Power feedback type brushless permanent magnet speed regulator based on magnetic field modulation principle

Abstract

The invention discloses a power feedback type brushless permanent magnet speed regulator based on a magnetic field modulation principle, which comprises an input shaft connected with a prime motor and an output shaft connected with a load, a permanent magnet rotor is arranged on the input shaft, a stator is fixed on a speed regulator shell, and the speed regulator comprises a stator iron core and a three-phase stator winding placed in a slot of the stator iron core. An inner magnetic field modulation unit and an outer magnetic field modulation unit are arranged on the output shaft, a stator surrounds the outer side of the outer magnetic field modulation unit, and the inner magnetic field modulation unit, the permanent magnet rotor, the outer magnetic field modulation unit and the stator are sequentially and concentrically sleeved in the radial direction; a first air gap is arranged between the internal magnetic field modulation unit and the permanent magnet rotor, a second air gap is arranged between the permanent magnet rotor and the external magnetic field modulation unit, and a third air gap is arranged between the external magnetic field modulation unit and the stator. The brushless transmission of the slip power of the input shaft and the output shaft to the stator can be realized, the efficient and stable operation of the speed regulation system is realized, and the energy-saving efficiency of the speed regulation system is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of energy-saving speed regulation and relates to a power feedback type brushless permanent magnet speed regulator based on the magnetic field modulation principle. Background Art

[0002] At present, there are mainly two energy-saving speed regulation solutions in industrial systems: variable frequency drive and variable speed drive. However, there are some inherent defects in the use of high-voltage variable frequency speed regulation technology for large-capacity high-voltage motors. For example, it pollutes the harmonics of the power grid, is not reliable enough, and is not suitable for harsh environments such as oceans and mines. In addition, variable frequency drive technology requires a dedicated variable frequency motor, and the cost of completely replacing the huge number of asynchronous motors is too high. Therefore, many industrial and mining enterprises do not adopt the high-voltage inverter solution. Variable speed drive is to add a simple device between the prime mover and the load to adjust the speed of the constant prime mover to any load speed. Permanent magnet speed regulator is the most commonly used speed regulation device at present. It uses permanent magnetic materials to realize the excitation of the magnetic pole rotor, and realizes the speed regulation on the load side by changing the air gap length or coupling area between the conductor rotor and the magnetic pole rotor. Permanent magnet speed regulator has the advantages of low price, space saving, and wide speed regulation range.

[0003] However, most permanent magnet speed regulators are currently of the slip power consumption type, that is, the slip power between the input and output ends is converted into heat generated in the conductor rotor and dissipated. The efficiency of this type of speed regulator is theoretically equal to 1-s, and as the slip increases, the efficiency of the speed regulator decreases linearly. In addition, the difficulty in heat dissipation on the conductor rotor will also seriously affect the working performance of the speed regulator. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a brushless power feedback permanent magnet speed regulator based on the magnetic field modulation principle, which can realize the brushless transmission of the slip power between the input shaft and the output shaft to the stator side.

[0005] Technical solution: The power feedback brushless permanent magnet speed regulator based on the magnetic field modulation principle described in the present invention includes an input shaft connected to a prime mover and an output shaft connected to a load, a permanent magnet rotor is arranged on the input shaft, a stator is fixed to a speed regulator housing, and includes a stator core and a three-phase stator winding placed in a slot of the stator core, an inner magnetic field modulation unit and an outer magnetic field modulation unit are arranged on the output shaft, a stator is surrounded on the outside of the outer magnetic field modulation unit, and the inner magnetic field modulation unit, the permanent magnet rotor, the outer magnetic field modulation unit and the stator are concentrically arranged in sequence along the radial direction; a first air gap is provided between the inner magnetic field modulation unit and the permanent magnet rotor, a second air gap is provided between the permanent magnet rotor and the outer magnetic field modulation unit, and a third air gap is provided between the outer magnetic field modulation unit and the stator.

[0006] Optionally, the number of pole pairs of the three-phase stator winding is smaller than the number of pole pairs of the permanent magnet rotor.

[0007] Optionally, the internal magnetic field modulation unit has a salient pole tooth structure, and the number of salient pole teeth is equal to the sum of the number of pole pairs of the three-phase stator winding and the number of pole pairs of the permanent magnet rotor.

[0008] Optionally, the external magnetic field modulation unit is composed of magnetic conductive blocks and non-magnetic conductive blocks arranged at intervals, and the number of magnetic conductive blocks is equal to the sum of the number of pole pairs of the three-phase stator winding and the number of pole pairs of the permanent magnet rotor.

[0009] Optionally, the three-phase stator winding is connected to a frequency converter, through which the slip power between the input shaft and the output shaft is fed back to the power grid, and the frequency converter changes the current frequency of the three-phase stator winding, thereby changing the output speed of the speed regulator.

[0010] Optionally, the three-phase stator winding adopts an integer-slot distributed winding.

[0011] Optionally, the permanent magnet rotor includes a permanent magnet rotor core and a permanent magnet array arranged in the middle of the permanent magnet rotor core.

[0012] Optionally, the permanent magnet array forms include but are not limited to spoke type, radial excitation type, Halbach type and alternating pole structure types.

[0013] Optionally, the inner magnetic field modulation unit, the permanent magnet rotor core of the permanent magnet rotor and the magnetic conductive block of the outer magnetic field modulation unit are all formed by laminating silicon steel sheets.

[0014] The motor of the present invention is equipped with the power feedback type brushless permanent magnet speed regulator based on the magnetic field modulation principle.

[0015] Beneficial effects: Compared with the prior art, the significant technical effects of the present invention are as follows: (1) The present invention adopts the inner and outer dual magnetic field modulation units to indirectly couple the permanent magnet rotor magnetic field and the three-phase stator winding magnetic field, realizing the brushless transmission of the slip power of the input shaft and the output shaft to the stator winding, and the inner and outer magnetic field modulation units are both made of laminated silicon steel sheets, which will not generate copper loss, further improving the energy-saving efficiency of the speed regulator. (2) The inner and outer dual magnetic field modulation unit form can increase the effective harmonics of the air gap magnetic density, increase the torque transmission density of the speed regulator, reduce the non-working harmonics of the air gap magnetic density, and thus reduce the stator core loss. (3) By adjusting the frequency and amplitude of the three-phase stator winding current to steplessly adjust the output speed and torque of the speed regulator, the complex mechanical speed regulating device in the traditional permanent magnet speed regulator is avoided, the stability of the permanent magnet speed regulation system is improved, and the maintenance cost is reduced; in general, the capacity of the inverter connected to the speed regulator of the present invention only accounts for 20%-30% of the load power, and compared with the variable frequency drive technical solution, it has the advantages of small size and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A two-dimensional schematic diagram of a cross section of a speed regulator shaft according to an embodiment of the present invention;

[0017] Figure 2 A two-dimensional schematic cross-sectional view of a speed regulator according to an embodiment of the present invention;

[0018] Figure 3 This is a Fourier harmonic analysis diagram of the three-layer air gap magnetic flux density under no-load operation conditions of an embodiment of the present invention;

[0019] Figure 4 This is a torque-speed curve diagram of an embodiment of the present invention;

[0020] Figure 5 A comparison diagram of the input power of the speed regulator of the embodiment of the present invention and the traditional speed regulator;

[0021] Wherein: 1-input shaft, 2-output shaft, 3-permanent magnet rotor, 4-internal magnetic field modulation unit, 5-external magnetic field modulation unit, 6-stator, 7-speed regulator housing, 8-first air gap, 9-second air gap, 10-third air gap, 301-permanent magnet rotor core, 302-permanent magnet array, 501-magnetic conductive block, 502-non-magnetic conductive block, 601-stator core, 602-three-phase stator winding. DETAILED DESCRIPTION

[0022] The present invention is further described below through specific embodiments:

[0023] See also Figure 1 , Figure 2 The power feedback type brushless permanent magnet speed regulator structure based on the magnetic field modulation principle described in the present invention comprises an input shaft 1 connected to the prime mover and an output shaft 2 connected to the load. The input shaft 1 is provided with a permanent magnet rotor 3, and the output shaft 2 is provided with an internal magnetic field modulation unit 4 and an external magnetic field modulation unit 5. The external magnetic field modulation unit 5 is surrounded by a stator 6 fixed to the speed regulator housing 7. The internal magnetic field modulation unit 4, the permanent magnet rotor 3, the external magnetic field modulation unit 5 and the stator 6 are concentrically arranged in sequence, wherein the internal magnetic field modulation unit 4 and the permanent magnet rotor 3 are separated by a first air gap 8, the permanent magnet rotor 3 and the external magnetic field modulation unit 5 are separated by a second air gap 9, and the external magnetic field modulation unit 5 and the stator 6 are separated by a third air gap 10.

[0024] The stator 6 includes a stator core 601 and a three-phase stator winding 602. In this embodiment, the three-phase stator winding 602 is embedded in the slotted stator core 601, and adopts a distributed winding with an integer slot of 36 slots / 2 pairs of poles, which has the advantage of less magnetomotive force harmonics. The conversion of magnetic field and electric energy is realized through the three-phase stator winding, thereby realizing the functions of speed regulation and energy feedback of the speed regulator; the number of pole pairs of the three-phase stator winding 602 is less than the number of pole pairs of the permanent magnet rotor 3, so as to reduce the capacity of the inverter connected to the stator winding. The permanent magnet rotor 3 includes a permanent magnet rotor core 301 and a permanent magnet array 302 arranged in the middle of the permanent magnet rotor core. The permanent magnet rotor core 301 adopts a cup-shaped structure, and the permanent magnet array forms include but are not limited to spoke type, radial excitation type, Halbach type, alternating pole structure and other forms. In this embodiment, the permanent magnet rotor 3 adopts an 8-pair alternating pole structure, which is composed of a permanent magnet rotor core 301 and an alternating pole permanent magnet array 302, which is conducive to improving the utilization rate of the permanent magnet. The internal magnetic field modulation unit 4 has a salient pole tooth structure, and the number of salient pole teeth is equal to the sum of the number of pole pairs of the three-phase stator winding 602 and the number of pole pairs of the permanent magnet rotor 3. In this embodiment, the number of salient pole teeth is 10. The external magnetic field modulation unit 5 is composed of magnetic conductive blocks 501 and non-magnetic conductive blocks 502 arranged alternately, and the number of magnetic conductive blocks 501 is equal to the sum of the number of pole pairs of the three-phase stator winding 602 and the number of pole pairs of the permanent magnet rotor 3. In this embodiment, the number of magnetic conductive blocks 501 is 10. The internal magnetic field modulation unit 4, the permanent magnet rotor core 301 and the magnetic conductive blocks 501 of the external magnetic field modulation unit 5 of the speed regulator are all stacked by silicon steel sheets with a thickness of 0.35 mm, and the stacking coefficient is 0.95. The 8-pole permanent magnet rotor magnetic field is modulated into a 2-pole magnetic field through the inner and outer dual magnetic field modulation units, which then interacts with the armature reaction magnetic field to achieve torque and energy transmission.

[0025] The three-phase stator winding 602 is connected to the frequency converter; the slip power between the input shaft 1 and the output shaft 2 can be fed back to the power grid through the frequency converter to improve the overall efficiency of the speed regulator, and the frequency converter can change the current amplitude and frequency of the three-phase stator winding 602, thereby changing the output speed and torque of the speed regulator; the capacity of the frequency converter is a part of the load mechanical power, which is related to the speed regulation range and pole pair ratio of the speed regulator.

[0026] The motor of the present invention is equipped with the power feedback type brushless permanent magnet speed regulator based on the magnetic field modulation principle.

[0027] See also Figure 3 The operating principle of the power feedback brushless speed regulator based on the magnetic field modulation principle of the present invention can be understood from the perspective of magnetic field modulation, as follows:

[0028] The permanent magnet rotor 3 rotates at a constant speed, generating an 8-pole rotating magnetic field, and generates a 2-pole magnetic field in the third air gap 10 through the magnetic field modulation of the inner magnetic field modulation unit 4 and the outer magnetic field modulation unit 5, and interacts with the 2-pole armature reaction magnetic field generated by the three-phase stator winding 602 to achieve torque and energy transmission. The output speed and torque of the speed regulator can be controlled by controlling the amplitude and frequency of the current of the three-phase stator winding 602. The inner and outer dual magnetic field modulation units help to improve the magnetic field modulation effect, enhance the modulated effective harmonics, and thus improve the torque transmission density of the speed regulation system.

[0029] The torque-speed curves of the present invention under different currents are as follows: Figure 4 As shown in the figure, the torque of the fan and pump loads is proportional to the square of the speed. Assuming that the fan and pump loads work at working point 1, the load working point can be adjusted to working point 2 by adjusting the frequency and amplitude of the stator winding current. This reduces the input power of the prime mover to achieve the purpose of speed regulation and energy saving.

[0030] Figure 5 The input power of the power feedback permanent magnet speed regulator based on the magnetic field modulation principle proposed by the present invention is compared with that of the traditional speed regulator under two working conditions. Since the proposed speed regulator can feed back the slip power of the input shaft and the output shaft to the power grid, the brushless transmission of the slip power to the stator is realized, and the energy-saving efficiency of the speed regulation system is improved. Therefore, the input power proposed by the present invention is significantly lower than that of the traditional speed regulator, and its speed regulation and energy-saving effect is better.

[0031] The above are only preferred implementations of the present invention. These cases are only used to illustrate the present invention and are not used to limit the scope of the present invention. All improvements and modifications made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A power feedback type brushless permanent magnet speed regulator based on the magnetic field modulation principle, comprising an input shaft (1) connected to a prime mover and an output shaft (2) connected to a load, a permanent magnet rotor (3) being arranged on the input shaft, a stator (6) being fixed to a speed regulator housing (7), comprising a stator core (601) and a three-phase stator winding (602) placed in a slot of the stator core (601), characterized in that: An internal magnetic field modulation unit (4) and an external magnetic field modulation unit (5) are arranged on the output shaft; a stator (6) surrounds the outer side of the external magnetic field modulation unit (5); the internal magnetic field modulation unit (4), the permanent magnet rotor (3), the external magnetic field modulation unit (5) and the stator (6) are concentrically sleeved in sequence along the radial direction; a first air gap (8) is provided between the internal magnetic field modulation unit (4) and the permanent magnet rotor (3); a second air gap (9) is provided between the permanent magnet rotor (3) and the external magnetic field modulation unit (5); and a third air gap (10) is provided between the external magnetic field modulation unit (5) and the stator (6).

2. The power feedback brushless permanent magnet speed regulator based on the magnetic field modulation principle according to claim 1 is characterized in that: The number of pole pairs of the three-phase stator winding (602) is smaller than the number of pole pairs of the permanent magnet rotor (3).

3. The power feedback brushless permanent magnet speed regulator based on the magnetic field modulation principle according to claim 1 is characterized in that: The internal magnetic field modulation unit (4) has a salient pole tooth structure, and the number of salient pole teeth is equal to the sum of the number of pole pairs of the three-phase stator winding (602) and the number of pole pairs of the permanent magnet rotor (3).

4. The power feedback brushless permanent magnet speed regulator based on the magnetic field modulation principle according to claim 1 is characterized in that: The external magnetic field modulation unit (5) is composed of magnetic conductive blocks (501) and non-magnetic conductive blocks (502) arranged at intervals, and the number of magnetic conductive blocks (501) is equal to the sum of the number of pole pairs of the three-phase stator winding (602) and the number of pole pairs of the permanent magnet rotor (3).

5. The power feedback brushless permanent magnet speed regulator based on the magnetic field modulation principle according to claim 1 is characterized in that: The three-phase stator winding (602) is connected to a frequency converter, through which the slip power between the input shaft (1) and the output shaft (2) is fed back to the power grid, and the output speed and torque of the speed regulator are controlled by controlling the amplitude and frequency of the current in the stator winding (602).

6. The power feedback brushless permanent magnet speed regulator based on the magnetic field modulation principle according to claim 1 is characterized in that: The three-phase stator winding (602) adopts an integer-slot distributed winding.

7. The power feedback brushless permanent magnet speed regulator based on the magnetic field modulation principle according to claim 1 is characterized in that: The permanent magnet rotor (3) comprises a permanent magnet rotor core (301) and a permanent magnet array (302) arranged in the middle of the permanent magnet rotor core.

8. The power feedback brushless permanent magnet speed regulator based on the magnetic field modulation principle according to claim 1 is characterized in that: The permanent magnet array types include, but are not limited to, spoke type, radial excitation type, Halbach type and alternating pole structure types.

9. The power feedback brushless permanent magnet speed regulator based on the magnetic field modulation principle according to claim 1 is characterized in that: The internal magnetic field modulation unit (4), the permanent magnetic rotor core (301) of the permanent magnetic rotor (3), and the magnetic conductive block (501) of the external magnetic field modulation unit (5) are all formed by laminating silicon steel sheets.

10. A motor, characterized in that: The motor is equipped with a power feedback type brushless permanent magnet speed regulator based on the magnetic field modulation principle as described in any one of claims 1-9.

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