SU1561183A1 - Ac electric drive - Google Patents

Abstract

The invention relates to electrical engineering. The aim of the invention is to expand the range of speed control. To this end, in the AC drive, the stator of the asynchronous motor with a short-circuited rotor is equipped with two three-phase sections 10, 11, connected by the same phases in a zigzag pattern. The stator winding 1 is connected to the secondary winding 5 of the transformer 2 and to the primary winding 4 of this transformer. Additional controllable switches 12, 13 were introduced, the AC terminals connected to the connection points of windings 1 and 5, and section 11 with winding 7 of transformer 3, respectively. The result is a twofold increase in the net magnetic flux of the engine. 8 il.

Description

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Editor A „Lezhnya

Compiled by AoGolovchenko

Tehred L. Oliynyk Proofreader M.Samborsk

Order 983

Circulation 450

VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5

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Production and Publishing Combine Patent, Uzhgorod, st. Gagarin, 101

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Subscription

Claims (1)

Claim An AC drive containing an asynchronous motor5 a short-circuited rotor winding and a three-phase stator winding, two transformers with three-phase primary and secondary windings, while the ends of the phases of the secondary winding of each transformer are connected to a star, two fully controllable AC keys , each of which is composed of diodes connected by a three-phase bridge circuit, closed by a controlled valve from the DC terminals, the beginning of the primary to these transformers 20 are equipped with clamps for connecting to the network, the ends of the phases of the primary winding of the first transformer are phase-wise combined with the ends of the three-phase stator winding of an asynchronous motor and 25 are connected to the terminals of the variable switching cycles. The voltage curve (Fig.6d), which determines the spectral composition of the main magnetic flux of the controlled motor, is much closer to the sinusoidal shape than the voltage curves of Fig.6a and c, corresponding to the output voltages of the simplest direct frequency converters based on the use of transformers 2 and 3, and semiconductor keys 8, 9, 12, 13. The main component of the output voltage curve (fig.bd) is determined by the sum of these components of the output voltages of both of these simplest direct frequency converters and therefore more than twice each of these components " Therefore, the device provides a twofold increase in the resulting magnetic flux of the motor, corresponding to the main component of the supply voltage of the stator of variable frequency. Since an increase in the frequency of the voltage supplying the motor is accompanied by a decrease in the corresponding magnetic flux and torque, the noted difference provides it with a significant increase in the upper limit of the range of the bridge circuit of the first fully controlled key, and the second terminals of the primary winding of the second transformer are connected to the terminals of the alternating current bridge. a second controlled key circuit, characterized in that, in order to expand the speed control range, the stator winding a the in35 motor is equipped with two three-phase sections interconnected in a zigzag circuit, and two additional fully controllable keys are introduced, made similar to the main keys, with the beginning of each phase of the stator winding of the induction motor connected to the beginning of the same phase of the secondary winding of the first transformer, and 45 points their connections are equipped with leads for connecting the first additional fully controllable bridge circuit to the AC leads. the key, the ends of the phases of the first section 50 of the stator winding are connected to the ends of the same phases of the primary winding of the second transformer, the beginnings of the phases of the secondary winding of which are connected to the ends of the phases of the second section of the stator winding of the induction motor and connected to the alternating current terminals of the second supplementation of the speed of the controlled induction motor . Full-body key. • 1561 183 KEY Key 12 zPbFtFbFE% d4J ~ LFLJ ~ ^t • fas ί — iljini., nr „