Speed control method of DC motor drive system with speed observer

A software-implemented control system of a DC motor (DCM) with a reduced-order observer is presented. In the proposed model, an estimated speed is calculated using armature current. The load torque is assumed to be constant in the analysis of the system, at first. In the case of dynamic load change, a torque feedforward control system is considered. Moreover, the design of the speed observer and the load torque observer is discussed. The main drive system is constructed using a 400 W DCM, and another motor of the same time is coupled as a load. The period of the bridge circuit connected transistor power converter is 250 μs, and the total processing period is 1 ms. The converter is modeled by a sample-hold model, and digital proportional-plus-integral controllers are used both in the speed control loop and in the current control loop. The validity of the proposed model and analysis is confirmed by comparing the simulation results on the speed response with experimental results