Axial electric motor having yoke

Abstract

The present invention relates to a method for improving the performance of a single-phase axial flux motor that generates a magnetic field horizontal to a rotation shaft, wherein permanent magnets are arranged on both sides of a core, the number of permanent magnets on one side is the same as the number of cores, and electricity is simultaneously applied to all of coils to generate the magnetic field and thereby rotate the motor. The present invention is characterized by being an axial flux motor having a structure in which permanent magnets are arranged on both sides of a core, the permanent magnets on both sides are arranged such that there is a phase difference, the number of permanent magnets on one side surface is the same as the number of cores, and the cores are connected by a yoke. According to the present invention, when the permanent magnets are arranged on both sides of the core and the permanent magnets on both side surfaces are arranged such that there is a phase difference when facing each other, there is a problem in that a reverse torque is generated in a certain rotation section of the axial motor due to the magnetic field of the permanent magnets on one side surface, and therefore the torque and efficiency of the motor can be improved while minimizing the generation of reverse torque by connecting the cores via the yoke.

Description

Axial electric motor with yoke

[0001] The present invention relates to an electric motor having high output and low weight characteristics necessary for developing UAM, drones, electric vehicles, e-mobility, robots, etc.

[0002] The electric motor of the present invention is based on axial electric motor technology that rotates the motor while generating a magnetic field parallel to the rotation axis, but is a single-phase electric motor rather than a conventional three-phase electric motor, and requires a new permanent magnet and core arrangement and operating principle to implement the single-phase method.

[0003] The present invention relates to an additional technical invention for solving problems of the existing patented single-phase axial electric motor technology.

[0004]

[0005] The present invention is intended to complement the high-efficiency DC motor technology disclosed in Republic of Korea Patent Registration No. 10-2200620. Typically, an axial flux motor, which generates a magnetic field parallel to the axis of rotation, has a structure in which permanent magnets are placed on both sides of the core without a yoke, or on only one side of the core with a yoke.

[0006] Patent 10-2200620 discloses an axial motor with a single-phase power input method that arranges permanent magnets on both sides of a core, has a structure in which the number of permanent magnets on one side is the same as the number of cores, and the permanent magnets arranged on both sides are arranged with a phase difference so that the center points of the magnets are located between the magnets on the opposite side, and has a structure in which there is no yoke in the core, and when the motor rotates, electricity is simultaneously applied to all coils to generate a magnetic field, and the motor rotates with the repulsive and attractive forces generated by the magnetic field generated in the coils and the magnetic field of the permanent magnets, and continuously rotates the motor by simultaneously changing the direction of the magnetic field of all coils according to the rotation phase.

[0007] However, when a motor is manufactured and rotated with this structure, there is a problem in that the repulsive force generated between the magnetic field generated from the core and the magnetic field generated from the permanent magnet on one side generates torque in a direction opposite to the direction of rotation at a certain rotational section, which causes the rotational torque of the motor to be uneven and reduces efficiency, and therefore a method to improve this problem is needed.

[0008]

[0009] The rotating machine presented in Patent 10-2200620 includes upper permanent magnets arranged in a circle with different polarities of adjacent permanent magnets at the upper end in the vertical direction of the rotating shaft, lower permanent magnets arranged in a circle with different polarities of adjacent permanent magnets at the lower end in the vertical direction of the rotating shaft and arranged so that the center point of the lower permanent magnet is located between the upper permanent magnets, a plurality of electromagnets arranged in a columnar shape between the upper and lower permanent magnets and having different polarity directions between adjacent electromagnets when electricity is applied, and a fixture that fixes the electromagnets between the upper permanent magnets and the lower permanent magnets, wherein the plurality of electromagnets are structured to be located closer to either the lower permanent magnets or the upper permanent magnets or to have different sizes of permanent magnets.

[0010] However, when a rotating machine manufactured with this structure is rotated, there is a problem that the magnetic field generated from the side of the permanent magnet with weaker magnetic force among the permanent magnets on both sides and the magnetic field generated from the core generates a torque opposite to the motor rotation due to the phase difference between the upper and lower permanent magnets, which reduces the efficiency of the motor. However, if the permanent magnets on the upper and lower sides are arranged facing each other so that there is no phase difference, there is a problem that the motor does not start initially and the cogging torque increases, so the phase difference of the magnets is necessary. Therefore, a method is needed to reduce the generation of reverse torque while maintaining the phase difference of the permanent magnets on both sides.

[0011]

[0012] In order to solve the problem of such reverse torque generation, a motor having a structure including upper permanent magnets arranged in a circle with different polarities at the upper end of the vertical direction of the rotation axis as presented in Patent 10-2200620, lower permanent magnets arranged in a circle with different polarities at the lower end of the vertical direction of the rotation axis and arranged so that the center point of the lower permanent magnet is located between the upper permanent magnets, a plurality of electromagnets arranged in a columnar shape between the upper and lower permanent magnets and having different polarity directions between adjacent electromagnets when electricity is applied, and a fixture that fixes the electromagnets between the upper permanent magnets and the lower permanent magnets, can improve this problem by adding a yoke made of a magnetic material instead of an electromagnet (core) fixture for fixing the core, thereby creating a path through which the magnetic field generated from the core and the permanent magnet can move to the adjacent core through the yoke.

[0013] When the core is connected to the yoke as shown in Fig. 2, the magnetic field generated from the coil and the core and the magnetic field generated from the permanent magnet move harmoniously through the yoke as shown in Fig. 3, which reduces the occurrence of reverse torque and improves torque and efficiency while the motor maintains a constant torque.

[0014] In addition, in Patent 10-2200620, the method of making the magnetic field strength of the permanent magnets generated on both sides different by making the sizes of the permanent magnets on the upper and lower sides different or making the air gap distance between the permanent magnets and the core different is because the core has a yoke, so the magnetic field of the permanent magnets on the yoke surface is absorbed by the yoke and flows, so the permanent magnets adjacent to the yoke surface do not generate a large physical torque and play a role in strengthening the magnetic field on the opposite side of the core, so there is no need to adjust the magnetic field strength by making the sizes of the permanent magnets different or adjusting the air gap distance between the permanent magnets and the core for the initial start of the motor.

[0015] However, in general, motors with a yoke have permanent magnets arranged on the surface close to the core end and not on the surface where the yoke is, because the magnetic field generated is small on the yoke surface and the magnetic field generated is strongest at the core end. As shown in Fig. 3, in the case of an axial motor with a yoke in which the upper and lower permanent magnets are arranged with a phase difference, the magnetic field generated from the lower permanent magnet is absorbed by the yoke, suppressing the generation of counter torque, and the absorbed magnetic field increases the strength of the magnetic field generated at the end of the core adjacent to the upper permanent magnet. Therefore, it was confirmed through experiments that the torque and rotational speed increase by more than 10% compared to the case where there is no lower permanent magnet.

[0016] However, there may be a problem (loss) of heat generation due to eddy current generation on the yoke surface due to the magnetic field of the permanent magnet rotating adjacent to the yoke, but if the yoke is made of a structure that laminates powdered metal or electrical steel plates, or if the yoke is manufactured using a material with low eddy current loss, the eddy current loss and heat generation can be reduced. In addition, since the performance improvement effect due to the yoke is greater than that of a motor without a yoke or a motor with a yoke but with permanent magnets on only one side, an axial motor with a yoke and permanent magnets arranged on both sides has higher marketability.

[0017]

[0018] The electric motor invented in Patent 10-2200620 has an axial flux motor structure and rotates the motor by generating a magnetic field simultaneously in all coils within the motor, so the weight of the motor can be reduced by more than 20% compared to existing BLDC motors and induction motors of the same output.

[0019] However, there were problems such as low efficiency and large vibration of the motor compared to the existing BLDC motor, but through the method of adding a yoke to the core suggested in the present invention, the efficiency of the motor was improved and the vibration of the motor was greatly reduced, thereby improving the performance of the motor and enhancing the marketability of the motor.

[0020]

[0021] FIG. 1 is a cross-sectional view of an axial magnetic generating motor having a structure in which a core according to the present invention is connected to a yoke and permanent magnets are arranged on the upper and lower surfaces of the core.

[0022] Figure 2 is a cross-sectional view of a core structure in which the core according to the present invention is connected to a yoke.

[0023] Figure 3 is a plan view illustrating the principle by which the problem of reverse torque generated by the lower permanent magnet in a certain rotation section of the motor is solved through the present invention.

[0024] Figure 4 is a plan view illustrating the torque generation principle in a rotation section in which reverse torque is not generated in a certain rotation section of the motor through the present invention.

[0025]

[0026] Hereinafter, the present invention will be described with reference to the attached drawings.

[0027] Fig. 1 is a cross-sectional view of an axial magnetic generating motor having a structure in which a core according to the present invention is connected to a yoke and permanent magnets are arranged on the upper and lower surfaces of the core, and Fig. 2 is a cross-sectional view of a core having a structure in which the core according to the present invention is connected to a yoke. Fig. 3 is a plan view explaining the principle by which the problem of reverse torque generation by a lower permanent magnet in a certain rotation section of a motor is solved through the present invention. Fig. 4 is a plan view explaining the principle of torque generation in a rotation section in which reverse torque is not generated in a certain rotation section of a motor through the present invention.

[0028] The present invention will be described with reference to the cross-sectional view of FIG. 1, which includes an upper permanent magnet rotating part (200) arranged in a circle so that adjacent permanent magnets have different polarities, a lower permanent magnet rotating part (300) arranged in a circle so that adjacent permanent magnets have different polarities at a lower portion in the vertical direction of the rotation axis and so that the lower permanent magnet (310) is positioned between the upper permanent magnets (210), a plurality of coils (120) arranged in a columnar shape between the upper and lower permanent magnets (210, 310) and having different magnetic field polarity directions between adjacent cores (110) when electricity is applied, and a magnetic yoke (130) for moving a magnetic field as shown in FIG. 2 while fixing the core (110) between the upper permanent magnet (210) and the lower permanent magnet (310) and the electromagnet to which the core (110) and the coil (120) are coupled.

[0029] The motor invented in Patent 10-2200620 is manufactured in a form without a yoke, and when the motor is rotated, as shown in FIG. 3, when the upper and lower permanent magnets (210, 310) and the core (110) are aligned, a torque is generated in the direction opposite to the motor rotation due to the lower permanent magnet (310), which causes a problem in that the torque is reduced and the efficiency is reduced.

[0030] Therefore, in order to solve this problem of reverse torque generation, the core (110) is manufactured in a form in which it is combined with a magnetic yoke (130) as shown in FIG. 2, and the core part is manufactured by winding a coil (120) around the core (110) like the motor core part (100) of FIG. 1, thereby improving the problem of reverse torque generation. In addition, due to the magnetic yoke (130), even if the phase difference between the upper and lower permanent magnets (210, 310) is such that the center points of the opposite magnets are not located exactly in the middle between the magnets but only between the magnets, there is no problem in the initial start, but the optimal phase difference must be found and determined by considering the main rotation direction of the motor, the size of the core and magnets, the method of use of the motor, and the efficiency.

[0031] The drawing expressed in Fig. 3 explains the principle of reducing reverse torque due to the magnetic yoke (130) in the alignment section of the permanent magnet and the core where reverse torque can occur. In a situation where the upper and lower permanent magnets (210, 310), which are the motor rotors, move to the right, when the upper permanent magnet (210) is located to the right of the core (110) and the lower permanent magnet (310) is located to the left of the core (110), when a magnetic field is generated in the core (110) as in Fig. 3, a repulsive force indicated by an arrow (402) is generated due to the magnetic fields of the upper permanent magnet (210) and the core (110), thereby generating a torque that moves the permanent magnet to the right (see arrow (401)). Among the magnetic fields generated from the core (110), the magnetic field generated near the magnetic yoke (130) moves to the adjacent core through the yoke and increases the magnetic field strength generated at the end of the core (110) adjacent to the upper permanent magnet (210).

[0032] And, the magnetic field (indicated as 404) generated from the lower permanent magnet (310) is absorbed by the yoke (130) and moves to the core (405) where the opposite polarity is generated, thereby increasing the strength of the magnetic field generated at the end of the core (110) connected to the upper permanent magnet, thereby reducing the generation of reverse torque and increasing the torque and efficiency of the motor.

[0033] The drawing expressed in Fig. 4 explains the principle of magnetic field flow and torque generation due to the yoke (130) in the alignment section of the permanent magnet and core where no reverse torque is generated. When the permanent magnets (210, 310), which are the motor rotors, are in a state where they move to the right, the upper permanent magnets (210) and the lower permanent magnets (310) are located to the right of the core (110), and the magnetic field generated from the upper permanent magnet (210) and the magnetic field generated from the core (110) generate a repulsive force (indicated as 402) and an attractive force (indicated as 403), generating a torque (401) that moves to the right, and the magnetic field generated from the lower permanent magnet (301) and the magnetic field (405) generated from the core (110) and flowing along the yoke generate a repulsive force (indicated as 402) and an attractive force (indicated as 403) that are smaller than the force generated from the upper permanent magnet, generating a torque (401) that moves the lower permanent magnet (310) to the right.

[0034] However, the magnetic field generated from the lower permanent magnet (310) interacts with the magnetic field generated from the core (110) due to the yoke (130) and the repulsive force (indicated by 402) and attractive force (indicated by 403) are weak, and the magnetic field generated from the lower permanent magnet (310) increases the strength of the magnetic field generated at the upper end of the core (110) along the yoke, thereby increasing the repulsive force (indicated by 402) and attractive force (indicated by 403) with the upper permanent magnet (210), thereby helping to generate a greater torque.

[0035] In addition, even if the position of the lower permanent magnet (310) is out of phase with respect to the upper permanent magnet (210) due to the yoke, there is no problem of the lower permanent magnet interfering with the initial start or reducing efficiency by generating reverse torque. Therefore, the axial motor with the invented yoke can generate greater torque than an axial motor with a yoke and permanent magnets on the cross-section, and other motor performances are also improved.

[0036] Compared to BLDC or induction motors, axial motors have a higher magnetic density, allowing for reduced motor weight and higher torque generation. Because of their light weight and high torque generation, axial motors are being developed for use in aircraft and e-mobility applications. With improvements in efficiency and advancements in manufacturing technology, they have the potential to replace conventional motors.

[0037] While existing commercially available axial motors are three-phase, the electric motor invented in Patent 10-2200620 is a single-phase motor and, due to the principle of using coils simultaneously, has the advantage of being lighter than existing axial motors. However, there was a need to improve the maintenance of constant torque, vibration, efficiency, etc., and through the present invention, these issues were improved, making it competitive with existing axial motors.

[0038] In the coming future, internal combustion engines will gradually disappear, replaced by electric motors. Demand for high-efficiency electric motors is expected to increase significantly. Therefore, single-phase axial motor technology, which enables the production of high-torque, highly efficient, and lightweight motors, is expected to generate significant demand in the electric motor market.

Claims

1. A rotating electric machine including an upper permanent magnet in which a plurality of permanent magnets are arranged in a circle at the upper end in the vertical direction of a rotation axis, a lower permanent magnet in which a plurality of permanent magnets, the same number as the number of upper permanent magnets, are arranged at the lower end in the vertical direction of a rotation axis so that the center point of the lower permanent magnets is located between the upper permanent magnets, a core having a coil coupled between the upper and lower permanent magnets, arranged in a circular columnar shape so that a magnetic field is generated in the core when a magnetic field is generated in the core, and a plurality of cores in which the magnetic field polarity directions are different between adjacent cores when electricity is applied to the coil, and a yoke made of a magnetic material that connects the cores located between the upper permanent magnets and the lower permanent magnets and serves as a passage for a magnetic field generated from the coil and the permanent magnets.

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