Modeling analysis and control methods for current source inverter fed induction motor drives

Abstract

It is estimated that more than 75% of all electrical drive newlineapplications require adjustable-speed. The extensively used AC electric drive newlineis based on the squirrel-cage Induction Motor (IM) due to low cost, newlinerobustness, reduced size and simple maintenance. Further, when driven by a newlinefield oriented controller, it behaves like a separately excited DC motor, where newlinetorque and flux are decoupled and controlled independently. For adjustablespeed newlineIM applications in low to moderate power, Pulse Width Modulation newline(PWM) with Voltage Source Inverter (VSI) is usually used. An alternate newlinetopology to VSI is Current Source Inverter (CSI); its ruggedness, inherent newlineshort circuit protection and significant reduction in load harmonics prefer CSI newlineunique. So, the high performance CSI fed variable speed AC drives are newlineprepared for a variety of industrial applications. The CSI fed IM drives are newlinedominated by various control methods. The noteworthy methods are Scalar newlineControl (V/f), Input Output Linearization (IOL) control, Field Oriented newlineControl (FOC), and Direct Torque Control (DTC). The objective of this work newlineis to compare the dynamic performances of the above drive control methods newlinefor CSI fed IM drives during step change in the references. In this work, a vector based V/f controlled CSI fed IM drive is newlinepresented. The simulation model is developed using simplified matlab newlineprograms. This simulation program is used to study and verify the system newlineperformance. In addition, this method is useful during real time control newlineapplications.The vector control is valid for both steady and transient states. newlineThree well known methods are discussed here. In IOL control, an optimal newlinecontrol law is designed to achieve pre-assigned eigen values with minimum newlinepossible magnitudes for the feedback gain elements and better control newlineperformance. In Indirect FOC, a new Rotor Flux Oriented control system is newlineimplemented for CSI fed IM drive, where as DTC offers simple control newlinearchitecture with a similar dynamic performance as that of FOC. newline newline