GB2609865A - High-performance permanent magnet motor with controllable magnetic field in variable operating conditions, and flux orientation design method and leakage flux - Google Patents

Abstract

A high-performance permanent magnet motor with a controllable magnetic field, comprising a stator and a rotor fixed to a rotation shaft. The stator comprises a stator core 1 and a stator winding 2. The core comprises armature teeth 1-1, a yoke, and slots between the teeth. The winding is a distributed integral slot winding and is wound on the armature teeth. The rotor comprises asymmetrical units, comprising leakage flux units 3 and torque units 4 that are alternately disposed. The leakage flux units of the rotor comprise a leakage flux magnetic bridge (fig 2, 3-4), a magnetic isolation magnetic barrier (fig 2, 3-5), and leakage flux magnetic steel, where the leakage flux magnetic bridge is located between the leakage flux magnetic steel and the air gap, and the magnetic isolation magnetic barrier is located between the leakage flux magnetic steel and the rotation shaft. The torque unit comprises a magnetic isolation magnetic barrier (fig 2, 4-4), a magnetic isolation magnetic barrier (fig 2, 4-3), and torque magnetic steel, where the magnetic isolation magnetic barrier is located between the torque magnetic steel and the rotation shaft, and the magnetic isolation magnetic barrier is located between the torque magnetic steel and the air gap. The leakage flux magnetic steel and the torque magnetic steel comprise permanent magnet arrangements.

Description

HIGH-PERFORMANCE PERMANENT MAGNET MOTOR WITH CONTROLLABLE MAGNETIC FIELD IN VARIABLE OPERATING CONDITIONS, AND FLUX ORIENTATION DESIGN METHOD AND LEAKAGE FLUX REGULATION METHOD THEREFOR

TECHNICAL FIELD

The present disclosure relates to a high-performance permanent magnet motor with a controllable magnetic field in variable operating conditions, a flux orientation design method, and a leakage flux regulation method therefor, and belongs to the fields of motor technologies, electric vehicles, and electric tractors.

BACKGROUND

With the continuous aggravation of environmental pollution and energy crisis, the transformation and upgrading of the automobile industry has been continuously promoted, and pure electric vehicles have emerged as the times require due to their characteristics of high efficiency and zero emissions. As the driving power of the electric vehicle, an automotive drive motor is the core of the whole electric vehicle and determines the power output of the electric vehicle. In recent years, permanent magnet motors have usually become a popular choice for automotive drive motors due to their advantages such as high power density and high torque density. However, the existing permanent magnet motors have many shortcomings in specific application, which are embodied in: (1) In the permanent magnet motor, a permanent magnet is used as an excitation magnetic source to replace an electric excitation magnetic source in a conventional electric excitation motor. This improves operation efficiency of the motor to some extent. However, at the same time, it is difficult to adjust a constant air-gap magnetic field of the permanent magnet. Limited by capacity of an inverter, it is difficult to accelerate the permanent magnet motor at a high speed. The conventional permanent magnet motor adopts field weakening control to weaken the air-gap magnetic field of the permanent magnet through armature reaction. However, with the increase of field weakening current, copper loss increases when the motor is at a high speed. This reduces efficiency during high-speed operation of the motor to some extent. In addition, the addition of the field weakening current also makes a permanent magnet torque of the motor to decrease. This limits a torque output capability of the motor at the high speed to some extent.

(2) In order to improve a field weakening capability of the permanent magnet motor at the high speed and overcome a shortcoming of the constant magnetic field of the conventional permanent magnet motor, a type of hybrid excitation motor has attracted attention of scholars at home and abroad. In this type of motor, an electric excitation magnetic field is added as an auxiliary magnetic field. By adjusting polarity and a direction of the electric excitation magnetic field, main flux of the motor is enhanced and weakened. This objectively overcomes the disadvantage of the constant magnetic field of the permanent magnet motor. However, the additional electric excitation magnetic field also increases the copper loss of the motor. Consequently, efficiency of this type of motor at the high speed is still low.

(3) In order to avoid the increase of copper loss caused by continuous excitation in the hybrid excitation motor, a type of memory motor in which an instantaneous excitation pulse is applied has become a research hotspot for scholars at home and abroad. This type of motor uses low-coercivity aluminum nickel cobalt permanent magnets. By applying short-time excitation pulse current online, online magnetization of the permanent magnet is implemented, and a magnetization direction and a magnetization level of the permanent magnet are changed according to a magnitude and a direction of the pulse current. This type of motor objectively improves operation efficiency of the motor at the high speed, and at the same time, makes up for the disadvantage of the non-adjustable magnetic field of the permanent magnet. However, due to the addition of additional excitation windings, complexity of the motor is greatly increased, and a difficulty of motor control is increased. In addition, the magnetization level of the motor is uncontrollable, and reliability of the motor is reduced.

In general, in terms of the current means and technologies, although a speed range of the permanent magnet motor at the high speed is partially improved, shortcomings such as reduction of efficiency at the high speed, increase of complexity of the motor, and reduction of reliability of the motor still exist. At present, an effective permanent magnet motor that has high -2 -reliability and a simple structure and that implements improvement of the speed range at the high speed and also ensures operation efficiency of the motor at the high speed is still lacked.

SUMMARY

Objective of the disclosure: To overcome shortcomings in the prior art, the present disclosure provides a high-performance permanent magnet motor with a controllable magnetic field in variable operating conditions, a flux orientation design method, and a leakage flux regulation method. In the permanent magnet motor, an oriented leakage flux unit (3) and an oriented torque unit (4) of a rotor are designed. A magnitude of leakage flux of the motor is quantitatively changed by changing armature current of the motor, to implement online adjustment of an effective air-gap magnetic field of the permanent magnet, thereby improving a speed range of the motor when the permanent magnet motor is at a high speed.

To achieve the foregoing objective, the technical solutions used in the present disclosure are as follows.

A high-performance permanent magnet motor with a controllable magnetic field in variable operating conditions is provided, including a stator and a rotor, where the stator is located on an outer side of the rotor; a layer of air gap is provided between the stator and the rotor; the rotor is fixed to a rotation shaft; the stator includes a stator core (1) and a stator winding (2), the stator core (1) includes m armature teeth (i-1) and a stator yoke, a slot shape between the armature teeth (1-1) is a pear shape, the stator winding (2) is a distributed integral slot winding, and the stator winding (2) is wound on the armature teeth (hi); and the rotor includes a plurality of asymmetrical units, including n oriented leakage flux units (3) and n oriented torque units (4) that are alternately disposed.

Further, the oriented leakage flux unit (3) of the rotor includes a leakage flux magnetic bridge (3-4), a magnetic isolation magnetic bather A (3-5), and leakage flux magnetic steel, where the leakage flux magnetic bridge (3-4) is located between the leakage flux magnetic steel and the air gap, and the magnetic isolation magnetic barrier A (3-5) is located between the leakage flux magnetic steel and the rotation shaft; the oriented torque unit (4) of the rotor includes a magnetic isolation magnetic barrier B (4-4), a magnetic isolation magnetic barrier C -3 - (4-3), and torque magnetic steel, where the magnetic isolation magnetic barrier B (4-4) is located between the torque magnetic steel and the rotation shaft, and the magnetic isolation magnetic barrier C (4-3) is located between the torque magnetic steel and the air gap.

Further, the leakage flux magnetic steel is in a shape of inverted U, and includes a permanent magnet A(3-1), a permanent magnet B (3-2), and a permanent magnet C (3-3), where the permanent magnet A(3-1) is in a shape of an inverted trapezium, and the permanent magnet B (3-2) and the permanent magnet C (3-3) form a shape of A; the torque magnetic steel is in a shape of A, and includes a permanent magnet D (4-1) and a permanent magnet E (4-2).

Further, the permanent magnet A (3-1) is radially magnetized, and the permanent magnet B (3-2) and the permanent magnet C (3-3) are forwardly magnetized; and the permanent magnet D (4-1) and the permanent magnet E (4-2) are forwardly magnetized.

Further, the stator is made of a silicon steel sheet material, the permanent magnet of the rotor is made of a neodymium iron boron material; and the leakage flux magnetic bridge (3-4) in the oriented leakage flux unit (3) of the rotor is made of a silicon steel sheet or a soft magnetic material with a low saturated magnetic induction intensity.

A flux orientation design method for the high-performance permanent magnet motor with the controllable magnetic field in the variable operating conditions according to the present disclosure is provided, specifically including the following steps: step 1: determining travel speed distribution of an electric vehicle with reference to the New European Driving Cycle operating condition, and providing a speed regulation range requirement of an automotive motor according to the speed distribution; and providing an output torque requirement of the automotive motor for a specific electric vehicle model; step 2: determining a power magnitude of the motor with reference to the speed regulation range and the torque output requirement of the motor, and providing basic dimensions of the motor according to a power dimension equation; step 3: considering a leakage flux variability effect of the motor, and determining a pole-slot combination of the motor; step 4: determining a size of the leakage flux magnetic bridge (3-4): providing a leakage flux orientation design idea, and intentionally disposing a leakage flux bypass on a q-axis magnetic circuit of the motor to guide leakage flux of the motor to pass through, where flux of the motor is divided into two parts: main flux and the leakage flux, and a magnitude of the leakage flux of the motor is changed by adjusting the size of leakage flux magnetic bridge (34); and providing a leakage flux factor coefficient A with a value between 0 and 1, where the leakage flux factor coefficient A is used to measure importance of the speed regulation range and the torque output capability of the motor; step 5: after providing the leakage flux factor coefficient A, providing an optimized objective function of the motor with reference to the leakage flux factor coefficient, and optimizing parameters of the motor by using an optimal algorithm of a motor in a plurality of operating conditions, to provide optimal parameter values of the motor; and step 6: verifying electromagnetic performance of the provided optimal parameter values of the motor, including: verifying whether an output power, an output torque, and a speed regulation range meet a preset requirement, and if not, repeating the foregoing steps until the electromagnetic performance of the motor meets the requirement.

Further, there are mainly two ways of guiding the leakage flux of the motor to pass through: first, designing a width of the leakage flux bypass, to make adjacent permanent flux form a closed loop on the leakage flux bypass of the rotor rather than pass through the air gap; and second, changing a material attribute of the leakage flux bypass, and using a material that has low magnetic resistance and that is easily saturated to reduce magnetic resistance of the leakage flux bypass, to make the permanent flux preferentially form a closed loop on the leakage flux bypass of the rotor.

Further, the size of the leakage flux magnetic bridge (3-4) has an effect of changing the magnitude of the leakage flux of the motor, and a width of the leakage flux magnetic bridge is 0.1 times to 0.5 times of a radius of the rotor.

Further, for an automotive motor having a requirement for a high torque output capability, a value of the leakage flux factor coefficient A is reduced; and for an automotive motor having a requirement for a wide speed regulation range, the value of the leakage flux factor coefficient is increased.

In a leakage flux regulation method for the high-performance permanent magnet motor with the controllable magnetic field in the variable operating conditions according to the present disclosure, a magnitude of armature current fed into the stator winding (2) is changed to make the leakage flux in the leakage flux magnetic bridge (3-4) passively adjusted, and a relationship satisfies: =k where //,.; is the leakage flux of the motor, iq is a value of the armature quadrature-axis current, k is a leakage flux constant, a value of k is between 0.01 and 0.1, and the leakage flux yto of the motor is 0.1 times to 0.5 times of permanent flux yfinn of the motor.

Compared with the prior art, the high-performance permanent magnet motor with the controllable magnetic field in the variable operating conditions and the flux orientation design method provided in the present disclosure have the following beneficial effects.

1. In the present disclosure, asymmetrical units of a rotor are constructed, to implement decoupling between a leakage flux magnetic circuit and a main magnetic circuit. When the motor operates at a high speed, oriented leakage flux reduces effective air-gap flux, and improves a field weakening capability of the motor at the high speed, and reduces iron loss of the motor at the high speed. This helps stable operation and wide-area high efficiency of the motor at the high speed. When the motor operates at a low speed, armature current increases, q-axis flux is coupled to a d-axis magnetic circuit, the oriented leakage flux is reduced, leakage flux magnetic steel and torque magnetic steel jointly generate effective permanent magnet air-gap flux of the motor, and the main flux of the motor greatly increases, so that a loading capability of the motor at the low speed is improved.

2. Designs of the leakage flux magnetic steel and the torque magnetic steel are directly coupled to operating characteristics of a low-speed constant torque region and a high-speed constant power region of the motor, When different torque and rotation speed requirements are provided, by adjusting the designs of the leakage flux magnetic steel and the torque magnetic steel, requirements for an electric tractor with different working requirements and working modes are implemented. By designing the magnetic steel and magnetic bridge in an orientated leakage flux region of the motor, a leakage flux state of the motor is changed, to implement high-efficiency operation when the motor is at the high speed. On the other hand, by changing the magnetic steel in an oriented torque region of the motor, a magnitude of effective flux in the low-speed constant torque region of the motor is changed, to improve a loading capability of the motor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structural diagram of a high-performance permanent magnet motor with a controllable magnetic field in variable operating conditions of the present disclosure.

FIG. 2 is a structural diagram of the oriented leakage flux unit (3) and the oriented torque unit (4) in FIG. 1, where arrow directions in the figure are magnetizing directions.

FIG. 3 is a diagram of magnetic circuit analysis of the oriented leakage flux unit (3) in a high-performance permanent magnet motor with a controllable magnetic field in variable operating conditions of the present disclosure.

FIG. 4 is a diagram of magnetic circuit analysis of the oriented torque unit (4) in a high-performance permanent magnet motor with a controllable magnetic field in variable operating conditions of the present disclosure.

FIG. 5 is a curve diagram of a change of a simulated d-axis magnetic linkage with q-axis current in a high-performance permanent magnet motor with a controllable magnetic field in variable operating conditions of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present disclosure is further described below with reference to the accompanying drawings.

As shown in FIG 1 to FIG 5, a high-performance permanent magnet motor with a controllable magnetic field in variable operating conditions includes a stator and a rotor, where the stator is located on an outer side of the rotor; a layer of air gap is provided between the stator and the rotor, the rotor is fixed to a rotation shaft; the stator includes the stator core (1) and the stator winding (2), the stator core (1) includes m armature teeth (1-1) and a stator yoke, a slot shape between the armature teeth (1-1) is a pear shape, the stator winding (2) is a distributed integral slot winding, and the stator winding (2) is wound on the armature teeth (1U; and the rotor includes a plurality of asymmetrical units, including n oriented leakage flux units (3) and n oriented torque units (4) that are alternately disposed.

The oriented leakage flux unit (3) of the rotor includes the leakage flux magnetic bridge (3-4), the magnetic isolation magnetic barrier A (3-5), and leakage flux magnetic steel, where the leakage flux magnetic bridge (3-4) is located between the leakage flux magnetic steel and the air gap, and the magnetic isolation magnetic barrier A (3-5) is located between the leakage flux magnetic steel and the rotation shaft; the oriented torque unit (4) of the rotor includes the magnetic isolation magnetic barrier B (4-4), the magnetic isolation magnetic barrier C (4-3), and torque magnetic steel, where the magnetic isolation magnetic barrier B (4-4) is located between the torque magnetic steel and the rotation shaft, and the magnetic isolation magnetic barrier C (4-3) is located between the torque magnetic steel and the air gap The leakage flux magnetic steel is in a shape of inverted U, and includes the permanent magnet A (3-1), the permanent magnet B (3-2), and the permanent magnet C (3-3), where the permanent magnet A (3-1) is in a shape of an inverted trapezium, and the permanent magnet B (3-2) and the permanent magnet C (3-3) form a shape of A; the torque magnetic steel is in a shape of A, and includes the permanent magnet D (4-1) and the permanent magnet E (4-2).

The permanent magnet A (3-1) is radially magnetized, and the permanent magnet B (3-2) and the permanent magnet C (3-3) are forwardly magnetized; and the permanent magnet D (41) and the permanent magnet E (4-2) are forwardly magnetized Preferably, the stator core (1) and the rotor core (5) are made of a silicon steel sheet material, the leakage flux magnetic steel and the torque magnetic steel of the rotor are made of a neodymium iron boron material; and the leakage flux magnetic bridge (3-4) in the oriented leakage flux unit (3) of the rotor is made of a silicon steel sheet or a soft magnetic material with a low saturated magnetic induction intensity.

A flux orientation design method specifically includes the following steps.

Step 1: travel speed distribution of an electric vehicle is determined with reference to the New European Driving Cycle operating condition, and a speed regulation range requirement of an automotive motor is provided according to the speed distribution; and for a specific electric -a -vehicle model, energy consumption distribution and a wheel torque output of the motor are determined with reference to parameters of the whole vehicle, including mass of the whole vehicle, a rolling resistance coefficient, a travel slope of the whole vehicle, an air resistance coefficient, a frontal area of the whole vehicle, and a rotating mass coefficient of the vehicle, and an output torque requirement of the automotive motor is provided.

Step 2: a power magnitude of the motor is determined with reference to the speed regulation range and the torque output requirement of the motor, and outer diameter and axial length dimensions of the motor are provided according to a power dimension equation Step 3: a leakage flux variability effect of the motor is fully considered, and a pole-slot combination of the motor is determined.

Step 4: a size of the leakage flux magnetic bridge (3-4) is determined: a leakage flux orientation design idea is provided, and a leakage flux bypass is intentionally disposed on a axis magnetic magnetic circuit of the motor to guide leakage flux of the motor to pass through, where flux of the motor is divided into two parts: main flux and the leakage flux, and a magnitude of the leakage flux of the motor may be changed by adjusting the size of leakage flux magnetic bridge (3-4); and a leakage flux factor coefficient X. with a value between 0 and 1 is provided, where the leakage flux factor coefficient ?c is used to measure importance of the speed regulation range and the torque output capability of the motor.

Step 5: after the leakage flux factor coefficient X, is provided, an optimized objective function of the motor is provided with reference to the leakage flux factor coefficient, and parameters of the motor are optimized by using an optimal algorithm of a motor in a plurality of operating conditions, to provide optimal parameter values of the motor.

Step 6: electromagnetic performance of the provided optimal parameter values of the motor is verified, including: verifying whether an output power, an output torque, and a speed regulation range meet a preset requirement, and if not, repeating the foregoing steps until the electromagnetic performance of the motor meets the requirement.

In the step 3, a leakage flux saturation effect of the motor is considered. The pole-slot combination of the permanent magnet motor with a controllable magnetic field in variable operating conditions should adopt a distributed integral slot winding, and a pole pitch is an integer. In addition, a span is made to be equal or close to the pole pitch. For a 36-slot stator slot structure, 36 slots with six poles are a preferred pole-slot combination scheme, and 36 slots with 8 poles, 36 slots with 10 poles, 36 slots with N poles, 36 slots with 16 poles, 36 slots with 20 poles, 36 slots with 22 poles, and 36 slots with 24 poles are feasible pole-slot combination schemes. For a 48-slot stator slot structure, 48 slots with 8 poles are a preferred pole-slot combination scheme, and 48 slots with 10 poles, 48 slots with 14 poles, 48 slots with 18 poles, 48 slots with 20 poles, 48 slots with 22 poles, 48 slots with 26 poles, 48 slots with 28 poles, 48 slots with 30 poles, and 48 poles with 32 poles are feasible pole-slot combination schemes. A quantity of poles of the motor cannot exceed 2/3 of a quantity of slots of the motor. When the quantity of poles of the motor is excessive, a leakage flux variability effect is not obvious. In this embodiment, the permanent magnet motor with a controllable magnetic field in variable operating conditions adopts a 48-slot and 8-pole structure.

The oriented leakage flux unit (3) of the rotor includes the leakage flux magnetic bridge (3-4), the magnetic isolation magnetic barrier A (3-5), and leakage flux magnetic steel, where the leakage flux magnetic bridge (3-4) is located between the leakage flux magnetic steel and the air gap, and the magnetic isolation magnetic barrier A (3-5) is located between the leakage flux magnetic steel and the rotation shaft; the oriented torque unit (4) of the rotor includes the magnetic isolation magnetic barrier B (4-4), the magnetic isolation magnetic barrier C (4-3), and torque magnetic steel, where the magnetic isolation magnetic barrier B (4-4) is located between the torque magnetic steel and the rotation shaft, and the magnetic isolation magnetic barrier C (4-3) is located between the torque magnetic steel and the air gap.

The leakage flux magnetic steel of the oriented leakage flux unit (3) of the rotor is in a shape of inverted U, and includes the permanent magnet A (3-1), the permanent magnet B (32), and the permanent magnet C, where the permanent magnet A (3-1) is in a shape of an inverted trapezium, and the permanent magnet B (3-2) and the permanent magnet C (3-3) form a shape of A; the torque magnetic steel of the oriented torque unit (4) of the rotor is in a shape of A, and includes the permanent magnet D (4-1) and the permanent magnet E (4-2).

An angle between the permanent magnet B (3-2) and the permanent magnet C (3-3) should be 10 degrees to 50 degrees. In this embodiment, the angle between the permanent magnet B -10 - (3-2) and the permanent magnet C (3-3) is set to 30 degrees. An angle between the permanent magnet D (4-1) and the permanent magnet E (4-2) should be 20 degrees to 50 degrees. In this embodiment, the angle between the permanent magnet D (4-1) and the permanent magnet E (42) is set to 30 degrees.

A thickness of the permanent magnet A (3-1) should be 1 mm to 5 mm. Thicknesses of the permanent magnet B (3-2) and the permanent magnet C (3-3) should be 1 mm to 4 mm. Thicknesses of the permanent magnet D (4-1) and the permanent magnet E (4-2) should be 1 mm to 4 mm. In this embodiment, the thickness of the permanent magnet A (3-1) is 2 mm, the thickness of the permanent magnet B (3-2) and the permanent magnet C (3-3) is 2.5 mm, and the thickness of the permanent magnet D (4-1) and the permanent magnet E (4-2) is 2.5 mm.

The permanent magnet A (3-1) in the oriented leakage flux unit (3) of the rotor is radially magnetized, and the permanent magnet B (3-2) and the permanent magnet C (3-3) are forwardly magnetized; and the permanent magnet D (4-1) and the permanent magnet E (4-2) in the oriented torque zone of the rotor are forwardly magnetized.

The leakage flux regulation principle means changing a magnitude of armature current to make the leakage flux passively adjusted, and a relationship satisfies: =kh, where ipri is the leakage flux of the motor, 1, is a value of the armature quadrature-axis current, kis a leakage flux constant, a value of k is between 0.01 and 0.1, and the leakage flux gm of the motor is 0.1 times to 0.5 times of permanent flux ig,"" of the motor.

Preferably, there are mainly two ways of guiding the leakage flux to pass through: first, designing a width of the leakage flux bypass, to make adjacent permanent flux form a closed loop on the leakage flux bypass of the rotor rather than pass through the air gap; and second, changing a material attribute of the leakage flux bypass, and using a material that has low magnetic resistance and that is easily saturated to reduce magnetic resistance of the leakage flux bypass, to make the permanent flux preferentially form a closed loop on the leakage flux bypass of the rotor.

Preferably, the size of the leakage flux magnetic bridge (3-4) has an effect of changing the magnitude of the leakage flux of the motor, and a width of the leakage flux magnetic bridge is 0.1 times to 0.5 times of a radius of the rotor.

Preferably, for an automotive motor having a requirement for a high torque output capability, a value of the leakage flux factor coefficient A is reduced; and for an automotive motor having a requirement for a wide speed regulation range, the value of the leakage flux factor coefficient is increased.

Preferably, the optimized objective function is specifically represented as: F = where F represents a comprehensive evaluation value of the target function, F7 represents a comprehensive evaluation value of a target torque, and F. represents a comprehensive evaluation value of a target speed regulation range Preferably, the method for optimizing a motor in a plurality of operating conditions specifically includes the following steps: Step I: dimension parameters of the motor that need to be optimized are selected based on a structure of the motor.

Step 2: a low-speed operating condition and a high-speed operating condition of the motor are considered, sensibility of the dimension parameters for the comprehensive evaluation value of the target function is calculated separately for the two operating conditions, the parameters are divided into two layers based on values of the sensitivity: a high-sensitive layer and a low-sensitive layer, and parameters of low-sensitive layers in the low-speed operating condition and the high-speed operating condition are deleted.

Step 3: For parameters of the high-sensitive layers in the low-speed operating condition and the high-speed operating condition, an intelligent modern algorithm including a genetic algorithm, a particle swarm algorithm, and a simulated annealing algorithm is separately used in different operating conditions, and an optimal parameter combination is selected.

Step 4: optimal parameters in the low-speed operating condition are compared with optional parameters in the high-speed operating condition, an intersection set between the two is selected as a candidate point, electromagnetic performance of the motor structure based on the candidate point is compared, and optimal motor parameters are comprehensively selected.

-12 -Specifically, when the high-performance permanent magnet motor with the controllable magnetic field in the variable operating conditions has no load, one piece of leakage flux starts from the permanent magnet C (3-3), passes through the permanent magnet B (3-2) and the leakage flux magnetic bridge (3-4), and returns to the permanent magnet C (3-3), and another piece of leakage flux starts from the permanent magnet C (3-3), passes through the permanent magnet Ac-1) and the leakage flux magnetic bridge (3-4), and returns to the permanent magnet C (3-3). The leakage flux improves a field weakening capability of the motor at a high speed, thereby improving a speed regulation range of the motor and operation efficiency of the motor at the high speed Specifically, when the high-performance permanent magnet motor with the controllable magnetic field in the variable operating conditions is loaded, with an increase of the armature current of the motor, the leakage flux magnetic bridge (3-4) of the motor is gradually saturated, a leakage flux path of the motor is blocked, the leakage flux path of the motor is disappeared, and the effective main flux of the motor increases, so that the loading capability of the motor at the low speed is improved.

The foregoing are merely preferred implementations of the present disclosure, but are not intended to limit the present disclosure. Any modification, equivalent replacement, improvement, or the like made within the spirit and principles of the present disclosure shall fall within the protection scope of the present disclosure.

-13 -

Claims (9)

1. CLAIMSWhat is claimed is: 1. A high-performance permanent magnet motor with a controllable magnetic field in variable operating conditions, characterized by comprising a stator and a rotor, wherein the stator is located on an outer side of the rotor; a layer of air gap is provided between the stator and the rotor; the rotor is fixed to a rotation shaft; the stator comprises a stator core (1) and a stator winding (2), the stator core (1) comprises m armature teeth (1-1) and a stator yoke, a slot shape between the armature teeth (1-1) is a pear shape, the stator winding (2) is a distributed integral slot winding, and the stator winding (2) is wound on the armature teeth (1-1); and the rotor comprises a plurality of asymmetrical units, comprising n oriented leakage flux units (3) and n oriented torque units (4) that are alternately disposed; and the oriented leakage flux unit (3) of the rotor comprises a leakage flux magnetic bridge (34), a magnetic isolation magnetic barrier A (3-5), and leakage flux magnetic steel, wherein the leakage flux magnetic bridge (3-4) is located between the leakage flux magnetic steel and the air gap, and the magnetic isolation magnetic barrier A (3-5) is located between the leakage flux magnetic steel and the rotation shaft; the oriented torque unit (4) of the rotor comprises a magnetic isolation magnetic barrier B (4-4), a magnetic isolation magnetic barrier C (4-3), and torque magnetic steel, wherein the magnetic isolation magnetic barrier B (4-4) is located between the torque magnetic steel and the rotation shaft, and the magnetic isolation magnetic barrier C (4-3) is located between the torque magnetic steel and the air gap.
2. 2. The high-performance permanent magnet motor with the controllable magnetic field in the variable operating conditions according to claim 1, characterized in that, the leakage flux magnetic steel is in a shape of inverted U, and comprises a permanent magnet A (3-1), a permanent magnet B (3-2), and a permanent magnet C (3-3), wherein the permanent magnet A (3-1) is in a shape of an inverted trapezium, and the permanent magnet B (3-2) and the permanent magnet C (3-3) form a shape of A; the torque magnetic steel is in a shape of A, and comprises a permanent magnet D (4-1) and a permanent magnet E (4-2).
3. 3. The high-performance permanent magnet motor with the controllable magnetic field in -14 -the variable operating conditions according to claim 2, characterized in that, the permanent magnet A (3-1) is radially magnetized, and the permanent magnet B (3-2) and the permanent magnet C (3-3) are forwardly magnetized; and the permanent magnet D (4-1) and the permanent magnet E (4-2) are forwardly magnetized.
4. 4. The high-performance permanent magnet motor with the controllable magnetic field in the variable operating conditions according to claim 1, characterized in that, the stator is made of a silicon steel sheet material, the permanent magnet of the rotor is made of a neodymium iron boron material; and the leakage flux magnetic bridge (3-4) in the oriented leakage flux unit (3) of the rotor is made of a silicon steel sheet or a soft magnetic material with a low saturated magnetic induction intensity.
5. 5. A flux orientation design method for the high-performance permanent magnet motor with the controllable magnetic field in the variable operating conditions according to claim 1, characterized by specifically comprising the following steps: step 1: determining travel speed distribution of an electric vehicle with reference to the New European Driving Cycle operating condition, and providing a speed regulation range requirement of an automotive motor according to the speed distribution; and providing an output torque requirement of the automotive motor for a specific electric vehicle model; step 2: determining a power magnitude of the motor with reference to the speed regulation range and the torque output requirement of the motor, and providing basic dimensions of the motor according to a power dimension equation; step 3: considering a leakage flux variability effect of the motor, and determining a pole-slot combination of the motor; step 4: determining a size of the leakage flux magnetic bridge (3-4): providing a leakage flux orientation design idea, and intentionally disposing a leakage flux bypass on a q-axis magnetic circuit of the motor to guide leakage flux of the motor to pass through, wherein flux of the motor is divided into two parts: main flux and the leakage flux, and a magnitude of the leakage flux of the motor is changed by adjusting the size of leakage flux magnetic bridge (34); and providing a leakage flux factor coefficient A with a value between 0 and 1, wherein the leakage flux factor coefficient >I is used to measure importance of the speed regulation range -15 -and the torque output capability of the motor; step 5: after providing the leakage flux factor coefficient A, providing an optimized objective function of the motor with reference to the leakage flux factor coefficient, and optimizing parameters of the motor by using an optimal algorithm of a motor in a plurality of operating conditions, to provide optimal parameter values of the motor; and step 6: verifying electromagnetic performance of the provided optimal parameter values of the motor, comprising: verifying whether an output power, an output torque, and a speed regulation range meet a preset requirement, and if not, repeating the foregoing steps until the electromagnetic performance of the motor meets the requirement.
6. 6. The flux orientation design method for the high-performance permanent magnet motor with the controllable magnetic field in the variable operating conditions according to claim 5, characterized in that, there are mainly two ways of guiding the leakage flux of the motor to pass through: first, designing a width of the leakage flux bypass, to make adjacent permanent flux form a closed loop on the leakage flux bypass of the rotor rather than pass through the air gap; and second, changing a material attribute of the leakage flux bypass, and using a material that has low magnetic resistance and that is easily saturated to reduce magnetic resistance of the leakage flux bypass, to make the permanent flux preferentially form a closed loop on the leakage flux bypass of the rotor.
7. 7. The flux orientation design method for the high-performance permanent magnet motor with the controllable magnetic field in the variable operating conditions according to claim 5, characterized in that, the size of the leakage flux magnetic bridge (3-4) has an effect of changing the magnitude of the leakage flux of the motor, and a width of the leakage flux magnetic bridge is 0.1 times to 0.5 times of a radius of the rotor.
8. 8. The flux orientation design method for the high-performance permanent magnet motor with the controllable magnetic field in the variable operating conditions according to claim 5, characterized in that, for an automotive motor having a requirement for a high torque output capability, a value of the leakage flux factor coefficient A is reduced; and for an automotive motor having a requirement for a wide speed regulation range, the value of the leakage flux factor coefficient is increased.-16 -
9. 9. A leakage flux regulation method for the high-performance permanent magnet motor with the controllable magnetic field in the variable operating conditions according to claim 1, characterized in that, a magnitude of armature current fed into the stator winding (2) is changed to make the leakage flux in the leakage flux magnetic bridge (3-4) passively adjusted, and a relationship satisfies: vcs =k / wherein gm is the leakage flux of the motor, iq is a value of the armature quadrature-axis current, k is a leakage flux constant, a value of k is between 0.01 and 0.1, and the leakage flux ya of the motor is 0.1 times to 0.5 times of permanent flux wpm of the motor.-17 -