Hybrid excitation magnetic circuit structure, motor with the structure and control method thereof

Abstract

The application provides a hybrid excitation magnetic circuit structure, a motor with the structure and a control method of the motor. The hybrid excitation magnetic circuit structure provides basic magnetic flux through a permanent magnet rotor assembly and dynamically adjusts the magnetic flux through an electric excitation winding assembly. Only by switching the direction of the electric excitation current, the main air gap magnetic field can be superimposed and enhanced or partially offset. In the constant torque area, the first direction current is passed to superimpose the magnetic field and improve the main air gap magnetic flux density, thereby significantly enhancing the motor output torque. In the constant power area, the second direction current is passed to offset part of the magnetic flux, thereby expanding the motor speed regulation range. Thus, the motor can adapt to various working condition requirements and realize wide-range and high-efficiency operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electric machines, in particular to a hybrid excitation magnetic circuit structure, an electric machine with the structure and a control method thereof. BACKGROUND

[0002] In the current rapid development of automobile electrification, the performance of the electric drive system as the core of vehicle power directly affects the vehicle power response, range and running stability. Among them, permanent magnet motor, with the core advantages of high torque density, high efficiency and low noise, has become the mainstream choice of automobile electric drive system and is widely used in the driving scene of pure electric and hybrid electric vehicles, providing a foundation for efficient vehicle operation. The electrically excited motor can flexibly control the excitation magnetic field by adjusting the excitation current, and can realize the operation of magnetic field enhancement or field weakening, which has certain application value in some scenes that require magnetic field adjustment.

[0003] For the automobile electric drive system, the electric machine needs to operate stably under different working conditions, and the core involves two key working intervals of constant torque region and constant power region. The constant torque region is the low-speed running stage of the electric machine, which needs to output stable torque to meet the power demand of vehicle starting, acceleration, climbing and other scenes. The torque density of this interval directly determines the low-speed power performance of the vehicle. The constant power region is the high-speed running stage of the electric machine, which needs to keep the output power stable and the torque decreases with the increase of speed to meet the demand of vehicle high-speed cruising scene. The running range and efficiency of this interval directly affect the high-speed driving ability and range performance of the vehicle.

[0004] However, the existing permanent magnet motor and electrically excited motor have certain technical defects in these two core intervals. In the constant torque region, although the initial torque density of the permanent magnet motor is high, it is limited by the inherent magnetic flux characteristics of the permanent magnet and cannot be further improved by external adjustment. It is difficult to meet the demand of higher torque in the scenes of vehicle heavy load starting and steep slope climbing. Although the electrically excited motor can realize magnetic field enhancement by increasing the excitation current, the excitation winding will produce additional copper loss, resulting in a significant decrease in motor efficiency, and the torque density improvement is limited during the magnetic field enhancement process, which is difficult to match the initial torque advantage of the permanent magnet motor. In the constant power region, the permanent magnet motor has limited field weakening capability due to the unadjustable permanent magnet flux, and when the speed rises to a certain threshold, the magnetic circuit is easily saturated, resulting in a decrease in power output, which cannot meet the wide range demand of vehicle high-speed cruising. Although the electrically excited motor can realize field weakening by reducing the excitation current to expand the high-speed running range, the motor torque decays quickly during the field weakening process, and the problem of low torque density is more prominent in the high-speed interval, which is difficult to meet the demand of vehicle high-speed power and energy saving.

[0005] Therefore, how to overcome the technical limitations of the existing two types of electric machines and meet the comprehensive demand of high torque in the constant torque region, wide range and high efficiency in the constant power region has become a problem to be solved. SUMMARY

[0006] The application aims to provide a hybrid excitation magnetic circuit structure capable of meeting different working condition requirements, a motor with the structure and a control method thereof.

[0007] To achieve the above-mentioned purpose, the application provides a hybrid excitation magnetic circuit structure, comprising a stator and a rotor, wherein the stator is arranged inside the rotor, and a main air gap is formed between the stator and the rotor.

[0008] The stator comprises a permanent magnet armature winding assembly and an electric excitation winding assembly, wherein the permanent magnet armature winding assembly and the electric excitation winding assembly are coaxially arranged, and the electric excitation winding assembly is connected to both ends of the permanent magnet armature winding assembly.

[0009] The rotor comprises an electromagnetic rotor assembly and two groups of permanent magnet rotor assemblies, wherein the electromagnetic rotor assembly and the two groups of permanent magnet rotor assemblies are coaxially arranged, the electromagnetic rotor assembly comprises end magnetic conductors distributed outside the two groups of permanent magnet rotor assemblies, and an electromagnetic rotor monomer is arranged between the two groups of permanent magnet rotor assemblies.

[0010] When the motor operates in a constant torque region, a first direction current is passed through the electric excitation winding assembly, a magnetic field generated by the electric excitation winding assembly is emitted from the stator side, guided and constrained by the end magnetic conductors and the electromagnetic rotor monomer, and finally returns to the stator side via the end magnetic conductors, the permanent magnet rotor assemblies and the electromagnetic rotor monomer on the rotor side, and the magnetic field generated by the electric excitation winding assembly and the magnetic field generated by the permanent magnet rotor assemblies are superimposed in the main air gap.

[0011] When the motor operates in a constant power region, a second direction current is passed through the electric excitation winding assembly, a magnetic field generated by the electric excitation winding assembly is emitted from the stator side, guided and constrained by the electromagnetic rotor monomer and the end magnetic conductors, and finally returns to the stator side via the electromagnetic rotor monomer, the permanent magnet rotor assemblies and the end magnetic conductors on the rotor side, and the magnetic field generated by the electric excitation winding assembly and the magnetic field generated by the permanent magnet rotor assemblies are partially cancelled in the main air gap.

[0012] In a further technical solution, the permanent magnet armature winding assembly comprises a permanent magnet armature winding and a stator core, the permanent magnet armature winding is wound on the stator core, and the electric excitation winding assembly is connected to both side ends of the stator core and located inside the permanent magnet armature winding.

[0013] In a further technical solution, the electric excitation winding assembly comprises an electric excitation winding and a winding support holder, a side surface of the winding support holder is provided with an accommodation groove, the electric excitation winding is wound in the accommodation groove, and the winding support holder is fixedly connected with the stator core.

[0014] Further, the winding support holder is made of a magnetic conductive material.

[0015] Further, an insulating member is arranged between the winding support holder and the permanent magnet armature winding.

[0016] Further, axial heat dissipation holes are arranged on the winding support holder, the axial heat dissipation holes pass through the accommodating groove and the other side of the winding support holder, and are uniformly distributed in the circumferential direction; radial heat dissipation holes are arranged on the end magnetic conductors, the radial heat dissipation holes pass through the inner and outer circumferential surfaces of the end magnetic conductors, and are uniformly distributed in the circumferential direction; the areas of the axial heat dissipation holes and the radial heat dissipation holes account for 6%-8% of the total magnetic conductive area of the winding support holder and the end magnetic conductors.

[0017] Further, the permanent magnet rotor assembly includes a rotor core and permanent magnets, the permanent magnets are embedded in the rotor core; the permanent magnets include N-pole permanent magnet groups and S-pole permanent magnet groups, the N-pole permanent magnet groups and S-pole permanent magnet groups are alternately and uniformly distributed along the circumferential direction of the rotor core, and the positions of the permanent magnets in the two groups of permanent magnet rotor assemblies are aligned in the axial direction.

[0018] Further, the electromagnetic rotor monomer includes an electromagnetic yoke ring and a salient pole magnetic conductor, the salient pole magnetic conductors are uniformly distributed along the inner circumferential surface of the electromagnetic yoke ring, the positions of the salient pole magnetic conductors correspond to the N-pole permanent magnet groups or S-pole permanent magnet groups in the permanent magnet rotor assemblies on both sides, the number of the salient pole magnetic conductors is equal to or a divisor of the number of the N-pole permanent magnet groups or S-pole permanent magnet groups of the permanent magnet rotor assemblies.

[0019] According to a second aspect of the present application, a hybrid excitation synchronous motor is provided, which includes the hybrid excitation magnetic circuit structure as described above, further includes a sensor assembly for detecting the rotating speed of the motor, and a controller electrically connected with the sensor assembly, the permanent magnet armature winding and the electric excitation winding; the controller is configured to:

[0020] determine the operating condition of the motor according to the rotating speed detected by the sensor assembly;

[0021] when the motor operates in the constant torque region, control the electric excitation winding to pass a first direction current, so that the magnetic field generated by the electric excitation winding and the magnetic field generated by the permanent magnet rotor assembly are superimposed in the main air gap, realizing the magnetic field increasing operation in the constant torque region;

[0022] When the motor operates in the constant power region, the controller controls the electric excitation winding to pass a current in the second direction, and the magnetic field generated by the electric excitation winding partially offsets the magnetic field generated by the permanent magnet rotor assembly in the main air gap, so that the motor operates in the constant power region with reduced magnetism.

[0023] According to the third aspect of the present application, a control method of the hybrid excitation synchronous motor is also provided, which is used for controlling the hybrid excitation synchronous motor as described above, and the hybrid excitation synchronous motor further comprises a current detection assembly for detecting the armature current in the permanent magnet armature winding, and the control method comprises the following steps: (1) threshold determination: the rated speed nn of the motor and the armature current threshold It are stored in advance, the rated speed nn is the critical speed in the constant torque region and the constant power region, and the armature current threshold It is the critical current for judging whether the magnetism needs to be increased; (2) real-time signal acquisition: the current speed n and the current armature current I of the motor are continuously acquired through the sensor assembly; (3) operation region judgment:

[0024] when n≤nn n and I≥I t , it is determined that the motor operates in the constant torque region and the magnetism needs to be increased, and the controller outputs the current control signal in the first direction;

[0025] when n≤nn n and I<I t , it is determined that the motor operates in the constant torque region and the magnetism does not need to be increased, and the controller outputs the zero current control signal;

[0026] when n>nn n , it is determined that the motor operates in the constant power region and the magnetism needs to be reduced, and the controller outputs the current control signal in the second direction.

[0027] Compared with the prior art, the hybrid excitation magnetic circuit structure, the motor with the structure and the control method of the motor provided by the present application have at least the following beneficial effects:

[0028] The structure provides the basic magnetic flux through the permanent magnet rotor assembly and dynamically adjusts the magnetic flux through the electric excitation winding assembly, and only needs to switch the direction of the electric excitation current, so as to realize the superposition enhancement or partial offset of the magnetic field in the main air gap: the first direction current is passed in the constant torque region (such as the low-speed heavy-load scene), the superposition magnetic field enhances the magnetic flux density in the main air gap, and the output torque of the motor is significantly enhanced; the second direction current is passed in the constant power region (such as the high-speed light-load scene), and part of the magnetic flux is offset to suppress the increase of the back electromotive force, so as to expand the speed regulation range of the motor, thereby being able to adapt to various working condition requirements.

[0029] In addition, by arranging the end magnetic conductor and the electric excitation winding assembly on the stator side and arranging the electromagnetic rotor monomer on the rotor side, the electric excitation magnetic flux can be effectively guided to pass through the main air gap, the disorder diffusion of the electric excitation magnetic flux to the non-target area is avoided, the leakage magnetic loss is greatly reduced, more electric excitation magnetic flux participates in the magnetic field superposition of the main air gap, the magnetic field superposition of the main air gap is reduced, and the adjustment sensitivity and response efficiency of the electric excitation to the main air gap magnetic field are significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of these drawings, wherein:

[0031] Figure 1 is the overall structure diagram of the hybrid excitation magnetic circuit structure provided by the embodiments of the present application;

[0032] Figure 2 is the partial cutaway structure diagram of the hybrid excitation magnetic circuit structure provided by the embodiments of the present application;

[0033] Figure 3 is the exploded view of the hybrid excitation magnetic circuit structure provided by the embodiments of the present application;

[0034] Figure 4 is the cross-sectional structure schematic diagram of the stator provided by the embodiments of the present application;

[0035] Figure 5 is the exploded view of the electric excitation winding assembly provided by the embodiments of the present application;

[0036] Figure 6 is the schematic diagram of the stator and the rotor forming the main air gap provided by the embodiments of the present application (wherein the red color is the N-pole permanent magnet group, and the green color is the S-pole permanent magnet group);

[0037] Figure 7 is the exploded view of the rotor provided by the embodiments of the present application (wherein the red color is the permanent magnet group corresponding to the salient pole);

[0038] Figure 8 is the magnetic flux schematic diagram when the electric excitation winding is not energized in the embodiments of the present application;

[0039] Figure 9 is the magnetic flux schematic diagram when the electric excitation winding is energized in the first direction in the embodiments of the present application (wherein the green small arrow is the electric excitation magnetic flux);

[0040] Figure 10is a schematic diagram of the magnetic flux in the electric excitation winding of the embodiment of the present application when a current in the second direction is passed therethrough (wherein the red arrow is the electric excitation magnetic flux);

[0041] Figure 11 is a schematic diagram of the cooperation relationship of the winding support cage and the end magnetic conductor in forming the heat dissipation gas channel in the embodiment of the present application;

[0042] Figure 12 is a schematic diagram of the constant torque zone and the constant power zone in the embodiment of the present application;

[0043] Figure 13 is a flow chart of the control method of the hybrid excitation synchronous motor in the embodiment of the present application;

[0044] wherein:

[0045] 1 - stator; 2 - rotor; 3 - main air gap; 11 - permanent magnet armature winding assembly; 111 - permanent magnet armature winding; 112 - stator core; 12 - electric excitation winding assembly; 121 - electric excitation winding; 122 - winding support cage; 123 - accommodating groove; 122a - axial heat dissipation hole; 21 - end magnetic conductor; 21a - radial heat dissipation hole; 22 - permanent magnet rotor assembly; 221 - rotor core; 222 - permanent magnet; 222A - N-pole permanent magnet group; 222B - S-pole permanent magnet group; 23 - electromagnetic rotor monomer; 231 - electromagnetic yoke ring; 232 - salient pole magnetic conductor. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work are within the scope of protection of the present application.

[0047] It should be noted that all the directionality indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative position relationship, movement condition, etc. between the components in a certain specific posture (as shown in the drawings), and if the specific posture changes, the directionality indications also change accordingly.

[0048] In addition, the technical solutions in each of the embodiments of the present application can be combined with each other, but it must be based on the fact that a person of ordinary skill in the art can realize it, and when the combination of the technical solutions appears to be contradictory or unachievable, it should be considered that the combination of the technical solutions does not exist and is not within the scope of protection claimed by the present application.

[0049] As Figure 1As shown, the embodiment provides a hybrid excitation magnetic circuit structure, which includes a stator 1 and a rotor 2. The stator 1 is arranged inside the rotor 2, i.e. an outer rotor and inner stator structure. The main air gap 3 is formed between the stator 1 and the rotor 2.

[0050] Figure 2 As shown in the partial cross-sectional view of the hybrid excitation magnetic circuit structure, Figure 1 As shown in the partial cross-sectional view of the hybrid excitation magnetic circuit structure, Figure 3 As shown in the partial cross-sectional view of the hybrid excitation magnetic circuit structure, Figure 2 and Figure 3 The stator 1 includes a permanent magnet armature winding assembly 11 and an electric excitation winding assembly 12. The permanent magnet armature winding assembly 11 is coaxially arranged with the electric excitation winding assembly 12, and the electric excitation winding assembly 12 is connected to both ends of the permanent magnet armature winding assembly 11.

[0051] The rotor 2 includes an electromagnetic rotor assembly and two groups of permanent magnet rotor assemblies 22. The electromagnetic rotor assembly and the two groups of permanent magnet rotor assemblies 22 are coaxially arranged. The electromagnetic rotor assembly includes end magnetic conductors 21 distributed outside the two groups of permanent magnet rotor assemblies 22, and an electromagnetic rotor monomer 23 located between the two groups of permanent magnet rotor assemblies.

[0052] By arranging the electric excitation winding assembly 12 on the stator side and the end magnetic conductors 21 and the electromagnetic rotor monomer 23 on the rotor side, the electric excitation magnetic flux can be effectively guided to pass through the main air gap between the stator 1 and the rotor 2, avoiding the disorderly diffusion of the electric excitation magnetic flux to non-target areas, greatly reducing the magnetic leakage loss, and enabling more electric excitation magnetic flux to participate in the magnetic field of the main air gap. The magnetic field is superimposed and offset, which improves the adjustment sensitivity and response efficiency of the electric excitation to the main air gap magnetic field.

[0053] As shown in the partial cross-sectional view of the hybrid excitation magnetic circuit structure, Figure 4 The permanent magnet armature winding assembly 11 includes a permanent magnet armature winding 111 and a stator core 112. The permanent magnet armature winding 111 is wound on the stator core 112. The electric excitation winding assembly 12 is connected to both sides of the stator core 112 and located inside the permanent magnet armature winding 111. By arranging the electric excitation winding assembly 12 at this position, the spare space at the end of the stator core can be fully utilized, and the compact design of the stator structure can be realized.

[0054] In addition, the electric excitation winding assembly 12 is directly connected to the stator core 112, so that the electric excitation system and the permanent magnet armature system share the same core structure, eliminating the need for independent excitation core design, significantly simplifying the overall structure and reducing material costs. At the same time, the stator core 112 as a high magnetic permeability medium can provide a directional magnetic path for the electric excitation magnetic field, guiding the electric excitation magnetic flux to be efficiently transmitted to the rotor side, while restricting its diffusion to non-target areas, reducing magnetic leakage loss, and improving the adjustment efficiency of the electric excitation.

[0055] The structure of the electric excitation winding assembly 12 is as shown in Figure 5As shown, in the present embodiment, the electric excitation winding assembly comprises an electric excitation winding 121 and a winding support holder 122, wherein the winding support holder 122 is provided with a receiving groove 123 on the side surface, and the electric excitation winding 121 is tightly wound in the receiving groove 123 to form a regular annular excitation unit, and the electric excitation winding 121 is coated with a copper wire paint film. The winding support holder 122 is made of a magnetic conductive material and is used to guide more electric excitation magnetic flux into the main magnetic circuit. The winding support holder 122, together with the stator core 112, the end magnetic conductive body 21 and the electromagnetic rotor monomer 23, forms a main magnetic circuit of the electric excitation magnetic flux, and restricts and guides the electric excitation magnetic flux, thereby reducing the magnetic flux loss and improving the regulation efficiency of the electric excitation.

[0056] The axial end of the winding support holder 122 is fixedly connected to the end of the stator core 112 by welding, bolt fastening or the like, thereby effectively resisting the vibration during the operation of the motor and avoiding the insulation wear or connection loosening of the winding due to displacement.

[0057] In order to block the electrical contact risk between the electric excitation winding assembly 12 and the permanent magnet armature winding assembly 11, a gap of 2mm to 4mm can be left between the winding support holder 122 and the permanent magnet armature winding assembly 11, and air is used as a natural insulating medium. In addition, a high-temperature-resistant insulating filler (such as a silicone rubber insulating paste) can also be filled in the interval area to further improve the electrical insulation reliability. In a possible embodiment, an insulating partition plate made of high-strength insulating material (such as glass fiber reinforced epoxy resin) can also be arranged between the electric excitation winding assembly 12 and the permanent magnet armature winding assembly 11.

[0058] Since the hybrid excitation motor adds an additional electric excitation winding, the total heat generation is higher than that of the same power permanent magnet motor. In the high excitation demand working condition (such as starting, low speed large torque, strong magnetic regulation), the copper loss of the electric excitation winding will increase significantly, further increasing the total heat dissipation load. In addition, since the installation position of the electric excitation winding is adjacent to the armature winding, the copper loss heat of the two will be superimposed, causing the local area of the stator end to become a weak point of heat dissipation.

[0059] Therefore, the present embodiment also optimizes the design of the heat dissipation structure of the electric excitation winding.

[0060] In a possible embodiment, the winding support holder 122 is provided with an axial heat dissipation hole 122a, and the axial heat dissipation holes 122a are uniformly arranged in the circumferential direction. Part of the heat generated by the electric excitation winding 121 is conducted away through the stator core 112, and part of the heat is conducted through the axial heat dissipation holes 122a.

[0061] In order to further improve the heat dissipation effect, radial heat dissipation holes 21a can also be provided on the end magnetic conductive body 21 in the circumferential direction. Figure 11As shown, when the rotor rotates, the centrifugal force generated by rotation drives the air to flow outward along the radial cooling holes 21a, thereby forming an air flow suction effect, which helps to dissipate the heat of the electric excitation winding 121 through air flow, thereby effectively reducing the operating temperature of the electric excitation assembly and ensuring the stability and durability of the hybrid excitation structure under high power density operation.

[0062] It should be noted that, in order to reduce the influence on the magnetic conductivity, the hole diameter of the axial cooling hole 122a and the radial cooling hole 21a should not be too large. Considering the cooling effect and magnetic conductivity, the area of the axial cooling hole 122a and the radial cooling hole 21a should be 6-8% of the total magnetic conductivity area of the winding support cage 122 and the end magnetic conductor 21, for example, 6%, 7%, 8%, so as to have certain cooling effect without affecting the magnetic conductivity.

[0063] In addition, the axial cooling hole 122a and the radial cooling hole 21a should be as far away from the main magnetic flux path as possible, that is, away from the contact surface of the winding support cage 122 and the stator core 112, and the contact surface of the end magnetic conductor 21 and the permanent magnet rotor assembly 22. Therefore, the axial cooling hole 122a can be arranged at the corresponding position of the accommodating groove 123, and the axial cooling hole 122a penetrates the accommodating groove 123 and the other side of the winding support cage 122, thereby avoiding the contact surface of the stator core 112. The radial cooling hole 21a is arranged to penetrate the inner and outer circumferential surfaces of the end magnetic conductor 21, thereby avoiding the contact surface of the end magnetic conductor 21 and the permanent magnet rotor assembly 22. Further, the main magnetic flux path can be determined by simulation experiment and the like, so as to more accurately determine the arrangement position of the cooling hole.

[0064] As shown in Figure 6 and Figure 7 The permanent magnet rotor assembly 22 includes a rotor core 221 and permanent magnets 222, and the permanent magnets 222 are embedded in the rotor core 221. The permanent magnets include N-pole permanent magnet groups 222A and S-pole permanent magnet groups 222B, which are uniformly distributed alternately and spaced along the circumferential direction of the rotor core 221, and the permanent magnets in the two groups of permanent magnet rotor assemblies are aligned in the axial direction. By radially embedding the permanent magnets and alternately distributing the polarities, the permanent magnet flux can be guided to pass through the main air gap 3 in the radial direction to form the main magnetic flux, thereby improving the proportion of the main magnetic flux to enhance the external function, while ensuring the uniform distribution of the magnetic field in the circumferential direction and optimizing the output performance of the motor.

[0065] Referring to Figure 7, the electromagnetic rotor unit 23 comprises an electromagnetic yoke ring 231 and salient pole magnetic conductors 232 which are uniformly distributed along the inner circumferential surface of the electromagnetic yoke ring 231. The positions of the salient pole magnetic conductors 232 correspond to the N-pole permanent magnet groups or S-pole permanent magnet groups in the two permanent magnet rotor assemblies. In the embodiment, the salient pole magnetic conductors 232 correspond to the N-pole permanent magnet groups (the red permanent magnet groups in the figure) in the two permanent magnet rotor assemblies in position and number.

[0066] It should be noted that the number of the salient pole magnetic conductors 232 should be equal to or a divisor of the number of the N-pole permanent magnet groups or S-pole permanent magnet groups in the permanent magnet rotor assemblies. For example, if there are 8 N-pole permanent magnet groups, the number of the salient pole magnetic conductors 232 should be 8, 4, 2 or 1. However, since it is difficult to realize uniform distribution of the electrically excited magnetic field with 1 or 2 salient pole magnetic conductors 232, 8 or 4 salient pole magnetic conductors 232 are preferred.

[0067] If the salient pole magnetic conductors of the electromagnetic rotor are unevenly distributed or the number thereof does not match the number of the pole pairs of the permanent magnets, the coupling efficiency of the electrically excited magnetic flux and the permanent magnetic flux will be low, and the magnetic field increasing or decreasing effect cannot be accurately realized. By uniformly distributing the salient pole magnetic conductors and matching the number thereof with the number of the pole pairs of the permanent magnets, it can be ensured that the electrically excited magnetic flux can be efficiently coupled with the permanent magnetic flux, and the magnetic field increasing or decreasing effect on the main magnetic field can be accurately realized when energized, thereby ensuring the adjustment accuracy of the motor under different working conditions.

[0068] Referring to Figure 8 When the electrically excited windings 121 are not energized, the N-pole magnetic flux generated by the permanent magnets 222 of the permanent magnet rotor assembly 22 first passes through the main air gap 3 in a radial direction, passes through the teeth, yoke and tooth portion of the stator core 112, and then returns to the S-pole of the permanent magnets 222 through the main air gap 3, thereby forming a main magnetic flux path to do work outside.

[0069] Referring to Figure 9 When the electrically excited windings 121 are energized with a first direction current, the magnetic field generated by the electrically excited windings 121 and the magnetic field generated by the permanent magnet rotor assembly 22 are superimposed in the main air gap 3, and the permanent magnetic flux and the electrically excited magnetic flux are connected in parallel to output energy outside, thereby improving the torque density.

[0070] Referring to Figure 10 When the electrically excited windings 121 are energized with a second direction current, the magnetic field generated by the electrically excited windings 121 and the magnetic field generated by the permanent magnet rotor assembly 22 are partially canceled in the main air gap 3, thereby realizing a demagnetizing operation to expand the working interval.

[0071] The first direction (field-enhancing direction) and the second direction (field-reducing direction) of the current of the field excitation winding 121 are determined in combination with the winding direction of the field excitation winding, the polarity direction of the permanent magnet of the permanent magnet rotor assembly and the Ampere rule. The winding direction of the field excitation winding (for example, from clockwise to counterclockwise) or the polarity direction of the permanent magnet is different, and the first direction and the second direction of the current of the field excitation winding 121 are also different. The core criterion is to ensure that the coupling direction of the field excitation magnetic field and the permanent magnet magnetic field in the main air gap meets the field-enhancing / reducing requirement.

[0072] The existing synchronous motor is mostly single excitation, which cannot balance the high torque output in the constant torque region and the wide speed regulation in the constant power region, and lacks a precise control method for the hybrid excitation structure, which limits the operation efficiency.

[0073] Therefore, another embodiment of the present application also provides a hybrid excitation synchronous motor, which comprises a hybrid excitation magnetic circuit structure as described above, and further comprises a sensor assembly for detecting the motor speed, and a controller electrically connected with the sensor assembly, the permanent magnet armature winding and the field excitation winding. Wherein, the controller judges the motor operating condition according to the speed detected by the sensor assembly, such as Figure 12 as shown:

[0074] When the motor operates in the constant torque region, the first direction current is controlled to flow into the field excitation winding, so that the magnetic field generated by the field excitation winding and the magnetic field generated by the permanent magnet rotor assembly are superimposed in the main air gap, realizing the field-enhancing operation in the constant torque region;

[0075] When the motor operates in the constant power region, the second direction current is controlled to flow into the field excitation winding, so that the magnetic field generated by the field excitation winding and the magnetic field generated by the permanent magnet rotor assembly are partially canceled in the main air gap, realizing the field-reducing operation in the constant power region.

[0076] By integrating the foregoing hybrid excitation magnetic circuit structure, sensor assembly and controller, the excitation mode of the motor in different operating regions can be switched, the output torque is improved in the constant torque region, and the speed regulation range is expanded in the constant power region, so that the comprehensive operating performance and operating condition adaptability of the synchronous motor can be significantly improved.

[0077] The sensor assembly for detecting the motor speed can adopt a magneto-electric encoder or a Hall sensor, the detection end of which is fixed to the non-output end of the stator and is arranged opposite to the outer circumferential surface of the end magnetic conductor of the outer rotor assembly. The outer circumferential surface of the end magnetic conductor is provided with uniformly distributed protrusions or magnetic markers in the circumferential direction. Those skilled in the art can also measure the motor speed in other ways.

[0078] Preferably, the hybrid excitation synchronous motor can further comprise a current detection assembly for detecting the current in the permanent magnet armature winding, so as to comprehensively judge the motor operating condition according to the armature current and the speed.

[0079] According to another embodiment of the present application, a control method of a hybrid excitation synchronous motor is also provided, as shown in the following steps: Figure 13 (1) preset threshold determination: pre-storing the rated speed n n and the armature current threshold I t of the motor, wherein the rated speed n n is the critical speed between the constant torque region and the constant power region, and the armature current threshold I t is the critical current for determining whether the excitation needs to be increased; (2) real-time signal acquisition: continuously acquiring the current speed n and the current armature current I of the motor through a sensor assembly; (3) operation region determination:

[0080] when n≤n n and I≥I t , it is determined that the motor is in the constant torque region and needs to be operated with increased excitation, and the controller outputs a first direction current control signal;

[0081] In possible embodiments, the first direction current control signal is designed to control the size of the current in the electric excitation winding according to the size of the armature current, for example, a target armature current value can be set, and the size of the current in the electric excitation winding is dynamically controlled according to the difference between the actual armature current value and the target armature current value.

[0082] when n≤n n and I<I t , it is determined that the motor is in the constant torque region and does not need to be operated with increased excitation, and the controller outputs a zero current control signal, i.e. no current is passed through the electric excitation winding;

[0083] when n>n n , it is determined that the motor is in the constant power region and needs to be operated with decreased excitation, and the controller outputs a second direction current control signal.

[0084] Exemplarily, the second direction current control signal can be designed to control the current in the electric excitation winding according to the size of the motor speed, for example, the current in the electric excitation winding can be controlled to linearly increase with the increase of the motor speed.

[0085] The above method further subdivides the constant torque region, i.e. into a high load state requiring increased excitation operation and a low load state not requiring increased excitation operation. The high load state strengthens the excitation to improve the torque, and the low load state stops the electric excitation to reduce the loss. Through the multi-parameter cooperative judgment of the speed and the armature current, the accurate division and smooth switching of the constant torque region and the constant power region are realized.

[0086] The above only describes the embodiments of the present application, and it should be noted that those skilled in the art can make improvements without departing from the inventive concept of the present application, and these improvements are within the protection scope of the present application.

Claims

1. A hybrid excitation magnetic circuit structure, applied in an electric motor, characterized in that, The structure includes a stator and a rotor, the stator being disposed inside the rotor, and a main air gap being formed between the stator and the rotor; The stator includes a permanent magnet armature winding assembly and an electric excitation winding assembly. The permanent magnet armature winding assembly and the electric excitation winding assembly are coaxially arranged, and the electric excitation winding assembly is connected to both ends of the permanent magnet armature winding assembly. The rotor includes an electromagnetic rotor assembly and two sets of permanent magnet rotor assemblies. The electromagnetic rotor assembly and the two sets of permanent magnet rotor assemblies are coaxially arranged. The electromagnetic rotor assembly includes end magnetic conductors distributed on the outside of the two sets of permanent magnet rotor assemblies, and an electromagnetic rotor unit located between the two sets of permanent magnet rotor assemblies. When the motor is running in the constant torque region, the first direction current flows through the electric excitation winding assembly. The magnetic field generated by the electric excitation winding starts from the stator side and, under the guidance and constraint of the end magnetic conductor and the electromagnetic rotor unit, passes through the end magnetic conductor on the rotor side, the permanent magnet rotor assembly and the electromagnetic rotor unit, and finally returns to the stator side. The magnetic field generated by the electric excitation winding and the magnetic field generated by the permanent magnet rotor assembly are superimposed in the main air gap. When the motor is operating in the constant power region, a second directional current flows through the electric excitation winding assembly. The magnetic field generated by the electric excitation winding starts from the stator side and, under the guidance and constraint of the electromagnetic rotor unit and the end magnetic conductor, passes through the electromagnetic rotor unit, the permanent magnet rotor assembly and the end magnetic conductor on the rotor side, and finally returns to the stator side. The magnetic field generated by the electric excitation winding and the magnetic field generated by the permanent magnet rotor assembly partially cancel each other out in the main air gap.

2. The hybrid excitation magnetic circuit structure according to claim 1, characterized in that, The permanent magnet armature winding assembly includes a permanent magnet armature winding and a stator core. The permanent magnet armature winding is wound on the stator core, and the electric excitation winding assembly is connected to both ends of the stator core and located inside the permanent magnet armature winding.

3. The hybrid excitation magnetic circuit structure according to claim 2, characterized in that, The electric excitation winding assembly includes an electric excitation winding and a winding support retainer. A receiving groove is provided on one side of the winding support retainer, and the electric excitation winding is wound in the receiving groove. The winding support retainer is fixedly connected to the stator core.

4. The hybrid excitation magnetic circuit structure according to claim 3, characterized in that, The winding support cage is made of magnetically conductive material.

5. The hybrid excitation magnetic circuit structure according to claim 3, characterized in that, An insulating element is provided between the winding support cage and the permanent magnet armature winding.

6. The hybrid excitation magnetic circuit structure according to claim 3, characterized in that, The winding support cage has axial heat dissipation holes that penetrate the receiving groove and the other side of the winding support cage, and are evenly distributed in the circumferential direction. The end magnetic conductor has radial heat dissipation holes that penetrate the inner and outer circumferential surfaces of the end magnetic conductor, and are evenly distributed in the circumferential direction. The area of ​​the axial heat dissipation holes and the radial heat dissipation holes accounts for 6% to 8% of the total magnetic conductive area of ​​the winding support cage and the end magnetic conductor.

7. The hybrid excitation magnetic circuit structure according to claim 1, characterized in that, The permanent magnet rotor assembly includes a rotor core and permanent magnets, with the permanent magnets embedded in the rotor core. The permanent magnets include an N-pole permanent magnet group and an S-pole permanent magnet group, which are evenly distributed alternately along the circumference of the rotor core, and the permanent magnets in the two groups of permanent magnet rotor assemblies are aligned in the axial direction.

8. The hybrid excitation magnetic circuit structure according to claim 7, characterized in that, The electromagnetic rotor unit includes an electromagnetic yoke ring and salient pole magnets. The salient pole magnets are uniformly distributed along the inner circumferential surface of the electromagnetic yoke ring. The positions of the salient pole magnets correspond to the N-pole permanent magnet groups or S-pole permanent magnet groups in the permanent magnet rotor assemblies on both sides. The number of salient pole magnets is equal to, or an approximation of, the number of N-pole permanent magnet groups or S-pole permanent magnet groups in the permanent magnet rotor assembly.

9. A hybrid excitation synchronous motor, characterized in that, Including the hybrid excitation magnetic circuit structure as described in claim 1, it further includes a sensor assembly for detecting motor speed, and a controller electrically connected to the sensor assembly, the permanent magnet armature winding, and the electrically excited winding; the controller is configured to: The operating condition of the motor is determined based on the rotational speed detected by the sensor components; When the motor is running in the constant torque region, the first direction current is passed through the electric excitation winding, so that the magnetic field generated by the electric excitation winding and the magnetic field generated by the permanent magnet rotor assembly are superimposed in the main air gap, thereby realizing the magnetization operation in the constant torque region. When the motor is running in the constant power region, a second directional current is supplied to the electrically excited winding. The magnetic field generated by the electrically excited winding partially cancels out the magnetic field generated by the permanent magnet rotor assembly in the main air gap, thereby achieving demagnetization operation in the constant power region.

10. A control method for a hybrid excitation synchronous motor, used to control the hybrid excitation synchronous motor as described in claim 9, characterized in that, The hybrid excitation synchronous motor further includes a current detection component for detecting the armature current in the permanent magnet armature winding, and the control method includes: Step 1: Determine the preset threshold: Pre-store the rated speed n of the motor. n and armature current threshold I t The rated speed n n The armature current threshold I is the critical speed between the constant torque region and the constant power region. t The critical current used to determine whether magnetization is necessary; Step 2, Real-time signal acquisition: Continuously acquire the current motor speed n and current armature current I through sensor components; Step 3, Determine the operating range: When n≤n n And I≥I t When the current is determined to be in the constant torque region and magnetization is required, the controller outputs a first-direction current control signal. When n≤n n And I t When the current is determined to be in the constant torque region and no magnetization is required, the controller outputs a zero current control signal.​ When n>n n When the system is in the constant power region, it needs to operate with reduced magnetization, and the controller outputs a second-direction current control signal.

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