Under the finite sampling time the continuous variable structure control algorithm is modified to the discrete variable structure algorithm. In position control of direct drive brushless DC motor by DVSS (discrete variable Structure system), conventional sliding surface has reaching phase and rather large steady state error.
To overcome theses immerits, new sliding surface is considered. The new sliding surface has summation term in addition to the conventional sliding surface and also considers system initial states. Summation term affects to reduce steady state error. And consideration of initial states makes no reaching phase in the state trajectories.
The performance of the new sliding surface is compared with that of conventional sliding surface through digital computer simulation and experiments.
