Radial magnetic field compound motor

Abstract

The present invention relates to the field of motor design, and discloses a radial magnetic field composite motor, comprising a rotating shaft, a first bearing surrounding the rotating shaft, an inner stator surrounding the first bearing, an inner rotor surrounding the inner stator, a magnetic isolation ring surrounding the inner rotor, an outer rotor surrounding the magnetic isolation ring, and an outer stator surrounding the outer rotor; air gaps are provided between the outer stator and the outer rotor and between the inner stator and the inner rotor; the inner stator is rotatably connected to the rotating shaft through the first bearing, and the outer rotor is fixedly connected to the inner rotor through the magnetic isolation ring; the outer rotor, the magnetic isolation ring and the inner rotor constitute the motor rotor, and are fixedly connected to the rotating shaft through a rotor bracket, and the outer stator is fixed on the housing and rotatably connected to the rotating shaft. The present invention meets the requirements of low-speed, high-torque and wide speed regulation range operation of the driving motor under the premise of improving the operating reliability of the permanent magnet and avoiding irreversible demagnetization of the permanent magnet due to weak magnetic speed regulation and high temperature.

Description

Technical Field

[0001] The invention relates to the field of motor design, and in particular to a radial magnetic field composite motor. Background Art

[0002] High torque density, low speed and high torque, and wide speed range are the performance requirements of drive motors, especially direct drive motors. The widely used switched reluctance motor has a wide speed range and a simple structure. There are no permanent magnets on the stator and rotor, and the working reliability is high. However, its torque density is significantly lower than that of permanent magnet motors. In recent years, stator permanent magnet motors have been widely studied due to their high torque density and high efficiency. In this motor structure, permanent magnets and windings are placed on the stator, and the rotor structure is simple, which improves the reliability and dynamic operation performance of the motor. However, due to the inherent characteristics of permanent magnets, the air gap magnetic field of the stator permanent magnet motor remains basically constant during operation. During electric operation, the motor excitation control is difficult and the speed range is limited. Scholars often use hybrid excitation to increase the speed range of stator permanent magnet motors. In addition to permanent magnets, excitation windings are also set on the stator to realize dual excitation source hybrid excitation, which can improve the magnetic field regulation capability and widen the speed operation range. However, the high-speed weak magnetic speed regulation in the motor speed regulation process will reduce the working performance of the permanent magnet, and in severe cases, lead to irreversible demagnetization of the permanent magnet. In addition, in the structure of the hybrid excitation stator permanent magnet motor, the stator has both permanent magnets and two sets of windings (excitation winding and armature winding). On the one hand, the magnetic circuit saturation is high, and on the other hand, the armature winding placement space is constrained, which limits the torque output capacity to a certain extent. Moreover, since the heat source is located in the stator, it is easy to cause the stator winding and permanent magnet temperature to rise too high, resulting in winding insulation damage and irreversible demagnetization of the permanent magnet. Summary of the invention

[0003] Purpose of the invention: In view of the problems existing in the prior art, the present invention provides a radial magnetic field composite motor, which meets the requirements of low-speed, high-torque and wide speed regulation range operation of the driving motor while improving the operating reliability of the permanent magnet and avoiding irreversible demagnetization of the permanent magnet due to weak magnetic speed regulation.

[0004] Technical solution: The present invention provides a radial magnetic field composite motor, comprising a rotating shaft, a first bearing surrounding the rotating shaft, an inner stator surrounding the first bearing, an inner rotor surrounding the inner stator, a magnetic isolation ring surrounding the inner rotor, an outer rotor surrounding the magnetic isolation ring, and an outer stator surrounding the outer rotor; air gaps are provided between the outer stator and the outer rotor and between the inner stator and the inner rotor; the inner stator is rotatably connected to the rotating shaft through the first bearing, and the outer rotor is fixedly connected to the inner rotor through the magnetic isolation ring; the outer rotor, the magnetic isolation ring and the inner rotor constitute a motor rotor, and are fixedly connected to the rotating shaft through a rotor bracket, and the outer stator is fixed on the outer casing and rotatably connected to the rotating shaft.

[0005] Furthermore, salient pole teeth are provided on opposite sides of the outer stator and the outer rotor, and on opposite sides of the inner stator and the inner rotor, and outer windings are provided on the salient pole teeth of the outer stator, and inner windings and excitation devices are provided on the salient pole teeth of the inner stator.

[0006] Preferably, the magnetizing direction of the excitation device is alternating magnetizing tangentially along the circumference of the inner stator.

[0007] Preferably, the excitation device is a permanent magnet or a hybrid excitation device. When a hybrid excitation device is used, the electric excitation source is only used for low-speed magnetization to increase the output torque capacity, and there is no high-speed weak magnetic working mode.

[0008] Preferably, the number of salient pole teeth of the outer stator is P so , the outer winding consists of symmetrically distributed P so The outer winding is composed of a coil sleeved on the salient pole teeth of the outer stator. m Phase concentrated winding, meet P so =2 k 1 m , where k 1 A positive integer; the number of teeth of the salient pole teeth of the outer rotor is P ro ,satisfy P ro = P so ±2N 1 , where N 1 Is a positive integer.

[0009] Preferably, the number of teeth of the inner stator salient pole teeth is P si , the inner winding consists of symmetrically distributed P si The inner winding is composed of a coil sleeved on the salient pole teeth of the inner stator. n Phase concentrated winding, meet P si =2 k 2 n , where k 2 A positive integer; the number of salient pole teeth of the inner rotor is P ri ,satisfy P ri = P si ±2N2 , where N 2 Is a positive integer.

[0010] Preferably, the salient pole teeth on the outer stator, the outer rotor, the inner stator and the inner rotor are all oriented in the radial direction.

[0011] Preferably, both the inner winding and the outer winding are multi-phase concentrated armature windings.

[0012] Beneficial effects: In the radial magnetic field composite motor of the present invention, the outer stator and the outer rotor constitute the outer motor, and the inner stator and the inner rotor constitute the inner motor. The inner and outer motors are completely independent and have no electromagnetic coupling, so they can be controlled independently. There are a variety of motor structure options for the inner and outer motors. For example, the inner motor can adopt a double-pole permanent magnet motor and a flux reversal motor. The stator and rotor tooth slot matching, phase number and excitation method of the inner and outer motors of the radial magnetic field composite motor proposed by the present invention can be flexibly adjusted according to the system performance requirements.

[0013] In the present invention, the inner stator is rotatably connected to the rotating shaft through the first bearing, and can rotate at a certain speed during operation. The outer rotor is fixedly connected to the inner rotor through the magnetic isolation ring, and the outer rotor, the magnetic isolation ring, and the inner rotor constitute the motor rotor, and are fixedly connected to the rotating shaft through the rotor bracket. The outer diameter of the outer stator is fixed on the housing, has no speed, and is rotatably connected to the rotating shaft through the second bearing and the third bearing.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. In the present invention, the outer motor mainly realizes the speed regulation of the motor according to the load speed requirement, so that the rotor output shaft rotates at the target speed; the role of the inner motor is to provide driving torque or braking torque according to the load requirements to make up for the lack of output torque of the outer motor. During the operation of the motor, the inner stator can rotate at a certain speed and the inner rotor differentially, so that the inner motor always works near the rated point with higher efficiency, and thus has a larger torque output capacity. Whether it is running at low speed or high speed, the lack of output torque of the outer motor can be provided by the inner motor, thereby realizing the requirements of low-speed, high-torque and wide speed regulation range operation of the motor.

[0016] 2. The present invention has no permanent magnets on the outer stator and the outer rotor, so the irreversible demagnetization of the permanent magnet caused by the weak magnetic speed regulation of the external speed regulating motor can be avoided; for the internal motor, the excitation device only works in the magnetization mode and does not participate in the weak magnetic speed regulation. Under high-speed conditions, the speed regulation is completed by the external motor, and the internal motor always works near the rated point, completing the increase in torque output while avoiding the risk of irreversible demagnetization of the permanent magnet caused by the weak magnetic speed regulation of the internal motor; therefore, the present invention improves the working stability of the permanent magnet and the reliability of the motor.

[0017] 3. In the present invention, the inner motor and the outer motor can operate in different working modes such as separate drive or joint drive. When one motor fails, the other motor can be operated separately for a short time. Therefore, the motors in the present invention have a certain fault tolerance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a cross-sectional view of a radial magnetic field compound motor with an inner motor of 3-phase stator 12 slots / rotor 22 poles and an outer motor of 3-phase stator 12 slots / rotor 8 poles.

[0019] Figure 2 It is a cross-sectional view of the radial magnetic field composite motor of the present invention.

[0020] In the figure: 1 outer stator, 2 outer rotor, 3 inner rotor, 4 inner stator, 5 rotating shaft, 6 outer casing, 7 rotor bracket, 8 first bearing, 9 second bearing, 10 third bearing, 1-1 outer winding, 2-3 magnetic isolation ring, 4-1 inner winding, 4-2 excitation device. DETAILED DESCRIPTION

[0021] The present invention is described in detail below in conjunction with the accompanying drawings.

[0022] This embodiment provides a radial magnetic field compound motor, such as Figure 1 , mainly including a rotating shaft 5, a first bearing 8 surrounding the rotating shaft 5, an inner stator 4 surrounding the first bearing 8, an inner rotor 3 surrounding the inner stator 4, a magnetic isolation ring 2-3 surrounding the inner rotor 3, an outer rotor 2 surrounding the magnetic isolation ring 2-3, and an outer stator 1 surrounding the outer rotor 2. An air gap is provided between the outer stator 1 and the outer rotor 2, an air gap is provided between the inner stator 4 and the inner rotor 3, and salient pole teeth without windings are provided on the side of the outer rotor 2 facing the outer stator 1 and the side of the inner rotor 3 facing the inner stator 4. Salient pole teeth and outer windings 1-1 wound on the salient pole teeth are provided on the inner side of the outer stator 1, and salient pole teeth and inner windings 4-1 wound on the salient pole teeth are provided on the outer side of the inner stator 4. The salient pole teeth of the inner stator 4 are provided with an excitation device 4-2, and the magnetization direction of the excitation device 4-2 is alternating magnetization along the circumference of the inner stator 4. The excitation device 4-2 in this embodiment uses a permanent magnet, and of course a hybrid excitation device can also be used. It should be pointed out that in the present embodiment, the directions of the salient poles of the stator and the rotor are all in the radial direction.

[0023] like Figure 1 This embodiment takes a radial magnetic field composite motor with an inner motor of 3-phase stator 12 slots / rotor 22 poles and an outer motor of 3-phase stator 12 slots / rotor 8 poles as an example to specifically illustrate the technical solution of the present invention.

[0024] The outer stator 1 has 12 salient pole teeth protruding radially inwardly from the yoke, on which there are no permanent magnets. The 12 salient pole teeth are covered with 12 armature winding coils, and every 4 coils are connected in series to form a concentrated winding, thus forming a three-phase outer armature winding, i.e., the outer winding 1-1. The number of salient pole teeth of the outer rotor 2 is 8. The outer stator 1, the outer rotor 2 and the outer winding 1-1 thereon form a three-phase 12 / 8-pole switched reluctance outer motor; the inner stator 4 has 12 "V"-shaped magnetic conductive cores and 12 rectangular permanent magnets distributed along the circumference. The magnets 4-2 are placed alternately adjacent to each other to form 12 inner stator poles. Each inner stator pole is composed of a permanent magnet and two adjacent inner stator teeth of a "V"-shaped conductive core on both sides of its circumference. The "V"-shaped conductive core opens toward the inner rotor 3. The inner rotor 3 has 22 salient pole teeth. There are 12 winding coils wound on the 12 inner stator poles of the inner stator 4, where every 4 winding coils form a phase concentrated winding, thus forming an inner three-phase concentrated armature winding, i.e., the inner winding 4-1. The inner rotor 3, the inner stator 4, the permanent magnets 4-2 thereon, and the inner winding 4-1 form a three-phase 12 / 22-pole permanent magnet flux switching inner motor structure.

[0025] See Figure 2 The inner stator 4 is rotatably connected to the rotating shaft 5 through the first bearing 8, the outer rotor 2 is fixedly connected to the inner rotor 3 through the magnetic isolation ring 2-3, the outer rotor 2, the magnetic isolation ring 2-3, and the inner rotor 3 constitute the motor rotor, and are fixedly connected to the rotating shaft 5 through the rotor bracket 7, the outer diameter of the outer stator 1 is fixed on the outer casing 6, and is rotatably connected to the rotating shaft 5 through the second bearing 9 and the third bearing 10.

[0026] The radial magnetic field composite motor in this embodiment is divided into two parts based on the functions that can be realized: one part is a speed-regulating outer motor, which adopts a three-phase 12 / 8-pole switched reluctance motor structure, has a simple structure, is suitable for high-speed operation, is easy to cool, and can allow a higher temperature rise due to the absence of permanent magnets; the other part is a torque-regulating inner motor, which adopts a three-phase 12 / 22-pole permanent magnet flux switching motor structure, has a simple rotor structure, and has high torque density and high efficiency. Since the outer rotor 2 and the inner rotor 3 are both fixedly connected to the rotating shaft 5, the inner motor and the outer motor have the same rotor speed, the outer stator 1 is fixedly connected to the housing 6 on the base, and has no speed, and the inner stator 4 can rotate at a certain speed according to the working conditions due to the presence of the first bearing 8. In the present invention, the outer motor mainly realizes the speed regulation of the motor according to the load speed requirement, so that the rotating shaft 5 rotates at the target speed and outputs a certain torque at the same time; the role of the inner motor is to provide driving torque or braking torque according to the load requirements to make up for the lack of output torque of the outer motor. In specific operation, the inner stator 4 can rotate in the same direction with the inner rotor 3 at a differential speed, so that the inner motor always works near the rated point with higher efficiency. The outer motor has no permanent magnets, so the permanent magnet weak magnetic field is not used to achieve speed regulation in the speed regulation operation of the motor, which helps to reduce the cost of the motor and improve the reliability of the operation of the outer motor. The inner motor adopts a permanent magnet motor structure with a magnetic concentration effect to achieve high torque density and high efficiency, and has a large torque regulation capability. Due to the effect of the first bearing 8, the inner motor can always work near the rated point under different working conditions, and whether it is running at low speed or high speed, the lack of output torque of the outer motor can be provided by the inner motor, thereby realizing the requirements of low-speed, high-torque and wide speed regulation range operation of the motor.

[0027] There is no electromagnetic coupling between the inner and outer motor systems of this radial magnetic field composite motor, and they can be independently controlled as two ordinary motors. The controllable parameters are much more than those of ordinary flux switching motors, which is very flexible. The inner and outer motors can operate in different working modes such as single-machine drive, dual-machine joint drive, and dual-machine power generation according to different working conditions. When both the inner and outer motors are used for power generation, they can output two sets of electric energy with different power, frequency, amplitude and voltage levels; the inner and outer motor systems can also be used for power generation and electric operation by one, to meet different application occasions and performance requirements.

[0028] The radial magnetic field composite motor integrates the permanent magnet flux switching outer motor and the switched reluctance inner motor in a radial magnetic field motor space, providing two power flow paths. Both the inner motor and the outer motor can adopt other motor structures, which greatly improves the flexibility of the system and expands the scope of application.

[0029] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A radial magnetic field compound motor, characterized in that: The invention comprises a rotating shaft (5), a first bearing (8) surrounding the rotating shaft (5), an inner stator (4) surrounding the first bearing (8), an inner rotor (3) surrounding the inner stator (4), a magnetic isolation ring (2-3) surrounding the inner rotor (3), an outer rotor (2) surrounding the magnetic isolation ring (2-3), and an outer stator (1) surrounding the outer rotor (2); air gaps are provided between the outer stator (1) and the outer rotor (2) and between the inner stator (4) and the inner rotor (3); the inner stator (4) is provided with an air gap through the first bearing (8); The outer rotor (2) is rotatably connected to the rotating shaft (5); the outer rotor (2) is fixedly connected to the inner rotor (3) via the magnetic isolation ring (2-3); the outer rotor (2), the magnetic isolation ring (2-3) and the inner rotor (3) constitute the motor rotor and are fixedly connected to the rotating shaft (5) via a rotor bracket (7); the outer stator (1) is fixed to the outer shell (6); the rotating shaft (5) is rotatably connected to the outer shell (6); neither the outer stator (1) nor the outer rotor (2) has a permanent magnet; and the inner stator (4) can rotate at a certain speed during operation.

2. The radial magnetic field compound motor according to claim 1, characterized in that: The opposite sides of the outer stator (1) and the outer rotor (2) and the opposite sides of the inner stator (4) and the inner rotor (3) are both provided with salient pole teeth, and the salient pole teeth of the outer stator (1) are provided with outer windings (1-1), and the salient pole teeth of the inner stator (4) are provided with inner windings (4-1) and excitation devices (4-2).

3. The radial magnetic field compound motor according to claim 2, characterized in that: The magnetizing direction of the excitation device (4-2) is alternating magnetization along the circumferential tangent of the inner stator (4).

4. The radial magnetic field compound motor according to claim 2, characterized in that: The excitation device (4-2) is a permanent magnet or a hybrid excitation device.

5. The radial magnetic field compound motor according to claim 2, characterized in that: The number of salient pole teeth of the outer stator (1) is P so , the outer winding (1-1) consists of symmetrically distributed P so The outer winding (1-1) is composed of a coil sleeved on the salient pole teeth of the outer stator (1). m Phase concentrated winding, meet P so =2 k 1 m , where k 1 positive integer; The number of salient pole teeth of the outer rotor (2) is P ro ,satisfy P ro = P so ±2N1, where N1 is a positive integer.

6. The radial magnetic field compound motor according to claim 5, characterized in that: The number of salient pole teeth of the inner stator (4) is P si , the inner winding (4-1) consists of symmetrically distributed P si The inner winding (4-1) is composed of a coil sleeved on the salient pole teeth of the inner stator. n Phase concentrated winding, meet P si =2 k 2 n , where k 2 positive integer; The number of teeth of the salient pole teeth of the inner rotor (3) is P ri ,satisfy P ri = P si ±2N2, where N2 is a positive integer.

7. The radial magnetic field compound motor according to any one of claims 1 to 6, characterized in that: The salient pole teeth on the outer stator (1), the outer rotor (2), the inner stator (4) and the inner rotor (3) are all oriented in the radial direction.

8. The radial magnetic field compound motor according to claim 2, characterized in that: The inner winding (4-1) and the outer winding (1-1) are both multi-phase concentrated armature windings.

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