Steady-State Investigations of a Chopper-Fed Dc Motor with Separate Excitation

A fixed frequency pulsewidth modulated chopper scheme is utilized to obtain a variable dc voltage from a constant dc voltage source. The steady-state performance of a separately excited chopper-fed dc motor is analyzed by four different methods based upon the following assumptions: 1) negligible commutation interval; 2) negligible ripple in the armature current; 3) constant current during commutation; and 4) direct solution of the governing differential equations. The effect of increased armature circuit resistance due to pulsating armature voltage on the characteristics obtained is discussed. The results by method 4) are found to show good agreement with experimental values.