Analysis of Stability of Electric Drives as Non-linear Systems According to Popov Criterion Adjusted to Amplitude and Phase Frequency Characteristics of Its Elements

Kodkin, Vladimir L.; Anikin, A. S.; Baldenkov, A. A.

doi:10.12783/dtetr/amsm2017/14810

Cited by 13 publications

(18 citation statements)

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“…Becomes a linear link, independent of the slip (load) and fully coinciding with the transfer function given in the Usoltsev monograph for small loads [14]. Pay attention to formula (15). A dynamic link is a first-order inertia with a coefficient that ultimately depends on the frequency of the stator voltage and on the absolute slip.…”

Section: Justification Of Pdf For Transfer Functions Of Aedmentioning

confidence: 96%

“…As the experiments showed, the applied algorithms are not very effective, and the hard positive feedback on the stator current breaks the stability. In works [6,15,18] the positive dynamic connection on current is described. Without compromising stability (and in some cases improving it), this relationship provides full compensation for the load torque and not only in statics.…”

Section: Corrections Of Asynchronous Electric Drivementioning

confidence: 99%

“…According to the formulas, it is possible to explain the efficiency of the positive feedback on the current of the stator of the electric motor, described in the articles [6,15,18]. Consider the option of applying local feedback on the electromagnetic torque in this structure.…”

Section: Justification Of Pdf For Transfer Functions Of Aedmentioning

confidence: 99%

“…It should be noted that the correction of the coefficient from the frequency is very easy to implement in frequency converters; several options for partial (indirect) adaptation of the connection to the load will be discussed below. Thus, the proposed positive feedback, selected by condition (15), makes it possible to compensate for the effect of the external load and the nonlinearity of the AED, spreading the transfer function of the motor as a link of the first order for any values of β. In addition, the block diagram (Figure 13) and the transfer function of the torque formation link (6) connecting the torque and slip allow us to offer an estimate of the efficiency of the torque formation algorithm: the algorithm that generates the necessary torque with the smallest absolute slip will be more effective.…”

Section: Justification Of Pdf For Transfer Functions Of Aedmentioning

confidence: 99%

“…Dynamic links are quite complex. This leads to the fact that the equivalent transfer functions of AED may in some modes contain resonant links that lead to control failures, high-frequency harmonics, and differences in dynamics at different speeds noted during the experiments [15,16]. The stability analysis of such systems presents a known complexity.…”

mentioning

confidence: 99%

See 4 more Smart Citations

Nonlinear Dynamics of Asynchronous Electric Drive: Engineering Interpretation and Correction Techniques

Kodkin¹,

Anikin²,

Baldenkov³

2019

Control Theory in Engineering [Working Title]

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The results of theoretical and practical research studies most widely used in the industry of variable frequency drives (VFD) are presented in this manuscript. Such objects are characterized by dynamic nonlinearities that are difficult to take into account in the mathematical description for the development of control algorithms. Accounting for these nonlinearities leads to equations that are very problematic to solve. Therefore, the equations of the mathematical model on which the vector control system is based are compiled with the assumption of the sinusoidality of the processes occurring in the control object. Comparative results of the analysis of dynamic of VFD with two types of sensorless control, vector and scalar, show the problems that these assumptions lead to.. For identification of nonlinearities, dynamic formulas of transfer functions of torque generator in VFD are proposed, taking into account slip and stator voltage frequency The nonlinear transfer functions obtained in this work made it possible to substantiate structural solutions that linearize the VFD and substantially increase their efficiency. The use of dynamic feedback on the stator current allowed to significantly increase the dynamics and efficiency of a more stable scalar control.• If in the "right" part of the equation, that is, at any input of the system, there is a harmonic signal of a certain frequency, then all blocks will have harmonic input and output signals of only this frequency, different in amplitude about the phase.Naturally, real electric drives can be identified by LSS with only very large approximations. In direct-current drives with independent excitation, these approximations are insignificant; they mostly relate to mechanical structures with stiffness and gaps. In asynchronous electric drives, the reduction to LSS is associated with much larger errors. The equations of a generalized AC motor, even with significant assumptions, can be reduced to linear equations with variable coefficients or to nonlinear control systems. For engineering calculations, the differences between these systems are very conditional. If variable coefficients depend on the same coordinates of the electric drive (rotational speed, stator current, etc.), the 2 Control Theory in Engineering

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Section: Justification Of Pdf For Transfer Functions Of Aedmentioning

confidence: 96%

Section: Corrections Of Asynchronous Electric Drivementioning

confidence: 99%