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Volume 50,Issue 8,2023 Table of Contents
2023, 50(8):1-8.
DOI: 10.12177/emca.2023.082
Abstract:
The high frequency injection sensorless control algorithm of permanent magnet synchronous motor（PMSM）is prone to lag when estimating motor angle, which affects the accuracy of speed control. To solve this problem, a sensorless control strategy of PMSM based on linear active disturbance rejection control is proposed. The speed closed-loop of PMSM is optimized by using simplified linear active disturbance rejection control algorithm. Simultaneously, a sensorless angle observation algorithm using high frequency sinusoidal voltage injection is used to obtain the angle and velocity information of the motor rotor. Finally, through simulation analysis and physical experiments, it was verified that the control strategy can effectively improve the estimation accuracy of motor angle and speed of PMSM, improve the control effect of the system, and have good prospect of engineering application.
The high frequency injection sensorless control algorithm of permanent magnet synchronous motor（PMSM）is prone to lag when estimating motor angle, which affects the accuracy of speed control. To solve this problem, a sensorless control strategy of PMSM based on linear active disturbance rejection control is proposed. The speed closed-loop of PMSM is optimized by using simplified linear active disturbance rejection control algorithm. Simultaneously, a sensorless angle observation algorithm using high frequency sinusoidal voltage injection is used to obtain the angle and velocity information of the motor rotor. Finally, through simulation analysis and physical experiments, it was verified that the control strategy can effectively improve the estimation accuracy of motor angle and speed of PMSM, improve the control effect of the system, and have good prospect of engineering application.
2023, 50(8):9-17.
DOI: 10.12177/emca.2023.094
Abstract:
GaN devices have faster switching speeds that reduce noise and significantly reduce servo-driver size, but electromagnetic interference (EMI) issues are more pronounced. The random carrier frequency modulation strategy (RCFPWM) can effectively suppress EMI, but the torque ripple is more severe after the carrier frequency is randomized. Therefore, a hybrid carrier frequency modulation strategy based on Markov chain (Markov-HCFPWM) is proposed. This strategy uses mixed carrier frequency modulation to reduce carrier frequency difference between adjacent switching cycles, and uses Markov chain to make local average carrier frequency close to the expected value. The simulation and test results show that compared with RCFPWM strategy, the proposed strategy can reduce torque ripple on the premise of effectively suppressing EMI.
GaN devices have faster switching speeds that reduce noise and significantly reduce servo-driver size, but electromagnetic interference (EMI) issues are more pronounced. The random carrier frequency modulation strategy (RCFPWM) can effectively suppress EMI, but the torque ripple is more severe after the carrier frequency is randomized. Therefore, a hybrid carrier frequency modulation strategy based on Markov chain (Markov-HCFPWM) is proposed. This strategy uses mixed carrier frequency modulation to reduce carrier frequency difference between adjacent switching cycles, and uses Markov chain to make local average carrier frequency close to the expected value. The simulation and test results show that compared with RCFPWM strategy, the proposed strategy can reduce torque ripple on the premise of effectively suppressing EMI.
3 On-Line Correction for Temperature Rise of Foil Winding in Transformer Based on Harmonic Resistance
2023, 50(8):18-25.
DOI: 10.12177/emca.2023.086
Abstract:
Hot-spot temperature of winding is an important indicator for on-line monitoring of distribution transformers. However, the existing on-line calculation methods for winding temperature rise do not consider the influence of foil winding structure. The structure of foil winding is identified by equivalent resistance ratio of distribution transformer under different harmonics, and comparing the heating difference between the wire winding structure and the foil winding structure, an algorithm for calculating the winding temperature rise through changes in winding resistance was online corrected. This method provides a new idea for predicting the hot-spot temperature of foil winding through the ratio of harmonic resistance.
Hot-spot temperature of winding is an important indicator for on-line monitoring of distribution transformers. However, the existing on-line calculation methods for winding temperature rise do not consider the influence of foil winding structure. The structure of foil winding is identified by equivalent resistance ratio of distribution transformer under different harmonics, and comparing the heating difference between the wire winding structure and the foil winding structure, an algorithm for calculating the winding temperature rise through changes in winding resistance was online corrected. This method provides a new idea for predicting the hot-spot temperature of foil winding through the ratio of harmonic resistance.
2023, 50(8):26-31.
DOI: 10.12177/emca.2023.085
Abstract:
Aiming at the difficulty in designing weight coefficients, and the problems of large steady-state torque and flux ripple in permanent magnet synchronous motor (PMSM) model predictive torque control (MPTC) systems, a weightless model predictive torque control method based on duty cycle optimization is proposed. Firstly, a PMSM weightless MPTC is established, and interaction errors are calculated based on the defined evaluation term within each control cycle. The voltage vector corresponding to the minimum interaction error is the optimal vector, thus eliminating the weight coefficient design. Then, on the basis of the weightless MPTC, a duty cycle optimization link is introduced. The proposed duty cycle calculation method used comprehensively considers the factors of flux and torque, which can effectively suppress torque and flux ripple. The simulation results show that the performance of the proposed weightless model predictive torque control system based on duty cycle optimization is good.
Aiming at the difficulty in designing weight coefficients, and the problems of large steady-state torque and flux ripple in permanent magnet synchronous motor (PMSM) model predictive torque control (MPTC) systems, a weightless model predictive torque control method based on duty cycle optimization is proposed. Firstly, a PMSM weightless MPTC is established, and interaction errors are calculated based on the defined evaluation term within each control cycle. The voltage vector corresponding to the minimum interaction error is the optimal vector, thus eliminating the weight coefficient design. Then, on the basis of the weightless MPTC, a duty cycle optimization link is introduced. The proposed duty cycle calculation method used comprehensively considers the factors of flux and torque, which can effectively suppress torque and flux ripple. The simulation results show that the performance of the proposed weightless model predictive torque control system based on duty cycle optimization is good.
2023, 50(8):32-37.
DOI: 10.12177/emca.2023.095
Abstract:
A single-phase cascaded H-bridge rectifier (CHBR) in the front end of the traction drive system of a transformer without power frequency is studied, and its mathematical model is constructed. On the basis of the voltage and current double closed-loop control strategy, the non phase-locked loop technology is introduced to improve the transient current control strategy. The grid-side current can quickly and accurately track the voltage phase frequency when the system is disturbed. Furthermore, the traditional additional balanced voltage control strategy has been improved, and the fuzzy control technology is added to solve the problems of unbalanced voltage and large voltage difference between all levels of capacitors on the DC side of CHBR when it is not ideal power grid or load is switched over a wide range. Finally, MATLAB/Simulink is used for simulation to verify the fast response and anti-interference ability of the proposed strategy during CHBR operation.
A single-phase cascaded H-bridge rectifier (CHBR) in the front end of the traction drive system of a transformer without power frequency is studied, and its mathematical model is constructed. On the basis of the voltage and current double closed-loop control strategy, the non phase-locked loop technology is introduced to improve the transient current control strategy. The grid-side current can quickly and accurately track the voltage phase frequency when the system is disturbed. Furthermore, the traditional additional balanced voltage control strategy has been improved, and the fuzzy control technology is added to solve the problems of unbalanced voltage and large voltage difference between all levels of capacitors on the DC side of CHBR when it is not ideal power grid or load is switched over a wide range. Finally, MATLAB/Simulink is used for simulation to verify the fast response and anti-interference ability of the proposed strategy during CHBR operation.
2023, 50(8):38-45.
DOI: 10.12177/emca.2023.087
Abstract:
Influenced by indistinguishable data samples and poor data balance, transformer state identification models using vibro-acoustic signals often have low accuracy. To address this problem, Focal loss is introduced to dynamic feedback weights according to the accuracy of the sample training process, thus constituting a Focal-XGBoost optimization model. Firstly, a set of filters that fit the transformer spectrum are used to fully extract the effective information of the vibro-acoustic signal, and then XGBoost-PCA is used to reduce the dimensionality of the samples. Then, the Softmax objective function in the original model is optimized using Focal loss to form the Focal-XGBoost model. After inputting the above samples, the hyperparameters of Focal are optimized based on the accuracy wave action, and the transformer state recognition results are output. The experimental results of 10 kV and 110 kV transformers show that Focal-XGBoost can reduce the number of samples compared with traditional SVM and KNN models. Focal-XGBoost reduces the misspecification of difficult samples in XGBoost test samples by 44.7%, which results in higher model recognition accuracy. In addition, non-uniform extraction compresses the sample space by 50% on the basis of average accuracy loss below 0.5%, which further reduces the model training cost.
Influenced by indistinguishable data samples and poor data balance, transformer state identification models using vibro-acoustic signals often have low accuracy. To address this problem, Focal loss is introduced to dynamic feedback weights according to the accuracy of the sample training process, thus constituting a Focal-XGBoost optimization model. Firstly, a set of filters that fit the transformer spectrum are used to fully extract the effective information of the vibro-acoustic signal, and then XGBoost-PCA is used to reduce the dimensionality of the samples. Then, the Softmax objective function in the original model is optimized using Focal loss to form the Focal-XGBoost model. After inputting the above samples, the hyperparameters of Focal are optimized based on the accuracy wave action, and the transformer state recognition results are output. The experimental results of 10 kV and 110 kV transformers show that Focal-XGBoost can reduce the number of samples compared with traditional SVM and KNN models. Focal-XGBoost reduces the misspecification of difficult samples in XGBoost test samples by 44.7%, which results in higher model recognition accuracy. In addition, non-uniform extraction compresses the sample space by 50% on the basis of average accuracy loss below 0.5%, which further reduces the model training cost.
2023, 50(8):46-51.
DOI: 10.12177/emca.2023.089
Abstract:
The traditional linear motor position detection accuracy heavily relies on the accuracy of sensors such as gratings, magnetic grids, and capacitive grids, and the installation accuracy and cost of sensors are also high. Based on the magnetic field analysis method, the influence of different permanent magnet shapes on linear Hall is analyzed, and the relationship between the magnetic field electrical angle and position at different detection distances is obtained. On this basis, a bread shaped permanent magnet structure that can achieve precise position detection is proposed, and a linear motor position feedback experimental platform is built based on complex programmable logic devices (CPLD) to achieve high-precision position detection of linear motors. The experimental results show that the use of Hall sensor induction designed bread shaped magnetic steel for linear motor position detection has the advantages of small installation method impact and high system reliability. The speed fluctuation of the linear motor during testing is within 5%, and the repeatability accuracy is 1.54 μm.
The traditional linear motor position detection accuracy heavily relies on the accuracy of sensors such as gratings, magnetic grids, and capacitive grids, and the installation accuracy and cost of sensors are also high. Based on the magnetic field analysis method, the influence of different permanent magnet shapes on linear Hall is analyzed, and the relationship between the magnetic field electrical angle and position at different detection distances is obtained. On this basis, a bread shaped permanent magnet structure that can achieve precise position detection is proposed, and a linear motor position feedback experimental platform is built based on complex programmable logic devices (CPLD) to achieve high-precision position detection of linear motors. The experimental results show that the use of Hall sensor induction designed bread shaped magnetic steel for linear motor position detection has the advantages of small installation method impact and high system reliability. The speed fluctuation of the linear motor during testing is within 5%, and the repeatability accuracy is 1.54 μm.
2023, 50(8):52-59.
DOI: 10.12177/emca.2023.090
Abstract:
Most multi-level inverters generate different levels of voltage through the front stage structure, and the rear stage is connected to the H-bridge arm to change the polarity of the output voltage. Due to the high harmonic content and increased cost of H-bridge, a differential symmetric five-level inverter is proposed. The inverter topology structure is symmetrical, easy to control, and has low harmonics. It does not require additional bridge arms to change the polarity of the output voltage, and the topology itself can generate multiple levels while also changing the polarity of the output voltage. In addition, the inverter has only one mode of discharge for each capacitor in one operating cycle, so the charging time of the capacitor is greater than the discharge time, and there is sufficient energy to supply the load. The proposed inverter was simulated using MATLAB/Simulink and a prototype was built for experimental verification. The simulation and experimental results were consistent with theoretical analysis, proving the effectiveness of the proposed inverter.
Most multi-level inverters generate different levels of voltage through the front stage structure, and the rear stage is connected to the H-bridge arm to change the polarity of the output voltage. Due to the high harmonic content and increased cost of H-bridge, a differential symmetric five-level inverter is proposed. The inverter topology structure is symmetrical, easy to control, and has low harmonics. It does not require additional bridge arms to change the polarity of the output voltage, and the topology itself can generate multiple levels while also changing the polarity of the output voltage. In addition, the inverter has only one mode of discharge for each capacitor in one operating cycle, so the charging time of the capacitor is greater than the discharge time, and there is sufficient energy to supply the load. The proposed inverter was simulated using MATLAB/Simulink and a prototype was built for experimental verification. The simulation and experimental results were consistent with theoretical analysis, proving the effectiveness of the proposed inverter.
2023, 50(8):60-65.
DOI: 10.12177/emca.2023.083
Abstract:
The internal electromagnetic parameters of a surfacemounted permanent magnet vernier machine are complex and changeable, and MATLAB/Simulink cannot accurately reflect the actual electromagnetic performance of the machine under different operating conditions. The influence of cross coupling on the flux, inductance and torque of surface-mounted permanent magnet vernier machine is analyzed and calculated by applying the cross coupling theory to the model of flux, inductance and torque of surface-mounted permanent magnet vernier machine. The field-curcuit co-simulation model of a machine drive control system model was established based on ANSYS Maxwell, Simplorer and MATLAB/Simulink software. The driving performance of the machine is tested and compared with the simulation results of MATLAB/Simulink constant parameter simulation. The theoretical analysis and simulation results show that the calculation results of the co-simulation analysis method have higher accuracy because of the real-time change of the electromagnetic state inside the machine.
The internal electromagnetic parameters of a surfacemounted permanent magnet vernier machine are complex and changeable, and MATLAB/Simulink cannot accurately reflect the actual electromagnetic performance of the machine under different operating conditions. The influence of cross coupling on the flux, inductance and torque of surface-mounted permanent magnet vernier machine is analyzed and calculated by applying the cross coupling theory to the model of flux, inductance and torque of surface-mounted permanent magnet vernier machine. The field-curcuit co-simulation model of a machine drive control system model was established based on ANSYS Maxwell, Simplorer and MATLAB/Simulink software. The driving performance of the machine is tested and compared with the simulation results of MATLAB/Simulink constant parameter simulation. The theoretical analysis and simulation results show that the calculation results of the co-simulation analysis method have higher accuracy because of the real-time change of the electromagnetic state inside the machine.
2023, 50(8):66-72.
DOI: 10.12177/emca.2023.093
Abstract:
In order to design a V-shaped built-in permanent magnet synchronous motor with good starting performance and more stable operation, the no-load back electromotive force （EMF）, air gap magnetic density, cogging torque and torque ripple are optimized by improving the structure of air magnetic isolation tank. Taking the geometric parameters of the air magnetic isolation tank as the variables to be optimized, the Latin hypercube sampling algorithm is used for multi-objective optimization to obtain the optimal parameter combination. After optimization, cogging torque decreased by 45%, torque ripple decreased by 4.4%, and electromagnetic torque increased by 5.2%. The optimization result is ideal, verifying the rationality of the optimization scheme for the permanent magnet synchronous motor.
In order to design a V-shaped built-in permanent magnet synchronous motor with good starting performance and more stable operation, the no-load back electromotive force （EMF）, air gap magnetic density, cogging torque and torque ripple are optimized by improving the structure of air magnetic isolation tank. Taking the geometric parameters of the air magnetic isolation tank as the variables to be optimized, the Latin hypercube sampling algorithm is used for multi-objective optimization to obtain the optimal parameter combination. After optimization, cogging torque decreased by 45%, torque ripple decreased by 4.4%, and electromagnetic torque increased by 5.2%. The optimization result is ideal, verifying the rationality of the optimization scheme for the permanent magnet synchronous motor.
2023, 50(8):73-83.
DOI: 10.12177/emca.2023.091
Abstract:
When the grid voltage drops, the stator and rotor of the wind turbine generate impulse voltage and impulse current, which will affect the security of the grid. In order to realize the low voltage ride-through of the brushless doubly-fed wind turbine and ensure the uninterrupted operation of the wind turbine under the grid voltage drop, transient analysis of the stator voltage and current of the brushless doubly-fed generator under the grid voltage drop is conducted. A mathematical model of brushless doubly-fed generator in the static coordinate system of power winding is built, then the dynamic change process of its power winding flux linkage and control winding voltage at the moment of grid voltage drop is deduced and analyzed, moreover a control strategy combining integral sliding mode direct power control and fault ride through control is proposed, hence the low-voltage ride through control of brushless doubly-fed generator is completed. The control strategy combined with the fault ride-through control completes the low voltage ride-through control of the brushless doubly-fed generator. Through MATLAB/Simulink and the semi-physical simulation experiment platform, the simulation and experimental results prove the correctness of the deduced power winding flux and control winding voltage dynamic change process and the effectiveness of the control strategy. The control strategy effectively inhibits the voltage and current distortion of the stator control winding side and improves the low voltage crossing performance of the brushless doubly-fed generator.
When the grid voltage drops, the stator and rotor of the wind turbine generate impulse voltage and impulse current, which will affect the security of the grid. In order to realize the low voltage ride-through of the brushless doubly-fed wind turbine and ensure the uninterrupted operation of the wind turbine under the grid voltage drop, transient analysis of the stator voltage and current of the brushless doubly-fed generator under the grid voltage drop is conducted. A mathematical model of brushless doubly-fed generator in the static coordinate system of power winding is built, then the dynamic change process of its power winding flux linkage and control winding voltage at the moment of grid voltage drop is deduced and analyzed, moreover a control strategy combining integral sliding mode direct power control and fault ride through control is proposed, hence the low-voltage ride through control of brushless doubly-fed generator is completed. The control strategy combined with the fault ride-through control completes the low voltage ride-through control of the brushless doubly-fed generator. Through MATLAB/Simulink and the semi-physical simulation experiment platform, the simulation and experimental results prove the correctness of the deduced power winding flux and control winding voltage dynamic change process and the effectiveness of the control strategy. The control strategy effectively inhibits the voltage and current distortion of the stator control winding side and improves the low voltage crossing performance of the brushless doubly-fed generator.
2023, 50(8):84-90.
DOI: 10.12177/emca.2023.021
Abstract:
In order to diagnose transformer winding looseness fault more accurately and effectively, a fault diagnosis method for transformer winding looseness based on variational mode decomposition (VMD) and support vector machine optimized by whale optimization algorithm (WOA-SVM) is proposed. Firstly, a fault simulation experiment is carried out on a 10 kV transformer to measure its vibration signal. Then, VMD is used to decompose the non-stationary vibration signal into multiple intrinsic mode functions (IMF), and the energy entropy of each IMF is calculated to constitute feature vectors. Finally, the feature vectors are input into the WOA-SVM to train the classification model, and the fault diagnosis of transformer winding looseness is realized. The results show that the proposed method is applicable to the fault diagnosis of transformer winding looseness, and its fault identification accuracy is higher than the traditional improved SVM classification model.
In order to diagnose transformer winding looseness fault more accurately and effectively, a fault diagnosis method for transformer winding looseness based on variational mode decomposition (VMD) and support vector machine optimized by whale optimization algorithm (WOA-SVM) is proposed. Firstly, a fault simulation experiment is carried out on a 10 kV transformer to measure its vibration signal. Then, VMD is used to decompose the non-stationary vibration signal into multiple intrinsic mode functions (IMF), and the energy entropy of each IMF is calculated to constitute feature vectors. Finally, the feature vectors are input into the WOA-SVM to train the classification model, and the fault diagnosis of transformer winding looseness is realized. The results show that the proposed method is applicable to the fault diagnosis of transformer winding looseness, and its fault identification accuracy is higher than the traditional improved SVM classification model.
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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.
