CN113422447A

CN113422447A - Electric machine

Info

Publication number: CN113422447A
Application number: CN202110418971.8A
Authority: CN
Inventors: 李锦洪
Original assignee: Jiangmen Xinke Motor Co ltd
Current assignee: Jiangmen Xinke Motor Co ltd
Priority date: 2021-04-19
Filing date: 2021-04-19
Publication date: 2021-09-21

Abstract

The invention relates to the field of motor electromagnetism, and particularly discloses a motor, which comprises a stator and a rotor, wherein the number of pole pairs of the motor is 10; the stator comprises a circular hollow iron core, a stator winding and a magnet; the inner diameter of the round hollow iron core is 10-90mm, the outer diameter is 150mm, the yoke height is 35mm, and 18 winding slots extending inwards are uniformly distributed on the circumference of the round hollow iron core; the stator winding is in a double-layer winding type, the pitch is 1, the number of parallel circuits is 1, the wire diameter is 0.2-0.8mm, and the number of turns of each coil is 80-300; the thickness of the magnet is 2.6mm, and the height of the magnet is 10-100 mm; the inner diameter of the rotor is 156.7mm, and the height of the yoke is 5-100 mm. The invention comprehensively considers the factors of the motor efficiency, the manufacturing cost, the temperature rise condition, the insulation grade, the wire material and the like, reasonably sets various parameters of the stator and the rotor, and the parameters are mutually related, thereby increasing the motor efficiency and improving the motor performance.

Description

Electric machine

Technical Field

The invention relates to the field of electromagnetic design of motors, in particular to a motor.

Background

The excellent motor design needs to meet the product specifications (such as power, voltage, rotating speed and the like) and the technical requirements (such as efficiency, parameters, temperature rise limit, mechanical reliability requirements and the like), and conforms to the national policy and production actual conditions in the aspect of technical economy. The design of the motor is a complex process, factors needing to be considered and determined sizes and data are large, and contradictions often exist among various performances of the motor and between technical indexes and economic indexes. When measures are taken to improve certain performance, other performance is often degraded and must be taken care of in full. The motor products on the market usually have design contradiction, and the parameter setting is unreasonable, can not compromise performance, reliability and economic nature of motor.

Disclosure of Invention

The present invention is directed to overcoming at least one of the disadvantages of the prior art described above and to providing an electric machine.

The technical scheme adopted by the invention is as follows: an electric machine comprising a stator and a rotor, the number of pole pairs of the machine being 10; the stator comprises a circular hollow iron core, a stator winding and a magnet; the inner diameter of the round hollow iron core is 10-90mm, the outer diameter is 150mm, the yoke height is 35mm, and 18 winding slots extending inwards are uniformly distributed on the circumference of the round hollow iron core; the stator winding is in a double-layer winding type, the pitch is 1, the number of parallel circuits is 1, the wire diameter is 0.2-0.8mm, and the number of turns of each coil is 80-300; the thickness of the magnet is 2.6mm, and the height of the magnet is 10-100 mm; the inner diameter of the rotor is 156.7mm, and the height of the yoke is 5-100 mm.

The motor is a 10-pole motor, is a small motor and has a rated voltage of 220V. The inner diameter of the circular hollow iron core is 90mm, the outer diameter of the circular hollow iron core is 150mm, the height of the yoke is 35mm, the air gap is smaller on the premise of meeting the electromagnetic load, no-load current is reduced to improve the power factor, and meanwhile, the air gap is not too small to influence the mechanical reliability of the motor and cause high temperature rise and larger noise of the motor. The rotor is sized to match the stator with an inner diameter of 156.7mm and a yoke height greater than 35 mm. The circumference of the round hollow iron core is uniformly distributed with 18 winding slots extending inwards, the number of slots of the round hollow iron core is increased as much as possible, good electrical performance of the motor is ensured, the magnetomotive force waveform of the motor is closer to a sine wave, motor loss caused by a harmonic magnetic field and harmonics is reduced, the total heat dissipation area of a coil edge in the slots is increased, and heat dissipation is facilitated; meanwhile, in the prior art, the slot processing of the circular hollow iron core can be realized at the size level, the consumption of insulating materials and processing time are increased due to the large number of the slots of the balanced stator, the manufacturing cost of the motor is increased, the processing difficulty is increased, the slot utilization rate is reduced, and the like.

The stator winding is in a double-layer winding form, the favorable pitch can be selected to improve the magnetic potential and the electric potential waveform, the electric performance of the motor is improved, and the coil size is the same, so that the manufacturing is convenient. The number of slots (distance) spanned between the two effective sides of a coil, called the pitch, is adapted to the dimensions of the circular hollow core and guarantees the electrical performance, the pitch of the stator winding being 1. The number of turns of each coil of the stator winding is determined to be 205 according to the inner diameter of the stator and the linear load of the motor, so that the efficiency of the motor is ensured. The method is characterized in that factors such as the efficiency, the manufacturing cost, the service life, the heat dissipation condition, the insulation grade, the wire material and the like of the motor are comprehensively considered, the number of parallel circuits of the stator winding is determined to be 1, the wire diameter is further determined to be 0.58mm, the current density is controlled in a proper range, and materials and cost are saved as far as possible on the premise of improving the efficiency, reducing the loss and reducing the temperature rise. The slot filling rate is the ratio of the cross sectional area occupied by the copper wires in the winding slots of the round hollow iron core to the total amount of available space in the bare slots, is 66-75%, the higher slot filling rate can reduce the area of the winding slots and is beneficial to the heat dissipation of the wires in the winding slots, but brings difficulty to wire embedding and increases the wire embedding working hours, insulation loss is easily caused during wire embedding, and the slot filling rate is preferably controlled to be 66-75%.

Preferably, the inner diameter of the circular hollow iron core is 90 mm; the wire diameter of the stator winding is 0.58mm, and the number of turns of each coil is 205; the height of the magnet is 40 mm; the yoke height of the rotor is 35 mm.

Further, the rotating speed of the motor is 0-250rpm under the working conditions that the output torque is the rated torque and the current is the rated current.

Under the working conditions that the output torque is rated torque and the current is rated current, the rotating speed of the motor is adjusted within 0-250rpm, and good efficiency and power factors are kept.

Or the inner diameter of the round hollow iron core is 50 mm; the wire diameter of the stator winding is 0.2mm, and the number of turns of each coil is 190; the height of the magnet is 60 mm; the yoke height of the rotor is 35 mm.

Further, the lamination coefficient of the round hollow iron core is larger than 0.97.

The lamination coefficient is the ratio of the actual volume of the magnetic material part contained in the motor to the total volume of the iron core, and in the lamination process of the silicon steel sheets, due to reasons of flatness, shearing burrs, coatings and the like, the effective sectional area of the actual magnetic material part of the circular hollow iron core is smaller than the geometric sectional area, the lamination coefficient of the circular hollow iron core is larger than 0.97, the processing flatness of the circular hollow iron core of the stator is guaranteed, and the influences of power factor reduction, copper consumption increase and temperature rise increase caused by the burrs are reduced.

Further, the winding groove is a trapezoidal groove.

The trapezoidal groove is one of the semi-closed grooves, and the semi-closed groove can reduce the intra-tooth pulse vibration loss of the surface loss of the round hollow iron core, reduce the effective air gap length and improve the power factor.

Further, the surface of the stator winding is provided with a coating layer so as to further increase the insulation performance of the stator winding.

Further, the round hollow iron core is 50w470 in number.

50w470 is the general grade of silicon steel, and can reach the iron loss and high magnetic flux density through annealing treatment. The motor has not only magnetic properties but also high plate thickness accuracy and coating properties, and can satisfy the processing characteristics of the motor.

Further, the magnet is under the brand name of N38 or N38H.

Furthermore, the rotor is made of magnetic conductive steel with the grade within 45.

Compared with the prior art, the invention has the beneficial effects that: the efficiency of the motor, the manufacturing cost, the temperature rise condition, the insulation grade, the wire material and other factors are comprehensively considered, various parameters of the stator and the rotor are reasonably set, the parameters are correlated, the efficiency of the motor is increased, and the performance of the motor is improved.

Drawings

Fig. 1 is a schematic view of a stator structure according to embodiment 1 of the present invention.

Fig. 2 is a phase diagram of example 1 of the present invention.

FIG. 3 shows design criteria of example 1 of the present invention.

Fig. 4 is a motor efficiency distribution diagram of embodiment 1 of the present invention.

Fig. 5 is a graph of the no-load line back emf of embodiment 1 of the present invention.

Fig. 6 is a graph showing the amplitude of the fundamental wave in embodiment 1 of the present invention.

Fig. 7 is a cogging torque graph of embodiment 1 of the present invention.

Fig. 8 is a power factor distribution diagram of embodiment 1 of the present invention.

Fig. 9 is a no-load magnetic field distribution diagram of embodiment 1 of the present invention.

Fig. 10 is a schematic diagram of maximum current demagnetization verification in embodiment 1 of the present invention.

Fig. 11 is a temperature field profile of example 1 of the present invention.

Fig. 12 is a parameter summary diagram of the circular hollow core according to embodiment 1 of the present invention.

Fig. 13 is a stator winding parameter summary diagram of embodiment 1 of the present invention.

Fig. 14 is a load parameter summary diagram according to embodiment 1 of the present invention.

Fig. 15 is a motor current distribution diagram of embodiment 1 of the present invention.

Fig. 16 is a motor power distribution diagram of embodiment 1 of the present invention.

Fig. 17 is a line inductance curve comparison diagram of example 1 of the present invention.

Fig. 18 is a load torque graph of embodiment 1 of the present invention.

Fig. 19 is a direct axis inductance distribution diagram of embodiment 1 of the present invention.

Fig. 20 is a cross-axis inductance distribution diagram according to embodiment 1 of the present invention.

Fig. 21 is a straight-axis current distribution diagram of embodiment 1 of the present invention.

Fig. 22 is a cross-axis inductance distribution diagram according to embodiment 1 of the present invention.

Fig. 23 is a direct axis voltage distribution diagram of embodiment 1 of the present invention.

Fig. 24 is a cross-axis inductance distribution diagram according to embodiment 1 of the present invention.

Fig. 25 is a direct axis electric flux distribution diagram of embodiment 1 of the present invention.

Fig. 26 is a cross-axis electric flux distribution diagram of embodiment 1 of the present invention.

Fig. 27 is a lead angle distribution diagram according to example 1 of the present invention.

FIG. 28 is a chart of design input parameter ranges for the present invention.

FIG. 29 is a summary of the load parameter ranges of the present invention.

Detailed Description

The drawings are only for purposes of illustration and are not to be construed as limiting the invention. For a better understanding of the following embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

Example 1

As shown in fig. 1-2, the present embodiment provides a motor, which includes a stator and a rotor, and the number of pole pairs of the motor is 10; the stator comprises a stator winding, a round hollow iron core and a magnet; the inner diameter of the round hollow iron core is 90mm, the outer diameter of the round hollow iron core is 150mm, the yoke height is 35mm, the lamination coefficient is greater than 0.97, and 18 winding slots extending inwards are uniformly distributed on the circumference of the round hollow iron core; the stator winding is in a double-layer winding type, the pitch is 1, the number of parallel circuits is 1, the wire diameter is 0.58mm, and the number of turns of each coil is 205; the thickness of the magnet is 2.6mm, and the height of the magnet is 35 mm; the rotor has an inner diameter of 156.7mm and the yoke height is greater than 35 mm.

The motor of the embodiment is a 10-pole motor, is a small motor and has a rated voltage of 220V. The inner diameter of the circular hollow iron core is 90mm, the outer diameter of the circular hollow iron core is 150mm, the height of the yoke is 35mm, the air gap is smaller on the premise of meeting the electromagnetic load, no-load current is reduced to improve the power factor, and meanwhile, the air gap is not too small to influence the mechanical reliability of the motor and cause high temperature rise and larger noise of the motor. The circumference of the round hollow iron core is uniformly distributed with 18 winding slots extending inwards, the number of slots of the round hollow iron core is increased as much as possible, good electrical performance of the motor is ensured, the magnetomotive force waveform of the motor is closer to a sine wave, motor loss caused by a harmonic magnetic field and harmonics is reduced, the total heat dissipation area of a coil edge in the slots is increased, and heat dissipation is facilitated; meanwhile, in the prior art, the slot processing of the circular hollow iron core can be realized at the size level, the consumption of insulating materials and processing time are increased due to the large number of the slots of the balanced stator, the manufacturing cost of the motor is increased, the processing difficulty is increased, the slot utilization rate is reduced, and the like.

Preferably, the lamination coefficient of the circular hollow core of the present embodiment is greater than 0.97.

Preferably, the winding groove of the present embodiment is a trapezoidal groove.

Preferably, the surface of the stator winding of the present embodiment is provided with a coating layer to further increase the insulation performance of the stator winding.

Preferably, the round hollow core of the present embodiment has a designation of 50w 470.

Preferably, the motor of the embodiment has a rotation speed of 0-250rpm under the condition that the output torque is the rated torque and the current is the rated current.

Specifically, as shown in fig. 3, the standard technical parameters of the present embodiment include bus voltage: 220V, rated power: 300W, rated rotating speed: 200rpm, working system: and S1. The circular hollow core of the stator has a skewed angle of 0 DEG and a weight of 1.69 kg. The stator winding adopts a Y connection method and adopts flying fork winding, and the weight is 0.89 kg. The wire resistance of the stator winding at 20 ℃ is about 18.2R, and the wire inductance is 162.8 mh. The thickness of the rotor is more than 4.5mm, the inner diameter is 156.7mm, the mark is within 45 magnetic conduction steel, and the height is more than 35 mm. The magnet had a thickness of 2.6mm, a designation of N38 or N38H, a height of 40mm and a weight of 0.263 kg.

Efficiency is an important performance indicator of an electric machine, and it is highly dependent on the losses generated in the electric machine during operation, the higher the losses, the lower the efficiency. The size of the loss is closely related to the parameters of the stator and the rotor, and the size, the material performance and the winding type of the stator winding of the circular hollow iron core of the stator are all closely related to the loss. Wherein the losses include no-load parasitic losses of the core. The no-load additional loss of the core is mainly the surface loss of the circular hollow core and the pulse vibration loss in the teeth, which is caused by the harmonic magnetic field in the air gap. These harmonic magnetic fields can be caused by two reasons: the slotting of the motor iron core causes the uneven magnetic conductance of an air gap and harmonic waves exist in a space distribution curve of no-load excitation magnetic potential. When the harmonic magnetic field moves relative to the magnetic pole surface, eddy currents are induced on the pole face, and eddy current loss is generated. Harmonic magnetic fields move relative to the pole faces and also cause hysteresis losses therein. Eddy current has a weakening effect on a magnetic field, eddy current loss and laminated magnetic pole loss are closely related to the number of slots of a stator, tooth harmonic flux density amplitude is caused by slotting of the stator, the number of the slots of the circular hollow iron core of the embodiment is 18, and in combination with other sizes of the stator and a rotor, as shown in fig. 5-6, fig. 5 is a no-load line back electromotive force curve diagram of the embodiment, fig. 6 is a fundamental wave amplitude curve diagram of the embodiment, the effective value of the no-load line back electromotive force of a motor at a rotating speed of 200rpm is 130.07V, the amplitude is 182V, after the motor is finished, the detected fundamental wave amplitude is 183.9, other harmonics are extremely few, the no-load additional loss of the iron core is greatly reduced, and the efficiency is improved. On the other hand, the harmonic wave rarely avoids the phenomena of overheating, insulation aging and damage caused by shortened service life of the lead, and the reliability of the motor is ensured. Furthermore, in the embodiment, the material with the trade mark of 50w470 is selected as the manufacturing material of the circular hollow iron core, so that the hysteresis loss caused by alternating magnetization in the ferromagnetic substance per unit weight is reduced. FIG. 4 is a motor efficiency distribution diagram of the present embodiment, where the motor efficiency reaches 88.28% under the conditions of 249.85rpm and 10.94N/m torque, and the efficiency can be ensured to be more than 75% between 200rpm and 300 rpm.

Cogging torque is the torque produced by the interaction between the magnets and the stator core when the permanent magnet motor windings are not energized, and is caused by the tangential component of the interaction force between the permanent magnets and the armature teeth. The cogging torque can cause the motor to generate vibration and noise, and the rotating speed fluctuation occurs, so that the motor cannot run stably, and the performance of the motor is influenced. In variable speed drives, the vibrations and noise generated by cogging torque will be amplified when the torque ripple frequency coincides with the mechanical resonance frequency of the stator or rotor. The existence of the cogging torque also affects the low-speed performance of the motor in a speed control system and the high-precision positioning in a position control system, fig. 7 is a cogging torque curve chart of the embodiment, the cogging torque of the embodiment is 0.302N/m and accounts for 2.1% of the rated torque through the parameter setting of the stator, and the noise of the motor meets the application requirement.

The level of the power factor of the motor is directly related to the magnitude of the reactive component of the stator current. If the power factor is too low, the indexes specified in the technical conditions cannot be met, and the reactive component of the stator current is related to the area of the stator and the rotor slots, the magnetic density of each part, the air gap, the number of conductors in each slot and the inner diameter of the stator, so that the power factor needs to be improved and the parameters need to be balanced. Fig. 8 is a power factor distribution diagram of the present embodiment, where the power factor of the motor at the rated rotation speed can reach 99.04%, and meets the index requirement specified in the technical condition.

Fig. 9 is a no-load magnetic field distribution diagram of the present embodiment, it can be seen that a part of magnetic lines of force between winding slots of the stator are the most dense, the magnetic lines of force are reasonably distributed, and the magnetic leakage is less, and as shown in fig. 10, under the action of 6Arms direct axis current, the coercive force of the magnetic steel is locally 600KA/m, the maximum current is demagnetized and checked, and the motor is safe.

When the motor normally runs under a certain capacity, the temperature rise of the motor is certain, the temperature rise cannot exceed the limit value allowed by the standard, and the necessary margin is considered. The temperature rise of the motor is directly related to loss, the loss is converted into heat energy in the running process, the temperature of each part of the motor is increased, and the difference between the temperature of a certain part of the motor and the temperature of a surrounding medium is the temperature rise of the part. Thus, the parameter affecting the loss is also the parameter affecting the temperature rise. Fig. 11 is a temperature field distribution diagram of the embodiment, when the environmental temperature of the motor is 30 ℃, the rated output is 14.32Nm, the motor continuously operates at 200rpm, the winding temperature is 85.5 ℃, the magnetic steel temperature is 60.1 ℃, the shell is 58.5 ℃, the winding temperature rise is 55.5K, and the motor temperature rise is reasonable.

In the embodiment, various factors such as motor efficiency, manufacturing cost, service life, temperature rise conditions, insulation grade and lead materials are comprehensively considered, various parameters of the stator and the rotor are reasonably set, the parameters are correlated, the motor efficiency is improved, the motor performance is improved, and the reliability parameters such as motor noise and temperature rise are ensured to meet the standard. The parameters of the motor provided by the embodiment are shown in detail in fig. 12-27.

Example 2

The present embodiment differs from embodiment 1 in the partial dimensions of the stator and rotor: the circular hollow core of this embodiment has an inner diameter of 50mm, a wire diameter of a stator winding of 0.2mm, a number of turns of each coil of 19, a height of a magnet of 60mm, and a yoke height of a rotor of 35 mm.

The design input parameters of the embodiment are different from those of the embodiment 1, so that the partial sizes of the stator and the rotor are different from those of the embodiment 1, but the various factors such as the motor efficiency, the manufacturing cost, the service life, the temperature rise condition, the insulation grade, the wire material and the like are also considered, various parameters of the stator and the rotor are reasonably set, the parameters are correlated with each other, the motor efficiency is increased, the motor performance is improved, and the reliability parameters such as the motor noise and the temperature rise are ensured to meet the standard.

The design input index of other embodiments is shown in fig. 28, and different load parameters are obtained according to different design input indexes is shown in fig. 29.

It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the technical solutions of the present invention, and are not intended to limit the specific embodiments of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention claims should be included in the protection scope of the present invention claims.

Claims

1. An electric machine comprising a stator and a rotor, characterized in that,

the number of pole pairs of the motor is 10;

the stator comprises a circular hollow iron core, a stator winding and a magnet;

the inner diameter of the round hollow iron core is 10-90mm, the outer diameter is 150mm, the yoke height is 35mm, and 18 winding slots extending inwards are uniformly distributed on the circumference of the round hollow iron core;

the stator winding is in a double-layer winding type, the pitch is 1, the number of parallel circuits is 1, the wire diameter is 0.2-0.8mm, and the number of turns of each coil is 80-300;

the thickness of the magnet is 2.6mm, and the height of the magnet is 10-100 mm;

the inner diameter of the rotor is 156.7mm, and the height of the yoke is 5-100 mm.

2. An electric machine according to claim 1,

the inner diameter of the round hollow iron core is 90 mm;

the wire diameter of the stator winding is 0.58mm, and the number of turns of each coil is 205;

the height of the magnet is 40 mm;

the yoke height of the rotor is 35 mm.

3. An electric machine according to claim 2,

the motor rotates at 0-250rpm under the working conditions that the output torque is rated torque and the current is rated current.

4. An electric machine according to claim 1,

the inner diameter of the round hollow iron core is 50 mm;

the wire diameter of the stator winding is 0.2mm, and the number of turns of each coil is 190;

the height of the magnet is 60 mm;

the yoke height of the rotor is 35 mm.

5. An electric machine according to claim 1,

the lamination coefficient of the round hollow iron core is more than 0.97.

6. An electric machine according to claim 1,

the winding groove is a trapezoidal groove.

7. An electric machine according to claim 1,

the surface of the stator winding is uniformly coated.

8. An electric machine according to claim 1,

the round hollow iron core is 50w470 in number.

9. An electric machine according to claim 1,

the magnet is of the brand number N38 or N38H.

10. An electric machine according to claim 1,

the rotor is made of magnetic conductive steel with the grade within 45.