Sliding mode vector control of PMSM drives with minimum energy position following

The original contribution of this paper is the direct use of a six switch inverter as the switching element of a multivariable sliding mode controller to achieve vector control for permanent magnet synchronous motor drives precisely realising a prescribed dynamic response to the rotor speed reference inputs. The extreme robustness against changes in the mechanical load parameters and external disturbance torques enables the user to set up the drive without any controller tuning, the only information required being the prescribed position step response settling time. The only information needed to design the controller is the relative degree (i.e., rank) of the plant with respect to the controlled outputs, i.e., the rotor speed and the direct axis current vector component. An outer position control loop is closed and a zero dynamic lag pre-compensator applied to achieve precise following of a pre-planned rest-to-rest manoeuvre that minimises the frictional energy loss for a given position change and manoeuvre time. Simulations predict that despite no knowledge of the load moment of inertia or the viscous friction coefficient, a) the precisely defined closed loop dynamics of the position step response is attained, b) precise following of pre-planned rest to rest manoeuvres is attained and c) step load torques cause negligible transient position errors.