基于SiC MOSFETs的三相固态变压器的研究

发布时间：2018-01-10 02:13

本文关键词：基于SiC MOSFETs的三相固态变压器的研究　出处：《山东大学》2017年硕士论文　论文类型：学位论文

【摘要】：在能源互联网的大背景下,固态变压器作为智能电网应用中的关键设备,在未来电力系统中占有重要地位,可以实现电力系统复杂的要求:对环境友好,改变/控制用户电压等级,保持单位功率因数运行,监测能量使用情况并记录信息,提供直流母线等。因为三相模块级联型固态变压器拓扑和控制复杂,需解决模块之间均压均功率等问题,本文采用简单的基于碳化硅器件的三相固态变压器拓扑,其拓扑与控制相对简单,使传统拓扑重新焕发生机,因而具有很强的现实意义。本文介绍了固态变压器相较于传统变压器的优点,从单相、三相以及基于碳化硅器件的固态变压器三个方面概述了固态变压器的研究现状以及工作原理,介绍了随着碳化硅电力电子器件的发展,基于碳化硅器件的固态变压器的优势。本文对所研究SiC-SST系统的三级结构进行了拓扑分析,对其前端整流级及DAB级的电路分析并相应建模。分析了前端整流级电路,建立了前端整流级abc坐标系下的数学模型与dq坐标系下的数学模型,给出了两种模型的转换矩阵;分区间介绍了 DAB级的工作过程,给出了等效漏感电流在各个区间内的表达式,分析了能量传输过程。本文研究了 SiC-SST各级的控制策略,前端整流级采用电流内环和电压外环双闭环控制,其中电流内环采用了具有快速电流响应的直接电流控制策略;中间DAB级采用了单移相控制,推导了其一阶小信号模型以及传递函数表达式,完成了 DAB级电压闭环设计;分析了在电网电压不平衡下SiC-SST系统的控制策略,使用PSIM仿真软件分别对电网电压平衡/不平衡时SiC-SST系统的两种控制策略进行了仿真验证。SiC MOSFET与传统的硅基MOSFET在驱动特性上差异很大,同时如果没有有效的保护或者保护过慢将会影响碳化硅器件使用寿命甚至严重损坏器件。本文分析了碳化硅MOSFET的特性与电路模型,介绍了目前学者对于SiC MOSFET驱动及过流保护电路的研究情况,在已有硅基器件驱动与保护的基础上,提出一种新型高压SiC MOSFET驱动及其过流保护电路,满足了 SiC MOSFET对驱动电压的特殊要求,动作迅速的保护电路在器件过流时能及时有效保护,并对设计的驱动及过流保护电路进行了仿真与实验验证。基于对SiC-SST系统的理论与仿真结果以及SiC MOSFET驱动和过流保护电路,本文选用CREE公司的C2M0080120D碳化硅器件搭建SiC-SST系统的前端整流级实验样机,包括SiC-SST系统的硬件与软件设计,初步完成了对所介绍理论与仿真结果的验证。
[Abstract]:In the context of the energy Internet, solid-state transformer, as the key equipment in the application of smart grid, plays an important role in the future power system. It can meet the complex requirements of the power system: environmentally friendly. Change / control user voltage grade, maintain unit power factor operation, monitor energy usage and record information, provide DC busbar, etc., because of the complex topology and control of three-phase modular cascaded solid-state transformer. In order to solve the problem of the average voltage and average power between modules, this paper adopts a simple topology of three-phase solid-state transformer based on silicon carbide device, its topology and control is relatively simple, which makes the traditional topology revitalized again. This paper introduces the advantages of solid-state transformer compared with the traditional transformer, from the single-phase. The research status and working principle of solid-state transformer are summarized in three aspects, which are three-phase and solid-state transformer based on silicon carbide device. The development of power electronic device based on silicon carbide is introduced. The advantage of solid-state transformer based on silicon carbide device. In this paper, the three-level structure of the studied SiC-SST system is analyzed in topology. The circuit of the front rectifier stage and DAB level are analyzed and the corresponding models are established. The mathematical model of the front end rectifier level abc coordinate system and the dq coordinate system are established. The transformation matrix of two models is given. In this paper, the working process of DAB stage is introduced, the expression of equivalent leakage inductance current in each region is given, and the process of energy transmission is analyzed. The control strategy of SiC-SST level is studied in this paper. The front-end rectifier adopts double closed loop control of current inner loop and voltage outer loop, in which the current inner loop adopts direct current control strategy with fast current response. In the middle DAB stage, the single-phase shift control is used, the first-order small-signal model and the expression of the transfer function are derived, and the closed-loop design of the DAB stage voltage is completed. The control strategy of SiC-SST system under unbalanced voltage is analyzed. Two control strategies of SiC-SST system under voltage balance / unbalance of power network are simulated with PSIM simulation software. Sic is used to verify the control strategy of SiC-SST system. The driving characteristics of MOSFET are very different from those of traditional silicon based MOSFET. At the same time, if there is no effective protection or too slow protection will affect the service life of silicon carbide devices and even seriously damaged devices. This paper analyzes the characteristics and circuit model of silicon carbide MOSFET. This paper introduces the current research situation of SiC MOSFET driver and over-current protection circuit, based on the existing silicon based device drive and protection. A novel high voltage SiC MOSFET driver and its overcurrent protection circuit are proposed, which meet the special requirements of SiC MOSFET for driving voltage. The protection circuit with rapid action can protect the device in time and effectively when the device is overcurrent. Based on the theory and simulation results of SiC-SST system and SiC MOSFET drive and over-current protection circuit, the design of the driver and over-current protection circuit is simulated and verified. In this paper, CREE C2M0080120D silicon carbide device is used to build the front-end rectifier prototype of SiC-SST system, including the hardware and software design of SiC-SST system. The theory and simulation results are preliminarily verified.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM41

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