RU17751U1 - ASYNCHRONOUS MOTOR - Google Patents

Abstract

1. An asynchronous motor containing a stator and a rotor with a short-circuited or phase winding, separated by an air gap, characterized in that in the teeth of the magnetic circuit of the rotor are recesses in which permanent magnets are mounted, and the poles of the magnet pairs facing the air gap must be opposite. and the number of magnets corresponds to the number of motor poles. 2. The asynchronous motor according to claim 1, characterized in that the number of magnets under the pole can be equal to one, or the number of grooves per pole and phase.

Description

ASHCHRONOUS ENGINE

The device relates to the field of electrical machines, specifically to asynchronous electric motors, and can be used as a drive motor for a wide class of mechanisms.

Asynchronous motors are known, including a stator and a squirrel-cage or phase rotor. The advantage of induction motors is their simplicity, reliability, low cost. One of the significant drawbacks of an induction motor is the relatively low power factor, especially when the shaft loads are lower than the nominal value. This is due to the consumption of reactive power by the engine from the network, whose share in the total power balance especially increases in the indicated load conditions 1, pp. 393-414. In addition, the energy performance of the motor (power factor and efficiency) is lower, the lower the rated power of the induction motor.

Reactive currents load electrical networks, lead to the appearance of additional losses of electric energy in them, which depend on the square of the current, necessitate the choice of wires and cables of a larger cross section.

To reduce the reactive capacities consumed by groups of induction motors from the network, substations install compensating devices in the form of capacitor banks. This allows you to increase the power factor for the entire aggregate load, however, it is associated with additional costs.

Compensated asynchronous motors of Heiland, Osnos, and others, developed in the early 20th century, are known. The principle of their operation is based on the use of a three-brush collector machine, combined with an induction motor or located on the same shaft with it 2. Such machines have a power factor close to unity or equal to it. However, they are difficult to manufacture, have high COST and have not received distribution.

In a constructive relation to the proposed invention, synchronous motors of small power with permanent magnets of various configurations and a starting short-circuited winding are close, however, they relate to another type of machine, which has different characteristics and its advantages and disadvantages 1, p. 687-691.

The prototype of the claimed invention is an asynchronous machine, in the core of the rotor of which deep grooves are made, and the role of the rods is performed by magnetic fluid with the addition of conductive powder, particles of which may have a ferromagnetic coating. Grooves

they are closed with wedges from above, and their ends with plugs 3. Such a device, according to its author, expands the range of rotation speeds, increases the efficiency and engine power factor.

The disadvantages of such an engine are: an obvious complication of its manufacturing technology, an increase in its cost, and a decrease in reliability. For example, the deformation of wedges under the influence of electrodynamic forces can lead to leakage of fluid from the grooves, the appearance of electrical asymmetry of the rotor, etc. Thus, improving the energy performance of the engine is achieved at the cost of reducing its main advantages.

The task to which the invention is directed is to improve an asynchronous motor with a squirrel-cage or phase rotor so that while maintaining its main advantages: simplicity, reliability and low cost, it would achieve the following technical results:

-reduction of consumption from a network of reactive power,

-decrease in the total power consumed from the network, while maintaining the nominal torque on the shaft,

-improving power factor and other energy indicators of an induction motor.

The problem is solved by the fact that in an induction motor having a stator and a rotor with a short-circuited or phase winding, recesses are made in the teeth of the rotor magnetic circuit, in which permanent magnets are mounted. The number of magnets corresponds to the number of motor poles, the number of magnets under the pole can be equal to one, or equal to the number of grooves per pole and phase. The poles of the pairs of magnets facing the air gap must be opposite.

The width and height of the permanent magnet must not exceed the width and height of the tooth of the rotor magnetic circuit. The length of the magnet depends on its specific magnetic energy and can vary from fractions to the full length of the tooth.

Permanent magnets may have an aluminum or copper foil cladding, which reduces the effect of the demagnetizing effect of the working field of the engine. However, for magnets with high specific energies, there is no need to use a shell.

The device of an induction motor with permanent magnets is illustrated in Fig. 1. The bed, bearing shields and other well-known nodes and parts that are not relevant to the invention are not shown in the figure. The motor has a stator 1 with a single and multiphase winding and a rotor 2 with a short-circuited or phase winding located on the shaft 3. Permanent magnets 4 are mounted in the teeth of the rotor. Thus, the inventive asynchronous motor is a combined

a machine consisting of an induction motor and a synchronous generator, which performs the function of an internal source of reactive power. In this case, the stator is common to asynchronous and synchronous machines.

The principle of operation of the inventive induction motor is as follows. Starting the engine and its subsequent operation on a natural characteristic occurs in the usual asynchronous mode. Permanent magnets, crossing the stator winding, induce an EMF in it, directed counter-to the mains voltage and creating a reactive current component in the stator winding, which is anticipatory. This leads to a decrease in the reactive and full power consumed by the engine from the network at the same useful shaft power as a conventional asynchronous motor.

Since the additional excitation of the induction motor is carried out by the rotor, the power consumed to rotate the synchronous machine is only a few percent of the power of the induction motor. For this reason, the motor is precisely asynchronous, and not synchronous with permanent magnets.

In fig. Figure 2 shows a histogram of the total S, active P, and reactive Q powers of a 4AISV2 serial asynchronous motor with a rated power of P2N 120 W and a synchronous speed of 3000 rpm and a pilot permanent magnet induction motor manufactured by the author on the basis of a machine of this series of the same power. The histogram is constructed according to the data for the nominal mode (P2 P2ii) and the idle mode (P2 0), obtained experimentally.

In the nominal mode, the reactive power consumption of asynchronous permanent magnet motors is reduced by 30%, and the power factor increases to 0.87 in comparison with a serial engine. At the same time, the apparent power consumed by the engine also decreases, while the fraction of active power increases slightly

In idle mode, an asynchronous permanent magnet motor in comparison with a serial engine dramatically reduces the consumed full (66%) and reactive (65%) power.

In fig. 3 shows the performance of the same engines. As can be seen from Fig. 3, in the entire range of motor loads from O to Rzn, the reactive power of an asynchronous permanent magnet motor is on average one third less than the reactive power of a serial motor.

Over the entire load range, the stator current of the inventive motor is less than the stator current of a serial asynchronous motor by an average of 2425%. In idle mode, this difference is more than 30%, which is extremely important for electric drives with asynchronous motors.

in which the engine idle mode occupies a significant part of the load diagram of the electric drive.

The use of permanent magnets with high specific energy provides higher energy performance.

The manufacture of an asynchronous permanent magnet motor slightly complicates the technology and cost of such motors. For comparison, we can indicate that the cost of two magnets pressed into the teeth of a prototype of an induction motor is 200 times less than the cost of the motor itself.

Given the massive nature of the production and use of induction motors, the claimed invention can provide:

- a significant increase in the power factor of asynchronous electric drives,

- a significant reduction in reactive power consumption,

- Significant reduction in electrical energy losses.

Since asynchronous electric drives consume from 60 to 70% of all electricity produced in industrialized countries, the use of the claimed invention can provide energy savings comparable to the amount of all electricity produced.

Claims (2)

1. An asynchronous motor containing a stator and a rotor with a short-circuited or phase winding, separated by an air gap, characterized in that in the teeth of the magnetic circuit of the rotor are recesses in which permanent magnets are mounted, and the poles of the magnet pairs facing the air gap must be opposite. and the number of magnets corresponds to the number of motor poles. 2. The induction motor according to claim 1, characterized in that the number of magnets under the pole can be equal to one, or the number of grooves per pole and phase.