An electromechanical power transfer system that transfers power between a direct current (DC) electrical power system and a prime mover, comprises: a permanent magnet machine (PMM) comprising a permanent magnet (PM) rotor that rotates a drive shaft of the prime mover, a stator and a control coil; that an inverter/rectifier system for converting DC power from the DC power system to multiphase alternating current (AC) power on an AC bus; a control coil current regulator system for regulating current through the control coil; wherein the inverter/rectifier system responds to a position reference signal, a current load feedback signal and a current load reference signal to regulate acceleration of the PMM; wherein the control coil current regulator system responds to a control coil current reference signal and a control coil current feedback signal to regulate current in the PMM; and wherein the power transfer system starts in an open loop mode, and the first and second speed switches respond to a closed loop enable mode to switch from their open loop mode to their closed loop mode.