Abstract: An example method of using a servomechanism can include controlling a reversible positive displacement pump that is located in a first chamber of a housing to push a fluid, via a first passage in the housing, against one side of a vane that is rotably disposed in a second chamber of a housing to rotate an output shaft that is coupled to the vane and controlling the reversible positive displacement pump to push a fluid, via a second passage in the housing, against another side of a vane to reverse rotation of the output shaft.

Abstract: A method and apparatus to provide a very compact and low power measurement of vehicular (automobile) exhaust emissions with results similar to those obtained with traditional CVS dynamometer lab emissions equipment. The sample dilution necessary for the analysis is performed by a computer controlled PWM valve as a function of measure exhaust mass flow, with the result that a "mini CVS" is accurately performed on a small fraction of the total exhaust flow.

Abstract: A feedback circuit prevents clipping of the inverter drive signals for a polyphase induction motor. The circuit senses the electromotive force (e.m.f.) of the motor and regulates the slip frequency as a function of the difference between the sensed motor e.m.f. and the DC power supply voltage. When the motor e.m.f. approaches the supply voltage, a voltage controlled oscillator adjusts the slip frequency to reduce the motor e.m.f. and thereby ensure that the motor drive waveforms are not distorted.

Abstract: A method of fabricating rotors for induction motors. In a first aspect, arcuately spaced apart rotor bars pass through channels the magnetic core of the motor. The rotors are formed of an elongate portion having a constant cross section parallel to the magnetic core laminations and include two portions protruding beyond the end laminations at opposite ends of the magnetic core. The protruding portions are, at one end, a head much like the head of a "T", and at the other end, a straight continuation of the elongate portion. The rotor bars are formed to fit closely with one another in an interleaving arrangement. The protruding portions form an end ring assembly which is subjected to a consolidation process. In this way, for a rotor having N rotor bars, there will only be N braze joints in each end ring.

Abstract: The present invention pertains to an improved rotor bar design and method of fabrication of asynchronous motors using such rotor bars. The rotor bar design employs "T"-shaped rotor bars that are interleaved around a magnetic core forming a rotor having a minimum amount of bonding interfaces between the rotor bars and end ring portions. The "T"-shaped rotor bars may either be formed from a single piece or from multiple pieces of copper. The single piece rotor bar method provides N bonding interfaces per end ring, where N is the number of rotor bars used. Where the "T"-shaped rotor bars are formed from three pieces for a rotor having N rotor bars, there will be 2N bonding interfaces for each end ring. Also, the "T" shape of the rotor bars may be added after straight rotor bars have been installed in the rotor bar channels in the magnetic core with their end portions extending beyond the rotor bar channels.

Abstract: A circuit generates phase pole command signals for controlling operation of an induction motor. To minimize instabilities occurring within the motor, a stability control circuit generates a phase shift signal, which is input to reference signal generators to adjust phase reference signals. When in a motoring mode, the phases of the reference signals are advanced monotonically with respect to the electro-motive force of the induction motor. When in a regeneration mode, the phases of the reference signals are decreased monotonically with respect to the electro-motive force. The resulting adjustment to the phases of the reference signals minimizes instabilities within the feedback control of the induction motor.

Abstract: A combined battery recharge and motor drive system employs an essentially conventional polyphase pulse width modulated (PWM) inverter and a polyphase motor which may be reconnected to operate in a battery recharge mode. Single phase or three-phase AC power from an external source is applied across the reconfigured circuit, and the inverter switches are then controlled to operate as a boost switching regulator. Electrostatic (Faraday) shielding techniques and construction allow extremely small ground currents for improved safety an GFI outlet compatibility.

Abstract: A drive and recharge system is disclosed that includes a bidirectional dc power source, two voltage-fed inverters, two induction motors, and a control unit. In the drive mode, power is bidirectionally connected between the dc power source and the motors. In the recharge mode, single-phase power applied to the neutral ports of the two motors is converted with unity power factor to return energy to the dc power source. An alternate scheme is also presented which uses a single motor having two sets of windings.

Abstract: An electrical component assembly includes a printed circuit board with a plurality of power transistors mounted in parallel, spaced-apart rows, a longitudinally-extending heat sink, and a longitudinally-extending leaf spring that presses the transistors into contact with the heat sink, thereby providing heat conduction from the transistors to the heat sink. The assembly is provided by placing two parallel rows of transistors between two parallel, spaced-apart walls of the heat sink, sliding two longitudinally-extending leaf springs into the space between the rows of transistors, and then inserting a longitudinally-extending spring spacer between the two leaf springs. The spring spacer compresses the leaf springs against the power transistors, urging the transistors into heat-conducting contact with the walls of the heat sink.

Abstract: A method and apparatus is disclosed for detecting an impending saturation in nonlinear magnetic material for particular operating conditions, such as in a core of a power transformer T.sub.1 of a switched-mode converter, in response to a varying magnetic field in a principal direction induced by a drive current through its primary winding with its axis aligned in the principal direction. A transverse flux sense winding (20) is used in monitoring the rate of change of flux density of a transverse magnetic field to produce a voltage proportional thereto. That voltage is compared in a comparator (22) with a predetermined threshold voltage characteristic of impending saturation of the core. The output of the comparator is used for controlling drivers (25) to prevent saturation of the switched-mode converter bias switching the drivers off alternately when the sensed voltage reaches the predetermined threshold set at the comparator (22).