学术报告第170期—张鸿淇 陈曦璇论文投稿报告

时间：2022年7月7日 周四 14:30

地点：313会议室

报告人：张鸿淇 研究生

负责导师：马少翔 副教授

拟投期刊：IEEE Transactions on Power Electronics

题目：A modular multilevel dc active filter with low switching frequency based on optimal parameter design

摘要：In this paper, a dc active power filter based on modular multilevel converter scheme (MMC-DAPF) for the acceleration grid power supply (AGPS) in fusion engineering is proposed to reduce the dc bus voltage ripple of AGPS and improve the heating efficiency. Compared with multiple DAPFs connected in parallel to the dc bus, this scheme has a smaller total power capacity and is more suitable for high-power applications with rich ripple frequencies. In addition, the scheme is special in that each module can compensate the ripple current of one frequency component, and the maximum switching frequency is not more than 4 times the ripple frequency. The electrical parameters of all DAPF modules (switching states and module capacitance voltages) are optimal values obtained through traversal calculation and condition screening. According to the calculation process, two types of APF modules are distinguished. They have different switching frequencies and ripple suppression effects to adapt to different occasions. The optimal parameter algorithms for two kinds of DAPF are introduced. The simulation results show that each module can reduce the relative frequency component of the ripple by about 80% under the optimal parameters. Similar results are obtained by the 400V AGPS prototype and 20V DAPF prototype. Because of the low switching frequency, this scheme can improve the power capacity of a single module, greatly reduce the number of modules of MMC and simplify the circuit of DAPF.

报告人：陈曦璇 研究生

负责导师：夏冬辉 副教授

拟投期刊：Fusion Engineering and Design

题目：Synthesis of two Quasi-Optical Polarizers for the Multi-Frequency High-Power Millimeter Wave System

摘要：Millimeter wave systems based on powerful gyrotron can deliver megawatt microwave power, which is an important auxiliary heating method for magnetic confinement fusion devices. Reflective gratings are normally used as the quasi-optical polarizers for polarization control of the wave in such systems. Based on the coordinate transformation method, we developed a numerical code to study the broadband polarization strategy. By considering the synthesis of two polarizers, we designed a pair of polarizers in the W band. Calculation results indicated that almost arbitrary polarization can be achieved in a wide frequency range. To verify the design, we set up a test platform and experiments were carried out. The performance of the polarizers was tested from 80GHz to 105GHz with a step of 5GHz. The test results agreed well with the numerical results, indicating that the design is reasonable. With the development of multi-frequency gyrotrons, the study in this paper can be used as a reference for design of broadband polarizers of the multi-frequency millimeter wave systems.