Abstract: A method for measuring capacitance in a power conversion system by measuring the time rate of discharge of the capacitance means and computing the value of capacitance corresponding to the measured discharge rate and a method for verifying that a filter in the power conversion system is effective for suppressing preselected frequencies corresponding to signalling frequencies used in a transit system. In this latter form, the system periodically initiates a self-test function in which the preselected frequency is injected into the system for verifying that the system will detect signals at the preselected frequency.

Abstract: In an electrical propulsion system on board a moving traction vehicle (such as a rapid transit rail car) having current collectors in contact with an energized third rail, controllable switch means is used to connect the system to the current collectors. From time to time the current collectors traverse gaps between adjacent sections of the third rail, in which event regenerative braking operation of the system will be prevented unless the next third rail section is energized by a wayside source of voltage. The switch means comprises the parallel combination of a diode that conducts current when the system is operating in a motoring mode and a reversely-poled thyristor that conducts regenerative braking current once a firing signal is applied thereto.

Abstract: A system and method for controlling power transfer between an internal combustion driven electrical power generator and a direct current (DC) motor. In one form, the invention includes control of a power inverter in a manner to restrict current through a winding of the generator to a predetermined polarity. The inverter includes a plurality of gate controlled switching devices which are selectively energized to allow current to free wheel through the motor during at least some portion of each alternating voltage cycle of the generator. In another form, a plurality of resistors are connected in series with an inverter and a DC motor with each resistor including a switching device for bypassing current around the associated resistor. In this form, resistors can be selectively inserted into the series path during electrical braking so that a maximum amount of electrical energy can be transferred to the generator through the inverter without exceeding the voltage limits of the inverter during high speed braking.

Abstract: An alternating current (AC) motor system includes an AC motor having a rotor and a stator with the rotor having a plurality of air passes for passing cooling air and the stator having end windings extending from each end. An air deflector is coupled to one end of the rotor and has a generally curved configuration for directing cooling air exiting the air passages into a generally radial flow direction and onto the stator end windings. The stator end windings comprise turns of a plurality of electrical conductors forming the stator winding circuits which are wound to form a plurality of phase windings. Controllable switches are connected to the winding circuits for coupling the phase windings into either a parallel or series circuit arrangement. The system is responsive to motor speed and operating state for selectively switching the windings between the series and parallel electrical circuit arrangements.

Abstract: An electric propulsion system for a traction vehicle includes a controllable power converter operable in either a propulsion or an electric braking mode in which power is withdrawn from a wayside source or returned to the source, respectively. The wayside source utilizes certain preselected frequencies for power generation and for signaling. It is desirable to detect these frequencies quickly and to be able to disconnect the vehicle from the source if some frequencies are being generated by the vehicle and others are not present on the system. Bandpass filters are coupled to the power converter to detect the preselected frequencies. Wayside transients sometimes encroach on these frequencies with large power spikes causing ringing of the filter circuits and delay in detecting the preselected frequencies. The system includes an active power limiter for limiting the peak amplitude of the signals coupled to the filters without interfering with the signal frequency content or affecting filter operation.

Abstract: Apparatus and method for auto-self testing of a power converter and motor system wherein the power converter has three parallel legs, each including two series connected gate-turn-off thyristors (GTO) connected between a pair of DC power source buses. A microprocessor controls the test sequence in which each GTO is individually turned on in a predetermined order so as to create a transient snubber current through the motor and through each GTO when it is turned on. The snubber current and a voltage in each leg is measured and compared to a respective reference to detect wiring errors, and defects in the motor, the GTOs, and other system components. Error messages are generated in response to detection of abnormalities or defects.

Abstract: A method for measuring capacitance in a power conversion system by measuring the time rate of discharge of the capacitance means and computing the value of capacitance corresponding to the measured discharge rate and a method for verifying that a filter in the power conversion system is effective for suppressing preselected frequencies corresponding to signalling frequencies used in a transit system. In this latter form, the system periodically initiates a self-test function in which the preselected frequency is injected into the system for verifying that the system will detect signals at the preselected frequency.

Abstract: A method and system for calibration of a primary signal processing path without interruption of signal processing utilizes a calibration signal processing path which is periodically used to process a signal concurrently with processing in the primary path. Any difference is compensated by gain adjustment in the primary path. In one form, a plurality of primary paths are sequentially compared with a calibrated path. The calibrated path is periodically checked using a precision reference and any error is corrected before comparison of the primary paths.

Abstract: An improved electrical circuit configuration for a chopper circuit is disclosed which is particularly adapted for use with an inductive load such as a braking resistor of the type used in many rapid transit vehicles. Instead of connecting a di/dt reactor directly in series with the electronic switch of the chopper circuit, a di/dt reactor is connected in series with the freewheeling diode. Using this configuration, the di/dt reactor does not have to continuously handle the average current through the electronic switch during the entire chopping operation. Hence, a much smaller, lighter, and less expensive di/dt reactor can be utilized.

Abstract: A method for determining operability of a dynamic braking system in an electrically propelled traction vehicle by cycling selected switching devices while the vehicle is at rest and measuring voltages and currents generated in response to operation of the switching devices. In one form, the dynamic braking system is operated to be connected to a power conversion system of the vehicle and the voltage developed at the braking system compared to the voltage coupled to the vehicle. Using prior knowledge of system resistances, calculated ideal values of voltage are compared to measured values to confirm proper system operation. Malfunctions of particular components are logically determined by ratios of measured to ideal values and by operation of selected ones of the switching devices.

Abstract: An improved electrical circuit configuration for a chopper circuit is disclosed which is particularly adapted for use with an inductive load such as a braking resistor of the type used in many rapid transit vehicles. Instead of connecting a di/dt reactor directly in series with the electronic switch of the chopper circuit, a di/dt reactor is connected in series with the freewheeling diode. Using this configuration, the di/dt reactor does not have to continuously handle the average current through the electronic switch during the entire chopping operation. Hence, a much smaller, lighter, and less expensive di/dt reactor can be utilized.

Abstract: In an electric power converter comprising at least one pair of serially-connected, alternately conducting controllable electric valves spanning a pair of d-c conductors, the conducting state of each valve is detected by comparing the actual magnitude of valve current with a predetermined low threshold level and by comparing the difference between the juncture potential of the two valves and a reference potential of one of the d-c conductors with the potential diffence between both d-c conductors. If both comparisons indicate the valve is in a conducting state and if this state is indicted concurrently for both valves, logic means is operative to indicate that a "shoot through" fault has occurred. In this abnormal event, whatever turn on and turn off signals for the two valves were extant at the time such operation of the logic means commenced will be prevented from changing while both valves are conducting.

Abstract: To increase the output voltage of a conventional rectifier bridge, one winding of an autotransformer is connected across a pair of a-c input terminals of the bridge through a thyristor which is turned on only when an output voltage increase is desired, and an extra diode is used to connect the other autotransformer winding to one of the d-c output terminals so that the boost voltage induced in the latter winding is added to the input voltage.

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: A rotatable member having multiple discrete positions between opposite ends of a normal path of movement is provided with two (or three) parallel, encoded tracks having different patterns of distinct, serial sections. These tracks cooperate with relatively stationary probes of a position sensor. As the rotatable member moves from position to position, the sensor will produce a family of two (or three) separate binary signals that changes states as the probes detect boundaries between successive sections of the tracks with which they respectively communicate, and the patterns of the encoded sections are so selected that the sequence of state changes when the rotatable member is approaching a predetermined mid position will differ from the sequence when the member is moving away therefrom.

Abstract: To detect any abnormal loss of a feedback signal in an electric power system wherein a plurality of feedback signals are respectively derived from various system quantities, such as voltage and current, and are used as inputs to a controller that regulates the output of a controllable source of power, the controller is arranged to estimate the desired value of the system quantity from which a first feedback signal is derived, to compare the estimated desired value with the actual value of the same quantity (as indicated by the first feedback signal), and to signal a malfunction if this comparison reveals that the first feedback signal is faulty.

Abstract: The propulsion control system of a diesel-electric locomotive includes means responsive to the rotational speed and the gross horsepower of a locomotive engine for controlling the rate at which traction load is added to the engine, when more load is called for, so that the loading rate will increase (between predetermined minimum and maximum limits) as the product of speed and horsepower increases. The loading rate is also increased in response to the ratio of combustion air to diesel fuel increasing above a predetermined no-smoke threshold.