Power Electronics and Motor Drive Systems

12.2. DC Motor Drive Systems

The dc motor historically precedes the ac motor. Because of its ability to provide easy speed and torque control, was for decades the only choice for electric drive systems requiring variable speed operation. The ease of control is that generally in a dc motor rotation speed is proportional to the applied voltage to the armature and the developing torque is proportional to the armature current (this is clearly only for separately excited dc motors). Therefore, as is already evident, it is quite simple to control such a motor (e.g., through a dc–dc converter). The dc motors have been used for many years in electric drive systems and was considered indispensable for variable speed. Only the last 20 years been able to ...