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Volume 50,Issue 12,2023 Table of Contents
2023, 50(12):1-9.
DOI: 10.12177/emca.2023.156
Abstract:
In traditional rolling bearing dynamic models, the contact profile of rolling elements is often neglected. Based on the comprehensive analysis of a rolling ball entering and leaving a defect, an equivalent profile quantitative characterization function for localized defects is established, integrating the geometric-motion principles of rolling bearings. From this, an enhanced dynamic model for system failures in rolling bearings is constructed. Using theoretical analysis and numerical simulations based on the dynamic model, the mapping relationship between the location dimensions of outer raceway defect for rolling element bearings and the characteristics of vibration signals is explored, offering a mechanistic foundation for the construction and extraction of quantitative diagnostic indicators. To address the challenge presented by noise interference affecting the diagnostic accuracy of location formulas in real signals, a new algorithm for adaptively decomposing multi-channel time series is used in this paper. In analyses of both simulated and experimental signals, it is shown that the subtle fault quantification features hidden within the original multi-channel signals are more effectively extracted using tensor singular spectrum decomposition.
In traditional rolling bearing dynamic models, the contact profile of rolling elements is often neglected. Based on the comprehensive analysis of a rolling ball entering and leaving a defect, an equivalent profile quantitative characterization function for localized defects is established, integrating the geometric-motion principles of rolling bearings. From this, an enhanced dynamic model for system failures in rolling bearings is constructed. Using theoretical analysis and numerical simulations based on the dynamic model, the mapping relationship between the location dimensions of outer raceway defect for rolling element bearings and the characteristics of vibration signals is explored, offering a mechanistic foundation for the construction and extraction of quantitative diagnostic indicators. To address the challenge presented by noise interference affecting the diagnostic accuracy of location formulas in real signals, a new algorithm for adaptively decomposing multi-channel time series is used in this paper. In analyses of both simulated and experimental signals, it is shown that the subtle fault quantification features hidden within the original multi-channel signals are more effectively extracted using tensor singular spectrum decomposition.
2023, 50(12):10-20.
DOI: 10.12177/emca.2023.145
Abstract:
The existing sensorless rotor position estimation technique for a dual-three phase permanent magnet synchronous motor (DTP-PMSM) that relies on the fundamental PWM excitation is able to achieve rotor position estimation at low and zero speeds without injecting high-frequency signals. However, it needs to take multiple current samples during individual active voltage vectors generated by a voltage source inverter. Although it is effective, the requirement on the multiple current sampling hinders its practical application. This paper therefore proposes a new algorithm to overcome the above shortcoming. The algorithm directly utilizes the saliency effect of dual three-phase PMSMs to extract the rotor position information in the average current derivatives of two adjacent PWM periods from the stationary coordinates by the synchronous sampling technique. The new algorithm allows a synchronous current sampling for both the rotor position estimation and the current control, which greatly eases the practical implementation. Finally, the proposed algorithm is effectively verified in a DTP-PMSM simulation model at low and zero speeds.
The existing sensorless rotor position estimation technique for a dual-three phase permanent magnet synchronous motor (DTP-PMSM) that relies on the fundamental PWM excitation is able to achieve rotor position estimation at low and zero speeds without injecting high-frequency signals. However, it needs to take multiple current samples during individual active voltage vectors generated by a voltage source inverter. Although it is effective, the requirement on the multiple current sampling hinders its practical application. This paper therefore proposes a new algorithm to overcome the above shortcoming. The algorithm directly utilizes the saliency effect of dual three-phase PMSMs to extract the rotor position information in the average current derivatives of two adjacent PWM periods from the stationary coordinates by the synchronous sampling technique. The new algorithm allows a synchronous current sampling for both the rotor position estimation and the current control, which greatly eases the practical implementation. Finally, the proposed algorithm is effectively verified in a DTP-PMSM simulation model at low and zero speeds.
2023, 50(12):21-31.
DOI: 10.12177/emca.2023.146
Abstract:
Aiming at the problem of low accuracy of classification model caused by the unbalanced category of transformer fault samples, a transformer fault diagnosis model based on sample integration learning and snake optimisation algorithm (SO) optimised support vector machine (SVM) is proposed. The model first uses the EasyEnsemble sampler to generate multiple subsets with balanced categories after multiple under-sampling of the samples; then the SVM model optimised by SO with key parameters is trained with the Bagging strategy, and the final fault types are obtained by integrating the results of the classifiers. The validity of the proposed model is verified by the arithmetic example, and the data show that the diagnostic accuracy of SO-SVM′s fault diagnosis is improved by 3.44%, 6.89%, 10.92%, and the AUC value is improved by 0.026 4, 0.042 5, and 0.081 2, respectively, compared with the models of RF, SVM and KNN; in the same classifier, the SO-SVM model is more accurate than the SMOTE and ADASYN sample balancing methods, the diagnostic accuracy is improved by 4.59% and 2.87%, respectively, indicating that the SO-SVM model has better fault diagnosis capability for unbalanced samples.
Aiming at the problem of low accuracy of classification model caused by the unbalanced category of transformer fault samples, a transformer fault diagnosis model based on sample integration learning and snake optimisation algorithm (SO) optimised support vector machine (SVM) is proposed. The model first uses the EasyEnsemble sampler to generate multiple subsets with balanced categories after multiple under-sampling of the samples; then the SVM model optimised by SO with key parameters is trained with the Bagging strategy, and the final fault types are obtained by integrating the results of the classifiers. The validity of the proposed model is verified by the arithmetic example, and the data show that the diagnostic accuracy of SO-SVM′s fault diagnosis is improved by 3.44%, 6.89%, 10.92%, and the AUC value is improved by 0.026 4, 0.042 5, and 0.081 2, respectively, compared with the models of RF, SVM and KNN; in the same classifier, the SO-SVM model is more accurate than the SMOTE and ADASYN sample balancing methods, the diagnostic accuracy is improved by 4.59% and 2.87%, respectively, indicating that the SO-SVM model has better fault diagnosis capability for unbalanced samples.
2023, 50(12):32-41.
DOI: 10.12177/emca.2023.151
Abstract:
The intensification of competition in the field of new energy vehicles has raised the requirements for the noise, vibration, and acoustic vibration roughness (NVH) performance of drive motors. The eccentricity of the air gap may also cause vibration and noise problems in the vehicle motor. This article takes a permanent magnet synchronous motor with a rated power of 35 kW as the research object, and uses a combination of analytical and finite element simulation methods to analyze the effects of rotor dynamic eccentricity and rotor static eccentricity on the electromagnetic force characteristics of the vehicle motor. And a finite element modal simulation model of the motor structure is established, accurately analyze the working mode of the vehicle motor. Based on acoustic simulation analysis, the influence of different degrees of dynamic eccentricity and static eccentricity on the electromagnetic noise spectrum characteristics of two key working points of vehicle motors is analyzed. Finally, the correctness of the theoretical analysis is verified through motor noise testing experiments in a semi anechoic room.
The intensification of competition in the field of new energy vehicles has raised the requirements for the noise, vibration, and acoustic vibration roughness (NVH) performance of drive motors. The eccentricity of the air gap may also cause vibration and noise problems in the vehicle motor. This article takes a permanent magnet synchronous motor with a rated power of 35 kW as the research object, and uses a combination of analytical and finite element simulation methods to analyze the effects of rotor dynamic eccentricity and rotor static eccentricity on the electromagnetic force characteristics of the vehicle motor. And a finite element modal simulation model of the motor structure is established, accurately analyze the working mode of the vehicle motor. Based on acoustic simulation analysis, the influence of different degrees of dynamic eccentricity and static eccentricity on the electromagnetic noise spectrum characteristics of two key working points of vehicle motors is analyzed. Finally, the correctness of the theoretical analysis is verified through motor noise testing experiments in a semi anechoic room.
2023, 50(12):42-53.
DOI: 10.12177/emca.2023.143
Abstract:
In order to improve the accuracy of short\|term wind power prediction, this paper proposes a short\|term wind power prediction model based on the ICEEMDAN\|SE\|MSGJO\|LSTM\|EC model. Firstly, the original wind power signal is decomposed using intrinsic computing expressive empirical mode decomposition with adaptive noise (ICEEMDAN) and reconstructed by adding components with similar entropy values through sample entropy calculation; Secondly, establish an multi\|strategy golden jackal optimization (MSGJO)\|long short\|term memory network (LSTM) prediction model, optimize the LSTM network parameters through the improved MSGJO, and predict various modal components; Finally, error correction (EC) is applied to the prediction results of each modal component and all modal prediction results are added to obtain the final prediction result. Taking a wind farm in Xinjiang as an example, simulation analysis was conducted using the prediction model proposed in this paper. The experimental results showed that the prediction model based on ICEEMDAN\|SE\|MSGJO\|LSTM\|EC proposed in this paper has higher prediction accuracy.
In order to improve the accuracy of short\|term wind power prediction, this paper proposes a short\|term wind power prediction model based on the ICEEMDAN\|SE\|MSGJO\|LSTM\|EC model. Firstly, the original wind power signal is decomposed using intrinsic computing expressive empirical mode decomposition with adaptive noise (ICEEMDAN) and reconstructed by adding components with similar entropy values through sample entropy calculation; Secondly, establish an multi\|strategy golden jackal optimization (MSGJO)\|long short\|term memory network (LSTM) prediction model, optimize the LSTM network parameters through the improved MSGJO, and predict various modal components; Finally, error correction (EC) is applied to the prediction results of each modal component and all modal prediction results are added to obtain the final prediction result. Taking a wind farm in Xinjiang as an example, simulation analysis was conducted using the prediction model proposed in this paper. The experimental results showed that the prediction model based on ICEEMDAN\|SE\|MSGJO\|LSTM\|EC proposed in this paper has higher prediction accuracy.
2023, 50(12):54-65.
DOI: 10.12177/emca.2023.154
Abstract:
With the increase of the proportion of new energy, in the Yunnan power grid with abundant hydropower resources, relying on the primary frequency modulation of traditional units can no longer meet the requirements of frequency stability of Yunnan asynchronous networking system. For the power reverse adjustment caused by the water hammer effect of large hydropower, a wind-storage combined frequency modulation control strategy considering load frequency characteristics is proposed. Firstly, the frequency domain model transfer function of traditional power (turbine), doubly-fed wind turbine, energy storage system and comprehensive load is established. Then, the DC power flow method is used to simplify the electric network, and the analytical formula of frequency response of wind-storage node under load disturbance is obtained. The four\|machines system with wind\|stroage, water turbine and lood is built in the electromechanical transient simulation sofware PSD\|BPA. Through the theoretical analysis of the analytical formula and the simulation verification of the four-machine system, the influence of the proportion of static load model and frequency characteristic parameters and the proportion of energy storage on the system frequency is analyzed. The results show that the wind-storage combined frequency modulation considering the load frequency characteristics can effectively reduce the system frequency deviation.
With the increase of the proportion of new energy, in the Yunnan power grid with abundant hydropower resources, relying on the primary frequency modulation of traditional units can no longer meet the requirements of frequency stability of Yunnan asynchronous networking system. For the power reverse adjustment caused by the water hammer effect of large hydropower, a wind-storage combined frequency modulation control strategy considering load frequency characteristics is proposed. Firstly, the frequency domain model transfer function of traditional power (turbine), doubly-fed wind turbine, energy storage system and comprehensive load is established. Then, the DC power flow method is used to simplify the electric network, and the analytical formula of frequency response of wind-storage node under load disturbance is obtained. The four\|machines system with wind\|stroage, water turbine and lood is built in the electromechanical transient simulation sofware PSD\|BPA. Through the theoretical analysis of the analytical formula and the simulation verification of the four-machine system, the influence of the proportion of static load model and frequency characteristic parameters and the proportion of energy storage on the system frequency is analyzed. The results show that the wind-storage combined frequency modulation considering the load frequency characteristics can effectively reduce the system frequency deviation.
2023, 50(12):66-73.
DOI: 10.12177/emca.2023.141
Abstract:
Aiming at the harmonic problem of stator phase current in the vector control system of a dual three-phase permanent magnet synchronous motor (PMSM), a magnetic field oriented control strategy based on the space vector pulse width modulation (SVPWM) algorithm with the maximum four-vector is proposed on the basis of using a conventional two-vector SVPWM algorithm. Secondly, to solve the problem of large computation and complex design of the SVPWM algorithm with maximum four vectors, an improved magnetic field oriented control strategy based on the SVPWM algorithm with virtual voltage vector is proposed. Finally, the effectiveness of the proposed improved control algorithm strategy is verified by MATLAB/Simulink simulation platform.
Aiming at the harmonic problem of stator phase current in the vector control system of a dual three-phase permanent magnet synchronous motor (PMSM), a magnetic field oriented control strategy based on the space vector pulse width modulation (SVPWM) algorithm with the maximum four-vector is proposed on the basis of using a conventional two-vector SVPWM algorithm. Secondly, to solve the problem of large computation and complex design of the SVPWM algorithm with maximum four vectors, an improved magnetic field oriented control strategy based on the SVPWM algorithm with virtual voltage vector is proposed. Finally, the effectiveness of the proposed improved control algorithm strategy is verified by MATLAB/Simulink simulation platform.
2023, 50(12):74-82.
DOI: 10.12177/emca.2023.159
Abstract:
The rare earth permanent magnet synchronous motor (PMSM) has superior performance, but the high price of rare earth permanent magnet material leads to the increase of motor cost. A new type of permanent magnet synchronous motor with less rare earth is presented, and the permanent magnet is of the combined magnet poles Halbach structure. The structural characteristics of the less rare earth combined pole permanent magnet synchronous motor are analyzed, and on this basis, three kinds of combined magnet poles Halbach permanent magnet synchronous motor topology structures of T-type, HAT type and LREH type are proposed. Three less rare earth permanent magnet synchronous motors are analyzed in terms of no-load back electromotive force, no-load cogging torque and rated load electromagnetic torque and compared with rare-earth permanent magnet synchronous motors. The effect of the thickness of NdFeB and ferrite permanent magnets on the material cost of less rare earth permanent magnet synchronous motor with combined magnet poles is studied under equal torque conditions. The material costs of rare earth permanent magnet synchronous motor and three kinds of less rare earth permanent magnet synchronous motor is compared. Finite element simulation results show that LREH type less rare earth combined pole Halbach permanent magnet synchronous motor has better torque performance and lower material cost.
The rare earth permanent magnet synchronous motor (PMSM) has superior performance, but the high price of rare earth permanent magnet material leads to the increase of motor cost. A new type of permanent magnet synchronous motor with less rare earth is presented, and the permanent magnet is of the combined magnet poles Halbach structure. The structural characteristics of the less rare earth combined pole permanent magnet synchronous motor are analyzed, and on this basis, three kinds of combined magnet poles Halbach permanent magnet synchronous motor topology structures of T-type, HAT type and LREH type are proposed. Three less rare earth permanent magnet synchronous motors are analyzed in terms of no-load back electromotive force, no-load cogging torque and rated load electromagnetic torque and compared with rare-earth permanent magnet synchronous motors. The effect of the thickness of NdFeB and ferrite permanent magnets on the material cost of less rare earth permanent magnet synchronous motor with combined magnet poles is studied under equal torque conditions. The material costs of rare earth permanent magnet synchronous motor and three kinds of less rare earth permanent magnet synchronous motor is compared. Finite element simulation results show that LREH type less rare earth combined pole Halbach permanent magnet synchronous motor has better torque performance and lower material cost.
2023, 50(12):83-91.
DOI: 10.12177/emca.2023.153
Abstract:
In order to improve the dynamic performance of single-phase two-level PWM rectifier, this paper proposes an improves control strategy based on the dual closed-loop control method of PI control in the traditional outer loop and power feed-forward decoupling direct power control in the inner loop, and introduces a voltage outer loop based on Linear Automatic Disturbance Rejection Control (LADRC) to reduce the overshoot of the DC side voltage and improve the response speed of the system, and enhance its anti-load disturbance ability. Furthermore, on the basis of power feed-forward decoupling control, SOGI is introduced to construct virtual quadrature components to improve the tracking ability of current to voltage on the grid side and improve the dynamic performance of the system. Finally, the system simulation model is established by MATLAB/Simulink and simulates, and the feasibility and effectiveness of the proposed improved control strategy are verified.
In order to improve the dynamic performance of single-phase two-level PWM rectifier, this paper proposes an improves control strategy based on the dual closed-loop control method of PI control in the traditional outer loop and power feed-forward decoupling direct power control in the inner loop, and introduces a voltage outer loop based on Linear Automatic Disturbance Rejection Control (LADRC) to reduce the overshoot of the DC side voltage and improve the response speed of the system, and enhance its anti-load disturbance ability. Furthermore, on the basis of power feed-forward decoupling control, SOGI is introduced to construct virtual quadrature components to improve the tracking ability of current to voltage on the grid side and improve the dynamic performance of the system. Finally, the system simulation model is established by MATLAB/Simulink and simulates, and the feasibility and effectiveness of the proposed improved control strategy are verified.
10 Improved Finite Control Set Model Predictive Speed Control for Permanent Magnet Synchronous Motor
2023, 50(12):92-100.
DOI: 10.12177/emca.2023.142
Abstract:
In the traditional finite set model predictive speed control strategy of permanent magnet synchronous motor, the direction of voltage vector is fixed, the range of optional vector is limited, and the sudden change of output voltage leads to large current ripple. Therefore, a direct speed control strategy of finite control set model predictive control (FCS-MPC) based on voltage subdivision is proposed. In the proposed concept, a group of finite voltage subdivision vectors with adjustable amplitude and movable origin are introduced into FCS-MPC scheme as candidate voltages, and bilinear transform (Tustin transform) integral approximation is used to obtain more accurate current prediction. The controller could predict the future current and speed, and uses pulse width modulation to output the optimal subdivision voltage. The simulation results of permanent magnet synchronous motor driven by two-level three-phase inverter show that compared with the traditional FCS-MPC scheme, this method effectively reduces the current ripple, broades the range of voltage vector selection and improves the robustness of the motor.
In the traditional finite set model predictive speed control strategy of permanent magnet synchronous motor, the direction of voltage vector is fixed, the range of optional vector is limited, and the sudden change of output voltage leads to large current ripple. Therefore, a direct speed control strategy of finite control set model predictive control (FCS-MPC) based on voltage subdivision is proposed. In the proposed concept, a group of finite voltage subdivision vectors with adjustable amplitude and movable origin are introduced into FCS-MPC scheme as candidate voltages, and bilinear transform (Tustin transform) integral approximation is used to obtain more accurate current prediction. The controller could predict the future current and speed, and uses pulse width modulation to output the optimal subdivision voltage. The simulation results of permanent magnet synchronous motor driven by two-level three-phase inverter show that compared with the traditional FCS-MPC scheme, this method effectively reduces the current ripple, broades the range of voltage vector selection and improves the robustness of the motor.
2023, 50(12):101-107.
DOI: 10.12177/emca.2023.149
Abstract:
The change of the main magnetic field caused by the interference of the permanent magnet motor stator will cause the performance of the actual motor to deviate from the design value. The influence of interference on the stress and strain of stator core is studied according to the ferromagnetism theory and magnetic circuit law to optimize the design. The solution model is established and the simulation calculation and experiment are carried out based on a 560 kW motor. The analysis results in this paper can be used for reference in the optimization design of permanent magnet motor.
The change of the main magnetic field caused by the interference of the permanent magnet motor stator will cause the performance of the actual motor to deviate from the design value. The influence of interference on the stress and strain of stator core is studied according to the ferromagnetism theory and magnetic circuit law to optimize the design. The solution model is established and the simulation calculation and experiment are carried out based on a 560 kW motor. The analysis results in this paper can be used for reference in the optimization design of permanent magnet motor.
2023, 50(12):108-117.
DOI: 10.12177/emca.2023.147
Abstract:
In order to solve the problem of wide rotor bearingless switched reluctance motors are prone to large torque ripple during operation due to the switching power supply method and double salient iron core structure, the rotor structure of a bearingless switched reluctance motor with wide rotor is improved by slotting on both sides of the rotor. By increasing the air gap magnetic resistance near the slots, the tangential air gap magnetic density used to generate torque can be increased, so that the torque ripple can be reduced. After the slots are parameterized, the control variates method is used to analyze the impact of slotting parameters on torque performance, and the slotting parameters are finally determined with the goal of optimizing performance indicators. By using the method of field circuit coupling, the finite element analysis model of the motor and the direct instantaneous torque control circuit model are combined to achieve the dynamic operation of the motor system. The simulation results show that slotting on the rotor can effectively reduce the torque ripple of the bearingless switched reluctance motor with wide rotor, and improve the average torque, while has little impact on radial suspension force.
In order to solve the problem of wide rotor bearingless switched reluctance motors are prone to large torque ripple during operation due to the switching power supply method and double salient iron core structure, the rotor structure of a bearingless switched reluctance motor with wide rotor is improved by slotting on both sides of the rotor. By increasing the air gap magnetic resistance near the slots, the tangential air gap magnetic density used to generate torque can be increased, so that the torque ripple can be reduced. After the slots are parameterized, the control variates method is used to analyze the impact of slotting parameters on torque performance, and the slotting parameters are finally determined with the goal of optimizing performance indicators. By using the method of field circuit coupling, the finite element analysis model of the motor and the direct instantaneous torque control circuit model are combined to achieve the dynamic operation of the motor system. The simulation results show that slotting on the rotor can effectively reduce the torque ripple of the bearingless switched reluctance motor with wide rotor, and improve the average torque, while has little impact on radial suspension force.
2023, 50(12):118-125.
DOI: 10.12177/emca.2023.150
Abstract:
Aiming at the problem of protection failure caused by abnormal intelligent terminals in active distribution network, an adaptive protection method for distribution network with abnormal intelligent terminals is proposed. This method judges the on-off of the switch and the running state of each smart terminal unit (STU) according to the measured switching and current of each STU. An adaptive protection scheme and criterion suitable for line and ring network cabinet are designed. In the case of abnormal STU, the traditional regional protection and adaptive protection are analyzed respectively. The method proposed in this paper is verified by PSCAD simulation software. The results show that the method can effectively deal with the protection failure caused by STU abnormality.
Aiming at the problem of protection failure caused by abnormal intelligent terminals in active distribution network, an adaptive protection method for distribution network with abnormal intelligent terminals is proposed. This method judges the on-off of the switch and the running state of each smart terminal unit (STU) according to the measured switching and current of each STU. An adaptive protection scheme and criterion suitable for line and ring network cabinet are designed. In the case of abnormal STU, the traditional regional protection and adaptive protection are analyzed respectively. The method proposed in this paper is verified by PSCAD simulation software. The results show that the method can effectively deal with the protection failure caused by STU abnormality.
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Electric Machines & Control Application ® 2025
Supported by:Beijing E-Tiller Technology Development Co., Ltd.
沪ICP备16038578号-3
Electric Machines & Control Application ® 2025
Supported by:Beijing E-Tiller Technology Development Co., Ltd.
