Dual mechanical ports permanent magnet motor with composite stator

Abstract

A dual rotor, dual stator permanent magnet motor, comprising: first armature stator 1; first rotor 3; composite (second) stator 4; and second rotor 5, wherein the composite stator comprises an excitat

Description

22 10 25 DESCRIPTION Dual Mechanical Ports Permanent Magnet Motor with Composite Stator TECHNICAL FIELD 5

[0001] The present invention belongs to the technical field of motor, and in particular, relates to a dual mechanical ports permanent magnet motor with composite stator and a torque distribution method therefor. BACKGROUND 10

[0002] With increasing severity of atmospheric pollution and growing scarcity of petroleum resources, zero-emission electric vehicles are gradually entering the market. As a key component of electric vehicles, selection of vehicle drive motors is crucial for improving the electric vehicles’ performance. Axial permanent magnet motors not only inherit advantages of permanent magnet motors, such as high power density and high torque density, but also 15 have advantages of axial motors including compact structure and high silicon steel sheet utilization rate, making them particularly suitable for the field of new energy vehicle, which demands high torque.

[0003] However, most vehicle drive motors focused by existing research are single-motor systems. To account for extreme conditions such as climbing and high-speed driving, the 20 motor size is often arranged to be oversized. However, in practice, the motors frequently are operated under conditions of low speed and low load, significantly reducing efficiency of the motors and leading to substantial energy waste.

[0004] Currently, a type of dual-rotor motor employs a two-layer rotor structure to achieve dual mechanical ports output, and has a compact structure and high integration. Compared to 25 traditional permanent magnet motors, the value of the combined torque of inner and outer motors is greatly enhanced, and motor efficiency is effectively improved. Nevertheless, since 22 10 25 these motors share a common stator, magnetic circuit coupling inevitably occurs on a stator side, thereby affecting the independent operation capability of the inner and outer motors. SUMMARY

[0005] An object of the present invention is to at least partially address the aforementioned technical problems, and aims to provide a dual mechanical ports permanent magnet motor with composite stator and a torque distribution method therefor. This solution not only enhances the power density of the permanent magnet motor but also enables multi-mode operation for the permanent magnet motor, meeting diverse operating conditions in the field of new energy vehicles.

[0006] In a first aspect of the present invention, it is provided a dual mechanical ports permanent magnet motor with composite stator comprising:

[0007] four components comprising a first armature stator, a first rotor, a composite stator, and a second rotor sequentially coaxially placed, an axial air gap being between two adjacent components of the four components,

[0008] wherein the composite stator comprises an excitation stator and a second armature stator arranged in a direction extending from the first armature stator to the second rotor, and

[0009] the dual mechanical ports permanent magnet motor is operated in one of three modes comprising an independent drive mode by the first armature stator, an independent drive mode by the second armature stator, and a combined drive mode by the first armature stator and the second armature stator by controlling current in armature windings of the first armature stator and the second armature stator.

[0010] In some embodiments of the present invention, when the dual mechanical ports permanent magnet motor is operated under conditions of medium speed and medium load, the dual mechanical ports permanent magnet motor is operated in the independent drive mode by the first armature stator, wherein the medium speed is greater than half of a rated speed of the 2 22 10 25 dual mechanical ports permanent magnet motor and less than the rated speed, and the medium load is less than 1.5 times of a reference torque of the dual mechanical ports permanent magnet motor and greater than half of the reference torque.

[0011] In some embodiments of the present invention, when the dual mechanical ports permanent magnet motor is operated under conditions of high speed and small load, the dual mechanical ports permanent magnet motor is operated in the independent drive mode by the second armature stator, wherein the high speed is greater than a rated speed of the dual mechanical ports permanent magnet motor, and the small load is less than half of a reference torque of the dual mechanical ports permanent magnet motor.

[0012] In some embodiments of the present invention, when the dual mechanical ports permanent magnet motor is operated under conditions of low speed and large load, the dual mechanical ports permanent magnet motor is operated in the combined drive mode by the first armature stator and the second armature stator, wherein the low speed is less than half of a rated speed of the dual mechanical ports permanent magnet motor, and the large load is greater than 1.5 times of a reference torque of the dual mechanical ports permanent magnet motor.

[0013] In some embodiments of the present invention, the excitation stator has a shape of circular ring and comprises m excitation cores and m neodymium-iron-boron permanent magnet blocks, the excitation cores comprising sector-shaped magnetically conductive iron blocks;

[0014] the neodymium-iron-boron permanent magnet blocks are arranged in a spoke pattern and circumferentially embedded in the excitation core, wherein m is an integer greater than or equal to 3; and

[0015] the axial air gap has a width in a range from 0.5mm to 1mm.

[0016] In some embodiments of the present invention, the second armature stator comprises second armature teeth and second armature windings wound around the second armature teeth, wherein the second armature teeth are closely positioned to the excitation core, and each of 3 22 10 25 the second armature teeth has a radial outer end surface aligned with an outer end surface of the excitation core and a radial inner end surface aligned with an inner end surface of the excitation core, and the sector-shaped magnetically conductive iron blocks of the excitation core have a radial symmetrical center line positioned in a same axial vertical plane as that of the second armature teeth.

[0017] In some embodiments of the present invention, the neodymium-iron-boron permanent magnet blocks are tangentially magnetized, and two circumferentially adjacent neodymium-iron-boron permanent magnet blocks have opposite magnetization directions; and

[0018] the neodymium-iron-boron permanent magnet block has a pole arc width a0, the excitation core has a pole arc width ap, the second armature tooth has a pole arc width m, and a relationship among them is a0<ai<ap.

[0019] In some embodiments of the present invention, the first armature core comprises:

[0020] a first stator armature core comprising a first armature yoke, first armature teeth and excitation teeth, the first armature teeth having an equal number to that of the excitation teeth, and the first armature teeth and the excitation teeth being circumferentially alternately arranged on the first armature yoke; and

[0021] a first stator winding comprising first armature windings wound around the first armature teeth and an excitation winding wound around the excitation teeth.

[0022] In some embodiments of the present invention, the first rotor consists of k salient pole magnetically conductive blocks arranged on a circumference and circumferentially spaced at equal intervals, of which two adjacent magnetically conductive blocks are connected by a non-magnetic material, wherein k is an integer greater than 3; and

[0023] the second rotor comprises a rotor yoke having a shape of circular ring and j salient pole rotor teeth protruding from the rotor yoke, wherein each of the salient pole rotor teeth has an outer end surface aligned with that of the rotor yoke and an inner end surface aligned 4 22 10 25 with that of the rotor yoke, and wherein j is an integer greater than 3.

[0024] In some embodiments of the present invention, the neodymium-iron-boron permanent magnet blocks of the composite stator generate permanent magnet flux paths including a permanent magnet flux path a and a permanent magnet flux path b, wherein

[0025] the permanent magnetic flux path a is as follows: starting from the neodymium-iron-boron permanent magnet block, sequentially passing through the excitation core, the first rotor, the first armature tooth, the first armature yoke, the excitation tooth, the first rotor and the excitation core, and finally returning to the neodymium-iron-boron permanent magnet block; and

[0026] the permanent magnetic flux path b is as follows: starting from the neodymium-iron-boron permanent magnet block, sequentially passing through the excitation core, the second armature tooth, the salient pole rotor tooth, the rotor yoke, the salient pole rotor tooth, the second armature tooth and the excitation core, and finally returning to the neodymium-iron-boron permanent magnet block.

[0027] In a second aspect of the present invention, it is provided a torque distribution method for the dual mechanical ports permanent magnet motor with composite stator according to any one of the above embodiments, comprising:

[0028] due to independently applying a three-phase alternating current to first armature windings of a first armature stator, the three-phase alternating current interacting with an outer air-gap magnetic field, such that a first rotor outputs torque and the dual mechanical ports permanent magnet motor is operated under an independent drive mode by the first armature stator;

[0029] due to independently applying the three-phase alternating current to second armature windings of a second armature stator, the three-phase alternating current interacting with an inner air-gap magnetic field, such that a second rotor outputs torque and the dual mechanical ports permanent magnet motor is operated under an independent drive mode by the second 5 armature stator; and

[0030] due to applying the three-phase alternating current to the first armature windings and the second armature windings, the three-phase alternating current applied to the first armature windings and the second armature windings interacting with the outer air-gap magnetic field 5 and the inner air-gap magnetic field, respectively, such that the first rotor and the second rotor output a superimposed torque and the dual mechanical ports permanent magnet motor is operated under a combined drive mode by the first the armature stator and the second armature stator.

[0031] In some embodiments of the present invention, the dual mechanical ports permanent 10 magnet motor has a rated speed of nrated, a rated current of iqrated, a reference torque of Tref 22 10 25 3 being expressed as Tref = pnXi qrated , where \| / pmi is permanent magnet excitation flux of the first stator, and k is the number of salient pole magnetically conductive blocks of the first rotor and is an integer greater than or equal to 3.

[0032] In some embodiments of the present invention, when the dual mechanical ports 15 permanent magnet motor is operated under conditions of high speed n being greater than nrated and small load T being less than 0.5Tref, the dual mechanical ports permanent magnet motor is operated in the independent drive mode by the second armature stator.

[0033] In some embodiments of the present invention, the torques output by the first rotor and the second rotor are < X=o respectively, and torque Te output by the dual mechanical 20 ports permanent magnet motor can be expressed as: 3

[0034] Te=-jWpn.iq. ;

[0035] where, \| / pm2 is the permanent magnet excitation flux of the second stator, iq2 is quadrature axis current supplied to the second armature windings, and j is the number of salient pole rotor teeth of the second rotor and is an integer greater than 3.

[0036] The direct axis current and the quadrature axis current supplied to the first armature windings of the first rotor are expressed as idx = i x = 0 ,

[0037] the direct axis current and the quadrature axis current supplied to the second armature windings of the second rotor are expressed as _ 2Te , where j is the number of salient 22 10 25 5 pole rotor teeth of the second rotor and is an integer greater than 3, and \| / pm2 is the permanent magnet excitation flux of the second stator.

[0038] In some embodiments of the present invention, when the dual mechanical ports permanent magnet motor is operated under conditions of medium speed n being greater than 0.5nrated and smaller than nrated and medium load T being greater than 0.5Tref and less than 10 1.5Tref, the dual mechanical ports permanent magnet motor is operated in the independent drive mode by the first armature stator.

[0039] In some embodiments of the present invention, the torques output by the first rotor and the second rotor are < X =T el e T, =0 I. el respectively, and torque Te output by the dual mechanical ports permanent magnet motor can be expressed as: 15 a. Te =-k(wpml+Lfif)iql

[0040] where, \| / pmi is the permanent magnet excitation flux of the first stator, Lf is inductance of the first stator excitation winding, if is direct current supplied to the first stator excitation winding, iqi is quadrature axis current supplied to the first armature winding, and k is the number of salient pole magnetically conductive blocks of the first rotor and is an integer 20 greater than or equal to 3.

[0041] When the torque Te output by the dual mechanical ports permanent magnet motor is lower than the reference torque Tref, the direct axis current and the quadrature axis current supplied to the first armature windings are expressed as 2Te , and

[0042] the direct axis current and the quadrature axis current supplied to the second armature windings of the second rotor are expressed as id2 = iq2 = 0 ; and

[0043] when the torque Te output by the dual mechanical ports permanent magnet motor is 5 higher than the reference torque Tref, the direct axis current and the quadrature axis current supplied to the first armature windings are expressed as lq\ Iqrated

[0044] excitation current supplied to the excitation winding is expressed as 22 10 25 -T7---— Wpmy ^^qrated / Lf, and

[0045] the direct axis current and the quadrature axis current supplied to the second armature 10 windings are expressed as id2 = iq2 = 0 .

[0046] In some embodiments of the present invention, when the dual mechanical ports permanent magnet motor is operated under conditions of low speed n being less than 0.5nrated and large load T being greater than 1.5Tref, the dual mechanical ports permanent magnet motor is operated in the combined drive mode by the first armature stator and the second armature 15 stator.

[0047] In some embodiments of the present invention, a total torque output by the first rotor and the second rotor is: 3 3

[0048] T=TeX + Te2 = +-jVpm2iq2.

[0049] In some embodiments of the present invention, with the minimum total copper 20 consumption of the motor as the control objective, an optimal torque distribution strategy for the first rotor and the second rotor is < T 1el pml RslWpm2 + R-slV pm\ _____RplWpml_____ RslWpm2 +Rs2.Wpml

[0050] In some embodiments of the present invention, under the optimal torque distribution strategy, the direct axis current and the quadrature axis current supplied to the first armature hi windings are expressed as t . 2Tel , and the direct axis current and the quadrature axis 3kVpml current of the second armature windings are expressed as < • 27e2 / 92 IJVpml 22 10 25

[0051] The dual mechanical ports permanent magnet motor with composite stator and the torque distribution method therefor according to an embodiment of the present invention have at least one of the following advantages:

[0052] 1. The dual mechanical ports permanent magnet motor of the present invention 10 utilizes a composite stator and a dual-rotor structure, and by controlling the currents of the armature windings of the first armature stator and the second armature stator, respectively, it can realize the distribution of the output power of the dual-mechanical ports, so as to satisfy the requirements of different working conditions, thereby making the output efficiency and the output torque of the permanent magnet motor reach the optimal value. 15

[0053] 2. In the dual mechanical ports permanent magnet motor of the present invention, the first rotor and the second rotor are both not equipped with permanent magnets and windings, which avoids the heat dissipation difficulty of rotor windings that may be caused by the rotor-excited type motor and the demagnetization problem that may be caused by the permanent magnets at the side of rotor under high temperature, thereby improving the reliability of the 20 permanent magnet motor. 22 10 25

[0054] 3. In the dual mechanical ports permanent magnet motor of the present invention, the first armature stator and the second armature stator share the permanent magnet flux generated by the neodymium-iron-boron permanent magnet blocks of the composite stator, which effectively improves the utilization rate of the permanent magnets of this type of motor and reduces the leakage of magnetism at the end of the permanent magnets.

[0055] 4. In the dual mechanical ports permanent magnet motor of the present invention, the excitation teeth are added to the first stator, and excitation strengthening / weakening can be achieved by supplying the current to the excitation winding, so as to make up for the defects that the magnetic field of the permanent magnet motor is unadjustable; and when demagnetization occurs in the permanent magnet of the inner stator, the existence of the excitation winding can build up the air-gap magnetic field to guarantee the normal operation of the motor.

[0056] 5. The dual mechanical ports permanent magnet motor of the present invention can change the operation mode of the motor by changing the armature current applied to the first and second armature windings to meet the requirements of different working conditions, so that the torque output by the motor and the efficiency of the motor reach the optimum, and at the same time, by adding the excitation winding, the air gap magnetic field of the motor can be adjustable, which strengthens the motor's weak magnetism and torque output capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] These and / or other aspects and advantages of the present invention will become apparent and more readily appreciated from the following description of preferred embodiments, taken in conjunction with the accompanying drawings of which:

[0058] Fig. 1 is an exploded schematic view of a dual mechanical ports permanent magnet motor with composite stator according to an embodiment of the present invention;

[0059] Fig. 2 is a structural schematic view of a first armature stator of Fig. 1; io 22 10 25

[0060] Fig. 3 is a structural schematic view of first armature windings and an excitation winding of Fig. 1;

[0061] Fig. 4 is a structural schematic view of a composite stator of Fig. 1;

[0062] Fig. 5 is a structural schematic view of a second rotor of Fig. 1; and

[0063] Fig. 6 is a magnetic circuit schematic diagram of the dual mechanical ports permanent magnet motor with composite stator as shown in Fig. 1. DETAILED DESCRIPTION

[0064] Hereinafter, the technical solutions of the present invention will be described in further detail by way of embodiments in conjunction with the accompanying drawings. In the specification, identical or similar reference numerals indicate identical or similar parts. The following description of embodiments of the present invention with reference to the accompanying drawings is intended to explain the general inventive concept of the present invention, and should not be construed to limit the present invention.

[0065] Referring to Fig. 1, it shows a dual mechanical ports permanent magnet motor, for example, with composite stator, according to an embodiment of the present invention.

[0066] The permanent magnet motor mainly includes four components: a first armature stator 1, a first rotor 3, a composite stator 4, and a second rotor 5. The first armature stator 1, the first rotor 3, the composite stator 4 and the second rotor 5 are coaxially placed and arranged in that order, that is the four componets are sequentially coaxially placed from the first armature stator 1. The components are placed axially but not closely positioned with an axial air gap between two adjacent components. The axial air gap has a width in a range from 0.5mm to 1mm, according to actual needs.

[0067] Referring to Fig. 2, the first armature stator 1 includes a first stator armature core and first stator winding 2. The first stator armature core includes three components: a first armature yoke 1-3, first armature teeth 1-1, and excitation teeth 1-2. Specifically, the number ii 22 10 25 of the first armature teeth 1-1 is equal to that of the excitation teeth 1-2. The specific number of the first armature teeth 1-1 or the excitation teeth 1-2 may be adjusted according to actual needs. The first armature teeth 1-1 and the excitation teeth 1-2 are both circumferentially alternately arranged on the first armature yoke 1 -3.

[0068] Referring to Fig. 3, the first stator winding 2 includes two components: first armature windings 2-1 and an excitation winding 2-2. The first armature windings 2-1 are in the first armature teeth 1-1. The excitation winding 2-2 is wound around the excitation teeth 1-2.

[0069] Referring back to Fig. 1, the first rotor 3 consists of k salient pole magnetically conductive blocks. The k salient pole magnetically conductive blocks are arranged on a circumference and circumferentially spaced at equal intervals. Two adjacent magnetically conductive blocks are connected by a non-magnetic material.

[0070] Referring to Fig. 4, the composite stator 4 consists of a two-layer structure arranged in a direction extending from the first armature stator to the second rotor. The two-layer structure includes a first layer and a second layer. The first layer is an excitation stator. The excitation stator has a shape of circular ring, and includes an excitation core 4-1 and neodymium-iron-boron permanent magnet blocks 4-2. The excitation core 4-1 is formed by m sector-shaped magnetically conductive iron blocks, and the number of the neodymium-iron-boron permanent magnet blocks 4-2 is m, wherein m is an integer greater than 3. The neodymium-iron-boron permanent magnet blocks 4-2 are arranged in a spoke pattern and circumferentially embedded in the excitation core 4-1.

[0071] The second layer is a second armature stator including second armature teeth 4-3 and second armature windings 4-4 wound around the second armature teeth 4-3. The second armature teeth 4-3 are closely positioned to the excitation core 4-1. Each of the second armature teeth 4-3 has a radial outer end surface aligned with an outer end surface of the excitation core 4-1, and a radial inner end surface aligned with an inner end surface of the excitation core 4-1. The sector-shaped magnetically conductive iron blocks have a radial 12 22 10 25 symmetrical center line positioned in the same axial vertical plane as that of the second armature teeth 4-3.

[0072] The neodymium-iron-boron permanent magnet blocks 4-2 are tangentially magnetized, and two circumferentially adjacent neodymium-iron-boron permanent magnet blocks 4-2 have opposite magnetization directions. The neodymium-iron-boron permanent magnet block 4-2 has a pole arc width a0, the excitation core 4-1 has a pole arc width ap, the second armature tooth 4-3 has a pole arc width ai, and the relationship among them is a0<ai<ap.

[0073] Referring to Fig. 5, the second rotor 5 includes a rotor yoke 5-2 and j salient pole rotor teeth 5-1 protruding from the rotor yoke 5-2. The salient pole rotor tooth 5-1 has an outer end surface aligned with that of the rotor yoke 5-2, and an inner end surface aligned with that of the rotor yoke 5-2. The rotor yoke 5-2 has a shape of circular ring.

[0074] In some embodiments, the first armature windings 2-1 are supplied with three-phase alternating current, and the excitation winding 2-2 is supplied with direct current. Excitation strengthening / weakening can be achieved by adjusting the magnitude and polarity of the direct current, so as to change torque output capability and speed regulation range of the permanent magnet motor.

[0075] Specifically, referring to Fig. 6, the neodymium-iron-boron permanent magnet blocks 4-2 in the first layer generate permanent magnet flux paths including a permanent magnet flux path a and a permanent magnet flux path b. The permanent magnetic flux path a is as follows: starting from the neodymium-iron-boron permanent magnet block 4-2, sequentially passing through the excitation core 4-1, the first rotor 3, the first armature tooth 1-1, the first armature yoke 1-3, the excitation tooth 1-2, the first rotor 3 and the excitation core 4-1, and finally returning to the neodymium-iron-boron permanent magnet block 4-2. The permanent magnetic flux path b is as follows: starting from the neodymium-iron-boron permanent magnet block 4-2, sequentially passing through the excitation core 4-1, the second armature tooth 4-3, the salient pole rotor tooth 5-1, the rotor yoke 5-2, the salient pole rotor tooth 5-1, 13 22 10 25 the second armature tooth 4-3 and the excitation core 4-1, and finally returning to the neodymium-iron-boron permanent magnet block 4-2.

[0076] Specifically, when the first armature windings 2-1 are independently applied with the three-phase alternating current, the three-phase alternating current interacts with an outer air-5 gap magnetic field to enable the first rotor 3 to output torque; when the second armature windings 4-4 are independently applied with the three-phase alternating current, the three-phase alternating current interacts with an inner air-gap magnetic field to enable the second rotor 5 to output torque; and when the first armature windings 2-1 and the second armature windings 4-4 are simultaneously applied with the three-phase alternating current, the three-10 phase current applied to the first and second armature windings 2-1 and 4-4 interact with the inner and outer air-gap magnetic fields, respectively, and connect the first and second rotors 3 and 5 via planetary gears, to enable value of the torque output by the motor to be superimposed, thereby greatly enhancing the torque output capability of the motor.

[0077] In another aspect of the present invention, it is further provided a torque distribution 15 method for a dual mechanical ports permanent magnet motor with composite stator which is operated mainly in the following three modes.

[0078] 1) Mode 1: Independent drive mode by the second armature stator

[0079] When the drive motor is operated under conditions of high speed and small load, the dual mechanical ports permanent magnet motor with composite stator is operated in the 20 independent drive mode by the second armature stator. In this mode, only the second armature stator is operated independently and only the second armature windings 4-4 are applied with the three-phase alternating current. Since the permanent magnet motor has a small pole saliency ratio, id can be arranged as 0 to realize the torque output of the permanent magnet motor. The torques output by the first rotor 3 and the second rotor 5 are, respectively, (1)

[0080] In this case, the torque Te output by the permanent magnet motor can be expressed as 3 i- Te=-jypm7iq2 (2)

[0081] where, \| / pm2 is the permanent magnet excitation flux of the second stator 5, iq2 is 5 quadrature axis current supplied to the second armature windings 4-4 , and j is the number of salient pole rotor teeth 5-1 of the second rotor 5 and is an integer greater than 3.

[0082] According to equation (2), the direct axis current and the quadrature axis current supplied to the first armature windings 2-1 and the second armature windings 4-4 of the permanent magnet motor can be expressed as ^dl 10 a. (3) 22 10 25

[0083] 2) Mode 2: Independent drive mode by the first armature stator

[0084] When the drive motor is operated under conditions of medium speed and medium load, the dual mechanical ports permanent magnet motor with composite stator is operated in the independent drive mode by the first armature stator. In this mode, only the first armature 15 stator is operated independently, only the second armature windings 4-4 are applied with the three-phase alternating current, and the excitation winding are supplied with the direct current to serve as an auxiliary flux-regulation function. The torques output by the first rotor 3 and the second rotor 5 are, respectively, fr = T i- 1 6 (4) Ze2 = 0 20

[0085] The torque Te output by the permanent magnet motor can be expressed as a- Te=^k(ypmX+Lfif}iqX (5)

[0086] where, \| / pmi is the permanent magnet excitation flux of the first stator, Lf is inductance of the first stator excitation winding, if is direct current supplied to the first stator excitation winding, iqi is quadrature axis current supplied to the first armature windings 2-1, and k is the number of salient pole magnetically conductive blocks of the first rotor and is an integer greater than or equal to 3. 5

[0087] A reference torque Tref can be expressed as 3 a. T f=—kw ,i ., (6) ref 2 ' '

[0088] According to equation (5), the direct axis current and the quadrature axis current supplied to the first armature windings 2-1 and the second armature windings 4-4 can be expressed as a. 22 10 25 Cl ^dl ^q2 0 . 2Te ,T <Tref 91 3^i hi hi hi 0 < hl — hrated •> Zf grated (7) (8)

[0089] where, iqrated is the rated q-axis current value of the first armature windings. When iqi for the quadrature axis current supplied to the first armature windings 2-1 reaches iqrated for the rated current value, the required torque output by the permanent magnet motor still does 15 not satisfy the required load requirements, then it is necessary to additionally apply the direct current to the excitation winding, the current magnitude of which is shown in equation (8).

[0090] 3) Mode 3: Combined drive mode by the first armature stator and the second armature stator

[0091] When the drive motor is operated under conditions of low speed and large load, the 20 dual mechanical ports permanent magnet motor with composite stator is operated in the combined drive mode by the first armature stator and the second armature stator. In this mode, the first and second armature stators operated cooperatively and the first and second armature windings are both supplied with the three-phase alternating current. The torque Te output by the motor can be expressed as 3 3 a- Te =Tc] +Te^=- kypnAiqX + - wpm2iq2 (9)

[0092] To maximize the torque per ampere of the motor, minimizing a total copper 5 consumption of the motor is selected as a control objective. a. Pc =-Rsl +i^ + -Rs2 + fqA (10) ol y Ul 1 y o Z y Ct Z cy Z y ' Z

[0093] According to equation (10), construct the Lagrange equation t 3 / ,. • Te ^pm^qA

[0094] Taking partial derivatives of the Lagrange's equation (11) with respect to iai, iqi, id2, 3 (11) 10 iq2 and X, respectively, it can be obtained: 22 10 25 dL — 3Rs\idi — 0 dL di ai = ^RPdi = 0 a. < dL diq, 3 = 3R j. —kw . = 0 si ql t pml (12) dL diqi 3 — ^Rsliq1 ~ Pm1 — 0 dL ~dk ’ 3 . 3 . . - Re Pm\iq\ Pmliq1 —

[0095] By solving equation (12), relationship expression among iai, iqi, ia2, iq2 can be obtained Li hi 0 i. . RsiVpnA . (13) Zgl „ lq1 [ Rs^pm1 15

[0096] By substituting equation (13) into equation (9), an optimal torque distribution strategy can be obtained: pml RslWpm2 + R-slV pm\ _____RplWpml_____ RslWpm2 + pml (14)

[0097] Under this torque distribution strategy, the direct axis current idi and the quadrature axis current iqi of the first armature windings 2-1 and the direct axis current id2 and the quadrature axis current iq2 of the second armature windings 4-4 can be expressed as, 5 respectively, (15) i 2T^ < 91 ^pm! ■ 2Ze2 / 92 ^j^pm2 22 10 25

[0098] The dual mechanical ports permanent magnet motor with composite stator and the torque distribution method therefor according to an embodiment of the present invention have at least one of the following advantages: 10

[0099] 1. The dual mechanical ports permanent magnet motor of the present invention utilizes a composite stator and a dual-rotor structure, and by controlling the currents of the armature windings of the first armature stator and the second armature stator respectively, it can realize the distribution of the output power of the dual-mechanical ports, so as to satisfy the requirements of different working conditions, thereby making the output efficiency and 15 the output torque of the permanent magnet motor reach the optimal value.

[00100] 2. In the dual mechanical ports permanent magnet motor of the present invention, the first rotor and the second rotor are both not equipped with permanent magnets and windings, which avoids the heat dissipation difficulty of rotor windings that may be caused by the rotor-excited type motor and the demagnetization problem that may be caused by the permanent 20 magnets at the side of rotor under high temperature, thereby improving the reliability of the 22 10 25 permanent magnet motor.

[00101] 3. In the dual mechanical ports permanent magnet motor of the present invention, the first armature stator and the second armature stator share the permanent magnet flux generated by the neodymium-iron-boron permanent magnet blocks of the composite stator, which 5 effectively improves the utilization rate of the permanent magnets of this type of motor and reduces the leakage of magnetism at the end of the permanent magnets.

[00102] 4. In the dual mechanical ports permanent magnet motor of the present invention, the excitation teeth are added to the first stator, and excitation strengthening / weakening can be achieved by supplying the current to the excitation winding, so as to make up for the defects 10 that the magnetic field of the permanent magnet motor is unadjustable; and when demagnetization occurs in the permanent magnet of the inner stator, the existence of the excitation winding can build up the air-gap magnetic field to guarantee the normal operation of the motor.

[00103] 5. The dual mechanical ports permanent magnet motor of the present invention can 15 change the operation mode of the motor by changing the armature current applied to the first and second armature windings to meet the requirements of different working conditions, so that the torque output by the motor and the efficiency of the motor reach the optimum, and at the same time, due to adding the excitation winding, the air gap magnetic field of the motor can be adjustable, which strengthens the motor's weak magnetism and torque output capability. 20

[00104] Although some embodiments of the present inventive concept have been shown and described, those of ordinary skill in the art can understand that variations can be made to these embodiments without departing from the principles and spirit of the present inventive concept, and the scope of the present invention is defined by the claims and their equivalents.

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