A demonstration of a sensorless torque meter for AC motors

Kliman, G.B.; Koegl, R.A.; Premerlani, W.; Breen, T.B.

doi:10.1109/ias.1996.557102

Cited by 11 publications

(6 citation statements)

References 1 publication

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“…The accuracy of the above expression for torque has been confirmed experimentally in [26]. We note that for squirrelcage induction machines, which often have saturable material connecting the rotor teeth at their pole faces, saturation can also occur in the rotor leakage.…”

Section: Magnetic Circuit Modelingsupporting

confidence: 52%

Stator-flux-based vector control of induction machines in magnetic saturation

Hofmann¹,

Sanders²,

Sullivan³

IAS '95. Conference Record of the 1995 IEEE Industry Applications Conference Thirtieth IAS Annual Meeting

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Abstract-In many variable-torque applications of induction machines, it is desirable to operate the machine at high flux levels, thus allowing the machine to produce higher torques. This can lead to saturation of the main flux path, introducing crosscoupling effects which can severely disrupt the performance of controllers dependent on knowledge of the machine's magnetic parameters. Stator-flux-oriented torque-control schemes need not depend on the magnetic parameters of the machine and, hence, are potentially more robust and easier to implement in magnetic saturation than rotor-flux-oriented control. In this paper, we present and analyze a stator-flux-oriented torque-control scheme. This controller only requires knowledge of the stator voltage, stator current, and stator resistance. An analytical expression for the maximum achievable torque output of the machine using a linear magnetics model is compared with values calculated using a nonlinear magnetics model incorporating saturation of the main flux path and is shown to be a good approximation at high flux levels, when the main flux path is heavily saturated. Experiments carried out on a 3-hp 1800-r/min wound-rotor induction machine show smooth operation of the control scheme at torque levels up to at least four times rated torque.

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Section: Magnetic Circuit Modelingsupporting

confidence: 52%

Stator-flux-based vector control of induction machines in magnetic saturation

Hofmann¹,

Sanders²,

Sullivan³

IAS '95. Conference Record of the 1995 IEEE Industry Applications Conference Thirtieth IAS Annual Meeting

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“…The AGT method is based on the electromagnetic or sensorless torque equations developed in the 1990s [20], [21], and the first known work suggesting the use of AGT to measure efficiency and load changes of in-service induction motors is [14]. The main advantages of the AGT method are its accuracy and ease of implementation [15], [19].…”

mentioning

confidence: 99%

Induction Motor Efficiency Evaluation Using a New Concept of Stator Resistance

Salomon

Sant’Ana

Silva

et al. 2015

IEEE Trans. Instrum. Meas.

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This paper presents an air-gap torque (AGT)-based method for efficiency estimation of induction motors. A new concept of stator resistance that includes the mechanical losses effect is proposed. This new stator resistance is estimated through a particle swarm optimization approach based on the stator flux equations and minimization of torque error at the rated operation point. Then, the obtained stator resistance is used in the AGT equations to estimate the shaft torque and then the efficiency. Moreover, the rotor speed is estimated using induction motor current signature analysis. Thus, the proposed methodology for induction motor efficiency estimation relies only on line currents, line voltages, and nameplate data, being appropriate for in-service applications. Finally, the simulation and experimental results are presented to validate the proposed method at different load conditions.

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“…This method has most accurate field-efficiency evaluation but also high intrusive. In the AGT method, the air-gap torque is calculated using instantaneous input line voltages and a line current [17,18]. The losses obtained from noload test are subtracted from air-gap power for efficiency calculation [19].…”

Section: Efficiency Estimation Methods For Induction Motormentioning

confidence: 99%