Research On Directional Radiation Applied In Microwave Wireless Power Transmitter

The technology of wireless power transmission has gained more and more attentions for its high adaptability to environment and flexibility.And because of lower transmission loss,longer distance as well as higher efficiency,the microwave wireless power transmission solves the problem of power supply on isolated islands and aircrafts.The microwave wireless power transmission system includes two parts:the microwave transmitter and the receiver,the power transmitted by the system is determined directly by the output power of the transmitter’s converter in the transmitter,and the efficiency of the microwave wireless power transmission system,the ability of directional radiation and the efficiency of transmitting antenna electricity to microwave energy can also have influence on one another.Based on this,the thesis researched on the high-powered converter of microwave transmitter and microwave directional radiation to make the microwave wireless power transmission system work efficiently.To increase the output power of the converter,this thesis proposes a Push-Pull resonant inverter based on a ClassΦ₂ inverter.Compared with the single-stage ClassΦ₂ inverter,the former doubles the output power without increasing the voltage stress or current stress of the transistor,which is suitable for high power.To decrease the output harmonics as well as increase the linearity of voltage output and the efficiency of transmitting antenna electricity to microwave energy,the thesis proposes a linear-resonant hybrid converter.It is formed by a linear amplifier in parallel with a resonant inverter at the load end.However,the efficiency of the resonant inverter is high,but the output linearity is poor.Since the working efficiency of the linear amplifier is low despite its high linearity while resonant inverter is on the contrary,we can reasonably design the linear resonant hybrid converter to make the linear amplifier only absorb the output ripple of the resonant inverter,and the active power is provided by the resonant inverter,which makes the converter work at the highest efficiency.To implement directional microwave radiation,we first analyzed the working principle of antenna array in detail and according to it,the output current phase should be controlled by the converter since the antenna can be equivalent to a load of 50Ωfor a power converter.Therefore,this thesis proposes a PLL phase shifter,which is adapt to UHF applications with the advantages that output voltage phase has a linear correlation with its control voltage and voltage phase is continuously adjustable.Finally,a drive circuit of push-pull resonant inverter and linear resonant converter is designed according to the PLL phase shifter and the output voltage phase can be controlled by changing the phase of drive voltage,therefore,the directional radiation of microwave is achieved.The thesis designed a prototype PLL phase shifter,a Push-Pull resonant inverter with 36V DC input,a 50?load and 36W AC output,and a linear-resonant hybrid converter with 30V DC input,a50?load and 10W AC output,both operating at an output frequency of approximately 100MHz.In the end,the theoretical analysis,simulation and experimental results coincide well,verifying the feasibility of the proposed converters and the correction of the designing methods.