Abstract: An adaptive noise control system comprises a reference microphone (12) (FIG. 2) for generating a reference signal (x(t)) that is correlated with noise emanating from a primary noise source (10), secondary loud speaker sources (S.sub.1, S.sub.2, . . . S.sub.N) for generating a plurality of secondary sound waves, microphones (e.sub.1, e.sub.2, . . . e.sub.M) for detecting a plurality of far-field sound waves in a far-field of the primary noise source and generating a plurality of error signals (e.sub.1 (t), e.sub.2 (t), . . . e.sub.M (t)) each of which is indicative of the power of a corresponding far-field sound wave, and an adaptive controller (14) for controlling the secondary sources in accordance with the reference signal and the error signals so as to minimize the power in the far-field sound waves.

Abstract: Vibration of a system such as a motor and pump on a platform or a transformer is minimized by applying a compensating force to the system. The optimum compensating force is determined by measuring the initial vibration and using that measurement in one of three algorithms to determine an adjustment to be made to the compensating force applied to the system at the time the initial vibration was measured. The adjusted compensating force is applied to the system which changes the vibration. That vibration is measured and applied to the selected algorithm to determine a second adjustment to the compensating force. The process is repeated until a compensating force is found which produces zero vibration, minimum vibration or a desired vibration. A plurality of sensors for measuring vibration and a plurality of actuators for applying a compensating force are preferably used.

Abstract: A bidirectional variable reluctance linear actuator and force control system by which one or more bidirectional linear actuators can be operated to produce a linear relationship between the net force on the armature structure and an applied flux linkage variation signal, as well as an actuator system by which the transmission of vibration through a structure can be blocked by applying forces and/or moments to the structure so as to cancel out its vibratory velocity. An adaptive control system, which is synchronized to machine speed, is able to determine the proper forces that will cancel the vibration of the structure and automatically null out each harmonic of the structure vibration, and cancels the vibration in up to six degrees of freedom of structural motion. The system can provide active attenuation system with a variety of noise sources and transmission paths, i.e.

Abstract: A current fed unrestricted frequency converter (UFC) for supplying power with balanced voltages to a three-phase unbalanced load generates two sets of existence functions for controlling the switching matrices of the UFC to generate positive and negative sequence current components in the load. Existence function generators generating the positive and negative sequence existence functions are phase locked, respectively, to a positive sequence reference signal generated by a clock and a negative sequence reference signal derived by circuits which monitor the negative sequence voltage in the load. Select circuits alternately gate the positive and negative sequence existence functions to the UFC switching matrices in proportion to the detected magnitude of the negative sequence voltage in a sense to drive the negative sequence voltage in the load to zero.

Abstract: Apparatus and process for the selective cancellation of harmonic frequencies of current produced in a multiphase dynamic stabilizer. A plurality of multiphase dynamic stabilizers providing electrical stabilization are interconnected to a multiphase AC electrical network via a coupling transformer. The leakage reactances and turns ratios of the windings of the transformer are such that the phases of selected harmonic frequencies of current produced in each of the stabilizer means are rotated with respect to those of the other stabilizer means with the selected harmonic frequencies being substantially cancelled in each of the stabilizer means. The harmonics are not the cause of subsynchronous resonance. The cancelled harmonic frequencies are dependent upon the number of dynamic stabilizers used.

Abstract: The present invention discloses a modular reactor that increases the inductance per axial length by winding a conductor circumferentially about a central axis in a manner which results in radially extending columns which are sequentially wound in alternating radial order. The modules are constructed to allow them to be combined in either radial or axial juxtaposition and electrically connected either in series or in parallel.

Abstract: A voltage regulator is taught for maintaining the terminal voltage of a three phase transmission line at a fixed reference value. The voltage regulator system utilizes the reactance of the transmission line in conjunction with reactive current from a VAR generator to compensate for the voltage effect of line current as it flows through the line reactance. The VAR generator is of the parallel capacitor-inductor type where the inductor is controlled by a thyristor switch. The conduction of the thyristor is controlled by utilizing a control system which generates an error signal based on the half period average of line voltage. The error signal is converted to a signal which is proportional to flux linkages by an integrator and then compared with the integral of the voltage signal for determining the conduction angle of the thyristor switches.

Abstract: A dynamic stabilizer of the type which is utilized to compensate or stabilize the effect of subsynchronous resonance oscillations in a turbine generator system is taught. Silicon controlled rectifiers are connected in series with inductors between the lines of the electrical system. The silicon controlled rectifiers may be maintained at two quiescent conduction intervals of 90.degree. and 135.degree. depending upon the peak value of rotor oscillation. If the peak value of rotor oscillation is sufficiently small the lower conduction interval of 90.degree. is utilized as this is sufficient to stabilize low level oscillations. Furthermore, it has great advantage in the fact that the losses represented by 90.degree. quiescent conduction interval are relatively small when compared with the larger quiescent conduction interval.

Abstract: This concerns a compensator for electrical lines fed by a turbine-generator. The mechanical properties of the turbine-generator are such that modulation of the terminal voltage is possible due to subsynchronous mechanical torsional oscillations. If the carrier frequency or synchronous frequency of the generator minus the torsional oscillation frequency is equal to the resonant frequency of the electrical line driven thereby, a relatively large side band current may flow in the electrical line at the resonant frequency. The effect of this current may feedback through the air gap of the generator to increase the torsional oscillation. A boot strapping effect between the electrical properties of the line and the torsional oscillation may thus result which could ultimately end in shaft breakage.

Abstract: A control circuit for a static VAR generator measures load power during consecutive half cycles of the source voltage. This information, together with load voltage and load current information is used to determine the firing angles of the VAR generator thyristors for providing compensating current for keeping the source current in phase with the source voltage and for balancing the source currents in a three-phase electrical system. The total computation time for determining the firing angles extends into the half cycle in which correction is to be applied beyond a fixed minimum firing angle.

Abstract: A voltage regulator is taught for maintaning the terminal voltage of a three phase transmission line at a fixed reference value. The voltage regulator system utilizes the inductive reactance of the transmission line in conjunction with reactive current from a VAR generator to compensate for the voltage effect of line current as it flows through the inductive reactance. The VAR generator is of the parallel capacitor-inductor type where the inductor is controlled by a thyristor switch. The firing range for the thyristor switch is determined by a fast acting static control system which utilizes line-to-line voltage and line-to-ground voltage as an input. A signal related to the latter voltages is processed and compared against a reference. The integrated difference thereof is utilized to determine the firing angle for the thyristor switch.

Abstract: An automatic expansion valve for controlling refrigerant flow from a condenser to an evaporator in which the valve includes an apertured deflectable disc which defines the refrigerant expanson orifice with other structure within the valve, and with the flow passage arrangement in the valve body being such as to subject the upstream face of the disc to the pressure of the liquid refrigerant, and the downstream face of the disc to the pressure of the expanded vaporous refrigerant so that the disc deflects in accordance with the differential pressure on the opposite faces and accordingly effects changes in the effective opening of the expansion orifice.

Abstract: An automatic expansion valve for controlling refrigerant flow from a condenser to an evaporator in which the valve includes a deflectable member which defines a refrigerant expansion orifice with other structure within the valve, and with the flow passage arrangement in the valve body being such as to subject at least part of the opposite faces of the deflectable member to the different pressures resulting from refrigerant flow through the expansion orifice so that changes in the deflection of the deflectable member are in accordance with differential pressure across the orifice and accordingly effects changes in the effective opening of the expansion orifice.

Abstract: A control valve is disclosed which includes first and second valves. An inverted pendulum is operative with the valves such that when the pendulum rotates in one direction the first valve is opened and the second valve is closed, and when the pendulum rotates in the opposite direction the valve operation is exactly opposite. An electromagnetic device may also be operative with the inverted pendulum which device when energized causes the inverted pendulum to rotate in one direction or the other. The inverted pendulum may also be rotatably biased for holding one valve opened and the other valve closed. The control valve may be used in any number of control systems and is especially suited for use as a master control valve in a vehicle braking system.