Abstract: A new induction motor control method and system utilizes one more electric power inverters each supplying a separate induction motor with alternating current excitation power. The respective inverters preferably comprise auto-sequential commutated controlled current inverters. Direct current is supplied to each inverter in the system from a common direct current power supply preferably comprising a phase controlled rectifier circuit with individual current smoothing inductors connected in the direct current link to each power inverter for isolation purposes. A common operator controlled power level control module is provided for controlling the magnitude of the output current supplied from the common phase controlled rectifier to all of the inverters in parallel. Respective motor flux sensing means are provided for each induction motor for deriving individual feedback control signals representative of the flux developed by the respective induction motors.

Abstract: A new and improved motor control method and system wherein the frequency of the rotating electro-magnetic flux produced in an alternating current machine, is sensed and compared to a desired value of machine flux frequency to derive an output error control signal. The output error control signal is then applied to control the frequency of the alternating current supplied to the machine in a direction and by an amount necessary to zero any difference in the sensed frequency and the desired frequency of machine flux. In preferred embodiments the actual value of the electromagnetic flux produced across the rotor-stator gap of the motor, is sensed and used as the controlling criterion in the motor control system. The magnitude of the alternating current supplied to the motor is separately controlled in accordance with some other predetermined motor operating characteristics such as motor torque, load current, etc.

Abstract: An electrical contact brush having interposed in a central longitudinal slot an abrasive element which frictionally contacts the commutator surface at crests where the radius of curvature of the commutator is less than that of a concave contact surface preformed at the distal end of the brush but which does not contact the commutator at valleys where the radius of curvature of the commutator is greater than that of the brush contact surface, said element in operation mechanically reducing the average radius of the commutator at a rate faster than the rate at which the commutator surface is electrically eroded, thereby tending to maintain a true cylindrical commutator surface with uniform wear characteristics.

Abstract: A multi-axled traction vehicle is equipped with a plurality of means for sensing the speeds of its respective drive axles, and control means is provided for producing a predetermined warning signal if the sensed speed of any one of the axles is under a predetermined low threshold level. In addition, means is provided for disabling the control means if none of the sensed axle speeds exceeds a predetermined higher threshold level, thereby preventing the production of a warning signal when the vehicle is not in motion.

Abstract: A torque regulating alternating current induction motor control system comprising a motor flux sensing coil arrangement mounted on the induction motor stator for sensing the actual flux produced across the rotor-stator air gap of the motor and deriving a motor flux voltage signal proportional to the actual motor flux. An integrating circuit integrates the voltage signal to obtain a feedback sensed actual motor flux signal representative of the actual air gap flux. An actual torque feedback circuit converts the actual air gap flux and stator current signal to an actual value of torque feedback control signal. A first feedback control loop is responsive to the actual torque feedback control signal and a command value of torque signal and controls the frequency of operation of a power converter supplying the induction motor.

Abstract: An electrical propulsion control system for self-propelled earthmoving traction vehicles of the type having integral earthmoving means and having a prime mover-driven electric generator supplying energy to traction motors, wherein the electrical output of the generator is regulated within predetermined maximum limits which are reduced in response to the application of a predetermined lifting force to the earthmoving means.

Abstract: An electrical propulsion control system for self-propelled traction vehicles having an electric generator supplying energy to separately excited traction motors, each motor field being normally excited with a substantially constant field excitation providing magnetic saturation such that motor load variations produce minimal changes in back emf, and means for equally boosting the excitation of each motor field responsive to the largest one of the individual motor armature currents exceeding a predetermined magnitude which is greater than the maximum attainable armature current during dynamic retarding operation.

Abstract: An electrical propulsion control system for self-propelled traction vehicles of the type having a prime mover-driven electric generator supplying energy to traction motors and regulating means for maintaining the electrical output of the generator within desired limits, wherein the limit of generator output voltage is varied between zero and a predetermined maximum level as a function of desired vehicle speed.

Abstract: A flux sensing coil is installed in each phase of the motor stator, and the resulting induced voltages represent the rate of change of air gap flux in that phase. The output voltage signals are integrated, rectified and summed to obtain an average motor flux signal which is in turn applied to vary the voltage to the motor in such a manner as to maintain a substantially constant motor flux level. In this way control errors due to motor parameter changes are eliminated and the flux margin normally required in motor design is reduced to achieve a more efficient utilization of the motor.

Abstract: A portable unit comprising a tiltable accelerometer is mounted on a vehicle which is allowed to coast on a plane and a reading is taken to provide an indication of vehicle rolling resistance without regard to terrain, slope, vehicle weight or speed. By proper precalibration of the accelerometer, it is possible to obtain the coefficient of friction directly from the accelerometer reading. Other values which may be directly obtained from the output of the accelerometer when it is properly recalibrated include accelerating rate and braking rate of a vehicle and grade of terrain.

Abstract: An improved auto-sequential commutated controlled current inverter for driving a multi-phase load from a source of controlled magnitude direct current is disclosed. The auto-sequential commutated inverter comprises a plurality of parallel connected branch sub-circuits with each branch sub-circuit comprising at least one gate controlled power thyristor device connected in series circuit relationship with a respective power diode. The branch sub-circuits thus comprised are connected between a respective phase input to the multi-phase load and a common direct current power supply terminal for connection to the source of controlled magnitude direct current. A respective commutating capacitor is interconnected between the junctures of the power thyristor and power diode of each respective branch sub-circuit and the power thyristor and power diode of the next adjacent branch sub-circuit.

Abstract: An electrical propulsion control system for self-propelled traction vehicles of the type having a thermal prime mover-driven electric generator supplying energy to traction motors, wherein the electrical output of the generator is regulated within predetermined maximum voltage, current, and power limits and is independently reduced, without reducing the voltage or current limit, in response to the prime mover decelerating to speeds at which it is subject to bogging.

Abstract: In an electric propulsion control system for self-propelled traction vehicles having reversible, variable speed tractiOn motors, wherein the operation of a direction selector means overrides the normal speed controlling means and initiates a dynamic retardation operating mode so as automatically to decrease the speed of the traction motors, and means responsive to the motors subsequently decelerating to a predetermined relatively slow speed effects a reversal of motor energization so as to reverse the direction of the vehicle.

Abstract: After vacuum pressure impregnating an insulated coil with liquid polyester resin the outer surface of the combination is treated to cause a quick low temperature gellation of an outer shell of the resin to thereby encapsulate the remaining liquid portion. A subsequent high temperature cure is imposed for a relatively long period of time to solidify the liquid inner portion and to fully cure the resin throughout the insulation.