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Volume 51,Issue 4,2024 Table of Contents
2024, 51(4):1-11.
DOI: 10.12177/emca.2024.018
Abstract:
The stability of the intermediate DC-bus voltage of the two-stage photovoltaic inverter is crucial for its good power generating quality and long-term operation. The power generation of photovoltaic inverters is easily affected by environmental factors such as the strength of illumination and temperature, and this power fluctuation can cause significant disturbance on the DC-bus voltage. In order to improve the disturbance resistance of the DC-bus voltage and the control performance of the inverter, a photovoltaic inverter bus voltage control strategy based on improved first-order linear active disturbance rejection control (LADRC) is proposed. The voltage outer loop controller in the dual loop control of the inverter is designed by using improved first-order LADRC. On the basis of the traditional LADRC linear extended state observer, the system control component in the expression of the state variable is removed, so that the observation error equation of the state variable only contains error components related to the system input, which reduces the observation error of the state variable. A new state variable is added and the system control quantity of the previous control cycle is introduced, and total disturbance is re-estimated and compensated based on the total disturbance expression. The control performance of improved LADRC is analyzed in the frequency domain. Compared with the traditional LADRC, the improved LADRC has an increased system bandwidth, enhanced dynamic tracking ability, and smaller disturbance gain in the mid to low frequency range. Simulation and experiments show that the improved LADRC has a shorter regulating time, better system dynamic performance, and the disturbance resistance ability of DC-bus voltage is enhanced.
The stability of the intermediate DC-bus voltage of the two-stage photovoltaic inverter is crucial for its good power generating quality and long-term operation. The power generation of photovoltaic inverters is easily affected by environmental factors such as the strength of illumination and temperature, and this power fluctuation can cause significant disturbance on the DC-bus voltage. In order to improve the disturbance resistance of the DC-bus voltage and the control performance of the inverter, a photovoltaic inverter bus voltage control strategy based on improved first-order linear active disturbance rejection control (LADRC) is proposed. The voltage outer loop controller in the dual loop control of the inverter is designed by using improved first-order LADRC. On the basis of the traditional LADRC linear extended state observer, the system control component in the expression of the state variable is removed, so that the observation error equation of the state variable only contains error components related to the system input, which reduces the observation error of the state variable. A new state variable is added and the system control quantity of the previous control cycle is introduced, and total disturbance is re-estimated and compensated based on the total disturbance expression. The control performance of improved LADRC is analyzed in the frequency domain. Compared with the traditional LADRC, the improved LADRC has an increased system bandwidth, enhanced dynamic tracking ability, and smaller disturbance gain in the mid to low frequency range. Simulation and experiments show that the improved LADRC has a shorter regulating time, better system dynamic performance, and the disturbance resistance ability of DC-bus voltage is enhanced.
2024, 51(4):12-19.
DOI: 10.12177/emca.2024.007
Abstract:
Generally, discharging conditions of ramp-type gravity energy storage system (GESS) can be realized by transporting heavy blocks from the upper stacking yard to the lower one. However, the number of heavy blocks may not be adjusted timely when load demand fluctuates during discharging process, which may cause the delayed response and additional energy loss of GESS. By configuring auxiliary heavy blocks stacking yards on both sides of the ramp rail and dividing the traditional ramp into two segments, precise control on discharging power and fast response to load demand can be realized by controlling the releasing heavy blocks quantity on the top stacking yard, the releasing height of the ramp stacking yard and the grab position of heavy blocks on the ramp stacking yard. With Matlab/Simulink, the simulated model of two-stage ramp-type GESS is established, and the correctness and effectiveness of the presented method are verified. The achievement can provide an important reference for the discharging power adjustment and precise control of ramptype GESS.
Generally, discharging conditions of ramp-type gravity energy storage system (GESS) can be realized by transporting heavy blocks from the upper stacking yard to the lower one. However, the number of heavy blocks may not be adjusted timely when load demand fluctuates during discharging process, which may cause the delayed response and additional energy loss of GESS. By configuring auxiliary heavy blocks stacking yards on both sides of the ramp rail and dividing the traditional ramp into two segments, precise control on discharging power and fast response to load demand can be realized by controlling the releasing heavy blocks quantity on the top stacking yard, the releasing height of the ramp stacking yard and the grab position of heavy blocks on the ramp stacking yard. With Matlab/Simulink, the simulated model of two-stage ramp-type GESS is established, and the correctness and effectiveness of the presented method are verified. The achievement can provide an important reference for the discharging power adjustment and precise control of ramptype GESS.
2024, 51(4):20-28.
DOI: 10.12177/emca.2024.006
Abstract:
In the photovoltaic (PV) full DC collection and transmission system, a short circuit fault on the high voltage DC (HVDC) side will lead to a decrease in power absorption capacity of the high voltage side DC grid. PVs cannot detect the fault of the high voltage side DC grid in time, therefore its output power remains unchanged, which results in the system overvoltage and causes the system to shut down. To address this problem, a fault ride through strategy based on the active voltage rise is proposed. While the voltage of the high voltage side submodule of the high voltage DC transformer is risen to a certain level, the number of the medium voltage side submodules which output the high voltage level is increased to rise the voltage of the medium DC bus. And with the maximum power point tracking (MPPT) converters which have the function of fault state P-V droop, the MPPTs enter the power limiting mode in advance to achieve the power balance of the high voltage DC transformer, thus reduces the overvoltage of the submodule capacitor, and achieves the fault ride through function. The overvoltage of the HVDC transformer submodule under the proposed strategy is analyzed, and the effectiveness and necessity of the strategy are verified by simulation.
In the photovoltaic (PV) full DC collection and transmission system, a short circuit fault on the high voltage DC (HVDC) side will lead to a decrease in power absorption capacity of the high voltage side DC grid. PVs cannot detect the fault of the high voltage side DC grid in time, therefore its output power remains unchanged, which results in the system overvoltage and causes the system to shut down. To address this problem, a fault ride through strategy based on the active voltage rise is proposed. While the voltage of the high voltage side submodule of the high voltage DC transformer is risen to a certain level, the number of the medium voltage side submodules which output the high voltage level is increased to rise the voltage of the medium DC bus. And with the maximum power point tracking (MPPT) converters which have the function of fault state P-V droop, the MPPTs enter the power limiting mode in advance to achieve the power balance of the high voltage DC transformer, thus reduces the overvoltage of the submodule capacitor, and achieves the fault ride through function. The overvoltage of the HVDC transformer submodule under the proposed strategy is analyzed, and the effectiveness and necessity of the strategy are verified by simulation.
2024, 51(4):29-39.
DOI: 10.12177/emca.2024.011
Abstract:
The main methods to reduce the no-load eddy current loss of permanent magnets of axial magnetic field motors include: reducing the width of the stator slot opening, increasing the length of the air gap, dividing the permanent magnet into blocks, using shielding layers and magnetic slot wedges, etc. Based on a simplified 2D analysis model of a permanent magnet axial field motor, the effects of reducing stator slot opening width and increasing air gap length, using shielding layers and magnetic slot wedges to reduce no-load eddy current losses are analyzed. The effects of different segmentation methods of permanent magnets on reducing noload eddy current losses are studied through three-dimensional electromagnetic field simulation. The research results indicate that reducing the width of the stator slot opening has the best effect; although increasing the length of the air gap can significantly reduce eddy current losses, the amount of permanent magnets used increases rapidly; the segmented permanent magnet has a better effect on reducing eddy currents, and the circumferential segmentation method is the best; the shielding layer has a counterproductive effect; the effect of using segmented magnetic slot wedges is slightly worse than reducing the width of stator slot openings, but the processing technology difficulty is lower.
The main methods to reduce the no-load eddy current loss of permanent magnets of axial magnetic field motors include: reducing the width of the stator slot opening, increasing the length of the air gap, dividing the permanent magnet into blocks, using shielding layers and magnetic slot wedges, etc. Based on a simplified 2D analysis model of a permanent magnet axial field motor, the effects of reducing stator slot opening width and increasing air gap length, using shielding layers and magnetic slot wedges to reduce no-load eddy current losses are analyzed. The effects of different segmentation methods of permanent magnets on reducing noload eddy current losses are studied through three-dimensional electromagnetic field simulation. The research results indicate that reducing the width of the stator slot opening has the best effect; although increasing the length of the air gap can significantly reduce eddy current losses, the amount of permanent magnets used increases rapidly; the segmented permanent magnet has a better effect on reducing eddy currents, and the circumferential segmentation method is the best; the shielding layer has a counterproductive effect; the effect of using segmented magnetic slot wedges is slightly worse than reducing the width of stator slot openings, but the processing technology difficulty is lower.
2024, 51(4):40-49.
DOI: 10.12177/emca.2024.021
Abstract:
For the static eccentricity fault of the doubly salient electromagnetic generator, firstly, the equivalent analytical model of the air gap length of the generator is carried out. The theoretically relationships between the degree of static eccentricity and important characteristics such as magnetic flux linkage, electromagnetic torque, and air-gap magnetic density are derived. And then, a 2D finite element model of a 12/8 three-phase electrically excited salient-pole synchronous generator is established using Ansys finite element analysis, and the theoretical analysis results of electromagnetic signals are verified. Finally, the radial vibration signals of the generator are simulated through the coupled electromagnetic, modal, and harmonic response analysis modules in Workbench. The research findings show that the simulation results are basically consistent with the theoretical analysis, confirming that the eccentricity ratio in static eccentricity faults has a certain impact on the performance of the electrically excited salient-pole synchronous generator, thus providing a theoretical foundation for subsequent diagnoses of its static eccentricity faults.
For the static eccentricity fault of the doubly salient electromagnetic generator, firstly, the equivalent analytical model of the air gap length of the generator is carried out. The theoretically relationships between the degree of static eccentricity and important characteristics such as magnetic flux linkage, electromagnetic torque, and air-gap magnetic density are derived. And then, a 2D finite element model of a 12/8 three-phase electrically excited salient-pole synchronous generator is established using Ansys finite element analysis, and the theoretical analysis results of electromagnetic signals are verified. Finally, the radial vibration signals of the generator are simulated through the coupled electromagnetic, modal, and harmonic response analysis modules in Workbench. The research findings show that the simulation results are basically consistent with the theoretical analysis, confirming that the eccentricity ratio in static eccentricity faults has a certain impact on the performance of the electrically excited salient-pole synchronous generator, thus providing a theoretical foundation for subsequent diagnoses of its static eccentricity faults.
2024, 51(4):50-59.
DOI: 10.12177/emca.2024.019
Abstract:
Permanent magnet synchronous motors have been widely used in various fields due to their high power density, efficiency, and reliability. In applications that require mechanical angles, position sensors are generally used to obtain the mechanical position information of the motor rotor, which can reduce the reliability, integration, and power density of the control system. In order to achieve mechanical angle identification of permanent magnet motors without the use of position sensors, the electromagnetism of a surface-mounted permanent magnet synchronous motor (SPMSM) is designed. By adding auxiliary teeth of different heights to the rotor, the inductance of the motor topology includes the mechanical angle information of the rotor. The negative effects of adding auxiliary teeth on the back electromotive force, output torque, and three-phase inductance of the motor are analyzed using finite element simulation software. Finally, the mechanical angle identification ability of the proposed topology is verified on the 0.75 kW SPMSM platform.
Permanent magnet synchronous motors have been widely used in various fields due to their high power density, efficiency, and reliability. In applications that require mechanical angles, position sensors are generally used to obtain the mechanical position information of the motor rotor, which can reduce the reliability, integration, and power density of the control system. In order to achieve mechanical angle identification of permanent magnet motors without the use of position sensors, the electromagnetism of a surface-mounted permanent magnet synchronous motor (SPMSM) is designed. By adding auxiliary teeth of different heights to the rotor, the inductance of the motor topology includes the mechanical angle information of the rotor. The negative effects of adding auxiliary teeth on the back electromotive force, output torque, and three-phase inductance of the motor are analyzed using finite element simulation software. Finally, the mechanical angle identification ability of the proposed topology is verified on the 0.75 kW SPMSM platform.
2024, 51(4):60-69.
DOI: 10.12177/emca.2024.010
Abstract:
The DC bus voltage will fluctuate after the disturbance of the new energy output and load change of photovoltaics, energy storage, direct current and flexibility (PEDF), which poses a challenge to the stable operation of the DC air conditioning motor. The topology, advantages and disadvantages of DC air conditioning drive system and AC air conditioning drive system are analyzed, and the control strategy combining sliding-mode observer, maximum torque per ampere and leading angle flux weakening is researched, which can quickly adjust the control parameters of the motor by identifying the fluctuation of DC bus voltage. The simulation model of airconditioning motor using the above control strategy is built in Matlab/Simulink software, and the simulation verification is carried out according to the actual operation conditions of the air-conditioning. The results show that the control strategy can realize the stable operation of the air-conditioning motor in the full speed range under the DC bus voltage fluctuation.
The DC bus voltage will fluctuate after the disturbance of the new energy output and load change of photovoltaics, energy storage, direct current and flexibility (PEDF), which poses a challenge to the stable operation of the DC air conditioning motor. The topology, advantages and disadvantages of DC air conditioning drive system and AC air conditioning drive system are analyzed, and the control strategy combining sliding-mode observer, maximum torque per ampere and leading angle flux weakening is researched, which can quickly adjust the control parameters of the motor by identifying the fluctuation of DC bus voltage. The simulation model of airconditioning motor using the above control strategy is built in Matlab/Simulink software, and the simulation verification is carried out according to the actual operation conditions of the air-conditioning. The results show that the control strategy can realize the stable operation of the air-conditioning motor in the full speed range under the DC bus voltage fluctuation.
2024, 51(4):70-81.
DOI: 10.12177/emca.2024.017
Abstract:
In order to improve the anti-interference ability of permanent magnet synchronous motor speed control system, a robust H∞ control method is proposed. Firstly, according to the principle of robust H∞ control, the design method of permanent magnet synchronous motor speed control is proposed, and the solution method is introduced. The tracking performance, disturbance suppression, output limitation and model uncertainty are considered when designing the weighting function. The influence of the performance weighting function on the dynamic performance is illustrated in detail by means of the Bode diagram, and the design method of the weighting function is given. Then, in order to further improve the disturbance rejection of the system by considering the parameter uncertainty and unmodeled dynamics, the disturbance is observed as a feedforward compensation through the Luenberger observer and feed back into the speed controller to accelerate the dynamic response and enhance the disturbance rejection. Finally, the traditional proportional-integral controller, H∞ speed controller, and the proposed composite speed controller are compared by experiments, and the effectiveness of the proposed speed controller are verified by the experimental results.
In order to improve the anti-interference ability of permanent magnet synchronous motor speed control system, a robust H∞ control method is proposed. Firstly, according to the principle of robust H∞ control, the design method of permanent magnet synchronous motor speed control is proposed, and the solution method is introduced. The tracking performance, disturbance suppression, output limitation and model uncertainty are considered when designing the weighting function. The influence of the performance weighting function on the dynamic performance is illustrated in detail by means of the Bode diagram, and the design method of the weighting function is given. Then, in order to further improve the disturbance rejection of the system by considering the parameter uncertainty and unmodeled dynamics, the disturbance is observed as a feedforward compensation through the Luenberger observer and feed back into the speed controller to accelerate the dynamic response and enhance the disturbance rejection. Finally, the traditional proportional-integral controller, H∞ speed controller, and the proposed composite speed controller are compared by experiments, and the effectiveness of the proposed speed controller are verified by the experimental results.
2024, 51(4):82-89.
DOI: 10.12177/emca.2024.022
Abstract:
Submersible induction motors are currently more widely used in the deep well pump market, but they are generally large and inefficient, resulting in serious pump energy consumption. Permanent magnet synchronous motors have the advantages of high efficiency, high power factor and high power density. Therefore, the use of permanent magnet synchronous motors instead of induction motors as the drive equipment for deep well pumps can not only improve the performance of the motor, but also save energy to reduce electricity costs, in response to the national “carbon emission reduction” call. In order to meet the requirements of the latest national standards for motor energy-efficiency rating, according to the special requirements of deep-well pumps for their supporting motors, a 22 kW water-filled submersible induction motors on the market, a same of water-filled permanent magnet synchronous submersible motors is designed. The finite element analysis calculation is used to compare and analyze the performance parameters and the data of various loss and induction motors under rated working conditions, and the temperature field simulation of the designed permanent magnet synchronous motor is carried out to verify its rationality. The production cost and energy consumption of the two motors are evaluated for economic benefits. And it can be seen that the designed permanent magnet synchronous submersible motor can complete the cost recovery of the motor within a certain period of time, which is cost-effective and superior. And at the same time, it provides a reference for designing and analyzing motors for similar deep-well pumps.
Submersible induction motors are currently more widely used in the deep well pump market, but they are generally large and inefficient, resulting in serious pump energy consumption. Permanent magnet synchronous motors have the advantages of high efficiency, high power factor and high power density. Therefore, the use of permanent magnet synchronous motors instead of induction motors as the drive equipment for deep well pumps can not only improve the performance of the motor, but also save energy to reduce electricity costs, in response to the national “carbon emission reduction” call. In order to meet the requirements of the latest national standards for motor energy-efficiency rating, according to the special requirements of deep-well pumps for their supporting motors, a 22 kW water-filled submersible induction motors on the market, a same of water-filled permanent magnet synchronous submersible motors is designed. The finite element analysis calculation is used to compare and analyze the performance parameters and the data of various loss and induction motors under rated working conditions, and the temperature field simulation of the designed permanent magnet synchronous motor is carried out to verify its rationality. The production cost and energy consumption of the two motors are evaluated for economic benefits. And it can be seen that the designed permanent magnet synchronous submersible motor can complete the cost recovery of the motor within a certain period of time, which is cost-effective and superior. And at the same time, it provides a reference for designing and analyzing motors for similar deep-well pumps.
2024, 51(4):90-101.
DOI: 10.12177/emca.2024.015
Abstract:
Aiming at the problem of low computational accuracy when analyzing the electromagnetic field and temperature field of canned permanent magnet synchronous motor by the directional coupling method, a magneto-thermal bidirectional coupling method is proposed. Firstly, a magneto-thermal coupling computational model is established. Secondly, the influence of the can sleeve material on the motor performance is analyzed by the magneto-thermal bi-directional coupling method, and the calculation results are compared with the directional coupling method. Finally, a three-dimensional model of the motor is established and the electromagnetic field and three-dimensional temperature field are analyzed using finite element software. The results show that the proposed magneto-thermal bi-directional coupling calculation method can effectively improve the calculation accuracy of electromagnetic field and temperature field. In addition, the can sleeve using non-conductive non-magnetic materials can effectively improve the efficiency of the canned permanent magnet synchronous motor and reduce the temperature rise of the motor. The proposed method not only provides a reference for the design of canned permanent magnet synchronous motor, but also is of great significance to ensure the efficient and reliable operation of the motor.
Aiming at the problem of low computational accuracy when analyzing the electromagnetic field and temperature field of canned permanent magnet synchronous motor by the directional coupling method, a magneto-thermal bidirectional coupling method is proposed. Firstly, a magneto-thermal coupling computational model is established. Secondly, the influence of the can sleeve material on the motor performance is analyzed by the magneto-thermal bi-directional coupling method, and the calculation results are compared with the directional coupling method. Finally, a three-dimensional model of the motor is established and the electromagnetic field and three-dimensional temperature field are analyzed using finite element software. The results show that the proposed magneto-thermal bi-directional coupling calculation method can effectively improve the calculation accuracy of electromagnetic field and temperature field. In addition, the can sleeve using non-conductive non-magnetic materials can effectively improve the efficiency of the canned permanent magnet synchronous motor and reduce the temperature rise of the motor. The proposed method not only provides a reference for the design of canned permanent magnet synchronous motor, but also is of great significance to ensure the efficient and reliable operation of the motor.
2024, 51(4):102-109.
DOI: 10.12177/emca.2024.009
Abstract:
For the sake of resolving the problem of large torque ripple problem of switched reluctance motor, especially under hysteresis control strategy, back propagation (BP) neural network control strategy is introduced on the account of traditional direct instantaneous torque control, and the direct instantaneous torque control is optimized and adjusted with the square of the torque error as the performance index function, which restrains the torque ripple of the motor during operation. In addition, based on the overall double closed-loop control, sliding mode control is introduced for the improvement of the speed link, which improves the response speed and robustness of the system. Finally, Matlab/Simulink is used for simulating the traditional direct instantaneous torque control and optimized direct instantaneous torque control, the effectiveness and feasibility of the proposed strategy are proved.
For the sake of resolving the problem of large torque ripple problem of switched reluctance motor, especially under hysteresis control strategy, back propagation (BP) neural network control strategy is introduced on the account of traditional direct instantaneous torque control, and the direct instantaneous torque control is optimized and adjusted with the square of the torque error as the performance index function, which restrains the torque ripple of the motor during operation. In addition, based on the overall double closed-loop control, sliding mode control is introduced for the improvement of the speed link, which improves the response speed and robustness of the system. Finally, Matlab/Simulink is used for simulating the traditional direct instantaneous torque control and optimized direct instantaneous torque control, the effectiveness and feasibility of the proposed strategy are proved.
2024, 51(4):110-118.
DOI: 10.12177/emca.2024.013
Abstract:
The electrically excited flux switching linear magnetic suspension motor (EEFSLMSM) for rail transit traction systems is taken as the object of study. Firstly, the structure of EEFSLMSM is analyzed, its operating mechanism and the principle of electromagnetic thrust and levitation force generation are studied. Secondly, the mathematical model of EEFSLMSM is established, and the voltage and magnetic chain equations as well as the mathematical expressions of electromagnetic thrust and suspension force of the motor are derived. Then, the magnetic field distribution and no-load back electromotive force waveform of EEFSLMSM are analyzed by Ansys Maxwell, and the magnetic modulation ability of the motor is studied. Finally, the connection between electromagnetic thrust, levitation force and armature current as well as excitation current is obtained through Ansys finite element calculation and analysis. The results verify the feasibility of EEFSLMSM operation and provide a theoretical reference for the design of traction and suspension integration.
The electrically excited flux switching linear magnetic suspension motor (EEFSLMSM) for rail transit traction systems is taken as the object of study. Firstly, the structure of EEFSLMSM is analyzed, its operating mechanism and the principle of electromagnetic thrust and levitation force generation are studied. Secondly, the mathematical model of EEFSLMSM is established, and the voltage and magnetic chain equations as well as the mathematical expressions of electromagnetic thrust and suspension force of the motor are derived. Then, the magnetic field distribution and no-load back electromotive force waveform of EEFSLMSM are analyzed by Ansys Maxwell, and the magnetic modulation ability of the motor is studied. Finally, the connection between electromagnetic thrust, levitation force and armature current as well as excitation current is obtained through Ansys finite element calculation and analysis. The results verify the feasibility of EEFSLMSM operation and provide a theoretical reference for the design of traction and suspension integration.
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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.
