Test example: Compare characteristic of DC
motors
The motors are started at nominal speed, then load is ramped down.
Simulate for 6 seconds and plot dcxx.wMechanical
(motor speed) versus dcxx.tauElectrical (motor
torque). Default machine parameters are used.
Note that the characteristics of permanent magnet and electrical excited dc machine (at nominal excitation) is identical, but speed of the series excited dc machine rises when load torque is lowered. Dynamic increase of speed is determined by the sum of inertias. Load torque of the series excited is not lowered to zero, otherwise speed would rise infinitely.