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Volume 51,Issue 10,2024 Table of Contents
2024, 51(10):1-8.
DOI: 10.12177/emca.2024.099
Abstract:
Taking self-ventilated traction motor as the research object, the characteristics of aerodynamic noise were analyzed in this paper, including the physical measurement of noise, identification and classification of aerodynamic noise. Through no-load noise test, the noise components of the prototype machine were analyzed and the main noise sources were identified. Based on CFD theory, the steady flow field of the whole motor was calculated to obtain parameters such as system wind resistance and velocity distribution. The motor aerodynamic noise was then predicted and evaluated according to flow characteristics. Noise reduction was achieved at the source by optimizing the design of the air inlet and outlet structures and the power fan. Meanwhile, an acoustic enclosure was used to control noise along the transmission path. The test results showed that the aerodynamic noise of the motor was significantly improved by adopting ventilation optimization design and acoustic measures at high rotational speeds
Taking self-ventilated traction motor as the research object, the characteristics of aerodynamic noise were analyzed in this paper, including the physical measurement of noise, identification and classification of aerodynamic noise. Through no-load noise test, the noise components of the prototype machine were analyzed and the main noise sources were identified. Based on CFD theory, the steady flow field of the whole motor was calculated to obtain parameters such as system wind resistance and velocity distribution. The motor aerodynamic noise was then predicted and evaluated according to flow characteristics. Noise reduction was achieved at the source by optimizing the design of the air inlet and outlet structures and the power fan. Meanwhile, an acoustic enclosure was used to control noise along the transmission path. The test results showed that the aerodynamic noise of the motor was significantly improved by adopting ventilation optimization design and acoustic measures at high rotational speeds
2024, 51(10):9-18.
DOI: 10.12177/emca.2024.105
Abstract:
To address the problem that the voltage monitor has difficulty accurately locating ground faults on the low-voltage side of the distribution transformer, this paper proposed an optimized voltage dip (Vdip) method based on negative sequence voltage changes. First, the asymmetric fault location probability calculation method was used to compare the negative sequence current of the feeder substation and the negative sequence voltage on the low-voltage side of the distribution transformer to determine the probability of asymmetric fault location. Then, based on this probability, the ground fault location was confirmed. Finally, to address issues such as frequency deviation and inter-harmonics, an inter-harmonic elimination method based on sliding window averaging was proposed. Through simulation experiment on the short-circuited auxiliary resistance of the resonant grounding distribution network, and verified in a 22 kV resonant grounding network of a certain regional power grid, the average ground fault location error was 1.06 km. Experimental results showed that the proposed method could achieve a fault location accuracy of up to 98.7% while avoiding inter-harmonic interference, and the model performance metrics were better than existing methods.
To address the problem that the voltage monitor has difficulty accurately locating ground faults on the low-voltage side of the distribution transformer, this paper proposed an optimized voltage dip (Vdip) method based on negative sequence voltage changes. First, the asymmetric fault location probability calculation method was used to compare the negative sequence current of the feeder substation and the negative sequence voltage on the low-voltage side of the distribution transformer to determine the probability of asymmetric fault location. Then, based on this probability, the ground fault location was confirmed. Finally, to address issues such as frequency deviation and inter-harmonics, an inter-harmonic elimination method based on sliding window averaging was proposed. Through simulation experiment on the short-circuited auxiliary resistance of the resonant grounding distribution network, and verified in a 22 kV resonant grounding network of a certain regional power grid, the average ground fault location error was 1.06 km. Experimental results showed that the proposed method could achieve a fault location accuracy of up to 98.7% while avoiding inter-harmonic interference, and the model performance metrics were better than existing methods.
2024, 51(10):19-28.
DOI: 10.12177/emca.2024.097
Abstract:
To address the problem of high common-mode voltage in deadbeat predictive control for permanent magnet synchronous motor (PMSM), this paper proposed the use of opposite-phases basic voltage vectors within one control cycle to generate a virtual zero voltage vector, which suppressed the common-mode voltage. A dynamic selection method for generating virtual voltage vectors was adopted to decrease switching frequency. To further improve the performances of deadbeat predictive control, 12 virtual non-zero voltage vectors were introduced to expand candidate voltage vector set. Simulation results showed that, compared to using 7 basic candidate voltage vectors, the deadbeat predictive control based on 19 candidate voltage vectors reduced torque ripple by 6.89%, decreased flux linkage ripple by 13.33% and effectively suppressed common-mode voltage. The dynamic selection method for virtual voltage vector generation reduced the switching frequency by 25.89% compared to the fixed generation method. Although this method significantly improved system performance, it increased the number of iterations, leading to a substantial increase in computation burden. To enhance the real-time performance of the algorithm, a simplified method was proposed, which determined the optimal voltage vector by identifying the region where the ideal voltage vector resided, eliminating the need for exhaustive calculations and reducing the computation burden. Real-time experiments based on the STM32H743IIT6 microcontroller showed that compared with using 7 voltage vectors, deadbeat predictive control using 19 voltage vectors increased execution time by 273.40%, while the optimal voltage vector simplified determination method reduced execution time by 88.09%.
To address the problem of high common-mode voltage in deadbeat predictive control for permanent magnet synchronous motor (PMSM), this paper proposed the use of opposite-phases basic voltage vectors within one control cycle to generate a virtual zero voltage vector, which suppressed the common-mode voltage. A dynamic selection method for generating virtual voltage vectors was adopted to decrease switching frequency. To further improve the performances of deadbeat predictive control, 12 virtual non-zero voltage vectors were introduced to expand candidate voltage vector set. Simulation results showed that, compared to using 7 basic candidate voltage vectors, the deadbeat predictive control based on 19 candidate voltage vectors reduced torque ripple by 6.89%, decreased flux linkage ripple by 13.33% and effectively suppressed common-mode voltage. The dynamic selection method for virtual voltage vector generation reduced the switching frequency by 25.89% compared to the fixed generation method. Although this method significantly improved system performance, it increased the number of iterations, leading to a substantial increase in computation burden. To enhance the real-time performance of the algorithm, a simplified method was proposed, which determined the optimal voltage vector by identifying the region where the ideal voltage vector resided, eliminating the need for exhaustive calculations and reducing the computation burden. Real-time experiments based on the STM32H743IIT6 microcontroller showed that compared with using 7 voltage vectors, deadbeat predictive control using 19 voltage vectors increased execution time by 273.40%, while the optimal voltage vector simplified determination method reduced execution time by 88.09%.
2024, 51(10):29-39.
DOI: 10.12177/emca.2024.102
Abstract:
To address the challenges posed by multiple coupling points and high difficulty in controlling levitation in a three-track electromagnetic levitation system arranged in a triangular prism configuration, a fuzzy sliding mode control method was proposed to achieve independent control of each coupling point. Based on the specific structure of the three-track electromagnetic levitation system, a decoupling analysis of the rotational motion of the system model was conducted to obtain control variables that could independently control the rotational offset angle and the levitation air gap height. Fuzzy input, output, and rules were established, and the fuzzy control variables were integrated with system errors for sliding mode control, enabling the system's levitation error to converge rapidly to zero. To verify the effectiveness of the fuzzy sliding mode controller in controlling the system's levitation, both simulation and experimental models were developed. The results showed that compared to traditional control methods, the fuzzy sliding mode control had a faster response, stronger anti-interference ability, and was beneficial for vibration control during the levitation process.
To address the challenges posed by multiple coupling points and high difficulty in controlling levitation in a three-track electromagnetic levitation system arranged in a triangular prism configuration, a fuzzy sliding mode control method was proposed to achieve independent control of each coupling point. Based on the specific structure of the three-track electromagnetic levitation system, a decoupling analysis of the rotational motion of the system model was conducted to obtain control variables that could independently control the rotational offset angle and the levitation air gap height. Fuzzy input, output, and rules were established, and the fuzzy control variables were integrated with system errors for sliding mode control, enabling the system's levitation error to converge rapidly to zero. To verify the effectiveness of the fuzzy sliding mode controller in controlling the system's levitation, both simulation and experimental models were developed. The results showed that compared to traditional control methods, the fuzzy sliding mode control had a faster response, stronger anti-interference ability, and was beneficial for vibration control during the levitation process.
2024, 51(10):40-50.
DOI: 10.12177/emca.2024.109
Abstract:
The potential safety risks and economic losses caused by open-neutral and open-phase faults in low-voltage distribution networks have been longstanding challenges for power grid companies. With the popularization of intelligent detection equipment in power grids, fault detection can now be performed using voltage and sequence current data collected by smart meters on the low-voltage side. This paper first established a hybrid model, TNN-BL, based on transformer neural network (TNN) and bi-directional long short-term memory (Bi-LSTM). Secondly, by selecting appropriate loss functions and regularization functions, the model was refined to further improve its detection performance. Finally, the model performance was validated using a dataset from the China Southern Power Grid. Experimental results showed that the proposed method had a more effective feature extraction capability, higher detection accuracy and stronger robustness compared to other fault detection methods.
The potential safety risks and economic losses caused by open-neutral and open-phase faults in low-voltage distribution networks have been longstanding challenges for power grid companies. With the popularization of intelligent detection equipment in power grids, fault detection can now be performed using voltage and sequence current data collected by smart meters on the low-voltage side. This paper first established a hybrid model, TNN-BL, based on transformer neural network (TNN) and bi-directional long short-term memory (Bi-LSTM). Secondly, by selecting appropriate loss functions and regularization functions, the model was refined to further improve its detection performance. Finally, the model performance was validated using a dataset from the China Southern Power Grid. Experimental results showed that the proposed method had a more effective feature extraction capability, higher detection accuracy and stronger robustness compared to other fault detection methods.
2024, 51(10):51-63.
DOI: 10.12177/emca.2024.101
Abstract:
To address the issue of large speed fluctuations caused by sudden load changes in the speed control system of permanent magnet synchronous motor, this paper proposed a novel model?free control scheme for the speed loop based on fractional-order extended sliding mode disturbance observer (FOESMDO). The new algorithm improved the dynamic and static performances of the speed control system by establishing a new ultra-local model for the permanent magnet synchronous motor, which did not rely on motor parameters. With this model as the research object, a new model-free sliding mode control scheme was designed using fast terminal sliding mode control and an improved sliding mode switching function. To enhance the accuracy of disturbance estimation and reduce the chattering phenomenon in sliding mode control, the improved algorithm employed a FOESMDO for online estimation of unknown parts in the ultra-local structure. Finally, simulation comparison was made between the proposed fast terminal sliding mode control method with a new switching function based on FOESMDO and traditional methods, which verified the superior performance of the new model-free control algorithm (FOESMDO-ISFFTSMC) in improving the response speed and anti-interference property of the speed control system.
To address the issue of large speed fluctuations caused by sudden load changes in the speed control system of permanent magnet synchronous motor, this paper proposed a novel model?free control scheme for the speed loop based on fractional-order extended sliding mode disturbance observer (FOESMDO). The new algorithm improved the dynamic and static performances of the speed control system by establishing a new ultra-local model for the permanent magnet synchronous motor, which did not rely on motor parameters. With this model as the research object, a new model-free sliding mode control scheme was designed using fast terminal sliding mode control and an improved sliding mode switching function. To enhance the accuracy of disturbance estimation and reduce the chattering phenomenon in sliding mode control, the improved algorithm employed a FOESMDO for online estimation of unknown parts in the ultra-local structure. Finally, simulation comparison was made between the proposed fast terminal sliding mode control method with a new switching function based on FOESMDO and traditional methods, which verified the superior performance of the new model-free control algorithm (FOESMDO-ISFFTSMC) in improving the response speed and anti-interference property of the speed control system.
2024, 51(10):64-75.
DOI: 10.12177/emca.2024.106
Abstract:
The multiphase self-excited synchronous motor achieves brushless excitation in the zero-low speed domain by injecting high-frequency harmonic current excitation into the stator side. However, existing research has not fully explored the phase of the injected high-frequency current, limiting further improvement in excitation current and torque at zero-low speed domain. To address the above problems, this paper first derived mathematical formulas based on the principle of fractional slot concentrated winding magnetomotive force, and analyzed the mechanism of high-frequency current injection for excitation. Next, the effect of the high-frequency current phase on excitation performance was investigated, and a phase optimization strategy was proposed. Finally, a self-excited motor model was established in Maxwell, and finite element analysis was conducted to verify the proposed strategy. The research results showed that with the high-frequency current phase optimization strategy, at 100 r/min, the induced potential increased by 17.5%, the excitation current rose by 7.5%, torque increased by 6.6% and the torque ripple decreased by 71.58%.
The multiphase self-excited synchronous motor achieves brushless excitation in the zero-low speed domain by injecting high-frequency harmonic current excitation into the stator side. However, existing research has not fully explored the phase of the injected high-frequency current, limiting further improvement in excitation current and torque at zero-low speed domain. To address the above problems, this paper first derived mathematical formulas based on the principle of fractional slot concentrated winding magnetomotive force, and analyzed the mechanism of high-frequency current injection for excitation. Next, the effect of the high-frequency current phase on excitation performance was investigated, and a phase optimization strategy was proposed. Finally, a self-excited motor model was established in Maxwell, and finite element analysis was conducted to verify the proposed strategy. The research results showed that with the high-frequency current phase optimization strategy, at 100 r/min, the induced potential increased by 17.5%, the excitation current rose by 7.5%, torque increased by 6.6% and the torque ripple decreased by 71.58%.
2024, 51(10):76-87.
DOI: 10.12177/emca.2024.098
Abstract:
Torque drop during winding commutation is one of the main causes of significant torque ripple in switched reluctance motors. Based on an analysis of the causes of torque ripple in conventional switched reluctance motors, this paper studied a torque ripple suppression method that combined structural optimization with direct instantaneous torque control to address this issue. The method added an internal stator and auxiliary windings, forming a circumferentially staggered switched reluctance motor. The auxiliary windings on the internal stator provided supplementary torque to compensate for the torque drop in the main windings on the external stator during commutation. A direct instantaneous torque control strategy was then designed, which switched the operating mode of the power converter based on torque deviation signals and sector signals, offering fast response and precise torque control. Finally, a field-circuit coupling co-simulation environment was constructed for the six-phase winding of the motor. The torque and speed characteristics were comparatively analyzed under three operating conditions: starting, acceleration/deceleration, and load increase/reduction. The simulation results showed that the improved motor exhibited excellent torque ripple suppression and good operational characteristics.
Torque drop during winding commutation is one of the main causes of significant torque ripple in switched reluctance motors. Based on an analysis of the causes of torque ripple in conventional switched reluctance motors, this paper studied a torque ripple suppression method that combined structural optimization with direct instantaneous torque control to address this issue. The method added an internal stator and auxiliary windings, forming a circumferentially staggered switched reluctance motor. The auxiliary windings on the internal stator provided supplementary torque to compensate for the torque drop in the main windings on the external stator during commutation. A direct instantaneous torque control strategy was then designed, which switched the operating mode of the power converter based on torque deviation signals and sector signals, offering fast response and precise torque control. Finally, a field-circuit coupling co-simulation environment was constructed for the six-phase winding of the motor. The torque and speed characteristics were comparatively analyzed under three operating conditions: starting, acceleration/deceleration, and load increase/reduction. The simulation results showed that the improved motor exhibited excellent torque ripple suppression and good operational characteristics.
2024, 51(10):88-97.
DOI: 10.12177/emca.2024.110
Abstract:
Fractional slot concentrated winding (FSCW) structure of induction motors contains abundant magnetomotive force harmonics in the air gap. Direct starting of the motor will result in huge inrush current and high torque ripple. Selecting an appropriate motor starting method ensures the necessary energy for starting the motor while minimizing costs and improving efficiency. This paper investigated two different starting methods for induction motors based on the FSCW structure: hard start and soft start. The full voltage method (hard start) was the simplest method but it might adversely affect motor lifespan. Alternatively, reduced voltage and frequency start (soft start) could reduce energy consumption during starting. First, the mathematical model of the induction motor was established based on winding theory. The starting torque and the impact of non-dominant pole-pair harmonic magnetic fields on torque ripple were analyzed under both hard and soft start conditions using electromagnetic torque theory. Then, the expression of the electromagnetic torque was derived using the virtual displacement method. Finally, the electromagnetic torque and torque ripple under the two starting methods were discussed based on the electromagnetic torque theory. In addition, the feasibility and stability of soft start were verified through theoretical calculation, finite element simulation and experimental validation.
Fractional slot concentrated winding (FSCW) structure of induction motors contains abundant magnetomotive force harmonics in the air gap. Direct starting of the motor will result in huge inrush current and high torque ripple. Selecting an appropriate motor starting method ensures the necessary energy for starting the motor while minimizing costs and improving efficiency. This paper investigated two different starting methods for induction motors based on the FSCW structure: hard start and soft start. The full voltage method (hard start) was the simplest method but it might adversely affect motor lifespan. Alternatively, reduced voltage and frequency start (soft start) could reduce energy consumption during starting. First, the mathematical model of the induction motor was established based on winding theory. The starting torque and the impact of non-dominant pole-pair harmonic magnetic fields on torque ripple were analyzed under both hard and soft start conditions using electromagnetic torque theory. Then, the expression of the electromagnetic torque was derived using the virtual displacement method. Finally, the electromagnetic torque and torque ripple under the two starting methods were discussed based on the electromagnetic torque theory. In addition, the feasibility and stability of soft start were verified through theoretical calculation, finite element simulation and experimental validation.
2024, 51(10):98-106.
DOI: 10.12177/emca.2024.107
Abstract:
This paper investigated a hybrid excitation flux switching linear magnetic suspension motor (HEFSLMSM), which is used in maglev trains. The extended state observer of the original active disturbance rejection control (ADRC) algorithm, designed using the traditional fal function, often leads to issues such as chattering, slow convergence speed and excessive overshoot. To improve the performance of suspension system, an improved ADRC strategy was proposed. Based on the special principle and operation mechanism of HEFSLMSM, the mathematical model of the system was derived, including the motor excitation circuit voltage equation, the magnetic suspension force equation and motion equation. A new sfal function, which met the criteria of “small error, large gain, large error, small gain, continuous smoothness, differentiability everywhere, symmetry at the origin,” was designed to replace the original fal function. An improved ADRC simulation model was established and compared with ADRC and proportional integral devivative controllers through simulation experiments. The simulation results showed that the HEFSLMSM maglev system using the improved ADRC exhibited significant advantages in dynamic performance, effectively suppressing various uncertain disturbances and ensuring the system stability and accuracy.
This paper investigated a hybrid excitation flux switching linear magnetic suspension motor (HEFSLMSM), which is used in maglev trains. The extended state observer of the original active disturbance rejection control (ADRC) algorithm, designed using the traditional fal function, often leads to issues such as chattering, slow convergence speed and excessive overshoot. To improve the performance of suspension system, an improved ADRC strategy was proposed. Based on the special principle and operation mechanism of HEFSLMSM, the mathematical model of the system was derived, including the motor excitation circuit voltage equation, the magnetic suspension force equation and motion equation. A new sfal function, which met the criteria of “small error, large gain, large error, small gain, continuous smoothness, differentiability everywhere, symmetry at the origin,” was designed to replace the original fal function. An improved ADRC simulation model was established and compared with ADRC and proportional integral devivative controllers through simulation experiments. The simulation results showed that the HEFSLMSM maglev system using the improved ADRC exhibited significant advantages in dynamic performance, effectively suppressing various uncertain disturbances and ensuring the system stability and accuracy.
2024, 51(10):107-119.
DOI: 10.12177/emca.2024.094
Abstract:
A large number of non-dominant pole-pair harmonics are present in fractional slot concentrated winding (FSCW) induction motors, resulting in high torque ripple and core losses. To address this problem, a FSCW doubly-fed induction motor with a 15-slot stator and 18-slot rotor was used to study the torque characteristics and core loss characteristics of this type of motor. Firstly, the structure and working principle of FSCW doubly-fed induction motor were introduced, and the stator current equation under doubly-fed operation was derived. Secondly, the sum of self-inductance and mutual inductance of the first n harmonics of the stator and rotor under a specific pole-slot fit was calculated using the winding function method and turns function method. Then, the electromagnetic torque was theoretically calculated based on the virtual displacement method, and the results were compared and analyzed with the finite element simulation results as well as the experimental measurement results. Finally, the torque characteristics and core loss characteristics under different operating conditions were analyzed, revealing the variation patterns of electromagnetic torque ripple frequency and core losses at different slip rates. Specifically, the torque ripple frequency increased as the slip rate decreased, while core losses decreased with the reduction in slip rate.
A large number of non-dominant pole-pair harmonics are present in fractional slot concentrated winding (FSCW) induction motors, resulting in high torque ripple and core losses. To address this problem, a FSCW doubly-fed induction motor with a 15-slot stator and 18-slot rotor was used to study the torque characteristics and core loss characteristics of this type of motor. Firstly, the structure and working principle of FSCW doubly-fed induction motor were introduced, and the stator current equation under doubly-fed operation was derived. Secondly, the sum of self-inductance and mutual inductance of the first n harmonics of the stator and rotor under a specific pole-slot fit was calculated using the winding function method and turns function method. Then, the electromagnetic torque was theoretically calculated based on the virtual displacement method, and the results were compared and analyzed with the finite element simulation results as well as the experimental measurement results. Finally, the torque characteristics and core loss characteristics under different operating conditions were analyzed, revealing the variation patterns of electromagnetic torque ripple frequency and core losses at different slip rates. Specifically, the torque ripple frequency increased as the slip rate decreased, while core losses decreased with the reduction in slip rate.
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沪ICP备16038578号-3
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.
