Stator

About: Stator is a research topic. Over the lifetime, 112505 publications have been published within this topic receiving 814877 citations.

Direct self-control (DSC) of inverter-fed induction machine

Abstract: The new direct self-control (DSC) is a simple method of signal processing that gives converter-fed three-phase machines an excellent dynamic performance. To control the torque of, say, an induction motor, it is sufficient to process the measured signals of the stator currents and the total flux linkages only. In the basic version of DSC, the power semiconductors of a three-phase voltage source inverter are directly switched on and off via three Schmitt triggers, comparing the time integrals of line-to-line voltages to a reference value of desired flux, if the torque has not yet reached an upper-limit value of a two-limit torque control. Optimal performance of drive systems is accomplished in steady state as well as under transient conditions by combination of several two-limit controls. >

A review of induction motors signature analysis as a medium for faults detection

Abstract: This paper is intended as a tutorial overview of induction motors signature analysis as a medium for fault detection. The purpose is to introduce in a concise manner the fundamental theory, main results, and practical applications of motor signature analysis for the detection and the localization of abnormal electrical and mechanical conditions that indicate, or may lead to, a failure of induction motors. The paper is focused on the so-called motor current signature analysis which utilizes the results of spectral analysis of the stator current. The paper is purposefully written without "state-of-the-art" terminology for the benefit of practising engineers in facilities today who may not be familiar with signal processing.

Rotor position and velocity estimation for a salient-pole permanent magnet synchronous machine at standstill and high speeds

Abstract: This paper addresses self-sensing ("sensorless") control of salient-pole permanent magnet synchronous motors (PMSMs). The major contribution of this work is the introduction of a simple-to-implement estimation technique that operates over a wide speed range, including zero speed. The technique achieves simplicity by decoupling the inherent cross-coupling in PMSMs. The technique utilizes the dependence of inductance on rotor position in interior permanent magnet machines to produce position and velocity estimates both for field orientation and for all motion control of the drives. The technique functions in a manner similar to a resolver and resolver-to-digital converter (RTDC) sensing system, whereby in the proposed technique the motor acts as the electromagnetic resolver and the power converter applies carrier-frequency voltages to the stator which produce high-frequency currents that vary with position. The sensed currents are then processed with a heterodyning technique that produces a signal that is approximately proportional to the difference between the actual rotor position and an estimated rotor position. This position error signal and a torque estimate are then used as inputs to a Luenberger style observer to produce parameter insensitive, zero lag, position and velocity estimates.

Flux-Weakening Regime Operation of an Interior Permanent-Magnet Synchronous Motor Drive

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.

Model Predictive Direct Torque Control—Part I: Concept, Algorithm, and Analysis

Abstract: This paper focuses on direct torque control (DTC) for three-phase AC electric drives. A novel model predictive control scheme is proposed that keeps the motor torque, the stator flux, and (if present) the inverter's neutral point potential within given hysteresis bounds while minimizing the switching frequency of the inverter. Based on an internal model of the drive, the controller predicts several future switch transitions, extrapolates the output trajectories, and chooses the sequence of inverter switch positions (voltage vectors) that minimizes the switching frequency. The advantages of the proposed controller are twofold. First, as underlined by the experimental results in the second part of this paper, it yields a superior performance with respect to the industrial state of the art. Specifically, the switching frequency is reduced by up to 50% while the torque and flux are kept more accurately within their bounds. Moreover, the fast dynamic torque response is inherited from standard DTC. Second, the scheme is applicable to a large class of (three-phase) AC electric machines driven by inverters.