Seong-Yun Kang, “5상 유도전동기의 DTC를 위한 토크리플저감 방법,” 아주대학교 공학석사 학위 논문, 2017. > Paper

This paper presents an improved switching selection method for direct torque control (DTC) of five-phase induction machine. A five-

phase inverter has 32 voltage vectors, including 30 nonzero and 2 zero voltage vectors. The effective voltage vector is represented as 

a large, medium, or small voltage vector according to its magnitude. The voltage vector magnitude is related to the torque response 

and torque ripple. When the large voltage magnitude value is selected, the torque response time decreases with increased torque 

ripple. However, when the voltage magnitude is small, the torque response time and torque ripple increase. As a result, this paper 

proposes an selection method of optimal voltage vector for improved DTC of a five-phase induction motor. In addition, this paper 

shows a torque ripple reduction method of DTC using fuzzy controller in five-phase induction machine. The conventional DTC method 

has some drawback. First, switching frequency changes according to the hysteresis bands gap and motor’s speed. Second, in short 

control period, the torque ripple is rapidly increased. To overcome this problem, the proposed method is changing the voltage vector 

insertion time by using the designed fuzzy controller by torque error. Both aforementioned methods are simulated and experimentally 

verified on a two-level inverter-fed five-phase induction motor drive.