The integral part can be implemented using forward difference discretization, i.e. s = (z − 1)/Ts [30]. It is worth noticing that other discretization methods are also available [41]. Zero-order hold, where z = esTs or Tustin’s bilinear rule, where s = (2/Ts)(z − 1)/(z + 1), can be mentioned. There are several “tricks” which can be used to prevent integrator windup—an important consideration for speed control, as the torque reference often goes into saturation. One of the better ways is the “back calculation” [30], [35] or “realizable reference” [40] method, where the error between the realizable torque and the torque reference, scaled by 1/Kp, is fed back into the integrator. The following integrator update is obtained: