Field Oriented Control of Induction Motors Based on DSP Controller

Induction Motor is the most widely used industrial workhorse due to its reliability and high robustness, low cost and good efficiency. Field oriented control technique (FOC) of AC machines facilitates the dynamic control of induction motor. Field oriented control improves the dynamic performance of an induction motor and is commonly used method for speed and torque control applications. In this thesis, the basic concepts and equivalent circuit model of squirrel cage induction motor are explained. A mathematical model is developed for squirrel cage induction motor. The Clarke's and Park's transformations are used to convert abc reference frame into dq rotating coordinate frame. The three-phase inverter, which supplies desired voltage/current to the stator winding is designed based on Pulse Width Modulation (PWM). The space vector PWM technique is implemented for controlling the three-phase inverter switches, which is simulated using Matlab/Simulink. Field oriented control method is developed to get the decoupled control of flux and torque, which is comparable to the DC motor. The direct and indirect field oriented control methods are presented to obtain rotor flux angle. In this thesis, a novel field oriented control scheme for induction motor is developed. PID based controllers are designed for speed and current control loop based on symmetrical optimum method, which guarantee the maximum phase margin. The control approach can be applied to both direct and indirect field oriented control of induction machines. The computer simulations are used to show the efficacy of the proposed algorithm. The developed field oriented control method is implemented using Texas Instrument AC motor development kit and software. A short review is presented on high voltage motor control board and DSP controllers. The field oriented control of induction motor shows satisfactory performance based on computer simulation and hardware implementation results