Design Of Closed Loop Wireless Power Supply System With Optimal Resonant Point Control

The power transmission technology has made rapid progress in modern times,but the use of electric energy does not get rid of the dependence on transmission cables in most occasions.Frequent insertion and removal of complicated power lines has problems such as friction and aging.Therefore,as a new type of non-contact power transmission technology,wireless power supply technology has got rid of the dependence on traditional transmission cables,and has been researched and developed for many years.Now it has gradually begun to be applied in the civilian electronics industry,electric vehicle charging,etc.aspect.At present,most of the radio energy transmission fields mainly do a lot of research on high-power,high-efficiency,long-distance transmission,and the focus is on the transmission of energy.In the face of most industrial and commercial applications,wireless power systems are required to provide a stable output voltage and the highest possible transmission efficiency.However,the power output of the wireless power supply system is difficult to stabilize due to changes in load characteristics,transmission distance,and position of the coupling coil.In order to make the wireless power supply system produce stable and efficient power output,this paper proposes a closed-loop control method to make the system work at its own resonance point to achieve stable power output.The main research contents of this paper include the following aspects:(1)Introduce the transmission mode(electromagnetic coupling,magnetic resonance,radio wave)of wireless power supply,and analyze the principle and characteristics of various methods.Because of the application scenarios with short distance and low power,the electromagnetic coupling type is selected as the research object.(2)Establishing a mathematical model through electromagnetic coupling theory,theoretically analyzing and verifying four coupled vibration models of series wireless power transmission(series-series,series-parallel,parallel-series,parallel-parallel),and analyzing the models of each model.Circuit characteristics and energy efficiency characteristics.(3)For the drive design of the resonant network,based on the principle of voltsecond balance,the drive design of a single MOS tube is used to simplify the common full-bridge inverter drive,making the system more controllable.(4)Based on the coupling model of parallel resonance,two circuit topologies of radio energy transmission are designed.Multisim is used to simulate the system,and the influence of the power receiving end on the transmitting end due to coupled resonance and the optimal system are obtained.The resonance point was analyzed in detail.(5)For the characteristics of current-type resonance,this paper establishes the information transmission between the transmitting end and the receiving end through Bluetooth.The current feedback is used at the transmitting end,and the voltage feedback at the receiving end is used as the input of the controller to establish a closed loop of the system.Through the step-by-step optimization algorithm,the driving of the resonant network of the transmitting end is controlled,so that the system works at the resonance point.(6)Through the production of hardware,the experimental environment was built,and the foreign object detection function for wireless energy transmission was realized.The load condition and the no-load condition of the system are tested separately.The experimental results show that the system can work at its own optimal resonance point through closed-loop control,keeping the 5V voltage output stable and up to 81% efficiency.In summary,this paper through the derivation and analysis of the mathematical model of the wireless power supply system,the design and debugging of the system circuit topology,and then the test of the experimental system,finally verified that through the closed-loop control,the wireless power supply system can achieve a stable voltage output and High-efficiency energy conversion lays a theoretical foundation for the research of subsequent wireless power supply systems.