40T混合磁体外超导磁体电源的开关电源方案研究与设计
发布时间：2018-11-22 07:53
【摘要】：中科院强磁场中心的40T稳态强磁场装置的磁体由内水冷磁体和外超导磁体两部分组成,其中的外超导磁体需要一个最大输出8V/16KA的电源,且对电流和电压的稳定度有很高的要求。超导磁体电源目前采用的是传统的双反星形可控硅整流方案,该方案最主要缺点是设备体积很大。另一种备选方案是基于开关电源设计,一般而言,高频开关电源具有更小的体积且容易做到更高的效率,但仅靠LC滤波难以滤除开关电源前级三相不可控整流带来的低频纹波,且电源无法输出负电压用于使磁体电流可控下降。 论文第2章首先介绍了各种逆变电路和整流电路并结合超导磁体电源的需求选择了原边全桥逆变加副边全波整流作为电源主回路的基本拓扑。为了降低损耗,在基本拓扑的基础上采用了原边串联饱和电感的移相全桥软开关技术和副边的同步整流技术。在第2章的最后给出了磁体电源的总拓扑并简要描述了拟采用的失超保护方案。接着的第3章对主拓扑各参数进行了计算。 为了更好地减小输出纹波,在开关变换器的输出端添加了有源滤波装置。论文第4章首先介绍了各种直流有源滤波器,然后重点分析了超导磁体电源选用串联线性有源滤波的原因。其中一个核心原因是将串联线性有源滤波与同步整流电路相结合,并通过恰当的控制方式,可以使电源输出负电压。在第4章的最后对串联线性有源滤波中MOSFET调整管的导通内阻调整能力进行了具体分析。 论文第5章首先给出了将有源滤波环节的控制系统和开关变换器环节的控制系统联系起来使其可以协同工作的总体控制方案。对于有源滤波环节的反馈控制系统,在电路建模的基础上,结合波特图设计了电压内环电流外环的双闭环控制系统；对于开关变换器环节的控制系统,在考虑了调整管导通电阻对开环传递函数的影响的基础上,基于第2章中的主拓扑建模结论演化后给出了具体的PID补偿网络设计方法。在第5章的最后简要介绍了开关变换器环节也可以采用的峰值电流控制方式。 为了验证前述章节中磁体电源主回路和控制回路设计的正确性,在第6章中设计了一个样机电源并给出了开关变换器软开关效果的仿真验证结果、直流有源滤波器环节滤波效果的仿真验证结果和整体控制系统的动态响应效果仿真验证结果,最后给出了样机实验测试结果。仿真和实验测试结果表明整体控制方案中的两个反馈控制环节协同工作良好,电源输出稳定度很高。 论文的第7章对全文完成的工作进行了总结,并提出了对后续研究的展望。
[Abstract]:The magnet of the 40T steady-state strong magnetic field device in the center of the strong magnetic field of the Chinese Academy of Sciences consists of two parts: the inner water-cooled magnet and the outer superconducting magnet, among which the external superconducting magnet needs a power source with the maximum output of 8V/16KA. The stability of current and voltage is very high. At present, the superconducting magnet power supply adopts the traditional double inverse star SCR rectifier. The main disadvantage of this scheme is the large size of the equipment. Another alternative is based on the switching power supply design. Generally speaking, the high frequency switching power supply is smaller in volume and easier to achieve higher efficiency, but it is difficult to filter the low frequency ripple caused by the three-phase uncontrollable rectifier in the front stage of the switching power supply by LC filtering alone. And the power supply can not output the negative voltage to make the magnets current controllable descent. In chapter 2, various inverter circuits and rectifier circuits are introduced firstly. Combined with the demand of superconducting magnet power supply, the primary full-bridge inverter plus auxiliary full-wave rectifier is selected as the basic topology of the main circuit of the power supply. In order to reduce the loss, the phase-shifted full-bridge soft switching technology of the primary edge series saturated inductor and the synchronous rectifying technology of the auxiliary edge are adopted on the basis of the basic topology. At the end of chapter 2, the total topology of the magnet power supply is given, and the proposed scheme is briefly described. Then the main topology parameters are calculated in Chapter 3. In order to reduce the output ripple, an active filter is added to the output of the converter. In chapter 4, we first introduce various DC active filters, and then analyze the reason why series linear active filter is used in superconducting magnet power supply. One of the key reasons is that the series linear active filter is combined with the synchronous rectifier circuit and the output negative voltage of the power supply can be made by proper control mode. At the end of chapter 4, the on resistance adjustment ability of MOSFET regulator in series linear active filter is analyzed in detail. In chapter 5, a general control scheme is presented, which combines the active filter control system and the switching converter control system to make it work together. For the feedback control system of active filter link, based on the circuit modeling, a double closed loop control system with voltage inner loop, current outer loop and external loop is designed. For the control system of switching converter, based on the evolution of the main topology modeling conclusion in Chapter 2, a concrete design method of PID compensation network is given after considering the effect of adjusting on-resistance on open-loop transfer function. At the end of chapter 5, the peak current control mode of switching converter is introduced briefly. In order to verify the correctness of the design of the main circuit and the control circuit of the magnet power supply in the previous chapters, a prototype power supply is designed in Chapter 6, and the simulation results of the soft-switching effect of the switching converter are given. The simulation results of the filter effect of DC active power filter and the dynamic response of the whole control system are verified. Finally, the experimental results of the prototype are given. Simulation and experimental results show that the two feedback control links work well in the overall control scheme, and the output stability of the power supply is very high. Chapter 7 summarizes the work done in this paper, and puts forward the prospect of further research.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM46
本文编号：2348579
[Abstract]:The magnet of the 40T steady-state strong magnetic field device in the center of the strong magnetic field of the Chinese Academy of Sciences consists of two parts: the inner water-cooled magnet and the outer superconducting magnet, among which the external superconducting magnet needs a power source with the maximum output of 8V/16KA. The stability of current and voltage is very high. At present, the superconducting magnet power supply adopts the traditional double inverse star SCR rectifier. The main disadvantage of this scheme is the large size of the equipment. Another alternative is based on the switching power supply design. Generally speaking, the high frequency switching power supply is smaller in volume and easier to achieve higher efficiency, but it is difficult to filter the low frequency ripple caused by the three-phase uncontrollable rectifier in the front stage of the switching power supply by LC filtering alone. And the power supply can not output the negative voltage to make the magnets current controllable descent. In chapter 2, various inverter circuits and rectifier circuits are introduced firstly. Combined with the demand of superconducting magnet power supply, the primary full-bridge inverter plus auxiliary full-wave rectifier is selected as the basic topology of the main circuit of the power supply. In order to reduce the loss, the phase-shifted full-bridge soft switching technology of the primary edge series saturated inductor and the synchronous rectifying technology of the auxiliary edge are adopted on the basis of the basic topology. At the end of chapter 2, the total topology of the magnet power supply is given, and the proposed scheme is briefly described. Then the main topology parameters are calculated in Chapter 3. In order to reduce the output ripple, an active filter is added to the output of the converter. In chapter 4, we first introduce various DC active filters, and then analyze the reason why series linear active filter is used in superconducting magnet power supply. One of the key reasons is that the series linear active filter is combined with the synchronous rectifier circuit and the output negative voltage of the power supply can be made by proper control mode. At the end of chapter 4, the on resistance adjustment ability of MOSFET regulator in series linear active filter is analyzed in detail. In chapter 5, a general control scheme is presented, which combines the active filter control system and the switching converter control system to make it work together. For the feedback control system of active filter link, based on the circuit modeling, a double closed loop control system with voltage inner loop, current outer loop and external loop is designed. For the control system of switching converter, based on the evolution of the main topology modeling conclusion in Chapter 2, a concrete design method of PID compensation network is given after considering the effect of adjusting on-resistance on open-loop transfer function. At the end of chapter 5, the peak current control mode of switching converter is introduced briefly. In order to verify the correctness of the design of the main circuit and the control circuit of the magnet power supply in the previous chapters, a prototype power supply is designed in Chapter 6, and the simulation results of the soft-switching effect of the switching converter are given. The simulation results of the filter effect of DC active power filter and the dynamic response of the whole control system are verified. Finally, the experimental results of the prototype are given. Simulation and experimental results show that the two feedback control links work well in the overall control scheme, and the output stability of the power supply is very high. Chapter 7 summarizes the work done in this paper, and puts forward the prospect of further research.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM46
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