Abstract: This paper presents a simulation and performance analysis of speed control of brushless DC motor using FOPID with LQR. DC motor is widely used in industries even if its maintenance cost is higher than the induction motor. Speed control of DC motor is attracted considerable research and several methods are evolved. The LQR controller is the very commonly used compensating controller. This paper presents a comparison of time response specification between conventional Fractional order Proportional- Integral-Derivatives (FOPID) controller and Linear Quadratic Regulator (LQR) for a speed control of a separately excited DC motor. A class of fractional order systems having single non-integer order element which show highly sluggish and oscillatory open loop responses have been tuned with an LQR based FOPID controller. The goal is to determine which control strategy delivers better performance with respect to DC motor’s speed. Performance of these controllers has been verified through simulation using MATLAB/SIMULINK software package. According to the simulation results, liner quadratic regulator method gives the better performance, such as settling time, steady state error and overshoot compared to FOPID controller. This shows the superiority of liner quadratic regulator method over FOPID controller.

Keywords: Linear Quadratic Regulator (LQR) Proportional-Integral Derivative Controller, FOPID controller, DC motor speed control.