Design of a Cooling System in a Medium Voltage MMC

To dissipate heat effectively, a sufficient cooling system is required for a five-level MMC (Modular Multilevel Converter) based on 10 kV, 100 A power modules. However, achieving efficient heat dissipation necessitates a large cooling system, which in turn reduces the overall power density of the converter. Additionally, ensuring proper insulation between the high voltage switching devices and cooling components poses another challenge. This paper addresses these issues by presenting a detailed numerical design procedure for liquid cooling and selecting appropriate coolant with high dielectric strength. Air cooling with specific clearance and creepage distances is also presented. These two types of cooling methods are compared in terms of thermal performance, size, cost and installation effort. The effectiveness of the design is validated through experimental measurements.