Speed control of two-inertia system by PI/PID control

The purpose of this paper is to develop systematic analysis and design meth ods for a two-inertia system. A Conventional proportional-integral speed co ntrol system with a torsional load is redesigned, and the damping character istic of the system is derived and analyzed. It is shown that the dynamic c haracteristic of the system strongly depends on the inertia ratio of load t o motor. Three kinds of typical pole assignments with identical radius/damp ing coefficient/real part are applied and compared, and the merits of each pole-assignment design are concluded. Furthermore, for small inertia ratio, we present how to improve the damping of the system by a derivative feedba ck of motor speed.