MRI梯度功率放大器硬件系统设计与分析

发布时间：2018-05-09 03:05

  本文选题：梯度功率放大器 + 控制电路设计　； 参考：《电子科技大学》2013年硕士论文

【摘要】：随着医疗水平的不断提高，核磁共振成像设备已经得到广泛应用。目前国内医疗事业正在蓬勃发展，核磁共振成像设备一直依赖进口的状况依然没有改变。我国磁共振设技术水平跟发达国家相比还有很大差距，研制出具有自主知识产权的国产磁共振设备对我国医疗设备技术提高具有重要作用。 梯度功率放大器是磁共振成像系统核心部件之一。随着磁共振成像技术的不断提高，系统对梯度功放的性能提出了更高的要求。梯度功放研究已经进行了多年，相关技术已经逐渐成熟。但是同其他磁共振成像设备部件一样，国内梯度功放设备发展还相对落后。 本文根据需要进行了梯度功率放大器总体方案和关键模块的硬件电路设计、调试。主要设计内容包括： 1、本文根据梯度功率放大器在磁共振成像系统中的作用和主要结构，完成了梯度功率放大器电路设计方案。阐述IGBT门极电容、门极电荷、门极电阻的相关概念与设计要求，IGBT中大功率IGBT驱动模块2SD315A的应用。本文对梯度功率放大器主要执行部件单元（电压源逆变电路）数字控制相关原理和基本算法进行了阐述。 2、本文完成梯度功率放大器电路的数学模型。以电路状态空间表达式为基础，给出带参考输入的线性二次最优调节器设计过程，并使用Simulink对整个梯度功率放大器功能模块进行仿真，验证了梯度功率放大器设计方案合理性与可行性。使用前馈控制算法消除了输出线性稳态误差。使用死区补偿算法消除了死区时间带来的非线性误差。 3、根据IGBT全桥双并联电路和系统控制所需测量信号，给出了梯度功率放大器的控制部分功能框图。详细介绍了TMS320F28335、FPGA和AD7760芯片外围电路设计。同时根据各个模块接口特点完成信号调理电路设计。使用VHDL语言对AD7760采样控制时序进行描述和逻辑设计。同时给出了对四路模数采样数据进行浮点预处理的设计方案，可以充分利用FPGA的资源分担数字信号处理器的工作。本文分析了控制硬件电路印制电路板布局布线和电磁兼容设计方法。 4、硬件调试部分以实际完成硬件电路为平台，，对主要的信号调理电路性能进行调试，设计ModelSim仿真对高精模数采样和浮点处理单元进行仿真验证。使用Quartus II工具SignalTap II逻辑分析仪验证AD7760采样功能，实时观察采样数据波形。最后介绍了梯度功率放大器硬件调试平台，给出了系统调试结果和性能分析。
[Abstract]:With the continuous improvement of medical level, NMR imaging equipment has been widely used. At present, the domestic medical industry is booming, MRI equipment has been dependent on imports of the situation remains unchanged. Compared with the developed countries, the level of magnetic resonance technology in China is still far from that in the developed countries. The development of domestic magnetic resonance equipment with independent intellectual property rights plays an important role in improving the technology of medical equipment in China. Gradient power amplifier is one of the core components of magnetic resonance imaging system. With the continuous improvement of magnetic resonance imaging technology, the performance of gradient power amplifier is required higher. Gradient power amplifier research has been carried out for many years, the related technology has gradually matured. However, like other MRI equipment components, the development of domestic gradient power amplifier equipment is relatively backward. In this paper, the general scheme of gradient power amplifier and the hardware circuit of key modules are designed and debugged according to the need. The main design contents include: 1. According to the function and the main structure of the gradient power amplifier in the magnetic resonance imaging system, the circuit design of the gradient power amplifier is completed. The related concepts and design requirements of IGBT gate capacitance, gate charge and gate resistance are described. In this paper, the principle and basic algorithm of digital control for the main executive unit of the gradient power amplifier (voltage source inverter circuit) are described. 2. The mathematical model of gradient power amplifier circuit is completed in this paper. Based on the expression of circuit state space, the design process of linear quadratic optimal regulator with reference input is given, and the whole function module of gradient power amplifier is simulated by Simulink. The rationality and feasibility of the gradient power amplifier design are verified. The feedforward control algorithm is used to eliminate the output linear steady-state error. The dead-time compensation algorithm is used to eliminate the nonlinear error caused by dead time. 3. According to the measurement signal of IGBT full bridge dual parallel circuit and system control, the control function block diagram of gradient power amplifier is given. The peripheral circuit design of TMS320F28335 FPGA and AD7760 chip is introduced in detail. At the same time, according to the characteristics of each module interface, the design of signal conditioning circuit is completed. The VHDL language is used to describe and design the AD7760 sampling control sequence. At the same time, the design scheme of floating-point preprocessing for four-channel analog-to-digital sampling data is given, which can make full use of the resources of FPGA to share the work of digital signal processor. This paper analyzes the layout, wiring and EMC design method of control hardware circuit printed circuit board. 4. In the hardware debugging part, the performance of the main signal conditioning circuit is debugged on the platform of the actual completed hardware circuit, and the ModelSim simulation is designed to simulate the high-precision analog-to-digital sampling and floating-point processing unit. The Quartus II tool SignalTap II logic analyzer is used to verify the AD7760 sampling function, and the sample data waveform is observed in real time. Finally, the hardware debugging platform of gradient power amplifier is introduced, and the system debugging results and performance analysis are given.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TN722.75

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本文编号：1864276