在此针对LC谐振式双有源桥功率变换器提出一种零回流功率的变频调制方法.该调制方法与传统变频调制方法相比,可完全消除运行过程中的回流功率,有效地降低导通损耗.同时,该调制方法能够保证所有的开关均实现软开关,从而降低了开关损耗.这里在时域中分析了谐振网络在各个开关状态下的谐振电流和谐振电容电压,并进一步推导出能实现零回流功率调制方法所需的占空比和开关频率条件.最后通过1.5 kW的原型机实验验证了此处理论分析的正确性和调制方法的可行性.

在此分析了LCL谐振式双有源桥中的电流谐波,并据此提出了新的控制方法,提高了能量传递效率.首先介绍了传统LCL谐振式双有源桥的控制原理,然后再频域内分析了电流谐波产生的原因和各次电流谐波的幅值,并将其转化为时域表示.基于以上对电流谐波的分析,提出新的软开关控制方法.此方法可以实现全负载域的软开关,并且不会引入回流功率.最后通过实验证明了新控制方法的正确性和有效性.

3D printing is one of hotspots in scientific research and commercial area due to that any products with complex shapes can be rapidly and accurately manufactured. In medical domain,3D printing is used to fabricate medical model,bone,organ and cell. Nowadays three dimension pictures can be achieved with using Computed Tomography(CT)via professional software. However,it is difficult to simulate operation. In this paper we developed a method to prepare transparent vein models using 3D printing. The method was based on patients' CT slice graphs,and a 3D point cloud model and 3D virtual model were firstly designed by software such as MATLAB and CAD,and then two kinds of vein models in different precision degrees were successfully fabricated by 3D printer. The vein models can clearly display the detailed structure of subclavian vein,internal jugular vein and brachiocephalic vein,and would help to simulate operation and promote the method of subclavian vein catheterization. Besides,the method can be easily employed to make other vein model.