Hardware System Design And Analysis Of MRI Gradient Power Amplifier

With the rapid development of modern medical, MRI (Magnetic ResonanceImaging) equipment has been widely used. The domestic medical industry is booming,the condition that magnetic resonance imaging equipment dependent on imports has notchanged. In terms of per capita number of magnetic resonance equipment there is a biggap between developed countries and our country, which mainly caused by foreignmonopoly of magnetic resonance equipment technology. Developing the domesticmagnetic resonance equipment with independent intellectual property rights has becomean important role in our medical level.Gradient power amplifier is the core component of the MRI imaging system. WithMRI imaging technology continues to improve, higher requirements on the the gradientamplifier’s performance is expected. Gradient amplifier reserarchs have been conductfor many years, and related technologies have being matured. But the same as otherMRI parts, gradient amplifier technology rests in the hands of foreign enterprises anddomestic gradient amplifier equipment has been monopolized by foreign companies.Some domestic research has reached the international level, but has not really beenapplied.According to the performance indicators of the company’s project requirements,we design the overall scheme of the gradient power amplifier. Designs include thefollowing:1、IGBT topology of the gradient amplifier is the main components of powerelectrical.Design constitutes double parallel full-bridge circuit using CM600DU-24NFHIGBT and selectes2SD315A module as the IGBT switch control drive. Integratedfeature of2SD315A module greatly facilitates circuit design.2、In this paper,we completed the gradient power amplifier circuit modeling. Basedon the circuit state space expression, we designed Linear Quadratic Optimal Regulatorwith reference input.Using MATLAB/Simulink to simulink entire gradient poweramplifier and verify the rationality and feasibility of gradient poweramplifier.Feedforward control algorithm eliminates the output linear steady-state error.Using dead-time compensation algorithm eliminates the nolinaear error.3、Acording to the measurement signal required for IGBT full bridge parallelcircuit control,we give gradient power amplifier’s control part block digram anddetailed the TMS320F28335, FPGA, AD7760chip peripheral circuit design.Completesignal conditioning circuit design according to the characteristics of each moduleinterface. Using VHDL language design AD7760sampling control timing sequence。Four A/D sampling data floating-point pretreatment design can take advantage of theresources of FPGA.The control hardware printed circuit board layout andelectromagnetic compatibility design were analyzed in this paper.4、Using platform of hardware circuit to debug the signal conditioning circuitperformance.Simulinking Modelsim simulations of the A/D sampling and floating-pointprocess unit.Using Quartus II tool SignalTap II online simulate AD7760samplingfuction and observe the sampled data waveform.Also describes the gradient poweramplifier hardware debugging platform, system debugging and performance analysis.