Variable flux memory motor and shaftless rim underwater propeller

Abstract

The invention discloses a variable flux memory motor and a shaftless rim underwater thruster, the motor comprises a stator, an armature winding, a rotor, a plurality of low-coercivity permanent magnets and a plurality of high-coercivity permanent magnets, the armature winding adopts a twelve-phase winding, the low-coercivity permanent magnets and the high-coercivity permanent magnets are arranged in the rotor and are alternately distributed in the circumferential direction; the low-coercive-force permanent magnet is connected with the high-coercive-force permanent magnet in series in a magnetism increasing state and a magnetism weakening state, and in the magnetism increasing state, the magnetomotive force direction of the low-coercive-force permanent magnet is consistent with that of the high-coercive-force permanent magnet; and in the weak magnetic state, the reverse is achieved. By adopting the series magnetic circuit structure design of the two different coercive force permanent magnets, the load magnetic stabilization capability of the low-coercive force permanent magnets in the motor can be effectively improved, so that the magnetic field stability and the overall performance of the motor are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of permanent magnet synchronous motors, and particularly relates to a variable flux memory motor and an underwater propeller without shaft and rim. BACKGROUND

[0002] With the increasing demand for underwater operation and the increasing requirement for high-efficiency motors, the traditional propeller motor without shaft and rim is facing various technical challenges. Although the traditional three-phase permanent magnet synchronous motor has a simple structure and is easy to manufacture, it has low efficiency and large torque ripple when facing high-speed and low-torque working conditions, and the traditional magnetic circuit structure cannot flexibly adjust the magnetic flux density, resulting in limited motor performance. These problems are particularly prominent in underwater propeller applications. In addition, the fault tolerance of the traditional three-phase permanent magnet synchronous motor is poor, and the failure of one phase will cause the entire motor to malfunction. The reliability and operating efficiency of the traditional three-phase motor are difficult to meet the requirements of complex underwater environments.

[0003] As a new type of motor, the variable flux memory motor can improve the overall electromagnetic performance of the motor by adjusting the magnetic flux density and changing the working state of the motor, especially in different load and speed conditions. However, the existing variable flux memory motor still has problems such as limited magnetic flux adjustment range and poor fault tolerance. In particular, the traditional series magnetic circuit type variable flux memory motor has certain restrictions on the magnetic adjustment range, and cannot provide ideal electromagnetic performance under multiple working conditions, affecting the efficient operation of the motor under all working conditions. SUMMARY

[0004] The main purpose of the application is to provide a variable flux memory motor and an underwater propeller without shaft and rim to solve the problems of insufficient stability and reliability of the existing traditional underwater propeller motor.

[0005] To achieve the aforementioned objective, the present invention employs the following technical solution: a variable flux memory motor, comprising a stator, an armature winding, a rotor, and permanent magnets; the armature winding is wound around the stator and employs a twelve-phase winding; the rotor is located inside the stator and rotates relative to the stator; the permanent magnets are disposed inside the rotor and comprise multiple low-coercivity permanent magnets and multiple high-coercivity permanent magnets, the low-coercivity permanent magnets and the high-coercivity permanent magnets being alternately distributed in the circumferential direction; each low-coercivity permanent magnet extends circumferentially on the rotor, its magnetization direction is radial magnetization, and adjacent low-coercivity permanent magnets are arranged in a radial direction. The permanent magnets are magnetized in opposite directions; each of the high coercivity permanent magnets is arranged radially on the rotor, and its magnetization direction is tangential along the circumference, with adjacent high coercivity permanent magnets having opposite magnetization directions; during motor operation, the magnetization state of the low coercivity permanent magnets is changed by applying d-axis current, thereby dynamically adjusting the motor's magnetic flux; the low coercivity permanent magnets are connected in series with the high coercivity permanent magnets in both magnetization and magnetization weakening states, and in the magnetization strengthening state, the magnetomotive force direction of the low coercivity permanent magnets is consistent with that of the high coercivity permanent magnets; in the magnetization weakening state, the magnetomotive force direction of the low coercivity permanent magnets is opposite to that of the high coercivity permanent magnets.

[0006] In a preferred embodiment, the twelve-phase winding consists of four sets of three-phase windings, with each set of three-phase windings having a phase difference of 15° electrical angle.

[0007] In a preferred embodiment, each of the low coercivity permanent magnets includes a first layer of low coercivity permanent magnets and a second layer of low coercivity permanent magnets. Both the first layer of low coercivity permanent magnets and the second layer of low coercivity permanent magnets extend along the circumferential direction and are radially distributed. Both magnetize in the same direction, which is radial magnetization.

[0008] In a preferred embodiment, the first layer of low coercivity permanent magnets is in the shape of a straight line, and the second layer of low coercivity permanent magnets is in the shape of a V-shape that protrudes towards the center of the rotor.

[0009] In a preferred embodiment, each of the high coercivity permanent magnets includes a layer of high coercivity permanent magnets, and each high coercivity permanent magnet is in the shape of a line.

[0010] In a preferred embodiment, a low-coercivity permanent magnet is magnetized or demagnetized by applying a d-axis current. The low-coercivity permanent magnet and the high-coercivity permanent magnet are uniformly and alternately distributed in the circumferential direction.

[0011] In a preferred embodiment, the ratio of the rotor's inner diameter to its shaft length is greater than or equal to 2.5, which is suitable for shaftless rimmed underwater propulsion.

[0012] In a preferred embodiment, the material of the high-coercivity permanent magnet is neodymium iron boron, and the material of the low-coercivity permanent magnet is aluminum-nickel-cobalt.

[0013] In another aspect, the application also adopts another technical solution, comprising: an axleless rim underwater propeller comprising the variable magnetic flux memory motor and a paddle connected with the variable magnetic flux memory motor.

[0014] In a preferred embodiment, the inner surface of the rotor of the variable magnetic flux memory motor is directly connected with the paddle.

[0015] Compared with the prior art, the application has at least the following beneficial effects:

[0016] 1. The application adopts the series magnetic circuit structure design of two different coercivity permanent magnets, which can effectively improve the load stability of the low-coercivity permanent magnet in the motor, thereby improving the magnetic field stability and overall performance of the motor; at the same time, the design of the double-layer low-coercivity permanent magnet effectively improves the magnetic adjustment range of the motor, solves the deficiency of the traditional series magnetic circuit type variable magnetic flux memory motor in the magnetic adjustment ability, improves the operating efficiency of the motor under multiple working conditions, and realizes the high-efficiency operation of the motor under different working conditions.

[0017] 2. The motor of the application adopts the twelve-phase redundant winding design, which improves the fault tolerance ability of the motor, enables it to operate stably in a complex underwater environment, and increases the reliability of the motor. In addition, the phase difference between the four sets of three-phase windings is designed to be fifteen degrees of electrical angle on average, which effectively reduces the torque ripple of the motor and improves the average output torque of the motor.

[0018] 3. The motor of the application adopts a larger inner diameter and shaft length ratio design, which is suitable for the axleless rim underwater propeller, the propeller blade can be directly connected with the inner wall of the rotor, the mechanical transmission structure of the traditional propulsion system is omitted, the system structure is simplified, the mechanical loss in the transmission process is reduced, and the overall efficiency and reliability of the driving system are improved.

[0019] 4. The motor of the application is particularly suitable for underwater working environments such as submarines and unmanned underwater vehicles, etc., and can provide efficient, stable and reliable power support under complex and variable working conditions. Through the optimization of winding design, permanent magnet arrangement and magnetic circuit structure, the application not only solves the deficiencies of the traditional motor in the magnetic adjustment range, torque ripple and fault tolerance ability, but also significantly improves the high-efficiency speed range of the system. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to make the technical solutions of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only aim to explain some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0021] Figure 1 is a structural schematic diagram of a variable-flux memory motor of the present application;

[0022] Figure 2 is a schematic diagram of a partial A in the motor in the magnetic enhancement state of the present application, wherein the arrow direction represents the magnetization direction of the permanent magnet; Figure 1

[0023] Figure 3 is a schematic diagram of a partial A in the motor in the magnetic weakening state of the present application, wherein the arrow direction represents the magnetization direction of the permanent magnet; Figure 1

[0024] Figure 4 is a magnetic flux path diagram of a partial A in the motor in the magnetic enhancement state of the present application; Figure 1

[0025] Figure 5 is a magnetic flux path diagram of a partial A in the motor in the magnetic weakening state of the present application; Figure 1

[0026] Figure 6 is a comparison between the present application and a conventional three-phase series magnetic circuit type shaftless rim variable-flux memory motor, T ave is the average value of the motor output torque (unit: N·m), T rip is the percentage of torque ripple. The motor output torque waveform schematic diagram of the motor in the magnetic enhancement state and the magnetic weakening state.

[0027] Reference signs:

[0028] 1, stator, 11, stator yoke part, 12, stator tooth part, 2, armature winding, 3, rotor, 4, low-coercivity permanent magnet, 41, first layer low-coercivity permanent magnet, 42, second layer low-coercivity permanent magnet, 5, high-coercivity permanent magnet. DETAILED DESCRIPTION

[0029] ​​​​The present application will be more fully understood by reference to the following detailed description when taken in conjunction with the accompanying drawings. Specific embodiments of the application are disclosed herein; however, the application is not limited to the disclosed embodiments. Rather, the specific functional details disclosed herein are meant to be illustrative only and are not limiting as the application can be embodied in various forms. Therefore, the specific functional details disclosed herein are not to be interpreted as limiting, but rather as a representative basis for teaching one skilled in the art of the application in various ways.

[0030] The variable flux memory motor and shaftless rim underwater propeller disclosed by the present application aims to solve the shortcomings of traditional motors in torque pulsation, flux modulation range and fault tolerance. The motor can effectively improve the load stability of low coercivity permanent magnets in the motor by adopting the series magnetic circuit structure design of two different coercivity permanent magnets, thereby improving the magnetic field stability and overall performance of the motor. At the same time, the design of double-layer low coercivity permanent magnets effectively improves the flux modulation range of the motor, solves the shortcomings of traditional series magnetic circuit type variable flux memory motor in flux modulation ability, and improves the operating efficiency of the motor under multiple working conditions.

[0031] In combination with Figures 1 to 3 As shown in the figure, the variable flux memory motor disclosed by the embodiment of the present application specifically comprises a stator 1, an armature winding 2, a rotor 3 and a permanent magnet. The armature winding 2 is installed in the stator 1, the rotor 3 is located inside the stator 1 and rotates relative to the stator 1, and the permanent magnet is arranged on the rotor 3.

[0032] Specifically, in the present embodiment, the stator 1 specifically comprises a stator yoke part 11 and a stator tooth part 12. The stator 1 is provided with a stator slot (not shown in the figure), and the armature winding 2 is installed in the stator slot for generating induced electromotive force during the operation of the motor.

[0033] The armature winding 2 of the present application preferably adopts a twelve-phase winding design, which specifically can be composed of four sets of three-phase windings. The phase difference between each set of three-phase windings is 15° electrical angle, forming a four-fold three-phase star winding structure. This design effectively reduces the torque pulsation of the motor, reduces the mechanical vibration and noise during operation, and at the same time improves the average output torque of the motor. In addition, the twelve-phase redundant design significantly enhances the fault tolerance of the motor. Even if a certain phase winding fails, the remaining windings can still work, ensuring the stable operation of the motor under complex working conditions.

[0034] The rotor 3 adopts a combination design of two different materials of permanent magnets, and the permanent magnets specifically include a plurality of low-coercivity permanent magnets 4 and a plurality of high-coercivity permanent magnets 5. The low-coercivity permanent magnets 4 and the high-coercivity permanent magnets 5 are alternately distributed in the circumferential direction of the rotor 3, that is, one high-coercivity permanent magnet 5 is arranged at intervals of one low-coercivity permanent magnet 4, and preferably uniformly and alternately distributed in the circumferential direction. The low-coercivity permanent magnet 4 is located between the two adjacent high-coercivity permanent magnets 5 in the circumferential direction.

[0035] Each low-coercivity permanent magnet 4 is arranged in the circumferential direction on the rotor 3, and the magnetization direction is radial magnetization, and the magnetization directions of the two adjacent low-coercivity permanent magnets 4 are opposite. Preferably, each low-coercivity permanent magnet 4 includes a first layer of low-coercivity permanent magnets 41 and a second layer of low-coercivity permanent magnets 42, and the first layer of low-coercivity permanent magnets 41 and the second layer of low-coercivity permanent magnets 42 are arranged in the circumferential direction and distributed in the radial direction, and the magnetization directions of the two layers are the same, that is, radial magnetization. In the embodiment, the first layer of low-coercivity permanent magnets 41 is a character, and the second layer of low-coercivity permanent magnets 42 is a V-shaped character protruding towards the center of the rotor 3.

[0036] Each high-coercivity permanent magnet 5 is arranged in the radial direction on the rotor 3, and the magnetization direction is circumferential tangential magnetization, and the magnetization directions of any two adjacent high-coercivity permanent magnets 5 are opposite. Preferably, each high-coercivity permanent magnet 5 includes at least one layer of high-coercivity permanent magnets, and in the embodiment, each high-coercivity permanent magnet 5 includes one layer of high-coercivity permanent magnets, and each layer of high-coercivity permanent magnets is in the form of a character.

[0037] During the operation of the motor, the magnetization state of the low-coercivity permanent magnet 4 is changed by applying a d-axis current, thereby dynamically adjusting the magnetic flux of the motor. Specifically, by applying a d-axis current, the low-coercivity permanent magnet 4 can be magnetized or demagnetized, and on the basis of the change of the magnetic motive force of the low-coercivity permanent magnet 4, the magnetic adjustment performance of the memory motor is further improved, and the speed regulation range of the motor is expanded.

[0038] The low-coercivity permanent magnet in this invention is designed as a two-layer structure, and these two layers of low-coercivity permanent magnets (i.e., the first layer of low-coercivity permanent magnet 41 and the second layer of low-coercivity permanent magnet 42) are connected in series with the high-coercivity permanent magnet 5 in both magnetization and magnet weakening states. Through this series magnetic circuit design, in the magnetization state, the low-coercivity permanent magnet 4 and the high-coercivity permanent magnet 5 together form a stable magnetic field; in the magnet weakening state, by adjusting the direction of the magnetomotive force, part of the magnetic flux is short-circuited, thereby effectively adjusting the air gap magnetic flux density and widening the high-efficiency speed range. In both magnetization and magnet weakening states, the low-coercivity permanent magnet 4 and the high-coercivity permanent magnet 5 are interconnected through the series magnetic circuit design. When the magnetomotive force directions are consistent, a stable series magnetic circuit is formed; when the low-coercivity permanent magnet 4 enters the magnet weakening state, its magnetomotive force direction is opposite to that of the high-coercivity permanent magnet 5, causing a magnetic flux short circuit, thereby adjusting the air gap magnetic flux density.

[0039] Specifically, such as Figure 4 As shown, in the initial state, the low-coercivity permanent magnet 4 is in a magnetized state, and the low-coercivity permanent magnet 4 and the high-coercivity permanent magnet 5 form a series magnetic circuit. The direction of its magnetomotive force is consistent with the direction of the magnetomotive force of the high-coercivity permanent magnet 5. At this time, the magnetic flux passes through the low-coercivity permanent magnet 4 and the high-coercivity permanent magnet 5 in sequence, forming a stable air gap magnetic field, providing higher output torque and air gap magnetic flux density, which is suitable for low-speed, high-torque operating conditions. Figure 5 As shown, when a d-axis demagnetizing current pulse is applied to the low-coercivity permanent magnet 4, the low-coercivity permanent magnet 4 switches to a weakened magnetic state. At this time, the magnetomotive force of the low-coercivity permanent magnet 4 is opposite to that of the high-coercivity permanent magnet 5, causing some magnetic flux to be short-circuited, thereby effectively reducing the air gap magnetic flux density and widening the high-efficiency speed range of the motor, making it suitable for high-speed operation. If it is necessary to restore the low-speed, high-torque state, a d-axis magnetizing pulse current can be applied again to restore the magnetization state of the low-coercivity permanent magnet 4. This magnetic flux regulation mechanism allows the motor to flexibly adjust its performance under different operating conditions, meeting the requirements of underwater operations for high efficiency and a wide speed range.

[0040] Preferably, the high-coercivity permanent magnet 5 is made of neodymium iron boron material, which has high remanence and coercivity, thus providing stable magnetic flux under various operating conditions. The two layers of low-coercivity permanent magnets 4 (i.e., the first layer 41 and the second layer 42) are both made of AlNiCo material, exhibiting reversible magnetic change characteristics, facilitating rapid switching of magnetization states via d-axis pulse current. This material combination and magnetic circuit design further enhance the motor's magnetic adjustment capability and operating efficiency.

[0041] like Figure 6As shown, by comparing the output torque waveform of the motor of the application with that of a conventional three-phase series magnetic circuit type shaftless rim variable flux memory motor, the superiority of the twelve-phase winding design can be verified. To ensure fairness of comparison, the rotor structure and permanent magnet design of the conventional three-phase motor are consistent with the application, only the armature winding part is different. In the state of magnetic enhancement and flux weakening, the torque ripple of the motor of the application is significantly lower than that of the conventional three-phase motor, the average output torque is higher, and the running stability is stronger. Among them, T ave represents the average value of the motor output torque, unit: Nm, T rip represents the percentage of motor torque ripple.

[0042] Preferably, the rotor 3 is designed with an inner diameter (i.e. the inner diameter of the rotor 3) and a shaft length (i.e. the axial length of the motor rotor 3) ratio greater than or equal to 2.5, commonly used interval is 2.5-4.0, taking into account the electromagnetic performance and mechanical reliability, to adapt to the design requirements of shaftless rim propeller. This direct drive system eliminates the mechanical transmission shaft structure in the traditional propeller, reduces mechanical loss and maintenance requirements, and improves the overall efficiency of the system.

[0043] The application also provides a shaftless rim underwater propeller, comprising the above variable flux memory motor and a propeller blade (not shown in the figure) connected with the variable flux memory motor, preferably the inner surface of the rotor 3 can be directly connected with the propeller blade of the underwater propeller, in contact with the water flow during operation, which can effectively reduce the rotor temperature and maintain the magnetic stability of the permanent magnet, thereby further improving the running reliability and thermal performance of the motor in underwater environment.

[0044] The application has the following advantages: 1. The application adopts the series magnetic circuit structure design of two different coercive force permanent magnets, which can effectively improve the load stability of the low coercive force permanent magnet in the motor, thereby improving the magnetic field stability and overall performance of the motor; at the same time, the design of the double-layer low coercive force permanent magnet effectively improves the magnetic adjustment range of the motor, solves the deficiency of the traditional series magnetic circuit type variable magnetic flux memory motor in the magnetic adjustment ability, improves the operation efficiency of the motor under multiple working conditions, and realizes the efficient operation of the motor under different working conditions. 2. The motor of the application adopts a twelve-phase redundant winding design, which improves the fault tolerance capability of the motor, enables it to operate stably in a complex underwater environment, and increases the reliability of the motor. In addition, the phase difference between the four sets of three-phase windings is designed to be fifteen degrees of electrical angle on average, which effectively reduces the torque ripple of the motor, reduces vibration and noise, and improves the average output torque of the motor. 3. The motor of the application adopts a larger inner diameter and shaft length ratio design, which is suitable for a shaftless rim underwater propeller. The propeller blades can be directly connected to the inner wall of the rotor, eliminating the mechanical transmission structure of the traditional propulsion system, simplifying the system structure, and reducing mechanical loss in the transmission process; at the same time, the characteristics of the rotor contacting the water flow effectively reduce the operating temperature, and improve the overall efficiency and reliability of the driving system. 4. The motor of the application is particularly suitable for underwater working environments such as submarines and unmanned underwater vehicles, and can provide efficient, stable and reliable power support under complex and variable working conditions. Through the optimization of winding design, permanent magnet arrangement and magnetic circuit structure, the application not only solves the deficiencies of the traditional motor in the magnetic adjustment range, torque ripple and fault tolerance capability, but also significantly improves the high-efficiency speed range of the system.

[0045] Aspects, embodiments, features, and examples of the application are to be considered in all respects as illustrative only and not restrictive, the scope of the application being defined solely by the claims. Other embodiments, modifications, and uses will occur to those skilled in the art upon considering the specification, and are intended to be within the scope of the claimed application.

[0046] The use of headings and sections in the present application is not meant to imply limitations; each section can apply to any aspect, embodiment, or feature of the application.

Claims

1. A variable flux memory motor, characterized in that: The motor includes a stator, an armature winding, a rotor, and permanent magnets. The armature winding is wound around the stator and employs a twelve-phase winding. The rotor is located inside the stator and rotates relative to it. The permanent magnets are disposed inside the rotor and include multiple low-coercivity permanent magnets and multiple high-coercivity permanent magnets, which are alternately distributed in a circumferential direction. Each low-coercivity permanent magnet extends circumferentially on the rotor, with its magnetization direction being radial, and adjacent low-coercivity permanent magnets having opposite magnetization directions. High coercivity permanent magnets are arranged radially on the rotor, and their magnetization direction is tangential along the circumference. The magnetization directions of two adjacent high coercivity permanent magnets are opposite. During motor operation, the magnetization state of low coercivity permanent magnets is changed by applying d-axis current, thereby dynamically adjusting the magnetic flux of the motor. The low coercivity permanent magnets are connected in series with the high coercivity permanent magnets in both magnetization and magnetization weakening states. In the magnetization strengthening state, the magnetomotive force direction of the low coercivity permanent magnets is consistent with that of the high coercivity permanent magnets. In the magnetization weakening state, the magnetomotive force direction of the low coercivity permanent magnets is opposite to that of the high coercivity permanent magnets.

2. The variable flux memory motor according to claim 1, characterized in that: The twelve-phase winding consists of four sets of three-phase windings, with a phase difference of 15° electrical degrees between each set of three-phase windings.

3. A variable flux memory motor according to claim 1, characterized in that: Each of the low coercivity permanent magnets includes a first layer of low coercivity permanent magnets and a second layer of low coercivity permanent magnets. Both the first layer of low coercivity permanent magnets and the second layer of low coercivity permanent magnets extend along the circumferential direction and are radially distributed. Both magnetize in the same direction, which is radial magnetization.

4. A variable flux memory motor according to claim 3, characterized in that: The first layer of low coercivity permanent magnets is in the shape of a straight line, and the second layer of low coercivity permanent magnets is in the shape of a V-shape that protrudes towards the center of the rotor.

5. A variable flux memory motor according to claim 1, characterized in that: Each of the high coercivity permanent magnets comprises at least one layer of high coercivity permanent magnets, and each layer of high coercivity permanent magnets is in a straight line.

6. A variable flux memory motor according to claim 1, characterized in that: The low coercivity permanent magnet is magnetized or demagnetized by applying a d-axis current. The low coercivity permanent magnet and the high coercivity permanent magnet are uniformly and alternately distributed in the circumferential direction.

7. A variable flux memory motor according to claim 1, characterized in that: The ratio of the inner diameter of the rotor to its shaft length is greater than or equal to 2.5, making it suitable for shaftless rimmed underwater propulsion.

8. A variable flux memory motor according to any one of claims 1 to 6, characterized in that: The high coercivity permanent magnet is made of neodymium iron boron, and the low coercivity permanent magnet is made of aluminum nickel cobalt.

9. A shaftless rimmed underwater propulsion device, characterized in that: It includes the variable flux memory motor as described in any one of claims 1 to 8 and the blade connected to the variable flux memory motor.

10. A shaftless rimmed underwater propulsion device according to claim 9, characterized in that: The inner surface of the rotor of the variable flux memory motor is directly connected to the blade.

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