Research On Wireless Transmission Technology Of Medical CT Machine

The medical CT machine system consists of a rotating scanning part and a fixed power supply part.Based on the needs of the medical CT machine for instantaneous high power stable output and long-term low power reliable output,and aiming at the problems of signal noise and contact resistance instability of the contact slip ring and brush of the rotating part,a multi-terminal magnetic coupling wireless transmission model of multi-coil series and multi-coil parallel is proposed in this paper.The maximum power tracking network and multi-coil current equalization method are established,and the wireless transmission experiment platform is built.Firstly,the end-face magnetic coupling structure based on multiple coil pairs is proposed.The loosely coupled transformers based on "U" shape single terminal magnetic coupling structure,"E" shape double terminal magnetic coupling structure and "UE" shape three terminal magnetic coupling structure are explored.The electromagnetic coupling simulation model was established,and the electromagnetic coupling mechanism was analyzed from the perspectives of magnetic circuit,mutual inductance and coil connection mode.The finite element simulation and theoretical calculation were carried out on the COMSOL cloud platform,and the feasibility of the multi-terminal structure for high power wireless transmission was verified.Secondly,a multi-input multi-output inductive contactless power transfer(MIMO-ICPT)model is established.The transmission performance of MIMO-ICPT system based on "E" shape and "UE" shape magnetic coupling structure is explored under resonant state.The theoretical analysis and simulation verify that the optimal magnetic coupling structure is "E" shape.The multi-coil series MIMO-ICPT resonant model is analyzed and verified to have good transmission performance and fault resistance.In addition,a multi-coil parallel MIMO-ICPT resonance model suitable for reliable output of long duration medical CT is proposed,and a distributed capacitor compensation current equalization method is proposed to eliminate the difference in coil current,and its effectiveness is verified by simulation.Thirdly,the impedance matching and maximum power tracking network of the MIMO-ICPT system is constructed.The perturbation observation method based on the adaptive change of the perturbation step size according to the output power and the particle swarm optimization algorithm combined with future Newton momentum are proposed.In the case of impedance mismatch caused by changes in load or other parameters,the power gain of the impedance matching network is taken as the objective function,and the maximum power output state under resonant state is achieved by adjusting the duty ratio of DC/DC converter to the optimal value.Finally,the SISO/MIMO-ICPT transmission experimental research platform was built,the experimental method of parameter measurement was studied,and the selfinductance and mutual inductance parameters of multi-coil were measured.The transmission characteristics experiments of the SISO-ICPT system and the multi-coil series MIMO-ICPT system and the distributed capacitance compensation method of the multi-coil parallel MIMO-ICPT system are completed,and the effectiveness of the proposed model and method is verified.