Unitary design of small DC motors used in modular add-on electrical systems

A complete sample of investigation work involving the design of a series of permanent magnet DC electric motors is presented in the paper. It was performed as part of a research program on modular systems for the propulsion of electrical light vehicles. The work includes the concept and design of the basic unit in that series, the theoretical analysis by numerical modeling and the assessment of rated data by testing the experimental model. Similar DC motors derived from the basic unit could be fabricated with the same technology, keeping unchanged as much as possible components designed for the basic unit. In our case, the derived units have the shape, structure and dimensions of the cross-section identical with the basic unit; power variation results basically by adjusting the length of the motor, i.e. by adding/eliminating laminations and adapting the stator's length. The paper shows practical ways for the numerical analysis of the magnetic field and motor's characteristics and for the rapid adjustment of the design to a new rated power.