Abstract: A fault protection system for an AC-DC distribution system detects the presence of DC content at individual loads, isolates the load responsible for the fault from the remainder of the distribution system, and blocks DC content from being propagated from the faulty load to the AC source. The fault protection system includes at least one circuit breaker connected to monitor the AC current provided to the individual electrical load and to detect the presence of DC content indicative of the load being faulty. In response to detected DC content, the circuit breaker trips open to disconnect the electrical load from the AC distribution system to prevent DC content from being propagated to adjacent loads.

Abstract: A fault protection system for an AC-DC distribution system detects the presence of DC content at individual loads, isolates the load responsible for the fault from the remainder of the distribution system, and blocks DC content from being propagated from the faulty load to the AC source. The fault protection system includes at least one circuit breaker connected to monitor the AC current provided to the individual electrical load and to detect the presence of DC content indicative of the load being faulty. In response to detected DC content, the circuit breaker trips open to disconnect the electrical load from the AC distribution system to prevent DC content from being propagated to adjacent loads.

Abstract: The present invention provides for detecting rotor speed through the use of sense coils on the stator teeth. Voltage ripples caused by the rotor slots is detected by combining the signals of several such sense coils so that the fundamental voltage signal is cancelled or rejected and only the ripple voltages remain, a signal proportional to rotor speed. Several alternative methods for implementing that technique are discussed herein. At low induction motor speeds, the present invention filters out the voltage ripples and incident third harmonics and instead estimates rotor speed from the fundamental voltage. When the induction motor is already being driven by a prime mover, the present invention selects a proper initial frequency command for initial motor start by identifying rotor speed from the PWM inverter. Further, the present invention provides for using a generator to control voltage to the induction motor, with a PWM inverter to control frequency signals to the induction motor.

Abstract: A control for operating an electromagnetic machine in a starting mode of operation wherein the main armature winding of the machine receives electrical power from a controllable power source during the starting mode of operation, comprises a circuit for detecting a magnitude of a parameter of power applied to the main armature winding relative to a stationary frame of reference, a position sensor for detecting rotor position of the electromagnetic machine, a converter responsive to angular position indication for converting the detected parameter magnitude into field and torque producing components relative to a rotating frame of reference, and a circuit responsive to the field and torque producing components for controlling the power source during operation in the starting mode. This control includes an igniter for igniting a prime mover.