Hi Rafay,
I have here pdf's containing different articles for dc motor harmonics.
1. Performance analysis of low harmonics and high efficient BLDC motor drive system for automotive application.
2. Harmonics and Torque Ripple Minimization using L-C Filter for Brushless DC Motors.
3. IMPROVED BRUSHLESS DC MOTOR CONTROL ALGORITHM FOR REDUCING SOURCE CURRENT HARMONICS. SIMULATION STUDY.
Hope it Helps,