Electro-magnetic field modulation motor

Abstract

The invention provides an electro-magnetic field modulation motor. The electro-magnetic field modulation motor comprises a stator and a rotor, an air gap exists between the stator and the rotor, and the stator adopts an open slot structure; the stator comprises a stator iron core and a stator armature winding, the stator iron core is provided with a plurality of stator teeth, and the stator armature winding is wound on the stator teeth; the rotor comprises a rotor iron core, a rotor excitation winding and a rotor harmonic winding; the rotor iron core is provided with a plurality of rotor teeth and rotor tooth grooves formed by the adjacent rotor teeth; the rotor excitation windings are wound on the rotor teeth, and the rotor harmonic windings are distributed in the rotor tooth grooves; the rotor harmonic winding and the rotor excitation winding are connected through a rotary rectifier; according to the invention, non-working magnetic field harmonic waves in the air-gap magnetic field are used for supplying power to the rotor excitation winding, so that waste is turned into wealth.

Description

Technical Field

[0001] The invention belongs to the technical field of motors, and in particular relates to an electric excitation magnetic field modulation motor. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] With the rapid development of high-performance rare earth permanent magnet materials, permanent magnet motors using rare earth permanent magnets have significant advantages such as reliable operation, simple structure, low loss, and high efficiency, but there are also some defects. First, rare earth permanent magnet materials are becoming increasingly scarce and the cost is becoming increasingly high; second, the characteristics of permanent magnets themselves will limit the use of permanent magnet synchronous motors. For example, extreme conditions such as excessive temperature, strong impact or strong magnetic field may cause permanent magnets to lose magnetism; in addition, the air gap magnetic field of permanent magnet synchronous motors is difficult to adjust, and it is not easy to perform weak magnetic speed control. These defects have hindered the widespread application of permanent magnet synchronous motors.

[0004] Compared with permanent magnet motors, traditional electric excitation motors do not need to use rare earth permanent magnet materials, which can reduce the cost of use; at the same time, the excitation magnetic field can be adjusted by changing the size of the excitation current, so it has good speed regulation performance. However, there are many problems with the electric excitation motor itself: the traditional electric excitation motor uses brushes and slip rings to pass direct current into the rotor excitation winding, which is not only easy to cause sparks and arcs, but also causes brush wear after long-term use, affecting the insulation performance and service life of the motor; in addition, in the field of small and medium power applications, additional exciters are required to achieve electric excitation, which greatly increases the size and cost of the device. These problems limit the application scope of electric excitation motors.

[0005] There are two types of electrically excited motors: one is the traditional electrically excited synchronous motor, whose armature winding and field winding are located on the stator and rotor respectively, and have the same number of pole pairs; the other is the electrically excited magnetic field modulation motor, whose armature winding and field winding are located on the stator and rotor respectively, and there is a modulation unit, and the armature winding pole pair number is different from the field winding pole pair number. Both rotor excitation requires brushes, slip rings or AC exciter devices, which reduces their reliability.

[0006] The electromagnetic field modulation motor usually has a higher pole ratio and a higher torque density than the traditional electromagnetic synchronous motor. At the same time, due to the modulation effect, the air gap magnetic field of the electromagnetic field modulation motor has more harmonic components.

[0007] Therefore, how to utilize the harmonic components in the air gap of the magnetic field modulation motor as the energy source for rotor excitation, so as to "turn waste into treasure", realize brushless rotor excitation, and improve the working efficiency of the motor, is a technical problem that needs to be solved at present. Summary of the invention

[0008] In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides an electrically excited magnetic field modulation motor, which utilizes the harmonic components in the air gap magnetic field to achieve brushless excitation of the magnetic field modulation motor.

[0009] In order to achieve the above object, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides an electric excitation magnetic field modulation motor, comprising: a stator and a rotor;

[0011] There is an air gap between the stator and the rotor;

[0012] The stator comprises a stator core and a stator armature winding, wherein the stator core has a plurality of stator teeth, the stator armature winding is wound on the stator teeth, and the stator teeth are used as magnetic conductive blocks of the modulation unit;

[0013] The rotor comprises a rotor core, a rotor excitation winding and a rotor harmonic winding; the rotor core has a plurality of rotor teeth and rotor tooth slots formed by adjacent rotor teeth; the rotor excitation winding is wound on the rotor teeth, and the rotor harmonic winding is distributed in the rotor tooth slots;

[0014] The rotor harmonic winding and the rotor excitation winding are connected via a rotating rectifier.

[0015] One or more of the above technical solutions have the following beneficial effects:

[0016] The motor of the present invention does not need to use rare earth permanent magnet materials, has low cost, has high economic value and environmental protection significance, and overcomes the defect that permanent magnet motors are difficult to adjust the magnetic field; it does not rely on brushes and slip rings, does not have arcing, ring fire and other phenomena, avoids friction loss, and operates reliably; it also does not need to use an additional exciter, the excitation system is simple in design, occupies a small area, saves costs and can operate reliably.

[0017] The motor of the present invention utilizes the magnetic field to modulate the non-working harmonic magnetic field components in the air gap magnetic field of the motor to achieve brushless excitation and reliable operation of the motor; the harmonic excitation technology adopted by the present invention is essentially induction excitation, has good dynamic stability, faster response speed and shorter voltage recovery time, and utilizes the non-working harmonic magnetic field in the air gap magnetic field for rotor excitation, thereby improving the efficiency of the motor.

[0018] The modulation unit in the motor of the present invention is the stator tooth, and the manufacturing process is almost the same as the processing of the stator punching sheet of the traditional electric excitation synchronous motor, with a simple structure and low cost.

[0019] The motor of the present invention inherits the advantage of high power density of magnetic field modulation motor, and is not affected by brush slip ring or AC exciter. It can use non-working magnetic field harmonics in the air gap magnetic field to power the rotor excitation winding, realizing "turning waste into treasure".

[0020] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0022] Figure 1 It is a schematic diagram of the stator and rotor structure of the electric excitation magnetic field modulation brushless motor in the first embodiment of the present invention;

[0023] Figure 2 Schematic diagram of the structure of the stator core and winding (taking phase A as an example) of the brushless motor with electric excitation magnetic field modulation in the first embodiment of the present invention;

[0024] Figure 3 It is a structural schematic diagram of the rotor core and the excitation winding and harmonic winding of the brushless motor with electric excitation magnetic field modulation in the first embodiment of the present invention;

[0025] Figure 4 The air gap magnetic flux distribution diagram of the brushless motor modulated by the electric excitation magnetic field in the first embodiment of the present invention;

[0026] Figure 5 This is a diagram showing the FFT analysis result of the air gap magnetic flux density of the brushless motor modulated by the electric excitation magnetic field in the first embodiment of the present invention;

[0027] Figure 6 Schematic diagram of winding arrangement on the motor rotor of the electric excitation magnetic field modulation brushless motor in Embodiment 1 of the present invention, F represents the rotor excitation winding, H represents the rotor harmonic winding, and the two are connected through a rotating rectifier;

[0028] Figure 7 This is a waveform diagram of the rotor excitation current generated by the lower induction of the electric excitation magnetic field modulation brushless motor in the first embodiment of the present invention;

[0029] In the figure: 1, stator core, 2, rotor core, 3, stator armature winding, 4, rotor excitation winding, 5, rotor harmonic winding, 6, stator teeth, 7, stator yoke, 8, rotor teeth, 9, rotor yoke, 10, rotor tooth slots. DETAILED DESCRIPTION

[0030] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0031] It should be noted that the terms used herein are for describing specific embodiments only and are not intended to be limiting of exemplary embodiments according to the present invention.

[0032] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0033] Embodiment 1

[0034] like Figure 1-Figure 7 As shown, this embodiment discloses an electric excitation magnetic field modulation motor, comprising: a stator and a rotor; the gap between the stator and the rotor is an air gap;

[0035] The stator includes a stator core 1 and a stator armature winding 3; the stator core 1 is composed of Z s The stator armature winding 3 is wound on the stator teeth. The stator armature winding 3 is a three-phase winding controlled by a three-phase sinusoidal inverter circuit to generate a stator excitation magnetic field in the air gap. Figure 2 As shown, a three-phase symmetrical sinusoidal fundamental current is passed through the stator armature winding 3; the stator armature winding 3 is a three-phase double-layered winding; the stator adopts open slots and also plays the role of a magnetic conductive block of the modulation unit.

[0036] The rotor includes a rotor core 2, a rotor excitation winding 4 and a rotor harmonic winding 5; the rotor core 2 adopts a rotor hidden pole structure, the rotor core 2 has a plurality of rotor teeth 8 and a rotor tooth slot 10 formed by adjacent rotor teeth, and the rotor core 2 is composed of Z r The rotor tooth 8 is composed of a rotor tooth 8 and a rotor yoke 9. A single non-overlapping concentrated rotor excitation winding 4 is wound around each rotor tooth 8, and the rotor harmonic winding 5 is distributed in the rotor tooth slots.

[0037] This embodiment is described by taking a three-phase 12-slot / 22-pole motor as an example, but is not limited to this structure. The stator core 1 has a 12-slot structure, i.e., Z s is 12, and no permanent magnet is used. The number of magnetic blocks in the modulation unit is P f =Z s The rotor core 2 is a 22-pole structure, each pole structure is wound with a rotor excitation winding 4, the rotor excitation winding 4 is wound on the rotor teeth, a DC current is passed through the rotor excitation winding 4 to form alternating N poles and S poles, that is, the rotor excitation pole pair number P e is 11.

[0038] The newly added harmonic magnetic field modulated by the modulation unit is used as the working magnetic field, and the original magnetic field is used as the brushless excitation magnetic field. Since the stator teeth in this embodiment are also used as the modulation unit and play the role of the magnetic conductive block of the modulation unit, the functions of the modulation unit are to generate electromagnetic force to drive the motor to rotate; and to modulate the air gap magnetic field as a modulation unit to generate high-order harmonic magnetic field components. Only affected by the tooth width, the composition of the motor air gap modulation magnetic field will change, thereby affecting the performance of the motor.

[0039] In this embodiment, the gap between the stator and the rotor is an air gap; after current is passed through the stator armature winding 3, an air gap magnetic field is generated in the air gap. Under the influence of the modulation unit, the air gap magnetic field includes the main fundamental magnetic field and the 11th harmonic magnetic field, as well as other harmonic components.

[0040] In this embodiment, a rotor harmonic winding 5 is placed in a rotor slot 10; the coils of the rotor harmonic winding 5 are connected in series, and the number of pole pairs of the rotor harmonic winding 5 is |P f -P e |, cutting the air gap magnetic field to generate the same-phase AC electromotive force, and the rotor harmonic winding 5 is connected in series to become the source of rotor excitation energy.

[0041] In this embodiment, the number of pole pairs of the stator armature winding 3 is the same as the number of pole pairs of the newly added air gap magnetic field fundamental wave, and the magnetic field rotation speed is the same as the rotation speed of the newly added air gap magnetic field fundamental wave.

[0042] In this embodiment, a rotor harmonic winding 5 with one pole pair is placed in the rotor tooth slot 10, and the rotor harmonic winding 5 is connected to the rotor excitation winding 4 through a rotating bridge rectifier installed on the periphery of the rotor. Figure 6 As shown. The excitation coils of the rotor excitation winding 4 are connected in series, and the polarity of each excitation coil is set so that the polarity of the magnetomotive force of two adjacent magnetic poles is opposite, and the pitch of the rotor excitation winding 4 is 1. The rotating rectifier adopts a bridge uncontrolled rectifier circuit, and the switching device in the bridge uncontrolled rectifier circuit adopts a diode; the rotor harmonic winding 5 is connected to the AC side of the bridge uncontrolled rectifier circuit, and the rotor excitation winding 4 is connected to the DC side of the bridge uncontrolled rectifier circuit. Neither the rotor harmonic winding 5 nor the rotor excitation winding 4 uses an additional power supply for independent current excitation.

[0043] According to the basic theory of magnetic field modulation, the number of spatial air gap harmonics is |mP e ±nZ s |, m = 1, 3, 5…, n = 0, 1, 2… It can be seen that there are 1st, 11th, 23rd and other harmonic components in the air gap magnetic field.

[0044] In this embodiment, the finite element simulation of the motor can be obtained as follows Figure 4 The air gap magnetic flux distribution diagram shown in the figure shows that the 1st, 11th and 23rd harmonic contents are relatively high. The component diagram is shown in Figure 5shown.

[0045] The rotor harmonic winding 5 of one pole pair is fully linked with the first harmonic magnetic field in the air gap magnetic field, and they cut each other at different speeds to generate magnetomotive force.

[0046]

[0047] in, is the magnitude of the magnetic flux linkage of a receiving coil; N h is the number of turns of the rotor harmonic winding coil; E sh is the amplitude of the induced potential of the harmonic winding; θ j0 is the electrical angle of the initial position of the rotor receiving winding; w1 and w2 are the rotor speed (11th harmonic magnetic field speed) and 1st harmonic magnetic field speed respectively; b a1h is the first harmonic component of the air gap magnetic field; l is the axial length of the motor; τ is the pole moment.

[0048] The operation control principle of an electric excitation magnetic field modulation motor proposed in this embodiment is:

[0049] Step 1: First, through the magnetic field modulation theory, it is deduced that after adding the modulation unit magnetic conductive block, the air gap magnetic field generated by the rotor excitation unit is:

[0050]

[0051] Among them, P e P is the number of rotor excitation pole pairs; f is the number of magnetic blocks in the modulation unit; w e P e The angular velocity of the rotating magnetic field; B pe P e Pole magnetic induction intensity; B |Pf-Pe| For |P f -P e |The induced magnetic field strength of the opposite pole.

[0052] Therefore, the number of pole pairs of the newly added air gap magnetic field is |P f -P e |;

[0053] Specifically, in step 1.1, the air gap mainly contains P e and |P f -P e | sub-rotating magnetic field;

[0054] Step 1.2, when the number of magnetic field pole pairs generated by the stator armature winding is |P f -P e |, the motor works in the magnetic field modulation motor mode, and the pole ratio of the magnetic field modulation motor (the number of pole pairs of the rotating part / the number of pole pairs of the armature winding) is:

[0055]

[0056] Step 2: Then, assume that the speed of the excitation unit is Ω e rpm, analyzing the motion characteristics of the newly added harmonic magnetic field, the speed of the fundamental wave of the newly added air gap magnetic field can be obtained as:

[0057]

[0058] Specifically, in step 2.1, the speed of the excitation unit, i.e. the rotor speed, is Ω e RPM, the speed of the fundamental wave of the newly added air gap magnetic field is:

[0059]

[0060] Therefore, the frequency of the current flowing through the stator winding is

[0061] Step 2.2, and the harmonic winding on the rotor is also in Ω e The speed of rotation is rpm, and the number of pole pairs of the harmonic winding magnetic field is |P f -P e |, due to the presence of a magnetic field in the air gap |P f -P e |Pole pairs The motor rotates at a speed of 100 rpm, thus inducing an AC voltage in the harmonic winding.

[0062] Step 2.3, it is then rectified by a rotating rectifier to provide a DC field winding. Since the flux generated by the field winding in the air gap has the same number of pole pairs as the stator fundamental magnetomotive force, they interact to produce torque.

[0063] Permanent magnet synchronous motors have significant advantages but require rare earth resources, while AC asynchronous motors are slightly cheaper but their performance and efficiency need to be improved. Therefore, electric excitation technology without permanent magnets and hybrid excitation technology with few permanent magnets have begun to become the forefront of research in academia and industry. When traditional wound-type electric excitation synchronous motors obtain DC excitation current, they need to be connected to the DC excitation power supply through brushes and slip rings. They have low reliability, poor cleanliness, and are difficult to achieve high-speed operation. At the same time, traditional electric excitation synchronous motors need to pass DC power into the rotor winding, which will increase copper loss and reduce torque density. Therefore, one of the important research directions is to study electric excitation motors based on magnetic field modulation and their brushless technology. First, the high pole ratio of the magnetic field modulation motor is used to achieve the high torque density of the motor. Secondly, the non-working harmonic magnetic field in the magnetic field modulation motor is used to realize the brushless electric excitation motor, realizing "turning waste into treasure".

[0064] The scheme of this embodiment does not rely on permanent magnets, eliminates brush slip rings and additional exciters, and adds subharmonic windings and rotating rectifiers on the rotor to achieve brushless operation of the motor; and adopts a high-pole ratio magnetic field modulation electric excitation motor structure to make the electric excitation motor have a higher torque density. At the same time, the non-working harmonic magnetic field in the air gap magnetic field of the magnetic field modulation motor is used to achieve brushless operation of the motor. Compared with ordinary electric excitation synchronous motors, the number of stator pole pairs of the electric excitation magnetic field modulation motor described in this embodiment is 1, and the number of rotor pole pairs is 11, which solves the contradiction that the increase of the number of pole pairs in the traditional synchronous electric excitation motor will reduce the stator magnetic flux in the same proportion, thereby increasing the product of the magnetic flux alternating frequency and the stator magnetic flux, thereby increasing the no-load back electromotive force, and increasing the torque and power density; at the same time, the motor described in this embodiment adds a set of rotor harmonic windings on the rotor, which can use the harmonic magnetic field in the air gap of the magnetic field modulation motor to generate harmonic magnetic field induced harmonic electromotive force, and the harmonic electromotive force provides excitation current to the rotor excitation winding through the rotating rectifier, thereby achieving brushless excitation. The motor described in this embodiment is completely based on electric excitation, does not use additional permanent magnetic materials and independent exciters, and has low cost and high reliability.

[0065] A finite element simulation model of the motor described in this embodiment is established. When a three-phase symmetrical sinusoidal fundamental current is passed through the stator armature winding, the following is obtained on the rotor excitation winding: Figure 7 The excitation current waveform is shown. Since the excitation winding itself has a large inductance, the excitation current will start from zero and gradually tend to a steady state, which contains more DC components and a small amount of pulsating current components. The simulation results illustrate the feasibility of the subharmonic excitation synchronous brushless motor proposed in this embodiment.

[0066] In summary, this embodiment is to solve the problems in the prior art that permanent magnet motors rely on expensive permanent magnet materials, traditional electrically excited synchronous motors rely on brush slip rings or independent excitation, and the copper loss of the rotor winding makes it difficult to break through the torque density. In this embodiment, every two excitation poles are a harmonic pole, and the corresponding slots are embedded with harmonic windings. The magnetic field is used to modulate the non-working harmonic magnetic field in the air gap of the motor to generate an induced current in the rotor harmonic winding to achieve brushless excitation. This embodiment completely relies on electrical excitation and does not rely on permanent magnets. At the same time, the brush slip ring and the exciter are eliminated to achieve brushless excitation. It has a simple structure, reliable operation, low cost, and good performance. It is suitable for electric vehicles, cranes, aerospace and other application fields.

[0067] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. An electric excitation magnetic field modulation motor, characterized in that: include: stator and rotor; There is an air gap between the stator and the rotor, and the stator adopts an open slot structure; The stator comprises a stator core and a stator armature winding, wherein the stator core has a plurality of stator teeth, and the stator armature winding is wound on the stator teeth; the stator teeth are used as magnetic conductive blocks of the modulation unit; The rotor comprises a rotor core, a rotor excitation winding and a rotor harmonic winding; the rotor core has a plurality of rotor teeth and rotor tooth slots formed by adjacent rotor teeth; the rotor excitation winding is wound on the rotor teeth, and the rotor harmonic winding is distributed in the rotor tooth slots; The rotor harmonic winding and the rotor excitation winding are connected via a rotating rectifier.

2. The electromagnetic field modulation motor according to claim 1, characterized in that: The stator armature winding adopts a three-phase double-layer winding, and the stator armature winding is controlled by a three-phase sinusoidal inverter circuit to generate a stator excitation magnetic field in the air gap.

3. The electromagnetic field modulation motor according to claim 1, characterized in that: The excitation coils of the rotor excitation winding are connected in series, and the polarity of each rotor excitation coil is set so that the polarities of the magnetomotive force of two adjacent magnetic poles are opposite.

4. The electromagnetic field modulation motor according to claim 1, characterized in that: The rotating rectifier adopts a bridge-type uncontrolled rectifier circuit, the rotor harmonic winding is connected to the AC side of the bridge-type uncontrolled rectifier circuit, and the rotor excitation winding is connected to the DC side of the bridge-type uncontrolled rectifier circuit.

5. The electromagnetic field modulation motor according to claim 1, characterized in that: The rotor harmonic winding has the same pole pair number as the fundamental wave magnetic field in the air gap magnetic field.

6. The electromagnetic field modulation motor according to claim 1, characterized in that: Current is passed through the stator armature winding to form alternating N poles and S poles.

7. The electromagnetic field modulation motor according to claim 1, characterized in that: The pole pair number of the rotor harmonic winding is |P f -P e |, cutting the air gap magnetic field to generate the same-phase AC electromotive force; the rotor harmonic windings are connected in series to become the source of rotor excitation energy; wherein, P f is the number of stator teeth, and the rotor excitation pole is 2P e .

8. The electromagnetic field modulation motor according to claim 1, characterized in that: The stator core adopts a 12-slot structure.

9. The electromagnetic field modulation motor according to claim 1, characterized in that: The stator armature winding is |P f -P e | opposite pole, where P f is the number of stator teeth, and the rotor excitation pole is 2P e .

10. The electromagnetic field modulation motor according to claim 1, characterized in that: The rotor core adopts a rotor hidden pole structure.

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