| In the field of hydrological survey,the cableway robot is often used to patrol the river section with optical and acoustic sensors.However,the traditional wired charging of cableway robot is easy to corrode and rust in the field environment,which needs frequent maintenance and replacement;Therefore,wireless power transfer(WPT)technology has broad application prospects in this field.At the same time,under the influence of cableway aging or sudden geological disasters,the cableway robot is prone to tilt;if the two-coil structure is adopted,the energy transfer efficiency of the system will decrease sharply due to the change of air gap.Aiming at the charging scene of receiving coil tilt,this paper studies the three-coil WPT system based on relay coil deflection.Firstly,the LCC-S two-coil WPT system and LCC-S-S three-coil WPT system are modeled and analyzed,and the expressions of two-coil efficiency,three-coil efficiency and three-coil resonance conditions are derived;The coil structure is modeled.From the perspective of mutual inductance change,it is concluded that with the inclination of the receiving coil,the mutual inductance between WPT systems gradually decreases,and the system efficiency also decreases.Then,an efficiency optimization method of three-coil WPT system based on relay coil deflection is proposed.Due to the deflection of the relay coil,the mutual inductance between the relay coil and the transmitting coil and the receiving coil will change,resulting in the change of the current of each coil circuit.In this paper,the system loss is analyzed by current ratio.Through analysis and simulation,it is found that: with the deflection of relay coil,the loss proportion of primary resonant inductance circuit and relay coil circuit decreases gradually,while the loss proportion of transmitting coil circuit increases gradually;Therefore,the relay coil has an optimal coupling angle to maximize the efficiency of the three-coil WPT system.Next,according to the simulation,it is found that the optimal coupling angle of relay coil is different under different coupling positions.Therefore,taking the energy transmission distance and the inclination angle of the receiving coil as a reference,this paper proposes a receiving coil positioning method based on the combination of inclination sensor and infrared ranging technology.Finally,the experimental prototype is made and the experimental platform is built.The two-coil WPT system experiment and the three-coil WPT system efficiency optimization experiment are carried out respectively.Under the experimental parameters in this paper,when the receiving coil is tilted by 30 °(the energy transmission distance is 50mm),the efficiency of the two-coil WPT system is reduced by 14.67%;Under this coupling condition,the system efficiency of the three-coil WPT system can reach the best 80.14%,which is13.39% higher than that of the two-coil WPT system.In summary,the efficiency optimization method of three-coil WPT system based on relay coil deflection can effectively improve the system energy transfer efficiency reduced due to the inclination of receiving coil. |
