In this paper a smooth starter, based on a DC/DC Buck power converter, for the angular velocity trajectory tracking task of a DC permanent magnet motor is presented. To this end, a hierarchical controller is designed, which is integrated with a control associated with the DC motor based on differential ﬂatness at the high level, and a control related to the DC/DCBuck converter based on a cascade control scheme at the low level. The control ofhigher level allows the DC motor angular velocity to track a desired trajectory and also provides the desired voltage proﬁle that must be tracked by the output voltage of the DC/DC Buck power converter. In order to assure the latter, a cascade control at the low level is designed, considering asliding mode control (SMC) for the inner current loop a proportional-integral (PI) control for the outer voltage loop.
The hierarchical controller is tested through experiments Matlab, Simulink and the DS1104 board from space. The obtained results show that the desired angular velocity is well tracked under abrupt variations in the system parameters and that the controller is robust in such operation conditions, conﬁrming the validity of the proposed controller.