Pseudo sliding mode control with integrative action applied to brushless DC motor speed control

Although sliding mode control has many drawbacks when applied to electrical drives due to real limitations of switches, as limited frequency of operation, turn on and turn off delays, some of its theory can be succesfully used in order to project a high performance controller, robust and with a reduced design effort. This paper shows the use of sigmoidal function, hyperbolic tangent, instead of the signal function. So, it actually consists not in a pure but in a pseudo (or quasi) sliding mode, combined to an integrative controller action and with an anti-windup effect, so the result is a high performance controller, robust to machine parameters and disturbances, and light in its design. Results shows its high performance and robustness. The chosen sliding surface has integrative control action combined to an anti-windup feature, which zeroes the steady state error and minimizes the output system overshoot.