The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field, as well as the related differential leakage, attenuation, asynch...The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field, as well as the related differential leakage, attenuation, asynchronous parasitic torques have been discussed in great detail in the literature, but always separately, for a long time. However, systematization of the phenomenon still awaits. Therefore, it is worth summarizing the completeness of the phenomena in a single study – with a new approach at the same time-in order to reveal the relationships between them. The role of rotor slot number is emphasized much more than before. An existing, commonly used, but still impractical basic figure has been modified to more clearly demonstrate the response of the rotor for the harmonics of the stator. The need to treat differential leakage, asynchronous parasitic torques and attenuation together will be demonstrated: new formula for asynchronous parasitic torque is derived;the long-used characteristic curves for differential leakage and attenuation used separately so far was merged into one, correct curve in order to provide a correct design guide for the engineers.展开更多
The multi-phase motor drive system with multiple H-bridge power supply has high fault tolerance,which is widely used in aerospace,electric vehicle,ship integrated power system and other fields.In this paper,a fault-to...The multi-phase motor drive system with multiple H-bridge power supply has high fault tolerance,which is widely used in aerospace,electric vehicle,ship integrated power system and other fields.In this paper,a fault-tolerant control strategy based on decoupling control and stator current compensation is proposed for the propulsion system of five-phase PMSM with independent neutrals.Firstly,the mathematical model of PMSM is established by using vector space decoupling method;Secondly,a stator current compensation method is adopted to carry out fault-tolerant control after the motor has single-phase and two-phase open-circuit faults and the fault-tolerant control system based on decoupling control is established;Finally,the decoupling control model and the fault-tolerant control of stator current compensation are verified by the simulation and experiment.The simulation and experiment results show that the method can reduce the torque ripple caused by the stator winding open-circuit fault,and the operation performance of the motor under fault condition is significantly improved.展开更多
A general method of calculating the saturable leakage reactances of squirrelcage asynchronous motors is presented.The method synthesized the variety of effectswhich affect the saturation of leakage magnetic circuit.An...A general method of calculating the saturable leakage reactances of squirrelcage asynchronous motors is presented.The method synthesized the variety of effectswhich affect the saturation of leakage magnetic circuit.And the saturable reactances canbe precisely evaluated in any running condition.The computation results of Y-series mo-tors are in good agreement with the test ones.展开更多
For starting high-voltage asynchronous motor,the voltage regulator based on current-limiting transformer is presented in the paper. Its mathematical model needs to be established analyzing and designing voltage regula...For starting high-voltage asynchronous motor,the voltage regulator based on current-limiting transformer is presented in the paper. Its mathematical model needs to be established analyzing and designing voltage regulator of high-voltage asynchronous motor. The mathematical model of the current-limiting transformer is deduced based on basic circuit theory. It can be found that a continuous variation reactance can describe the current-limiting transformer during starting process. The two variables functions of current and voltage are transformed into one-variable functions,and thus system control is greatly simplified. The voltage regulator is simulated on the basis. The simulation results show that this model has enough accuracy. Finally, the high-voltage asynchronous motor voltage regulator based on current-limiting transformer is designed and tested on this model.展开更多
The heating calculation of three-phase squirrel- cage asynchronous motor on the condition of starting for a prescribed rotary angle is firstly studied with time dissection method and its corresponding algorithm is pro...The heating calculation of three-phase squirrel- cage asynchronous motor on the condition of starting for a prescribed rotary angle is firstly studied with time dissection method and its corresponding algorithm is provided. Then based upon the algorithm, a new method for motor power selection is established. Motor initial power determined by load power ischecked and modified in terms of time crit erion, heating criterion,and starting torque criterion.An appropriate motor power which meets three criterions is obtained at last, in the meantime, working displacement matrix andfrequency matrix used for control are acquired. Lifting motor of MDJ1800 low-level high- speed palletizer is taken as a reaI case in the paper.展开更多
Deduced the relationship between the power factor (PF) and the angular fre-quency according to the simplified equivalent circuit of asynchronous motor, forming a power factor auto-control system. An anti-interference ...Deduced the relationship between the power factor (PF) and the angular fre-quency according to the simplified equivalent circuit of asynchronous motor, forming a power factor auto-control system. An anti-interference circuit was also introduced in the middle voltage link of inverter to avoid the shift of the optimum PF point caused by the change of the load and the reliable run of the control system was assured. The experi-ment results show that it has a good self-adaptation in the whole scope of speed ad-justment and an obvious economization on energy while it runs under load.展开更多
There are several problems existing in the direct starting of asynchronous motor such as large starting current,reactive power absorption from network side and weak interference-resistance,etc.Aiming at this,a compreh...There are several problems existing in the direct starting of asynchronous motor such as large starting current,reactive power absorption from network side and weak interference-resistance,etc.Aiming at this,a comprehensive energy-saving optimization model of asynchronous motor for voltage regulation based on static synchronous compensator(STATCOM)is put forward.By analyzing the working principle and operation performance of static synchronous compensator regulating voltage,a new energy-efficient optimization method for asynchronous motor is proposed based on the voltage regulator model to achieve soft start,continuous dynamic reactive power compensation and the terminal voltage stability control.The multi-objective optimal operation of asynchronous motor is realized by controlling the inverter to adjust the reactive current dynamically.The strategy reduces the influence of starting current and grid voltage by soft starting,and realizes the function of reactive power compensation and terminal voltage stabilization.The effectiveness and superiority of the proposed model is verified by the simulation analysis and the results of comparison with the motor started directly.展开更多
For the two-level five-phase permanent magnet synchronous motor(FP-PMSM)drive system,an improved finite-control-set model predictive torque control(MPTC)strategy is adopted to reduce torque ripple and improve the cont...For the two-level five-phase permanent magnet synchronous motor(FP-PMSM)drive system,an improved finite-control-set model predictive torque control(MPTC)strategy is adopted to reduce torque ripple and improve the control performance of the system.The mathematical model of model reference adaptive system(MRAS)of FP-PMSM is derived and a method based on fractional order sliding mode(FOSM)is proposed to construct the model reference adaptive system(FOSMMRAS)to improve the motor speed estimation accuracy and eliminate the sliding mode integral saturation effect.The simulation results show that the FP-PMSM speed sensorless FCS-MPTC system based on FOSM-MRAS has strong robustness,good dynamic performance and static performance,and high reliability.展开更多
In this paper, the relationship between the protection and control of asynchronous motor and all sorts of protection devices for asynchronous motor are briefly expounded. The protection of motor has mainly developed i...In this paper, the relationship between the protection and control of asynchronous motor and all sorts of protection devices for asynchronous motor are briefly expounded. The protection of motor has mainly developed in three stages： thermal relay, electronic integrated protector, and microcomputer protector. In terms of sampling methods, the protection can be divided into two types： （1） the sampling current detection, which is implemented using a thermal relay with circuit breaker for the thermomagnetic tripping motor protection, and an electronic and solid state relay with circuit breaker and sof~ starter for the thermomagnetic tripping motor protection; （2） the sampling temperature detection, which is to directly detect electromotor winding temperature using bimetallic strip temperature relay, thermal protector, detecting coil, and heat resistance temperature relay. However, the second method is very expensive and difficult to maintain because a motor winding is necessary to directly bury, so it is used only in the cases requiring some frequent operations. Finally, the harmonious cooperation between overload protection device and motor or between overload protection device and short circuit protection device must be considered regardless of the protection device model.展开更多
Based on the principle of direct torque control,a DTC(Direct Torque Control)system with five-phase induction motor has been studied.Providing direct control of stator flux and electromagnetic torque by optimized volta...Based on the principle of direct torque control,a DTC(Direct Torque Control)system with five-phase induction motor has been studied.Providing direct control of stator flux and electromagnetic torque by optimized voltage vector,five-phase induction motor enhances flexibility of the invert states selection by increasing the number of voltage vectors,resulting in more precise control of stator flux and electromagnetic torque.The model of DTC for five-phase induction motor is constructed on equations and the method of approximate circle of torque track is used to conduct the simulation analysis of the system.The simulation results demonstrate that the DTC for five-phase induction motor control has merits of little calculation compared with vector control,simple structure,fast response and greater dynamic performance.展开更多
In the process of the continuous development of power electronics technology, motor control gradually toward more optimized, efficient direction. In this paper, the variable frequency asynchronous motor control system...In the process of the continuous development of power electronics technology, motor control gradually toward more optimized, efficient direction. In this paper, the variable frequency asynchronous motor control system as the research object, mainly discusses the design requirements and design content of PLC in the variable frequency asynchronous motor control system, to achieve the control effect of the motor.展开更多
Model predictive current control(MPCC)and model predictive torque control(MPTC)are two derivatives of model predictive control.These two control methods have demonstrated their strengths in the fault-tolerant control ...Model predictive current control(MPCC)and model predictive torque control(MPTC)are two derivatives of model predictive control.These two control methods have demonstrated their strengths in the fault-tolerant control of multiphase motor drives.To explore the inherent link,the pros and cons of two strategies,the performance analysis and comparative investigation of MPCC and MPTC are conducted through a five-phase permanent magnet synchronous motor with open-phase fault.In MPCC,the currents of fundamental and harmonic subspaces are simultaneously employed and constrained for a combined regulation of the open-circuit fault drive.In MPTC,apart from the torque and the stator flux related to fundamental subspace,the x-y currents are also considered and predicted to achieve the control of harmonic subspace.The principles of two methods are demonstrated in detail and the link is explored in terms of the cost function.Besides,the performance by two methods is experimentally assessed in terms of steady-state,transition,and dynamic tests.Finally,the advantages and disadvantages of each method are concluded.展开更多
In this paper,a robust torque speed estimator(RTSE)for linear parameter changing(LPC)system is proposed and designed for an encoderless five-phase permanent magnet assisted synchronous reluctance motor(5-phase PMa-Syn...In this paper,a robust torque speed estimator(RTSE)for linear parameter changing(LPC)system is proposed and designed for an encoderless five-phase permanent magnet assisted synchronous reluctance motor(5-phase PMa-SynRM).This estimator is utilized for estimating the rotor speed and the load torque as well as can solve the speed sensor fault problem,as the feedback speed information is obtained directly from the virtual sensor.In addition,this technique is able to enhance the 5-phase PMa-SynRM performance by estimating the load torque for the real time compensation.The stability analysis of the proposed estimator is performed via Schur complement along with Lyapunov analysis.Furthermore,for improving the 5-phase PMa-SynRM performance,five super-twisting sliding mode controllers(ST-SMCs)are employed with providing a robust response without the impacts of high chattering problem.A super-twisting sliding mode speed controller(ST-SMSC)is employed for controlling the PMa-SynRM rotor speed,and four super-twisting sliding mode current controllers(ST-SMCCs)are employed for controlling the 5-phase PMa-SynRM currents.The stability analysis and the experimental results indicate the effectiveness along with feasibility of the proposed RTSE and the ST-SMSC with ST-SMCCs approach for a 750-W 5-phase PMa-SynRM under load disturbance,parameters variations,single open-phase fault,and adjacent two-phase open circuit fault conditions.展开更多
The effect of a metal shell on the launch efficiency of an asynchronous coil launcher(coil AC pulse linear motor)remains insufficiently understood in terms of the underlying mechanisms and principles.To address this g...The effect of a metal shell on the launch efficiency of an asynchronous coil launcher(coil AC pulse linear motor)remains insufficiently understood in terms of the underlying mechanisms and principles.To address this gap,this study conducted extensive modelling simulations and calculations,varying the shell's conductivity,permeability,and dimensions.Through comparative analysis of these models,this paper identifies a unique‘tick-shaped efficiency curve’for the asynchronous coil launcher:the launch efficiency first decreases and then increases as the shell's electromagnetic parameters are enhanced.Enhancements that bolster the electromagnetic induction effect within the shell-such as increased conductivity,permeability and dimensions-are termed as the augmentation of electromagnetic parameters.This study delves into Lenz's law of electromagnetism to elucidate the observed phenomena,attributing them to the spatio-temporal force characteristics of the multipeak and multi-valley armature of the transmitting device,and the resulting‘tick-shaped efficiency curve’.A comprehensive summary of shell-related research in electromagnetic emission reveals that the driving current fundamentally dictates the shell's impact on launch efficiency.DC-driven launchers conform to the monotonic effect efficiency curve,whereas AC-driven launchers conform to the tick-shaped efficiency curve.展开更多
High-voltage asynchronous motors(HVAMs)face the problem of excessive internal temperatures during operation,which not only compromises operational safety,but may also shorten their service life.Therefore,finding an op...High-voltage asynchronous motors(HVAMs)face the problem of excessive internal temperatures during operation,which not only compromises operational safety,but may also shorten their service life.Therefore,finding an optimally effective cooling system is crucial.The performance of a centrifugal fan within the inner airflow path of an HV AM plays a critical role in determining the overall ventilation and cooling capacity.Installing splitter blades is an effective method to improve the performance of centrifugal fans.This study investigates the specific effects of splitter blade design on the performance of centrifugal fans,the internal flow field,and the rise in temperature of the motor.The performance of an internal fan in a 630 kW,10 kV HVAM is analyzed using a combination of flow-thermal analysis and experiment.First,the effects of splitter blades with varying lengths and peripheral positions on the external characteristic parameters of the fan are investigated.A nonlinear relationship between the length and peripheral position of the splitter blades and the external characteristic parameters is identified,and the optimal configuration is determined.Second,the influence of splitter blades with different lengths and peripheral positions on the flow field of the inner loop is analyzed.The mechanisms through which splitter blades enhance the passage vortices are clarified.Finally,a comparison of the temperature fields between the optimal splitter blade configuration and the original centrifugal fan design demonstrates the effectiveness of the splitter blades in improving the ventilation and cooling capacity.The results of this study provide an optimized solution for the heat dissipation and cooling systems of HVAMs and can serve as a reference for the design of cooling systems for similar motors.展开更多
The harmonics that appear in the squirrel cage asynchronous machine have been discussed in great detail in the literature for a long time. However, the systematization of the phenomenon is still pending, so we made an...The harmonics that appear in the squirrel cage asynchronous machine have been discussed in great detail in the literature for a long time. However, the systematization of the phenomenon is still pending, so we made an attempt to fill this gap in the previous parts of our study by elaborating formulas for calculation of parasitic torques. It was a general demand among those who work in this field towards the author to verify his formulas with measurements. In the literature, it seems,only one detailed, purposeful series of measurements has been published so far, the purpose of which was to investigate the effect of the number of rotor slots on the torque-speed characteristic curve of the machine. The main goal of this study is to verify the correctness of the formulas by comparing them with the referred series of measurements. Relying on this, the expected synchronous parasitic torques were developed for the frequently used rotor slot numbers-as a design guide for the engineer.Thus, together with our complete table for radial magnetic pull published in our previous work, the designer has all the principles, data and formulas available for the right number of rotor slots for his given machine and for the drive system. This brings this series of papers to an end.展开更多
文摘The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field, as well as the related differential leakage, attenuation, asynchronous parasitic torques have been discussed in great detail in the literature, but always separately, for a long time. However, systematization of the phenomenon still awaits. Therefore, it is worth summarizing the completeness of the phenomena in a single study – with a new approach at the same time-in order to reveal the relationships between them. The role of rotor slot number is emphasized much more than before. An existing, commonly used, but still impractical basic figure has been modified to more clearly demonstrate the response of the rotor for the harmonics of the stator. The need to treat differential leakage, asynchronous parasitic torques and attenuation together will be demonstrated: new formula for asynchronous parasitic torque is derived;the long-used characteristic curves for differential leakage and attenuation used separately so far was merged into one, correct curve in order to provide a correct design guide for the engineers.
文摘The multi-phase motor drive system with multiple H-bridge power supply has high fault tolerance,which is widely used in aerospace,electric vehicle,ship integrated power system and other fields.In this paper,a fault-tolerant control strategy based on decoupling control and stator current compensation is proposed for the propulsion system of five-phase PMSM with independent neutrals.Firstly,the mathematical model of PMSM is established by using vector space decoupling method;Secondly,a stator current compensation method is adopted to carry out fault-tolerant control after the motor has single-phase and two-phase open-circuit faults and the fault-tolerant control system based on decoupling control is established;Finally,the decoupling control model and the fault-tolerant control of stator current compensation are verified by the simulation and experiment.The simulation and experiment results show that the method can reduce the torque ripple caused by the stator winding open-circuit fault,and the operation performance of the motor under fault condition is significantly improved.
文摘A general method of calculating the saturable leakage reactances of squirrelcage asynchronous motors is presented.The method synthesized the variety of effectswhich affect the saturation of leakage magnetic circuit.And the saturable reactances canbe precisely evaluated in any running condition.The computation results of Y-series mo-tors are in good agreement with the test ones.
基金Natural Science Foundation of Shanghai,China(No.14ZR1419100)Shanghai Science and Technology Commission,China(No.13160501500)+1 种基金Shanghai Maritime University Foundation,China(No.20130430)the Ministry of Transport Foundation of China(No.2013329 810350)
文摘For starting high-voltage asynchronous motor,the voltage regulator based on current-limiting transformer is presented in the paper. Its mathematical model needs to be established analyzing and designing voltage regulator of high-voltage asynchronous motor. The mathematical model of the current-limiting transformer is deduced based on basic circuit theory. It can be found that a continuous variation reactance can describe the current-limiting transformer during starting process. The two variables functions of current and voltage are transformed into one-variable functions,and thus system control is greatly simplified. The voltage regulator is simulated on the basis. The simulation results show that this model has enough accuracy. Finally, the high-voltage asynchronous motor voltage regulator based on current-limiting transformer is designed and tested on this model.
基金This project is supported by National 863 Foundation (863-512-9801-06)
文摘The heating calculation of three-phase squirrel- cage asynchronous motor on the condition of starting for a prescribed rotary angle is firstly studied with time dissection method and its corresponding algorithm is provided. Then based upon the algorithm, a new method for motor power selection is established. Motor initial power determined by load power ischecked and modified in terms of time crit erion, heating criterion,and starting torque criterion.An appropriate motor power which meets three criterions is obtained at last, in the meantime, working displacement matrix andfrequency matrix used for control are acquired. Lifting motor of MDJ1800 low-level high- speed palletizer is taken as a reaI case in the paper.
基金Supported by Liaoning Educational Foundation(202183386)
文摘Deduced the relationship between the power factor (PF) and the angular fre-quency according to the simplified equivalent circuit of asynchronous motor, forming a power factor auto-control system. An anti-interference circuit was also introduced in the middle voltage link of inverter to avoid the shift of the optimum PF point caused by the change of the load and the reliable run of the control system was assured. The experi-ment results show that it has a good self-adaptation in the whole scope of speed ad-justment and an obvious economization on energy while it runs under load.
文摘There are several problems existing in the direct starting of asynchronous motor such as large starting current,reactive power absorption from network side and weak interference-resistance,etc.Aiming at this,a comprehensive energy-saving optimization model of asynchronous motor for voltage regulation based on static synchronous compensator(STATCOM)is put forward.By analyzing the working principle and operation performance of static synchronous compensator regulating voltage,a new energy-efficient optimization method for asynchronous motor is proposed based on the voltage regulator model to achieve soft start,continuous dynamic reactive power compensation and the terminal voltage stability control.The multi-objective optimal operation of asynchronous motor is realized by controlling the inverter to adjust the reactive current dynamically.The strategy reduces the influence of starting current and grid voltage by soft starting,and realizes the function of reactive power compensation and terminal voltage stabilization.The effectiveness and superiority of the proposed model is verified by the simulation analysis and the results of comparison with the motor started directly.
基金National Natural Science Foundation of China(No.51867012)。
文摘For the two-level five-phase permanent magnet synchronous motor(FP-PMSM)drive system,an improved finite-control-set model predictive torque control(MPTC)strategy is adopted to reduce torque ripple and improve the control performance of the system.The mathematical model of model reference adaptive system(MRAS)of FP-PMSM is derived and a method based on fractional order sliding mode(FOSM)is proposed to construct the model reference adaptive system(FOSMMRAS)to improve the motor speed estimation accuracy and eliminate the sliding mode integral saturation effect.The simulation results show that the FP-PMSM speed sensorless FCS-MPTC system based on FOSM-MRAS has strong robustness,good dynamic performance and static performance,and high reliability.
文摘In this paper, the relationship between the protection and control of asynchronous motor and all sorts of protection devices for asynchronous motor are briefly expounded. The protection of motor has mainly developed in three stages： thermal relay, electronic integrated protector, and microcomputer protector. In terms of sampling methods, the protection can be divided into two types： （1） the sampling current detection, which is implemented using a thermal relay with circuit breaker for the thermomagnetic tripping motor protection, and an electronic and solid state relay with circuit breaker and sof~ starter for the thermomagnetic tripping motor protection; （2） the sampling temperature detection, which is to directly detect electromotor winding temperature using bimetallic strip temperature relay, thermal protector, detecting coil, and heat resistance temperature relay. However, the second method is very expensive and difficult to maintain because a motor winding is necessary to directly bury, so it is used only in the cases requiring some frequent operations. Finally, the harmonious cooperation between overload protection device and motor or between overload protection device and short circuit protection device must be considered regardless of the protection device model.
文摘Based on the principle of direct torque control,a DTC(Direct Torque Control)system with five-phase induction motor has been studied.Providing direct control of stator flux and electromagnetic torque by optimized voltage vector,five-phase induction motor enhances flexibility of the invert states selection by increasing the number of voltage vectors,resulting in more precise control of stator flux and electromagnetic torque.The model of DTC for five-phase induction motor is constructed on equations and the method of approximate circle of torque track is used to conduct the simulation analysis of the system.The simulation results demonstrate that the DTC for five-phase induction motor control has merits of little calculation compared with vector control,simple structure,fast response and greater dynamic performance.
文摘In the process of the continuous development of power electronics technology, motor control gradually toward more optimized, efficient direction. In this paper, the variable frequency asynchronous motor control system as the research object, mainly discusses the design requirements and design content of PLC in the variable frequency asynchronous motor control system, to achieve the control effect of the motor.
基金supported in part by the Fundamental Research Funds for Central Universities under Grant JUSRP121020the Natural Science Foundation of Jiangsu Province under Grant BK20210475。
文摘Model predictive current control(MPCC)and model predictive torque control(MPTC)are two derivatives of model predictive control.These two control methods have demonstrated their strengths in the fault-tolerant control of multiphase motor drives.To explore the inherent link,the pros and cons of two strategies,the performance analysis and comparative investigation of MPCC and MPTC are conducted through a five-phase permanent magnet synchronous motor with open-phase fault.In MPCC,the currents of fundamental and harmonic subspaces are simultaneously employed and constrained for a combined regulation of the open-circuit fault drive.In MPTC,apart from the torque and the stator flux related to fundamental subspace,the x-y currents are also considered and predicted to achieve the control of harmonic subspace.The principles of two methods are demonstrated in detail and the link is explored in terms of the cost function.Besides,the performance by two methods is experimentally assessed in terms of steady-state,transition,and dynamic tests.Finally,the advantages and disadvantages of each method are concluded.
文摘In this paper,a robust torque speed estimator(RTSE)for linear parameter changing(LPC)system is proposed and designed for an encoderless five-phase permanent magnet assisted synchronous reluctance motor(5-phase PMa-SynRM).This estimator is utilized for estimating the rotor speed and the load torque as well as can solve the speed sensor fault problem,as the feedback speed information is obtained directly from the virtual sensor.In addition,this technique is able to enhance the 5-phase PMa-SynRM performance by estimating the load torque for the real time compensation.The stability analysis of the proposed estimator is performed via Schur complement along with Lyapunov analysis.Furthermore,for improving the 5-phase PMa-SynRM performance,five super-twisting sliding mode controllers(ST-SMCs)are employed with providing a robust response without the impacts of high chattering problem.A super-twisting sliding mode speed controller(ST-SMSC)is employed for controlling the PMa-SynRM rotor speed,and four super-twisting sliding mode current controllers(ST-SMCCs)are employed for controlling the 5-phase PMa-SynRM currents.The stability analysis and the experimental results indicate the effectiveness along with feasibility of the proposed RTSE and the ST-SMSC with ST-SMCCs approach for a 750-W 5-phase PMa-SynRM under load disturbance,parameters variations,single open-phase fault,and adjacent two-phase open circuit fault conditions.
基金supported by Scientific Instrument Developing Project of Chinese Academy of Sciences(Grant/Award YJKYYQ20200011)Chinese Academy of Sciences‘Light of West China’Program(Grant/Award xbzg-zdsys-202317).
文摘The effect of a metal shell on the launch efficiency of an asynchronous coil launcher(coil AC pulse linear motor)remains insufficiently understood in terms of the underlying mechanisms and principles.To address this gap,this study conducted extensive modelling simulations and calculations,varying the shell's conductivity,permeability,and dimensions.Through comparative analysis of these models,this paper identifies a unique‘tick-shaped efficiency curve’for the asynchronous coil launcher:the launch efficiency first decreases and then increases as the shell's electromagnetic parameters are enhanced.Enhancements that bolster the electromagnetic induction effect within the shell-such as increased conductivity,permeability and dimensions-are termed as the augmentation of electromagnetic parameters.This study delves into Lenz's law of electromagnetism to elucidate the observed phenomena,attributing them to the spatio-temporal force characteristics of the multipeak and multi-valley armature of the transmitting device,and the resulting‘tick-shaped efficiency curve’.A comprehensive summary of shell-related research in electromagnetic emission reveals that the driving current fundamentally dictates the shell's impact on launch efficiency.DC-driven launchers conform to the monotonic effect efficiency curve,whereas AC-driven launchers conform to the tick-shaped efficiency curve.
基金supported by the National Natural Science Foundation of China under Grant No.U2004183.
文摘High-voltage asynchronous motors(HVAMs)face the problem of excessive internal temperatures during operation,which not only compromises operational safety,but may also shorten their service life.Therefore,finding an optimally effective cooling system is crucial.The performance of a centrifugal fan within the inner airflow path of an HV AM plays a critical role in determining the overall ventilation and cooling capacity.Installing splitter blades is an effective method to improve the performance of centrifugal fans.This study investigates the specific effects of splitter blade design on the performance of centrifugal fans,the internal flow field,and the rise in temperature of the motor.The performance of an internal fan in a 630 kW,10 kV HVAM is analyzed using a combination of flow-thermal analysis and experiment.First,the effects of splitter blades with varying lengths and peripheral positions on the external characteristic parameters of the fan are investigated.A nonlinear relationship between the length and peripheral position of the splitter blades and the external characteristic parameters is identified,and the optimal configuration is determined.Second,the influence of splitter blades with different lengths and peripheral positions on the flow field of the inner loop is analyzed.The mechanisms through which splitter blades enhance the passage vortices are clarified.Finally,a comparison of the temperature fields between the optimal splitter blade configuration and the original centrifugal fan design demonstrates the effectiveness of the splitter blades in improving the ventilation and cooling capacity.The results of this study provide an optimized solution for the heat dissipation and cooling systems of HVAMs and can serve as a reference for the design of cooling systems for similar motors.
文摘The harmonics that appear in the squirrel cage asynchronous machine have been discussed in great detail in the literature for a long time. However, the systematization of the phenomenon is still pending, so we made an attempt to fill this gap in the previous parts of our study by elaborating formulas for calculation of parasitic torques. It was a general demand among those who work in this field towards the author to verify his formulas with measurements. In the literature, it seems,only one detailed, purposeful series of measurements has been published so far, the purpose of which was to investigate the effect of the number of rotor slots on the torque-speed characteristic curve of the machine. The main goal of this study is to verify the correctness of the formulas by comparing them with the referred series of measurements. Relying on this, the expected synchronous parasitic torques were developed for the frequently used rotor slot numbers-as a design guide for the engineer.Thus, together with our complete table for radial magnetic pull published in our previous work, the designer has all the principles, data and formulas available for the right number of rotor slots for his given machine and for the drive system. This brings this series of papers to an end.
