Optimized Torque Ripple Suppression Method for Standalone Brushless Doubly Fed Induction Generator With Special Loads

In the standalone power generation system based on brushle doubly fed induction generator (BDFIG), the special loads such as unbalanced loads and nonlinear loads will cause negative sequence, fifth and seventh harmonic components in power winding (PW) and the corresponding harmonic components in control winding, which will cause some torque ripple so as to make the machine unable to output stable active power, increase the vibration and noise, and so on. This article will first analyze the harmonic components of the torque in details, and then propose an optimized torque ripple suppression method. Through the low frequency harmonic control method of the line side converter without additional sensors, the negative sequence, and fifth harmonic components of PW voltage are controlled to achieve the suppression of the second and sixth harmonic components of the torque. Compared with traditional active filtration method, the proposed method in this article needs to satisfy fewer constraints and tune fewer parameters, and can be utilized more flexibly. Comprehensive experimental results based on a 5-kVA BDFIG demonstrate the effectiveness of the proposed method.