A high-efficiency wide-speed permanent magnet synchronous motor and speed regulation method thereof

Abstract

The present invention relates to the field of motor technology, and in particular to a high-efficiency, wide-speed-regulating permanent magnet synchronous motor and a speed regulation method thereof. It comprises a motor main shaft and a rotor meshed with each other, a stator is embedded in the outer circumference of the rotor, and a moving device for adjusting the size of the area facing the stator and the rotor is provided at the end of the motor main shaft. The moving device comprises a servo motor arranged at the tail end of the motor main shaft, and the servo motor main shaft is fastened with a driving gear; a lead screw is symmetrically arranged at the end of the parallel motor main shaft, one end of the lead screw is fixedly sleeved with an annular electromagnet, and the other end of the lead screw is connected to a lead screw positioning piece; the driving gear is meshed with a gear nut, and the gear nut is meshed with a lead screw nut, and the lead screw nut is fixedly sleeved on the lead screw; an armature is provided at the end of the rotor, and the annular electromagnet is directly opposite to the armature. The speed regulation of the permanent magnet synchronous motor of the present invention is safe and reliable.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to a high-efficiency, wide-speed-regulating permanent-magnet synchronous motor and a speed regulation method thereof. Background Art

[0002] As the country promotes the development of new energy vehicles, the demand for permanent magnet synchronous motors in automobiles is increasing, and the requirements for motors and batteries are also getting higher and higher. Since the power supply voltage of new energy vehicles is fixed, and the rated back electromotive force of the motor increases with the increase of the motor speed, and the saturation of the current regulator is caused after the DC side voltage of the inverter reaches the maximum value, in order to obtain a wider speed regulation range and achieve constant power speed regulation when running at high speed above the base speed, it is necessary to perform weak magnetic control on the motor. The idea of ​​weak magnetic control of permanent magnet synchronous motors is derived from the magnetic control of separately excited DC motors. When the terminal voltage of separately excited DC motors reaches the maximum voltage, the motor can only be operated at a higher speed at constant power by reducing the excitation current of the motor and changing the excitation flux under the condition of ensuring voltage balance. In other words, separately excited DC motors can achieve the purpose of weak magnetic speed expansion by reducing the excitation current. For permanent magnet synchronous motors, the excitation magnetomotive force cannot be adjusted due to the permanent magnets. The only way to achieve the purpose of weak magnetic field speed expansion is to adjust the stator current, that is, to increase the stator direct-axis demagnetization current component to maintain the voltage balance during high-speed operation. However, by increasing the stator current, it is very harmful to the battery, electronic control, and motor of new energy vehicles. In many cases, high temperature and high discharge will occur due to unsatisfactory control, which will cause the car to smoke, catch fire, etc. Summary of the invention

[0003] In response to the above technical problems, the present invention controls the back electromotive force of the motor by controlling the position of the rotor permanent magnet in the stator coil of the motor. There is no need to achieve high-speed operation through weak magnetic control such as increasing the current, so that the motor can operate in an efficient and safe range.

[0004] In order to solve the above technical problems, the specific solution provided by the present invention is as follows: a high-efficiency, wide-speed-regulating permanent magnet synchronous motor, comprising a motor main shaft and a rotor meshing with each other, a stator embedded in the outer periphery of the rotor, and a moving device for adjusting the size of the facing area between the stator and the rotor is provided at the end of the motor main shaft.

[0005] Further: in the above-mentioned high-efficiency and wide-speed-regulating permanent magnet synchronous motor, the motor main shaft has external splines, the rotor has internal splines, and the inner circumference of the stator is evenly distributed with protrusions.

[0006] The moving device includes a servo motor arranged at the tail end of the motor main shaft, and the servo motor main shaft is tightly connected to a driving gear; a lead screw is symmetrically arranged at the end parallel to the motor main shaft, one end of the lead screw is fixedly sleeved with an annular electromagnet, and the other end of the lead screw is connected to a lead screw positioning piece; the driving gear is meshed with a gear nut, and the gear nut is meshed with a lead screw nut, and the lead screw nut is fixedly sleeved on the lead screw; an armature is arranged at the end of the rotor, and the annular electromagnet is directly opposite to the armature.

[0007] The rotor is a surface mounted permanent magnet or an embedded permanent magnet. The stator is an assembled type or an integrated type. The motor further comprises a front cover, a rear cover, and a housing arranged between the front cover and the rear cover. The motor further comprises a protective cover arranged at the rear end of the servo motor.

[0008] The present invention also provides a speed regulation method for the above-mentioned high-efficiency wide speed regulation permanent magnet synchronous motor, the speed regulation steps are:

[0009] A. When the required speed of the motor is within the rated speed range, the servo motor rotates in the positive direction to drive the driving gear to rotate, and the gear nut meshing with the driving gear also rotates, so that the lead screw moves toward the front end cover of the motor; due to the action of the electromagnet, the rotor with internal splines also moves with the movement of the electromagnet fastened to the lead screw, so that the rotor with internal splines moves toward the front end cover of the motor, so that the radial centerline position of the rotor coincides with the centerline position of the stator, and the effective magnetic induction area of ​​the rotor and the stator is maximized;

[0010] B. When the required speed of the motor exceeds the rated speed, the servo motor rotates in the opposite direction to drive the drive gear to rotate, and the gear nut meshing with the drive gear also rotates, thereby causing the lead screw to move toward the rear end cover of the motor. Due to the action of the electromagnet, the rotor with internal splines also moves with the movement of the electromagnet fastened to the lead screw, thereby moving the rotor with internal splines toward the rear end cover of the motor, causing the radial center line position of the rotor to move away from the center line position of the stator, and the effective magnetic induction area of ​​the stator and rotor is reduced.

[0011] The size of the distance is related to how much the motor speed exceeds the rated speed. The more the motor speed exceeds the rated speed, the greater the distance between the rotor radial centerline position and the stator centerline position, and the smaller the effective magnetic induction area between the stator and the rotor.

[0012] Back EMF calculation;

[0013] According to Faraday's law of electromagnetic induction; electromagnetic induction refers to the phenomenon of induced electromotive force generated by changes in magnetic flux. For example, when a part of the conductor of a closed circuit moves in a magnetic field to cut the magnetic flux lines, a current will be generated in the conductor. The generated current is called induced current, and the generated electromotive force (voltage) is called induced electromotive force. The magnitude of the induced electromotive force in the circuit is proportional to the rate of change of the magnetic flux passing through the circuit, which is represented by E, E = Δφ / Δt①;

[0014] According to the laws of electromagnetism, when the magnetic field changes, the nearby conductor will generate an induced electromotive force, the direction of which conforms to Faraday's law and Lenz's law, and is exactly opposite to the voltage originally applied to both ends of the coil. This voltage is the back electromotive force.

[0015] Thus, the reverse electromotive force of the armature winding of the AC motor is derived, E = 4*K NM *f*N*K DP *φ ②

[0016] K NM ——Air gap magnetic field fundamental coefficient, when the air gap magnetic field is sinusoidally distributed, it is equal to 1.11

[0017] f——input current frequency

[0018] N——Number of turns in series of armature windings

[0019] K DP ——Armature winding coefficient

[0020] φ——Magnetic flux per pole, calculation formula of motor speed and input current frequency;

[0021] f=P*n / 60 ③

[0022] P——rotor pole pairs

[0023] n——motor speed

[0024] Magnetic flux calculation formula;

[0025] φ=B*S ④

[0026] B——Magnetic induction intensity of rotor pole

[0027] S——Effective induction area of ​​motor stator and rotor Calculation of effective induction area of ​​motor stator and rotor;

[0028] S=3.14*d*(hL) / Z ⑤

[0029] d——Inner diameter of stator

[0030] h——stator height

[0031] L——The distance between the radial centerline of the rotor and the centerline of the stator

[0032] Z——Number of stator slots obtained from equations ①, ②, ③, ④, and ⑤ above;

[0033] Motor back electromotive force E = [3.14*K NM *P*n*N*K DP *B*d*(hL)] / 15*Z

[0034] Due to motor technology and normal use, K NM , P, N, K DP , B, d, h, Z are constants (fixed values). The rated back electromotive force E of the motor increases with the increase of the motor speed. Since the DC side voltage of the inverter causes the saturation of the current regulator after reaching the maximum value, when the back electromotive force E reaches the maximum limit value, in the wide-band speed regulation, it can only be determined by the mutual conversion of the two dependent variables n and L.

[0035] Compared with the prior art, the high-efficiency and wide-speed-regulating permanent magnet synchronous motor of the present invention comprises a motor main shaft and a rotor meshed with each other, a stator is embedded in the outer periphery of the rotor, and a moving device for adjusting the size of the area facing the stator and the rotor is provided at the end of the motor main shaft. The moving device comprises a servo motor arranged at the tail end of the motor main shaft, and the servo motor main shaft is fastened with a driving gear; a screw rod is symmetrically arranged at the end of the parallel motor main shaft, one end of the screw rod is fixedly sleeved with an annular electromagnet, and the other end of the screw rod is connected to a screw rod positioning member; the driving gear is meshed with a gear nut, and the gear nut is meshed with a screw rod nut, and the screw rod nut is fixedly sleeved on the screw rod; an armature is provided at the end of the rotor, and the annular electromagnet is directly opposite to the armature. The permanent magnet synchronous motor of the present invention controls the back electromotive force voltage of the motor by controlling the position of the rotor permanent magnet in the stator coil of the motor, and does not need to realize high-speed operation by increasing the current and other weak magnetic control, so that the motor can maintain high-efficiency and safe operation in the range. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram of the longitudinal cross-section structure of the synchronous motor of the present invention;

[0037] Figure 2 The cross-sectional structure of the synchronous motor of the present invention is simplified (the radial centerline position of the rotor is close to the direction of the centerline position of the stator);

[0038] Figure 3 The cross-sectional structure of the synchronous motor of the present invention is simplified (the radial centerline of the rotor is far away from the radial centerline of the stator);

[0039] Among them, 1 is the motor spindle, 2 is the rotor, 3 is the stator, 4 is the protrusion, 5 is the servo motor, 6 is the driving gear, 7 is the lead screw, 8 is the annular electromagnet, 9 is the lead screw positioning piece, 10 is the gear nut, 11 is the lead screw nut, 12 is the armature, 13 is the front end cover, 14 is the rear end cover, 15 is the shell, and 16 is the protective cover. DETAILED DESCRIPTION

[0040] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0041] like Figure 1-3 :A high-efficiency, wide-speed-regulating permanent magnet synchronous motor comprises a motor main shaft 1 and a rotor 2 meshed with each other, a stator 3 is embedded in the outer circumference of the rotor, and a moving device for adjusting the size of the area facing the stator and the rotor is provided at the end of the motor main shaft. The motor main shaft has an external spline, the rotor has an internal spline, and the inner circumference of the stator is evenly distributed with protrusions 4. The moving device comprises a servo motor 5 arranged at the tail end of the motor main shaft, and the servo motor main shaft is fastened with a driving gear 6; a screw rod 7 is symmetrically arranged at the end of the parallel motor main shaft, one end of the screw rod is fixedly sleeved with an annular electromagnet 8, and the other end of the screw rod is connected to a screw rod positioning member 9; the driving gear is meshed with a gear nut 10, and the gear nut is meshed with a screw nut 11, and the screw nut is fixedly sleeved on the screw rod 7; an armature 12 is provided at the end of the rotor, and the annular electromagnet is opposite to the armature. The rotor 2 is a surface-mounted permanent magnet or an embedded permanent magnet. The stator 3 is assembled or integrated. The motor further comprises a front end cover 13, a rear end cover 14, and a housing 15 disposed between the front end cover and the rear end cover. The motor further comprises a protective cover 16 disposed at the rear end of the servo motor.

[0042] like Figure 2 :When the required speed of the motor is within the rated speed range, the servo motor rotates in the positive direction to drive the drive gear to rotate, and the gear nut meshing with the drive gear also rotates, so that the lead screw moves toward the front end cover of the motor; due to the action of the electromagnet, the rotor with internal splines also moves with the movement of the electromagnet fastened to the lead screw, so that the rotor with internal splines moves toward the front end cover of the motor, so that the radial center line position of the rotor coincides with the center line position of the stator, and the effective magnetic induction area of ​​the rotor and the stator is maximized;

[0043] like Figure 3:When the required speed of the motor exceeds the rated speed, the servo motor rotates in the opposite direction to drive the drive gear to rotate, and the gear nut meshing with the drive gear also rotates, so that the lead screw moves toward the rear end cover of the motor. Due to the action of the electromagnet, the rotor with internal splines also moves with the movement of the electromagnet fastened to the lead screw, so that the rotor with internal splines moves toward the rear end cover of the motor, making the radial centerline position of the rotor away from the centerline position of the stator. The size of the distance away is related to how much the motor speed exceeds the rated speed. The more the required speed of the motor exceeds the rated speed, the greater the distance between the radial centerline position of the rotor and the centerline position of the stator, and the smaller the effective magnetic induction area of ​​the stator and the rotor.

[0044] Motor back electromotive force E = [3.14*KNM*P*n*N*KDP*B*d*(hL)] / 15*Z

[0045] When the back electromotive force E reaches the maximum limit value, during wide-band speed regulation, it can only be determined by the mutual transformation of the two dependent variables n and L.

[0046] The above is a preferred implementation of the present invention. Any obvious modifications and substitutions without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A high-efficiency, wide-speed-regulating permanent magnet synchronous motor, comprising a motor main shaft (1) and a rotor (2) meshed with each other, wherein a stator (3) is embedded on the outer circumference of the rotor, and characterized in that: The end of the motor main shaft is provided with a moving device for adjusting the size of the facing area between the stator and the rotor; The motor main shaft has external splines, the rotor has internal splines, and the inner circumference of the stator is evenly distributed with protrusions (4); The moving device comprises a servo motor (5) arranged at the rear end of the motor main shaft, and the servo motor main shaft is fastened with a driving gear (6); A screw rod (7) is symmetrically arranged at the end of the parallel motor main shaft, one end of the screw rod is fixedly sleeved with a ring-shaped electromagnet (8), and the other end of the screw rod is connected to a screw rod positioning member (9); The driving gear is meshed with a gear nut (10), the gear nut is meshed with a screw nut (11), and the screw nut is fixedly sleeved on the screw (7); An armature (12) is provided at the end of the rotor, and the annular electromagnet faces the armature; The rotor (2) is a surface-mounted permanent magnet or an embedded permanent magnet.

2. The high-efficiency, wide-speed-regulating permanent magnet synchronous motor according to claim 1 is characterized in that: The stator (3) is of assembled type or integrated type.

3. The high-efficiency, wide-speed-regulating permanent magnet synchronous motor according to claim 1, characterized in that: The motor further comprises a front end cover (13), a rear end cover (14), and a housing (15) arranged between the front end cover and the rear end cover.

4. The high-efficiency, wide-speed-regulating permanent magnet synchronous motor according to claim 3 is characterized in that: The motor also includes a protective cover (16) arranged at the rear end of the servo motor.

5. A speed regulation method for a high-efficiency, wide-speed-regulating permanent magnet synchronous motor according to any one of claims 1 to 4, characterized in that: The speed adjustment steps are: A. When the required speed of the motor is within the rated speed range, the servo motor rotates in the positive direction to drive the driving gear to rotate, and the gear nut meshing with the driving gear also rotates, so that the lead screw moves toward the front end cover of the motor; due to the action of the electromagnet, the rotor with internal splines also moves with the movement of the electromagnet fastened to the lead screw, so that the rotor with internal splines moves toward the front end cover of the motor, so that the radial centerline position of the rotor coincides with the centerline position of the stator, and the effective magnetic induction area of ​​the rotor and the stator is maximized; B. When the required speed of the motor exceeds the rated speed, the servo motor rotates in the opposite direction to drive the drive gear to rotate, and the gear nut meshing with the drive gear also rotates, thereby causing the lead screw to move toward the rear end cover of the motor. Due to the action of the electromagnet, the rotor with internal splines also moves with the movement of the electromagnet fastened to the lead screw, thereby moving the rotor with internal splines toward the rear end cover of the motor, causing the radial center line position of the rotor to move away from the center line position of the stator, and the effective magnetic induction area of ​​the stator and rotor is reduced.

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