RU2302692C1 - Electromechanical converter - Google Patents

Abstract

FIELD: electrical engineering; low-speed drives, vehicle motor-wheels, elevator drive motors, generators, including windmill ones, as well as low- and medium-speed water-wheel generator,s synchronous condensers, and the like.

SUBSTANCE: proposed electromechanical converter has at least one stator-and-rotor pair in which stator has high-magnetic-permeability core whose butt-ends are attached to stator supporting ring and positioned in parallel with main magnetic flux. Multiphase winding conductors are disposed between these cores. Rotor is assembled of two coaxially disposed inductors, external and internal ones, made of high-magnetic-permeability material in the form of cylinders, they function as magnetic circuits and are mounted for rotation about stator and carry alternating-polarity poles disposed on circumference facing stator through working clearances and enclosing this stator. Polarity of poles disposed on internal and external inductors opposing one another is additive. Stator core number z and number of coil groups per phase d are correlated by equation p/d = k, where p is pole pair number; k = 1.5, 2, 2.5, 3, 3.5 ... is integer positive number or number differing from the latter by 0.5; d is integer even number. When k is integer number, coil group windings of each phase are connected cumulatively. When k differs from integer number by 0.5, coil group windings are connected differentially in each phase. and 0.5 < z/(2 x p) < 2. In this case z/(2 x p) ≠ 1.

EFFECT: improved power characteristics, enhanced specific power output.

3 cl, 2 dwg

Description

Technical field

The invention relates to electrical engineering and for the implementation of an electromechanical converter (EMF) for mainly low-speed devices, which can be used, for example, as an electric motor in drum winches or in the motor wheels of light vehicles, in particular electric carts and electric vehicles, as well as an electric generator in wind power plants or as a starter-generator in gas or diesel generator stations. It can also be used in electric vehicles with a combined power plant, as a synchronous compensator, as well as in other devices where high specific characteristics or advanced functionality are required.

State of the art

A known electromagnetic converter [patent RU 2076431] containing a stator with a multiphase winding, a rotor, one part of which is made in the form of a magnetic circuit with a short-circuited winding, and the other part is in the form of a magnetic circuit of magnetically hard material, while the stator consists of two parts on which are located multiphase windings with an unequal number of pole pairs. The rotor is made in the form of a glass, on one part of which a layer of conductive material is applied, and on the other - a layer of hard magnetic material, and the stator consists of external and internal parts. A disadvantage of the known Converter is the insufficient received values of torque and specific torque.

A known electromagnetic converter [patent RU 2083051], containing a rotor with a magnetic circuit and a magnetic flux source and a stator with a winding and a magnetic circuit, the stator winding consists of sections formed by conductors, and the stator magnetic circuit is made in the form of individual elements from a material with high magnetic permeability, which are placed between sections of the armature winding, and the elements of the magnetic circuit and sections of the armature winding are fastened together using a binder. The inductor and the armature are made cylindrical and have the ability to rotate relative to each other. The inductor is mounted for rotation relative to the armature, and the armature is made in the form of a hollow thin-walled cylinder. The electromagnetic converter contains a housing, while the magnetic circuit of the inductor is cylindrical and mounted on the shaft coaxially with it, and the conductors of the armature winding sections form coils. The inductor magnetic circuit contains two annular parts mounted on the mounting disk coaxially to each other, each of which is made with an inner and outer annular wall, at least one of which has magnetic flux sources, and an anchor is placed in the gap between the annular parts of the inductor magnetic circuit. Although the known electromagnetic converter is designed to convert high power, however, when operating at low speeds it does not provide the required magnitude of torque and specific torque, and also does not provide the required reliability, since the stator design provides for the mounting of magnetic circuit elements and sections of the armature winding using a binder , it does not have the required rigidity and is not able to withstand pulsed loads for a long time.

The closest in technical essence to the present invention (its prototype) is a drive device for mobile vehicles [patent RU 2074761], containing a stator-rotor pair, in which the stator is made of cores, ends attached to the supporting stator ring and oriented parallel to the magnetic flux, and between which there are active conductors of a multiphase, for example, two or more, concentrated windings, the rotor is made in the form of two coaxially located external and internal inductors - a magnet wires in the form of hollow cylinders with the possibility of rotation relative to the stator, bearing alternating poles located around the circumferences of the pole, facing the stator through the working gaps and covering it, while the polarity of the magnets located on the inner and outer inductors opposite each other, consonant.

In the claims of the prototype invention, it is indicated that the coils are arranged with a step different from the step of placing permanent magnets by the amount α (n-1) ... α / n, where α is the angular width of the gap between the magnets, n is the number of coils in the group.

The studies carried out by the patent holder (who is also the applicant of this application) showed that this ratio is not universal. In essence, it was adequate to a specific modification of the drive device (electric motor) and attempts to follow it when designing electric machines with other structural parameters showed that when designing machines of both a larger diameter and a smaller diameter, the angular width of the gap between the permanent magnets is excessively increased, as a result of which the magnitude of the magnetic flux penetrating from the rotor into the stator decreases, and hence the magnitude of the effective value of the EMF and, as a result, consumer x product characteristics, primarily efficiency.

SUMMARY OF THE INVENTION

The objective of the invention is to provide an electromechanical transducer with increased specific power and torque at low angular speeds.

Another objective of the invention is the creation of a compact EMF and reduced weight.

Another objective of the invention is to increase the efficiency and efficiency of EMF, expanding its scope.

These problems are solved in accordance with the present invention by creating an electromechanical transducer in a structural embodiment similar to the implementation of the specified prototype, but in which the following relations are observed between the number of stator cores z, the number of poles 2 · p, the number of pairs of poles p and the number of coil groups in phase d :

where k is a positive integer or a number that differs from the integer by 0.5, that is, 1, 1.5, 2, 2.5, 3, ..., and d is an even integer.

и

and

while z / 2 · p is not equal to 1.

If k in the relation (1) is an integer, the windings of the coil groups in each phase are connected according to, and when k is 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 operating mode of the converter, the voltage and current are identical in phase 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 inductors.

Expression (2) determines the optimal boundaries of the ratio of the number of cores and the number of poles (from 0.5 to 2), provided that it is not equal to 1. At the same time, the most optimal option is to perform a converter with the specified ratio close to unity, in particular based on the relation (3)

where b is the number of stator cores per phase group, and

m is the number of phases.

The above relations can be used in the design and manufacture of electromechanical transducers with various structural layouts and modes of use (generator, motor, compensatory).

Brief Description of the Drawings

Figure 1 shows an embodiment of a stator-rotor pair in accordance with the present invention

Figure 2 shows an embodiment of a converter in accordance with the present invention with four stator-rotor pairs.

Examples of carrying out the invention.

Refer to figure 1, which shows a variant of the stator-rotor pair of EMFs with the number z = 18 cores (teeth) 6, the number m = 3 phases, the number d = 2 groups of 20 and 21 cores 6, the number b = 3 cores 6 in groups 20 and 21.

The ratio between the number of 2 · p poles, the number of d groups, the number b of cores 6 (teeth) in groups 20 and 21 and the number m of phases in the stator-rotor pair 1 indicates when the maximum interaction of the magnetic flux of the inductors 9 and 10 of the stator-rotor pair is achieved and the magnetic flux generated by the winding 7 of the stator 4. Figure 1 shows a variant of the stator-rotor pair of the EMF that satisfies relation (3) to determine the number of 2 · p poles:

and the ratio (2)

i.e. close to one.

The EMF phase winding 7 can be performed using parallel branches, which, in turn, contain one or more groups of 20 and 21 cores 6. The coils of one group 20 and 21 can be connected without breaking the winding wire obtained by through winding on the winding the machine in one technological operation. This allows you to reduce the number of connections, reduce the complexity of the Assembly, simplify the design, reduce the cost of the stator, increase reliability.

The connection of the terminals of the parallel branches of the phase windings 7 of the stators 4 can be performed using ring-shaped conductors in the form of tires, which can be located on the outside of the supporting stator 5 and (or) clamping 30 rings and (or) in the inner cavity of the internal inductor 10.

The cores 6 and (or) the outer 11 and (or) the inner 12 magnetic circuits of the stator-rotor pairs can be made of ferromagnetic powder, for example by pressing, which reduces the cost of EMF. In addition, the cores 6 can be burdened from sheet electrical steel, which allows to achieve maximum values of magnetic induction and, ultimately, the highest values of torque and power density. The direction of the charge parallel to the axis of rotation of the EMF in order to increase the electrical resistance for the flow of induced currents, creating additional losses. The fastening of the plates of the cores 6 is carried out by gluing, tightening with studs or welding, and only along the lines of symmetry on the surfaces facing the working gaps 2 and 3.

The principle of operation of the EMF in general corresponds to the principle of operation of synchronous electrical AC machines. When the rotor 8 is stationary, the magnetic flux of each outer pole 13 of the external inductor 9 passes through the outer main working gap 2, through the nearest cores 6 of the stator 4, through the inner main working gap 3, reaches the inner pole 14 of the inner inductor 10, passes through the inner pole 14, then branches on the internal magnetic circuit 12 (yoke).

In the motor mode, alternating voltage is applied to the terminals of the stator winding of the EMF of each stator-rotor pair, a current flows through the winding, causing the stator to rotate MDS. When an electric current flows in the winding 7 of the stator 4, a force interaction of the magnetic flux of the winding 7 with the main magnetic flux of the EMF poles 13 and 14 occurs. Moving, the MDS stator wave rotates the rotor 8, the magnetic flux of the poles 13 and 14 moves from one core 6 to the next core 6, while inducing an electromotive force (EMF) in the active conductors 22 located in the grooves between the cores 6. The magnitude of the EMF is directly proportional to the speed changes in magnetic flux due to the magnitude of the total magnetic flux of all poles 13 and 14 of both inductors 9 and 10 and the rotational speed of the rotor 8. When the rotor rotates with a certain rotation frequency, the EMF will give mechanical power to manual ultrasonic inspection.

In the generator mode, the EMF rotor 8 is driven into rotation by an external source of mechanical energy, for example, a wind turbine, while the torque is applied to the rotor 8, for example, by means of a pulley with a belt drive. The resulting electrical energy is used in an external circuit.

When operating in the synchronous compensator mode, the EMF is connected to the network, but its shaft is necessary only for rotation in the bearings and is not suitable for docking with other devices. In this case, the number of turns 22 of the stator winding 7 must be so coordinated with the flow of poles 13 and 14 so that the EMF consumes active power from the network and gives reactive power to it. In this case, the EMF, in fact playing the role of a large capacitor, increases the power factor of the network. Reactive power is usually consumed in the network to create an electromagnetic field in numerous asynchronous motors.

In the general case, the number of stator-rotor pairs in one EMF can be different - from one to 10 or even more. Their quantity is determined by the design of the product and the ease of placement of EMF components inside the product. The rotors of the stator-rotor pairs may not be bonded to each other and rotate independently or be combined into separate rotor groups or all together, which is determined by the specific purpose of the EMF. Figure 2 shows the EMF with four stator-rotor pairs, in which the rotors are combined (fastened) in two rotor groups. In each of the stator-rotor pairs there are external 2 and internal 3 working gaps, a stator 4 containing a supporting stator ring 5 and cores 6, between which active conductors of the winding 7 are laid, a rotor 8 containing external 9 and internal 10 inductors with external 11 and internal 12 magnetic cores (yokes) with external 13 and internal 14 poles and a rotor ring 15. Support stator rings 5 stators 4 of all stator-rotor pairs are rigidly connected to a stationary hollow shaft 16. The left rotors 8 are fastened together and their resulting rotating m The moment from their rotor rings 15 is transmitted through the first bolt connection 17, the right rotors 8 are also fastened and their resulting torque from their rotor rings 15 is transmitted through the second bolt connection 18, and the resulting reactive moment of all stator-rotor pairs through the supporting stator rings 5 , a stationary hollow shaft 16 and a keyway 19. One of several stator-rotor pairs can perform an information function, for example, an m-phase rotor position sensor.

One or more stator-rotor pairs 1 EMF may have the number of pole pairs and (or) the number of phases and (or) the number of cores (teeth or grooves) that do not coincide with the corresponding numbers of other stator-rotor pairs. This allows you to get one or more generator multiphase systems with their rated voltage and rated frequency, for example 50 and 400 Hz at the same time. For example, in FIG. 2, the EMF is driven from the outside, and all the stator-rotor pairs 1 operate in a generator mode. A second variant of EMF is possible, when voltage U ₀ with frequency f ₀ and number m _{0 of} phases is supplied to the winding 7 of one stator-rotor pair 1 operating as an engine. The torque created by it brings into rotation the remaining stator-rotor pairs 1, which operate in the generator mode, forming two electrical systems U ₁ , m ₁ , f ₁ , U ₂ , m ₂ , f ₂ . Such an EMF can be used as the basis for an umformer with the aim of obtaining several levels of constant voltage. A third variant of the EMF, made according to the “generator-engine” scheme, is possible, when with disconnected rotors 8 of two stator-rotor pairs, an electric reducer can be obtained. The rotor 8 of the first stator-rotor pair is driven from the outside with an angular frequency of n _g . The voltage obtained from the winding 7 is fed to the winding 7 of the second stator-rotor pair 1, and its rotor 8 is independently and synchronously with the first rotated, but with an angular frequency n _d = i · n _g , where i is the reduction coefficient. To do this, it is necessary to fulfill the conditions of equality of voltage U _g = U _d and the number of phases m _g = m _d , as well as the reduction condition for the number of pole pairs p _g = i · p _d .

It is possible to use one of several stator-rotor pairs for informational purposes, for example, as an m-phase rotor position sensor. Such a sensor can be used as an absolute in high-precision closed-loop automatic control systems in position. The presence of a sensor simplifies the construction of an EMF control system.

Industrial applicability

For the motor-wheel of an electric vehicle when implementing the invention in accordance with the embodiment shown in FIG. 1, the following parameters were obtained: rated power of 3 kW at a speed of 700 rpm without forced cooling, the mass of the motor-wheel with a tire and an integrated brake is 25 kg, of which purely electric motor - 13 kg. The magnitude of the specific moment is 1.7 N · m / kg per motor wheel as a whole, in terms of the mass of the electric motor - 3.3 N · m / kg. In peak mode - during acceleration and braking - the peak torque is 5 ... 6 times more, while the specific torque reaches values of the order of 16 ... 20 N · m / kg.

For the electric generator during the implementation of the invention, the following parameters were obtained: rated power of 5 kW at a speed of 500 rpm without forced cooling, weight 32 kg The nominal value of the torque is 100 N · m, the specific gravity is 3 N · m / kg.

Claims (3)

1. Electromechanical transducer containing at least one stator-rotor pair, in which the stator consists of cores of material with high magnetic permeability, the ends attached to the supporting stator ring and oriented parallel to the main magnetic flux, and between which there are multiphase winding conductors , the rotor is made in the form of two coaxially located external and internal inducers-magnetic cores of a material with high magnetic permeability in the form of hollow cylinders, mounted rotatably relative to the stator, bearing alternating poles located around the circumference of the pole, facing the stator through working gaps and covering it, while the polarity of the poles located on the internal and external inductors opposite each other, consonant, characterized in that the number of poles 2 · P, the number of pole pairs p, the number of stator cores z and the number of coil groups in phase d are related by

where k = 1, 1.5, 2, 2.5, 3, 3.5 ... is a positive integer or a number different from it by 0.5, d is an even integer, while if k is an integer, the windings of the coil groups in each phase are connected according to, and at k - other than an integer by 0.5, the windings of the coil groups in each phase are connected in opposite and

and moreover, z / (2 · p) ≠ 1. 2. The electromechanical converter according to claim 1, characterized in that the ratio z / (2 · p) for the stator-rotor pair is set close to unity. 3. The electromechanical converter according to claim 2, characterized in that the ratio z / (2 · p) is set based on the ratio

where b is the number of stator cores per phase group, and m is the number of phases.

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