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Wireless power transfer (WPT) techniques have gained wide acceptance across a range of battery charging applications such as cell phones, cardiac pacemakers, and electric vehicles. In a wireless battery charging system, a constant current/constant voltage (CC/CV) charging strategy, regardless of the variation of the battery load which may roughly range from a few ohms to several hundred ohms, is typically adopted to ensure the safety, durability, and performance of the battery. However, system efficiency drops significantly as the load increases in CV mode, especially at very light-load conditions. This paper proposes an efficiency optimization method for an LCC-parallel compensated inductive power transfer (IPT) battery charging system without the help of any additional power converter and control method. The equivalent circuit and resonant conditions of the LCC-parallel compensation topology are firstly analyzed to achieve the load-independent CV output at a zero phase angle (ZPA) operating frequency. Over the full range of CV charging mode, the efficiency of the LCC-parallel resonant tank circuit is analyzed and optimized. An IPT battery charger prototype with 48 V charging voltage and 1 A charging current is implemented. A measured DC–DC transfer efficiency of greater than 90.48% is achieved during the whole CV charging profile.
Shuangcheng Yang; Xiangtian Deng; Jianghua Lu; Zhixuan Wu; Kai Du. Light-Load Efficiency Optimization for an LCC-Parallel Compensated Inductive Power Transfer Battery Charger. Electronics 2020, 9, 2080 .
AMA StyleShuangcheng Yang, Xiangtian Deng, Jianghua Lu, Zhixuan Wu, Kai Du. Light-Load Efficiency Optimization for an LCC-Parallel Compensated Inductive Power Transfer Battery Charger. Electronics. 2020; 9 (12):2080.
Chicago/Turabian StyleShuangcheng Yang; Xiangtian Deng; Jianghua Lu; Zhixuan Wu; Kai Du. 2020. "Light-Load Efficiency Optimization for an LCC-Parallel Compensated Inductive Power Transfer Battery Charger." Electronics 9, no. 12: 2080.
The DC-link voltage control (DVC) timescale (i.e., the frequency dynamics covering converter outer controls) instabilities in wind generation have gained increased attention recently. This paper presents DVC timescale modeling and stability analysis for multi doubly-fed induction generators (DFIGs) connected to weak AC grids. A reduced-order, small-signal model of a grid-tied multi-DFIG system, designed for DVC dynamics analysis, is firstly proposed. The model allows for the dynamic interactions among the DC-link voltage control, active power control (APC), terminal voltage control (TVC) and phase-locked loop (PLL). Eigenvalue and participation factor analyses are conducted to explore the potential instabilities and correlated critical factors for such a multi-machine system. The sensitivity studies find that instability can occur at high levels of power generations or low short-circuit ratio (SCR) conditions. In addition, the dominant mode is identified to be highly related to the PLL, and its modal damping is decreased when the bandwidths of PLLs in different generators are close. Detailed model-based time domain simulations verified the analysis above.
Dong Wang; Houquan Chen; Yunhui Huang; Xiangtian Deng; Guorong Zhu. Modeling and Stability Analysis of Weak-Grid Tied Multi-DFIGs in DC-Link Voltage Control Timescale. Energies 2020, 13, 3689 .
AMA StyleDong Wang, Houquan Chen, Yunhui Huang, Xiangtian Deng, Guorong Zhu. Modeling and Stability Analysis of Weak-Grid Tied Multi-DFIGs in DC-Link Voltage Control Timescale. Energies. 2020; 13 (14):3689.
Chicago/Turabian StyleDong Wang; Houquan Chen; Yunhui Huang; Xiangtian Deng; Guorong Zhu. 2020. "Modeling and Stability Analysis of Weak-Grid Tied Multi-DFIGs in DC-Link Voltage Control Timescale." Energies 13, no. 14: 3689.
Recent works have shown that phase-locked loop (PLL) synchronized wind turbines (WTs) suffer stability issues when integrated into weak grids. However, most of the current studies are limited to a single machine case, the interactions among the WTs are usually overlooked. This paper studies the stability of multiple doubly-fed induction generators (DFIGs) that are connected in parallel to a weak AC grid. A state space model of a two-DFIG system is firstly presented. Subsequently, eigenvalue sensitivity analysis shows that instability can occur at low short-circuit ratio (SCR) or heavy loading conditions. Meanwhile, participation factor analysis implies that the unstable mode is primarily induced by the interactions between the PLLs of the two WTs. Further, to make out how the PLLs interact to cause instability, a reduced-order model is proposed for analysis simplicity, and an explanation in terms of transfer function residue is given for illustration. Detailed model-based time domain simulations are conducted to validate the analyses’ results.
Dong Wang; Yunhui Huang; Min Liao; Guorong Zhu; Xiangtian Deng. Grid-Synchronization Stability Analysis for Multi DFIGs Connected in Parallel to Weak AC Grids. Energies 2019, 12, 4361 .
AMA StyleDong Wang, Yunhui Huang, Min Liao, Guorong Zhu, Xiangtian Deng. Grid-Synchronization Stability Analysis for Multi DFIGs Connected in Parallel to Weak AC Grids. Energies. 2019; 12 (22):4361.
Chicago/Turabian StyleDong Wang; Yunhui Huang; Min Liao; Guorong Zhu; Xiangtian Deng. 2019. "Grid-Synchronization Stability Analysis for Multi DFIGs Connected in Parallel to Weak AC Grids." Energies 12, no. 22: 4361.
A parallel active power filter (APF) is generally used to suppress dynamic harmonic current and compensate reactive power in the grid. However, parallel APF may have a negative effect on the load current when compensating the nonlinear load of a voltage source type, which may lead to the amplification effect of the load harmonic current. In this paper, the fundamental causes of harmonic current amplification were analyzed by studying the harmonic current amplification effect when a parallel APF compensates a nonlinear load. According to the results of the theoretical derivation, a feasible method to limit this current amplification effect by changing the system structure and the APF’s own control was proposed, and the corresponding design scheme is given. Finally, the correctness of the theoretical derivation of the harmonic current amplification effect and the feasibility of the proposed solution were proven through simulation and experiment.
Xueliang Wei; Cunzhong Li; Mingxuan Qi; Bingyang Luo; Xiangtian Deng; Guorong Zhu. Research on Harmonic Current Amplification Effect of Parallel APF Compensating Voltage Source Nonlinear Load. Energies 2019, 12, 3070 .
AMA StyleXueliang Wei, Cunzhong Li, Mingxuan Qi, Bingyang Luo, Xiangtian Deng, Guorong Zhu. Research on Harmonic Current Amplification Effect of Parallel APF Compensating Voltage Source Nonlinear Load. Energies. 2019; 12 (16):3070.
Chicago/Turabian StyleXueliang Wei; Cunzhong Li; Mingxuan Qi; Bingyang Luo; Xiangtian Deng; Guorong Zhu. 2019. "Research on Harmonic Current Amplification Effect of Parallel APF Compensating Voltage Source Nonlinear Load." Energies 12, no. 16: 3070.
This paper proposes an inductive power transfer (IPT) system with three-bridge switching compensation topology. With the proposed IPT topology, the equivalent circuit and the resonant condition are analyzed to achieve the load-independent constant current (CC) and load-independent constant voltage (CV) outputs. On this basis, multiple power levels can be achieved under CC/CV conditions by bridge arm switching, which makes it possible to complete charging tasks for multiple power level electric vehicles (EV) without switching the IPT system. A circuit simulation was built to verify the different power level switching effects of the structure. A 3.3 kW IPT system was designed to verify the proposed structure. At the rated output power, the experimental efficiency was up to 92.04% and 91.21% in CC and CV output modes, respectively.
Bingyang Luo; Yatao Shou; Jianghua Lu; Ming Li; Xiangtian Deng; Guorong Zhu; Luo; Shou; Lu; Li; Deng; Zhu. A Three-Bridge IPT System for Different Power Levels Conversion under CC/CV Transmission Mode. Electronics 2019, 8, 884 .
AMA StyleBingyang Luo, Yatao Shou, Jianghua Lu, Ming Li, Xiangtian Deng, Guorong Zhu, Luo, Shou, Lu, Li, Deng, Zhu. A Three-Bridge IPT System for Different Power Levels Conversion under CC/CV Transmission Mode. Electronics. 2019; 8 (8):884.
Chicago/Turabian StyleBingyang Luo; Yatao Shou; Jianghua Lu; Ming Li; Xiangtian Deng; Guorong Zhu; Luo; Shou; Lu; Li; Deng; Zhu. 2019. "A Three-Bridge IPT System for Different Power Levels Conversion under CC/CV Transmission Mode." Electronics 8, no. 8: 884.