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Volume 50,Issue 7,2023 Table of Contents
2023, 50(7):1-12.
DOI: 10.12177/emca.2023.081
Abstract:
The unified theory of electrical machinery should identify the inherent relationships of the electromechanical energy conversion process among different types of electrical machinery. Previously, the concepts of “Faraday reference frame” and “entrainment electromotive force” are proposed for rotational reference frames, which achieved a consistent expression of voltage equations under the winding-fixed coordinate system and the rotational coordinate system. On this basis, a four-coil unified model of electrical machinery is proposed. The electromechanical energy transformation process of the motor is uniformly characterized. Based on space vector mathematics, and its voltage and torque equation of four-coil prototype motor under space vector expressions are derived. Furthermore, the basic input and output characteristics of the unified model of electrical machinery is discussed, an equivalent physical characterization of typical electrical machinery is provided by setting additional constraint conditions through theoretical analysis. This work comes from teaching practice and is a helpful extension and supplement to the unified model of electrical machinery theory. This work also has a potential reference value for practical applications. The proposed vector control principle may potentially achieve a unified underlying algorithmic architecture for vector control of different types of electrical machineries.
The unified theory of electrical machinery should identify the inherent relationships of the electromechanical energy conversion process among different types of electrical machinery. Previously, the concepts of “Faraday reference frame” and “entrainment electromotive force” are proposed for rotational reference frames, which achieved a consistent expression of voltage equations under the winding-fixed coordinate system and the rotational coordinate system. On this basis, a four-coil unified model of electrical machinery is proposed. The electromechanical energy transformation process of the motor is uniformly characterized. Based on space vector mathematics, and its voltage and torque equation of four-coil prototype motor under space vector expressions are derived. Furthermore, the basic input and output characteristics of the unified model of electrical machinery is discussed, an equivalent physical characterization of typical electrical machinery is provided by setting additional constraint conditions through theoretical analysis. This work comes from teaching practice and is a helpful extension and supplement to the unified model of electrical machinery theory. This work also has a potential reference value for practical applications. The proposed vector control principle may potentially achieve a unified underlying algorithmic architecture for vector control of different types of electrical machineries.
2023, 50(7):13-20.
DOI: 10.12177/emca.2023.073
Abstract:
High-speed permanent magnet micromotor with slotless structure is widely used in testing equipment and medical equipment. However, the production process of slotless motor winding is complicated, and the production process of winding can be simplified by using winding printing technology. At present, existing printing technologies are mostly applied to motors with axial flux using rigid printed circuit board (PCB) as carrier. For high-speed motor with radial flux, rigid PCB can hardly meet the requirement for winding distribution along the circumference. Flexible PCB winding comes into being, but there is no complete design scheme of flexible PCB winding motor at present. Therefore, a high-speed micromotor with flexible PCB winding is designed. In order to solve the problem of unequal winding of flexible PCB winding, an average radius method is proposed and the motor is analyzed by simulation. The results show that the average radius method solve the problem of unequal winding of flexible PCB winding, and the desigred flexible PCB winding motor can meet the techaical requirements of the motor and has good thermal stability.
High-speed permanent magnet micromotor with slotless structure is widely used in testing equipment and medical equipment. However, the production process of slotless motor winding is complicated, and the production process of winding can be simplified by using winding printing technology. At present, existing printing technologies are mostly applied to motors with axial flux using rigid printed circuit board (PCB) as carrier. For high-speed motor with radial flux, rigid PCB can hardly meet the requirement for winding distribution along the circumference. Flexible PCB winding comes into being, but there is no complete design scheme of flexible PCB winding motor at present. Therefore, a high-speed micromotor with flexible PCB winding is designed. In order to solve the problem of unequal winding of flexible PCB winding, an average radius method is proposed and the motor is analyzed by simulation. The results show that the average radius method solve the problem of unequal winding of flexible PCB winding, and the desigred flexible PCB winding motor can meet the techaical requirements of the motor and has good thermal stability.
2023, 50(7):21-28.
DOI: 10.12177/emca.2023.078
Abstract:
The energy storage converter is the core carrier of the energy storage system to smooth the power fluctuations of renewable energy generation and to support the regulation of frequency and voltage. The key operation control technology of energy storage converter, especially the control strategy under current-control mode, is investigated. The tracking control strategy without static error of current inner loop is proposed. The design method of the PI control key parameters based on optimal damping ratio is proposed. Based on open-loop amplitude-phase frequency characteristic and open-loop logarithmic frequency characteristic method, the open-loop frequency domain model of the current inner loop of the energy storage converter is constructed. Through the Bode stability criterion, the influence of different current inner loop proportional coefficient, integral coefficient and converter resistance parameter change on the control stability of the energy storage converter is quantitatively analysed. At meanwhile, the Nyquist stability criterion is used to verify the results. The grid-connected test of the energy storage converter is carried out on the real time labratory (RT-LAB) platform. The grid-connected system remains stable under the different proportional coefficient and integral coefficient. Based on the transfer function of filter capacitor input voltage to output current, the problem of harmonic resonance is found. The active damping resonant suppression strategy based on capacitor current feedback is proposed, which can effectively eliminate the effect of harmonic resonance. The analysis results indicate that the proposed current-control type energy storage converter and its harmonic resonance suppression method is robustness for supporting development of renewable energy generation.
The energy storage converter is the core carrier of the energy storage system to smooth the power fluctuations of renewable energy generation and to support the regulation of frequency and voltage. The key operation control technology of energy storage converter, especially the control strategy under current-control mode, is investigated. The tracking control strategy without static error of current inner loop is proposed. The design method of the PI control key parameters based on optimal damping ratio is proposed. Based on open-loop amplitude-phase frequency characteristic and open-loop logarithmic frequency characteristic method, the open-loop frequency domain model of the current inner loop of the energy storage converter is constructed. Through the Bode stability criterion, the influence of different current inner loop proportional coefficient, integral coefficient and converter resistance parameter change on the control stability of the energy storage converter is quantitatively analysed. At meanwhile, the Nyquist stability criterion is used to verify the results. The grid-connected test of the energy storage converter is carried out on the real time labratory (RT-LAB) platform. The grid-connected system remains stable under the different proportional coefficient and integral coefficient. Based on the transfer function of filter capacitor input voltage to output current, the problem of harmonic resonance is found. The active damping resonant suppression strategy based on capacitor current feedback is proposed, which can effectively eliminate the effect of harmonic resonance. The analysis results indicate that the proposed current-control type energy storage converter and its harmonic resonance suppression method is robustness for supporting development of renewable energy generation.
2023, 50(7):29-34.
DOI: 10.12177/emca.2023.075
Abstract:
The traditional model predictive control (MPC) of dual three-phase permanent magnet synchronous motor (DTP-PMSM) only applies one voltage vector in one cycle control, resulting in poor control performance, especially the torque fluctuation in steady state. In order to solve this problem, a multi-vector model predictive torque control (MPTC) strategy based on virtual voltage vector (VVV) is proposed. The proposed strategy applies multiple voltage vectors in one cycle control, which can expand the vector modulation range. By this way, the torque ripple can be suppressed and the steady-state performance have been improved. In addition, VVV are adopted in the strategy so as to suppress the harmonic current. The cost function with no weighting factor is selected to select the candidate vector combinations, which reduces the complexity of the algorithm. Finally, the effectiveness of the proposed strategy is verified by comparing it with the traditional dual vector MPTC on the experimental platform.
The traditional model predictive control (MPC) of dual three-phase permanent magnet synchronous motor (DTP-PMSM) only applies one voltage vector in one cycle control, resulting in poor control performance, especially the torque fluctuation in steady state. In order to solve this problem, a multi-vector model predictive torque control (MPTC) strategy based on virtual voltage vector (VVV) is proposed. The proposed strategy applies multiple voltage vectors in one cycle control, which can expand the vector modulation range. By this way, the torque ripple can be suppressed and the steady-state performance have been improved. In addition, VVV are adopted in the strategy so as to suppress the harmonic current. The cost function with no weighting factor is selected to select the candidate vector combinations, which reduces the complexity of the algorithm. Finally, the effectiveness of the proposed strategy is verified by comparing it with the traditional dual vector MPTC on the experimental platform.
2023, 50(7):35-42.
DOI: 10.12177/emca.2023.071
Abstract:
Although the sensorless strategy has been widely used in general industrial occasions, it has not been applied in the field of position servo. The reason is that the rotor mechanical angle cannot be identified. Therefore, a sensorless identification strategy of surface permanent magnet synehromous motor (SPMSM) rotor mechanical angle with auxiliary teeth based on high-frequency voltage injection is proposed. According to the mathematical model of SPMSM with auxiliary teeth, the mechanical sector is divided by injecting high-frequency voltage signal at the electrical angle zero point. The traditional sensorless algorithm is used to obtain the electrical angle. Finally, the mechanical angle is obtained from the relationship among electrical angle, mechanical sector and mechanical angle. The simulation results show that the proposed algorithm can identify the mechanical angle of the motor rotor.
Although the sensorless strategy has been widely used in general industrial occasions, it has not been applied in the field of position servo. The reason is that the rotor mechanical angle cannot be identified. Therefore, a sensorless identification strategy of surface permanent magnet synehromous motor (SPMSM) rotor mechanical angle with auxiliary teeth based on high-frequency voltage injection is proposed. According to the mathematical model of SPMSM with auxiliary teeth, the mechanical sector is divided by injecting high-frequency voltage signal at the electrical angle zero point. The traditional sensorless algorithm is used to obtain the electrical angle. Finally, the mechanical angle is obtained from the relationship among electrical angle, mechanical sector and mechanical angle. The simulation results show that the proposed algorithm can identify the mechanical angle of the motor rotor.
2023, 50(7):43-50.
DOI: 10.12177/emca.2023.067
Abstract:
Bearingless switched reluctance motor (BSRM) has been widely used in industry due to its high fault tolerance, low loss and high efficiency, but the vibration during motor operation can affect its application in certain fields. Taking BSRM as the research object, a method of opening the window at the stator-rotor teeth is introduced. By changing the reluctance of stator or rotor core, the magnetic flux density in the air gap can be reduced, to achieve the purpose of reducing electromagnetic vibration. The position and size of windows are optimized by electromagnetic finite element method and orthogonal experimental method. Verify the impact of rotor window opening on radial force and torque of the external stator. Finally, the influence of rotor window opening on vibration response is verified by modal superposition method. The results show that the proposed method has a good suppression effect on the electromagnetic vibration of hybrid excitation double-stator BSRM , but has a certain influence on the torque of the motor.
Bearingless switched reluctance motor (BSRM) has been widely used in industry due to its high fault tolerance, low loss and high efficiency, but the vibration during motor operation can affect its application in certain fields. Taking BSRM as the research object, a method of opening the window at the stator-rotor teeth is introduced. By changing the reluctance of stator or rotor core, the magnetic flux density in the air gap can be reduced, to achieve the purpose of reducing electromagnetic vibration. The position and size of windows are optimized by electromagnetic finite element method and orthogonal experimental method. Verify the impact of rotor window opening on radial force and torque of the external stator. Finally, the influence of rotor window opening on vibration response is verified by modal superposition method. The results show that the proposed method has a good suppression effect on the electromagnetic vibration of hybrid excitation double-stator BSRM , but has a certain influence on the torque of the motor.
2023, 50(7):51-58.
DOI: 10.12177/emca.2023.079
Abstract:
The Rtunit rapid prototyping development system is used to quickly develop and control the induction motor current source excitation system. The modeling and simulation of the three-phase programmable current source system is completed in MATLAB/Simulink. The supporting components is used and converted into engineering code which can be downloaded to the hardware controller. The three-phase full-bridge inverter is controlled through the integrated development environment online detection and modification of corresponding parameters. The development of the three-phase current source excitation system is completed. The system can stably output three-phase current source excitation with real-time frequency modulation and amplitude modulation. The test results show that this method has the advantages of simple programming, short development cycle, low cost and high efficiency under the condition of meeting the requirements.
The Rtunit rapid prototyping development system is used to quickly develop and control the induction motor current source excitation system. The modeling and simulation of the three-phase programmable current source system is completed in MATLAB/Simulink. The supporting components is used and converted into engineering code which can be downloaded to the hardware controller. The three-phase full-bridge inverter is controlled through the integrated development environment online detection and modification of corresponding parameters. The development of the three-phase current source excitation system is completed. The system can stably output three-phase current source excitation with real-time frequency modulation and amplitude modulation. The test results show that this method has the advantages of simple programming, short development cycle, low cost and high efficiency under the condition of meeting the requirements.
2023, 50(7):59-65.
DOI: 10.12177/emca.2023.066
Abstract:
In order to solve the problem of voltage drop in the process of mode switching in permanent magnet starting/generating system, a mode switching strategy considering capacitor charging and discharging delay is proposed based on the traditional mode switching strategy. By considering the delay process of capacitor charging and discharging, the control structure and the switching time of electrical load switch are changed to reduce the drop voltage during the switching process. Set the generation mode speed threshold in the mode switching controller, so that it can smoothly switch to the starting mode when the generation mode cannot be maintained. This switching strategy improves the system stability. Through simulation experiment, the correctness and feasibility of the above switching strategy are verified.
In order to solve the problem of voltage drop in the process of mode switching in permanent magnet starting/generating system, a mode switching strategy considering capacitor charging and discharging delay is proposed based on the traditional mode switching strategy. By considering the delay process of capacitor charging and discharging, the control structure and the switching time of electrical load switch are changed to reduce the drop voltage during the switching process. Set the generation mode speed threshold in the mode switching controller, so that it can smoothly switch to the starting mode when the generation mode cannot be maintained. This switching strategy improves the system stability. Through simulation experiment, the correctness and feasibility of the above switching strategy are verified.
2023, 50(7):66-73.
DOI: 10.12177/emca.2023.074
Abstract:
Magnetic gear motor has the characteristics of high torque density and strong rotor structure. To solve the problem of high cogging torque of external rotor spoke magnetic gear motor, a three-phase 18-slot 28-pole external rotor spoke magnetic gear motor is taken as the research object. The air gap is calculated analytically using the magnetic field modulation theory, and then the mechanism of cogging torque of the external rotor spoke magnetic gear motor is analyzed based on Maxwell tensor method. The magnetic year structure is optimized by adjusting the groove angle and rotor cutting angle. The finite element analysis results show that the third harmonic of the oplimized motor′s back electromotive force is reduced by 53%, the amplitude of cogging torque is reduced by 93.4%, and the output torque ripple is reduced by 73.7%. The finite element analysis results verify the effectiveness of the structural optimization method by adjusting the groove angle and rotor cutting angle.
Magnetic gear motor has the characteristics of high torque density and strong rotor structure. To solve the problem of high cogging torque of external rotor spoke magnetic gear motor, a three-phase 18-slot 28-pole external rotor spoke magnetic gear motor is taken as the research object. The air gap is calculated analytically using the magnetic field modulation theory, and then the mechanism of cogging torque of the external rotor spoke magnetic gear motor is analyzed based on Maxwell tensor method. The magnetic year structure is optimized by adjusting the groove angle and rotor cutting angle. The finite element analysis results show that the third harmonic of the oplimized motor′s back electromotive force is reduced by 53%, the amplitude of cogging torque is reduced by 93.4%, and the output torque ripple is reduced by 73.7%. The finite element analysis results verify the effectiveness of the structural optimization method by adjusting the groove angle and rotor cutting angle.
2023, 50(7):74-80.
DOI: 10.12177/emca.2023.070
Abstract:
In the field of industrial servo control, notch filter is often used to suppress the mechanical resonance, and accurate acquisition of resonance frequency is the primary condition for the successful suppression of resonance. The second-order generalized integrator-frequency-locked loop (SOGI-FLL) is used to analyze the output signal of speed controller in order to detect the resonance frequency. Firstly, the basic structure of SOGI-FLL and the operating principle of frequency-locked loop are introduced, and then the frequency response performance of amplitude-frequency adaptive SOGI-FLL is analyzed. Finally, simulation and experiment show that the amplitude-frequency adaptive SOGI-FLL can measure the resonance frequency accurately and quickly. The measured frequency is used to set the parameters of notch filter, and the mechanical resonance is restrained successfully.
In the field of industrial servo control, notch filter is often used to suppress the mechanical resonance, and accurate acquisition of resonance frequency is the primary condition for the successful suppression of resonance. The second-order generalized integrator-frequency-locked loop (SOGI-FLL) is used to analyze the output signal of speed controller in order to detect the resonance frequency. Firstly, the basic structure of SOGI-FLL and the operating principle of frequency-locked loop are introduced, and then the frequency response performance of amplitude-frequency adaptive SOGI-FLL is analyzed. Finally, simulation and experiment show that the amplitude-frequency adaptive SOGI-FLL can measure the resonance frequency accurately and quickly. The measured frequency is used to set the parameters of notch filter, and the mechanical resonance is restrained successfully.
2023, 50(7):81-88.
DOI: 10.12177/emca.2023.069
Abstract:
The output of wind and solar power units is uncertain, which will affect the dispatching optimization of regional power grid. To solve this problem, a multi-source multi-objective scheduling optimization model including wind and solar power units is proposed. The objective function takes into account the economic operation cost and environmental treatment cost, and at the same time, the constraints such as reserve capacity and climbing ability increase. Considering the influence of weighting factors on the multi-objective optimization results, based on different load conditions, the multi-objective optimization weighting factors are dynamically selected, and the corresponding weighting factors under different load stages are obtained. The load is divided into three situations: base load, waist load and peak load. According to the fuzzy comprehensive evaluation method, the weighting factors of each middle load situation are dynamically determined, and four optimization schemes are proposed. In order to reduce the comprehensive cost, under the premise of considering various constraints, an improved particle swarm optimization algorithm was used to solve the model, obtains the comprehensive cost of four schemes in different periods, determines the scheduling optimization scheme. At the same time, the optimal strategy for unit output in the regional power grid during the operation period was obtained. Finally, the effectiveness of the proposed multi-objective scheduling optimization strategy based on dynamic weighting factors was verified by an example.
The output of wind and solar power units is uncertain, which will affect the dispatching optimization of regional power grid. To solve this problem, a multi-source multi-objective scheduling optimization model including wind and solar power units is proposed. The objective function takes into account the economic operation cost and environmental treatment cost, and at the same time, the constraints such as reserve capacity and climbing ability increase. Considering the influence of weighting factors on the multi-objective optimization results, based on different load conditions, the multi-objective optimization weighting factors are dynamically selected, and the corresponding weighting factors under different load stages are obtained. The load is divided into three situations: base load, waist load and peak load. According to the fuzzy comprehensive evaluation method, the weighting factors of each middle load situation are dynamically determined, and four optimization schemes are proposed. In order to reduce the comprehensive cost, under the premise of considering various constraints, an improved particle swarm optimization algorithm was used to solve the model, obtains the comprehensive cost of four schemes in different periods, determines the scheduling optimization scheme. At the same time, the optimal strategy for unit output in the regional power grid during the operation period was obtained. Finally, the effectiveness of the proposed multi-objective scheduling optimization strategy based on dynamic weighting factors was verified by an example.
2023, 50(7):89-94.
DOI: 10.12177/emca.2023.077
Abstract:
The adjustment speed of traditional energy storage control is relatively slow,making it difficult to meet the precise control after a high proportion of new energy is connected to the power grid. The error rate in the scheduling cycle is introduced into the optimal control strategy of the energy storage system, and the feedback error link is added before the current closed-loop control using the error rate to optimize the control of the DC/DC bidirectional controller of the energy storage battery. With the goal of minimizing the root-mean-square error between the active output and the planned active output of the photovoltaic(PV)-and-storage combined generation system,the mathematical model takes into account the limiting conditions of the state of charge of the energy storage battery and the allowable deviation of the combined power generation system. The transfer function of the BUCK/BOOST circuit in the bidirectional DC/DC converter is given.Then the PQ control strategy for the grid-connected operation of the PV-and-storage combined generation system is given, and the active power and reactive power decoupling control is adopted. Based on the MATLAB/simulink simulation platform,the simulation system of the PV-and-storage combined generation system is established. The effectiveness of the control strategy proposed in this paper is verified by the analysis of the simulation results.
The adjustment speed of traditional energy storage control is relatively slow,making it difficult to meet the precise control after a high proportion of new energy is connected to the power grid. The error rate in the scheduling cycle is introduced into the optimal control strategy of the energy storage system, and the feedback error link is added before the current closed-loop control using the error rate to optimize the control of the DC/DC bidirectional controller of the energy storage battery. With the goal of minimizing the root-mean-square error between the active output and the planned active output of the photovoltaic(PV)-and-storage combined generation system,the mathematical model takes into account the limiting conditions of the state of charge of the energy storage battery and the allowable deviation of the combined power generation system. The transfer function of the BUCK/BOOST circuit in the bidirectional DC/DC converter is given.Then the PQ control strategy for the grid-connected operation of the PV-and-storage combined generation system is given, and the active power and reactive power decoupling control is adopted. Based on the MATLAB/simulink simulation platform,the simulation system of the PV-and-storage combined generation system is established. The effectiveness of the control strategy proposed in this paper is verified by the analysis of the simulation results.
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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.
