两种新颖的三相SPWM逆变器死区补偿策略

目的：探索转化生长因子β1（tansforming growth factor-β1，TGF-β1）对人成熟树突状细胞（mature dendritic cells，mDCs）骨架丝状肌动蛋白（filament actin，F-actin）及其部分骨架结合蛋白表达的影响，为深入理解树突状细胞（dendritic cells，DCs）的生物学行为和提高基于DCs的抗肿瘤免疫治疗的临床效率提供线索。方法：不同浓度的TGF-β1处理mDCs后，用激光共聚焦显微镜和免疫印迹实验分别研究细胞骨架F-actin的结构和部分细胞骨架结合蛋白表达水平的变化。结果：（1）与对照组相比，TGF-β1处理后的mDCs的F-actin出现了明显重排，F-actin的表达量在3 ng/ml组下调（P=0.000），在5 ng/ml组上调（P=0.000）。（2）mDCs表面丝状突起长度和数量的变化，长度在3 ng/ml和5 ng/ml组较对照组细、短（P=0.001，0.000）；数量在1、3 ng/ml和5 ng/ml组较对照组少而稀疏（P=0.000）；在7 ng/ml组mDCs表面丝状突起长度和数量的变化均无统计学意义（P=0.114）；通过回归分析细胞丝状突起长度和数量与F-actin表达量之间存在非线性相关性（R2分别为0.828和0.746，P=0.000）。（3）细胞骨架蛋白结合蛋白的表达，fascin1在所有实验组中均出现了下调（P=0.001、0.000）；p-cofilin1与总cofilin1的表达水平比在1 ng/ml和3 ng/ml组均下调（P=0.000）；profilin的表达在1、3 ng/ml和5 ng/ml组均上调（P=0.001、0.001、0.013）。结论：TGF-β1以浓度依赖的方式影响mDCs的细胞骨架F-actin结构及其部分结合蛋白的表达，提示在临床上施行基于DCs的抗肿瘤免疫治疗时，需以适当的方式阻断TGF-β1的信号转导通路，这对进一步深入理解DCs的生物学行为和肿瘤的免疫逃逸机制具有重要意义。

Two Novel Dead Time Compensation Strategies for Three Phase SPWM Inverter

The dead time effect for three phase SPWM inverter will result in voltage distortions, zero current clamping effect, motor speed pulsation, and other bad consequences. By analyzing dead time effect, both theoretical derivation and simulation analysis are carried for the impact of dead time on fundamental wave and harmonics of the output voltage, and the relationship diagrams of the output voltage variation, power factor angle and modulation are obtained. Further, two novel compensation strategies, compensation with reference wave and logic circuits, are proposed in this work. Finally, the experiment is carried on a three phase SPWM inverter, which shows that these two proposed strategies can effectively reduce low harmonics and zero current clamping effect and improve system performance.