RU1835594C - Asynchronous engine - Google Patents

Abstract

Usage: electrical engineering, induction motor. The inventive induction motor contains a stator magnetic wire 1, a three-phase toroidal winding 4, a magnetic shunt shunt 5, a toroidal magnet winding 7. two short-circuited rotors 10 and 11 and an intermediate cylinder 14. The stator magnet wire has slots on the inner and outer surface x. A magnetic shunt is placed on the outer surface of the stator and has grooves 6 on its inner surface. The second squirrel-cage rotor 10 is arranged concentrically with respect to the first 11. An intermediate cylinder 14 of non-magnetic alloy is placed between the two rotors. The grooves of the second rotor have a smaller cross section than the first. The axis of the grooves of the rotors coincide. The winding of the first rotor is made of copper, the second - of brass or bronze. 5 ill.

Description

The invention relates to electrical engineering and can be used in systems requiring a wide range of speed control and good starting characteristics.

An object of the invention is to expand the speed control range of an induction motor with improved starting performance.

The goal is achieved by placing a second short-circuited rotor located concentrically with respect to the first, the axes of the grooves of the second and first rotors coincide, and the grooves of the second rotor have a smaller cross section than the first.

An asynchronous motor with an adjustable rotation speed and improved starting characteristics (see Figs. 1, 2) contains a stator magnetic circuit 1 with grooves 2 on the internal and 3 external cylindrical

surfaces in which a three-phase toroidal winding 4 is placed. A magnetic shunt shunt 5 located on the outer cylindrical surface of the stator package has grooves 6 on the inner surface, the axes of which coincide with the axes of the stator grooves.

The magnetization winding 7 of the toroidal type is located in the grooves b of the magnetic shunt and on the outer surface of the housing with internal protrusions 8. A rotor 9 is placed in the bore of the stator package.

The rotor is made in the form of two short-circuited rotors 10 and 11 located concentrically between the surface of the first rotor 11 and the inner surface of the second rotor 10, an intermediate cylinder 14 of non-magnetic alloy is located, the axis of the grooves of the second 13 and the first 12 rotors coincide. The grooves of the second rotor have a smaller cross section than nepi / w. Winding second

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the rotor 15 is made of brass or bronze, the first 16 is made of copper,

In FIG. 1 shows that the magnetization winding 7 is connected to a control unit 17, to which a signal is supplied to a point by a consumed induction motor, from a current transformer 18 and a control signal. .

The control unit (see Fig. 3) includes a measuring body 19, to which signals from a current transformer 18, a control signal Uynp, and from a reference voltage unit 20 are received; reference voltage block 20; an amplifier 21, in which the amplified signal from the output of the measuring organ enters the magnetization winding 7, with the aim of increasing the speed, it is made on semiconductor elements. The circuits of the measuring body 19, the reference voltage unit 20, and the amplifier 21 are well known.

An adjustable speed induction motor operates as follows.

When the motor is switched on (starting), the current consumed by the stator winding (4) significantly exceeds the rated current of the motor. As a result of this, the signal from the current transformer 8 is supplied to the control unit 17 and the current in the magnetization winding 7 increases.

In this case, the magnetic shunt is saturated and the flux, as well.

An increase in the working magnetic flux рараЬ leads to a significant increase in the flux closing through the PMO of the first 11 magnetic circuit of the rotor, since The PMO of the second rotor 10 is of such a size that, in the minimum current mode, magnetize 7 in the winding, and therefore, the flux ФТ, which is completely closed through it, saturates it, i.e. . An increase in the flux Фg during engine start leads to what is observed, due to a significant excess of the reactance of the short-circuited winding 16 over the reactance of the short-circuited winding 15, a significant excess of the current in the winding 15 over the current in the winding 16, i.e. similar to a double squirrel cage engine 1,

Thus, at the time of starting the engine has a large starting torque {M start.), Because it is due to the interaction of the working magnetic flux with the current of the winding 15, which has a large resistance, and a lower value of the consumed (starting) current, because engine has increased

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active resistance of the rotor (see Fig. 4).

As the rotor accelerates, the amount of current consumed by the motor stator decreases, the signal from the current transformer 18 decreases, and the current in the magnetization winding 7 decreases,

In this case, the magnetic circuit of the shunt is unsaturated and, a. Magnetic flux in the rotor, as and there is an intermediate cylinder that closes mainly through the PMO of the second (10) rotor (F1). Those. under minimum load, the moment is created by the interaction of the working magnetic flux with the current flowing through the short-circuited winding (15), which has a large active resistance.

The motor has a mechanical characteristic Ml (see FIG. 4), in which MTech is shifted to the right, as for an engine with increased rotor resistance and works with Si slip.

When a signal is supplied to the control unit 17 (Uynp increases), the current in the magnetization winding 17 increases. This leads to an increase in the magnetic resistance of the shunt 5 and, as a consequence, to a decrease in Fg and an increase in Php. Because in 10p-pn mode (p, Fg-max, the increase in the slave leads to an increase that closes through the rmo of the first rotor 15. Therefore, the short-circuit winding 16, which has a small active resistance, begins to participate in the creation of the electromagnetic moment in the motor. This indicates the fact that the mechanical characteristic begins to shift to the left in the direction of decreasing sliding and the frequency of the motor increases.

For the occasion. which means that the maximum current in the winding is magnetized, the mechanical characteristic has the form M2, and the slip in this case is S2, because ,, i.e. the moment is due to the interaction of the magnetic flux with the currents of the short-circuited winding 16 having a low active resistance. In this case, the phenomenon of current redistribution as at start-up is not observed, since the frequency of the EMF and current in the rotor windings (f2) is small, and therefore the reactances are small and their role is insignificant.

Taking into account that in the prototype when changing the current e of the magnetization winding, the maximum of the electric moment changes at a constant (see Fig. 5), and in the invention it changes mainly 5 kr with a small change in the maximum value of the electromagnetic M, speed control (Si-S2 ) in the proposed device is much wider than in the prototype.

Thus, the invention allows, by making two rotors arranged concentrically relative to each other and having an intermediate cylinder of non-magnetic alloy between them, making the grooves of the second rotor smaller in cross-section than the first, the winding of which is made of brass or bronze, to expand the range of speed control of the motor and improve starting performance.

Claims (1)

SUMMARY OF THE INVENTION An asynchronous motor comprising a stator magnetic circuit with grooves on the inner and outer cylindrical surfaces, in which a three-phase toroidal winding is placed, a magnetic shunt placed on the outer cylindrical surface of the stator package with grooves on the inner surface, the axes of which coincide with the axis of the stator grooves with a toroidal coil placed in them magnetization, and squirrel-cage rotor, characterized in that, in order to expand the range of speed control of the motor and improve starting characteristics, there is a second a squirrel-cage rotor located concentrically relative to the first, between the outer surface of the first rotor and the inner surface of the second rotor there is an intermediate cylinder of non-magnetic material, the axes of the grooves of the second and first rotors coincide, and the grooves of the second rotor have a smaller cross section than the first, the winding of the second rotor is made of brass or bronze, the first - from copper. 3 Fig 1 and TR Ki4 ".- {. / g ( M-N about; ff / z h $: $ t #. wC  / 7 I  U ) Zt & tGGSCBI V2 vKpa Oi .1SKP, S % g h L zan3 zonf Mi Mem i S  ig s