Permanent magnet motor stator winding and permanent magnet motor

Abstract

The invention provides a permanent magnet motor stator winding and a permanent magnet motor, the permanent magnet motor comprises a rotor, a stator core and stator windings, the number of magnetic pole pairs of rotor permanent magnets is p, the surface of the stator core is provided with stator slots, and at least two sets of stator windings are arranged in the stator slots; the number of magnetic pole pairs of the armature magnetic field generated by one set of stator winding is p, and the number of magnetic pole pairs of the armature magnetic field generated by at least one set of stator winding is kp; the ratio of the fundamental wave frequency of the input current of each set of stator winding to the number of magnetic pole pairs of an armature magnetic field generated by each set of stator winding is the same; wherein k is an odd number. According to the invention, the odd-order harmonic component of the armature magnetic field is injected in the space and time domain, and the odd-order harmonic component can interact with the odd-order harmonic magnetic field generated by the permanent magnet of the permanent magnet motor to generate an extra torque component, thereby improving the torque of the permanent magnet motor.

Description

Technical Field

[0001] The present invention relates to the technical field of permanent magnet motors, and in particular to a stator winding of a permanent magnet motor and a permanent magnet motor. Background Art

[0002] Due to the physical structure of a three-phase permanent magnet motor, that is, the symmetry of the three-phase permanent magnet motor and the phase difference of the currents, when three-phase and multiples of three-phase harmonic currents are applied, the applied harmonic currents will cancel each other out in space. Therefore, the harmonic components generated by the stator winding cannot interact with the corresponding harmonic components in the permanent magnet magnetic field to generate additional torque components, and the utilization rate of the harmonic magnetic field generated by the permanent magnet is relatively low. Summary of the Invention

[0003] The technical problem to be solved by the present disclosure is to overcome the defect that the utilization rate of the harmonic magnetic field generated by the permanent magnet of a permanent magnet motor in the prior art is relatively low, and to provide a stator winding of a permanent magnet motor and a permanent magnet motor.

[0004] The present disclosure solves the above technical problem by the following technical solutions:

[0005] In a first aspect, a stator winding of a permanent magnet motor is provided. The permanent magnet motor includes a rotor, a stator core, and a stator winding. Stator slots are formed on the surface of the stator core, and at least two sets of stator windings are provided in the stator slots;

[0006] The number of pole pairs of the armature magnetic field generated by one set of stator windings is p, and the number of pole pairs of the armature magnetic field generated by at least one set of stator windings is kp; the ratio of the fundamental wave frequency of the current applied to each set of stator windings to the number of pole pairs of the armature magnetic field generated by each set of stator windings is the same; where k is an odd number.

[0007] Optionally, each set of stator windings in the stator slots is arranged along the radial direction of the rotor.

[0008] Optionally, the wire types used for the stator windings include Litz wire, round copper wire, and flat copper wire, and the order of the suppression effects of each wire type on AC loss is Litz wire > round copper wire > flat copper wire.

[0009] Optionally, the rotor includes a permanent magnet with p pole pairs. By adjusting the phase of the current applied to the stator winding that generates an armature magnetic field with kp pole pairs, the phase of the armature magnetic field generated by the stator winding is made to differ by 90 degrees from the phase of the kth harmonic magnetic field of the permanent magnetic field generated by the permanent magnet;

[0010] And / or, adjusting the amplitude of the current applied to the stator winding that generates an armature magnetic field with kp pole pairs, under the condition of the same total copper loss of the motor, to maximize the motor torque.

[0011] Optionally, by changing the number of turns and / or the number of parallel windings and / or the wire type dimensions, the space occupancy ratio of each set of windings in the slot of the stator slot is adjusted, so that the motor can improve the motor torque as much as possible under the condition of the same total copper loss.

[0012] Optionally, the topological structure of the stator winding is a double-layer overlapping winding or a single-layer overlapping winding or a wave winding.

[0013] Optionally, the stator winding that generates an armature magnetic field with a pole pair number of p is a three-phase winding or a multi-phase winding, and the number of phases of the stator winding that generates an armature magnetic field with a pole pair number of kp is the same as the number of phases of the stator winding that generates an armature magnetic field with a pole pair number of p.

[0014] In a second aspect, a permanent magnet motor is provided, characterized in that the permanent magnet motor includes a rotor, a stator core, and the permanent magnet motor stator winding described in any one of the above.

[0015] On the basis of conforming to the common knowledge in the art, the above preferred conditions can be combined arbitrarily to obtain the preferred examples of the present disclosure.

[0016] The positive and progressive effect of the present disclosure is that: in the present disclosure, there is at least one set of stator windings in which the pole pair number of the generated armature magnetic field is an odd multiple of the pole pair number of the permanent magnet motor rotor, and a current with a fundamental wave frequency k times that of the rotor magnetic field fundamental wave frequency is passed through this set of windings, realizing the injection of harmonic components in the armature magnetic field in the space and time domains. The harmonic components can interact with the harmonic magnetic field generated by the permanent magnets of the permanent magnet motor to generate additional torque components, improving the utilization rate of the harmonic magnetic field generated by the permanent magnets and increasing the torque of the permanent magnet motor. Description of the Drawings

[0017] Figure 1 It is a schematic structural diagram of a permanent magnet motor provided by an exemplary embodiment of the present disclosure;

[0018] Figure 2 It is a schematic diagram of the relationship between the currents passed through each set of permanent magnet motor stator windings provided by an exemplary embodiment of the present disclosure;

[0019] Figure 3 It is a schematic diagram comparing the torque generated by a permanent magnet motor and the torque generated by a traditional motor provided by an exemplary embodiment of the present disclosure;

[0020] Figure 4 It is a schematic diagram of the winding wire type layout of the stator slot where the stator winding of a permanent magnet motor is located provided by an exemplary embodiment of the present disclosure;

[0021] Figure 5 It is a schematic diagram of the arrangement of the A-phase winding of the flat copper wire double-layer short-pitch overlapping winding in a permanent magnet motor provided by an exemplary embodiment of the present disclosure;

[0022] Figure 6 Schematic diagram of the arrangement of the A-phase winding of the Litz wire single-layer winding in a permanent magnet motor provided by an exemplary embodiment of the present disclosure. Detailed implementation manners

[0023] The present disclosure will be further described below by way of embodiments, but the present disclosure is not limited to the scope of the described embodiments.

[0024] In the embodiments of the present disclosure, prefix words such as "first" and "second" are only used to distinguish different described objects, and have no limiting effect on the position, order, priority, quantity or content of the described objects. The use of ordinal numbers and other prefix words for distinguishing described objects in the embodiments of the present disclosure does not constitute a limitation on the described objects. For the statements of the described objects, refer to the description in the claims or the context of the embodiments, and no redundant limitation should be constituted because of the use of such prefix words. In addition, in the description of this embodiment, unless otherwise specified, the meaning of "a plurality" is two or more.

[0025] Embodiment 1

[0026] Figure 1 Schematic diagram of the structure of a permanent magnet motor provided by an exemplary embodiment of the present disclosure.

[0027] The permanent magnet motor includes a stator and a rotor. The stator includes a stator core 101 and stator slots 102. The rotor includes permanent magnets 103 and a rotor 104. The number of pole pairs of the rotor permanent magnets is p. Stator slots 102 are formed on the surface of the stator core 101. Stator windings are embedded in the stator slots 102, and at least two sets of stator windings are provided in the stator slots 102.

[0028] The number of pole pairs of the armature magnetic field generated by one set of stator windings is p, and the number of pole pairs of the armature magnetic field generated by at least one set of stator windings is kp. The ratio of the fundamental wave frequency of the current passed through each set of stator windings to the number of pole pairs of the armature magnetic field it generates is the same. Wherein, k is an odd number.

[0029] In one embodiment, the value of k is 3.

[0030] Specifically, the number of pole pairs of the rotor is denoted as p. It is assumed that a first set of stator windings and a second set of stator windings are provided in the stator slots 102. The number of pole pairs of the armature magnetic field generated by the first set of stator windings is p, that is, the first set of stator windings is arranged with conventional p pairs of poles, and the generated armature magnetic field is a p-pole rotating magnetic field. The number of pole pairs of the armature magnetic field generated by the second set of stator windings is 3p, that is, the second set of windings is arranged with 3p pairs of poles, and the generated armature magnetic field is a 3p-pole rotating magnetic field. The fundamental wave frequency of the current passed through the second set of stator windings is three times that of the first set of stator windings.

[0031] Figure 2 Schematic diagram of the relationship between currents applied to the stator windings of a different set of permanent magnet motors provided by an exemplary embodiment of the present disclosure. Figure 2 In the figure, the horizontal axis represents the electrical angle, and the vertical axis represents the current amplitude. The solid line represents the current I 1 , and the dashed line represents the current I 2 , I 1 and I 2 are respectively the currents applied to two different sets of stator windings of the permanent magnet motor.

[0032] When k is 3, by arranging the pole pairs of at least one set of stator windings to be three times the pole pairs of the rotor's magnetic poles, a third harmonic component in space is introduced. The third harmonic in space generally refers to the third harmonic component of the magnetic field generated due to the motor structure and the distribution of the stator windings. The fundamental frequency of the current applied to the stator winding with the pole pairs of the armature magnetic field being 3p is k times the fundamental frequency of the current applied to the stator winding with the pole pairs of the armature magnetic field being p, introducing a third harmonic component in the time domain. The third harmonic in the time domain generally refers to the harmonic component whose frequency in the time domain is three times the fundamental frequency of a periodic signal.

[0033] The permanent magnets of the rotor generate third harmonics both in space and time. Therefore, it is necessary to inject third harmonic components of the armature magnetic field in both the space and time domains to make full use of the third harmonic magnetic field generated by the permanent magnets, generating an additional torque component and improving the torque of the permanent magnet motor. Refer to Figure 3 , Figure 3 The new type of hybrid winding motor in the figure is the permanent magnet motor in this embodiment. The traditional motor is usually a traditional double-layer overlapping flat copper wire winding motor. Compared with the traditional motor, the torque generated by the permanent magnet motor in this embodiment is increased compared with that of the traditional motor.

[0034] In this embodiment, the pole pairs of the armature magnetic field generated by at least one set of stator windings are 3p. The fundamental frequency of the current applied to the stator winding with the pole pairs of the armature magnetic field being 3p is 3 times the fundamental frequency of the current applied to the stator winding with the pole pairs of the armature magnetic field being p, realizing the injection of triple and multiple harmonic currents in both space and time domains. The magnetic field generated by this set of stator windings can interact with the harmonic magnetic field generated by the permanent magnets of the permanent magnet motor to generate an additional torque component, enabling the harmonic magnetic field generated by the permanent magnets to be effectively utilized, thereby improving the torque of the permanent magnet motor.

[0035] The value of k can be odd numbers such as 3, 5, 7, 9, etc., which can be specifically selected according to the actual situation and are not particularly limited herein. If the value of k is 5, it can be used to utilize the fifth harmonic magnetic field generated by the permanent magnet to generate an additional torque component. In one embodiment, each set of stator windings in the stator slots 102 is deployed along the radial direction of the rotor 104.

[0036] In one embodiment, the value of k is 3, and the permanent magnet motor is a three-phase permanent magnet motor. The number of pole pairs of the armature magnetic field generated by one set of stator windings in each stator slot is p, and the number of pole pairs of the armature magnetic field generated by at least one set of stator windings in each stator slot is 3p; the ratio of the fundamental frequency of the current passed through each set of stator windings to the number of pole pairs of the armature magnetic field generated by it is the same.

[0037] In this embodiment, the injection of third harmonic current in the spatial and time domains is realized. The harmonic components generated by the stator windings can interact with the harmonic magnetic field generated by the permanent magnets of the permanent magnet motor to generate an additional torque component, enabling the harmonic magnetic field generated by the permanent magnets to be effectively utilized, thereby improving the torque density of the permanent magnet motor and thus increasing the torque of the permanent magnet motor.

[0038] Assume that there are two sets of stator windings in the stator slot 102, and the two sets of stator windings occupy different positions in the stator slot 102. The first set of stator windings can be wound with flat copper wires and placed at the bottom of the stator slot 102 where the leakage magnetic field has less influence, ensuring a high overall slot fill factor. The second set of stator windings can be wound with loose wires or Litz wires and placed at the slot opening position in the stator slot 102 where the leakage magnetic field has greater influence, which can suppress the winding eddy current loss caused by the leakage magnetic field.

[0039] In this embodiment, multiple stator windings can use different wire types and be placed at different positions in the stator slot 102, which can significantly suppress the winding eddy current loss caused by the leakage magnetic field at the slot opening position while ensuring a high overall slot fill factor.

[0040] In one embodiment, the wire type of the stator winding near the rotor in the stator slot 102 has a better effect on suppressing the AC loss than the wire type of the stator winding far from the rotor in the stator slot 102.

[0041] At the position near the rotor in the stator slot 102 (such as Figure 4 shown at the slot opening 201), the wire type of the stator winding has a better effect on suppressing the AC loss than at the position far from the rotor in the stator slot 102 (such as Figure 4As shown, the wire type used for the stator winding at the bottom of the slot (202). In traditional flat copper wire overlapping windings, due to the large cross-sectional area of a single conductor and relatively severe magnetic leakage at the motor slot opening, the AC loss problem of the winding is severe. To reduce the AC loss of the winding and ensure a relatively high slot fill factor of the motor, flat copper wire is used for the stator winding far from the rotor in the stator slot 102, while a wire type with a better effect of suppressing AC loss is used for the stator winding close to the rotor in the stator slot 102. In addition, using two sets of windings with different wire types has more advantages than using only one set of windings. In addition to AC loss, a larger part of the copper loss of the motor is DC loss. Therefore, if only one set of windings is used, it is impossible to achieve a balance between DC loss and AC loss. Selecting flat wire will result in larger AC loss, and selecting Litz wire will result in larger DC loss. However, two sets of windings can better achieve the balance between DC loss and AC loss, realizing relatively low AC loss without causing a sharp increase in DC loss.

[0042] In this embodiment, a wire type with a better effect of suppressing AC loss is set at the opening of the stator slot 102, which can make full use of the advantages of various wire types, significantly suppress the eddy current loss of the winding while ensuring a high overall slot fill factor, and improve the operating efficiency of the motor.

[0043] To achieve the effects in the above embodiments, various different methods can be selected.

[0044] In one embodiment, the wire types used for the stator winding include Litz wire, round copper wire, and flat copper wire. The effect of suppressing AC loss for each wire type is Litz wire > round copper wire > flat copper wire. The effect of suppressing DC loss for each wire type is Litz wire < round copper wire < flat copper wire.

[0045] In one embodiment, the rotor includes a permanent magnet with a pole pair number of p. By adjusting the phase of the current applied to the stator winding that generates an armature magnetic field with a pole pair number of kp, the phase of the armature magnetic field generated by the stator winding is made to differ by 90 degrees from the phase of the kth harmonic magnetic field of the permanent magnetic field generated by the permanent magnet.

[0046] It can be understood that the phase of the current applied to at least one set of stator windings is adjusted according to the phase of the kth harmonic magnetic field of the permanent magnetic field generated by the permanent magnet, so that the phase of the current applied to at least one set of stator windings differs by 90 degrees from the phase of the kth harmonic magnetic field of the permanent magnetic field generated by the permanent magnet.

[0047] In this embodiment, the phase of the current applied to at least one set of stator windings differs by 90 degrees from the phase of the kth harmonic magnetic field of the permanent magnetic field generated by the permanent magnet, which can better utilize the kth harmonic magnetic field generated by the permanent magnet to generate an additional torque component, thereby improving the torque of the permanent magnet motor.

[0048] In one embodiment, the amplitude of the current passing through the stator winding with the number of pole pairs of the generated armature magnetic field being kp is adjusted to maximize the motor torque under the condition that the total copper loss of the motor is the same.

[0049] In this embodiment, the amplitude of the current passing through the stator winding with the number of pole pairs of the generated armature magnetic field being kp is adjusted to maximize the motor torque under the condition that the total copper loss of the motor is the same, so as to better utilize the k - th harmonic magnetic field generated by the permanent magnet and generate an additional torque component, thereby increasing the torque of the permanent magnet motor.

[0050] In one embodiment, by changing the number of turns and / or the number of parallel conductors and / or the wire type dimensions, the proportion of the space occupied by each set of windings in the slot space of the stator slot 102 is adjusted to maximize the motor torque as much as possible under the condition that the total copper loss of the motor is the same.

[0051] Specifically, the proportion of the space occupied by each set of windings in the stator slot 102 can be designed with the goal of maximizing the torque under the premise of keeping the total copper loss the same. The proportion of the two sets of windings affects not only the magnitude of the motor torque generated by using the fundamental wave and harmonic waves of the permanent magnet, but also the copper loss of the motor windings. Through finite - element simulation of the motor, the AC loss and DC loss in the stator winding of the permanent magnet motor can be calculated. Different sets of windings use different wire types, and the order of the suppression effect of each wire type on AC loss is Litz wire > round copper wire > flat copper wire, and the order of the suppression effect of each wire type on DC loss is Litz wire < round copper wire < flat copper wire. By adjusting the proportion of each set of windings using different wire types, the magnitude of the torque generated by using the harmonic magnetic field of the permanent magnet can be adjusted, and while achieving a high slot fill factor (i.e., low DC loss), the AC loss can be significantly reduced, realizing the maximum total motor torque under the condition of the same total copper loss. The above - mentioned proportion can be adjusted by changing the number of turns, the number of parallel conductors, and the wire type dimensions of each set of windings.

[0052] In this embodiment, according to different motor requirements, by changing the proportion of each set of windings, the motor torque is maximized as much as possible under the condition that the total copper loss of the motor is the same, thereby increasing the torque of the motor.

[0053] In one embodiment, the topological structure of the stator winding is a double - layer overlapping winding or a single - layer overlapping winding or a wave winding.

[0054] The specific wire type and topological structure of the stator winding can be determined according to the actual situation.

[0055] Figure 5 It is a schematic diagram of the arrangement of the A - phase winding of a flat copper wire double - layer short - pitched overlapping winding in a permanent magnet motor provided by an exemplary embodiment of the present disclosure. Figure 6 It is a schematic diagram of the arrangement of the A - phase winding of a Litz wire single - layer winding in a permanent magnet motor provided by an exemplary embodiment of the present disclosure. Figure 5 andFigure 6 The slot numbers in Figure 1 are numbered counterclockwise from stator slot 102 in Figure 1 as stator slot No. 1 for 36 stator slots.

[0056] In one embodiment, the stator winding is a three-phase winding or a multi-phase winding, and the number of phases of the flat copper wire winding is the same as that of the Litz wire winding.

[0057] An exemplary embodiment of the present disclosure also provides a permanent magnet motor. The permanent magnet motor includes a rotor, a stator core, and the permanent magnet motor stator winding of any one of the above.

[0058] In this embodiment, the harmonic components of three and multiples of three of the armature magnetic field are introduced in the space and time domains. The harmonic components generated by the stator winding can interact with the harmonic magnetic field generated by the permanent magnet of the permanent magnet motor to generate additional torque components, so that the harmonic magnetic field generated by the permanent magnet can be effectively utilized, thereby improving the torque density of the permanent magnet motor and thus improving the torque of the permanent magnet motor.

[0059] Although the specific embodiments of the present disclosure have been described above, those skilled in the art should understand that this is only an example. The protection scope of the present disclosure is defined by the appended claims. Without departing from the principles and essence of the present disclosure, those skilled in the art can make various changes or modifications to these embodiments, but these changes and modifications all fall within the protection scope of the present disclosure.

Claims

1. A permanent magnet motor stator winding, characterized in that: The permanent magnet motor comprises a rotor, a stator core and a stator winding, the number of magnetic pole pairs of the rotor permanent magnet is p, a stator slot is provided on the surface of the stator core, and at least two sets of stator windings are provided in the stator slot; There is a set of stator windings generating an armature magnetic field with a pole pair number of p, and there is at least one set of stator windings generating an armature magnetic field with a pole pair number of kp; the fundamental frequency of the current flowing through each set of stator windings is the same as the ratio of the pole pair number of the armature magnetic field generated by each set of stator windings; wherein k is an odd number.

2. The permanent magnet motor stator winding according to claim 1, characterized in that: Each set of stator windings in the stator slots is arranged along the radial direction of the rotor.

3. The permanent magnet motor stator winding according to claim 1, characterized in that: The wire types used in the stator winding include Litz wire, round copper wire and flat copper wire, and the suppression effect of each wire type on AC loss is ranked as Litz wire>round copper wire>flat copper wire.

4. The permanent magnet motor stator winding according to claim 1, characterized in that: The rotor comprises a permanent magnet having a magnetic pole pair number of p, and the phase of the current passed through the stator winding having a magnetic pole pair number of kp of the generated armature magnetic field is adjusted so that the phase of the armature magnetic field generated by the stator winding differs by 90 degrees from the phase of the kth harmonic magnetic field of the permanent magnetic field generated by the permanent magnet; And / or, adjusting the amplitude of the current flowing into the stator winding whose pole pair number of the generated armature magnetic field is kp, so as to maximize the motor torque under the condition that the total copper loss of the motor is the same.

5. The permanent magnet motor stator winding according to claim 1, characterized in that: By changing the number of turns and / or the number of parallel windings and / or the linear size, the space occupied by each set of windings in the stator slot is adjusted, so as to increase the motor torque as much as possible under the condition of the same total copper loss of the motor.

6. The permanent magnet motor stator winding according to any one of claims 1 to 5, characterized in that: The topological structure of the stator winding is a double-layer winding, a single-layer winding or a wave winding.

7. The permanent magnet motor stator winding according to any one of claims 1 to 5, characterized in that: The stator winding whose pole pair number of the generated armature magnetic field is p is a three-phase winding or a multi-phase winding, and the number of phases of the stator winding whose pole pair number of the generated armature magnetic field is kp is the same as the number of phases of the stator winding whose pole pair number of the generated armature magnetic field is p.

8. A permanent magnet motor, characterized in that: The permanent magnet motor comprises a rotor, a stator core and a permanent magnet motor stator winding according to any one of claims 1 to 7.

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