| Dynamic Wireless Power Transmission(DWPT)for electric vehicles provides energy supply to electric vehicles in a non-contact manner,which reduces the demand for on-board battery capacity,improves the user experience,and is conducive to the further promotion of electric vehicles.With the increasing demand for system energy efficiency and electromagnetic safety from DWPT technology,DWPT systems using short transmitters have received increasing attention.Their "point to point" approach not only has high efficiency and good electromagnetic safety,but also facilitates the design of power supply capacity,and the range of power loss caused by the loss of a single coil is also small.The combination of short transmitter and LCC compensation topology makes the system possess the advantages of high power,high efficiency,and high stability,making it one of the most widely used configurations in electric vehicle wireless power supply systems.In this paper,a short transmitter coil for LCC compensation is considered as a transmitter unit,and based on this,the coupling parameter design method,compensation network parameter method,and topology structure of the transmitter unit are studied in order to improve the engineering practicality of the transmitter unit and promote the popularization and application of industrialization.First,in order to meet the energy supply requirements of current working conditions for transmitter units,and to address the problems of poor working condition correlation and weak energy matching in existing coupling parameter design methods,this paper proposes an energy balance based coupling parameter design method for transmitter units.By constructing displacement elements,a discrete wireless charging energy model suitable for irregular mutual inductance distribution is established.Combining with the actual variable speed operating conditions,a continuous processing method for discrete operating conditions of electric vehicles is presented,and an energy balance model for the transmitter unit is established.Based on the planar spiral coil structure,a detailed design process for the coupling parameters of the transmitter unit was established,and the design result with the highest compatibility with the operating energy consumption was obtained.Energy gain hot zone of a transmitter unit was given.Second,in order to achieve the design of transmitter unit compensation network parameters under variable mutual inductance and variable load conditions,and improve the comprehensiveness and versatility of LCC compensation network design methods in DWPT systems,this paper studies a method for designing LCC compensation network parameters that considers variable mutual inductance,variable load,multiple constraints,and cooperatively designs optional objective functions for excitation current.By establishing a circuit model of the inductance and capacitance compensation coefficients,the solution variables of the compensation network parameters are normalized,and the influence of the compensation coefficients on the main characteristics of the system is analyzed.By constructing the calculation formulas for load average efficiency,system overall efficiency,and system load average total energy consumption,the expressions for each constraint condition of the DWPT system under variable mutual inductance and variable load conditions are established.A mathematical model for solving the inductance compensation coefficient and the excitation current at the transmitter under optional objective functions is established,with the lowest average total energy consumption of the load and the lowest supply voltage demand of the inverter source as the objective functions,respectively.The specific design results are given,and a ZVS for decoupling the voltage gain from the load is achieved.Then,in order to reduce the cost of transmitter units and suppress the impact of device parameter errors,a highly economical multiplexing LCC Module(MLM)topology and corresponding parameter error suppression methods are proposed.Firstly,the influence of parameter errors on system characteristics is analyzed from the perspective of power conversion rate and power consistency.Subsequently,an MLM with device reuse characteristics is proposed,and the working principle,layout,and action logic of MLM are explained.Compared to traditional independent source LCC compensation topology,MLM can save 50% of the inverter source,25% of the compensation capacitance,and 100% of the compensation inductance.For parameter error suppression,a rearrangement method and a voltage adjustment method are proposed.The results show that the method can eliminate the adverse effects on power conversion and power consistency when the parameter error is 5%.Finally,a testing topology MLMC that can adapt to different power sources is proposed,and an experimental prototype is built to verify the functional feasibility of MLM and MLMC.Finally,when short transmitters are arranged in an overlapping manner,the strong mutual coupling between the transmitters will lead to over-voltage and over-current hazards to the circuit of compensation networks.Aiming at this problem,this paper proposes a parallel LCC compensation topology with back switches(PLCTBS)for suppressing coil coupling.Firstly,the application scenarios and working modes of the coil element coupling problem are analyzed,and based on the mutual inductance coupling model,the coupling diffusion problem of the coil element under the independent source LCC compensation topology is revealed.Subsequently,a PLCTBS topology for suppressing coupling diffusion is proposed and its working principle is explained.In order to reduce the switching steady-state isolation voltage of PLCTBS,a three coil coupling model was established,and the expression of the switching isolation voltage was derived.The superiority of PLCTBS in the same terminal connection mode was established.The correctness of theoretical and simulation results was verified by experiments.The results showed that PLCTBS can effectively work in situations where mutual coupling mutual inductance is 330% of primary and secondary coupling mutual inductance,The maximum isolation voltage of the switch in the dotted connection mode can be as low as 50% of that in the undotted connection mode.Finally,the application of multilevel PLCTBS is studied and generalized,and the expression of switching steady-state isolation voltage corresponding to multi source and multi load conditions is derived. |
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