Abstract: A system for determining rotor position of an n-phase alternator driven by an inverter uses as inputs the stator terminal voltages of the alternator with respect to the negative power bus, which are already also provided as inputs to the inverter, and provides as outputs simulated rotor positions states. The simulated rotor position states are provided to one or more inverter controllers which, in turn, provide firing signals to one or more corresponding inverters which are used to crank an engine, e.g., an internal combustion engine of a diesel electric locomotive.

Abstract: A method and apparatus for detecting and correcting the occurrence of flashover in a direct current electric motor. The polarity and magnitude of voltage on the field winding of the motor is continuously monitored. Detection of a sudden reversal of the polarity of the field voltage accompanied by a rapid increase in magnitude results in the generation of a flashover signal. The flashover signal is coupled to power controlling elements regulating power supplied to the motor and is effective to force removal of power from the motor. In a preferred embodiment the apparatus is disclosed in a two-motor system with two field windings serially connected such that the field voltage monitoring is accomplished on a differential basis.

Abstract: Apparatus for increasing the available regenerative braking energy and for enabling low current control without frequency variation in a time-ratio controlled main thyristor power circuit for a direct current traction motor. A variable impedance element is serially inserted in a motor armature free-wheeling current path between a free-wheeling diode and the motor armature, the variable impedance element preferably comprising a power resistor and parallel connected thyristor. During electrical regenerative braking the thyristor is used to modulate the power resistor to thereby present a continuously variable impedance in the armature current path. During motoring at very low speeds the thyristor can be operated to modulate the power resistor and thus reduce the minimum controllable level of motor current normally limited to commutation current level without the necessity of reducing the main thyristor operating frequency.

Abstract: A power match system for a train of individually powered traction vehicles in which two distinct types of power control systems are employed. The system includes a programmed power matched circuit which has programmed therein the volt-ampere characteristics of a motor operating under the control of one of the types of power control systems, such as a cam controlled resistor system. The power match circuit is serially inserted in the current command system for the other type of power control, such as a chopper controlled power system. A signal representative of the motor CEMF in the chopper system is supplied to the power match circuit which then regulates the current supplied by the chopper control power system in accordance with the programmed characteristics of the cam controlled resistor system. In this manner the motive power developed by the two distinct types of power control systems is matched whereby each type of system provides substantially the same pulling power to the train.

Abstract: A method and control system for minimizing peak current levels in a direct current traction motor drive system in which the traction motor is powered by periodic current pulses metered from a direct current source by a controllable switch. The control system includes apparatus for comparing actual motor current to commanded motor current and for controlling the duty factor of the controllable switch in a manner tending to minimize any difference between actual and commanded currents. The control system further includes apparatus for changing the repetition rate of the current pulses in response to the magnitude of current in the motor, without effecting the commanded duty factor of the controllable switch, so that the ripple currents which are inversely related to repetition rate are reduced as average motor current is increased to thereby maintain total peak current levels within predetermined limits.