Abstract: An electric drive system that is used in submarines, for powering or contling towed arrays handling systems and other machinery, which has at least one submersible brushless direct current motor whose operation is monitored and regulated by a 6-step variable bus motor controller receiving command signals from a control and indicator unit. The controller receives, in addition to the command signals for the operation of the motor from the control and indicator unit, signals indicative of the rotational velocity of the motor from the motor itself. The controller comprises a servo-mechanism unit that compares the two signals and adjusts the speed of the motor in compliance with the command signals from the control and indicator unit.