Eaton Corporation

American Superconductor Corporation

Drs Power & Control Technologies, Inc.

David J Gritter

Allan Roy Gale

Dora Yuan Wang

Thomas G Habetler

Walter K O'Neil

David M Messersmith

Jerome Kenneth Hastings

James E Hansen

Birger Pahl

Douglas C Folts

Edward Louis Wellner

Ronald Gordon Harley

Engelbert Hetzmannseder

David W Turner

Sang-Bin Lee

Scott A Reid

John H Wolcott

James A Ulrich

Jeffrey A Reichard

William Edward Berkopec

Elias G Strangas

Michael P Ross

Rangarajan M Tallam

Michael A Shanblatt

Karen Sjaarda Bland

Thomas Edward Strunsee

Embodiments of the present invention are directed to a controller that is configured to limit the rate of change of speed of a motor (e.g., the acceleration or deceleration) regardless of the operating mode of the motor (e.g., speed, torque, or power control mode). The controller can include an acceleration estimator which monitors the output speed of a motor and provides an acceleration-limited speed set point. The output of the acceleration estimator may be limited to a range of acceptable acceleration values that correspond to the required limits of acceleration and deceleration. The acceleration estimator can be configured such that it causes the speed regulator to override the torque and/or power regulators when the acceleration range is exceeded.

Acceleration estimator for speed rate control

An inverter controller comprising a current regulator unit, a voltage regulator unit coupled to the current regulator unit, an inverter unit coupled to the voltage regulator unit, and a drive unit controlled by the inverter unit.

Inverter control when feeding high impedance loads

A system for connecting a wind turbine generator to a utility power network includes a first power converter that converts an AC signal from the wind turbine generator to a DC signal and supplies a controlled amount of reactive current to the wind turbine generator. The system also includes a second power converter, connected in series with the first converter, which converts the DC signal from the first power converter to a line-side AC signal and supplies a controlled amount of current to the utility power network. A power dissipation element is coupled to the first and second power converters for dissipating power from the first power converter.

Low voltage ride through

A control system for an AC line voltage distribution system includes a DC energy storage system and an inverter coupled to the DC energy storage system adapted for coupling to the AC line distribution system. A proportional-integral voltage regulator coupled to the DC energy storage system receives a voltage signal for the DC energy storage system and receives a voltage reference. In an exemplary embodiment, the voltage regulator includes a proportional path and an integral path to receive the DC voltage information and the voltage reference signal information, a filter to remove an AC component having a predetermined frequency contained in the DC voltage signal, and an output terminal to output a control signal with the AC component removed.

Power system having a voltage regulator with a notch filter

A power system having a phase locked loop (PLL) with a notch filter for synchronous reference frame sequence separation. The notch filter includes a generalized integrator tuned to the notch frequency. The output of the generalized integrator is summed with the filter input signal and the output of the summer is fed back to the integrator input. In one embodiment, the notch filter is programmable by a control signal generated in response to the filter output signal, thereby causing the filter to self-regulate to a frequency related to the PLL input signal. Illustrative power systems include active VAR generators and active rectifiers. One or more additional notch filters may be used to remove harmonic components from derived synchronous reference frame sequence components.

Power system having a phase locked loop with a notch filter

A device and method to estimate the resistance of a stator winding of an AC induction motor is provided. The device includes an AC induction circuit connecting one phase of the AC induction motor to an AC source. The circuit includes a resistor and a switch connected in parallel. The switch is alternatively closed during the half cycles of the AC current supplied to the motor so as to inject a DC voltage and current bias to the AC motor. The resistance of the stator winding is estimated in response to the DC voltage and current bias.

Device and method for estimating the resistance of a stator winding for an AC induction motor

A stator turn fault detection system and method capable of real-time detection of a stator turn fault in an electric motor is provided. The stator turn fault detector includes a feed forward neural network that when trained, using fundamental frequency sequence components of the voltage and current supplying the electric motor, will estimate a fundamental frequency sequence component of current indicative of a stator turn fault. A method for detecting a stator turn fault in an electric motor as well as a method for training a feed forward neural network for use with the stator turn fault detector is disclosed.

Method and apparatus to detect a stator turn fault in an AC motor

A method is provided for controlling a three-phase, AC induction motor. Each phase of the AC induction motor is connected to an AC input source by a thyristor switch and a bypass contactor connected in parallel in order to provide voltage and current to the AC induction motor. The method includes the steps of sequentially firing pairs of thyristor switches at a predetermined initial gamma firing angle. A new gamma firing angle is calculated which is dependant upon the initial gamma firing angle. Thereafter, pairs of thyristor switches are fired at the new gamma firing angle. The new gamma firing angle is provided as the initial gamma firing angle and a new gamma firing angle is calculated. The process is repeated until the AC induction motor reaches its full operating speed.

Method and controlling the starting of an AC induction motor with closed loop current control

A method is provided for controlling a three-phase, AC induction motor. Each phase of the AC induction motor is connected to an AC input source by a thyristor switch and a bypass contactor connected in parallel in order to provide voltage and current to the AC induction motor. The method includes the steps of sequentially firing pairs of thyristor switches at a predetermined initial alpha firing angle. A new alpha firing angle is calculated which is dependant upon the initial alpha firing angle. Thereafter, pairs of thyristor switches are fired at the new alpha firing angle. The new alpha firing angle is provided as the initial alpha firing angle and a new alpha firing angle is calculated. The process is repeated until the AC induction motor reaches its full operating speed.

Method for controlling the starting of an induction motor utilizing closed loop alpha control

A method is provided for controlling the starting of an AC induction motor with a soft starter. The windings are connected in a delta configuration and each winding has a corresponding thyristor switch connected in series therewith such that each winding and thyristor switch combination is connected between two corresponding terminals of the AC induction motor. Alpha control of the thyristor switches is utilized to start the AC induction motor and bring the AC induction motor to near full operating speed. As the AC induction motor nears full operating speed, gamma control of the thyristor switches is utilized to bring the AC induction motor to full operating speed. With the AC induction motor at full operating speed, bypass contactors, in parallel across corresponding thyristor switches, are closed and the AC induction motor operates in a conventional manner.

Method for controlling the starting of an AC induction motor

Electrical equipment is safeguarded from damage due to faults by a circuit that provides several levels of protection. A semiconductor switch and a current sensor are placed in series with the electrical equipment. When the current to the equipment exceeds a first threshold for a predefined period of time, the semiconductor switch is rendered non-conductive until the circuit is specifically reset. When the current to the equipment exceeds a greater second threshold, a pulsed signal alternately places the semiconductor switch in conductive and non-conductive states so that the average current applied to the equipment is within an acceptable level. Should the current exceed an even greater third threshold, the semiconductor switch is immediately rendered non-conductive until the circuit is manually reset.

Soild state protection circuit for electrical apparatus

A voltage rise limiting circuit (10) for use in conjunction with an inverter-driven induction motor (14). The circuit (10) includes capacitors (C4, C5, C6) connected in a delta configuration, with each node (64, 66, 68) coupled between an inductor (L7,L8,L9) and an input line of a diode bridge rectifier. The rectifier clamps positive voltage levels, putting trapped energy back into the dc inverter bus.

DV/DT limiting of inverter output voltage

A method and a device for regulating current from an inverter supplying three-phase excitation signals to an induction motor. Two of the three phase currents are converted to digital signals which are sent to a microprocessor. The microprocessor converts the digital signals into a waveform angle signal and a waveform modulation constant signal. The switching signals for the inverter are generated in response to the waveform angle signal and the waveform modulation constant signal.

Digital current regulator

A method for starting an unexcited, multiple phase, alternating current induction motor rotating at an unknown speed is provided. The method includes generating an output signal with an AC drive at a predetermined frequency in order to energize the motor. The output signal has independently adjustable frequency and voltage components. A speed reference is provided which is functionally related to the frequency of the output signal. The voltage of the output signal is ramped at a predetermined rate and the frequency of the output signal is adjusted such that the voltage of the output signal equals the motor's set point and the speed reference is substantially equal to the speed of the motor. The motor then enters the normal operating mode.

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Racine, WI, United States of America

David J Gritter