A Series-Connected Multilevel Inverter Topology For Medium-Voltage BLDC Motor Drive Applications

Present day drive types are the Induction motor drives with voltage source inverters. Also the voltage waveforms of traditional two level inverter fed Induction motor shows that the voltage across the motor contains not only the required “fundamental” sinusoidal components, but also pulses of voltage i.e. “ripple” voltage. Moreover the voltage waveforms produced by the inverter has sharp edges. The rate of change of voltage with respect to time i.e. dv/dt is very high at these edges, of the order of 500–5000 V/µs. The two-level inverter topology has attracted attention in low power low voltage drive applications where as Three Level inverter topology has attracted attention in high power High performances voltage drives applications. The Main purpose of these three level inverter topologies is to provide a three phase voltage source, where the amplitude, phase, and frequency of the voltages should always be controllable. Although most of the applications require sinusoidal voltage waveforms the benefits are especially clear for medium-voltage drives in industrial applications and are being considered for future naval ship propulsion systems. In this paper, a topology with series connection of three-phase three-level inverters is proposed, which addresses the problems of medium-voltage drives. The simulation results based on Matlab/Simulink are discussed in detail in this paper.