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Allan Barr Plunkett

Bio: Allan Barr Plunkett is an academic researcher from General Electric. The author has contributed to research in topics: Induction motor & AC motor. The author has an hindex of 22, co-authored 49 publications receiving 1245 citations.

Papers
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Patent
14 Dec 1987
TL;DR: In this article, a field orientation control system for an interior permanent magnet synchronous motor includes function generating means responsive to a torque command signal for producing direct and quadrature axis direct current signals which are converted to synchronously-varying two-phase signals for coupling to power control means, for effecting sinusoidal energization of the permanent magnet motor.
Abstract: A field orientation control system for an interior permanent magnet synchronous motor includes function generating means responsive to a torque command signal for producing direct and quadrature axis direct current signals which are converted to synchronously-varying two-phase signals for coupling to power control means, for effecting sinusoidal energization of the permanent magnet motor. The function generators modify the torque command signal as a predetermined function of the motor parameters. Rotor position information is derived from measured stator voltages and currents without the use of a separate rotor position sensor. The control system includes means for establishing a preselected amplitude of a stator α-axis current in the motor at start-up prior to establishing orthogonal β-axis current such that the motor rotor is caused to become initially aligned with the selected α-axis.

118 citations

Patent
14 Apr 1975
TL;DR: In this article, 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 the motor flux voltage signal proportional to the actual motor flux was presented.
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. A second feedback control loop also responsive to the feedback sensed actual value of flux converts the flux signal into a (V/Hz) voltage control signal for maintaining a substantially controlled value of rotor-stator air gap flux level. The first and second feedback control loops are interconnected and coact to maintain operation of the induction motor at a controlled value of torque. The actual torque feedback circuit includes a flux signal processing circuit for deriving from the output motor flux signals respective direct and quadrature axes flux signal components and combines these signals with direct and quadrature axes motor current signal components in multiplier circuits for multiplying the quadrature axis flux signal by the direct axis motor current signal and for multipyling the direct axis flux signal by the quadrature axis motor current signal. A summing circuit sums the two products to derive an output actual value of torque developd by the induction motor in accordance with the expression T=K(ψ d i qs -ψ q i ds ). The system is designed primarily for use with a three-phase, variable voltage, variable speed, alternating current induction motor intended for traction motor drives and makes available a new and novel actual torque measuring arrangement for use in such systems.

80 citations

Journal ArticleDOI
TL;DR: In this article, an analysis method was developed to predict the performance of an induction motor in response to inverter waveforms, which was then used to aid in the development of a modulation strategy, to accurately evaluate the motor heating problem and to analyze a new method of transitioning from pulsewidth modulation to square wave operation.
Abstract: When induction motors are driven by electronic inverters, the applied voltage waveforms are quite nonsinusoidal. The fundamental component of the current is controlled by the load. The harmonic currents are limited principally by the motor leakage inductance and are independent of load. These harmonic currents can lead to increased motor heating and to increased peak currents. In addition, the modulation technique can give rise to problems in the control. An analysis method was developed to predict the performance of an induction motor in response to inverter waveforms. The correctness of the method was verified by comparison to measurements made on an operating system. This tool was then used to aid in the development of a modulation strategy, to accurately evaluate the motor heating problem and to analyze a new method of transitioning from pulsewidth modulation to square wave operation.

75 citations

Journal ArticleDOI
TL;DR: In this article, a practical method was developed to measure the flux level in an induction motor in the actual operating environment, using the flux signals and stator current, the actual electromagnetic torque signal responds correctly to motor saturation and inverter voltage waveform harmonics.
Abstract: A dc motor drive is controlled by varying the armature current and field current. The field is a measure of flux, and the armature current times field current is a measure of torque. Various approximate means of estimating the flux and torque levels in an induction motor exist. Most of these methods are sensitive to motor parameter value changes and do not work well near zero speed. Also, the harmonics in the motor voltage and current due to the nonsinusoidal inverter waveform cause errors in the estimated torque. A practical method has been developed to measure the flux level in an induction motor in the actual operating environment. Using the flux signals and stator current, the actual electromagnetic torque can be obtained. This torque signal responds correctly to motor saturation and inverter voltage waveform harmonics. The motor can be designed to operate without the customarily required flux margin, since the flux level is accurately controlled. The control strategy for use with these feedback signals does not require the use of a tachometer.

73 citations

Patent
25 Jun 1984
TL;DR: In this paper, a rotor structure having permanent magnet poles embedded therein is placed adjacent the end surface of the stator and coupled to the axial gap between the stators and rotor.
Abstract: An electric machine has a stator body formed of a coil of concentric layers of amorphous metal tape and slots are formed in one end of the coil for receiving a stator winding. A rotor structure having permanent magnet poles embedded therein is placed adjacent the end surface of the stator and is coupled thereto through the axial gap between the stator and rotor. The magnets are held in place in a nonmagnetic matrix which consists of an epoxy fiber laminate material. By enlarging the outer diameter of the rotor with the epoxy fiber laminate material, the rotor serves as an integral flywheel structure.

72 citations


Cited by
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Journal ArticleDOI
TL;DR: The author provides a guideline and quick reference for the practicing engineer to decide which methods should be considered for an application of a given power level, switching frequency, and dynamic response.
Abstract: The author evaluates the state of the art in pulsewidth modulation for AC drives fed from three-phase voltage source inverters. Feedforward and feedback pulsewidth modulation schemes with relevance for industrial application are described and their respective merits and shortcomings are explained. Secondary effects such as the influence of load-current dependent switching time delay and transients in synchronized pulsewidth modulation schemes are discussed, and adequate compensation methods are presented. Recorded oscillograms illustrate the performance of the respective pulsewidth modulation principles. The author provides a guideline and quick reference for the practicing engineer to decide which methods should be considered for an application of a given power level, switching frequency, and dynamic response. >

1,250 citations

Journal ArticleDOI
01 Aug 1994
TL;DR: In this paper, the authors present a detailed overview of the switching functions used in power converters, ranging from simple averaging schemes to involved methods of real-time optimization, which can be found in the literature.
Abstract: The efficient and fast control of electric power forms part of the key technologies of modern automated production It is performed using electronic power converters The converters transfer energy from a source to a controlled process in a quantized fashion, using semiconductor switches which are turned on and off at fast repetition rates The algorithms which generate the switching functions-pulsewidth-modulation techniques-are manifold They range from simple averaging schemes to involved methods of real-time optimization This paper gives an overview >

1,041 citations

Journal ArticleDOI
TL;DR: In this article, the inherent limitations of commanding voltages and currents in a three-phase load with an inverter are examined, and an overview of several current controllers described in the literature is presented, and computer simulations are used to compare performance.
Abstract: The inherent limitations of commanding voltages and currents in a three-phase load with an inverter are examined. An overview of several current controllers described in the literature is presented, and computer simulations are used to compare performance. A switching diagram is developed which reveals some of the operating characteristics of hysteresis controllers. For ramp comparison controllers, a frequency transfer function analysis is used to predict the line currents and provide some insight into the compensation required to reduce the current errors.

889 citations

Journal ArticleDOI
Thomas M. Jahns1
TL;DR: In this article, the authors present a flux-weakening control algorithm for the interior permanent magnet (IPM) synchronous motor, which is compatible with extended-speed-range constant power operation by means of flux weakening control.
Abstract: The interior permanent magnet (IPM) synchronous motor is compatible with extended-speed-range constant-power operation by means of flux-weakening control. Flux weakening uses stator current components to counter the fixed-amplitude magnetic airgap flux generated by the rotor magnets, performing a role similar to field weakening in a separately excited dc motor. The nature of current regulator saturation caused by the finite inverter dc source voltage is described, marked by premature torque and power degradation at high speeds in the absence of flux-weakening control. This is followed by presentation of a new flux-weakening control algorithm developed as a modification of an established feedforward IPM torque control algorithm described previously in the literature. Attractive features of this new algorithm include smooth drive transitions into and out of the flux-weakening mode, fast response, as well as automatic adjustment to changes in the dc source voltage. Simulation and empirical test results from a 3-hp laboratory IPM motor drive are used to confirm the constant-power operating envelope achieved using the new flux-weakening control algorithm.

750 citations

Journal ArticleDOI
01 Jul 1962

656 citations