What is the electronic control of motors?

It is necessary to control motors. That is, motors must be started, stopped, and reversed, and, within limits, it must be possible to control their speed.

The controls needed to perform these various functions on DC motors are designed to alter the quantity or the direction; of the current in the field or in the armature of the motor. On DC controls, these functions were shown to consist mainly of resistances, switches, and solenoids.