Determination and Novel Implementation of Interval Time for Enhancing Forced Commutation Performance of Load Commutated Inverter in Low-Speed Operation

This paper proposes a method for selecting commutation intervals and a novel implementation approach for motor drives by using a thyristor-based load commutated inverter (LCI) during forced commutation operation. The equivalent circuit of the LCI system is modeled during forced commutation, and the current and voltage characteristics are formulated into ignition equations to develop a stable method for selecting commutation intervals. Additionally, an algorithm is proposed to implement and maintain the selected commutation intervals throughout operation. The proposed method for selecting commutation intervals and the corresponding implementation algorithm are verified through MATLAB / SIMULINK and experiments using a scaled model.