Fan front end speed regulation constant rotating speed output system and design method thereof

Abstract

The invention discloses a fan front-end speed regulation constant rotating speed output system and a design method thereof. The fan front-end speed regulation constant rotating speed output system comprises a wind wheel, a front-end speed regulation device connected with the wind wheel, a generator connected with the front-end speed regulation device, a transformer connected with the generator and a power grid connected with the transformer. The front-end speed regulation device comprises a low-speed rotor, a high-speed rotor, a stator winding and a frequency converter; a high-speed rotor of the front-end speed regulation device is connected with a rotating shaft of the generator, and a low-speed rotor of the front-end speed regulation device is connected with a rotating shaft of the wind wheel and fixed with the stator winding; according to the fan front end speed regulation constant rotating speed output method, automatic regulation can be conducted according to the rotating speed change of a wind wheel to ensure that the rotating speed of a generator is kept constant, so that the generator outputs electric energy with constant frequency, and a transmission chain has the advantages of being sensitive in speed regulation, large in speed regulation range, simple in structure, convenient to control, high in efficiency, low in maintenance cost, high in reliability and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power, and in particular to a wind turbine front end speed regulation constant speed output system and a design method thereof. Background Art

[0002] The current front-end speed regulation technologies mainly include hydraulic variable pitch speed regulation, electromagnetic coupling speed regulation, differential gear speed regulation, dual power flow electromechanical hybrid speed regulation and other technologies. The existing electromagnetic coupler has a low speed regulation range, and a single-stage or multi-stage gearbox needs to be installed in front, which increases the structural complexity and maintenance cost. The electromagnetic coupling speed regulation technology is prone to increased electromagnetic loss and reduced efficiency at high wind speeds, and the electronic control module of the electromagnetic coupling speed regulation system is too complex, resulting in high operating costs for the entire speed regulation system. The mechanical mechanism of hydraulic variable pitch speed regulation is complex and expensive. It causes a large amount of energy loss when running at low speed, has low transmission efficiency, and has the risk of leakage. The manufacturing cost of differential gear speed regulation technology is high, especially the precision manufacturing and long-term maintenance costs of planetary gearboxes are high. In addition, under extreme wind conditions, the wear problem of gears is still a challenge that needs to be solved. The system of dual power flow electromechanical hybrid speed regulation technology is complex, involving multiple components working together, with numerous and interrelated control targets, difficult coordinated control, and high requirements for real-time performance and accuracy; in terms of motor performance, it is necessary to optimize efficiency and ensure reliability to cope with complex working environments. At the same time, there is room for improvement in wind energy utilization efficiency, including optimization issues of maximum power tracking accuracy and energy conversion efficiency. The system also faces challenges in riding through grid faults and coping with component failures.

[0003] The existing electromagnetic coupler has a low speed regulation range, and a single-stage or multi-stage gearbox needs to be installed in front, which increases the structural complexity and maintenance cost. There are some problems in the technical performance of electromagnetic coupling speed regulation. Its magnetic field coupling is complex and is affected by many factors. The speed regulation accuracy and range are limited. It is difficult to achieve high-precision speed regulation in actual operation and the speed regulation range may not meet the requirements. There are losses in the energy conversion and transmission process, and the efficiency may be reduced under low-speed conditions. It also contains multiple key components, and its reliability and system stability are affected by the magnetic field coupling characteristics and are sensitive to external interference.

[0004] With its unique working principle, hydraulic torque converter speed regulation uses the changes in kinetic and potential energy of the liquid in energy transfer to achieve speed regulation. However, this also leads to some technical difficulties. Its speed regulation range is relatively narrow, which makes it difficult to meet the needs of complex and changeable working conditions; the speed regulation accuracy is affected by many factors and is not accurate enough; the efficiency is low under low speed and high torque conditions, and the energy utilization is insufficient; the dynamic response speed is slow and cannot adapt to the rapid changes in load in time. In addition, the requirements for the working medium are high, and the properties and temperature changes of the medium will affect its performance. The hydraulic torque converter and its supporting control system have complex structures and high manufacturing process requirements, resulting in high equipment costs. This makes hydraulic torque converter speed regulation may not be competitive in some cost-sensitive application scenarios. Due to the complex internal structure, when the hydraulic torque converter fails during operation, it is difficult to diagnose and repair, requiring professional technicians and equipment. At the same time, the cost of replacing parts is also high, which increases maintenance costs and downtime.

[0005] The manufacturing cost of differential gear speed regulation technology is high, especially the precision manufacturing and long-term maintenance costs of planetary gearboxes are high. The differential gear speed regulation structure is complex in design, with many internal components and close coordination, which increases the difficulty of design and manufacturing. In terms of speed regulation accuracy and range, it is difficult to achieve accurate and extensive speed regulation due to various factors. At the same time, it also faces challenges in reliability and maintainability. Component wear will affect speed regulation accuracy and system performance, and fault diagnosis difficulties increase maintenance costs. In addition, energy loss is large, and factors such as friction during the transmission process lead to low efficiency, and there are many challenges in optimizing efficiency. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a fan front-end speed regulation and constant speed output system and a design method thereof which can automatically adjust according to the change of the speed of the wind wheel to ensure that the speed of the generator remains constant, thereby making the generator output electric energy with a constant frequency.

[0007] The technical solution adopted by the present invention to solve the technical problem is:

[0008] A wind turbine front-end speed regulation constant speed output system comprises a wind wheel, a front-end speed regulation device connected to the wind wheel, a generator connected to the front-end speed regulation device, a transformer connected to the generator, and a power grid connected to the transformer.

[0009] In one embodiment, the front-end speed regulating device includes a low-speed rotor, a high-speed rotor, a stator winding and a frequency converter.

[0010] In one embodiment, the high-speed rotor of the front-end speed regulating device is connected to the rotating shaft of the generator.

[0011] In one embodiment, the low-speed rotor of the front-end speed regulating device is connected to the rotating shaft of the wind wheel.

[0012] In one embodiment, an inner air gap is formed between the high-speed rotor and the low-speed rotor, and an outer air gap is formed between the low-speed rotor and the stator winding.

[0013] In one embodiment, the low-speed rotor is composed of permanent magnets and an iron yoke, and a plurality of magnetic conductive core blocks are evenly distributed on the low-speed rotor.

[0014] In one embodiment, the generator includes a permanent magnet synchronous generator, a doubly fed generator and a high voltage motor.

[0015] The technical solution adopted by the present invention to solve the technical problem is:

[0016] A method for designing a constant speed output of a fan front end speed regulation includes the following steps: Step 1, the number of the magnetic permeable core blocks is equal to the sum of the number of magnetic pole pairs of the high-speed rotor and the number of magnetic pole pairs of the stator winding;

[0017] p hr +p s =p lr (1)

[0018] p hr is the number of magnetic pole pairs of the high-speed rotor in the front-end speed control device, p lr is the number of magnetic core blocks on the low-speed rotor in the front-end speed control device, p s are the number of magnetic pole pairs of the stator winding in the front-end speed control device;

[0019] Step 2: The magnetic field generated by the high-speed rotor of the front-end speed regulating device in the inner air gap is modulated to the outer air gap through the low-speed rotor, and the magnetic field generated by the stator winding in the outer air gap is also modulated to the inner air gap through the action of the low-speed rotor;

[0020] After the magnetic field of the stator winding is modulated, it will generate harmonics with the same speed and pole pair number as the fundamental wave of the high-speed rotor magnetic field, and form a pair of harmonic pairs with the fundamental wave of the high-speed rotor magnetic field; after the magnetic field of the high-speed rotor is modulated, it will generate harmonics with the same speed and pole pair number as the fundamental wave of the stator winding magnetic field, and form a pair of harmonic pairs with the fundamental wave of the stator winding magnetic field;

[0021] Therefore, the transformation ratio of the front-end speed regulating device satisfies the following relationship:

[0022]

[0023] Among them, n hr is the speed of the high-speed rotor in the front-end speed regulating device, n lris the speed of the low-speed rotor in the front-end speed regulating device, R G is the transformation ratio of the front-end speed regulating device;

[0024] The speed of the high-speed rotor in the front-end speed control device n hr for

[0025]

[0026] Among them, n hr The speed of the high-speed rotor in the front-end speed control device, n lr is the speed of the low-speed rotor in the front-end speed regulating device, R G is the transformation ratio of the front-end speed regulating device;

[0027] Step 3: The speed n of the low-speed rotor in the front-end speed regulating device lr To reduce, it is necessary to reduce the ratio R of the front-end speed regulating device in the same proportion G Value; the speed of the low-speed rotor in the front-end speed control device n lr Increase, it is necessary to increase the ratio R of the front-end speed regulating device in the same proportion G value, thereby maintaining the speed n of the high-speed rotor in the output front-end speed regulating device hr of constancy;

[0028] The high-speed rotor of the front-end speed regulating device and the low-speed rotor of the front-end speed regulating device satisfy the following relationship when rotating:

[0029] p hr n hr +p s n s =p lr n lr (4)

[0030] Among them, p hr is the number of magnetic pole pairs of the high-speed rotor in the front-end speed control device, p lr Number of low-speed rotor blocks in the front-end speed regulating device, p s is the number of magnetic pole pairs of the stator winding in the front-end speed control device, n hr is the speed of the high-speed rotor in the front-end speed regulating device, n lr is the speed of the low-speed rotor in the front-end speed regulating device, n s The speed of the rotating magnetic field generated by the stator winding in the outer air gap in the front-end speed control device;

[0031] Step 4: When three-phase AC is supplied to the stator winding of the front-end speed regulating device, the stator winding of the front-end speed regulating device will generate a rotating magnetic field, that is, the speed of the rotating magnetic field generated by the stator winding in the outer air gap is n s for;

[0032] n s =60f / ps (5)

[0033] Where, f is the frequency of the three-phase current, p s is the number of magnetic pole pairs of the stator winding in the front-end speed control device;

[0034] Combining the above equations (1)(2)(3)(4)(5), we can get the transformation ratio R of the front-end speed regulating device: G for

[0035]

[0036] Among them, R G Transformation ratio of the front-end speed regulator, p hr is the number of magnetic pole pairs of the high-speed rotor in the front-end speed control device, p lr Number of low-speed rotor blocks in the front-end speed regulating device, n hr is the speed of the high-speed rotor in the front-end speed regulating device, and f is the frequency of the three-phase current;

[0037] Step 5: The speed n of the low-speed rotor input in the front-end speed control device lr When the change starts, the speed of the low-speed rotor in the front-end speed control device is n lr When it decreases, the transformation ratio R of the front-end speed regulating device needs to be reduced in the same proportion G value, so it is necessary to increase the frequency f of the stator current; when the low-speed rotor speed n of the current end speed control device lr When the speed increases, the ratio R of the front-end speed regulating device needs to be reduced in the same proportion. G value, so it is necessary to reduce the frequency f of the stator current, so as to maintain the speed n of the high-speed rotor in the output front-end speed control device hr of constancy;

[0038] Step 6: The speed n of the low-speed rotor in the front-end speed regulating device lr When the speed decreases, the frequency f of the stator current increases; when the low-speed rotor n lr When the frequency f of the stator current increases, the high-speed rotor speed n in the output front-end speed control device is maintained. hr of constancy;

[0039] Step 7: The transformation ratio of the front-end speed regulating device is controlled by the frequency f of the stator current. When the speed of the wind wheel input changes, the front-end speed regulating device adjusts the transformation ratio R of the front-end speed regulating device by adjusting the frequency f of the stator current. G , thereby realizing the adjustment of the change of wind wheel input speed, achieving constant speed output, and then obtaining stable grid-connected current.

[0040] Furthermore, the speed of the high-speed rotor in the front-end speed regulating device is as follows:

[0041]

[0042] Among them, n hr is the speed of the high-speed rotor in the front-end speed regulating device, p hr is the number of magnetic pole pairs of the high-speed rotor in the front-end speed control device, n lr is the speed of the low-speed rotor in the front-end speed control device, f is the frequency of the stator current, p lr It is the number of magnetic core blocks on the low-speed rotor in the front-end speed control device.

[0043] Furthermore, when the system loss is not considered, the output power of the front-end speed regulating device satisfies

[0044] P o =P i +P e (8)

[0045] P i is the input mechanical power, P e is the input electrical power, P o is the output mechanical power.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The speed regulating transmission chain at the front end of the fan of the present invention can automatically adjust according to the change in the speed of the wind wheel to ensure that the speed of the generator remains constant, so that the generator outputs electrical energy with a constant frequency. The transmission chain has the advantages of sensitive speed regulation, large speed regulation range, simple structure, convenient control, high efficiency, low maintenance cost, high reliability, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 Schematic diagram of the fan front-end speed regulation structure of embodiment 1 of the present invention

[0049] In the figure: 10. wind wheel, 20. front-end speed regulating device, 21. stator winding, 22. low-speed rotor, 23. high-speed rotor, 24. inverter, 30. generator, 40. transformer, 50. power grid. DETAILED DESCRIPTION

[0050] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0051] Example 1

[0052] like Figure 1As shown, this embodiment includes a wind wheel 10, a front-end speed regulating device 20 connected to the wind wheel 10, a generator 30 connected to the front-end speed regulating device 20, a transformer 40 connected to the generator 30, and a power grid 50 connected to the transformer 40; the front-end speed regulating device 20 includes a low-speed rotor 22, a high-speed rotor 23, a stator winding 21 and a frequency converter 24; the high-speed rotor 23 of the front-end speed regulating device 20 is connected to the rotating shaft of the generator 30, and the low-speed rotor 22 of the front-end speed regulating device 20 is connected to the rotating shaft of the wind wheel 10; an inner air gap is formed between the high-speed rotor 23 and the low-speed rotor 22, and an outer air gap is formed between the low-speed rotor 22 and the stator winding 21.

[0053] In this embodiment, the low-speed rotor 22 is composed of permanent magnets and an iron yoke, and a plurality of magnetic conductive core blocks are evenly distributed on the low-speed rotor 22 .

[0054] In this embodiment, the generator 30 includes a permanent magnet synchronous generator, a doubly fed generator and a high voltage motor.

[0055] Example 2

[0056] This embodiment includes the following steps:

[0057] Step 1: The number of the magnetic conductive core blocks is equal to the sum of the number of magnetic pole pairs of the high-speed rotor 23 and the number of magnetic pole pairs of the stator winding 21;

[0058] p hr +p s =p lr (1)

[0059] p hr is the number of magnetic pole pairs of the high-speed rotor 23 in the front-end speed regulating device 20, p lr is the number of magnetic core blocks on the low-speed rotor 22 in the front-end speed regulating device 20, p s are respectively the number of magnetic pole pairs of the stator winding 21 in the front-end speed regulating device 20;

[0060] Step 2: The magnetic field generated by the high-speed rotor 23 of the front-end speed regulating device 20 in the inner air gap is modulated to the outer air gap through the low-speed rotor 22, and the magnetic field generated by the stator winding 21 in the outer air gap is also modulated to the inner air gap through the action of the low-speed rotor 22;

[0061] After being modulated, the magnetic field of the stator winding 21 will generate harmonics with the same speed and pole pair number as the fundamental wave of the magnetic field of the high-speed rotor 23, and form a pair of harmonic pairs with the fundamental wave of the magnetic field of the high-speed rotor 23; after being modulated, the magnetic field of the high-speed rotor 23 will generate harmonics with the same speed and pole pair number as the fundamental wave of the magnetic field of the stator winding 21, and form a pair of harmonic pairs with the fundamental wave of the magnetic field of the stator winding 21;

[0062] Therefore, the transformation ratio of the front-end speed regulating device 20 satisfies the following relationship:

[0063]

[0064] Among them, n hr is the speed of the high-speed rotor 23 in the front-end speed regulating device 20, n lr is the speed of the low-speed rotor 22 in the front-end speed regulating device 20, R G is the transformation ratio of the front-end speed regulating device 20;

[0065] That is, the speed n of the high-speed rotor 23 in the front-end speed regulating device 20 hr for

[0066]

[0067] Among them, n hr The speed of the high-speed rotor 23 in the front-end speed regulating device 20, n lr is the speed of the low-speed rotor 22 in the front-end speed regulating device 20, R G is the transformation ratio of the front-end speed regulating device 20.

[0068] Step 3: The speed n of the low speed rotor 22 in the front speed regulating device 20 is lr To reduce, the transformation ratio R of the front-end speed regulating device 20 needs to be reduced in the same proportion G The speed n of the low-speed rotor 22 in the front speed regulating device 20 lr Increase, it is necessary to increase the ratio R of the front-end speed regulating device 20 in the same proportion G value, thereby maintaining the speed n of the high-speed rotor 23 in the output front-end speed regulating device 20 hr of constancy;

[0069] The high-speed rotor 23 of the front-end speed regulating device 20 and the low-speed rotor 22 of the front-end speed regulating device 20 satisfy the following relationship when rotating:

[0070] p hr n hr +p s n s =p lr n lr (4)

[0071] Among them, p hr is the number of magnetic pole pairs of the high-speed rotor 23 in the front-end speed regulating device 20, p lr The number of low-speed rotors 22 of the front-end speed regulating device 20, p s is the number of magnetic pole pairs of the stator winding 21 in the front-end speed regulating device 20, n hr is the speed of the high-speed rotor 23 in the front-end speed regulating device 20, n lr is the speed of the low-speed rotor 22 in the front-end speed regulating device 20, n sThe speed of the rotating magnetic field generated by the stator winding 21 in the front-end speed regulating device 20 in the outer air gap;

[0072] Step 4: When three-phase AC is supplied to the stator winding 21 of the front-end speed regulating device 20, the stator winding 21 of the front-end speed regulating device 20 will generate a rotating magnetic field, that is, the speed n of the rotating magnetic field generated by the stator winding 21 in the outer air gap is s for;

[0073] n s =60f / p s (5)

[0074] Where, f is the frequency of the three-phase current, p s is the number of magnetic pole pairs of the stator winding (21) in the front-end speed regulating device (20); the transformation ratio R of the front-end speed regulating device 20 can be obtained by combining the above equations (1)(2)(3)(4)(5). G for

[0075]

[0076] Among them, R G The ratio of the front speed regulating device 20, p hr is the number of magnetic pole pairs of the high-speed rotor 23 in the front-end speed regulating device 20, p lr Number of low-speed rotors 22 in the front-end speed regulating device 20, n hr is the speed of the high-speed rotor 23 in the front-end speed regulating device 20, and f is the frequency of the three-phase current;

[0077] Step 5: The speed n input by the low speed rotor 22 in the front speed regulating device 20 lr When the change starts, the speed n of the low-speed rotor 22 in the front-end speed regulating device 20 is lr When the speed is reduced, the transformation ratio R of the front-end speed regulating device 20 needs to be reduced in the same proportion. G value, so it is necessary to increase the frequency f of the stator current; when the low-speed rotor 22 speed n of the front-end speed regulating device 20 lr When the speed increases, the transformation ratio R of the front-end speed regulating device 20 needs to be reduced in the same proportion. G value, so it is necessary to reduce the frequency f of the stator current, so as to maintain the speed n of the high-speed rotor 23 in the output front-end speed regulating device 20 hr of constancy;

[0078] The rotation speed of the high-speed rotor 23 in the front-end speed regulating device 20 can be obtained from the above formula as follows:

[0079]

[0080] Among them, n hr is the speed of the high-speed rotor 23 in the front-end speed regulating device 20, p hris the number of magnetic pole pairs of the high-speed rotor 23 in the front-end speed regulating device 20, n lr is the speed of the low-speed rotor 22 in the front-end speed regulating device 20, f is the frequency of the stator current, p lr is the number of magnetic core blocks on the low-speed rotor 22 in the front-end speed regulating device 20;

[0081] Step 6: The speed n of the low speed rotor 22 in the front speed regulating device 20 lr When the speed decreases, the frequency f of the stator current increases; when the low-speed rotor 22n in the speed front-end speed regulating device 20 lr When the frequency f of the stator current increases, the speed n of the high-speed rotor 23 in the output front-end speed regulating device 20 is maintained. hr of constancy;

[0082] Step 7: The transformation ratio of the front-end speed regulating device 20 is controlled by the frequency f of the stator current. When the speed input by the wind wheel 10 changes, the front-end speed regulating device 20 adjusts the transformation ratio R of the front-end speed regulating device 20 by adjusting the frequency f of the stator current. G , thereby adjusting the input speed change of the wind wheel 10, achieving constant speed output, and then obtaining a stable grid-connected current.

[0083] When the system loss is not considered, the output power of the front-end speed regulating device 20 satisfies

[0084] P o =P i +P e (8)

[0085] P i is the input mechanical power, P e is the input electrical power, P o is the output mechanical power.

[0086] Thus, the wind wheel 10 converts wind energy into mechanical energy and inputs it into the front-end speed regulating device 20 with a power of P i The current input power of the stator current is P e Together they constitute the input power. Before reaching the rated wind speed, as the wind speed increases, the input power of the front-end speed regulating device 20 lr The input mechanical power P i Increase, at this time reduce the frequency of the stator current f of the front-end speed regulating device 20, thereby reducing the transformation ratio R G , to achieve a stable speed n lr output, while reducing the input power P i ; When the wind speed reaches above the rated wind speed and reaches the rated transformation ratio, the input power is reduced to 0; when the wind speed is less than the rated wind speed and continues to decrease, the input speed n of the front-end speed regulating device 20 lr As the torque decreases, the input mechanical power Pi Reduce, at this time increase the frequency of the stator current of the front-end speed regulating device, thereby increasing the transformation ratio R G , to achieve a stable speed n lr Output, while increasing the input power P i .

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the technical solutions of the present invention have been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fan front end speed regulation constant speed output system, characterized in that: The invention comprises a wind wheel (10), a front-end speed regulating device (20) connected to the wind wheel (10), a generator (30) connected to the front-end speed regulating device (20), a transformer (40) connected to the generator (30), and a power grid (50) connected to the transformer (40).

2. The fan front end speed regulation constant speed output system according to claim 1 is characterized in that: The front-end speed regulating device (20) comprises a low-speed rotor (22), a high-speed rotor (23), a stator winding (21) and a frequency converter (24).

3. The fan front end speed regulation constant speed output system according to claim 2 is characterized in that: The high-speed rotor (23) of the front-end speed regulating device (20) is connected to the rotating shaft of the generator (30).

4. The fan front end speed regulation constant speed output system according to claim 3 is characterized in that: The low-speed rotor (22) of the front-end speed regulating device (20) is connected to the rotating shaft of the wind wheel (10).

5. The fan front end speed regulation constant speed output system according to claim 4 is characterized in that: An inner air gap is formed between the high-speed rotor (23) and the low-speed rotor (22), and an outer air gap is formed between the low-speed rotor (22) and the stator winding (21).

6. The fan front end speed regulation constant speed output system according to claim 5 is characterized in that: The low-speed rotor (22) is composed of a permanent magnet and an iron yoke, and a plurality of magnetic conductive core blocks are evenly distributed on the low-speed rotor (22).

7. The fan front end speed regulation constant speed output system according to claim 6 is characterized in that: The generator (30) comprises a permanent magnet synchronous generator, a double-fed generator and a high-voltage motor.

8. A design method for a fan front-end speed regulation constant speed output, characterized in that: The steps include: Step 1: The number of the magnetic permeable core blocks is equal to the sum of the number of magnetic pole pairs of the high-speed rotor (23) and the number of magnetic pole pairs of the stator winding (21); p hr +p s =p lr (1) p hr is the number of magnetic pole pairs of the high-speed rotor (23) in the front-end speed regulating device (20), p lr is the number of magnetic core blocks on the low-speed rotor (22) in the front-end speed regulating device (20), p s are respectively the number of magnetic pole pairs of the stator winding (21) in the front-end speed regulating device (20); Step 2: The magnetic field generated by the high-speed rotor (23) of the front-end speed regulating device (20) in the inner air gap is modulated to the outer air gap through the low-speed rotor (22), and the magnetic field generated by the stator winding (21) in the outer air gap is also modulated to the inner air gap through the action of the low-speed rotor (22); After being modulated, the magnetic field of the stator winding (21) generates harmonics having the same rotation speed and pole pair number as the fundamental wave of the magnetic field of the high-speed rotor (23), and forms a pair of harmonic pairs with the fundamental wave of the magnetic field of the high-speed rotor (23); after being modulated, the magnetic field of the high-speed rotor (23) generates harmonics having the same rotation speed and pole pair number as the fundamental wave of the magnetic field of the stator winding (21), and forms a pair of harmonic pairs with the fundamental wave of the magnetic field of the stator winding (21); Therefore, the transformation ratio of the front-end speed regulating device (20) satisfies the following relationship: Among them, n hr is the speed of the high-speed rotor (23) in the front-end speed regulating device (20), n lr is the speed of the low-speed rotor (22) in the front-end speed regulating device (20), R G is the transformation ratio of the front-end speed regulating device (20); The speed n of the high-speed rotor (23) in the front-end speed regulating device (20) hr for Among them, n hr The speed of the high-speed rotor (23) in the front-end speed regulating device (20), n lr is the speed of the low-speed rotor (22) in the front-end speed regulating device (20), R G is the transformation ratio of the front-end speed regulating device (20); Step 3: The speed n of the low speed rotor (22) in the front speed regulating device (20) lr To reduce, it is necessary to reduce the transformation ratio R of the front-end speed regulating device (20) in the same proportion. G value; the speed n of the low-speed rotor (22) in the front-end speed regulating device (20) lr Increase, it is necessary to increase the transformation ratio R of the front-end speed regulating device (20) in the same proportion G value, thereby maintaining the speed n of the high-speed rotor (23) in the output front-end speed regulating device (20) hr of constancy; The high-speed rotor (23) of the front-end speed regulating device (20) and the low-speed rotor (22) of the front-end speed regulating device (20) satisfy the following relationship when rotating: p hr n hr +p s n s =p lr n lr (4) Among them, p hr is the number of magnetic pole pairs of the high-speed rotor (23) in the front-end speed regulating device (20), p lr The number of low-speed rotors (22) of the front-end speed regulating device (20), p s is the number of magnetic pole pairs of the stator winding (21) in the front-end speed regulating device (20), n hr is the speed of the high-speed rotor (23) in the front-end speed regulating device (20), n lr is the speed of the low-speed rotor (22) in the front-end speed regulating device (20), n s The speed of the rotating magnetic field generated by the stator winding (21) in the front-end speed regulating device (20) in the outer air gap; Step 4: When three-phase alternating current is supplied to the stator winding (21) of the front-end speed regulating device (20), the stator winding (21) of the front-end speed regulating device (20) will generate a rotating magnetic field, that is, the speed n of the rotating magnetic field generated by the stator winding (21) in the outer air gap is s for; n s =60f / p s (5) Where, f is the frequency of the three-phase current, p s is the number of magnetic poles of the stator winding (21) in the front-end speed regulating device (20); Combining the above equations (1)(2)(3)(4)(5), we can get the transformation ratio R of the front-end speed regulating device (20): G for Among them, R G The transformation ratio of the front-end speed regulating device (20), p hr is the number of magnetic pole pairs of the high-speed rotor (23) in the front-end speed regulating device (20), p lr Number of low-speed rotors (22) in the front-end speed regulating device (20), n hr is the speed of the high-speed rotor (23) in the front-end speed regulating device (20), and f is the frequency of the three-phase current. Step 5: The speed n input by the low speed rotor (22) in the front end speed regulating device (20) lr When the change starts, the speed n of the low speed rotor (22) in the front speed regulating device (20) is lr When the speed is reduced, the transformation ratio R of the front-end speed regulating device (20) needs to be reduced in the same proportion. G value, thereby increasing the frequency f of the stator current; when the low-speed rotor (22) speed n of the front-end speed regulating device (20) lr When the speed increases, the transformation ratio R of the front-end speed regulating device (20) needs to be reduced in the same proportion. G value, so it is necessary to reduce the frequency f of the stator current, so as to maintain the speed n of the high-speed rotor (23) in the output front-end speed regulating device (20) hr of constancy; Step 6: The speed n of the low speed rotor (22) in the front speed regulating device (20) lr When the speed decreases, the frequency f of the stator current increases; when the speed of the front-end speed regulating device (20) is low speed rotor (22) n lr When the frequency f of the stator current increases, the speed n of the high-speed rotor (23) in the output front-end speed regulating device (20) is maintained. hr of constancy; Step 7: The transformation ratio of the front-end speed regulating device (20) is controlled by the frequency f of the stator current. When the speed input by the wind wheel (10) changes, the front-end speed regulating device (20) adjusts the transformation ratio R of the front-end speed regulating device (20) by adjusting the frequency f of the stator current. G , thereby achieving the adjustment of the input speed change of the wind wheel (10), achieving constant speed output, and then obtaining a stable grid-connected current.

9. A method for designing a fan front end speed regulation constant speed output according to claim 8, characterized in that: The speed of the high-speed rotor (23) in the front-end speed regulating device (20) is as follows: Among them, n hr is the speed of the high-speed rotor (23) in the front-end speed regulating device (20), p hr is the number of magnetic pole pairs of the high-speed rotor (23) in the front-end speed regulating device (20), n lr is the speed of the low-speed rotor (22) in the front-end speed regulating device (20), f is the frequency of the stator current, p lr It is the number of magnetic core blocks on the low-speed rotor (22) in the front-end speed regulating device (20).

10. A method for designing a fan front end speed regulation constant speed output according to claim 8, characterized in that: When the system loss is not considered, the output power of the front-end speed regulating device (20) satisfies P o =P i +P e (8) P i is the input mechanical power, P e is the input electrical power, P o is the output mechanical power.

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