WO2024083155A1

WO2024083155A1 - Motor, compressor, and refrigeration device

Info

Publication number: WO2024083155A1
Application number: PCT/CN2023/125230
Authority: WO
Inventors: 杨勤; 邱小华; 盖蕊; 张德金
Original assignee: 广东美芝制冷设备有限公司
Priority date: 2022-10-21
Filing date: 2023-10-18
Publication date: 2024-04-25
Also published as: CN117955266A

Abstract

A motor, a compressor, and a refrigeration device. The motor comprises a rotor (100) and a stator (200). The rotor (100) comprises a rotor iron core and a plurality of permanent magnets (120) provided on the rotor iron core, and the permanent magnets (120) each contain a cerium element having a mass percentage of x%; the stator (200) comprises a stator iron core, Q stator teeth (210) are provided on the stator iron core in the inner circumferential direction, a stator winding is wound on each stator tooth (210), and the number of phases of each stator winding is m; the mass percentage x% of the cerium element meets: 3%≤x%≤10%; the number Q of the stator teeth (210) and the number m of phases of each stator winding satisfy the relationship: Q/m≤3; and the width of magnetic poles of the rotor (100) is bm, and bm satisfies the relationship: bm≥3040/(165-x).

Description

Motors, compressors and refrigeration equipment

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese patent application No. 202211296964.6, filed on October 21, 2022, and entitled “Motors, Compressors and Refrigeration Equipment,” the entire contents of which are incorporated by reference into this application.

Technical Field

The present application belongs to the technical field of compressors, and specifically relates to a motor, a compressor and a refrigeration device.

Background technique

At present, in the field of household air-conditioning compressors, fixed-speed models are gradually withdrawing from the market, and variable-frequency motors have become the mainstream technology. In order to adapt to the application environment of household air conditioners, the permanent magnets of variable-frequency motors are mostly _NdFeB permanent magnets containing heavy rare earth elements and high coercivity. NdFeB permanent magnets are permanent magnet materials based on the intermetallic compound _Nd2Fe14B , and the main components are neodymium, iron and boron. In order to obtain different properties, other rare earth metals such as dysprosium and praseodymium can be used to replace part of the neodymium in the permanent magnet. With the annual increase in the total number of variable-frequency models, the consumption of heavy rare earth elements (especially dysprosium and terbium) resources has also increased year by year. In order to reduce the use of heavy rare earth elements, new technologies need to be developed.

Compared with praseodymium and neodymium, cerium has obvious cost advantages, but compared with the same praseodymium and neodymium, the remanence _Br and intrinsic coercivity _Hcj of the corresponding rare earth magnets will be reduced, which directly affects the performance of the motor. Therefore, in order to meet the application requirements of motor performance in the whole machine, it is necessary to redesign the motor structure according to the content of rare earth element cerium in the permanent magnet.

Summary of the invention

The present application aims to at least partially solve one of the above technical problems existing in the prior art. To this end, the present application provides a motor, a compressor including the motor of the present application, and a refrigeration device including the compressor of the present application.

According to the first aspect of the present application, the motor provided by the embodiment includes a rotor and a stator;

The rotor comprises a rotor core and a plurality of permanent magnets arranged on the rotor core, wherein the permanent magnets contain a cerium element with a mass percentage of x%;

The stator comprises a stator core, wherein the stator core is provided with Q stator teeth along the inner circumference, each stator tooth is wound with a stator winding, and the number of phases of the stator winding is m;

The mass percentage x% of the cerium element satisfies: 3%≤x%≤10%;

The number of stator teeth Q and the number of phases m of the stator winding satisfy the relationship: Q/m≤3;

The width of the magnetic pole of the rotor is b _m , and the magnetic pole width b _m satisfies the relationship: b _m ≥ 3040/(165-x).

According to some embodiments of the present application, the number Q of the stator teeth is 9.

According to some embodiments of the present application, the number Q of the stator teeth is 6.

According to some embodiments of the present application, the phase number m of the stator winding is 3.

According to some embodiments of the present application, the number of magnetic pole pairs of the rotor is P, and P≤3.

According to some embodiments of the present application, in the stator winding, the coils on the stator teeth in each phase are connected in series.

According to some embodiments of the present application, in the stator winding, the coils on the stator teeth in each phase are connected in parallel.

According to some embodiments of the present application, the magnetic pole width b _m satisfies the relationship: b _m ≤ 3900/(165-x).

According to some embodiments of the present application, the efficiency of the motor is ≥91.5%.

The efficiency of a motor is the efficiency under rated voltage, frequency and load conditions.

According to some embodiments of the present application, the permanent magnet contains dysprosium element, and the content of the dysprosium element is less than 3wt%.

According to some embodiments of the present application, the permanent magnet contains dysprosium element, and the content of the dysprosium element is less than 2.3 wt %.

According to some embodiments of the present application, the permanent magnet contains dysprosium element, and the content of dysprosium element is about 2.25wt%.

According to some embodiments of the present application, the permanent magnet contains praseodymium and neodymium elements, and the sum of the contents of the praseodymium and neodymium elements is 20wt% to 32wt%.

According to some embodiments of the present application, the permanent magnet contains praseodymium and neodymium elements, and the sum of the contents of the praseodymium and neodymium elements is 25wt% to 32wt%.

According to some embodiments of the present application, the permanent magnet contains praseodymium and neodymium elements, and the sum of the contents of the praseodymium and neodymium elements is 25 wt %.

According to some embodiments of the present application, the permanent magnet contains cobalt element, and the content of the cobalt element is 1wt% to 2wt%.

According to some embodiments of the present application, a plurality of slots are provided on the end surface of the rotor core along the circumferential direction of the rotor core, and each of the permanent magnets is correspondingly embedded in each of the slots.

According to some embodiments of the present application, the slot is V-shaped.

According to some embodiments of the present application, the V-shaped opening faces the motor stator.

According to some embodiments of the present application, the motor of the present application is a permanent magnet synchronous motor.

The compressor provided in accordance with the second aspect of the present application includes the motor described above.

The refrigeration equipment provided in accordance with the third aspect of the present application includes the compressor described above.

According to some embodiments of the present application, the refrigeration equipment is an air conditioner.

According to some embodiments of the present application, the air conditioner is a household air conditioner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the structure of the motor of the present application.

FIG. 2 is a schematic diagram of the partial structure of the permanent magnets and slots in the motor of the present application.

FIG. 3 is a graph showing the relationship between the addition of cerium and the decrease in the residual magnetism of a magnet.

Reference numerals:
100: rotor; 110: slot; 120: permanent magnet;
200: stator; 210: stator teeth;
300: Air gap.

Detailed ways

The following are specific embodiments of the present application, and the technical solution of the present application is further described in conjunction with the embodiments, but the present application is not limited to these embodiments.

In some embodiments of the present application, the present application provides a motor, which includes a rotor 100 and a stator 200 , and an air gap 300 is formed between the rotor 100 and the stator 200 .

1 and 2 , the rotor 100 includes a rotor core and a plurality of permanent magnets 120 disposed on the rotor core, wherein the permanent magnets 120 contain a cerium element of x mass percent;

The stator 200 includes a stator core, and the stator core is provided with Q stator teeth 210 along the inner circumference direction. A stator winding (not shown) is wound around each stator tooth 210, and the number of phases of the stator winding is m.

The mass percentage x% of the cerium element satisfies: 3%≤x%≤10%;

The number Q of the stator teeth 210 and the number m of phases of the stator winding satisfy the relationship: Q/m≤3;

The width of the magnetic pole of the rotor 100 is b _m , and b _m satisfies the relationship: b _m ≥ 3040/(165-x).

It can be understood that one of the core components of an air conditioner is the compressor, and a motor is provided in the compressor. The torque of the motor is generated by the interaction between the magnetic field strength of the NdFeB magnet in the motor and the magnetic field strength generated by the stator in the current. In order to meet the needs of air conditioner manufacturers for demagnetization current, the intrinsic coercive force of the NdFeB permanent magnets used in the inverter models of general compressor manufacturers is ≥1830kA/m. The permanent magnets under this intrinsic coercive force all contain a large proportion of praseodymium, neodymium and heavy rare earth elements. In order to reduce the dependence on praseodymium, neodymium and heavy rare earth elements, magnets containing cerium elements can be used, but the use of cerium elements will lead to a decrease in intrinsic coercive force. The intrinsic coercive force of permanent magnets containing cerium is in the range of 1500≤H _cj ≤1800kA/m, which is lower than the NdFeB permanent magnets with an intrinsic coercive force of more than 1830kA/m used in the inverter models of general compressor manufacturers. Due to the decrease in intrinsic coercive force, under the existing motor design scheme, the demagnetization ability of the motor will decrease by more than 40%. In order to use rare earth magnets containing cerium, a new design of the motor is required.

To this end, the present application proposes a motor, including a rotor 100 and a stator 200. Specifically:

The rotor 100 in the motor includes a rotor core and a plurality of permanent magnets 120 disposed on the rotor core, wherein the permanent magnets 120 contain a cerium element with a mass percentage of x%.

The stator 200 in the motor includes a stator core, and the stator core is provided with Q stator teeth 210 along the inner circumference direction. A stator winding (not shown) is wound around each stator tooth 210, and the number of phases of the stator winding is m.

The mass percentage x% of the cerium element satisfies: 3%≤x%≤10%;

It can also be understood that in the motor of the present application, the permanent magnet 120 contains a cerium element with a mass percentage of x%, thereby reducing the use of praseodymium, neodymium and heavy rare earth elements, and effectively controlling the cost. Since the addition of cerium will cause the remanence of the magnet B _r to decrease, in order to ensure that the efficiency of the motor can meet the demand under the condition of equivalent cost, the present application proposes a motor, according to the mass percentage of x% of the cerium element in the permanent magnet 120, the number Q of the stator teeth 210 and the number m of the phases of the stator winding are developed and designed. When the number Q of the stator teeth 210 and the number m of the phases of the stator winding satisfy the relationship Q/m≤3, and the pole width _bm satisfies the relationship _bm≥3040 /(165-x), the efficiency and reliability of the motor can be optimized, and the cost of the motor is the lowest.

In order to reduce the dependence on praseodymium, neodymium and heavy rare earth elements, the present application adopts a permanent magnet containing cerium, corresponding to a mass percentage of x% of cerium in the total weight of the permanent magnet. The addition of cerium will cause the remanence of the magnet to decrease, and the remanence decrease is shown in reference to Figure 3. From Figure 3, it can be seen that the decrease in the remanence _Br of the permanent magnet corresponding to different mass percentages of cerium in different permanent magnets. Due to the decrease in the remanence of the magnet, under the existing motor design, the motor flux is reduced, and the motor efficiency decreases significantly under the condition of equivalent cost. In order to apply rare earth magnets containing cerium, the present application has made a new design of the motor structure size according to the mass percentage of x% of cerium in the permanent magnet.

In some embodiments of the present application, the number Q of stator teeth is 9.

In some other embodiments of the present application, the number Q of stator teeth is 6.

In some embodiments of the present application, the phase number m of the stator winding is 3.

It can be understood that since most of the existing motor structures satisfy Q/m≤3, the present application limits the number of stator teeth Q and the number of phases m of the stator winding to satisfy the relationship Q/m≤3. Without changing the existing motor structure, the utilization of permanent magnets with a cerium content x% of 3% to 10% can be achieved, thereby reducing the use of heavy rare earth resources, which is beneficial to broadening the scope of use of the product and is suitable for popularization and use.

In some embodiments of the present application, the number of magnetic pole pairs of the rotor 100 is P, where P≤3.

The motor of the present application is a permanent magnet synchronous motor, and the main excitation magnetic field is generated by the rotor magnet. Therefore, the number of pairs of magnets determines the number of poles of the magnetic field. For example, a three-pole pair magnet generates a three-pole pair magnetic field.

The number of magnetic pole pairs of a permanent magnet motor refers to how many pairs of N and S poles the rotor or stator has. The number of poles is the total number of N and S poles. The number of magnetic pole pairs = number of poles/2, so 6 poles means 3 pairs of poles.

Rotate the permanent magnet rotor once and observe its back electromotive force. The number of cycles is the number of its magnetic pole pairs. The motor has different magnetic pole pairs and different speeds.

The torque of the motor is generated by the interaction between the magnetic field strength of the magnet in the motor and the magnetic field strength generated by the stator in the current. The excitation of the motor is provided by the permanent magnet in the rotor. The remanence _Br and width of the permanent magnet determine the magnetic flux that the rotor can provide. The number of magnetic pole pairs of the rotor is P, and the magnetic pole width is _bm , then the magnetic flux that the permanent magnet can provide is 2P× _bm × _Br . Due to the use of rare earth magnets containing cerium elements, the _Br value decreases accordingly, and the overall excitation of the permanent magnet is reduced. In the motor of the present application, the permanent magnet is a magnet containing cerium elements. When the corresponding number of magnetic pole pairs P is matched to achieve a comparable _Br and _Hcj , the cost is lower and the motor is more cost-effective.

In the motor of the present application, the magnetic pole width b _m is defined to satisfy the relationship: b _m ≥ 3040/(165-x).

Table 1 lists the change values of 3040/(165-x) corresponding to when the width _bm of the rotor magnetic pole is 20 and the cerium content x% in the permanent magnet changes from 0% to 13%. In fact, when the cerium content x% exceeds 10%, the _Br value decreases significantly, the motor excitation magnetic field is too small, the motor efficiency is poor, and the compressor energy efficiency requirements cannot be met.

It should be noted that the width of the magnetic pole of the rotor is b _m . When each magnetic pole is composed of two permanent magnets, b _m is the sum of the actual widths of the two permanent magnets.

It should be noted that the stator winding is divided into concentrated winding and distributed winding. Concentrated winding refers to the winding in which the coil is wound on one stator tooth. Distributed winding refers to the winding in which the coil is wound on multiple stator teeth. Specifically, the span of the concentrated winding is 1, such as slot one to slot two; while the span of the distributed winding is not 1, such as the span is 3, and the winding is from slot one to slot four. The "slot" here refers to the area formed between the stator tooth and the stator tooth. In addition, the end height of the concentrated winding is small and the cost is low; the end height of the distributed winding is relatively larger and the cost is higher, but the motor runs with less noise.

It should also be noted that the permanent magnets in the motor of the present application can be purchased directly from the market. Specifically, in the permanent magnets of Table 1, in addition to the cerium content as shown in Table 1, the sum of the praseodymium and neodymium content is 25wt%, the dysprosium content is 2.25wt%, the cobalt content is 1.5wt%, and the remaining elements are iron. In commercially available permanent magnets that do not contain cerium, the element content is generally: the sum of the praseodymium and neodymium content is 30wt%, the dysprosium content is 2.25wt%, the cobalt content is 1.5wt%, and the rest is mainly Fe, and there may be a small amount of trace elements.

Table 1 The changing pattern of 3040/(165-x)

Furthermore, the remanence _Br of the permanent magnet, the motor efficiency and the cost changes are compared when the cerium content x% in the permanent magnet changes from 0% to 15%. The results are shown in Table 2. According to Table 2, the higher the addition ratio of the cerium element in the permanent magnet, the more the remanence _Br of the permanent magnet decreases. In the permanent magnet of the motor of the present application, the mass percentage x% of the cerium element satisfies 3%≤x%≤10%. When the mass percentage x% of the cerium element satisfies 3%≤x%≤10%, the optimal motor efficiency and motor cost performance can be achieved.

It should be noted that the motor efficiency is the efficiency obtained by testing under rated voltage, frequency and load conditions. Specifically, the voltage is 220V, the speed is 3600r/min, and the torque is 1.75N·m.

Table 2 Relationship between the mass percentage x% of cerium and the remanence of permanent magnets, motor efficiency and motor cost

As described above, in some embodiments of the present application, the width of the magnetic pole of the rotor is b _m , and the magnetic pole width b _m satisfies the relationship: b _m ≥ 3040/(165-x). Table 3 shows the relationship between the remanence _Br , 3040/(165-x), and the motor efficiency when b _m is 20 mm and the mass percentage x% of the cerium element changes from 0 to 15%.

Table 3 Relationship between the change of cerium content and motor efficiency and 3040/(165-x)

It can be seen from Table 3 that when the mass percentage x% of cerium is greater than 10% and 3040/(165-x) is greater than 20, the magnet performance is seriously degraded, the motor efficiency is low, and it cannot meet the use requirements. Therefore, the mass percentage x% of cerium in the permanent magnet used in the motor of the present application satisfies 3%≤x%≤10%, and at the same time, for the motor structure, b _m ≥3040/(165-x) is limited.

It should be noted that the magnet performance _Br data is provided by the magnet manufacturer after production and testing. Since it is a common test method in the industry, this article will not repeat it. _Br is the residual magnetization intensity, the unit is T.

It should also be noted that motor efficiency refers to the ratio of the motor's output power to its input power. For permanent magnet motors, a 0.5% increase in motor efficiency can be considered a significant efficiency improvement.

The test method and steps for motor efficiency are as follows:

Fix the stator on the stator fixture and fix the rotor on the corresponding bearing;

Set the test conditions, including voltage, speed, torque point, input the controller parameters of the corresponding motor, start the power supply, and energize the inverter;

Record the voltage U, current I, input power Pi, speed N, and torque T data under corresponding conditions;

The motor efficiency = 6.283×N×T/Pi can be automatically calculated by the testing equipment.

As mentioned above, the torque of the motor is generated by the interaction between the magnetic field strength of the magnet in the motor and the magnetic field strength generated by the stator in the current. The excitation of the motor is provided by the permanent magnet in the rotor. The remanence _Br and width of the permanent magnet determine the magnetic flux that the rotor can provide. The number of pole pairs of the rotor is P, and the pole width is _bm , then the magnetic flux that the permanent magnet can provide is 2P× _bm × _Br . Due to the use of rare earth magnets containing cerium elements, the _Br value decreases accordingly, and the overall excitation of the permanent magnet is reduced. In the motor of the present application, when the pole width _bm satisfies the relationship _bm ≥3040/(165-x), the magnetic properties of the magnet can meet the motor efficiency requirements.

In some embodiments of the present application, the coils on the stator teeth in each phase of the stator winding are connected in series.

It can be understood that at the same power level, the series winding used on the motor with relatively thicker wire diameter can achieve higher back electromotive force and improve the efficiency of medium and low frequency motors.

In some embodiments of the present application, in the stator winding, the coils on the stator teeth in each phase are connected in parallel.

It can also be understood that at the same power level, the use of parallel windings on motors with relatively thinner wire diameters can appropriately reduce the back electromotive force, which is beneficial to improving the efficiency of high-frequency motors.

In some embodiments of the present application, the magnetic pole width _bm satisfies the relationship: bm≤3900/(165-x).

In some embodiments of the present application, the efficiency of the motor is ≥91.5%.

The efficiency of the motor of the present application is ≥91.5%, which is the efficiency obtained by testing under rated voltage, frequency and load conditions. Specifically, the voltage is 220V, the speed is 3600r/min, and the torque is 1.75N·m.

In some embodiments of the present application, the permanent magnet contains dysprosium element, and the content of dysprosium element is less than 3wt%.

In some embodiments of the present application, the permanent magnet contains dysprosium element, and the content of dysprosium element is less than 2.3wt%.

In some embodiments of the present application, the permanent magnet contains dysprosium element, and the content of dysprosium element is about 2.25wt%.

Dysprosium is a silvery-white metal that is soft and can be cut with a knife. In addition to the chemical activity common to rare earth elements and the fact that it can be used as mixed rare earth metals and compounds, dysprosium also has excellent optical, electrical, magnetic and nuclear properties. Dysprosium is used as an additive to NdFeB permanent magnets. Adding about 2wt% to 3wt% of dysprosium to the magnet can increase its coercive force. With the increasing demand for NdFeB magnets, dysprosium has become a necessary additive element, and the demand is also increasing rapidly.

In some embodiments of the present application, the permanent magnet contains praseodymium and neodymium elements, and the sum of the contents of praseodymium and neodymium elements is 20 wt % to 32 wt %.

In some embodiments of the present application, the permanent magnet contains praseodymium and neodymium elements, and the sum of the content of praseodymium and neodymium elements is 25wt% to 32wt%.

In some embodiments of the present application, the permanent magnet contains praseodymium and neodymium elements, and the sum of the contents of praseodymium and neodymium elements is 25 wt %.

In some embodiments of the present application, the permanent magnet contains cobalt element, and the content of cobalt element is 1wt% to 2wt%.

The presence of cobalt in permanent magnets can increase coercive force and magnetic energy product.

Referring to FIG. 1 , in some embodiments of the present application, a plurality of slots 110 are provided on the end surface of the rotor core along the circumferential direction of the rotor core, and each permanent magnet 120 is correspondingly embedded in each slot 110 .

In some embodiments of the present application, the slot 110 is V-shaped.

In some embodiments of the present application, the V-shaped opening faces the stator 200 .

Since the intrinsic coercive force of rare earth magnets containing cerium is lower than that of conventional rare earth magnets, directly using rare earth magnets containing cerium will reduce the demagnetization ability of the motor. The slot 110 is V-shaped, which can enhance the anti-demagnetization ability of the motor and make the demagnetization ability of the motor not lower than that of conventional rare earth magnets.

In some other embodiments of the present application, the present application provides a compressor, which includes the motor of the present application.

It can be understood that the compressor of the present application contains the motor of the present application, and the motor includes a rotor and a stator. Among them:

The rotor comprises a rotor core and a plurality of permanent magnets arranged on the rotor core, wherein the permanent magnets contain a cerium element with a mass percentage of x%.

The stator comprises a stator core, the stator core is provided with Q stator teeth along the inner circumference direction, each stator tooth is wound with a stator winding, and the number of phases of the stator winding is m;

The mass percentage x% of the cerium element satisfies: 3%≤x%≤10%;

The width of the magnetic pole of the rotor is b _m , and b _m satisfies the relationship: b _m ≥ 3040/(165-x).

In the motor of the compressor of the present application, the permanent magnet contains x% of cerium by mass, thereby reducing the use of praseodymium, neodymium and heavy rare earth elements, and effectively controlling the cost. Since the addition of cerium will cause the remanence of the magnet B _r to decrease, in order to ensure that the efficiency of the motor can meet the demand under the condition of equivalent cost, the present application proposes a motor, according to the mass percentage of x% of cerium in the permanent magnet, the number of stator teeth Q and the number of phases m of the stator winding are developed and designed. When the number of stator teeth Q and the number of phases m of the stator winding satisfy the relationship Q/m≤3, and the pole width _bm satisfies the relationship _bm≥3040 /(165-x), the efficiency and reliability of the motor can be optimized, and the motor cost is the lowest. As a result, the compressor has higher efficiency and lower cost.

In some other embodiments of the present application, a refrigeration device is provided, and the refrigeration device includes the compressor of the present application.

It can be understood that the refrigeration equipment of the present application, because it uses the compressor of the present application, has all the effects and advantages of the above-mentioned motor and compressor. Specifically:

The refrigeration device of the present application comprises a compressor and a motor, wherein the motor comprises a rotor and a stator.

The mass percentage x% of the cerium element satisfies: 3%≤x%≤10%;

In the motor of the refrigeration equipment of the present application, the permanent magnet contains a cerium element with a mass percentage of x%, thereby reducing the use of praseodymium, neodymium and heavy rare earth elements, and effectively controlling the cost. Since the addition of cerium will cause the remanence of the magnet B _r to decrease, in order to ensure that the efficiency of the motor can meet the demand under the condition of equivalent cost, the present application proposes a motor, according to the mass percentage of cerium element x% in the permanent magnet, the number of stator teeth Q and the number of phases m of the stator winding are developed and designed, when the number of stator teeth Q and the number of phases m of the stator winding satisfy the relationship Q/m≤3, and the pole width _bm satisfies the relationship _bm≥3040 /(165-x), the efficiency and reliability of the motor can be optimized, and the motor cost is the lowest. Furthermore, the compressor is more efficient and less expensive. Finally, the performance of the refrigeration equipment is improved.

In some embodiments of the present application, the refrigeration device is an air conditioner.

In some embodiments of the present application, the air conditioner is a household air conditioner.

It should also be noted that the cerium-containing permanent magnets involved in the technical solution of this application are all products already available on the market. This application is based on the content of cerium in the cerium-containing permanent magnets, through the number of stator teeth Q and the number of phases m of the stator winding, as well as the pole width b _m of the rotor, to improve the performance of permanent magnet motors, compressors and refrigeration equipment.

In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

In this application, unless otherwise expressly specified or limited, the terms "installed", "connected", "connected", "fixed" and "connected" shall be used interchangeably. The terms "fixed" and "fixed" 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, an electrical connection, or a communication; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

An electric machine comprises a rotor and a stator, wherein:

The rotor comprises a rotor core and a plurality of permanent magnets arranged on the rotor core, wherein the permanent magnets contain a cerium element with a mass percentage of x%;

The stator comprises a stator core, wherein the stator core is provided with Q stator teeth along the inner circumference, each stator tooth is wound with a stator winding, and the number of phases of the stator winding is m;

The mass percentage x% of the cerium element satisfies: 3%≤x%≤10%;

The number of stator teeth Q and the number of phases m of the stator winding satisfy the relationship: Q/m≤3; and

The width of the magnetic pole of the rotor is b m , and b m satisfies the relationship: b m ≥ 3040/(165-x).
The motor according to claim 1, wherein the number of magnetic pole pairs of the rotor is P, and P≤3.
The motor according to claim 1 or 2, wherein the coils on the stator teeth in each phase of the stator winding are connected in series.
The motor according to any one of claims 1 to 3, wherein the coils on the stator teeth in each phase of the stator winding are connected in parallel.
The motor according to any one of claims 1 to 4, wherein the magnetic pole width b m satisfies the relationship: b m ≤ 3900/(165-x).
According to any one of claims 1 to 5, the permanent magnet contains dysprosium, and the content of the dysprosium is less than 3wt%.
The motor according to any one of claims 1 to 6, wherein the permanent magnet contains dysprosium, and the content of the dysprosium is less than 2.3wt%.
The motor according to any one of claims 1 to 7, wherein the permanent magnet contains praseodymium and neodymium elements, and the sum of the contents of the praseodymium and neodymium elements is 20wt% to 32wt%.
The motor according to any one of claims 1 to 8, wherein the permanent magnet contains cobalt element, and the content of the cobalt element is 1wt% to 2wt%.
The motor according to any one of claims 1 to 9, wherein a plurality of slots are provided on the end surface of the rotor core along the circumferential direction of the rotor core, and each of the permanent magnets is correspondingly embedded in each of the slots.
The motor according to claim 10, wherein the slot is V-shaped.
The motor according to claim 11, wherein the V-shaped opening faces the motor stator.
A compressor comprising the motor according to any one of claims 1 to 12.
A refrigeration device comprises the compressor according to claim 13.