Hybrid bidirectional multilevel inverter structures for induction motor drive

Multilevel inverters performance enhancement is a major topic, which has attracted the attention of most of the researchers, to evolve with newer topologies and modulation strategies. In this manuscript, two novel hybrid bidirectional multilevel inverter structures, which are suitable for bidirectional loads, are proposed. An enhancement in the voltage levels and reduction of the component count are achieved for these newly introduced structures. Modular expansion and series cascading are suggested systems for extension of the voltage levels. The prime requirement in most of the industrial drives is a controlled output. VSI fed induction motor drive satisfies this requirement. The Multicarrier PWM technique has been applied to the basic bidirectional seven level models and nine level model and its performance with induction motor as load has been analyzed for various modulation indices. The simulated results of the proposed structures are verified using MATLAB/SIMULINK platform. The characteristics such as stator current, rotor current speed and torque plots achieved as above model affirm that its performance is good. By then, the tracking time of the proposed work during reference speed change, load change and constant reference change is 0.185, 1.094 and 1.5 s. The tracking time of the VSI during reference speed change, load change and constant reference change is 0.5 s, 3.8 and 3.5 s. The tracking time of the MLI during reference speed change, load change and constant reference change is 0.2 s, 1.8 and 2 s.