Electronic marker for experimental estimation of rotor current delay in an induction motor

RELEVANCE. In subordinate and field-oriented control of induction motor drives, rotor electromagnetic inertia is often treated implicitly. However, when the bandwidth of inner current loops is increased, rotor dynamics introduces a measurable delay and affects stability margins.

SCIENTIFIC SIGNIFICANCE. The study provides an experimental basis for validating inductionmachine dynamic models and for estimating an equivalent rotor time constant from oscillograms. OBJECT. To develop and validate a laboratory method for estimating rotor current delay with respect to a stator-side reference event using a short electronic marker.

METHODOLOGY. A rectangular pulse marker is injected into one stator phase. The marker is generated by an NE555 pulse generator and delivered through a TLP627(F) optocoupler, providing galvanic isolation. A digital oscilloscope with a differential probe records the marker on the 50 Hz waveform together with rotor current. The test is carried out in a locked-rotor condition (slip s=1).

RESULTS. The marker is reliably detected on top of the supply waveform. The measured phase delay between the stator reference and the rotor current response is about 40–45 degrees (2.2–2.5 ms at 50 Hz).

CONCLUSIONS. The electronic marker approach improves repeatability of rotor delay measurements and can be used for simulation validation and current-loop tuning that accounts for rotor electromagnetic inertia.

1. Rodriguez-Sotelo D, Rodriguez-Licea MA, Araujo-Vargas I, et al. Power Losses Models for Magnetic Cores: A Review. Micromachines. 2022;13(3):418. doi:10.3390/mi13030418.

2. Bloch F. Nuclear Induction. Physical Review. 1946;70(7-8):460-474.

3. Hamzehbahmani H, Anderson PI. Static hysteresis modeling for grain-oriented electrical steels for dynamic modeling. Journal of Applied Physics. 2021;130:055102. doi:10.1063/5.0058554.

4. Bašić M, Vukadinović D, Grgić I. Model Predictive Current Control of an Induction Motor Considering Iron Core Losses and Saturation. Processes. 2023;11(10):2917. doi:10.3390/pr11102917.

5. Han Y, et al. Robust Online Rotor Time Constant Tuning Method with High-Frequency Current Injection for Indirect Field-Oriented Induction Motor Drives. Symmetry. 2025;17(10):1729. doi:10.3390/sym17101729.

6. Janisch G, Kugi A, Kemmetmüller W. A high-performance model predictive torque control concept for induction machines for electric vehicle applications. Control Engineering Practice. 2024;153:106128. doi:10.1016/j.conengprac.2024.106128.

7. Martynov KV, Panteleeva LA, Blagodatskikh IA. Otsenka energeticheskikh kharakteristik asinkhronnogo dvigatelya s sovmeshchennoy obmotkoy [Estimation of energy characteristics of an induction motor with a combined winding]. Proceedings of the higher educational institutions. ENERGY SECTOR PROBLEMS. 2021;23(6):109-118. (In Russ). doi:10.30724/1998-9903-2021-23-6-109-118.

8. Tsvetkov AN, Doan NS, Yaroslavsky DA. Issledovaniya po optimizatsii vektornogo upravleniya asinkhronnym dvigatelem s primeneniem sistemy analiticheskogo kontrolya [Research on optimization of vector control of an asynchronous motor using an analytical control system]. Proceedings of the higher educational institutions. ENERGY SECTOR PROBLEMS. 2022;24(3):144-157. (In Russ). doi:10.30724/1998-9903-2022-24-3-144-157.

9. Ismoilov II, Gracheva EI. Povyshenie upravlyaemosti ehnergeticheskimi sistemami i uluchshenie kachestva ehlektroehnergii [Improving controllability of power systems and electric power quality]. Vestnik Kazanskogo gosudarstvennogo ehnergeticheskogo universiteta. 2022;14(1(53)):3-12. (In Russ).

10. Safin AR, Gracheva EI, Behera RK, Petrov TI. Ispol'zovanie ferritovykh magnitov v sinkhronnykh dvigatelyakh s postoyannymi magnitami [Using ferrite magnets in permanentmagnet synchronous motors]. Vestnik Kazanskogo gosudarstvennogo ehnergeticheskogo universiteta. 2022;14(1(53)):47-55. (In Russ).

11. Texas Instruments. NE555 Precision Timers. Datasheet. Available at: https://www.ti.com/lit/ds/symlink/ne555.pdf. Accessed: 31 Jan 2026.

12. Toshiba. TLP627, TLP627-2, TLP627-4 Photocouplers. Datasheet. Available at: https://www.farnell.com/datasheets/2007824.pdf. Accessed: 31 Jan 2026.

13. Dzyuin DV, Dmitrieva VV. Razrabotka programmy rascheta parametrov skhemy zameshcheniya trekhfaznogo asinkhronnogo ehlektrodvigatelya [Development of a program for calculating the equivalent circuit parameters of a three-phase induction motor]. Avtomatizatsiya i modelirovanie v proektirovanii i upravlenii. 2024;(3):84-92. (In Russ). doi:10.30987/2658-64362024-3-84-92.

14. Olkhovatov DV, Grebennikov NV, Shevkunova AV. Sintez ehlektroprivoda kompressornoy ustanovki ehlektrovoza [Synthesis of an electric drive for an electric locomotive compressor unit]. Transportnoe mashinostroenie. 2024;(5):40-49. (In Russ). doi:10.30987/27825957-2024-5-40-49.

15. Ustroistvo upravleniya vektorom asinkhronnogo ehlektroprivoda [Vector control device for induction drive]. Patent RUS RU 2392732 C1. Publ. 20 Jun 2010. Available at: https://patents.google.com/patent/RU2392732C1/ru. Accessed: 31 Jan 2026. (In Russ).