Abstract: Methods of dynamic braking include two embodiments with braking circuits for vehicles such as, for example, locomotives which are operable down to very low speeds. These circuits can provide a braking force even at zero locomotive speed.

Abstract: The present invention relates generally to regenerative braking methods for a hybrid vehicle such as a hybrid locomotive, which are compatible with optimum management of a large battery pack energy storage system. Four methods for recovering energy from regenerative braking and for transferring this energy to an energy storage systems are disclosed. These methods may also be used with battery operated vehicles.

Abstract: Methods of dynamic braking include two embodiments with braking circuits for vehicles such as, for example, locomotives which are operable down to very low speeds. These circuits can provide a braking force even at zero locomotive speed.

Abstract: An apparatus and method for making a self-supporting fiber optic cable (40) having a messenger section (42) and a core section (44). The messenger section (42) and core section (44) include a jacket (47) that are interconnected by a series of webs (48) spaced by longitudinal gaps. The core section (44) includes a slotted core (45) having at least one slot with at least one optical fiber ribbon (46). Jacket (47) includes a substantially uniform cross sectional thickness. A method of making self-supporting fiber optic cable (40) comprises the steps of drawing the messenger wire (43) and the core (45) through a melt cavity including a molten jacketing material therein. Messenger section (42) and core section (44) are then defined by coating the messenger wire and the core with the molten jacketing material. Webs (48) are formed intermittently between the messenger and core sections (42,44).

Abstract: For responding to a shorted gate in a gate turnoff thyristor the gate electrode of which is connected by means of a controllable switch to a control voltage terminal having a negative potential with respect to the cathode potential of the thyristor, the controllable switch being arranged to conduct negative gate current in response to a thyristor turnoff command, voltage comparing means is coupled to the controllable switch for detecting when the switch is conducting negative gate current of relatively high magnitude, timing means is active for a predetermined interval following the start of said thyristor turnoff command, and logic means is operative to cause the switch to stop conducting negative gate current if the voltage comparing means detects high gate current at the end of such interval.

Abstract: A plurality of high power semiconductor devices are connected in circuit with at least one electric traction motor for controlling electric power to the motor. The semiconductor devices are each thermally connected between a pair of generally hollow heat sinks adapted for passing cooling air therethrough for extracting heat therefrom. An anode terminal of the devices is coupled to one of the heat sinks of a pair and a cathode terminal of the devices is connected to the other heat sink of the pair. Each of the heat sinks are mounted in a cantilever fashion to a common air plenum forming one wall of an electrical circuit area of a vehicle. The distal ends of the heat sinks of a pair are coupled together by an air flow conduit thus forming a continuous air passage through the pair of heat sinks which begins and ends at the surface containing the air supply plenum. One end of one of the pair of heat sinks, preferably the heat sink coupled to the cathode terminal, is connected to an exhaust conduit.

Abstract: Flashover protection is provided for a locomotive propulsion system including a plurality of d-c traction motors each having a commutator subject to flashovers, a traction alternator having armature and field windings and a rotor driven by a prime mover, a controllable source of excitation current connected to the alternator field, and means including an electric power rectifier for connecting the alternator to the motor commutators. It comprises means for producing a fault signal whenever a flashover occurs in any motor, a solid-state controllable electric valve connected between the excitation current source and the alternator field and having alternative conducting and non-conducting states, and means for changing the valve from conducting to non-conducting states in response to a fault signal being produced, whereupon the magnitude of excitation current in the alternator field is rapidly reduced toward zero and the alternator's output current is correspondingly decreased whenever a flashover occurs.

Abstract: A power supply has a stack formed by a first bus plate, a gate take off (GTO) thyristor, a second bus plate, a bypass diode and a third bus plate all mounted to a heat sink by a single clamp, with the anode of the thyristor closest to the heat sink. Preferably, the bus plates are sized and of a material to provide local thermal storage. The heat sink then can be sized to handle only the average heat dissipation requirements, rather than the peak requirements, and the total power supply can be very compact.

Abstract: Flashover protection is provided for a locomotive propulsion system including a plurality of d-c traction motors each having a commutator subject to flashovers, a traction alternator having armature and field windings and a rotor driven by a prime mover, a controllable source of excitation current connected to the alternator field, and means including an electric power rectifier for connecting the alternator to the motor commutators. It comprises means for producing a fault signal whenever a flashover occurs in any motor, a solid-state controllable electric valve connected between the excitation current source and the alternator field and having alternative conducting and non-conducting states, and means for changing the valve from conducting to non-conducting states in response to a fault signal being produced, whereupon the magnitude of excitation current in the alternator field is rapidly reduced toward zero and the alternator's output current is correspondingly decreased whenever a flashover occurs.

Abstract: For connecting the d-c terminals of a voltage-source inverter to a direct current (d-c) power source, a d-c link capacitor is connected directly between the d-c terminals, a line capacitor is connected in parallel with the d-c link capacitor, and a series inductor is connected between the line capacitor and the source. A dynamic brake resistor and an electric power chopper are connected in series with one another across the line capacitor. Between the two capacitors, no inductance is provided but a resistor is inserted in the braking current path during electrical braking operation of the inverter.

Abstract: Apparatus for controlling the voltage on a commutating capacitor in a thyristor time ratio control power circuit whereby the energy stored in the capacitor may be continuously adjusted to a magnitude required for commutation so that the size of the commutating circuit can be significantly reduced. An inductive circuit is provided in a charging current path for the capacitor so that the capacitor can be charged above available source voltage by capacitive/inductive action. A controllable switch connected in parallel with the inductive circuit provides a short-circuit path for terminating charging of the capacitor. A logic circuit monitors capacitor voltage, source voltage and load current and closes the controllable switch when the capacitor voltage reaches a magnitude established by the logic circuit as sufficient to commutate the measured magnitude of load current.

Abstract: A propulsion system for an electrically driven traction vehicle includes a chopper, a d-c traction motor, and means effective when the system is operating in a motoring mode for connecting the chopper in series with the armature and the field windings of the motor to a d-c electric power source that includes a filter capacitor. Cyclically operative means provides periodic gating signals for alternately turning on and turning off the chopper, and it can be smoothly changed from a constant frequency, variable pulse width mode to a variable frequency, constant (minimum) off time mode so as to vary the "duty factor" of the chopper over a wide range extending up to 100 percent on time. Brake set up means is operative in response to a motoring-to-braking command for reconnecting the chopper in parallel with the motor and the filter capacitor and for reversing the polarity of the connection of the series field winding relative to the armature.

Abstract: A pulse shaping and amplifying circuit is formed by connecting a capacitor in series with the primary winding of a pulse transformer, connecting normally open switching means in parallel with the capacitor and primary winding, and connecting this parallel combination through a series inductor to a source of d-c control power, whereby the capacitor accumulates a charge from the control power source and then, during periods when the switching means is closed, discharges through the switching means and the primary winding. During its closed periods the switching means also conducts current from the control power source through the inductor, but when the switching means is opened the current in the inductor is transferred to the capacitor and the primary winding and thereby assists recharging of the capacitor.

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 method and apparatus for controlling the phase retard time of a phase-controlled rectifier circuit in a power conversion system wherein a clock-pulse synchronized alternating voltage source is connected to supply power to the phase-controlled rectifier circuit. The clock pulses controlling the voltage source are detected and delayed for a predetermined time interval prior to their application to the voltage source. A ramp voltage generator synchronized to the clock pulses and a comparator circuit for comparing the ramp voltage signal level to a reference level provide a means for generating gate pulses to control the phase retard time of the phase-controlled rectifier circuit between maximum and minimum retard times. Maximum retard time is established at the occurrence of a clock pulse by applying a gating signal to the rectifier circuit if the rectifier circuit has not been triggered prior to detection of the clock pulse.