Asynchronous excitation three-stage generator without rotating rectifier

Abstract

The embodiment of the invention discloses an asynchronous excitation three-stage generator without a rotating rectifier, and relates to the technical field of aviation three-stage starting generators, in a starting stage, a main motor is connected to a three-phase alternating current voltage source and can be directly started as an induction motor; in the power generation stage, the permanent magnet machine is connected to a three-phase alternating-current voltage source, an exciter stator is connected to the GCU to obtain an alternating-current excitation power source output by the permanent magnet machine, induced current is generated in the cage type rotor, a rotating rotor magnetic field cuts a main motor stator winding, and therefore induced current power generation is generated. Structural optimization of a traditional three-stage synchronous motor is achieved, dependence of a traditional three-stage motor brushless excitation system on a rotating rectifier is eliminated, and limitation of the rotating speed of the motor due to the fault problem of the rotating rectifier is broken through. While brushless excitation is ensured, the upper limit of the rotating speed of the three-stage motor is improved, and the purpose of further improving the power level of the aero-generator is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of aviation three-stage starter generators, and in particular to an asynchronous excitation three-stage generator without a rotating rectifier. Background Art

[0002] With the continuous development of green aviation, airborne secondary energy is gradually unified into electric energy. More electric aircraft have higher and higher requirements for the power level of the power system, and high-power generators have become one of the important components. The three-stage synchronous motor is widely used due to its mature technology and high reliability. As an important component of the three-stage motor, the rotating rectifier replaces the traditional brushes and slip rings, and solves the problems of poor contact and heating caused by the brush excitation system. However, when the generator is working normally, the rotating rectifier rotates with the shaft, and the working environment is very harsh, so it is very easy to fail. Especially today when the speed of aircraft generators is getting higher and higher, the rotating rectifier is prone to open circuit and short circuit failures at high speed, which not only affects the output power quality, but also directly shortens the life of the motor. On the other hand, the rotating rectifier uses mechanical contact for rectification, which has problems of friction and wear, which will increase the overall mechanical load and energy loss. After long-term use, the rectifier needs to be replaced and repaired, which increases the maintenance cost.

[0003] Therefore, the existence of the rotating rectifier limits the increase in the generator speed, and to a certain extent limits the further increase in the power level of the aviation three-stage motor. How to optimize the three-stage motor structure is of certain practical significance for the brushless excitation system to get rid of its dependence on the rotating rectifier, and has become a topic that needs to be studied. Summary of the invention

[0004] The embodiment of the present invention provides an asynchronous excitation three-level generator structure without a rotating rectifier, which can free a brushless excitation system from dependence on a traditional rotating rectifier.

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

[0006] An asynchronous excitation three-stage generator without a rotating rectifier comprises: 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 a rotating rectifier passes through the squirrel cage rotor (3);

[0007] The permanent magnet exciter (1) is used to provide a three-phase AC excitation current for an exciter stator (2) during a power generation stage, wherein the permanent magnet exciter (1) comprises 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-mounted structure and is adhered to the permanent magnet rotor core (13);

[0008] The exciter stator (2) comprises an exciter stator core (21) and an exciter armature winding (22), wherein the armature winding (22) is wound on the stator core (21);

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

[0010] The asynchronous excitation three-stage generator structure without rotating rectifier provided by the embodiment of the present invention has the following advantages: in the starting stage, the main motor is connected to the three-phase AC voltage source, and can be directly started as an induction motor; in the power generation stage, the permanent magnet machine is connected to the three-phase AC voltage source, and the stator of the excitation machine is connected to the GCU (generator control unit) to obtain the AC excitation power output by the permanent magnet machine, and an induced current is generated in the cage rotor, and the rotating rotor magnetic field cuts the stator winding of the main motor, thereby generating induced current to generate electricity. The structure of the traditional three-stage synchronous motor is optimized, the dependence of the traditional three-stage motor brushless excitation system on the rotating rectifier is eliminated, and the limitation on the motor speed due to the failure of the rotating rectifier is broken through. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

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

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

[0015] Figure 4 1 is a schematic diagram of the stator structure of an exciter according to an embodiment of the present invention;

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

[0017] Figure 6 2 is a schematic diagram of a squirrel cage rotor bar structure according to an embodiment of the present invention;

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

[0019] Figure 8 1 is a schematic diagram of the stator structure of a main motor according to an embodiment of the present invention;

[0020] Fig. 9 It is a schematic diagram of the principle of an asynchronous excitation three-stage generator without a rotating rectifier provided by an embodiment of the present invention working in the power generation stage;

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

[0022] Fig.11 The waveform of no-load power generation of an asynchronous excitation three-stage generator without a rotating rectifier provided by an embodiment of the present invention at a rated speed of 11640 rpm;

[0023] Fig.12 The invention provides an asynchronous excitation three-stage generator without a rotating rectifier, which generates power with a 1-fold resistive load at a rated speed of 11640 rpm.

[0024] The numbers in the accompanying drawings are respectively: permanent magnet exciter ~1, exciter stator ~2, squirrel cage rotor ~3, main motor stator ~4, permanent magnet machine stator core ~11, permanent magnet machine stator armature winding ~12, permanent magnet machine rotor core ~13, permanent magnet ~14, exciter stator core ~21, exciter stator armature winding ~22, squirrel cage rotor bars ~31, squirrel cage rotor core ~32, main motor stator core ~41, main motor stator armature winding ~42. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments of the present invention will be described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention. It can be understood by those skilled in the art that, unless specifically stated, the singular forms "one", "one", "said" and "the" used herein may also include plural forms. It should be further understood that the term "including" used in the specification of the present invention refers to the presence of the 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 their groups. It should be understood that when we say that an element is "connected" or "coupled" to another element, it can be directly connected or coupled to other elements, or there may also be intermediate elements. In addition, the "connection" or "coupling" used here may include wireless connection or coupling. The term "and / or" used herein includes any unit and all combinations of one or more associated listed items. It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as generally understood by those of ordinary skill in the art to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0026] The embodiment of the present invention provides an asynchronous excitation three-level generator without a rotating rectifier, such as Figure 1 As shown, it comprises: 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 a 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), wherein the armature winding (42) is wound on the stator core (41). The permanent magnet exciter (1) is used to provide a three-phase AC excitation current for the exciter stator (2) during the power generation stage, wherein, Figure 2 , 3As shown, the permanent magnet exciter (1) comprises a permanent magnet machine stator core (11), a permanent magnet machine stator armature winding (12), a permanent magnet machine rotor core (13) and a permanent magnet (14); the permanent magnet machine stator armature winding (12) is wound on the stator core (11), and the permanent magnet (14) is a surface-mounted structure and is attached to the permanent magnet machine rotor core (13); Figure 4 As shown, the exciter stator (2) comprises an exciter stator core (21) and an exciter armature winding (22), wherein the armature winding (22) is wound on the stator core (21);

[0028] In this embodiment, Figure 5 , 6 As shown in , 7, the squirrel cage rotor (3) comprises a squirrel cage rotor bar (31) and a squirrel cage rotor core (32), and two annular squirrel cage rotor bars (31) are respectively installed at two 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. The permanent magnet exciter (1) provides a three-phase AC power supply for the exciter stator armature winding (21) during the power generation stage, thus meeting the self-excitation requirements of the aircraft generator. The material used to manufacture the permanent magnet stator core (11) and the rotor core (13) is 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 20 mm. 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, the axial length is 100 mm, and the material of the stator core of the main motor stator (4) is 1j22 soft magnetic alloy.

[0030] like Figure 5 , 6 7. The squirrel cage rotor (3) adopts a 36-slot structure, and the angle of each skewed slot is 7.5 degrees, wherein the skewed slot angle is the angle of inclination of each slot, and is usually 0.9-1.2 stator tooth pitches to effectively suppress electromagnetic vibration and noise. In this example, the influence of the skewed slot on the suppression of tooth harmonics is also considered. After further optimization, the skewed slot of 7.5 degrees is selected. The squirrel cage rotor core (32) is made of 1j22 soft magnetic alloy, and the squirrel cage rotor bar (31) is made of copper. The rotor axial length of the squirrel cage rotor bar (31) is 180 mm.

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

[0032] Preferably, in 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) outputs a three-phase AC power with a frequency of 800 Hz through the GCU and is input into the stator armature winding (21) of the exciter. Based on the principle of electromagnetic induction, the three-phase AC power with the same frequency of 800 Hz can be generated in the stator armature winding of the main motor through the current transmission of the squirrel cage rotor.

[0033] When the asynchronous excitation three-stage generator without rotating rectifier is running in the starting stage, the working principle is as follows: Fig.10 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. ， ; in φ1 ， Under the action of ， The induced current generates a magnetic field φ2 of the squirrel cage rotor (3) ， , where, due to the different frequencies of the stator current and rotor current of the main motor, φ1, and φ2, have relative motion, and the two magnetic fields interact with each other 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, corresponding to the speed) (cannot reach the synchronous speed), the induced current generated in the rotor bars gradually decreases, and the electromagnetic torque gradually decreases accordingly, and the motor smoothly transitions to a stable operating state and completes the start-up.

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

[0035] The asynchronous excitation three-stage generator structure without rotating rectifier provided in this embodiment combines the principles of traditional three-stage synchronous motor and induction motor, gets rid of the dependence of brushless excitation system on rotating rectifier, on the one hand, retains the characteristics of self-excitation power generation of traditional three-stage motor, and improves the upper limit of speed, meeting the demand of aviation power supply system for high power level of generator. On the other hand, the present invention combines the working principle of induction motor, has the characteristics of simple structure and convenient starting, and can be applied to various loads, frequent starting or braking occasions.

[0036] The motor power generation principle in this embodiment is solved by using the principle of the transformer. Therefore, under other unchanged conditions, the output power can be changed 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 changing the axial length of the main motor stator or the number of winding turns. The motor starting principle is the same as that of the induction motor, which has the characteristics of easy starting and is suitable for various load conditions. The topological structure gets rid of the dependence of the brushless excitation system on the rotating rectifier and can break through the speed limit of the traditional three-stage motor.

[0037] In practical applications, finite element simulation can be used to verify the solution. In Ansys Maxwell software, a finite element simulation model of the exciter and the main motor is built, and the squirrel cage rotor current is used as an intermediate quantity for simulation verification. The solution of this embodiment is simulated and verified for power generation at no-load and 1 times resistive load 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, the armature winding of the main motor outputs the rated voltage, and the no-load output voltage waveforms are obtained as follows: Fig.11 , the output voltage waveform under 1 times resistive load is as follows Fig.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 general, the asynchronous excitation three-stage generator structure without rotating rectifier provided in this embodiment combines the principles of traditional three-stage synchronous motor and induction motor, gets rid of the dependence of brushless excitation system on rotating rectifier, on the one hand, retains the characteristics of self-excitation power generation of traditional three-stage motor, and improves the upper limit of speed, meeting the demand of aviation power supply system for high power level of generator. On the other hand, the present invention combines the working principle of induction motor, has the characteristics of simple structure and convenient starting, and can be applied to various loads, frequent starting or braking occasions. The main advantages are: 1. It gets rid of the dependence of traditional brushless excitation system of three-stage motor on rotating rectifier, on the one hand, reduces the possibility of motor failure and improves reliability, on the other hand, breaks through the limitation of speed of traditional three-stage motor structure, and improves the upper limit of power level of aviation three-stage motor. 2. When used as an aviation starter generator, the starting principle is similar to that of induction motor, and can be applied to various loads, frequent starting or braking occasions.

[0039] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. The above is only a specific implementation method of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. An asynchronous excitation three-level generator without a rotating rectifier, characterized in that: include: 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 excitation three-stage generator without a rotating rectifier passes through the squirrel cage rotor (3); The permanent magnet exciter (1) is used to provide a three-phase AC excitation current for an exciter stator (2) during a power generation stage, wherein the permanent magnet exciter (1) comprises 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-mounted structure and is adhered to the permanent magnet rotor core (13); The exciter stator (2) comprises an exciter stator core (21) and an exciter armature winding (22), wherein the armature winding (22) is wound on the stator core (21); The exciter stator (2) and the main motor stator (4) share a squirrel cage rotor (3).

2. The asynchronous excitation three-level generator without rotating rectifier according to claim 1, characterized in that: The squirrel cage rotor (3) comprises a squirrel cage rotor bar (31) and a squirrel cage rotor iron core (32), wherein two annular squirrel cage rotor bars (31) are respectively mounted at two ends of the cylindrical squirrel cage rotor iron core (32).

3. The asynchronous excitation three-level 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. The permanent magnet exciter (1) provides a three-phase AC power supply to the stator armature winding (21) of the exciter in the power generation stage. The material used to manufacture the stator core (11) and the rotor core (13) of the permanent magnet machine is DW310-35 silicon steel, and the material used to manufacture the permanent magnet (14) is SmCo28 permanent magnet material.

4. The asynchronous excitation three-level generator without rotating rectifier according to claim 3, characterized in that: The exciter stator (2) has a 4-pole 48-slot structure and an axial length of 20 mm; The material of the stator core of the exciter stator (2) is 1j22 soft magnetic alloy.

5. The asynchronous excitation three-level generator without rotating rectifier according to claim 1, characterized in that: The main motor stator (4) adopts a 4-pole 48-slot structure, and the axial length is 100 mm. The material of the stator core of the main motor stator (4) is 1j22 soft magnetic alloy.

6. The asynchronous excitation three-level generator without rotating rectifier according to claim 1, characterized in that: The squirrel cage rotor (3) adopts a 36-slot structure, and the angle of each slot is 7.5 degrees; The squirrel cage rotor core (32) is made of 1j22 soft magnetic alloy, the squirrel cage rotor bars (31) are made of copper, and the rotor axial length of the squirrel cage rotor bars (31) is 180 mm.

7. The asynchronous excitation three-level generator without rotating rectifier according to any one of claims 1 to 6, characterized in that: In the power generation stage, the motor shaft of the asynchronous excitation three-stage generator without a rotating rectifier rotates at a speed 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 outputs a three-phase AC power with a frequency of f1 through a generator control unit (GCU), and the three-phase AC power is continuously input into the exciter armature winding (22), and the exciter armature winding (22) rotates at a synchronous speed n1 and generates a magnetic field φ1; Rat cage The motor shaft of the rotor (3) rotates at a speed n, and the squirrel cage rotor (3) forms a relative motion with the rotating magnetic field φ1, thereby generating an alternating current with a frequency f2 in the squirrel cage rotor bars (31); The alternating current induced by the squirrel cage rotor (3) forms a magnetic field φ2 of the squirrel cage rotor (3) which rotates at a speed n2, thereby satisfying n1=n+n2. The magnetic field φ2 of the squirrel cage rotor (3) cuts the stator armature winding (42) of the main motor, and the stator armature winding (42) of the motor induces three-phase alternating current with a frequency of f1 and outputs it, thereby completing the power generation work.

8. The asynchronous excitation three-level generator without rotating rectifier according to claim 7, characterized in that: In the power generation stage, the motor shaft is driven to rotate 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 through the GCU and input into the stator armature winding (21) of the exciter.

9. The asynchronous excitation three-level generator without rotating rectifier according to claim 7, characterized in that: During the starting phase, the main motor stator armature winding (42) is connected to 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. ， ; in φ1 ， Under the action of ， The induced current generates a magnetic field φ2 of the squirrel cage rotor (3) ， , due to φ1 ， and φ2 ， There is relative motion so that the squirrel cage rotor (3) starts to rotate.

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