An Alternating Pole Series Magnetic Circuit Hybrid Permanent Magnet Memory Motor

Abstract

The present invention discloses an alternating-pole series magnetic circuit hybrid permanent magnet memory motor, which includes: a stator, a hybrid permanent magnet rotor, and a non-magnetic conducting shaft. The stator includes a stator yoke, stator core teeth, stator slots, and armature windings; the hybrid permanent magnet rotor includes a rotor core, V-shaped slots, straight-shaped slots, air magnetic barriers, a first permanent magnet, and a second permanent magnet. The first permanent magnet and the second permanent magnet of the present invention form a series magnetic circuit, which helps to improve the operating point of the second permanent magnet, thereby enhancing the magnetic stability effect. Moreover, the second permanent magnet is magnetized bidirectionally along the radial direction, enabling flexible adjustment of the air-gap magnetic density; an alternating-pole design is adopted, using iron core poles to replace half of the permanent magnet poles. While maintaining the torque performance of the motor, by reducing the direct-axis permanent magnet usage, the field weakening current of the motor is effectively reduced; field weakening is carried out using short-time current pulses, with almost no field weakening copper loss, and low coercivity permanent magnets can be field-weakened repeatedly online. The field weakening control is similar to traditional vector control and is easy to implement.

Description

Technical Field

[0001] The present invention belongs to the technical field of motors, and particularly relates to an alternating-pole series magnetic circuit hybrid permanent magnet memory motor. Background Art

[0002] Permanent magnet synchronous motors (PMSMs) mostly use rare earth permanent magnet materials (such as neodymium iron boron), and have advantages such as high power density, high torque density, high efficiency, and strong overload capacity. They are widely used in industries such as new energy transportation, industrial production, and household appliances.

[0003] However, due to the inherent characteristics of neodymium iron boron materials, traditional permanent magnet motors have "stuck-neck" problems such as non-adjustable air-gap magnetic field, limited speed regulation range, and low efficiency at high-speed operation. There are technical bottlenecks in the application of wide-speed direct drive scenarios. To solve the problem of non-adjustable air-gap magnetic flux density of permanent magnet motors, variable flux permanent magnet motors have become a research hotspot.

[0004] German scholar Ostrovich first proposed the concept of variable flux memory motors in 2001. Memory motors utilize the characteristic that low coercivity permanent magnets - aluminum nickel cobalt permanent magnets can be repeatedly magnetized and demagnetized under the action of current pulses, enabling adjustable motor magnetic flux, broadening the speed regulation range, and promising to achieve high efficiency operation under all working conditions. It is a truly variable flux permanent magnet motor. To ensure the torque performance of the motor, memory motors generally adopt a hybrid permanent magnet structure, that is, high coercivity permanent magnets (such as neodymium iron boron) and low coercivity permanent magnets (such as aluminum nickel cobalt) act together to achieve adjustable air-gap magnetic flux density while ensuring a certain torque density. According to the magnetic circuit structure formed by high and low coercivity permanent magnets, hybrid permanent magnet memory motors can be divided into parallel magnetic circuit types and series magnetic circuit types. Parallel magnetic circuit type memory motors have a larger magnetic flux adjustment range, but the low coercivity permanent magnets are prone to load demagnetization problems; on the other hand, series magnetic circuit type memory motors have stronger anti-load demagnetization ability, but the required magnetic flux adjustment current is larger, increasing the capacity requirement for the inverter. Therefore, it is practically necessary to design a motor that can reduce the amplitude of the magnetic flux adjustment current and the required inverter capacity.

[0005] In view of the above problems, an alternating-pole series magnetic circuit hybrid permanent magnet memory motor is proposed. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide an alternating-pole series magnetic circuit hybrid permanent magnet memory motor, which can reduce the amount of direct-axis permanent magnets and increase the direct-axis inductance without significantly reducing the motor's force and energy indicators, thereby effectively reducing the amplitude of the magnetic flux adjustment current and the required inverter capacity.

[0007] The object of the present invention can be achieved by the following technical solutions:

[0008] An alternating-pole series magnetic circuit hybrid permanent magnet memory motor, comprising a stator, a hybrid permanent magnet rotor and a non-magnetic conducting shaft. The non-magnetic conducting shaft is placed at the innermost side, and the hybrid permanent magnet rotor is placed between the stator and the non-magnetic conducting shaft.

[0009] The stator includes a stator yoke, stator core teeth and an armature winding. The armature winding is arranged on the stator core teeth. The stator core teeth are arranged between the stator yoke and the hybrid permanent magnet rotor. Stator slots are formed between adjacent stator core teeth for placing the armature winding wound on the stator core teeth. An air gap is left between the stator and the hybrid permanent magnet rotor.

[0010] The hybrid permanent magnet rotor includes a rotor core, V-shaped slots, straight slots, air magnetic barriers, first permanent magnets and second permanent magnets. The rotor core is fixedly arranged outside the non-magnetic conducting shaft. The straight slots are distributed in the rotor core in an array. The V-shaped slots are distributed in the rotor core in an array. The air magnetic barriers are arranged at both ends of the V-shaped slots and the straight slots to reduce permanent magnet leakage flux.

[0011] Further, the cross-section of the straight slot is rectangular. The second permanent magnets are installed in the straight slots. The "V" shaped openings of the V-shaped slots face the straight slots and are oriented towards the stator. The central axes of the V-shaped slots coincide with the central axes of the straight slots. The single-side cross-section of the V-shaped slot is a rectangular structure, and the first permanent magnets are installed in the straight slots.

[0012] Further, the first permanent magnets are neodymium iron boron permanent magnets, and the second permanent magnets are alnico permanent magnets. The first permanent magnets and the second permanent magnets form a series magnetic circuit. The magnetization directions of the two first permanent magnets in the same V-shaped slot are opposite. The second permanent magnets are magnetized bidirectionally along the radial direction. The magnetization state for magnetic enhancement is radial outward magnetization, and the magnetization state for field weakening is radial inward magnetization.

[0013] Advantages of the present invention:

[0014] 1. For the alternating-pole series magnetic circuit hybrid permanent magnet memory motor proposed by the present invention, the first permanent magnets arranged in the V-shaped slots and the second permanent magnets arranged in the straight slots form a series magnetic circuit, which helps to improve the operating point of the second permanent magnets, thereby enhancing the magnetic stability effect. Moreover, the second permanent magnets are magnetized bidirectionally along the radial direction, enabling flexible adjustment of the air-gap magnetic density.

[0015] 2. For the alternating-pole series magnetic circuit hybrid permanent magnet memory motor proposed by the present invention, an alternating-pole design is adopted, and half of the permanent magnet poles are replaced by iron core poles. While maintaining the torque performance of the motor, the field weakening current of the motor can be effectively reduced by reducing the direct-axis permanent magnet usage.

[0016] 3. The alternating-pole series magnetic circuit hybrid permanent magnet memory motor proposed by the present invention uses short-time current pulses for magnetic field regulation, with almost no copper loss for magnetic field regulation. Moreover, the low coercivity permanent magnets can be magnetically regulated repeatedly online. The magnetic field regulation control is similar to the traditional vector control and is easy to implement.

[0017] 4. The alternating-pole series magnetic circuit hybrid permanent magnet memory motor proposed by the present invention has a simple structure, is easy to manufacture, and the iron core pole part ensures strong mechanical reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 is the overall cross-sectional structure schematic diagram of the present invention;

[0020] Figure 2 is the magnetic field line distribution diagram in the magnetic flux increasing state of the embodiment of the present invention;

[0021] Figure 3 is the magnetic field line distribution diagram in the magnetic flux decreasing state of the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0023] In the description of the present invention, it should be understood that the terms "opening", "upper", "lower", "thickness", "top", "middle", "length", "inner", "periphery", etc. indicating the orientation or positional relationship are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the components or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present invention.

[0024] As Figure 1 shown, an alternating-pole series magnetic circuit hybrid permanent magnet memory motor includes a stator 1, a hybrid permanent magnet rotor 2, and a non-magnetic conducting shaft 3. The non-magnetic conducting shaft 3 is placed on the innermost side, and the hybrid permanent magnet rotor 2 is placed between the stator 1 and the non-magnetic conducting shaft 3.

[0025] The stator 1 includes a stator yoke 1.1, stator core teeth 1.2, and an armature winding 1.4. The armature winding 1.4 is disposed on the stator core teeth 1.2. The stator core teeth 1.2 are disposed between the stator yoke 1.1 and the hybrid permanent magnet rotor 2. A cavity, namely a stator slot 1.3, is formed between adjacent stator core teeth 1.2. The stator slot 1.3 is used to place the armature winding 1.4 wound around the stator core teeth 1.2. An air gap is left between the stator 1 and the hybrid permanent magnet rotor 2.

[0026] The hybrid permanent magnet rotor 2 includes a rotor core 2.1, V-shaped slots 2.2, straight slots 2.3, air barriers 2.4, first permanent magnets 2.5, and second permanent magnets 2.6. The rotor core 2.1 is fixedly disposed outside the non-magnetic rotating shaft 3. The straight slots 2.3 are distributed in the rotor core 2.1 in an array, and the cross-section of the straight slots 2.3 is rectangular. The second permanent magnets 2.6 are installed in the straight slots 2.3. The V-shaped slots 2.2 are distributed in the rotor core 2.1 in an array. The "V" shaped openings of the V-shaped slots 2.2 face the straight slots 2.3 and are oriented towards the stator 1. The central axes of the V-shaped slots 2.2 coincide with the central axes of the straight slots 2.3. The single-side cross-section of the V-shaped slots 2.2 is a rectangular structure, and the first permanent magnets 2.5 are installed in the straight slots 2.3. The air barriers 2.4 are disposed at both ends of the V-shaped slots 2.2 and the straight slots 2.3 for reducing permanent magnet leakage flux.

[0027] The first permanent magnets 2.5 are neodymium iron boron permanent magnets, and the second permanent magnets 2.6 are aluminum nickel cobalt permanent magnets. The first permanent magnets 2.5 and the second permanent magnets 2.6 form a series magnetic circuit. The magnetization directions of the two first permanent magnets 2.5 in the same V-shaped slot 2.2 are opposite. The second permanent magnets 2.6 are magnetized bidirectionally in the radial direction. The magnetization state for increasing magnetic flux is magnetized radially outward, and the magnetization state for weakening magnetic flux is magnetized radially inward.

[0028] The magnetic poles of the present invention are composed of two forms: permanent magnetic poles and iron core poles. One permanent magnetic pole is composed of two first permanent magnets 2.5 and one second permanent magnet 2.6 connected in series. The number of permanent magnetic poles is half of the total number of magnetic poles of the motor. The permanent magnetic poles form the north pole of the motor, and the iron core part between adjacent permanent magnetic poles acts as the south pole of the motor. It can effectively reduce the permanent magnet usage and improve the magnetic field regulation performance without significantly weakening the force and energy indexes of the motor.

[0029] The operating principle of the alternating pole series magnetic circuit hybrid permanent magnet memory motor disclosed in the present invention is as follows:

[0030] In the magnetization state for increasing magnetic flux, the magnetic flux lines are distributed as Figure 2 shown. The first permanent magnets 2.5 and the second permanent magnets 2.6 together form the north pole of the motor, and the rotor core 2.1 can converge the magnetic flux lines to form the south pole, without significantly reducing the output performance of the motor.

[0031] Utilizing the property that the magnetization state of the second permanent magnet 2.6 is easily changed, it can be magnetized and demagnetized by applying an instantaneous direct-axis current, realizing the adjustability of the air-gap magnetic density of the motor. In the demagnetized state, the magnetic field line distribution of the motor is as shown in Figure 3 shown. At this time, the magnetic field of the second permanent magnet 2.6 is weakened, and the air-gap magnetic density is reduced.

[0032] Since this motor adopts an alternating-pole structure, the permanent magnet usage on the direct axis of the motor is small, and the direct-axis inductance is large, which can effectively reduce the amplitude of the field-weakening current required and reduce the capacity of the required inverter.

[0033] In the description of this specification, the description referring to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0034] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and the above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. An alternating pole series magnetic circuit hybrid permanent magnet memory motor, comprising a stator (1), a hybrid permanent magnet rotor (2) and a non-magnetic conducting shaft (3), characterized in that, The non-magnetic rotating shaft (3) is placed at the innermost side, and the hybrid permanent magnet rotor (2) is placed between the stator (1) and the non-magnetic rotating shaft (3); The stator (1) includes a stator yoke (1.1), stator core teeth (1.2), and an armature winding (1.4). The armature winding (1.4) is arranged on the stator core teeth (1.2). The stator core teeth (1.2) are arranged between the stator yoke (1.1) and the hybrid permanent magnet rotor (2). A stator slot (1.3) is formed between adjacent stator core teeth (1.2). The stator slot (1.3) is used to place the armature winding (1.4) wound around the stator core teeth (1.2). An air gap is left between the stator (1) and the hybrid permanent magnet rotor (2); The hybrid permanent magnet rotor (2) includes a rotor core (2.1), V-shaped slots (2.2), straight slots (2.3), air barriers (2.4), a first permanent magnet (2.5), and a second permanent magnet (2.6). The rotor core (2.1) is fixedly arranged outside the non-magnetic rotating shaft (3). The straight slots (2.3) are arranged in the rotor core (2.1) in an array. The V-shaped slots (2.2) are arranged in the rotor core (2.1) in an array. The air barriers (2.4) are arranged at both ends of the V-shaped slots (2.2) and the straight slots (2.3) to reduce permanent magnet leakage flux. The magnetization directions of the first permanent magnet (2.5) and the second permanent magnet (2.6) are both outward; The rotor core (2.1) converges magnetic field lines to form the south pole of the motor, and the first permanent magnet (2.5) and the second permanent magnet (2.6) together form the north pole of the motor.

2. The alternating-pole series magnetic circuit hybrid permanent magnet memory motor according to claim 1, characterized in that The cross-section of the straight slot (2.3) is rectangular. The second permanent magnet (2.6) is installed in the straight slot (2.3). The "V" - shaped opening of the V-shaped slot (2.2) faces the straight slot (2.3) and is oriented towards the stator (1). The central axis of the V-shaped slot (2.2) coincides with the central axis of the straight slot (2.3). The single-sided cross-section of the V-shaped slot (2.2) is a rectangular structure, and the first permanent magnet (2.5) is installed in the straight slot (2.3).

3. The hybrid permanent magnet memory motor with an alternating pole series magnetic circuit according to claim 2, characterized in that The first permanent magnet (2.5) is a neodymium iron boron permanent magnet, and the second permanent magnet (2.6) is an aluminum nickel cobalt permanent magnet. The first permanent magnet (2.5) and the second permanent magnet (2.6) form a series magnetic circuit. The magnetization directions of the two first permanent magnets (2.5) in the same V-shaped slot (2.2) are opposite, and their components in the radial direction are both radially outward. The second permanent magnet (2.6) is magnetized bidirectionally in the radial direction. The magnetization state of increasing magnetic field is radially outward magnetization, and the magnetization state of weakening magnetic field is radially inward magnetization.

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