Abstract: An apparatus including a frame, where the frame includes a user handle, a motor receiving area, and a first aperture through the frame into the motor receiving area, where the motor receiving area is configured to removably receive a cannulated motor assembly therein; and a first seal located proximate the first aperture through the frame, where the first seal is configured to form a seal between the cannulated motor assembly and the frame when the cannulated motor assembly is in the motor receiving area.

Abstract: Medical systems and methods for making and using medical systems are disclosed. Example medical systems may include an atherectomy system configured to engage and remove plaque from walls in vessels of a vascular system. The atherectomy system may include a drive shaft, a rotational tip coupled to an end of the drive shaft, a motor coupled to the drive shaft to rotate the rotational tip, and a controller configured to control a motor state of the motor. The controller may adjust a range of possible load outputs from the motor and/or a maximum load output from the motor to account for external loads acting on the drive shaft and/or rotational tip rotated by the motor and facilitate passing an occlusion in a vasculature of a patient.

Abstract: An endoscope and related method comprise a proximal handle and a distal shaft having an insertion end. A housing comprising a camera assembly may be mounted on an insertion end of the shaft and include at least one lens and an image sensor. The camera assembly housing is rotatable about an axis perpendicular to the long axis of the shaft, giving the camera assembly a variable field of view. The rotatable camera assembly housing may be mounted to the insertion end of the shaft so that the rotatable housing of the camera assembly comprises the distal-most element of the endoscope shaft or insertion end. The endoscope may include a circuit board having a first portion disposed within the proximal handle and one or more extension portions that extend within the shaft to the camera assembly and/or to a light source near the distal end of the shaft.

Abstract: A medical manipulator system includes an operation unit that has motors, a composite input unit and a tip operating unit that is operated by a driving force of the motors, a working unit that may by attached to and detached from the operating unit, and a console. The motors are driven based on an input operation to the composite input unit. The tip operating unit performs at least a rotation operation along an axial direction or a swing operation that crosses the axial direction. The console changes a driving speed of the motors and includes a speed setting unit that changes an operating speed of the rotation operation or the swing operation of the tip operating unit.

Abstract: An alternating current rotating machine control device that shares information among power conversion devices and instruments. A power conversion system has a top level control device, a master station, multiple power conversion devices, instruments (such as a temperature sensor and a pressure sensor), and the like. The top level control device is connected to two of the power conversion devices by a first communication line. These power conversion devices have two or more communication functions, and are connected to a remaining power conversion device, a temperature sensor, and a pressure sensor by a second communication line.

Abstract: A method for estimating a torque of a three-phase motor for a vehicle includes measuring a respective current strength in at least two of three phase lines, wherein the three-phase motor is supplied with power by a converter, and wherein the three phase lines lead from the converter to the three-phase motor of the vehicle, measuring a respective voltage at each of the three phase lines, determining a rotating field frequency as a function of the measured current strengths or the measured voltages; and determining an estimated value for the torque as a function of the measured current strengths, the measured voltages and the determined rotating field frequency.

Abstract: A motor control device has a motor driving unit that drives a motor, a current detecting unit that detects a motor current flowing through the motor, a control unit that compares a detected current value of the motor current detected by the current detecting unit with a target current value to obtain a deviation, to control the motor driving unit based on the deviation, and a compensation unit that sets as a current offset value a detected current value of a drift current detected by the current detecting unit in a state where the motor current is regarded as zero, to compensate the detected current value of the motor current by the current offset value. The compensation unit sets a target offset value according to the current value of the detected drift current to correct the current offset value stepwise until the current offset value reaches the target offset value.

Abstract: A sterilizable surgical power tool and an operating unit for the surgical power tool are described. The operating unit includes a hermetically sealed metal capsule for arrangement in the region of a housing of the surgical power tool, the capsule having a contact surface for a finger on an outer face. A force sensor which is in force-transmitting connection to the contact surface is arranged inside the capsule. At least one electrical contact leads out of the capsule. The capsule may be a low-cost standard transistor housing.

Abstract: Described herein is a drive arrangement for the motor-driven adjustment of an adjustable element in a motor vehicle, the drive arrangement having two electrical drives and a control device, the drives, in the fitted state, acting in the same way on the adjustable element and having a substantially identical configuration, apart from tolerance-related discrepancies. The control device has a power controller which, in the fitted state, during the motor-driven adjustment of the adjustable element, subjects the electrical power that is output respectively to the two drives to closed-loop control, for the purpose of compensating for the tolerance-related discrepancies, in such a way that an identical electrical power consumption is established for both drives.

Abstract: An apparatus and method for protecting a power system comprising a generator providing power to an alternating current bus, a power converter for converting alternating current power on the alternating current bus to direct current power on a direct current bus, and a direct current load powered by the direct current power on the direct current bus. An undesired condition is identified at the input to the power converter from the alternating current bus. The undesired condition is caused by at least one of the power converter, the direct current bus, or the load. The power converter is disconnected from the alternating current bus in response to identifying the undesired condition for at least a time delay. The time delay is selected such that the power converter is disconnected from the alternating current bus before the alternating current bus is disconnected from the generator due to the undesired condition.

Abstract: An alternating current-to-direct current (AC-to-DC) power supply has a first stage providing a first DC voltage and a second stage providing a second DC voltage. The AC-to-DC power supply has a first efficiency at the first stage and a second efficiency at the second stage that is less than the first efficiency. The second DC voltage is also less than the first DC voltage. A blower is electrically connected to the first stage of the AC-to-DC power supply to receive the first DC voltage from the AC-to-DC power supply to power the blower. Electrical connection of the blower to the first stage of the AC-to-DC power supply instead of to the second stage of the AC-to-DC power supply wastes less power and is more efficient.

Abstract: A precharge circuit (20, 20?, 20?) charges at least one capacitor (22, 22?, 22?) associated with an electrical device with high capacitance, such as a motor (14) which drives a compressor (16) of the pneumatic system. One end of the at least one capacitor is connected with a high voltage bus (10). The other end of the at least one capacitor is connected by at least one charge limiting resistor (24, 24?, 24?) with a low reference node. When the at least one capacitor is charged at least to a preselected level, a control circuit (28, 28?, 28?) controls a switch (26, 26?, 26?) to bypass the current limiting resistor. In this manner, the current limiting resistors limit the surge current to charge the capacitors. Once the capacitors are charged, the resistors and their associated heat dissipation are removed from the circuit and only ripple current from across the capacitors flows through the switch reducing a required current carrying capacity and needed heat sinking for the switch.

Abstract: Included herein is a system and method for controlling a velocity vector of an overhead crane. A motor is attached to the crane and is positioned to move the overhead crane and has an output vector including a rotational direction and a rotational speed. A variable frequency drive is positioned to transfer voltage and current at a frequency to the motor. A processing unit converts the output vector to an amount of voltage and current at a given frequency and can instruct the variable frequency drive to send a frequency to the motor at a frequency substantially equal to the frequency at which the motor is presently rotating. This creates a speed match for the motor reducing spikes during operation of the motor and substantially eliminates open circuit decay. A hydraulic brake operates in connection with the processing unit and the variable frequency drive to slow the crane without driving the motor into the brake.

Abstract: An apparatus and method for controlling a linear compressor is provided. The linear compressor controlling apparatus includes a voltage detection unit, a current detection unit, a control unit and a compressor drive unit. The voltage detection unit detects a voltage supplied to the linear compressor, while the current detection unit detects a current supplied to the linear compressor. The control unit determines whether a collision of a piston of the compressor with a valve of the compressor occurs using output signals of the voltage and current detection units, and controls the amplitude of the piston if the collision of the piston with the valve occurs. The compressor drive unit controls the amplitude of the piston under the control of the control unit.

Abstract: By controlling all motors so that they all decelerate at substantially the same rate, buckling of media in a media handling system is substantially eliminated on shutdown. Preferably, the deceleration rate of the highest inertia motor is used as the common deceleration rate.

Abstract: A washing machine motor drive device drives a motor using an inverter circuit, which implements a constant torque control through a change in the torque-revolution speed characteristic of the motor. This facilitates an easy control of braking torque (negative torque), thereby providing a maximized braking torque. An easy control of regenerative energy is also provided, and back electromotive force is consumed by the internal resistance of the motor. Practically described, DC power of a rectifier circuit connected to an alternating current source is converted by an inverter circuit into AC power for driving the motor for operating an agitator or a washing/spinning tub. Motor rotor position is detected by rotor position detector, motor current is detected by current detector, and a control device controls the inverter circuit for resolving the motor current into a current component corresponding to magnetic flux and a current component corresponding to torque.

Abstract: A method for measuring the current in each phase of a three-phase motor (26) by the sensor (32), the motor (26) being controlled by a plurality of switching devices (S1-S6) that receive pulse width modulation signals from a controller (34). In one embodiment, a first and second sampling window (t1 and t2) are monitored. When both the first and second sampling windows (t1 and t2) are less than a minimum sampling window (mw), the voltage pulse trains associated with the highest output (V_h) and the lowest output (V_l) are shifted to form a first modified sampling window (t1′) and a modified second sampling window (t2′). When the first sampling window (t1) is less than the minimum sampling window and the second sampling window (t2) is greater than the minimum sampling window (mw), then the voltage pulse train associated with the highest output (V_h) and/or the middle output (V_m) may be shifted to form the first and second modified sampling windows (t1′ and t2′).

Abstract: A N pulse variable frequency drive for driving two or more motors that is the combination of two or more variable frequency drives with each drive driving an associated one of the two or motors. One application is a decanter centrifuge which has a main motor to drive the bowl and a back motor to drive the conveyor. One of the two variable frequency drives drives the main motor and the other drive drives the back motor. The variable frequency drives are connected to a common buss and to a N pulse phase shifting transformer.

Abstract: An exemplary embodiment of the invention is a method for detecting a potentially locked axle on a vehicle propelled by an AC motor. The method includes conducting a speed test by estimating axle speed and comparing estimated axle speed to measured vehicle speed. The existence of a potential locked axle condition is determined based on the comparing of estimated axle speed to measured vehicle speed. Additional tests are disclosed for determining a potential locked axle condition and a sensor fault condition.

Abstract: A torque controller system provides improved torque distribution as a function of wheel diameter size in a vehicle propelled by electric traction motors. The system includes one or more torque processors each having a multiplier coupled to receive an input signal and configured to produce an output signal which is the product of the input signal and a variable multiplier value generated by a respective torque distribution generator based on a predetermined torque distribution control function.

Abstract: A method and apparatus for reducing winding failures in electric machines resulting from the application of high frequency or high dV/dt voltage pulses or voltage signals to the phase windings of the machine in which an inductive element is provided between the source of the high-frequency or high dV/dt pulses and the phase winding to absorb a portion of the voltage stresses on the phase windings that result from the application of the high-frequency or high dV/dt pulses to the machine.

Abstract: A surgical power tool is disclosed including a power console and a handheld motor unit. The power console provides controlled power and to the handheld motor unit. Pressure sensitive switching elements on the handheld unit provide signals to the power console which are transformed into operating power to the motor unit including variable speed, speed range, forward/reverse, and safety. The handheld motor unit includes a chuck or tool receptacle and a Hall effect or other radiation field detector which response to the presence of a magnet or other radiation device as a part of the surgical tool, to identify the tool installed and provide a control signal to the motor, e.g., speed range limitation. The handheld motor unit housing is sealed and autoclavable.

Abstract: A system and method for evaluating the effectiveness of a tractive effort maximizing control system in a wheeled vehicle utilizes a process of operating the vehicle by applying controlled power to at least some wheels of the vehicle to enable motion of the vehicle, disabling the tractive effort maximizing control system, and varying creep speed between a minimum value and a selected maximum value while monitoring the tractive effort to identify a maximum available tractive effort. Thereafter, the tractive effort maximizing control system is enabled and the resulting tractive effort developed by the vehicle measured. Comparing the resulting tractive effort to the maximum available tractive effort produces a measure of effectiveness of the tractive effort maximizing control system.

Abstract: In a motor vehicle driving system comprising several asynchronous electric machines (11, 12) each coupled to a driving wheel (13, 14), a polyphase supply device (2) and a regulating device (6) using a reference signal (SR) representative of a speed of one of the driving wheels, the invention provides a method and a device allowing an optimum electric supply to be assured when one or more of the driving wheels skid in drive mode or locks in the event of braking. For each driving wheel, a measured speed signal (NM1, NM2) is processed in a detection unit (23, 24) which detects skidding or locking and delivers binary skid (P1, P2) and locking (B1, B2) signals and a corrected speed signal (NC1, NC2) representing, as required, the speed prior to skidding or locking. A selection unit (25) selects one of the corrected speed signals as reference signal. Applications to electric or hybrid-powered vehicles.

Abstract: A traction control system for an ac locomotive optimizes traction performance by separately controlling the allowable creep level of each individual axle and by minimizing torsional vibration per axle. The traction control system includes a torque maximizer and a torsional vibration detector. The torque maximizer measures traction system performance levels and determines the desired torque maximizer state for maximizing traction performance of each individual axle. The torsional vibration detector digitally processes estimated torque feedback of each traction motor in order to detect an unacceptable level of torsional vibration. The outputs of the torque maximizer and the torsional vibration detector are provided to a creep modulator which processes these inputs in order to control the operating creep level of each locomotive axle. As a result, traction performance is improved while minimizing torsional vibration and operating noise levels due to wheel/rail squeal.

Abstract: An apparatus for controlling a surgical device includes a housing and a magnetic switching element mounted on the housing. The magnetic switching element includes a magnet, a magnetic sensor configured to produce a control signal for controlling the surgical device, and an actuator mounted on the housing for movement between a first position in which a magnetic field of the magnet is decoupled from the magnetic sensor and a second position in which the magnetic field is coupled to the magnetic sensor so as to change a value of the control signal produced by the magnetic sensor. The magnetic switching element may also include magnetically soft material positioned so that movement of the actuator causes relative movement between the magnet and the magnetically soft material.

Abstract: A system having two or more A.C. motors driving the same load. The stator windings and rotors of both motors each conduct current having a vector representative of a magnitude and angular position of the current in the respective rotor and stator winding. Stator current sensors are provided for producing an indication of the magnitude of the stator current vector to each motor. Encoders are provided for sensing the rotating speed of each of the rotors from which can be calculated the angular position of the rotor load current vector with respect to the rotating stator flux current vector. A first torque control controls the magnitude of the stator current of a first one of the motors such that the stator flux current vector of the first motor and the rotor load current vector of the first motor are angularly separated by 90.degree.. This angular relationship produces maximum torque at the rotating speed of the first motor.

Abstract: A traction enhancing system detects and corrects wheel slip and enhances wheel traction in a railroad locomotive having a plurality of wheel pairs for engaging a pair of rails and a traction motor operatively associated with each wheel pair. The locomotive includes an electrical source responsive to an applied level of excitation and is operatively coupled to the traction motors for controlling the power applied thereto. The traction enhancing system includes a plurality of current measuring devices adapted to measure current drawn by each traction motor, and a plurality of voltage measuring devices adapted to measure a voltage of each traction motor. A computer receives the current and voltage measurements and is configured to detect wheel slip between the wheel pairs and the rails by calculating a change in the current and voltage measured over a predetermined period of time.

Abstract: The invention relates to apparatus for controlling a plurality of electric motors. The apparatus includes drive means for applying electrical power to the motors at a predetermined current or voltage. Sensor means are provided for sensing the load on each motor. Comparator means, which include polarity detection means for generating at least one polarity signal representative of the combined polarity of the loads, and summing means for deriving a magnitude signal representative of the loads, are used to determine the relative magnitudes of the loads. Control means are arranged to generate a compensation signal which is applied to the drive means to reduce the power applied to the more heavily loaded motor or motors. The control means typically includes switching means responsive to the polarity detection means for determining the polarity of the magnitude signal, thereby to obtain the compensation signal. The invention extends to a method of controlling a plurality of electric motors.

Abstract: The present invention relates to a current supply control apparatus capable of actuating a large inductance load at a low electric power source voltage and also capable of improving a responsibility in a current supply control of the inductance load. When a detecting voltage of an absolute value circuit (10) representing a current value flowing in an exiting coil (1), provided as an inductance load, exceeds a standard voltage, transistors (3a, 3b) interposed between a DC electric power source (2a, 2b) and the exciting coil are turned off, and a magnetic energy stored in the exciting coil is utilized to charge a capacitor (5) up to a high voltage so that a current flowing after the transistors have been turned off is quickly reduced.

Abstract: A drive system with slip control for railway vehicles with two or more dc drive motors and with common control of the motor armature currents and a logic unit to which are input a measured signal which indicates the armature current intensity of the motor driving the axle having the best adhesion which is usually the trailing axle motor. The measured signal and an amplification signal are multiplied by each other and the product signal issued in a feedback loadsharing system to control the other motors such that the torque of the other motors increased to a maximum allowed level, the trailing axle then rolling very close to ground speed without slipping. This speed is used as a measure of the true speed, which in turn controls the system for loadsharing such that the vehicle can be controlled to maximum tractive effort without causing slipping axles.

Abstract: An apparatus for controlling the speed of a plurality of DC motors, comprises a device for supplying voltage to one of the plurality of DC motors, first selector for selecting one of the DC motors to be connected to the device for supplying voltage, second selector for selecting a desired speed for the selected DC motor, a device for producing a feedback signal representative of an electrical current drawn by the selected DC motor and a controller for: (i) producing a reference voltage in response to the first and second selectors (ii) producing a load voltage in response to the feedback signal and (iii) outputting a control signal which is the sum of the reference voltage and the load voltage to the device for supplying voltage so that the selected DC motor is operated at the desired speed.

Abstract: A locomotive propulsion system includes wheelslip control with the following interrelated features: comparing the rotational speeds of the locomotive's separately driven wheels and detecting the highest and lowest; providing a reference speed value indicative of the rotational speed of a wheel that is not slipping; determining a desired maximum difference between the reference speed and a selected one of the detected speeds; deriving a speed error value by summing the reference speed, selected speed, and maximum difference; obtaining a wheelslip correction value which is a function of the speed error value; reducing the magnitude of voltage applied to the locomotive's traction motors in accordance with the correction value.

Abstract: A brushless DC motor useful as a driving source of a refrigerant compressor of a refrigerating apparatus or a fan. A position detecting means generates a control signal by detecting the terminal voltage on input-output terminals current to three-phase rotor drive coils. Filters convert the detected terminal voltages to smoothed signals. A mixing means generates three kinds of mixed signal from the smoothed signal and comparing means generates the control signal for switching a current path to the three-phase coils by a signal made by comparing the mixed signal with the smoothed signal. The current path to the coils is switched by a switching-driving part in turn on the basis of the control signal of the position detecting means.The present invention provides a brushless DC motor wherein current flowing to the drive coils can be switched without special position detecting elements.

Abstract: A DC voltage on an electric car stringing is supplied to a variable voltage and variable frequency PWM inverter so as to be converted into a three-phase alternating current which is supplied to a plurality of three-phase induction motors. The motors are connected to different wheels to drive an electric car. The inverter is controlled on the basis of an operating frequency command determined by adding or subtracting a slip frequency command to or from a motor speed and a voltage command proportional to the operating frequency command. On the other hand, a motor current command is set and compared with a maximum current value of currents of the plurality of motors, and the slip frequency command is corrected in accordance with a difference therebetween.

Abstract: In a control system for a power converter for driving induction motors, the control system separately controlling an exciting current component of the primary current of the induction motors contributing to generation of a magnetic flux and a torque current component of the primary current contributing to generation of a torque, a voltage detecting device detects the output voltage of the power converter, and a correcting device responds to the voltage detecting device for determining a current correction for correcting at least one of the exciting current component and the torque current component to reduce the difference of the detected voltage from a reference value of the output voltage.

Abstract: A main circuit of an electric vehicle using an induction motor is constituted by an invertor for producing three phase AC power having a variable frequency and a variable voltage and a three-phase induction motor supplied with the AC power by the invertor. The rotational speed of the induction motor is detected and a slip frequency signal is added (in power running) or subtracted (in regenerating running) to or from the rotational speed to control the output frequency of the invertor. On the other hand, the output voltage of the invertor is controlled to be in proportion to the output frequency thereof. The output voltage of the invertor is limited in accordance with notch positions of a master controller of the electric vehicle so as to be provided with a voltage notch stopping characteristic of the conventional electric vehicle.

Abstract: An electric vehicle monitoring system in which one induction motor has a rotational speed detector but another motor does not have such a detector. Separate current detectors monitor the current delivered to each of the motors. A calculations circuit uses the rotation of the one motor and a comparison of the two currents to monitor the performance of both motors.

Abstract: In a system having a plurality of electric motors which are rated at different voltages, a voltage control circuit enables the electric motors to be connected to a common power supply. The voltage control circuit determines a first voltage appearing between the positive bus of the power supply and the motor and a second voltage appearing between the negative bus and the motor. One voltage is inverted and then summed with the non-inverted voltage to provide an average voltage. The average voltage is compared to a reference voltage and when the average voltage exceeds the reference voltage, a limit signal is generated. The limit signal is used to prevent higher voltages from being applied across the motor.

Abstract: A plural motor changeover control system for using a plurality of motors (1a, 1b), the power outputs of which differ, by successively switching among the motors. A conversion table (32a, 32b) corresponding to a motor designated for operation from among the plurality of motors (1a, 1b) is selected, and an amplitude command is fetched from the selected conversion table, which command corresponds to a velocity error, which is a difference between an actual velocity of the designated motor and a commanded velocity. The amplitude command is applied to the servo control circuit to control the designated motor.

Abstract: Apparatus for controlling wheel slip in a locomotive driven by d.c. motors which receive power from a diesel driven generator, has sensors which provide signals representing speeds of different driven wheels to a velocity unit. The velocity unit derives a differential signal representing the difference between the highest and the lowest wheel speeds. A sensor detects current or power in the generator output and the signal from this sensor is sampled periodically and the latest two sampled values are stored. The sampled values are compared to provide a creep reference signal. The differential signal and the creep reference signal are compared and the resulting difference signal is used to control generator output to maximize current during acceleration.

Abstract: In the propulsion system of an electric locomotive, a-c wayside power is converted to direct current for the traction motors by means of several phase-controlled rectifying bridges having serially connected outputs. The bridges are controlled sequentially so that their respective output voltages are introduced in stages as increasing amounts of voltage are required at the motors of an accelerating locomotive. Normally certain thresholds of speed need to be attained before the second bridge, and later the third bridge, are permitted to be phased on. Means is provided for changing the bridge control sequence in response to faults in the first or second bridges.

Abstract: In the propulsion system of an electric locomotive, a-c wayside power is converted to direct current for the traction motors by a plurality of phase-controlled rectifying circuits having serially connected outputs. To improve power factor, forced commutation means is provided for turning off the controllable valves in one of the circuits at a desired "extinction angle." This angle is varied with motor speed, but its effective range of variation is restricted so as to avoid undesired leading power factor at low speeds, to optimize power factor when the locomotive is running at full power, and to prevent misoperation when the level of load current is low.

Abstract: The propulsion control apparatus for a vehicle including a plurality of motor driven wheel units detects a slip or slide operation of at least one wheel unit in accordance with a predetermined difference between sensed motor currents, and reduces the tractive effort of those wheel units until the sensed motor currents no longer have that difference.

Abstract: The speed control circuit detects an actual and selected speed for the wheelchair and supplies power to the wheelchair motors in a manner which tends to bring the actual and selected speeds into conformity. A reference signal circuit detects a speed and direction selected by a joystick and produces a reference signal whose magnitude varies with the selected speed. The reference circuit includes a polarity circuit which detects the polarity of the reference signal to determine whether the motors are to be rotated in a forward or reverse direction. The voltage and current across the armature of the motor are both detected as measures of its actual speed. A comparing circuit compares the actual speed as determined by the armature voltage and current with the selected speed as denoted by their reference signal. Specifically, it subtractively combines the armature voltage and the reference signal to produce a first difference signal.

Abstract: A control system for an electric motor vehicle adapted to be driven by a group of induction motors, comprises a converter for producing an a.c. output to energize the group of induction motors, a frequency command circuit for producing a value representing a minimum number of rotations among those of at least two induction motors of the group added with a slip frequency in a power running mode of the vehicle on one hand and a value representing a maximum number of revolutions among those of at least two given induction motors of the group subtracted by the slip frequency in a regenerative braking mode, respectively, the values being utilized as frequency control commands, and a frequency control circuit for controlling the output for controlling the output frequency of the converter in dependence on the frequency control commands, thereby to improve the adhesion performance of the electric motor vehicle.

Abstract: A method and apparatus are described for regulating the armature currents of a plurality of electric motors connected to share the same load, but having separate power sources. The described method and apparatus thereby operate to enhance the load-sharing characteristics of these motors. Each of the motors is provided with armature currents by a separate generator set so that each motor is connected in an individual Ward-Leonard type system. The fields of each of the motors are excited separately from the aforementioned separate power sources. The armature currents for each of the motors are individually sensed, and values corresponding to the armature current values are derived. The latter analog values are compared with an average value for all of the armature currents.

Abstract: A variable speed, alternating current motor unit which operates continuously in a stepless manner and delivers full torque over a speed range from zero to maximum speed. The unit includes two induction motors which are mounted side-by-side in a housing. Each induction motor is a polyphase, squirrel cage induction motor with a rolled shell stator wound core and an associated rotor core. The stator elements are each equipped with a double shaft extension, and the rotor elements are also each equipped with a double shaft extension. The stator elements are suitably journaled in antifriction bearings which are mounted in the housing. The rotor elements are journaled in the housing in a similar manner. The stator elements are mechanically linked by a gear train so that rotation of one stator element opposes rotation of the other stator element when both of the induction motors are energized. Consequently, the stator elements buck one another and torque is induced in the rotor elements.

Abstract: A method and apparatus are disclosed for controlling the wheel slip of an electric or diesel electric locomotive such that optimum wheel adhesion may be attained. A certain characteristic of a series traction motor, specifically the back emf per rpm versus motor current (E/n vs. I), forms the basis for a voltage control which limits the voltage (V) supply to each motor to a value which will limit the maximum percentage wheel slip. The selected limit value of wheel slip is great enough to encompass the conditions of maximum adhesion under most rail conditions. By combining the E/n with the motor IR drop, motor current, and a locomotive speed signal, the idealized voltage V for a non-slip condition is derived. This voltage is increased by a factor representing the desired maximum percentage slip to obtain the limiting voltage which may be supplied to the motor.