The Experts below are selected from a list of 31872 Experts worldwide ranked by ideXlab platform
Jiacheng Wang - One of the best experts on this subject based on the ideXlab platform.
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Reference Trajectory optimized svm for high power current source converters to improve harmonic performance and reduce common mode voltage
IEEE Transactions on Power Electronics, 2015Co-Authors: Anping Hu, Dewei David Xu, Bin Wu, Jiacheng Wang, Jianhui SuAbstract:For medium-voltage high-power drives fed by current-source converters (CSCs), a transformerless configuration has benefits in both cost and volume. Removing the isolation transformer necessitates a common-mode choke to undertake the major portion of the drive's common-mode voltage (CMV) stress, which would otherwise cause premature failure of the motor insulation system. On the other hand, as device switching frequency in high-power CSCs is normally limited to a few hundred hertz, improving harmonic performance via modulation has always been a challenge. Selective harmonic elimination (SHE) is a preferred modulation scheme in such a system owing to its ability to eliminate several unwanted low-order harmonic currents. Alternatively, conventional space vector modulation (SVM) provides continuous modulation index adjustment capability, but its output current contains low-order harmonics with high magnitudes that may arouse harmful resonances in the system. Aiming at reducing CMV and improving harmonic performance at the same time, this paper proposes a new SVM-based modulation strategy for high-power CSCs using synthesized Reference Trajectory on the hexagon in the αβ plane. Along with the proposed strategy, two methods of Reference Trajectory optimization (RTO) are investigated. By introducing a coefficient to the duty-cycle function for RTO, the first method can remove an extra low-order harmonic component, or minimize the weighted total harmonic distortion. The second method, with a different approach of RTO, eliminates the unwanted low-order harmonics by combining the proposed SVM with the SHE. The proposed concepts are verified by both simulation and experimental results.
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Reference Trajectory optimized svm for high power current source converters to improve harmonic performance and reduce common mode voltage
IEEE Transactions on Power Electronics, 2015Co-Authors: Jiacheng WangAbstract:For medium-voltage high-power drives fed by current-source converters (CSCs), a transformerless configuration has benefits in both cost and volume. Removing the isolation transformer necessitates a common-mode choke to undertake the major portion of the drive's common-mode voltage (CMV) stress, which would otherwise cause premature failure of the motor insulation system. On the other hand, as device switching frequency in high-power CSCs is normally limited to a few hundred hertz, improving harmonic performance via modulation has always been a challenge. Selective harmonic elimination (SHE) is a preferred modulation scheme in such a system owing to its ability to eliminate several unwanted low-order harmonic currents. Alternatively, conventional space vector modulation (SVM) provides continuous modulation index adjustment capability, but its output current contains low-order harmonics with high magnitudes that may arouse harmful resonances in the system. Aiming at reducing CMV and improving harmonic performance at the same time, this paper proposes a new SVM-based modulation strategy for high-power CSCs using synthesized Reference Trajectory on the hexagon in the αβ plane. Along with the proposed strategy, two methods of Reference Trajectory optimization (RTO) are investigated. By introducing a coefficient to the duty-cycle function for RTO, the first method can remove an extra low-order harmonic component, or minimize the weighted total harmonic distortion. The second method, with a different approach of RTO, eliminates the unwanted low-order harmonics by combining the proposed SVM with the SHE. The proposed concepts are verified by both simulation and experimental results.
Jianhui Su - One of the best experts on this subject based on the ideXlab platform.
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Reference Trajectory optimized svm for high power current source converters to improve harmonic performance and reduce common mode voltage
IEEE Transactions on Power Electronics, 2015Co-Authors: Anping Hu, Dewei David Xu, Bin Wu, Jiacheng Wang, Jianhui SuAbstract:For medium-voltage high-power drives fed by current-source converters (CSCs), a transformerless configuration has benefits in both cost and volume. Removing the isolation transformer necessitates a common-mode choke to undertake the major portion of the drive's common-mode voltage (CMV) stress, which would otherwise cause premature failure of the motor insulation system. On the other hand, as device switching frequency in high-power CSCs is normally limited to a few hundred hertz, improving harmonic performance via modulation has always been a challenge. Selective harmonic elimination (SHE) is a preferred modulation scheme in such a system owing to its ability to eliminate several unwanted low-order harmonic currents. Alternatively, conventional space vector modulation (SVM) provides continuous modulation index adjustment capability, but its output current contains low-order harmonics with high magnitudes that may arouse harmful resonances in the system. Aiming at reducing CMV and improving harmonic performance at the same time, this paper proposes a new SVM-based modulation strategy for high-power CSCs using synthesized Reference Trajectory on the hexagon in the αβ plane. Along with the proposed strategy, two methods of Reference Trajectory optimization (RTO) are investigated. By introducing a coefficient to the duty-cycle function for RTO, the first method can remove an extra low-order harmonic component, or minimize the weighted total harmonic distortion. The second method, with a different approach of RTO, eliminates the unwanted low-order harmonics by combining the proposed SVM with the SHE. The proposed concepts are verified by both simulation and experimental results.
Jacob F Sherson - One of the best experts on this subject based on the ideXlab platform.
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fast state transfer in a λ system a shortcut to adiabaticity approach to robust and resource optimized control
New Journal of Physics, 2018Co-Authors: H Mortensen, Jens Jakob Sorensen, Klaus Molmer, Jacob F ShersonAbstract:We propose an efficient strategy to find optimal control functions for state-to-state quantum control problems. Our procedure first chooses an input state Trajectory, that can realize the desired transformation by adiabatic variation of the system Hamiltonian. The shortcut-to-adiabaticity formalism then provides a control Hamiltonian that realizes the Reference Trajectory exactly but on a finite time scale. As the final state is achieved with certainty, we define a cost functional that incorporates the resource requirements and a perturbative expression for robustness. We optimize this functional by systematically varying the Reference Trajectory. We demonstrate the method by application to population transfer in a laser driven three-level Λ-system, where we find solutions that are fast and robust against perturbations while maintaining a low peak laser power.
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fast state transfer in a lambda system a shortcut to adiabaticity approach to robust and resource optimized control
arXiv: Quantum Physics, 2017Co-Authors: H Mortensen, Jens Jakob Sorensen, Klaus Molmer, Jacob F ShersonAbstract:We propose an efficient strategy to find optimal control functions for state-to-state quantum control problems. Our procedure first chooses an input state Trajectory, that can realize the desired transformation by adiabatic variation of the system Hamiltonian. The shortcut-to-adiabaticity (STA) formalism then provides a control Hamiltonian that realizes the Reference Trajectory exactly but on a finite time scale. As the final state is achieved with certainty, we define a cost functional that incorporates the resource requirements and a perturbative expression for robustness. We optimize this functional by systematically varying the Reference Trajectory. We demonstrate the method by application to population transfer in a laser driven three-level {\Lambda}-system, where we find solutions that are fast and robust against perturbations while maintaining a low peak laser power.
Anping Hu - One of the best experts on this subject based on the ideXlab platform.
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Reference Trajectory optimized svm for high power current source converters to improve harmonic performance and reduce common mode voltage
IEEE Transactions on Power Electronics, 2015Co-Authors: Anping Hu, Dewei David Xu, Bin Wu, Jiacheng Wang, Jianhui SuAbstract:For medium-voltage high-power drives fed by current-source converters (CSCs), a transformerless configuration has benefits in both cost and volume. Removing the isolation transformer necessitates a common-mode choke to undertake the major portion of the drive's common-mode voltage (CMV) stress, which would otherwise cause premature failure of the motor insulation system. On the other hand, as device switching frequency in high-power CSCs is normally limited to a few hundred hertz, improving harmonic performance via modulation has always been a challenge. Selective harmonic elimination (SHE) is a preferred modulation scheme in such a system owing to its ability to eliminate several unwanted low-order harmonic currents. Alternatively, conventional space vector modulation (SVM) provides continuous modulation index adjustment capability, but its output current contains low-order harmonics with high magnitudes that may arouse harmful resonances in the system. Aiming at reducing CMV and improving harmonic performance at the same time, this paper proposes a new SVM-based modulation strategy for high-power CSCs using synthesized Reference Trajectory on the hexagon in the αβ plane. Along with the proposed strategy, two methods of Reference Trajectory optimization (RTO) are investigated. By introducing a coefficient to the duty-cycle function for RTO, the first method can remove an extra low-order harmonic component, or minimize the weighted total harmonic distortion. The second method, with a different approach of RTO, eliminates the unwanted low-order harmonics by combining the proposed SVM with the SHE. The proposed concepts are verified by both simulation and experimental results.
Michael Wang - One of the best experts on this subject based on the ideXlab platform.
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Reference Trajectory generation for force tracking impedance control by using neural network based environment estimation
Robotics Automation and Mechatronics, 2006Co-Authors: Heng Wang, K H Low, Michael WangAbstract:This paper presents a Reference Trajectory generation approach for impedance control by using neural networks to estimate the environment dynamics. In this method, the environment dynamics is estimated by a neural network (NN1), which constructs the relationship between the environment deformation and its first and second derivatives, and the interaction force. Another network (NN2) is then used to approximate the statics of the environment, which is the relationship between the interaction force and the deformation. The major advantage of the proposed method is that no exact environment model is required, so that it suites for operations on any unstructured environments. Furthermore, the neural networks have the capability of learning, due to which the precision of the generated Reference Trajectory will continuously be increased as the robot-environment interaction lasts. The system performance by using the proposed method is evaluated by simulations.