Doubly salient permanent magnet motor

Abstract

The utility model relates to a doubly salient permanent magnet motor. The utility model is suitable for the technical field of motor manufacturing of electrical engineering. The technical problem to be solved by the utility model is to provide a doubly salient permanent magnet motor. According to the technical scheme, the doubly salient permanent magnet motor comprises a stator core, a rotor core, armature windings and permanent magnets, and is characterized in that the stator core is provided with N stator teeth, a stator yoke of the stator core is divided by the N permanent magnets to form N stator yoke sections, and the N stator yoke sections are connected with the N stator teeth in a one-to-one correspondence mode.

Description

Technical Field

[0001] The utility model relates to a double-salient-pole permanent-magnet motor, which is applicable to the technical field of motor manufacturing in electrical engineering. Background Art

[0002] Doubly Salient Permanent Magnet (DSPM) motor is a new type of stator permanent magnet motor that just appeared in the 1990s. This type of motor is based on the structure of switched reluctance (SR) motor, and introduces permanent magnets on its stator yoke. Due to the introduction of high-performance permanent magnets, DSPM motor has the advantages of large output torque and simple structure, so it has attracted wide attention from the motor engineering community.

[0003] Figure 1 (a) is a double salient pole permanent magnet motor of an existing topological structure, including a stator core 1, a rotor core 2, an armature winding 3 and a permanent magnet 4. The outer contour of the stator core is circular. The stator core 1 and the rotor core 2 both adopt a salient pole structure, which cooperate to form an inner rotor structure. The stator core 1 is divided into four "E"-shaped stator core segments by the permanent magnet 4. The stator core 1 is composed of a stator yoke 11 and stator teeth 12; the rotor core 2 is composed of a rotor yoke 21 and rotor teeth 22; the permanent magnet is magnetized along the circumference of the stator, and the magnetization direction changes alternately along the circumference. The number of stator teeth 12 is 12, the number of rotor teeth 22 is 8, and the number of permanent magnets 4 is 4. The E-shaped stator core segment makes the permanent magnetic circuit of the middle stator tooth different from that of the side teeth, resulting in an asymmetric defect of the permanent magnetic circuit. At the same time, when the number of stator poles and rotor poles is combined to 12 / 8, the middle teeth of the E-type stator core segment are evenly distributed to the B-phase coil, causing the reverse electromotive force of B to be different from that of A and C phases, resulting in an unbalanced three-phase reverse electromotive force problem.

[0004] The conventional combination of the number of stator poles, the number of permanent magnets and the number of rotor poles used in the existing doubly salient permanent magnet motor minimizes the number of cycles of the cogging torque in one electrical cycle, which can cause the motor to generate a relatively large magnitude of cogging torque. Utility Model Content

[0005] The technical problem to be solved by the utility model is: to provide a double-salient-pole permanent-magnet motor in view of the above-mentioned problems.

[0006] The technical solution adopted by the utility model is: a double-salient pole permanent magnet motor, including a stator core, a rotor core, an armature winding and a permanent magnet, characterized in that: the stator core has N stator teeth, the stator yoke of the stator core is divided by N permanent magnets to form N stator yoke segments, and the N stator yoke segments are connected to the N stator teeth in a one-to-one correspondence.

[0007] The stator teeth are connected to the middle position of the stator yoke section connected thereto.

[0008] The stator pole number P of the stator core s , the number of permanent magnets P of the permanent magnets PM ,satisfy:

[0009] P s =12k;

[0010] P PM =12k;

[0011] k is a positive integer.

[0012] The rotor pole number P of the rotor core r =11k or 13k.

[0013] The outer contour of the stator core is circular or polygonal.

[0014] The rotor teeth of the rotor core are of a straight tooth structure or a helical tooth structure.

[0015] The stator and the rotor are matched to form an inner rotor structure or an outer rotor structure.

[0016] The beneficial effects of the utility model are as follows: in the utility model, the number of stator teeth, the number of stator poles and the number of permanent magnets are equal, the permanent magnets with alternating tangential magnetization are embedded in the stator yoke, the stator core block is cut into a plurality of stator core segments, each stator core segment is formed into a T shape by a stator yoke segment and stator teeth, and compared with the "E-type" stator core segment of the existing motor, the relative position relationship between the stator teeth 12 and the adjacent permanent magnets of the "T"-type stator core segment in the utility model is the same, thereby avoiding the problem of magnetic circuit asymmetry existing in the traditional E-type stator core segment.

[0017] In the utility model, the number of stator poles of the stator core and the number of permanent magnets of the permanent magnets are both 12k, and the number of rotor poles is designed to be 11k or 13k. The number of cogging torque cycles in one electrical cycle is the largest, and the cogging torque amplitude is the smallest. The combination of the number of stator poles and the number of rotor poles in the utility model can also eliminate the even harmonics of the opposite potential, further reducing the permanent magnet torque harmonics.

[0018] The utility model can effectively reduce the torque pulsation of the traditional double-salient permanent magnet motor by optimizing the combination of the number of stator poles, the number of rotor poles and the number of permanent magnets.

[0019] The utility model increases the amount of permanent magnets, thereby enhancing the permanent magnetic field and further improving the torque output capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1The topological comparison diagram of the existing motor and the motor in the embodiment of the present invention is shown: (a) the existing motor; (b) the motor 1 in the embodiment of the present invention; (c) the motor 2 in the embodiment of the present invention.

[0021] Figure 2 The star diagrams of the armature coils of the conventional motor and the motor of the present invention are compared as follows: (a) the conventional motor; (b) the motor 1 in the embodiment of the present invention; (c) the motor 2 in the embodiment of the present invention.

[0022] Figure 3 The three-phase back electromotive force of the existing motor is shown as follows: (a) waveform; (b) spectrum.

[0023] Figure 4 The three-phase phase electromotive force of motors 1 and 2 in the embodiment of the present invention is illustrated: (a) waveform; (b) spectrum.

[0024] Figure 5 A comparison diagram of the cogging torque waveforms of an existing motor and a motor in an embodiment of the present invention is shown.

[0025] Figure 6 The load torque comparison diagram of the existing motor and the motor in the embodiment of the present invention is shown: (a) waveform; (b) frequency spectrum.

[0026] In the figure: 1 is the stator core, 2 is the rotor core, 3 is the armature winding, 4 is the permanent magnet, 11 is the stator yoke, 12 is the stator teeth, 21 is the rotor yoke, and 22 is the rotor teeth. DETAILED DESCRIPTION

[0027] This embodiment is a double salient pole permanent magnet motor, including a stator core 1, a rotor core 2, an armature winding 3 and a permanent magnet 4. The outer contour of the stator core is circular. The stator core 1 and the rotor core 2 both adopt a salient pole structure, which cooperate to form an inner rotor structure. In some embodiments, an outer rotor structure can also be formed. The inner rotor structure motor is conducive to the heat dissipation of the permanent magnet and reduces the risk of demagnetization of the permanent magnet material; the outer rotor structure motor is conducive to improving the stator slot space, increasing the electrical load, and further improving the torque output capacity of the motor.

[0028] In this example, the outer contour of the stator core is circular or polygonal, which increases the amount of permanent magnets, strengthens the permanent magnetic field, and thus improves the torque output capacity. The rotor teeth of the rotor core are straight tooth structures or helical tooth structures. The rotor core teeth are designed as a helical slot structure, which is beneficial to reducing the slot torque amplitude.

[0029] When the inventors were studying the method of suppressing torque pulsation of double-salient permanent magnet motors, they found that the defect in the prior art was caused by factors such as many harmonics of permanent magnet torque and large amplitude of cogging torque. They found that the defect could be solved by optimizing the combination of the number of stator poles, the number of rotor poles and the number of permanent magnets. For this reason, the number of stator poles P of the stator core 1 in this embodiment is s, the number of permanent magnets P of permanent magnet 4 PM , the number of rotor poles P of rotor core 2 r , satisfying P s =12k,P PM =12k, Pr=11k or 13k, where k is a positive integer.

[0030] In this example, the stator core 1 is evenly divided into 12k stator core segments by 12k permanent magnets 4. Each stator core segment has a circular arc stator yoke segment and a stator tooth. The stator tooth is connected to the middle position of the stator yoke segment connected to it, forming a "T"-shaped stator core segment. The permanent magnets are magnetized tangentially along the stator circumference, and the magnetization direction changes alternately along the circumference tangentially.

[0031] like Figure 1 (b) and Figure 1 As shown in (c), two double-pole permanent magnet motors are provided in this example, including Motor 1 and Motor 2, wherein Motor 1 has 12 stator teeth 12, 11 rotor teeth 22, and 12 permanent magnets 4; Motor 2 has 12 stator teeth 12, 13 rotor teeth 22, and 12 permanent magnets 4.

[0032] like Figure 2 As shown in (a), when 12 stator teeth and 8 rotor teeth are used, on the one hand, the B-phase armature coils are all assigned to stator teeth numbered 2, 5, 8, and 11, resulting in an unbalanced back-EMF between phases; on the other hand, there is no reverse connection between the coils in the same phase, and the even-order harmonic back-EMF induced by the armature coils cannot be offset, which deteriorates the sinusoidality of the reverse EMF waveform. Figure 2 (b) and Figure 2 As shown in (c), the combination of the number of stator poles, the number of rotor poles, and the number of permanent magnets proposed in this embodiment not only eliminates the problem of unbalanced three-phase back electromotive force, but also cleverly improves the connection method of the armature coils in the same phase. The two coils with a mechanical angle difference of 180° have a fundamental electrical angle difference of 180°, and the even harmonic electrical angles are equal. The two coils are connected in reverse, which can enable each phase winding to obtain a larger fundamental flux, so that the fundamental components in the two coils are superimposed, and all even harmonics completely cancel each other out, so that there are no even harmonics in the phase winding, and the sinusoidality of the phase flux and the back electromotive force is improved.

[0033] like Figure 3 As shown, in the existing motor, Figure 3 In (a), it can be found that the sinusoidal nature of the back EMF waveform of each phase is poor, and the waveform of phase B is different from that of phases A and C. In addition, Figure 3 As can be seen from (b), the three-phase back EMF is unbalanced and there are a large number of even harmonics. These defects will cause the motor to generate a large number of permanent magnet torque harmonics, thereby generating torque pulsation.

[0034] like Figure 4 As shown, in the motors 1 and 2 of the present embodiment, when the number of stator poles is 12, the number of rotor poles is 11 and 13, and the number of permanent magnets is 12, the back electromotive force is three-phase symmetrical, and there are no even harmonics, and the waveform has good sinusoidal properties. When acting with a three-phase sinusoidal current, no permanent magnet torque harmonics are generated, effectively eliminating a factor causing load torque pulsation.

[0035] Figure 5 A comparison diagram of the cogging torque waveforms of the existing motor and the motor of the present invention is given. According to the formula LCM(P PM , P r ) / P r , it can be obtained that the number of cogging torque cycles of the existing motor and the motor of the present invention in one electrical cycle is 1 and 12 respectively. The larger the number of cycles, the smaller the cogging torque amplitude. It can be found that compared with the traditional motor, the cogging torque pulsation of the motor of the present invention is almost negligible.

[0036] Figure 6 Given the existing motor (P s =12,P r =8,P PM =4) and the motor of this embodiment (P s =12,P r =11 and 13, P PM =12) Under the same copper loss condition, a steady-state load torque comparison diagram is obtained. The torque pulsation of the existing motor is 114.1%, while the torque pulsations of the motors 1 and 2 in this embodiment are 1.7% and 1.3% respectively, and the torque pulsation is significantly suppressed.

[0037] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A double-salient permanent magnet motor, comprising a stator core, a rotor core, an armature winding and a permanent magnet, characterized in that: The stator core has N stator teeth, armature windings are wound around the stator teeth, the stator yoke of the stator core is divided into N stator yoke segments by N permanent magnets, and the N stator yoke segments are connected to the N stator teeth in a one-to-one correspondence.

2. The doubly salient permanent magnet motor according to claim 1, characterized in that: The stator teeth are connected to the middle position of the stator yoke section connected thereto.

3. The doubly salient permanent magnet motor according to claim 1 or 2, characterized in that: The stator pole number P of the stator core s , the number of permanent magnets P of the permanent magnets PM ,satisfy: P s =12k; P PM =12k; k is a positive integer.

4. The doubly salient permanent magnet motor according to claim 3, characterized in that: The rotor pole number P of the rotor core r =11k or 13k.

5. The doubly salient permanent magnet motor according to claim 4, characterized in that: The outer contour of the stator core is circular or polygonal.

6. The doubly salient permanent magnet motor according to claim 4, characterized in that: The rotor teeth of the rotor core are of a straight tooth structure or a helical tooth structure.

7. The doubly salient permanent magnet motor according to claim 4, characterized in that: The stator and the rotor are matched to form an inner rotor structure or an outer rotor structure.

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