Understanding DC motors through experiments

We present here a set of simple experiments through which various characteristics of a DC motor can be investigated. The experiments also provide insights on how to control a DC motor. We first study the back-emf versus angular speed and the torque versus current characteristics. We then extract the moment of inertia of the rotor and the speedtorque curve for the load from the start-stop dynamics of the motor. Finally, we study an alternate way of obtaining the angular speed from the back-emf waveform.