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
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
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
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
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
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
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.
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.
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.
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.
