RU2417506C2 - Low-speed electric machine with circular stator - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: in electric machine the stator in the form of a circular structure of "П"-shaped form with anchor winding and toroidal excitation winding is taken out to the value of the average radius of the anchor magnetic conductor, determined by calculation, and the disc rotor with double-sided arrangement of ferromagnetic poles is structurally combined with the shaft by radially aligned rods-spikes, which provides for considerable increase of circumferential speed of poles, and accordingly, of electromotive force of the anchor winding, and accordingly, reduction of the anchor winding resistance, which provides for achievement of technical result, consisting in increase of efficiency factor of this electric machine at low values of angular frequency of rotor rotation. The possibility is also provided to use a modular principle of the electric machine, which simplifies technology of manufacturing low-speed electric machines of high capacity (over 100 kW), and also increases specific values of capacity and torque.

EFFECT: improved specific indices of electric machine, which is especially evident in zone of low reducer-free speeds of rotation with considerable reduction of electric machine manufacturing labour intensity as a whole.

5 dwg

Description

The invention relates to the field of electrical engineering and can be used in powerful drives of rolling mills, mine hoists and, in particular, as a generator of a wind power installation.

Known arc asynchronous machine, which is obtained by converting a circular stator of a conventional machine (previously conditionally open it) into an arc stator of increasing radius until a certain central angle of the arc is obtained (see Fridkin P.A. Gearless arc-guided electric drive. M.: Energy, 1970, p. 10, 111).

The main disadvantage of the known design is that in the presence of an open stator magnetic circuit, the magnetic system is asymmetric and the magnetic field is distributed unevenly in the gap along the inductor, which causes a number of edge effects that have a harmful effect on the performance of the electric machine.

Closest to the claimed invention is a structural diagram of a non-contact direct current motor with a disk rotor containing a stator with radial grooves for laying, armature windings, a toroidal field winding and a disk rotor in which the stator is made of a number of separate magnetically unconnected U-shaped ferromagnetic rods located symmetrically relative to the ferromagnetic poles of the disk rotor, the base of which is made of non-magnetic material and is rigidly connected to the shaft, and the end h The parts of the radially oriented U-shaped rods are fixed in the non-magnetic end shields of the stator (see the description of the patent of Ukraine No. 78249, H02K 29/06, IPC (2006), 2007, Bull. No. 3).

The design of this electric machine is selected as a prototype.

The prototype and the claimed invention have the following common features:

- a stator with radial grooves made of individual magnetic circuits of a U-shaped;

- disk rotor;

- toroidal field winding.

Providing significant advantages compared to DC motors of classical design (improved dynamic characteristics, increased specific values of power and engine torque) in the zone of high values of their rotation speeds (750 ÷ 1500 rpm), the prototype has the disadvantages of low-speed machines (25 ÷ 425 rpm / min), which are associated with a sharp decrease in the efficiency (Efficiency) due to the need to increase the total length of the conductors of the armature of the armature, respectively, increase the active resistance and losses in tmotka anchors.

In addition, the shift when laying the sections of the armature winding of the two opposite modules by pole division provides full compensation of the magnetomotive forces (MDS) of the currents of the frontal parts and, accordingly, the magnetic flux of the MDS of the frontal parts Ф _l in the path of the main magnetic flux Ф _о mainly at small and medium power values prototype (up to 100 kW). At high power values, i.e. at high currents of the sections of the armature winding, in the zone of the extreme teeth of each pole division of the armature magnetic cores, the influence of the flux Ф _l is manifested, similar to the influence of the transverse reaction of the armature of a conventional DC machine, due to incomplete compensation of the currents of the frontal sections of the winding sections of the opposite armature modules in the extreme sections of each pole division . A similar effect of the magnetic flux of currents of the frontal parts on the main magnetic flux of the prototype limits its overload capacity, respectively, reduces its speed and degrades the dynamic characteristics of the engine.

The basis of the invention is the task of creating a low-speed electric machine in which a stator in the form of a U-shaped ring structure with an armature winding and a toroidal excitation winding is set out by a calculation of the average radius of the armature magnetic circuit, and a disk rotor with a bilateral arrangement of ferromagnetic poles is structurally combined with the shaft radially oriented spokes. This provides a significant increase in the peripheral speed of the poles, and therefore, the electromotive force (EMF) of the armature winding and, accordingly, a decrease in the resistance of the armature winding, i.e. increase efficiency (efficiency) for small values of the angular frequency of rotation of the rotor.

The possibility of the modular principle of building an electrical machine, i.e. sequential alternation along the axis of the common shaft of the U-shaped stator modules (tooth zones, armature winding sections, toroidal field winding and disk rotor in each), which simplifies the manufacturing technology of low-speed high-power electric machines (over 100 kW), increases specific power values and moment.

The problem is solved in the design of a low-speed electric DC machine containing a stator with radial grooves for laying the armature winding, a toroidal field winding and a disk rotor, in that the stator in the form of a ring structure is made of a series of magnetically unconnected U-shaped ferromagnetic magnetic cores-teeth , the transverse rods of each of which are installed with a shift in the pole division relative to opposite teeth, in the intervals-grooves between which sections of the armature winding are laid, and the dis The rotor consists of a ferromagnetic ring, on each side of which there is a row of ferromagnetic poles with a gap in the pole division and with a shift of one row relative to the other by the magnitude of the pole division, moreover, the ferromagnetic ring is structurally combined with the shaft by radially oriented spokes, the length of each which is determined by the calculated value of the average radius of the annular stator, while both the bearing shields of the electric machine and non-magnetic retaining shields of the ring stat pa combined end shields sector type.

The causal relationship between the totality of the claimed features and the achievement of a technical result can be explained as follows.

In the inventive low-speed electric machine with a ring stator (EMC), the geometric dimensions of the main structural elements are determined based on the maximum value of the efficiency and high speed, i.e. providing significant current overloads in dynamic modes. The increase in comparison with the prototype of the average radius of the annular magnetic circuit of the armature provides a small increase in the angular velocity of the disk rotor, a significant increase in the peripheral (linear) speed of the poles relative to the armature of the armature, thereby reducing the length of the conductors and the active resistance of the armature winding (OA), respectively, reducing energy losses in the EMC increasing efficiency. Preliminary calculation of a generator for a wind power plant based on a prototype with parameters: P _H = 100 kW; ν _H = 400 V; n _H = 80 rpm showed an efficiency of η = 0.65 with an average radius of the armature magnetic core R _sr = 0.8 m. For the inventive electric machine with the same initial parameters with an average radius of R '= 1.5 m, the efficiency is η' = 0 , 91, which meets the requirements of the developers of wind energy installations (wind turbines), because at the same time, the moment and geometric dimensions of the wind turbine of a wind turbine are sharply reduced. The implementation of the wind generator only with electromagnetic excitation, as in the inventive design of the EMC, allows you to significantly expand the range of operating speeds of wind turbines due to the zone of their low values, significantly limited in the option of using wind turbines with magnetoelectric excitation generators (permanent magnets), the so-called "moving speed", due to by the forces of magnetic attraction of permanent magnets (V _p = 3 ÷ 5 m / s), at a nominal rotation speed of existing wind generators n = (300 ÷ 500) rpm The proposed design of the EMC provides the minimum values of the rotation speed in the range (25 ÷ 100) rpm.

Ensuring high current overload capacity and, accordingly, speed in the proposed EMC is provided by the following methods. To limit the transverse reaction of the armature, the annular stator is made of separate magnetically unconnected ferromagnetic magnetic cores, U-shaped teeth, i.e. on the path of the magnetic flux F _a created by the currents of the active conductors of the armature winding, there are a number of air gaps, grooves, sharply limiting the reaction of the EMC armature. The magnetic flux F _l currents winding heads armature completely neutralized using shear transverse rods U-shaped magnetic cores, the teeth on the value of the pole pitch τ relative to the opposed teeth of each of the two magnetic circuits armature EMKS for symmetrical installation sections armature winding on each of two opposing pole pitch. The corresponding shift in the direction of the main magnetic flux Ф _{о is} provided by a two-sided shift of the ferromagnetic poles of the disk rotor by a value of τ relative to its total annular ferromagnetic yoke. With such a structure for constructing the design scheme of the proposed EMC in any cross section of the U-shaped armature magnetic circuit, the total magnetomotive force (MDS) of the currents of the frontal parts of the armature winding is zero. Accordingly, the magnetic flux of currents of the frontal parts is also equal to zero (F _l = 0, F _l = 0), i.e. there is no limiting effect on the magnitude of the main magnetic flux Ф _о , which ensures the possibility of a significant multiplicity of current overload in the inventive EMC. So, a preliminary comparative analysis of the characteristic data of the EMC and DC motor of the classical design of the MP4000-32U4 type (for a reversible rolling mill) with the parameters: P _H = 4000 kW; ν _H = 930 V, n _H = 32 rpm, efficiency η = 0.9 showed the following values (for the same parameters):

- moment of inertia of the DPT: j = 60 · 10 ³ kgm ² ;

- moment of inertia of the EMC (in the DPT mode): j = 18.2 · 10 ³ kgm ² ;

- the mass of the DPT: m = 150,000 kg (150 t)

- mass EMC: m '= 50,000 kg (50 t);

- the main technical indicator characterizing the maximum possible productivity of a reversing rolling mill:

- the same indicator for EMC:

those. the use of the inventive EMC provides an increase in productivity of the rolling mill by 3.5 times, which is due to a decrease in the mass of the rotating parts of the engine and, accordingly, a decrease in the electromechanical time constant Tm = 0.17 s for the existing DPT to T'm = 0.056 s in the version with EMC.

In the proposed low-speed electric machine with a ring stator, the modular principle of constructing modern electric machines is quite simply implemented, in which the modules of U-shaped ring stators are located in the axial direction, the disk rotors of which are connected by a common shaft, and the structure of the fixing rods can be one to several modules disk rotors. Such a design scheme of EMC provides an increase in the specific indicators of an electric machine, which is especially manifested in the zone of low gearless speeds, with a significant decrease in the complexity of its manufacture as a whole.

An electric machine with a ring stator is shown in the drawings, where:

FIG. 1 is a structural diagram of the proposed electric machine;

FIG. 2 - electric machine section AA;

FIG. 1 - electric machine, section BB (part of the section is presented);

FIG. 1 - electric machine, section BB (part of the section is presented);

FIG. 3 - electric machine, section GG (part of the scan section is presented);

FIG. 4 - electric machine, cross section DD (presented part of the scan section);

FIG. 5 - disk rotor module, axonometry scan.

A low-speed electric machine with a ring stator contains a stator 1, consisting of modules of the armature 2, 3 and a disk rotor 4. On the inner surface of the stator 1 there is a toroidal coil of the field winding 5. (Fig. 1 ÷ 5).

The end shields of the sector view 6, 7 of the stator 1 are non-magnetic disks 8, 9 mounted motionless relative to the shaft 10 by means of bearings 11, 12. A disk rotor module 14 is rigidly articulated with the shaft 10 with radially oriented spokes 13 (Fig. 5), consisting from a ferromagnetic ring 15, on each side of which a row of ferromagnetic poles 16, 17 is installed. In this case, the pole, for example, 16 of one row is mounted relative to the pole 17 of the other row with a shift in the pole division τ. The width of each pole b _p = α _b -τ, where α _b is the coefficient of pole overlap, and the number of poles in each row 16, 17 is equal to the number of pairs of pole divisions τ: n _p = n _{τ / 2} = p, where n _ε is the number pole divisions of the modules of the anchor 2, 3; p is the number of pole pairs. The anchor modules 2, 3 contain ferromagnetic magnetic cores-teeth 18, 19, forming U-shaped structures by means of closing transverse rods 20 (Fig. 3, 4). While the transverse rods 20 opposite teeth 18, 19 are shifted along the generatrix of each of the modules of the armature 2, 3 by the magnitude of the pole division τ. So, for example, the magnetic flux Φ ₀ emerging from the teeth of module 19 (teeth number 1, 2, 3) passes through pole 17, ring 15, pole 16, teeth of module 18 (teeth number 4, 5, 6) and transverse rods 20 ( Fig. 3, 4), providing a shift in the loop circuit of the main magnetic flux Φ _{0 of} two opposite modules of the armature 2, 3 by the magnitude of the pole division τ. In this case, the armature winding sections 21 of the armature module 2 and the armature winding sections 22 of the armature module 3 are stacked without shear in the opposite gaps (groove numbers 1 ÷ 6) formed by the corresponding installation of magnetic cogs 18, 19, which ensures full compensation of the magnetomotive forces currents of the frontal parts of the armature winding and, accordingly, the complete absence of a pulsating magnetic flux of currents of the frontal parts of the armature winding Ф _л , the presence of which limited the overload capacity of the prototype.

In the proposed EMC, there are two possible ways of laying sections of the winding of the armature 21, 22: the use of a two-layer winding for each of the modules of the armature 2, 3; use of a single layer winding. In this case, it is necessary to provide opposite directions of the currents of the sections of the armature winding lying on the same pole division of the armature modules 2, 3.

The power supply of the closed armature winding, for example, in the operation mode of the DC motor can be fully provided according to the prototype semiconductor switch circuit or using the known electromechanical collector switch.

The proposed EMC in the mode of, for example, a DC motor operates as follows.

When voltage is applied to the toroidal coil of the field winding 5 (Fig. 1, 2), the interaction of the main magnetic flux Φ ₀ and the currents of the conductors of sections 21, 22 of the armature modules 2, 3 located at a melon moment in the zone of the poles 16, 17 of the disk rotor 4 is created electromagnetic moment Mam, under the action of which the disk rotor 4 begins to rotate. The semiconductor or electromechanical switch provides switching currents of the corresponding sections so that when rotating in one direction, the currents of the conductors located at this time against the poles 16, 17, maintain a constant direction. Speed control and engine reverse are carried out by methods known for classical machines.

Claims (1)

A low-speed electric machine with a ring stator, containing a stator with radial grooves for laying the armature winding, a toroidal field winding and a disk rotor, characterized in that the stator in the form of a ring structure is made of a series of magnetically unconnected U-shaped magnetic magnetic cores, transverse rods each of which is installed with a shift in the pole division relative to opposite teeth, in the intervals-grooves between which sections of the armature winding are laid, and the disk rotor consists of a magnetic ring, on each side of which there is a series of ferromagnetic poles with a gap in the pole division and with a shift of one row relative to the other also by the magnitude of the pole division, the ferromagnetic ring being structurally combined with the shaft by radially oriented spokes, the length of each of which is determined by the calculated value the average radius of the ring stator, while both the bearing shields of the electric machine and the non-magnetic mounting shields of the ring stator are combined sector-type shields.

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