CN115296500B - Double-stator low-speed permanent magnet synchronous motor and driving method - Google Patents

Abstract

The present invention provides a dual-stator low-speed permanent magnet synchronous motor and a driving method, which relate to the technical field of motors, and optimize the motor structure to a certain extent, make full use of the internal cavity of the motor, and improve the torque density of the motor. The dual-stator low-speed permanent magnet synchronous motor provided by the present invention includes an outer stator component, a rotor component, and an inner stator component; a cavity is formed inside the outer stator component, the inner stator component and the rotor component are both arranged in the cavity, the rotor component is located between the inner stator component and the outer stator component, and a first gap is formed between the outer ring wall surface of the rotor component and the inner ring wall surface of the outer stator component, and a second gap is formed between the inner ring wall surface of the rotor component and the outer ring wall surface of the inner stator component.

Description

Dual-stator low-speed permanent magnet synchronous motor and driving method

Technical Field

The present invention relates to the field of motor technology, and in particular to a dual-stator low-speed permanent magnet synchronous motor and a driving method.

Background technique

Among many high-end equipment manufacturing industries, some equipment needs to be driven by low-speed and high-torque drive systems, such as large industrial belt conveyors, cranes, scrapers, and grinders. Such electromechanical equipment consumes extremely high energy, so improving the energy-saving level of such equipment is beneficial to environmental protection and reduces the operating costs of factory equipment.

At present, most common low-speed, high-torque motor drive equipment adopts the driving mode of "normal-speed motor + reducer structure", but this driving mode can no longer meet the driving requirements of high-end equipment. Therefore, it is necessary to use high-torque density and high-efficiency rare earth permanent magnet motors to achieve low-speed direct drive of industrial equipment.

However, since most permanent magnet synchronous motors have a large diameter and a large internal cavity space, if the torque density (output torque) of the motor needs to be increased, the size of the motor will increase, which is not conducive to the miniaturization of the motor and limits the use environment of the motor.

Therefore, there is an urgent need to provide a dual-stator low-speed permanent magnet synchronous motor and a driving method to solve the problems existing in the prior art to a certain extent.

Summary of the invention

The purpose of the present invention is to provide a dual-stator low-speed permanent magnet synchronous motor and a driving method, so as to optimize the motor structure to a certain extent, make full use of the internal cavity of the motor, and improve the torque density of the motor.

A dual-stator low-speed permanent magnet synchronous motor provided by the present invention comprises an outer stator assembly, a rotor assembly and an inner stator assembly; a cavity is formed inside the outer stator assembly, the inner stator assembly and the rotor assembly are both arranged in the cavity, the rotor assembly is located between the inner stator assembly and the outer stator assembly, and a first gap is formed between the outer ring wall surface of the rotor assembly and the inner ring wall surface of the outer stator assembly, and a second gap is formed between the inner ring wall surface of the rotor assembly and the outer ring wall surface of the inner stator assembly.

Among them, the outer stator component includes an outer stator core and a first winding, and the inner stator component includes an inner stator core and a second winding; the inner ring wall surface of the outer stator core is formed with a plurality of first accommodating grooves, and the plurality of first accommodating grooves are evenly distributed along the circumference of the inner ring wall surface of the outer stator core, and the axis of the first accommodating grooves extends along the radial direction of the outer stator core, and the two long sides of the first winding are respectively arranged in two adjacent first accommodating grooves; the outer ring wall surface of the inner stator core is formed with a plurality of second accommodating grooves, and the plurality of second accommodating grooves are evenly distributed along the circumference of the outer ring wall surface of the inner stator core, and the axis of the second accommodating grooves extends along the radial direction of the outer stator core, and the two long sides of the second winding are respectively arranged in two different second accommodating grooves.

Specifically, the angle between the axis of the first starting receiving groove and the axis of the second starting receiving groove is β, so that the angle between the axis of the first adjacent receiving groove and the axis of the second adjacent receiving groove is β.

Furthermore, the first winding is a formed winding, and the second winding is a loose wire winding; the first accommodating groove is rectangular, and the open end of the second accommodating groove is a retracted structure.

Among them, the rotor assembly includes a rotor core and permanent magnets; a plurality of third accommodating grooves are formed on the outer ring wall of the rotor core, and the plurality of third accommodating grooves are evenly distributed along the circumference of the outer ring wall of the rotor core, and the axes of the third accommodating grooves extend along the radial direction of the rotor core; a plurality of fourth accommodating grooves are formed on the inner ring wall of the rotor core, and the plurality of fourth accommodating grooves are evenly distributed along the circumference of the inner ring wall of the rotor core, and the axes of the fourth accommodating grooves extend along the radial direction of the rotor core; the third accommodating grooves and the fourth accommodating grooves are arranged in a one-to-one correspondence, the permanent magnets are correspondingly arranged in the third accommodating grooves and the fourth accommodating grooves, and an air groove is formed between the third accommodating grooves and the fourth accommodating grooves.

Specifically, the permanent magnet includes NdFeB and ferrite, the ferrite in the third receiving slot is located between the NdFeB and the outer stator assembly; the ferrite in the fourth receiving slot is located between the NdFeB and the inner stator assembly.

Further, a ratio between a size of the NdFeB in the radial direction of the rotor core and a size of the ferrite in the radial direction of the rotor core is α.

The permanent magnet is magnetized along the tangent direction of the rotor core, and the magnetization directions of the permanent magnets in the third accommodating slot and the fourth accommodating slot whose axes coincide with each other are consistent.

Specifically, the air groove is filled with resin material.

Compared with the prior art, the dual-stator low-speed permanent magnet synchronous motor provided by the present invention has the following advantages:

The dual-stator low-speed permanent magnet synchronous motor provided by the present invention comprises an outer stator assembly, a rotor assembly and an inner stator assembly; a cavity is formed inside the outer stator assembly, the inner stator assembly and the rotor assembly are both arranged in the cavity, the rotor assembly is located between the inner stator assembly and the outer stator assembly, and a first gap is formed between the outer ring wall surface of the rotor assembly and the inner ring wall surface of the outer stator assembly, and a second gap is formed between the inner ring wall surface of the rotor assembly and the outer ring wall surface of the inner stator assembly.

From this analysis, it can be seen that by arranging the inner stator assembly and the rotor assembly in the cavity formed by the outer stator assembly, the rotor assembly is located between the inner stator assembly and the outer stator assembly, thereby fully utilizing the cavity formed by the outer stator assembly, and thus, without changing the overall size and volume of the motor, the torque density of the motor can be improved to a certain extent, and the overall performance of the motor can be improved.

Furthermore, since the rotor assembly in the present application can rotate independently relative to the inner stator assembly or independently relative to the outer stator assembly or simultaneously relative to the inner stator assembly and the outer stator assembly, the dual-stator low-speed permanent magnet synchronous motor provided in the present application has output power in three fixed modes.

When the working condition is light load, power output can be achieved by starting the inner stator assembly only. When the working condition is between light load and heavy load, power output can be achieved by starting the outer stator assembly only. When the working condition is heavy load, the maximum power output is achieved through the joint action of the inner stator assembly and the outer stator assembly to adapt to the heavy load condition.

Therefore, the motor provided by the present application can better adapt to different working conditions and avoid the power waste caused by "a big horse pulling a small cart" to a certain extent. Moreover, when one of the inner stator component and the outer stator component fails, the power can still be supplied for a certain period of time through the other component, thereby improving the fault-tolerant operation capability of the motor to a certain extent.

In addition, the present invention also provides a driving method for the above-mentioned dual-stator low-speed permanent magnet synchronous motor, comprising the following steps: Step 1, when the load torque is less than 1/4 of the rated torque, the second winding is connected in star shape, the second winding is powered by a separate inverter, the first winding is not powered, and the inner stator component runs; Step 2, when the load torque is greater than 1/4 of the rated torque and less than 3/4 of the rated torque, the first winding is connected in star shape, the first winding is powered by a separate inverter, the second winding is not powered, and the outer stator component runs; Step 3, when the load torque is greater than 3/4 of the rated torque, the first winding and the second winding are connected in series, the tail ends of the windings are connected in star shape, and are powered by a inverter, and the inner stator component and the outer stator component run simultaneously.

Through the different wiring methods corresponding to different working conditions of the present application, the power adaptation output of the motor under different working conditions can be achieved, thereby avoiding the waste of electricity to a certain extent. In addition, when the inner stator component fails, the motor can be connected in the way of step two, that is, the first winding is connected in a star shape, and the outer stator component is powered by a separate frequency converter, so that the outer stator component can be started to provide power output for the working condition where the load torque is less than 1/4 of the rated torque. When the outer stator component fails, the motor can be connected in the way of step two, that is, the second winding is connected in a star shape, and the inner stator component is powered by a separate frequency converter, so that the inner stator component can be started to provide power output for the working condition where the load torque is greater than 1/4 of the rated torque and less than 3/4 of the rated torque within a certain period of time, thereby improving the fault-tolerant operation capability of the motor to a certain extent.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

FIG1 is a schematic structural diagram of a dual-stator low-speed permanent magnet synchronous motor provided in an embodiment of the present invention;

FIG2 is a schematic structural diagram of a permanent magnet of a dual-stator low-speed permanent magnet synchronous motor provided by an embodiment of the present invention;

FIG. 3 is a flow chart of a driving method provided by an embodiment of the present invention.

In the figure: 1-outer stator core; 101-first receiving slot; 2-inner stator core; 201-second receiving slot; 3-rotor core; 301-air slot; 302-rotor pole shoe; 4-permanent magnet; 401-ferrite; 402-NdFeB; 5-first winding; 6-second winding.

Detailed ways

To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with 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. The components of the embodiments of the present application usually described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

In the description of the embodiments of the present application, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or are the positions or positional relationships in which the inventive product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

In the description of the embodiments of the present application, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "setting", "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

As used herein, the term "and/or" includes any one of the associated listed items and any combination of any two or more items.

For ease of description, spatial relative terms such as "above", "upper", "below", and "lower" may be used herein to describe the relationship of one element to another element as shown in the drawings. Such spatial relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the drawings.

The terms used herein are only used to describe various examples and are not used to limit the present disclosure. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms "include", "comprise" and "have" list the stated features, quantities, operations, components, elements and/or their combinations that exist, but do not exclude the existence or addition of one or more other features, quantities, operations, components, elements and/or their combinations.

Variations in the shapes shown in the drawings may occur due to manufacturing techniques and/or tolerances. Therefore, the examples described herein are not limited to the specific shapes shown in the drawings but include variations in shapes that occur during manufacturing.

The features of the examples described herein may be combined in various ways that will be apparent after understanding the disclosure of the present application. In addition, although the examples described herein have various configurations, other configurations are possible as will be apparent after understanding the disclosure of the present application. In addition, the technical solutions between the various embodiments may be combined with each other, but must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that the combination of such technical solutions does not exist and is not within the scope of protection required by the present application.

As shown in Figure 1, the present invention provides a dual-stator low-speed permanent magnet synchronous motor, including an outer stator assembly, a rotor assembly and an inner stator assembly; a cavity is formed inside the outer stator assembly, the inner stator assembly and the rotor assembly are both arranged in the cavity, the rotor assembly is located between the inner stator assembly and the outer stator assembly, and a first gap is formed between the outer ring wall surface of the rotor assembly and the inner ring wall surface of the outer stator assembly, and a second gap is formed between the inner ring wall surface of the rotor assembly and the outer ring wall surface of the inner stator assembly.

Compared with the prior art, the dual-stator low-speed permanent magnet synchronous motor provided by the present invention has the following advantages:

The dual-stator low-speed permanent magnet synchronous motor provided by the present invention arranges an inner stator assembly and a rotor assembly in a cavity formed by an outer stator assembly, so that the rotor assembly is located between the inner stator assembly and the outer stator assembly, thereby fully utilizing the cavity formed by the outer stator assembly, and further, without changing the overall size and volume of the motor, can improve the torque density of the motor to a certain extent and improve the overall performance of the motor.

Furthermore, since the rotor assembly in the present application can rotate independently relative to the inner stator assembly or independently relative to the outer stator assembly or simultaneously relative to the inner stator assembly and the outer stator assembly, the dual-stator low-speed permanent magnet synchronous motor provided in the present application has output power in three fixed modes.

When the working condition is light load, power output can be achieved by starting the inner stator assembly only. When the working condition is between light load and heavy load, power output can be achieved by starting the outer stator assembly only. When the working condition is heavy load, the maximum power output is achieved through the joint action of the inner stator assembly and the outer stator assembly to adapt to the heavy load condition.

Therefore, the motor provided by the present application can better adapt to different working conditions and avoid the power waste caused by "a big horse pulling a small cart" to a certain extent. Moreover, when one of the inner stator component and the outer stator component fails, the power can still be supplied for a certain period of time through the other component, thereby improving the fault-tolerant operation capability of the motor to a certain extent.

Optionally, as shown in Figure 1, the outer stator assembly in the present application includes an outer stator core 1 and a first winding 5, and the inner stator assembly includes an inner stator core 2 and a second winding 6; the inner ring wall of the outer stator core 1 is formed with a plurality of first accommodating grooves 101, and the plurality of first accommodating grooves 101 are evenly spaced along the circumference of the inner ring wall of the outer stator core 1, and the first accommodating grooves 101 extend radially along the outer stator core 1, and the two long sides of the first winding 5 are respectively arranged in two adjacent first accommodating grooves 101; the outer ring wall of the inner stator core 2 is formed with a plurality of second accommodating grooves 201, and the plurality of second accommodating grooves 201 are evenly spaced along the circumference of the outer ring wall of the inner stator core 2, and the axis of the second accommodating grooves 201 extends radially along the outer stator core 1, and the two long sides of the second winding 6 are respectively arranged in two different second accommodating grooves 201.

The multiple first accommodating grooves 101 formed by the outer stator core 1 of the present application can stably carry the first winding 5, and the multiple second accommodating grooves 201 formed by the inner stator core 2 can stably carry the second winding 6. In addition, since the multiple first accommodating grooves 101 in the present application are evenly distributed along the circumference of the outer stator core 1, and the multiple second accommodating grooves 201 are evenly distributed along the circumference of the inner stator core 2, the relative rotation process of the rotor core 3 can be made more stable and uniform, thereby improving the stability of the motor output.

It should be additionally explained here that, in the present application, the two long sides of the first winding 5 and the two long sides of the second winding 6 are both the two side coil sides of the winding.

Specifically, as shown in FIG. 1 , in the present application, the angle between the axis of the starting first receiving groove 101 and the axis of the starting second receiving groove 201 is β, so that the angle between the axis of the adjacent first receiving groove 101 and the axis of the second receiving groove 201 is β.

It can be understood that the first winding 5 and the second winding 6 in the present application are both three-phase windings, the tail ends of phase A, phase B and phase C of the first winding 5 are X, Y, Z, and the tail ends of phase a, phase b and phase c of the second winding 6 are x, y, z.

Since the motor has torque pulsation during rotation, when the torque pulsation is large, the stability of the motor is poor, and the process of dragging the load is prone to jitter, which not only affects the stability of the motor speed, but also increases the energy consumption of the motor. Therefore, in order to suppress torque pulsation in this application, preferably, the first winding 5 is sequentially offline in the clockwise direction according to the offline sequence of A-Z-B-X-C-Y, and the second winding 6 is sequentially offline in the clockwise direction according to the offline sequence of a-z-b-x-c-y.

Therefore, it can be understood that the above-mentioned starting first receiving slot 101 and the starting second receiving slot 201 are the receiving slots for the first winding 5 and the second winding 6 to start from, and by making the angle between the axis of the starting first receiving slot 101 and the axis of the starting second receiving slot 201 a fixed value β, and in the present application, the first receiving slots 101 are evenly distributed along the circumference of the outer stator core 1, and the second receiving slots 201 are evenly distributed along the circumference of the inner stator core 2, so that the angles between the axes of the subsequent adjacent first receiving slots 101 and the axes of the second receiving slots 201 are all fixed values β, which can weaken the high torque pulsation of the motor under low-speed operation to a certain extent, improve the stability of the motor operation, and reduce the problem of jitter under load to a certain extent.

It should be noted that the value range of β in this application is Wherein Z is the number of slots, that is, the number of the first receiving slots 101 or the number of the second receiving slots 201 mentioned above.

Since the parameters of low-speed dual-stator motors with different power levels and the same structure are inconsistent, the corresponding β values are different. The optimal β value can be determined by an optimization method. The optimal β value is selected to ensure that the peaks and troughs of the output torque of the outer stator component coincide with the troughs and peaks of the output torque of the inner stator component, thereby reducing the torque pulsation level of the motor and improving the stability of the output torque.

Preferably, the first winding 5 in the present application is a formed winding, and the second winding 6 is a loose wire winding; the first accommodating groove 101 is rectangular, and the open end of the second accommodating groove 201 is a retracted structure.

First, the open end of the second receiving slot 201 in the present application is a retracted structure, that is, the semi-closed slot structure can reduce the tooth harmonic content to a certain extent, and the low tooth harmonic content can further reduce the torque pulsation and harmonic loss of the motor. Since the formed winding cannot be embedded in the semi-closed slot structure, the first receiving slot 101 in the present application needs to be used with a rectangular slot structure.

Secondly, compared with traditional scattered wire windings, formed windings have the advantages of being strong and durable and convenient to insert wires, and are therefore widely used in low-speed direct-drive motors. Since the outer stator assembly of the dual-stator low-speed permanent magnet synchronous motor provided by the present application has a large diameter, the tooth width is relatively wide, so when concentrated windings are used, the distance between the left and right coil sides of each formed winding is relatively wide, so that it can be directly wound out using a winding machine.

Since the inner stator component is placed in the cavity of the outer stator component, the outer diameter of the inner stator component is smaller and the tooth width is also smaller. This means that if a formed winding is used, the distance between the left and right coil sides of the formed winding is very narrow. The narrow distance between the left and right coil sides will severely limit the bending of the flat copper wire at the end of the formed winding, making it impossible to process such a formed winding. Therefore, the second winding 6 in the present application adopts a traditional loose wire winding, which can realize the assembly and forming of the overall motor.

Finally, since the formed winding can be applied to higher voltages, and the outer stator assembly in the present application needs to provide a higher output torque when in operation, the outer stator assembly can provide a stable output torque by making the first winding 5 a formed winding. Since the inner stator assembly needs to adapt to light load conditions in the present application, the second winding 6 in the present application is a scattered wire winding, which can provide an output torque equivalent to 1/3 of the capacity of the outer stator assembly, and can adapt to light load conditions when starting alone, saving energy consumption.

Optionally, as shown in Figure 1, the rotor assembly in the present application includes a rotor core 3 and a permanent magnet 4; a plurality of third accommodating grooves are formed on the outer ring wall of the rotor core 3, and the plurality of third accommodating grooves are evenly spaced along the circumference of the outer ring wall of the rotor core 3, and the axis of the third accommodating grooves extends radially along the rotor core 3; a plurality of fourth accommodating grooves are formed on the inner ring wall of the rotor core 3, and the plurality of fourth accommodating grooves are evenly spaced along the circumference of the inner ring wall of the rotor core 3, and the axis of the third accommodating grooves extends radially along the rotor core 3; the third accommodating grooves and the fourth accommodating grooves are arranged one by one, the permanent magnets 4 are correspondingly arranged in the third accommodating grooves and the fourth accommodating grooves, and an air groove 301 is formed between the third accommodating groove and the fourth accommodating groove.

The third accommodating groove and the fourth accommodating groove formed on the rotor core 3 can better accommodate permanent magnets, and permanent magnets can be set on the inner ring of the rotor core 3 facing the inner stator core 2 and the outer ring of the rotor core 3 facing the outer stator core 1, so that the inner stator assembly and the outer stator assembly can better cooperate with the rotor assembly.

It should be noted here that the first receiving groove 101, the third receiving groove and the fourth receiving groove in the present application are all rectangular groove structures, and the second receiving groove 201 is approximately a rectangular groove structure, thus having three axes, wherein the above-mentioned radially extending axis is the axis of the first receiving groove 101, the second receiving groove 201, the third receiving groove and the fourth receiving groove in the width direction, and the axis of the first receiving groove 101, the second receiving groove 201, the third receiving groove and the fourth receiving groove in the length direction extends along the axial direction of the outer stator core 1, the inner stator core 2 and the rotor core 3.

Preferably, in the present application, the permanent magnets 4 are magnetized along the tangential direction of the rotor core 3, and the magnetization directions of the permanent magnets 4 in the third accommodating slot and the fourth accommodating slot whose axes coincide with each other are consistent.

Since tangential magnetization is adopted, the magnetic field generated by two adjacent tangential permanent magnets 4 on the rotor core 3 on the same side enters the air gap through the rotor pole shoe 302 between the two, forming an air gap magnetic field under a single magnetic pole. The present application is beneficial to the sinusoidalization of the permanent magnet rotor magnetic field by weakening the air gap magnetic density at both ends of the rotor pole shoe 302 and maintaining the air gap magnetic density size corresponding to the central part of the rotor pole shoe 302. The sinusoidalization of the air gap magnetic field can reduce the high-order harmonic content in the air gap magnetic field, thereby further reducing the torque pulsation of the motor, reducing harmonic losses, and improving the motor efficiency.

In order to better achieve the above-mentioned effects, preferably, as shown in FIG. 1 and FIG. 2 , the permanent magnet 4 in the present application includes NdFeB 402 and ferrite 401, and the ferrite 401 in the third receiving groove is located between the NdFeB 402 and the outer stator assembly; the ferrite 401 in the fourth receiving groove is located between the NdFeB 402 and the inner stator assembly.

It should be noted that when the motor is overloaded, the copper loss of the motor increases sharply, which will cause the temperature of the first winding 5 and the second winding 6 to rise rapidly. In addition, the torque density of the motor provided by the present application is relatively high, which makes the overall temperature rise of the motor relatively high. The permanent magnet 4 uses a single NdFeB 402 material, and the partial area of the NdFeB 402 near the winding position will have the risk of local high-temperature demagnetization, which is not conducive to the stable operation of the motor. Therefore, the present application uses a combination of NdFeB 402 and ferrite 401 magnetic poles, and utilizes the characteristic that the anti-demagnetization ability of the ferrite 401 material is enhanced as the temperature rises, and replaces the NdFeB 402 to be set near the first winding 5 and the second winding 6, thereby greatly reducing the risk of high-temperature demagnetization of the original NdFeB 402 material near the first winding 5 and the second winding 6.

Furthermore, since the cost of the ferrite 401 material is lower than that of the NdFeB 402 material, replacing a portion of the NdFeB 402 material with the ferrite 401 can reduce the overall manufacturing cost of the motor to a certain extent.

Further preferably, as shown in FIG. 2 , in the present application, the ratio between the radial dimension of the NdFeB 402 and the radial dimension of the ferrite 401 of the rotor core 3 is α.

In the present application, the range of α is between 1/8 and 1/4, that is, the ratio of NdFeB 402 to ferrite 401 is between 8:1 and 4:1, thereby improving the sinusoidalization of the permanent magnet rotor magnetic field, further reducing the torque pulsation of the motor under low-speed conditions, and ensuring to a certain extent that the motor output torque capacity will not be significantly reduced due to the use of low-residual magnet ferrite 401 material.

As shown in FIG. 1 and FIG. 2, in the present application, there is an air slot 301 inside the rotor core 3, and the air slot 301 is located between the third accommodating slot and the fourth accommodating slot in the same radial direction and between the inner and outer rotor pole shoes 302 in the same radial direction, and the leakage magnetic flux can be suppressed to a certain extent by the existing air slot 301. Preferably, the air slot 301 in the present application is filled with resin material, and the poured resin can improve the thermal conductivity of the air slot 301, promote the uniform distribution of the temperature rise inside the rotor, and the poured resin can also fix the permanent magnet 4, and reduce the vibration of the permanent magnet 4 when the motor is running to a certain extent.

In addition, as shown in Figure 3, the present invention also provides a driving method for the above-mentioned dual-stator low-speed permanent magnet synchronous motor, comprising the following steps: Step 1, when the load torque is less than 1/4 of the rated torque, the second winding 6 is connected in star shape, the second winding 6 is powered by a separate inverter, the first winding 5 is not powered, and the inner stator assembly runs; Step 2, when the load torque is greater than 1/4 of the rated torque and less than 3/4 of the rated torque, the first winding 5 is connected in star shape, the first winding 5 is powered by a separate inverter, the second winding 6 is not powered, and the outer stator assembly runs; Step 3, when the load torque is greater than 3/4 of the rated torque, the first winding 5 and the second winding 6 are connected in series, the tail ends of the windings are connected in star shape, and one inverter is used for power supply, and the inner stator assembly and the outer stator assembly run simultaneously.

Through the different wiring methods corresponding to different working conditions of the present application, the power adaptation output of the motor under different working conditions can be achieved, thereby avoiding the waste of electricity to a certain extent. In addition, when the inner stator component fails, the motor can be connected in the way of step two, that is, the first winding 5 is connected in a star shape, and the outer stator component is powered by a separate frequency converter, so that the outer stator component can be started to provide power output for the working condition where the load torque is less than 1/4 of the rated torque. When the outer stator component fails, the motor can be connected in the way of step two, that is, the second winding 6 is connected in a star shape, and the inner stator component is powered by a separate frequency converter, so that the inner stator component can be started to provide power output for the working condition where the load torque is greater than 1/4 of the rated torque and less than 3/4 of the rated torque within a certain period of time, thereby improving the fault-tolerant operation capability of the motor to a certain extent.

When the motor drives a heavy load, the first winding 5 of the outer stator assembly and the second winding 6 of the inner stator assembly are connected in series. At this time, the tail end of the A phase of the first winding 5 is X and is connected to the tail end of the a phase of the second winding 6 is x, so that the A phase of the first winding 5 and the a phase of the second winding 6 are connected in series. Similarly, the B phase of the first winding 5 and the b phase of the second winding 6 and the C phase of the first winding 5 and the c phase of the second winding 6 are connected in series. After the series connection, the tail ends of the three phases are connected in a star connection, and the three-phase electricity output by the inverter is connected to the A, B, and C phases respectively. At this time, the internal and external motors work simultaneously to drive the heavy load.

When the load torque is less than 1/4 of the rated torque, the tail ends x, y, and z of the three-phase winding of the second winding 6 are connected in a star connection, the head ends a, b, and c are powered by independent inverters, and the internal stator components work alone.

When the load torque is greater than 1/4 of the rated torque and less than 3/4 of the rated torque, the three-phase winding tail ends X, Y, and Z of the first winding 5 are connected in a star connection, the head ends A, B, and C are powered by an independent inverter, and the external stator assembly works alone.

It should be additionally explained here that in the present application, the switching of the connection mode of the first winding 5 and the second winding 6 under different working conditions is achieved by using a dedicated winding switch.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (9)

1. The double-stator low-speed permanent magnet synchronous motor is characterized by comprising an outer stator assembly, a rotor assembly and an inner stator assembly;

The inner stator assembly and the rotor assembly are arranged in the cavity, the rotor assembly is positioned between the inner stator assembly and the outer stator assembly, a first gap is formed between the outer annular wall surface of the rotor assembly and the inner annular wall surface of the outer stator assembly, and a second gap is formed between the inner annular wall surface of the rotor assembly and the outer annular wall surface of the inner stator assembly;

The rotor assembly comprises a rotor core and permanent magnets;

A plurality of third accommodating grooves are formed in the outer annular wall surface of the rotor core, a plurality of fourth accommodating grooves are formed in the inner annular wall surface of the rotor core, and the permanent magnets are correspondingly arranged in the third accommodating grooves and the fourth accommodating grooves;

The permanent magnet comprises neodymium iron boron and ferrite, and the ferrite in the third accommodating groove is positioned between the neodymium iron boron and the outer stator assembly;

And the ferrite in the fourth accommodating groove is positioned between the NdFeB and the inner stator assembly.

2. The dual stator low speed permanent magnet synchronous motor of claim 1, wherein the outer stator assembly includes an outer stator core and a first winding, and the inner stator assembly includes an inner stator core and a second winding;

The inner annular wall surface of the outer stator core is provided with a plurality of first accommodating grooves, the plurality of first accommodating grooves are distributed at equal intervals along the circumferential direction of the inner annular wall surface of the outer stator core, the axes of the first accommodating grooves extend along the radial direction of the outer stator core, and two long sides of the first winding are respectively arranged in two adjacent first accommodating grooves;

the outer annular wall surface of the inner stator core is provided with a plurality of second accommodating grooves, the second accommodating grooves are distributed at equal intervals along the circumferential direction of the outer annular wall surface of the inner stator core, the axes of the second accommodating grooves extend along the radial direction of the outer stator core, and two long sides of the second winding are respectively arranged in two different second accommodating grooves.

3. The dual stator low speed permanent magnet synchronous motor according to claim 2, wherein an angle between an axis of the first receiving groove initially and an axis of the second receiving groove initially is β such that angles between axes of the adjacent first receiving groove and second receiving groove are β.

4. The dual stator low speed permanent magnet synchronous motor of claim 2, wherein the first winding is a profiled winding and the second winding is a split winding;

the first accommodating groove is rectangular, and the open end of the second accommodating groove is of a furling structure.

5. The double-stator low-speed permanent magnet synchronous motor according to claim 2, wherein a plurality of the third accommodation grooves are equally spaced in a circumferential direction of an outer circumferential wall surface of the rotor core, and an axis of the third accommodation groove extends in a radial direction of the rotor core;

a plurality of fourth accommodating grooves are distributed at equal intervals along the circumferential direction of the inner annular wall surface of the rotor core, and the axes of the fourth accommodating grooves extend along the radial direction of the rotor core;

The third accommodating grooves and the fourth accommodating grooves are arranged in one-to-one correspondence, and an air groove is formed between the third accommodating grooves and the fourth accommodating grooves.

6. The double stator low speed permanent magnet synchronous motor according to claim 5, wherein a ratio between a dimension of the neodymium iron boron in a radial direction of the rotor core and a dimension of the ferrite in the radial direction of the rotor core is α.

7. The double stator low speed permanent magnet synchronous motor according to claim 5, wherein the permanent magnets are magnetized in a tangential direction of the rotor core, and the magnetizing directions of the permanent magnets in the third accommodation groove and the fourth accommodation groove with the axes coincident are identical.

8. The dual stator low speed permanent magnet synchronous motor according to claim 5, wherein the air slots are filled with a resin material.

9. A driving method, characterized in that the double-stator low-speed permanent magnet synchronous motor according to any one of the preceding claims 2-8 is applied, comprising the steps of:

When the load torque is smaller than 1/4 rated torque, the second winding adopts a star connection mode, the second winding adopts an independent frequency converter to supply power, the first winding does not supply power, and the inner stator assembly operates;

When the load torque is larger than 1/4 rated torque and smaller than 3/4 rated torque, the first winding adopts a star connection mode, the first winding adopts an independent frequency converter to supply power, the second winding does not supply power, and the outer stator assembly operates;

And thirdly, when the load torque is greater than 3/4 rated torque, the first winding and the second winding are connected in series, the tail ends of the windings are in star connection, a frequency converter is adopted for supplying power, and the inner stator assembly and the outer stator assembly operate simultaneously.