| Dynamic wireless power transfer(DWPT)technology can provide real-time power supply for vehicles in motion through a non-contact way,which is conducive to reducing battery usage,lowering overall vehicle weight and cost,shortening charging time and extending driving range,and has important research significance and practical value.As the system spreads farther,transmits more power and is compatible with more working conditions,it faces a number of key issues such as rail segmentation and power supply,power stable transmission and multi-frequency load compatibility that need to be solved.This dissertation focus on the above key issues of the transmitter side of the electric vehicle DWPT system,and aim to provide theoretical support and feasible solutions for the transmitter topology configuration and control method of DWPT system.In order to provide a theoretical basis for the analysis and design of DWPT systems,the transmission characteristics are described analytically and expressed uniformly.Based on the two-port theory,a generic transmission model of the system module cascade is established.The input and output impedances of the modules at each port are derived,and the resonance conditions of the system are solved based on the zero imaginary part of the impedance.Using Middlebrook stability criterion,the cascade stability of the system with various topologies is investigated,and it is proved that the T-S topology has relatively better stability,and the Buck topology of the receiver converter is better than the Boost topology.The gain characteristics and efficacy characteristics of the DWPT system under various complex operating conditions are analyzed,and it is proved that the T-S-Buck topology driven by voltage source has better adaptability to mutual inductance fluctuation and load variation,and is more suitable for DWPT system.In order to improve the economy and efficiency of the DWPT system,the segmented power supply topology and switching control method of the transmitter rail are investigated.The configuration and switching methods of existing typical power supply topologies are analyzed and evaluated.A power supply topology and control method for online switching are proposed for the centralized source type power supply topology.And a road section level power supply topology is constructed to ensure the superior economy and realize the online switching,which greatly improves the response speed and switching control characteristics of the system.For the distributed source type power supply topology,a MT-type topology with mutualcompensated rails is proposed,its constant current and resonant conditions are given,and a phase-shifting control method of the transmitter current based on a three-bridge inverter is proposed,which reduces the number of power supplies and resonant devices,reduces the volume and cost,and improves the economy on the basis of the excellent characteristics of the T-type topology.In order to improve the power level and reduce the output fluctuation,a threephase transmitter system is studied.It is modeled and its power characteristics are analyzed to reveal the suppression principle for output power fluctuations.On this basis,a three-phase transmitter single-phase receiver DWPT system is constructed,and its three-phase unbalanced and position-dependent reflected impedance characteristics are analyzed,and a three-phase T-topology is proposed to compensate for it and ensure the symmetry of the transmitter current.The transmitter current regulation method and the constant current control method to suppress bus powerfrequency fluctuations are proposed to ensure the symmetry of the three-phase transmitter current while realizing the full range of induced voltage and output power regulation.An experimental platform is built and it is proved that the proposed threephase transmitter can improve the stability of induced voltage and output power,and the induced voltage and the output power fluctuation rate is ±5.38% and ±7.76%.The compensation topology and decoupling control method for solving the dualfrequency load compatibility at the transmitter side are studied.A transmitting system with load frequency compatibility and power decoupling based on current modulation and L(CL)C dual-frequency compensation topology is proposed.Compared with the single-frequency load system,the mutual coupling at the receiver side can avoid the problems of reducing the output power and system efficiency,as well as affecting the resonance at the transmitter side,increasing the reactive power and thus reducing the output capacity of the power supply.In order to realize the system decoupling control,the SPWM dual-frequency modulation method based on single-phase full-bridge inverter is proposed to obtain the transmitter current with two independently adjustable frequency components and realize the current dual closed-loop decoupling control.The experimental platform is built to demonstrate that it is compatible with two resonant frequencies of 20 k Hz and 85 k Hz with mutually coupled receivers,and a single inverter with a single transmitter rail can supply power to both receivers simultaneously,and the transmitter current and output power of both frequencies can be adjusted independently. |
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