Permanent magnet auxiliary ring winding electro-magnetic salient pole synchronous motor

Abstract

The invention relates to the technical field of motors, and discloses a permanent magnet auxiliary ring winding electro-magnetic salient pole synchronous motor, which comprises a stator core, a rotor core sleeved with the stator core, a ring excitation winding wound on the rotor core and a plurality of permanent magnets arranged on the rotor core, the rotor iron core is of an annular structure, the outer surface and the inner surface of the rotor iron core are respectively provided with a plurality of outer grooves and inner grooves in one-to-one correspondence in the circumferential direction, a rotor yoke part is formed between the outer grooves and the inner grooves, and the annular excitation winding is wound on the rotor yoke part through the outer grooves and the inner grooves; according to the invention, the number of ampere turns of the annular excitation winding can be reduced, so that the loss of the annular excitation winding is reduced, the problem that the temperature rise of the rotor is too high 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 relates to the technical field of motors, and particularly to a permanent magnet assisted toroidal winding electrically excited salient pole synchronous motor. Background Art

[0002] In an electrically excited synchronous motor, a DC current is passed through the excitation winding to establish an excitation magnetic field, and the excitation magnetic field can be flexibly adjusted by adjusting the magnitude of the current. However, the losses and heat generation of the excitation winding limit the performance of the motor, such as efficiency and power density. A permanent magnet synchronous motor uses permanent magnets to provide the excitation magnetic field, has no excitation loss, a simple rotor structure, small heat generation, and high efficiency and power density. However, due to the non-adjustable magnetic field of the permanent magnet, its application in occasions with high reliability requirements, such as large generators, is restricted.

[0003] There are two magnetic potential sources in a hybrid excitation synchronous motor: the permanent magnet magnetic potential and the electrically excited magnetic potential. Using permanent magnets for excitation can effectively reduce rotor losses and improve motor efficiency. Using an electrically excited winding can flexibly adjust the air-gap magnetic flux of the motor. Hybrid excitation synchronous motors can be divided into three types according to the relationship between the permanent magnet magnetic potential and the electrically excited magnetic potential: series type, parallel type, and juxtaposed type. However, existing hybrid excitation motors have problems such as complex rotor structures and low reliability. Summary of the Invention

[0004] The purpose of the present invention is to provide a permanent magnet assisted toroidal winding electrically excited salient pole synchronous motor, aiming to solve or improve at least one of the above technical problems.

[0005] To achieve the above purpose, the present invention provides the following solution: The present invention provides a permanent magnet assisted toroidal winding electrically excited salient pole synchronous motor, including a stator core, a rotor core sleeved on the stator core, a toroidal excitation winding wound on the rotor core, and a plurality of permanent magnets arranged on the rotor core;

[0006] The rotor core is of an annular structure, and a plurality of corresponding outer slots and inner slots are circumferentially formed on the outer surface and the inner surface of the rotor core respectively. A rotor yoke is formed between the outer slots and the inner slots, and the toroidal excitation winding is wound on the rotor yoke through the outer slots and the inner slots;

[0007] The permanent magnets are arranged at the openings of the inner slots.

[0008] Optionally, there is an air gap between the stator core and the rotor core.

[0009] Optionally, the magnetization direction of the permanent magnets is perpendicular to the radial direction of the rotor core.

[0010] Optionally, the magnetization directions of two adjacent permanent magnets are opposite.

[0011] Optionally, it further includes a support member for connecting with the rotor core.

[0012] Optionally, the stator core is coated on the outer ring of the rotor core.

[0013] Optionally, the rotor core is coated on the outer ring of the stator core.

[0014] Optionally, a plurality of grooves are circumferentially formed in the inner ring of the stator core, and a stator winding is wound between the plurality of grooves.

[0015] Optionally, the permanent magnet is composed of a plurality of equally spaced magnetic blocks.

[0016] Optionally, the permanent magnet is composed of a plurality of closely arranged magnetic blocks.

[0017] The present invention discloses the following technical effects:

[0018] By providing an outer groove and an inner groove on the rotor core, winding the annular excitation winding in the outer groove and the inner groove, and arranging a permanent magnet at the notch of the inner groove, the ampere-turns of the annular excitation winding can be reduced, thereby reducing the loss of the annular excitation winding, solving the problem of excessive rotor temperature rise, improving the efficiency and power density of the motor, and at the same time reducing the structural complexity of the rotor and improving the reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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:

[0020] Figure 1 is a cross-sectional schematic view of the present invention;

[0021] Figure 2 is a magnetic field line distribution diagram of the present invention during no-load operation;

[0022] Figure 3 is a schematic diagram of the no-load induced voltage of the present invention varying with the excitation current compared with that of a conventional electrically excited salient-pole synchronous motor;

[0023] Figure 4 is a magnetic field line distribution diagram of the present invention when the excitation current is zero.

[0024] In the figure: 1, stator core; 2, rotor core; 3, outer groove; 4, inner groove; 5, annular excitation winding; 6, permanent magnet; 7, air gap; 8, support member; 9, stator winding; 10, rotor yoke. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] In the electrical excitation circuit of a series hybrid excitation synchronous motor, the flux passes through a permanent magnet, resulting in a large magnetic resistance and low excitation efficiency. Moreover, during field weakening operation, there is a risk of demagnetization of the permanent magnet.

[0026] The parallel hybrid excitation synchronous motor is formed by directly paralleling two motors, with a simple structure. However, to reduce the leakage flux of the motor rotor, generally a relatively large axial air gap is set between the rotors, resulting in a serious reduction in torque density. The large axial air gap will form two centers of mass on the rotating shaft, especially during high-speed rotation, which is prone to axial runout and then cause rotor rubbing against the stator. When the excitation current of the series and parallel hybrid excitation motors is zero, there is still a permanent magnetic field. If a stator short-circuit fault occurs, there is a risk of stator burnout.

[0027] In the parallel hybrid excitation synchronous motor, the magnetic flux generated by the excitation winding does not directly pass through the permanent magnet. The motor has strong magnetic flux regulation ability and a relatively low risk of demagnetization. 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.

[0028] A permanent magnet refers to a magnet that can maintain its magnetism for a long time and is not easily demagnetized or magnetized. They are usually made of natural magnets (such as magnetite) or artificial materials (such as alnico alloys, neodymium iron boron, etc.). The polarity of a permanent magnet does not change, while the polarity of a soft magnet changes with the polarity of the applied magnetic field.

[0029] The air gap of the rotor in the motor plays a crucial role during motor operation, mainly reflected in the following aspects:

[0030] Ensuring mechanical rotation: The air gap is the actual physical distance that separates the stator and rotor in the motor, ensuring that the rotor can rotate freely within the stator cavity. Without this air gap, the rotor will not be able to rotate freely, thus affecting the normal operation of the motor.

[0031] Influencing motor performance and reliability: The size of the air gap directly affects the performance and reliability of the motor. A smaller air gap can reduce the leakage magnetic flux, enabling more magnetic flux to be used for actual work, thereby improving the motor efficiency. However, a smaller air gap also requires precision machining, increasing the manufacturing cost. A larger air gap will weaken the magnetic circuit, reducing the motor efficiency and requiring more excitation current.

[0032] Influencing motor temperature rise: The size of the air gap also affects the motor temperature rise. A larger air gap will increase the air-gap magnetic conductance harmonics, resulting in an increase in additional losses and then affecting the motor temperature rise. By adjusting the size of the air gap, the starting performance and temperature rise of the motor can be effectively controlled. For example, appropriately increasing the air gap between the stator and rotor can reduce the air-gap magnetic conductance harmonics, reduce additional losses, and thus reduce the motor temperature rise.

[0033] Electromagnetic connection: When the motor is running, after the stator winding is energized, a connection is generated between the rotor and the stator through electromagnetic induction, thereby realizing the conversion between electrical energy and mechanical energy. The existence of the air gap enables this electromagnetic connection to be achieved.

[0034] The exciting winding generates a magnetic field through current, and this process follows Faraday's law of electromagnetic induction. When an electric current passes through a wire, a magnetic field is generated around it. In a generator, the relative motion between the magnetic field generated by the exciting winding and the rotor or stator induces an electromotive force in the stator winding, thereby generating electrical energy.

[0035] 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. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0036] 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 in conjunction with the accompanying drawings and specific embodiments.

[0037] Referring to Figures 1 - 4 , the present invention provides a permanent magnet assisted ring winding electrically excited salient pole synchronous motor, including a stator core 1, a rotor core 2 sleeved with the stator core 1, a ring exciting winding 5 wound around the rotor core 2, and a plurality of permanent magnets 6 arranged on the rotor core;

[0038] The rotor core 2 is of a ring structure. A plurality of corresponding outer slots 3 and inner slots 4 are circumferentially formed on the outer surface and the inner surface of the rotor core 2 respectively. A rotor yoke 10 is formed between the outer slots 3 and the inner slots 4. The ring exciting winding 5 is wound around the rotor yoke 10 through the outer slots 3 and the inner slots 4;

[0039] The permanent magnets 6 are arranged at the openings of the inner slots 4.

[0040] By arranging the outer slots 3 and the inner slots 4 on the rotor core 2, winding the ring exciting winding 5 in the outer slots 3 and the inner slots 4, and arranging the permanent magnets 6 at the openings of the inner slots 4, the ampere-turns of the ring exciting winding 5 can be reduced, thereby reducing the loss of the ring exciting winding 5, 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.

[0041] Further, the ring exciting winding 5 is two coils, and the two coil sides are respectively placed in the outer slots 3 and the inner slots 4.

[0042] Furthermore, the permanent magnet 6 and the adjacent coils wound around the rotor yoke 10 are connected in parallel to provide the magnetic flux per pole. With such a design, when the excitation current of the annular excitation winding 5 is zero, the permanent magnetic field generated by the permanent magnet 6 is completely short-circuited, which can reduce the effective value of the no-load voltage of the stator; as needed, an appropriate reverse excitation current is applied to the annular excitation winding 5 to achieve rotor demagnetization, thereby preventing the stator winding from burning out after a short circuit.

[0043] By using the permanent magnet 6 to assist the annular excitation winding 5 to jointly provide the magnetic flux per pole, it combines the advantages of a permanent magnet synchronous motor and an electrically excited synchronous motor. With the assistance of the permanent magnet 6, when the stator winding 9 generates the same no-load voltage, the required excitation current is reduced, thereby reducing the copper loss of the annular excitation winding 5, reducing the temperature rise of the rotor core 2, and improving the motor efficiency; by adopting the annular excitation winding 5, it is easy to carry out modular design, and at the same time, the length of the end winding of the rotor is reduced, which can further reduce the copper loss of the annular excitation winding 5. Without increasing the rotor loss and temperature rise, the magnetic load can be increased, the volume and weight of the motor can be reduced, and the power density can be improved; secondly, by adopting the annular excitation winding 5, the width of the rotor slot can be reduced, the width of the pole body of the magnetic pole can be increased, and the saturation degree of the magnetic circuit can be reduced, which can also play a role in increasing the magnetic load.

[0044] In an embodiment of the present invention, there is an air gap 7 between the stator core 1 and the rotor core 2.

[0045] The annular excitation winding 5 is excited by passing a direct current, forming N poles and S poles that are alternately distributed on the circumference of the air gap 7.

[0046] In an embodiment of the present invention, the magnetization direction of the permanent magnet 6 is perpendicular to the radial direction of the rotor core 2, and the magnetization directions of two adjacent permanent magnets 6 are opposite. The design of this structure 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.

[0047] In an embodiment of the present invention, it further includes a support member 8 for connecting with the rotor core 2, and the support member 8 is made of a non-magnetic material.

[0048] In an embodiment of the present invention, the stator core 1 is coated on the outer circle of the rotor core 2. Secondly, the rotor core 2 is coated on the outer circle of the stator core 1 to form an outer rotor structure motor.

[0049] In an embodiment of the present invention, a plurality of grooves are circumferentially formed in the inner circle of the stator core 1, and a stator winding 9 is wound between the plurality of grooves.

[0050] In an embodiment of the present invention, the permanent magnet 6 is composed of a plurality of equally spaced magnetic blocks.

[0051] In an embodiment of the present invention, the permanent magnet 6 is composed of multiple magnet blocks arranged in a fitting manner.

[0052] Compared with the series-type hybrid excitation synchronous motor: the electric excitation circuit does not pass through the permanent magnet, has a small magnetic resistance, high excitation efficiency, and when operating in weak magnetic field, there is no demagnetization risk for the permanent magnet.

[0053] Compared with the parallel-type hybrid excitation synchronous motor: the internal space of the motor can be fully utilized, the volume is reduced, the weight of the motor is decreased, and the reliability of the rotor structure is improved.

[0054] Compared with the existing conventional electric excitation 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 annular excitation winding 5, reducing the rotor temperature rise, and improving the motor efficiency; by adopting the annular excitation winding 5, the width of the rotor slot can be reduced, the width of the pole body of the magnetic pole can be increased, so as to increase the magnetic flux per pole, and at the same time, the length of the end winding of the rotor can be reduced, further reducing the copper loss of the annular excitation winding 5. When the excitation current of the annular excitation winding 5 is zero, the permanent magnetic field generated by the permanent magnet 6 is all short-circuited, which can reduce the effective value of the stator no-load voltage; according to the need, an appropriate reverse excitation current is applied to the excitation winding to achieve rotor demagnetization, thereby preventing the stator winding from being burned out after a short circuit.

[0055] As Figure 2 shown, the present invention is a magnetic force line distribution diagram during no-load operation. It can be clearly seen from the figure that the permanent magnet 6 and the adjacent annular excitation winding 5 wound on the rotor yoke 10 are in parallel to provide the magnetic flux per pole, and the magnitude of the air-gap magnetic field can be adjusted by adjusting the magnitude of the current of the annular excitation winding 5.

[0056] As Figure 3 and Table 1 show, taking the no-load rated phase voltage of 4 kV as an example, the excitation current required for the conventional electric excitation salient pole synchronous motor is 93.18 A, while the excitation current required for the present invention can be reduced to 40.78 A, significantly reducing the rotor excitation copper loss, thereby reducing the rotor temperature rise and improving the motor efficiency.

[0057]

[0058] Table 1. Comparison table of no-load voltages generated by the present invention and the conventional electric excitation salient pole synchronous motor at the same excitation current

[0059] Furthermore, as Figure 4 shown, when the current of the annular excitation winding 5 of the present application is zero, the permanent magnetic field generated by the permanent magnet 6 is all short-circuited. At this time, the effective value of the stator no-load voltage is only 5.7 V, which is 0.14% of the rated value, significantly reducing the stator no-load voltage. According to the need, an appropriate reverse excitation current is applied to the annular excitation winding 5 to achieve rotor demagnetization.

[0060] 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-regulating operation driving occasions.

[0061] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "lateral", "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. It 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.

[0062] 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 toroidal winding electrically excited salient pole synchronous motor, characterized in that: It comprises a stator core (1), a rotor core (2) sleeved with the stator core (1), an annular excitation winding (5) wound on the rotor core (2), and a plurality of permanent magnets (6) arranged on the rotor core; The rotor core (2) is an annular structure, and the outer surface and inner surface of the rotor core (2) are respectively provided with a plurality of outer slots (3) and inner slots (4) corresponding to each other in a circumferential direction, a rotor yoke (10) is formed between the outer slots (3) and the inner slots (4), and the annular excitation winding (5) is wound on the rotor yoke (10) through the outer slots (3) and the inner slots (4); The permanent magnet (6) is arranged at the slot opening of the inner slot (4).

2. A permanent magnet assisted toroidal winding electrically excited salient pole synchronous motor according to claim 1, characterized in that: An air gap (7) is provided between the stator core (1) and the rotor core (2).

3. The permanent magnet assisted toroidal winding electrically excited salient pole synchronous motor according to claim 1, characterized in that: The magnetization direction of the permanent magnet (6) is perpendicular to the radial direction of the rotor core (2).

4. The permanent magnet assisted toroidal winding electrically excited salient pole synchronous motor according to claim 1, characterized in that: The magnetization directions of the two adjacent permanent magnets (6) are opposite.

5. The permanent magnet assisted toroidal winding electrically excited salient pole synchronous motor according to claim 1, characterized in that: It also comprises a support member (8) for connecting with the rotor core (2).

6. The permanent magnet assisted toroidal winding electrically excited salient pole synchronous motor according to claim 1, characterized in that: The stator iron core (1) is coated on the outer ring of the rotor iron core (2).

7. The permanent magnet assisted toroidal winding electrically excited salient pole synchronous motor according to claim 1, characterized in that: The rotor iron core (2) is coated on the outer ring of the stator iron core (1).

8. The permanent magnet assisted toroidal winding electrically excited salient pole synchronous motor according to claim 1, characterized in that: The inner ring of the stator core (1) is provided with a plurality of grooves in the circumferential direction, and stator windings (9) are wound between the grooves.

9. The permanent magnet assisted toroidal winding electrically excited salient pole synchronous motor according to claim 1, characterized in that: The permanent magnet (6) is composed of a plurality of magnetic blocks arranged at equal intervals.

10. The permanent magnet assisted toroidal winding electrically excited salient pole synchronous motor according to claim 1, characterized in that: The permanent magnet (6) is composed of a plurality of magnetic blocks arranged in close contact.

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