高压SVG级联H桥模块等电位研究

Research on Equipotential of High Voltage SVG Cascaded H-bridge Module

高压级联型SVG装置由数个H桥模块级联而成,由于其电压等级、绝缘要求高,H桥模块不接地,处于悬浮状态。IGBT工作会产生大量的热量,因此开关器件衬底需要紧贴散热器表面以更好的散热,但同时也形成了较大的分布电容。散热器受IGBT开关电压和分布电容影响会感应电压,悬浮散热器就相当于电磁辐射源,会产生严重的电磁干扰。本文通过建立H桥模块近场耦合模型,分析了散热器悬浮的危害,并搭建仿真模型进行验证。最后针对散热器悬浮及等电位联结对模块电磁干扰影响的研究,搭建试验平台,通过多维度比较,最终得到散热器直流中点等电位联结为最佳方式。

The high voltage cascadeSVG device is composed of several H-bridge modules and is in suspension due to its high voltage level and insulation requirements as well as ungrouneded H-bridge module.IGBT can,in case of operation,generate a large amount of heat,the substrate of the switching device therefore needs to be close to the surface of the radiator for better heat dissipation,but at the same time,it also forms a large distributed capacitance.The radiator which is affected by IGBT switching voltage and distributed capacitance will induce voltage and the suspension radiator is equivalent to electromagnetic radiation source,which can create serious electromagnetic interference.In this paper,the harm of radiator suspension is analyzed by setting up a near-field coupling model of H-bridge module,and a simulation model is set up for verification.Finally,a test platform is built to study the influence of radiator suspension and equipotential connection on module electromagnetic interference.Through multi-dimensional comparison,it is finally concluded that the equipotential connection at the DC midpoint of radiator was the best way.