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Electric Machines & Control Application (CN 31-1959/TM, ISSN 1673-6540) was founded in 1959 in title of Technical Information of Small and Medium-sized Electric Machines. The title was changed to Small and Medium-sized Electric Machines in 1977, and then changed to its current title in 2005. The journal is sponsored by Shanghai Electrical Apparatus Research Institute (Group) Co., Ltd., aims to publish cutting-edge achievements in various research fields related to the electrical science. The journal is a source journal of the Comprehensive Evaluation Database of Chinese Academic Journals, and the full text articles are included in Chinese Academic Journals (CD). It has been included in Chinese Core Journals and Key Magazine of China Technology for years. Recently, it has also been included in Scopus, EBSCO, DOAJ, EuroPub, Research4Life, ICI world of Jourmals, ICI Journal Master Lister, Japan Science and Technology Agency database (JST, Japan) and Abstract Journals (AJ, Russia). The impact factor is steadily increasing year by year. Electric Machines and Control Application is published on the 10th of each month and is publicly distributed domestically and internationally. The post issuing code is 4-199.
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2026,53(5):420-431, DOI: 10.12177/emca.2026.167
Abstract:
[Objective] With the rapid development of new energy, the weak anti-interference capability of new energy inverters intensifies the risk of cascading grid disconnection after fault disturbances, posing new challenges to current risk prevention and control technologies for protection. This paper investigates the cycle-by-cycle (CBC) current limiting control methods for the fault condition of active neutral point clamped (ANPC) inverters when an AC side short circuit occurs. [Methods] In traditional CBC current limiting control methods, all switching devices of the inverter were turned off when the current exceeded the over-current threshold. However, this frequently triggered current limiting control, resulting in high current change rate di/dt of switching devices, and excessive current flowing through the anti-parallel diode of the insulated gate bipolar transistor (IGBT), which failed to effectively protect the switching devices in the inverter. Between the control strategy of forcibly turning off all switching devices and the new energy grid disconnection accidents caused by allowing over-current to develop, this paper proposed a technology that controlled the inverter in an intermediate state—partial-switching-off CBC "soft" current limiting control technology. When the control was triggered, the specified switching devices were turned off while the remaining ones were kept on. Finally, a simulation model was established using MATLAB/Simulink to verify the proposed CBC current limiting control method. [Results] The results indicated that this method could effectively reduce the number of triggers, lower the di/dt of the switching devices, and decrease the current peak value of the internal switching devices in the inverter, thereby enhancing the reliability of the inverter. Compared with the full-switching-off CBC current limiting method, the trigger cycles of the partial-switching-off CBC "soft" current limiting were longer, and the trigger frequency was lower. Moreover, the CBC "soft" current limiting method limited the peak current of the switching devices to a lower level, which was beneficial for improving the reliability of the inverter and optimizing the CBC current limiting control method. [Conclusion] The proposed CBC "soft" current limiting control method for ANPC inverters can effectively control inverter current under short-circuit faults, improve the inverter’s short-circuit fault ride-through capability, and provide technical support for the safe operation of new energy grid connection.
[Objective] With the rapid development of new energy, the weak anti-interference capability of new energy inverters intensifies the risk of cascading grid disconnection after fault disturbances, posing new challenges to current risk prevention and control technologies for protection. This paper investigates the cycle-by-cycle (CBC) current limiting control methods for the fault condition of active neutral point clamped (ANPC) inverters when an AC side short circuit occurs. [Methods] In traditional CBC current limiting control methods, all switching devices of the inverter were turned off when the current exceeded the over-current threshold. However, this frequently triggered current limiting control, resulting in high current change rate di/dt of switching devices, and excessive current flowing through the anti-parallel diode of the insulated gate bipolar transistor (IGBT), which failed to effectively protect the switching devices in the inverter. Between the control strategy of forcibly turning off all switching devices and the new energy grid disconnection accidents caused by allowing over-current to develop, this paper proposed a technology that controlled the inverter in an intermediate state—partial-switching-off CBC "soft" current limiting control technology. When the control was triggered, the specified switching devices were turned off while the remaining ones were kept on. Finally, a simulation model was established using MATLAB/Simulink to verify the proposed CBC current limiting control method. [Results] The results indicated that this method could effectively reduce the number of triggers, lower the di/dt of the switching devices, and decrease the current peak value of the internal switching devices in the inverter, thereby enhancing the reliability of the inverter. Compared with the full-switching-off CBC current limiting method, the trigger cycles of the partial-switching-off CBC "soft" current limiting were longer, and the trigger frequency was lower. Moreover, the CBC "soft" current limiting method limited the peak current of the switching devices to a lower level, which was beneficial for improving the reliability of the inverter and optimizing the CBC current limiting control method. [Conclusion] The proposed CBC "soft" current limiting control method for ANPC inverters can effectively control inverter current under short-circuit faults, improve the inverter’s short-circuit fault ride-through capability, and provide technical support for the safe operation of new energy grid connection.
2026,53(5):432-443, DOI: 10.12177/emca.2026.159
Abstract:
[Objective] In inverter-fed interior permanent magnet synchronous motor (IPMSM), harmonic currents and the associated radial electromagnetic forces are primary sources of electromagnetic vibration and noise. Conventional control strategies usually target either low frequency or high frequency vibration suppression, resulting in limited effectiveness over a wide frequency range. This paper proposes an improved control strategy for coordinated suppression of low- and high-frequency electromagnetic vibration. [Methods] A random zero-vector SVPWM strategy based on Logistic mapping and Markov chains was first employed to generate uniformly distributed random zero-vector sequences, which dynamically adjust inverter switching instants to suppress high-frequency harmonics around the switching frequency. Meanwhile, a virtual sinusoidal signal injection method was incorporated into the maximum torque per ampere control scheme to optimize the current vector angle at the current control level, thereby reducing low-order harmonic currents and mitigating low-frequency electromagnetic vibration. [Results] The results indicated that, compared to the traditional control strategy, the proposed control strategy had reduced the harmonic distortion rate of A-phase current to 5.53% and achieved a maximum vibration acceleration reduction of 65.96%, significantly improving the electromagnetic vibration performance of the motor. [Conclusion] The proposed control strategy effectively suppresses both low-frequency and high-frequency harmonic currents and weakens the corresponding radial electromagnetic force components, enabling coordinated suppression of low-frequency and high-frequency electromagnetic vibration in IPMSM. The results confirm its practical potential for electromagnetic vibration and noise reduction in electric drive systems.
[Objective] In inverter-fed interior permanent magnet synchronous motor (IPMSM), harmonic currents and the associated radial electromagnetic forces are primary sources of electromagnetic vibration and noise. Conventional control strategies usually target either low frequency or high frequency vibration suppression, resulting in limited effectiveness over a wide frequency range. This paper proposes an improved control strategy for coordinated suppression of low- and high-frequency electromagnetic vibration. [Methods] A random zero-vector SVPWM strategy based on Logistic mapping and Markov chains was first employed to generate uniformly distributed random zero-vector sequences, which dynamically adjust inverter switching instants to suppress high-frequency harmonics around the switching frequency. Meanwhile, a virtual sinusoidal signal injection method was incorporated into the maximum torque per ampere control scheme to optimize the current vector angle at the current control level, thereby reducing low-order harmonic currents and mitigating low-frequency electromagnetic vibration. [Results] The results indicated that, compared to the traditional control strategy, the proposed control strategy had reduced the harmonic distortion rate of A-phase current to 5.53% and achieved a maximum vibration acceleration reduction of 65.96%, significantly improving the electromagnetic vibration performance of the motor. [Conclusion] The proposed control strategy effectively suppresses both low-frequency and high-frequency harmonic currents and weakens the corresponding radial electromagnetic force components, enabling coordinated suppression of low-frequency and high-frequency electromagnetic vibration in IPMSM. The results confirm its practical potential for electromagnetic vibration and noise reduction in electric drive systems.
2026,53(5):444-455, DOI: 10.12177/emca.2026.155
Abstract:
[Objective] Traditional permanent magnet synchronous motor drives are limited by the thermal degradation characteristics of electrolytic capacitors, resulting in a lifespan bottleneck. Electrolytic capacitor-less drive systems improve reliability by replacing electrolytic capacitors with film capacitors, but the large inductors introduced can easily cause LC resonance on the grid side. To address this, this paper proposes a virtual damping power control method that effectively suppresses grid-side resonance and enhances the system’s power factor and power quality. [Methods] To investigate the influencing factors of grid-side LC resonance, the characteristic equation of the electrolytic capacitor-less drive system was derived, and the necessity of increasing system damping to suppress resonance was clarified. The traditional virtual impedance control scheme was optimized, and the corresponding relationship between bus capacitor power, grid-side inductor power, and resonant power was established based on energy conservation and space vector pulse width modulation control cycles. By accurately calculating the resonant power and converting it into a voltage vector for compensation, effective suppression of resonance was achieved. [Results] The experimental results demonstrated that the proposed method effectively suppressed grid-side LC resonance under both rated and high-speed operating conditions. The total harmonic distortion of the grid-side current was significantly reduced, and the system power factor reached a maximum of 0.99. [Conclusion] The proposed method provides a reference for the engineering application of electrolytic capacitor-less drive systems in low-cost and high-reliability fields.
[Objective] Traditional permanent magnet synchronous motor drives are limited by the thermal degradation characteristics of electrolytic capacitors, resulting in a lifespan bottleneck. Electrolytic capacitor-less drive systems improve reliability by replacing electrolytic capacitors with film capacitors, but the large inductors introduced can easily cause LC resonance on the grid side. To address this, this paper proposes a virtual damping power control method that effectively suppresses grid-side resonance and enhances the system’s power factor and power quality. [Methods] To investigate the influencing factors of grid-side LC resonance, the characteristic equation of the electrolytic capacitor-less drive system was derived, and the necessity of increasing system damping to suppress resonance was clarified. The traditional virtual impedance control scheme was optimized, and the corresponding relationship between bus capacitor power, grid-side inductor power, and resonant power was established based on energy conservation and space vector pulse width modulation control cycles. By accurately calculating the resonant power and converting it into a voltage vector for compensation, effective suppression of resonance was achieved. [Results] The experimental results demonstrated that the proposed method effectively suppressed grid-side LC resonance under both rated and high-speed operating conditions. The total harmonic distortion of the grid-side current was significantly reduced, and the system power factor reached a maximum of 0.99. [Conclusion] The proposed method provides a reference for the engineering application of electrolytic capacitor-less drive systems in low-cost and high-reliability fields.
2026,53(5):456-464, DOI: 10.12177/emca.2026.156
Abstract:
[Objective] To address the strong parameter dependence of permanent magnet synchronous motor (PMSM) model predictive current control (MPCC), this paper proposes a near-current-variation-based prediction model, which eliminates the resistance and rotor flux parameters, thereby improving the parameter robustness of PMSM MPCC. [Methods] Based on the traditional current prediction model of PMSM and near-current-variation, the predicted current value for applying the same voltage vector Vn as the previous moment was first calculated. Then, using this as a reference value, the predicted values for applying other voltage vectors were derived, thereby establishing a near-current-variation-based prediction model. Finally, through simulations and experiments, the performance of PMSM MPCC based on the traditional current prediction model, incremental current prediction model, and near-current-variation prediction model was compared. [Results] The simulation and experimental results demonstrated that the proposed near-current-variation prediction model did not require stator resistance or rotor flux linkage parameters, and its control performance was comparable to that of both the traditional and incremental current prediction models. Moreover, the optimal voltage vector selections of the three models were consistent. The proposed model relied solely on the stator d, q-axis inductance, significantly reducing parameter dependency while maintaining stable system operation. [Conclusion] The proposed model provides a more simplified solution for PMSM MPCC.
[Objective] To address the strong parameter dependence of permanent magnet synchronous motor (PMSM) model predictive current control (MPCC), this paper proposes a near-current-variation-based prediction model, which eliminates the resistance and rotor flux parameters, thereby improving the parameter robustness of PMSM MPCC. [Methods] Based on the traditional current prediction model of PMSM and near-current-variation, the predicted current value for applying the same voltage vector Vn as the previous moment was first calculated. Then, using this as a reference value, the predicted values for applying other voltage vectors were derived, thereby establishing a near-current-variation-based prediction model. Finally, through simulations and experiments, the performance of PMSM MPCC based on the traditional current prediction model, incremental current prediction model, and near-current-variation prediction model was compared. [Results] The simulation and experimental results demonstrated that the proposed near-current-variation prediction model did not require stator resistance or rotor flux linkage parameters, and its control performance was comparable to that of both the traditional and incremental current prediction models. Moreover, the optimal voltage vector selections of the three models were consistent. The proposed model relied solely on the stator d, q-axis inductance, significantly reducing parameter dependency while maintaining stable system operation. [Conclusion] The proposed model provides a more simplified solution for PMSM MPCC.
2026,53(5):465-476, DOI: 10.12177/emca.2026.157
Abstract:
[Objective] In modern industrial applications with variable operating conditions and cross-equipment scenarios, the performance of traditional fault diagnosis models for induction motors severely degrades due to data distribution shifts. To address the limitations of existing single-domain alignment strategies (insufficient generalization) and high computational complexity in diagnostic models, this paper proposes a lightweight fault diagnosis method integrating domain adversarial neural network (DANN) with correlation alignment (CORAL). [Methods] A co-simulation platform was established based on Maxwell and Simulink to simulate the dynamic behavior of motors under vector control, and stator current signals under multiple operating conditions were obtained. A preprocessing strategy combining time-domain differencing and continuous wavelet transform was adopted to suppress the fundamental component and generate highly distinguishable time-frequency image features. The lightweight network GhostNetV2 was employed as the feature extraction backbone to reduce computational costs. On the basis of standard domain adversarial training, a CORAL loss was introduced, where the second-order statistics of source and target domain features were explicitly aligned, constructing a dual-domain alignment mechanism that implicit adversarial learning with explicit statistical matching. [Results] The simulation and experimental results demonstrated that the proposed method significantly improved diagnostic performance while maintaining model lightweightness. In the transfer task under varying operating conditions of the same motor, an average classification accuracy of 99.1% was achieved in the target domain. For the more challenging cross-model transfer task between different motors, the average classification accuracy remained at 81.9% in the target domain, which was significantly superior to comparative algorithms. [Conclusion] The proposed dual-domain alignment strategy can alleviate the feature transfer challenges under complex operating conditions to a certain extent, achieving a balanced performance in noise reduction, model lightweighting, and generalization capability. It provides a reliable solution for non-intrusive online monitoring and cross-domain fault diagnosis of induction motors.
[Objective] In modern industrial applications with variable operating conditions and cross-equipment scenarios, the performance of traditional fault diagnosis models for induction motors severely degrades due to data distribution shifts. To address the limitations of existing single-domain alignment strategies (insufficient generalization) and high computational complexity in diagnostic models, this paper proposes a lightweight fault diagnosis method integrating domain adversarial neural network (DANN) with correlation alignment (CORAL). [Methods] A co-simulation platform was established based on Maxwell and Simulink to simulate the dynamic behavior of motors under vector control, and stator current signals under multiple operating conditions were obtained. A preprocessing strategy combining time-domain differencing and continuous wavelet transform was adopted to suppress the fundamental component and generate highly distinguishable time-frequency image features. The lightweight network GhostNetV2 was employed as the feature extraction backbone to reduce computational costs. On the basis of standard domain adversarial training, a CORAL loss was introduced, where the second-order statistics of source and target domain features were explicitly aligned, constructing a dual-domain alignment mechanism that implicit adversarial learning with explicit statistical matching. [Results] The simulation and experimental results demonstrated that the proposed method significantly improved diagnostic performance while maintaining model lightweightness. In the transfer task under varying operating conditions of the same motor, an average classification accuracy of 99.1% was achieved in the target domain. For the more challenging cross-model transfer task between different motors, the average classification accuracy remained at 81.9% in the target domain, which was significantly superior to comparative algorithms. [Conclusion] The proposed dual-domain alignment strategy can alleviate the feature transfer challenges under complex operating conditions to a certain extent, achieving a balanced performance in noise reduction, model lightweighting, and generalization capability. It provides a reliable solution for non-intrusive online monitoring and cross-domain fault diagnosis of induction motors.
2026,53(5):477-488, DOI: 10.12177/emca.2026.160
Abstract:
[Objective] In practical applications, the speed of permanent magnet synchronous motor (PMSM) is susceptible to multi-source coupled disturbances, rendering traditional motor control inadequate for meeting the control requirements of PMSM in certain high-precision applications. Therefore, it is of great significance to study anti-disturbance control strategies for PMSM against periodic and aperiodic disturbances to suppress speed fluctuations and enhance the control accuracy of the motor system. [Methods] Addressing the speed fluctuation issue of permanent magnet synchronous motors under the influence of periodic and non-periodic disturbances, a speed fluctuation suppression strategy for PMSM based on active disturbance rejection repetitive controller was proposed to achieve speed fluctuation suppression. Firstly, the error-based active disturbance rejection controller (EBADRC) was improved by replacing the integrator in the extended state observer (ESO) with a low-pass filter to enhance its anti-disturbance capability. Secondly, a repetitive controller was used to improve the control law of EBADRC, thereby achieving suppression of periodic fluctuations caused by various disturbance frequencies. Finally, experimental comparisons were conducted on a prototype test platform between the control strategy proposed in this paper, EBADRC, improved EBADRC, and PI control. [Results] Under the conditions of sudden 50% and 100% load increases, the proposed control strategy was able to better suppress periodic and aperiodic disturbances. Under the condition of a sudden 100% load increase at rated speed of 2 000 r/min, the speed drop when using the proposed control method was reduced by 65, 78, and 85 r/min compared to when using a PI controller, EBADRC, and improved EBADRC, respectively. The periodic speed fluctuations were reduced by 7, 12, and 26 r/min, respectively. The steady-state speed test of the proposed method under b0 mismatch conditions showed that the PMSM still operated stably when the parameter b0 was doubled or halved, thus demonstrating the good parameter robustness of the proposed method. [Conclusion] The speed fluctuation suppression strategy for PMSM based on active disturbance rejection repetitive controller proposed in this paper can effectively suppress both periodic and aperiodic disturbances and exhibits good robustness.
[Objective] In practical applications, the speed of permanent magnet synchronous motor (PMSM) is susceptible to multi-source coupled disturbances, rendering traditional motor control inadequate for meeting the control requirements of PMSM in certain high-precision applications. Therefore, it is of great significance to study anti-disturbance control strategies for PMSM against periodic and aperiodic disturbances to suppress speed fluctuations and enhance the control accuracy of the motor system. [Methods] Addressing the speed fluctuation issue of permanent magnet synchronous motors under the influence of periodic and non-periodic disturbances, a speed fluctuation suppression strategy for PMSM based on active disturbance rejection repetitive controller was proposed to achieve speed fluctuation suppression. Firstly, the error-based active disturbance rejection controller (EBADRC) was improved by replacing the integrator in the extended state observer (ESO) with a low-pass filter to enhance its anti-disturbance capability. Secondly, a repetitive controller was used to improve the control law of EBADRC, thereby achieving suppression of periodic fluctuations caused by various disturbance frequencies. Finally, experimental comparisons were conducted on a prototype test platform between the control strategy proposed in this paper, EBADRC, improved EBADRC, and PI control. [Results] Under the conditions of sudden 50% and 100% load increases, the proposed control strategy was able to better suppress periodic and aperiodic disturbances. Under the condition of a sudden 100% load increase at rated speed of 2 000 r/min, the speed drop when using the proposed control method was reduced by 65, 78, and 85 r/min compared to when using a PI controller, EBADRC, and improved EBADRC, respectively. The periodic speed fluctuations were reduced by 7, 12, and 26 r/min, respectively. The steady-state speed test of the proposed method under b0 mismatch conditions showed that the PMSM still operated stably when the parameter b0 was doubled or halved, thus demonstrating the good parameter robustness of the proposed method. [Conclusion] The speed fluctuation suppression strategy for PMSM based on active disturbance rejection repetitive controller proposed in this paper can effectively suppress both periodic and aperiodic disturbances and exhibits good robustness.
2026,53(5):489-499, DOI: 10.12177/emca.2026.161
Abstract:
[Objective] To address the issues of the poor thermal conductivity in traditional organic insulating materials, which restricts heat dissipation and performance of motors under overload conditions, this study replaced traditional slot insulation paper with high-thermal-conductivity silicon carbide (SiC) insulating varnish for performance enhancement of motors. [Methods] Taking a 1.1 kW asynchronous motor as the test case, a three-dimensional temperature field simulation model was firstly established. Subsequently, thermal analyses were performed via simulation for motors employing standard slot insulation paper and the SiC-based insulating varnish, respectively. Finally, an experimental platform was constructed to measure and compare key performance parameters—including temperature rise, current, and efficiency—of both motor configurations under loads ranging from the rated condition to 1.5-fold load. [Results] Experimental and simulation results indicated that motors utilizing SiC-based high-thermal-conductivity insulating varnish exhibited lower steady-state temperature rises and operating currents compared to traditional insulated motors, while also boasting higher efficiency. Notably, under a 1.5-fold load condition, traditional insulated motors reached a temperature of 150 ℃, triggering an overtemperature shutdown, whereas SiC insulated motors remained stable at 135 ℃ with ample safety margin.This solution proves effective in reducing operational temperature rise and enhancing reliability, rendering it particularly suitable for high-overload applications and scenarios where thermal sensitivity is a critical concern. [Conclusion] The application of SiC high-thermal-conductivity insulating material in stator slot insulation can significantly improve heat dissipation, suppress winding temperature rise, and thereby enhance motor efficiency and overload capacity. This solution can effectively reduce temperature rise and improve reliability, making it particularly suitable for high-overload and heat-sensitive motor applications.
[Objective] To address the issues of the poor thermal conductivity in traditional organic insulating materials, which restricts heat dissipation and performance of motors under overload conditions, this study replaced traditional slot insulation paper with high-thermal-conductivity silicon carbide (SiC) insulating varnish for performance enhancement of motors. [Methods] Taking a 1.1 kW asynchronous motor as the test case, a three-dimensional temperature field simulation model was firstly established. Subsequently, thermal analyses were performed via simulation for motors employing standard slot insulation paper and the SiC-based insulating varnish, respectively. Finally, an experimental platform was constructed to measure and compare key performance parameters—including temperature rise, current, and efficiency—of both motor configurations under loads ranging from the rated condition to 1.5-fold load. [Results] Experimental and simulation results indicated that motors utilizing SiC-based high-thermal-conductivity insulating varnish exhibited lower steady-state temperature rises and operating currents compared to traditional insulated motors, while also boasting higher efficiency. Notably, under a 1.5-fold load condition, traditional insulated motors reached a temperature of 150 ℃, triggering an overtemperature shutdown, whereas SiC insulated motors remained stable at 135 ℃ with ample safety margin.This solution proves effective in reducing operational temperature rise and enhancing reliability, rendering it particularly suitable for high-overload applications and scenarios where thermal sensitivity is a critical concern. [Conclusion] The application of SiC high-thermal-conductivity insulating material in stator slot insulation can significantly improve heat dissipation, suppress winding temperature rise, and thereby enhance motor efficiency and overload capacity. This solution can effectively reduce temperature rise and improve reliability, making it particularly suitable for high-overload and heat-sensitive motor applications.
2026,53(5):500-511, DOI: 10.12177/emca.2026.164
Abstract:
[Objective] The axial stagger high-speed switched reluctance motor employs dual stator-rotor sets with a staggered angle to mitigate the high torque ripple inherent in conventional switched reluctance motors (SRMs) due to their double salient structure and nonlinear magnetic circuit. In order to further reduce the torque ripple and improve the efficiency of the motor, a new torque sharing function strategy for switched reluctance motor with stagger structure is proposed in this paper. [Methods] The strategy, aimed at the steady-state operation phase, takes into account the two sets of stator and rotor are in single-phase conduction and single-phase conduction and two-phase exchange conduction respectively. The former allocated the torque of the two conduction phases according to the torque per square ampere, while the latter used the torque generated at the single-phase conduction side to compensate for the lack of torque at the two-phase exchange side, in order to achieve optimal allocation of torque to each phase winding on both sides of the motor. What’s more, in order to ensure the reliability of the control system, the operation process of the control system was designed. The current chopping control strategy was adopted in the start-up phase to limit the current peak while ensuring the rapid tracking of the given speed. The torque sharing function in the transition phase was designed to realize the smooth switching from the start-up phase to the steady-state operation phase. Finally, a simulation model of the motor control system was built using Simulink to verify the effectiveness of the control strategy proposed in this paper. [Results] The transient simulation results indicated that the proposed control strategy optimized the speed regulation time and overshoot, ensuring a smooth transition between the start-up phase and the steady-state phase, thereby verifying the reliability of the proposed control strategy. The steady-state simulation results demonstrated that the torque ripple coefficient and torque current ratio of the improved torque sharing function strategy were superior to other four traditional torque sharing function strategies under both low-speed and high-speed conditions. [Conclusion] The control strategy proposed in this paper has the feasibility and stability, which can reduce the torque ripple and improve the efficiency of the motors, and provides a new idea for improving the control performance of high-speed switched reluctance motors.
[Objective] The axial stagger high-speed switched reluctance motor employs dual stator-rotor sets with a staggered angle to mitigate the high torque ripple inherent in conventional switched reluctance motors (SRMs) due to their double salient structure and nonlinear magnetic circuit. In order to further reduce the torque ripple and improve the efficiency of the motor, a new torque sharing function strategy for switched reluctance motor with stagger structure is proposed in this paper. [Methods] The strategy, aimed at the steady-state operation phase, takes into account the two sets of stator and rotor are in single-phase conduction and single-phase conduction and two-phase exchange conduction respectively. The former allocated the torque of the two conduction phases according to the torque per square ampere, while the latter used the torque generated at the single-phase conduction side to compensate for the lack of torque at the two-phase exchange side, in order to achieve optimal allocation of torque to each phase winding on both sides of the motor. What’s more, in order to ensure the reliability of the control system, the operation process of the control system was designed. The current chopping control strategy was adopted in the start-up phase to limit the current peak while ensuring the rapid tracking of the given speed. The torque sharing function in the transition phase was designed to realize the smooth switching from the start-up phase to the steady-state operation phase. Finally, a simulation model of the motor control system was built using Simulink to verify the effectiveness of the control strategy proposed in this paper. [Results] The transient simulation results indicated that the proposed control strategy optimized the speed regulation time and overshoot, ensuring a smooth transition between the start-up phase and the steady-state phase, thereby verifying the reliability of the proposed control strategy. The steady-state simulation results demonstrated that the torque ripple coefficient and torque current ratio of the improved torque sharing function strategy were superior to other four traditional torque sharing function strategies under both low-speed and high-speed conditions. [Conclusion] The control strategy proposed in this paper has the feasibility and stability, which can reduce the torque ripple and improve the efficiency of the motors, and provides a new idea for improving the control performance of high-speed switched reluctance motors.
2026,53(5):512-522, DOI: 10.12177/emca.2026.163
Abstract:
[Objective] Inter-turn short-circuit faults are a common and latent early-stage failures in circuit and motor drive systems. Although the underlying physical mechanisms of such faults are essentially identical across different phases, significant discrepancies in data distributions arise due to phase shifts and measurement conditions, which limits the cross-phase applicability of data-driven diagnostic methods. This paper proposes a unified diagnosis method for inter-turn short-circuit faults in different phases under limited annotation conditions. [Methods] The phase-to-phase difference was regarded as a specific form of data distribution shift, so the core criterion for inter-turn short-circuit was independent of the specific phase. Based on this, a feasible method was proposed in this paper from the perspective of cross-phase transfer, which utilized only single-phase inter-turn short-circuit fault data for model training and directly applied it to fault diagnosis of other phases. This method achieved multi-phase inter-turn short-circuit fault identification under single-phase training conditions by constructing a physically consistent feature representation and employing a unified lightweight diagnostic model. [Results] The results indicated that, without the introduction of complex transfer structures or additional labeled data, the proposed method demonstrated high diagnostic accuracy on the training phase and maintained stable performance in different phase-to-phase inter-turn short-circuit fault diagnosis tasks, significantly enhancing the cross-phase generalization ability of fault diagnosis. [Conclusion] This study provides a concise and effective solution for reducing the dependence of the inter-turn short-circuit fault diagnosis model on multi-phase labeled data and enhancing the model’s generalizability in practical engineering scenarios, thus possessing high engineering practical value.
[Objective] Inter-turn short-circuit faults are a common and latent early-stage failures in circuit and motor drive systems. Although the underlying physical mechanisms of such faults are essentially identical across different phases, significant discrepancies in data distributions arise due to phase shifts and measurement conditions, which limits the cross-phase applicability of data-driven diagnostic methods. This paper proposes a unified diagnosis method for inter-turn short-circuit faults in different phases under limited annotation conditions. [Methods] The phase-to-phase difference was regarded as a specific form of data distribution shift, so the core criterion for inter-turn short-circuit was independent of the specific phase. Based on this, a feasible method was proposed in this paper from the perspective of cross-phase transfer, which utilized only single-phase inter-turn short-circuit fault data for model training and directly applied it to fault diagnosis of other phases. This method achieved multi-phase inter-turn short-circuit fault identification under single-phase training conditions by constructing a physically consistent feature representation and employing a unified lightweight diagnostic model. [Results] The results indicated that, without the introduction of complex transfer structures or additional labeled data, the proposed method demonstrated high diagnostic accuracy on the training phase and maintained stable performance in different phase-to-phase inter-turn short-circuit fault diagnosis tasks, significantly enhancing the cross-phase generalization ability of fault diagnosis. [Conclusion] This study provides a concise and effective solution for reducing the dependence of the inter-turn short-circuit fault diagnosis model on multi-phase labeled data and enhancing the model’s generalizability in practical engineering scenarios, thus possessing high engineering practical value.
2026,53(5):523-535, DOI: 10.12177/emca.2026.165
Abstract:
[Objective] This paper addresses the cogging torque inherent in fractional-slot concentrated winding (FSCW) stator axial-flux dual-rotor synchronous generator, which can induce vibration and acoustic noise, degrade control accuracy and operational smoothness. The virtual displacement method is employed to analyze the underlying mechanism of cogging torque generation and to derive its approximate analytical expression, thereby providing a theoretical basis for generator design, manufacturing, and optimization. [Methods] First, the fundamental theory of FSCW was reviewed, and the structural characteristics and coupling principle of an electrically excited through-FSCW-stator axial-flux dual-rotor synchronous generator (AF-DR-TS-FSCW-SG) were introduced. Subsequently, the cogging torque generation mechanism of this class of generators was analyzed using the virtual displacement method, and an analytical expression for cogging torque was derived based on the magnetomotive force-permeance method, yielding an approximate mathematical model. In addition, a two-dimensional finite element modeling approach tailored for axial-flux dual-rotor synchronous machines was proposed, and its accuracy was validated through no-load electromagnetic characteristic experiments. Finally, the dominant subharmonic amplitudes of cogging torque obtained from the analytical model were compared with those derived from two-dimensional finite element simulations. [Results] The results indicated that the relative errors of the no-load back electromotive force (EMF) amplitude between the two-dimensional finite element analysis (2-D FEA) results and the experimental measurements under three operating conditions—namely, excitation of rotor 1 alone, excitation of rotor 2 alone, and simultaneous excitation of both rotors—were 4.02%, 16.84%, and 10.73%, respectively. Despite the amplitude discrepancies, the waveform variation trends showed good agreement among all cases. Meanwhile, for the operating conditions with rotor 1 alone and rotor 2 alone excited, the relative errors of the dominant harmonic component of the cogging torque between the 2-D FEA results and the analytical results obtained by the virtual displacement method were 13.86% and 13.57%, respectively. [Conclusion] The proposed two-dimensional finite element modeling approach for the FSCW-stator axial-flux dual-rotor synchronous generator in this paper can accurately reflect the actual performance of the generator. In addition, the cogging torque mathematical model derived based on the virtual displacement method exhibits high accuracy.
[Objective] This paper addresses the cogging torque inherent in fractional-slot concentrated winding (FSCW) stator axial-flux dual-rotor synchronous generator, which can induce vibration and acoustic noise, degrade control accuracy and operational smoothness. The virtual displacement method is employed to analyze the underlying mechanism of cogging torque generation and to derive its approximate analytical expression, thereby providing a theoretical basis for generator design, manufacturing, and optimization. [Methods] First, the fundamental theory of FSCW was reviewed, and the structural characteristics and coupling principle of an electrically excited through-FSCW-stator axial-flux dual-rotor synchronous generator (AF-DR-TS-FSCW-SG) were introduced. Subsequently, the cogging torque generation mechanism of this class of generators was analyzed using the virtual displacement method, and an analytical expression for cogging torque was derived based on the magnetomotive force-permeance method, yielding an approximate mathematical model. In addition, a two-dimensional finite element modeling approach tailored for axial-flux dual-rotor synchronous machines was proposed, and its accuracy was validated through no-load electromagnetic characteristic experiments. Finally, the dominant subharmonic amplitudes of cogging torque obtained from the analytical model were compared with those derived from two-dimensional finite element simulations. [Results] The results indicated that the relative errors of the no-load back electromotive force (EMF) amplitude between the two-dimensional finite element analysis (2-D FEA) results and the experimental measurements under three operating conditions—namely, excitation of rotor 1 alone, excitation of rotor 2 alone, and simultaneous excitation of both rotors—were 4.02%, 16.84%, and 10.73%, respectively. Despite the amplitude discrepancies, the waveform variation trends showed good agreement among all cases. Meanwhile, for the operating conditions with rotor 1 alone and rotor 2 alone excited, the relative errors of the dominant harmonic component of the cogging torque between the 2-D FEA results and the analytical results obtained by the virtual displacement method were 13.86% and 13.57%, respectively. [Conclusion] The proposed two-dimensional finite element modeling approach for the FSCW-stator axial-flux dual-rotor synchronous generator in this paper can accurately reflect the actual performance of the generator. In addition, the cogging torque mathematical model derived based on the virtual displacement method exhibits high accuracy.
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The impact of largescale access of wind farms on the transient stability of power grids could not be ignored. Taking the extended twomachine system with doublyfed wind turbines as an example, the equivalent model of doublyfed induction generator was established, and the twomachine system could be equivalent to a singlemachine infinity system. Based on the law of equal area, the analytic formula of critical clearing angle of the system was deduced in detail after wind power accessed. The analytic formula was used to quantitatively analyze the variation trends of the critical clearing angle with wind power ratio, wind turbine grid connection position, fault location and load access position. The influence laws of the above four factors on the stability of transient power angle were summarized. The simulation models of the extended twomachine system with doublyfed induction generator was established in BPA and FASTEST, and the accuracy of the theoretical analysis was verified.
The impact of largescale access of wind farms on the transient stability of power grids could not be ignored. Taking the extended twomachine system with doublyfed wind turbines as an example, the equivalent model of doublyfed induction generator was established, and the twomachine system could be equivalent to a singlemachine infinity system. Based on the law of equal area, the analytic formula of critical clearing angle of the system was deduced in detail after wind power accessed. The analytic formula was used to quantitatively analyze the variation trends of the critical clearing angle with wind power ratio, wind turbine grid connection position, fault location and load access position. The influence laws of the above four factors on the stability of transient power angle were summarized. The simulation models of the extended twomachine system with doublyfed induction generator was established in BPA and FASTEST, and the accuracy of the theoretical analysis was verified.
Abstract:
Multimotor synchronous and coordinate system was widely used in the field of motor control. The control strategy played a important role in the performance of multimotor synchronization system. Domestic and foreign scholars had conducted deep research, who aimed at the problem of multimotor synchronization.They put forward a variety of synchronization control strategies. The control strategies proposed at home and abroad were reviewed. The accuracy of tracking, robustness and capacity of antiload of the control object were analyzed. The new prospect of multimotor synchronization control was proposed.
Multimotor synchronous and coordinate system was widely used in the field of motor control. The control strategy played a important role in the performance of multimotor synchronization system. Domestic and foreign scholars had conducted deep research, who aimed at the problem of multimotor synchronization.They put forward a variety of synchronization control strategies. The control strategies proposed at home and abroad were reviewed. The accuracy of tracking, robustness and capacity of antiload of the control object were analyzed. The new prospect of multimotor synchronization control was proposed.
Abstract:
Inwheel motor drive technology represents an essential development direction in new energy vehicle drive system. The technical requirements and drive form were introduced. The technical requirements and drive form of inwheel motor drive were summarized. Current research situation of inwheel motor drive technology was compared and analyzed briefly. The key technique problems of inwheel motor technology were proposed. The essential technologies in descreasing unsprung mass, restraining vertical vibration effect and reducing torque ripple of inwheel motor were discussed, which were supposed to be solved urgently. The development trend of inwheel motor drive technology was predicted.
Inwheel motor drive technology represents an essential development direction in new energy vehicle drive system. The technical requirements and drive form were introduced. The technical requirements and drive form of inwheel motor drive were summarized. Current research situation of inwheel motor drive technology was compared and analyzed briefly. The key technique problems of inwheel motor technology were proposed. The essential technologies in descreasing unsprung mass, restraining vertical vibration effect and reducing torque ripple of inwheel motor were discussed, which were supposed to be solved urgently. The development trend of inwheel motor drive technology was predicted.
2024,51(9):70-79, DOI: 10.12177/emca.2024.090
Abstract:
To address the issue of high torque ripple in permanent magnet assisted synchronous reluctance motor (PMA-SynRM), a multi-objective optimization design method based on the non-dominated sorting genetic algorithm II (NSGA-II) was proposed. First, the basic structure and working principle of the PMA-SynRM were introduced. Next, the rotor structure of the PMA-SynRM was improved by constructing air barriers and designing asymmetric auxiliary slots. Then, sensitivity analysis was conducted to identify the parameters that had the most significant impact on the optimization objectives of the PMA-SynRM, and multi-objective optimization was performed using NSGA-II. The optimal topology was selected from the generated Pareto front. Finally, the torque performance of the optimized motor was compared with that of the initial motor using finite element analysis software. Simulation results showed that the performance of the PMA-SynRM optimized through NSGA-II was significantly improved.
To address the issue of high torque ripple in permanent magnet assisted synchronous reluctance motor (PMA-SynRM), a multi-objective optimization design method based on the non-dominated sorting genetic algorithm II (NSGA-II) was proposed. First, the basic structure and working principle of the PMA-SynRM were introduced. Next, the rotor structure of the PMA-SynRM was improved by constructing air barriers and designing asymmetric auxiliary slots. Then, sensitivity analysis was conducted to identify the parameters that had the most significant impact on the optimization objectives of the PMA-SynRM, and multi-objective optimization was performed using NSGA-II. The optimal topology was selected from the generated Pareto front. Finally, the torque performance of the optimized motor was compared with that of the initial motor using finite element analysis software. Simulation results showed that the performance of the PMA-SynRM optimized through NSGA-II was significantly improved.
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Electric Machines & Control Application ® 2026
Supported by:Beijing E-Tiller Technology Development Co., Ltd.
