Induction tandem type brushless excitation motor
Technical Field
The invention belongs to the technical field of motors, and particularly relates to a brushless excitation motor.
Background
In order to realize excitation, the rotor excitation type motor needs to provide excitation current by adopting a brush. However, brushes are prone to wear and require frequent replacement. In addition, the electric brush is easy to generate ring fire, and is not suitable for petrochemical engineering, flammable and explosive occasions and aerospace occasions. The permanent magnet motor has high power density and realizes brushless excitation, but the permanent magnet motor cannot realize voltage stabilization along with load or rotating speed change. Meanwhile, the permanent magnet is easy to generate the performance reduction phenomenon under the high-temperature condition, is difficult to demagnetize under the short-circuit condition, and is not suitable for occasions with higher performance requirements, such as petrochemical aerospace and the like.
The existing brushless excitation scheme mainly comprises methods of exciter excitation, axial magnetic field adoption, stator alternating current excitation and the like. By adopting an exciter excitation method, a motor needs to be added in a power generation system, the system structure is complex, and the volume is overlarge. By adopting other methods, if the excitation winding is arranged on the stator, the topological shape of the original rotor excitation type motor needs to be changed, and the following problems are easily caused: 1. the quality of the voltage waveform is poor, and the power density of the motor is obviously reduced; 2. the additional magnetic field introduced for realizing brushless excitation is seriously coupled with the original magnetic field, so that the local saturation of the magnetic core is serious; 3. excitation efficiency is low, and copper loss is increased; 4. an axial magnetic circuit exists, and iron loss and magnetic flux leakage are increased.
Disclosure of Invention
In order to solve the technical problems mentioned in the background art, the invention provides an induction series type brushless excitation motor.
In order to achieve the technical purpose, the technical scheme of the invention is as follows:
an induction tandem type brushless excitation motor comprises a stator excitation winding, a rotor induction winding, a rotor direct-current excitation winding and a three-phase power winding; the stator exciting windings are uniformly arranged in the stator slots, and after direct current exciting current is introduced, the stator exciting windings establish a static exciting magnetic field in the air gap; the rotor induction winding is wound on the rotor teeth and used for inducing a static excitation magnetic field generated by the stator excitation winding, the number of elements of the rotor induction winding is equal to that of the rotor teeth, two elements with the rotor induction potential difference of 180 degrees or the same phase are connected in series in each element of the rotor induction winding, the synonym ends of the two elements with the rotor induction potential difference of 180 degrees are connected in series, and the induction alternating current of the rotor induction winding elements after the series connection supplies direct current to the rotor direct current excitation winding after full-wave rectification; the rotor direct-current excitation windings are wound on the rotor teeth, the winding directions of elements of adjacent rotor direct-current excitation windings are opposite, the elements of the rotor direct-current excitation windings are connected in series, the rotor teeth are magnetized into NS alternate rotor poles through the rotor direct-current excitation windings, and the number of pole pairs of the rotor direct-current excitation windings is in an even-numbered multiple relation with the number of pole pairs formed by the stator excitation windings; the three-phase power windings are uniformly arranged in the stator slots, and the number of pole pairs of the three-phase power windings is equal to that of the rotor direct-current excitation windings.
Furthermore, permanent magnets can be arranged on the rotor iron core, and the number of pole pairs formed by the permanent magnets is equal to that of the rotor direct-current excitation winding; when the motor is started, most of magnetic flux generated by the permanent magnet is in short circuit through the rotor iron core, and residual magnetic flux passes through an air gap and a three-phase power winding linkage; when direct current is introduced into the stator excitation winding, the magnetic field of the current generated by the rotor direct current excitation winding changes the direction of the original short-circuit magnetic flux of the permanent magnet, so that the magnetic flux and the magnetic flux generated by the current of the rotor direct current excitation winding jointly enter an air gap, and electromotive force is induced on the three-phase power winding.
Further, permanent magnets may be placed on the stator core, which generate a magnetic field with the same function as the stator field winding.
Further, the stator and the rotor of the motor are of a non-salient pole structure or a salient pole structure.
Further, the rotor induction winding and the rotor direct-current excitation winding are concentrated windings.
Further, the three-phase power winding is an alternating current winding in any form, and comprises a concentrated winding and a distributed winding, a single-phase winding, a three-phase winding and a multi-phase winding, and a single-layer winding and a double-layer winding.
Further, the motor is of an inner rotor structure or an outer rotor structure.
Adopt above-mentioned technical scheme's beneficial effect:
the invention does not need to add an exciter, so the structure is simple, the volume is small, and the topological shape of the rotor excitation type motor is not required to be changed unlike other brushless excitation methods, thereby the motor performance problem caused by the change of the topological structure is avoided.
Drawings
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a schematic diagram of the establishment of a magnetic field after a stator exciting winding is energized with direct current in the invention;
FIG. 3 is a schematic view of a rotor winding connection according to the present invention;
FIG. 4 is a graph of the corresponding rotor induction winding induced current waveform of FIG. 3;
FIG. 5 is a schematic view of another rotor winding connection of the present invention;
fig. 6 is a schematic view of a hybrid excitation rotor formed by adding permanent magnets.
Description of reference numerals: 1. a stator field winding; 2. a stator slot; 3. the rotor core 4, the rotor direct current excitation winding, 4-1, 4-2, 4-3 and 4-4 are elements of the rotor direct current excitation winding; 5-1, 5-2, 5-3 and 5-4 are elements of the rotor induction winding; 6. a stator core; 7. a three-phase power winding; 8. and a permanent magnet.
Detailed Description
The technical scheme of the invention is explained in detail in the following with the accompanying drawings.
As shown in fig. 1, a motor with 36 stator poles and 4 rotor poles will be described as an example. Two sets of windings are arranged in the stator slot: three-phase power winding 7 and stator field winding 1. The pole pair number of the three-phase power winding 7 is the same as that of the rotor direct-current excitation winding 4 and is an even number multiple of the pole pair number formed by the stator excitation winding 1. Taking the example of 2 times, when the number of pole pairs formed by the stator excitation winding 1 is 1, the number of pole pairs of the three-phase power winding 7 and the number of pole pairs of the rotor direct-current excitation winding 4 are 2. The rotor direct current excitation winding 4 is composed of four elements 4-1, 4-2, 4-3 and 4-4 and is wound on the rotor tooth body, and the winding directions of adjacent elements are opposite. Rotor induction windings are also wound on the rotor teeth. The winding directions of the opposing rotor induction winding elements are the same or opposite. If the winding directions of the opposing rotor induction winding elements are the same, as shown in fig. 1, the electrical angle of the opposing rotor induction winding elements is 0 ° with respect to the stationary field pole formed by the stator field winding 1, then the windings of elements 5-1 and 5-3 are connected in series at their dotted ends, and the windings of 5-2 and 5-4 are connected in series at their dotted ends. If the winding directions of the opposite rotor induction winding elements are opposite, and the electrical angle of the opposite rotor induction winding elements is 180 degrees, the synonym terminals of the windings of the elements 5-1 and 5-3 are connected in series, and the synonym terminals of the windings of the elements 5-2 and 5-4 are connected in series.
As shown in fig. 2, taking the example of a stator 2, the stator field winding 1 generates a stationary field magnetic field in the air gap after passing a dc current. When the rotor core 3 rotates, the elements of the rotor induction winding will induce an alternating induction potential.
If the winding directions of the opposite rotor induction winding elements are the same, the windings of the elements 5-1 and 5-3 are connected in series at the same ends, and the windings of 5-2 and 5-4 are connected in series at the same ends, as shown in fig. 3. The windings of the elements 5-1 and 5-3 are connected in series at the same name end and then are subjected to full-wave rectification by a diode to provide direct current for the direct current excitation winding 4 of the rotor. The windings of the elements 5-2 and 5-4 are connected in series at the same name end and then are subjected to full-wave rectification by a diode to provide direct current for the direct current excitation winding 4 of the rotor. The rectified outputs of the windings of the elements 5-1 and 5-3 are connected in parallel with the rectified outputs of the windings of the elements 5-2 and 5-4.
As shown in fig. 4, when the rotor winding is wound according to fig. 3, the rotor induction winding current is an alternating current. Because the rotor induction winding is connected with the direct-current excitation winding 4 after full-wave rectification, the resistance value of the direct-current excitation winding 4 is very small, so that the rotor induction winding generates stronger armature reaction, and the influence of a magnetic field generated by the current of the rotor induction winding on an air gap can be almost ignored.
If the winding directions of the opposite rotor induction winding elements are opposite, the synonym terminals of the windings of the elements 5-1 and 5-3 are connected in series, and the synonym terminals of the windings of the elements 5-2 and 5-4 are connected in series, as shown in fig. 5. The different name ends of the windings of the elements 5-1 and 5-3 are connected in series and then are subjected to full-wave rectification by a diode to provide direct current for the direct current excitation winding 4 of the rotor. The different name ends of the windings of the elements 5-2 and 5-4 are connected in series and then are subjected to full-wave rectification by a diode to provide direct current for the direct current excitation winding 4 of the rotor. The rectified outputs of the windings of the elements 5-1 and 5-3 are connected in parallel with the rectified outputs of the windings of the elements 5-2 and 5-4.
As shown in fig. 6, on the basis of fig. 1, the rotor pole shoes are stretched, the tangentially magnetized permanent magnets 8 are added in the adjacent rotor pole shoes, and the magnetic field direction after the tangentially magnetized permanent magnets enter the air gap is the same as the magnetic pole after the rotor teeth are magnetized by the direct current excitation winding 4. The hybrid excitation structure formed can increase the power density of the motor. The permanent magnets 8 may also be arranged in a V-shape or radial direction.
The permanent magnet can also be arranged on the stator, and the function of the permanent magnet for generating a magnetic field is the same as that of the stator exciting winding.
The embodiments are only for illustrating the technical idea of the present invention, and the technical idea of the present invention is not limited thereto, and any modifications made on the basis of the technical scheme according to the technical idea of the present invention fall within the scope of the present invention.