Research on Discrete Variable Frequency soft starting and electricity-economizing control system of induction motor

Against soft starting of 3-phase induction motors with heavy loads which is achieved by means of Discrete Variable Frequency(DVF) and electricity-economizing control system in light load situation, some technical problems are analyzed and studied. Analysizes the optimal combination of phase sequence of DVF bands based on the theory of DVF soft starting.The given voltage of the initial frequency is appropriately increased ,in order to make up the voltage drop resulting from the freewheel problems of equivalent sine policy. Based on the power factor angle the closed-loop control strategy is designed.Based on control strategy of optimal adjustion voltage,Energy saving measures are taken on the condition of light load;The soft ware and hard ware of the control system are designed at last.Simulations results made by MATLAB/simulink under light load configurations are presented to show the reliability and the effectiveness.