Microprocessor-based feedforward controller for a CSI-IM drive with state feedback

A microprocessor-based multivariable controller incorporating state feedback as well as feedforward control for fast regulation and stability of a current source inverter-fed induction motor (CSI-IM) drive is presented. The design of the state feedback controller is based on the industrial regulator theory together with the pole-placement technique applied on a linearized d-q axes state-space model of the drive and includes a reduced-order observer to estimate the inaccessible states such as d-q axes rotor currents. A feedforward control in terms of reference and disturbance inputs has been added to the feedback controller-observer to obtain faster dynamic response. The controller is implemented in real-time using an Intel 8085 microprocessor kit. The hardware and software aspects of the controller are discussed, and test results are presented and compared with digital simulation results for step changes in references and load torque. Typical results show the possible improvement in response with the addition of feedforward control.<>