Characteristics of asynchronous motors with combined windings. Scheme, description

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Characteristics of asynchronous motors with combined windings. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Electric motors

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Serially produced asynchronous motors (IM), which are equipped with all modern enterprises, contain three sets of phase windings, which are shifted by 120°. This design is due to the ubiquitous three-phase AC system proposed by M.O. Dolivo-Dobrovolsky.

Modern research has shown that a four-phase AC power supply system is the most efficient. If the existing power supply system were converted into a four-phase one, then with the same useful work, it would be possible to reduce the electricity consumed by the AD. But in real networks, such a transition is impossible.

On a local scale, the four-phase AC power system is widely used in modern equipment, which has high requirements for energy efficiency and noise levels. The four-phase system provides such high parameters due to the optimal phase shift angle of 90°.

In order to obtain a phase shift angle of not 120°, but 90° in serial IMs, it was proposed by N.V. Yalovega to install combined orthogonal windings in IMs between the phase windings. At the same time, the characteristics of IM with combined windings in their parameters approach the characteristics of four-phase IM. Induction motors with combined windings have lower starting currents compared to serial ones; increased starting torque; mechanical characteristic close to excavator; higher efficiency and cosϕ in a wide range of loads; lower level of electromagnetic and mechanical noise; less heating; reduced electricity consumption.

The reduction in the level of electromagnetic mechanical noise and vibration is due to the fact that the combined windings suppress the odd higher harmonics of the field and currents. The shape of the field in the air gap and magnetic circuits has been improved. Due to the greater sectioning, the insulation of the windings is strengthened and the turn-to-turn voltage is reduced. For high-voltage IM increased resistance to corona in the frontal parts.

Combined windings can be installed on almost any three-phase IM in the process of overhaul or manufacturing. Such work can be performed in the conditions of operating enterprises during the repair of the operating fleet of AD. Such modernization for the enterprise is painless and does not require significant capital expenditures. At the same time, by upgrading the most energy-intensive IM, enterprises in the shortest possible time have the opportunity to reduce electricity consumption. This is the cheapest way to achieve energy savings. The introduction of other energy-saving technologies requires the attraction of more significant funds.

The characteristics given below were taken for two motors that underwent major repairs after winding burnout. Standard windings were mounted on one, combined on the second. The measurements were carried out in a specialized laboratory of the Karl Marx Electromechanical Plant.

Figure 1 shows the characteristics of idling,