Xuling Chen

Modeling and Optimization of Magnetically Coupled Resonant Wireless Power Transfer System With Varying Spatial Scales

Previous work reveals that the magnetically coupled resonant (MCR) wireless power transfer (WPT) technology is efficient and practical for mid-range wireless energy transmission, able to handle nontrivial amount of power. Due to the variable coupling coefficient under lateral misalignment and angular misalignment between transmitting coils and receiving coils, the output power and transmission efficiency will fluctuate, leading to instability of the system. This paper presented an equivalent analytical model for the MCR WPT system to incorporate spatial misalignments. The mutual inductance formulas were derived when receiving coils are laterally, angularly or generally misaligned from transmitting coils. The relationship among the output power, transmission efficiency, the mutual inductance, and load resistance were analyzed in detail. For the design of the MCR WPT system, it is necessary to seek optimal transmission performance under different applications. To achieve maximum output power and high stability of power transfer in a specific misalignments range, a normalization method based on the obtained analytical model was introduced, providing critical insight into the optimal design of coils. Relative design considerations and optimization procedures were further stated. Experiments had also been carried out to evaluate the accuracy of theoretical analysis and confirm the validity of the proposed optimization method.

Optimization of coils for magnetically coupled resonant wireless power transfer system based on maximum output power

Magnetically coupled resonant (MCR) wireless power transfer (WPT) technology is efficient and practical for mid-range wireless energy transmission. For the design of MCR WPT system, it is necessary to seek optimal transmission performance under different applications. This paper presented an equivalent analytical model for such system to incorporate spatial misalignments between the transmitting coils and receiving coils. According to the obtained model, the relationship among the output power, spatial misalignments and coil parameters were analyzed in detail. To achieve maximum output power and high stability of power transfer in a specific misalignments range, a normalization method was introduced, providing critical insight into the optimal design of coils. Relative design considerations and optimization procedures were further stated. Experiments had also been carried out to evaluate the accuracy of theoretical analysis and confirm the validity of the proposed method.

A maximum power point tracking control scheme for magnetically coupled resonant wireless power transfer system by cascading SEPIC converter at the receiving side

Variation of spatial scales and load resistances have significant effects on the transmission power of magnetically coupled resonant (MCR) wireless power transfer (WPT) system. To realize maximum power transmission under arbitrary spatial scale and different load resistances, a control scheme for automatic maximum power point tracking (MPPT) operation was presented in this paper. Based on the transmission power characteristics of a two-coil WPT system with a series resonant topology, a SEPIC converter was introduced to cascade at the receiving side to achieve MPPT for MCR WPT system. Adopting perturbation and observation (P&O) method to adjust equivalent input resistance of SEPIC converter dynamically, the proposed scheme tracked the maximum transmission power operating point by matching the corresponding mutual inductance with varying spatial scales. The experimental results had shown the validity of the theoretical analysis and the feasibility of the proposed scheme.

Comprehensive Analysis of Three-Phase Three-Level LC-Type Resonant DC/DC Converter With Variable Frequency Control—Series Resonant Converter

A three-phase three-level (TPTL) converter is an optimal alternative for high-input and high-power dc/dc conversion system. The voltage stress on the primary switch is only half of the input voltage due to its three-level (TL) structure, and the current rating of power devices can be reduced by the three-phase configuration. To achieve soft switching and improve efficiency, the resonant tank can be introduced to optimize the performance of the converter. In this paper, a novel TPTL LC-type series resonant converter with few switches and simple configuration is proposed. The voltage stress on all switches can be reduced to the half of the input voltage, and the voltage across output rectifiers is clamped to the output voltage; as a result, the proposed converter is suitable for high-input/output applications. Meanwhile, the ripple frequency of the output current can be increased significantly, resulting in a reduced filter requirement. Variable frequency control strategy is adopted in order to obtain zero-voltage switching for all switches and zero-current switching for all rectifier diodes in wide input voltage and load range. In this paper, the comprehensive analysis on the proposed converter is carried out, including the operation mode classification, the operating mechanism under different operation mode, along with the circuit model, and gain characteristics of the converter by the fundamental harmonic analysis. Experimental results from a 440–590 V input and 400 V/5 A output are presented to verify the theoretical analysis and the performance of the converter.

Optimization of coils for a three-phase magnetically coupled resonant wireless power transfer system oriented by the zero-voltage-switching range

Multi-phase magnetically coupled resonant (MCR) wireless power transfer (WPT) technology has become one of the most promising technologies in the mid-range applications, as it effectively reduces the limits of coils spatial locations on power transfer. In this paper, a kind of three-phase MCR WPT system was investigated and the equivalent circuit model was built for theoretical analysis. Meanwhile, this paper analyzed the influential factors on zero-voltage-switching (ZVS) conditions of power switches in the driver inverter, including input voltage phase difference, coil turns and spatial locations of receiving coil. Detailed discussions on relationships between coil turns, spatial locations and ZVS conditions were completed under different input voltage phase difference. Further, coil turns were optimized to ensure the power switches realize ZVS within the full range of angular misalignment, and the corresponding characteristic of output power was derived. Finally, the experiments had been carried out to confirm to the theoretical analysis.

Optimization of coils and control strategy for a three-phase magnetically coupled resonant wireless power transfer system oriented by the optimal output power characteristics

Multi-phase magnetically coupled resonant (MCR) wireless power transfer (WPT) technology, which can effectively reduce the limits of coils spatial locations on power transfer, has become one of the most promising technologies in the mid-range applications. In this paper, a three-phase MCR WPT system was investigated and the equivalent circuit model was built and simplified. Based on the theoretical analysis of the simplified model, the influential factors on output power of the system were revealed, including the phase-shifted angle between each phase, coil turns and spatial locations of receiving coil. Further, coil turns and control strategy of the phase-shifted angle were optimized to ensure the system realize the optimal output power characteristics that was defined as the one with high amplitude and minor fluctuations within the full range of angular misalignment. Finally, the experiments had been carried out to confirm the theoretical analysis.

Modeling of wireless power system with giant magnetostrictive material load under multi-field coupling

Giant magnetostrictive material (GMM) is a new material which owes several characteristics such as giant magnetostriction and fast dynamic response. It can be driven by the electromagnetic field, and can be used into wireless power transfer (WPT) system in order to convert the electrical energy to the mechanical energy in real time. Several issues on electrical-magnetic-mechanical multi-field coupling can be found in magnetically coupled resonant (MCR) WPT system with GMM load, which increases the complexity and difficulty of system modeling, design and control. In this paper, the MCR WPT system with GMM load is analyzed, and the equivalent circuit of MCR WPT system is established to compare with that with the resistive load. The impedance characteristic of GMM coil as the receiving load of MCR WPT system is analyzed by multi-field theory, which is proved to present inductive composed by the electrical part and the mechanical part. Based on impendence model of GMM, the receiving terminal of MCR WPT system is simulated and experimented. It can be found that the experimental results are well consistent with the theoretical analysis. Meanwhile, based on the equivalent circuit of MCR WPT system, researches on relationships between transmission power, transmission distance and operating frequency are carried out. The research results show the correctness and effectiveness of the proposed modeling method.

Transmission characteristics analysis of a three-phase magnetically coupled resonant wireless power transfer system

Multi-phase magnetically coupled resonant (MCR) wireless power transfer (WPT) technology has attracted wide spread attention recently, for it can not only reduce the sensitivity of system to the spatial scale effectively, but also maintain the high transmission efficiency and power in the middle distance. This paper presented an analytical equivalent model for a three-phase MCR WPT system under phase angle control method with different spatial locations between the sending coils and receiving coil. The mutual inductance formulas of the sending coils and receiving coil were derived. The relationship among the output power, transmission efficiency and the angular misalignments were analyzed in detail. Experiments have also been carried out to facilitate quantitative comparison and validate the theoretical analysis.

Modeling and investigation of 4-coil wireless power transfer system with varying spatial scales

As a mid-range wireless power transfer (WPT) technology, magnetically coupled resonant (MCR) WPT has become a reseach focus in recent years. In this paper, an equivalent circuit model of 4-coil MCR WPT system was presented, along with the formulas of the output power and transmission efficiency. Besides, to comfirm whether spatial misalignments will influence the transmission characteristics of the system, the relationship between the mutual inductance and the spatial misalignments of the coils was analyzed, and the transmission characteristics under various spatial scales was revealed. An experiment circuit was designed and experimental results were well consistent with the theoretical analysis.