Variable Switching Frequency Control-Based Six-Step Operation Method of a Traction Inverter for Driving an Interior Permanent Magnet Synchronous Motor for a Railroad Car. - Jin-Ho Park 008; Woong Jo; Eun-Tak Jeon; Sang-Hun Kim; Chang-Hee Lee; Jung-Hyo Lee; June-Hee Lee; Junsin Yi; Chung-Yuen Won (IEEE Access, 2022)