Kyo-Beum Lee, Joong-Ho Song, Ick Choy, and Ji-Yoon Yoo, “Torque Ripple Reduction in DTC of Induction Motor Driven by Three-Level Inverter With Low Switching Frequency,” IEEE Transactions on Power Electronics, vol. 17, no. 2, pp. 255–264, Mar. 2002. -SCI > Paper

A torque ripple reduction technique of direct torque control (DTC) for high power induction motors driven by 3-level inverters with

the inverter switching frequency limited around 0.5-1 kHz level is presented. It is noted that conventional DTC algorithms to reduce

torque ripple are devised for applications with relatively high switching frequency above 2-3 MHz. Such conventional algorithms

cannot accomplish satisfactory torque ripple reduction for 3-level inverter systems with lower switching frequency. A new DTC

algorithm, especially for low switching frequency inverter system, illustrates relatively reduced torque ripple characteristics all over

the operating speed region. Simulation and experimental results show effectiveness of the proposed control algorithm.