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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]

The coupling of converters with resonant networks poses significant challenges for frequency tracking and power control in inductive power transfer (IPT) systems. This paper presents an implementation method that addresses these issues by dividing the system's operation into two distinct states: self-oscillating and power-injecting. Based on these states, a phase-closed loop is constructed. Within this closed loop, the phase tracking unit detects and tracks frequency drift, while the power regulating unit incorporates an integrator and adopts a control variable to adjust the output power by modifying the duration of the power injecting state. Meanwhile, the oscillating unit operates in the self-oscillating state. Operating in this manner, the system achieves self-oscillation and demonstrates the capability to effectively track and compensate for system variations within a single cycle. A verification prototype has been constructed, and it demonstrates that the converter within it completely decoupled from the resonant network. Experimental results validate that altering the control variable solely affects the duration of the power-injecting state, allowing for independent control of the output power. When the control variable changes from 2.0 V to 3.5 V, the output power changes from 178 W to 519 W while the self-oscillating state remains unchanged. Furthermore, the system accurately tracks frequency changes, even under significant variations in the coupling coefficient or load, without compromising the power injection state. When the air gap changes from 3 cm to 12 cm, the duration of the self-oscillating state changes from 22.1 μs to 26.3 μs, while the power injecting state remains unchanged. This approach exhibits a robust performance, particularly suitable for dynamic IPT systems sensitive to parameter variations. [ABSTRACT FROM AUTHOR]

An automatic stage transition converter for an inductive power transfer system is presented in this paper. An effective control strategy with two working stages of independent energy injection stage and free resonance stage is employed in the proposed converter. With the automatic stage transition strategy, when the frequency of the resonance network changes, the ending time of the free resonance stage is automatically determined. At the same time, the phase angle of the free resonance stage is automatically set as half a resonant cycle. As the stage transition is not triggered by the switches, the switch motion can be executed in advance of the transition moments. Time margins are offered for every switch in the converter, which make the switching moments of the switches flexible and the control simple. Another feature of this converter is that during the energy injection stage, the energy is injected into the inductor independently. Therefore, the input power can be easily regulated by adjusting the energy injection time. A prototype for the converter and the inductive power transfer system was implemented experimentally. From the experimental results, the automatic stage transition and power regulation capability of the proposed converter are verified. The switches all operated at the soft switch condition. When the energy injection time was adjusted from 10 μs to 25 μs, the output power changed from 143 W to 740 W. [ABSTRACT FROM AUTHOR]

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]

This paper presents a study of a piezoelectric energy harvesting circuit based on low-power-consumption synchronized switch technology. The proposed circuit includes a parallel synchronized switch harvesting on inductor interface circuit (P-SSHI) and a step-down DC-DC converter. The synchronized switch technology is applied to increase the conversion efficiency of the circuit. The DC-DC converter is used to accomplish the impedance matching for different loads. A low-power-consumption microcontroller and discrete components are used to build the P-SSHI interface circuit. The study starts with theoretical analysis and simulations of the P-SSHI interface circuit. Simulations and experiments were conducted to validate the theoretical analysis. The experimental results show that the maximum energy harvested by the system with a P-SSHI interface circuit is 231 μW, which is 2.89 times that of a system without the P-SSHI scheme. The power consumption of the P-SSHI interface circuit can be as low as 10.6 μW. [ABSTRACT FROM AUTHOR]

In order to compensate the large leakage inductance and improve the power transmission capacity, capacitors are widely used in inductive power transfer (IPT) systems, which results in high voltage or current stresses in the resonant tanks and limits higher volt-ampere (VA) rating of the transfer power, especially in medium and low frequency applications. This paper presents a symmetrical half-bridge resonant converter (SHRC) for series-series/series compensated IPT systems with detailed analysis and design. It operates at a relatively low frequency of 12.5 kHz, suitable for IGBT applications. The theoretical analysis shows that, compared with full-bridge resonant converter (FRC) for IPT, the symmetrical half-bridge resonant converter achieves a higher efficiency. Simulation and a prototype of 1500 W power output were built to verify the theoretical analysis. The experimental results show that the power loss of SHRC is 39.7 W while that of FRC is 79.4 W, which is consistent with the theoretical analysis. The global efficiency of the IPT based on the proposed converter is 91.6%. [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]