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For an electric locomotive traction motor, it is necessary to maintain relatively low vibration and noise due to the higher design standards. By using effective motor control strategies and implementing current harmonic suppression schemes, motor efficiency and vibration and noise suppression can be effectively improved. This study investigates the current harmonic suppression strategy for permanent magnet synchronous motors by (1) constructing a mathematical model of the permanent magnet motor to explore the sources of low-order harmonics currents such as fifth and seventh harmonics, as well as high-order harmonics at switch frequencies and their multiples, and analyzing the electromagnetic force characteristics generated by the current, and (2) establishing a vector control system for the permanent magnet motor. To suppress the fifth and seventh harmonic components in the current, a resonance controller is constructed, which utilizes the parallel connection of a resonator and PI controller to achieve low-order harmonic suppression. The factors affecting the effectiveness of the resonance controller's suppression are also analyzed. The experiments are conducted, and the current harmonic suppression scheme constructed in this study can effectively reduce the harmonics in the current, thereby reducing motor vibration and noise. [ABSTRACT FROM AUTHOR]

Aiming at the adverse influence of penalty parameter and mode number on the VMD（ variational mode decomposition）,a newly MVMD（ modification variational mode decomposition） was proposed through the information entropy difference. The change of the amount of information in each mode extraction characteristic of information entropy difference was analyzed. The information entropy difference under the condition of different penalty parameters was got through making full use of the analysis result of extraction characteristic. The excellent penalty parameter was determined in the position of jumpy information entropy difference. The Fourier spectrum of MVMD was used to detect the unbalance of Cardan shaft in high-speed train. The method and model was verified through the unbalance experiment data. The experiment results show that this method could effectively seize the basic frequency,multi-frequency fault features. With comparison to VMD,the problem of Parameter selection has been solved. With comparison to the classic ensemble empirical model decomposition,the fault detection ability has been significantly improved.

Strong coupling in an inductive power transfer (IPT) system will lead to difficulties in power control and loss of soft switching conditions. This paper presents an IPT system that can decouple the converter from the resonant network. In the proposed system, the energy transmission process is divided into energy injection stage and free resonance stage. In the energy injection stage, the inductor is separated from the resonance network, and the power source injects energy into the inductor independently. In the free resonance stage, the inductor is connected to the resonance network for resonating. As a benefit from the decoupling of the converter from the resonance network, the proposed IPT system is characterized by easy power control and soft switching operation. A prototype was built for experiments. The experimental results show that with a supply voltage of 300 V, coupling factor of 0.2, and load resistance of 10 Ω, the output power can be controlled nearly linearly by the time of the energy injection stage in a range of 40–60 μs, and the system works under soft switching conditions. [ABSTRACT FROM AUTHOR]

In a traditional inductive coupling power transfer (ICPT) system, the converter and the resonant network are strongly coupled. Since the coupling coefficient and the parameters of the resonant network usually vary, the resonant network easily detunes, and the system efficiency, power source capacity, power control, and soft switching conditions of the ICPT system are considerably affected. This paper presents an ICPT system based on a power converter decoupled from the resonant network. In the proposed system, the primary inductor is disconnected from the resonant network during the energy injection stage. After storing a certain amount of energy, the primary inductor is reconnects with the resonant network. Through this method, the converter can be decoupled from the resonant network, and the resonant network can be tuned under various coupling coefficients. Theoretical analysis was explored first. Simulations and experimental work are carried out to verify the theoretical analysis. The results show that the proposed ICPT system has the virtues of low power source capacity, independent power control, and soft switching operation under different coupling coefficients. [ABSTRACT FROM AUTHOR]