Research On Wireless Power Supply System Based On Coaxial Coplanar Resolver

Robot is an important technical means to accelerate the "unattended and less manned" industry and agriculture,and to move towards the age of intelligence.The electrical energy transmission between the joints of robots at all levels is mainly by means of cables or mechanical slip rings,and there are safety problems of limited rotational freedom of joints or electric sparks caused by wear and tear.Therefore,Inductive Power Transfer(IPT)technology,which has no direct mechanical connection,high environmental adaptability,flexibility and convenience,is considered as a feasible solution.The rotating wireless power supply system studied in this paper is applied between all levels of robot joints.The rotating transformer is the core part of the wireless power supply system,and the application scenario of the robot joints has strict requirements for it.The rotating transformer must firstly meet the application requirements of compact axial distance,secondly,it must have low overall loss and light weight,meet the electromagnetic compatibility characteristics,and the parameters must remain stable under rotating conditions.The rotating wireless power supply system needs to resonate through the compensation topology to achieve a constant voltage output independent of speed and power.Firstly,based on the design principles of rotating transformer,a coaxial coplanar rotating transformer is proposed for the application of robot joints and the problems of existing rotating transformers.By means of finite element simulation software,the wire gauge of the coil winding is selected,and the arrangement and number of ferrite cores of the primary and secondary coils are optimized.Then the designed coaxial coplanar resolver is tested for rotational performance to determine the resolver parameters.Then,based on the power supply characteristics of the motor module in the robot rotating joint,a constant voltage output is achieved by resonating through the compensation topology.A method of analysis applicable to any higher-order compensation is used to achieve the goal of constant voltage output.A suitable compensation topology is selected to achieve constant voltage output on the basis of ensuring a simple structure.Equivalent calculations are performed for the resonant cavity circuit to obtain the parameters of the compensation elements and verify them by simulation;the mathematical model of the efficiency of the AC-AC side of the resonant cavity is obtained by considering the parasitic resistance values of the rotating transformer coil and each compensation element in the compensation topology.Finally,an LCR tester is used to measure the parameters of the developed coaxial coplanar resolver.A rotating transformer test structure is proposed to test the output characteristics of the coaxial coplanar non-contact rotating transformer under different rotating operating conditions.The hardware circuit of the rotating wireless power supply system is designed,and the experimental platform of the rotating wireless power supply system is built to verify the accuracy of the theoretical analysis.The designed rotating wireless power supply system is applied in a robotic arm robot to supply 48 V constant voltage to the motor module.In this paper,a coaxial coplanar resolver is proposed for the application scenario of robot joints and optimized according to the size and power requirements.The coaxial coplanar resolver has an axial dimension of only 5.5 mm,a small overall weight,and can achieve a rated output of 48 V and 2.4A.For the rotating wireless power supply system,an analysis method applicable to arbitrary high-order compensation is used to achieve the goal of constant voltage output;the practicality of the rotating wireless power supply system is verified by applying it in a robotic arm,and the maximum system efficiency can reach 90%.This paper provides theoretical support and scientific guidance for the rotary wireless power supply system to replace the traditional power supply method between robot joints.