Permanent magnet auxiliary electro-magnetic salient pole synchronous motor

Abstract

The invention discloses a permanent magnet auxiliary type electro-magnetic salient pole synchronous motor, which comprises a stator and a rotor arranged in the stator, the rotor comprises a rotor core arranged in the stator, an air gap is arranged between the rotor core and the stator, excitation windings are arranged in the rotor core at equal intervals in the circumferential direction, and the excitation windings are arranged in the stator. The center of the rotor core is provided with a non-magnetic support part, the periphery of the non-magnetic support part is provided with a plurality of permanent magnets at equal intervals, the rotor core comprises a rotor magnetic pole and a rotor yoke part, the rotor yoke part is fixedly connected with the non-magnetic support part, and the excitation winding is wound on the rotor magnetic pole. The permanent magnets are arranged in the salient pole rotor, and the ampere turns of the excitation winding are reduced, so that the loss of the excitation winding is reduced, the problem of overhigh temperature rise of the rotor is solved, the efficiency and the power density of the motor are improved, the structural complexity of the rotor is reduced, and the reliability is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of motors, and in particular relates to a permanent magnet assisted electrically excited salient pole synchronous motor. Background Art

[0002] The electric excitation synchronous motor uses direct current to establish the excitation magnetic field through the excitation winding. The excitation magnetic field can be flexibly adjusted by adjusting the current, but the loss and heat of the excitation winding limit the efficiency and power density of the motor. The permanent magnet synchronous motor uses permanent magnets to provide the excitation magnetic field, has no excitation loss, simple rotor structure, low heat, high efficiency and power density, etc., but because the permanent magnet magnetic field cannot be adjusted, it is limited to large generators and other occasions with high reliability requirements.

[0003] There are two sources of magnetic potential in the hybrid excitation synchronous motor: permanent magnet magnetic potential and electric excitation magnetic potential. The use of permanent magnet excitation can effectively reduce rotor loss and improve motor efficiency. The use of electric excitation winding can flexibly adjust the air gap flux of the motor. Hybrid excitation synchronous motors can be divided into three types according to the relationship between permanent magnet magnetic potential and electric excitation magnetic potential: series type, parallel type, and parallel type. The electric excitation circuit of the series hybrid excitation synchronous motor passes through the permanent magnet, with large magnetic resistance and low excitation efficiency. In addition, there is a risk of demagnetization of the permanent magnet during weak magnetic operation. The parallel hybrid excitation synchronous motor is formed by two motors directly in parallel, with a simple structure. However, in order to reduce the leakage of the motor rotor, the axial air gap between the rotors is generally set larger, resulting in a serious reduction in torque density; a larger axial air gap will form two centers of mass on the shaft, especially during high-speed rotation, which is prone to axial runout and thus causes rotor sweeping. When the excitation current is zero, there is still a permanent magnetic field in the series and parallel hybrid excitation motors. If a stator short circuit fault occurs, there is a risk of stator burning. The magnetic flux generated by the excitation winding of the parallel hybrid excitation synchronous motor does not directly pass through the permanent magnet. The motor has a strong flux regulation capability and a low demagnetization risk. When the excitation current is zero, the permanent magnet flux can be short-circuited through the rotor core, making the air gap magnetic field very small. However, the existing parallel hybrid excitation motors have problems such as complex rotor structure and low reliability. Summary of the invention

[0004] The purpose of the present invention is to provide a permanent magnet assisted electrically excited salient pole synchronous motor to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the present invention provides the following solution: The present invention provides a permanent magnet assisted electrically excited salient pole synchronous motor, including a stator and a rotor disposed within the stator. The rotor includes a rotor core disposed within the stator, and there is an air gap between the rotor core and the stator. The rotor core is circumferentially and equally spaced with exciting windings, and a non-magnetic support member is provided at the center of the rotor core. A plurality of permanent magnets are circumferentially and equally spaced on the outer periphery of the non-magnetic support member. The rotor core includes rotor poles and a rotor yoke, and the rotor yoke is fixedly connected to the non-magnetic support member. The exciting windings are wound around the rotor poles.

[0006] Preferably, the permanent magnets are installed in the rotor yoke between two adjacent rotor poles.

[0007] Preferably, the magnetization direction of the permanent magnets is perpendicular to the radial direction of the rotor, and the magnetization directions of two adjacent permanent magnets are opposite.

[0008] Preferably, the stator includes a stator core and stator windings. A plurality of stator slots are equally spaced within the stator core, and the stator windings are located within the stator slots.

[0009] Preferably, the permanent magnets are uniformly installed in multiple pieces or combined into one piece and installed in the rotor yoke between two adjacent rotor poles.

[0010] Preferably, the exciting windings are excited by direct current to form N poles and S poles that are alternately distributed in the circumference.

[0011] The present invention discloses the following technical effects: By installing permanent magnets in the salient pole rotor, the ampere-turns of the exciting windings are reduced, thereby reducing the losses of the exciting windings, solving the problem of excessive rotor temperature rise, improving the motor efficiency and power density, and at the same time reducing the structural complexity of the rotor and improving the reliability.

[0012] The present invention uses permanent magnets to assist the exciting windings to jointly provide the magnetic flux per pole, combining the advantages of permanent magnet synchronous motors and electrically excited synchronous motors. With the assistance of permanent magnets, when the stator windings generate the same no-load voltage, the required exciting current is reduced, thereby reducing the copper loss of the rotor exciting windings, reducing the rotor temperature rise, and improving the motor efficiency. Further, the permanent magnet assisted electrically excited salient pole synchronous motor can increase the magnetic load, reduce the volume and weight of the motor, and improve the power density without increasing the rotor losses and temperature rise. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The drawings constituting a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application. In the drawings:

[0014] Figure 1 It is a schematic cross-sectional view of a conventional electrically excited salient-pole synchronous motor;

[0015] Figure 2 It is a schematic cross-sectional view of the permanent-magnet-assisted electrically excited salient-pole synchronous motor of the present invention;

[0016] Figure 3 It is a magnetic field line distribution diagram when the permanent-magnet-assisted electrically excited salient-pole synchronous motor of the present invention operates without load;

[0017] Figure 4 It is a schematic diagram showing the variation of the no-load induced voltage of the permanent-magnet-assisted electrically excited salient-pole synchronous motor of the present invention and the conventional electrically excited salient-pole synchronous motor with the exciting current;

[0018] Figure 5 It is a magnetic field line distribution diagram when the exciting current of the permanent-magnet-assisted electrically excited salient-pole synchronous motor of the present invention is zero.

[0019] In the figure: 1. Rotor core; 2. Air gap; 3. Exciting winding; 4. Non-magnetic support component; 5. Permanent magnet; 6. Rotor pole; 7. Rotor yoke; 8. Stator core; 9. Stator winding. Detailed implementation manners

[0020] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0021] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners.

[0022] Referring to Figures 2 - 5 As shown, this embodiment provides a permanent-magnet-assisted electrically excited salient-pole synchronous motor, including a stator and a rotor disposed inside the stator. The rotor includes a rotor core 1 disposed inside the stator. An air gap 2 is provided between the rotor core 1 and the stator. Exciting windings 3 are circumferentially and equally spaced inside the rotor core 1. A non-magnetic support component 4 is provided at the center of the rotor core 1. A plurality of permanent magnets 5 are circumferentially and equally spaced outside the non-magnetic support component 4. The rotor core 1 includes a rotor pole 6 and a rotor yoke 7. The rotor yoke 7 is fixedly connected to the non-magnetic support component 4. The exciting windings 3 are wound around the rotor poles 6.

[0023] By installing a permanent magnet 5 in the salient-pole rotor, the ampere-turns of the field winding 3 are reduced, thereby reducing the loss of the field winding 3, solving the problem of excessive rotor temperature rise, improving the motor efficiency and power density, while reducing the structural complexity of the rotor and improving the reliability.

[0024] The present invention uses the permanent magnet 5 to assist the field winding 3 to jointly provide the magnetic flux per pole, combining the advantages of a permanent magnet synchronous motor and an electrically excited synchronous motor. With the assistance of the permanent magnet 5, when the stator winding 9 generates the same no-load voltage, the required exciting current is reduced, thereby reducing the copper loss of the rotor field winding 3, reducing the rotor temperature rise, and improving the motor efficiency. Further, the permanent magnet assisted electrically excited salient-pole synchronous motor can increase the magnetic load without increasing the rotor loss and temperature rise, reduce the volume and weight of the motor, and improve the power density.

[0025] In a further optimized solution, the permanent magnet 5 is installed in the rotor yoke 7 between two adjacent rotor poles 6.

[0026] In a further optimized solution, the magnetization direction of the permanent magnet 5 is perpendicular to the radius direction of the rotor, and the magnetization directions of two adjacent permanent magnets 5 are opposite.

[0027] In a further optimized solution, the stator includes a stator core 8 and a stator winding 9. A plurality of stator slots are equally spaced in the stator core 8, and the stator winding 9 is located in the stator slots.

[0028] In a further optimized solution, the permanent magnet 5 is installed in the rotor yoke 7 between two adjacent rotor poles 6 in the form of multiple pieces evenly installed or combined into one piece. Such a setting can make full use of the internal space of the motor, reduce the volume, reduce the weight of the motor, and improve the reliability of the rotor structure.

[0029] In a further optimized solution, the field winding 3 is excited by passing a direct current, forming N poles and S poles alternately distributed in the circumference.

[0030] In a further optimized solution, the permanent magnet 5 and the adjacent field winding 3 are connected in parallel to provide the magnetic flux per pole; with such a design, when the exciting current of the field winding 3 is zero, the permanent magnetic field generated by the permanent magnet 5 is all short-circuited, which can reduce the effective value of the stator no-load voltage; according to needs, an appropriate reverse exciting current is applied to the field winding 3 to achieve rotor demagnetization, thereby preventing the stator winding 9 from being burned out after a short circuit.

[0031] The rotor can also be located outside the stator to form an outer-rotor structure motor. At this time, the supporting components outside the rotor core yoke are made of non-magnetic materials.

[0032] The permanent magnet assisted electrically excited salient pole synchronous motor of the present invention can be used as a generator and applied in grid-connected power generation fields such as hydropower generation, wind power generation, pumped storage, synchronous condensers, etc., as well as various independent power supply fields; it can also be used as a motor and applied to various speed regulation driving occasions.

[0033] Compared with the series hybrid excitation synchronous motor: in the parallel hybrid excitation synchronous motor, the electrical excitation circuit does not pass through the permanent magnet 5, with small reluctance, high excitation efficiency, and there is no demagnetization risk for the permanent magnet 5 during weak magnetic operation.

[0034] Compared with the juxtaposed hybrid excitation synchronous motor: the design of the structure of the parallel hybrid excitation synchronous motor can make full use of the internal space of the motor, reduce the volume, decrease the weight of the motor, and improve the reliability of the rotor structure.

[0035] Compared with the existing conventional electrically excited salient pole synchronous motor: when the stator winding 9 generates the same no-load voltage, the required excitation current is reduced, thereby reducing the copper loss of the rotor excitation winding 3, decreasing the rotor temperature rise, and improving the motor efficiency. When the excitation current of the excitation winding 3 is zero, the permanent magnetic field generated by the permanent magnet 5 is all short-circuited, which can reduce the effective value of the stator no-load voltage; as needed, an appropriate reverse excitation current is applied to the excitation winding 3 to achieve rotor demagnetization, thereby preventing the stator winding 9 from being burned out after a short circuit.

[0036] As Figure 3 shown, it is the magnetic force line distribution diagram of the permanent magnet assisted electrically excited salient pole synchronous motor during no-load operation. It can be clearly seen from the figure that the permanent magnet 5 and the adjacent excitation winding 3 are connected in parallel to provide the magnetic flux per pole, and the magnitude of the air-gap 2 magnetic field can be adjusted by adjusting the magnitude of the current in the excitation winding 3.

[0037] As Figure 1 shown, it is a schematic diagram of a conventional electrically excited salient pole synchronous motor. The rotor is arranged inside the stator; there is an air-gap 2 between the stator and the rotor; the rotor includes a rotor core 1, an excitation winding 3, and a support component; the rotor core 1 includes parts such as rotor poles 6 and a rotor yoke 7; the rotor yoke 7 is fixed on the support component; the excitation winding 3 is wound around the rotor poles 6, and the excitation winding 3 is excited by passing a direct current to form N poles and S poles that are alternately distributed in the circumference; the stator includes a stator core 8 and a stator winding 9. The inner side of the stator core 8 is evenly grooved, and the stator winding 9 is installed in the stator slots.

[0038] As Figure 4As shown in Table 1, they are respectively the schematic diagrams of the curves of different induced voltages and excitation currents of a conventional electrically excited salient-pole synchronous motor and a permanent-magnet assisted electrically excited salient-pole synchronous motor under no-load conditions, and the comparison table of the no-load voltages generated by the permanent-magnet assisted electrically excited salient-pole synchronous motor and the conventional electrically excited salient-pole synchronous motor at the same excitation current. Obviously, the excitation current required for the permanent-magnet assisted electrically excited salient-pole synchronous motor provided by the present invention is reduced when generating the same no-load voltage. Taking the no-load rated phase voltage of 4 kV as an example, the excitation current required for the conventional electrically excited salient-pole synchronous motor is 93.18 A, while the excitation current required for the permanent-magnet assisted electrically excited salient-pole synchronous motor can be reduced to 46.04 A, significantly reducing the rotor excitation copper loss, thereby reducing the rotor temperature rise and improving the motor efficiency.

[0039] Table 1 Comparison Table of No-Load Voltages Generated by Permanent-Magnet Assisted Electrically Excited Salient-Pole Synchronous Motor and Conventional Electrically Excited Salient-Pole Synchronous Motor at the Same Excitation Current

[0040]

[0041] As Figure 5 shown, when the current of the excitation winding 3 of the permanent-magnet assisted electrically excited salient-pole synchronous motor is zero, the permanent magnetic field generated by the permanent magnet 5 is completely short-circuited. At this time, the effective value of the stator no-load voltage is only 40.8 V, which is 1.02% of the rated value, significantly reducing the stator no-load voltage. According to the need, an appropriate reverse excitation current is applied to the excitation winding 3 to achieve rotor demagnetization.

[0042] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0043] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A permanent magnet assisted electrically excited salient pole synchronous motor, characterized in that: The invention comprises a stator and a rotor arranged in the stator, wherein the rotor comprises a rotor core (1) arranged in the stator, an air gap (2) is arranged between the rotor core (1) and the stator, excitation windings (3) are arranged at equal intervals in the inner circumferential direction of the rotor core (1), a non-magnetic support component (4) is arranged at the center of the rotor core (1), and a plurality of permanent magnets (5) are arranged at equal intervals in the outer circumferential direction of the non-magnetic support component (4), the rotor core (1) comprises rotor poles (6) and a rotor yoke (7), the rotor yoke (7) is fixedly connected to the non-magnetic support component (4), and the excitation windings (3) are wrapped around the rotor poles (6).

2. The permanent magnet assisted electrically excited salient pole synchronous motor according to claim 1, characterized in that: The permanent magnet (5) is installed in a rotor yoke (7) between two adjacent rotor poles (6).

3. The permanent magnet assisted electrically excited salient pole synchronous motor according to claim 1, characterized in that: The magnetizing direction of the permanent magnets (5) is perpendicular to the radial direction of the rotor, and the magnetizing directions of two adjacent permanent magnets (5) are opposite.

4. The permanent magnet assisted electrically excited salient pole synchronous motor according to claim 1, characterized in that: The stator comprises a stator core (8) and a stator winding (9); a plurality of stator slots are arranged at equal intervals in the stator core (8); and the stator winding (9) is located in the stator slots.

5. The permanent magnet assisted electrically excited salient pole synchronous motor according to claim 2, characterized in that: The permanent magnets (5) are multiple pieces evenly installed or combined into one piece and installed in the rotor yoke (7) between two adjacent rotor poles (6).

6. The permanent magnet assisted electrically excited salient pole synchronous motor according to claim 1, characterized in that: The field winding (3) is excited by a direct current, thereby forming N poles and S poles alternately distributed on the circumference.

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