Mobile website
Volume 47,Issue 9,2020 Table of Contents
2020, 47(9):1-7.
DOI: 10.12177/emca.2020.109
Abstract:
Switched reluctance motor (SRM) has the advantages of ruggedness, high power density, wide speed range, large starting torque and so on. However, there are few researches of power converter for SRM. On the basis of domestic and foreign literature, the asymmetric half-bridge power converter, common switching power converter, split-phase power converter, and three-switch power converter are analyzed. The advantages and disadvantages of these traditional converters are compared. After that, the topology of several new types of power converter and their current-voltage relationship are analyzed, and the future development trend of SRM power converters is summarized. This research will provide reference for the future development of power converters.
Switched reluctance motor (SRM) has the advantages of ruggedness, high power density, wide speed range, large starting torque and so on. However, there are few researches of power converter for SRM. On the basis of domestic and foreign literature, the asymmetric half-bridge power converter, common switching power converter, split-phase power converter, and three-switch power converter are analyzed. The advantages and disadvantages of these traditional converters are compared. After that, the topology of several new types of power converter and their current-voltage relationship are analyzed, and the future development trend of SRM power converters is summarized. This research will provide reference for the future development of power converters.
2020, 47(9):8-15.
DOI: 10.12177/emca.2020.110
Abstract:
Model predictive torque control (MPTC) selects the optimal voltage vector by traversing all candidate voltage vectors, which results in large calculation and poor real-time performance. In order to solve these problems, the data of MPTC are collected to train a convolutional neural network (CNN) and the CNN is then used to replace MPTC for the optimal voltage vector selection. In order to solve the out-of-control problem in using CNN, the MPTC based on direct torque control (DTC) and CNN is proposed. Voltage vectors selected by CNN and DTC are used as candidate voltage vectors of MPTC. Simulation results show that the proposed strategy can effectively solve the out-of-control problem of CNN, its control effect is basically equivalent to MPTC, while the torque and stator flux ripples of the proposed strategy are significantly lower than those of DTC.
Model predictive torque control (MPTC) selects the optimal voltage vector by traversing all candidate voltage vectors, which results in large calculation and poor real-time performance. In order to solve these problems, the data of MPTC are collected to train a convolutional neural network (CNN) and the CNN is then used to replace MPTC for the optimal voltage vector selection. In order to solve the out-of-control problem in using CNN, the MPTC based on direct torque control (DTC) and CNN is proposed. Voltage vectors selected by CNN and DTC are used as candidate voltage vectors of MPTC. Simulation results show that the proposed strategy can effectively solve the out-of-control problem of CNN, its control effect is basically equivalent to MPTC, while the torque and stator flux ripples of the proposed strategy are significantly lower than those of DTC.
2020, 47(9):16-21，65.
DOI: 10.12177/emca.2020.078
Abstract:
In order to solve the integral saturation problem in speed regulating system of switched reluctance motor (SRM), which leads to the poor control performance, a design method of variableproportiondesaturation PI regulator is proposed, and its related parameter setting method is given. By utilizing the MATLAB/Simulink tool, the PI regulator performance of the traditional method, the antisaturation method and the variableproportiondesaturation method are verified under the conditions of constant speed with noload and variable speed with load, respectively. The results indicate that the variableproportiondesaturation PI regulator has better dynamic performance and antidisturbance performance.
In order to solve the integral saturation problem in speed regulating system of switched reluctance motor (SRM), which leads to the poor control performance, a design method of variableproportiondesaturation PI regulator is proposed, and its related parameter setting method is given. By utilizing the MATLAB/Simulink tool, the PI regulator performance of the traditional method, the antisaturation method and the variableproportiondesaturation method are verified under the conditions of constant speed with noload and variable speed with load, respectively. The results indicate that the variableproportiondesaturation PI regulator has better dynamic performance and antidisturbance performance.
2020, 47(9):22-28.
DOI: 10.12177/emca.2020.097
Abstract:
In the traditional PI speed control of permanent magnet synchronous motor (PMSM), there exists speed overshoot, large impulse current and poor anti-load-disturbance ability of speed loop. To solve these problems, a new variable structure PI (VSPI) control method based on the electromagnetic torque is proposed by deducing the mathematical model of PMSM and analyzing the PI control theory. On the basis of traditional PI control and VSPI control, the problems of speed overshoot and anti-disturbance are well solved by closed-loop control strategies such as fusing differential feedforward control and introducing torque feedback closed-loop control strategies. A voltage-current hybrid observation model and the corresponding calculation method are proposed for electromagnetic torque. Meanwhile, the influence of open-loop gain variation on system stability is analyzed in detail. Finally, the feasibility and effectiveness of the proposed method are verified by simulation.
In the traditional PI speed control of permanent magnet synchronous motor (PMSM), there exists speed overshoot, large impulse current and poor anti-load-disturbance ability of speed loop. To solve these problems, a new variable structure PI (VSPI) control method based on the electromagnetic torque is proposed by deducing the mathematical model of PMSM and analyzing the PI control theory. On the basis of traditional PI control and VSPI control, the problems of speed overshoot and anti-disturbance are well solved by closed-loop control strategies such as fusing differential feedforward control and introducing torque feedback closed-loop control strategies. A voltage-current hybrid observation model and the corresponding calculation method are proposed for electromagnetic torque. Meanwhile, the influence of open-loop gain variation on system stability is analyzed in detail. Finally, the feasibility and effectiveness of the proposed method are verified by simulation.
2020, 47(9):29-33.
DOI: 10.12177/emca.2020.094
Abstract:
Permanent magnet linear synchronous motor (PMLSM) has attracted much attention because of its high speed and high dynamic response. The uncertain factors such as parameter change, end effect and friction force will reduce the control system performance of PMLSM. In order to improve the robustness of the system, a plug-in integral sliding mode control is proposed. The output of the original controller is added to the designed sliding surface in the sliding mode control, which makes the control system obtain strong robustness without changing the structure and performance of the original controller. At the same time, the continuous super-twisting control is used to replace the original discontinuous part in the integral sliding mode control, which weakens the inherent chattering in the sliding mode. The MATLAB/Simulink simulation results verify the effectiveness of the proposed method.
Permanent magnet linear synchronous motor (PMLSM) has attracted much attention because of its high speed and high dynamic response. The uncertain factors such as parameter change, end effect and friction force will reduce the control system performance of PMLSM. In order to improve the robustness of the system, a plug-in integral sliding mode control is proposed. The output of the original controller is added to the designed sliding surface in the sliding mode control, which makes the control system obtain strong robustness without changing the structure and performance of the original controller. At the same time, the continuous super-twisting control is used to replace the original discontinuous part in the integral sliding mode control, which weakens the inherent chattering in the sliding mode. The MATLAB/Simulink simulation results verify the effectiveness of the proposed method.
2020, 47(9):34-38，72.
DOI: 10.12177/emca.2020.091
Abstract:
Many problems of the sensorless control of the motor in zero- and low-speed range are solved effectively by the pulsed high-frequency voltage injection (PHFVI) utilizing the salient pole effect generated in the motor. However, there still exist poor stability and large estimation error in the PHFVI control strategy when permanent magnet synchronous motor (PMSM) runs in the range of zero and low speed. For these problems, a new method of PHFVI is proposed based on the traditional method. The d axis component and the q axis component in the estimation synchronous coordinate system are both considered in the new method when the current response signal is demodulated, and the phase-locked loop (PLL) technology is used in the process of obtaining the speed and rotor position. After the theory is analyzed and the mathematical model of PMSM is built, the design process of PLL is strictly deduced. Finally, the overall design is verified by the comprehensive simulation. The results show that with the novel PHFVI method, the PMSM system has better stability, less error in position estimation, and better robustness.
Many problems of the sensorless control of the motor in zero- and low-speed range are solved effectively by the pulsed high-frequency voltage injection (PHFVI) utilizing the salient pole effect generated in the motor. However, there still exist poor stability and large estimation error in the PHFVI control strategy when permanent magnet synchronous motor (PMSM) runs in the range of zero and low speed. For these problems, a new method of PHFVI is proposed based on the traditional method. The d axis component and the q axis component in the estimation synchronous coordinate system are both considered in the new method when the current response signal is demodulated, and the phase-locked loop (PLL) technology is used in the process of obtaining the speed and rotor position. After the theory is analyzed and the mathematical model of PMSM is built, the design process of PLL is strictly deduced. Finally, the overall design is verified by the comprehensive simulation. The results show that with the novel PHFVI method, the PMSM system has better stability, less error in position estimation, and better robustness.
2020, 47(9):39-43，50.
DOI: 10.12177/emca.2020.081
Abstract:
The traction power supply system of electric multiple unit (EMU) adopts 25 kV single-phase transformer to draw power from the traction catenary. The disconnection of pantograph-catenary during the locomotive running operation, nonlinear characteristics of power devices, and the asymmetry of hardware circuit and control system can all cause the DC components to inject into the vehicle traction transformer through the electrical circuit, and result in the DC magnetic bias of transformer. By applying the proportional-integral-resonance (PIR) control to the current inner loop controller, the stable track of the sinusoidal signal and the suppression of the DC components are realized. The simulation and the hardware-in-the-loop simulation results show the effectiveness of the control strategy.
The traction power supply system of electric multiple unit (EMU) adopts 25 kV single-phase transformer to draw power from the traction catenary. The disconnection of pantograph-catenary during the locomotive running operation, nonlinear characteristics of power devices, and the asymmetry of hardware circuit and control system can all cause the DC components to inject into the vehicle traction transformer through the electrical circuit, and result in the DC magnetic bias of transformer. By applying the proportional-integral-resonance (PIR) control to the current inner loop controller, the stable track of the sinusoidal signal and the suppression of the DC components are realized. The simulation and the hardware-in-the-loop simulation results show the effectiveness of the control strategy.
2020, 47(9):44-50.
DOI: 10.12177/emca.2020.104
Abstract:
The mode of motor is the basis of vibration analysis, which is determined by natural frequency, mode shape and damping ratio. When the excitation frequency of the motor is the same as or similar to the natural frequency of a certain order, resonance will occur, and the motor will vibrate violently, which will affect its normal operation. After the 3D modeling of dualchannel permanent magnet synchronous motor (PMSM) applied in aero electric reverse system, the 3D model is sent to the ANSYS Workbench, and the motor modal analysis, response spectrum analysis and impact response simulation are carried out on the ANSYS platform. The first six order natural frequencies and vibration modes of the motor, the equivalent stress of the motor under the external response spectrum and the stress distribution on the mechanical structure of the motor under the transient impact are given.
The mode of motor is the basis of vibration analysis, which is determined by natural frequency, mode shape and damping ratio. When the excitation frequency of the motor is the same as or similar to the natural frequency of a certain order, resonance will occur, and the motor will vibrate violently, which will affect its normal operation. After the 3D modeling of dualchannel permanent magnet synchronous motor (PMSM) applied in aero electric reverse system, the 3D model is sent to the ANSYS Workbench, and the motor modal analysis, response spectrum analysis and impact response simulation are carried out on the ANSYS platform. The first six order natural frequencies and vibration modes of the motor, the equivalent stress of the motor under the external response spectrum and the stress distribution on the mechanical structure of the motor under the transient impact are given.
2020, 47(9):51-55，96.
DOI: 10.12177/emca.2020.096
Abstract:
The increasing speed grade of electric multiple unit (EMU) requires more power, lighter weight and higher efficiency of traction motor. The parameters selection and structure design of permanent magnet traction motor of highspeed EMU are studied, and the simulation analysis and calculation are carried out. In the existing installation space, a permanent magnet traction motor with higher speed and higher power density is designed to meet the operation requirements of high-speed EMU.
The increasing speed grade of electric multiple unit (EMU) requires more power, lighter weight and higher efficiency of traction motor. The parameters selection and structure design of permanent magnet traction motor of highspeed EMU are studied, and the simulation analysis and calculation are carried out. In the existing installation space, a permanent magnet traction motor with higher speed and higher power density is designed to meet the operation requirements of high-speed EMU.
2020, 47(9):56-60.
DOI: 10.12177/emca.2020.093
Abstract:
Based on the design requirement of 160 kW permanent magnet direct drive synchronous traction motor for metro vehicle, the design difficulties of 160 kW direct drive synchronous traction motor are analyzed. In view of the design difficulties of permanent magnet direct drive motor, the topology structure of the V-shaped permanent magnet rotor of the motor is studied, and is optimized based on Maxwell. Through comparative analysis of motor′s no-load performance and load performance of different V-shaped magnet steel rotor topology structures, the suitables rotor topology structure for the design of the motor is obtained. A prototype is developed and the test results verify the feasibility of the design.
Based on the design requirement of 160 kW permanent magnet direct drive synchronous traction motor for metro vehicle, the design difficulties of 160 kW direct drive synchronous traction motor are analyzed. In view of the design difficulties of permanent magnet direct drive motor, the topology structure of the V-shaped permanent magnet rotor of the motor is studied, and is optimized based on Maxwell. Through comparative analysis of motor′s no-load performance and load performance of different V-shaped magnet steel rotor topology structures, the suitables rotor topology structure for the design of the motor is obtained. A prototype is developed and the test results verify the feasibility of the design.
2020, 47(9):61-65.
DOI: 10.12177/emca.2020.103
Abstract:
Shortcircuit explosions sometimes occur in the main terminal box (TB) of highvoltage (HV) motor, resulting in serious personal injuries or losses of property. It is of great practical significance to study the shortcircuit capacity of main TB. Based on the 10 kV pressure relief TB, the shortcircuit capacity test at 40 kA with a duration of 0.25 s is introduced. The universality suggestions of the TB design with high safety level are also proposed based on the test result, so as to reduce the risk of shortcircuit explosion from the design, and ensure safe and reliable operation of the main TB in the industrial field.
Shortcircuit explosions sometimes occur in the main terminal box (TB) of highvoltage (HV) motor, resulting in serious personal injuries or losses of property. It is of great practical significance to study the shortcircuit capacity of main TB. Based on the 10 kV pressure relief TB, the shortcircuit capacity test at 40 kA with a duration of 0.25 s is introduced. The universality suggestions of the TB design with high safety level are also proposed based on the test result, so as to reduce the risk of shortcircuit explosion from the design, and ensure safe and reliable operation of the main TB in the industrial field.
12 An Energy-Saving Design Scheme for the Stator Winding of Single-Winding Double-Speed Induction Motor
2020, 47(9):66-72.
DOI: 10.12177/emca.2020.098
Abstract:
Currently, two-speed or multi-speed energy-saving remanufacturing of motor system is generally realized by improved design of stator winding. But the energy efficiency at different speeds should be close to each other so that the optimal efficiency can be achieved under different rotating speeds in some special conditions. In response to this demand, three single-winding two-speed schemes of stator winding are compared, and it is found that the reverse commutation method can maintain a relatively high fundamental winding factor for both pole pair numbers. The effects of different pitches and winding turns on the motor performance are analyzed by finite element method, and the optimal winding design scheme is proposed. Taking a 5.5 kW, 4-pole motor as an example, the proposed method is used to carry out a 4/6 pole winding design and experiment validation. The results show that the motor efficiency is generally the same under the two speeds, which verifies the feasibility and effectiveness of the proposed design method.
Currently, two-speed or multi-speed energy-saving remanufacturing of motor system is generally realized by improved design of stator winding. But the energy efficiency at different speeds should be close to each other so that the optimal efficiency can be achieved under different rotating speeds in some special conditions. In response to this demand, three single-winding two-speed schemes of stator winding are compared, and it is found that the reverse commutation method can maintain a relatively high fundamental winding factor for both pole pair numbers. The effects of different pitches and winding turns on the motor performance are analyzed by finite element method, and the optimal winding design scheme is proposed. Taking a 5.5 kW, 4-pole motor as an example, the proposed method is used to carry out a 4/6 pole winding design and experiment validation. The results show that the motor efficiency is generally the same under the two speeds, which verifies the feasibility and effectiveness of the proposed design method.
2020, 47(9):73-78.
DOI: 10.12177/emca.2020.087
Abstract:
A 48 V belt driven starter generator (BSG) motor controller for mild hybrid vehicle is developed. The overall principle diagram of electrical design is described. The structure and hardware scheme of the 48 V BSG motor controller are analyzed in detail. A design scheme of 48 V BSG motor controller based on the MOSFET module is proposed. The thermal simulation of the heat dissipation baseplate is carried out to study its heat dissipation effect on MOSFET module. Finally, the bench test of the 48 V BSG motor controller prototype is carried out. The test results show that the 48 V BSG motor controller has a good control performance.
A 48 V belt driven starter generator (BSG) motor controller for mild hybrid vehicle is developed. The overall principle diagram of electrical design is described. The structure and hardware scheme of the 48 V BSG motor controller are analyzed in detail. A design scheme of 48 V BSG motor controller based on the MOSFET module is proposed. The thermal simulation of the heat dissipation baseplate is carried out to study its heat dissipation effect on MOSFET module. Finally, the bench test of the 48 V BSG motor controller prototype is carried out. The test results show that the 48 V BSG motor controller has a good control performance.
2020, 47(9):79-83.
DOI: 10.12177/emca.2020.102
Abstract:
Electromagnetic vibration and noise level is a comprehensive index to measure the comfort of electric vehicles. Radial electromagnetic force is the main excitation source of vibration and noise. The radial electromagnetic force of permanent magnet synchronous motor (PMSM) is analyzed. The three-dimensional spectrum obtained from the radial electromagnetic force space-time separation is used to extract the certain time-space order and the corresponding force densities which have great influence on the electromagnetic noise. The finite element method is used to simulate the vibration and noise of PMSMs with different types of step-skewed rotor. The optimal type of step-skewed rotor is found by comparing the results.
Electromagnetic vibration and noise level is a comprehensive index to measure the comfort of electric vehicles. Radial electromagnetic force is the main excitation source of vibration and noise. The radial electromagnetic force of permanent magnet synchronous motor (PMSM) is analyzed. The three-dimensional spectrum obtained from the radial electromagnetic force space-time separation is used to extract the certain time-space order and the corresponding force densities which have great influence on the electromagnetic noise. The finite element method is used to simulate the vibration and noise of PMSMs with different types of step-skewed rotor. The optimal type of step-skewed rotor is found by comparing the results.
2020, 47(9):84-90.
DOI: 10.12177/emca.2020.072
Abstract:
The electric spring (ES) can effectively improve the critical load (CL) power quality in view of the intermittent problems caused by new energy grid-connected power generation. When the grid voltage imbalance and line impedance resistance are large, there is control coupling. In this case, single-phase multi-ES cannot obtain stable voltage and frequency by traditional droop control. Therefore, it needs the droop control strategy with real-time correction of droop parameters. The second-order generalized integral generator is used to construct the virtual quadrature voltage and current signals to complete the single-phase dq rotational coordinate transformation. Then the optimized particle swarm optimization (PSO) is used to improve the droop coefficient in real time by detecting the voltage across the CL, collecting the balance information, and generating the state variable matrix. At the same time, the droop control module collects the circuit information in real time and inputs it to the PSO module to optimize the voltage deviation when each cycle is updated. The optimization result is fed back to the droop parameters for real-time update. Finally, the effectiveness of the proposed control strategy is verified by software simulation through comparing the traditional and the improved droop control strategies.
The electric spring (ES) can effectively improve the critical load (CL) power quality in view of the intermittent problems caused by new energy grid-connected power generation. When the grid voltage imbalance and line impedance resistance are large, there is control coupling. In this case, single-phase multi-ES cannot obtain stable voltage and frequency by traditional droop control. Therefore, it needs the droop control strategy with real-time correction of droop parameters. The second-order generalized integral generator is used to construct the virtual quadrature voltage and current signals to complete the single-phase dq rotational coordinate transformation. Then the optimized particle swarm optimization (PSO) is used to improve the droop coefficient in real time by detecting the voltage across the CL, collecting the balance information, and generating the state variable matrix. At the same time, the droop control module collects the circuit information in real time and inputs it to the PSO module to optimize the voltage deviation when each cycle is updated. The optimization result is fed back to the droop parameters for real-time update. Finally, the effectiveness of the proposed control strategy is verified by software simulation through comparing the traditional and the improved droop control strategies.
2020, 47(9):91-96.
DOI: 10.12177/emca.2020.106
Abstract:
In view of the over-current problem of wind turbines caused by voltage dips, the existing over-current suppression techniques based on virtual resistors cannot take into account both the over-current suppression effect and the fundamental frequency control performance. At the same time, the existing techniques do not consider the high-frequency steady-state performance of the system, leading to the poor harmonic suppression performance during the fault ride-through. In order to give consideration to both the performance of fault ride-through and the harmonic suppression during fault ride-through, the mechanism of over-current and transient flux suppression is studied by analyzing the mathematical model of doubly fed induction generator (DFIG) in the case of voltage dips, and based on the virtual impedance technique, an improved control technique for DFIG under voltage dips is proposed. In the improved control technique, an additional control loop is added to the rotor current control loop of the machine-side converter to suppress the transient flux oscillation and improve the performance of the DFIG. Furthermore, the parameters of the proposed virtual impedance link are designed and analyzed to ensure that the proposed control method can take into account overcurrent suppression performance, highfrequency performance and fundamental frequency control performance. Finally, simulation results verify the effectiveness and feasibility of the proposed improved control strategy.
In view of the over-current problem of wind turbines caused by voltage dips, the existing over-current suppression techniques based on virtual resistors cannot take into account both the over-current suppression effect and the fundamental frequency control performance. At the same time, the existing techniques do not consider the high-frequency steady-state performance of the system, leading to the poor harmonic suppression performance during the fault ride-through. In order to give consideration to both the performance of fault ride-through and the harmonic suppression during fault ride-through, the mechanism of over-current and transient flux suppression is studied by analyzing the mathematical model of doubly fed induction generator (DFIG) in the case of voltage dips, and based on the virtual impedance technique, an improved control technique for DFIG under voltage dips is proposed. In the improved control technique, an additional control loop is added to the rotor current control loop of the machine-side converter to suppress the transient flux oscillation and improve the performance of the DFIG. Furthermore, the parameters of the proposed virtual impedance link are designed and analyzed to ensure that the proposed control method can take into account overcurrent suppression performance, highfrequency performance and fundamental frequency control performance. Finally, simulation results verify the effectiveness and feasibility of the proposed improved control strategy.
2020, 47(9):97-105.
DOI: 10.12177/emca.2020.101
Abstract:
An ocean-current generator based on macro fiber composite (MFC) is proposed, and the performance of the generator is analyzed. Firstly, the cantilever structure is taken as the research object to analyze the influencing factors of performance of piezoelectric generation. The laws of influences of substrate materials, thickness, frequency, displacement excitation, and single/double crystal structure are researched. Then, an ocean-current generator based on MFC is designed according to the performance analysis results. Finally, the electricity generation performance of the ocean-current generator is analyzed. The maximum output power of the generator is 9.31 W at a rotor speed of 500 r/min, which can meet the power requirements.
An ocean-current generator based on macro fiber composite (MFC) is proposed, and the performance of the generator is analyzed. Firstly, the cantilever structure is taken as the research object to analyze the influencing factors of performance of piezoelectric generation. The laws of influences of substrate materials, thickness, frequency, displacement excitation, and single/double crystal structure are researched. Then, an ocean-current generator based on MFC is designed according to the performance analysis results. Finally, the electricity generation performance of the ocean-current generator is analyzed. The maximum output power of the generator is 9.31 W at a rotor speed of 500 r/min, which can meet the power requirements.
2020, 47(9):106-110.
DOI: 10.12177/emca.2020.095
Abstract:
Aiming at the vibration signal characteristics for asynchronous motor fault diagnosis，the method combining kurtosis, wavelet denoising and resonance demodulation analysis is proposed. We consider four types of motor states including the normal state, the incomplete open state of centrifugal switch, the chamber swept state, and the rear bearing damaged state, and collect the corresponding single-phase asynchronous motor samples for tests. NI CompactRIO is used to acquire the vibration signals at the side and top of the front cover for each motor. The kurtosis statistical analysis is firstly performed, and wavelet de-noising and resonance demodulation analysis are combined to extract the frequency domain characteristics for each failure type. The tests demonstrate the effectiveness of the proposed approach in the fault diagnosis of asynchronous motors.
Aiming at the vibration signal characteristics for asynchronous motor fault diagnosis，the method combining kurtosis, wavelet denoising and resonance demodulation analysis is proposed. We consider four types of motor states including the normal state, the incomplete open state of centrifugal switch, the chamber swept state, and the rear bearing damaged state, and collect the corresponding single-phase asynchronous motor samples for tests. NI CompactRIO is used to acquire the vibration signals at the side and top of the front cover for each motor. The kurtosis statistical analysis is firstly performed, and wavelet de-noising and resonance demodulation analysis are combined to extract the frequency domain characteristics for each failure type. The tests demonstrate the effectiveness of the proposed approach in the fault diagnosis of asynchronous motors.
You are thevisitor
沪ICP备16038578号-3
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.
