An asynchronous three-stage generator without rotating rectifier

Abstract

This invention discloses an asynchronous three-stage generator without a rotating rectifier, relating to the field of aviation three-stage starter generator technology. During the starting phase, the main motor is connected to a three-phase AC voltage source and can be directly started as an induction motor. During the power generation phase, the permanent magnet generator is connected to the three-phase AC voltage source, and the exciter stator is connected to the GCU to obtain the AC excitation power output from the permanent magnet generator. Induced current is generated in the squirrel-cage rotor, and the rotating rotor magnetic field cuts the stator windings of the main motor, thereby generating electricity. This invention achieves structural optimization of the traditional three-stage synchronous motor, eliminates the dependence of the traditional three-stage motor brushless excitation system on the rotating rectifier, and overcomes the limitation on motor speed caused by rotating rectifier failure. While ensuring brushless excitation, this invention increases the upper speed limit of the three-stage motor, achieving the goal of further improving the power rating of aviation generators.

Description

Technical Field

[0001] This invention relates to the field of aviation three-stage starter generator technology, and more particularly to an asynchronous excitation three-stage generator without a rotating rectifier. Background Technology

[0002] With the continued development of green aviation, airborne secondary energy is gradually shifting towards electricity. More-electric aircraft are placing increasingly higher demands on the power rating of their electrical systems, making high-power generators a crucial component. Three-stage synchronous motors are widely used due to their mature technology and high reliability. Rotating rectifiers, as an important part of three-stage motors, replace traditional brushes and slip rings, solving problems such as poor contact and overheating associated with brushed excitation systems. However, during normal generator operation, the rotating rectifier rotates along with the shaft, operating in a harsh environment and thus prone to failure. Especially with the ever-increasing speeds of aircraft generators, rotating rectifiers are susceptible to open-circuit and short-circuit faults under high-speed rotation, affecting not only the quality of output power but also significantly shortening the motor's lifespan. Furthermore, rotating rectifiers use mechanical contact for rectification, leading to friction and wear, increasing the overall mechanical load and energy loss. With prolonged use, the rectifier requires replacement and maintenance, increasing maintenance costs.

[0003] Therefore, the presence of a rotating rectifier limits the increase in generator speed, which to some extent restricts the further improvement of the power rating of three-stage aerospace motors. Optimizing the structure of the three-stage motor is of practical significance for brushless excitation systems to break free from their dependence on rotating rectifiers, and has become a research topic that needs to be addressed. Summary of the Invention

[0004] Embodiments of the present invention provide an asynchronous excitation three-stage generator structure without a rotating rectifier, which enables the brushless excitation system to break free from the dependence on traditional rotating rectifiers.

[0005] To achieve the above objectives, the embodiments of the present invention adopt the following technical solutions:

[0006] An asynchronous three-stage generator without rotating rectifier includes: a permanent magnet exciter (1), an exciter stator (2), a squirrel-cage rotor (3) and a main motor stator (4), wherein the motor shaft of the asynchronous three-stage generator without rotating rectifier passes through the squirrel-cage rotor (3).

[0007] The permanent magnet exciter (1) is used to provide three-phase AC excitation current to the exciter stator (2) during the power generation stage. The permanent magnet exciter (1) includes a permanent magnet stator core (11), a permanent magnet stator armature winding (12), a permanent magnet rotor core (13), and a permanent magnet (14). The permanent magnet stator armature winding (12) is wound on the stator core (11), and the permanent magnet (14) is a surface-mount structure and is attached to the permanent magnet rotor core (13).

[0008] The exciter stator (2) includes an exciter stator core (21) and an exciter armature winding (22), with the armature winding (22) wound around the stator core (21);

[0009] The exciter stator (2) and the main motor stator (4) share a single squirrel-cage rotor (3).

[0010] The asynchronous three-stage generator structure without rotating rectifier provided in this invention allows the main motor to be directly started as an induction motor during the starting phase, connected to a three-phase AC voltage source. During the power generation phase, the permanent magnet generator is connected to the three-phase AC voltage source, and the exciter stator is connected to the GCU (generator control unit) to obtain the AC excitation power output from the permanent magnet generator. Induction current is generated in the squirrel-cage rotor, and the rotating rotor magnetic field cuts the stator windings of the main motor, thereby generating electricity. This structure optimizes the traditional three-stage synchronous motor structure, eliminates the dependence on rotating rectifiers in traditional three-stage brushless excitation systems, and overcomes the speed limitations imposed by rotating rectifier failures. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a simplified topology diagram of an asynchronous excitation three-stage generator without a rotating rectifier provided in an embodiment of the present invention;

[0013] Figure 2 This is a schematic diagram of the permanent magnet exciter structure according to an embodiment of the present invention;

[0014] Figure 3 This is a front view of the permanent magnet exciter according to an embodiment of the present invention;

[0015] Figure 4 This is a schematic diagram of the exciter stator structure according to an embodiment of the present invention;

[0016] Figure 5 This is a schematic diagram of the squirrel cage rotor structure according to an embodiment of the present invention;

[0017] Figure 6 This is a schematic diagram of the rod structure of the squirrel cage rotor according to an embodiment of the present invention;

[0018] Figure 7 This is a schematic diagram of the squirrel cage rotor core structure according to an embodiment of the present invention;

[0019] Figure 8 This is a schematic diagram of the main motor stator structure according to an embodiment of the present invention;

[0020] Figure 9 This is a schematic diagram illustrating the principle of an asynchronous three-stage generator without a rotating rectifier operating in the power generation stage, as provided in an embodiment of the present invention.

[0021] Figure 10 This is a schematic diagram of the working principle of an asynchronous excitation three-stage generator without rotating rectifier in the starting stage, provided by an embodiment of the present invention;

[0022] Figure 11 This is the no-load power generation waveform of an asynchronous three-stage generator without rotating rectifier provided in an embodiment of the present invention at a rated speed of 11640 rpm;

[0023] Figure 12 This is a waveform of an asynchronous three-stage generator without a rotating rectifier generating power at a rated speed of 11640 rpm with a resistive load, provided by an embodiment of the present invention.

[0024] The numbers in the attached diagram are as follows: Permanent magnet exciter ~1, exciter stator ~2, squirrel-cage rotor ~3, main motor stator ~4, permanent magnet exciter stator core ~11, permanent magnet exciter stator armature winding ~12, permanent magnet exciter rotor core ~13, permanent magnet ~14, exciter stator core ~21, exciter stator armature winding ~22, squirrel-cage rotor conductor bar ~31, squirrel-cage rotor core ~32, main motor stator core ~41, main motor stator armature winding ~42. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Embodiments of the present invention will be described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in the specification of the present invention means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, “connected” or “coupled” as used herein can include wireless connections or couplings. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the meaning consistent with their meaning in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0026] This invention provides an asynchronous three-stage generator without a rotating rectifier, such as... Figure 1 As shown, it includes: a permanent magnet exciter (1), an exciter stator (2), a squirrel-cage rotor (3) and a main motor stator (4). The motor shaft of the asynchronous excitation three-stage generator without rotating rectifier passes through the squirrel-cage rotor (3). The exciter stator (2) and the main motor stator (4) share a squirrel-cage rotor (3).

[0027] The structure of the main motor stator (4) is basically the same as that of the exciter stator (2), such as... Figure 8 As shown, the main motor stator (4) includes a main motor stator core (41) and a main motor stator armature winding (42), the armature winding (42) being wound around the stator core (41). The permanent magnet exciter (1) is used to provide three-phase AC excitation current to the exciter stator (2) during the power generation stage, wherein, as... Figure 2 , 3As shown, the permanent magnet exciter (1) includes a permanent magnet stator core (11), a permanent magnet stator armature winding (12), a permanent magnet rotor core (13), and a permanent magnet (14). The permanent magnet stator armature winding (12) is wound on the stator core (11), and the permanent magnet (14) is a surface-mount structure and is attached to the permanent magnet rotor core (13). Figure 4 As shown, the exciter stator (2) includes an exciter stator core (21) and an exciter armature winding (22), with the armature winding (22) wound around the stator core (21);

[0028] In this embodiment, Figure 5 , 6 As shown in Figures 7 and 8, the squirrel cage rotor (3) includes a squirrel cage rotor guide bar (31) and a squirrel cage rotor core (32). Two annular squirrel cage rotor guide bars (31) are respectively installed at both ends of the cylindrical squirrel cage rotor core (32).

[0029] In the preferred embodiment, the permanent magnet exciter (1) adopts a 3-pole, 18-slot surface-mounted permanent magnet motor. During the power generation phase, the permanent magnet exciter (1) provides three-phase AC power to the stator armature winding (21) of the exciter, meeting the self-excitation requirements of the aircraft generator. The materials used to manufacture the stator core (11) and rotor core (13) of the permanent magnet motor are DW310-35 silicon steel, and the material used to manufacture the permanent magnet (14) is SmCo28 permanent magnet material. The exciter stator (2) adopts a 4-pole, 48-slot structure with an axial length of 20mm. The material used to manufacture the stator core of the exciter stator (2) is 1j22 soft magnetic alloy. Figure 8 As shown, the main motor stator (4) adopts a 4-pole 48-slot structure with an axial length of 100mm. The stator core of the main motor stator (4) is made of 1J22 soft magnetic alloy.

[0030] like Figure 5 , 6 7. The squirrel-cage rotor (3) adopts a 36-slot structure, with each slot having an angle of 7.5 degrees. The angle of the slot is the angle of inclination of each slot, which is usually 0.9-1.2 times the stator tooth pitch to effectively suppress electromagnetic vibration and noise. In this example, the influence of the slot on suppressing tooth harmonics is also considered. After further optimization, a 7.5-degree slot is adopted. The material for manufacturing the squirrel-cage rotor core (32) is 1J22 soft magnetic alloy, and the material for manufacturing the squirrel-cage rotor guide bar (31) is copper. The axial length of the squirrel-cage rotor guide bar (31) is 180mm.

[0031] When the asynchronous three-stage generator without a rotating rectifier is operating in the power generation stage, its working principle is as follows: Figure 9As shown. The motor shaft of the asynchronous excitation three-stage generator without rotating rectifier rotates at a speed of n. An induced voltage is generated in the stator armature winding (12) of the permanent magnet exciter and a three-phase AC excitation current is output. The three-phase AC excitation current is output as a three-phase AC power with a frequency of f1 by the generator control unit (GCU). The three-phase AC power continues to be input into the armature winding (22) of the exciter. The armature winding (22) of the exciter rotates at a synchronous speed of b1 and generates a magnetic field φ1. The motor shaft of the squirrel-cage rotor (3) rotates at a speed of n. The squirrel-cage rotor (3) forms a relative motion with the rotating magnetic field φ1, thereby generating an AC induced current with a frequency of f2 in the conductor bars (31) of the squirrel-cage rotor. The condition n1>b is satisfied, which is the same as the working principle of the induction motor. There is a slip s. The alternating current induced by the squirrel-cage rotor (3) forms a magnetic field φ2 that rotates at a speed of n2. The whole rotates with the shaft at a speed of n, thus satisfying n1=n+n2. The magnetic field φ2 of the squirrel-cage rotor (3) cuts the stator armature winding (42) of the main motor. The stator armature winding (42) of the motor induces a three-phase alternating current with a frequency of f1 and outputs it, thus completing the power generation work.

[0032] Preferably, during the power generation stage, the motor shaft of the prime mover rotates at 11640 rpm, and the AC power output by the permanent magnet exciter (1) is converted into three-phase AC power with a frequency of 800 Hz via the GCU and input into the stator armature winding (21) of the exciter. Based on the principle of electromagnetic induction, through the current transmission of the squirrel-cage rotor, three-phase AC power with the same frequency of 800 Hz can be generated in the stator armature winding of the main motor.

[0033] When the asynchronous three-stage generator without rotating rectifier is operating in the starting phase, its working principle is as follows: Figure 10 As shown. The main motor stator armature winding (42) is connected at a frequency of f1. ， The three-phase alternating current generates a rotating magnetic field φ1 in the stator armature winding (42) of the main motor. ， ; at φ1 ， Under the action of the rod, the conductor bar (31) of the squirrel cage rotor generates a frequency of f2. ， The induced current generates a magnetic field φ2 in the squirrel-cage rotor (3). ， Because the stator current and rotor current of the main motor have different frequencies, φ1 and φ2 have relative motion. The two magnetic fields interact to generate electromagnetic force, causing the squirrel-cage rotor to start rotating and gradually accelerate. When the rotor speed gradually approaches the synchronous speed (f1, the corresponding speed) (but does not reach the synchronous speed), the induced current generated in the rotor bars gradually decreases, and the electromagnetic torque decreases accordingly. The motor smoothly transitions to a stable operating state, completing the start-up.

[0034] The starting principle of the asynchronous excitation three-stage generator without rotating rectifier in this embodiment can be referred to the starting principle of induction motor. Therefore, in addition to the direct starting method described above, the starting methods applicable to induction motors, such as reduced voltage starting and star-delta starting, are also applicable to this invention.

[0035] The asynchronous three-stage generator structure without rotating rectifier provided in this embodiment combines the principles of traditional three-stage synchronous motors and induction motors, eliminating the dependence of brushless excitation systems on rotating rectifiers. On the one hand, it retains the self-excited generation characteristics of traditional three-stage motors and increases the upper speed limit, meeting the high power requirements of aviation power systems. On the other hand, this invention, combined with the working principle of induction motors, features a simple structure and convenient starting, making it suitable for various loads and frequent starting or braking applications.

[0036] The motor power generation principle in this embodiment utilizes the principle of a transformer. Therefore, under the condition that other factors remain unchanged, the output power can be changed simply by adjusting the structural parameters of the main motor stator (4) and the exciter stator (2). For example, the output voltage can be changed by altering the axial length of the main motor stator or the number of winding turns. The motor's starting principle is the same as that of an induction motor, making it easy to start and suitable for various load conditions. This topology eliminates the dependence of brushless excitation systems on rotating rectifiers, thus overcoming the speed limitations of traditional three-stage motors.

[0037] In practical applications, finite element simulation can be used to verify the scheme. Finite element simulation models of the exciter and main motor are built in Ansys Maxwell software, and simulation verification is performed using the squirrel-cage rotor current as an intermediate quantity. In this embodiment, the scheme is tested under no-load and 1x resistive load conditions with a rated output voltage of 115V / 800Hz and a rated output power of 12kVA. At a rated speed of 11640rpm, by adjusting the input voltage of the exciter to make the armature winding of the main motor output the rated voltage, the no-load output voltage waveforms are obtained as follows: Figure 11 The output voltage waveform under a resistive load of 1 is as follows: Figure 12 When the asynchronous excitation three-stage generator without rotating rectifier is running in the starting stage, it can be directly started as an induction motor by connecting 115V / 400Hz three-phase AC power to the stator armature winding (42) of the main motor.

[0038] In summary, the asynchronous three-stage generator structure without rotating rectifier provided in this embodiment combines the principles of traditional three-stage synchronous motors and induction motors, eliminating the dependence of brushless excitation systems on rotating rectifiers. On the one hand, it retains the self-excited generation characteristics of traditional three-stage motors while increasing the upper speed limit, meeting the high power rating requirements of aviation power systems. On the other hand, this invention, combined with the working principle of induction motors, features a simple structure and convenient starting, making it suitable for various loads and frequent starting or braking applications. The main advantages are: 1. It eliminates the dependence of traditional brushless excitation systems on rotating rectifiers in three-stage motors, reducing the possibility of motor failure and improving reliability. It also overcomes the speed limitations of traditional three-stage motor structures, increasing the upper power rating limit of aviation three-stage motors. 2. When used as an aviation starter generator, the starting principle is similar to that of an induction motor, making it suitable for various loads and frequent starting or braking applications.

[0039] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on its differences from other embodiments. In particular, the device embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. The above descriptions are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A three-stage asynchronous generator without a rotating rectifier, characterized in that, include: The generator consists of a permanent magnet exciter (1), an exciter stator (2), a squirrel-cage rotor (3), and a main motor stator (4), with the motor shaft of the asynchronous excitation three-stage generator without a rotating rectifier passing through the squirrel-cage rotor (3). The permanent magnet exciter (1) is used to provide three-phase AC excitation current to the exciter stator (2) during the power generation stage. The permanent magnet exciter (1) includes a permanent magnet stator core (11), a permanent magnet stator armature winding (12), a permanent magnet rotor core (13), and a permanent magnet (14). The permanent magnet stator armature winding (12) is wound on the stator core (11), and the permanent magnet (14) is a surface-mount structure and is attached to the permanent magnet rotor core (13). The exciter stator (2) includes an exciter stator core (21) and an exciter armature winding (22), with the armature winding (22) wound around the stator core (21); The exciter stator (2) and the main motor stator (4) share a squirrel-cage rotor (3); The squirrel cage rotor (3) includes a squirrel cage rotor guide bar (31) and a squirrel cage rotor core (32). Two annular squirrel cage rotor guide bars (31) are respectively installed at both ends of the cylindrical squirrel cage rotor core (32). During the power generation phase, the motor shaft of the aforementioned asynchronous excitation three-stage generator without a rotating rectifier rotates at a speed of... The rotating permanent magnet exciter generates an induced voltage in the stator armature winding (12) and outputs a three-phase AC excitation current. The three-phase AC excitation current is output by the generator control unit (GCU) at a frequency of [missing value]. The three-phase alternating current continues to be input into the armature winding (22) of the exciter, and the armature winding (22) of the exciter moves at a synchronous speed. Rotate and generate a magnetic field ; The squirrel cage rotor (3) motor shaft rotates at a speed of Rotation, squirrel cage rotor (3) and rotating magnetic field Relative motion is generated, thus producing a frequency of [frequency value] in the guide bars (31) of the squirrel cage rotor. AC induced current; The alternating current induced in the squirrel-cage rotor (3) forms the magnetic field of the squirrel-cage rotor (3). With rotational speed Rotation, thus satisfying The magnetic field of the squirrel cage rotor (3) Cut the stator armature winding (42) of the main motor, and the stator armature winding (42) of the main motor induces a frequency of It generates and outputs three-phase alternating current, thereby completing the power generation work.

2. The asynchronous three-stage generator without rotating rectifier according to claim 1, characterized in that, The permanent magnet exciter (1) adopts a 3-pole 18-slot surface-mounted permanent magnet motor. During the power generation stage, the permanent magnet exciter (1) provides three-phase AC power to the stator armature winding (22) of the exciter. The materials used to manufacture the stator core (11) and rotor core (13) of the permanent magnet machine are DW310-35 silicon steel, and the materials used to manufacture the permanent magnet (14) are SmCo28 permanent magnet material.

3. The asynchronous three-stage generator without rotating rectifier according to claim 2, characterized in that, The exciter stator (2) adopts a 4-pole, 48-slot structure with an axial length of 20mm; The stator core of the exciter stator (2) is made of 1J22 soft magnetic alloy.

4. The asynchronous three-stage generator without rotating rectifier according to claim 1, characterized in that, The main motor stator (4) adopts a 4-pole 48-slot structure with an axial length of 100mm. The stator core material for manufacturing the main motor stator (4) is 1J22 soft magnetic alloy.

5. The asynchronous three-stage generator without rotating rectifier according to claim 1, characterized in that, The squirrel cage rotor (3) adopts a 36-slot structure, with each slot having an angle of 7.5 degrees; The material used to manufacture the squirrel cage rotor core (32) is 1J22 soft magnetic alloy, and the material used to manufacture the squirrel cage rotor guide bar (31) is copper. The axial length of the squirrel cage rotor guide bar (31) is 180mm.

6. The asynchronous three-stage generator without rotating rectifier according to claim 1, characterized in that, During the power generation stage, the motor shaft of the prime mover rotates at 11640 rpm, and the AC power output by the permanent magnet exciter (1) is fed into the exciter stator armature winding (22) via the GCU output of three-phase AC power with a frequency of 800 Hz.

7. The asynchronous three-stage generator without rotating rectifier according to claim 6, characterized in that, During the startup phase, the frequency of the main motor stator armature winding (42) is... The three-phase alternating current generates a rotating magnetic field in the stator armature winding (42) of the main motor. ;exist Under the action of the rod, the frequency generated in the guide bar (31) of the squirrel cage rotor is . The induced current generates a magnetic field in the squirrel-cage rotor (3). ,because and The relative motion causes the rat cage rotor (3) to start rotating.

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