Self-starting low-speed oxygenation pump motor

Abstract

A self-starting low-speed oxygenation pump motor is composed of a rotor permanent magnet, a rotor iron core, a stator iron core, a rotor iron core, a three-phase stator winding, a rotor support, a rotating shaft and a machine shell, the three-phase stator winding comprises an A phase, a B phase and a C phase, and the stator iron core is installed in a machine shell hole; the rotor iron core is arranged on the rotating shaft and is arranged in the stator iron core hole; the three-phase stator winding is embedded into a tooth groove of the stator iron core; s poles and N poles of the permanent magnets are alternately distributed; the windings only cross over one stator tooth, and the polarities of magnetic fields generated when the adjacent stator windings are electrified are opposite; magnetic fields generated by the stator windings of all phases are only distributed in corresponding phase areas of all phases and respectively form pulsating magnetic fields, and the pulsating magnetic fields of all phases act on the rotor at the same time to generate superimposed pulsating torque; the superposed pulsating torque can be decomposed into a positive sequence pulsating torque component and a negative sequence pulsating torque component; the negative-sequence pulsating torque components of all phases are superposed and counteracted, the positive-sequence pulsating torque components are added, and the alternating frequency of the positive-sequence pulsating torque is lower than the frequency of a power supply, so that frequency-reduction self-starting is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electric machines, in particular to the field of low-speed direct-drive self-starting electric machines. BACKGROUND

[0002] The oxygen-increasing pump motor generally adopts the mode of permanent magnet motor plus driving control, which not only increases the manufacturing cost and reduces the reliability, but also the existing oxygen-increasing pump motor has high speed and large noise, which affects the living environment of aquatic organisms and the surrounding ecological environment.

[0003] In order to increase the output torque, the conventional low-speed direct-drive permanent magnet motor adopts the method of increasing the outer diameter of the rotor and increasing the number of pole pairs of the permanent magnet, which causes the increase of the manufacturing cost of the motor, therefore, it is urgent to seek a new solution. SUMMARY

[0004] In view of the existing problems, it is necessary to invent a permanent magnet motor different from the conventional rotating magnetic field working principle. The working principle of the new motor is that the stator winding generates each phase pulse magnetic field, the multi-phase pulse magnetic field acts on the same rotor, the generated each phase pulse torque is superimposed, the alternating frequency of the pulse torque is reduced, and the motor is self-starting. In this way, the amount of rotor permanent magnet can be reduced, and the manufacturing cost can be reduced. With the support of colleges and research institutions, our company has developed a self-starting low-speed oxygen-increasing pump motor after three years. After testing by the authoritative institution, the starting time is 20-40 ms (milliseconds), the output power is 1350 W, and the requirements of self-starting low-speed of the oxygen-increasing pump can be fully met.

[0005] The utility model provides a kind of self-starting low-speed oxygenation pump motor, is by rotor permanent magnet, stator core, rotor core, three-phase stator winding, rotating shaft, shell, machine cover component and tapered roller bearing, characterized by, stator core is installed in shell hole, three-phase stator winding is wound on the tooth of stator core, rotor core is installed in stator core hole along with rotating shaft, machine cover component and tapered roller bearing are installed in shell both ends, structure and connection mode are same with Y series three-phase asynchronous motor;The stator core is made of silicon steel sheet lamination, and the stator core has stator core salient pole, stator core yoke and wire slot, similar to Y series three-phase asynchronous motor;The rotor core is made of silicon steel sheet lamination, and the rotor core has rotor core salient pole and rotor core yoke;Rotor permanent magnet is embedded in rotor core salient pole partial slot, and is bonded with high-temperature resistant glue;The rotor permanent magnet is tile-shaped, and the lower part of the tile-shaped is attached to the rotor, and the two sides are embedded in the rotor slot;The rotating shaft end is equipped with oxygenation pump impeller, and transmits torque with flat key, and is fastened with nut;Machine cover and shell are fastened with standard parts, and the assembly mode is same with Y series three-phase asynchronous motor;The permanent magnet and the salient pole of the core are alternately arranged on the circumference of the rotor, forming an alternating pole structure;The N pole and S pole of the permanent magnet are alternately distributed;Each stator tooth of the stator winding is wound with stator winding, and the winding only crosses one stator tooth, and the polarity of the magnetic field generated by adjacent stator windings when energized is opposite;By using ANSYS Motor-CAD simulation design software, the shape of the permanent magnet, rotor core salient pole and stator tooth is designed to make the air gap flux density close to sinusoidal distribution;The magnetic field generated by each phase stator winding is only distributed in the corresponding phase area, and each forms a pulse magnetic field, and the pulse magnetic fields of each phase act on the rotor simultaneously to generate superimposed pulse torque;The superimposed pulse torque can be decomposed into positive sequence pulse torque component and negative sequence pulse torque component;Each phase negative sequence pulse torque component is superimposed and cancelled, and the positive sequence pulse torque component is added, and the alternating frequency of the positive sequence pulse torque is lower than the power frequency, so that frequency reduction self-starting is realized;For three-phase motor, the number of permanent magnet poles P m , P m is a positive integer, and cannot be a multiple of 3 of the number of motor phases;When the number of permanent magnet poles P m is 3k+1 (k=0, 1, 2, 3...), negative sequence three-phase current is input, and the motor will be self-started in the positive direction;The greatest common divisor of the number of stator slots and the number of rotor magnetic poles P m is as small as possible to reduce the cogging torque and improve the self-starting performance。(Machine cover component, tapered roller bearing is omitted in the figure) BRIEF DESCRIPTION OF DRAWINGS

[0006] Figure 1 is the cross-sectional view of the utility model;

[0007] Figure 2 is the enlarged view of the rotor section in the utility model;

[0008] Figure 3This is an enlarged view of the stator cross-section in this invention.

[0009] In the figure, rotor permanent magnet .1, stator core .2, stator core salient pole .2-1, stator core yoke .2-2, rotor core .3, rotor teeth .3-1, rotor core yoke .3-2, three-phase stator winding .4, shaft .5, housing .6.

[0010] Figure 4 It is a waveform diagram of a single phase magnetomotive force invented;

[0011] Figure 5 This is a simulation diagram of the torque waveform during the starting process of this invention;

[0012] Figure 6 This is a simulation diagram of the speed waveform during the starting process of this invention;

[0013] Figure 7 It is the waveform of the air gap magnetic flux density distribution along the circumference;

[0014] Figure 8 This is a spectral analysis diagram of the air gap magnetic flux density distribution waveform. Detailed Implementation

[0015] The principle of the present invention will be explained below. The present invention is a three-phase 30-slot / 14-pole alternating pole pulsating magnetic field self-starting. Specifically, the motor rotor is made of silicon steel sheets with salient pole shape stacked together, and permanent magnets and iron core salient poles are alternately arranged around the rotor to form an alternating pole structure.

[0016] like Figure 1 , Figure 2 , Figure 3 As shown, the rotor has 14 pairs of teeth, and the stator has 30 teeth, forming a 30-slot / 14-pair alternating pole permanent magnet motor structure. The stator teeth are wound with windings, and the three-phase windings are as follows... Figure 2 The distribution is shown as a 120° phase zone.

[0017] The winding spans only one stator tooth, and the magnetic fields generated when adjacent stator windings are energized have opposite polarities. By coordinating the design of the permanent magnet, the rotor core salient pole, and the stator tooth shape, the air gap magnetic flux density is made to be approximately sinusoidal.

[0018] Figure 4 The figure shows the magnetomotive force waveform of one phase in this embodiment. In the figure, mmf represents the magnetomotive force and slot represents the stator slot. It can be seen that the magnetic field generated by each phase stator winding pulsates only in the corresponding phase region, forming a pulsating magnetic field and generating a pulsating torque. The pulsating torque can be decomposed into a positive-sequence pulsating torque component and a negative-sequence pulsating torque component. When a negative-sequence current is applied, the positive-sequence pulsating torques of each phase are superimposed and canceled out. The alternating frequency of the negative-sequence pulsating torque is lower than the power supply frequency, thereby achieving frequency reduction self-starting.

[0019] Figure 5 For the starting process torque graph when negative sequence current is passed, after starting, the torque is stable.

[0020] Figure 6 For the speed waveform graph when negative sequence current is passed, after starting, the speed is stable.

[0021] Figure 7 It is the air gap magnetic flux distribution waveform along the circumference, and when small high-order harmonics are ignored, it is close to a sine wave.

[0022] Figure 8 It is the frequency spectrum analysis of the air gap magnetic flux distribution waveform, and it can be seen that the fundamental wave is the largest, followed by the 3rd harmonic, and the 5th and above harmonics are already small enough to be ignored. In the case of ignoring the small 3rd harmonic, the air gap magnetic field is basically the fundamental wave, that is, the above-mentioned sine wave.

[0023] The simulation design is carried out under the guidance of experts from Huazhong University of Science and Technology, and by using ANSYS Motor-CAD simulation design software to design permanent magnets, rotor iron core salient poles and stator tooth shapes, the air gap magnetic flux is close to a sine distribution.

[0024] In the design, the number of stator teeth is about twice the number of rotor permanent magnets, the pole arc of the permanent magnet is equal to the pole arc of the rotor iron core salient pole, and the stator tooth shape is designed to ensure that the local saturation degree of the tooth tip is not high, and the air gap magnetic flux distribution waveform along the circumference is shown in the following figure, and when small high-order harmonics are ignored, it is close to a sine wave. The motor design has always been designed towards the direction of sinusoidal air gap, but in practice, the magnetic field will appear harmonics due to the influence of the slot and local saturation, as long as the harmonics are much smaller than the fundamental wave, it is considered that the magnetic field is close to a sine wave. Due to the complexity of the motor structure, it is difficult to express by formula, so the motor design generally relies on magnetic field finite element calculation, and the magnetic field simulation result proves the relevant description.

[0025] The structure of the application will be further described below in combination with the drawings, such as Figure 1 , Figure 2 , Figure 3As shown, the application is composed of a rotor permanent magnet, a rotor core, a stator core, a rotor core, a three-phase stator winding, a rotor support, a rotating shaft and a machine shell, the three-phase stator winding contains three phases of A, B and C, the stator core is installed in the machine shell hole; the rotor core is installed on the rotating shaft and in the stator core hole; the three-phase stator winding is wound on the stator core teeth, the machine cover assembly and the tapered roller bearing are installed at both ends of the machine shell; the stator core is made of silicon steel sheets, the stator core has rotor core salient poles and rotor core magnetic yokes; the rotor core is made of silicon steel sheets, the rotor core has rotor core salient poles and rotor core magnetic yokes; the rotor permanent magnet is embedded in the rotor core salient pole part slot and bonded with high-temperature resistant glue; the rotating shaft end is provided with an oxygen increasing pump impeller, the torque is transmitted by a flat key and fastened by a nut; the machine cover assembly and the machine shell are fastened by standard parts, the assembly mode is the same as that of a Y series three-phase asynchronous motor; the permanent magnet and the rotor core salient poles are alternately arranged on the rotor circumference to form an alternating pole structure, the S poles and the N poles are alternately distributed; the stator winding is wound on each stator tooth of the stator winding, the winding only crosses one stator tooth, and the polarity of the magnetic field generated by the adjacent stator windings when electrified is opposite; by matching the design of the permanent magnet, the rotor core salient pole and the stator tooth shape, the air gap magnetic density is close to a sine distribution; the magnetic field generated by each phase stator winding is only distributed in the corresponding phase area, and each forms a pulse magnetic field, the pulse magnetic fields of each phase act on the rotor at the same time to generate a superimposed pulse torque; the superimposed pulse torque can be decomposed into a positive sequence pulse torque component and a negative sequence pulse torque component; the negative sequence pulse torque components of each phase are superimposed and cancelled out, the positive sequence pulse torque components are added, and the alternating frequency of the positive sequence pulse torque is lower than the power frequency, so that the frequency reduction self-starting is realized; the permanent magnet pole number P m = 28, the permanent magnet pole number P m is 3k+1; the stator slot number is 30, which can meet the condition that the greatest common divisor is as small as possible and improve the self-starting performance.

[0026] By matching the design of the permanent magnet, the rotor core salient pole and the stator tooth shape, the air gap magnetic density is close to a sine distribution. The air gap magnetic field is distributed along the circumference according to the sine wave, and the phase flux linkage can be expressed as: Ψ = ψ m cosp(θ-θ0); in the formula, ψ m is the phase flux linkage amplitude, θ0 is the initial position angle of the rotor, and p is the magnetic field pole pair number.

[0027] In summary, for a three-phase motor, the permanent magnet pole number P m cannot be a multiple of the phase number 3, otherwise the motor cannot self-start; when the permanent magnet pole number P m is 3k+1, the motor will self-start in the positive direction when the positive sequence three-phase current is input. The permanent magnet pole number P m of the design is 28, which meets the permanent magnet pole number P mThe stator slot number is 30, which can satisfy the condition that the greatest common divisor is as small as possible, and can satisfy and improve the self-starting performance.

[0028] The above only describes the preferred embodiments of the present application, and any modification, equivalent replacement, improvement, etc. within the principles of the present application shall be included in the protection scope of the present application.

[0029] The present application can be used in the low-speed direct-drive self-starting field of fish pond oxygenation pumps, industrial ceiling fans, fans, etc., and has a broad application prospect.

Claims

1. A self-starting low-speed oxygen-increasing pump motor, which is composed of a rotor permanent magnet (1), a stator core (2), a rotor core (3), a three-phase stator winding (4), a rotating shaft (5), a machine shell (6), a machine cover assembly and a tapered roller bearing, characterized in that, The stator core is installed in the housing bore, and the three-phase stator windings are wound on the teeth of the stator core. The rotor core, along with the shaft, is installed in the stator core bore. The cover assembly and tapered roller bearings are installed at both ends of the housing. The structure and connection method are the same as those of the Y-series three-phase asynchronous motor. The stator core is made of laminated silicon steel sheets and has stator core salient poles (2-1), stator core yokes (2-2), and slots (2-3), similar to those of the Y-series three-phase asynchronous motor. The rotor core is also made of laminated silicon steel sheets and has rotor core salient poles (3-1) and rotor core yokes (3-2). The rotor permanent magnets are embedded in the rotor core salient poles. The slots are partially bonded with high-temperature resistant adhesive; the rotor permanent magnet is tile-shaped, with the lower part of the tile fitting against the rotor and the two sides embedded in the rotor slots; the end of the shaft is equipped with an oxygen pump impeller, which transmits torque using a flat key and is secured with a nut; the cover and housing are secured with standard parts, and the assembly method is the same as that of the Y-series three-phase asynchronous motor; the permanent magnets and the iron core salient poles are alternately arranged on the rotor circumference, forming an alternating pole structure; the N poles and S poles of the permanent magnets are alternately distributed; each stator tooth of the stator winding is wound with a stator winding, and the winding only crosses one stator tooth, and the polarity of the magnetic field generated when adjacent stator windings are energized is opposite; by using ANSYS Motor-CAD simulation design software, in conjunction with the design of permanent magnets, rotor core salient poles, and stator tooth shapes, ensures that the air gap magnetic flux density is approximately sinusoidal. The magnetic fields generated by each phase stator winding are distributed only in their respective phase regions, each forming a pulsating magnetic field. These pulsating magnetic fields simultaneously act on the rotor, generating superimposed pulsating torque. This superimposed pulsating torque can be decomposed into positive-sequence and negative-sequence pulsating torque components. The negative-sequence pulsating torque components of each phase are superimposed and canceled out, while the positive-sequence pulsating torque components are added together. The alternating frequency of the positive-sequence pulsating torque is lower than the power supply frequency, thus achieving frequency reduction self-starting. For a three-phase motor, the number of pole pairs of the permanent magnet is P. m P m It must be a positive integer and cannot be a multiple of the number of motor phases (3); when the number of permanent magnet poles P m When the value is 3k+1 (k = 0, 1, 2, 3...), applying a negative sequence three-phase current will cause the motor to start in the forward direction; the number of stator slots and the number of rotor magnetic pairs P of the motor... m The greatest common divisor should be minimized to reduce cogging torque and improve self-starting performance. (The cover assembly and tapered roller bearing are omitted in the diagram).

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