MATLAB-based simulation of three-level PWM inverter-fed motor speed control system

The need for energy savings and introduction of new high power devices like IGCTs accelerate the broad use of medium and high voltage adjustable speed drives (ASD) in industrial and traction applications. As part of the mission to design a 6 kV, 1600 kVA three-level converter-based ASD, a simulation system is developed using MATLAB package for the purpose of validating the practical power electronic circuits and offering suggestions for controller design. In this paper various aspects of the proposed simulation system are discussed, including the Simulink modeling of the power electronic circuit, control mechanism of the simulation and the friendly graphic user interface (GUI). Some key issues in improving simulation efficiency are also highlighted. For illustration, two control schemes, the conventional V/F control and the direct torque control (DTC), are investigated. The starting process of the controlled motor system is simulated. Results demonstrate the effectiveness of the developed simulation system and also the superiority of DTC over open-loop V/F control in speed regulation and torque response.