Abstract: A regenerative braking system for a linear induction motor includes a control device to increase the frequency slip in a braking mode and reduce the regenerative capacity of the motor. The control device is regulated by sensing means which monitor the voltage of the external power conductor and increase the slip if the voltage exceeds a predetermined value. This reduces the power regenerated by the motor and prevents excessive voltages in the conductor. A latch prevents cycling between the full and reduced regenerative braking to prevent oscillation of the braking force and is reset upon selection of a motoring condition for the motor.

Abstract: A self-propelled traction vehicle equipped with an a-c traction motor energized by the a-c output of a controlled current inverter is propelled by a process comprising the steps of providing a traction alternator on-board the vehicle, rotating the rotor of the alternator, exciting the field winding of the alternator, converting the output current of the armature windings of the alternator to a unidirectional current, and feeding the unidirectional current to d-c terminals of the controlled current inverter without appreciably smoothing the unidirectional current. A system for carrying out this process is also disclosed.

Abstract: Dynamic response of an a-c induction motor control system including an adjustable frequency and adjustable magnitude power source is made more stable during the transition from a motoring to an electrical braking mode by modifying the system characteristics as a function of rate of change of motor flux and torque magnitude during electrical braking. The control system responds to a torque command signal and a torque feedback signal to generate an error signal which controls the frequency of the excitation supplied to the motor and thus the torque developed by the motor. During electrical braking this error signal is modified as a direct function of the rate of change of motor flux and as an inverse function of the magnitude of torque developed by the motor. During the transition from motoring to electrical braking, when the system tends to be unstable, the rate of change of flux is relatively high while the motor torque is at a relatively low value.

Abstract: Apparatus for providing firing signals to a phase controlled rectifier circuit at a time at which valves in the rectifier circuit are forward biased without the need for providing continuous firing signals. The apparatus monitors the voltage applied across the rectifier valves and provides a signal when a valve is forward biased. This signal is applid to a gating circuit which determines whether a normal phase control firing command was initiated prior to the time the valve became forward biased. If such a command was initiated, the gating circuit passes the signal to a valve firing circuit which provides firing signals to the rectifier circuit. If the firing command was not previously initiated, the signal is inhibited and firing signals are subsequently applied to the rectifier circuit upon receipt of a firing command.

Abstract: A highly regenerative electrical brake control system including a variable time ratio power conditioning circuit for regulating braking effort of a direct current electric traction motor in a traction vehicle. The system includes a plurality of switches adapted for connecting the power conditioning circuit in a series path between the motor and a power source during high speed braking whereby the power conditioning circuit steps-down the motor generated voltage magnitude to match the power source voltage magnitude without using series connected resistors for voltage dropping. During low speed brake the switches are effective to reconnect the power conditioning circuit in a shunt arrangement with the motor whereby the motor voltage magnitude may be stepped-up to match the higher voltage magnitude of the power source. In a further embodiment provision is made for blending of dynamic and regenerative electrical braking when the power source is not totally receptive to motor generated current.

Abstract: A regenerative braking system for a linear induction motor includes a control device to increase the frequency slip in a braking mode and reduce the regenerative capacity of the motor. The control device is regulated by sensing means which monitor the voltage of the external power conductor and increase the slip if the voltage exceeds a predetermined value. This reduces the power regenerated by the motor and prevents excessive voltages in the conductor. A latch prevents cycling between the full and reduced regenerative braking to prevent oscillation of the braking force and is reset upon selection of a motoring condition for the motor.