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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 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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2025,52(3):231-240, DOI: 10.12177/emca.2025.007
Abstract:
[Objective] To enhance the dynamic response performance and stability of interior permanent magnet synchronous motor (IPMSM) under flux-weakening conditions, and to address issues of current trajectory deviation and voltage saturation in traditional flux-weakening control strategies during high-speed operation, an improved flux-weakening control strategy for IPMSM is proposed. [Methods] Firstly, based on the mathematical model of IPMSM, the current trajectory of the traditional negative d-axis current compensation strategy was analyzed. It was observed that the current vector rotation transformation caused variations in output torque. Therefore, an improved flux-weakening control strategy was proposed, incorporating q-axis current compensation to offset torque fluctuations, thereby optimizing current trajectories and improving torque output stability. Secondly, for sudden load change conditions, the mechanism of voltage saturation was analyzed, and an anti-voltage saturation strategy prioritizing d-axis voltage supply was proposed. By dynamically adjusting the voltage distribution priority to ensure sufficient d-axis voltage supply, this strategy avoided current loss of control caused by voltage saturation, further enhancing system stability and reliability. [Results] To verify the effectiveness of the proposed strategy, an IPMSM experimental platform was established for comparative testing. The experimental results showed that, after the implementation of the improved flux-weakening control strategy, the current trajectory in the flux-weakening region of the IPMSM was significantly improved, the torque output stability was enhanced, and the system's dynamic response performance was improved. The anti-voltage saturation strategy effectively prevented current loss of control caused by voltage saturation, ensuring stable system operation. [Conclusion] The improved flux-weakening control strategy proposed in this study, by incorporating q-axis current compensation and prioritizing d-axis voltage supply, effectively addresses the issues of current trajectory deviation and voltage saturation in traditional flux-weakening control strategies during high-speed operation. Experimental results demonstrate that the proposed method can significantly enhance the current trajectory characteristics of IPMSM under flux-weakening conditions, improve the dynamic response performance of the system, and strengthen the anti-interference capability of the system, providing reliable technical support for the application of IPMSM in fields such as electric vehicles and high-speed machine tools.
[Objective] To enhance the dynamic response performance and stability of interior permanent magnet synchronous motor (IPMSM) under flux-weakening conditions, and to address issues of current trajectory deviation and voltage saturation in traditional flux-weakening control strategies during high-speed operation, an improved flux-weakening control strategy for IPMSM is proposed. [Methods] Firstly, based on the mathematical model of IPMSM, the current trajectory of the traditional negative d-axis current compensation strategy was analyzed. It was observed that the current vector rotation transformation caused variations in output torque. Therefore, an improved flux-weakening control strategy was proposed, incorporating q-axis current compensation to offset torque fluctuations, thereby optimizing current trajectories and improving torque output stability. Secondly, for sudden load change conditions, the mechanism of voltage saturation was analyzed, and an anti-voltage saturation strategy prioritizing d-axis voltage supply was proposed. By dynamically adjusting the voltage distribution priority to ensure sufficient d-axis voltage supply, this strategy avoided current loss of control caused by voltage saturation, further enhancing system stability and reliability. [Results] To verify the effectiveness of the proposed strategy, an IPMSM experimental platform was established for comparative testing. The experimental results showed that, after the implementation of the improved flux-weakening control strategy, the current trajectory in the flux-weakening region of the IPMSM was significantly improved, the torque output stability was enhanced, and the system's dynamic response performance was improved. The anti-voltage saturation strategy effectively prevented current loss of control caused by voltage saturation, ensuring stable system operation. [Conclusion] The improved flux-weakening control strategy proposed in this study, by incorporating q-axis current compensation and prioritizing d-axis voltage supply, effectively addresses the issues of current trajectory deviation and voltage saturation in traditional flux-weakening control strategies during high-speed operation. Experimental results demonstrate that the proposed method can significantly enhance the current trajectory characteristics of IPMSM under flux-weakening conditions, improve the dynamic response performance of the system, and strengthen the anti-interference capability of the system, providing reliable technical support for the application of IPMSM in fields such as electric vehicles and high-speed machine tools.
2025,52(3):241-250, DOI: 10.12177/emca.2024.170
Abstract:
[Objective] Hydrogen energy storage has the characteristics of high energy density and high power. Unitized regenerative fuel cell (URFC) is highly integrated hydrogen storage systems, but their application in distributed DC microgrids has been rarely reported. When combined with electrical energy storage, they hold significant potential in islanded microgrid applications. Economic dispatch is a critical issue in islanded microgrids, as they consist of various generation units with different generation costs and power outputs. Coordinating the output of these units to achieve optimal overall economic operation is a complex optimization problem. [Methods] This paper proposed an improved distributed economic control strategy based on the incremental cost (IC) consensus distributed algorithm, which ensured the lowest system cost when the IC of all generation units was equal. Additionally, a specific node was designed to achieve high-quality voltage restoration. Considering the power limitations of each generation unit, corresponding constraints were incorporated into the algorithm to ensure the feasibility of the dispatch results. Finally, simulations were performed using Matlab/Simulink, and a comparative analysis was conducted on the system’s dynamic response performance, economic performance, and stability under different operating conditions. [Results] Simulation results showed that the proposed control strategy could effectively achieve voltage restoration and significantly enhance the reliability and power quality of the photovoltaic-hydrogen storage islanded DC microgrid. Under various disturbances and load changes, the system could quickly recover to a stable state. Compared with traditional methods, the proposed strategy exhibited notable advantages in both economic efficiency and dynamic performance. [Conclusion] The distributed economic control strategy proposed in this paper exhibits good flexibility and adaptability. In practical applications, the node responsible for voltage restoration can dynamically switch to other power units based on power constraints, ensuring continuous and stable operation of the system. Meanwhile, nodes no longer participating in dispatch can be disconnected from the communication network, reducing the communication burdens. This design enhances the system’s fault tolerance and scalability.
[Objective] Hydrogen energy storage has the characteristics of high energy density and high power. Unitized regenerative fuel cell (URFC) is highly integrated hydrogen storage systems, but their application in distributed DC microgrids has been rarely reported. When combined with electrical energy storage, they hold significant potential in islanded microgrid applications. Economic dispatch is a critical issue in islanded microgrids, as they consist of various generation units with different generation costs and power outputs. Coordinating the output of these units to achieve optimal overall economic operation is a complex optimization problem. [Methods] This paper proposed an improved distributed economic control strategy based on the incremental cost (IC) consensus distributed algorithm, which ensured the lowest system cost when the IC of all generation units was equal. Additionally, a specific node was designed to achieve high-quality voltage restoration. Considering the power limitations of each generation unit, corresponding constraints were incorporated into the algorithm to ensure the feasibility of the dispatch results. Finally, simulations were performed using Matlab/Simulink, and a comparative analysis was conducted on the system’s dynamic response performance, economic performance, and stability under different operating conditions. [Results] Simulation results showed that the proposed control strategy could effectively achieve voltage restoration and significantly enhance the reliability and power quality of the photovoltaic-hydrogen storage islanded DC microgrid. Under various disturbances and load changes, the system could quickly recover to a stable state. Compared with traditional methods, the proposed strategy exhibited notable advantages in both economic efficiency and dynamic performance. [Conclusion] The distributed economic control strategy proposed in this paper exhibits good flexibility and adaptability. In practical applications, the node responsible for voltage restoration can dynamically switch to other power units based on power constraints, ensuring continuous and stable operation of the system. Meanwhile, nodes no longer participating in dispatch can be disconnected from the communication network, reducing the communication burdens. This design enhances the system’s fault tolerance and scalability.
2025,52(3):251-261, DOI: 10.12177/emca.2025.009
Abstract:
[Objective] As a core component of the synchronous generator excitation system, the accuracy of the equivalent circuit modeling for brushless AC exciters directly determines the reliability of output performance analysis. Traditional equivalent circuit models often overlook the magnetic circuit asymmetry caused by the salient pole effect of AC exciters during parameter equivalence, resulting in systematic deviations between theoretical calculations of commutation reactance parameters and actual operating conditions. These deviations further compromise the evaluation accuracy of key performance indicators, such as AC voltage distortion rate and DC voltage ripple. To address this issue, an improved equivalent circuit modeling method is proposed, with a focus on the influence of the salient pole effect on commutation reactance. [Methods] First, the equivalent circuit model of the brushless AC exciter was derived based on its flux linkage and voltage equations. Second, by analyzing the operational process of the brushless AC exciter over half a cycle in conjunction with the working modes of a three-phase bridge rectifier circuit, the effect of commutation reactance on AC voltage distortion rate and DC voltage ripple was systematically investigated. Finally, a solution for determining commutation reactance under varying salient-pole effect intensities was developed, and a refined commutation reactance calculation model incorporating the salient-pole effect was re-established. [Results] To validate the effectiveness of the model, a two-dimensional transient field-circuit coupling simulation model was established using finite element analysis. Simulation results showed that an increase in commutation reactance significantly increased both the AC voltage distortion rate and DC voltage ripple. The proposed equivalent circuit model, which incorporated the salient-pole effect, exhibited higher accuracy in calculating commutation reactance parameters, with significantly reduced errors compared to conventional methods. [Conclusion] The proposed equivalent circuit modeling method not only offers a high-precision tool for analyzing the commutation characteristics of brushless AC exciters, but also extends to generator systems with rectifier circuits, such as permanent magnet synchronous motors and electrically excited doubly-fed generators. This approach has significant implications for dynamic performance prediction and multi-physics co-optimization of complex electromagnetic devices.
[Objective] As a core component of the synchronous generator excitation system, the accuracy of the equivalent circuit modeling for brushless AC exciters directly determines the reliability of output performance analysis. Traditional equivalent circuit models often overlook the magnetic circuit asymmetry caused by the salient pole effect of AC exciters during parameter equivalence, resulting in systematic deviations between theoretical calculations of commutation reactance parameters and actual operating conditions. These deviations further compromise the evaluation accuracy of key performance indicators, such as AC voltage distortion rate and DC voltage ripple. To address this issue, an improved equivalent circuit modeling method is proposed, with a focus on the influence of the salient pole effect on commutation reactance. [Methods] First, the equivalent circuit model of the brushless AC exciter was derived based on its flux linkage and voltage equations. Second, by analyzing the operational process of the brushless AC exciter over half a cycle in conjunction with the working modes of a three-phase bridge rectifier circuit, the effect of commutation reactance on AC voltage distortion rate and DC voltage ripple was systematically investigated. Finally, a solution for determining commutation reactance under varying salient-pole effect intensities was developed, and a refined commutation reactance calculation model incorporating the salient-pole effect was re-established. [Results] To validate the effectiveness of the model, a two-dimensional transient field-circuit coupling simulation model was established using finite element analysis. Simulation results showed that an increase in commutation reactance significantly increased both the AC voltage distortion rate and DC voltage ripple. The proposed equivalent circuit model, which incorporated the salient-pole effect, exhibited higher accuracy in calculating commutation reactance parameters, with significantly reduced errors compared to conventional methods. [Conclusion] The proposed equivalent circuit modeling method not only offers a high-precision tool for analyzing the commutation characteristics of brushless AC exciters, but also extends to generator systems with rectifier circuits, such as permanent magnet synchronous motors and electrically excited doubly-fed generators. This approach has significant implications for dynamic performance prediction and multi-physics co-optimization of complex electromagnetic devices.
2025,52(3):262-271, DOI: 10.12177/emca.2024.171
Abstract:
[Objective] Permanent magnet synchronous motor (PMSM) is widely used in servo systems, electric vehicles and other fields, where high requirements exist for motor control accuracy, response speed, and anti-interference ability. The speed control of PMSM mostly adopts proportional integral differential (PID) control. However, the linear structure of traditional PID controllers struggles to provide the precise tracking performance and anti-interference ability required by PMSM when dealing with complex nonlinear systems. In order to address this issue, this paper proposes an active disturbance rejection control (ADRC) strategy based on the improved Black-winged Kite algorithm (IBKA). [Methods] Firstly, the PMSM was modeled and analyzed in the d-q coordinate system, and a speed controller for the PMSM was designed. Nonlinear ADRC was used to control the PMSM’s speed loop to enhance the system’s robustness against model uncertainties and external disturbances. The core advantage of ADRC is its ability to estimate and compensate for the total disturbance of the system in real time through the extended state observer, including unmodeled dynamics and external disturbances, thereby achieving precise control of the system state. Secondly, to address the issue of traditional ADRC relying on experience for parameter tuning, an IBKA algorithm that integrated Tent chaotic mapping and Gaussian mutation mechanism was proposed. This algorithm was used to achieve real-time online tuning of ADRC parameters. Finally, simulations based on Matlab/Simulink were conducted to verify the effectiveness of the ADRC strategy based on IBKA optimization proposed in this paper. [Results] The simulation results showed that compared with the traditional proportional integral (PI) control and standard ADRC, the ADRC based on IBKA optimization enabled the PMSM to exhibit good dynamic and static performance, with faster response speed, better tracking accuracy, stronger anti-interference ability, and superior torque control capability. The simulation results not only verified the effectiveness of IBKA in ADRC parameter optimization but also demonstrated the potential of ADRC in improving PMSM control performance. [Conclusion] The control strategy proposed in this paper provides an effective solution for PMSM in high precision, high dynamic, and high anti-interference applications, with important theoretical significance and practical value.
[Objective] Permanent magnet synchronous motor (PMSM) is widely used in servo systems, electric vehicles and other fields, where high requirements exist for motor control accuracy, response speed, and anti-interference ability. The speed control of PMSM mostly adopts proportional integral differential (PID) control. However, the linear structure of traditional PID controllers struggles to provide the precise tracking performance and anti-interference ability required by PMSM when dealing with complex nonlinear systems. In order to address this issue, this paper proposes an active disturbance rejection control (ADRC) strategy based on the improved Black-winged Kite algorithm (IBKA). [Methods] Firstly, the PMSM was modeled and analyzed in the d-q coordinate system, and a speed controller for the PMSM was designed. Nonlinear ADRC was used to control the PMSM’s speed loop to enhance the system’s robustness against model uncertainties and external disturbances. The core advantage of ADRC is its ability to estimate and compensate for the total disturbance of the system in real time through the extended state observer, including unmodeled dynamics and external disturbances, thereby achieving precise control of the system state. Secondly, to address the issue of traditional ADRC relying on experience for parameter tuning, an IBKA algorithm that integrated Tent chaotic mapping and Gaussian mutation mechanism was proposed. This algorithm was used to achieve real-time online tuning of ADRC parameters. Finally, simulations based on Matlab/Simulink were conducted to verify the effectiveness of the ADRC strategy based on IBKA optimization proposed in this paper. [Results] The simulation results showed that compared with the traditional proportional integral (PI) control and standard ADRC, the ADRC based on IBKA optimization enabled the PMSM to exhibit good dynamic and static performance, with faster response speed, better tracking accuracy, stronger anti-interference ability, and superior torque control capability. The simulation results not only verified the effectiveness of IBKA in ADRC parameter optimization but also demonstrated the potential of ADRC in improving PMSM control performance. [Conclusion] The control strategy proposed in this paper provides an effective solution for PMSM in high precision, high dynamic, and high anti-interference applications, with important theoretical significance and practical value.
2025,52(3):272-283, DOI: 10.12177/emca.2025.001
Abstract:
[Objective] High voltage isolation switches operate in harsh outdoor environments and are susceptible to external forces, natural aging, high temperatures, humidity, and other factors, which can lead to a series of faults and affect the healthy and normal operation of the power grid. This paper proposes a fault diagnosis method for isolation switches based on the Newton-Raphson-based optimizer (NRBO) improved feature mode decomposition (FMD) and support vector machine (SVM). [Methods] Firstly, NRBO was used to optimize the three parameters of FMD, and the optimal parameter combination was obtained. The vibration signals of the isolation switch collected in the experiment were decomposed by the FMD based on NRBO optimization (NRFMD), and the optimal intrinsic mode components were obtained. Secondly, the refined composite multiscale fluctuation dispersion entropy (RCMFDE) was used to extract the intrinsic mode components and obtain a high-dimensional feature matrix. Finally, the kernel principal component analysis was used to reduce the dimension of the high-dimensional feature matrix, and the SVM based on NRBO optimization (NRSVM) model was applied to diagnose the fault of the isolation switch. [Results] The fault simulation experiments were carried out for a 220 kV isolation switch, and the vibration signals of the isolation switch under four working states were collected. The fault diagnosis method proposed in this paper was compared with other commonly used diagnosis methods. The results showed that under different mechanical fault conditions, this method could achieve a fault classification accuracy of 98.33% for isolation switches, demonstrating high recognition accuracy, outperforming other commonly used algorithms. [Conclusion] The NRFMD used in this paper can ignore the periodicity and impulse of mechanical signals, exhibiting good robustness. RCMFDE can better extract the features of mode components. In summary, the proposed NRFMD-RCMFDE-NRSVM algorithm has good applicability for fault diagnosis of isolation switches, providing new insights for future research on isolation switch faults.
[Objective] High voltage isolation switches operate in harsh outdoor environments and are susceptible to external forces, natural aging, high temperatures, humidity, and other factors, which can lead to a series of faults and affect the healthy and normal operation of the power grid. This paper proposes a fault diagnosis method for isolation switches based on the Newton-Raphson-based optimizer (NRBO) improved feature mode decomposition (FMD) and support vector machine (SVM). [Methods] Firstly, NRBO was used to optimize the three parameters of FMD, and the optimal parameter combination was obtained. The vibration signals of the isolation switch collected in the experiment were decomposed by the FMD based on NRBO optimization (NRFMD), and the optimal intrinsic mode components were obtained. Secondly, the refined composite multiscale fluctuation dispersion entropy (RCMFDE) was used to extract the intrinsic mode components and obtain a high-dimensional feature matrix. Finally, the kernel principal component analysis was used to reduce the dimension of the high-dimensional feature matrix, and the SVM based on NRBO optimization (NRSVM) model was applied to diagnose the fault of the isolation switch. [Results] The fault simulation experiments were carried out for a 220 kV isolation switch, and the vibration signals of the isolation switch under four working states were collected. The fault diagnosis method proposed in this paper was compared with other commonly used diagnosis methods. The results showed that under different mechanical fault conditions, this method could achieve a fault classification accuracy of 98.33% for isolation switches, demonstrating high recognition accuracy, outperforming other commonly used algorithms. [Conclusion] The NRFMD used in this paper can ignore the periodicity and impulse of mechanical signals, exhibiting good robustness. RCMFDE can better extract the features of mode components. In summary, the proposed NRFMD-RCMFDE-NRSVM algorithm has good applicability for fault diagnosis of isolation switches, providing new insights for future research on isolation switch faults.
2025,52(3):284-293, DOI: 10.12177/emca.2025.006
Abstract:
[Objective] A method has been proposed to preprocess, predict, and classify the load data of automated guided vehicle (AGV) drive motors, and then predict the health status and failure of AGVs. The aim is to evaluate the health status and failure probability of AGV motors, and improve the maintenance and work strategies of AGVs. [Methods] Based on the experimental collection of AGV motor channel current, vibration signal data, and temperature data, the data is sampled. The proposed method uses autoregressive model and convolutional neural network model to predict the health status and calculate the failure probability of AGV drive motor's current, vibration signal, and temperature rise data trends. The collected and predicted data are converted into symmetrized dot pattern (SDP) images using SDP algorithm for classification detection, thereby determining the health level of the working motor. After classifying the health level of the dataset into three levels based on the temperature rise data of the motor, the autoregressive model and Convolutional network model is used to detect the health status of the driving motor and estimate the probability of the driving motor health level based on the load current and vibration signals of the AGV motor. Based on the determination of the health status, the statistical model can calculate the failure probability of the AGV driving motor. [Results] The data verification through the acceleration test of the driving motor shows that the accuracy of this method in evaluating the health status diagnosis of AGV driving motors reaches an average of about 99.7%, with an accuracy of 100% in classifying the test samples as healthy and unhealthy. When predicting the probability of AGV drive motor failure under planned workload, the root mean square error of AGV motor state data prediction reaches around 0.053. [Conclusion] By applying deep learning methods to the current, vibration, temperature rise and other data of AGV motors, the health level classification of AGV motors (healthy, sub healthy, unhealthy) is achieved. Based on the evaluation results of health status and the calculation of failure probability, reference is provided for the assessment of AGV workload intensity and maintenance plan.
[Objective] A method has been proposed to preprocess, predict, and classify the load data of automated guided vehicle (AGV) drive motors, and then predict the health status and failure of AGVs. The aim is to evaluate the health status and failure probability of AGV motors, and improve the maintenance and work strategies of AGVs. [Methods] Based on the experimental collection of AGV motor channel current, vibration signal data, and temperature data, the data is sampled. The proposed method uses autoregressive model and convolutional neural network model to predict the health status and calculate the failure probability of AGV drive motor's current, vibration signal, and temperature rise data trends. The collected and predicted data are converted into symmetrized dot pattern (SDP) images using SDP algorithm for classification detection, thereby determining the health level of the working motor. After classifying the health level of the dataset into three levels based on the temperature rise data of the motor, the autoregressive model and Convolutional network model is used to detect the health status of the driving motor and estimate the probability of the driving motor health level based on the load current and vibration signals of the AGV motor. Based on the determination of the health status, the statistical model can calculate the failure probability of the AGV driving motor. [Results] The data verification through the acceleration test of the driving motor shows that the accuracy of this method in evaluating the health status diagnosis of AGV driving motors reaches an average of about 99.7%, with an accuracy of 100% in classifying the test samples as healthy and unhealthy. When predicting the probability of AGV drive motor failure under planned workload, the root mean square error of AGV motor state data prediction reaches around 0.053. [Conclusion] By applying deep learning methods to the current, vibration, temperature rise and other data of AGV motors, the health level classification of AGV motors (healthy, sub healthy, unhealthy) is achieved. Based on the evaluation results of health status and the calculation of failure probability, reference is provided for the assessment of AGV workload intensity and maintenance plan.
2025,52(3):294-304, DOI: 10.12177/emca.2025.005
Abstract:
[Objective] The traction rectifier and the traction inverter are crucial components of train traction converters. The traction rectifier primarily consists of insulated gate bipolar transistor (IGBT), resonant circuit, DC-side capacitor, and other components. Its fault frequency is higher than that of the traction inverter. An open-circuit fault in an IGBT does not result in significant overcurrent or overvoltage, making diagnosis and protection relatively challenging. Therefore, this paper proposes an open-circuit fault diagnosis algorithm for the traction rectifier IGBT based on a mixed logic dynamic (MLD) model and adaptive thresholds. [Methods] Based on the working principle of the traction rectifier, an MLD model of the traction rectifier was established, and the grid-side current was estimated. The residual difference between the actual and estimated values of the grid-side current during single IGBT open-circuit faults was then analyzed. Finally, adaptive thresholds were designed for fault diagnosis, and the location of the IGBT open-circuit fault was distinguished based on the changes in the adaptive threshold. This led to the development of an open-circuit fault diagnosis algorithm for the traction rectifier IGBT based on the MLD model and adaptive threshold, enabling the diagnosis and localization of IGBT open-circuit faults. [Results] The MLD model was established based on the Matlab/Simulink platform, and the adaptive thresholds were introduced to verify the effectiveness of the proposed algorithm. Simulation results indicated that this fault diagnosis method can detect the open circuit faults of the IGBT within several hundred microseconds, accurately locate the faulty IGBT, and avoid misdiagnosis even in the presence of external interference. [Conclusion] The open-circuit fault diagnosis algorithm for IGBTs based on the MLD model and adaptive thresholds can quickly detect and locate faulty IGBTs. Compared to traditional MLD fault diagnosis algorithms, this proposed method effectively addresses the threshold selection issue for different IGBT open-circuit faults, offers high diagnostic accuracy, and demonstrates strong robustness to external interference.
[Objective] The traction rectifier and the traction inverter are crucial components of train traction converters. The traction rectifier primarily consists of insulated gate bipolar transistor (IGBT), resonant circuit, DC-side capacitor, and other components. Its fault frequency is higher than that of the traction inverter. An open-circuit fault in an IGBT does not result in significant overcurrent or overvoltage, making diagnosis and protection relatively challenging. Therefore, this paper proposes an open-circuit fault diagnosis algorithm for the traction rectifier IGBT based on a mixed logic dynamic (MLD) model and adaptive thresholds. [Methods] Based on the working principle of the traction rectifier, an MLD model of the traction rectifier was established, and the grid-side current was estimated. The residual difference between the actual and estimated values of the grid-side current during single IGBT open-circuit faults was then analyzed. Finally, adaptive thresholds were designed for fault diagnosis, and the location of the IGBT open-circuit fault was distinguished based on the changes in the adaptive threshold. This led to the development of an open-circuit fault diagnosis algorithm for the traction rectifier IGBT based on the MLD model and adaptive threshold, enabling the diagnosis and localization of IGBT open-circuit faults. [Results] The MLD model was established based on the Matlab/Simulink platform, and the adaptive thresholds were introduced to verify the effectiveness of the proposed algorithm. Simulation results indicated that this fault diagnosis method can detect the open circuit faults of the IGBT within several hundred microseconds, accurately locate the faulty IGBT, and avoid misdiagnosis even in the presence of external interference. [Conclusion] The open-circuit fault diagnosis algorithm for IGBTs based on the MLD model and adaptive thresholds can quickly detect and locate faulty IGBTs. Compared to traditional MLD fault diagnosis algorithms, this proposed method effectively addresses the threshold selection issue for different IGBT open-circuit faults, offers high diagnostic accuracy, and demonstrates strong robustness to external interference.
2025,52(3):305-314, DOI: 10.12177/emca.2024.173
Abstract:
[Objective] Fractional slot concentrated winding (FSCW) induction motors may experience rotor eccentricity during operation, leading to the generation of air-gap flux density of non-dominant pole. This results in variations in radial electromagnetic force density, further inducing unbalanced magnetic pull (UMP), which can cause damage to the motor. To address this issue, this paper investigates the air-gap flux density, radial electromagnetic force density, and UMP of an FSCW induction motor with a 15-slot stator and an 18-slot rotor, where both the stator and rotor are FSCW. [Method] First, the causes and effects of rotor eccentricity were introduced, and the air-gap flux density expression was derived using the magnetomotive force-permeance method, followed by an analysis of its harmonic components under ideal conditions and static eccentricity fault conditions. Then, Maxwell's equations were used to obtain expressions for radial electromagnetic force density and UMP. A two-dimensional finite element model of the FSCW induction motor was developed using Ansys-Maxwell for analysis. Finally, closing the stator slot was proposed as a method to optimize the air-gap flux density and suppress UMP. [Results] Rotor eccentricity introduced additional harmonics that were multiples of three, which did not exist under ideal operating conditions, and altered the fundamental wave amplitude without changing the harmonic frequencies. When a static eccentricity fault occurred, the harmonic orders of radial electromagnetic force density shifted to ±1 of those in the ideal state, and the amplitude increased significantly. Moreover, radial electromagnetic force density and UMP increased with the eccentricity value. Compared to stator with slots, the average air-gap flux density of the motor decreased under stator with closed slots, the stator tooth harmonics were significantly reduced, and the average UMP decreased by 21.83%. [Conclusion] Rotor eccentricity is the primary cause of UMP. By adopting the stator slot closure method, the air-gap flux density is optimized, significantly reducing stator tooth harmonics and lowering radial electromagnetic force density, ultimately mitigating UMP.
[Objective] Fractional slot concentrated winding (FSCW) induction motors may experience rotor eccentricity during operation, leading to the generation of air-gap flux density of non-dominant pole. This results in variations in radial electromagnetic force density, further inducing unbalanced magnetic pull (UMP), which can cause damage to the motor. To address this issue, this paper investigates the air-gap flux density, radial electromagnetic force density, and UMP of an FSCW induction motor with a 15-slot stator and an 18-slot rotor, where both the stator and rotor are FSCW. [Method] First, the causes and effects of rotor eccentricity were introduced, and the air-gap flux density expression was derived using the magnetomotive force-permeance method, followed by an analysis of its harmonic components under ideal conditions and static eccentricity fault conditions. Then, Maxwell's equations were used to obtain expressions for radial electromagnetic force density and UMP. A two-dimensional finite element model of the FSCW induction motor was developed using Ansys-Maxwell for analysis. Finally, closing the stator slot was proposed as a method to optimize the air-gap flux density and suppress UMP. [Results] Rotor eccentricity introduced additional harmonics that were multiples of three, which did not exist under ideal operating conditions, and altered the fundamental wave amplitude without changing the harmonic frequencies. When a static eccentricity fault occurred, the harmonic orders of radial electromagnetic force density shifted to ±1 of those in the ideal state, and the amplitude increased significantly. Moreover, radial electromagnetic force density and UMP increased with the eccentricity value. Compared to stator with slots, the average air-gap flux density of the motor decreased under stator with closed slots, the stator tooth harmonics were significantly reduced, and the average UMP decreased by 21.83%. [Conclusion] Rotor eccentricity is the primary cause of UMP. By adopting the stator slot closure method, the air-gap flux density is optimized, significantly reducing stator tooth harmonics and lowering radial electromagnetic force density, ultimately mitigating UMP.
2025,52(3):315-327, DOI: 10.12177/emca.2025.002
Abstract:
[Objective] This study investigates the multi-objective optimization of proportional integral (PI) controller parameters for the unified power quality conditioner (UPQC) using the non-dominated sorting genetic algorithm II (NSGA-II). UPQC is a crucial power quality enhancement device capable of effectively mitigating voltage fluctuations, harmonics, and imbalances in the grid. Its performance is highly dependent on the optimal configuration of controller parameters. Traditional optimization methods fail to satisfy the system’s multi-objective performance requirements and are susceptible to local optima. To overcome these challenges, this paper introduces a multi-objective optimization approach based on NSGA-II, aiming to identify a controller parameter configuration that concurrently optimizes harmonic suppression, voltage stability, and dynamic response speed. [Methods] The study utilizes NSGA-II for multi-objective optimization. This algorithm achieves global optimization of the multi-objective function through fast non-dominated sorting and crowding degree calculation. NSGA-II possesses strong global search capabilities and rapid convergence characteristics, enabling it to swiftly and accurately identify the optimal solution for UPQC controller parameter optimization. In the optimization process, harmonic suppression, voltage stability, and dynamic response speed are prioritized as the main optimization objectives. By precisely adjusting the PI controller parameters, the optimal control strategy is derived. [Results] The effectiveness and accuracy of the proposed strategy are verified through grid voltage compensation simulation and DC/AC side voltage simulation. In the grid voltage compensation simulation, the proposed strategy is compared with the nonlinear proportional integral-model predictive control (PI-MPC) strategy. The proposed strategy compensates the voltage waveform to be closer to a sine wave, with a smoother and more uniform waveform, and lower harmonic content compared to the nonlinear PI-MPC strategy. In the DC/AC side voltage simulation, the proposed strategy achieves shorter adjustment time, lower overshoot, and quicker recovery time when the system is disturbed, exhibiting stronger robustness than other strategies. [Conclusion] The PI controller parameter optimization strategy based on NSGA-II can effectively enhance the performance of UPQC under complex operating conditions, improving the system’s power quality and response efficiency. Compared to traditional methods, this optimization strategy not only improves power quality but also demonstrates better stability and faster adjustment capabilities in dynamic response processes.
[Objective] This study investigates the multi-objective optimization of proportional integral (PI) controller parameters for the unified power quality conditioner (UPQC) using the non-dominated sorting genetic algorithm II (NSGA-II). UPQC is a crucial power quality enhancement device capable of effectively mitigating voltage fluctuations, harmonics, and imbalances in the grid. Its performance is highly dependent on the optimal configuration of controller parameters. Traditional optimization methods fail to satisfy the system’s multi-objective performance requirements and are susceptible to local optima. To overcome these challenges, this paper introduces a multi-objective optimization approach based on NSGA-II, aiming to identify a controller parameter configuration that concurrently optimizes harmonic suppression, voltage stability, and dynamic response speed. [Methods] The study utilizes NSGA-II for multi-objective optimization. This algorithm achieves global optimization of the multi-objective function through fast non-dominated sorting and crowding degree calculation. NSGA-II possesses strong global search capabilities and rapid convergence characteristics, enabling it to swiftly and accurately identify the optimal solution for UPQC controller parameter optimization. In the optimization process, harmonic suppression, voltage stability, and dynamic response speed are prioritized as the main optimization objectives. By precisely adjusting the PI controller parameters, the optimal control strategy is derived. [Results] The effectiveness and accuracy of the proposed strategy are verified through grid voltage compensation simulation and DC/AC side voltage simulation. In the grid voltage compensation simulation, the proposed strategy is compared with the nonlinear proportional integral-model predictive control (PI-MPC) strategy. The proposed strategy compensates the voltage waveform to be closer to a sine wave, with a smoother and more uniform waveform, and lower harmonic content compared to the nonlinear PI-MPC strategy. In the DC/AC side voltage simulation, the proposed strategy achieves shorter adjustment time, lower overshoot, and quicker recovery time when the system is disturbed, exhibiting stronger robustness than other strategies. [Conclusion] The PI controller parameter optimization strategy based on NSGA-II can effectively enhance the performance of UPQC under complex operating conditions, improving the system’s power quality and response efficiency. Compared to traditional methods, this optimization strategy not only improves power quality but also demonstrates better stability and faster adjustment capabilities in dynamic response processes.
2025,52(3):328-340, DOI: 10.12177/emca.2025.003
Abstract:
[Objective] This paper aims to address the issue of high content of non-dominant harmonics and significant torque pulsation in fractional slot concentrated winding (FSCW) dual-rotor synchronous motors. A compensation winding is proposed to optimize the magnetic field structure of dual-pole-pair coupling, suppress non-dominant pole-order harmonics, and increase the content of dominant harmonics, thereby reducing torque pulsation caused by non-uniform magnetic fields. [Methods] Firstly, the fundamental theory of FSCW was analyzed, and the structural characteristics and coupling principles of dual-rotor synchronous motors were introduced. The algebraic and phasor synthesis methods were employed to analyze the distribution patterns of harmonic magnetomotive force in FSCW under different slot-pole combinations, and the distribution coefficients were derived. Subsequently, based on the distribution of dominant and high-content non-dominant pole-order harmonics, as well as the peak and valley characteristics of the synthesized magnetomotive force, a direct compensation method for specific harmonics was designed. The virtual displacement method was used to derive the expression for electromagnetic torque. Finally, finite element simulation and theoretical calculations using the virtual displacement method were conducted to analyze the changes in air-gap flux density and torque pulsation before and after harmonic compensation. [Results] The finite element simulation results showed high consistency with the theoretical calculations using the virtual displacement method, verifying the accuracy of the method for torque calculation. The electromagnetic torque waveform exhibited better sinusoidal characteristics after adding the compensation winding, and the torque pulsation of both rotors was significantly reduced. Specifically, after adding 1-pole compensation windings, the torque pulsation of Rotor 1 and Rotor 2 decreased by 30.11% and 41.1%, respectively. [Conclusion] The proposed method can effectively suppress the high-content non-dominant harmonics, optimize the torque waveform, and reduce the torque pulsation, thereby enhancing the operational efficiency of the motor.
[Objective] This paper aims to address the issue of high content of non-dominant harmonics and significant torque pulsation in fractional slot concentrated winding (FSCW) dual-rotor synchronous motors. A compensation winding is proposed to optimize the magnetic field structure of dual-pole-pair coupling, suppress non-dominant pole-order harmonics, and increase the content of dominant harmonics, thereby reducing torque pulsation caused by non-uniform magnetic fields. [Methods] Firstly, the fundamental theory of FSCW was analyzed, and the structural characteristics and coupling principles of dual-rotor synchronous motors were introduced. The algebraic and phasor synthesis methods were employed to analyze the distribution patterns of harmonic magnetomotive force in FSCW under different slot-pole combinations, and the distribution coefficients were derived. Subsequently, based on the distribution of dominant and high-content non-dominant pole-order harmonics, as well as the peak and valley characteristics of the synthesized magnetomotive force, a direct compensation method for specific harmonics was designed. The virtual displacement method was used to derive the expression for electromagnetic torque. Finally, finite element simulation and theoretical calculations using the virtual displacement method were conducted to analyze the changes in air-gap flux density and torque pulsation before and after harmonic compensation. [Results] The finite element simulation results showed high consistency with the theoretical calculations using the virtual displacement method, verifying the accuracy of the method for torque calculation. The electromagnetic torque waveform exhibited better sinusoidal characteristics after adding the compensation winding, and the torque pulsation of both rotors was significantly reduced. Specifically, after adding 1-pole compensation windings, the torque pulsation of Rotor 1 and Rotor 2 decreased by 30.11% and 41.1%, respectively. [Conclusion] The proposed method can effectively suppress the high-content non-dominant harmonics, optimize the torque waveform, and reduce the torque pulsation, thereby enhancing the operational efficiency of the motor.
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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 ® 2025
Supported by:Beijing E-Tiller Technology Development Co., Ltd.
