The Variable-integrator PID Control on Brushless DC Motor System

The effect of integral element in PID controller is to eliminate static error.But under the action of the inte-gral term,large disturbances or setpoint changed substantially often resulted in large overshoot and long time fluctua-tions because of inertia and lagging.Due to the above problem,the control system must have the characteristic that in-tegral role should be reduced or even no when the deviation is large and strengthened when the deviation is small.The conventional PI control algorithm is analyzed in-depth and a modified PID is introduced on the control system of brushless DC motor,which is a time-varying,strong coupling,nonlinear system.The experiment is conducted and the results show that the above methods significantly improved the static and dynamic performance of the system.It not only reserved the role of integration,but also reduced the overshoot.