2003 Volume 123 Issue 3 Pages 271-277
This paper proposes a novel induction motor drive system using a three-phase V-connection ac chopper that consists of two single-phase ac choppers. There are three new topics proposed in this paper. Firstly, this paper proves that the three-phase V-connection ac chopper can be operated properly only if the input and the output voltages are in synchronism . Secondly, a novel commutation method for ac chopper isproposed. The proposed commutation method combines the load current commutation and the input voltage commutation. Therefore, by applying the proposed commutation method, voltage and current surge around zero crossing of the input voltage and the load current do not occur. Thirdly, a novel high effciency control method for induction motor is proposed. The proposed control method does not require d-axis and q-axis current components, but uses only the magnitude ofthe primary current. The whole control system has a very simple structure. These new topics are confirmed by experimental results on a 750W general-purpose induction motor.