Design And Analysis Of Magnetic Stimulation System By Coil Array

Noninvasive brain stimulation techniques have been widely used for studying thebrain function and have been one of the effective methods of treating neuropsychiatricdisorders where the early diagosis play a great role in. However, the objective andquantitative parameters is currently lacked. Therefore, this paper proposes a new ideathat combinating controllable transcranial magnetic stimulation and brain functionimaging techniques to achieve quantitative brain function parameters.Based on the idea of system identification, this paper first proposed coil arraymagnetic stimulation which has the characteristic of low-intensity magnetic ifeld,stimulate regional variable, parameters adjustable combine with the EEG brainfunction detecting platform. This platform make magnetic stimulation as an input andEEG as a output, make up a detecting and analysis system of researching function ofcerebrum. This paper comes up with the overall design scheme of this magneticstimulation system, which including upper system, control circuit, the mainstimulating circuit et al.Based on the mechanism of Electromagnetic stimulation can effect on the brainelectrical activity, By using ANSYS sotfware, this paper analyzed distribution ofinduced electromagnetic field in the head of coil array magnetic stimulation produced.From the amplitude of stimulus current, the change in time of stimulus current, thedirection of stimulus current, the different combination forms of activating coils thisfour aspect, proceeding electromagnetic simulation in detail and analyzing thesimulation results. Through analyzing, this paper proved coil array can realize manystimulating forms such as single circular coil, horoscope coil, coil array and so on.Stimulating area is able to achieve the whole brain or the regions of interest, whichcan meet the requirements of a variety of experiments.According to the requirement of the detection system stimulation, in this paper,we designed the control system of coil array, to realize the stimulus current variable,stimulus magnetic ifeld adjustable and stimulate coil controllable and other functions.To the part of stimulus current output, designed the whole bridge circuit that based onIGBT control switches, which can generate a one-way, two-way, clusters pulsedcurrent waveform. In order to achieve the stimulus magnetic field adjustable this paper adopted step-down/up DC-DC converter with voltage loop compensation, which can automatically adjust the output voltage according to the magnetic field strength, to produce different intensity of stimulating electromagnetic field. Finally aiming at stimulating coil controllable, we puted forward the control scheme based on bidirectional thyristor and photoelectric coupler. For the above designs, circuit simulation results were given.In this paper, the design of coil array magnetic stimulation system provides the detecting of brain function and diagnosis of mental illness early a new stimulus package.