CN205681272U - Straight tiltedly compound stator winding slotless electric machines for artificial heart pump - Google Patents

Abstract

The utility model discloses a straight-inclined composite stator winding slotless motor used for an artificial heart pump, which comprises: a rotating shaft located in the center, a rotor permanent magnet surrounding the outer side of the rotating shaft in sequence from inside to outside, a straight-inclined composite winding and a stator iron core; an air gap is formed between the permanent magnet of the rotor and the straight-inclined composite winding; the edge of the straight-inclined composite winding is flush with the edge of the stator core. The utility model has beneficial effects: after adopting the straight-inclined composite winding, the electromagnetic torque of the motor increases, and the harmonic winding coefficient decreases. The stator structure is simple, compared with the traditional motor structure, the stator becomes a slotless structure, the processing is relatively simple, the cogging torque is eliminated, and the copper loss is reduced.

Description

Straight inclined compound stator winding slotless motor for artificial heart pump

technical field

The utility model belongs to the technical field of artificial heart pumps, in particular to a slotless motor with straight-inclined composite stator windings for artificial heart pumps.

Background technique

Artificial heart pump, also known as blood pump, is a mechanical pump device that partially or completely replaces the heart's blood pumping function, and has broad clinical application prospects. The driving motor is an important part of the artificial heart pump, and its characteristics directly determine the performance of the artificial heart pump. Compared with traditional motors, artificial heart pump drive motors are required to reduce volume, reduce noise, and improve operating performance on the basis of meeting high reliability and high stability. The permanent magnet brushless DC motor has a series of advantages such as high power density, small geometric size, fast dynamic response, and high operating efficiency. It has broad application prospects in high-speed operating occasions and has been widely used in the drive of artificial heart pumps.

The stator of the traditional permanent magnet brushless DC motor has a cogged structure, and the torque ripple is relatively large. The existence of torque ripple will lead to vibration and noise, affecting the control accuracy of the system, especially in high-speed motors, the impact of torque ripple is more serious. The torque ripple of the permanent magnet brushless DC motor mainly comes from its harmonic torque, which includes cogging torque and ripple torque. The former is generated by the interaction between the stator core and the rotor permanent magnet, which is caused by the change of the iron core reluctance caused by the existence of the stator cogging; the latter is caused by the deviation of the armature current waveform and the induced electromotive force waveform. Although there are ways to weaken the torque ripple, it cannot be completely eliminated.

In addition, the length of the rotor of the permanent magnet brushless DC motor with cogging is equal to the length of the vertical part of the winding, and the winding end of the coil is placed outside the edge of the stator, which has a large thickness and occupies axial space, and cannot effectively use the winding end The internal part increases the magnetic flux leakage and copper loss of the motor, and reduces the rotational torque and efficiency of the motor.

The winding distribution of traditional motors is divided into two types: straight winding and oblique winding. The motor harmonic winding coefficient of the straight winding is higher, and the oblique winding distribution can reduce the harmonic winding coefficient.

The heating problem of the artificial heart pump motor will affect the efficiency of the motor and the life safety of the patient. Therefore, how to reduce the heat generation and improve the efficiency of the motor is the focus of the development of the artificial heart pump motor.

Utility model content

The purpose of this utility model is to solve the above problems and provide a slotless motor with straight-inclined composite stator windings for artificial heart pumps. At the same time of pulsation, the harmonic current is reduced to a certain extent, and the rotational torque and efficiency of the motor are improved.

In order to achieve the above object, the utility model adopts the following technical solutions:

A slotless motor with straight-inclined composite stator windings for artificial heart pumps, comprising: a rotating shaft located at the center, a rotor permanent magnet surrounding the outside of the rotating shaft in sequence from the inside to the outside, a straight-inclined composite winding and a stator core; the stator The inner surface of the iron core has no cogging structure, and the straight-inclined compound winding is arranged between the rotor permanent magnet and the stator core; an air gap is formed between the rotor permanent magnet and the straight-inclined compound winding; the straight-inclined compound winding The edge is flush with the edge of the stator core.

Further, the straight-inclined composite winding includes A, B, and C three-phase windings wound along the ring; each phase winding is divided into three parts along the axial direction: the upper and lower ends of the winding are respectively obliquely wound along the axial direction The oblique winding part, the middle part of the winding is the straight winding part.

Further, in the three-phase windings of A, B, and C, the inclination direction angle α of the windings wound obliquely along the axial direction at the upper and lower ends of each phase winding satisfies:

$\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}}$

$\frac{\mathrm{<span\; class="notranslate">\; d</span>}}{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&pi;r</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}$

Among them, α is the angle between the oblique winding and the horizontal direction, 0°<α<90°; L is the axial length of the winding; l _q is the length of the oblique winding; l _s is the length of the straight winding; D is the single-turn diameter of the winding; is the horizontal length of a single turn of the oblique winding; N is the total number of turns of a layer of winding; r _in is the inner radius of the coil.

Further, the particle swarm optimization algorithm is used to optimize the inclination direction angle α of the windings whose upper and lower ends of each phase winding are obliquely wound along the axial direction.

Further, the oblique winding part of the straight oblique composite winding is arranged regularly, and the length of the permanent magnet of the rotor is longer than that of the straight winding part.

Further, the A, B, and C three-phase windings are symmetrically and evenly distributed into two layers, each turn of the coil spans a pole pitch, each layer and each phase winding occupies an angle of 120°, and the winding connection mode is a star connection.

Further, the rotor permanent magnet is made of NdFeB permanent magnet material, radially magnetized, composed of a single magnet, or spliced by a plurality of magnets, and has a one-pole or multi-pole structure.

Further, the outside of the permanent magnet of the rotor is wrapped by non-magnetic medical titanium alloy, and there is an impeller outside the titanium alloy shell, which can drive blood to flow axially when rotating; the inside of the stator coil is provided with a medical titanium alloy inner shell; the titanium alloy The outer shell and titanium alloy inner shell can reduce the higher harmonics of the air gap magnetic field and reduce the eddy current loss of the permanent magnet of the rotor.

Further, the stator core is formed by stacking silicon steel sheets.

The beneficial effects of the utility model are:

(1) After using straight-inclined composite windings, the electromagnetic torque and efficiency of the motor increase, and the harmonic current decreases.

(2) The structure of the stator core is simple. Compared with the structure of the traditional motor, the stator becomes a slotless structure, the processing is relatively simple, and the torque ripple is eliminated.

(3) The electromagnetic torque and harmonic winding coefficient of the motor can be adjusted by changing the proportion of the oblique winding part and the straight winding part of the winding.

(5) The use of straight-inclined composite windings effectively suppresses the torque ripple of the motor, weakens vibration and noise, improves the control accuracy of the artificial heart pump system, and is conducive to the stable operation of the artificial heart pump.

(6) Optimizing the motor structure through the particle swarm optimization algorithm can design the optimal oblique winding inclination angle, so that the motor efficiency can be maximized, the harmonic suppression rate can be effectively improved, and the heat generation of the heart pump can be reduced.

Description of drawings

Fig. 1 is the radial sectional view of the straight-inclined compound stator winding slotless motor of the utility model used in an artificial heart pump;

Fig. 2 is a structural schematic diagram of a straight-inclined compound stator winding slotless motor for an artificial heart pump of the present invention;

Fig. 3 is the working principle of the straight-inclined composite stator winding slotless motor used in the artificial heart pump of the present invention;

Figure 4 is the no-load back electromotive force waveform of the three-phase winding;

Fig. 5 is a schematic diagram of the structure of the straight-inclined composite stator winding of the present invention.

Among them, 1. Stator core, 2. Straight-inclined compound winding, 3. Air gap, 4. Rotor permanent magnet, 5. Rotating shaft, 6. Motor casing.

detailed description:

Below in conjunction with accompanying drawing and example the utility model is described further:

As shown in Figures 1 and 2, a slotless motor with straight-inclined composite stator windings for artificial heart pumps includes: a stator core 1, a straight-inclined composite winding 2, a rotor permanent magnet 4, and a rotating shaft 5; the rotating shaft 5 is located at The central position, from the inside to the outside, is the rotating shaft 5, the rotor permanent magnet 4, the straight and inclined composite stator winding and the stator core 1; the motor air gap 3 is formed between the rotor permanent magnet 4 and the straight and inclined composite winding 2; the straight and inclined composite The winding 2 is interposed between the stator and the rotor, and the edge of the straight-inclined composite winding 2 is flush with the edge of the stator core 1 . The stator core 1 is formed by stacking silicon steel sheets, the rotor permanent magnet 4 is made of NdFeB permanent magnet material, and is radially magnetized, and the stator core 1 has a structure without cogging.

Figure 3 is a schematic diagram of the working principle of the motor of the present invention. The rotor position detection device detects the position of the motor rotor through the back electromotive force method, and sends the signal to the controller. The controller controls the inverter switch to conduct according to the feedback signal, and accordingly controls the three motor The conduction state of the phase winding forms a pulsating rotating magnetic field, which makes the motor generate electromagnetic torque, thereby driving the motor rotor to rotate. The driving motor of the artificial heart pump adopts the operation mode of two-phase conduction star three-phase six-state.

For the winding of a traditional motor, the length of the rotor is equal to the length of the vertical part of the winding, and the ends of the winding are arranged outside the edge of the rotor.

For the straight-slant composite winding 2, the edge of the winding end is flush with the edge of the stator, the inclined part of the winding is arranged regularly, and the length of the rotor is longer than the vertical part of the winding. The use of the oblique winding at the end of the straight oblique composite winding 2 increases the effective length of the conductor, which increases the electromotive force of the motor; the regular arrangement of the oblique winding at the end reduces the thickness of the coil, and the air gap between the stator core 1 and the rotor permanent magnet 4 3 is reduced, and the magnetic induction intensity of the air gap 3 is increased; the oblique winding part can effectively suppress high-order harmonics, thereby weakening the torque ripple. The electromagnetic torque of the motor increases and the harmonic winding coefficient decreases. In addition, the stator core 1 with no cogging structure with straight-inclined composite windings 2 eliminates cogging torque and reduces copper loss.

For the motor using the straight-inclined composite winding 2, the use of the winding end increases the effective length of the conductor, which increases the electromotive force of the motor; the regular arrangement of the end windings reduces the thickness of the coil; the stator core 1 has a slotless structure, fundamentally The cogging torque is eliminated; the oblique winding part can effectively suppress high-order harmonics, so that the motor can run smoothly. Electromotive force and air gap 3 increase the magnetic induction intensity, and the electromagnetic torque of the motor increases. At the same time, the reluctance torque of the non-cogging motor is small, and it has a high positioning torque, which can effectively suppress the torque ripple of the motor and make the operation more stable. .

Figure 4 shows the no-load back electromotive force waveforms of the three-phase windings. The waveforms have good sine, and the Fourier analysis shows that the harmonic amplitudes are low, which verifies the effectiveness of the motor design of the present invention.

The suppression of high-order harmonics is beneficial to reduce the stray loss of the motor, improve efficiency, and reduce temperature rise, which reflects the advantages of straight-inclined composite winding 2.

According to the magnetic flux density distribution of the air gap 3 in the inner layer and the outer layer of the straight-inclined composite winding 2, it can be concluded that the magnetic flux density of the air gap 3 in the inner layer of the winding is obviously greater than that in the outer layer. It can be seen that different radii The magnetic density of the air gap 3 is different; the waveform is a good sine wave, and the structure without cogging effectively weakens the high-frequency harmonics of the air gap 3 magnetic field caused by the armature reaction, and also eliminates the high frequency harmonics caused by the slotting of the stator. Tooth harmonics in the air-gap 3 magnetic field.

The straight-inclined composite winding 2 has the property of the inclined slot motor. When the rotor is larger than the vertical part of the coil, the inclined part of the winding is utilized, which can significantly reduce some harmonic winding coefficients. Compared with the inclined slot motor, due to the straight winding part Exist, make the motor more efficient and have more torque.

The stator has a non-cogging structure, which increases the space for placing the winding. In the case of the same number of winding turns, the non-cogging structure can use a wire with a larger diameter to reduce the winding resistance. Therefore, the copper consumption of the non-cogging structure motor is lower. Smaller than motors with cogged structure.

FIG. 5 is a schematic structural diagram of the straight-inclined composite winding 2 of the driving motor of the artificial heart pump, and the edge of the winding is flush with the edge of the stator core 1 . Straight oblique compound winding 2 is composed of three-phase windings A, B, and C. The three-phase windings are symmetrically and evenly distributed into two layers. Each turn of the coil spans a pole pitch, and each layer and each phase winding occupy a space angle of 120°. The three-phase winding can be divided into three parts along the axial direction: the upper and lower windings are oblique winding parts, and the middle winding is straight winding part. The inclined winding part of the A, B, and C three-phase windings is the same as the axial angle α, and the inclination direction of the upper winding and the lower winding is opposite. By adjusting the inclination angle α, the proportion of oblique winding and straight winding in each phase winding can be adjusted.

In the three-phase windings A, B, and C, the inclination direction angle α of the windings wound axially at the upper and lower ends of each phase winding satisfies:

$\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

$\frac{\mathrm{<span\; class="notranslate">\; d</span>}}{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&pi;r</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Among them, α is the angle between the oblique winding and the horizontal direction, 0°<α<90°; L is the axial length of the winding; l _q is the length of the oblique winding; l _s is the length of the straight winding; D is the single-turn diameter of the winding; is the horizontal length of a single turn of the oblique winding; N is the total number of turns of a layer of winding; r _in is the inner radius of the coil.

The particle swarm optimization algorithm is used to optimize the inclination direction angle α of the windings whose upper and lower ends of each phase winding are obliquely wound along the axial direction, so that the optimal winding structure parameters can be obtained.

Under the condition that the angle α satisfies formula (1) and formula (2), the angle α is optimized, and the optimization steps are as follows:

(1) Use the particle swarm optimization algorithm to calculate the optimal angle α under the condition of the initial temperature, and calculate the straight-inclined compound winding 2-stator slotless motor.

(2) Establish the finite element calculation model of the motor magnetic field in the finite element simulation software, set the structural parameters of the motor, including the included angle α, run the finite element simulation program, and analyze the load characteristics of the motor's no-load characteristics, specifically including the air gap 3 Magnetic field, back EMF waveform, torque waveform at rated speed;

(3) Combined with the finite element simulation results, calculate the motor loss, including rotor eddy current loss, stator copper loss, stator eddy current loss, etc.;

(4) Establish a temperature field model based on the motor electromagnetic field model, conduct heat generation analysis, input motor material thermal parameters, boundary conditions, ambient temperature, blood flow field temperature, flow velocity and other parameters, and obtain the motor temperature field analysis results according to the following procedure.

(5) Using the parameters of rotor surface temperature, stator inner temperature, and motor casing 6 temperature parameters as feedback, update the parameters of the particle swarm optimization algorithm, repeat the algorithm, and end when the difference between the two iterations reaches the expected value after several iterations, thus obtaining The best included angle α.

Although the specific implementation of the utility model has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the utility model. Those skilled in the art should understand that on the basis of the technical solution of the utility model, those skilled in the art do not need to Various modifications or deformations that can be made with creative efforts are still within the protection scope of the present utility model.

Claims (8)

1. A straight-inclined composite stator winding slotless motor for artificial heart pumps, characterized in that it comprises: a rotating shaft positioned at the center, a rotor permanent magnet, a straight-inclined composite winding and a stator that surround the rotating shaft outside successively from the inside to the outside Iron core; the inner surface of the stator core is a structure without cogging, and the straight-inclined compound winding is arranged between the rotor permanent magnet and the stator core; an air gap is formed between the rotor permanent magnet and the straight-inclined compound winding; The edges of the straight-inclined composite winding are flush with the edges of the stator core. 2. A kind of slotless motor with straight-inclined compound stator windings for artificial heart pumps as claimed in claim 1, wherein said straight-inclined compound windings comprise A, B, and C three-phase windings wound along the ring ; Each phase winding is divided into three parts along the axial direction: the upper and lower ends of the winding are oblique winding parts which are wound obliquely along the axial direction, and the middle part of the winding is a straight winding part. 3. A straight-inclined compound stator winding slotless motor for artificial heart pumps as claimed in claim 2, characterized in that, in the three-phase windings of A, B, and C, the upper and lower ends of each phase winding are The tilt direction angle α of the axially tilted winding satisfies: Among them, α is the angle between the oblique winding and the horizontal direction, 0°<α<90°; L is the axial length of the winding; l _q is the length of the oblique winding; l _s is the length of the straight winding; D is the single-turn diameter of the winding; is the horizontal length of a single turn of the oblique winding; N is the total number of turns of a layer of winding; r _in is the inner radius of the coil. 4. A kind of slotless motor with straight-inclined composite stator windings for artificial heart pumps as claimed in claim 3, characterized in that, the upper and lower ends of each phase winding are obliquely wound in the axial direction by using the particle swarm optimization algorithm. The inclination direction angle α of the winding is optimized. 5. A kind of slotless motor with straight-inclined composite stator windings for artificial heart pumps as claimed in claim 2, characterized in that, the oblique windings of said straight-inclined composite windings are arranged regularly, and the length of the permanent magnets of the rotor is longer than that of the straight-inclined composite windings. The length of the winding section. 6. A straight-inclined compound stator winding slotless motor for artificial heart pumps as claimed in claim 2, wherein the A, B, and C three-phase windings are symmetrically and evenly distributed into two layers, and each turn of the coil Across a pole pitch, the windings of each layer and phase occupy an angle of 120°, and the winding connection method is a star connection. 7. A straight-inclined compound stator winding slotless motor for artificial heart pumps as claimed in claim 1, wherein the permanent magnets of the rotor are NdFeB permanent magnet materials, magnetized radially, and composed of a single It is composed of magnets, or spliced by multiple magnets, and has a structure of one pair of poles or multiple pairs of poles. 8. A slotless motor with straight-inclined composite stator windings for artificial heart pumps as claimed in claim 1, wherein the permanent magnet of the rotor is wrapped by a non-magnetic medical titanium alloy, and an impeller is arranged outside the titanium alloy shell , which can drive blood to flow axially when rotating; the inner side of the stator coil is provided with a medical titanium alloy inner shell; the titanium alloy outer shell and titanium alloy inner shell can reduce the high-order harmonics of the air gap magnetic field and reduce the rotor permanent magnet eddy current loss.