° symmetrical couple torque; the conditions are met: Z d / m is an even number; The m phase windings are connected end to end, and the m contacts formed by the adjacent phase windings are connected to the driver. The driver controls the m phase windings to be energized simultaneously according to the following rules: When any phase winding is energized, the other m-1 phase windings are connected in series and then energized in parallel with it; The power-on sequence is A→B→…→m→A→B.

2. The natural magnetic levitation stepping motor for use in extreme environments according to claim 1, characterized in that: When m=5, the five-phase ten-wire stepper motor is constructed as follows: Each phase winding is set to Z d / m=10 / 5=2 elements. Connect the two elements of each phase in parallel head-to-head and tail-to-tail to form two branches. The head ends of the five phases form the positive input ports of A, B, C, D, and E, and the tail ends of the five phases form the negative input ports of A, B, C, D, and E. The five-phase winding generates a restoring force against the radial deviation of the motor in 10 directions. Each phase winding is connected end to end, with the drive end led out from five contacts. When the A phase winding is energized, the other four windings BCDE are connected in series and then energized in parallel with the A phase winding. The windings A-B-C-D-E-A-B are switched in sequence to make the rotor rotate step by step. The resulting step angle θ s =180° / PN r =180° / 5N r Where N r is the number of rotor teeth, and P is the number of pole pairs.

3. The natural magnetic levitation stepping motor for use in extreme environments according to claim 1, characterized in that: When m=5, the five-phase six-wire stepper motor is constructed as follows: Each phase winding is set to Z d / m=10 / 5=2 elements. Connect the two elements of each phase head-to-head and tail-to-tail in parallel to form two branches. The head ends of the five phases form the positive input ports of A, B, C, D, and E. The tail ends of the five phases are connected in parallel to form the midpoint port of the motor. The five-phase winding generates a restoring force against the radial deviation of the motor from 10 directions. Each phase winding is connected end to end, with the drive end led out from five contacts. When the A phase winding is energized, the other four windings BCDE are connected in series and then energized in parallel with the A phase winding. The windings A-B-C-D-E-A-B are switched in sequence to make the rotor rotate step by step. The resulting step angle θ s =180° / PN r =180° / 5N r Where N r is the number of rotor teeth, and P is the number of pole pairs.

4. The natural magnetic levitation stepping motor for use in extreme environments according to claim 1, characterized in that: When m=4, the four-phase eight-wire stepper motor is constructed as follows: Each phase winding is set to Z d / m=8 / 4=2 elements. Connect the two elements of each phase in parallel head-to-head and tail-to-tail to form two branches. The head ends of the four phases form the positive input ports of A, B, C, and D, and the tail ends of the four phases form the negative input ports of A, B, C, and D. The four-phase winding generates restoring forces against the radial deviation of the motor from eight directions. Each phase winding is connected end to end, with the drive end led out from four contacts. When the A phase winding is energized, the other three windings BCD are connected in series and then energized in parallel with the A phase winding. The windings A-B-C-D-A-B are switched in sequence to make the rotor rotate step by step. The resulting step angle θ s =180° / PN r =180° / 5N r Where N r is the number of rotor teeth, and P is the number of pole pairs.

5. The natural magnetic levitation stepping motor for use in extreme environments according to claim 1, characterized in that: When m=4, the four-phase five-wire stepper motor is constructed as follows: Each phase winding is set to Z d / m=8 / 4=2 elements. The two elements of each phase are connected in parallel head-to-head and tail-to-tail to form two branches. The head ends of the four phases form the positive input ports of A, B, C, and D. The tail ends of the four phases are connected in parallel to form the midpoint port of the motor. The four-phase winding generates restoring force against the radial deviation of the motor from eight directions. Each phase winding is connected end to end, with the drive end led out from four contacts. When the A phase winding is energized, the other three windings BCD are connected in series and then energized in parallel with the A phase winding. The windings A-B-C-D-A-B are switched in sequence to make the rotor rotate step by step. The resulting step angle θ s =180° / PN r =180° / 5N r Where N r is the number of rotor teeth, and P is the number of pole pairs.

6. The natural magnetic levitation stepping motor for use in extreme environments according to claim 1, characterized in that: When m=3, the three-phase six-wire stepper motor is constructed as follows: Each phase winding is set to Z d / m=6 / 3=2 elements. Connect the two elements of each phase in parallel head-to-head and tail-to-tail to form two branches. The head ends of the four phases form the positive input ports of the three phases A, B, and C, and the tail ends of the four phases form the negative input ports of the three phases A, B, and C. The three-phase winding generates a restoring force against the radial deviation of the motor from six directions. The phase windings are connected end to end, with the drive end led out from three contacts. When the phase A winding is energized, the other two windings BC are connected in series and then energized in parallel with the phase A winding. The windings A-B-C-A-B are switched in sequence to make the rotor rotate step by step. The resulting step angle θ s =180° / PN r =180° / 5N r Where N r is the number of rotor teeth, and P is the number of pole pairs.

7. The natural magnetic levitation stepping motor for use in extreme environments according to claim 1, characterized in that: When m=3, the three-phase four-wire stepper motor is constructed as follows: Each phase winding is set to Z d / m=6 / 3=2 elements. The two elements of each phase are connected head-to-head and tail-to-tail in parallel to form two branches. The head ends of the three phases form the positive input ports of A, B, and C. The tail ends of the three phases are connected in parallel to form the midpoint port of the motor. The three-phase winding generates a restoring force against the radial deviation of the motor from six directions. The phase windings are connected end to end, with the drive end led out from three contacts. When the phase A winding is energized, the other two windings BC are connected in series and then energized in parallel with the phase A winding. The windings A-B-C-A-B are switched in sequence to make the rotor rotate step by step. The resulting step angle θ s =180° / PN r =180° / 5N r Where N r is the number of rotor teeth, and P is the number of pole pairs.

8. The natural magnetic levitation stepping motor for use in extreme environments according to claim 1, characterized in that: Auxiliary bearings are provided, and the bearing clearance of the auxiliary bearings is 0.1 to 1 mm.

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