Fig.5 shows the general structure of each of the three sliding mode control loops.
The basic sliding mode control system of Fig. 1 would suffer from control chatter, i.e., high frequency switching of the control variable, u, between its limits, ±U , and this might interact adversely with the switching of the inverter, so a boundary layer is introduced [1] in which the switching element is replaced by a saturation element with the same control saturation limits having a finite but relatively high gain, K.