Effect of Rotor bar Shape and Stator Slot Opening on the Performance of Three Phase Squirrel Cage Induction Motors with Broken Rotor Bars
- Makhetha, Eveline, Muteba, Mbika, Nicolae, Dan-Valentin
- Authors: Makhetha, Eveline , Muteba, Mbika , Nicolae, Dan-Valentin
- Date: 2019
- Subjects: Finite Element Method , Broken rotor bars , Rotor bar shape
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/395761 , uj:32830 , Citation: Makhetha, E., Muteba, M. & Nicolae, D.V. 2019. Effect of Rotor bar Shape and Stator Slot Opening on the Performance of Three Phase Squirrel Cage Induction Motors with Broken Rotor Bars.
- Description: Abstract: Stator slot opening width has an impact on the airgap magnetic field, a poor choice of this design parameter can results in distorted airgap magnetic field and increased space harmonics. This will in turn affect the overall performance of three phase squirrel cage induction machine (SCIM). On the other hand changes in rotor bar geometry results in different resistances at various depths of the rotor bar and this yields increased or decreased electromagnetic torque. This paper aims to investigate the effect of different rotor bar types (geometrical shapes) and stator slot opening widths when a SCIM operates under healthy and broken rotor bars condition. The three phase squirrel cage induction machine is designed and modelled using two dimension (2D) finite Element Model (FEM). Static and transient analysis are performed in order to determine the target performance indexes such as transient torque, steady state torque, torque ripple, power factor and efficiency. The Finite Element Analysis (FEA) results evidence that both the rotor bar geometrical shape and stator slot opening can be optimized, such that the SCIM is yet to produce good performance when the phase shift between neighboring bars e.m.f is changed due to rotor bar breakage.
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- Authors: Makhetha, Eveline , Muteba, Mbika , Nicolae, Dan-Valentin
- Date: 2019
- Subjects: Finite Element Method , Broken rotor bars , Rotor bar shape
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/395761 , uj:32830 , Citation: Makhetha, E., Muteba, M. & Nicolae, D.V. 2019. Effect of Rotor bar Shape and Stator Slot Opening on the Performance of Three Phase Squirrel Cage Induction Motors with Broken Rotor Bars.
- Description: Abstract: Stator slot opening width has an impact on the airgap magnetic field, a poor choice of this design parameter can results in distorted airgap magnetic field and increased space harmonics. This will in turn affect the overall performance of three phase squirrel cage induction machine (SCIM). On the other hand changes in rotor bar geometry results in different resistances at various depths of the rotor bar and this yields increased or decreased electromagnetic torque. This paper aims to investigate the effect of different rotor bar types (geometrical shapes) and stator slot opening widths when a SCIM operates under healthy and broken rotor bars condition. The three phase squirrel cage induction machine is designed and modelled using two dimension (2D) finite Element Model (FEM). Static and transient analysis are performed in order to determine the target performance indexes such as transient torque, steady state torque, torque ripple, power factor and efficiency. The Finite Element Analysis (FEA) results evidence that both the rotor bar geometrical shape and stator slot opening can be optimized, such that the SCIM is yet to produce good performance when the phase shift between neighboring bars e.m.f is changed due to rotor bar breakage.
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Dynamic analysis of a novel synchronous reluctance motor with a sinusoidal anisotropic rotor
- Muteba, Mbika, Nicolae, Dan-Valentin
- Authors: Muteba, Mbika , Nicolae, Dan-Valentin
- Date: 2018
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/273068 , uj:29084 , Citation: Muteba, M. & Nicolae, D.V. 2018. Dynamic analysis of a novel synchronous reluctance motor with a sinusoidal anisotropic rotor.
- Description: Abstract: This paper deals with the dynamic analysis of a Novel Synchronous Reluctance Motor (NSynRM) having a sinusoidal rotor shape in the axial direction, without changing the flux-barriers design variables. Due to the non-self-starting characteristic of a Synchronous Reluctance Motor (SynRM), the motor is started by means of an industrial drive of ACS880 type. The motor is a 4-pole, 5.5 kW with a base speed of 1500 rpm. The practical tests are performed at three different speeds in order to analyze the dynamic responses when there is a sudden change in mechanical load characteristics. The measured results of the NSynRM are compared with those of a Standard Synchronous Reluctance Motor (SSynRM).
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- Authors: Muteba, Mbika , Nicolae, Dan-Valentin
- Date: 2018
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/273068 , uj:29084 , Citation: Muteba, M. & Nicolae, D.V. 2018. Dynamic analysis of a novel synchronous reluctance motor with a sinusoidal anisotropic rotor.
- Description: Abstract: This paper deals with the dynamic analysis of a Novel Synchronous Reluctance Motor (NSynRM) having a sinusoidal rotor shape in the axial direction, without changing the flux-barriers design variables. Due to the non-self-starting characteristic of a Synchronous Reluctance Motor (SynRM), the motor is started by means of an industrial drive of ACS880 type. The motor is a 4-pole, 5.5 kW with a base speed of 1500 rpm. The practical tests are performed at three different speeds in order to analyze the dynamic responses when there is a sudden change in mechanical load characteristics. The measured results of the NSynRM are compared with those of a Standard Synchronous Reluctance Motor (SSynRM).
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Torque per ampere enhancement of a three-phase induction motor by means of a capacitive auxiliary winding
- Muteba, Mbika, Nicolae, Dan-Valentin
- Authors: Muteba, Mbika , Nicolae, Dan-Valentin
- Date: 2018
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/273057 , uj:29083 , Citation: Muteba, M. & Nicolae, D.V. 2018. Torque per ampere enhancement of a three-phase induction motor by means of a capacitive auxiliary winding.
- Description: Abstract: This paper presents the use of a capacitive three-phase auxiliary winding to enhance the torque per ampere of a three-phase Squirrel Cage Induction Motor (SCIM) for electric traction, which generally requires high torque density, a high power factor and high efficiency. The three-phase auxiliary winding is only magnetically coupled to the stator’s main winding. A conventional 5.5-kW, 50-Hz, and 4-pole three-phase SCIM is modified to accommodate main and auxiliary windings in the stator slots. The practical results evidenced that on no-load the torque per ampere is ± 5 times higher with the presence of a capacitive auxiliary winding that utilizes 80 μF per phase.
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- Authors: Muteba, Mbika , Nicolae, Dan-Valentin
- Date: 2018
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/273057 , uj:29083 , Citation: Muteba, M. & Nicolae, D.V. 2018. Torque per ampere enhancement of a three-phase induction motor by means of a capacitive auxiliary winding.
- Description: Abstract: This paper presents the use of a capacitive three-phase auxiliary winding to enhance the torque per ampere of a three-phase Squirrel Cage Induction Motor (SCIM) for electric traction, which generally requires high torque density, a high power factor and high efficiency. The three-phase auxiliary winding is only magnetically coupled to the stator’s main winding. A conventional 5.5-kW, 50-Hz, and 4-pole three-phase SCIM is modified to accommodate main and auxiliary windings in the stator slots. The practical results evidenced that on no-load the torque per ampere is ± 5 times higher with the presence of a capacitive auxiliary winding that utilizes 80 μF per phase.
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Effect of capacitive auxiliary winding on a three- phase induction motor performance behaviour
- Muteba, Mbika, Nicolae, Dan-Valentin
- Authors: Muteba, Mbika , Nicolae, Dan-Valentin
- Date: 2017
- Subjects: Capacitive auxiliary winding , Efficiency , Power factor
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/241900 , uj:24938 , Citation: Muteba, M. & Nicolae, D.V. 2017. Effect of capacitive auxiliary winding on a three- phase induction motor performance behaviour.
- Description: Abstract: This paper investigates the effect of a capacitive three-phase auxiliary winding on the target variables of a threephase squirrel cage induction motor (SCIM). The three-phase auxiliary winding is only magnetically coupled to the stator main winding. The three-phase SCIM is modelled using 2D Finite Element Method (FEM). The flux density distribution is numerically computed through the magnetostactic solver, and the other target variables of interst such as the efficiency, power factor and torque are obtained through ac magnetic-transient solver. A conventional 4 kW, 50-Hz, and 4-pole three-phase SCIM is modified to accommodate both main and auxiliary windings in the stator slots. The results obtained from Finite Element Analysis (FEA) are compared with results from experimental measurement. From both simulation and experimental results, it is noted that the capacitive auxiliary winding has not only enhanced the power factor, but it also has a significant impact on the efficiency, torque and other electromagnetic parameters of the three-phase SCIM.
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- Authors: Muteba, Mbika , Nicolae, Dan-Valentin
- Date: 2017
- Subjects: Capacitive auxiliary winding , Efficiency , Power factor
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/241900 , uj:24938 , Citation: Muteba, M. & Nicolae, D.V. 2017. Effect of capacitive auxiliary winding on a three- phase induction motor performance behaviour.
- Description: Abstract: This paper investigates the effect of a capacitive three-phase auxiliary winding on the target variables of a threephase squirrel cage induction motor (SCIM). The three-phase auxiliary winding is only magnetically coupled to the stator main winding. The three-phase SCIM is modelled using 2D Finite Element Method (FEM). The flux density distribution is numerically computed through the magnetostactic solver, and the other target variables of interst such as the efficiency, power factor and torque are obtained through ac magnetic-transient solver. A conventional 4 kW, 50-Hz, and 4-pole three-phase SCIM is modified to accommodate both main and auxiliary windings in the stator slots. The results obtained from Finite Element Analysis (FEA) are compared with results from experimental measurement. From both simulation and experimental results, it is noted that the capacitive auxiliary winding has not only enhanced the power factor, but it also has a significant impact on the efficiency, torque and other electromagnetic parameters of the three-phase SCIM.
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Effect of rotor bar shape on the performance of three phase induction motors with broken rotor bars
- Maloma, Evelin, Muteba, Mbika, Nicolae, Dan-Valentin
- Authors: Maloma, Evelin , Muteba, Mbika , Nicolae, Dan-Valentin
- Date: 2017
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/240299 , uj:24720 , Citation: Maloma, E., Muteba, M. & Nicolae, D.V. 2017. Effect of rotor bar shape on the performance of three phase induction motors with broken rotor bars.
- Description: Abstract: A slight change in time phase shift between currents in adjacent rotor end ring segments directly affects the characteristics of the airgap torque in a squirrel cage induction machine (SCIM). On the other hand the rotor slot geometrical permeance has a strong impact on the rotor bar leakage inductance. This paper deals with effect of different rotor bar types (geometrical shapes) when a SCIM operates under healthy and broken rotor bars condition. The three phase squirrel cage induction machine is designed and modelled using two dimension (2D) finite Element Model (FEM). Static and dynamic analysis are performed in order to determine the target performance indexes such as transient torque, steady state torque, torque ripple, air-gap flux density, power factor and efficiency. The Finite Element Analysis (FEA) results evidence that the rotor bar shape can be optimized, such that the SCIM is yet to produce good performance when the phase shift between neighbouring bars e.m.f is changed due to rotor bar breakage.
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- Authors: Maloma, Evelin , Muteba, Mbika , Nicolae, Dan-Valentin
- Date: 2017
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/240299 , uj:24720 , Citation: Maloma, E., Muteba, M. & Nicolae, D.V. 2017. Effect of rotor bar shape on the performance of three phase induction motors with broken rotor bars.
- Description: Abstract: A slight change in time phase shift between currents in adjacent rotor end ring segments directly affects the characteristics of the airgap torque in a squirrel cage induction machine (SCIM). On the other hand the rotor slot geometrical permeance has a strong impact on the rotor bar leakage inductance. This paper deals with effect of different rotor bar types (geometrical shapes) when a SCIM operates under healthy and broken rotor bars condition. The three phase squirrel cage induction machine is designed and modelled using two dimension (2D) finite Element Model (FEM). Static and dynamic analysis are performed in order to determine the target performance indexes such as transient torque, steady state torque, torque ripple, air-gap flux density, power factor and efficiency. The Finite Element Analysis (FEA) results evidence that the rotor bar shape can be optimized, such that the SCIM is yet to produce good performance when the phase shift between neighbouring bars e.m.f is changed due to rotor bar breakage.
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Influence of mixed winding arrangements on torque ripples offive-phase induction machines
- Muteba, Mbika, Nicolae, Dan-Valentin
- Authors: Muteba, Mbika , Nicolae, Dan-Valentin
- Date: 2017
- Subjects: Five-phase induction machines , Phase-belt , Winding combinations
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/269704 , uj:28654 , Citation: Muteba, M. & Nicolae, D.V. 2017. Influence of mixed winding arrangements on torque ripples offive-phase induction machines. Electric Power Systems Research 151 (2017) 154-165
- Description: Abstract: In this paper, the authors take a particular look at the influence of mixed stator winding arrangementson torque ripple production in a 30 stator slots, 2-pole, and five-phase induction machine. The con-ventional five-phase double layer windings with 14/15 and 13/15 chorded coils are compared with theproposed five-phase mixed winding arrangements. This paper presents the design consideration andcalculation of winding factors of the proposed mixed winding configurations. The different five-phasewinding arrangements have been modelled using Finite Element Methods. The results obtained from sim-ulation are compared to those obtained from experimental measurements. Both simulation and practicalresults have proven that the combination of double and triple layer winding, mixed with coil side shiftto other layer, has tremendously reduced the torque ripple factor while maintaining the torque average.
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- Authors: Muteba, Mbika , Nicolae, Dan-Valentin
- Date: 2017
- Subjects: Five-phase induction machines , Phase-belt , Winding combinations
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/269704 , uj:28654 , Citation: Muteba, M. & Nicolae, D.V. 2017. Influence of mixed winding arrangements on torque ripples offive-phase induction machines. Electric Power Systems Research 151 (2017) 154-165
- Description: Abstract: In this paper, the authors take a particular look at the influence of mixed stator winding arrangementson torque ripple production in a 30 stator slots, 2-pole, and five-phase induction machine. The con-ventional five-phase double layer windings with 14/15 and 13/15 chorded coils are compared with theproposed five-phase mixed winding arrangements. This paper presents the design consideration andcalculation of winding factors of the proposed mixed winding configurations. The different five-phasewinding arrangements have been modelled using Finite Element Methods. The results obtained from sim-ulation are compared to those obtained from experimental measurements. Both simulation and practicalresults have proven that the combination of double and triple layer winding, mixed with coil side shiftto other layer, has tremendously reduced the torque ripple factor while maintaining the torque average.
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Investigation into effects of a novel rotor cut-off design for synchronous reluctance machines
- Doorsamy, W., Muteba, M., Twala, B., Nicolae, Dan-Valentin
- Authors: Doorsamy, W. , Muteba, M. , Twala, B. , Nicolae, Dan-Valentin
- Date: 2017
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/237805 , uj:24371 , Citation: Doorsamy, W. et al. 2017. Investigation into effects of a novel rotor cut-off design for synchronous reluctance machines.
- Description: Abstract: This paper presents an investigation into the effects of a novel rotor cut-off design on the performance of a synchronous reluctance machine. The rotor design consists of a sinusoidal lamination shape in the axial direction thereby varying the magnetic flux in the q-axis direction and reducing torque harmonics due to slotting effects. The presented study uses single-factor experimental design, with Analysis of Variance (ANOVA), and Finite Element Analysis (FEA) to quantitatively and qualitatively assess the effects of the rotor cut-off on the torque, torque ripple, saliency, power factor and efficiency of the machine. Results of the investigation indicate that although variation in the rotor cut-off design significantly reduces the torque ripple, the effects on the average output torque, saliency, power factor of the machine are relatively insignificant. Index Terms—Synchronous Reluctance Machine; Rotor Design; ANOVA; FEA.
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- Authors: Doorsamy, W. , Muteba, M. , Twala, B. , Nicolae, Dan-Valentin
- Date: 2017
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/237805 , uj:24371 , Citation: Doorsamy, W. et al. 2017. Investigation into effects of a novel rotor cut-off design for synchronous reluctance machines.
- Description: Abstract: This paper presents an investigation into the effects of a novel rotor cut-off design on the performance of a synchronous reluctance machine. The rotor design consists of a sinusoidal lamination shape in the axial direction thereby varying the magnetic flux in the q-axis direction and reducing torque harmonics due to slotting effects. The presented study uses single-factor experimental design, with Analysis of Variance (ANOVA), and Finite Element Analysis (FEA) to quantitatively and qualitatively assess the effects of the rotor cut-off on the torque, torque ripple, saliency, power factor and efficiency of the machine. Results of the investigation indicate that although variation in the rotor cut-off design significantly reduces the torque ripple, the effects on the average output torque, saliency, power factor of the machine are relatively insignificant. Index Terms—Synchronous Reluctance Machine; Rotor Design; ANOVA; FEA.
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Novel synchronous reluctance motor with sinusoidal rotor lamination shape for less torque ripple contents
- Muteba, M., Twala, B., Nicolae, Dan-Valentin
- Authors: Muteba, M. , Twala, B. , Nicolae, Dan-Valentin
- Date: 2017
- Subjects: High average torque , Low torque ripple , Synchronous reluctance motor
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/269712 , uj:28655 , Citation: Muteba, M., Twala, B. & Nicolae, D.V. 2017. Novel synchronous reluctance motor with sinusoidal rotor lamination shape for less torque ripple contents.
- Description: Abstract: This paper presents the analysis of a novel Synchronous Reluctance Motor (SynRM), which has an axially sinusoidal rotor lamination shape. The sinusoidal lamination shape is used to vary magnetic flux in the q-axis direction. Therefore, cancelling some torque harmonics produced by stator slotting effects and rotor anisotropy, while maintaining the average torque. The stator of a 5.5 kW, 4-pole, 50 Hz conventional three-phase squirrel cage induction motor, with distributed and chorded by one slot, double layer winding, is used for both standard and novel motors. The Finite Element Analysis (FEM) is used to study the electromagnetic parameters of interests. The FEA results are validated by means of practical measurements. The results obtained from both FEA and practical measurements evidenced that the novel SynRM dropped tremendously the torque ripple contents while still maintained the average torque. The drop in torque ripple contents is mainly due to mitigation of the most dominant torque harmonics caused by stator slotting and rotor anisotropy.
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- Authors: Muteba, M. , Twala, B. , Nicolae, Dan-Valentin
- Date: 2017
- Subjects: High average torque , Low torque ripple , Synchronous reluctance motor
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/269712 , uj:28655 , Citation: Muteba, M., Twala, B. & Nicolae, D.V. 2017. Novel synchronous reluctance motor with sinusoidal rotor lamination shape for less torque ripple contents.
- Description: Abstract: This paper presents the analysis of a novel Synchronous Reluctance Motor (SynRM), which has an axially sinusoidal rotor lamination shape. The sinusoidal lamination shape is used to vary magnetic flux in the q-axis direction. Therefore, cancelling some torque harmonics produced by stator slotting effects and rotor anisotropy, while maintaining the average torque. The stator of a 5.5 kW, 4-pole, 50 Hz conventional three-phase squirrel cage induction motor, with distributed and chorded by one slot, double layer winding, is used for both standard and novel motors. The Finite Element Analysis (FEM) is used to study the electromagnetic parameters of interests. The FEA results are validated by means of practical measurements. The results obtained from both FEA and practical measurements evidenced that the novel SynRM dropped tremendously the torque ripple contents while still maintained the average torque. The drop in torque ripple contents is mainly due to mitigation of the most dominant torque harmonics caused by stator slotting and rotor anisotropy.
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Optimal modelling of planar thermal converter device
- Golovins, E., Nicolae, Dan-Valentin
- Authors: Golovins, E. , Nicolae, Dan-Valentin
- Date: 2017
- Subjects: Thermal converter , Thermoelectric sensor , Thermal transfer
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/247438 , uj:25691 , Citation: Golovins, E. & Nicolae, D.V. 2017. Optimal modelling of planar thermal converter device.
- Description: Abstract: The root mean square (rms) measurement of alternating voltage of any waveform is frequently done by means of thermal transfer instruments. The principle of these thermal rms converters is to transfer the heating energy of resistive load to a temperature-sensing element. The dc voltage output of the sensor reflects the amount of electrical power (ac or dc) applied to the input. This paper is addressing the modelling of a thermal converter device in planar technology using finite element platform. The original approach of this study capitalizes on introduction of a resistive thermal sensing element of a planar type to provision the thermal-conversion response to the active power dissipated on the 3D stratified non-reactive heater structure. Through iterative multi-physics simulations, model properties and dimensions have been evaluated and optimized.
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- Authors: Golovins, E. , Nicolae, Dan-Valentin
- Date: 2017
- Subjects: Thermal converter , Thermoelectric sensor , Thermal transfer
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/247438 , uj:25691 , Citation: Golovins, E. & Nicolae, D.V. 2017. Optimal modelling of planar thermal converter device.
- Description: Abstract: The root mean square (rms) measurement of alternating voltage of any waveform is frequently done by means of thermal transfer instruments. The principle of these thermal rms converters is to transfer the heating energy of resistive load to a temperature-sensing element. The dc voltage output of the sensor reflects the amount of electrical power (ac or dc) applied to the input. This paper is addressing the modelling of a thermal converter device in planar technology using finite element platform. The original approach of this study capitalizes on introduction of a resistive thermal sensing element of a planar type to provision the thermal-conversion response to the active power dissipated on the 3D stratified non-reactive heater structure. Through iterative multi-physics simulations, model properties and dimensions have been evaluated and optimized.
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Performance indexes’ evaluation of a novel synchronous reluctance motor with sinusoidal rotor shape
- Muteba, M., Twala, B., Nicolae, Dan-Valentin
- Authors: Muteba, M. , Twala, B. , Nicolae, Dan-Valentin
- Date: 2017
- Subjects: Enhanced performance indexes , Low torque ripple , Novel rotor with sinusoidal shape
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/269720 , uj:28656 , Citation: Muteba, M., Twala, B. & Nicolae, D.V. 2017. Performance indexes’ evaluation of a novel synchronous reluctance motor with sinusoidal rotor shape.
- Description: Abstract: This paper presents the evaluation of performance indexes of a novel Synchronous Reluctance Motor (SynRM), which has an axially sinusoidal rotor lamination shape. The stator of a 5.5 kW, 4-pole, 50 Hz conventional three-phase squirrel cage induction motor, with distributed and chorded by one slot, double layer winding, is used for both standard and novel synchronous reluctance motors. Due to the nature of the sinusoidal rotor structure, the 3D Finite Element Analysis (FEA) is utilized to study the electromagnetic parameters of interests. The SynRM with sinusoidal rotor shape results are compared with the standard SynRM without cut-off on the q-axis. The FEA results are validated by means of practical measurements. From both FEA and measured results, it is evident that the novel SynRM enhances the performance indexes of interests such as torque density, torque ripple factor and efficiency.
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- Authors: Muteba, M. , Twala, B. , Nicolae, Dan-Valentin
- Date: 2017
- Subjects: Enhanced performance indexes , Low torque ripple , Novel rotor with sinusoidal shape
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/269720 , uj:28656 , Citation: Muteba, M., Twala, B. & Nicolae, D.V. 2017. Performance indexes’ evaluation of a novel synchronous reluctance motor with sinusoidal rotor shape.
- Description: Abstract: This paper presents the evaluation of performance indexes of a novel Synchronous Reluctance Motor (SynRM), which has an axially sinusoidal rotor lamination shape. The stator of a 5.5 kW, 4-pole, 50 Hz conventional three-phase squirrel cage induction motor, with distributed and chorded by one slot, double layer winding, is used for both standard and novel synchronous reluctance motors. Due to the nature of the sinusoidal rotor structure, the 3D Finite Element Analysis (FEA) is utilized to study the electromagnetic parameters of interests. The SynRM with sinusoidal rotor shape results are compared with the standard SynRM without cut-off on the q-axis. The FEA results are validated by means of practical measurements. From both FEA and measured results, it is evident that the novel SynRM enhances the performance indexes of interests such as torque density, torque ripple factor and efficiency.
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Transient analysis of a start-up synchronous reluctance motor with symmetrical distributed rotor cage bars
- Aguba, Vitalis, Muteba, Mbika, Nicolae, Dan-Valentin
- Authors: Aguba, Vitalis , Muteba, Mbika , Nicolae, Dan-Valentin
- Date: 2017
- Subjects: Efficiency , Power Factor , Finite Element Method
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/242202 , uj:24975 , Citation: Aguba, V. Muteba, M. & Nicolae, D.V. 2017. Transient analysis of a start-up synchronous reluctance motor with symmetrical distributed rotor cage bars.
- Description: Abstract: In this paper, a start-up synchronous reluctance motor (SynRM) is modelled using the approach of 2D Finite Element Method (FEM). Finite Element Analysis (FEA) approach is used to analyze the synchronized and unsynchronized behavior of a synchronous motor with the application of cage bars in the rotor structure for transient characteristics. Two SynRMs (1 and 2) are modelled. Both are compared in terms of starting and synchronizing on load and on no-load. Again the variables (Efficiency and power Factor) of both machines were calculated and compared. Only SynRM2 is used to investigate the variation of applied voltages. The simulated results shows at which supply voltage can the motor stabilized and also the parameters that was taken into account for proper stabilization.
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- Authors: Aguba, Vitalis , Muteba, Mbika , Nicolae, Dan-Valentin
- Date: 2017
- Subjects: Efficiency , Power Factor , Finite Element Method
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/242202 , uj:24975 , Citation: Aguba, V. Muteba, M. & Nicolae, D.V. 2017. Transient analysis of a start-up synchronous reluctance motor with symmetrical distributed rotor cage bars.
- Description: Abstract: In this paper, a start-up synchronous reluctance motor (SynRM) is modelled using the approach of 2D Finite Element Method (FEM). Finite Element Analysis (FEA) approach is used to analyze the synchronized and unsynchronized behavior of a synchronous motor with the application of cage bars in the rotor structure for transient characteristics. Two SynRMs (1 and 2) are modelled. Both are compared in terms of starting and synchronizing on load and on no-load. Again the variables (Efficiency and power Factor) of both machines were calculated and compared. Only SynRM2 is used to investigate the variation of applied voltages. The simulated results shows at which supply voltage can the motor stabilized and also the parameters that was taken into account for proper stabilization.
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An approach to quantify the technical impact of power quality in medium voltage distribution systems
- Dlamini, F. M., Nicolae, Dan-Valentin
- Authors: Dlamini, F. M. , Nicolae, Dan-Valentin
- Date: 2016
- Subjects: Power factor correction , Total harmonic distortion , Resonance
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/212857 , uj:21036 , Citation: Dlamini, F.M & Nicolae, D.V. 2016. An approach to quantify the technical impact of power quality in medium voltage distribution systems.
- Description: Abstract: This paper provides a useful guidance in the interpretation and analyses of the technical impact of power factor correction in a power system. It is intended to raise awareness in order to achieve correct measurements, calculations and the key dynamics of the power system when quantifying the impact of power quality (PQ) in a non-linear power system. This paper is therefore targeting the power producing utilities, municipalities and the bulk end users of electricity.
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An approach to quantify the technical impact of power quality in medium voltage distribution systems
- Authors: Dlamini, F. M. , Nicolae, Dan-Valentin
- Date: 2016
- Subjects: Power factor correction , Total harmonic distortion , Resonance
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/212857 , uj:21036 , Citation: Dlamini, F.M & Nicolae, D.V. 2016. An approach to quantify the technical impact of power quality in medium voltage distribution systems.
- Description: Abstract: This paper provides a useful guidance in the interpretation and analyses of the technical impact of power factor correction in a power system. It is intended to raise awareness in order to achieve correct measurements, calculations and the key dynamics of the power system when quantifying the impact of power quality (PQ) in a non-linear power system. This paper is therefore targeting the power producing utilities, municipalities and the bulk end users of electricity.
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Characterization and modeling of an RMS-DC solid-state thermal converter
- Nicolae, Dan-Valentin, Golovins, E.
- Authors: Nicolae, Dan-Valentin , Golovins, E.
- Date: 2016
- Subjects: Thermal converter , Thermoelectric sensor , Thermal transfer
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/213823 , uj:21201 , Citation: Nicolae, D.V & Golovins, E. 2016. Characterization and modeling of an RMS-DC solid-state thermal converter.
- Description: Abstract: The Root Mean Square (rms) measurements of alternating signal of any waveform are frequently done by means of thermal transfer instruments. The principle of these thermal transfer instruments is to transfer the heating energy of resistive load to a temperature-sensing element. The DC output of the sensor reflects the amount of electrical power (ac or dc) applied to the input. The paper addresses the characterization and modelling of an RMS-DC thermal converter of a solid state technology type at various frequencies. The theoretical and simulation analysis is carried out to outline the factors influencing the transfer characteristics of the converter device in the dc and ac input regimes.
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- Authors: Nicolae, Dan-Valentin , Golovins, E.
- Date: 2016
- Subjects: Thermal converter , Thermoelectric sensor , Thermal transfer
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/213823 , uj:21201 , Citation: Nicolae, D.V & Golovins, E. 2016. Characterization and modeling of an RMS-DC solid-state thermal converter.
- Description: Abstract: The Root Mean Square (rms) measurements of alternating signal of any waveform are frequently done by means of thermal transfer instruments. The principle of these thermal transfer instruments is to transfer the heating energy of resistive load to a temperature-sensing element. The DC output of the sensor reflects the amount of electrical power (ac or dc) applied to the input. The paper addresses the characterization and modelling of an RMS-DC thermal converter of a solid state technology type at various frequencies. The theoretical and simulation analysis is carried out to outline the factors influencing the transfer characteristics of the converter device in the dc and ac input regimes.
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Diagnostic methods of frequency response analysis for power transformer winding a review
- Nnachi, G. U., Nicolae, Dan-Valentin
- Authors: Nnachi, G. U. , Nicolae, Dan-Valentin
- Date: 2016
- Subjects: Power transformers , Diagnostic methods , Frequency response analysis
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/212835 , uj:21033 , Citation: Nnachi, G.V & Nicolae, D.V. 2016. Diagnostic methods of frequency response analysis for power transformer winding a review.
- Description: Abstract: Monitoring and diagnosis of power transformers in power systems have been investigated and discussed for the past decades. Earlier detect power transformer winding failures is recommended for both manufacturing process and also for power system operators. One of the most powerful and accurate tool for sufficient winding deformation detection is considered Frequency Response Analysis (FRA) among other diagnostic methods. In this paper a review of diagnostic methods of FRA for power transformer winding are presented. Different methods of transformer winding diagnosis, with their benefits and drawbacks where investigated. Moreover, possible windings failures, diagnostic methods of FRA in Off-line and On-line power transformers, detailed advantages and disadvantages of two major types of FRA are presented. The paper was able to show that some uncertainties have not been eliminated completely.
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- Authors: Nnachi, G. U. , Nicolae, Dan-Valentin
- Date: 2016
- Subjects: Power transformers , Diagnostic methods , Frequency response analysis
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/212835 , uj:21033 , Citation: Nnachi, G.V & Nicolae, D.V. 2016. Diagnostic methods of frequency response analysis for power transformer winding a review.
- Description: Abstract: Monitoring and diagnosis of power transformers in power systems have been investigated and discussed for the past decades. Earlier detect power transformer winding failures is recommended for both manufacturing process and also for power system operators. One of the most powerful and accurate tool for sufficient winding deformation detection is considered Frequency Response Analysis (FRA) among other diagnostic methods. In this paper a review of diagnostic methods of FRA for power transformer winding are presented. Different methods of transformer winding diagnosis, with their benefits and drawbacks where investigated. Moreover, possible windings failures, diagnostic methods of FRA in Off-line and On-line power transformers, detailed advantages and disadvantages of two major types of FRA are presented. The paper was able to show that some uncertainties have not been eliminated completely.
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Effect of double-triple winding layout on axially-laminated anisotropic rotor synchronous reluctance motors
- Muteba, M., Twala, B., Nicolae, Dan-Valentin
- Authors: Muteba, M. , Twala, B. , Nicolae, Dan-Valentin
- Date: 2016
- Subjects: Average torque, , Axially-laminated anisotropic rotor , Double-triple winding layout
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/123619 , uj:20819 , Citation: Muteba, M., Twala, B. & Nicolae, D.V. 2016. Effect of double-triple winding layout on axially-laminated anisotropic rotor synchronous reluctance motors.
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- Authors: Muteba, M. , Twala, B. , Nicolae, Dan-Valentin
- Date: 2016
- Subjects: Average torque, , Axially-laminated anisotropic rotor , Double-triple winding layout
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/123619 , uj:20819 , Citation: Muteba, M., Twala, B. & Nicolae, D.V. 2016. Effect of double-triple winding layout on axially-laminated anisotropic rotor synchronous reluctance motors.
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Effect of rotor barrier pitch angle on torque ripple production in synchronous reluctance machines
- Muteba, Mbika, Twala, Bhekisipho, Nicolae, Dan-Valentin
- Authors: Muteba, Mbika , Twala, Bhekisipho , Nicolae, Dan-Valentin
- Date: 2016
- Subjects: Barrier pitch angle , Synchronous reluctance machines , Torque density
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/123832 , uj:20841 , Citation: Muteba, M., Twala, B & Nicolae, D.V. 2016. Effect of rotor barrier pitch angle on torque ripple production in synchronous reluctance machines.
- Description: Abstract: This paper analyses the effect of rotor barrier pitch angles on torque ripple production in Synchronous Reluctance Machines (SynRMs), with the objective to reduce torque ripple contents in medium size ground Electric Vehicles (EVs). While keeping major-design parameters constant, the barrier pitch angle is varied by a quarter of the stator slot pitch. Three SynRMs having different rotor barrier pitch angles are designed and modeled using 2D Finite Element Method (FEM). The specifications of a traditional 5.5 kW, three-phase, 50 Hz, induction machine are used to design and model the SynRMs. Torque ripple reduction of ± 48 % is achieved for barrier pitch angles of 15o and 17.5o mech, when the machines operate at current space phasor angle of 45o electric.
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- Authors: Muteba, Mbika , Twala, Bhekisipho , Nicolae, Dan-Valentin
- Date: 2016
- Subjects: Barrier pitch angle , Synchronous reluctance machines , Torque density
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/123832 , uj:20841 , Citation: Muteba, M., Twala, B & Nicolae, D.V. 2016. Effect of rotor barrier pitch angle on torque ripple production in synchronous reluctance machines.
- Description: Abstract: This paper analyses the effect of rotor barrier pitch angles on torque ripple production in Synchronous Reluctance Machines (SynRMs), with the objective to reduce torque ripple contents in medium size ground Electric Vehicles (EVs). While keeping major-design parameters constant, the barrier pitch angle is varied by a quarter of the stator slot pitch. Three SynRMs having different rotor barrier pitch angles are designed and modeled using 2D Finite Element Method (FEM). The specifications of a traditional 5.5 kW, three-phase, 50 Hz, induction machine are used to design and model the SynRMs. Torque ripple reduction of ± 48 % is achieved for barrier pitch angles of 15o and 17.5o mech, when the machines operate at current space phasor angle of 45o electric.
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Modelling and analysis of a radio frequency dielectric heating for defatted soy flour
- Van der Walt, H. P., Paul, B. S., Nicolae, Dan-Valentin
- Authors: Van der Walt, H. P. , Paul, B. S. , Nicolae, Dan-Valentin
- Date: 2016
- Subjects: Dielectric heating , Soy flour , Class E amplifier
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/213845 , uj:21203 , Citation: Van der Walt, H.P., Paul, B.S & Nicolae, D.V. 2016. Modelling and analysis of a radio frequency dielectric heating for defatted soy flour.
- Description: Abstract: In this paper a Radio Frequency (RF) method for drying defeated soy flower is developed using a class E amplifier. The raw and uncooked soy flour contains a few undesirable inherent soybean enzymes. Minimizing the content and effect of these enzymes usually is done through “drying/heating” methods. The method used in this study is “RF dielectric heating”. Modelling, simulation and implementation results complete the paper.
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- Authors: Van der Walt, H. P. , Paul, B. S. , Nicolae, Dan-Valentin
- Date: 2016
- Subjects: Dielectric heating , Soy flour , Class E amplifier
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/213845 , uj:21203 , Citation: Van der Walt, H.P., Paul, B.S & Nicolae, D.V. 2016. Modelling and analysis of a radio frequency dielectric heating for defatted soy flour.
- Description: Abstract: In this paper a Radio Frequency (RF) method for drying defeated soy flower is developed using a class E amplifier. The raw and uncooked soy flour contains a few undesirable inherent soybean enzymes. Minimizing the content and effect of these enzymes usually is done through “drying/heating” methods. The method used in this study is “RF dielectric heating”. Modelling, simulation and implementation results complete the paper.
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Modelling and analysis of RMS-DC solid state thermal converter
- Hlakola, Mmatselagale M., Nicolae, Dan-Valentin, Golovins, Eugene
- Authors: Hlakola, Mmatselagale M. , Nicolae, Dan-Valentin , Golovins, Eugene
- Date: 2016
- Subjects: Thermal converter , Thermoelectric sensor , Thermal transfer
- Language: English
- Type: Conference proceedings
- Identifier: http://ujcontent.uj.ac.za8080/10210/365744 , http://hdl.handle.net/10210/212684 , uj:21007 , Citation: Hlakola, M.M., Nicolae, D.V. & Golovins, E. 2016. Modelling and analysis of RMS-DC solid state thermal converter.
- Description: Abstract: The Root Mean Square (RMS) measurements of alternating signal are frequently done by means of thermal transfer instruments. The principle of these thermal transfer instruments is to transfer the heating energy of resistive load to a temperature-sensing element. The DC output of the sensor gauges the amount of electrical power (AC or DC) applied to the input. The paper examines performance of an RMS-DC thermal converter of a solid state technology type at various frequencies such as LT1088CD integrated circuit. The theoretical and simulation analysis is carried out to outline the factors influencing the transfer characteristics of the converter device in the DC and AC input regimes.
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- Authors: Hlakola, Mmatselagale M. , Nicolae, Dan-Valentin , Golovins, Eugene
- Date: 2016
- Subjects: Thermal converter , Thermoelectric sensor , Thermal transfer
- Language: English
- Type: Conference proceedings
- Identifier: http://ujcontent.uj.ac.za8080/10210/365744 , http://hdl.handle.net/10210/212684 , uj:21007 , Citation: Hlakola, M.M., Nicolae, D.V. & Golovins, E. 2016. Modelling and analysis of RMS-DC solid state thermal converter.
- Description: Abstract: The Root Mean Square (RMS) measurements of alternating signal are frequently done by means of thermal transfer instruments. The principle of these thermal transfer instruments is to transfer the heating energy of resistive load to a temperature-sensing element. The DC output of the sensor gauges the amount of electrical power (AC or DC) applied to the input. The paper examines performance of an RMS-DC thermal converter of a solid state technology type at various frequencies such as LT1088CD integrated circuit. The theoretical and simulation analysis is carried out to outline the factors influencing the transfer characteristics of the converter device in the DC and AC input regimes.
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Statistical analysis of operating times of high voltage SF6 circuit breakers
- Mabunda, N., Bokoro, P., Nicolae, Dan-Valentin
- Authors: Mabunda, N. , Bokoro, P. , Nicolae, Dan-Valentin
- Date: 2016
- Subjects: Circuit breakers , Hypothesis testing
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/123312 , uj:20775 , Citation: Mabunda, N., Bokoro, P & Nicolae, D. 2016. Statistical analysis of operating times of high voltage SF6 circuit breakers.
- Description: Abstract: In this paper the operating times of high voltage SF6 live tank circuit breakers are tested using standard timing tests. The time measurements obtained have proven to be adequate to the normal distribution. The hypothesis testing methodology is applied in order to determine the mean difference value between the tested phase operating times. The results obtained showed that the time difference between the operating times of the tested circuit breakers is located between - 0.661 and 0.536 ms, which indicates that the operating mechanism of the breakers is still reliable and in good condition.
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- Authors: Mabunda, N. , Bokoro, P. , Nicolae, Dan-Valentin
- Date: 2016
- Subjects: Circuit breakers , Hypothesis testing
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/123312 , uj:20775 , Citation: Mabunda, N., Bokoro, P & Nicolae, D. 2016. Statistical analysis of operating times of high voltage SF6 circuit breakers.
- Description: Abstract: In this paper the operating times of high voltage SF6 live tank circuit breakers are tested using standard timing tests. The time measurements obtained have proven to be adequate to the normal distribution. The hypothesis testing methodology is applied in order to determine the mean difference value between the tested phase operating times. The results obtained showed that the time difference between the operating times of the tested circuit breakers is located between - 0.661 and 0.536 ms, which indicates that the operating mechanism of the breakers is still reliable and in good condition.
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Torque ripple minimization in synchronous reluctance motor using a sinusoidal rotor lamination shape
- Muteba, M., Twala, B., Nicolae, Dan-Valentin
- Authors: Muteba, M. , Twala, B. , Nicolae, Dan-Valentin
- Date: 2016
- Subjects: Finite element method (FEM) , Sinusoidal rotor lamination shape , Synchronous reluctance motors
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/123701 , uj:20829 , Citation: Muteba, M., Twala, B & Nicolae, D.V. 2016. Torque ripple minimization in synchronous reluctance motor using a sinusoidal rotor lamination shape.
- Description: Abstract: A Synchronous Reluctance Motor (SynRM), which has sinusoidal rotor lamination shape in the axial direction, is proposed. The sinusoidal lamination shape is utilized to vary the magnetic flux in the q-axis direction. Therefore, cancelling some torque harmonics produced by slotting effects. The stator geometry of a 1.5 kW, conventional three-phase squirrel cage induction motor, with distributed double layer winding, chorded by one slot, is used for both basic and proposed models. Due to the axial geometry design of sinusoidal lamination shape for the proposed model, 3-D Finite Element Method (FEM) is used for dynamic analysis. From the FEM results, it evidenced that with current vector angle of 45oelectric, the proposed model reduced the torque ripple content by more than 60 % and still maintained the average torque.
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Torque ripple minimization in synchronous reluctance motor using a sinusoidal rotor lamination shape
- Authors: Muteba, M. , Twala, B. , Nicolae, Dan-Valentin
- Date: 2016
- Subjects: Finite element method (FEM) , Sinusoidal rotor lamination shape , Synchronous reluctance motors
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/123701 , uj:20829 , Citation: Muteba, M., Twala, B & Nicolae, D.V. 2016. Torque ripple minimization in synchronous reluctance motor using a sinusoidal rotor lamination shape.
- Description: Abstract: A Synchronous Reluctance Motor (SynRM), which has sinusoidal rotor lamination shape in the axial direction, is proposed. The sinusoidal lamination shape is utilized to vary the magnetic flux in the q-axis direction. Therefore, cancelling some torque harmonics produced by slotting effects. The stator geometry of a 1.5 kW, conventional three-phase squirrel cage induction motor, with distributed double layer winding, chorded by one slot, is used for both basic and proposed models. Due to the axial geometry design of sinusoidal lamination shape for the proposed model, 3-D Finite Element Method (FEM) is used for dynamic analysis. From the FEM results, it evidenced that with current vector angle of 45oelectric, the proposed model reduced the torque ripple content by more than 60 % and still maintained the average torque.
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