CN113726114A - Double-stator permanent magnet synchronous motor for underwater vehicle - Google Patents

Double-stator permanent magnet synchronous motor for underwater vehicle Download PDF

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Publication number
CN113726114A
CN113726114A CN202110897637.5A CN202110897637A CN113726114A CN 113726114 A CN113726114 A CN 113726114A CN 202110897637 A CN202110897637 A CN 202110897637A CN 113726114 A CN113726114 A CN 113726114A
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rotor
permanent magnet
stator
motor
winding
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CN113726114B (en
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张继鹏
苏锦智
廖雪松
孙瑞杰
孙建国
王辉
徐英振
王飞
侯政良
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Baotou Chang'an Permanent Magnet Motor Co ltd
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Baotou Chang'an Permanent Magnet Motor Co ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K16/00—Machines with more than one rotor or stator
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K16/00—Machines with more than one rotor or stator
    • H02K16/04—Machines with one rotor and two stators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K21/00—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets
    • H02K21/12—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets
    • H02K21/14—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets with magnets rotating within the armatures
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K3/00—Details of windings
    • H02K3/04—Windings characterised by the conductor shape, form or construction, e.g. with bar conductors
    • H02K3/12—Windings characterised by the conductor shape, form or construction, e.g. with bar conductors arranged in slots
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K3/00—Details of windings
    • H02K3/04—Windings characterised by the conductor shape, form or construction, e.g. with bar conductors
    • H02K3/28—Layout of windings or of connections between windings
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K5/00—Casings; Enclosures; Supports
    • H02K5/02—Casings or enclosures characterised by the material thereof
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
    • H02P25/16—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the circuit arrangement or by the kind of wiring
    • H02P25/18—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the circuit arrangement or by the kind of wiring with arrangements for switching the windings, e.g. with mechanical switches or relays
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K2201/00—Specific aspects not provided for in the other groups of this subclass relating to the magnetic circuits
    • H02K2201/03—Machines characterised by aspects of the air-gap between rotor and stator
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K2213/00—Specific aspects, not otherwise provided for and not covered by codes H02K2201/00 - H02K2211/00
    • H02K2213/03—Machines characterised by numerical values, ranges, mathematical expressions or similar information

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Permanent Magnet Type Synchronous Machine (AREA)
  • Permanent Field Magnets Of Synchronous Machinery (AREA)

Abstract

The invention relates to a permanent magnet synchronous motor for an underwater vehicle. The motor of the present invention comprises: the permanent magnet motor comprises an outer stator, an inner stator, a permanent magnet rotor, a rotor shell and an end ring; the outer rotor and the inner rotor are concentrically arranged, are fixed relative to the space position and have the same groove number; the winding mode of armature windings in the outer rotor and the inner rotor is completely the same, and the armature windings are used for generating a traveling wave magnetic field in an air gap; the central axes of the outer rotor and the inner rotor are staggered, namely the axis of the groove in the inner rotor and the axis of the groove in the outer rotor are not completely overlapped, so that the traveling wave magnetic fields generated by the two sets of stator windings have position difference in the circumferential direction of the motor in space. The permanent magnet synchronous motor for underwater propulsion can reduce the harmonic content in an air gap magnetic field, inhibit the motor torque and solve the problems of low power torque density and low fault-tolerant rate in the existing motor for underwater propulsion on the basis of combining the advantages of the traditional permanent magnet synchronous motor.

Description

Double-stator permanent magnet synchronous motor for underwater vehicle
Technical Field
The invention relates to the technical field of underwater motors, in particular to a permanent magnet synchronous motor for an underwater vehicle.
Background
The ocean has significant development potential as an earth treasury with abundant and diverse non-renewable resources such as natural gas, petroleum, rare metals, and the like. The method has great significance for promoting national economic development, expanding rare resource reserves and establishing a resource-economic recyclable economic system by exploring, exploiting and reasonably utilizing precious marine resources. The underwater motor is used as a power part of a marine detection work propulsion device and is used as a technical core of an underwater propulsion system. However, unlike the traditional onshore motor, the underwater motor needs to work in a special marine environment with high voltage, low temperature and easy corrosion, and meanwhile, a built-in storage battery is used for supplying power, which puts higher requirements on the sealing property, the pressure resistance, the corrosion resistance, the temperature adaptability, especially the power density and the fault tolerance of the motor. Therefore, the research on the high-performance underwater propulsion motor meeting the conditions is a key problem to be solved urgently in the field of ocean exploration at the present stage.
Research institutions at home and abroad carry out a great deal of research on motors for propelling underwater vehicles. The current commonly used motors for underwater propulsion mainly comprise induction motors, permanent magnet direct current motors and permanent magnet synchronous motors. The induction motor has the advantages of complex structure, large volume, low motor power density, large starting current and low motor efficiency. The permanent magnet direct current motor has excellent low-speed performance and wider speed regulation range, but the motor of the type has larger volume, low reliability and poor system fault tolerance because of the existence of mechanisms such as a commutator, an electric brush and the like. The permanent magnet synchronous motor has the advantages of small size, high power density, high efficiency, small rotational inertia and the like, can more easily meet the requirements of the motor for underwater propulsion on high power density and small size, and has better development and research prospects. However, the traditional permanent magnet synchronous motor only adopts one set of stator winding and is crossed in fault tolerance, when faults such as turn-to-turn short circuit and single-phase open circuit occur in the winding, the motor cannot normally operate, in addition, large torque pulsation exists, large noise is generated in the operation process of an underwater vehicle, and the expansion of partial ocean exploration work is not facilitated.
Disclosure of Invention
The invention provides a double-stator permanent magnet synchronous motor for an underwater vehicle, aiming at solving the problems of low power torque density, low fault-tolerant rate and large power pulsation in the existing motor for underwater propulsion, and the invention provides the following technical scheme:
a permanent magnet synchronous motor for underwater vehicles, the motor comprising: the permanent magnet motor comprises an outer stator, an inner stator, a permanent magnet rotor, a rotor shell and an end ring;
the outer rotor and the inner rotor are concentrically arranged, are fixed relative to the space position and have the same groove number; the winding mode of armature windings in the outer rotor and the inner rotor is completely the same, and the armature windings are used for generating a traveling wave magnetic field in an air gap; the central axes of the outer rotor and the inner rotor are staggered, namely the axis of the groove in the inner rotor is not completely superposed with the axis of the groove in the outer rotor, so that the traveling wave magnetic fields generated by the two sets of stator windings have position difference in the circumferential direction of the motor in space;
the permanent magnet rotor is concentrically arranged with the inner rotor and the outer rotor; the rotor permanent magnet adopts a hollow cup-shaped structure to reduce the rotational inertia, and the permanent magnet rotor adopts a segmented unequal thickness structure and is used for improving the waveform of air gap flux density, reducing harmonic components in the air gap flux density and enabling the air gap magnetic field to be distributed more close to a sinusoidal curve along the circumferential direction of the motor, thereby reducing torque pulses;
the rotor shell is matched with the end ring, and the permanent magnet rotor is embedded in the rotor shell to play a role in fixing the rotor; because the motor works in the underwater high-pressure special environment, the air gaps among the outer stator, the inner stator and the rotor permanent magnet adopt an internal oil filling structure, and the deformation of motor parts caused by the internal and external pressure difference is avoided.
Preferably, the axes of the grooves in the inner rotor and the outer rotor are not completely coincident and have a theta mechanical angle; for fundamental wave traveling wave magnetic fields generated by two sets of stator windings, the electrical angle difference of the fundamental wave traveling wave magnetic fields along the circumferential direction of the motor is psi1：
Figure BDA0003198502530000021
Wherein Z represents the number of stator slots;
for the i-th harmonic traveling wave magnetic field generated by the two sets of stator windings, the electrical angle difference in the circumferential direction of the motor is psii：
Figure BDA0003198502530000022
So that the mechanical angle difference theta between the axis of the inner rotor middle groove and the axis of the outer rotor middle groove satisfies the following condition:
Figure BDA0003198502530000023
where k represents the number of harmonics corresponding to the harmonic magnetic field having the largest amplitude among the magnetomotive forces generated by the stator winding.
Preferably, the magnetic pole of the rotor permanent magnet is made of neodymium iron boron material, and the magnetizing direction is radial magnetizing; the axial length of the permanent magnet is equal to the length of the stator core; for a single magnetic pole, the permanent magnet is divided into a central section, a middle section and an outer side section, and the permanent magnets in the sections have different thicknesses and adopt concentric ring structures; the inner diameter of the central section permanent magnet is Rin3Outer diameter of Rout3Corresponding to a central angle of alpha3(ii) a The inner diameter of the middle section permanent magnet is Rin2Outer diameter of Rout2Corresponding to a central angle of (α)2-α3) 2; the outside segment permanent magnet has an inner diameter Rin1Outer diameter of Rout1Corresponding to a central angle of (α)1-α2) 2; the inner diameter of each section of permanent magnet meets the following conditions: rout3>Rout2>Rout1>Rin1>Rin2>Rin3The central angle satisfies: alpha is alpha1>α2>α3。
Preferably, the outer stator and the inner stator both adopt a laminated silicon steel sheet structure, wherein the inner diameter of the outer stator is D1-inOuter diameter of D1-outThe length of the iron core is l1(ii) a The inner diameter of the inner stator is D2-inOuter diameter of D2-outThe length of the iron core is l2(ii) a The lengths of the cores of the outer stator and the inner stator are the same, i.e./1＝l2(ii) a The inner stator and the outer stator are symmetrically grooved at equal intervals along the circumferential direction, and the stator groove type adopts a round bottom semi-closed groove; the stator winding adopts a three-phase symmetrical three-phase or short-distance winding structure, and the structures of the stator winding and the rotor winding are the same.
Preferably, the rotor casing is made of paramagnetic titanium alloy material, and grooves with the same number as the rotor poles are cut in the casing and used for embedding the permanent magnet magnetic poles into the casing to support and protect the permanent magnet magnetic poles; an oil filling structure is adopted in an air gap of the motor, the outer surface of the rotor shell is polished to increase the surface smoothness, and the mechanical loss generated by oil stirring friction in the rotation process of the rotor shell is reduced; the end part of the casing is respectively connected with the two end rings, and after the rotor permanent magnet is embedded, the inner sealing and the fixing of the rotor permanent magnet are finished through the end rings.
Preferably, the outer stator and the inner stator winding are connected in parallel on a circuit and share a set of three-phase inversion source; the A phase of the inner stator is connected with the A phase of the outer stator in parallel; the phase B and the phase C of the inner stator are connected with the phase B and the phase C of the outer stator in parallel; a switching control switch is arranged between each phase winding of the inner stator and each phase winding of the outer stator and the three-phase inversion source; when faults such as turn-to-turn short circuit, turn-to-turn open circuit, single-phase open circuit and the like occur in the single set of winding, the change-over switch of the set of stator winding is opened, so that the set of winding does not work; and at the moment, a single set of stator winding working mode is entered, and derating operation is carried out at the cost of reducing part of output torque, so that the fault tolerance of the underwater motor is improved.
Preferably, the inner and outer diameters R of each segment of permanent magnetout3，Rout2,Rout1,Rin1,Rin2,Rin3And central angle alpha1，α2，α3The selection of the air gap flux density determines that the amplitude of the air gap flux density is related to the harmonic distortion rate in the air gap flux density; central angle alpha1，α2，α3The number of pole pairs of the magnetic poles of the rotor is related, and the following selection principle is satisfied:
Figure BDA0003198502530000041
Figure BDA0003198502530000042
determines the central angle alpha1，α2，α3After the specific numerical value is obtained, a group of parameters with the highest air gap flux density amplitude and the lowest total harmonic distortion rate is selected to determine the inner diameter R and the outer diameter R of each section of the permanent magnet through parametric scanning in finite element simulationout3，Rout2,Rout1,Rin1,Rin2,Rin3The value of (c).
The invention has the following beneficial effects:
in order to overcome the defects of the existing research, the invention provides a permanent magnet synchronous motor for underwater propulsion, which is composed of a permanent magnet rotor with different sectional thicknesses, an inner stator and an outer stator with staggered central axes and a titanium alloy rotor shell. Through the segmented permanent magnet poles with different thicknesses, the sine degree of the air gap flux density can be effectively improved, and the harmonic content and the air gap leakage magnetic field are reduced; the inner stator and the outer stator are utilized to generate a synthetic magnetic field, so that the volume power density of the motor is improved under the same volume, and the output torque of the motor is increased; the central axis of the inner rotor and the central axis of the outer rotor are designed in a staggered manner, so that harmonic components in stator magnetomotive force are eliminated, and the torque pulsation in the traditional permanent magnet synchronous motor is reduced; meanwhile, the double-stator winding is connected in parallel with the common three-phase inverter through the selector switch, and a double-stator cooperative working mode and a single-stator independent working mode can be respectively carried out, so that the fault-tolerant performance of the motor is further improved, and the fault-tolerant operation of the underwater vehicle is allowed when a single set of winding fails; in conclusion, the permanent magnet synchronous motor for underwater propulsion disclosed by the invention has the advantages of the traditional permanent magnet synchronous motor, can reduce the harmonic content in an air gap magnetic field, inhibit the motor torque, solve the problems of low power torque density and low fault tolerance rate in the existing motor for underwater propulsion, and has important significance for promoting the development and popularization of the underwater motor in the field of ocean detection.
Drawings
FIG. 1 is a schematic structural view of a permanent magnet synchronous motor for underwater propulsion according to the present invention;
FIG. 2 is an assembly view of a PMSM for underwater propulsion according to the present invention; (abstract figure)
FIG. 3 is a front view of the present invention as shown in FIG. 1;
FIG. 4 is a schematic view of the assembly of the rotor in the motor of the present invention;
FIG. 5 is a schematic structural view of a rotor permanent magnet according to the present invention;
fig. 6 is a schematic structural view of an inner stator and an outer stator in the motor of the present invention;
FIG. 7 is a schematic diagram of the connection of the inner and outer stator armature windings in the motor of the present invention;
FIG. 8 is a schematic view of the connection between the motor for underwater propulsion and the pressure compensation device according to the present invention;
FIG. 9 is a comparison graph of air gap flux density waveforms generated by optimized front and rear armature windings of inner and outer stators in a motor according to the present invention;
fig. 10 is a comparison graph of the air gap flux density waveforms generated by the rotor permanent magnets in the motor of the present invention and the conventional surface-mounted permanent magnet motor.
1-outer stator; 2-rotor magnetic pole; 3-rotor case; 4-inner stator; 5-end ring.
Detailed Description
The present invention will be described in detail with reference to specific examples.
The first embodiment is as follows:
referring to fig. 1 to 10, the present invention provides a permanent magnet synchronous motor for underwater propulsion, which is used to solve the problems of low power torque density, low fault tolerance and large power pulsation in the existing motors for underwater propulsion.
In order to solve the defects of the prior art, the invention aims to realize the following steps:
FIG. 1 shows a schematic structural diagram of a permanent magnet synchronous motor for underwater propulsion, which consists of an outer stator, an inner stator, a permanent magnet rotor, a rotor shell and an end ring, wherein the motor adopts a series magnetic circuit structure;
fig. 2 and fig. 3 respectively show an assembly schematic diagram and a front view of the permanent magnet synchronous motor for underwater propulsion, wherein an outer rotor and an inner rotor in the motor are concentrically arranged, the relative spatial positions of the outer rotor and the inner rotor are fixed, and the outer rotor and the inner rotor have the same number of grooves; the winding mode of armature windings in the outer rotor and the inner rotor is completely the same, and the armature windings are used for generating a traveling wave magnetic field in an air gap; the central axes of the outer rotor and the inner rotor are staggered, namely the axis of the groove in the inner rotor is not completely superposed with the axis of the groove in the outer rotor, so that the traveling wave magnetic fields generated by the two sets of stator windings have position difference in the space along the circumferential direction of the motor, the harmonic component in the synthesized stator magnetomotive force is eliminated, and the torque pulsation of the motor is reduced; the permanent magnet rotor is concentrically arranged with the inner rotor and the outer rotor, and is used for generating a main magnetic field in an air gap of the motor, generating electromagnetic torque after generating traveling wave magnetic field interaction with the three-phase stator winding and driving the motor rotor to rotate; the rotor permanent magnet adopts a hollow cup type structure to reduce the rotational inertia; meanwhile, a segmented unequal-thickness structure is adopted for improving the waveform of the air gap flux density, reducing the harmonic component in the air gap flux density and enabling the distribution of an air gap magnetic field along the circumferential direction of the motor to be closer to a sinusoidal curve, so that torque pulsation is reduced; the rotor shell is matched with the end ring, and the permanent magnet rotor is embedded in the rotor shell to play a role in fixing the rotor; because the motor works in the underwater high-pressure special environment, the air gaps among the outer stator, the inner stator and the rotor permanent magnet adopt an internal oil filling structure, and the deformation of motor parts caused by the internal and external pressure difference is avoided;
FIG. 4 is a schematic view of the assembly of the rotor in the motor of the present invention; the rotor structure is composed of 3 parts of a permanent magnet rotor, a rotor shell and an end ring; the rotor shell is made of paramagnetic titanium alloy material, the magnetic conductivity of the rotor shell is basically the same as that of air, and the rotor shell has no influence on the distribution of a main magnetic field; grooves with the same number as the poles of the rotor are cut in the casing and used for embedding the permanent magnet magnetic poles into the casing to support and protect the permanent magnet magnetic poles; the rotor case and the rotor permanent magnet are coaxially arranged and rotate at the same rotating speed; because the air gap of the motor adopts the oil filling structure, the outer surface of the rotor shell is polished to improve the surface smoothness, the mechanical loss generated by oil stirring friction in the rotation process of the rotor shell is reduced, and the motor efficiency is improved; the end part of the shell is respectively connected with the two end rings, and after the rotor permanent magnet is embedded, the inner sealing and fixing of the rotor permanent magnet are completed through the end rings, so that the mechanical strength and the service life of the rotor can be improved, the contact between the rotor and the external environment can be avoided, and the corrosion resistance of the rotor permanent magnet is improved;
FIG. 5 is a schematic structural diagram of a rotor permanent magnet according to the present invention; the magnetic pole of the rotor permanent magnet is made of neodymium iron boron material, and the magnetizing direction of the rotor permanent magnet is radial magnetizing; the axial length of the permanent magnet is equal to the length of the stator core; the rotor permanent magnet adopts a sectional unequal-thickness structureThe magnetic field generator has the effects of reducing the total consumption of the permanent magnets and the cost of the motor, optimizing the distribution of an air gap magnetic field, reducing the content of higher harmonics in a magnetic field generated by the rotor permanent magnets and reducing torque pulsation; for a single magnetic pole, the permanent magnet is divided into a central section, a middle section and an outer side section, and the permanent magnets in the sections have different thicknesses and adopt concentric ring structures; the inner diameter of the central section permanent magnet is Rin3Outer diameter of Rout3Corresponding to a central angle of alpha3(ii) a The inner diameter of the middle section permanent magnet is Rin2Outer diameter of Rout2Corresponding to a central angle of (α)2-α3) 2; the outside segment permanent magnet has an inner diameter Rin1Outer diameter of Rout1Corresponding to a central angle of (α)1-α2) 2; the inner diameter of each section of permanent magnet meets the following conditions: rout3>Rout2>Rout1>Rin1>Rin2>Rin3The central angle satisfies: alpha is alpha1>α2>α3；
Fig. 6 is a schematic structural view of an inner stator and an outer stator in the motor of the present invention; the outer stator and the inner stator both adopt a laminated silicon steel sheet structure, wherein the inner diameter of the outer stator is D1-inOuter diameter of D1-outThe length of the iron core is l1(ii) a The inner diameter of the inner stator is D2-inOuter diameter of D2-outThe length of the iron core is l2(ii) a The lengths of the cores of the outer stator and the inner stator are the same, i.e./1＝l2(ii) a The inner stator and the outer stator are symmetrically grooved at equal intervals along the circumferential direction, and the stator groove type adopts a round-bottom semi-closed groove so as to increase the available area in the groove and reduce the influence of the grooving on the air gap magnetic field waveform; the stator winding adopts a three-phase symmetrical three-phase or short-distance winding structure, and the structures of the stator winding and the rotor winding are the same;
fig. 7 is a schematic diagram showing the connection mode of the armature windings of the inner stator and the outer stator in the motor of the present invention, wherein the armature windings of the outer stator and the inner stator are connected in parallel on a circuit and share a set of three-phase inversion source; the A phase of the inner stator is connected with the A phase of the outer stator in parallel; in the same way, the phase B and the phase C of the inner stator are connected with the phase B and the phase C of the outer stator in parallel; a switching control switch is arranged between each phase winding of the inner stator and each phase winding of the outer stator and the three-phase inversion source; when faults such as turn-to-turn short circuit, turn-to-turn open circuit, single-phase open circuit and the like occur in a single set of winding, the change-over switch of the set of stator winding is opened, so that the set of winding does not work; at the moment, the system enters a working mode of a single set of stator winding, and the motor operates in a derating mode at the cost of reducing part of output torque, so that the fault tolerance of the underwater motor is improved;
FIG. 8 is a schematic view of the connection between the motor for underwater propulsion and the pressure compensation device according to the present invention; because the underwater propeller needs to work in a high-pressure working environment, the underwater motor needs to bear the pressure generated by seawater in the running process; although an oil filling mode is adopted in an air gap of the motor, in order to further reduce the pressure difference between the motor and seawater, the motor needs to be externally connected with a pressure compensation device, the pressure compensation device is connected with a motor shell and is communicated through an internal guide pipe, and the pressure of the voltage can be dynamically adjusted under different water pressures through the adjustment of a piston of the pressure device;
detailed description of the invention
This embodiment mode is a further description of the first embodiment mode;
in order to reduce torque pulsation and eliminate higher harmonic components in stator magnetomotive force, the axis of the inner rotor middle groove and the axis of the outer rotor middle groove in the motor for underwater propulsion are not completely overlapped and have a theta mechanical angle; for fundamental wave traveling wave magnetic fields generated by two sets of stator windings, the fundamental wave traveling wave magnetic fields have an electrical angle difference phi in the circumferential direction of the motor in space1：
Figure BDA0003198502530000081
Wherein Z represents the number of stator slots;
for the i-th harmonic traveling wave magnetic fields generated by the two sets of stator windings, the i-th harmonic traveling wave magnetic fields have an electrical angle difference phi in the circumferential direction of the motor in spacei：
Figure BDA0003198502530000082
In order to eliminate harmonic components in magnetomotive force generated in the two sets of stator windings, the mechanical angle difference theta between the axis of the groove in the inner rotor and the axis of the groove in the outer rotor meets the following requirements:
Figure BDA0003198502530000083
in the formula, k represents the harmonic frequency corresponding to the harmonic magnetic field with the maximum amplitude in the magnetomotive force generated by the stator winding; because k is influenced by the stator configuration, the mechanical angle difference theta between the axis of the inner rotor middle groove and the axis of the outer rotor middle groove is comprehensively determined by the shape of the stator groove, the pole arc coefficient and the like;
for the slot type and pole arc coefficient motor shown in fig. 3, the harmonic occupancy rate of the 5 th harmonic magnetic field in the air gap flux density generated by the two sets of stator windings is high, so that k is equal to 5, and the mechanical angle difference θ can be calculated to be 18 °; FIG. 9 shows simulation results of the resulting air gap flux density generated by the stator winding when the mechanical angle difference θ is equal to 0 and 18, respectively; as can be seen from the figure, the permanent magnet synchronous motor for underwater propulsion can effectively reduce the higher harmonic component in the magnetomotive force of the stator winding by designing the mechanical angle difference between the axis of the groove in the inner rotor and the axis of the groove in the outer rotor;
detailed description of the invention
This embodiment mode is a further description of the first embodiment mode;
in order to reduce the torque ripple, the higher harmonic components in the air gap magnetic field generated by the rotor permanent magnet also need to be eliminated; the rotor permanent magnet adopts a distributed unequal thickness structure, and the inner diameter and the outer diameter of each section of permanent magnet are Rout3，Rout2,Rout1,Rin1,Rin2,Rin3And central angle alpha1，α2，α3The selection of the air gap flux density determines that the amplitude of the air gap flux density is related to the harmonic distortion rate in the air gap flux density; central angle alpha1，α2，α3The number of pole pairs of the magnetic poles of the rotor is related, and the following selection principle is satisfied:
Figure BDA0003198502530000091
Figure BDA0003198502530000092
then the central angle alpha is determined1，α2，α3After the specific numerical value is obtained, a group of parameters with the highest air gap flux density amplitude and the lowest total harmonic distortion rate is selected to determine the inner diameter R and the outer diameter R of each section of the permanent magnet through parametric scanning in finite element simulationout3，Rout2,Rout1,Rin1,Rin2,Rin3A value of (d);
fig. 10 is a graph showing a comparison of simulation results of air gap flux density waveforms generated by the rotor permanent magnets of the permanent magnet synchronous motor for underwater propulsion and the conventional surface-mounted permanent magnet motor, and it can be seen from the graph that the segmented unequal-thickness rotor permanent magnet structure in the motor of the present invention can effectively reduce the higher harmonic component in the air gap magnetic field generated by the permanent magnet, thereby reducing torque ripple.
The invention provides a novel permanent magnet synchronous motor for underwater propulsion, which is composed of a segmented hollow cup-shaped permanent magnet rotor with unequal thicknesses and two sets of three-phase stator windings with staggered central axes. The double stator winding structure can further increase the power density and output torque of the motor under the same volume. Meanwhile, when one set of stator winding breaks down, the other set of stator winding can be adopted to work independently, and the fault tolerance of the motor is further improved. The two sets of stator windings are staggered through the center, so that higher harmonics in magnetomotive force of the stator windings are eliminated, torque pulsation is further suppressed, and noise generated in the running process of the motor is reduced. The underwater permanent magnet synchronous motor provided by the invention not only meets the requirements of an underwater propulsion system on the characteristics of small motor size, high power density and the like at the present stage, but also solves the problems of poor fault tolerance, large torque pulsation and the like of the traditional underwater motor, and has important significance for promoting the development of the field of ocean detection.
The above description is only a preferred embodiment of the double-stator permanent magnet synchronous motor for the underwater vehicle, and the protection scope of the double-stator permanent magnet synchronous motor for the underwater vehicle is not limited to the above embodiments, and all technical solutions belonging to the idea belong to the protection scope of the present invention. It should be noted that modifications and variations which do not depart from the gist of the invention will be those skilled in the art to which the invention pertains and which are intended to be within the scope of the invention.

Claims (7)

1. A permanent magnet synchronous motor for an underwater vehicle is characterized in that: the motor includes: the permanent magnet motor comprises an outer stator, an inner stator, a permanent magnet rotor, a rotor shell and an end ring;
the outer rotor and the inner rotor are concentrically arranged, are fixed relative to the space position and have the same groove number; the winding mode of armature windings in the outer rotor and the inner rotor is completely the same, and the armature windings are used for generating a traveling wave magnetic field in an air gap; the central axes of the outer rotor and the inner rotor are staggered, namely the axis of the groove in the inner rotor is not completely superposed with the axis of the groove in the outer rotor, so that the traveling wave magnetic fields generated by the two sets of stator windings have position difference in the circumferential direction of the motor in space;
the permanent magnet rotor is concentrically arranged with the inner rotor and the outer rotor; the rotor permanent magnet adopts a hollow cup-shaped structure to reduce the rotational inertia, and the permanent magnet rotor adopts a segmented unequal thickness structure and is used for improving the waveform of air gap flux density, reducing harmonic components in the air gap flux density and enabling the air gap magnetic field to be distributed more close to a sinusoidal curve along the circumferential direction of the motor, thereby reducing torque pulses;
the rotor shell is matched with the end ring, and the permanent magnet rotor is embedded in the rotor shell to play a role in fixing the rotor; because the motor works in the underwater high-pressure special environment, the air gaps among the outer stator, the inner stator and the rotor permanent magnet adopt an internal oil filling structure, and the deformation of motor parts caused by the internal and external pressure difference is avoided.
2. A double stator permanent magnet synchronous motor for underwater vehicles according to claim 1, wherein: the axis of the inner rotor middle groove is not completely superposed with the axis of the outer rotor middle groove, and has a theta mechanical angle; for fundamental wave traveling wave magnetic fields generated by two sets of stator windings, the electrical angle difference of the fundamental wave traveling wave magnetic fields along the circumferential direction of the motor is psi1：
Figure FDA0003198502520000011
Wherein Z represents the number of stator slots;
for the i-th harmonic traveling wave magnetic field generated by the two sets of stator windings, the electrical angle difference in the circumferential direction of the motor is psii：
Figure FDA0003198502520000012
So that the mechanical angle difference theta between the axis of the inner rotor middle groove and the axis of the outer rotor middle groove satisfies the following condition:
Figure FDA0003198502520000013
where k represents the number of harmonics corresponding to the harmonic magnetic field having the largest amplitude among the magnetomotive forces generated by the stator winding.
3. A permanent magnet synchronous motor for underwater vehicles according to claim 2, characterized in that:
the magnetic pole of the rotor permanent magnet is made of neodymium iron boron material, and the magnetizing direction is radial magnetizing; the axial length of the permanent magnet is equal to the length of the stator core; for a single magnetic pole, the permanent magnet is divided into three parts, namely a central section, a middle section and an outer section, wherein each sectionThe permanent magnets are different in thickness and adopt concentric ring structures; the inner diameter of the central section permanent magnet is Rin3Outer diameter of Rout3Corresponding to a central angle of alpha3(ii) a The inner diameter of the middle section permanent magnet is Rin2Outer diameter of Rout2Corresponding to a central angle of (α)2-α3) 2; the outside segment permanent magnet has an inner diameter Rin1Outer diameter of Rout1Corresponding to a central angle of (α)1-α2) 2; the inner diameter of each section of permanent magnet meets the following conditions: rout3>Rout2>Rout1>Rin1>Rin2>Rin3The central angle satisfies: alpha is alpha1>α2>α3。
4. A double stator permanent magnet synchronous motor for underwater vehicles according to claim 3, wherein: the outer stator and the inner stator both adopt a laminated silicon steel sheet structure, wherein the inner diameter of the outer stator is D1-inOuter diameter of D1-outThe length of the iron core is l1(ii) a The inner diameter of the inner stator is D2-inOuter diameter of D2-outThe length of the iron core is l2(ii) a The lengths of the cores of the outer stator and the inner stator are the same, i.e./1＝l2(ii) a The inner stator and the outer stator are symmetrically grooved at equal intervals along the circumferential direction, and the stator groove type adopts a round bottom semi-closed groove; the stator winding adopts a three-phase symmetrical three-phase or short-distance winding structure, and the structures of the stator winding and the rotor winding are the same.
5. A double stator permanent magnet synchronous motor for underwater vehicles according to claim 4, wherein: the rotor case is made of paramagnetic titanium alloy materials, grooves with the same number as the poles of the rotor are cut in the case, and the grooves are used for embedding the magnetic poles of the permanent magnet into the case and supporting and protecting the magnetic poles of the permanent magnet; an oil filling structure is adopted in an air gap of the motor, the outer surface of the rotor shell is polished to increase the surface smoothness, and the mechanical loss generated by oil stirring friction in the rotation process of the rotor shell is reduced; the end part of the casing is respectively connected with the two end rings, and after the rotor permanent magnet is embedded, the inner sealing and the fixing of the rotor permanent magnet are finished through the end rings.
6. A double stator permanent magnet synchronous motor for underwater vehicles according to claim 5, wherein: the outer stator winding and the inner stator winding are connected in parallel on a circuit and share a set of three-phase inversion source; the A phase of the inner stator is connected with the A phase of the outer stator in parallel; the phase B and the phase C of the inner stator are connected with the phase B and the phase C of the outer stator in parallel; a switching control switch is arranged between each phase winding of the inner stator and each phase winding of the outer stator and the three-phase inversion source; when faults such as turn-to-turn short circuit, turn-to-turn open circuit, single-phase open circuit and the like occur in the single set of winding, the change-over switch of the set of stator winding is opened, so that the set of winding does not work; and at the moment, a single set of stator winding working mode is entered, and derating operation is carried out at the cost of reducing part of output torque, so that the fault tolerance of the underwater motor is improved.
7. A double stator permanent magnet synchronous motor for underwater vehicles according to claim 6, wherein: inner and outer diameters R of each permanent magnetout3，Rout2,Rout1,Rin1,Rin2,Rin3And central angle alpha1，α2，α3The selection of the air gap flux density determines that the amplitude of the air gap flux density is related to the harmonic distortion rate in the air gap flux density; central angle alpha1，α2，α3The number of pole pairs of the magnetic poles of the rotor is related, and the following selection principle is satisfied:
Figure FDA0003198502520000031
Figure FDA0003198502520000032
determines the central angle alpha1，α2，α3After the specific numerical value is obtained, the maximum air gap flux density amplitude and the total harmonic distortion are selected through parametric scanning in finite element simulationDetermining the inner and outer diameters R of each permanent magnet section by a group of parameters with the lowest rateout3，Rout2,Rout1,Rin1,Rin2,Rin3The value of (c).
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009303362A (en) * 2008-06-12 2009-12-24 Mitsubishi Electric Corp Rotary electric machine
CN102204070A (en) * 2008-07-22 2011-09-28 阿利发风有限公司 Permanently excited synchronous machine
JP2017022994A (en) * 2016-09-30 2017-01-26 シーメンス アクチエンゲゼルシヤフトＳｉｅｍｅｎｓ Ａｋｔｉｅｎｇｅｓｅｌｌｓｃｈａｆｔ Electric motor
CN107078617A (en) * 2014-10-17 2017-08-18 株式会社Ihi Bimorph transducer type circulator

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009303362A (en) * 2008-06-12 2009-12-24 Mitsubishi Electric Corp Rotary electric machine
CN102204070A (en) * 2008-07-22 2011-09-28 阿利发风有限公司 Permanently excited synchronous machine
CN107078617A (en) * 2014-10-17 2017-08-18 株式会社Ihi Bimorph transducer type circulator
JP2017022994A (en) * 2016-09-30 2017-01-26 シーメンス アクチエンゲゼルシヤフトＳｉｅｍｅｎｓ Ａｋｔｉｅｎｇｅｓｅｌｌｓｃｈａｆｔ Electric motor

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