| Wireless power transmission technology is an emerging technology to achieve by means of electromagnetic coupling energy in the form of wireless transmission.The technologies in recent years become a hot research investigators,it has been in electric cars,digital home appliances,industrial lifting,oil drilling and other fields has been widely used.Although there are a large number of applications,but the low efficiency of the runtime is still plagued by one of the bottlenecks of the technology development.To enhance efficiency,researchers have proposed some solutions,but they are optimized for a single target or control,optimal efficiency can not be achieved globally integrated control system.To achieve the integrated control system,we must now consider a number of system performance,complete system design from a global point of view,control and optimization.However,due to the wireless power transmission system is in the form of a loosely coupled system,and the system and the presence of multi-stage resonance system strong nonlinear components,causing the system exhibits a complex structure and operating characteristics,system design and control are more difficult.Aiming at these problems from the control theory point of view,the demand for multi-objective optimal conditions for efficient system design and optimization control research,including research work is mainly carried out in the following aspects:(1)To improve the WPT system efficiency,this thesis proposes a two degree of freedom tracking control method for maximum efficiency.This method utilzes active matching for maximum efficiency through real-time identification of the load parameters.By dynamically varying the duty cycle of the active part of the impedance matching,maximum efficiency impedance matching can be achieved to ensure the system operating at maximum efficiency point.To meet output voltage control requirement,this paper porposes a decoupling control method to fulfill maximum efficiency tracking and output voltage control requirements.A two degree of freedom control algorithm is put forward accordingly.Finaly,experimental results verify this control method.(2)In order to extend the load variation range under maxiumum efficiency trakcing,this theis proposes a impedance rnage extendtion method by dynaicaaly switching CCM(Continuous Conduction Mode)and DCM(Discontinuous Conduction Mode)operation mode.Without adding any additional circuitry premise,the impedance matching rnage can be effectively extended by running at different operation mode.After analysis shows that by expanding this method can effectively achieve 3 times the original range of matching impedance transformation.(3)This thesis proposed a multi-objective robust control method based on virtual converter.The method uses phase-shifted control in order to achieve the overall control of system,but phase-shifted control is not directly applicable to the integrated control system.To this end,this thesis presents to use the virtual converter to enable efficient robust control system,and establish the connection relationship between the real physical systems and virtual converter phase shift controller.On this basis,establishing a highly efficient multi-objective robust control algorithm to achieve control of integrated system for multiple performance objectives.(4)A method of robust multi-objective optimization efficiency design is proposed for integrated design of multi-objective WPT system.The method takes into account several performance indexes of the system,including a high-gain input and output,power transmission capacity,overall system efficiency,and considering the random fluctuations caused by loosely coupled of the system,and then robust optimization design strategy is given.Based on this method,the design can not only satisfied the design requirements,but also satisfied the requirements of robustness in a certain range to optimize overall performance.(5)To improve the efficiency of the system under the condition of short-time overload,a new method based on double excitation unit is proposed.By using a double excitation unit,not only can it increase the instantaneous power output capacity,while effectively reducing converter the voltage and current stress,but also effectively improve the overall efficiency of the system.In this thesis,the different topologies are compared and analyzed,and then select the optimal power transformation structure.This method can achieve 3 times the power capacity of the original method,and can effectively reduce the voltage and current stress of the systemThe main contribution of this thesis innovation(1)For low efficiency WPT system,a method of maximum efficiency tracking control method based on active impedance matching of the two degrees of freedom is proposed to ensure maximum efficiency of the system and output voltage.On this basis,we propose an active impedance matching method based on CCM and DCM mode switching,which enhance the adaptability of WPT system under the condition of load change.(2)For uncertainty of multi parameter and the problem of low efficiency caused by loose coupling of WPT system,a multi-objective robust control method based on virtual converter is proposed,which solves the problem of phase-shifted converter and integrated controller,to reduce the voltage regulator and improve the efficiency of system.Considering the parameter uncertainty and performance demand,proposes robust H∞ optimal controller design method,which effectively solves the problem of uncertainty of system frequency,coupling coefficient and load.(3)For complex structure design of the WPT system.This thesis presents an integrated design method for the optimal efficiency of the multi performance index.Not only can this method choose the optimal parameters of system according to design requirements,but also can choose the optimal topology structure of the system.And considering the robustness factor from parameter perturbation,the optimal performance of whole system is achieved. |
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