Soft-Starting Brushless Doubly Fed Machine Winding Design and Magnetic Field Analysis

Abstract

With the development and maturity of control technology, brushless doubly-fed motor (BDFM) is widely used in the field of variable frequency speed regulation. In order to improve motor starting performance, a soft starting method is proposed to reduce impulse current. The core of the method is to reconstruct the stator power winding and rotor winding. The BDFM with wound rotor is flexible in structure, and the air-gap magnetic field distribution can be changed by adjusting the pitch, turns and connection mode of stator and rotor windings, so as to improve the motor starting performance. In this paper, the design process, connection mode and working principle of the stator and rotor of a BDFM with a 2/4 pole pairs are introduced in detail. In addition, a multi-loop chain equivalent circuit is used to calculate the starting torque in this connection mode. Finally, the starting performance of the motor is analyzed by finite element method, and an experimental prototype is made, which proves the effectiveness of the scheme.