Three-phase wound-rotor induction motor

Abstract

A three-phase wound-rotor induction motor is prepared as setting triangle three-phase stator winding on stator and connecting wire outgoing end at top to wire outgoing end of three-phase power supply when motor is normally operated, series-connecting coils in each phase winding, switching on different power supply wire outgoing end and converting operation modes of start-up and normal operation by switch unit, arranging multiphase symmetric winding on rotor and forming composite coil by parallel-connecting two sub-coils with different number of turns in the same rotor groove.

Description

technical field [0001] The invention belongs to the field of electric motors, and in particular relates to a three-phase wound rotor induction motor whose stator windings are started using a delta-to-delta connection method. Wound rotor induction motor with ring brushes. Background technique [0002] Ordinary three-phase induction motors can start automatically, but if they are directly put into the grid to start without any measures, the starting current is often very large (5 to 7 times the rated current), and the starting torque is not too large, which needs to be limited in many applications. Starting current, but also to ensure that there is a large enough starting torque. [0003] In order to limit the starting current of the induction motor while ensuring a sufficient starting torque, the currently used starting methods mainly include: 1) step-down starting method; 2) variable frequency starting method; 3) pole-changing starting method; 4. ) Rotor winding series res...

AI Technical Summary

Problems solved by technology

[0005] The main advantage of the part-winding starting method is that it can be switched from the starting state to the normal working state without power supply, but there are two problems as follows: First, the two parts of the winding must be connected to the two main contacts through two three-phase external cables during normal operation. The contactor is connected in parallel to the power supply. This operation control method, which is different from the conventional motor, is actually found to be less reliable. The reason is that when one of the contactors has a fault such as poor contact or lack of phase, it will often lead to The motor is damaged, and if the impedance of the two external cables is not well matched, it will also cause a circulating current between the two parts of the winding, thereby reducing the overall efficiency of the motor operation and may cause failure; in addition, the two parts of the winding The number of turns of the coil or the section of the wire is often different, and the choice of the pitch of the coil is limited, which makes the manufacturing process complicated and the performance of the motor will be affected accordingly.

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