WO2024082577A1

WO2024082577A1 - Permanent magnet motor, compressor, and refrigeration apparatus

Info

Publication number: WO2024082577A1
Application number: PCT/CN2023/087144
Authority: WO
Inventors: 杨勤; 盖蕊; 郭谨博; 姚俊; 邱小华
Original assignee: 广东美芝制冷设备有限公司
Priority date: 2022-10-21
Filing date: 2023-04-07
Publication date: 2024-04-25
Also published as: CN117955273A

Abstract

The present application provides a permanent magnet motor, a compressor, and a refrigeration apparatus. The permanent magnet motor comprises a motor rotor (100), a motor stator (200), and a stator winding. The motor rotor (100) comprises a rotor core and a plurality of permanent magnets (110) arranged on the rotor core, and the permanent magnets (110) contain x% of cerium element by mass. The motor stator (200) comprises a stator core surrounding the outer side of the rotor core, and the stator core is provided with a plurality of stator teeth (210) in an inner circumferential direction. The stator winding is wound around each stator tooth (210), the number of turns of the stator winding on each stator tooth (210) is N, and the number of branches connected in parallel in each phase of the stator winding is a. When the connection form of the stator winding on the stator teeth (210) is a Y-shaped connection, N/a satisfies N/a≤5.2(25-x); and when the connection form of the stator winding on the stator teeth (210) is a triangular connection, N/a satisfies N/a≤5.2(25-x)×sqrt(3).

Description

Permanent magnet motors, compressors and refrigeration equipment

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese patent application No. 202211296295.2, filed on October 21, 2022, and entitled “Permanent Magnet Motor, Compressor 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 permanent magnet 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. However, compared with the same praseodymium and neodymium, the remanence Br and intrinsic coercivity Hcj of the corresponding rare earth magnet will be reduced, which directly affects the motor performance and demagnetization reliability. Therefore, a new design of the motor structure is needed to meet the requirements of motor cost, motor efficiency and demagnetization reliability.

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 permanent magnet motor, a compressor containing the permanent magnet motor and a refrigeration device containing the compressor.

A first aspect of the present application provides a permanent magnet motor, comprising:

A motor rotor, comprising a rotor core and a plurality of permanent magnets arranged on the rotor core, wherein the permanent magnets contain cerium;

The motor stator comprises a stator core arranged around the outer side of the rotor core, wherein the stator core is provided with a plurality of stator teeth along the inner circumference direction;

A stator winding is wound on each of the stator teeth, the number of turns of the stator winding on each of the stator teeth is N, and the number of branches connected in parallel per phase of the stator winding is a;

The permanent magnet contains x% cerium by mass;

When the stator winding is connected to the stator teeth in a Y-shaped connection, N/a satisfies: N/a≤5.2(25-x);

When the connection form of the stator winding on the stator teeth is a triangle connection, N/a satisfies: N/a≤5.2(25-x)×sqrt(3).

According to some embodiments of the present application, when the connection form of the stator winding on the stator teeth is a Y-shaped connection, the number of turns N of the stator winding on each stator tooth satisfies: 50≤N≤90.

According to some embodiments of the present application, when the connection form of the stator winding on the stator teeth is a Y-shaped connection, the number of turns N of the stator winding on each stator tooth satisfies: 50≤N≤80.

According to some embodiments of the present application, when the connection form of the stator winding on the stator teeth is a Y-shaped connection, the number of turns N of the stator winding on each stator tooth is 80.

According to some embodiments of the present application, when the connection form of the stator winding on the stator teeth is a triangle connection, the number of turns N of the stator winding on each stator tooth satisfies: 80≤N≤170.

According to some implementations of the present application, the number a of branches connected in parallel per phase satisfies: 1≤a≤4.

According to some embodiments of the present application, stator slots are formed between adjacent stator teeth.

According to some embodiments of the present application, the number of the stator slots is 12.

According to some embodiments of the present application, the wire diameter of the stator winding is d, 0.45mm≤d≤0.9mm.

The wire diameter of 0.45mm to 0.9mm is the optimal stator winding wire diameter.

According to some embodiments of the present application, the permanent magnet contains x% by mass of cerium, and the x% satisfies: 3%≤x%≤10%.

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

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

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 praseodymium and neodymium elements is 20wt%~32wt%.

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

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

According to some embodiments of the present application, the permanent magnet contains cobalt element, and the content of the cobalt element is 1wt%~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, when a is 1, the stator windings distributed on different stator teeth are actually connected in series.

At the same power level, series windings used on motors with relatively thicker wire diameters can achieve higher back electromotive force and improve the efficiency of medium and low frequency motors.

According to some embodiments of the present application, when a is greater than 1, the stator windings distributed on different stator teeth are actually connected in parallel.

A second aspect of the present application provides a compressor, which includes the permanent magnet motor.

A third aspect of the present application provides a refrigeration device, which includes the compressor.

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

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the structure of a permanent magnet motor of the present application;

FIG2 is a comparison diagram of the motor efficiency of the present application solution and the comparative solution; and

FIG3 is a comparison diagram of the demagnetization current resistance of the solution of the present application and the comparative solution.

Reference numerals:

100: motor rotor; 110: permanent magnet; 120: slot;

200: motor stator; 210: stator teeth.

Detailed ways

The following are specific embodiments of the present application, and the technical solution of the present application is further described in combination with the embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

Referring to FIG. 1 , in some embodiments of the present application, the present application provides a permanent magnet motor, which includes a motor rotor 100 , a motor stator 200 , and a stator winding (not shown). Specifically, wherein:

The motor rotor 100 includes a rotor core and a plurality of permanent magnets 110 disposed on the rotor core, wherein the permanent magnets 110 contain cerium elements;

The motor stator 200 includes a stator core, which is disposed around the outer side of the rotor core. The stator core is provided with a plurality of stator teeth 210 along the inner circumference.

The stator winding is provided on each stator tooth 210 , the number of turns of the stator winding on each stator tooth 210 is N, and the number of branches connected in parallel per phase of the stator winding is a;

The permanent magnet 110 contains x% of cerium by mass;

When the stator winding is connected to the stator teeth 210 in a Y-shaped connection, N/a satisfies: N/a≤5.2(25-x);

When the stator winding is connected on the stator teeth 210 in a delta connection, N/a satisfies: N/a≤5.2(25-x)×sqrt(3).

It can be understood that the compressor is one of the core components of the air conditioner, and a permanent magnet motor is usually provided in the compressor. In order to meet the demand for demagnetization current of air conditioner manufacturers, the intrinsic coercive force of the neodymium iron boron permanent magnets used by the inverter models of general compressor manufacturers at 20°C is ≥1830kA/m. The permanent magnets under this coercive force all contain a large proportion of praseodymium, neodymium and heavy rare earth elements, especially dysprosium and terbium. In order to reduce the dependence on praseodymium, neodymium and heavy rare earth elements, magnets containing cerium elements are used, and the corresponding coercive force satisfies: 1500≤H _cj ≤1800kA/m. Due to the reduction of its intrinsic coercive force, under the existing permanent magnet motor design scheme, the demagnetization ability of the motor will decrease by more than 40%. In order to use rare earth magnets containing cerium elements, it is necessary to develop and design the motor for matching according to the cerium content. The permanent magnet motor of the present application includes a motor rotor 100, a motor stator 200 and a stator winding. The motor rotor 100 includes a rotor core and a plurality of permanent magnets 110 disposed on the rotor core, wherein the permanent magnets 110 contain cerium; the motor stator 200 includes a stator core, which is disposed around the outer side of the rotor core, and the stator core is provided with a plurality of stator teeth 210 along the inner circumference; a stator winding is disposed on each stator tooth 210, and the number of turns of the stator winding on each stator tooth 210 is N, and the number of branches connected in parallel per phase of the stator winding is a;

When the stator winding is connected on the stator teeth 210 in a Y-shaped connection, N/a≤5.2(25-x);

When the stator winding is connected on the stator teeth 210 in a delta connection, N/a≤5.2(25-x)×sqrt(3).

It can also be understood that in the permanent magnet motor of the present application, the permanent magnet contains cerium element, thereby reducing the use of praseodymium, neodymium and heavy rare earth elements, and effectively controlling the cost. Since the addition of cerium element will cause the magnet remanence B _r to decrease, in order to ensure that the efficiency of the permanent magnet motor can meet the demand under the condition of equivalent cost, the cerium element ratio x, the number of stator winding turns N and the number of parallel branches per phase a are matched. If the connection form of the stator winding is a Y-shaped connection, when N and a meet the N/a≤5.2(25-x) defined in the present application, the magnetic properties of the magnet meet the motor efficiency requirements, the efficiency of the motor can reach the best, the motor cost is the lowest, and the demagnetization resistance is improved most significantly; if the connection form of the stator winding is a triangle connection, when N and a meet the N/a≤5.2(25-x)×sqrt(3) defined in the present application, the magnetic properties of the magnet meet the motor efficiency requirements, the efficiency of the motor can reach the best, the motor cost is the lowest, and the demagnetization resistance is improved most significantly.

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 stator slot number 1 to stator slot number 2; while the span of the distributed winding is not 1, for example, the span is 3, and the winding is from stator slot number 1 to stator slot number 4. 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 operation noise is smaller.

It should also be noted that the "number of branches connected in parallel" refers to the circuit formed by the lead heads of multiple pole phase groups in each phase in the stator winding being directly connected to the power supply.

In some embodiments of the present application, when the connection form of the stator winding on the stator tooth 210 is a Y-shaped connection, the number of turns N of the stator winding on each stator tooth 210 satisfies: 50≤N≤90.

In some embodiments of the present application, when the connection form of the stator winding on the stator tooth 210 is a Y-shaped connection, the number of turns N of the stator winding on each stator tooth 210 satisfies: 50≤N≤80.

In some embodiments of the present application, when the connection form of the stator winding on the stator tooth 210 is a Y-shaped connection, the number of turns N of the stator winding on each stator tooth 210 is 80.

In some other embodiments of the present application, when the connection form of the stator winding on the stator tooth 210 is a triangle connection, the number of turns N of the stator winding on each stator tooth 210 satisfies: 80≤N≤170.

In some embodiments of the present application, the number a of branches connected in parallel per phase satisfies: 1≤a≤4.

In some embodiments of the present application, stator slots are formed between adjacent stator teeth 210 .

In some embodiments of the present application, the number of stator slots is 12.

It can be understood that the number of stator slots is 12, and the corresponding number of stator teeth is also 12, which can effectively reduce the number of winding turns in series on each stator tooth, thereby effectively reducing the demagnetization reverse magnetic field strength generated by the stator winding being energized, so that the demagnetization reverse magnetic field is not sufficient to demagnetize the permanent magnet, thereby improving the overall anti-demagnetization ability of the motor.

It should be noted that the demagnetization potential F=Nc×I. Among them, I is the demagnetization current, which is constant. As the number of turns Nc increases, the demagnetization potential F increases, and the magnet is easier to demagnetize. The number of turns N is the number of series turns per phase, and Nc is the number of turns on each tooth. Generally, the motor is designed as a three-phase motor. When the number of stator slots is 9, the number of slots per phase is 3. When the number of stator slots is 12, the number of slots per phase is 4. The number of series turns N remains unchanged, and the number of turns per tooth is N/3 and N/4 respectively. The more slots there are, the lower Nc is, and the lower the demagnetization potential is. Therefore, thinner magnets can be used or the coercive force H _cj of the magnet can be reduced.

In some embodiments of the present application, the wire diameter of the stator winding is d, 0.45 mm≤d≤0.9 mm.

In some embodiments of the present application, the mass percentage x% of the cerium element in the permanent magnet 110 satisfies: 3%≤x%≤10%.

Since the more cerium content in the magnet, the smaller the magnet remanence _Br value, when the mass percentage of cerium in the permanent magnet exceeds 10%, the _Br value decreases significantly, the excitation magnetic field of the permanent magnet motor is too small, and the motor efficiency is poor. When the permanent magnet motor is used in a compressor, it cannot meet the energy efficiency requirements of the compressor. The protection range of 3% to 10% for the cerium content x% in this application is a suitable range, within which the optimal motor efficiency and demagnetization resistance can be achieved.

In some embodiments of the present application, the permanent magnet 110 contains dysprosium, and the content of dysprosium is less than 3 wt %.

In some embodiments of the present application, the permanent magnet 110 contains dysprosium, and the content of dysprosium is less than 2.3 wt %.

In some embodiments of the present application, the permanent magnet 110 contains dysprosium, and the content of dysprosium is about 2.25 wt %.

In some embodiments of the present application, in the permanent magnet 110 , the sum of the content of praseodymium and neodymium elements is 20 wt % to 32 wt %.

In some embodiments of the present application, in the permanent magnet 110 , the sum of the content of praseodymium and neodymium elements is 25 wt % to 32 wt %.

In some embodiments of the present application, in the permanent magnet 110 , the sum of the content of praseodymium and neodymium elements is 25 wt %.

In some embodiments of the present application, the permanent magnet 110 contains cobalt element, and the content of cobalt element is 1wt%~2wt%.

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

In some embodiments of the present application, the slot 120 is V-shaped.

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

Since the intrinsic coercive force of the rare earth magnet containing cerium is lower than that of the existing conventional rare earth magnet, directly using the rare earth magnet containing cerium will reduce the demagnetization ability of the motor. The slot 120 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 the existing conventional rare earth magnet.

In some embodiments of the present application, in each phase of the stator winding, the stator windings distributed on different stator teeth 210 are connected in series or in parallel.

In some embodiments of the present application, when a is 1, the stator windings distributed on different stator teeth are actually 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, when a is greater than 1, the stator windings distributed on different stator teeth are actually connected in parallel.

It can 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.

Refer to the scheme and comparative scheme of the present application in Table 1 to better understand the technical scheme of the present application. In Table 1, the scheme of the present application refers to the case where the connection form of the stator winding of the permanent magnet motor is a Y-shaped connection. When x% is 7.0%, N is 80, and a is 1, 5.2(25-x)=93.6, which satisfies the N/a≤5.2(25-x) specified in the present application. At this time, the motor efficiency is 93.2%, and the demagnetization current is 22A at the same demagnetization rate.

The comparison scheme refers to the case where the connection form of the stator winding of the permanent magnet motor is a Y-shaped connection. When x% is 7.0%, N is 100, and a is 1, 5.2(25-x)=93.6, which does not meet the N/a≤5.2(25-x) specified in this application. At this time, the motor efficiency is 92.8%, and the demagnetization current at the same demagnetization rate is 18A.

The details are shown in Table 1, Figure 2 and Figure 3.

Table 1 Comparison of N, a, motor efficiency and demagnetization current

serial number	N	x/%	a	5.2(25-x)	Whether N/a≤5.2(25-x) is satisfied	Motor efficiency (%)	Demagnetization current at the same demagnetization rate/A
This application plan	80	7.0	1	93.6	yes	93.2%	twenty two
Comparison plan	100	7.0	1	93.6	no	92.8%	18

From the results in Table 1, it can be seen that the permanent magnet motor solution of the present application has improved motor efficiency and demagnetization current. Therefore, it can be seen that the design scheme of the present application has a double efficiency-enhancing effect on the permanent magnet motor.

It should be noted that in Table 1, in the solution of the present application and the comparative solution, the content of praseodymium and neodymium in the permanent magnet motor is 25wt%, the content of cerium is 7wt%, the content of dysprosium is 2.25wt%, the content of cobalt is 1.5wt%, and the remaining element is iron. The permanent magnet can be directly purchased from the market.

It should also be noted that Table 1 shows the case of a Y-shaped connection. If it is a triangle connection, the number of turns of the triangle winding can be equivalent to the number of turns of the star winding/sqrt(3). In addition, it should be noted that the value range of the number of turns N of the stator winding is different in the Y-shaped connection and the triangle connection. Specifically, when the connection form of the stator winding on the stator teeth is a Y-shaped connection, the number of turns N of the stator winding on each stator tooth satisfies: 50≤N≤90. When the connection form of the stator winding on the stator teeth is a triangle connection, the number of turns N of the stator winding on each stator tooth satisfies: 80≤N≤170.

In some other embodiments of the present application, a compressor is provided, which includes a permanent magnet motor.

Specifically, the compressor of the present application contains the permanent magnet motor of the present application, which includes a motor rotor 100, a motor stator 200 and a stator winding. The motor rotor 100 includes a rotor core and a plurality of permanent magnets 110 arranged on the rotor core, and the permanent magnets 110 contain cerium elements; the motor stator 200 includes a stator core, which is arranged around the outer side of the rotor core, and the stator core is provided with a plurality of stator teeth 210 along the inner circumference; the stator winding is arranged on each stator tooth 210, and the number of turns of the stator winding on each stator tooth 210 is N, and the number of branches connected in parallel per phase of the stator winding is a;

The permanent magnet 110 contains x% of cerium by mass;

Furthermore, in the compressor of the present application, the permanent magnet 110 contains cerium, 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 _Br to decrease, in order to ensure that the efficiency of the permanent magnet motor can meet the demand under the condition of equivalent cost, a matching design is carried out for the number of turns N of the stator winding and the number a of branches connected in parallel per phase. If the connection form of the stator winding is a Y-shaped connection, when N and a meet the N/a≤5.2(25-x) specified in the present application, the magnetic properties of the magnet meet the motor efficiency requirements, the motor efficiency can be optimized, the motor cost is the lowest, and the demagnetization resistance is improved most significantly; if the connection form of the stator winding is a triangle connection, when N and a meet the N/a≤5.2(25-x)×sqrt(3) specified in the present application, the magnetic properties of the magnet meet the motor efficiency requirements, the motor efficiency can be optimized, the motor cost is the lowest, and the demagnetization resistance is improved most significantly. As a result, the efficiency of the compressor can be optimized, the motor cost can be minimized, and the demagnetization resistance can be improved most significantly.

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

It is easy to understand that the refrigeration equipment of the present application, because the compressor of the present application is used, has all the effects and advantages of the above-mentioned permanent magnet motor and compressor. Specifically, the refrigeration equipment of the present application, because the compressor of the present application is used, has all the effects and advantages of the above-mentioned permanent magnet motor and compressor.

Furthermore, the refrigeration equipment of the present application contains the compressor of the present application, and the compressor contains the permanent magnet motor of the present application, and the permanent magnet motor includes a motor rotor, a motor stator and a stator winding. Among them, the motor rotor includes a rotor core and a plurality of permanent magnets arranged on the rotor core, and the permanent magnets contain cerium elements; the motor stator includes a stator core, and the stator core is arranged around the outer side of the rotor core, and the stator core is provided with a plurality of stator teeth along the inner circumference; the stator winding is arranged on each stator tooth, and the number of turns of the stator winding on each stator tooth is N, and the number of branches connected in parallel per phase of the stator winding is a;

The permanent magnet contains x% of cerium by mass;

When the stator winding is connected on the stator teeth in a Y-shaped connection, N/a satisfies: N/a≤5.2(25-x);

When the stator winding is connected on the stator teeth in a delta connection, N/a satisfies: N/a≤5.2(25-x)×sqrt(3).

In the refrigeration equipment of the present application, the permanent magnet motor used in the compressor contains cerium element in the permanent magnet, thereby reducing the use of praseodymium, neodymium and heavy rare earth elements, and effectively controlling the cost. Since the addition of cerium element will cause the remanence of the magnet B _r to decrease, in order to ensure that the efficiency of the permanent magnet motor can meet the demand under the condition of equivalent cost, the present application is designed to match the number of stator winding turns N and the number of branches in parallel per phase according to the cerium element content. If the connection form of the stator winding is a Y-shaped connection, when N and a meet the N/a≤5.2(25-x) defined in the present application, the magnetic properties of the magnet meet the motor efficiency use requirements, the motor efficiency can reach the optimal, the motor cost is the lowest, and the demagnetization resistance is improved most significantly; if the connection form of the stator winding is a triangle connection, when N and a meet the N/a≤5.2(25-x)×sqrt(3) defined in the present application, the magnetic properties of the magnet meet the motor efficiency use requirements, the motor efficiency can reach the optimal, the motor cost is the lowest, and the demagnetization resistance is improved most significantly. As a result, the efficiency of the compressor can be optimized, the motor cost can be minimized, and the demagnetization resistance can be improved significantly. Ultimately, the performance of the refrigeration equipment is also improved.

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

By arranging the compressor in the air conditioner, the overall performance of the air conditioner is improved.

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 magnet, and through the structural design of the number of turns N of the stator winding and the number of branches a in parallel per phase of the stator winding, ultimately improving the performance of permanent magnet motors, compressors and refrigeration equipment. In other words, the technical solution of this application does not involve improvements in the content of cerium and other elements in permanent magnets.

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 clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like 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, 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

A permanent magnet motor, comprising:

A motor rotor (100) comprises a rotor core and a plurality of permanent magnets (110) arranged on the rotor core, wherein the permanent magnets (110) contain cerium elements;

A motor stator (200), comprising a stator core arranged around the outside of the rotor core, the stator core being provided with a plurality of stator teeth (210) along an inner circumferential direction; and

A stator winding is wound on each of the stator teeth (210), the number of turns of the stator winding on each of the stator teeth (210) is N, and the number of branches connected in parallel per phase of the stator winding is a;

The permanent magnet (110) contains x% of cerium by mass;

When the connection form of the stator winding on the stator tooth (210) is a Y-shaped connection, N/a satisfies: N/a≤5.2(25-x);

When the connection form of the stator winding on the stator tooth (210) is a triangle connection, N/a satisfies: N/a≤5.2(25-x)×sqrt(3).
The permanent magnet motor according to claim 1, wherein, when the connection form of the stator winding on the stator tooth (210) is a Y-shaped connection, the number of turns N of the stator winding on each stator tooth (210) satisfies: 50≤N≤90.
The permanent magnet motor according to claim 1 or 2, wherein, when the connection form of the stator winding on the stator tooth (210) is a delta connection, the number of turns N of the stator winding on each stator tooth (210) satisfies: 80≤N≤170.
The permanent magnet motor according to any one of claims 1 to 3, wherein the number a of branches connected in parallel per phase satisfies: 1≤a≤4.
The permanent magnet motor according to any one of claims 1 to 4, wherein the wire diameter of the stator winding is d, and d satisfies: 0.45 mm ≤ d ≤ 0.9 mm.
The permanent magnet motor according to any one of claims 1 to 5, wherein the mass percentage x% of the cerium element in the permanent magnet (110) satisfies: 3%≤x%≤10%.
The permanent magnet motor according to any one of claims 1 to 6, wherein the permanent magnet (110) contains praseodymium and neodymium elements, and the sum of the contents of the praseodymium and neodymium elements in the permanent magnet (110) is 20 wt% to 32 wt% by mass.
The permanent magnet motor according to any one of claims 1 to 7, wherein the permanent magnet contains dysprosium element, and the dysprosium element content is less than 3wt%.
The permanent magnet 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%~2wt%.
The permanent magnet motor according to any one of claims 1 to 9, wherein a plurality of slots (120) are provided on the end surface of the rotor core along the circumferential direction of the rotor core, and each of the permanent magnets (110) is correspondingly embedded in each of the slots (120).
The permanent magnet motor according to claim 10, wherein the slot (120) is V-shaped.
A compressor, comprising the permanent magnet motor according to any one of claims 1 to 11.
A refrigeration device comprises the compressor according to claim 12.