A tangentially magnetized segmented permanent magnet low voltage regulation rate generator rotor structure

Abstract

A tangentially magnetized segmented permanent magnet low voltage regulation rate generator rotor structure reduces the generator voltage regulation rate from the perspective of the segmented permanent magnet shape. An original permanent magnet is divided into three pieces, and the shapes of the three permanent magnets are changed without increasing the amount of permanent magnets used, and the rotor core shape changes with the change of the permanent magnet shape. The permanent magnets close to the air gap are trapezoidal permanent magnets, so that the magnetic resistance of the common magnetic flux path of the motor's AC and DC armature reactions is reduced, and the AC and DC axis magnetic fluxes are increased. The increase in the AC axis magnetic flux is greater than the increase in the direct axis magnetic flux, and the impact on the voltage regulation rate of the generator is also greater. The permanent magnets close to the rotating shaft are isosceles trapezoidal permanent magnets, and the permanent magnets in the middle are rectangular permanent magnets, so that the magnetic resistance of the motor's direct axis armature reaction magnetic flux path is increased and the direct axis magnetic flux is reduced. This block permanent magnet shape coordination increases the output voltage of the permanent magnet generator and reduces the voltage regulation rate of the generator.

Description

Technical Field

[0001] The invention relates to the technical field of permanent magnet synchronous motors, in particular to a tangential magnetized block permanent magnet low voltage regulation rate generator rotor structure. Background Art

[0002] With the improvement of permanent magnet material performance, the development of power electronics technology and the accumulation of design experience, rare earth permanent magnet motors have become widely popular. At present, they are used in many fields, such as small generators driven by internal combustion engines for independent power supplies, generators for vehicle-mounted systems, small direct-drive permanent magnet wind turbines, small hydroelectric generators and other small-power permanent magnet generator products, as well as generators for contemporary aerospace and auxiliary exciters for large thermal power plants. In addition, my country's development plans in the fields of energy and aviation also provide opportunities for the further development of permanent magnet motors.

[0003] Permanent magnet generators are excited by permanent magnets, eliminating the excitation winding, collector ring and brushes, and have a simpler structure and more reliable operation. However, when the load or speed of the generator changes, the permanent magnet generator cannot control its output voltage and power factor by adjusting the excitation magnetic field like an electrically excited synchronous generator, and excessive changes in the output voltage may even affect the normal operation of the load. Therefore, there is an urgent need to study methods to reduce the voltage regulation rate of permanent magnet motors.

[0004] Domestic and foreign scholars have proposed some methods to reduce the voltage regulation rate of motors, mainly focusing on the length of permanent magnets in the magnetizing direction, air gap length, stator slot type, core length, number of series turns per phase, permanent magnet coercive force, etc. Changing the air gap length will affect the stability and heat dissipation of the motor; increasing the length of permanent magnets in the magnetizing direction and changing the core length have a greater impact on the no-load back EMF of the motor. If the no-load back EMF of the motor is to be kept unchanged, the amount of permanent magnets must be increased, which will inevitably greatly increase the cost of the motor; and reducing the number of series turns per phase will increase the size and weight of the motor.

[0005] In order to further reduce the motor voltage regulation rate while ensuring that the motor's no-load back EMF remains basically unchanged, this study divides the permanent magnet into blocks from the perspective of permanent magnet shape. By studying the relationship between the shape and size of the divided permanent magnets and the motor voltage regulation rate, the appropriate permanent magnet shape is found to reduce the motor voltage regulation rate. Summary of the invention

[0006] In order to solve the above technical problems, the present invention proposes a tangentially magnetized segmented permanent magnet low voltage regulation rate generator rotor structure, which reduces its voltage regulation rate when the load or speed of the generator changes to avoid excessive changes in output voltage affecting the normal operation of the load.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A tangentially magnetized block permanent magnet low voltage regulation rate generator rotor structure, comprising an integrated permanent magnet and a rotor core punching sheet, wherein the integrated permanent magnet is embedded between the rotor punching sheets on both sides, and is characterized in that: the integrated permanent magnet comprises three permanent magnets, namely permanent magnet one, permanent magnet two and permanent magnet three, wherein permanent magnet one and permanent magnet three are isosceles trapezoidal permanent magnets with different bottom angles, and permanent magnet two is a rectangular permanent magnet, wherein permanent magnet two is between permanent magnet one and permanent magnet three,

[0009] The present invention divides a permanent magnet into three pieces. Under the premise of ensuring that the sum of the cross-sectional areas of the three permanent magnets remains unchanged, the shapes of the three permanent magnets are changed. The shape of the rotor core punching sheet changes with the shape of the permanent magnet, thereby changing the magnetic resistance of the cross-axis and direct-axis magnetic flux paths. The first permanent magnet and the third permanent magnet adopt isosceles trapezoidal permanent magnets, but their bottom angles are different. The second permanent magnet adopts a rectangular permanent magnet. The three permanent magnets of different shapes are matched, so that under the premise that the no-load back electromotive force of the motor remains basically unchanged, the output voltage of the motor when loaded is increased and the voltage regulation rate is reduced.

[0010] The sum of the cross-sectional areas of the permanent magnet one, the permanent magnet two and the permanent magnet three of the present invention is equal to the cross-sectional area of ​​the original permanent magnet, that is, the amount of the permanent magnets used remains unchanged.

[0011] As a further improvement of the present invention, an upper base of the permanent magnet is located on the air gap side, tangential magnetization is adopted, and the rotor core punching sheet is in close contact with one or two sides of the permanent magnet.

[0012] As a further improvement of the present invention, the second permanent magnet is tangentially magnetized, the thickness in the magnetization direction is increased, and the rotor core punching sheet is in close contact with the second permanent magnet.

[0013] As a further improvement of the present invention, the upper base of the permanent magnet three is located on the rotating shaft side, tangential magnetization is adopted, and the rotor core punching sheet is in close contact with the waist of the permanent magnet three.

[0014] As a further improvement of the present invention, the rotor core punching sheets are in close contact with the integrated permanent magnets, a rectangular groove is opened in the middle, the core punching sheets close to the air gap are widened, and the core punching sheets close to the rotating shaft are thinned.

[0015] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0016] (1) The present invention divides a permanent magnet into three pieces and then changes the shape of the divided permanent magnets, thereby reducing the voltage regulation rate of the permanent magnet generator from the perspective of the permanent magnet shape, without increasing the amount of permanent magnets used or the volume of the motor, and having little effect on the no-load back electromotive force of the motor.

[0017] (2) The shape of the permanent magnets and the shape of the rotor core punching sheets used in the present invention fit in with each other, making the permanent magnets more firmly embedded and the motor more reliable when running at high speeds.

[0018] (3) The present invention has an obvious optimization effect on the voltage regulation rate of the permanent magnet generator and is not difficult to process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the permanent magnet and the rotor core punching sheet of the present invention;

[0020] Figure 2 It is a schematic diagram of the existing permanent magnet and rotor core punching structure;

[0021] Figure 3 Taking a 10-pole 12-slot spoke motor as an example, a comparison diagram of the no-load back electromotive force of the existing permanent magnet structure and the block permanent magnet structure of the present invention;

[0022] Figure 4 Taking a 10-pole 12-slot spoke motor as an example, a comparison diagram of the output voltage under load of the existing permanent magnet structure and the block permanent magnet structure of the present invention;

[0023] Figure 5 Taking a 10-pole 12-slot spoke motor as an example, a comparison diagram of the DC-axis inductance under load of the existing permanent magnet structure and the block permanent magnet structure of the present invention is shown.

[0024] The parts are marked as follows:

[0025] 1. Permanent magnet one; 2. Permanent magnet two; 3. Permanent magnet three; 4. Rotor core punching sheet. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further described in detail below through specific implementation methods. It should be noted that the following embodiments are only used to illustrate the technical solution of the present invention rather than to limit it; although the present invention is described in detail with reference to the preferred embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents; without departing from the spirit of the technical solution of the present invention, they should all be included in the scope of the technical solution claimed for protection by the present invention.

[0027] like Figure 1 As shown, the present invention discloses a tangential magnetized block permanent magnet low voltage regulation rate generator rotor structure, the method is to Figure 2 A permanent magnet is divided into three pieces. Without changing the sum of the cross-sectional areas of the three permanent magnets, the shapes of the three permanent magnets are changed. The rotor core punchings are in close contact with the permanent magnets. The shapes of the permanent magnets are changed according to the specific conditions of the AC and DC axis armature reaction flux paths of the motor, so that the AC-axis armature reaction reactance is increased and the output voltage of the generator under load is improved.

[0028] like Figure 1As shown, permanent magnet 1 adopts trapezoidal permanent magnet, tangential magnetization, and the bottom angle of permanent magnet is relatively large, because the quadrature axis magnetic flux is mainly concentrated in the tooth part of the rotor core punching sheet 4 near the permanent magnet, and the trapezoidal permanent magnet with a larger bottom angle is used, which is beneficial to increase the rotor core punching sheet area in this area, increase the quadrature axis magnetic flux, increase the quadrature axis armature reaction reactance, and thus improve the output voltage of the generator under load. Permanent magnet 2 adopts rectangular permanent magnet, tangential magnetization, and the thickness of the rectangular permanent magnet in the magnetization direction is relatively thick, because part of the direct axis magnetic flux passes through the permanent magnet and is closed, and increasing the thickness of the permanent magnet in the magnetization direction is beneficial to increase the magnetic resistance of the direct axis magnetic circuit, reduce the direct axis magnetic flux, and reduce the direct axis armature reaction reactance. Permanent magnet 3 adopts trapezoidal permanent magnet, the purpose of which is to reduce the amount of permanent magnets used in this part and increase the thickness of the rectangular permanent magnet.

[0029] In order to determine the specific size of the block permanent magnet, the motor must first be parametrically modeled using finite element software, and the size variables of the block permanent magnet must be set. The block permanent magnet topology structure satisfies the sum of the cross-sectional areas as a constant. Then, current is passed through the stator winding to simulate the cross-axis flux path when id=0 and the direct-axis flux path when iq=0, respectively. The size of the block permanent magnet is preliminarily determined based on the cross-axis and direct-axis flux paths. Then, discrete sampling simulation is performed on all size variables of the permanent magnet. Based on the comparative simulation, the no-load back electromotive force and load output voltage of the motor under different sizes of block permanent magnets are obtained, and the size of the block permanent magnet is further determined. Finally, the multi-size variable optimization of the block permanent magnet structure is performed to determine the size of the final block permanent magnet. Example

[0030] This example uses a 10-pole 12-slot spoke permanent magnet motor as the object for verification, and the parameters are as follows:

[0031]

[0032] like Figure 3 As shown in the figure, the no-load back EMF fundamental effective value of the existing permanent magnet structure motor is 183.8V, and the no-load back EMF fundamental effective value of the permanent magnet structure motor using the present invention to change the shape of the segmented permanent magnet is 181.9V, indicating that the present invention has little effect on the no-load back EMF of the permanent magnet motor. Figure 4 As shown in the figure, the load output voltage fundamental effective value of the existing permanent magnet structure motor is 150.4V, and the load output voltage fundamental effective value of the permanent magnet structure motor with the permanent magnet shape changed by the present invention is 155.5V. The output voltage of the generator is significantly improved under the same load, and the voltage regulation rate is reduced from the original 19.87% to the current 15.71%, with obvious effect. Figure 5As shown, when the permanent magnet structure motor with the permanent magnet shape changed by the present invention is loaded, both the inductance of the AC and DC axes increase, that is, both the armature reaction reactance of the AC and DC axes increase, and the increase of the armature reaction reactance of the AC axis is more obvious, which has a greater impact on the voltage regulation rate. Therefore, the present invention can effectively reduce the voltage regulation rate of the motor.

[0033] The above description is only a preferred embodiment of the present invention and does not constitute any other form of limitation to the present invention. Any modification or equivalent change made based on the technical essence of the present invention still falls within the scope of protection required by the present invention.

Claims

1. A tangentially magnetized block permanent magnet low voltage regulation rate generator rotor structure, comprising an integrated permanent magnet and a rotor core punching sheet, wherein the integrated permanent magnet is embedded between the rotor punching sheets on both sides, characterized in that: The integrated permanent magnet includes three permanent magnets, namely permanent magnet one, permanent magnet two and permanent magnet three. The permanent magnet one and permanent magnet three are isosceles trapezoidal permanent magnets with different bottom angles. The permanent magnet two is a rectangular permanent magnet. The permanent magnet two is between the permanent magnet one and the permanent magnet three. The upper base of the permanent magnet is located on the air gap side, tangential magnetization is adopted, and the rotor core punching sheet is closely attached to the waist of the permanent magnet; The second permanent magnet is tangentially magnetized, the thickness increases in the magnetization direction, and the rotor core punching sheet is in close contact with the second permanent magnet; The upper bottom of the permanent magnet three is located on the rotating shaft side, and tangential magnetization is adopted, and the rotor core punching sheet is closely attached to the waist of the permanent magnet three.

2. According to claim 1, a tangentially magnetized block permanent magnet low voltage regulation rate generator rotor structure is characterized in that: The rotor core punching sheet is in close contact with the integrated permanent magnet, and a rectangular slot is opened in the middle. The core punching sheet near the air gap is widened, and the core punching sheet near the rotating shaft is thinned.

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