CN1674415A - External rotor double-feed AC brushless asynchronous dynamo - Google Patents

Abstract

The invention relates to an outer rotor double-fed AC brushless asynchronous motor, which is composed of a base 1, a rotor casing 2, a wind wheel or blade 12 directly fixed on the rotor casing 2, and two parts A and B respectively. It is composed of stator, rotor core and corresponding windings. When equipped with AC variable frequency power supply, it has the ability of speed regulation operation. It is suitable as a generator directly driven by an extremely low-speed wind turbine, and can also be used as a power source for an axial flow fan with mechanical and electrical integration. The advantage of small power capacity.

Description

An Outer Rotor Double-fed AC Brushless Asynchronous Motor

The invention relates to an AC rotating electrical machine, in particular to an outer rotor double-fed AC brushless asynchronous electrical machine.

Ordinary synchronous generators, in order to provide power frequency electric energy to the grid, the speed of operation is synchronized with the frequency of the grid, and DC power is used to excite the rotor. In order to meet the needs of mechanical devices for speed regulation, with the development of electronic technology, asynchronous generators using AC excitation have appeared. This kind of asynchronous generator generally uses AC frequency converters as excitation power sources. By adjusting the frequency and voltage of the excitation power , can make the generator run at variable speed under the premise of outputting power frequency electric energy, because it can realize the conversion between mechanical energy and electric energy on the two sets of power supplies of the stator and rotor, so this technology is also called double-fed asynchronous power generation machine, which was originally implemented on a wound asynchronous motor, and in recent years there has been a technical solution to realize the function of a doubly-fed motor on a brushless double stator and rotor. However, in these existing technical solutions, the rotor is built in, and the torque is transmitted through the motor shaft. The structure is heavy, the cost is high, and the axial size is large, which is extremely unfavorable for the mechatronics of the wind power generation device and the fan. And when they are used as generators of wind power generation devices, the speed is still not low enough to be directly driven by the wind wheel. At the same time, each generator needs to be equipped with a set of corresponding excitation devices, resulting in the control and control of the wind power generator group. There are many power transmission equipment, and the cost increases.

The purpose of the present invention is to design a mechatronic outer rotor double-fed AC brushless asynchronous motor that can overcome the above-mentioned technical defects, so that the wind wheel of the wind power generation device or the blades of the axial flow fan are directly fixed on the rotor shell of the motor. On top of that, it has the ability to share a power transmission and excitation system with multiple generator sets.

The purpose of the present invention is achieved through the following technical proposals: an outer rotor doubly-fed AC brushless asynchronous motor: it is composed of a machine base, a rotor shell, a wind wheel or a wind blade and a fixed motor that is divided into two parts A and B. , rotor core and windings, the rotor windings of parts A and B are connected in anti-phase sequence, the rotor cores of parts A and B fixed on the rotor shell and the stators of parts A and B fixed on the frame On the outside of the iron core, the wind wheel or blades are directly fixed on the rotor casing.

As for the above-mentioned motor, a cavity is also provided inside the frame, and bearing supports and bearings are arranged in the cavity, and the rotor shaft is connected with the rotor shell as a whole, and rotates around the stator through the bearing in the cavity of the frame.

As mentioned above, two motors can also be used in series, the stator winding of part A of motor C is connected to the excitation power supply, the stator winding of part B is connected to the stator winding of A of motor D, and the stator winding of B is connected to the grid power supply to complete All electrical connections.

The outer rotor double-fed AC brushless asynchronous motor formed according to the above technical scheme has the following beneficial effects:

(1) The wind turbine or the axial flow fan realizes mechatronics, the structure is light and handy, the cost is low, the motor itself has no electrical contact elements, the reliability is high, the power factor is high, the manufacture is simple, and the maintenance workload is small. At the same time, variable speed operation can greatly improve the comprehensive efficiency and power generation capacity of the wind power generating set.

(2) The speed is low, especially after the two units are connected in series, the speed is further reduced. It is suitable as a wind turbine directly driven by the wind wheel, allowing multiple wind turbines to share a set of excitation and power transmission systems, which helps to reduce their overall cost.

(3) It is beneficial to improve the support structure of the existing wind energy generating set and the axial flow fan, and increase the capacity of a single wind energy generating set. When it is used as the power source of the speed-adjustable axial flow fan, the required frequency conversion power supply has small capacity, high reliability and low overall cost.

Fig. 1 is the structural representation of invention.

Figure 2 is a schematic diagram of the wiring when two motors are used in series.

Below in conjunction with accompanying drawing, the present invention will be described in further detail:

As shown in Figure 1, the outer rotor double-fed AC asynchronous motor of the present invention divides the stator and the rotor of the motor into two parts A and B respectively, and the stator cores 6 and 7 of parts A and B are fixed on the base 1 , the excitation winding 8 and the power winding 9 are embedded on it, and their lead wires are drawn out through the cavity of the frame 1, and the rotor cores 4 and 5 of parts A and B are fixed on the rotor shell 2, and the The rotor windings 10 and 11 connected in opposite phase sequence, the rotor cores 4 and 5 fixed on the A and B parts of the rotor casing 2 are arranged outside the A and B part stator cores 6 and 7 fixed on the frame 1 , the wind wheel or blade 12 is directly fixed on the rotor casing 2 . The form of windings 10 and 11 can be specifically determined according to the number of pole pairs of the motor. The motor with a slow speed has more pole pairs. The lead wires can be docked according to the law of reverse phase sequence. The number of pole pairs of fast-speed motors is small, and squirrel-cage windings can be used. , the rotor housing 2 should be made streamlined.

In order to facilitate the fixing between the motor and the foundation and the mechanical cooperation between the stator and the rotor, and to reduce its weight, a cavity is also provided inside the base 1 of the motor, and a bearing support and a bearing support are arranged in the cavity. Bearing, the rotor shaft 3 is connected with the rotor housing 2 as a whole, and rotates around the stator through the bearing in the cavity of the machine base 1, and one end of the machine base 1 is provided with a flange for fixing between the motor and the foundation.

In order to adapt to the ultra-low speed requirements of wind turbines and simplify the control and transmission system of the unit group, this motor can also be used in series, so that two or more motors share a set of excitation and power transmission system. Figure 2 shows a schematic diagram of the electrical wiring of two motors used in series. In the figure, the lead wire of the stator winding C8 of the motor C composed of A1 and B1 is connected to the excitation power supply 13, and its stator winding C9 is connected to the motor C composed of A2 and B2. The stator winding D8 of the motor D and the stator winding D9 of the motor D are connected to the grid power supply 15 . For the generator set connected according to this technical scheme, the speed of the motor is half that of a single motor, and the electric energy of the two motors is completely fed to the grid by the motor D. In order to reduce the burden on the excitation device, this technical solution also has a power capacitor group 14 between the windings C9 and D8, whose function is to provide capacitive excitation current and reduce the capacity of the excitation device. The excitation power supply referred to in the present invention is broadly defined, and it can be a variable frequency power supply with adjustable frequency, voltage and phase, it can also be a DC power supply, and it can even be a short wire.

Explain basic principle of the present invention below: know by the theory of electromechanics: as long as the rotating magnetic field between the stator and the rotor of rotating electric machine keeps relatively static in space just can make motor produce synthetic torque. Ordinary doubly-fed asynchronous motors use this principle to realize asynchronous operation. Its stator and rotor have AC power supplies of different frequencies, and the speed of the rotor is the difference between the speed vectors of the stator and rotor rotating magnetic fields. The rotating magnetic field of the rotor The speed and direction of rotation of the motor depend on the frequency and phase sequence of the excitation power supply, so adjusting the frequency and phase sequence of the excitation power supply can achieve the purpose of changing the motor speed. Different from synchronous motors, the excitation power supply of double-fed motors not only has the function of excitation, but also has the function of energy conversion. When running below the speed, only the stator outputs electric energy, while the rotor inputs electric energy through the excitation power supply. The utility model divides the motor into two parts, A and B. The motor of part B is a double-fed motor, and the exciter current of its rotor is provided by the rotor winding of the motor of part A, while the motor of part A is an armature Rotary doubly-fed motor, which applies excitation power to the stator, and after its rotor generates an induced potential, it forms a closed loop through the two rotor windings to provide excitation current to the rotor of the B-part motor, so the stator winding of the B-part motor is equivalent to a common winding. The stator winding of the wire-type asynchronous motor, the stator winding of the A motor is equivalent to the rotor winding of the wire-wound asynchronous motor. This is the internal reason why this motor can realize the function of doubly-fed motor. Further analysis also shows that as long as the A and B rotor windings are connected in antiphase sequence, they can always generate electromagnetic torque in the same direction. During the operation of the motor, in order to keep the rotating magnetic field between the stator and the rotor relatively static, its speed is half of that of the common one, that is, its maximum speed is 1500 rpm. When two motors are used in series, motor C is equivalent to part A of a single motor, and motor D is equivalent to part B of a single motor. Obviously, as long as the appropriate phase sequence is selected to connect their stator windings, at the same time ensure that The two motors have approximately the same load, so that they can share a set of excitation and power transmission systems, and their speed will be half that of a single machine, and a quarter of that of a common homopolar logarithmic motor. This is very beneficial to low-speed motors, especially wind turbines directly driven by wind rotors.

The motors are all reversible, that is, the motor can be used as a generator or as a motor, so this motor can also be used as an AC speed regulating motor to drive a mechatronic axial flow fan, and the frequency conversion power it needs The capacity is much smaller than that of ordinary squirrel cage motors, and its power factor and reliability are also higher.

Claims (3)

1. An external rotor double-fed AC brushless asynchronous motor: it is composed of a machine base (1), a rotor casing (2), a wind wheel or blade (12) and a stator and a rotor that are each divided into two parts A and B. Composed of iron core and windings, the rotor windings (10) and (11) of parts A and B are connected in anti-phase sequence, and its feature is that the rotor cores (4) of parts A and B are fixed on the rotor casing (2) and (5) are arranged outside the stator cores (6) and (7) of parts A and B fixed on the base (1), and the wind wheel or blade (12) is directly fixed on the rotor shell (2) . 2. The motor according to claim 1, characterized in that the base (1) is provided with a cavity inside, and bearing supports and bearings are arranged in the cavity, and the rotor shaft (3) is connected with the rotor casing (2) as a One body, and rotate around the stator through the bearing in the cavity of the machine base (1). 3. The motor according to claim 1, characterized in that it can also use two motors in series, the stator winding C8 of the motor C is connected to the excitation power supply (13), the winding C9 is connected with the stator winding D8 of the motor D, and the motor The stator winding D9 of D is connected to the grid power supply (15).

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