RU2311715C1 - Synchronous electrical machine - Google Patents

Abstract

FIELD: electrical engineering; electrical machines such as low-speed high-torque wheel motors for driving vehicles, elevators, for use as motor-car starting generators and low-speed generators for wind-electric and dam-free hydroelectric power plants, and the like.

SUBSTANCE: proposed synchronous electrical machine has stator carrying multiphase coil winding, each coil being disposed on separate tooth and all coils being cumulatively interconnected within coil groups; rotor inductor with alternate-polarity poles; coil number in each group λ = 3, 5, 7 ... which is negative integer odd number greater than or equal to 3. Novelty is that coils are assembled into groups so that stator tooth number Z, coil number λ in stator coil group, coil group number d per phase, and rotor pole pair number p are interrelated by definite equations.

EFFECT: enhanced efficiency, improved vibroacoustic characteristics, reduced manufacturing cost due to use of practically feasible stator winding.

8 cl, 2 dwg, 1 tbl

Description

The invention relates to electrical engineering, in particular to electric machines, and can be used as low-speed high-torque motor-wheel motors for driving vehicles, elevator drive motors, automobile starter-generators and low-speed generators for wind turbines and damless hydroelectric stations, etc.

Known three-phase generator (AS USSR No. 430471 according to IPC Н02К 19/16, bull. No. 20, 1974, authors Abramov A.I., Ivanov-Smolensky A.V. and Petrov G.N.), stator which is made with the number of teeth less than the tripled number of pole pairs, and on each second tooth, a high-voltage concentric winding is alternately located. The disadvantage of this technical solution is the location of the winding is not on everyone, but only on every second tooth. As a result, the dependence of the electromotive force (EMF) on time has a wide range of higher harmonic components, which degrades the vibroacoustic performance of the generator and does not allow it to work in parallel with the network. In addition, the stator pole iron and the stator winding copper are not used optimally in this design.

The prototype of this technical solution is a synchronous motor (A.S. USSR No. 1345291 according to IPC Н02К 19/02, bull. No. 38, 1987, author Shevchenko AF), containing a stator with a three-phase winding (in the present invention is multiphase coil winding) and an active rotor with alternating polarity of poles (in the claimed invention, one rotor inductor whose poles are formed by permanent magnets with alternating polarity) ..., the stator winding coils belonging to one phase are located at the poles (in the claimed invention are separate x teeth), shifted by 360 e. city., included counter.

The disadvantage of the prototype is that a shift of 360 e. hail. between the coils of one phase makes the harmonic composition of the dependence of the EMF on the time of this engine very extensive, which degrades the vibration-acoustic performance, creates additional power losses and degrades the efficiency.

The aim of the present invention is to provide a synchronous electric machine with increased efficiency, acceptable vibroacoustic performance and a technologically advanced coil winding of the stator (armature), in which each coil is located on a separate tooth.

This goal is achieved in accordance with the present invention by observing the following relationships between the number of coil groups in phase d, the number of stator teeth Z and the number of pole pairs of the rotor p:

where k = 1, 1.5, 2, 2.5, 3, 3.5 ... is a positive integer or a number that differs from it by 0.5, and

in this case, Z / p ≠ 2 and the number of coils in the stator coil group λ = 3, 5, 7 ... - a positive integer odd number greater than 3.

If k in the relation (1) is an integer, the windings of the coil groups in each phase are connected according to, and for k different from the integer by 0.5, the windings of the coil groups in each phase are connected in the opposite direction. Subject to this ratio, the EMF induced in each of the coil groups are geometrically added; when deviating from it, they are subtracted, which leads to a loss in the useful power of the machine.

Relation (1) allows us to obtain

- in the generator mode of operation of the electric machine - the same phase voltage and current in all coil groups of the same phase,

- in motor mode - the same position of the cores of each group of the same phase relative to the poles of the inductor.

Expression (2) defines the boundaries of the ratio of the number of stator teeth and the number of pairs of rotor poles, provided that it is not 2. If Z = 2 · p, the position of the rotor relative to the stator, when the axis of each stator tooth coincides with the axis of each rotor pole, is very sustainable. To bring the electric machine out of this position, it is necessary to expend a significant amount of energy.

At the same time, the most optimal options are to perform an electric machine with a specified ratio close to two, in particular, based on relation (3):

rounded to the nearest whole number.

The technical result is a significant reduction in the amplitudes of the higher harmonic components of the EMF dependence on time, which leads to a decrease in the share of “additional” power losses from higher harmonic and an increase in the efficiency of the electric machine by at least 2–4%.

Figure 1 shows a sketch of an example of the active part of a synchronous electric machine in accordance with the present invention - an option with the number of teeth 1 of the stator core Z = 18, on which is placed a three-phase winding 2, where A, B, C are phase names, 0 is neutral point, the phase consists of two coil groups 3 and 4 connected in parallel using conductors 5. The number of pairs of rotor poles is p = 8, the rotor poles are formed using sixteen permanent magnets 6 of alternating polarity attached to the yoke 7 of the rotor. The rotor yoke 7 must be made by machining from casting or forging structural steel with high magnetic permeability, for example, steel 10. For magnetization reversal frequencies less than 10 ÷ 15 Hz, the stator core, consisting of teeth 1 and yoke 8, can be made similarly yoke 7 rotor. At high values of the mentioned frequency, the stator core should be burdened from sheets of electrical steel, the direction of the burden should be parallel to the axis of rotation of the machine. In order to reduce the cost of the stator core, it can be made of soft magnetic powder material, for example, by pressing.

The stator winding coils 2 are wound from a winding wire, for example, copper enamel wire, onto electrically insulating frames or on tooth insulation on each tooth 1 of the stator core. To reduce electrical ("ohmic") losses, the coil group or phase as a whole can be wound with a continuous wire. To simplify and automate the technology of winding winding 2, the stator core can be made detachable, that is, teeth 1 and yoke 8 are manufactured separately, winding 2 is wound on teeth 1, and then teeth 1 are fastened with yoke 8. After winding work is completed, to increase the electrical insulation strength and increasing its reliability, the winding is impregnated with varnish or compound.

To obtain the EMF of maximum amplitude, the number of coils in the group is λ = 3. To combat the higher harmonic components of the EMF dependence on time, it is possible to carry out groups with the number of coils λ = 5 or 7. The adjacent coils in the coil group must be connected in the opposite direction, since they are mainly under the poles of the rotor of opposite polarity.

Figure 2 shows a sketch of the execution of the active part of the synchronous electric machine in accordance with the present invention, when the stator coil groups are connected together in series using conductors 5.

The device operates as follows. The magnetic flux of each permanent magnet 6 passes through the air gap, the closest tooth 1 of the stator, the yoke 8 of the stator, the next tooth 1 of the stator, the air gap, the next permanent magnet 6 and closes along the yoke 7 of the rotor. In motor mode, alternating voltage is applied to the terminals of each phase of the stator winding 2 of the synchronous machine, current flows through the winding, causing the stator to rotate MDS. When an electric current flows in the stator winding 2, the magnetic flux of the winding 2 interacts with the main magnetic flux of magnets 6. Moving, the stator MDS wave rotates the rotor, the magnetic flux of poles 6 moves from one tooth to the next, while inducing an electromotive force (EMF) in the active part of the conductors of the winding 2, located in the grooves between the teeth. The magnitude of the EMF is due to the magnitude of the magnetic flux of the poles and the rotational speed of the rotor. When the rotor rotates, the synchronous machine will give mechanical power to the load. In the generator mode, the rotor of the synchronous machine is driven into rotation by an external source of mechanical energy, for example, a wind turbine, while torque is applied to the rotor, for example, using a pulley with a belt drive. The field of permanent magnets, moving together with the rotor, crosses the conductors of the stator winding, in which the emf is induced. If the load circuit is closed, current flows through the winding. The resulting electrical energy is transferred to the load.

It should be noted that when the stator winding 1 is powered by a DC inverter, for the efficient operation of the machine in the motor mode, feedback on the position of the rotor is introduced. For example, in a three-phase winding with a sensor, at each moment of time, those two phases must be included, the axis of the central tooth of the coil groups of which is closer to the axis of the closest intermagnetic gap in the direction of rotation, the polarity of the inclusion of the coil group is such that the teeth are attracted to the next magnet , it is precisely on the teeth of these two phases that the greatest electromagnetic force acts. When using the Hall sensor as a sensitive element of the rotor position sensor, it can be placed between the stator and the rotor on the side of the stator facing the permanent magnets of the rotor, directly in the main working air gap between the tooth crowns. It is not necessary to create an additional magnetic system for the rotor position sensor. This makes it possible:

- to simplify the design due to the rejection of an additional magnetic system;

- reduce the requirements for the sensitivity of the used Hall sensors, since the magnetic field of the power permanent magnets is used;

- more accurately ensure the moments of phase switching, since it is in the working gap that the true front of the fields of permanent magnets passes;

- provide higher stability of the sensors;

- simplify control operations during production and diagnostics.

This arrangement of sensors became possible due to the fact that the magnetic field of the armature reaction is concentrated in the teeth, each of which is covered by a separate coil. As a result, the reaction field of the anchor is smaller than with the traditional design of the tooth zone, and is concentrated in the slotted areas of the grooves. It is perpendicular to the axis of the groove and is directed from one tooth to the next in the direction of the minimum sensitivity of the Hall sensor. Thus, the sensor practically does not respond to the reaction field of the armature, which provides guaranteed conditions for reliable operation and smooth rotation.

It should be noted that the poles of the rotor inductor can be made with an excitation winding, as in a traditional synchronous machine.

Examples of carrying out the invention. According to the calculations, the following examples of the optimal implementation of an electric machine with a three-phase stator winding can be given (table).

Table No. one 2 3 four Z eighteen 27 thirty 36 λ 3 3 5 3 d 2 3 2 four p 8 12 13 16

Industrial applicability. When carrying out the invention in accordance with No. 2 (table), a value of a long-term developed stop torque of 40 N · m was obtained, with an engine weight of 9 kg and a maximum efficiency of 92%. The maximum rotor speed was 70 rpm.

Claims (8)

1. A synchronous electric machine containing a stator with a multiphase coil winding, each coil of which is located on a separate tooth, the coils in the coil group are interconnected, and the rotor inductor, the poles of which are made with alternating polarity, characterized in that the number of coils in each coil the stator group λ = 3, 5, 7 ... is an odd positive integer greater than or equal to 3, the number d of coil groups in phase, the number Z of stator teeth and the number p of rotor pole pairs are related by the relations: 1 <Z / p <4, for Z / p ≠ 2 and P / d = k, where k = 1; 1.5; 2; 2.5; 3; 3,5 ... is a positive integer or a number that differs from it by 0.5, while the windings of the coil groups in each phase are connected according to if k is an integer, and for k other than an integer by 0.5 , the windings of the coil groups in each phase are connected counterclockwise. 2. The synchronous electric machine according to claim 1, characterized in that at the poles of the rotor inductor there is an excitation winding. 3. The synchronous electric machine according to claim 2, characterized in that the number of pairs of rotor poles is set when rounding to the nearest whole number of the result of the formula: p = 4 · λ · d / 3. 4. The synchronous electric machine according to claim 3, characterized in that it is equipped with rotor angular position sensors, the action of which is based on the Hall effect, located on the stator and facing the rotor with its sensitive element. 5. The synchronous electric machine according to claim 4, characterized in that the coil groups are interconnected in series. 6. The synchronous electric machine according to claim 4, characterized in that the coil groups are interconnected in parallel. 7. A synchronous electric machine according to any one of claims 1 to 6, characterized in that the rotor inductor is located on the inside with respect to the stator. 8. A synchronous electric machine according to any one of claims 1 to 6, characterized in that the rotor inductor is located on the outside with respect to the stator.

Images