Indonesian J our nal of Electrical Engineering and Computer Science V ol. 41, No. 1, January 2026, pp. 3 17 ISSN: 2502-4752, DOI: 10.11591/ijeecs.v41.i1.pp3-17 3 Dynamic beha vior of induction machines in A TP-EMTP with space harmonics J ose Manuel Aller , Ruben Nicolas Gue v ara, Bryam Ste v en Pulla Department of Electrical Ener gy , Uni v ersidad Politecnica Salesiana (UPS), Cuenca, Ecuador Article Inf o Article history: Recei v ed Apr 4, 2025 Re vised Dec 5, 2025 Accepted Dec 14, 2025 K eyw ords: A TP-EMTP Induction machine Space harmonics T ransient analysis VBR model ABSTRA CT This w ork de v elops a space-v ector model of a squirrel-cage induction machine that incorporates the ef fects of spatial harmonics arising from the windi ng distri- b ution. The modeli ng approach includes the rst, fth, and se v enth spatial har - monics, which are the components with the greatest inuence on the machine’ s magnetic eld. Simulation results highlight the impact of these harmonics on the stator and rotor currents, the electromagnetic torque, and the machine’ s speed. T o b uild the model, the v oltage behind reactances (VBR) technique is emplo yed, enabling a h ybrid strate gy that combines circuit-based modeling tools—such as A TP-EMTP—with computational programming in models t o complement the solution of the dif ferential equations go v erning the beha vior of the electrome- chanical system. This methodology ef fecti v ely transforms the induction ma- chine into a dynamic Th ` ev enin-equi v alent circuit for each phas e of the con v erter . This study pro vides a useful frame w ork for e v aluating ho w space harmonics af- fect t he performance and operating characteristics of induction machines. The models were implemented using the A TP-EMTP softw a re and its graphical in- terf ace, A TPDra w . This is an open access article under the CC BY -SA license . Corresponding A uthor: Jose Manuel Aller Department of Electrical Ener gy , Uni v ersidad Politecnica Salesiana (UPS) Sede Cuenca, Calle V ieja y Elia Liut, 010105 Cuenca, Ecuador Email: jaller@ups.edu.ec 1. INTR ODUCTION The induction machine is currently the most widely used electromechanical con v erter . Its rob ustnes s, reliability , and lo w maintenance requirements enable it to operate e v en under v ery harsh conditions [1], [2]. Its in v ention is attrib uted to Nicola T esla, who de v eloped the concept of the rotating magnetic eld in 1888 [3]. Ho we v er , during the same period, the Italian Galilera Ferraris presented similar w ork between 1885 and 1888 [4], [5]. Later , in Doli v o-Dobro v olsk y [6] and Ferraris and Arno [7] introduced the use of three-phase coils in the induction machine, which is no w standard in electrical distrib ution systems. This de v elopment laid the foundation for modern electrical industry , pro viding signicant performance, v ersatility , and reliability across v arious sectors [8]. The space harmonics generated by the space distrib ution of the stator and rotor windings af fect the machine’ s performance, which has been e xtensi v ely studied [9], [10]. These harmonics alter the distrib ution of the magnetic eld and can generate uctuations in electrical torque, distorted v oltage w a v eforms, losses and noise that af fect the ef cienc y and operational characteristics of the machine [11]–[13]. This article models the induction machine, considering the rst, fth, and se v enth space harm o ni cs, which are the most important components of the eld in the air g ap. This type of model allo ws for the de v el- J ournal homepage: http://ijeecs.iaescor e .com Evaluation Warning : The document was created with Spire.PDF for Python.
4 ISSN: 2502-4752 opment of speed measurement strate gies u s ing the harmonic spectrum of the currents [14], [15]. The approach used consists of representing the machine through space v ectors where both the stator and rotor refer to their respecti v e reference systems [16], [17], due to the presence of space harmonics that pre v ent simplifying the dependence on the angular position θ of the rotor when transforming the equations to the stator reference. The v oltage behind reactance (VBR) model is a widely used method for representing induction ma- chines due to its impro v ed numerical ef cienc y and e xibility compared to traditional models [18], [19]. In the modeling, the VBR approach is applied, which f acilitates analysis by representing the internal v oltage of the machine as a combination of electromoti v e force, r esistance, and inductance whose parameters v ary o v er time with the rotor’ s position. This approach has been utilized by se v eral authors for the inte gration of the machine with its electronic dri v es, b ut the inclusion of space harmonics in this type of modeling is unprecedented, e v en though [20] has proposed an approach based on the VBR technique to include the ef fects of saturation in the induction machine. Furthermore, this model is implemented using the A TP-EMTP tool and its graphical en vironment A TPDra w [21], [22] to study the impact of space harmonics on k e y v ariables such as angular speed, electrical torque, and currents. This approach allo ws for obtaining a more accurate model of the induction machine, which f acilitates the e v aluation of losses, ef cienc y , and its operational characteristics [23]–[25]. 2. METHOD 2.1. Statement of the theor etical pr oblem The analysis of the dynamic beha vior of induction machines is fundamental to ensuring the st ability and ef cienc y of modern electrical systems [26], [27]. These machines represent an essential component in industrial, commercial, and po wer generation applications, where their proper modeling allo ws for predicting their response under dif ferent operating conditions. Ho we v er , the presence of space harmonics in their opera- tion introduces comple x phenomena that af fect their performance, generating current distortions, v ariat ions in electromagnetic torque, and additional losses in the system [11]-[13]. Space har monics are produced by the geometry of the air g ap, the winding distrib ution, and magnetic saturation, generating adv erse ef fects on the operation of induction machines. Consequently , the precise sim- ulation of these ef fects is crucial for e v aluating their impact on the stability of the electrical system and the ef cienc y of de vices connected to the grid [20]. In this conte xt, there is a need to de v elop a model that realistically represents the dynamic beha vior of induction machines, considering the ef fects of space harmonics and v alidating it through simulations in A TP- EMTP . This study aims to bridge the e xisting g ap between theory and practice by implementing more accurate models. The v alidation of these models will impro v e the design of induction machines by implem enting ne w technologies to lter the harmonics produced by the induction machine. Furthermore, this model will allo w for observing the impact of these harmonics on electrical parameters suc h as torque, angular speed, currents in the stator , among others. In this w ay , it will contrib ute to mitig ating these ef fects and aid in the constructability of the machine. 2.2. VBR model of the IM considering rst harmonic space distrib ution The v oltage equations of the IM in space v ectors can be represented as [28]: v s 0 = R s 0 0 R r i s i r + p " λ s λ r # (1) where, " λ s λ r # = L s M 1 e j θ M 1 e j θ L r i s i r (2) From (1) and (2), we obtain, p λ r = R r L r λ r M 1 e j θ i s (3) Indonesian J Elec Eng & Comp Sci, V ol. 41, No. 1, January 2026: 3–17 Evaluation Warning : The document was created with Spire.PDF for Python.
Indonesian J Elec Eng & Comp Sci ISSN: 2502-4752 5 and, ir = 1 Lr λ r M 1 e j θ i s (4) Introducing (3) and (4) into the stator v oltage equation v s (1), we obtain the VBR model, which is a dynamic Th ` ev enin equi v alent: v s = R eq , i s + L eq , p i eq + e eq , (5) where: R eq = R s + R r M 2 1 L 2 r (6) L eq = L s M 2 1 L r (7) e eq = M 1 L r j ˙ θ R r L r e j θ λ r (8) The electrical torque in space v ectors is obtained from, T e 1 = M 1 m n i s i r e j θ o = M 1 L r m n i s λ r e j θ o (9) In Figure 1, the VBR model of the IM in space v ectors is presented, referenced to the stator and rotor ax es, considering that the space distrib ution is of the rst harmonic. i s R eq = R s + R r M 2 1 L 2 r L eq = L s L r M 2 1 L 2 r + e eq v s p λ r = R r L r λ r M 1 i s e eq = M 1 L r j ˙ θ R r L r e j θ λ r T e = M 1 L r Im n i s λ r e j θ o Figure 1. VBR model of the IM corresponding to the rst space harmonic in stator -rotor coordinates 2.3. VBR model of the IM considering higher space harmonics T o assess the ef fect of space harmonics in the IM model, the contents of the rst, fth, and se v enth space harmonics are included, as the y ha v e the most signicant magnitudes. Ho we v er , the proposed method can be generalized to an y number of harmonics in space. The third harmonic in balanced three-phase machines is generally ne gligible and, for this reason, it has not been considered in this model. The (1) is v alid for an y number of harmonics. The fundamental dif ference lies in the determination of the inductance matrix and its relationship with the ux links: " λ s λ r # = L s P M sr i ( θ ) P M r s i ( θ ) L r i s i r (10) Dynamic behavior of induction mac hines in A TP-EMTP with space harmonics (J ose Manuel Aller) Evaluation Warning : The document was created with Spire.PDF for Python.
6 ISSN: 2502-4752 where: X M sr i ( θ ) = M 1 e j θ + M 5 e j 5 θ + M 7 e j 7 θ + M 11 e j 11 θ + M 13 e j 13 θ + · · · From e xpression (10), we obtain: ir = 1 Lr λr X M r s i ( θ ) i s (11) and replacing (11) in (1), we ha v e: p λ r = R r L r λ r X M r s i ( θ ) i s (12) The stator v oltage equation, obtained from (1), including the ef fect of the space harmonics, is: v s = R s i s + p L s i s + X M sr i ( θ ) i r (13) By substituting (11) and (12) into (13), we obtain: R eq = R s + R r L 2 r M 2 1 + M 2 5 + M 2 7 + . · · · + 2 ( M 1 M 5 + M 1 M 7 + M 5 M 7 ) cos 6 θ + · · · (14) The equi v alent inductance L eq is: L eq = L s 1 L r M 2 1 + M 2 5 + M 2 7 + . · · · + 2 ( M 1 M 5 + M 1 M 7 + M 5 M 7 ) cos 6 θ + . · · · (15) The electromoti v e force e e is: e eq = R r L r A + j ˙ θ A θ λ r L r + 12 ˙ θ B L r sin 6 θ i s (16) where: A = M 1 e j θ + M 5 e j 5 θ + M 7 e j 7 θ B = M 1 M 5 + M 1 M 7 + 4 M 5 M 7 cos 6 θ Finally , the electrical torque can be determined as: T e = T e 1 + T e 5 + T e 7 (17) where, T e 1 = M 1 L r m n i s λ r e j θ o (18) T e 5 = 5 M 5 L r m n i s λ r e j 5 θ o (19) T e 7 = 7 M 7 L r m n i s λ r e j 7 θ o (20) The VBR model is a dynamic equi v alent of the dif ferential equations of the machine that allo ws it to be represented by an electrical circuit with R eq , L eq , and an electromoti v e force e eq . The v ariables used are space v ectors obtained from the general e xpression: x s = r 2 3 n x a ( t ) + e j 2 π 3 x b ( t ) + e j 4 π 3 x c ( t ) o (21) Indonesian J Elec Eng & Comp Sci, V ol. 41, No. 1, January 2026: 3–17 Evaluation Warning : The document was created with Spire.PDF for Python.
Indonesian J Elec Eng & Comp Sci ISSN: 2502-4752 7 The equi v alent resistance R eq and inductance L eq can be directly used in each of the phases of an electrical circuit. The rotor’ s ux link can be obtained by numerically inte grating the dif ferential (3). W ith this information, it is possible to determine the space v ector of the electromoti v e force e eq . T o determine the electromoti v e forces of each phase of the IM, the in v erse transformations are used: x a ( t ) = r 2 3 e { x s } (22) x b ( t ) = r 2 3 e n x s e j 4 π 3 o (23) x a ( t ) = r 2 3 e n x s e j 2 π 3 o (24) 2.4. VBR model of the IM in A TPDraw Figure 2 represents the dynamic model of an induction machine de v eloped in the graphical en viron- ment of A TPDra w from the A TP-EMTP program, including the inuence of space harmonics. The model includes the three phases of the IM, calculating within the simulation models block the rotor’ s ux link, which allo ws for the determination of instantaneous v alues of R eq , L eq , e a , e b y e c . The dependent electromoti v e forces must be simulated using Norton equi v alents because the tool does not ha v e isolated dependent v oltage sources from ground. One of the main dif culties with programming in models is that it requires separating the v ariable s into real and imaginary parts, as this tool does not handle comple x numbers. The programming used to create the model can be found in section 4.2.1, where the v ariables denoted with x represent the real part and those with y represent the imaginary part of the space v ector . Figure 2. Model in A TPDra w of a VBR induction machine for space harmonic analysis Dynamic behavior of induction mac hines in A TP-EMTP with space harmonics (J ose Manuel Aller) Evaluation Warning : The document was created with Spire.PDF for Python.
8 ISSN: 2502-4752 3. RESUL TS 3.1. Results of the VBR model of the IM In T able 1, the data used to analyze the beha vior of the IM is presented. T able 1. Data of the IM used in the VBR modeling P arameter V alue R s 0 . 353 R r 0 . 424 L ls 2 . 59 mH L lr 3 . 88 mH p 2 pair M sr1 67 . 47 mH M sr5 0 . 60 mH M sr7 0 . 60 mH J 0 . 163 k g m 2 k r 0 . 002 W / ( r a d/s ) 2 3.1.1. Results corr esponding to the simulation with fundamental harmonic in space In Figure 3, the results obtained with the VBR model of the IM are sho wn, considering the beha vior of the rst, fth, and se v enth space harmonics. In Figure 4, the beha vior of the currents obtained is represented for the same case, considering in the simulation only the rst space harmonic. Figure 5 presents a detail of the machine’ s currents in steady state when only the rst harmonic is considered in the spac e distrib ution. In this case, the stator currents also e xhibit a rst temporal harmonic. Figure 3. Electrical torque and angular speed of the IM considering the fundamental harmonic Figure 4. Currents in phases a, b, and c of the IM stator , considering the fundamental harmonic Indonesian J Elec Eng & Comp Sci, V ol. 41, No. 1, January 2026: 3–17 Evaluation Warning : The document was created with Spire.PDF for Python.
Indonesian J Elec Eng & Comp Sci ISSN: 2502-4752 9 Figure 6 sho ws the F ouri er spectrum of the currents obtained in t he simulation, where it is observ ed that only the presence of the rst temporal harmonic e xists due to the space distrib ution, which includes only the fundamental component. Finally , Figure 7 presents the de v elopment of the space v ectors of the rotor ux of the IM during startup. Figure 5. Currents in phases a, b, and c of the IM stator , considering the fundamental harmonic Figure 6. F ourier spectrum of the currents obtained in the VBR simulation of the IM with rst harmonic space distrib ution Dynamic behavior of induction mac hines in A TP-EMTP with space harmonics (J ose Manuel Aller) Evaluation Warning : The document was created with Spire.PDF for Python.
10 ISSN: 2502-4752 Figure 7. Ev olution of the space v ector of the rotor ux linkages λ r during the startup of the IM 3.1.2. Results corr esponding to the simulation considering rst, fth, and se v enth space harmonics In Figure 8, the results obtained with the VBR model of the IM are sho wn, considering the beha vior of the rst three space harmonics. In Figure 9, the beha vior of the currents obtained is represented for the same case, considering the simulation of the rst three space harmonics. Figure 10 sho ws a detail of the steady-state currents where the presence of temporal harmonics caused by the space harmonic distrib ution in the air g ap is observ ed. Figure 8. Electrical torque and angular speed of the IM considering the rst, fth, and se v enth space harmonics Indonesian J Elec Eng & Comp Sci, V ol. 41, No. 1, January 2026: 3–17 Evaluation Warning : The document was created with Spire.PDF for Python.
Indonesian J Elec Eng & Comp Sci ISSN: 2502-4752 11 Figure 9. Currents in phases a, b, and c of the IM stator , considering the rst, fth, and se v enth harmonics Figure 11 presents the F ourier spectrum of t h e currents obtained in the simulati on , where the pres ence of the rst, fth, and se v enth temporal harmonics in the currents can be observ ed, along with their multiples, due to the space distrib ution that includes the rst, fth, and se v enth space harmonics. Finally , Figure 12 presents the de v elopment of the s pace v ectors of the rotor ux of the IM during startup, considering the rst three space harmonics. Figure 10. Detail of the steady-state currents in phases a, b, and c of the IM stator , considering the rst, fth, and se v enth harmonics Dynamic behavior of induction mac hines in A TP-EMTP with space harmonics (J ose Manuel Aller) Evaluation Warning : The document was created with Spire.PDF for Python.
12 ISSN: 2502-4752 Figure 11. F ourier spectrum of the currents obtained in the VBR simulation of the IM with space distrib ution of the rst, fth, and se v enth space harmonics Figure 12. Ev olution of the space v ector of the rotor ux linkages λ r during the startup of the IM considering the rst three space harmonics Indonesian J Elec Eng & Comp Sci, V ol. 41, No. 1, January 2026: 3–17 Evaluation Warning : The document was created with Spire.PDF for Python.